基于扩散强化的Pickering界面生物催化系统构建及CO_(2)矿化过程研究

CO_(2)的有效利用有助于解决环境和生态问题.碳酸酐酶(CA)等酶分子可精准活化CO_(2)分子以降低反应能垒,为CO_(2)的高效和高选择性转化提供了一种有前景的途径.然而,酶离开生物体后易失活,且难以重复利用.目前,包埋型固定化酶是常用且有效的提高酶稳定性与回用率的方法之一,但载体的存在会造成反应物CO_(2)内扩散阻力增加,降低反应活性.此外,CO_(2)酶促转化是一个气-液-固三相反应过程,反应体系中CO_(2)的外扩散性能也需要加强.金属有机骨架(MOFs),特别是咪唑酯骨架(ZIFs),常被用作酶固定化的载体.ZIFs的拓扑结构可被设计成不同形貌,进而通过ZIFs的结构工程来加强分子向其中的内扩散.Pickering乳液是指以固体颗粒代替常规表面活性剂而稳定的乳液.当固体颗粒具有催化活性时,催化剂颗粒会扩大液-液-固或气-液-固三相接触面积,从而有效协调反应物在不同相中的扩散时间.如果酶被用作这些颗粒的活性中心,所制备的Pickering乳液也可能具备类似的特性,可加强底物分子向酶的外扩散.本文选择两种具有不同结构的ZIFs(ZIF-L和ZIF-8),原位包埋CA后形成CA@ZIFs颗粒以稳定Pickeirng乳液.ZIF-L和CA@ZIF-L颗粒显示出独特的二维层状堆叠结构.ZIF-8和CA@ZIF-8颗粒呈棱角清晰的十二面体结构.与CA@ZIF-8颗粒相比,CA@ZIF-L颗粒显示出更大的孔径和更宽的孔径分布,这有助于CO_(2)从CA@ZIF-L颗粒表面扩散至酶活性中心.利用酶活测试来研究内扩散是否通过结构工程得到了加强,发现CA@ZIF-L颗粒的活性比CA@ZIF-8颗粒高22.3%,推测这是由于CA@ZIF-L颗粒特殊的十字花状结构会缩短CO_(2)从颗粒表面扩散至酶活性中心的距离.同时,十字花状结构可暴露更多的酶活性位点(CA@ZIF-L颗粒的暴露面积是CA@ZIF-8颗粒的~8倍),从而提升了反应物浓度并显示出更高的催化活性.本文还设计了吸附实验来进一步验证上述假设,发现BSA@ZIF-L颗粒对香豆素的吸附率远高于BSA@ZIF-8颗粒,说明与ZIF-8相比,酶包埋于ZIF-L具有更强的捕获小分子的能力,表明CO_(2)分子向CA@ZIF-L的扩散速度更快,即CA@ZIF-L的十字花状结构可强化系统的内扩散过程.进一步比较了PIBS和游离多酶体系的催化活性,将CO_(2)通入每个系统,在反应前20 min,PIBS的pH值下降速度比游离体系快得多,说明PIBS通过在气相和液相间构建更大的界面,缩短了CO_(2)向CA的扩散距离,从而提高了催化效率,促进了CO_(2)转化.上述假设也通过扩散动力学的计算得到了验证.为进一步研究PIBS的CO_(2)矿化能力,本文开展了CaCO_(3)矿化反应,发现PIBS的CaCO_(3)产量远高于游离多酶体系,表明构建的PIBS在强化内外扩散方面具有显著优势.最后,评估了PIBS在工业应用中的性能,由CA@ZIF-L和CA@ZIF-8颗粒构建的PIBS显示出较好的可回收性,在第8个循环后,PIBS仍可保持8.9 mg/5 min的CaCO_(3)产量.综上,PIBS可为CO_(2)的酶促转化和框架提供一个新方法和新平台.

