Enhancing CO2 electroreduction performance through transition metal atom doping and strain engineering in γ-GeSe: a first-principles study.

The development of electrocatalysts that exhibit stability, high activity, and selectivity for CO2 reduction reactions (CO2RR) remains a significant challenge. Single-atom catalysts (SACs) hold promise in addressing this challenge due to their high atomic utilization efficiency. In this study, we explore the potential of monolayer γ-GeSe doped with transition metals, referred to as TM@γ-GeSe, for facilitating electrocatalytic CO2RR. Among the 26 TM@γ-GeSe SACs systematically designed, we have identified four stable transition metal catalysts (TM = Rh, Pd, Pt, and Au). Mechanistic investigations into the CO2RR pathways reveal exceptional electrocatalytic activity for Rh@γ-GeSe and Pd@γ-GeSe, with limiting potentials of -0.26 and -0.35 V, respectively. Particularly, Pd@γ-GeSe exhibits outstanding product selectivity toward formic acid. The introduction of strain engineering induces modifications in the catalytic activity and selectivity of Rh@γ-GeSe. Notably, a 1% tensile strain promotes formic acid as the preferred product, thereby improving the specific product selectivity of Rh@γ-GeSe. Conversely, compressive strain reduces CO2RR activity while enhancing the hydrogen evolution reaction, leading to a decrease in CO2RR selectivity. Furthermore, we use the work function as a descriptor to elucidate the underlying mechanism of strain tunability. We hope that our theoretical study will offer valuable insights for the design of catalysts based on γ-GeSe for electrocatalytic CO2RR.

CO2 electroreduction performance of PtS2 supported single transition metal atoms: a theoretical study.

Electrocatalytic CO2 reduction is a sustainable strategy to convert CO2 into valuable carbon products. Atomically dispersed single-atom catalysts (SACs) have great potential as effective electrocatalysts for the CO2 reduction reaction (CO2RR). Transition metal dichalcogenides (TMDs) are considered to be a kind of promising SAC supports. In this work, ten different 3d TM single atoms (TM = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn) embedded in PtS2 with single S-vacancy (TM-PtS2) were designed by density functional theory (DFT) as candidate electrocatalysts for the CO2RR. Possible reaction pathways of CO2 reduction to different C1 products were systematically investigated. The results show that for all these TM-PtS2 SACs, higher selectivity was achieved for CO2 reduction to C1 products than for the competing hydrogen evolution. HCOOH is the most favorable reduction product on PtS2-Sv supported Sc, Ti, V, Cr, Mn, Fe and Cu SACs, while multiple C1 products are generated on Co-, Ni- and Zn-PtS2. In particular, it is found that Sc-, V-, Fe-, Co- and Cu-PtS2 exhibit higher electrocatalytic performance for the CO2RR than Cu(211). Therefore, these five SACs are promising CO2RR electrocatalysts.

Single-walled carbon nanotubes enhance the immune protective effect of a bath subunit vaccine for pearl gentian grouper against Iridovirus of Taiwan.

Iridovirus of Taiwan (TGIV) has been threatening the grouper farming since 1997, effective prophylaxis method is urgently needed. Subunit vaccine was proved to be useful to against the virus. Bath is the simplest method of vaccination and easy to be administrated without any stress to fish. In this research, we constructed a prokaryotic expression vector of TGIV's major capsid protein (MCP) to acquire the vaccine. Single-walled carbon nanotubes (SWCNTs) were used as the carrier to enhance the protective effect of bath vaccination for juvenile pearl gentian grouper (bath with concentrations of 5, 10, 20 mg/L for 6 h). Virus challenge was done after 28 days. Survival rates were calculated after 14 days. The level of antibody, activities of related enzymes in serums and expression of immune-related genes in kidneys and spleens were test. The results showed that vaccine with SWCNTs as carrier induced a higher level of antibody than that without. In addition, the activities of related enzymes (acid phosphatase, alkaline phosphatase, superoxide dismutase) and the expression of immune-related genes (Mx1, IgM, TNFαF, Lysozyme, CC chemokine 1, IL1-ß, IL-8) had a significantly increase. What's more, higher survival rates (42.10%, 77.77%, 89.47%) were provided by vaccine with SWCNTs than vaccine without SWCNTs (29.41%, 38.09%, 43.75%). This study suggests that the protective effect of vaccine that against TGIV with the method of bath vaccination could be enhanced by SWCNTs and SWCNTs could be a potential carrier for other subunit vaccines.

