1
|
Cera-Glow, ferment lysates of Lacticaseibacillus rhamnosus IDCC 3201, improves skin barrier function in clinical study. J Cosmet Dermatol 2023; 22:1879-1886. [PMID: 36718839 DOI: 10.1111/jocd.15642] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 12/23/2022] [Accepted: 01/08/2023] [Indexed: 02/01/2023]
Abstract
BACKGROUND Ceramides are essential lipids in stratum corneum for skin permeability barrier function in that they retain the skin moisture and protect from the invasion of foreign pathogens. Previously, we demonstrated that ferment lysates of Lacticaseibacillus rhamnosus IDCC 3201 enhanced ceramide production in human epidermal keratinocytes. Furthermore, for comprehensive knowledge of this effect, in vitro experiments and multi-omics analysis were conducted to explore the underlying mechanisms. AIMS This study was designed to identify whether a cosmetic sample (i.e., Cera-Glow) containing the lysates improves the skin barrier function in clinical trials. PATIENTS/METHODS Twenty-four female participants (45.46 ± 9.78 years) had been enrolled in the transepidermal water loss (TEWL) measurement for 5 days and 21 female participants (50.33 ± 5.74 years) had undergone a skin hydration evaluation for 4 weeks. TEWL and skin hydration were evaluated using a Tewameter and the Epsilon Permittivity Imaging System, respectively. After applying the Cera-Glow sample, all participants recorded a satisfaction survey questionnaire (e.g., satisfaction, efficacy, and adverse reactions). RESULTS Application of Cera-Glow significantly improved transepidermal water loss induced by 1% (w/v) sodium lauryl sulfate (p < 0.05-0.01) and increased skin hydration (p < 0.01). Metabolic analysis suggested that Cera-Glow should contain beneficial gradients for skin barrier function. According to the questionnaire, most of participants were satisfied with the skin hydration improvement and efficacy of Cera-Glow. CONCLUSIONS Cera-Glow, ferment lysates of Lacticaseibacillus rhamnosus IDCC 3201, can significantly improve skin barrier function.
Collapse
|
2
|
NaCl-Assisted Temperature-Dependent Controllable Growth of Large-Area MoS 2 Crystals Using Confined-Space CVD. ACS OMEGA 2022; 7:30074-30086. [PMID: 36061644 PMCID: PMC9434612 DOI: 10.1021/acsomega.2c03108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Accepted: 08/10/2022] [Indexed: 06/15/2023]
Abstract
Due to its semiconducting nature, controlled growth of large-area chemical vapor deposition (CVD)-grown two-dimensional (2D) molybdenum disulfide (MoS2) has a lot of potential applications in photodetectors, sensors, and optoelectronics. Yet the controllable, large-area, and cost-effective growth of highly crystalline MoS2 remains a challenge. Confined-space CVD is a very promising method for the growth of highly crystalline MoS2 in a controlled manner. Herein, we report the large-scale growth of MoS2 with different morphologies using NaCl as a seeding promoter for confined-space CVD. Changes in the morphologies of MoS2 are reported by variation in the amount of seeding promoter, precursor ratio, and the growth temperature. Furthermore, the properties of the grown MoS2 are analyzed using optical microscopy, scanning electron microscopy (SEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDX), and atomic force microscopy (AFM). The electrical properties of the CVD-grown MoS2 show promising performance from fabricated field-effect transistors. This work provides new insight into the growth of large-area MoS2 and opens the way for its various optoelectronic and electronic applications.
Collapse
|
3
|
Integration of Reinforcement Learning and Model Predictive Control to Optimize Semi‐batch Bioreactor. AIChE J 2022. [DOI: 10.1002/aic.17658] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
|
4
|
Pretreatment and enzymatic saccharification of oak at high solids loadings to obtain high titers and high yields of sugars. BIORESOURCE TECHNOLOGY 2019; 284:391-397. [PMID: 30959376 DOI: 10.1016/j.biortech.2019.03.134] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 03/26/2019] [Accepted: 03/27/2019] [Indexed: 05/28/2023]
Abstract
Production of high-titer sugar from lignocellulose is important in terms of process economics of bio-based product industry. In this study, to obtain high titers and yields of sugars, we combined pretreatment and saccharification steps, both at high solids loadings. First, pretreatment of oak was optimized at a 30% (w/w) solids loading. The whole slurry of the pretreated oak was subjected to a fed-batch saccharification step at the final solids loading of 30%, to minimize loss of fermentable sugars and simplify the processes. As a result, high-titer sugars (157.5 g/L) consisting of 120.2 g/L of glucose and 37.3 g/L of xylose were obtained at 75.9% and 58.6%, respectively, of theoretical maximum yields, based on the initial glucan and xylan contents. Thus, through proper optimization processes of oak, the combination of pretreatment and saccharification at high solids loadings was effective in obtaining both high titers and high yields of sugars from lignocellulose.
