Direct detection of a single[4Fe-4S]cluster in a tungsten-containing enzyme:Electrochemical conversion of CO_(2) into formate by formate dehydrogenase

The conversion of CO_(2) into fuels and valuable chemicals is one of the central topics to combat climate change and meet the growing demand for renewable energy.Herein,we show that the formate dehydrogenase from Clostridium ljungdahlii(ClFDH)adsorbed on electrodes displays clear characteristic voltammetric signals that can be assigned to the reduction and oxidation potential of the[4Fe-4S]^(2+/+)cluster under nonturnover conditions.Upon adding substrates,the signals transform into a specific redox center that engages in catalytic electron transport.ClFDH catalyzes rapid and efficient reversible interconversion between CO_(2) and formate in the presence of substrates.The turnover frequency of electrochemical CO_(2) reduction is determined as 1210 s^(-1) at 25℃ and pH 7.0,which can be further enhanced up to 1786 s^(-1) at 50℃.The Faradaic efficiency at−0.6 V(vs.standard hydrogen electrode)is recorded as 99.3%in a 2-h reaction.Inhibition experiments and theoretical modeling disclose interesting pathways for CO_(2) entry,formate exit,and OCN−competition,suggesting an oxidation-state-dependent binding mechanism of catalysis.Our results provide a different perspective for understanding the catalytic mechanism of FDH and original insights into the design of synthetic catalysts.

Co-transplantation of Schwann cells and bone marrow stromal cells versus single cell transplantation on repairing hemisected spinal cord injury of rats

BACKGROUND: Bone marrow stromal cells (BMSCs) or Schwann cells (SCs) transplantation alone can treat spinal cord injury. However, the transplantation either cell-type alone has disadvantages. The co-transplantation of both cells may benefit structural reconstruction and functional recovery of spinal nerves. OBJECTIVE: To verify spinal cord repair and related mechanisms after co-transplantation of BMSCs and SCs in a rat model of hemisected spinal cord injury. DESIGN, TIME AND SETTING: A randomized, controlled, animal experiment was performed at the Department of Histology and Embryology, Mudanjiang Medical College from January 2008 to May 2009. MATERIALS: Rabbit anti-S-100, glial fibrillary acidic protein, neuron specific enolase and neurofilament-200 monoclonal antibodies were purchased from Sigma, USA. METHODS: A total of 100 Wistar rats were used in a model of hemisected spinal cord injury. The rats were randomly assigned to vehicle control, SCs transplantation, BMSCs transplantation, and co-transplantation groups; 25 rats per group. At 1 week after modeling, SCs or BMSCs cultured in vitro were labeled and injected separately into the hemisected spinal segment of SCs and BMSCs transplantation groups through three injection points [5 μL (1 × 107 cells/mL)] cell suspension in each point). In addition, a 15 μL 1 × 107 cells/mL SCs suspension and a 15 μL 1 × 107 cells/mL BMSC suspension were injected into co-transplantation group by the above method. MAIN OUTCOME MEASURES: The Basso-Beattie-Bresnahan (BBB) locomotor rating scale and somatosensory evoked potential (SEP) tests were used to assess the functional recovery of rat hind limbs following operation. Structural repair of injured nerve tissue was observed by light microscopy, electron microscopy, immunohistochemistry, and magnetic resonance imaging (MRI). In vivo differentiation, survival and migration of BMSCs were evaluated by immunofluorescence. RESULTS: BBB scores were significantly greater in all three transplantation groups compared with vehicle control group 8 weeks after transplantation. In particular, the co-transplantation group displayed the highest scores among the groups (P < 0.05). Moreover, recovery of SEP latency and amplitude was observed in all the transplantation groups, particularly after 8 weeks. Again, the co-transplantation group exhibited the greatest improvement (P < 0.05). In the co-transplantation group, imaging showed a smooth surface and intact inner structure at the injury site, with no scar formation, and a large number of orderly cells at the injured site. Axonal regeneration, new myelination, and a large amount of cell division were detected in the co-transplantation group by electron microscopy. Neuron specific enolase (NSE)- and glial fibrillary acidic protein (GFAP)-positive cells were observed in the spinal cord sections 1 week following co-transplantation by immunofluorescence staining. CONCLUSION: Co-transplantation of SCs and BMSCs effectively promoted functional recovery of injured spinal cord in rats compared with SCs or BMSCs transplantation alone. This repair effect is probably achieved because of neuronal-like cells derived from BMSCs to supplement dead neurons in vivo.

