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Balbinotti V, Menezes MGA, Silva AM, Ferreira FNA, Peripolli V, Pilati C, Bianchi I, Schwegler E, Moreira F. Effect of glycoelectrolytic supplement on post-weaning piglet performance and intestinal integrity. Trop Anim Health Prod 2023; 55:418. [PMID: 37996717 DOI: 10.1007/s11250-023-03826-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 11/07/2023] [Indexed: 11/25/2023]
Abstract
This study evaluated the effects of glycoelectrolytic supplements on the performance, blood parameters, and intestinal morphology of piglets during the post-weaning period. In the study, a total of 240 piglets weaned aged 17 22.60 + 1.10 days were used. The control group (n = 120) received only water, and the treatment group (n = 120) received an oral glycoelectrolytic supplement diluted in water (0.75%) during the first three days after weaning. Feed intake, daily weight gain, final weight, feed conversion ratio, and post-weaning mortality were evaluated. On the third day after weaning, the blood glucose levels of all piglets were analyzed. Blood was collected from 12 piglets from each treatment group on day 3 after weaning for blood count analysis, and intestinal fragments were collected for anatomopathological and morphometric evaluation. Better feed conversion ratio (1.29) and higher consumption of liquids (0.639 L/day) were observed in the piglet group supplemented with glycoelectrolytes on day 3 after weaning (P < 0.05). The supplemented group presented a higher glycemic index (80.78 mg/dL), average corpuscular volume (67.35 fL), and average corpuscular hemoglobin (20.46 pg) than the control group (P < 0.05). The evaluation of intestinal integrity and the probability of diarrhea occurrence were similar between the groups (P > 0.05). Oral glycoelectrolytic supplementation can be an option for piglets immediately after weaning as it improves feed conversion and consumption of liquids, in addition to increasing blood glucose without the occurrence of diarrhea, thus reducing dehydration and energy deficit.
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Affiliation(s)
- V Balbinotti
- Pós-Graduação Em Produção E Sanidade Animal, Instituto Federal Catarinense, Campus Araquari, Araquari, SC, 89.245-000, Brazil
- Agroceres Multimix Nutrição Animal LTDA, Rio Claro, SP, 13.502-741, Brazil
| | - M G A Menezes
- Núcleo de Extensão, Ensino E Pesquisa Em Produção Animal, Faculdade de Veterinária, Instituto Federal Catarinense, Campus Araquari, Araquari, Brazil
| | - A M Silva
- Agroceres Multimix Nutrição Animal LTDA, Rio Claro, SP, 13.502-741, Brazil
| | - F N A Ferreira
- Agroceres Multimix Nutrição Animal LTDA, Rio Claro, SP, 13.502-741, Brazil
| | - V Peripolli
- Núcleo de Extensão, Ensino E Pesquisa Em Produção Animal, Faculdade de Veterinária, Instituto Federal Catarinense, Campus Araquari, Araquari, Brazil
| | - C Pilati
- Centro de Ciências Agroveterinárias, Lages, SC, 88.520-000, Brazil
| | - I Bianchi
- Núcleo de Extensão, Ensino E Pesquisa Em Produção Animal, Faculdade de Veterinária, Instituto Federal Catarinense, Campus Araquari, Araquari, Brazil
| | - E Schwegler
- Núcleo de Extensão, Ensino E Pesquisa Em Produção Animal, Faculdade de Veterinária, Instituto Federal Catarinense, Campus Araquari, Araquari, Brazil
| | - F Moreira
- Núcleo de Extensão, Ensino E Pesquisa Em Produção Animal, Faculdade de Veterinária, Instituto Federal Catarinense, Campus Araquari, Araquari, Brazil.
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Schwegler E, Bachmann M, Kube F, Eriksson U. Gender-specific differences in comorbidities, in-hospital complications and outcomes in emergency patients with ethanol intoxication with and without multisubstance use. Swiss Med Wkly 2023; 153:40061. [PMID: 37155832 DOI: 10.57187/smw.2023.40061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/10/2023] Open
Abstract
AIMS OF THE STUDY To analyse gender-specific differences in comorbidities, multisubstance abuse, in-hospital complications, intensive care unit transfers and referrals to psychiatric wards of emergency department patients with ethanol intoxication. Several lines of evidence suggest an influence of gender differences on diagnostic and therapeutic approaches to various diseases. METHODS Over a period of 7 years, all patients with signs or symptoms of ethanol intoxication and a positive blood ethanol test admitted for the first time to the emergency department of a Swiss regional tertiary referral hospital were prospectively enrolled. Patients were categorised into two subgroups: patients without additional drug use were considered ethanol-only cases, whereas patients who had also ingested other substances (as determined from bystanders, physicians and urine drug screening) were considered multisubstance cases. A retrospective analysis of this database evaluated gender-specific differences in comorbidities, multisubstance abuse, in-hospital complications, intensive care unit transfers and referrals to psychiatric wards within these two subgroups. Statistical analysis included Fisher's exact test for categorical data and Wilcoxon rank sum test for continuous data. RESULTS Of 409 enrolled patients, 236 cases were ethanol-only and 173 were multisubstance cases. The three most common comorbidities in multisubstance patients showed significant gender differences: psychiatric disorders (43% males vs 61% females; p = 0.022), chronic ethanol abuse (55% males vs 32% females; p = 0.002) and drug addiction (44% males vs 17% females; p = 0.001). Gender differences were also found for the most frequently co-ingested substances: benzodiazepines (35% males vs 43% females; p = 0.014), cannabis (45% males vs 24% females; p = 0.006) and cocaine (24% males vs 6% females; p = 0.001). Male and female ethanol-only patients were transferred to the intensive care unit in 8% of cases. In multisubstance cases, 32% of male and 43% of female patients were transferred to the intensive care unit (no significant gender difference). The psychiatric ward referral rate in male (30%) and female (48%) patients with multisubstance abuse was significantly different (p = 0.028). No significant gender difference in psychiatric ward referral rates was observed for ethanol-only patients (12% males, 17% females). CONCLUSION Among emergency department patients admitted with ethanol intoxication, gender differences in comorbidities, substance use and psychiatric ward referrals were highly significant among patients who presented with multisubstance abuse. Rates of intensive care unit transfer for patients with ethanol intoxication are substantial for both genders, reflecting relevant disease burden and resource demand, as well as the need for further preventive efforts.
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Affiliation(s)
- Eric Schwegler
- Department of Medicine, GZO Regional Health Center, Wetzikon, Switzerland
| | - Marta Bachmann
- Department of Medicine, GZO Regional Health Center, Wetzikon, Switzerland
| | - Frank Kube
- Emergency Department, GZO Regional Health Center, Wetzikon, Switzerland
| | - Urs Eriksson
- Department of Medicine, GZO Regional Health Center, Wetzikon, Switzerland
- University of Zurich, Zürich, Switzerland
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Aluru NR, Aydin F, Bazant MZ, Blankschtein D, Brozena AH, de Souza JP, Elimelech M, Faucher S, Fourkas JT, Koman VB, Kuehne M, Kulik HJ, Li HK, Li Y, Li Z, Majumdar A, Martis J, Misra RP, Noy A, Pham TA, Qu H, Rayabharam A, Reed MA, Ritt CL, Schwegler E, Siwy Z, Strano MS, Wang Y, Yao YC, Zhan C, Zhang Z. Fluids and Electrolytes under Confinement in Single-Digit Nanopores. Chem Rev 2023; 123:2737-2831. [PMID: 36898130 PMCID: PMC10037271 DOI: 10.1021/acs.chemrev.2c00155] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/12/2023]
Abstract
Confined fluids and electrolyte solutions in nanopores exhibit rich and surprising physics and chemistry that impact the mass transport and energy efficiency in many important natural systems and industrial applications. Existing theories often fail to predict the exotic effects observed in the narrowest of such pores, called single-digit nanopores (SDNs), which have diameters or conduit widths of less than 10 nm, and have only recently become accessible for experimental measurements. What SDNs reveal has been surprising, including a rapidly increasing number of examples such as extraordinarily fast water transport, distorted fluid-phase boundaries, strong ion-correlation and quantum effects, and dielectric anomalies that are not observed in larger pores. Exploiting these effects presents myriad opportunities in both basic and applied research that stand to impact a host of new technologies at the water-energy nexus, from new membranes for precise separations and water purification to new gas permeable materials for water electrolyzers and energy-storage devices. SDNs also present unique opportunities to achieve ultrasensitive and selective chemical sensing at the single-ion and single-molecule limit. In this review article, we summarize the progress on nanofluidics of SDNs, with a focus on the confinement effects that arise in these extremely narrow nanopores. The recent development of precision model systems, transformative experimental tools, and multiscale theories that have played enabling roles in advancing this frontier are reviewed. We also identify new knowledge gaps in our understanding of nanofluidic transport and provide an outlook for the future challenges and opportunities at this rapidly advancing frontier.