Physico-mechanical properties of granite after cyclic thermal shock

Understanding rock mechanical behaviors after thermal shock is critically important for practical engineering application.In this context,physico-mechanical properties of Beishan granite,Gansu Province,China after cyclic thermal shock were studied using digital image correlation(DIC),acoustic emission(AE)monitoring,and microscopic observation.The results show that the peak strength and elastic modulus decreased gradually with increase in thermal shock cycle.However,the above two parameters showed no further changes after 10 thermal shock cycles.The loading stress ratio(i.e.the ratio of the current loading stress level to the peak stress in this state)corresponding to the occurrence of the uneven principal strain field and the local strain concentration zone on the surface of the granite specimen decreased with increase in thermal shock cycle.Three transformation forms of the standard deviation curves of the surface principal strain were found.For granite with fewer thermal shock cycles(e.g.no more than 2 cycles),the standard deviation curves exhibited approximately exponential growth in exponential form.With increase in thermal shock cycle,the S-shaped curve was dominant.After 10 thermal shock cycles,an approximate ladder-shaped curve was observed.It is displayed that AE activity was mainly concentrated around the peak strength zone of the granite specimen when the rock samples underwent fewer thermal shock cycles.With increase in thermal shock cycle,AE activity could occur at low loading stress levels.Microscopic observation further confirmed these scenarios,which showed that more microcracks were induced with increase in thermal shock cycle.The number of induced microcracks at the edge location of the granite specimen was significantly larger than that at the interior location.Finally,a continuum damage model was proposed to describe the damage evolution of the granite specimen after cyclic thermal shock during loading.

Rapid Isolation and Multiplexed Detection of Exosome Tumor Markers Via Queued Beads Combined with Quantum Dots in a Microarray

Tumor-derived exosomes are actively involved in cancer progression and metastasis and have emerged as a promising marker for cancer diagnosis in liquid biopsy.Because of their nanoscale size,complex biogenesis,and methodological limitations related to exosome isolation and detection,advancements in their analysis remain slow.Microfluidic technology offers a better analytic approach compared with conventional methods.Here,we developed a bead-based microarray for exosome isolation and multiplexed tumor marker detection.Using this method,exosomes are isolated by binding to antibodies on the bead surface,and tumor markers on the exosomes are detected through quantum dot(QD)probes.The beads are then uniformly trapped and queued among micropillars in the chip.This design benefits fluorescence observation by dispersing the signals into every single bead,thereby avoiding optical interference and enabling more accurate test results.We analyzed exosomes in the cell culture supernatant of lung cancer and endothelial cell lines,and different lung cancer markers labeled with three QD probes were used to conduct multiplexed detection of exosome surface protein markers.Lung cancer-derived samples showed much higher(~sixfold-tenfold)fluorescence intensity than endothelial cell samples,and different types of lung cancer samples showed distinctive marker expression levels.Additionally,using the chip to detect clinical plasma samples from cancer patients showed good diagnostic power and revealed a well consistency with conventional tests for serological markers.These results provide insight into a promising method for exosome tumor marker detection and early-stage cancer diagnosis.

Effect of the Inclination Angle on Slippage Loss in Gas-Liquid Two-Phase Flow

The lifting efficiency and stability of gas lift well are affected by the socalled slippage-loss effect in gas-liquid two-phase flow.The existing studies on this subject have generally been based on vertical and horizontal wells.Only a few of them have considered inclined pipes.In the present work a new focused study is presented along these lines.More specifically,we use the non-slip pressure drop model with Flanigan’s fluctuation correction coefficient formula(together with the parameters of slippage density,slippage pressure drop and slippage ratio)to analyze the influence of the inclination angle on slippage loss for different conditions(different gas-liquid superficial velocity and pipe diameters).Moreover,the“standard regression coefficient method”is used for multi-factor sensitivity analysis.The experimental results indicate that slippage loss is affected by multiple factors,and the influence of the inclination angle on slippage loss is less significant than other factors.The change of the slippage pressure drop with the superficial velocity of gas-liquid is similar to that of the total pressure drop.The inclination angles of 45°and 60°have the greatest influence on slippage loss.The correlation between slippage density and slippage ratio is not obvious.Using the so-called slippage ratio seems to be a more accurate option to evaluate the degree of slippage loss.

