Femtosecond gas-phase mega-electron-volt ultrafast electron diffraction

The development of ultrafast gas electron diffraction with nonrelativistic electrons has enabled the determination of molecular structures with atomic spatial resolution. It has, however, been challenging to break the picosecond temporal resolution barrier and achieve the goal that has long been envisioned-making space- and-time resolved molecular movies of chemical reaction in the gas-phase. Recently, an ultrafast electron diffraction (UED) apparatus using mega-electron-volt (MeV) electrons was developed at the SLAC National Accelerator Laboratory for imaging ultrafast structural dynamics of molecules in the gas phase. The SLAC gas-phase MeV UED has achieved 65 fs root mean square temporal resolution, 0.63 Å spatial resolution, and 0.22 Å-1 reciprocal-space resolution. Such high spatial-temporal resolution has enabled the capturing of real-time molecular movies of fundamental photochemical mechanisms, such as chemical bond breaking, ring opening, and a nuclear wave packet crossing a conical intersection. In this paper, the design that enables the high spatial-temporal resolution of the SLAC gas phase MeV UED is presented. The compact design of the differential pump section of the SLAC gas phase MeV UED realized five orders-of-magnitude vacuum isolation between the electron source and gas sample chamber. The spatial resolution, temporal resolution, and long-term stability of the apparatus are systematically characterized.

Short communication: Supply of methionine during late pregnancy enhances whole-blood innate immune response of Holstein calves partly through changes in mRNA abundance in polymorphonuclear leukocytes

The supply of methionine (Met) in late pregnancy can alter mRNA abundance of genes associated with metabolism and immune response in liver and polymorphonuclear leukocytes (PMN) of the neonatal calf. Whether prenatal supply of Met elicits postnatal effects on systemic inflammation and innate immune response of the calf is not well known. We investigated whether enhancing the maternal supply of Met via feeding ethyl-cellulose rumen-protected Met (RPM) was associated with differences in calf innate immune response mRNA abundance in PMN and systemic indicators of inflammation during the first 50 d of life. Calves (n = 14 per maternal diet) born to cows fed RPM at 0.09% of diet dry matter per day (MET) for the last 28 ± 2 d before calving or fed a control diet with no added Met (CON) were used. Blood for biomarker analysis and isolation of PMN for innate immune function assays and mRNA abundance was harvested at birth (before colostrum feeding) and at 7, 21 and 50 d of age. Whole blood was challenged with enteropathogenic bacteria (Escherichia coli 0118:H8) and phagocytosis and oxidative burst of neutrophils and monocytes were quantified via flow cytometry. Although concentration of haptoglobin and activity of myeloperoxidase among calves from both maternal groups increased markedly between 0 and 7 d of age followed by a decrease to baseline at d 21 the responses were lower in MET compared with CON calves. Nitric oxide concentration decreased markedly between 0 and 7 d regardless of maternal group but MET calves tended to have lower overall concentrations during the study. In vitro phagocytosis in stimulated neutrophils increased markedly over time in both CON and MET calves but responses were overall greater in MET calves. Oxidative burst in both neutrophils and monocytes increased over time regardless of maternal treatment. The mRNA abundance of lactate dehydrogenase (LDHA) signal transducer and activator of transcription 3 (STAT3) and S100 calcium binding protein A8 (S100A8) in PMN was overall greater in MET calves. Overall data suggest that increasing the maternal supply of Met during late pregnancy could affect the neonatal calf inflammatory status and innate immune response. Although changes in mRNA abundance could play a role in coordinating the immune response the exact mechanisms merit further study.

First Measurement of Near-Threshold J/ψ Exclusive Photoproduction off the Proton

We report on the measurement of the γp→J/ψp cross section from E_{γ}=11.8  GeV down to the threshold at 8.2 GeV using a tagged photon beam with the GlueX experiment. We find that the total cross section falls toward the threshold less steeply than expected from two-gluon exchange models. The differential cross section dσ/dt has an exponential slope of 1.67±0.39  GeV^{-2} at 10.7 GeV average energy. The LHCb pentaquark candidates P_{c}^{+} can be produced in the s channel of this reaction. We see no evidence for them and set model-dependent upper limits on their branching fractions B(P_{c}^{+}→J/ψp) and cross sections σ(γp→P_{c}^{+})×B(P_{c}^{+}→J/ψp).

