Two-dimensional C_(2)N-based single-atom catalyst with complex microenvironment for enhanced electrochemical nitrogen reduction:A descriptor-based design

The catalytic descriptor with operational feasibility is highly desired towards rational design of high-performance catalyst especially the electrode/electrolyte solution interface working under mild conditions.Herein,we demonstrate that the descriptorΩparameterized by readily accessible intrinsic properties of metal center and coordination is highly operational and efficient in rational design of single-atom catalyst(SAC)for driving electrochemical nitrogen reduction(NRR).Using twodimensional metal(M)-B_(x)P_(y)S_(z)N_m@C_(2)N as prototype SAC models,we reveal that^(*)N_(2)+(H~++e~-)→^(*)N_(2)H acts predominantly as the potential-limiting step(PLS)of NRR on M-B_(2)P_(2)S_(2)@C_(2)N and M-B_(1)P_(1)S_(1)N_(3)@C_(2)N regardless of the distinction in coordination microenvironment.Among the 28 screened M active sites,withΩvalues close to the optimal 4,M-B_(2)P_(2)S_(2)@C_(2)N(M=V(Ω=3.53),Mo(Ω=5.12),and W(Ω=3.92))and M-B_(1)P_(1)S_(1)N_(3)@C_(2)N(M=V(Ω=3.00),Mo(Ω=4.34),and W(Ω=3.32))yield the lowered limiting potential(U_(L))as-0.45,-0.54.-0.36,-0.58,-0.25,and-0.24 V,respectively,thus making them the promising NRR catalysts.More importantly,these SACs are located around the top of volcano-shape plot of U_(L) versusΩ,re-validatingΩas an effective descriptor for accurately predicting the high-activity NRR SACs even with complex coordination.Our study unravels the relationship between active-site structure and NRR performance via the descriptorΩ,which can be applied to other important sustainable electrocatalytic reactions involving activation of small molecules viaσ-donation andπ^(*)-backdonation mechanism.

Microbulbifer sp.FG5琼胶酶的分离纯化及酶学性质研究

琼胶酶是一种糖苷水解酶,能够特异性降解琼胶为琼胶寡糖。本研究从一株琼胶降解菌FG5的培养液中分离纯化得到纯净的琼胶酶并研究其酶学特性。将FG5菌株的发酵液离心后得到粗酶液,再通过超滤浓缩、透析、葡聚糖凝胶柱层析进行酶的分离纯化。收集得到葡聚糖凝胶柱层析紫外检测主峰组份,经SDS-PAGE电泳检测为单一条带蛋白质,分子量约为54 kD。酶活检测证明该蛋白具有琼脂酶活性,命名为琼胶酶FG5-A。采用单因素试验和正交试验设计对FG5-A的酶解反应条件进行优化分析。FG5-A琼胶酶活性最适条件为:pH 7.3,反应温度51℃,反应底物含量0.351%。探索了FG5-A的纯化流程,经葡聚糖凝胶柱纯化后琼胶酶活性相比发酵液提高了6.95倍,并初步优化了FG5-A琼胶酶的最适酶解条件,为高纯度琼胶酶的工业化生产和应用奠定理论与实践基础。

Monoclonal antibody-based cancer therapies

Targeted therapy has been widely demonstrated as an effective strategy to treat cancers,the leading cause of death in the world.This minireview summarizes the technical platforms and methodologies utilized to develop and engineer therapeutic monoclonal antibodies and antibody-drug conjugates.First,the USA FDA approved monoclonal antibody(mAb)-based targeted therapies are reviewed.Then the representative innovative chimeric,humanized and fully human anti-cancer antibodies and antibody-drug conjugates are described.Finally,the past and predictive market trend of therapeutic antibodies is discussed.

