From 2e- to 4e- pathway in the alkaline oxygen reduction reaction on Au(100): Kinetic circumvention of the volcano curve.

We report the free energy barriers for the elementary reactions in the 2e- and 4e- oxygen reduction reaction (ORR) steps on Au(100) in an alkaline solution. Due to the weak adsorption energy of O2 on Au(100), the barrier for the association channel is very low, and the 2e- pathway is clearly favored, while the barrier for the O-O dissociation channel is significantly higher at 0.5 eV. Above 0.7 V reversible hydrogen electrode (RHE), the association channel becomes thermodynamically unfavorable, which opens up the O-O dissociation channel, leading to the 4e- pathway. The low adsorption energy of oxygenated species on Au is now an advantage, and residue ORR current can be observed up to the 1.0-1.2 V region (RHE). In contrast, the O-O dissociation barrier on Au(111) is significantly higher, at close to 0.9 eV, due to coupling with surface reorganization, which explains the lower ORR activity on Au(111) than that on Au(100). In combination with the previously suggested outer sphere electron transfer to O2 for its initial adsorption, these results provide a consistent explanation for the features in the experimentally measured polarization curve for the alkaline ORR on Au(100) and demonstrate an ORR mechanism distinct from that on Pt(111). It also highlights the importance to consider the spin state of O2 in ORR and to understand the activation barriers, in addition to the adsorption energies, to account for the features observed in electrochemical measurements.

Calcitonin gene-related peptide inhibits neuronal apoptosis in heatstroke rats via PKA/p-CREB pathway.

PURPOSE: The incidence of heatstroke (HS) is not particularly high; however, once it occurs, the consequences are serious. It is reported that calcitonin gene-related peptide (CGRP) is protective against brain injury in HS rats, but detailed molecular mechanisms need to be further investigated. In this study, we further explored whether CGRP inhibited neuronal apoptosis in HS rats via protein kinase A (PKA)/p-cAMP response element-binding protein (p-CREB) pathway. METHODS: We established a HS rat model in a pre-warmed artificial climate chamber with a temperature of (35.5 ± 0.5) °C and a relative humidity of 60% ± 5%. Heatstress was stopped once core body temperature reaches above 41 °C. A total of 25 rats were randomly divided into 5 groups with 5 animals each: control group, HS group, HS+CGRP group, HS+CGRP antagonist (CGRP8-37) group, and HS+CGRP+PKA/p-CREB pathway blocker (H89) group. A bolus injection of CGRP was administered to each rat in HS+CGRP group, CGRP8-37 (antagonist of CGRP) in HS+CGRP8-37 group, and CGRP with H89 in HS+CGRP+H89 group. Electroencephalograms were recorded and the serum concentration of S100B, neuron-specific enolase (NSE), neuron apoptosis, activated caspase-3 and CGRP expression, as well as pathological morphology of brain tissue were detected at 2 h, 6 h, and 24 h after HS in vivo. The expression of PKA, p-CREB, and Bcl-2 in rat neurons were also detected at 2 h after HS in vitro. Exogenous CGRP, CGRP8-37, or H89 were used to determine whether CGRP plays a protective role in brain injury via PKA/p-CREB pathway. The unpaired t-test was used between the 2 samples, and the mean ± SD was used for multiple samples. Double-tailed p < 0.05 was considered statistically significant. RESULTS: Electroencephalogram showed significant alteration of θ (54.50 ± 11.51 vs. 31.30 ± 8.71, F = 6.790, p = 0.005) and α wave (16.60 ± 3.21 vs. 35.40 ± 11.28, F = 4.549, p = 0.020) in HS group compared to the control group 2 h after HS. The results of triphosphate gap terminal labeling (TUNEL) showed that the neuronal apoptosis of HS rats was increased in the cortex (9.67 ± 3.16 vs. 1.80 ± 1.10, F = 11.002, p = 0.001) and hippocampus (15.73 ± 8.92 vs. 2.00 ± 1.00, F = 4.089, p = 0.028), the expression of activated caspase-3 was increased in the cortex (61.76 ± 25.13 vs. 19.57 ± 17.88, F = 5.695, p = 0.009) and hippocampus (58.60 ± 23.30 vs. 17.80 ± 17.62, F = 4.628, p = 0.019); meanwhile the expression of serum NSE (5.77 ± 1.78 vs. 2.35 ± 0.56, F = 5.174, p = 0.013) and S100B (2.86 ± 0.69 vs. 1.35 ± 0.34, F = 10.982, p = 0.001) were increased significantly under HS. Exogenous CGRP decreased the concentrations of NSE and S100B, and activated the expression of caspase-3 (0.41 ± 0.09 vs. 0.23 ± 0.04, F = 32.387, p < 0.001) under HS; while CGRP8-37 increased NSE (3.99 ± 0.47 vs. 2.40 ± 0.50, F = 11.991, p = 0.000) and S100B (2.19 ± 0.43 vs. 1.42 ± 0.30, F = 4.078, p = 0.025), and activated the expression caspase-3 (0.79 ± 0.10 vs. 0.23 ± 0.04, F = 32.387, p < 0.001). For the cell experiment, CGRP increased Bcl-2 (2.01 ± 0.73 vs. 2.15 ± 0.74, F = 8.993, p < 0.001), PKA (0.88 ± 0.08 vs. 0.37 ± 0.14, F = 20.370, p < 0.001), and p-CREB (0.87 ± 0.13 vs. 0.29 ± 0.10, F = 16.759, p < 0.001) levels; while H89, a blocker of the PKA/p-CREB pathway reversed the expression. CONCLUSIONS: CGRP can protect against HS-induced neuron apoptosis via PKA/p-CREB pathway and reduce activation of caspase-3 by regulating Bcl-2. Thus CGRP may be a new target for the treatment of brain injury in HS.

