Nitrate reduction capacity of the oral microbiota is impaired in periodontitis:potential implications for systemic nitric oxide availability

The reduction of nitrate to nitrite by the oral microbiota has been proposed to be important for oral health and results in nitric oxide formation that can improve cardiometabolic conditions. Studies of bacterial composition in subgingival plaque suggest that nitrate-reducing bacteria are associated with periodontal health, but the impact of periodontitis on nitrate-reducing capacity(NRC)and, therefore, nitric oxide availability has not been evaluated. The current study aimed to evaluate how periodontitis affects the NRC of the oral microbiota. First, 16S rRNA sequencing data from five different countries were analyzed, revealing that nitratereducing bacteria were significantly lower in subgingival plaque of periodontitis patients compared with healthy individuals(P < 0.05 in all five datasets with n = 20–82 samples per dataset). Secondly, subgingival plaque, saliva, and plasma samples were obtained from 42 periodontitis patients before and after periodontal treatment. The oral NRC was determined in vitro by incubating saliva with 8 mmol/L nitrate(a concentration found in saliva after nitrate-rich vegetable intake) and compared with the NRC of 15healthy individuals. Salivary NRC was found to be diminished in periodontal patients before treatment(P < 0.05) but recovered to healthy levels 90 days post-treatment. Additionally, the subgingival levels of nitrate-reducing bacteria increased after treatment and correlated negatively with periodontitis-associated bacteria(P < 0.01). No significant effect of periodontal treatment on the baseline saliva and plasma nitrate and nitrite levels was found, indicating that differences in the NRC may only be revealed after nitrate intake. Our results suggest that an impaired NRC in periodontitis could limit dietary nitrate-derived nitric oxide levels, and the effect on systemic health should be explored in future studies.

Electrifying Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3-δ) for focalized heating in oxygen transport membranes

Industry decarbonization requires the development of highly efficient and flexible technologies relying on renewable energy resources,especially biomass and solar/wind electricity.In the case of pure oxygen production,oxygen transport membranes(OTMs)appear as an alternative technology for the cryogenic distillation of air,the industrially-established process of producing oxygen.Moreover,OTMs could provide oxygen from different sources(air,water,CO_(2),etc.),and they are more flexible in adapting to current processes,producing oxygen at 700^(-1)000℃.Furthermore,OTMs can be integrated into catalytic membrane reactors,providing new pathways for different processes.The first part of this study was focused on electrification on a traditional OTM material(Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3-δ)),imposing different electric currents/voltages along a capillary membrane.Thanks to the emerging Joule effect,the membrane-surface temperature and the associated O_(2) permeation flux could be adjusted.Here,the OTM is electrically and locally heated and reaches 900℃on the surface,whereas the surrounding of the membrane was maintained at 650℃.The O_(2)permeation flux reached for the electrified membranes was~3.7 NmL min^(-1)cm^(-2),corresponding to the flux obtained with an OTM non-electrified at 900℃.The influence of depositing a porous Ce_(0.8)Tb_(0.2)O_(2-δ) catalytic/protective layer on the outer membrane surface revealed that lower surface temperatures(830℃)were detected at the same imposed electric power.Finally,the electrification concept was demonstrated in a catalytic membrane reactor(CMR)where the oxidative dehydrogenation of ethane(ODHE)was carried out.ODHE reaction is very sensitive to temperature,and here,we demonstrate an improvement of the ethylene yield by reaching moderate temperatures in the reaction chamber while the O_(2) injection into the reaction can be easily fine-tuned.

Assessing the Performance of a Dynamical Downscaling Simulation Driven by a Bias-Corrected CMIP6 Dataset for Asian Climate

In this study,we aim to assess dynamical downscaling simulations by utilizing a novel bias-corrected global climate model(GCM)data to drive a regional climate model(RCM)over the Asia-western North Pacific region.Three simulations were conducted with a 25-km grid spacing for the period 1980–2014.The first simulation(WRF_ERA5)was driven by the European Centre for Medium-Range Weather Forecasts Reanalysis 5(ERA5)dataset and served as the validation dataset.The original GCM dataset(MPI-ESM1-2-HR model)was used to drive the second simulation(WRF_GCM),while the third simulation(WRF_GCMbc)was driven by the bias-corrected GCM dataset.The bias-corrected GCM data has an ERA5-based mean and interannual variance and long-term trends derived from the ensemble mean of 18 CMIP6 models.Results demonstrate that the WRF_GCMbc significantly reduced the root-mean-square errors(RMSEs)of the climatological mean of downscaled variables,including temperature,precipitation,snow,wind,relative humidity,and planetary boundary layer height by 50%–90%compared to the WRF_GCM.Similarly,the RMSEs of interannual-tointerdecadal variances of downscaled variables were reduced by 30%–60%.Furthermore,the WRF_GCMbc better captured the annual cycle of the monsoon circulation and intraseasonal and day-to-day variabilities.The leading empirical orthogonal function(EOF)shows a monopole precipitation mode in the WRF_GCM.In contrast,the WRF_GCMbc successfully reproduced the observed tri-pole mode of summer precipitation over eastern China.This improvement could be attributed to a better-simulated location of the western North Pacific subtropical high in the WRF_GCMbc after GCM bias correction.