产微球茎属(Microbulbifer sp.)FG4菌株琼胶酶功能基因的克隆与表达

以FG4菌株琼胶酶基因侧翼序列为基础,构建重组质粒与载体,从而获得高效产琼胶酶的表达菌株。本研究利用染色体步移法获得FG4菌珠琼胶酶基因功能的侧翼序列之后,将基因组端序列克隆基因片段与表达载体进行重组,并转入到受体细胞BL21中,在鉴定表达菌株的成功构建后利用IPTG诱导表达琼胶酶。实现产微球茎属(Microbulbifer sp.)FG4菌株琼胶酶功能基因的克隆与表达,以期为琼胶酶类在不同领域的实际应用提供理论支持。

Microstructure Evolution and Dynamic Mechanical Properties of Laser Additive Manufacturing Ti-6Al-4V Under High Strain Rate

The dynamic mechanical properties of the Ti-6Al-4V(TC4)alloy prepared by laser additive manufacturing(LAM-TC4)under the high strain rate(HSR)are proposed.The dynamic compression experiments of LAM-TC4 are conducted with the split Hopkinson pressure bar(SHPB)equipment.The results show that as the strain rate increases,the widths of the adiabatic shear band(ASB),the micro-hardness,the degree of grain refinement near the ASB,and the dislocation density of grains grow gradually.Moreover,the increase of dislocation density of grains is the root factor in enhancing the yield strength of LAM-TC4.Meanwhile,the heat produced from the distortion and dislocations of grains promotes the heat softening effect favorable for the recrystallization of grains,resulting in the grain refinement of ASB.Furthermore,the contrastive analysis between LAM-TC4 and TC4 prepared by forging(F-TC4)indicates that under the HSR,the yield strength of LAM-TC4 is higher than that of F-TC4.

Binocular form deprivation influences the visual cortex

a-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors are considered to play a crucial role in synaptic plasticity in the developing visual cortex. In this study, we established a rat model of binocular form deprivation by suturing the rat binocular eyelids before eye-opening at postnatal day 14. During development, the decay time of excitatory postsynaptic currents mediated by a-amino-3- hydroxy-5-methyl-4-isoxazolepropionic acid receptors of normal rats became longer after eye- opening; however, the decay time did not change significantly in binocular form deprivation rats. The peak value in the normal group became gradually larger with age, but there was no significant change in the binocular form deprivation group. These findings indicate that binocular form deprivation influences the properties of excitatory postsynaptic currents mediated by a-amino-3- hydroxy-5-methyl-4-isoxazolepropionic acid receptors in the rat visual cortex around the end of the critical period, indicating that form stimulation is associated with the experience-dependent modification of neuronal synapses in the visual cortex.

巨正则密度泛函理论研究新型多孔BC_(4)N纳米结构上光电催化氮气还原反应

无金属类石墨烯结构碳基催化剂已被证明在促进光和电催化反应方面非常有效.在此,在恒电势模型(CPM)框架下,我们计算探索了所提出的新型二维BC_(4)N结构的材料和催化性能,以促进光电催化(PEC)N_(2)还原(NRR).结果表明,BC_(4)N作为光电阴极能够高效地捕获可见光和紫外光,光生电子可以提供U_(e)=-1.07 V的电势,这足以克服在电解质水溶液中发生的PEC NRR的电势限制步骤.此外,还发现共吸附反应中间体在介导/促进NRR生成NH3方面起着重要作用.从头算分子动力学模拟表明,质子耦合电子转移可以与分子间氢转移发生相互作用,使NRR机制在原子尺度上更加复杂.我们还讨论了CPM和领域内广泛使用的恒电荷模型之间的潜在差异.本研究为无金属半导体材料近真实条件下驱动光辅助PEC NRR的工作机制提供了基本见解.