Risk factors for brain injury in patients with exertional heatstroke: A 5-year experience.

PURPOSE: Minimal data exist on brain injury in patients with exertional heatstroke (EHS) in developing country. In this study, we explored the risk factors for brain injury induced by EHS 90-day after onset. METHODS: A retrospective cohort study of patients with EHS was conducted in the intensive care unit of the General Hospital of Southern Theater Command of PLA in China from April 2014 to June 2019. Patients were divided into non-brain injury (fully recovered) and brain injury groups (comprising deceased patients or those with neurological sequelae). The brain injury group was further subdivided into a death group and a sequela group for detailed analysis. General information, neurological performance and information on important organ injuries in the acute stage were recorded and analysed. Multivariable logistic regression was used to identify risk factors for brain injury after EHS and mortality risk factors for brain injury, and Kaplan-Meier survival curve was used to evaluate the effect of the neurological dysfunction on survival. RESULTS: Out of the 147 EHS patients, 117 were enrolled, of which 96 (82.1%) recovered, 13 (11.1%) died, and 8 (6.8%) experienced neurological sequelae. Statistically significant differences were found between non-brain injury and brain injury groups in age, hypotension, duration of consciousness disorders, time to drop core body temperature below 38.5°C, lymphocyte counts, platelet counts, procalcitonin, alanine aminotransferase, aspartate aminotransferase, creatinine, cystatin C, coagulation parameters, international normalized ratio, acute physiology and chronic health evaluation II scores, sequential organ failure assessment (SOFA) scores, and Glasgow coma scale scores (all p < 0.05). Multivariate logistic regression showed that age (OR = 1.090, 95% CI: 1.02 - 1.17, p = 0.008), time to drop core temperature (OR = 8.223, 95% CI: 2.30 - 29.40, p = 0.001), and SOFA scores (OR = 1.676, 95% CI: 1.29 - 2.18, p < 0.001) are independent risk factors for brain injury induced by EHS. The Kaplan-Meier curves suggest significantly prolonged survival (p < 0.001) in patients with early Glasgow coma scale score > 8 and duration of consciousness disorders ≤ 24 h. CONCLUSIONS: Advanced age, delayed cooling, and higher SOFA scores significantly increase the risk of brain injury post-EHS. These findings underscore the importance of rapid cooling and early assessment of organ failure to improve outcomes in EHS patients.

