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With the development of the Internet of Things and the popularity of smart terminal devices, mobile crowdsourcing systems are receiving more and more attention. However, the information overload of crowdsourcing platforms makes workers face difficulties in task selection. This paper proposes a task recommendation model based on the prediction of workers’ mobile trajectories. A recurrent neural network is used to obtain the movement pattern of workers and predict the next destination. In addition, an attention mechanism is added to the task recommendation model in order to capture records that are similar to candidate tasks and to obtain task selection preferences. Finally, we conduct experiments on two real datasets, Foursquare and AMT (Amazon Mechanical Turk), to verify the effectiveness of the proposed recommendation model.

Xinxin Li,1– 3 Yibao Chen,1– 3 Shuang Wang,1– 3 Xiaochao Duan,1– 3 Fenqiang Zhang,1– 3 Aizhen Guo,1– 3 Pan Tao,1– 3 Huanchun Chen,1– 3 Xiangmin Li,1– 3 Ping Qian1– 3 1State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei, 430070, People’s Republic of China; 2College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei, 430070, People’s Republic of China; 3Key Laboratory of Preventive Veterinary Medicine in Hubei Province, the Cooperative Innovation Center for Sustainable Pig Production, Wuhan, Hubei, 430070, People’s Republic of ChinaCorrespondence: Ping Qian, Tel +86-27-87282608, Fax +86-27-87282608, Email qianp@mail.hzau.edu.cnBackground: Methicillin-resistant Staphylococcus aureus (MRSA) is an important zoonotic pathogen worldwide. Infections due to MRSA are associated with higher mortality rates compared with methicillin-susceptible S. aureus. Meanwhile, bacteriophages have been shown to overcome the emergence of MRSA.Methods: Phage PHB22a, PHB25a, PHB38a, and PHB40a were isolated. Here, we evaluated the ability of a phage cocktail containing phages PHB22a, PHB25a, PHB38a, and PHB40a against MRSA S-18 strain in vivo and in vitro. Phage whole-genome sequencing, host-range determination, lytic activity, and biofilm clearance experiments were performed in vitro. Galleria mellonella larvae and a mouse systemic infection model to evaluate the efficacy of phage therapy in vivo.Results: The phage cocktail exhibited enhanced antibacterial and anti-biofilm effects compared to the single phage. Phage cocktail contained with Ca2+/Zn2+ significantly reduced the number of viable bacteria (24-h or 48-h biofilm) by more than 0.81-log compared to the phage cocktail alone. Furthermore, we demonstrated that the addition of Ca2+ and Zn2+ phage cocktail could increase the survival rate of G. mellonella larvae infected with S. aureus by 10% compared with phage cocktail alone. This was further confirmed in the mouse model, which showed a 2.64-log reduction of host bacteria S-18, when Ca2+ and Zn2+ were included in the cocktail compared with the phage cocktail alone.Conclusion: Our results indicated that phage cocktail supplemented with Ca2+/Zn2+ could effectively remove bacteria in biofilms and mice tissues infected with S. aureus.Keywords: methicillin-resistant Staphylococcus aureus, phage cocktail, metal ions, biofilm, phage therapy

Foot-and-mouth disease (FMD) is an acute, febrile, and highly contagious infectious disease common in cloven-hoofed animals. Outbreaks and epidemics of FMD can result in major economic losses of livestock. Using ferritin nanoparticles as the scaffold for an antigen can enhance the immunogenicity of the subunit vaccine and provide possible protection against FMD. We used a baculovirus expression system to express four recombinant proteins (VP1, VP1-Ft, G-H loop-Ft, and ferritin) and the protective immunity of the FMD ferritin nanoparticle vaccines was evaluated in mice. The recombinant subunit vaccines containing VP1, VP1-Ft, and G-H loop-Ft proteins significantly increased FMDV-specific IgG and IgG subclass antibody titers compared with the PBS group, as well as enhancing splenocyte proliferation and the expression of IL-4 and IFN-γ. The VP1 and VP1-Ft vaccines provided survival rates of 55.6% and 66.7%, respectively. The G-H loop-Ft vaccine provided a 77.8% survival rate compared with 100% survival in the inactivated vaccine group. The partial survival provided by the ferritin nanoparticle vaccines indicated that further study of the effects of the fused ferritin nanoparticle FMDV vaccines in animals is warranted.