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Affiliation(s)
- Narayana R Aluru
- Oden Institute for Computational Engineering and Sciences, Walker Department of Mechanical Engineering, The University of Texas at Austin, Austin, 78712TexasUnited States
| | - Fikret Aydin
- Materials Science Division, Physical and Life Science Directorate, Lawrence Livermore National Laboratory, Livermore, California94550, United States
| | - Martin Z Bazant
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts02139, United States
- Department of Mathematics, Massachusetts Institute of Technology, Cambridge, Massachusetts02139, United States
| | - Daniel Blankschtein
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts02139, United States
| | - Alexandra H Brozena
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland20742, United States
| | - J Pedro de Souza
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts02139, United States
| | - Menachem Elimelech
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut06520-8286, United States
| | - Samuel Faucher
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts02139, United States
| | - John T Fourkas
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland20742, United States
- Institute for Physical Science and Technology, University of Maryland, College Park, Maryland20742, United States
- Maryland NanoCenter, University of Maryland, College Park, Maryland20742, United States
| | - Volodymyr B Koman
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts02139, United States
| | - Matthias Kuehne
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts02139, United States
| | - Heather J Kulik
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts02139, United States
| | - Hao-Kun Li
- Department of Mechanical Engineering, Stanford University, Stanford, California94305, United States
| | - Yuhao Li
- Materials Science Division, Physical and Life Science Directorate, Lawrence Livermore National Laboratory, Livermore, California94550, United States
| | - Zhongwu Li
- Materials Science Division, Physical and Life Science Directorate, Lawrence Livermore National Laboratory, Livermore, California94550, United States
| | - Arun Majumdar
- Department of Mechanical Engineering, Stanford University, Stanford, California94305, United States
| | - Joel Martis
- Department of Mechanical Engineering, Stanford University, Stanford, California94305, United States
| | - Rahul Prasanna Misra
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts02139, United States
| | - Aleksandr Noy
- Materials Science Division, Physical and Life Science Directorate, Lawrence Livermore National Laboratory, Livermore, California94550, United States
- School of Natural Sciences, University of California Merced, Merced, California95344, United States
| | - Tuan Anh Pham
- Materials Science Division, Physical and Life Science Directorate, Lawrence Livermore National Laboratory, Livermore, California94550, United States
| | - Haoran Qu
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland20742, United States
| | - Archith Rayabharam
- Oden Institute for Computational Engineering and Sciences, Walker Department of Mechanical Engineering, The University of Texas at Austin, Austin, 78712TexasUnited States
| | - Mark A Reed
- Department of Electrical Engineering, Yale University, 15 Prospect Street, New Haven, Connecticut06520, United States
| | - Cody L Ritt
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut06520-8286, United States
| | - Eric Schwegler
- Materials Science Division, Physical and Life Science Directorate, Lawrence Livermore National Laboratory, Livermore, California94550, United States
| | - Zuzanna Siwy
- Department of Physics and Astronomy, Department of Chemistry, Department of Biomedical Engineering, University of California, Irvine, Irvine92697, United States
| | - Michael S Strano
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts02139, United States
| | - YuHuang Wang
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland20742, United States
- Maryland NanoCenter, University of Maryland, College Park, Maryland20742, United States
| | - Yun-Chiao Yao
- Materials Science Division, Physical and Life Science Directorate, Lawrence Livermore National Laboratory, Livermore, California94550, United States
- School of Natural Sciences, University of California Merced, Merced, California95344, United States
| | - Cheng Zhan
- Materials Science Division, Physical and Life Science Directorate, Lawrence Livermore National Laboratory, Livermore, California94550, United States
| | - Ze Zhang
- Department of Mechanical Engineering, Stanford University, Stanford, California94305, United States
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Egan GC, Lau EY, Schwegler E. Multiframe Imaging of Micron and Nanoscale Bubble Dynamics. Nano Lett 2022; 22:1053-1058. [PMID: 35044188 DOI: 10.1021/acs.nanolett.1c04101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Here, we report on the direct sequential imaging of laser-induced cavitation of micron and nanoscale bubbles using Movie-Mode Dynamic Transmission Electron Microscopy (MM-DTEM). A 532 nm laser pulse (∼12 ns) was used to excite gold nanoparticles inside a ∼1.2 μm layer of water, and the resulting bubbles were observed with a series of nine electron pulses (∼10 ns) separated by as little as 40 ns peak to peak. Isolated nanobubbles were observed to collapse in less than 50 ns, while larger (∼2-3 μm) bubbles were observed to grow and collapse in less than 200 ns. Temporal profiles were generally asymmetric, possibly indicating faster growth than collapse dynamics, and the collapse time scale was found to be consistent with modeling and literature data from other techniques. More complex behavior was also observed for bubbles within proximity to each other, with interaction leading to longer lifetimes and more likely rebounding after collapse.
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Affiliation(s)
- Garth C Egan
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
| | - Edmond Y Lau
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
| | - Eric Schwegler
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
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Oliveira Júnior J, Mendes A, Montes J, Alves B, Moreira F, Bianchi I, Schwegler E, Peripolli V. Acidifiers blend on digestibility, blood metabolites and performance of nursery piglets. ARQ BRAS MED VET ZOO 2022. [DOI: 10.1590/1678-4162-12464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
ABSTRACT The aim of this study was to evaluate the effect of inclusion of two acidifiers blend (with different protection levels) on the acidification potential in vitro, apparent total tract digestibility of diet nutrients, blood metabolites, and average daily gain of nursery piglets. Two commercial acidifiers blend additives (AC1 and AC2) were evaluated. The acidification potential of the two acidifiers blend added to the diet were tested by buffering capacity and initial pH in vitro. For the evaluation of apparent digestibility of diet nutrients, blood metabolites and average daily gain, two experiments were carried out. The AC2 acidifier had a greater effect on the initial reduction in pH and a lower linear buffering rate of the diet. The use of acidifiers did not improve the nutrient digestibility of the diets and had no effect on the blood metabolite concentrations of urea, total protein, albumin, globulin, and lactate. Although the inclusion of acidifiers in the diets did not affect the apparent total tract digestibility of the diet nutrients the inclusion of the AC2 acidifier at different levels showed a negative quadratic effect on the average daily gain, with the best inclusion level being 0.26%.