Determining Feynman Integrals with Only Input from Linear Algebra.

We find that all Feynman integrals (FIs), having any number of loops, can be completely determined once linear relations between FIs are provided. Therefore, FI computation is conceptually changed to a linear algebraic problem. Examples up to five loops are given to verify this observation. As a by-product, we obtain a powerful method to calculate perturbative corrections in quantum field theory.

Hong-Ou-Mandel Interference between Two Hyperentangled Photons Enables Observation of Symmetric and Antisymmetric Particle Exchange Phases.

Two-photon Hong-Ou-Mandel (HOM) interference is a fundamental quantum effect with no classical counterpart. The existing research on two-photon interference was mainly limited in one degree of freedom (DOF); hence, it is still a challenge to realize quantum interference in multiple DOFs. Here, we demonstrate HOM interference between two hyperentangled photons in two DOFs of polarization and orbital angular momentum (OAM) for all 16 hyperentangled Bell states. We observe hyperentangled two-photon interference with a bunching effect for ten symmetric states (nine boson-boson states and one fermion-fermion state) and an antibunching effect for six antisymmetric states (three boson-fermion states and three fermion-boson states). More interestingly, expanding the Hilbert space by introducing an extra DOF for two photons enables one to transfer the unmeasurable external phase in the initial DOF to a measurable internal phase in the expanded two DOFs. We directly measured the symmetric exchange phases being 0.012±0.002, 0.025±0.002, and 0.027±0.002 in radian for the three boson states in OAM and the antisymmetric exchange phase being 0.991π±0.002 in radian for the other fermion state, as theoretical predictions. Our Letter may not only pave the way for more wide applications of quantum interference, but also develop new technologies by expanding Hilbert space in more DOFs.

Effect mechanism of litter extract from Alternanthera philoxeroides on the selective absorption of heavy metal ions by amphoteric purple soil.

Plant litter causes a serious waste of resources. Thus, plant litter extract (LE) should be used in the soil remediation of heavy metals. In this study, different proportions of LE from the Alternanthera philoxeroides were used to modify dodecyl dimethyl betaine (BS)-modified purple soil (P). The basic physicochemical properties of LE + BS-modified Ps (LE + BS-Ps) were determined, and the microscopic morphology of LE + BS-Ps was studied by using scanning electron microscopy (SEM), energy dispersion spectroscopy (EDS), Fourier transform infrared (FTIR) spectroscopy, and specific surface area detection. The isothermal adsorption characteristics of heavy metal ions (Pb2+, Cu2+, and Cr6+) on different LE + BS-Ps were investigated by the batch method, and the effect mechanisms of temperature, pH, ionic strength, and LE + BS-P's property were compared. Results showed that the cation exchange capacity and specific surface area of LE + BS-Ps increased, pH of LE + BS-Ps decreased, and TOC of LE + BS-Ps increased first and then decreased with increasing proportion of LE. FTIR, SEM, and EDS results proved that LE was modified on the surface of BS-P. Langmuir and Freundlich models could be used to describe the adsorption isotherms of heavy metal ions on different LE + BS-Ps, and the fitting correlation of the Langmuir model was higher than that of the Freundlich model. The maximum adsorption capacity (qm) of Pb2+, Cu2+, and Cr6+ were 107.60-295.66, 133.00-342.11, and 33.59-75.41 mmol/kg, respectively. The qm of Pb2+, Cu2+, and Cr6+ on LE + BS-Ps all increased first and then decreased with increasing proportion of LE, and the peak value was observed in 20%LE + BS-Ps. High pH improved Pb2+ and Cu2+ adsorption but inhibited Cr6+ adsorption. The adsorption amounts of Pb2+, Cu2+, and Cr6+ all increased first and then decreased with incresing ionic strength and were maintained at the maximum value of 0.1-0.2 mol/L. The Pb2+, Cu2+, and Cr6+ adsorption mechanisms on different LE + BS-Ps showed a positive temperature effect and presented spontaneous, exothermic and entropy-adding processes.

