Large Modifications Research Articles

Study of the Photoswitching of a Fe(II) Chiral Complex through Linear and Nonlinear Ultrafast Spectroscopy.

Photoswitching the physical properties of molecular systems opens large possibilities for driving materials far from equilibrium toward new states. Moreover, ultrashort pulses of light make it possible to induce and to record photoswitching on a very short time scale, opening the way to fascinating new functionalities. Among molecular materials, Fe(II) complexes exhibit an ultrafast spin-state transition during which the spin state of the complex switches from a low spin state (LS, S = 0) to a high spin state (HS, S = 2). The latter process is remarkable: It takes place within ∼100 fs with a quantum efficiency of ∼100%. Moreover, the spin-state switching induces an important shift of the broad metal-to-ligand absorption band of the complex, and it results in large modifications of the physical and chemical properties of the compounds. But because most of the Fe(II) complexes crystallize in centrosymmetric space groups, this prevents them from exhibiting piezoelectric, ferroelectric, as well as second-order nonlinear optical properties such as second-harmonic generation (SHG). This considerably limits their potential applications. We have recently synthesized [Fe(phen)3] [Δ-As2(tartrate)2] chiral complexes that crystallize in a noncentrosymmetric 32 space group. Hereafter, upon the excitation of a thin film of these complexes by a femtosecond laser pulse and performing simultaneously transient absorption (TRA) and time-resolved SHG (TRSH) measurements, we have recorded the ultrafast LS to HS switching. Whereas a single TRA measurement gives only partial information, we demonstrate that TRSH readily reveals the different mechanisms in play during the HS-to-LS state relaxation. Moreover, a simple model makes it possible to evaluate the relaxation times as well as the hyperpolarizabilities of the different excited states through which the system travels during the spin-state transition.

Modified theory of gravity and clustering of multi-component system of galaxies

In this paper, we analyze the clustering of galaxies using a modified theory of gravity, in which the field content of general relativity has been be increased. This increasing in the field content of general relativity changes the large distance behavior of the theory, and in weak field approximation, it will also modify the large distance behavior of Newtonian potential. So, we will analyzing the clustering of multi-component system of galaxies interacting through this modified Newtonian potential. We will obtain the partition function for this multi-component system, and study the thermodynamics of this system. So, we will analyze the effects of the large distance modification to the Newtonian potential on Helmholtz free energy, internal energy, entropy, pressure and chemical potential of this system. We obtain also the modified distribution function and the modified clustering parameter for this system, and hence observe the effect of large distance modification of Newtonian potential on clustering of galaxies.

Matrix Metalloproteinase in Abdominal Aortic Aneurysm and Aortic Dissection.

Abdominal Aortic Aneurysm (AAA) affects 4–5% of men over 65, and Aortic Dissection (AD) is a life-threatening aortic pathology associated with high morbidity and mortality. Initiators of AAA and AD include smoking and arterial hypertension, whilst key pathophysiological features of AAA and AD include chronic inflammation, hypoxia, and large modifications to the extra cellular matrix (ECM). As it stands, only surgical methods are available for preventing aortic rupture in patients, which often presents difficulties for recovery. No pharmacological treatment is available, as such researchers are attempting to understand the cellular and molecular pathophysiology of AAA and AD. Upregulation of matrix metalloproteinase (MMPs), particularly MMP-2 and MMP-9, has been identified as a key event occurring during aneurysmal growth. As such, several animal models of AAA and AD have been used to investigate the therapeutic potential of suppressing MMP-2 and MMP-9 activity as well as modulating the activity of other MMPs, and TIMPs involved in the pathology. Whilst several studies have offered promising results, targeted delivery of MMP inhibition still needs to be developed in order to avoid surgery in high risk patients.

Myxoma virus jumps species to the Iberian hare.

