氯化锌水溶液为溶剂制备的聚丙烯腈过滤膜

为了避免使用有机溶剂引起的环境污染问题,以高浓度氯化锌水溶液为溶剂,氧化-还原引发丙烯腈聚合得到的聚丙烯腈(PAN)为铸膜液,以水为凝固浴制备聚丙烯腈过滤膜,记为PAN(ZnCl2)膜。同时以二甲基甲酰胺(DMF)为溶剂溶解商品化PAN,以水为凝固浴制备PAN过滤膜,记为PAN(DMF)膜。通过扫描电子显微镜和X射线衍射对2种膜的形貌结构进行表征,研究了2种膜的力学性能、亲水性、抗污染性,以及对不同染料的过滤性能。结果表明,PAN(ZnCl2)膜比PAN(DMF)膜在亲水性、抗污染性、力学性能方面均有提高。在0.1 MPa的压力下,PAN(ZnCl2)膜的纯水通量达到70 L/(m2·h),染料溶液的通量在50~65 L/(m2·h),对刚果红(Mw=696.68)、直接黄27(Mw=662.62)和苋菜红(Mw=604.47)的截留率分别为100%、100%和55%;PAN(DMF)膜的水通量达到150 L/(m2·h),其对刚果红、直接黄27和苋菜红的截留率仅为92%、68%和19%,且膜易被染料污染。

Light-driven single-cell rotational adhesion frequency assay

The interaction between cell surface receptors and extracellular ligands is highly related to many physiological processes in living systems.Many techniques have been developed to measure the ligand-receptor binding kinetics at the single-cell level.However,few techniques can measure the physiologically relevant shear binding affinity over a single cell in the clinical environment.Here,we develop a new optical technique,termed single-cell rotational adhesion frequency assay(scRAFA),that mimics in vivo cell adhesion to achieve label-free determination of both homogeneous and heterogeneous binding kinetics of targeted cells at the subcellular level.Moreover,the scRAFA is also applicable to analyze the binding affinities on a single cell in native human biofluids.With its superior performance and general applicability,scRAFA is expected to find applications in study of the spatial organization of cell surface receptors and diagnosis of infectious diseases.

Effects of insect infestation on rodent-mediated dispersal of Quercus aliena:results from field and enclosure experiments

Rodents influence plant establishment and regeneration by functioning as both seed predators and dispersers.However,these rodent-plant interactions can vary significantly due to various environmental conditions and the activity of other insect seed predators.Here,we use a combination of both field and enclosure(i.e.individual cage and semi-natural enclosure)experiments,to determine whether rodents can distinguish sound seeds from those infested with insects.We also demonstrate how such responses to insects are influenced by food abun-dance and other environmental factors.We presented rodents with 2 kinds of Quercus aliena seeds(sound and insect-infested seeds)in a subtropical forest in the Qinling Mountains,central China,from September to No-vember of 2011 to 2013.The results showed that rodents preferred to hoard and eat sound seeds than infested seeds in the field and semi-natural enclosure,while they preferred to eat infested seeds over sound seeds in the individual cages.In addition,both hoarding and eating decisions were influenced by food abundance.Rodents hoarded more sound seeds in years of high food abundance while they consumed more acorns in years of food shortage.Compared with field results,rodents reduced scatter-hoarding behavior in semi-natural enclosures and ate more insect-infested seeds in smaller individual cages.These results further confirm that rodents distinguish infested seeds from non-infested seeds but demonstrate that this behavior varies with conditions(i.e.environ-ment and food abundance).We suggest that such interactions will influence the dispersal and natural regenera-tion of seeds as well as predation rates on insect larvae.

Bubble-pen lithography:Fundamentals and applications

Developing on-chip functional devices requires reliable fabrication methods with high resolution for miniaturization,desired components for enhanced performance,and high throughput for fast prototyping and mass production.Recently,laser-based bubble-pen lithography(BPL)has been developed to enable sub-micron linewidths,in situ synthesis of custom materials,and on-demand patterning for various functional components and devices.BPL exploits Marangoni convection induced by a laser-controlled microbubble to attract,accumulate,and immobilize particles,ions,and molecules onto different substrates.Recent years have witnessed tremendous progress in theory,engineering,and application of BPL,which motivated us to write this review.First,an overview of experimental demonstrations and theoretical understandings of BPL is presented.Next,we discuss the advantages of BPL and its diverse applications in quantum dot displays,biological and chemical sensing,clinical diagnosis,nanoalloy synthesis,and microrobotics.We conclude this review with our perspective on the challenges and future directions of BPL.