Physical Properties and Theoretical Study of NixCo3-xO₄ (0 ≤ x ≤ 1.5) Nanostructures as High-Performance Electrode Materials for Supercapacitors

Study evaluates the electrochemical performance of off-stoichiometric Ni_xCo_3-xO₄ compounds. The off-stoichiometric samples were prepared via hydrothermal technique by systematically varying Co/Ni molar ratio. Physical and electrochemical properties of Ni_xCo_3-xO₄ were observed to be stoichiometry dependent. The increase in Ni/Co ratio in Ni_xCo_3-xO₄ leads to the morphological transformation from fibrous bundles to urchin like nanospheres with a concomitant increase in the surface area reaching up to 132 m2/g. The optimal specific capacitance of 225 F/g at a current density of 1 A/g and 524 F/g at 10 mV/s scan rate was observed of x 1.0 sample, with an increased retention capacity ∼120% measured at 2 A/g current density. The hybrid density functional theory (DFT) calculations of the electronic density of states identified Ni_1.0Co₂O₄ with optimal band-gap of 2.38 eV with an expectation of displaying higher electrocapacitive performance. Experimentally, Ni_0.92Co_2.08O₄ displayed superior electrocapacitive performance among all Ni/Co ratio in Ni_xCo_3-xO₄. The DFT study also predicted Ni preference to the octahedral site, which is in-line with the observed increase in ferromagnetic nature, decreased lattice parameter, and increased structural disorder with increasing Ni/Co ratio. The improved electrochemical performance of Ni_xCo_3-xO₄ (x > 0) is attributed to the mesoporous hierarchical structure, with a high electroactive surface which can effectively improve structural stability, and reduce the ionic and electron diffusion length. Compared to the pure Co₃O₄, the reduction of Co content in Ni_xCo_3-xO₄ is desired due to the high cost and toxicity of Co element.

Characterization of seminal plasma proteomic alterations associated with the IVF and rescue-ICSI pregnancy in assisted reproduction

BACKGROUND

Seminal plasma is a promising diagnostic fluid for male infertility. In assisted reproduction, the seminal plasma-based characteristics of normozoospermic men achieving successful clinical pregnancy through rescue intracytoplasmic sperm injection after in vitro fertilization failure remain unclear.

OBJECTIVE

To identify potential seminal plasma proteins to contribute to a new understanding of unexplained male factor infertility.

MATERIALS AND METHODS

An approach with isobaric tags for relative and absolute quantification labeling coupled with liquid chromatography matrix-assisted laser desorption ionization mass spectrometry was applied to investigate differentially expressed proteins in the seminal plasma of a rescue intracytoplasmic sperm injection pregnancy group versus an in vitro fertilization pregnancy group of normozoospermic men.

RESULT(S)

The present work revealed seventy-three differentially expressed seminal plasma proteins between the in vitro fertilization and rescue intracytoplasmic sperm injection groups. Forty-five proteins were upregulated, and 28 proteins were downregulated in the rescue intracytoplasmic sperm injection group compared with the in vitro fertilization group. Bioinformatics analyses showed that these altered proteins were involved in various functions, including the kallikrein-related proteolytic cascade, immune response, and heparin binding. Furthermore, the validity of the proteomic results was verified by Western blot analysis of the proteins (lactoferrin [LTF], fibronectin [FN1], creatine kinase B type [CKB], kallikrein-2 [KLK2], aminopeptidase N [ANPEP], extracellular matrix protein 1 [ECM1], glycodelin [PAEP], alpha-1-antitrypsin [SERPINA1], and semenogelin-1 [SEMG1]) and immunofluorescence. Moreover, 16% of the seminal plasma proteins identified in the present work have not been reported in previous studies.