Observation system simulation experiments using an ensemble-based method in the northeastern South China Sea

An ensemble-based method for the observation system simulation experiment(OSSE)is employed to design optimal observation stations and assess the present observation stations in the northeastern South China Sea(SCS).We employed the 20-year(1992-2012)sea surface height(SSH)data to design an array to monitor the intraseasonal to interannual variability.The results show that the most key region was found located at the northwest of Luzon Island(LI)where the energetic Luzon cyclonic gyre(LCG)occurs;other key regions include the edge of the LCG,the northwest of the Luzon Strait(LS),and the southwest of Taiwan,China.By contrast,we found that the present observation stations might oversample at the northwest of the LS and undersample at the northwest of LI.In addition,the optimal stations perform better in a larger area than the present stations.In vertical direction,the key layer is located within the upper 200-m depth,of which the surface and subsurface layers are most valuable to the observing system.

5G High Frequency Band Channel Modeling and Insights on System Design

There are two main opposing views in the wireless industry on the feasibility of developing 5th generation(5G) cellular networks in mm-Wave bands. The optimistic view is based on the fact that the path loss in mm Wave bands is not significantly worse than that in cellular bands when beamforming gain is also considered. The cautious view points out the significant blockage issues due to the lack of diffraction and adequate penetration in mm Wave bands. The implementation of 5G mm Wave cellular networks also faces major challenges due to the high link budget needed for long- range communication and the strong dependency on beamforming technology. This paper addresses some of these fundamental technology issues, from mm Wave channel characters and channel modeling to the implications on system and network architecture design.Although we believe that mm Wave can be used for 5G networks, we show that the air interface, device and network design will be very different from existing cellular design.

Primary assessment of the diversity of Omicron sublineages and the epidemiologic features of autumn/winter 2022 COVID-19 wave in Chinese mainland

With the recent ongoing autumn/winter 2022 COVID-19 wave and the adjustment of public health control measures,there have been widespread SARS-CoV-2 infections in Chinese mainland.Here we have analyzed 369 viral genomes from recently diagnosed COVID-19 patients in Shanghai,identifying a large number of sublineages of the SARS-CoV-2 Omicron family.Phylogenetic analysis,coupled with contact history tracing,revealed simultaneous community transmission of two Omicron sublineages dominating the infections in some areas of China(BA.5.2 mainly in Guangzhou and Shanghai,and BF.7 mainly in Beijing)and two highly infectious sublineages recently imported from abroad(XBB and BQ.1).Publicly available data from August 31 to November 29,2022 indicated an overall severe/critical case rate of 0.035%nationwide,while analysis of 5706 symptomatic patients treated at the Shanghai Public Health Center between September 1 and December 26,2022 showed that 20 cases(0.35%)without comorbidities progressed into severe/critical conditions and 153 cases(2.68%)with COVID-19-exacerbated comorbidities progressed into severe/critical conditions.These observations shall alert healthcare providers to place more resources for the treatment of severe/critical cases.Furthermore,mathematical modeling predicts this autumn/winter wave might pass through major cities in China by the end of the year,whereas some middle and western provinces and rural areas would be hit by the upcoming infection wave in mid-to-late January 2023,and the duration and magnitude of upcoming outbreak could be dramatically enhanced by the extensive travels during the Spring Festival(January 21,2023).Altogether,these preliminary data highlight the needs to allocate resources to early diagnosis and effective treatment of severe cases and the protection of vulnerable population,especially in the rural areas,to ensure the country’s smooth exit from the ongoing pandemic and accelerate socio-economic recovery.