Collapse
|
5
|
Efficacy of pretreating oil palm fronds with an acid-base mixture catalyst. BIORESOURCE TECHNOLOGY 2017; 236:234-237. [PMID: 28416125 DOI: 10.1016/j.biortech.2017.03.191] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 03/30/2017] [Accepted: 03/31/2017] [Indexed: 06/07/2023]
Abstract
Oil palm fronds are abundant but recalcitrant to chemical pretreatment. Herein, an acid-base mixture was applied as a catalyst to efficiently pretreat oil palm fronds. Optimized conditions for the pretreatment were a 0.1M acidic acid-base mixture and 3min ramping to 190°C and 12min holding. The oil palm fronds pretreated and washed with the acid-base mixture exhibited an enzymatic digestibility of 85% by 15 FPU Accellerase 1000/g glucan after 72h hydrolysis, which was significantly higher than the enzymatic digestibilities obtained by acid or alkali pretreatment alone. This could be attributed to the synergistic actions of the acid and base, producing an 87% glucose recovery with 100% and 40.3% removal of xylan and lignin, respectively, from the solids. Therefore, an acid-base mixture can be a feasible catalyst to deconstruct oil palm fronds for sugar production.
Collapse
|
6
|
Randomized clinical trial of preoperative skin antisepsis with chlorhexidine gluconate or povidone–iodine. Br J Surg 2016; 104:e145-e150. [DOI: 10.1002/bjs.10395] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Revised: 07/04/2016] [Accepted: 09/06/2016] [Indexed: 11/11/2022]
Abstract
Abstract
Background
Skin antiseptic agents are used to prevent surgical-site infection (SSI); few trials have reported the superiority of any specific agent in clean-contaminated abdominal surgery. This RCT was designed to compare the effectiveness of chlorhexidine gluconate and povidone–iodine.
Methods
Consecutive patients who underwent clean-contaminated upper gastrointestinal or hepatobiliary–pancreatic open surgery between 2011 and 2014 were assigned randomly to either chlorhexidine gluconate or povidone–iodine. The primary endpoint was the occurrence of SSI within 30 days of surgery. Secondary endpoints included causative organisms and risk factors for SSI.
Results
A total of 534 patients were randomized; 31 (5·8 per cent) developed an SSI. There was no difference in the overall SSI rate in the chlorhexidine gluconate and povidone–iodine groups: 15 of 267 (5·6 per cent) and 16 of 267 (6·0 per cent) respectively (P = 0·853). The most common causative organism was Enterococcus faecalis. In subgroup analysis, biliary–pancreatic surgery had a higher SSI rate (26 of 127, 20·5 per cent) than upper gastrointestinal (2 of 204, 1·0 per cent) and hepatic (3 of 203, 1·5 per cent) resection. Both age (60 years and over) and type of incision were associated with the risk of SSI.
Conclusion
No difference was detected between chlorhexidine gluconate and povidone–iodine antiseptics for prevention of SSI. Registration number: NCT01495117 (http://www.clinicaltrials.gov).
Collapse
|
7
|
Note: Near infrared interferometric silicon wafer metrology. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2016; 87:046106. [PMID: 27131722 DOI: 10.1063/1.4948292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
In this investigation, two near infrared (NIR) interferometric techniques for silicon wafer metrology are described and verified with experimental results. Based on the transparent characteristic of NIR light to a silicon wafer, the fiber based spectrally resolved interferometry can measure the optical thickness of the wafer and stitching low coherence scanning interferometry can reconstruct entire surfaces of the wafer.
Collapse
|
8
|
Abstract
Undoped InAs and Si-doped InAs nanowires with stacking faults and twins were synthesized by catalyst-free molecular beam epitaxy and their thermoelectric enhancements due to planar defects were experimentally and theoretically demonstrated.
Collapse
|
9
|
Abstract
A solid solution alloy of Ir–Au, theoretically predicted to be an excellent catalyst, equivalent to Pt, has been experimentally synthesized.
Collapse
|
10
|
Combination of high solids loading pretreatment and ethanol fermentation of whole slurry of pretreated rice straw to obtain high ethanol titers and yields. BIORESOURCE TECHNOLOGY 2015; 198:861-866. [PMID: 26461793 DOI: 10.1016/j.biortech.2015.09.102] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2015] [Revised: 09/19/2015] [Accepted: 09/21/2015] [Indexed: 06/05/2023]
Abstract
In cellulosic ethanol production using lignocellulose, an increase in biomass solids loading during the pretreatment process significantly affects the final ethanol titer and the production cost. In this study, pretreatment using rice straw at high solids loading (20% (w/v)) was evaluated, using maleic acid as a catalyst. After pretreatment at optimal conditions of 190°C, 20 min, and 0.2% or 5% (w/v) maleic acid, the highest enzymatic digestibility obtained was over 80%. Simultaneous saccharification and fermentation (SSF) of the whole slurry of pretreated rice straw in the presence of activated carbon to separate inhibitory compounds generated a high ethanol yield of 62.8%, based on the initial glucan in unpretreated rice straw. These findings suggest that high solids loading pretreatment using maleic acid and SSF of the whole slurry of pretreated rice straw can be combined to improve the process economics of ethanol production.
Collapse
|
11
|
Mimicking the Fenton reaction-induced wood decay by fungi for pretreatment of lignocellulose. BIORESOURCE TECHNOLOGY 2015; 179:467-472. [PMID: 25575206 DOI: 10.1016/j.biortech.2014.12.069] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2014] [Revised: 12/14/2014] [Accepted: 12/21/2014] [Indexed: 05/22/2023]
Abstract
In this study, the Fenton reaction, which is naturally used by fungi for wood decay, was employed to pretreat rice straw and increase the enzymatic digestibility for the saccharification of lignocellulosic biomass. Using an optimized Fenton's reagent (FeCl3 and H2O2) for pretreatment, an enzymatic digestibility that was 93.2% of the theoretical glucose yield was obtained. This is the first report of the application of the Fenton reaction to lignocellulose pretreatment at a moderate temperature (i.e., 25°C) and with a relatively high loading of biomass (i.e., 10% (w/v)). Substantial improvement in the process economics of cellulosic fuel and chemical production can be achieved by replacing the conventional pretreatment with this Fenton-mimicking process.