Severe COVID-19-associated sepsis is different from classical sepsis induced by pulmonary infection with carbapenem-resistant klebsiella pneumonia (CrKP).

PURPOSE: COVID-19 is also referred to as a typical viral septic pulmonary infection by 2019-nCoV. However, little is known regarding its characteristics in terms of systemic inflammation and organ injury, especially compared with classical bacterial sepsis. This article aims to investigate the clinical characteristics and prognosis between COVID-19-associated sepsis and classic bacterial-induced sepsis. METHODS: In this retrospective cohort study, septic patients with COVID-19 in the intensive care unit (ICU) of a government-designed therapy center in Shenzhen, China between January 14, 2020 and March 10, 2020, and septic patients induced by carbapenem-resistant klebsiella pneumonia (CrKP) admitted to the ICU of the Second People's Hospital of Shenzhen, China between January 1, 2014 and October 30, 2019 were enrolled. Demographic and clinical parameters including comorbidities, critical illness scores, treatment, and laboratory data, as well as prognosis were compared between the two groups. Risk factors for mortality and survival rate were analyzed using multivariable logistic regression and survival curve, respectively. RESULTS: A total of 107 patients with COVID-19 and 63 patients with CrKP were enrolled. A direct comparison between the two groups demonstrated more serious degrees of primary lung injury following 2019-nCoV infection (indicated by lower PaO2/FiO2), but milder systemic inflammatory response, lower sequential organ failure assessment score and better functions of the organs like heart, liver, kidney, coagulation, and circulation. However, the acquired immunosuppression presented in COVID-19 patients was more severe, which presented as lower lymphocyte counts (0.8×109/L vs. 0.9×109/L). Moreover, the proportion of COVID-19 patients treated with corticosteroid therapy and extracorporeal membrane oxygenation was larger compared with CrKP patients (78.5% vs. 38.1% and 6.5% vs. 0, respectively) who required less invasive mechanical ventilation (31.6% vs. 54.0%). The incidence of hospitalized mortality and length of ICU stay and total hospital stay were also lower or shorter in viral sepsis (12.1% vs. 39.7%, 6.5 days vs. 23.0 days and 21.0 days vs. 33.0 days, respectively) (all p < 0.001). Similar results were obtained after being adjusted by age, gender, comorbidity and PaO2/FiO2. Lymphocytopenia and high acute physiology and chronic health evaluation II scores were common risk factors for in-hospital death. While the death cases of COVID-19 sepsis mostly occurred at the later stages of patients' hospital stay. CONCLUSION: Critical COVID-19 shares clinical characteristics with classical bacterial sepsis, but the degree of systemic inflammatory response, secondary organ damage and mortality rate are less severe. However, following 2019-nCoV infection, the level of immunosuppression may be increased and thus induce in more death at the later stage of patients' hospitalstay.

[Influencing factors for the quality of bowel preparation with polyethylene glycol electrolyte powder combined with diet control before colonoscopy in children]. / å„¿ç«¥ç»“è‚ é•œæ£€æŸ¥å‰èšä¹™äºŒé†‡ç”µè§£è´¨æ•£è”åˆé¥®é£ŸæŽ§åˆ¶è‚ é“å‡†å¤‡è´¨é‡çš„å½±å“å› ç´ åˆ†æž.