Cu_(2+1)O/CuO_(x)heterostructures promote the electrosynthesis of C^(2+)products from CO_(2)

Manipulating the oxidation state of Cu catalysts can significantly affect the selectivity and activity of electrocatalytic carbon dioxide reduction(CO_(2)RR).However,the thermodynamically favorable cathodic reduction to metallic states typically leads to catalytic deactivation.Herein,a defect construction strategy is employed to prepare crystalline/amorphous Cu_(2+1)O/CuO_(x)heterostructures(c/a-CuO_(x))with abundant Cu0 and Cuδ+(0<δ<1)sites for CO_(2)RR.The C^(2+)Faradaic efficiency of the heterostructured Cu catalyst is up to 81.3%,with partial current densities of 406.7 mA·cm−2.Significantly,real-time monitoring of the Cu oxidation state evolution by in-situ Raman spectroscopy confirms the stability of Cuδ+species under long-term high current density operation.Density functional theory(DFT)calculations further reveal that the adjacent Cu0 and Cuδ+sites in heterostructured c/a-CuO_(x)can efficiently reduce the energy barrier of CO coupling for C^(2+)products.

用于高活性和选择性加氢反应的氧化镍纳米片的非晶态策略

过渡金属氧化物(TMOs)作为低成本的加氢催化剂,具有良好的选择性和耐久性.然而,由于缺乏氢气解离所需的金属活化位点,通常需要在高压(1-5 Mpa H_(2))和高温(100-250℃)等苛刻条件下才能实现氢的活化.在此,我们开发了一种具有极低的Ni-Ni配位数的非晶态氧化镍纳米片,这种独特的特征不仅有利于H_(2)的活化,而且在室温(25℃)和室压(100 kPa H_(2))下,乙烯基的加氢过程具有显著的活性与高选择性(~99%).

Atomically dispersed Au_1 catalyst towards efficient electrochemical synthesis of ammonia

Tremendous efforts have been devoted to explore energy-efficient strategies of ammonia synthesis to replace Haber–Bosch process which accounts for 1.4% of the annual energy consumption. In this study,atomically dispersed Au_1 catalyst is synthesized and applied in electrochemical synthesis of ammonia under ambient conditions. A high NH_4^+ Faradaic efficiency of 11.1% achieved by our Au_1 catalyst surpasses most of reported catalysts under comparable conditions. Benefiting from efficient atom utilization, an NH_4^+ yield rate of 1,305 lg h^(-1) mg_(Au)^(-1) has been reached, which is roughly 22.5 times as high as that by supported Au nanoparticles. We also demonstrate that by employing our Au_1 catalyst, NH4+can be electrochemically produced directly from N_2 and H_2 with an energy utilization rate of 4.02 mmol kJ^(-1). Our study provides a possibility of replacing the Haber–Bosch process with environmentally benign and energy-efficient electrochemical strategies.

Co-occurrence of nitrite-dependent anaerobic methane oxidizing and anaerobic ammonia oxidizing bacteria in two Qinghai-Tibetan saline lakes

亚硝酸根依赖者厌氧氧化甲烷(n-damo ) 氧化的细菌和厌氧的氨(anammox ) 细菌是涉及全球碳并且氮骑车的二组微生物。为了测试 n-damo 和 anammox 细菌是否在自然盐的环境， DNA 和 cDNA 共同发生，样品从二个盐的湖的地表的沉积获得了(与 32 和 84 g/L 的咸度，分别地)与 anammox-damo-specific 和 n-damo-specific 教材集合的使用在西藏的高原上是 放大PCR 的，由克隆图书馆建设和种系发生的分析列在后面。DNA 和基于 cDNA 的克隆与 n-damo 结盟了， anammox 细菌成功地从二件样品被检索，显示这些二组细菌能象 84 g/L 一样高在有咸度的自然盐的环境共同发生。我们发现在自然为我们全球碳和氮周期的理解有大含意[出版摘要]