Collapse
|
12
|
Galvanic synthesis of three-dimensional and hollow metallic nanostructures. NANOSCALE RESEARCH LETTERS 2014; 9:2403. [PMID: 26088979 PMCID: PMC4493846 DOI: 10.1186/1556-276x-9-679] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Accepted: 12/04/2014] [Indexed: 05/25/2023]
Abstract
We report a low-cost, facile, and template-free electrochemical method of synthesizing three-dimensional (3D) hollow metallic nanostructures. The 3D nanoporous gold (3D-NPG) nanostructures were synthesized by a galvanic replacement reaction (GRR) using the different reduction potentials of silver and gold; hemispherical silver nanoislands were electrochemically deposited on cathodic substrates by a reverse-pulse potentiodynamic method without templates and then nanoporous gold layer replicated the shape of silver islands during the GRR process in an ultra-dilute electrolyte of gold(III) chloride trihydrate. Finally, the wet etching process of remaining silver resulted in the formation of 3D-NPG. During the GRR process, the application of bias voltage to the cathode decreased the porosity of 3D-NPG in the voltage range of 0.2 to -0.62 V. And the GRR process of silver nanoislands was also applicable to fabrication of the 3D hollow nanostructures of platinum and palladium. The 3D-NPG nanostructures were found to effectively enhance the SERS sensitivity of rhodamine 6G (R6G) molecules with a concentration up to 10(-8) M.
Collapse
|
13
|
Control of mesenchymal stem cell phenotype and differentiation depending on cell adhesion mechanism. Eur Cell Mater 2014; 28:387-403. [PMID: 25422949 DOI: 10.22203/ecm.v028a27] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Control of cell-matrix adhesion has become an important issue in the regulation of stem cell function. In this study, a maltose-binding protein (MBP)-linked basic fibroblast growth factor (FGF2)-immobilised polystyrene surface (PS-MBP-FGF2) was applied as an artificial matrix to regulate integrin-mediated signalling. We sought to characterise human mesenchymal-stem cell (hMSC) behaviour in response to two different mechanisms of cell adhesion; (i) FGF2-heparan sulphate proteoglycan (HSPG)-mediated adhesion vs. (ii) fibronectin (FN)-integrin-mediated adhesion. Heparin inhibited hMSC adhesion to PS-MBP-FGF2 but not to FN-coated surface. The phosphorylation of focal adhesion kinase, cytoskeletal re-organisation, and cell proliferation were restricted in hMSCs adhering to PS-MBP-FGF2 compared to FN-coated surface. Expression of MSC markers, such as CD105, CD90 and CD166, decreased in hMSCs expanded on PS-MBP-FGF2 compared to expression in cells expanded on FN-coated surface. hMSCs that were expanded on FN-coated surface differentiated into osteogenic and adipogenic cells more readily than those that were expanded on PS-MBP-FGF2. Furthermore, we characterised the N-linked glycan structures of hMSCs depending on the cell adhesion mechanism using mass spectrometry (MS)-based quantitative techniques. MS analysis revealed that 2,3-sialylated glycans, a potential marker of stem cell function, were more abundant on hMSCs expanded on FN-coated surface than on those expanded on PS-MBP-FGF2. Thus, the differentiation potential of hMSCs is controlled by the type of adhesion substrate that might provide an idea for the design of biomaterials to control stem cell fate. Elucidation of the glycan structure on the cell membrane may help characterise hMSC function.
Collapse
|
14
|
Twin-driven thermoelectric figure-of-merit enhancement of Bi2Te3 nanowires. NANOSCALE 2014; 6:6158-65. [PMID: 24788482 DOI: 10.1039/c4nr00191e] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Thermoelectric figure-of-merits (ZT) are enhanced or degraded by crystal defects such as twins and excess atoms that are correlated with thermal conductivity (k) and carrier concentration (n). For Bi2Te3, it is unclear whether the crystal defects can enhance ZT without a degradation in the thermopower factor. In the present study, n-type Bi2Te3 nanowires (NWs) are electrochemically synthesized to have twin-free (TF) or twin-containing (TC) microstructures with a ZT of 0.10 and 0.08, respectively, at 300 K. The ZTs of TF and TC NWs remarkably increase up to 0.21 and 0.31, when heat-treatments cause n-reduction and twins induce phonon scattering, as follows: first, the enhancement of the Seebeck coefficient from -70 to -98 μV K(-1) for TF NWs and from -57 to -143 μV K(-1) for TC NWs, by virtue of n-reduction; secondly, twin-driven k-reduction from 1.9 to 1.4 W m(-1) K(-1) of TC NWs, while the k of TF NWs increases from 2.3 to 2.6 W m(-1) K(-1) due to the enhanced carrier mobility. The lattice thermal conductivities of TC NW are lowered from 1.1 to 0.8 W m(-1) K(-1) by phonon scattering at twins. Density functional theory calculations indicate that twins do not significantly influence the Seebeck coefficient of Bi2Te3. It is strongly recommended that twins be incorporated with an optimum carrier concentration to enhance the ZT of Bi2Te3.