OBJECTIVES: To investigate the influencing factors for the quality of bowel preparation before colonoscopy in children and the association of the interval from the last administration of laxative to the start of colonoscopy (shortly referred to as waiting time) with the quality of bowel preparation. METHODS: A retrospective analysis was performed for the children who were admitted to the Department of Gastroenterology, Children's Hospital of Nanjing Medical University, from January to November 2020, and received bowel preparation with polyethylene glycol electrolyte powder combined with diet control before colonoscopy. According to the score of Boston bowel preparation scale, they were divided into two groups: adequate bowel preparation group (n=337) and inadequate bowel preparation group (n=30). Related data were collected from the children in both groups, including general information, possible influencing factors for the quality of bowel preparation, adverse reactions associated with bowel preparation, duration of colonoscopy, and postoperative diagnosis. Univariate and multivariate analyses were used to explore the influencing factors for the quality of bowel preparation. RESULTS: The univariate analysis showed that age, body weight, and waiting time were associated with inadequate bowel preparation (P<0.05). The multivariate analysis showed that older age (OR=2.155, 95%CI: 1.087-4.273, P=0.028) and longer waiting time (OR=1.559, 95% CI: 1.191-2.041, P=0.001) were independent risk factors for inadequate bowel preparation. The receiver operating characteristic (ROC) curve analysis showed that the cut-off value of waiting time was 5.5 hours in determining whether bowel preparation was adequate or not, with a sensitivity of 90.0%, a specificity of 50.7%, and an area under the ROC curve of 0.708. After grouping based on waiting time, it was found that the incidence rate of inadequate bowel preparation in the ≥5.5 hours group was significantly higher than that in the <5.5 hours group [14.0% (27/193) vs 1.7% (3/174), P<0.001]. CONCLUSIONS: For children who use polyethylene glycol electrolyte powder combined with diet control for bowel preparation, older age is an independent risk factor for inadequate bowel preparation before colonoscopy, which may be associated with an insufficient dose of polyethylene glycol in older children. Longer waiting time is also an independent risk factor for inadequate bowel preparation, and it is recommended that the waiting time should not exceed 5.5 hours.

Evolution of the linker in microhydrated hydrogen dinitrate anions: From H+ to H5 O2.

Hydrogen dinitrate anion, HNO3 (NO3- ), is a proton-bound dimer with a very strong hydrogen bond. By employing ab initio molecular dynamics (AIMD) method, we studied the effects of the proton transfer and the rotation of the nitrates on the vibrational profiles of HNO3 (NO3- )(H2 O)n (n = 0-2). The AIMD results indicate that the structure of the n = 0 cluster is very flexible, even though its hydrogen bond is quite strong. Significant rotations around the hydrogen bond and frequent transfers of proton from HNO3 to NO3- are observed in AIMD simulations. Dynamic changes are therefore an important factor in understanding the broadening of vibrational features. For n = 1, the extent of structural fluctuation increases further, as H2 O could move around the anion while the HNO3 (NO3- ) core also goes through structural changes. Its vibrational spectrum can be understood as a mixture of many isomers visited during AIMD simulations. By n = 2, the structure is stabilized around one isomer, with the linker between the two nitrates being H5 O2+ , rather than H+ . Due to strong hydrogen bonds between nitrates and water molecules, this H5 O2+ takes the extraordinary structure with the H+ localized on one H2 O, rather than being shared. While this novel structure is stable during AIMD simulations, the dynamic fluctuations in hydrogen bond distances still produce significant broadening in its vibrational profile.

Microbial Oligosaccharides with Biomedical Applications.

Microbial oligosaccharides have been regarded as one of the most appealing natural products attributable to their potent and selective bioactivities, such as antimicrobial activity, inhibition of α-glucosidases and lipase, interference of cellular recognition and signal transduction, and disruption of cell wall biosynthesis. Accordingly, a handful of bioactive oligosaccharides have been developed for the treatment of bacterial infections and type II diabetes mellitus. Given that naturally occurring oligosaccharides have increasingly gained recognition in recent years, a comprehensive review is needed. The current review highlights the chemical structures, biological activities and divergent biosynthetic origins of three subgroups of oligomers including the acarviosine-containing oligosaccharides, saccharomicins, and orthosomycins.

Protective Effects of Hyperbaric Oxygen Therapy on Brain Injury by Regulating the Phosphorylation of Drp1 Through ROS/PKC Pathway in Heatstroke Rats.