Biomimetic lubricant-grafted surfaces on laser-textured microwell arrays with multifunctionality

Recently,various slippery liquid-infused porous surfaces(SLIPS)have been fabricated for the protection of various materials.However,these SLIPSs are limited by their underlying storage structure and superficial lubricant layer,showing poor durability.Herein,inspired by the high-strength structure of Shell nacre’s“brick-mud”layer,we fabricated an all-inorganic composite coating by using wet chemically etched MXene as a brick and an aluminum phosphate binder(AP)as mud.Then,a series of microwell-array structures were designed and prepared on the coating via nanosecond ultrafast laser writing ablation technology.Subsequently,the textured surface was modified by a silane coupling agent.Vinyl-terminated polydimethylsiloxane(PDMS)was tightly grafted onto the porous surface through a thiol-ene click reaction to obtain lubricant grafted texture surface(LGTS).The prepared LGTS showed good lubrication properties for multiple phases,including various liquids,ice crystals,and solids.It exhibits excellent chemical stability and mechanical durability under deionized water impact,centrifugal test,strong acid solutions,anti/de-icing cycles,and high-intensity friction.Thus,the proposed strategy for constructing robust LGTS will greatly promote theoretical research on super wetting interfacial materials and their applications in the fields of antifouling,anti/de-icing,and lubricating protection.

基于语音的抑郁症识别

抑郁症是世界范围内常见的精神疾病之一,抑郁症患者往往长期伴随情绪低落,如悲伤内疚、低自尊、兴趣丧失、功能减退等,对个人、家庭及社会造成了巨大损失.抑郁症的发病原因复杂,临床诊断存在一定的困难,有必要寻找一种更加便捷、客观、高效的方式来辅助抑郁症的快速识别.语音作为一个相对客观且容易获得的变量,具有其潜在的价值.本研究旨在构建基于语音的抑郁症识别模型,探究语音与抑郁症之间的关系.收集了103名被试(45名抑郁症患者,58名健康人)的语音数据,实验组为临床确诊的抑郁症患者,年龄在23.8~44.6岁之间,控制组为健康人,年龄为20.1~41.7岁.我们采用了3(情绪状态:正性、中性、负性)×3(任务类型:语言问答、文本朗读、图片描述)的实验设计,运用机器学习的分类算法——逻辑回归(LR)来构建抑郁识别模型.实验结果表明,语音的抑郁识别精度可以达到82.9%.本文采用机器学习方法,基于语音变量建立有效的抑郁症自动识别模型,为抑郁症的辅助识别提供客观的指标和依据.

社会媒体大数据视角下经济发展对集体道德的影响模式

集体道德反映了群体在道德上的共同特征,受经济发展因素影响很大,深入研究经济发展对集体道德的影响模式有助于培养积极健康的社会心态.传统的问卷和量表等自陈形式虽能有效测得个体的心理特征,但难以高效率大范围地开展,社会媒体大数据的出现为道德研究提供了新的契机.本研究利用2011~2017年间的社会媒体大数据,跨时间、跨空间地检验了地区经济指标与道德重视度之间的关系.结果显示,经济的发展水平与人们的道德重视程度呈显著正相关,主要体现在多元道德的忠诚维度(β=0.14,t=2.68,P<0.01).发展速度则与道德重视度呈显著负相关,体现在道德的关爱(β=-0.58,t=-10.16,P<0.01)、忠诚(β=-0.65,t=-12.69,P<0.01)、权威(β=-0.30,t=-4.29,P<0.01)和圣洁维度(β=-0.65,t=-6.20,P<0.01),但这种负面关系主要存在于在经济水平较低且发展速度较快的情况下.随着经济水平的提高,发展速度与道德重视度之间的相关强度会随之减弱.本研究通过大数据分析的方式发现了经济发展对于集体道德的潜在影响模式,即经济水平的提高可能有利于集体道德的提升,而发展速度过快则有可能产生负面效应.研究结果为建立良性的集体道德提供了科学的支撑,也为今后深入研究经济与道德的关系提供了新的思路.