Collapse
|
15
|
Pharmacological profile of DA-6886, a novel 5-HT4 receptor agonist to accelerate colonic motor activity in mice. Eur J Pharmacol 2014; 735:115-22. [PMID: 24769304 DOI: 10.1016/j.ejphar.2014.03.061] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Revised: 03/27/2014] [Accepted: 03/31/2014] [Indexed: 02/07/2023]
Abstract
DA-6886, the gastrointestinal prokinetic benzamide derivative is a novel 5-HT4 receptor agonist being developed for the treatment of constipation-predominant irritable bowel syndrome (IBS-C). The purpose of this study was to characterize in vitro and in vivo pharmacological profile of DA-6886. We used various receptor binding assay, cAMP accumulation assay, organ bath experiment and colonic transit assay in normal and chemically constipated mice. DA-6886 exhibited high affinity and selectivity to human 5-HT4 receptor splice variants, with mean pKi of 7.1, 7.5, 7.9 for the human 5-HT4a, 5-HT4b and 5-HT4d, respectively. By contrast, DA-6886 did not show significant affinity for several receptors including dopamine D2 receptor, other 5-HT receptors except for 5-HT2B receptor (pKi value of 6.2). The affinity for 5-HT4 receptor was translated into functional agonist activity in Cos-7 cells expressing 5-HT4 receptor splice variants. Furthermore, DA-6886 induced relaxation of the rat oesophagus preparation (pEC50 value of 7.4) in a 5-HT4 receptor antagonist-sensitive manner. The evaluation of DA-6886 in CHO cells expressing hERG channels revealed that it inhibited hERG channel current with an pIC50 value of 4.3, indicating that the compound was 1000-fold more selective for the 5-HT4 receptor over hERG channels. In the normal ICR mice, oral administration of DA-6886 (0.4 and 2mg/kg) resulted in marked stimulation of colonic transit. Furthermore, in the loperamide-induced constipation mouse model, 2mg/kg of DA-6886 significantly improved the delay of colonic transit, similar to 10mg/kg of tegaserod. Taken together, DA-6886 is a highly potent and selective 5-HT4 receptor agonist to accelerate colonic transit in mice, which might be therapeutic agent having a favorable safety profile in the treatment of gastrointestinal motor disorders such as IBS-C and chronic constipation.
Collapse
|
16
|
Spin-induced band modifications of graphene through intercalation of magnetic iron atoms. NANOSCALE 2014; 6:3824-3829. [PMID: 24584481 DOI: 10.1039/c3nr04178f] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Intercalation of magnetic iron atoms through graphene formed on the SiC(0001) surface is found to induce significant changes in the electronic properties of graphene due mainly to the Fe-induced asymmetries in charge as well as spin distribution. From our synchrotron-based photoelectron spectroscopy data together with ab initio calculations, we observe that the Fe-induced charge asymmetry results in the formation of a quasi-free-standing bilayer graphene while the spin asymmetry drives multiple spin-split bands. We find that Fe adatoms are best intercalated upon annealing at 600 °C, exhibiting split linear π-bands, characteristic of a bilayer graphene, but much diffused. Subsequent changes in the C 1s, Si 2p, and Fe 3p core levels are consistently described in terms of Fe-intercalation. Our calculations together with a spin-dependent tight binding model ascribe the diffuse nature of the π-bands to the multiple spin-split bands originated from the spin-injected carbon atoms residing only in the lower graphene layer.
Collapse
|
17
|
Unusual congenital pulmonary anomaly with presumed left lung hypoplasia in a young dog. J Small Anim Pract 2014; 55:274-7. [PMID: 24628409 DOI: 10.1111/jsap.12192] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/23/2013] [Indexed: 11/28/2022]
Abstract
A seven-month-old, entire, male miniature schnauzer dog was referred with acute vomiting, inappetence and depression primarily as a result of a gastric foreign body (pine cones). During investigations, thoracic radiographs revealed increased volume of the right lung lobes, deviated cardiomediastinal structures and elevation of the heart from the sternum. Thoracic computed tomography revealed left cranial lung lobe hypoplasia and extension of the right cranial lung parenchyma across the midline to the left hemithorax. Branches of the right pulmonary vessels and bronchi also crossed the midline and extended to the left caudal lung lobe. These findings suggested that the right and left lungs were fused. In humans this finding is consistent with horseshoe lung, which is an uncommon congenital malformation. To the authors' knowledge, this case represents the first report of such a pulmonary anomaly in a dog.
Collapse
|
18
|
|
19
|
One-pot pretreatment, saccharification and ethanol fermentation of lignocellulose based on acid–base mixture pretreatment. RSC Adv 2014. [DOI: 10.1039/c4ra10092a] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
One-pot pretreatment, saccharification and ethanol fermentation of lignocellulose, which is based on acid–base mixture pretreament, will greatly reduces the overall processing costs not only for the production of cellulosic ethanol but also for the lignocellulose-based biorefinery.
Collapse
|
20
|
Electrochemical flow-based solution–solid growth of the Cu2O nanorod array: potential application to lithium ion batteries. Phys Chem Chem Phys 2014; 16:18226-32. [DOI: 10.1039/c4cp02049a] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Facile and template-free synthesis of the Cu2O nanorod array is realized by an electrochemical flow-based solution–solid method based on electrical field-driven filamentary anisotropy.