小胶质细胞在卒中中的作用

小胶质细胞在缺血后的炎症反应和受损组织的清除中扮演关键角色,它们对缺血引起的干扰反应迅速,致力于恢复失去的稳态。然而,被修改的环境,包括离子失衡、关键的神经元-小胶质细胞相互作用的中断、去极化传播以及来自坏死神经元的危险信号的产生,诱导了小胶质细胞的形态和表型转变。这导致它们表现为促炎表型并增加吞噬活动。从缺血后的第3天开始,巨噬细胞渗透到坏死组织核心,而小胶质细胞则在病灶周边聚集。此外,炎症促使代谢转向有利于糖酵解、戊糖磷酸途径和脂质合成。这些转变与吞噬脂质的摄入相结合,促进了脂滴生成、合成代谢,并使小胶质细胞增殖。增殖的小胶质细胞释放营养因子,有助于神经保护和修复。然而,一些小胶质细胞持续积累脂质,并转变为功能失调且可能有害的泡沫细胞。研究还表明,有些小胶质细胞要么清除凋亡细胞能力的受损,要么消除突触、活神经元或内皮细胞。然而,阐明被吞噬细胞的生存能力、局部环境特征、组织损伤程度和时间序列将是至关重要的。缺血为小胶质细胞提供了丰富多样的、依赖于区域和损伤的刺激,随着时间演变导致出现不同的小胶质细胞表型,包括表现为促炎性或功能失调特征的细胞,以及显示出促进修复功能的细胞。准确分析小胶质细胞表型,以及更精确地了解相关的缺血后组织条件,是对卒中进行针对性干预的必要步骤。

Identification of quantitative trait loci and candidate genes for primary metabolite content in strawberry fruit

Improvement of nutritional and organoleptic quality of fruits is a key goal in current strawberry breeding programs.The ratio of sugars to acids is a determinant factor contributing to fruit liking,although different sugars and acids contribute in varying degrees to this complex trait.A segregating F1 population of 95 individuals,previously characterized for several fruit quality characters,was used to map during 2 years quantitative trait loci(QTL)for 50 primary metabolites,L-ascorbic acid(L-AA)and other related traits such as soluble solid content(SSC),titratable acidity(TA),and pH.A total of 133 mQTL were detected above the established thresholds for 44 traits.Only 12.9%of QTL were detected in the 2 years,suggesting a large environmental influence on primary metabolite content.An objective of this study was the identification of key metabolites that were associated to the overall variation in SSC and acidity.As it was observed in previous studies,a number of QTL controlling several metabolites and traits were co-located in homoeology group V(HG V).mQTL controlling a large variance in raffinose,sucrose,succinic acid,and L-AA were detected in approximate the same chromosomal regions of different homoeologous linkage groups belonging to HG V.Candidate genes for selected mQTL are proposed based on their co-localization,on the predicted function,and their differential gene expression among contrasting F1 progeny lines.RNA-seq analysis from progeny lines contrasting in L-AA content detected 826 differentially expressed genes and identified Mannose-6-phosphate isomerase,FaM6PI1,as a candidate gene contributing to natural variation in ascorbic acid in strawberry fruit.