Immobilization of carbonic anhydrase for facilitated CO2 capture and separation

Carbonic anhydrase(CA)as a typical metalloenzyme in biological system can accelerate the hydration/dehydration of carbon dioxide(CO2,the major components of greenhouse gases),which performer with high selectivity,environmental friendliness and superior efficiency.However,the free form of CA is quite expensive(~RMB 3000/100 mg),unstable,and non-reusable as the free form of CA is not easy for recovery from the reaction environment,which severely limits its large-scale industrial applications.The immobilization may solve these problems at the same time.In this context,many efforts have been devoted to improving the chemical and thermal stabilities of CA through immobilization strategy.Very recently,a wide range of available inorganic,organic and hybrid compounds have been explored as carrier materials for CA immobilization,which could not only improve the tolerance of CA in hazardous environments,but also improve the efficiency and recovery to reduce the cost of large-scale application of CA.Several excellent reviews about immobilization methods and application potential of CA have been published.By contrast,in our review,we stressed on the way to better retain the biocatalytic activity of immobilized CA system based on different carrier materials and to solve the problems facing in practical operations well.The concluding remarks are presented with a perspective on constructing efficient CO2 conversion systems through rational combining CA and advanced carrier materials.

Geomechanical modeling of CO2 geological storage:A review

This paper focuses on the progress in geomechanical modeling associated with carbon dioxide(CO2)geological storage.The detailed review of some geomechanical aspects,including numerical methods,stress analysis,ground deformation,fault reactivation,induced seismicity and crack propagation,is presented.It is indicated that although all the processes involved are not fully understood,integration of all available data,such as ground survey,geological conditions,microseismicity and ground level deformation,has led to many new insights into the rock mechanical response to CO2injection.The review also shows that in geomechanical modeling,continuum modeling methods are predominant compared with discontinuum methods.It is recommended to develop continuum-discontinuum numerical methods since they are more convenient for geomechanical modeling of CO2geological storage,especially for fracture propagation simulation.The Mohr-Coulomb criterion is widely used in prediction of rock mass mechanical behavior.It would be better to use a criterion considering the effect of the intermediate principal stress on rock mechanical behavior,especially for the stability analysis of deeply seated rock engineering.Some challenges related to geomechanical modeling of CO2geological storage are also discussed.

Investigation of time domain characteristics of negative capacitance FinFET by pulse-train approaches

The HfO2-based ferroelectric field effect transistors(FeFET)have been widely studied for their ability in breaking the Boltzmann limit and the potential to be applied to low-power circuits.This article systematically investigates the transient response of negative capacitance(NC)fin field-effect transistors(FinFETs)through two kinds of self-built test schemes.By comparing the results with those of conventional FinFETs,we experimentally demonstrate that the on-current of the NC FinFET is not degraded in the MHz frequency domain.Further test results in the higher frequency domain show that the on-state current of the prepared NC FinFET increases with the decreasing gate pulse width at pulse widths below 100 ns and is consistently greater(about 80%with NC NMOS)than the on-state current of the conventional transistor,indicating the great potential of the NC FET for future high-frequency applications.

Improved performance of MoS_(2)FET by in situ NH_(3)doping in ALD Al_(2)O_(3)dielectric

Since defects such as traps and oxygen vacancies exist in dielectrics,it is difficult to fabricate a high-performance MoS_(2)field-effect transistor(FET)using atomic layer deposition(ALD)Al_(2)O_(3)as the gate dielectric layer.In this paper,NH_(3)in situ doping,a process treatment approach during ALD growth of Al_(2)O_(3),is used to decrease these defects for better device characteristics.MoS_(2)FET has been well fabricated with this technique and the effect of different NH_(3)in situ doping sequences in the growth cycle has been investigated in detail.Compared with counterparts,those devices with NH_(3)in situ doping demonstrate obvious performance enhancements:Ion/Ioff is improved by one order of magnitude,from 1.33×10^(5)to 3.56×10^(6),the threshold voltage shifts from-0.74 V to-0.12 V and a small subthreshold swing of 105 m V/dec is achieved.The improved MoS_(2)FET performance is attributed to nitrogen doping by the introduction of NH_(3)during the Al_(2)O_(3)ALD growth process,which leads to a reduction in the surface roughness of the dielectric layer and the repair of oxygen vacancies in the Al_(2)O_(3)layer.Furthermore,the MoS_(2)FET processed by in situ NH_(3)doping after the Al and O precursor filling cycles demonstrates the best performance;this may be because the final NH_(3)doping after film growth restores more oxygen vacancies to screen more charge scattering in the MoS_(2)channel.The reported method provides a promising way to reduce charge scattering in carrier transport for high-performance MoS_(2)devices.