Collapse
|
21
|
Rational design of a structural framework with potential use to develop chemical reagents that target and modulate multiple facets of Alzheimer's disease. J Am Chem Soc 2013; 136:299-310. [PMID: 24397771 DOI: 10.1021/ja409801p] [Citation(s) in RCA: 150] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Alzheimer's disease (AD) is characterized by multiple, intertwined pathological features, including amyloid-β (Aβ) aggregation, metal ion dyshomeostasis, and oxidative stress. We report a novel compound (ML) prototype of a rationally designed molecule obtained by integrating structural elements for Aβ aggregation control, metal chelation, reactive oxygen species (ROS) regulation, and antioxidant activity within a single molecule. Chemical, biochemical, ion mobility mass spectrometric, and NMR studies indicate that the compound ML targets metal-free and metal-bound Aβ (metal-Aβ) species, suppresses Aβ aggregation in vitro, and diminishes toxicity induced by Aβ and metal-treated Aβ in living cells. Comparison of ML to its structural moieties (i.e., 4-(dimethylamino)phenol (DAP) and (8-aminoquinolin-2-yl)methanol (1)) for reactivity with Aβ and metal-Aβ suggests the synergy of incorporating structural components for both metal chelation and Aβ interaction. Moreover, ML is water-soluble and potentially brain permeable, as well as regulates the formation and presence of free radicals. Overall, we demonstrate that a rational structure-based design strategy can generate a small molecule that can target and modulate multiple factors, providing a new tool to uncover and address AD complexity.
Collapse
|
22
|
Preparation of an aqueous suspension of stabilized TiO2 nanoparticles in primary particle form. JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY 2013; 13:6153-6159. [PMID: 24205619 DOI: 10.1166/jnn.2013.7637] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
To prepare stabilized TiO2 nanoparticles (TiO2 NPs) in aqueous media as a suspension of the primary particles, we attempted to optimize the conditions for dispersing stable, aggregated TiO2 NPs (A-TiO2 NPs) in aqueous HCl/NaOH solutions or 5 mM pH buffered aqueous solutions. The A-TiO2 NPs with a hydrodynamic diameter (or DLS size) of 150 +/- 20 nm could be dispersed at high concentration (63.5 +/- 0.5 mg/ml) in a 5 mM phosphate buffer (PB) solution of pH 8, and a primary TiO2 (P-TiO2) NP suspension (1.2 +/- 0.3 mg/ml) with DLS size of 30 +/- 5 nm could be separated from the highly concentrated A-TiO2 NP suspension by sonication and subsequent centrifugation. It was observed by comparing the UV-Vis absorption spectra of the A-TiO2 and P-TiO2 NP suspensions that the extinction coefficient of the TiO2 NPs in the aqueous suspension depended on the degree of aggregation. The stabilized P-TiO2 NP suspension in aqueous solution can be used to study nanotoxicity as well as to characterize the physicochemical properties of TiO2 NPs.
Collapse
|
23
|
Biopersistence of silver nanoparticles in tissues from Sprague-Dawley rats. Part Fibre Toxicol 2013; 10:36. [PMID: 24059869 PMCID: PMC3734196 DOI: 10.1186/1743-8977-10-36] [Citation(s) in RCA: 161] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Accepted: 07/31/2013] [Indexed: 11/13/2022] Open
Abstract
Silver nanoparticles are known to be distributed in many tissues after oral or inhalation exposure. Thus, understanding the tissue clearance of such distributed nanoparticles is very important to understand the behavior of silver nanoparticles in vivo. For risk assessment purposes, easy clearance indicates a lower overall cumulative toxicity. Accordingly, to investigate the clearance of tissue silver concentrations following oral silver nanoparticle exposure, Sprague–Dawley rats were assigned to 3 groups: control, low dose (100 mg/kg body weight), and high dose (500 mg/kg body weight), and exposed to two different sizes of silver nanoparticles (average diameter 10 and 25 nm) over 28 days. Thereafter, the rats were allowed to recover for 4 months. Regardless of the silver nanoparticle size, the silver content in most tissues gradually decreased during the 4-month recovery period, indicating tissue clearance of the accumulated silver. The exceptions were the silver concentrations in the brain and testes, which did not clear well, even after the 4-month recovery period, indicating an obstruction in transporting the accumulated silver out of these tissues. Therefore, the results showed that the size of the silver nanoparticles did not affect their tissue distribution. Furthermore, biological barriers, such as the blood–brain barrier and blood-testis barrier, seemed to play an important role in the silver clearance from these tissues.
Collapse
|
24
|
Association between VEGF and eNOS gene polymorphisms and lumbar disc degeneration in a young Korean population. GENETICS AND MOLECULAR RESEARCH 2013; 12:2294-305. [PMID: 23884772 DOI: 10.4238/2013.july.8.10] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Disturbances in blood flow to intervertebral discs (IVD) play an important role in IVD degeneration. Vascular endothelial growth factor (VEGF) and endothelial nitric oxide synthase (eNOS) are extremely important angiogenic factors for vasodilation and neovascularization. We investigated the relationship between single nucleotide polymorphisms (SNPs) of the VEGF and eNOS genes and genetic susceptibility to lumbar IVD degeneration in a young adult Korean population. Two hundred and forty-one participants (aged 18 to 30 years), with or without low back pain, were selected for the study. Magnetic resonance imaging was made of the lumbar spine in all participants. The patient group (N = 102) had low back pain clinically and lumbar IVD degeneration radiographically. The control group (N = 139) included subjects with and without low back pain; all were negative radiographically for lumbar IVD degeneration. Using PCR-RFLP analysis, we analyzed VEGF (-2578C>A, -1154G>A, -634G>C, and 936C>T) and eNOS (-786T>C, 4a4b and 894G>T) SNPs. We made combined analyses of the genes and performed haplotype analyses. There were no significant differences in the genotype distribution of polymorphisms of VEGF and eNOS genes among patients and controls. However, the frequency of VEGF -2578CA +AA/-634CC combined genotypes was significantly higher in patients when compared with controls [odds ratio (OR) = 21.00; 95% confidence interval (CI) = 2.590- 170.240]. The frequencies of the -2578A/-1154A/-634C/936C (OR = 3.831; 95%CI = 1.068-13.742), -2578A/-1154A/-634C (OR = 3.356; 95%CI = 1.198-9.400), and -2578A/-634C/936C (OR = 10.820; 95%CI = 2.811-41.656) haplotypes were also significantly higher in patients than in controls. We conclude that the combined genotype VEGF -2578CA+AA/-634CC is a possible risk factor for IVD degeneration and the VEGF -2578A/-1154A/-634C/936C haplotype may increase the risk for development of IVD degeneration. Furthermore, the VEGF -634C allele appears to be associated with susceptibility to IVD degeneration.