DISCUSSION

This panel of altered seminal plasma proteins associated with unexplained male factor infertility might have clinical relevance and may be useful in the diagnosis and prognosis of idiopathic infertility in in vitro fertilization.

CONCLUSIONS

Our work not only provides a new complementary high-confidence dataset of seminal plasma proteins but also shines new light onto the molecular characteristics of seminal plasma from normozoospermic men with different assisted reproductive outcomes.

KrasG12D-LOH promotes malignant biological behavior and energy metabolism of pancreatic ductal adenocarcinoma cells through the mTOR signaling pathway

Oncogenic Kras with loss of heterozygosity (LOH) is frequently detected in various tumours. However, the exact function and mechanism by which KrasG12D-LOH operates remain unclear. Therefore, the current study investigated the effect of KrasG12D-LOH on the malignant phenotype of pancreatic ductal adenocarcinoma (PDAC) cells. Our investigation revealed that KrasG12D-LOH is associated with increased proliferation, invasion and reduced apoptosis in PDAC cells. The results also exhibited enhanced glycolytic phenotype of KrasG12D-LOH PDAC cells. Hyperactive mTOR plays a significant role in the initiation and maintenance of tumors. To investigate the correlation between KrasG12D-LOH and mTOR, the mTOR signaling pathway was detected by western blot analysis. We found that KrasG12D-LOH up-regulated Akt, AMPK, REDD1 and mTOR in PDAC cells. In summary, our results demonstrated that KrasG12D-LOH promotes oncogenic Kras-induced PDAC by regulating energy metabolism and mTOR signaling pathway. These data may provide novel therapeutic perspectives for PDAC.

[The effect of perioperative fluid therapy on early postoperative pulmonary complications after orthotopic liver transplantation]

Objective: To investigate the effect of perioperative fluid therapy on early postoperative pulmonary complication (PPC) after orthotopic liver transplantation (OLT). Methods: The clinical data of 132 patients who underwent OLT in the First Affiliated Hospital of Xi'an Jiaotong University from April 2016 to December 2017 were analyzed retrospectively. These patients included 96 males and 36 females, aged (47.3±9.6) years (range: 24-69 years). Based on the clinical manifestations, laboratory and imaging findings of patients in ICU and PPC occurrence within 7 days after OLT surgery, the patients were divided into 2 groups: non-PPC group and PPC group. Univariate and multivariate logistic regression analyses were used to evaluate the association between perioperative variables and PPC. The Kaplan-Meier method was used to estimate cumulative survival of recipients with or without PPC within 2-years. Results: During the follow-up, 11 patients (8.3%) died and 72 patients (54.5%) developed PPC after operation. There were 34 cases, 6 cases, 3 cases, 4 cases, 15 cases, 6 cases and 4 cases of only pleural effusion, only pulmonary edema, only pneumonia, pleural effusion with pneumonia, pleural effusion with pulmonary edema, pleural effusion with atelectasis, and pleural effusion with pneumonia and pneumonia in PPC, respectively. Univariate analysis showed that the preoperative factors (model for end-stage liver disease score), the intra-operative factors (duration of surgery, total infusion volume, total blood products) and the postoperative cumulative fluid balance within the first 24 h, 48 h, and 72 h were the prognosis factors of PPC (P<0.05). At least two out of the first three postoperative days with a fluid balance of ≤-500 ml was a protective factor. Using multivariate analysis by Logistic regression, only the red blood units >10 U (OR=3.55, 95% CI: 1.35-9.26, P=0.010) and the cumulative fluid intake >12 L (OR=2.98, 95% CI: 1.14-7.80, P=0.026) within the first 72 h after operation were independent prognosis factors of PPC after OLT. Kaplan-Meier analysis showed that the cumulative survival rate was lower in PPC group than that in non-PPC group (χ(2)=6.590, P=0.01). Conclusion: Massive red blood cell transfusion and the cumulative fluid volume >12 L during perioperative 72 hours are independent prognosis factors of PPC after OLT.