First-principles Simulations of Tunneling FETs Based on van der Waals MoTe2/SnS2 Heterojunctions with Gate-to-drain Overlap Design

The electronic properties and transport properties of MoTe2/SnS2 heterostructure Tunneling FETs are investigated by the density functional theory coupled with non-equilibrium Green’s function method.Two dimensional(2D)monolayer MoTe2 and SnS2 are combined to a vertical van der Waals heterojunction.A small staggered band gap is formed in the overlap region,while larger gaps remain in the underlap source and drain regions of monolayer MoTe2 and SnS2 respectively.Such a type-II heterojunction is favorable for tunneling FET.Furthermore,we suggest short stack length and large gate-to-drain overlap to enhance the on-state current suppress the leakage current respectively.The numerical results show that at a low drain to source voltage Vds=0.05V,On/Off current ratio can reach 108 and the On-state currents is over 20μA/μm for ntype devices.Our results present that van der Waals heterostructure TFETs can be potential candidate as next generation ultra-steep subthreshold and low-power electronic applications.

通过高通量研究识别用于本征陡坡晶体管的原子级薄孤立能带沟道材料

Developing low-power FETs holds significant importance in advancing logic circuits,especially as the feature size of MOSFETs approaches sub-10 nanometers.However,this has been restricted by the thermionic limitation of SS,which is limited to 60 mV per decade at room temperature.Herein,we proposed a strategy that utilizes 2D semiconductors with an isolated-band feature as channels to realize subthermionic SS in MOSFETs.Through high-throughput calculations,we established a guiding principle that combines the atomic structure and orbital interaction to identify their sub-thermionic transport potential.This guides us to screen 192 candidates from the 2D material database comprising 1608 systems.Additionally,the physical relationship between the sub-thermionic transport performances and electronic structures is further revealed,which enables us to predict 15 systems with promising device performances for low-power applications with supply voltage below 0.5 V.This work opens a new way for the low-power electronics based on 2D materials and would inspire extensive interests in the experimental exploration of intrinsic steep-slope MOSFETs.

Dendrimer-induced synthesis of porous organosilica capsules for enzyme encapsulation

Organic matter-induced mineralization is a green and versatile method for synthesizing hybrid nanostructured materials,where the material properties are mainly influenced by the species of natural biomolecules,linear synthetic polymer,or small molecules,limiting their diversity.Herein,we adopted dendrimer poly(amidoamine)(PAMAM)as the inducer to synthesize organosilica-PAMAM network(OSPN)capsules for mannose isomerase(MIase)encapsulation based on a hard-templating method.The structure of OSPN capsules can be precisely regulated by adjusting the molecular weight and concentration of PAMAM,thereby demonstrating a substantial impact on the kinetic behavior of the MIase@OSPN system.The MIase@OSPN system was used for catalytic production of mannose from Dfructose.A mannose yield of 22.24% was obtained,which is higher than that of MIase in organosilica network capsules and similar to that of the free enzyme.The overall catalytic efficiency(kcat/Km)of the MIase@OSPN system for the substrate D-fructose was up to 0.556 s^(-1)·mmol^(-1)·L.Meanwhile,the MIase@OSPN system showed excellent stability and recyclability,maintaining more than 50% of the yield even after 12 cycles.