Collapse
|
25
|
One-step large-scale synthesis of micrometer-sized silver nanosheets by a template-free electrochemical method. NANOSCALE RESEARCH LETTERS 2013; 8:248. [PMID: 23692676 PMCID: PMC3664087 DOI: 10.1186/1556-276x-8-248] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Accepted: 05/15/2013] [Indexed: 05/30/2023]
Abstract
We have synthesized micrometer-sized Ag nanosheets via a facile, one-step, template-free electrochemical deposition in an ultra-dilute silver nitrate aqueous electrolyte. The nanosheet growth was revealed to occur in three stages: (1) formation of polygonal Ag nuclei on a substrate, (2) growth of {112}-faceted nanowire from the nuclei, and (3) anisotropic growth of (111)-planar nanosheets, approximately 20 to 50 nm in thickness and 10 μm in width, in the <112>-direction. The vertical growth of the facet nanowire was induced by the strong interface anisotropy between the deposit and electrolyte due to the ultra-dilute concentration of electrolyte and high reduction potential. The thickness of Ag nanosheets was controllable by the adjustment of the reduction/oxidation potential and frequency of the reverse-pulse potentiodynamic mode.
Collapse
|
26
|
Gene expression profiling of kidneys from Sprague–Dawley rats following 12-week inhalation exposure to silver nanoparticles. Toxicol Mech Methods 2013; 23:437-48. [DOI: 10.3109/15376516.2013.780196] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
|
27
|
Template-free and filamentary growth of silver nanowires: application to anisotropic conductive transparent flexible electrodes. NANOSCALE 2013; 5:1864-1869. [PMID: 23348502 DOI: 10.1039/c2nr33056c] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Silver nanowires (NWs) are currently fabricated via template-free or template-assisted methods. The former is based on a medium-mediated anisotropic synthesis, which enables precursor atoms to be selectively adsorbed onto specific crystallographic planes, and the latter is performed via directional growth guided by preformed templates. These methods are costly and complicated. We outline a facile and low-cost approach for the electrochemical synthesis of silver NWs in a manner that is template- and surfactant-free and that provides control over the NW diameter in the range of 80 to 800 nm by the repetition of nucleation and dissolution. The nanowires vertically grow with the help of the interface anisotropy driven by a field enhancement at the tips of the islands nucleated on the substrate in ultra-dilute electrolytes (ca. 10(-5) M), which is similar to a lightning-rod effect. The silver nanowires of vertical configuration are utilized for fabrication of anisotropic conducting, transparent, and flexible films.
Collapse
|
28
|
Remarkable Solvent, Porphyrin Ligand, and Substrate Effects on Participation of Multiple Active Oxidants in Manganese(III) Porphyrin Catalyzed Oxidation Reactions. Chemistry 2012. [DOI: 10.1002/chem.201202640] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
29
|
Selective Fe2+Ion Recognition Using a Fluorescent Pyridinyl-benzoimidazole-derived Ionophore. B KOREAN CHEM SOC 2012. [DOI: 10.5012/bkcs.2012.33.11.3625] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|
30
|
Exploring the reactivity of flavonoid compounds with metal-associated amyloid-β species. Dalton Trans 2012; 41:6558-66. [PMID: 22437427 DOI: 10.1039/c2dt12207c] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Metal ions associated with amyloid-β (Aβ) peptides have been suggested to be involved in the development of Alzheimer's disease (AD), but this remains unclear and controversial. Some attempts to rationally design or select small molecules with structural moieties for metal chelation and Aβ interaction (i.e., bifunctionality) have been made to gain a better understanding of the hypothesis. In order to contribute to these efforts, four synthetic flavonoid derivatives FL1-FL4 were rationally selected according to the principles of bifunctionality and their abilities to chelate metal ions, interact with Aβ, inhibit metal-induced Aβ aggregation, scavenge radicals, and regulate the formation of reactive oxygen species (ROS) were studied using physical methods and biological assays. The compounds FL1-FL3 were able to chelate metal ions, but showed limited solubility in aqueous buffered solutions. In the case of FL4, which was most compatible with aqueous conditions, its binding affinities for Cu(2+) and Zn(2+) (nM and μM, respectively) were obtained through solution speciation studies. The direct interaction between FL4 and Aβ monomer was weak, which was monitored by NMR spectroscopy and mass spectrometry. Employing FL1-FL4, no noticeable inhibitory effect on metal-mediated Aβ aggregation was observed. Among FL1-FL4, FL3, having 3-OH, 4-oxo, and 4'-N(CH(3))(2) groups, exhibited similar antioxidant activity to the vitamin E analogue, Trolox, and ca. 60% reduction in the amount of hydrogen peroxide (H(2)O(2)) generated by Cu(2+)-Aβ in the presence of dioxygen (O(2)) and a reducing agent. Overall, the studies here suggest that although four flavonoid molecules were selected based on expected bifunctionality, their properties and metal-Aβ reactivity were varied depending on the structure differences, demonstrating that bifunctionality must be well tuned to afford desirable reactivity.