Residential electrical vehicle charging strategies:the good,the bad and the ugly

In recent years,a wide variety of centralised and decentralised algorithms have been proposed for residential charging of electric vehicles(EVs).In this paper,we present a mathematical framework which casts the EV charging scenarios addressed by these algorithms as optimisation problems having either temporal or instantaneous optimisation objectives with respect to the different actors in the power system.Using this framework and a realistic distribution network simulation testbed,we provide a comparative evaluation of a range of different residential EV charging strategies,highlighting in each case positive and negative characteristics.

Tailoring activation sites of metastable distorted 1T′-phase MoS_(2) by Ni doping for enhanced hydrogen evolution

Heteroatom doping is a promising approach to enhance catalytic activity by modulating physical properties,electronic structure,and reaction pathway.Herein,we demonstrate that appropriate Ni-doping could trigger a preferential transition of the basal plane from 2H(trigonal prismatic)to 1T′(clustered Mo)by inducing lattice distortion and S vacancy(SV)and thus dramatically facilitate its catalytic hydrogen evolution activity.It is noteworthy that the unique catalysts did possess superior catalytic performance of hydrogen evolution reaction(HER).The rate of photocatalytic hydrogen evolution could reach 20.45 mmol·g^(−1)·h^(−1) and reduced only slightly in the long period of the photocatalytic process.First-principles calculations reveal that the distorted Ni-1T′-MoS_(2) with SV could generate favorable water adsorption energy(Ead(H_(2)O))and Gibbs free energy of hydrogen adsorption(∆GH).This work exhibits a facile and promising pathway for synergistically regulating physical properties,electronic structure,or wettability based on the doping strategy for designing HER electrocatalysts.

Revisiting lithium-storage mechanisms of molybdenum disulfide

Molybdenum disulfide(MoS_(2)),a typical two-dimensional transition metallic layered material,attracts tremendous attentions in the electrochemical energy storage due to its excellent physicochemical properties.However,with the deepening of the research and exploration of the lithium storage mechanism of these advanced MoS_(2)-based anode materials,the complex reaction process influenced by internal and external factors hinders the exhaustive understanding of the lithium storage process.To design stable anode material with high performance,it is urgent to review the mechanisms of reported anode materials and summarize the related factors that influence the reaction processes.This review aims to dissect all possible side reactions during charging and discharging process,uncover internal and external factors inducing various anode reactions and finally put forward strategies of controlling high cycling capacity and super-stable lithium storage capability of MoS_(2).This review will be helpful to the design of MoS_(2)-based lithium-ion batteries(LIBs) with excellent cycle performance to enlarge the application fields of these advanced electrochemical energy storage devices.

A pioneering survey of deep-diving and off-shore cetaceans in the northern South China Sea

A pioneering boat-based survey was conducted in 2019,to gather baseline information regarding the presence,composition,relative abundance,and spatial distribution of deep-diving and off-shore cetaceans in the northern South China Sea(SCS).A total of 27 sightings comprising at least 8 cetacean species were recorded during the 13-day survey,including 5 deep-diving species(i.e.Risso’s dolphin[Grampus griseus],short-finned pilot whale[Globicephala macrorhynchus],sperm whale[Physeter macrocephalus],Cuvier’s beaked whale[Ziphius cavirostris],and an unidentified beaked whale[either the ginkgo-toothed beaked whale,Mesoplodon ginkgodens,or Deraniyagala’s beaked whale,Mesoplodon hotaula]),as well as 3 off-shore dolphins(i.e.pantropical spotted dolphin[Stenella attenuate],striped dolphin[Stenella coeruleoalba],and Fraser’s dolphin[Lagenodelphis hosei]).With the exception of pantropical spotted dolphins,all other species were sighted and recorded at sea in the northern SCS for the first time.The pantropical spotted dolphin was the most frequently sighted species,comprising 30%of the total sightings.Deep-diving cetaceans were mainly sighted in the northern Xisha Archipelago,whereas off-shore dolphins were distributed across the survey area.The pantropical spotted dolphin was observed in aggregations of more than 100 individuals and nearly all encountered species included calves;these findings suggested that the survey area functions as an important feeding and calving ground for various cetacean species.This pioneering survey provides fundamental information regarding cetacean fauna in the northern SCS and highlights the need to strengthen research and conservation efforts concerning these species.