Li(Cd,Mn)P: a new cadmium based diluted ferromagnetic semiconductor with independent spin & charge doping

We report a new diluted ferromagnetic semiconductor Li_1+y(Cd,Mn)P, wherein carrier is doped via excess Li while spin is doped by isovalence substitution of Mn²⁺ into Cd²⁺. The extended Cd 4d-orbitals lead to more itinerant characters of Li_1+y(Cd,Mn)P than that of analogous Li_1+y(Zn,Mn)P. A higher Curie temperature of 45 K than that for Li_1+y(Zn,Mn)P is obtained in Li_1+y(Cd,Mn)P polycrystalline samples by Arrott plot technique. The p-type carriers are determined by Hall effect measurements. The first principle calculations and X-ray diffraction measurements indicate that occupation of excess Li is at Cd sites rather than the interstitial site. Consequently holes are doped by excess Li substitution. More interestingly Li_1+y(Cd,Mn)P shows a very low coercive field (<100 Oe) and giant negative magnetoresistance (~80%) in ferromagnetic state that will benefit potential spintronics applications.

Vegetarians have a lower fasting insulin level and higher insulin sensitivity than matched omnivores: A cross-sectional study

BACKGROUND AND AIMS

Potential associations of vegetarian diet patterns with fasting insulin (FI) and insulin sensitivity remain unclear. We aimed to investigate whether vegetarian diets were associated with FI and insulin sensitivity in a cross-sectional study in Chinese vegetarians and matched omnivores and then to test whether it is independent of body mass index (BMI).

METHODS AND RESULTS

This study included 279 vegetarians (73 vegans, 206 lacto-ovo-vegetarians) and 279 age- and sex-matched omnivores. Fasting blood glucose (FG) and FI concentrations were measured, and β-cell function (HOMA-β) and insulin resistance index (HOMA-IR) were used to evaluate insulin sensitivity. All blood glucose and insulin sensitivity indices were naturally log-transformed, and multiple-linear regression was used to determine the association between vegetarian diet patterns and insulin sensitivity after adjusting for confounders including BMI, visceral fat area, physical activity, sedentary time, income, alcohol consumption, and daily dietary intakes of macronutrients. Compared to omnivores, both vegan diet [β = -0.25, 95% CI: (-0.38, -0.14)] and lacto-ovo-vegetarian diet [β = -0.10, 95% CI: (-0.18, -0.01)] were negatively associated with HOMA-IR after adjusting for BMI. Vegan diet remained negatively associated with FI [β = -0.16, 95% CI: (-0.30, -0.01)] and HOMA-IR [β = -0.17, 95% CI: (-0.32, -0.03)] after adjusting for all confounders.

CONCLUSION

Vegetarian diet, especially vegan diet, is negatively associated with FI and IR, independent of BMI.

Silibinin attenuates Streptococcus suis serotype 2 virulence by targeting suilysin

AIMS

To determine the antivirulence properties of silibinin against suilysin (SLY), a virulence factor of Streptococcus suis serotype 2 (SS2) that plays an important role in the pathogenesis of S. suis infection and its protective effect against SS2 infection in a mouse model.

METHODS AND RESULTS

Susceptibility testing, haemolysis assay and Western blot assays were employed to evaluate the performance of silibinin on SLY pore-forming activity. Cytotoxicity assays and mouse infection tests were also performed to determine the efficacy of silibinin against SS2 infection. The results showed that silibinin, a flavonoid with little anti-S. suis activity, was identified to be a potent antagonist of SLY-mediated haemolysis through the inhibition of its oligomerization. Treatment with silibinin reduced S. suis-induced cytotoxicity in macrophages (J774 cells). In addition, S. suis-infected mice that received silibinin showed a lower bacterial burden.

CONCLUSIONS

Our results demonstrated that silibinin is a promising candidate for the development of antivirulence therapeutic agents to treat S. suis infections.