This study aimed to elucidate the neurotherapeutic effect of hyperbaric oxygen (HBO) on brain injury and the potential role of dynamin-related protein 1 (Drp1) and its regulatory pathway in heatstroke (HS) rats. In in vivo experiments, rats were exposed to HBO after the onset of HS, or the same pressure but normal air as a control. The results indicated that HBO decreased the mortality and thermoregulatory dysfunction and prolonged the survival time of HS rats. Neurological dysfunction induced by HS was attenuated by HBO through assessment of modified neurological severity score and Morris water maze. HBO also alleviated histopathologic changes and oxidative injury (malondialdehyde and 8-hydroxyguanine), increased activities of superoxide dismutase (SOD) and glutathione/oxidized glutathione and ameliorated apoptotic parameters (caspase-3/6 activities and the number of apoptotic cells) of the hippocampus, hypothalamus and brain stem in rats compared to the HS group. Phosphorylation of DrpSer616 was increased by HS but decreased by HBO in the brains of rats determined by Western blot and immunohistochemical staining. In experiments in vitro, rat hippocampal neurons were used as a heat stress (HS) cellular model to examine the effects of HBO. As the results, HBO attenuated HS-induced cytotoxicity, oxidative injury (malondialdehyde), reactive oxygen species (ROS) generation, decreasing SOD activity and apoptosis. Drp1 inhibitor (Mdivi-1) treatment produced the same effects and had a trend to decrease oxidative injury. But the difference is not statistically significant. HBO and Mdivi-1decreased the phosphorylation of DrpSer616 induced by HS and HBO decreased the phosphorylation of protein kinase C (PKC) induced by HS. Moreover, both PKC inhibitor and ROS scavenger inhibited HS-induced p-DrpSer616. In conclusion, HBO may alleviate the brain injury caused by HS by decreasing ROS/PKC-regulated p-DrpSer616.

Solvated proton and the origin of the high onset overpotential in the oxygen reduction reaction on Pt(111).

For the oxygen reduction reaction (ORR) in acidic media, a proton is a key component in the hydrogenation of O2, O, and OH. Modeling a proton requires an explicit account of its solvation and its dynamic nature in the interfacial solution region. We employed ab initio molecular dynamics to study these reactions on Pt(111), which is a model problem in electro-catalysis. Our results show that the branching ratio for the two hydrogenation channels of O atoms adsorbed on Pt(111) shifts dramatically with the electrode potential. This kinetic factor underlies the electrochemical observations peculiar to ORR on Pt(111) and provides an explanation for the long-standing puzzle of its high onset overpotential.

Cryogenic ion trap vibrational spectroscopy of the microhydrated sulfate dianions SO42-(H2O)3-8.

Infrared photodissociation spectra of the D2-tagged microhydrated sulfate dianions with three to eight water molecules are presented over a broad spectral range that covers the OH stretching and H2O bending modes of the solvent molecules at higher energies, the sulfate stretching modes of the solute at intermediate energies and the intermolecular solute librational modes at the lowest energies. A low ion temperature combined with messenger-tagging ensures well-resolved vibrational spectra that allow for structure assignments based on a comparison to harmonic and anharmonic IR spectra from density functional theory (DFT) calculations. DFT ab initio molecular dynamics simulations are required to disentangle the broad and complex spectral signatures of microhydrated sulfate dianions in the OH stretching region and to identify systematic trends in the correlation of the strength and evolution of the solute-solvent and solvent-solvent interactions with cluster size. The onset for the formation of the second solvation shell is observed for n = 8.

Acylated Aminooligosaccharides from the Yellow Sea Streptomyces sp. HO1518 as Both α-Glucosidase and Lipase Inhibitors.