Unveiling the potential of superalkali cation Li3+ for capturing nitrogen.

The potential of the superalkali cation Li3+ for capturing N2 and its behavior in gaseous nitrogen have been theoretically studied at the MP2/6-311+G(d) level. The evolution of structures and stability of the Li3+(N2)n (n = 1-7) complexes shows that the N2 molecules tend to bind to different vertices of the Li3+ core, and that Li3+ might have the capacity to capture up to twelve nitrogen molecules in the first coordination shell. Based on natural population and molecular orbital analyses, Li3+ keeps its superatom identity in the lowest-lying Li3+(N2)n (n = 1-4) complexes. The change in the Gibbs free energies of possible fragmentation channels also indicates the thermodynamic stability of Li3+ in the (N2)n clusters when n ≤ 4. Different from the case of Li3+(H2O)n, where the electrostatic interaction is dominant, the electrostatic and polarization components are found to make nearly equal contributions to Li3+(N2)n complex formation. In addition, it can be concluded that the superalkali cation Li3+ surpasses heavy alkali metal cations in capturing N2 molecules, since it has a larger binding energy with N2 than Na+ and K+ ions.

Limbic encephalitis associated with antibodies against the α-Amino-3-Hydroxy-5-Methyl-4-Isoxazolepropionic acid receptor: a case report.

We report a case of a 51-year-old man with limbic encephalitis (LE) associated with antibodies against the α-Amino-3-Hydroxy-5-Methyl-4-Isoxazolepropionic acid receptor (AMPAR). The patient presented with anterograde memory loss for 2 months. Cranial magnetic resonance and electroencephalogram were normal. AMPAR antibodies were found in blood serum and cerebrospinal fluid. All other test results were unremarkable. CT scans found a tumor in the right lobus superior pulmonis. A CT-guided needle biopsy was performed and pathological results showed small cell lung cancer (SCLC). The patient was diagnosed with LE associated with AMPAR antibodies and SCLC. Three months after immunotherapy and tumor removal, patient's memory was partially restored. We recommend that AMPAR antibodies should be detected in patients with classic LE with or without tumor. Prompt treatment of the tumor and immunotherapy are important.

Hydrolysis of Sulfur Dioxide in Small Clusters of Sulfuric Acid: Mechanistic and Kinetic Study.

The deposition and hydrolysis reaction of SO2 + H2O in small clusters of sulfuric acid and water are studied by theoretical calculations of the molecular clusters SO2-(H2SO4)n-(H2O)m (m = 1,2; n = 1,2). Sulfuric acid exhibits a dramatic catalytic effect on the hydrolysis reaction of SO2 as it lowers the energy barrier by over 20 kcal/mol. The reaction with monohydrated sulfuric acid (SO2 + H2O + H2SO4 - H2O) has the lowest energy barrier of 3.83 kcal/mol, in which the cluster H2SO4-(H2O)2 forms initially at the entrance channel. The energy barriers for the three hydrolysis reactions are in the order SO2 + (H2SO4)-H2O > SO2 + (H2SO4)2-H2O > SO2 + H2SO4-H2O. Furthermore, sulfurous acid is more strongly bonded to the hydrated sulfuric acid (or dimer) clusters than the corresponding reactant (monohydrated SO2). Consequently, sulfuric acid promotes the hydrolysis of SO2 both kinetically and thermodynamically. Kinetics simulations have been performed to study the importance of these reactions in the reduction of atmospheric SO2. The results will give a new insight on how the pre-existing aerosols catalyze the hydrolysis of SO2, leading to the formation and growth of new particles.