Microbiota of a seepage face at the mouth of a subterranean estuary:diversity,distribution and substrate dependence

Subterranean estuaries,i.e.,the mixing zone between terrestrial groundwater and recirculated seawater,host a wide range of microbiota.Here,field campaigns were conducted at the mouth of the subterranean estuary at the Sanggou Bay(Shandong Province,China)over four consecutive seasons at a seepage face(0−20 cm depth).The diversity of benthic microbiome was characterized via 16S rRNA gene sequencing and metagenomics,combined with physic-chemical parameters,e.g.,organic carbon,total nitrogen and sulfate contents in sediments.During spring,the dominant species were assigned to the phylum Proteobacteria.Important opportunistic species was assigned to Acidobacteria,Actinobacteria and Bacteroidetes.The key components were identified to be species of the genera Pseudoalteromonas,Colwellia and Sphingobium,indicating the involvement of sediment microbiota in the degradation of sedimentary organic carbon,particularly that of pelagic origin,e.g.,phytoplankton detritus and bivalve pseudo-feces.During spring,the microbial community was statistically similar along the depth profiles and among the three sampled stations.Similar spatial distributions were obtained in the remaining seasons.By contrast,the dominant species assemblages varied significantly among seasons,with key genera being Thioprofundum and Nitrosopumilus during summer and autumn and Thioprofundum and Ilumatobacter during winter.Network analysis revealed a seasonal shift in benthic nitrogen and sulfur metabolism associated with these variations in microbial community composition.Overall,our findings suggested that macro elements derived from pelagic inputs,particularly detrital phytoplankton,shaped the microbial community compositions at the seepage face,resulting in significant seasonal variations,while the influence of terrestrial materials transported by groundwater on the sediment microbiota at the seepage face found to be minor.

Metal-organic framework-based materials as key components in electrocatalytic oxidation and reduction reactions

Studies have extensively addressed the development of electrocatalytic technologies for energy storage and conversion,fuel production,and environmental protection.Electrode processes such as different oxidation and reduction reactions play a vital and significant role in these technologies.In this regard,efficient,inexpensive,and stable electrocatalysts capable can significantly promote electrochemical reactions.Unique features of metal–organic frameworks(MOFs)such as their high porosity,tunable structure,size,and pore shape,high surface area,and redox properties have introduced them as an ideal electrocatalyst candidate.This review is thus aimed at elucidating the role of MOF-based materials(pristine,derivatives and composites)as efficient electrocatalysts in energy and sensing-related oxidation and reduction reactions such as oxygen reduction reaction(ORR),hydrogen oxidation reaction(HOR),carbon dioxide reduction reaction(CO_(2)RR),urea oxidation reaction(UOR),alcohol oxidation reaction(AOR),nitrogen reduction reaction(NRR),and glucose oxidation reaction(GOR)in advanced energy and sensing devices.Also,the structure–property relationship of the electrocatalyst was elaborated for each electrocatalytic reaction.Finally,perspectives on the potential research topics for practical use of MOF-based electrocatalysts are addressed.The present review can improve the interest in MOF-based electrocatalysts to study different oxidation and reduction reactions in energy and sensing systems.

流化冰保鲜对鲣鱼蛋白质功能特性的影响

为探索流化冰对冰鲜水产品保鲜效果,以鲣鱼鱼肉为研究对象,以传统碎块冰保鲜为对照,探讨流化冰处理对鲣鱼肌肉蛋白质功能特性影响。结果表明:1)流化冰冰粒子呈球形,外表光滑、单位表面积大且流动性能好,8 min内可将鱼肉整体温度由35℃降低至1.3℃;2)-4℃贮藏18 d后,流化冰保鲜处理的鱼肉弹性和咀嚼性依次为1.19 mm和5.50 m J,而空白(不加冰)、淡水碎块冰组分别为0.67 mm和1.65 m J、0.95 mm和3.32 m J,可见流化冰对鱼肉质构特性保持效果显著(P<0.05);3)0~18 d贮藏期内,不同处理鲣鱼肌原纤维蛋白含量、Ca2+-ATPase活性及总巯基含量均呈逐渐下降趋势,其中以流化冰处理对鲣鱼蛋白质功能特性的保持效果最佳;此外,流化冰保鲜还兼具有抑制鱼肉氧合肌红蛋白自动氧化、维持肌肉原有色泽的作用。流化冰处理显著保持了鲣鱼肌肉组织的质构和相关蛋白质功能特性,可满足冰鲜水产品远洋、长距离运输和保鲜贮藏要求。

流化冰对于鲣鱼的保鲜效果研究

以远洋鲣鱼为研究对象,以传统淡水碎冰保鲜为对照,研究流化冰处理对鲣鱼的理化性质及微生物特性的影响。结果表明:(1)–4°C冷藏18d后,流化冰保鲜鱼肉pH值、TVB-N、TBA、a*值和菌落总数依次为5.57、10.2mgN/100g、2.87mg/100g、8.92和2.61lgCFU/g,而淡水碎冰保鲜鱼肉各指标已达6.05、20.3mgN/100g、6.60mg/100g、7.16和3.02lgCFU/g,故可知流化冰保鲜处理效果明显优于碎冰保鲜。(2)在25±1°C室温条件下,将冰与鱼放入保温箱内保鲜8h后,流化冰保鲜鱼肉的a*值、pH值、TVB-N、TBA、菌落总数和汁液流失率均显著低于空白和淡水碎冰保鲜处理组(P<0.05)。流化冰保鲜可显著减缓鱼体的腐败进程、延长产品货架期,进而满足冰鲜水产品的远洋及长距离运输要求。