The study of myxoma virus (MYXV) infections in the European rabbit (Oryctolagus cuniculus) has produced one of the most accepted host-pathogen evolutionary models. To date, myxomatosis has been limited to the European rabbit with sporadic reports in hares. However, reports of widespread mortalities in the Iberian hare (Lepus granatensis) with myxomatosis-like clinical signs indicate a potential species jump has occurred. The presence of MYXV DNA was confirmed by PCR in 244 samples received from regional veterinary services, animal health laboratories, hunters or rangers over a 5-month period. PCR analysis of 4 MYXV positive hare samples revealed a 2.8kb insertion located within the M009 gene with respect to MYXV. The presence of this insertion was subsequently confirmed in 20 samples from 18 Spanish provinces. Sanger sequencing and subsequent analysis show that the insert contained 4 ORFs which are phylogenetically related to MYXV genes M060, M061, M064 and M065. The complete MYXV genome from hare tissue was sequenced using Ion torrent next-generation technology and a summary of the data presented here. With the exception of the inserted region, the virus genome had no large scale modifications and 110 mutations with respect to the MYXV reference strain Lausanne were observed. The next phase in the evolution of MYXV has taken place as a host species jump from the European rabbit to the Iberian hare an occurrence which could have important effects on this naïve population.

Exploring the different environments effect of piperine via combined crystallographic, QM/MM and molecular dynamics simulation study

Piperine is a pungent alkaloid, largely present in the skin of pepper. It is the most active component of pepper and being used as a medicine in many Asian countries. The effect of piperine on memory impairment and neurodegeneration in Alzheimer's disease model has been investigated. In the present study, we aim to investigate the effect of piperine molecule in different environments (crystal and active site of proteins) from crystallography, molecular docking, QM/MM based charge density analysis and molecular dynamic simulation. The crystal structure of piperine has been used to determine the topological electron density of intermolecular interactions. The O-atoms of piperine is forming C–H⋅⋅⋅O interactions with the neighboring molecules in the crystal, these interactions also confirmed from the Hirshfeld surface. Further, to understand the nature of interactions and the conformational flexibility of piperine in the active site of recombinant human acetylcholinesterase (rhAChE), molecular docking analysis has been performed. The selected docked complex suggests favorable hydrogen bonding and hydrophobic interactions with rhAChE enzyme; notably, the O3 atom of piperine molecule forms strong hydrogen bonding interaction with Glu202 at 1.8 Å. To determine the charge density distribution and the electrostatic properties of piperine molecule in the active site of rhAChE, the piperine-rhAChE complex was minimized at QM/MM energy level; in which, the binding pocket with piperine was considered as QM region. The charge density analysis of piperine and the interacting amino acid groups have been carried out. The topological analysis of O3⋯H–O/Glu202 hydrogen bonding interaction exhibits strong interactions and the electron density ρcp(r): 0.242 eÅ−3 and the Laplacian ∇2ρcp(r): 3.176 eÅ−5 respectively. These results were compared with the corresponding molecule present in the crystal and gas phase environments of piperine. The comparison of active site structure with the corresponding crystal phase and gas phase structures reveal that piperine exhibits large conformational modification in the active site. The molecular dynamics simulation and binding free energy calculations were performed, this gives the stability, binding affinity of the molecule in the active site of rhAChE. The O3⋯H–O/Glu202 interaction shows the high stability (89.2%), this was confirmed from the stability of hydrogen bond analysis. The binding free energy was used to measure the rate of inhibition of enzyme in the presence of ligand molecule. The comparative study allows to understand the nature of piperine molecule in the gas and crystal phases, and amino acids environment.