Mechanism of the gaseous hydrolysis reaction of SO2: Effects of NH3 versus H2O.

Effects of ammonia and water molecules on the hydrolysis of sulfur dioxide are investigated by theoretical calculations of two series of the molecular clusters SO2-(H2O)n (n = 1-5) and SO2-(H2O)n-NH3 (n = 1-3). The reaction in pure water clusters is thermodynamically unfavorable. The additional water in the clusters reduces the energy barrier for the reaction, and the effect of each water decreases with the increasing number of water molecules in the clusters. There is a considerable energy barrier for reaction in SO2-(H2O)5, 5.69 kcal/mol. With ammonia included in the cluster, SO2-(H2O)n-NH3, the energy barrier is dramatically reduced, to 1.89 kcal/mol with n = 3, and the corresponding product of hydrated ammonium bisulfate NH4HSO3-(H2O)2 is also stabilized thermodynamically. The present study shows that ammonia has larger kinetic and thermodynamic effects than water in promoting the hydrolysis reaction of SO2 in small clusters favorable in the atmosphere.

Theoretical study on the kinetics of the reaction CH2Br + NO2.

The mechanism for the reaction CH2Br + NO2 was investigated by quantum chemical calculation, and the kinetic calculations were carried out by means of multichannel RRKM and variational transition-state theory method. Both singlet and triplet potential energy surfaces (PESs) were considered at the CCSD(T)/6-311++G(d,p)//B3LYP/6-311G(d,p) level. The results show that the singlet PES is preferred, and the initial association is a barrierless process (CH2Br + NO2 → CH2BrNO2), consistent with previous study, while the reaction occurring on the triplet PES is unfavorable due to the high barriers at the entrance channels. The calculated overall rate constants agree well with the experimental data within the measured temperature range of 221-363 K, fitted to the expression of k(T) = 2.61 × 10(-10)T(-0.76) exp(461/T) cm(3) molecule(-1) s(-1) over the temperature range of 200-2000 K. The product ratios were obtained by using master equation modeling and show that the formation of product CH2O + BrNO (P1) is dominant, in line with the experimental observation.

Central nervous system involvement in primary Sjogren`s syndrome manifesting as multiple sclerosis.

Central nervous system symptoms in patients with primary Sjogren`s syndrome are rare. They can present as extraglandular manifestations and require a differential diagnosis from multiple sclerosis. Due to a variety of presentations, Sjogren`s syndrome with neurologic involvement may be difficult to diagnose. Here, we report a case of a 75-year-old woman who was first diagnosed with multiple sclerosis in 2010, but who was subsequently diagnosed with primary Sjogren`s syndrome 2 years later after showing signs of atypical neurologic manifestations. Therefore, primary Sjogren`s syndrome should be suspected in patients who present with atypical clinical and radiologic neurologic manifestations.

A feasible strategy for designing cytochrome P450-mimic sandwich-like single-atom nanozymes toward electrochemical CO2 conversion.

Carbon dioxide electroreduction (CO2ER) presents a promising strategy for environmentally friendly CO2 utilization due to its low energy consumption. Single-atom nanozymes (SANs), amalgamating the benefits of single-atom catalysts and nanozymes, have become a hot topic in catalysis. Inspired by the intricate structure of cytochrome P450, we designed 81 sandwich-like SANs using Group-VIII transition metals (TMN4-S-TM'N4) and evaluated their performance in CO2ER using density functional theory (DFT). Our investigation revealed that most SANs display superior catalytic activity and improved specific product selectivity in comparison to the Cu (211) surface. Notably, IrN4-S-TMN4 (TM = Co, Rh, Pd) exhibited selective CO2 reduction to CO with remarkable limiting potentials (UL) of -0.11, -0.07, and -0.09 V, respectively, demonstrating potential as artificial CO dehydrogenases. Furthermore, RuN4-S-RuN4 exhibited formate dehydrogenase-like activity, resulting in selective production of HCOOH at a UL of -0.10 V. Machine learning analysis elucidated that the exceptional activity and selectivity of these SANs stemmed from precise modulation of electron density on sulfur atoms, achieved by varying transition metals in the subsurface. Our research not only identifies exceptional SANs for CO2ER but also provides insights into innovative methods for regulating non-bonding interactions and achieving sustainable CO2 conversion.