DSC测定加脂革氧化参数

研究了用鱼油、菜籽油、牛蹄油、卵磷脂及其亚硫酸化或硫酸化产物制备的,具有不同碘值的一系列加脂剂的氧化性。加脂剂以及加脂革的氧化性能通过非等温差示扫描量热仪(DSC)测定。记录热氧化反应的起始温度以及195～265℃热氧化峰的热焓值,然后与不同加脂剂标准配方进行比较。用UV辐射以及高温对皮革进行老化处理。归因于老化处理的皮革变性温度的降低是与加脂剂的氧化性能相关的。

Gut microbiota-related complications in cirrhosis

Gut microbiota plays an important role in cirrhosis. The liver is constantly challenged with commensal bacteria and their products arriving through the portal vein in the so-called gut-liver axis. Bacterial translocation from the intestinal lumen through the intestinal wall and to mesenteric lymph nodes is facilitated by intestinal bacterial overgrowth, impairment in the permeability of the intestinal mucosal barrier, and deficiencies in local host immune defences. Deranged clearance of endogenous bacteria from portal and systemic circulation turns the gut into the major source of bacterialrelated complications. Liver function may therefore be affected by alterations in the composition of the intestinal microbiota and a role for commensal flora has been evidenced in the pathogenesis of several complications arising in end-stage liver disease such as hepatic encephalopathy, splanchnic arterial vasodilatation and spontaneous bacterial peritonitis. The use of antibioticsis the main therapeutic pipeline in the management of these bacteria-related complications.However,other strategies aimed at preserving intestinal homeostasis through the use of pre-,pro-or symbiotic formulations are being studied in the last years.In this review,the role of intestinal microbiota in the development of the most frequent complications arising in cirrhosis and the different clinical and experimental studies conducted to prevent or improve these complications by modifying the gut microbiota composition are summarized.

How to protect liver graft with nitric oxide

Organ preservation and ischemia reperfusion injury associated with liver transplantation play an important role in the induction of graft injury. One of the earliest events associated with the reperfusion injury is endothelial cell dysfunction. It is generally accepted that endothelial nitric oxide synthase （e-NOS） is cell-pro- tective by mediating vasodilatation, whereas inducible nitric oxide synthase mediates liver graft injury after transplantation. We conducted a critical review of the literature evaluating the potential applications of regulating and promoting e-NOS activity in liver preservation and transplantation, showing the most current evidence to support the concept that enhanced bioavailability of NO derived from e-NOS is detrimental to ameliorate graft liver preservation, as well as preventing subse- quent graft reperfusion injury. This review deals mainly with the beneficial effects of promoting ＂endogenous＂ pathways for NO generation, via e-NOS inducer drugs in cold preservation solution, surgical strategies such as ischemic preconditioning, and alternative ＂exogenous＂ pathways that focus on the enrichment of cold storage liquid with NO donors. Finally, we also provide a basic bench-to-bed side summary of the liver physiology and cell signalling mechanisms that account for explaining the e-NOS protective effects in liver preservation and transplantation.

Insulin like growth factor-1 increases fatty liver preservation in IGL-1 solution

AIM: To investigate the benefits of insulin like growth factor-1 (IGF-1) supplementation to serum-free institut georges lopez-1 (IGL-1) solution to protect fatty liver against cold ischemia reperfusion injury. METHODS: Steatotic livers were preserved for 24 h in IGL-1  solution supplemented with or without IGF-1 and then perfused "ex vivo " for 2 h at 37℃. We examined the effects of IGF-1 on hepatic damage and function (transaminases, percentage of sulfobromophthalein clearance in bile and vascular resistance). We also studied other factors associated with the poor tolerance of fatty livers to cold ischemia reperfusion injury such as mitochondrial damage, oxidative stress, nitric oxide, tumor necrosis factor-α (TNF-α) and mitogen-activated protein kinases.RESULTS: Steatotic livers preserved in IGL-1 solutionsupplemented with IGF-1 showed lower transaminase levels, increased bile clearance and a reduction in vascular resistance when compared to those preserved in IGL-1solution alone. These benefits are mediated by activation of AKT and constitutive endothelial nitric oxide synthase (eNOS), as well as the inhibition of inflammatory cytokines such as TNF-α. Mitochondrial damage and oxidative stress were also prevented.CONCLUSION: IGL-1  enrichment with IGF-1 increasedfatty liver graft preservation through AKT and eNOS activation, and prevented TNF-α release during normothermic reperfusion.