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Fornazari Neto A, Martins C, Schwegler E, Barcellos J, Barth A. Blood metabolites and fecal starch as indicators of feed efficiency of beef cattle in the feedlot. ARQ BRAS MED VET ZOO 2021. [DOI: 10.1590/1678-4162-12360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
ABSTRACT The use of blood metabolites (BM), fecal starch (FS), and apparent digestion of starch, (ATTSD) as indicators of feed efficiency (FE) in beef cattle in the feedlot was studied. Fourteen bulls were used, originating in an industrial cross, without a defined racial group, with mean body weight of 284.86kg, individually fed, being evaluated in a 42-day confinement system. After the evaluation, the animals were divided into two groups according to the individual FE: high feed efficiency (HE) and low feed efficiency (LE). There was a difference between the groups in the variables FE, feed conversion (FC), final weight (FW), and daily weight gain (DWG). The FE had a positive correlation with DWG, FC, and FW. There was no difference between the groups for the variables BM, FS, and ATTSD, nor was there any correlation between these variables and FE. Considering the feed cost, the HE animals proved more profitable. BM, FS, and ATTSD did not statistically show potential to be used as indicators of FE, despite the evidence of numerical differences of these variables between the different groups, tendency of correlations with FE, and discriminating function with potential assertiveness.
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Affiliation(s)
| | | | | | | | - A.L. Barth
- Instituto Federal de Santa Catarina, Brazil
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Palmeira M, Borba Neto C, Vieira A, Schwegler E, Lehmann M, Moreira F, Oliveira Jr J, Bianchi I, Peripolli V. Produção leiteira de vacas em sistema semi-extensivo e sua relação com o estresse calórico. ARCH ZOOTEC 2021. [DOI: 10.21071/az.v70i272.5577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Considerando as caraterísticas subtropicais sul do Brasil, onde o verão é caracterizado por sua extensa duração com elevadas temperaturas e altos níveis de umidade, o estresse calórico é fator recorrente e pronunciado na bovinocultura leiteira. TTendo em vista o número expressivo de pequenos produtores e agricultura familiar na região de Santa Catarina, é imprescindível a análise dos impactos do estresse calórico em produções com menores dimensões. Por essas razões, o objetivo do presente estudo foi avaliar o impacto do estresse calórico na produção leiteira de vacas de baixa produção.11 animais foram analisados durante 4 meses (novembro a março), e as produções individuais diárias de leite foram obtidas através de copo coletor acoplado ao sistema de ordenha tipo espinha de peixe, com circuito fechado. Os dados das temperaturas diárias mínima e máxima, bem como a umidade relativa do ar durante o período experimental foram obtidos na estação meteorológica do Instituto Federal Catarinense Campus Araquari. As análises estatísticas foram realizadas com o auxílio do software SAS (versão 9.3, SAS Institute Inc., Cary, NC). Os dados foram submetidos a análise de variância (PROC MIXED) para avaliar o efeito do mês sobre o índice temperatura e umidade e a produção média de leite, e avaliar o efeito do ITU abaixo ou acima de 72 sobre a produção média de leite, além de correlação de Pearson (PROC CORR) e regressão (PROC REG) para avaliar a relação entre o ITU e a produção média de leite. As médias foram comparadas pelo teste de Tukey a 5% de probabilidade de erro. Os animais estudados não tiveram queda na produção quando o ITU foi mais pronunciado, sendo justificado pela baixa produção leiteira dos animais, tendo menor desafio metabólico.
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Aydin F, Moradzadeh A, Bilodeau CL, Lau EY, Schwegler E, Aluru NR, Pham TA. Ion Solvation and Transport in Narrow Carbon Nanotubes: Effects of Polarizability, Cation-π Interaction, and Confinement. J Chem Theory Comput 2021; 17:1596-1605. [PMID: 33625224 DOI: 10.1021/acs.jctc.0c00827] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Understanding ion solvation and transport under confinement is critical for a wide range of emerging technologies, including water desalination and energy storage. While molecular dynamics (MD) simulations have been widely used to study the behavior of confined ions, considerable deviations between simulation results depending on the specific treatment of intermolecular interactions remain. In the following, we present a systematic investigation of the structure and dynamics of two representative solutions, that is, KCl and LiCl, confined in narrow carbon nanotubes (CNTs) with a diameter of 1.1 and 1.5 nm, using a combination of first-principles and classical MD simulations. Our simulations show that the inclusion of both polarization and cation-π interactions is essential for the description of ion solvation under confinement, particularly for large ions with weak hydration energies. Beyond the variation in ion solvation, we find that cation-π interactions can significantly influence the transport properties of ions in CNTs, particularly for KCl, where our simulations point to a strong correlation between ion dehydration and diffusion. Our study highlights the complex interplay between nanoconfinement and specific intermolecular interactions that strongly control the solvation and transport properties of ions.
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Affiliation(s)
- Fikret Aydin
- Quantum Simulations Group, Materials Science Division, Lawrence Livermore National Laboratory, 7000 East Ave, Livermore, California 94550, United States
| | - Alireza Moradzadeh
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Camille L Bilodeau
- Department of Chemical and Biological Engineering and Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
| | - Edmond Y Lau
- Biosciences and Biotechnology Division, Lawrence Livermore National Laboratory, 7000 East Ave, Livermore, California 94550, United States
| | - Eric Schwegler
- Quantum Simulations Group, Materials Science Division, Lawrence Livermore National Laboratory, 7000 East Ave, Livermore, California 94550, United States
| | - Narayana R Aluru
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Tuan Anh Pham
- Quantum Simulations Group, Materials Science Division, Lawrence Livermore National Laboratory, 7000 East Ave, Livermore, California 94550, United States
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Bampi D, Borstnez K, Dias C, Costa O, Moreira F, Peripolli V, Oliveira Júnior J, Schwegler E, Rauber L, Bianchi I. Evaluation of reproductive and animal welfare parameters of swine females of different genetic lines submitted to different reproductive management and housing systems during pregnancy. ARQ BRAS MED VET ZOO 2020. [DOI: 10.1590/1678-4162-11767] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
ABSTRACT The aim of this study was to evaluate swine females of different genetic lines submitted to different reproductive management and housing systems during pregnancy on reproductive performance and animal welfare parameters. After artificial insemination protocol, 524 females were divided into two gestation housing systems: PEN1=animals housed in individual stalls during the breeding and after group-housed; PEN32=animals housed in individual stalls from breeding until 32 days of pregnancy and after group-housed. The number of piglets born, and the pregnancy and farrowing rates were evaluated. Welfare parameters related to the pregnancy phase were used. Females who weaned more piglets in the previous farrowing had a higher number of piglets born at the next farrowing. The pregnancy rate was affected by the number of semen doses. The farrowing rate was not influenced by the evaluated parameters, with average value of 91.36%. There was no effect of the gestation housing system and the genetic lines on pregnancy and farrowing rates, with values above 90.0%. The animal welfare indicators showed more compromised parameters in PEN1 system. PEN1 system did not impair the reproductive performance although it presented more compromised animal welfare parameters.
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Affiliation(s)
- D. Bampi
- Instituto Federal Catarinense, Brazil; Pamplona Alimentos S/A, Brazil
| | | | - C.P. Dias
- Universidade Estadual de Londrina, Brazil
| | | | - F. Moreira
- Instituto Federal Catarinense, Brazil; Instituto Federal Catarinense, Brazil
| | - V. Peripolli
- Instituto Federal Catarinense, Brazil; Instituto Federal Catarinense, Brazil
| | | | - E. Schwegler
- Instituto Federal Catarinense, Brazil; Instituto Federal Catarinense, Brazil
| | | | - I. Bianchi
- Instituto Federal Catarinense, Brazil; Instituto Federal Catarinense, Brazil
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Aydin F, Zhan C, Ritt C, Epsztein R, Elimelech M, Schwegler E, Pham TA. Similarities and differences between potassium and ammonium ions in liquid water: a first-principles study. Phys Chem Chem Phys 2020; 22:2540-2548. [DOI: 10.1039/c9cp06163k] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Understanding ion solvation in liquid water is critical in optimizing materials for a wide variety of emerging technologies, including water desalination and purification.