Mechanism of ammonia decomposition and oxidation on Ir(110): a first-principles study.

The mechanism of ammonia decomposition and oxidation on Ir(110) was studied on the basis of periodic density functional theory calculations and microkinetic modeling. The results indicate that NH3 dissociation is more favorable than desorption at atop site, while at top site NH3 desorption and dissociation are competitive. On the other hand, when O or OH is co-adsorbed, the NH3 dehydrogenation is slightly inhibited and mainly via hydrogen abstraction reaction rather than thermal decomposition, while it is reversed for NH2 dehydrogenation. The former mechanism is favored for O assisted NH dehydrogenation, while it changed to latter one for OH. On clean Ir(110), N + NH → N2 + H pathway is the major N2 formation pathway and N + N is also involved but less competitive, while N + N becomes the predominant one and is enhanced on O-predosed Ir(110). NO formation occurs only at higher temperature when N2 is desorbed from the surface. The microkinetic analysis further confirms that the dominant product is N2 at low temperature while becomes NO as temperature increases, and the temperature of NO formation decreases when O2 partial pressure increases. The present calculation results are in good agreement with the experimental observations.

Rapid Thalidomide Racemization Is Related to Proton Tunneling Reactions via Water Bridges.

Quantum mechanical tunneling (QMT) can play an important role in light element-related chemical reactions; however, its influence on racemization is not fully understood. Herein, we demonstrate that the role of QMT is decisive for rapid racemization of the well-known thalidomide molecule in aqueous environments, increasing the reaction rate constants of the most likely racemization pathways by 87-149 times at approximately body temperature and achieving good agreement between theoretical calculations and experimental observations. In addition, the kinetic isotope effect values fit well with those of previous experiments. These results are attributed to enhanced tunneling probability due to the alteration of potential barriers for proton transfer reactions via water bridges. This work highlights the significance of the QMT effect in racemization and its potential impact on drug safety, providing a fundamental perspective for understanding chirality-related issues in biological systems.

Theoretical study and rate constants calculation for the reactions X + CF3CH2OCF3 (X = F, Cl, Br).

The multiple-channel reactions X + CF3CH2OCF3 (X = F, Cl, Br) are theoretically investigated. The minimum energy paths (MEP) are calculated at the MP2/6-31 + G(d,p) level, and energetic information is further refined by the MC-QCISD (single-point) method. The rate constants for major reaction channels are calculated by canonical variational transition state theory (CVT) with small-curvature tunneling (SCT) correction over the temperature range 200­2000 K. The theoretical three-parameter expressions for the three channels k1a(T) = 1.24 x 10(-15T1.24)exp(-304.81/T), k2a(T) = 7.27 x 10(-15T0.37)exp(-630.69/T), and k3a(T) = 2.84 x 10(-19T2.51)exp(-2725.17/T) cm3 molecule(-1) s(-1) are given. Our calculations indicate that hydrogen abstraction channel is only feasible channel due to the smaller barrier height among five channels considered.

Theoretical study on the reaction CX3 + SiH(CH3)3 (X = H, F).