Collapse
|
31
|
Recovery from silver-nanoparticle-exposure-induced lung inflammation and lung function changes in Sprague Dawley rats. Nanotoxicology 2012; 7:169-80. [PMID: 22264098 DOI: 10.3109/17435390.2011.648223] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
In a previous study, the lung function, as indicated by the tidal volume, minute volume, and peak inspiration flow, decreased during 90 days of exposure to silver nanoparticles and was accompanied by inflammatory lesions in the lung morphology. Therefore, this study investigated the recovery from such lung function changes in rats following the cessation of 12 weeks of nanoparticle exposure. Male and female rats were exposed to silver nanoparticles (14-15 nm diameter) at concentrations of 0.66 × 10(6) particles/cm(3) (49 μg/m(3), low dose), 1.41 × 10(6) particles/cm(3) (117 μg/m(3), middle dose), and 3.24 × 10(6) particles/cm(3) (381 μg/m(3), high dose) for 6 h/day in an inhalation chamber for 12 weeks. The rats were then allowed to recover. The lung function was measured every week during the exposure period and after the cessation of exposure, plus animals were sacrificed after the 12-week exposure period, and 4 weeks and 12 weeks after the exposure cessation. An exposure-related lung function decrease was measured in the male rats after the 12-week exposure period and 12 weeks after the exposure cessation. In contrast, the female rats did not show a consistent lung function decrease either during the exposure period or following the exposure cessation. The histopathology showed a gradual recovery from the lung inflammation in the female rats, whereas the male rats in the high-dose group exhibited persistent inflammation throughout the 12-week recovery period. Therefore, the present results suggest a potential persistence of lung function changes and inflammation induced by silver nanoparticle exposure above the no observed adverse effect level.
Collapse
|
32
|
Construction of HgII complexes containing chelating 2,2′-dipyridylamine ligands: Anion effect, photoluminescence and catalytic activities. INORG CHEM COMMUN 2012. [DOI: 10.1016/j.inoche.2011.10.026] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|
33
|
Light-induced self-assemblies suitable for photodimerization and their light-induced [2+2] cycloaddition: Light as a control factor of crystal growth. Inorganica Chim Acta 2011. [DOI: 10.1016/j.ica.2011.07.042] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
34
|
Fluorescent chemosensor based-on naphthol–quinoline for selective detection of aluminum ions. Tetrahedron Lett 2011. [DOI: 10.1016/j.tetlet.2011.08.045] [Citation(s) in RCA: 149] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
35
|
|
36
|
Robust and Efficient Amide‐Based Nonheme Manganese(III) Hydrocarbon Oxidation Catalysts: Substrate and Solvent Effects on Involvement and Partition of Multiple Active Oxidants. Chemistry 2011; 17:7336-44. [DOI: 10.1002/chem.201003202] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2010] [Revised: 02/08/2011] [Indexed: 11/09/2022]
|
37
|
Novel CdII coordination polymers (1-D, 2-D to 3-D) constructed from 1,2-cyclohexanedicarboxylate and various bipyridyl ligands. J Mol Struct 2011. [DOI: 10.1016/j.molstruc.2011.03.046] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
38
|
Anion effects on the crystal structures of ZnII complexes containing 2,2′-bipyridine: Their photoluminescence and catalytic activities. Polyhedron 2011. [DOI: 10.1016/j.poly.2011.03.040] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
|
39
|
Mass imaging of iron oxide nanoparticles inside cells for in vitro cytotoxicity. JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY 2011; 11:638-641. [PMID: 21446514 DOI: 10.1166/jnn.2011.3273] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Time-of-flight secondary ion mass spectrometry (ToF-SIMS) imaging analysis was performed on murine macrophage cells treated with various concentrations of iron oxide (Fe3O4) nanoparticles, which are used as MRI contrast agents. First, murine macrophage cells were seeded on a slide glass for 24 hrs and treated with varying concentrations of Fe3O4 nanoparticles for 24 hrs. To expose a cross section of each cell and obtain a distribution of the nanoparticles inside the cells, the cells were sputtered using Bi ions after which the cross section of each cell was scanned and imaged using the focused cluster ion beam with a spatial resolution of 300 nm. Fe3O4 nanoparticles were found mainly in the cytoplasm region of the cells, not in the nucleus region of cells, suggesting that the uptake of the Fe3O4 nanoparticles were into the cytoplasm of cell, not into the nucleus of cell. Based on these observations, our protocol using mass imaging analysis would be a useful addition to the study of in vitro nanoparticle cytotoxicity.