Effects of Composted and Thermally Dried Sewage Sludges on Soil and Soil Humic Acid Properties

The effect of annual additions of composted sewage sludge (CS) and thermally dried sewage sludge (TS) at 80 t ha-1 on soil chemical properties was investigated for three years in a field experiment under semiarid conditions. Humic acids (HAs) isolated by conventional procedures from CS, TS, and unamended (SO) and sludge amended soils were analysed for elemental (C, H, N, S and O) and acidic functional groups (carboxylic and phenolic) and by ultraviolet-visible, Fourier transform infrared and fluorescence spectroscopies. With respect to CS, TS had similar pH and total P and K contents, larger dry matter, total organic C, total N and C/N ratio and smaller ash content and electrical conductivity. Amendment with both CS and TS induced a number of modifications in soil properties, including an increase of pH, electrical conductivity, total organic C, total N, and available P. The CS-HA had greater O, total acidity, carboxyl, and phenolic OH group contents and smaller C and H contents than TS-HA. The CS-HA and TS-HA had larger N and S contents, smaller C, O and acidic functional group contents, and lower aromatic polycondensation and humification degrees than SO-HA. Amended soil-HAs showed C, H, N and S contents larger than SO-HA, suggesting that sludge HAs were partially incorporated into soil HAs. These effects were more evident with increasing number of sludge applications.

Polymorphisms in oxidative pathway related genes and susceptibility to inflammatory bowel disease

AIM To investigate whether common variants in the oxidative pathway genes influence inflammatory bowel disease(IBD) risk among Moroccan patients. METHODS The distribution of(TAAA)n_rs12720460 and(CCTTT)n_rs3833912 NOS2 A microsatellite repeats, HIF-1 A_rs11549467 and NFKB1-94 ins/delA TTG_rs28362491 was analyzed in 507 subjects grouped in 199 IBD and 308 healthy controls. Genotyping was performed withpolymerase chain reaction-fluorescent method and the TaqMan~? allelic discrimination technology.RESULTS The allele and genotype frequencies of HIF1 A_ rs11549467, NFKB1_rs28362491 and NOS2 A_(TAAA)n did not differ significantly between patients and controls. Analysis of NOS2 A_(CCTTT)n markers evidenced differences between patients and healthy controls. A preferential presence of the(CCTTT)8(P = 0.02; OR = 1.71, 95%CI: 1.07-2.74),(CCTTT)14(P = 0.02; OR = 1.71, 95%CI: 1.06-2.76) alleles in IBD,(CCTTT)8(P = 0.008; OR = 1.95, 95%CI: 1.17-3.23) in CD and(CCTTT)7(P = 0.009; OR = 7.61, 95%CI: 1.25-46.08),(CCTTT)11(P = 0.05; OR = 0.51, 95%CI: 0.25-1.01),(CCTTT)14(P = 0.02; OR = 2.05, 95%CI: 1.07-3.94),(CCTTT)15(P = 0.01; OR = 2.25, 95%CI: 1.16-4.35) repeats in UC patients indicated its possible association with higher disease risk which need to be confirmed in a larger sample size. CONCLUSION Our results suggest that the NOS2 A_(CCTTT)n gene variations may influence IBD susceptibility in the Moroccan population.

Comparing Land Degradation and Regeneration Trends in China Drylands

The aim of this paper is to offer a statistically sound method to make a precise account of the speed of land degradation and regeneration processes.Most common analyses of land degradation focus instead on the extent of degraded areas,rather than on the intensity of degradation processes.The study was implemented for the Potential Extent of Desertification in China(PEDC),composed by arid,semi-arid,and dry sub-humid regions and refers to the period 2002 to 2012.The metrics were standard partial regression coefficients from stepwise regressions,fitted using Net Primary Productivity as the dependent variable,and year number and aridity as predictors.The results indicate that:①the extension of degrading lands(292896 km 2 or 9.12%of PEDC)overcomes the area that is recovering(194560 km 2 or 6.06%of PEDC);and②the intensity of degrading trends is lower than that of increasing trends in three land cover types(grassland,desert,and crops)and in two aridity levels(semi-arid and dry sub-humid).Such an outcome might pinpoint restoration policies by the Chinese government,and document a possible case of hysteresis.