Ingeniously designed Ni-Mo-S/ZnIn_(2)S_(4) composite for multi-photocatalytic reaction systems

Molybdenum disulfide (MoS_(2)) with low cost, high activity and high earth abundance has been found to be a promising catalyst for the hydrogen evolution reaction (HER), but its catalytic activity is considerably limited due to its inert basal planes. Here, through the combination of theory and experiment, we propose that doping Ni in MoS_(2) as catalyst can make it have excellent catalytic activity in different reaction systems. In the EY/TEOA system, the maximum hydrogen production rate of EY/Ni-Mo-S is 2.72 times higher than that of pure EY, which confirms the strong hydrogen evolution activity of Ni-Mo-S nanosheets as catalysts. In the lactic acid and Na_(2)S/Na_(2)SO_(3) systems, when Ni-Mo-S is used as co-catalyst to compound with ZnIn_(2)S_(4) (termed as Ni-Mo-S/ZnIn_(2)S_(4)), the maximum hydrogen evolution rates in the two systems are 5.28 and 2.33 times higher than those of pure ZnIn_(2)S_(4), respectively. The difference in HER enhancement is because different systems lead to different sources of protons, thus affecting hydrogen evolution activity. Theoretically, we further demonstrate that the Ni-Mo-S nanosheets have a narrower band gap than MoS_(2), which is conducive to the rapid transfer of charge carriers and thus result in multi-photocatalytic reaction systems with excellent activity. The proposed atomic doping strategy provides a simple and promising approach for the design of photocatalysts with high activity and stability in multi-reaction systems.

First live sighting of Deraniyagala’s beaked whale(Mesoplodon hotaula)or ginkgo-toothed beaked whale(Mesoplodon ginkgodens)in the western Pacific(South China Sea)with preliminary data on coloration,natural markings,and surfacing patterns

Beaked whales represent around 25%of known extant cetacean species,yet they are the least known of all marine mammals.Identification of many Mesoplodon species has relied on examination of a few stranded individuals.Particularly,the ginkgo-toothed beaked whale(Mesoplodon ginkgodens)and Deraniyagala’s beaked whale(Mesoplodon hotaula)are among the least-known of beaked whale species,without confirmed sightings of living individuals to date.We present a sighting of 3 free-ranging individuals of M.ginkgodens/hotaula whale from a dedicated marine mammal vessel survey carried out in the South China Sea in April and May 2019.Photographic data(301 photographs)from the sighting were compared to photos of fresh stranded ginkgo-toothed beaked whale and Deraniyagala’s beaked whale from both historical and unpublished records.We found that free-ranging M.ginkgodens and M.hotaula individuals can be easily distinguished from other Mesoplodon species due to differences in melon and gape shapes and coloration patterns.However,accurate at-sea differentiation of M.ginkgodens and M.hotaula may not be possible due to high similarity in both coloration and scarring patterns.In addition to our photo-identification data,we collected what we believe to be the first preliminary descriptions of surfacing behavior and diving patterns of one of these species.Finally,the presence of scars possibly caused by fishing gear or marine litter raises concerns about anthropogenic impacts and conservation of these poorly known species.

Photo-identification comparison of four Indo-Pacific humpback dolphin populations off southeast China

Indo-Pacific humpback dolphins(Sousa chinensis)inhabit shallow coastal waters of the Indo-Pacific region including southeast China,with at least 6 putative populations identified to date in Chinese waters.However,the connectivity among these populations has not yet been fully investigated.In the present study,we compared and crossmatched photographic catalogs of individual dolphins collected to date in the Pearl River Delta region,Leizhou Bay,Sanniang Bay,and waters southwest of Hainan Island,a total of 3158 individuals,and found no re-sighting of individual dolphins among the 4 study areas.Furthermore,there was a notable difference in the pigmentation pattern displayed by individuals from these 4 regions.We suggest that this may be a phenotypical expression of fine-scale regional differentiation among humpback dolphin groups,possibly distinct populations.Given the considerable conservation management implications it may carry(e.g.definition of management units),further research is much needed.