Theoretical investigations are carried out on the multiple-channel reactions, CH(3) + SiH(CH(3))(3) → products and CF(3) + SiH(CH(3))(3) → products. The minimum energy paths (MEP) are calculated at the MP2/6-311 + G(d,p) level, and energetic information is further refined by the MC-QCISD (single point) method. The rate constants for major reaction channels are calculated by the canonical variational transition state theory (CVT) with small-curvature tunneling (SCT) correction over the temperature range 200-1500 K. The theoretical rate constants are in good agreement with the available experimental data and are found to be k(1a)(T) = 1.93 × 10(-24) T(3.15) exp(-1214.59/T) and k(2a)(T) = 1.33 × 10(-25) T(4.13) exp(-397.94/T) (in unit of cm(3) molecule(-1) s(-1)). Our calculations indicate that hydrogen abstraction channel from SiH group is the major channel due to the smaller barrier height among five channels considered.

Analysis of mitochondrial haplogroups associated with TTR Val30Ala familial amyloidotic polyneuropathy in Chinese patients.

Extracellular deposition of abnormal transthyretin (TTR) amyloid fibrils leads to familial amyloidotic polyneuropathy (FAP), an inherited autsomal dominant disease. A large number of protein variants, each caused by a different point mutation in the TTR gene have been identified, including TTR Val30Ala. Since the age of onset, organ involvement, and disease progression are highly variable in FAP, even among individuals with the same TTR genetic variation. it is likely that other genetic and environmental factors influence FAP disease phenotype. One study has found a relationship between mitochondrial haplogroups and age of onset of FAP. In this study, we wondered whether certain mitochondrial haplogroups were associated with the cases of TTR Val30Ala FAP in a Chinese population. Mitochondrial haplogroup analysis was performed on a group of patients and their relatives and on a group of healthy controls. All FAP probands were unrelated in their maternal lineages. The chi-squared test for independence found no difference in mitochondrial haplogroup distribution between FAP and control groups. This is the first study reporting frequency and distribution of different haplogroups in FAP in a Chinese population. Although the study group was small, TTR Val30Ala FAP in China seems unrelated to mitochondrial haplogroup.

[Effect of S-adenosylmethionine on vascular smooth cells proliferation and migration].

OBJECTIVE: To investigate the effect of S-adenosyl-L-methionine (SAMe) on vascular smooth muscle cells (VSMCs) proliferation and migration and neointima formation in rat carotid artery balloon injury model. METHODS: Rat VSMCs were divided into control group, TNF-α (10 ng/ml) group, SAMe (0.2 mmol/L) group and TNF-α + SAMe group. VSMC migration distance and proliferation were examined by cell scrape tests and MTT method. NF-κB activity was analyzed by EMSA. PDGF mRNA expression was detected by Northern blot. SD rat were divided into control group, carotid balloon injury group treated with saline or SAMe (15 mg×kg(-1)×d(-1) for 14 d), then blood vessel proliferation was observed histologically in rat carotid artery. RESULTS: (1) In vitro, the VSMCs migration distance, absorbance at 490 nm, PDGF mRNA expression, NF-κB activity were all increased in TNF-α group compared to the control group (P < 0.01), and decreased in TNF-α + SAMe group compared to the TNF-α group (P < 0.01). (2) In the balloon injury in vivo models, the intima area of saline group and SAMe group was increased compared to the control group, while the lumen area was larger and the intima area was smaller in the SAMe group than in the saline group (all P < 0.05). CONCLUSION: SAMe could reduce TNF-α induced VSMC proliferation and migration possibly through inhibiting NF-κB activity and downregulating PDGF gene expression.

Thrombotic thrombocytopenic purpura with neurological impairment: A Review.