The hysteresis in the transfer curve of MoS2 has significant impact on the device performance. However, the hysteresis mechanism is still not clear. Here, we investigate the hysteresis of the monolayer MoS2 by probing the local Fermi level variations as a function of the back gate voltage in different atmosphere using the Kelvin probe microscopy. While the Fermi level of the MoS2 in air is much lower than that in vacuum, both the MoS2 devices in vacuum and air show large Fermi level hysteresis. The Fermi level hysteresis direction is clock-wise, identical to that observed in the transfer curves. Both the hysteresis in Fermi level and transfer curve can be explained consistently by taking into account the charge trapping. Our findings confirm that carrier density modulation in MoS2 plays a vital role in the hysteresis, and provide insight into the hysteresis mechanism for the optimization of the device performance.

The oxygen adsorption can drastically alter the electronic properties of the 2D materials, which is usually difficult to be removed. In this work, we report the UV illumination induced desorption of the O2 molecules from the monolayer MoS2 surface by using the atmosphere dependent transport measurement, Kelvin probe microscopy, photoluminescence spectroscopy and X-ray photoelectron spectroscopy. Obvious increasing of the conductivity, rising of the Fermi level, and red shift of the photoluminescence peaks of the MoS2 were observed after the UV illumination in vacuum, indicating the elimination of the depletion effect from the oxygen adsorption. Such parameter changes can be reversibly recovered by the subsequent O2 exposure. Furthermore, obvious decreasing of the oxygen concentration after the UV illumination was also observed by X-ray photoelectron spectroscopy. Thus the UV induced O2 photodesorption effect is evidenced. The photo-excited charge transfer mechanism is proposed to account for the photodesorption effect. These results provide a nondestructive way to clean the MoS2 surface and manipulate the performance of the MoS2 based devices.

The emergence and worldwide spread of Methicillin-resistant Staphylococcus aureus (MRSA) pose a threat to human health. While bacteriophages are recognized as an effective alternative to treat infections caused by drug resistant pathogens, some bacteriophages in particular the temperate bacteriophage may also influence the virulence of the host bacteria in distinct ways. In this study, we isolated a bacteriophage vB_Saus_PHB21 from an epidermal sample of Siberian tiger (Panthera tigris altaica) using an MRSA strain SA14 as the indicator. Our following laboratory tests and whole genome sequencing analyses revealed that vB_Saus_PHB21 was a temperate bacteriophage belonging to the Siphoviridae family, and this bacteriophage did not contain any virulence genes. However, the integration of PHB21 genome into the host MRSA increased the bacterial capacities of cell adhesion, anti-phagocytosis, and biofilm formation. Challenge of the lysogenic strain (SA14+) caused severe mortalities in both Galleria mellonella and mouse models. Mice challenged with SA14+ showed more serious organ lesions and produced higher inflammatory cytokines (IL-8, IFN-γ and TNF-α) compared to those challenged with SA14. In mechanism, we found the integration of PHB21 genome caused the upregulated expression of many genes encoding products involved in bacterial biofilm formation, adherence to host cells, anti-phagocytosis, and virulence. This study may provide novel knowledge of “bacteria-phage-interactions” in MRSA.

The lytic bacteriophages have potential application value in the treatment of bacterial infections. However, the narrow host spectrum of these phages limits their range of clinical application. Here, we demonstrate the use of scarless Cas9-assisted recombination (no-SCAR) gene-editing technology to regulate phage–host range. We used phage PHB20 as the scaffold to create agents targeting different multidrug-resistant Escherichia coli by replacing its phage tail fiber gene (ORF40). The engineered phages were polyvalent and capable of infecting both the original host bacteria and new targets. Phage-tail fiber genes can be amplified by PCR to construct a recombinant phage PHB20 library that can deal with multidrug-resistant bacteria in the future. Our results provide a better understanding of phage–host interactions, and we describe new anti-bacterial editing methods.

TiO2 was widely considered as a promising material for gas sensing. However, developing TiO2 based O2 sensors working at room temperature is still challenging owing to the difficulties of desorbing oxygen adatoms from the TiO2 surface. Here, the influence of the UV irradiation on the desorption of the surface oxygen on the TiO2 films was investigated by using the atmosphere dependent electric transport, Kelvin probe microscopy and x-ray photoelectron spectroscopy. A lasting high conductivity and high Fermi level of the TiO2 film were observed after the UV irradiation in vacuum, which can be drastically suppressed by a subsequent O2 gas exposure. Thus the UV induced desorption of the surface oxygen is evidenced. Moreover a surface charge transfer model is proposed based on DFT calculations to account for the photodesorption mechanism. Utilizing such effect, the film conductivity was increased and the adsorption sites were actively recovered upon UV irradiation, thereby greatly enhanced the O2 gas sensitivity. Our findings provided a way to optimize the performance of the O2 sensors at room temperature with low cost and high efficiency.