Three new acylated aminooligosaccharide (1-3), along with five known congeners (4-8), were isolated from the marine-derived Streptomyces sp. HO1518. Their structures were fully elucidated by extensive spectroscopic analysis, mainly based on 1D-selective and 2D TOCSY, HSQC-TOCSY, and HRESIMS spectrometry measurements, and by chemical transformations. All of the compounds were evaluated for their α-glucosidase and pancreatic lipase inhibitory activities. Among the isolates, D6-O-isobutyryl-acarviostatin II03 (3) and D6-O-acetyl-acarviostatin II03 (8), sharing acarviostatin II03-type structure, showed the most potent α-glucosidase and lipase inhibitory effects, far stronger than the antidiabetic acarbose towards α-glucosidase and almost equal to the anti-obesity orlistat towards lipase in vitro. This is the first report on inhibitory activities against the two major digestive enzymes for acylated aminooligosaccharides. The results from our investigation highlight the potential of acylated aminooligosaccharides for the future development of multi-target anti-diabetic drug.

[A single-center retrospective analysis of 46 children with aerophagia].

OBJECTIVE: To study the clinical features of aerophagia in children. MEYJODS: A retrospective analysis was performed on the medical data of 46 children with aerophagia who were diagnosed and treated in Children's Hospital Affiliated to Nanjing Medical University from October 2011 to September 2019. RESULTS: Among these 46 children, 15 (33%) had Tourette syndrome. Abdominal distension was the most common symptom and was observed in 45 children (98%). The 24-hour esophageal multichannel intraluminal impedance monitoring showed a mean number of 341 times of air swallowing and a mean number of 212 times of gas reflux, and 95% of gas refluxes occurred in the upright body position. Compared with those without Tourette syndrome, the children with Tourette syndrome had a significantly higher incidence rate of air swallowing symptoms (67% vs 6%, P<0.001), but there were no significant differences in other symptoms and the results of 24-hour esophageal impedance. Dietary adjustment, psycho-behavioral therapy, and drug intervention significantly improved the scores of clinical symptoms and quality of life, among which psycho-behavioral therapy was an important intervention measure. CONCLUSIONS: Some children with aerophagia may have Tourette syndrome, and such children are more likely to have air swallowing symptoms. Psycho-behavioral therapy is one of the most important treatment methods, and children with aerophagia tend to have a good prognosis after treatment.

Calpain-2 protects against heat stress-induced cardiomyocyte apoptosis and heart dysfunction by blocking p38 mitogen-activated protein kinase activation.

Cardiovascular dysfunction is a common complication among heatstroke patients, but its underlying mechanism is unclear. This study was designed to investigate the role of calpain-2 and its downstream signal pathway in heat stress-induced cardiomyocyte apoptosis and heart dysfunction. In cultured primary mouse neonatal cardiomyocytes (MNCs), heat stress (43°C for 2 hr) induced a heat-shock response, as indicated by upregulated heat-shock protein 27 (HSP27) expression and cellular apoptosis, as indicated by increased caspase-3 activity, DNA fragmentation and decreased cell viability. Meanwhile, heat stress decreased calpain activity, which was accompanied by downregulated calpain-2 expression and increased phosphorylation of p38, extraceIIuIar signaI-reguIated protein kinase (ERK1/2) and c-Jun N-terminaI kinase (JNK). Calpain-2 overexpression abrogated heat stress-induced apoptosis and phosphorylation of p38 and JNK, but not of ERK1/2. Blocking only p38 prevented heat stress-induced apoptosis in MNCs. In cardiac-specific calpain-2 overexpressing transgenic mice, p38 phosphorylation and cardiomyocyte apoptosis were decreased in the heart tissue of heatstroke mice, as revealed by western blot and terminal deoxynucleotidyl transferase dUTP nick end labelling assays, respectively. M-mode echocardiography also demonstrated that calpain-2 overexpression significantly improved heatstroke-induced decreases in ventricular end-diastolic volume and cardiac output. In conclusion, our study suggests that heat stress reduces calpain-2 expression, which then activates p38, leading to cardiomyocyte apoptosis and heart dysfunction.

Structural inhomogeneity as a factor promoting the homogenous catalysis of CO2 hydrogenation by (PMe3)4RuH2.