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Affiliation(s)
- Fikret Aydin
- Lawrence Livermore National Laboratory
- Livermore
- USA
| | - Cheng Zhan
- Lawrence Livermore National Laboratory
- Livermore
- USA
| | - Cody Ritt
- Department of Chemical and Environmental Engineering
- Yale University
- New Haven
- USA
| | - Razi Epsztein
- Department of Chemical and Environmental Engineering
- Yale University
- New Haven
- USA
- Faculty of Civil and Environmental Engineering
| | - Menachem Elimelech
- Department of Chemical and Environmental Engineering
- Yale University
- New Haven
- USA
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11
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Pham TA, Govoni M, Seidel R, Bradforth SE, Schwegler E, Galli G. Electronic structure of aqueous solutions: Bridging the gap between theory and experiments. Sci Adv 2017; 3:e1603210. [PMID: 28691091 PMCID: PMC5482551 DOI: 10.1126/sciadv.1603210] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Accepted: 04/28/2017] [Indexed: 05/31/2023]
Abstract
Predicting the electronic properties of aqueous liquids has been a long-standing challenge for quantum mechanical methods. However, it is a crucial step in understanding and predicting the key role played by aqueous solutions and electrolytes in a wide variety of emerging energy and environmental technologies, including battery and photoelectrochemical cell design. We propose an efficient and accurate approach to predict the electronic properties of aqueous solutions, on the basis of the combination of first-principles methods and experimental validation using state-of-the-art spectroscopic measurements. We present results of the photoelectron spectra of a broad range of solvated ions, showing that first-principles molecular dynamics simulations and electronic structure calculations using dielectric hybrid functionals provide a quantitative description of the electronic properties of the solvent and solutes, including excitation energies. The proposed computational framework is general and applicable to other liquids, thereby offering great promise in understanding and engineering solutions and liquid electrolytes for a variety of important energy technologies.
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Affiliation(s)
- Tuan Anh Pham
- Quantum Simulations Group, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
| | - Marco Govoni
- Institute for Molecular Engineering, University of Chicago, Chicago, IL 60637, USA
- Materials Science Division, Argonne National Laboratory, Lemont, IL 60439, USA
| | - Robert Seidel
- Department of Chemistry, University of Southern California, Los Angeles, CA 90089–0482, USA
| | - Stephen E. Bradforth
- Department of Chemistry, University of Southern California, Los Angeles, CA 90089–0482, USA
| | - Eric Schwegler
- Quantum Simulations Group, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
| | - Giulia Galli
- Institute for Molecular Engineering, University of Chicago, Chicago, IL 60637, USA
- Materials Science Division, Argonne National Laboratory, Lemont, IL 60439, USA
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12
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Ogitsu T, Lordi V, Schwegler E, Widom M. Comment on "New Ground-State Crystal Structure of Elemental Boron". Phys Rev Lett 2017; 118:159601. [PMID: 28452521 DOI: 10.1103/physrevlett.118.159601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Indexed: 06/07/2023]
Affiliation(s)
- Tadashi Ogitsu
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, USA
| | - Vincenzo Lordi
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, USA
| | - Eric Schwegler
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, USA
| | - Michael Widom
- Carnegie Mellon University, Department of Physics, 5000 Forbes Avenue, Pittsburgh, Pennsylvania 15213, USA
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13
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Tabeleão V, Schwegler E, Pereira R, Krause A, Montagner P, Feijó J, Schneider A, Schmitt E, Brauner C, Rabassa V, Pino FD, Corrêa M. Combinação de butafosfan e cianocobalamina no metabolismo da glicose em vacas leiteiras após o parto. ARQ BRAS MED VET ZOO 2017. [DOI: 10.1590/1678-4162-8453] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
RESUMO A hipótese deste estudo é de que o uso da combinação de butafosfan e cianocobalamina pode melhorar a resistência periférica à insulina, aumentar a quantidade de glicose disponível para a glândula mamária e a produção de leite. Assim, o objetivo foi investigar os efeitos combinados de butafosfan e cianocobalamina sobre o metabolismo da glicose em vacas leiteiras no período pós-parto. Vinte e uma vacas leiteiras foram divididas em dois grupos: grupo controle (CON, n= 11), que recebeu cinco aplicações de solução salina (20mL / animal 0,9% NaCl), e grupo Catosal(r) (ABC, n= 10), que recebeu cinco aplicações de 20mL de uma solução contendo as substâncias butafosfan e cianocobalamina (B12 Catosal(r), 100mg da substância butafosfan e 50µg de cianocobalamina por mL). As aplicações foram realizadas por via intramuscular, nos dias sete, 12, 17, 22 e 27 pós-parto. As amostras de sangue foram coletadas para a avaliação das concentrações plasmáticas de fósforo, glicose, ácidos graxos não esterificados (AGNE), albumina, aspartato aminotransferase (AST) e creatina quinase (CK). Nos dias oito e 28 pós-parto, os animais foram pesados e submetidos aos testes de tolerância à glicose e à insulina. O tratamento promoveu perda de peso (ABC 40,4kg, CON 10,73kg, P<0,05) e aumento da AST (ABC 62,92 ±3,31U/L, CON 53,11±3,49 U / L, P<0,05) e dos níveis de CK (ABC 134,09± 19,08U / L, CON 79,43 ± 18,27U / L). Os grupos não diferiram quanto ao metabolismo (área sob a curva) da glicose nos dias oito e 28, porém os animais tratados tiveram um aumento na glicemia (P<0,05) no dia 28 pós-parto (97,54 ± 8,54mg / dL), após a administração de insulina, em comparação ao dia oito (83,01 ± 8,54mg / dL). Assim, pode-se concluir que a combinação de butafosfan e cianocobalamina melhora a adaptação do metabolismo da glicose em vacas leiteiras no início da lactação.
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Abstract
Efficient exploration of configuration space and identification of metastable structures in condensed phase systems are challenging from both computational and algorithmic perspectives. In this regard, schemes that utilize a set of pre-defined order parameters to sample the relevant parts of the configuration space [L. Maragliano and E. Vanden-Eijnden, Chem. Phys. Lett. 426, 168 (2006); J. B. Abrams and M. E. Tuckerman, J. Phys. Chem. B 112, 15742 (2008)] have proved useful. Here, we demonstrate how these order-parameter aided temperature accelerated sampling schemes can be used within the Born-Oppenheimer and the Car-Parrinello frameworks of ab initio molecular dynamics to efficiently and systematically explore free energy surfaces, and search for metastable states and reaction pathways. We have used these methods to identify the metastable structures and reaction pathways in SiO2 and Ti. In addition, we have used the string method [W. E, W. Ren, and E. Vanden-Eijnden, Phys. Rev. B 66, 052301 (2002); L. Maragliano et al., J. Chem. Phys. 125, 024106 (2006)] within the density functional theory to study the melting pathways in the high pressure cotunnite phase of SiO2 and the hexagonal closed packed to face centered cubic phase transition in Ti.