Biologically inspired silk fibroin grafted polyacrylonitrile filtration membrane prepared in ZnCl_2 aqueous solution

In this study, biologically inspired silk fibroin grafted polyacrylonitrile(SF-g-PAN) filtration membrane was prepared using ZnCl_2 aqueous solution as solvent, avoiding the use of organic solvents. Phase inversion occurred when Zn^(2+)and Cl-ions gradually diffused into water, creating a well-connected ion channel network and the SF-g-PAN filtration membrane was obtained. The membranes were observed by SEM and 3D ultra-depth microscope. The hydrophilic property, pore size distribution and dye rejection of the membrane were investigated. Results showed that the membrane has no finger hole formation because ZnCl_2 aqueous solution has a lower curing rate parameter compared with organic solvents. SF-gPAN membrane possessed good anti-fouling properties and pH sensitivity. The pore size distribution of the SF-g-PAN membrane was 0.25–1.04 nm. The rejection of direct yellow 27(Mw = 662.6) and amaranth(Mw = 604.5) was 96.51% and 30.63%, with the flux of 72.32 L m^(-2) h^(-1) and 73.83 L m^(-2) h^(-1) respectively at0.1 MPa. The SF-g-PAN membrane has a wide range of applications prospect in fine separation, dye desalination, waste water treatment and biomedical fields.

Optical Patterning of Two-Dimensional Materials

Recent advances in the field of two-dimensional(2D)materials have led to new electronic and photonic devices enabled by their unique properties at atomic thickness.Structuring 2D materials into desired patterns on substrates is often an essential and foremost step for the optimum performance of the functional devices.In this regard,optical patterning of 2D materials has received enormous interest due to its advantages of high-throughput,site-specific,and on-demand fabrication.Recent years have witnessed scientific reports of a variety of optical techniques applicable to patterning 2D materials.In this minireview,we present the state-of-the-art optical patterning of 2D materials,including laser thinning,doping,phase transition,oxidation,and ablation.Several applications based on optically patterned 2D materials will be discussed as well.With further developments,optical patterning is expected to hold the key in pushing the frontiers of manufacturing and applications of 2D materials.

Optothermally Assembled Nanostructures

CONSPECTUS:Nanofabrication is one of the core techniques in rapidly evolving nanoscience and nanotechnology.Conventional top-down nanofabrication approaches such as photolithography and electron beam lithography can produce high-resolution nanostructures in a robust way.However,these methods usually involve multistep processing and sophisticated instruments and have difficulty in fabricating three-dimensional complex structures of multiple materials and reconfigurability.Recently,bottom-up techniques have emerged as promising alternatives to fabricating nanostructures via the assembly of individual building blocks.In comparison to top-down lithographical methods,bottom-up assembly features the on-demand construction of superstructures with controllable configurations at single-particle resolution.The size,shape,and composition of chemically synthesized building blocks can also be precisely tailored down to the atomic scale to fabricate multimaterial architectural structures of high flexibility.Many techniques have been reported to assemble individual nanoparticles into complex structures,such as self-assembly,DNA nanotechnology,patchy colloids,and optically controlled assembly.Among them,the optically controlled assembly has the advantages of remote control,site-specific manipulation of single components,applicability to a wide range of building blocks,and arbitrary configurations of the assembled structures.In this Account,we provide a concise review of our contributions to the optical assembly of architectural materials and structures using discrete nanoparticles as the building blocks.By exploiting entropically favorable optothermal conversion and controlling optothermal−matter interactions,we have developed optothermal assembly techniques to manipulate and assemble individual nanoparticles.Our techniques can be operated both in solution and on solid substrates.First,we discuss the opto-thermoelectric assembly(OTA)of colloidal particles into superstructures by coordinating thermophoresis and interparticle depletion bonding in the solution.Localized laser heating generates a temperature gradient field,where the thermal migration of ions creates a thermoelectric field to trap charged particles.The depletion of ion species at the gap between closely positioned particles under optical heating provides strong interparticle bonding to stabilize colloidal superstructures with precisely controlled configurations and interparticle distances.Second,we discuss bubble-pen lithography(BPL)for the rapid printing of nanoparticles using an optothermal microbubble.The long-range convection flow induced by the optothermal bubble drags the colloidal particles to the substrate with a high velocity.BPL represents a general method for printing all kinds of building blocks into desired patterns in a high-resolution and high-throughput way.Third,we present the optothermally-gated photon nudging(OPN)technique,which manipulates and assembles particles on a solid substrate.Our solid-phase optical control of particles synergizes the modulation of particle−substrate interactions by optothermal effects and photon nudging of the particles by optical scattering forces.Operated on the solid surfaces without liquid media,OPN can avoid the undesired Brownian motion of nanoparticles in solutions to manipulate individual particles with high accuracy.In addition,the assembled structures can be actively reassembled into new configurations for the fabrication of tunable functional devices.Next,we discuss applications of the optothermally assembled nanostructures in surfaceenhanced Raman spectroscopy,color displays,biomolecule sensing,and fundamental research.Finally,we conclude this Account with our perspectives on the challenges,opportunities,and future directions in the development and application of optothermal assembly.