During homogenous catalysis by organometallic complexes, the dissociation of a ligand to produce an unsaturated site on the metal center is often invoked as the first step of activation, especially when photo-excitation is involved. In this theoretical study, we demonstrated that under mild conditions, a thermodynamically unstable yet dynamically favorable active intermediate could be produced by the inhomogeneity of the solvent distribution around the catalyst rather than by ligand dissociation. This occurred at the end of the first catalytic cycle when the product was eliminated. The empty site was immediately filled by one of the additive molecules aggregated around the reaction center even when the intermediate complex was unstable, producing a transient and more active catalyst. This process accounted for the accelerated reaction rate observed in the landmark CO2 hydrogenation catalyzed by (PMe3)4RuH2 in supercritical CO2 when H2O, MeOH, or HNMe2 was added. This also suggests a new way to exploit the structural inhomogeneity around an organometallic complex for the design of superior catalysts.

Vibrational spectroscopy of the hexahydrated sulfate dianion revisited: role of isomers and anharmonicities.

We report on the gas phase vibrational spectroscopy of the hexahydrated sulfate dianion, SO42-(H2O)6, and its fully deuterated isotopologue, SO42-(D2O)6, using infrared photodissociation (IRPD) spectroscopy of the D2-tagged dianions in combination with density-functional-theory calculations on minimum-energy structures as well as finite temperature ab initio molecular dynamics (AIMD) simulations. The IRPD spectra were recorded at an ion trap temperature of 12 K and in the spectral range from 650 to 3800 cm-1, covering the intramolecular modes of the solvent (OH/OD stretches and H2O/D2O bends) at higher energies, those of the solute (sulfate stretches) at intermediate energies and the intermolecular solute librational modes at the lowest energies. Isomer-specific double resonance in combination with messenger-tag dependent IRPD spectra show that only a single isomer is contributing significantly and that this isomer is not the highly symmetric Td but rather the lower symmetry C3 isomer. Temperature-dependent IR multiple photon dissociation spectra of bare SO42-(H2O)6 suggest that the C3 isomer remains the most stable one up to 200 K. The AIMD simulations reveal that the IRPD spectra can only be fully understood when anharmonic effects as well as entropy-driven hydrogen bond network fluctuations are considered.

Solvation effects on the N-O and O-H stretching modes in hydrated NO3-(H2O)n clusters.

NO3-(H2O)n clusters are a molecular model used to understand the solvation interaction between water and nitrate, an important anion in nature, industrial processes and biology. We demonstrate by ab initio molecular dynamics simulations that among the many isomeric structures at each cluster size with n = 1-6, thermal stability is an important consideration. The vibrational profile at a particular size, probed previously by infrared multiple photon dissociation (IRMPD) spectroscopy, can be accounted for by the isomers, which are both energetically and dynamically stable. Conversion and broadening due to the fluctuation of hydrogen bonds are important not only for the O-H stretching modes but also for the N-O stretching modes. Distinct patterns for the O-H stretching modes are predicted for the various solvation motifs. We also predict a surface structure for NO3-(H2O)n as n increases beyond 6, which can be verified by an early onset of strong libration bands for H2O in the IRMPD spectra and a flattening of the vertical detachment energy in the photoelectron spectra.

Solvation effects on the vibrational modes in hydrated bicarbonate clusters.

HCO3-(H2O)n clusters provide a model system to understand the solvation interaction between the bicarbonate ion and water. Based on harmonic analysis, ab initio molecular dynamics simulations, and comparison with infrared multiple photon dissociation spectra and with previous results on H2PO4-(H2O)n, the solvation effects on the vibrational modes of HCO3-(H2O)n are analyzed. Hydrogen bond interactions have a significant impact on the vibration, especially when a hydrogen atom is directly involved in a particular mode. The COH bending mode is flattened, when the COH group is solvated by water molecules. The emergence of broad water libration modes indicates the aggregation of water molecules and the formation of a surface structure with bicarbonate on the surface.