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Affiliation(s)
- Amit Samanta
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - Miguel A Morales
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - Eric Schwegler
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
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15
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Pham TA, Ogitsu T, Lau EY, Schwegler E. Structure and dynamics of aqueous solutions from PBE-based first-principles molecular dynamics simulations. J Chem Phys 2016; 145:154501. [DOI: 10.1063/1.4964865] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Affiliation(s)
- Tuan Anh Pham
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - Tadashi Ogitsu
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - Edmond Y. Lau
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - Eric Schwegler
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94551, USA
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16
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Goliaei A, Lau EY, Adhikari U, Schwegler E, Berkowitz ML. Behavior of P85 and P188 Poloxamer Molecules: Computer Simulations Using United-Atom Force-Field. J Phys Chem B 2016; 120:8631-41. [PMID: 27232763 DOI: 10.1021/acs.jpcb.6b03030] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
To study the interaction between poloxamer molecules and lipid bilayers using molecular dynamics simulation technique with the united-atom resolution, we augmented the GROMOS force-field to include poloxamers. We validated the force-field by calculating the radii of gyration of two poloxamers, P85 and P188, solvated in water and by considering the poloxamer density distributions at the air/water interface. The emphasis of our simulations was on the study of the interaction between poloxamers and lipid bilayer. At the water/lipid bilayer interface, we observed that both poloxamers studied, P85 and P188, behaved like surfactants: the hydrophilic blocks of poloxamers became adsorbed at the polar interface, while their hydrophobic block penetrated the interface into the aliphatic tail region of the lipid bilayer. We also observed that when P85 and P188 poloxamers interacted with damaged membranes that contained pores, the hydrophobic blocks of copolymers penetrated into the membrane in the vicinity of the pore and compressed the membrane. Due to this compression, water molecules were evacuated from the pore.
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Affiliation(s)
| | - Edmond Y Lau
- Lawrence Livermore National Laboratory , 7000 East Avenue, Livermore, California 94550, United States
| | | | - Eric Schwegler
- Lawrence Livermore National Laboratory , 7000 East Avenue, Livermore, California 94550, United States
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17
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Fattebert JL, Law RJ, Bennion B, Lau EY, Schwegler E, Lightstone FC. Quantitative Assessment of Electrostatic Embedding in Density Functional Theory Calculations of Biomolecular Systems. J Chem Theory Comput 2015; 5:2257-64. [PMID: 26616612 DOI: 10.1021/ct900209y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
We evaluate the accuracy of density functional theory quantum calculations of biomolecular subsystems using a simple electrostatic embedding scheme. Our scheme is based on dividing the system of interest into a primary and secondary subsystem. A finite difference discretization of the Kohn-Sham equations is used for the primary subsystem, while its electrostatic environment is modeled with a simple one-electron potential. Force-field atomic partial charges are used to generate smeared Gaussian charge densities and to model the secondary subsystem. We illustrate the utility of this approach with calculations of truncated dipeptide chains. We analyze quantitatively the accuracy of this approach by calculating atomic forces and comparing results with full QM calculations. The impact of the choice made in terminating dangling bonds at the frontier of the QM region is also investigated.
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Affiliation(s)
- J-L Fattebert
- Center for Applied Scientific Computing, and Physical & Life Sciences, Lawrence Livermore National Laboratory, Livermore, California 94551
| | - R J Law
- Center for Applied Scientific Computing, and Physical & Life Sciences, Lawrence Livermore National Laboratory, Livermore, California 94551
| | - B Bennion
- Center for Applied Scientific Computing, and Physical & Life Sciences, Lawrence Livermore National Laboratory, Livermore, California 94551
| | - E Y Lau
- Center for Applied Scientific Computing, and Physical & Life Sciences, Lawrence Livermore National Laboratory, Livermore, California 94551
| | - E Schwegler
- Center for Applied Scientific Computing, and Physical & Life Sciences, Lawrence Livermore National Laboratory, Livermore, California 94551
| | - F C Lightstone
- Center for Applied Scientific Computing, and Physical & Life Sciences, Lawrence Livermore National Laboratory, Livermore, California 94551
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18
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Pham TA, Lee D, Schwegler E, Galli G. Interfacial Effects on the Band Edges of Functionalized Si Surfaces in Liquid Water. J Am Chem Soc 2014; 136:17071-7. [DOI: 10.1021/ja5079865] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Tuan Anh Pham
- Department
of Chemistry, University of California, Davis, California 95616, United States
- Lawrence
Livermore
National Laboratory, Livermore, California 94551, United States
| | - Donghwa Lee
- Lawrence
Livermore
National Laboratory, Livermore, California 94551, United States
| | - Eric Schwegler
- Lawrence
Livermore
National Laboratory, Livermore, California 94551, United States
| | - Giulia Galli
- The
Institute for Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
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19
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Wood BC, Schwegler E, Choi WI, Ogitsu T. Hydrogen-Bond Dynamics of Water at the Interface with InP/GaP(001) and the Implications for Photoelectrochemistry. J Am Chem Soc 2013; 135:15774-83. [DOI: 10.1021/ja403850s] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Brandon C. Wood
- Quantum
Simulations Group, Lawrence Livermore National Laboratory, Livermore, CA 94550
| | - Eric Schwegler
- Quantum
Simulations Group, Lawrence Livermore National Laboratory, Livermore, CA 94550
| | - Woon Ih Choi
- Quantum
Simulations Group, Lawrence Livermore National Laboratory, Livermore, CA 94550
| | - Tadashi Ogitsu
- Quantum
Simulations Group, Lawrence Livermore National Laboratory, Livermore, CA 94550
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20
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Bennion BJ, Lau EY, Fattebert JL, Huang P, Schwegler E, Corning W, Lightstone FC. MODELING THE BINDING OF CWAs TO AChE AND BuChE. ACTA ACUST UNITED AC 2013. [DOI: 10.31482/mmsl.2013.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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21
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Ogitsu T, Schwegler E, Galli G. β-Rhombohedral Boron: At the Crossroads of the Chemistry of Boron and the Physics of Frustration. Chem Rev 2013; 113:3425-49. [DOI: 10.1021/cr300356t] [Citation(s) in RCA: 149] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Tadashi Ogitsu
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California
94550, United States
| | - Eric Schwegler
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California
94550, United States
| | - Giulia Galli
- University of California, Davis, California 95616,
United States
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22
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Schmitt E, Schneider A, Goulart M, Schwegler E, Pereira R, Hoffmann D, Lopes M, Hax L, Del Pino F, Corrêa M. Correlação entre cálcio e insulina durante o teste de tolerância à glicose em ovelhas gestantes e não gestantes. ARQ BRAS MED VET ZOO 2012. [DOI: 10.1590/s0102-09352012000500006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Compararam-se as concentrações de cálcio, glicose e insulina em ovelhas gestantes e não gestantes submetidas ao teste de tolerância à glicose (TTG). Oito ovelhas gestantes (GG) e oito não gestantes (NG) foram submetidas ao TTG por meio da administração endovenosa de uma solução de glicose, na dose de 500mg/kg de peso vivo. Amostras de sangue foram coletadas nos tempos de -15, zero, 15, 30, 45, 60, 90, 120, 150 e 180 minutos, sendo zero min o momento da infusão, para avaliação da concentração sanguínea de glicose, cálcio e insulina. Foi avaliada a taxa de metabolização de glicose e insulina, por meio do cálculo da área sob a curva (ASC). As concentrações de glicose, cálcio, insulina e a ASC da insulina não diferiram entre os grupos (P>0,05), entretanto as três últimas ASCs da glicose foram mais elevados nas gestantes (P<0,05), que correspondem ao período entre 90 e 180min. O teste de correlação de Pearson revelou correlação negativa entre concentração de cálcio e insulina nas gestantes (P<0,05). Estes resultados indicam menor taxa de metabolização de glicose em ovelhas gestantes e uma possível relação de cálcio e insulina no terço final de gestação.