Impact of polyelectrolytes on lysozyme properties in colloidal dispersions

In this work, we investigated the impact of different polyelectrolytes (polyacrylic acid, polystyrene sulfonate, dextran sulfate, and chondroitin sulfate) on lysozyme properties when they form colloidal complexes. To this aim, we characterized (i) the size and stability of the different polyelectrolyte-lysozyme complexes upon addition of NaCl (different concentrations) by diffusion light scattering, and (ii) the structure and accessibility of lysozyme active site in such complexes by fluorescence quenching and time resolved fluorescence analysis. We then used these results to explain the antibacterial activity variations among colloidal complexes and compared with free lysozyme. Our findings show that colloidal complexes that are more prone to swelling (i.e., lysozyme complexed with polystyrene sulfonate) are less stable upon salt addition. In these colloids, the enzymatic site is also more accessible. However, the antibacterial activity does not depend on the swelling properties because no large structural modification of the active site occurs.

Constant time recovery in Azure SQL database

Azure SQL Database and the upcoming release of SQL Server introduce a novel database recovery mechanism that combines traditional ARIES recovery with multi-version concurrency control to achieve database recovery in constant time, regardless of the size of user transactions. Additionally, our algorithm enables continuous transaction log truncation, even in the presence of long running transactions, thereby allowing large data modifications using only a small, constant amount of log space. These capabilities are particularly important for any Cloud database service given a) the constantly increasing database sizes, b) the frequent failures of commodity hardware, c) the strict availability requirements of modern, global applications and d) the fact that software upgrades and other maintenance tasks are managed by the Cloud platform, introducing unexpected failures for the users. This paper describes the design of our recovery algorithm and demonstrates how it allowed us to improve the availability of Azure SQL Database by guaranteeing consistent recovery times of under 3 minutes for 99.999% of recovery cases in production.

Effects of varying nitride concentration in Ar:N2 sputtering of indium-tin-oxide film for use as electrode in resistance switching device

In this paper, we have observed the deposition of ITO films using different mixtures of Ar and N2 gases, and examine the effects of increasing the N2 concentration. Compared to the use of pure Ar to deposit pure ITO film, incorporating N2 with Ar for the deposition causes many differences in the structural and optical characteristics of the ITON film. Material analyses, including scanning electron microscopy (SEM) and atomic force microscopy (AFM), confirm the surface morphologies of the ITON films for different ratios of Ar and N2. Depositions using N2 induced large surface modifications on the ITON films. In addition, the X-ray diffractometer (XRD) results suggested that increasing the concentrations of N2 will alter the originally polycrystalline ITO film to an amorphous ITON film under conditions of higher N2 gas flow. As for optical properties, the higher N2 gas flow caused a decrease in the film transparency, especially for shorter wavelengths below 500 nm within the visible spectrum. As for electrical properties, ITON films all exhibit lower conductivity than the pure ITO film, possibly due to the decrease of carrier concentration and carrier mobility. We then applied these results in an HfO2-based RRAM, where the ITO film acted as a top electrode, in order to examine the effects on the forming processes. Experimental results show that while the distributions of forming voltages exhibited very little difference, the self-compliance current varied with the concentration of N2 gas.

Construction of Electrospun Organic/Inorganic Hybrid Nanofibers for Drug Delivery and Tissue Engineering Applications

Electrospun nanofibers hold a great potential in biomedical applications due to their advantages of large specific surface area, good biocompatibility, easy fabrication and surface modification. In particular, organic/inorganic hybrid nanofibers exhibit enhanced mechanical properties and long-term sustained release or controlled release profile of encapsulated drugs, which enables hybrid nanofibers to serve as desired platform for drug delivery and tissue engineering applications. This review summarizes the recent progresses in the preparation, performances and applications of hybrid nanofibers as drug delivery vectors for antibacterial and antitumor therapy, and as nanofibrous scaffolds for bone tissue engineering or other types of tissue engineering applications. Nanofibers doped with various types of inorganic nanoparticles (e.g., halloysite, laponite®, nano-hydroxyapatite, attapulgite, carbon nanotubes, and graphene, etc.) are introduced and summarized in detail. Future perspectives are also briefly discussed.