Sustainable thermal energy harvest for generating electricity

Electricity is the lifeblood of modern society.However,the predominant source of electricity generation still relies on non-renewable fossil fuels,whose combustion releases greenhouse gases contributing to global warming.The increasing demand for energy and escalating environmental concerns necessitate proactive measures to develop innovative green energy technologies capable of both cooling the Earth and generating electricity.Here,we look forward to an interdisciplinary power system integrating solar absorbers,radiative coolers,and thermoelectric generators.This system can simultaneously harvest thermal energy from the sun and from cold space,thereby transforming the challenges posed by global warming into opportunities for the production of clean electricity.We underscore recent advancements in this field and address key challenges while also exploring forward-looking opportunities in the foreseeable future.The proposed integrated energy technology achieves uninterrupted power supply through the unrestricted capture of thermal energy,offering a robust alternative pathway for next-generation sustainable energy technologies.

Gut microbiota bridges dietary nutrients and host immunity

Dietary nutrients and the gut microbiota are increasingly recognized to cross-regulate and entrain each other,and thus affect host health and immune-mediated diseases.Here,we systematically review the current understanding linking dietary nutrients to gut microbiota-host immune interactions,emphasizing how this axis might influence host immunity in health and diseases.Of relevance,we highlight that the implications of gut microbiota-targeted dietary intervention could be harnessed in orchestrating a spectrum of immune-associated diseases.

Nanophotonic catalytic combustion enlightens mid-infrared light source

The tunable mid-infrared source in a broad-spectrum heralds great scientific implications and remains a challenge.Nanolocalized catalytic combustion facilitates access to customizable infrared light sources.Here,we report on fabricating platinumalumina bilayer nano-cylinder arrays for methanol catalytic combustion,which enables them to act as an array of infrared point light sources,with wavelength tunable by controlling the flow rate of methanol/air mixture.We then propose a technique of integrating nanophotonic structures with catalytic combustion to engineer infrared light emission.We demonstrate a prototype of a topological photonic crystal catalyst array in which infrared emission can be enhanced significantly with highly vertical emission.This work establishes a framework of nanophotonic catalytic combustion for infrared light sources.

Removal of polycyclic aromatic hydrocarbons and phenols from coking wastewater by simultaneously synthesized organobentonite in a one-step process

The optimal condition for a one-step process removing organic compounds from coking wastewater by simultaneously synthesized organobentonite as a pretreatment was investigated.Results showed that sorption of organic compounds by organobentonite was positively correlated to the cation surfactant exchange on the bentonite and the octanol-water partition coefficient（Kow） of the solutes.With 0.75 g/L bentonite and 180 mg/L（60% of bentonite cation exchange capacity） cetyltrimethylammonium bromide,the removal efficiencies of the 16 polycyclic aromatic hydrocarbon（PAHs） specified by the US Environmental Protection Agency in coking wastewater except naphthalene were more than 90%,and that of benzo（a）pyrene was 99.5%.At the same time,the removal efficiencies of CODCr,NH3-N,volatile phenols,colour and turbidity were 28.6%,13.2%,8.9%,55% and 84.3%,respectively,and the ratio of BOD5/CODCr increased from 0.31 to 0.41.These results indicated that the one-step process had high removal efficiency for toxic and refractory hydrophobic organic compounds,and could improve the biodegradability of the coking wastewater.Therefore it could be a promising technology for the pretreatment of toxic and refractory organic wastewater.

Advanced Process and Electron Device Technology

This article reviews advanced process and electron device technology of integrated circuits,including recent featuring progress and potential solutions for future development.In 5 years,for pushing the performance of fin field-effect transistors(FinFET)to its limitations,several processes and device boosters are provided.Then,the three-dimensional(3 D)integration schemes with alternative materials and device architectures will pave paths for future technology evolution.Finally,it could be concluded that Moore’s law will undoubtedly continue in the next 15 years.