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Affiliation(s)
- E. Schmitt
- Universidade Federal de Pelotas; EMBRAPA Rondônia
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23
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Kulik HJ, Schwegler E, Galli G. Probing the Structure of Salt Water under Confinement with First-Principles Molecular Dynamics and Theoretical X-ray Absorption Spectroscopy. J Phys Chem Lett 2012; 3:2653-2658. [PMID: 26295887 DOI: 10.1021/jz300932p] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We investigated the structure of liquid water around cations (Na(+)) and anions (Cl(-)) confined inside of a (19,0) carbon nanotube with first-principles molecular dynamics and theoretical X-ray absorption spectroscopy (XAS). We found that the ions preferentially reside near the interface between the nanotube and the liquid. Upon confinement, the XAS signal of water molecules surrounding Na(+) exhibits enhanced pre-edge and reduced post-edge features with respect to that of pure water, at variance with the solvation shell of Na(+) in bulk water. Conversely, the first solvation shell of confined Cl(-) has a main-edge intensity comparable to that of bulk solvated Cl(-), likely as a result of a high number of acceptor hydrogen bonds in the first solvation shell. Confined nonsolvating water molecules exhibit bulk-like or water-monomer-like properties, depending on whether they belong to core or interfacial layers, respectively.
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Affiliation(s)
- Heather J Kulik
- †Department of Chemistry, Stanford University, 333 Campus Drive, Mudd Building Room 121, Stanford, California 94305, United States
| | - Eric Schwegler
- ‡Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, 7000 East Avenue, PO Box 808, L-415, Livermore, California 94550, United States
| | - Giulia Galli
- ¶Departments of Chemistry and Physics, University of California-Davis, One Shields Avenue, Davis, California 95618, United States
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Affiliation(s)
- T. Anh Pham
- Lawrence Livermore National Laboratory, Livermore, California 94551, United
States
- Department of Chemistry, University of California, Davis, California 95616,
United States
| | - P. Huang
- Lawrence Livermore National Laboratory, Livermore, California 94551, United
States
| | - E. Schwegler
- Lawrence Livermore National Laboratory, Livermore, California 94551, United
States
| | - G. Galli
- Department of Chemistry, University of California, Davis, California 95616,
United States
- Department
of Physics, University of California, Davis,
California 95616,
United States
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25
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Lee JRI, Whitley HD, Meulenberg RW, Wolcott A, Zhang JZ, Prendergast D, Lovingood DD, Strouse GF, Ogitsu T, Schwegler E, Terminello LJ, van Buuren T. Ligand-mediated modification of the electronic structure of CdSe quantum dots. Nano Lett 2012; 12:2763-2767. [PMID: 22594309 DOI: 10.1021/nl300886h] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
X-ray absorption spectroscopy and ab initio modeling of the experimental spectra have been used to investigate the effects of surface passivation on the unoccupied electronic states of CdSe quantum dots (QDs). Significant differences are observed in the unoccupied electronic structure of the CdSe QDs, which are shown to arise from variations in specific ligand-surface bonding interactions.
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Affiliation(s)
- Jonathan R I Lee
- Lawrence Livermore National Laboratory , 7000 East Avenue, Livermore, California 94550, United States
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26
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Kang J, Zhu J, Wei SH, Schwegler E, Kim YH. Persistent medium-range order and anomalous liquid properties of Al(1-x)Cu(x) alloys. Phys Rev Lett 2012; 108:115901. [PMID: 22540487 DOI: 10.1103/physrevlett.108.115901] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Revised: 12/05/2011] [Indexed: 05/31/2023]
Abstract
The development of short-to-medium-range order in atomic arrangements has generally been observed in noncrystalline solid systems such as metallic glasses. Whether such medium-range order (MRO) can exist in materials at well above their melting or glass-transition temperature has been a long-standing important scientific issue. Here, using ab initio molecular dynamics simulations, we show that a novel, persistent MRO exists in liquid Al-Cu alloys near the composition of CuAl3. The correlated atomic motions associated with the MRO give rise to a substantially enhanced viscosity in the vicinity of the composition. The component of the MRO liquid state gradually decreases with increasing temperature, and it disappears above a crossover temperature T(LLC). The continuous liquid-liquid crossover through a percolationlike transition leads to a pronounced heat capacity peak at T(LLC).
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Affiliation(s)
- Joongoo Kang
- National Renewable Energy Laboratory, Golden, Colorado 80401, USA.
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27
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Wood BC, Ogitsu T, Schwegler E. Local structural models of complex oxygen- and hydroxyl-rich GaP/InP(001) surfaces. J Chem Phys 2012; 136:064705. [DOI: 10.1063/1.3682768] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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28
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Spanu L, Donadio D, Hohl D, Schwegler E, Gallia G. Stability of hydrocarbons at deep Earth pressures and temperatures. Acta Crystallogr A 2011. [DOI: 10.1107/s0108767311095857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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29
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Boates B, Hamel S, Schwegler E, Bonev SA. Structural and optical properties of liquid CO2 for pressures up to 1 TPa. J Chem Phys 2011; 134:064504. [DOI: 10.1063/1.3549593] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
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30
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Sadigh B, Erhart P, Åberg D, Trave A, Schwegler E, Bude J. First-principles calculations of the Urbach tail in the optical absorption spectra of silica glass. Phys Rev Lett 2011; 106:027401. [PMID: 21405249 DOI: 10.1103/physrevlett.106.027401] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2010] [Indexed: 05/27/2023]
Abstract
We present density-functional theory calculations of the optical absorption spectra of silica glass for temperatures up to 2400 K. The calculated spectra exhibit exponential tails near the fundamental absorption edge that follow the Urbach rule in good agreement with experiments. We discuss the accuracy of our results by comparing to hybrid exchange correlation functionals. We show that the Urbach rule holds in a frequency interval where optical absorption is Poisson distributed with very large statistical fluctuations. In this regime, a direct relation between the optical absorption coefficient and electronic density of states is derived, which provides a link between photoemission and absorption spectra and is used to determine the lower bound to the Urbach frequency regime.
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Affiliation(s)
- B Sadigh
- Lawrence Livermore National Laboratory, Chemistry, Materials and Life Sciences Directorate, Livermore, California 94550, USA
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31
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Kulik HJ, Marzari N, Correa AA, Prendergast D, Schwegler E, Galli G. Local Effects in the X-ray Absorption Spectrum of Salt Water. J Phys Chem B 2010; 114:9594-601. [DOI: 10.1021/jp103526y] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Heather J. Kulik
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139; Lawrence Livermore National Laboratory, Livermore, California, 94550; Lawrence Berkeley National Laboratory, Berkeley, California, 94720; and Department of Chemistry, University of California, Davis, California 95616
| | - Nicola Marzari
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139; Lawrence Livermore National Laboratory, Livermore, California, 94550; Lawrence Berkeley National Laboratory, Berkeley, California, 94720; and Department of Chemistry, University of California, Davis, California 95616
| | - Alfredo A. Correa
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139; Lawrence Livermore National Laboratory, Livermore, California, 94550; Lawrence Berkeley National Laboratory, Berkeley, California, 94720; and Department of Chemistry, University of California, Davis, California 95616
| | - David Prendergast
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139; Lawrence Livermore National Laboratory, Livermore, California, 94550; Lawrence Berkeley National Laboratory, Berkeley, California, 94720; and Department of Chemistry, University of California, Davis, California 95616
| | - Eric Schwegler
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139; Lawrence Livermore National Laboratory, Livermore, California, 94550; Lawrence Berkeley National Laboratory, Berkeley, California, 94720; and Department of Chemistry, University of California, Davis, California 95616
| | - Giulia Galli
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139; Lawrence Livermore National Laboratory, Livermore, California, 94550; Lawrence Berkeley National Laboratory, Berkeley, California, 94720; and Department of Chemistry, University of California, Davis, California 95616
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32
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Roos T, Tabeleão V, Dümmer L, Schwegler E, Goulart M, Moura S, Corrêa M, Leite F, Gil-Turnes C. Effect ofBacillus cereusvar. Toyoi andSaccharomyces boulardiion the immune response of sheep to vaccines. FOOD AGR IMMUNOL 2010. [DOI: 10.1080/09540100903443691] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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33
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Klepeis JHP, Evans WJ, Zaitseva N, Schwegler E, Teat SJ. Ammonium salicylate: a synchrotron study. Acta Crystallogr Sect E Struct Rep Online 2009; 65:o2062. [PMID: 21577486 PMCID: PMC2970122 DOI: 10.1107/s1600536809029857] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2009] [Accepted: 07/27/2009] [Indexed: 11/30/2022]
Abstract
The structure of the title salt, NH4+·C7H5O3−, is stabilized by substantial hydrogen bonding between ammonium cations and salicylate anions that links the components into a two-dimensional array.