Ni-based catalysts obtained from perovskites oxides for ethanol steam reforming

Perovskites as host structures of cations were used in order to generate in situ active and stable catalysts for ethanol steam reforming. For this purpose,La_(1-x)Mg_xAl_(1-y)Ni_yO_3(x = 0.1; y = 0,0.1,0.2,0.3) perovskites were synthetized by the citrate method.Ni segregation is evident for a substitution level higher than 0. 2. The segregation of Ni as NiO generated species interacts with different metal-support after the reduction step. The y = 0.1 catalyst presents the highest H_2 yield value about 85% during reaction time,with low mean values of CH_4 and CO selectivities of 3.4% and 11%,respectively and a low carbon formation. The better performance of y = 0.1 catalyst could be attributed to the minor proportion of segregated phases,thus a controlled expulsion of Ni is successfully reached.

A comprehensive study of the proteins involved in salinity stress response in roots and shoots of the FL478 genotype of rice(Oryza sativa L. ssp. indica)

Rice,a major staple,is the most salt-sensitive cereal.High salinity triggers several adaptive responses in rice to cope with osmotic and ionic stress at the physiological,cellular,and molecular levels.A major QTL for salinity tolerance,named Saltol,is present on chromosome 1 of Indian landraces such as Pokkali and Nona Bokra.The early proteomic and physiological responses to salinity in roots and shoots of FL478,an inbred rice line harboring the Saltol QTL,were characterized.Plantlets were cultured in hydroponic cultures with 100 mmol L^(-1) Na Cl and evaluated at 6,24,and 48 h.At the physiological level,root length significantly increased at 48 h,whereas shoot length was reduced.The Na^(+)/K^(+) ratio was maintained at lower levels in shoots than in roots,suggesting that roots play a protective role.More than 2000 proteins were detected in both tissues.Roots showed a faster and more coordinated proteomic response than shoots,evident after only 6 h of treatment.These responses showed clear correspondence with those of proteins involved in transcription and translation.Maintenance of mitochondrial activity and amino acid metabolism in roots,and activation of stress-responsive proteins such as dehydrins and PLAT in shoots,may play a key role during the response of the plant to salinity stress.Proteomic and physiological responses showed that roots respond in a more highly adaptive manner than shoots to salinity stress,suggesting that this tissue is critical to the tolerance observed in cultivars harboring Saltol.

Non-steroidal anti-inflammatory drugs(NSAIDs) and neuroprotection in the elderly a view from the mitochondria

The most important risk factor for stroke and neurodegeneration is aging. In fact, survival after stroke diminishes largely with aging. In fact, recovery after brain artery occlusion is dramatically worsened by aging, even normal aging is associated with neuron damage and cognitive decline. Mechanisms involved in aging-related, cognitive decline and susceptibility to neuron damage in stroke and neurode- generation are largely unknown. One of the most important mech- anisms contributing to neural dysfunction and death is excitotox- icity. This process is based on the fact that the excessive glutamate receptor stimulation may lead to neuronal damage. This overstim- ulation may be due to increased concentration of glutamate, or the prolonged activation of receptors.

Molybdenum carbide as catalyst in biomass derivatives conversion

The present energy dilemma in conjunction with the adverse environmental impacts caused by fossil fuel combustion motivates researchers to seek for new renewable energy with minimal CO_(2)footprint.As a practice pathway,it is of significance to produce biofuel and platform chemicals from sustainable biomass resources.However,the research and development of high-efficiency catalysts remain one key scientific challenge.Among the catalysts developed,transition metal carbides,especially molybdenum carbide,show promising performances on biomass-based conversion.Significant efforts have been made in past few decades on tuning the structure and electronic property of molybdenum carbide via controlling particle size and morphology,metal and nonmetal doping and vacancies,etc.The review summarizes recent developments of molybdenum carbide as catalysts in converting biomass into fuel,mainly focused on the preparation methods,the structure-dependent effects and the electronic modulation.The controllable selective cleavage of C-C,C-O and C-H bonds over modified molybdenum carbides that has been demonstrated in the conversion of biomass feedstocks is then highlighted.In addition,the possible deactivation mechanisms of molybdenum carbide are also presented in the review.This review provides systematic and fundamental information for the further design and development of molybdenum carbide for the conversion of biomass resources.