西藏热泉沉积物的硫氧化细菌多样性及其影响因素

【目的】探究西藏热泉沉积物中硫氧化细菌群落多样性及其环境影响因素。【方法】选取西藏5个地热区的25个热泉样点,现场测量各采样点的水体理化参数,并采集热泉水和沉积物样品。通过功能基因(硫代硫酸盐水解酶编码基因:soxB)克隆文库分析方法,研究沉积物样品中硫氧化细菌群落的组成和多样性,并统计分析其与环境参数之间的相关性。【结果】克隆文库分析结果显示,西藏热泉沉积物样品中的硫氧化细菌主要分属于α-Proteobacteria、β-Proteobacteria和γ-Proteobacteria纲。研究样品中的硫氧化菌群落香农指数与溶解有机碳的浓度(R=0.489,P<0.05)呈显著正相关。另外,统计发现西藏各热泉之间的硫氧化菌群落组成差异较大,其优势硫氧化细菌种群差异明显,大多数样点的优势硫氧化细菌种群为β-Proteobacteria,少量样点以α-Proteobacteria和γ-Proteobacteria为主。Mantel检验结果显示,西藏热泉样品中的硫氧化细菌群落组成与温度、硫化物、电导率、海拔、总溶解固体和pH显著(P<0.05)相关。【结论】西藏热泉沉积物中的硫氧化细菌群落广泛分布,且主要以变形菌门为主。地理隔离和理化差异导致了热泉沉积物样品间的硫氧化菌群落组成差异。

Anisotropic Cu@Cu-BTC core-shell nanostructure for memory device

The activity and stability of Cu nanostructures strongly depend on their sizes,morphology and structures.Here we report the preparation of two-dimensional(2 D)Cu@Cu-BTC core-shell nanosheets(NSs).The thickness of the Cu NSs could be tuned to sub-10 nm through a mild etching process,in which the Cu-BTC in situ grow along with the oxidation on the surface of the Cu NSs.This unique strategy can also be extended to synthesize one-dimensional(1 D)Cu@Cu-BTC nanowires(NWs).Furthermore,the obtained Cu@Cu-BTC NSs could be applied as an effective material to the memory device with the write-onceread-many times(WORM)behavior and the high ION/I(OFF)ratio(>2.7×103).

NiCo-LDH nanosheets strongly coupled with GO-CNTs as a hybrid electrocatalyst for oxygen evolution reaction

The rational fabrication of highly efficient electrocatalysts with low cost toward oxygen evolution reaction(OER)is greatly desired but remains a formidable challenge.In this work,we present a facile and straightforward method of incorporating NiCo-layered double hydroxide(NiCo-LDH)into GO-dispersed CNTs(GO-CNTs)with interconnected configuration.X-ray absorption spectroscopy(XAS)reveals the strong electron interaction between NiCo-LDH and the underlying GO-CNTs substrate,which is supposed to facilitate charge transfer and accelerate the kinetics for OER.By tuning the amount of CNTs,the optimized NiCo-LDH/GO-CNTs composite can achieve a low overpotential of 290 mV at 10 mA·cm^(−2) current density,a small Tafel slope of 66.8 mV·dec^(−1) and robust stability,superior to the pure NiCo-LDH and commercial RuO_(2) in alkaline media.The preeminent oxygen evolution performance is attributed to the synergistic effect stemming from the merits and the intimate electron interaction between LDH and GO-CNTs.This allows NiCo-LDH/GO-CNTs to be potentially applied in an industrial non-noble metal-based water electrolyzer as the anodic catalysts.