Toward High Carrier Mobility and Low Contact Resistance:Laser Cleaning of PMMA Residues on Graphene Surfaces

Poly(methyl methacrylate)(PMMA) is widely used for graphene transfer and device fabrication.However,it inevitably leaves a thin layer of polymer residues after acetone rinsing and leads to dramatic degradation of device performance.How to eliminate contamination and restore clean surfaces of graphene is still highly demanded.In this paper,we present a reliable and position-controllable method to remove the polymer residues on graphene films by laser exposure.Under proper laser conditions,PMMA residues can be substantially reduced without introducing defects to the underlying graphene.Furthermore,by applying this laser cleaning technique to the channel and contacts of graphene fieldeffect transistors(GFETs),higher carrier mobility as well as lower contact resistance can be realized.This work opens a way for probing intrinsic properties of contaminant-free graphene and fabricating high-performance GFETs with both clean channel and intimate graphene/metal contact.

Immunoglobulin genes and diversity: what we have learned from domestic animals

This review focuses on the diversity of immunoglobulin （Ig） genes and Ig isotypes that are expressed in domestic animals. Four livestock species--cattle, sheep, pigs, and horses--express a full range of Ig heavy chains （IgHs）, including t J, 6, y, c, and a. Two poultry species （chickens and ducks） express three IgH isotypes, la, u, and a, but not （5. The K and X light chains are both utilized in the four livestock species, but only the X chain is expressed in poultry. V（D）J recombination, somatic hypermutation （SHM）, and gene conversion （GC） are three distinct mechanisms by which immunoglobulin variable region diversity is generated. Different domestic animals may use distinct means to diversifyrearrancled variable reqions of la aenes.

Reduced graphene oxide-nano zero value iron(rGO-nZVI) micro-electrolysis accelerating Cr(Ⅵ) removal in aquifer

Nanoscale zero-valent iron （nZVI） assembled on graphene oxide （GO） （rGO-nZVI） composites were synthesized by reduction of GO and ferrous ions with potassium borohydride, for use in Cr（VI） removal from aqueous solution. The results showed that the two-dimensional structure of GO could provide a skeleton support for Fe0, thus overcoming the bottleneck of aggregation for nZVI. Also, rGO-nZVI would form a ferric-carbon micro-electrolysis system in Cr（VI）-contaminated aquifers, enhancing and accelerating electron transfer, exhibiting high rate and capacity for Cr（VI） removal. The optimum dosage of the applied rGO-nZVI was linearly correlated with the initial Cr（VI） concentration. Characterization of rGO-nZVI before and after reaction with Cr（VI） revealed the process of Cr（VI） removal： rGO-nZVI firstly transferred electrons from Fe0 cores via their Fe（II）/Fe（III） shells to the GO sheet; there, negatively charged Cr（VI） received electrons and changed into positively charged Cr（III）, which was adsorbed by the negatively charged GO sheet, avoiding the capping and passivating of nZVI rGO-nZVI formed a good electrically conductive network, and thus had long-term electron releasing properties, which was important for groundwater remediation.

Animal models for the atherosclerosis research:a review

Atherosclerosis is a leading cause of death worldwide,and its mechanisms are still unclear.However,various animal models have significantly advanced our understanding of the mechanisms involved in atherosclerosis and have allowed the evaluation of therapeutic options.The aim of this paper is to review those animal models(i.e.,rabbits,mice,rats,guinea pigs,hamsters,avian,carnivores,swine,and,non-human primates)that have been used to study atherosclerosis.Though there is no single perfect animal model that completely replicates the stages of human atherosclerosis,cholesterol feeding and mechanical endothelial injury are two common features shared by most models of atherosclerosis.Further,with the development of genetically modified animals,these models are significantly broadening our understanding of the pathogenesis of atherosclerosis.

Depletion of conventional mature B cells and compromised specific antibody response in bovine immunoglobulin μ heavy-chain transgenic mice

In this study,we introduced the bovine immunoglobulinμheavy-chain gene(the orphaned gene on BTA11)into mouse germline cells.Bovine IgM was highly expressed in selected transgenic lines,and it largely inhibited rearrangements of the endogenous immunoglobulin heavy chain(IgH)genes in these lines.The forced expression of bovine IgM resulted in reduced numbers of pro-and pre-B cells but increased the number of immature B cells in the transgenic mice.Bovine IgM-expressing B cells can migrate from the bone marrow to the spleen,but most of the cells are arrested at the T1 transitional B cell stage,leading to a significantly lower number of T2 transitional and mature B cells in the spleen.Although the serum concentrations of endogenous IgM and IgG in the transgenic mice were significantly decreased,the IgA levels were slightly increased compared to the WT mice.The bovine IgM level in the serum was only one-tenth to one-fifth of that of endogenous mouse IgM,suggesting that most of the serum immunoglobulin were contributed by endogenous IgH gene-expressing B cells.These transgenic mice also exhibited a lower frequency of unique complementarity determining region 3(CDR3)sequences in their VH repertoire and Vκrepertoire but exhibited an increased frequency of unique CDR3 in their Vλrepertoire.Compared to the WT mice,the transgenic mice had a significantly higher percentage of mouse IgMexpressing B cells that expressedλchains.Finally,we showed that the transgenic mice were deficient in a specific antibody response to antigen stimulation.

A comprehensive analysis of immunoglobulin heavy chain genes in the Bactrian camel(Camelus bactrianus)

Heavy chain only antibodies(HCAbs)represent a rare type of antibody that is devoid of light chains and the CH1 domain that have been reported in cartilaginous fish and camelids.By analyzing transcript data and genome sequences,we conducted a comprehensive analysis of Bactrian camel immunoglobulin heavy chain genes.Based on the transcript data,oneμgene,fiveγgenes,oneαgene and oneεgene were found.Additionally,the variable region of HCAbs(VHH)and the conventional antibodies(VH)sequences associated with theγ3,γ1a/b andμgenes were amplified.Based on these genome sequences,seven DH,six JH,μ,γ2a,γ2c,α,andεgenes and a portion of aγ3 gene were observed.Different Kozak sequences within different VH families were found in our analysis,and the variability index differed between the VHH3 and VH3 families.Phylogenetic analysis of the constant regions of the camelid immunoglobulin genes indicates that these genes appeared before the evolutionary divergence of Bactrian camels and dromedaries.