Comparison of Fragmentation Functions for Jets Dominated by Light Quarks and Gluons from pp and Pb+Pb Collisions in ATLAS.

Charged-particle fragmentation functions for jets azimuthally balanced by a high-transverse-momentum, prompt, isolated photon are measured in 25 pb^{-1} of pp and 0.49 nb^{-1} of Pb+Pb collision data at 5.02TeV per nucleon pair recorded with the ATLAS detector at the Large Hadron Collider. The measurements are compared to predictions of MonteCarlo generators and to measurements of inclusively selected jets. In pp collisions, a different jet fragmentation function in photon-tagged events from that in inclusive jet events arises from the difference in fragmentation between light quarks and gluons. The ratios of the fragmentation functions in Pb+Pb events to that in pp events are used to explore the parton color-charge dependence of jet quenching in the hot medium. In relatively peripheral collisions, fragmentation functions exhibit a similar modification pattern for photon-tagged and inclusive jets. However, photon-tagged jets are observed to have larger modifications than inclusive jets in central Pb+Pb events.

Maximum energy dissipation for elasto-plastic plates via isogeometric shape optimization

In this research, optimum shape of plate structures is sought to maximize the energy dissipation via structural shape optimization. To achieve this, isogeometric analysis (IGA) is utilized for structural analysis of plates considering elasto-plastic behavior of materials. The von Mises material model is employed for this purpose. Non-uniform rational B-splines basis functions are used for both geometry definition and approximating the unknown deformation field. The optimization problem is to maximize the structural dissipated energy until a prescribed displacement is reached and a fixed amount of material is considered in the design domain. A direct shape sensitivity analysis is performed and a mathematical based approach is employed for the optimization process. To demonstrate the efficiency of the proposed algorithm three examples are illustrated. Using the IGA prevents adjusting analysis model during the optimization process, which is time-consuming especially when iterative nonlinear analysis is performed. The results also show that large geometry modifications can be properly managed by the proposed algorithm.

Fast and Exact Algorithm for Structural Static Reanalysis Based on Flexibility Disassembly Perturbation

Fast static reanalysis techniques are very important tools often used in structural optimization design. Generally, the existing exact methods for static reanalysis are only suitable for low-rank modifications. To combat this drawback, this paper presents a new exact method for structural static reanalysis based on flexibility disassembly perturbation. The proposed method is both exact and computationally efficient, and can be applied to many types of modifications in design, including low-rank modification, high-rank modification, small modification, and large modification. The effectiveness of the presented method is demonstrated using three truss structures. It has been shown that the results obtained by the proposed reanalysis method are the same as those obtained by the complete analysis. Compared with the existing exact methods, the proposed reanalysis method has obvious advantages in solving the high-rank large modification problem.

Proteomic and lipidomic analyses of the Arabidopsis atg5 autophagy mutant reveal major changes in endoplasmic reticulum and peroxisome metabolisms and in lipid composition.

Autophagy is a universal mechanism in eukaryotic cells that facilitates the degradation of unwanted cell constituents and is essential for cell homeostasis and nutrient recycling. The salicylic acid-independent effects of autophagy defects on leaf metabolism were determined through large-scale proteomic and lipidomic analyses of atg5 and atg5/sid2 mutants under different nitrogen and sulfur growth conditions. Results revealed that irrespective of the growth conditions, plants carrying the atg5 mutation presented all the characteristics of endoplasmic reticulum (ER) stress. Increases in peroxisome and ER proteins involved in very long chain fatty acid synthesis and β-oxidation indicated strong modifications of lipid metabolism. Lipidomic analyses revealed changes in the concentrations of sphingolipids, phospholipids and galactolipids. Significant accumulations of phospholipids and ceramides and changes in GIPCs (glycosyl-inositol-phosphoryl-ceramides) in atg5 mutants indicated large modifications in endomembrane-lipid and especially plasma membrane-lipid composition. Decreases in chloroplast proteins and galactolipids in atg5 under low nutrient conditions, indicated that chloroplasts were used as lipid reservoirs for β-oxidation in atg5 mutants. In conclusion, this report demonstrates the strong impact of autophagy defect on ER stress and reveals the role of autophagy in the control of plant lipid metabolism and catabolism, influencing both lipid homeostasis and endomembrane composition.