To gain insight into the presence and nature of prophages in the black soldier fly (BSF; Hermetia illucens L. [Diptera: Stratiomyidae]) gut, we isolated and characterized a novel, temperate Escherichia bacteriophage designated vB_EcoS_PHB10 (PHB10). Electron microscopy analysis revealed that phage PHB10 has a long, flexible, non-contractile tail and belongs to the family Siphoviridae. The phage was found to be stable over a wide range of temperatures (4-37 °C) and pH values (pH 5-9), and it lysed two out of 13 Escherichia strains tested. The genome of PHB10 contains genes encoding a putative transcriptional regulator and an integrase, and it shows a high degree of similarity to a region of the Enterobacter cloacae MBRL1077 genome. Induction experiments revealed that phage PHB10 could be induced by different gut substrates, suggesting that diet might be a potential regulator of lytic/lysogenic switches in commensal lysogens.

Here we report the spectral-timing results of the black hole X-ray binary 4U 1630–47 during its 2021 outburst using observations from the Hard X-ray Modulation Telescope (Insight-HXMT). Type C quasi-periodic oscillations (QPOs) in ∼1.6–4.2 Hz and quasi-regular modulation (QRM) near 60 mHz are detected during the outburst. The mHz QRM has a fractional rms of ∼10%–16% in the 8–35 keV energy band with a Q factor (frequency/width) of ∼2–4. Benefiting from the broad energy band of Insight-HXMT, we study the energy dependence of the ∼60 mHz QRM in 1–100 keV for the first time. We find that the fractional rms of the mHz QRM increases with photon energy, while the time lags of the mHz QRM are soft and decrease with photon energy. Fast recurrence of the mHz QRM, in a timescale of less than 1 hr, has been observed during the outburst. During this period, the corresponding energy spectra moderately change when the source transitions from the QRM state to the non-QRM state. The QRM phenomenon also shows a dependence with the accretion rate. We suggest that the QRM could be caused by an unknown accretion instability aroused from the corona.

The locomotor behavior of creatures in nature can bring a lot of inspiration for the fabrication of soft actuators. In this paper, we fabricated a bionic light-driven swimming soft robot that can perform grasping of tiny objects and achieve the task of object transfer. By adding carbon nanotubes (CNTs), the temperature-sensitive hydrogels can be endowed with light-responsive properties. The fabricated composite hydrogel structure can control the contraction and expansion of volume by light, which is similar to the contraction and diastole behavior of muscles. The oscillation of the fish tail and the grasping action of the normally closed micromanipulator can be achieved by the control of the irradiation of the xenon light source. The bending of the bionic arm can be controlled by the irradiation of a near-infrared (NIR) laser, which transforms the spatial position and posture of the micromanipulator. The proposed scheme is feasible for miniaturized fabrication and application of flexible actuators. This work provides some important insights for the study of light-driven microrobots and light-driven flexible actuators.

The emergence and worldwide spread of Methicillin-resistant Staphylococcus aureus (MRSA) poses a threat to human health. While bacteriophages are recognized as an effective alternative to treat infections caused by drug resistant pathogens, some bacteriophages in particular the temperate bacteriophage may also influence the virulence of the host bacteria in distinct ways. In this study, we isolated a bacteriophage vB_Saus_PHB21 from an epidermal sample of Siberian tiger (Panthera tigris altaica) using a MRSA strain SA14 as the indicator. Our following laboratory tests and whole genome sequencing analyses revealed that vB_Saus_PHB21 was a temperate bacteriophage belonging to the Siphoviridae family, and this bacteriophage did not contain any virulence genes. However, the integration of PHB21 genome into the host MRSA increased the bacterial capacities of cell adhesion, cell invasion, anti-phagocytosis and biofilm formation. Challenge of the lysogenic strain (SA14+) caused severer mortalities in both Galleria mellonella and mouse models. Mice challenged with SA14+ showed more serious organ lesions and produced higher inflammatory cytokines (IL-8, IFN-γ and TNF-α) compared to those challenged with SA14. In mechanism, we found the integration of PHB21 genome caused the upregulated expression of many genes encoding products involved in bacterial biofilm formation, adherence and invasion to host cells, anti-phagocytosis, and virulence. This study may provide novel knowledge of “bacteria-phage-interactions” in MRSA.IMPORTANCEThe interaction between bacteriophage and bacteria is like a “double-edged sword”: phages can either kill bacteria, or they may contribute to the bacterial fitness and virulence. In general, phages have positive impacts on bacterial fitness and virulence mainly because they carry antimicrobial resistance genes (ARGs) and/or virulence factors encoding genes (VFGs) and they can spread these harmful genes to the host bacteria. However, we found those phages which do not harbor ARGs and/or VFGs may also enhance the bacterial fitness and virulence. In addition, we also found the integration of phage genomes may lead to the upregulated expression of virulence associated genes in bacteria. Our study may provide new insights to redefine the relationship between phage and bacteria, and the results may also remind a cautious way to set phage-therapy for bacterial infections, before which the safety of a phage intends to be used should be fully evaluated.