SIGNIFICANCE AND IMPACT OF THE STUDY

The antivirulent property of silibinin against SS2 by targeting SLY provides the possibility for the future pharmaceutical application of silibinin to prevent and treat S. suis infection.

Application of High-throughput Sequencing in Researches of Cadaveric Microorganisms and Postmortem Interval Estimation

Necrobiome is the main factor causing the cadaver decomposition. Studying the microbial succession during decomposition is one of the main tasks of forensic microbiology. The interactive relationships among cadaver, environment and microorganisms are complicated. The microbial succession study relies on macroscopic monitoring of community composition and the diversity change in each decomposition stage. With the maturity and development of high-throughput sequencing （HTS）, the structure and diversity of microbial communities in different environments have been successively revealed. A new breakthrough to explore the cadaveric microorganisms has been opened as well. It has become the research hotspots in forensic microbiology to reveal the microbial succession in the process of cadaver decomposition and to interpret the essence of various decomposition phenomena by using HTS, which can provide a new reference for postmortem interval （PMI） estimation. The present paper reviews studies on PMI estimation by using cadaveric microorganism. Problems and application prospects of forensic microbiology studies are discussed on the basis of the current application of HTS technology in the exploration of microbial succession.

Enhanced energy gain in a dielectric laser accelerator using a tilted pulse front laser

Using an 800 nm, 45 fs pulse-front-tilted laser we demonstrate a record 315 keV energy gain in a dual grating dielectric laser accelerator (DLA) and average accelerating gradients of 560 MV/m over 0.5 mm. These results open a new regime in DLA characterized by significant evolution of the beam distribution in the longitudinal phase space, corresponding to > 1/4 of a synchrotron oscillation. By tilting the laser wavefront we control the resonant velocity of the DLA and observe a net energy gain, indicating that a tapered optical phase could be used to achieve very high energy gain.

Determination of the electron-lattice coupling strength of copper with ultrafast MeV electron diffraction

Electron-lattice coupling strength governs the energy transfer between electrons and the lattice and is important for understanding the material behavior under highly non-equilibrium conditions. Here we report the results of employing time-resolved electron diffraction at MeV energies to directly study the electron-lattice coupling strength in 40-nm-thick polycrystalline copper excited by femtosecond optical lasers. The temporal evolution of lattice temperature at various pump fluence conditions were obtained from the measurements of the Debye-Waller decay of multiple diffraction peaks. We observed the temperature dependence of the electron-lattice relaxation time which is a result of the temperature dependence of electron heat capacity. Comparison with two-temperature model simulations reveals an electron-lattice coupling strength of (0.9 ± 0.1) × 10¹⁷ W/m³/K for copper.

An interlocked flexible piezoresistive sensor with 3D micropyramidal structures for electronic skin applications

The development of flexible pressure sensors with human-like sensing capabilities is an emerging field due to their wide range of applications from human robot interactions to wearable electronics. Piezoresistive sensors respond to externally induced mechanical stimuli through changes in their electrical resistance. The current state-of-the-art piezoresistive sensors are mainly constructed via dispersion of conductive nanofillers in an elastomer matrix making their performance strongly reliable on the degree of dispersion. Alternatively, changes in the contact area of conductive elastomers result in higher sensitivity and more tunable variables. Herein, an interlocked sensor comprising two flexible layers of 3D pyramidal microstructures is fabricated with a thin layer of carbon nanotubes deposited onto the micropatterns. The introduced array of micropyramids with varying height and pitch sizes allows for higher changes in the contact area upon applying an external load. The results indicate that the height and pitch of the structures together with a newly defined variable, the critical dimension, affect the sensor's sensitivity. An optimal performance is observed for minimized values of the critical dimension. Furthermore, to verify the obtained results, a finite-element-assisted analytical constriction-resistance model is used to capture the piezoresistive response of the sensor. The theoretical results show the high tracking ability of their experimental counterparts.