Direction controllable inverse transition radiation from the spatial dispersion in a graphene-dielectric stack

Transition radiation(TR) induced by electron–matter interaction usually demands vast accelerating voltages, and the radiation angle cannot be controlled. Here we present a mechanism of direction controllable inverse transition radiation(DCITR) in a graphene-dielectric stack excited by low-velocity electrons. The revealed mechanism shows that the induced hyperbolic-like spatial dispersion and the superposition of the individual bulk graphene plasmons(GPs) modes make the fields, which are supposed to be confined on the surface, radiate in the stack along a special radiation angle normal to the Poynting vector. By adjusting the chemical potential of the graphene sheets, the radiation angle can be controlled. And owing to the excitation of bulk GPs, only hundreds of volts for the accelerating voltage are required and the field intensity is dramatically enhanced compared with that of the normal TR. Furthermore, the presented mechanism can also be applied to the hyperbolic stack based on semiconductors in the infrared region as well as noble metals in the visible and ultraviolet region.Accordingly, the presented mechanism of DCITR is of great significance in particle detection, radiation emission,and so on.

Multiple exosome RNA analysis methods for lung cancer diagnosis through integrated on-chip microfluidic system

Exosomes are now raising focus as a prospective biomarker for cancer diagnostics and prognosis owing to its unique bio-origin and composition.Exosomes take part in cellular communication and receptor mediation and transfer their cargos(e.g.,proteins,m RNA and DNA).Quantitative analysis of tumor-related nucleic acid mutations can be a potential method to cancer diagnosis and prognosis in early stages.Here we present an integrated microfluidic system for exosome on-chip isolation and lung cancer RNA analysis through droplet digital PCR(dd PCR).Gradient dilution experiments show great linearity over a large concentration range with R^(2)=0.9998.Utilizing the system,four cell lines and two mutation targets were parallelly detected for mutation analysis.The experiments demonstrated mutation heterogeneity and the results were agree with cell researches.These results proved our integrated microfluidic system as a promising means for early cancer diagnosis and prognosis in the era of liquid biopsy.

Single-cell level point mutation analysis of circulating tumor cells through droplet microfluidics

Tumor heterogeneity plays a critical role in the determination of appropriate anticancer therapy.As cir-culating tumor cells(CTCs)contain all tumor-related information,the genetic changes on CTCs could help us choose the appropriate treatments for different patients.Single-base mutations are very common in tumor genetic changes which may result in drug resistance.Here,we introduce a single-cell mutation de-tection platform based on droplet microfluidics.This platform integrates cell capsulation,cell lysis,poly-merase chain reaction(PCR)and the observation process.The droplets’generation speed is over 6000 per minute and more than 600 cells could be encapsulated in one second.To verify the performance of our platform in practical use,we performed the mutation analysis of 4 kinds of cells with our platform and noted that the genetic status of each single cell was clearly discriminated.Moreover,these results agreed with those from direct sequencing.Compared with other forms of single-cell mutation detection techniques,our platform has high throughput,short experimental time and less experimental operations.

Bioinspired Centimeter-scale Sensor Free Obstacle-passing Robots with a Wireless Control System

Obstacle avoidance is of great importance for mobile robots since it provides protection for the robots’safety and ensures their routine operations.Sensors are proven to play an important role in robots obstacle avoidance,and they are useful as well.However,more sensors indicating additional space,larger weight load and more energy consumption.Reducing unnecessary sensors is conducive to the development of mobile robots and remains promising.Here we demonstrate Sensor Free Obstacle-Passing Robots(SFOPRs)inspired by flies using the Obstacle-passing strategy instead of Obstacle avoidance.The ability to autonomously adjust its direction after hitting obstacles and the ability to continuously hit obstacles are 2 key problems that need to be solved to build this robot.Owing to arc-shaped head design and undulating motion behaviors,the robots can autonomously adjust their direction to the outline of obstacles,such as a 90°corner,dispersive irregular obstacles,and even an"S"type channel without the assistance of any sensor.Besides,the caterpillar-like movement enables robots to continuously hit obstacles.Furthermore,collaborative awareness and mutual aid can be realized among two or more prototype robots,indicating simple yet functional units for future swarm robots.This study could provide a new strategy to pursue sensor-free obstacle-passing robots for future swarm robot applications.