Protein-based self-assembling nanoplatforms exhibit superior immunogenicity compared with soluble antigens. Here, we present a comprehensive vaccine strategy for displaying classical swine fever virus (CSFV) E2 glycoprotein on the surface of ferritin (fe) nanocages. An E2-specific blocking antibody assay showed that the blocking rates in pE2-fe/Gel02 (84.3%) and a half-dose cohort of E2-fe/Gel02 (81.9%) were significantly higher (p &lt, 0.05) than that in a ferritin-free cohort of pE2/Gel02 (62.7%) at 21 days post immunization (dpi) in vivo. Furthermore, quantitation of neutralizing potency revealed that a highly significant difference (p &lt, 0.001) was observed between the pE2-fe/Gel02 cohort (1:32, equivalent to live-attenuated strain C at 1:32) and the pE2/Gel02 cohort (1:4) at 21 dpi. Moreover, the innate immune cytokines of IL-4 and IFN-&gamma, activated by the half-dose (20 &mu, g) cohort of E2-fe/Gel02 were equivalent to those elicited by the full dose (40 &mu, g) of purified E2 in the pE2/Gel02 cohort at most time points. In conclusion, we successfully obtained an antigen-displaying E2-ferritin nanoplatform and confirmed high ferritin-assisted humoral and cellular immunities. Our results provided a novel paradigm of self-assembling nanovaccine development for the defense and elimination of potentially pandemic infectious viral pathogens.

Acoustic-based microfluidics has been widely used in recent years for fundamental research due to its simple device design, biocompatibility, and contactless operation. In this article, the basic theory, typical devices, and technical applications of acoustic microfluidics technology are summarized. First, the theory of acoustic microfluidics is introduced from the classification of acoustic waves, acoustic radiation force, and streaming flow. Then, various applications of acoustic microfluidics including sorting, mixing, atomization, trapping, patterning, and acoustothermal heating are reviewed. Finally, the development trends of acoustic microfluidics in the future were summarized and looked forward to.

Cell separation has always been a key topic in academic research, especially in the fields of medicine and biology, due to its significance in diagnosis and treatment. Accurate, high-throughput and non-invasive separation of individual cells is key to driving the development of biomedicine and cellular biology. In recent years, a series of researches on the use of microfluidic technologies for cell separation have been conducted to solve bio-related problems. Hence, we present here a comprehensive review on the recent developments of microfluidic technologies for cell separation. In this review, we discuss several cell separation methods, mainly including: physical and biochemical method, their working principles as well as their practical applications. We also analyze the advantages and disadvantages of each method in detail. In addition, the current challenges and future prospects of microfluidic-based cell separation were discussed.

Enterococcus faecalis is an opportunistic pathogen that causes illnesses ranging from urinary tract infections to sepsis in humans and animals. However, the overuse of antibiotics has increased rates of drug resistance among E. faecalis isolates. Bacteriophages and their derivatives have recently been identified as good candidates for the treatment of drug-resistant bacterial infections. Here, we isolated a virulent E. faecalis phage, PHB08, using the double-layer plate method. The bioactivity of the phage was determined via one-step growth curve testing and bacterial killing assays, and whole-genome sequencing was performed using the Illumina HiSeq platform. In addition, protein expression and antibiofilm assays were performed to investigate the activity of the phage lysin. Results showed that PHB08 has a 55,244-bp linear double-stranded DNA genome encoding 91 putative coding sequences. PHB08 inhibited the growth of host strain EF3964 at 37 &deg, C in tryptic soy broth (TSB) medium, while in vegetable models, PHB08 caused a 4.69-log decrease in viable E. faecalis cells after 24 h. Both PHB08 and its endolysin lys08 showed antibiofilm activity against E. faecalis biofilms, which was enhanced by Mn2+ ions. Thus, virulent phage PHB08 and endolysin lys08 may be good candidates for reducing and/or eradicating E. faecalis infections.