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Affiliation(s)
- Davide Donadio
- Department of Chemistry, University of California, One Shields Avenue, Davis, California 95616, Department of Materials Science and Chemical Eng., Politecnico di Torino, Turin, Italy, and Lawrence Livermore National Laboratory, Livermore, California 94550
| | - Giancarlo Cicero
- Department of Chemistry, University of California, One Shields Avenue, Davis, California 95616, Department of Materials Science and Chemical Eng., Politecnico di Torino, Turin, Italy, and Lawrence Livermore National Laboratory, Livermore, California 94550
| | - Eric Schwegler
- Department of Chemistry, University of California, One Shields Avenue, Davis, California 95616, Department of Materials Science and Chemical Eng., Politecnico di Torino, Turin, Italy, and Lawrence Livermore National Laboratory, Livermore, California 94550
| | - Manu Sharma
- Department of Chemistry, University of California, One Shields Avenue, Davis, California 95616, Department of Materials Science and Chemical Eng., Politecnico di Torino, Turin, Italy, and Lawrence Livermore National Laboratory, Livermore, California 94550
| | - Giulia Galli
- Department of Chemistry, University of California, One Shields Avenue, Davis, California 95616, Department of Materials Science and Chemical Eng., Politecnico di Torino, Turin, Italy, and Lawrence Livermore National Laboratory, Livermore, California 94550
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35
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Ogitsu T, Gygi F, Reed J, Motome Y, Schwegler E, Galli G. Imperfect Crystal and Unusual Semiconductor: Boron, a Frustrated Element. J Am Chem Soc 2009; 131:1903-9. [DOI: 10.1021/ja807622w] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Tadashi Ogitsu
- Lawrence Livermore National Laboratory, Livermore, California 94550, University of California, Davis, California 95616, and University of Tokyo, Tokyo, Japan
| | - François Gygi
- Lawrence Livermore National Laboratory, Livermore, California 94550, University of California, Davis, California 95616, and University of Tokyo, Tokyo, Japan
| | - John Reed
- Lawrence Livermore National Laboratory, Livermore, California 94550, University of California, Davis, California 95616, and University of Tokyo, Tokyo, Japan
| | - Yukitoshi Motome
- Lawrence Livermore National Laboratory, Livermore, California 94550, University of California, Davis, California 95616, and University of Tokyo, Tokyo, Japan
| | - Eric Schwegler
- Lawrence Livermore National Laboratory, Livermore, California 94550, University of California, Davis, California 95616, and University of Tokyo, Tokyo, Japan
| | - Giulia Galli
- Lawrence Livermore National Laboratory, Livermore, California 94550, University of California, Davis, California 95616, and University of Tokyo, Tokyo, Japan
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36
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Abstract
We have computed infrared (IR) spectra of water confined between nonpolar surfaces by using ab initio calculations. We show that electronic charge fluctuations at the interface, occurring even in the case of highly hydrophobic substrates, are responsible for specific features present in IR signals and for important differences between IR spectra and vibrational density of states. We also find that most of the frequency shifts observed under confinement originate from the modified hydrogen bonded network in close proximity to the interface.
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Affiliation(s)
- Manu Sharma
- Department of Chemistry, University of California, One Shields Avenue, Davis, California 95616, USA
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37
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Cicero G, Grossman JC, Schwegler E, Gygi F, Galli G. Water confined in nanotubes and between graphene sheets: a first principle study. J Am Chem Soc 2008. [PMID: 18211065 DOI: 10.1021/ja074418] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Water confined at the nanoscale has been the focus of numerous experimental and theoretical investigations in recent years, yet there is no consensus on such basic properties as diffusion and the nature of hydrogen bonding (HB) under confinement. Unraveling these properties is important to understand fluid flow and transport at the nanoscale, and to shed light on the solvation of biomolecules. Here we report on a first principle, computational study focusing on water confined between prototypical nonpolar substrates, i.e., single-wall carbon nanotubes and graphene sheets, 1-2.5 nm apart. The results of our molecular dynamics simulations show the presence of a thin, interfacial liquid layer (approximately 5 A) whose microscopic structure and thickness are independent of the distance between confining layers. The properties of the HB network are very similar to those of the bulk outside the interfacial region, even in the case of strong confinement. Our findings indicate that the perturbation induced by the presence of confining media is extremely local in liquid water, and we propose that many of the effects attributed to novel phases under confinement are determined by subtle electronic structure rearrangements occurring at the interface with the confining medium.
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Affiliation(s)
- Giancarlo Cicero
- Physics Department, Politecnico of Torino, C.so Duca degli Abruzzi 24, 10129 Torino, Italy.
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38
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Cicero G, Grossman JC, Schwegler E, Gygi F, Galli G. Water Confined in Nanotubes and between Graphene Sheets: A First Principle Study. J Am Chem Soc 2008; 130:1871-8. [DOI: 10.1021/ja074418+] [Citation(s) in RCA: 367] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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39
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Allesch M, Lightstone FC, Schwegler E, Galli G. First principles and classical molecular dynamics simulations of solvated benzene. J Chem Phys 2008; 128:014501. [DOI: 10.1063/1.2806288] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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40
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Raty JY, Schwegler E, Bonev SA. Electronic and structural transitions in dense liquid sodium. Nature 2007; 449:448-51. [PMID: 17898764 DOI: 10.1038/nature06123] [Citation(s) in RCA: 121] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2007] [Accepted: 07/19/2007] [Indexed: 11/09/2022]
Abstract
At ambient conditions, the light alkali metals are free-electron-like crystals with a highly symmetric structure. However, they were found recently to exhibit unexpected complexity under pressure. It was predicted from theory--and later confirmed by experiment--that lithium and sodium undergo a sequence of symmetry-breaking transitions, driven by a Peierls mechanism, at high pressures. Measurements of the sodium melting curve have subsequently revealed an unprecedented (and still unexplained) pressure-induced drop in melting temperature from 1,000 K at 30 GPa down to room temperature at 120 GPa. Here we report results from ab initio calculations that explain the unusual melting behaviour in dense sodium. We show that molten sodium undergoes a series of pressure-induced structural and electronic transitions, analogous to those observed in solid sodium but commencing at much lower pressure in the presence of liquid disorder. As pressure is increased, liquid sodium initially evolves by assuming a more compact local structure. However, a transition to a lower-coordinated liquid takes place at a pressure of around 65 GPa, accompanied by a threefold drop in electrical conductivity. This transition is driven by the opening of a pseudogap, at the Fermi level, in the electronic density of states--an effect that has not hitherto been observed in a liquid metal. The lower-coordinated liquid emerges at high temperatures and above the stability region of a close-packed free-electron-like metal. We predict that similar exotic behaviour is possible in other materials as well.