Onset and demise of coral reefs, relationship with regional ocean circulation on the Wyville Thomson Ridge

Results from a vibrocore collected on the northern edge of the Scottish continental shelf at around 300 m water depth, on the Wyville Thomson Ridge, enable to reconstruct the history of cold water coral (CWC) reef growth and demise during the Holocene period. We report on significant age differences between U/Th and 14C dates obtained on pristine well-preserved CWC (Lophelia pertusa), which may reflect an diagenetic process that standard quality tests have failed to highlight. Additional 14C dates derived from bivalve fragments (Venus sp.) and foraminifera (Cibicides refulgens) samples show a gradual ageing with core depth but with significant age inversions in the lower section of the sediment core, which we consider reflects sedimentary mixing. We thus chose to derive an independent age model using planktonic foraminifera Globigerina bulloides stable isotope profiles. The vibrocore record is divided into 3 phases: 1- Mixed sediment deposits of glacial age corresponding to the base of the core with ages older than 13 cal ka BP, 2- The end of the deglacial/early Holocene between 13 and 9 cal ka BP and 3- Finally, the Holocene period from around 9 cal ka BP with abundant Lophelia pertusa fossils. Siliciclastic grain size and clay mineralogical composition show two significant shifts at around 13 and 9 cal ka BP indicating changes in sedimentary sources and transport associated with the dynamics and flow patterns of surface currents during the deglaciation and Holocene. Our results show that the onset of CWC reef growth on the Wyville Thomson Ridge occurred around 9 cal ka BP and was associated with a shift in flow patterns of surface currents in this area. This change of circulation patterns induced favourable sedimentological and hydrological conditions for corals to grow, and is associated with large scale modifications of North Atlantic circulation patterns at the end of the deglaciation.

Highly siderophile element geochemistry and Re–Os isotopic systematics of carbonatites: Insights from Tamil Nadu, India

Carbonatite metasomatism has been widely implicated for worldwide mafic mantle suites but so far, no combined data have been available for highly siderophile element systematics (HSE – Os, Ir, Ru, Pt, Pd, Re) and Re–Os isotopic compositions in carbonatites themselves. We present the first systematic survey of the HSE and Re–Os isotopic compositions in a suite of well-characterized Neoproterozoic carbonatites, silicocarbonatites and associated silicate rocks (pyroxenites, monzogabbros, syenites) from south India in order to place constraints on the HSE systematics in carbonatite magmas, anchoring possible mantle sources of carbonatites and relationship to the ambient crustal lithologies as well as preliminary constraints on carbonatite metasomatism in Earth's mantle. The most plausible explanation for generally low HSE contents in calciocarbonatites from Tamil Nadu (∑HSE < 1.22 ppb) involves a low-degree (<1%) partial melting of the mantle source producing sulfur-saturated carbonatitic magmas leaving behind sulfide phases retaining HSE. The new data also indicate a strong FeO control on the distribution of Os and Pt during segregation of carbonatite melt from its enriched mantle source and/or melt differentiation. The combined 187Re/188Os values (from 0.10 to 217), 187Os/188Os ratios (0.186–10.4) and initial γOs values back-calculated to 800 Ma (from +0.1 to +6052) predict that most Tamil Nadu calciocarbonatites were plausibly derived from a carbonated peridotite source with <10% recycled component. This model would thus provide significant constraints on the origin/source of carbonatites, irrespective of their post-emplacement history. The unusual, volumetrically rare, Mg–Cr-rich silicocarbonatites (∑HSE = 14–41 ppb) display almost identical HSE patterns with those of host pyroxenites and predominantly high Pt (up to 38 ppb), the origin of which remains unknown. Positive co-variations between Pt, Pd and Re, and the well-developed positive correlation between Pt and MgO in these Mg–Cr-rich silicocarbonatites argue for a source coming predominantly from the upper mantle. The Re–Os isotopic systematics agree with direct incorporation of enriched mantle-derived material into parental melts but variable incorporation of potassium-rich crustal materials is evidenced by highly positive γOs800 Ma values for a sub-suite of Mg–Cr-rich silicocarbonatites, indicating intense fenitization. The highly radiogenic Os isotopic compositions of monzogabbros and a syenite argue for their derivation from crustal lithologies with no or only negligible contribution of mantle material. Collectively, low Ir, Ru, Pt and Pd contents found in the Tamil Nadu carbonatites appear to indicate the incapability to significantly modify the total budget of these elements in the Earth's mantle during carbonatite metasomatism. In contrast, very high Re/Os ratios found in some of the analyzed carbonatites, paralleled by extremely radiogenic 187Os/188Os signature, can produce large modification of the Re–Os isotopic composition of mantle peridotites during carbonatite melt percolation when high melt/rock ratios are achieved.