The last 2 decades have witnessed considerable advances in our understanding of thrombotic thrombocytopenic purpura (TTP). However, there is still some ambiguity regarding the precise nature of this disease, especially with respect to nervous system involvement and the correct nomenclature. This article seeks to summarize the clinical manifestations of TTP and the associated diseases. We describe TTP complicated with cerebrovascular disease, spinal cord injury, posterior reversible encephalopathy syndrome (PRES), anxious-depressive symptoms, and cognitive decline. TTP with spinal cord injury is rarely reported. For better clarity, we discuss the case of a 57-year-old woman who was diagnosed with neuromyelitis optica spectrum disease (NMOSD) with atypical TTP. The concurrent occurrence of NMOSD and TTP in this patient is consistent with the characteristics of acquired autoimmunity. We highlight the importance of early recognition of TTP in patients with atypical presentation who may not have the expected clinical or laboratory findings. This is particularly important in TTP patients with other concomitant autoimmune diseases or age-related comorbid conditions.

Genetic characteristics of Chinese patients with hemorrhagic cerebrovascular disease.

BACKGROUND: We investigate the clinical and genetic characteristics of hemorrhagic cerebrovascular disease in order to provide a new theoretical basis for the prevention and treatment of hereditary cerebrovascular disease. METHOD: Three hereditary cerebral hemorrhage cases were analyzed retrospectively. The patients' families were surveyed, the clinical characteristics summarized, and gene polymorphisms investigated. RESULTS: Among the three cases, two patients had familial cerebral cavernous hemangiomas, and genetic testing revealed a heterozygous mutation in the CCM1 gene, with a deletion of base (T) in exon 15 (c.1542delT). The last patient had hereditary cerebral hemorrhage with amyloidosis, Finnish type, and the proband, his mother, and his daughter were found to have a heterozygous G duplicate mutation at position 100 in exon 1 of the GSN gene (c.100dupG). CONCLUSIONS: Future screening for genetic mutations associated with a high-risk of hereditary cerebral hemorrhage can help identify individuals at risk for this condition and thereby reduce the occurrence and progression of the disease. Such screening will further enhance the precision in preventing and treating cerebrovascular diseases.

Elucidation of the methyl transfer mechanism catalyzed by chalcone O-methyltransferase: a density functional study.

The mechanism of the methyl transfer catalyzed by chalcone O-methyltransferase has been computationally investigated by employing the hybrid functional B3LYP. Two models are constructed based on the two conformations of the substrate isoliquiritigenin in the X-ray structure. Our calculations show that the overall reaction is divided into two elementary steps: the water-assisted deprotonation of the substrate by His278 as a catalytic base, followed by the methyl transfer from S-adenosyl-L-methionine (SAM) to the substrate. The calculated rate-limiting barriers for the methyl-transfer step indicate that the catalytic reactions are energetically feasible for both conformations adopted by the substrate.

Theoretical mechanistic study on the reaction of CN radical with HNCN.

The mechanism for the reaction of the cyanogen radical (CN) with the cyanomidyl radical (HNCN) has been investigated theoretically. The electronic structure information of the singlet and triplet potential energy surfaces (PESs) is obtained at the B3LYP/6-311+G(3df,2p) level, and the single-point energies are refined at the CCSD(T)/6-311+G(3df,2p) level as well as by multilevel MCG3-MPWB method. The calculations show that the C atom of CN additions to middle- and end-N atoms of HNCN are two barrierless association processes leading to the energy-rich intermediates IM1 HN(CN)CN and IM2 HNCNCN, respectively, on the singlet PES. The higher barriers of the subsequent isomerization and dissociation channels from IM1 and IM2 indicate that these two intermediates, which have considerably thermodynamic and kinetic stability, are the dominant product at high pressure. While at low pressure, the most favorable product is P(2) H + NCNCN, which will be formed from both IM1 and IM2 via direct dissociation processes by the H-N bond rupture, and the secondary feasible product is P(4) HCN + (1) NCN, while P(5) HCCN + N(2) and P(6) HCNC + N(2) are the least competitive products. On the triplet PES, P(14) NCNC + HN may be a comparable competitive product at high temperature. In addition, the comparison between the mechanisms of the CN + HNCN and OH + HNCN reactions is made. The present results will enrich our understanding of the chemistry of the HNCN radical in combustion processes and interstellar space.