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41
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42
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Abstract
We report on the aqueous hydration of benzene and hexafluorobenzene, as obtained by carrying out extensive (>100 ps) first principles molecular dynamics simulations. Our results show that benzene and hexafluorobenzene do not behave as ordinary hydrophobic solutes, but rather present two distinct regions, one equatorial and the other axial, that exhibit different solvation properties. While in both cases the equatorial regions behave as typical hydrophobic solutes, the solvation properties of the axial regions depend strongly on the nature of the pi-water interaction. In particular, pi-hydrogen and pi-lone pair interactions are found to dominate in benzene and hexafluorobenzene, respectively, which leads to substantially different orientations of water near the two solutes. We present atomic and electronic structure results (in terms of Maximally Localized Wannier Functions) providing a microscopic description of benzene- and hexafluorobenzene-water interfaces, as well as a comparative study of the two solutes. Our results point at the importance of an accurate description of interfacial water to characterize hydration properties of apolar molecules, as these are strongly influenced by subtle charge rearrangements and dipole moment redistributions in interfacial regions.
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Affiliation(s)
- Markus Allesch
- Department of Theoretical and Computational Physics, Graz University of Technology, Graz, Austria
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43
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Ping Y, Hanson D, Koslow I, Ogitsu T, Prendergast D, Schwegler E, Collins G, Ng A. Broadband dielectric function of nonequilibrium warm dense gold. Phys Rev Lett 2006; 96:255003. [PMID: 16907313 DOI: 10.1103/physrevlett.96.255003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2006] [Indexed: 05/11/2023]
Abstract
We report on the first single-state measurement of the broadband (450-800 nm) dielectric function of gold isochorically heated by a femtosecond laser pulse to energy densities of 10(6) - 10(7) J/kg. A Drude and an interband component are clearly seen in the imaginary part of the dielectric function. The Drude component increases with energy density while the interband component shows both enhancement and redshift. This is in strong disagreement with predictions of a recent calculation of dielectric function based on limited Brillouin zone sampling.
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Affiliation(s)
- Y Ping
- Lawrence Livermore National Laboratory, Livermore, California, USA
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44
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Tymczak CJ, Weber VT, Schwegler E, Challacombe M. Linear scaling computation of the Fock matrix. VIII. Periodic boundaries for exact exchange at the Gamma point. J Chem Phys 2006; 122:124105. [PMID: 15836367 DOI: 10.1063/1.1869470] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A translationally invariant formulation of the Hartree-Fock (HF) Gamma-point approximation is presented. This formulation is achieved through introduction of the minimum image convention (MIC) at the level of primitive two-electron integrals, and implemented in a periodic version of the ONX algorithm [E. Schwegler, M. Challacombe, and M. Head-Gordon, J. Chem. Phys. 106, 9708 (1997)] for linear scaling computation of the exchange matrix. Convergence of the HF-MIC Gamma-point model to the HF k-space limit is demonstrated for fully periodic magnesium oxide, ice, and diamond. Computation of the diamond lattice constant using the HF-MIC model together with the hybrid PBE0 density functional [C. Adamo, M. Cossi, and V. Barone, THEOCHEM 493, 145 (1999)] yields a0=3.569 A with the 6-21G* basis set and a 3x3x3 supercell. Linear scaling computation of the HF-MIC exchange matrix is demonstrated for diamond and ice in the condensed phase.
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Affiliation(s)
- C J Tymczak
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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45
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Affiliation(s)
- Felice C Lightstone
- Biosciences, Lawrence Livermore National Laboratory, Livermore, CA 94551, USA.
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46
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Ogitsu T, Schwegler E, Galli G, Gygi F. First-principles simulations of LiH: towards the B2 Phase. Acta Crystallogr A 2005. [DOI: 10.1107/s0108767305080591] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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47
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Bonev SA, Schwegler E, Ogitsu T, Galli G. A quantum fluid of metallic hydrogen suggested by first-principles calculations. Nature 2004; 431:669-72. [PMID: 15470423 DOI: 10.1038/nature02968] [Citation(s) in RCA: 259] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2004] [Accepted: 08/25/2004] [Indexed: 11/08/2022]
Abstract
It is generally assumed that solid hydrogen will transform into a metallic alkali-like crystal at sufficiently high pressure. However, some theoretical models have also suggested that compressed hydrogen may form an unusual two-component (protons and electrons) metallic fluid at low temperature, or possibly even a zero-temperature liquid ground state. The existence of these new states of matter is conditional on the presence of a maximum in the melting temperature versus pressure curve (the 'melt line'). Previous measurements of the hydrogen melt line up to pressures of 44 GPa have led to controversial conclusions regarding the existence of this maximum. Here we report ab initio calculations that establish the melt line up to 200 GPa. We predict that subtle changes in the intermolecular interactions lead to a decline of the melt line above 90 GPa. The implication is that as solid molecular hydrogen is compressed, it transforms into a low-temperature quantum fluid before becoming a monatomic crystal. The emerging low-temperature phase diagram of hydrogen and its isotopes bears analogies with the familiar phases of 3He and 4He (the only known zero-temperature liquids), but the long-range Coulomb interactions and the large component mass ratio present in hydrogen would result in dramatically different properties.
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Affiliation(s)
- Stanimir A Bonev
- Lawrence Livermore National Laboratory, University of California, Livermore, California 94550, USA.
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48
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Grossman JC, Schwegler E, Galli G. Quantum and Classical Molecular Dynamics Simulations of Hydrophobic Hydration Structure around Small Solutes. J Phys Chem B 2004. [DOI: 10.1021/jp0470187] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jeffrey C. Grossman
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550
| | - Eric Schwegler
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550
| | - Giulia Galli
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550
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49
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Schwegler E, Grossman JC, Gygi F, Galli G. Towards an assessment of the accuracy of density functional theory for first principles simulations of water. II. J Chem Phys 2004; 121:5400-9. [PMID: 15352834 DOI: 10.1063/1.1782074] [Citation(s) in RCA: 318] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A series of 20 ps ab initio molecular dynamics simulations of water at ambient density and temperatures ranging from 300 to 450 K are presented. Car-Parrinello (CP) and Born-Oppenheimer (BO) molecular dynamics techniques are compared for systems containing 54 and 64 water molecules. At 300 K, an excellent agreement is found between radial distribution functions (RDFs) obtained with BO and CP dynamics, provided an appropriately small value of the fictitious mass parameter is used in the CP simulation. However, we find that the diffusion coefficients computed from CP dynamics are approximately two times larger than those obtained with BO simulations for T>400 K, where statistically meaningful comparisons can be made. Overall, both BO and CP dynamics at 300 K yield overstructured RDFs and slow diffusion as compared to experiment. In order to understand these discrepancies, the effect of proton quantum motion is investigated with the use of empirical interaction potentials. We find that proton quantum effects may have a larger impact than previously thought on structure and diffusion of the liquid.
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Affiliation(s)
- Eric Schwegler
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 84559, USA
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50
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Abstract
We present the results of Car-Parrinello (CP) simulations of water at ambient conditions and under pressure, using a rigid molecule approximation. Throughout our calculations, water molecules were maintained at a fixed intramolecular geometry corresponding to the average structure obtained in fully unconstrained simulations. This allows us to use larger time steps than those adopted in ordinary CP simulations of water, and thus to access longer time scales. In the absence of chemical reactions or dissociation effects, these calculations open the way to ab initio simulations of aqueous solutions that require time scales substantially longer than presently feasible (e.g., simulations of hydrophobic solvation). Our results show that structural properties and diffusion coefficients obtained with a rigid model are in better agreement with experiment than those determined with fully flexible simulations. Possible reasons responsible for this improved agreement are discussed.
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Affiliation(s)
- Markus Allesch
- Department of Theoretical Physics, Graz University of Technology, Austria
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