High-Throughput Platform for Efficient Chemical Transfection, Virus Packaging, and Transduction.

Intracellular gene delivery is normally required to study gene functions. A versatile platform able to perform both chemical transfection and viral transduction to achieve efficient gene modification in most cell types is needed. Here we demonstrated that high throughput chemical transfection, virus packaging, and transduction can be conducted efficiently on our previously developed superhydrophobic microwell array chip (SMAR-chip). A total of 169 chemical transfections were successfully performed on the chip in physically separated microwells through a few simple steps, contributing to the convenience of DNA delivery and media change on the SMAR-chip. Efficiencies comparable to the traditional transfection in multi-well plates (~65%) were achieved while the manual operations were largely reduced. Two transfection procedures, the dry method amenable for the long term storage of the transfection material and the wet method for higher efficiencies were developed. Multiple transfections in a scheduled manner were performed to further increase the transfection efficiencies or deliver multiple genes at different time points. In addition, high throughput virus packaging integrated with target cell transduction were also proved which resulted in a transgene expression efficiency of >70% in NIH 3T3 cells. In summary, the SMAR-chip based high throughput gene delivery is efficient and versatile, which can be used for large scale genetic modifications in a variety of cell types.

Modification of Vip3Ab1 C-Terminus Confers Broadened Plant Protection from Lepidopteran Pests.

Vegetative insecticidal proteins (Vips) from Bacillus thuringiensis (Bt) are unique from crystal (Cry) proteins found in Bt parasporal inclusions as they are secreted during the bacterial vegetative growth phase and bind unique receptors to exert their insecticidal effects. We previously demonstrated that large modifications of the Vip3 C-terminus could redirect insecticidal spectrum but results in an unstable protein with no lethal activity. In the present work, we have generated a new Vip3 protein, Vip3Ab1-740, via modest modification of the Vip3Ab1 C-terminus. Vip3Ab1-740 is readily processed by midgut fluid enzymes and has lethal activity towards Spodoptera eridania, which is not observed with the Vip3Ab1 parent protein. Importantly, Vip3Ab1-740 does retain the lethal activity of Vip3Ab1 against other important lepidopteran pests. Furthermore, transgenic plants expressing Vip3Ab1-740 are protected against S. eridania, Spodoptera frugiperda, Helicoverpa zea, and Pseudoplusia includens. Thus, these studies demonstrate successful engineering of Vip3 proteins at the C-terminus to broaden insecticidal spectrum, which can be employed for functional expression in planta.