Collapse
|
40
|
Development of multiplexed analysis for the photocatalytic activities of nanoparticles in aqueous suspension. Photochem Photobiol Sci 2011; 10:1979-82. [DOI: 10.1039/c1pp05244f] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
41
|
Anion effects on construction of ZnII compounds with a chelating ligand bis(2-pyridylmethyl)amine and their catalytic activities. Inorganica Chim Acta 2011. [DOI: 10.1016/j.ica.2010.11.029] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
42
|
1-D, 2-D and 3-D coordination polymers assembled from polynuclear CoII units based on the isophthalate(-2) ligand. Polyhedron 2010. [DOI: 10.1016/j.poly.2010.09.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
|
43
|
Pregnenolone sulfate enhances spontaneous glutamate release by inducing presynaptic Ca2+-induced Ca2+ release. Neuroscience 2010; 171:106-16. [PMID: 20816925 DOI: 10.1016/j.neuroscience.2010.07.057] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2010] [Revised: 07/27/2010] [Accepted: 07/27/2010] [Indexed: 01/08/2023]
Abstract
Pregnenolone sulfate (PS) acts as an excitatory neuromodulator and has a variety of neuropharmacological actions, such as memory enhancement and convulsant effects. In the present study, we investigated the effect of PS on glutamatergic spontaneous excitatory postsynaptic currents (sEPSCs) in acutely isolated dentate gyrus (DG) hilar neurons by use of a conventional whole-cell patch-clamp technique. PS significantly increased sEPSC frequency in a concentration-dependent manner without affecting the current amplitude, suggesting that PS acts presynaptically to increase the probability of spontaneous glutamate release. However, known molecular targets of PS, such as α7 nicotinic ACh, NMDA, σ1 receptors and voltage-dependent Ca(2+) channels, were not responsible for the PS-induced increase in sEPSC frequency. In contrast, the PS-induced increase in sEPSC frequency was completely occluded in a Ca(2+)-free external solution, and was significantly reduced by either the depletion of presynaptic Ca(2+) stores or the blockade of ryanodine receptors, suggesting that PS elicits Ca(2+)-induced Ca(2+) release (CICR) within glutamatergic nerve terminals. In addition, the PS-induced increase in sEPSC frequency was completely occluded by transient receptor potential (TRP) channel blockers. These data suggest that PS increases spontaneous glutamate release onto acutely isolated hilar neurons via presynaptic CICR, which was triggered by the influx of Ca(2+) through presynaptic TRP channels. The PS-induced modulation of excitatory transmission onto hilar neurons could have a broad impact on the excitability of hilar neurons and affect the pathophysiological functions mediated by the hippocampus.
Collapse
|
44
|
A case of multiple myeloma possibly cured by autologous blood stem cell transplantation. Intern Med J 2010; 40:314-5. [PMID: 20529044 DOI: 10.1111/j.1445-5994.2009.02157.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
45
|
|
46
|
|
47
|
Royal jelly enhances migration of human dermal fibroblasts with decreased levels of triglycerides and cholesterol in in vitro wound healing model. FASEB J 2010. [DOI: 10.1096/fasebj.24.1_supplement.922.6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
48
|
|
49
|
Extension of the Helmholtz-Smoluchowski velocity to the hydrophobic microchannels with velocity slip. LAB ON A CHIP 2009; 9:291-296. [PMID: 19107287 DOI: 10.1039/b808432g] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Electrokinetic flows through hydrophobic microchannels experience velocity slip at the microchannel wall, which affects volumetric flow rate and solute retention time. The usual method of predicting the volumetric flow rate and velocity profile for hydrophobic microchannels is to solve the Navier-Stokes equation and the Poisson-Boltzmann equation for the electric potential with the boundary condition of velocity slip expressed by the Navier slip coefficient, which is computationally demanding and defies analytic solutions. In the present investigation, we have devised a simple method of predicting the velocity profiles and volumetric flow rates of electrokinetic flows by extending the concept of the Helmholtz-Smoluchowski velocity to microchannels with Navier slip. The extended Helmholtz-Smoluchowski velocity is simple to use and yields accurate results as compared to the exact solutions. Employing the extended Helmholtz-Smoluchowski velocity, the analytical expressions for volumetric flow rate and velocity profile for electrokinetic flows through rectangular microchannels with Navier slip have been obtained at high values of zeta potential. The range of validity of the extended Helmholtz-Smoluchowski velocity is also investigated.
Collapse
|
50
|
Synthesis of uniform hollow oxide nanoparticles through nanoscale acid etching. NANO LETTERS 2008; 8:4252-8. [PMID: 19367964 DOI: 10.1021/nl8019467] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
We synthesized various hollow oxide nanoparticles from as-prepared MnO and iron oxide nanocrystals. Heating metal oxide nanocrystals dispersed in technical grade trioctylphosphine oxide (TOPO) at 300 degrees C for hours yielded hollow nanoparticles retaining the size and shape uniformity of the original nanocrystals. The method was highly reproducible and could be generalized to synthesize hollow oxide nanoparticles of various sizes, shapes, and compositions. Control experiments revealed that the impurities in technical grade TOPO, especially alkylphosphonic acid, were responsible for the etching of metal oxide nanocrystals to the hollow structures. Elemental mapping analysis revealed that the inward diffusion of phosphorus and the outward diffusion of metal took place in the intermediate stages during the etching process. The elemental analysis using XPS, EELS, and EDX showed that the hollow nanoparticles were amorphous metal oxides containing significant amount of phosphorus. The hollow nanoparticles synthesized from MnO and iron oxide nanocrystals were paramagnetic at room temperature and when dispersed in water showed spin relaxation enhancement effect for magnetic resonance imaging (MRI). Because of their morphology and magnetic property, the hollow nanoparticles would be utilized for multifunctional biomedical applications such as the drug delivery vehicles and the MRI contrast agents.
Collapse
|