Cetacean occurrence and diversity in whale-watching waters off Mirissa,Southern Sri Lanka

Scientific information is vital to the conservation of cetaceans and the management of whale-watching activities.The southern coastal waters of Sri Lanka are near a narrow continental shelf and biologically abundant in cetacean species.Although the occurrence of cetaceans has been investigated in certain waters of Sri Lanka,few surveys have been conducted along the southern coast.To fill this gap,we conducted boat-based surveys from January to May 2017 to investigate the occurrence,diversity,and behavior of cetaceans in the waters off Mirissa,covering a survey area of 788.9 km2.During 55 survey days,we recorded a total of 242 cetacean sightings and identified at least 9 species(3 mysticetes and 6 odontocetes).The blue whale was the most common mysticete species(167 of 174 mysticete encounters),followed by the Omura’s whale(4 of 174)and Bryde’s whale(3 of 174).The spinner dolphin was the most common odontocete species(28 of 68 odontocete encounters),followed by the sperm whale(18 of 68),common bottlenose dolphin(13 of 68),short-finned pilot whale(5 of 68),melon-headed whale(2 of 68),and killer whale.Blue whales and sperm whales exhibited a clear preference for outer shelf and high slope areas,and blue whales were observed feeding along these waters.The present study provides near-baseline information on cetacean occurrence and diversity in whale-watching waters off southern Sri Lanka,and highlights the urgent need for proper management strategies for whale-watching activities.

Potential impacts of shipping noise on Indo-Pacific humpback dolphins and implications for regulation and mitigation:a review

Shipping noise is a widespread and relatively loud sound source among human-induced underwater sounds.The impacts of shipping noise are of special concern for Indo-Pacific humpback dolphins(Sousa chinensis),as they inhabit shallow and nearshore habitats and are highly dependent on sound for survival.This study synthesizes our current understanding of the potential impacts of shipping noise on Indo-Pacific humpback dolphins combined with knowledge on sound production and hearing of these animals and the impacts of noise on other whales and dolphins.For further protection and management of Indo-Pacific humpback dolphins and their habitats,shipping noise should be regulated and mitigated to modify sound from ships,to reduce overall noise levels,and to set more marine protected areas(MPAs)covering most Indo-Pacific humpback dolphin habitats with seasonal and geographical restrictions to avoid ensonification of shipping noise.The emphasis for future research should be on obtaining more baseline information about the population distribution,sound production,hearing capabilities at the population level,behavior,and stress hormones of the humpback dolphins under different noise conditions or under different noise-producing activities,and/or in high-noise areas compared with relatively quiet areas,and the noise characteristics of ships of different types,sizes and speeds.

The biogeography of group sizes in humpback dolphins(Sousa spp.)

Humpback dolphins(Sousa spp.)are obligate shallow-water and resident species,and they typically live in fission–fusion societies composed of small-sized groups with changeable membership.However,we have scant knowledge of their behavioral ecology,starting with potential factors influencing inter-population variability of their group sizes.Here,we compiled a new global dataset of humpback dolphin group sizes based on 150 published records.Our data indicated an inter-specific consistency of group-living strategy among the 4 species in the Sousa genus,as these species preferred living in small-sized groups with a mean size of mostly no more than 10,a minimum size of single individual or small pairs,and a maximum size of several tens or≈100.In addition,we clearly showed the geographic variations in group sizes of humpback dolphins at a global scale.We found that the geographic variations in humpback dolphin group sizes were primarily associated with the latitude,sea surface temperature,and abundance.To conclude,our findings provide insights into social dynamics and socioecological trade-offs of humpback dolphins,and help better understand how these resident animals adapted to their shallow-water habitats from the perspectives of biogeography and socioecology.