CRISPR-READI: Efficient Generation of Knockin Mice by CRISPR RNP Electroporation and AAV Donor Infection

Genetically engineered mouse models harboring large sequence insertions or modifications are critical for a wide range of applications including endogenous gene tagging, conditional knockout, site-specific transgene insertion, and gene replacement; however, existing methods to generate such animals remain laborious and costly. To address this, we developed an approach called CRISPR-READI (CRISPR RNP electroporation and AAV donor infection), combining adeno-associated virus (AAV)-mediated HDR donor delivery with Cas9/sgRNA RNP electroporation to engineer large site-specific modifications in the mouse genome with high efficiency and throughput. We successfully targeted a 774bp fluorescent reporter, a 2.1 kb CreERT2 driver, and a 3.3 kb expression cassette into endogenous loci inboth embryos and live mice. CRISPR-READI is applicable to most widely used knockin schemes requiring donor lengths within the 4.9 kb AAV packaging capacity. Altogether, CRISPR-READI is an efficient, high-throughput, microinjection-free approach for sophisticated mouse genome engineering with potential applications in other mammalian species.

Rapid transcriptional responses to serum exposure are associated with sensitivity and resistance to antibody-mediated complement killing in invasive Salmonella Typhimurium ST313

Background: Salmonella Typhimurium ST313 exhibits signatures of adaptation to invasive human infection, including higher resistance to humoral immune responses than gastrointestinal isolates. Full resistance to antibody-mediated complement killing (serum resistance) among nontyphoidal Salmonellae is uncommon, but selection of highly resistant strains could compromise vaccine-induced antibody immunity. Here, we address the hypothesis that serum resistance is due to a distinct genotype or transcriptome response in S. Typhimurium ST313. Methods: Six S. Typhimurium ST313 bloodstream isolates, three of which were antibody resistant, were studied. Genomic content (single nucleotide polymorphisms and larger chromosomal modifications) of the strains was determined by Illumina and PACBIO sequencing, and functionally characterized using RNA-seq, transposon directed insertion site sequencing (TraDIS), targeted gene deletion and transfer of selected point mutations in an attempt to identify features associated with serum resistance. Results: Sequence polymorphisms in genes from strains with atypical serum susceptibility when transferred from strains that were highly resistant or susceptible to a strain that exhibited intermediate susceptibility did not significantly alter serum killing phenotype. No large chromosomal modifications typified serum resistance or susceptibility. Genes required for resistance to serum identified by TraDIS and RNA-seq included those involved in exopolysaccharide synthesis, iron scavenging and metabolism. Most of the down-regulated genes were associated with membrane proteins. Resistant and susceptible strains had distinct transcriptional responses to serum, particularly related to genes responsible for polysaccharide biosynthesis. There was higher upregulation of wca locus genes, involved in the biosynthesis of colanic acid exopolysaccharide, in susceptible strains and increased expression of fepE, a regulator of very long-chain lipopolysaccharide in resistant strains. Conclusion: Clinical isolates of S. Typhimurium ST313 exhibit distinct antibody susceptibility phenotypes that may be associated with changes in gene expression on exposure to serum.

Preparation of porous silicon rubber membranes by breath figure method

ABSTRACTA series of porous silicon rubber membranes with regularity and uniform size had been prepared by breath figure method form polydimethylsiloxane and hydrogen silicon oil (Si‐H1341). Hydrophilicity and hydrophobicity of polymer, different methods of cast films, co‐solvents, solid particle dispersants, temperature, solution concentration, and molecular weight of silicon rubber are considered and discussed in the article to analyze effects of experiment situations on porosity of porous silicon rubber membranes. Remarkably, using the method of blending silicon rubber with branch hydrophilic silica‐gel, large area hydrophilic modification of the silicon rubber can be achieved, and it is easy to form pores with regular structure. With synergies of co‐solvents, the excellent porosity with more rounded pore shape and better regularity is acquired. The results indicate that the pore size of the silicon were affected greatly by the addition of co‐solvent, the boiling point of solvent, molecular weight of raw materials, and reaction temperature. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47912.