Cell adhesion plays an important role in cell communication, organ formation and tissue maintenance. Spatial microstructure patterning has the capability to regulate cell functions such as cell adhesion and cell proliferation as well as cellular mechanical properties. In this study, we present a simple method to fabricate micro-hump patterned interfaces based on electrohydrodynamic jet (E-jet) printing to control and direct cell organization. Micro-hump structures were rapidly fabricated by E-jet printing and arbitrary cell patterns can be achieved by selective cell adhesion induced by this surface topography. Furthermore, cellular mechanical properties were regulated by changing the density of microstructures. The technique we proposed could dynamically direct cell organization in a controlled manner, providing help for exploring the fundamental mechanism of cell adhesion and sensing.

Shiga toxin-producing Escherichia coli (STEC) strains are important zoonotic foodborne pathogens, causing diarrhea, hemorrhagic colitis, and life-threatening hemolytic uremic syndrome (HUS) in humans. However, antibiotic treatment of STEC infection is associated with an increased risk of HUS. Therefore, there is an urgent need for early and effective therapeutic strategies. Here, we isolated lytic T7-like STEC phage PHB19 and identified a novel O91-specific polysaccharide depolymerase (Dep6) in the C terminus of the PHB19 tailspike protein. Dep6 exhibited strong hydrolase activity across wide ranges of pH (pH 4 to 8) and temperature (20 to 60°C) and degraded polysaccharides on the surface of STEC strain HB10. In addition, both Dep6 and PHB19 degraded biofilms formed by STEC strain HB10. In a mouse STEC infection model, delayed Dep6 treatment (3 h postinfection) resulted in only 33% survival, compared with 83% survival when mice were treated simultaneously with infection. In comparison, pretreatment with Dep6 led to 100% survival compared with that of the control group. Surprisingly, a single PHB19 treatment resulted in 100% survival in all three treatment protocols. Moreover, a significant reduction in the levels of proinflammatory cytokines was observed at 24 h postinfection in Dep6- or PHB19-treated mice. These results demonstrated that Dep6 or PHB19 might be used as a potential therapeutic agent to prevent STEC infection. IMPORTANCE Shiga toxin-producing Escherichia coli (STEC) is an important foodborne pathogen worldwide. The Shiga-like toxin causes diarrhea, hemorrhagic colitis, and life-threatening hemolytic uremic syndrome (HUS) in humans. Although antibiotic therapy is still used for STEC infections, this approach may increase the risk of HUS. Phages or phage-derived depolymerases have been used to treat bacterial infections in animals and humans, as in the case of the “San Diego patient” treated with a phage cocktail. Here, we showed that phage PHB19 and its O91-specific polysaccharide depolymerase Dep6 degraded STEC biofilms and stripped the lipopolysaccharide (LPS) from STEC strain HB10, which was subsequently killed by serum complement in vitro. In a mouse model, PHB19 and Dep6 protected against STEC infection and caused a significant reduction in the levels of proinflammatory cytokines. This study reports the use of an O91-specific polysaccharide depolymerase for the treatment of STEC infection in mice.

The Insight-Hard X-ray Modulation Telescope (Insight-HXMT) is a broad band X-ray and gamma-ray (1-3000 keV) astronomy satellite. The High Energy X-ray telescope (HE) is one of its three main telescopes. The main detector plane of HE is composed of 18 NaI(Tl)/CsI(Na) phoswich detectors, where NaI(Tl) serves as primary detector to measure ~ 20-250 keV photons incident from the field of view (FOV) defined by the collimators, and CsI(Na) is used as an active shield detector to NaI(Tl) by pulse shape discrimination. CsI(Na) is also used as an omnidirectional gamma-ray monitor. The HE collimators have a diverse FOV: 1.1{\deg}x 5.7{\deg} (15 units), 5.7{\deg}x 5.7{\deg} (2 units) and blocked (1 unit), thus the combined FOV of HE is about 5.7{\deg}x 5.7{\deg}. Each HE detector has a diameter of 190 mm, resulting in the total geometrical area of about 5100 cm_2. The energy resolution is ~15% at 60 keV. The timing accuracy is better than 10 {\mu}s and dead-time for each detector is less than 10 {\mu}s. HE is devoted to observe the spectra and temporal variability of X-ray sources in the 20-250 keV band either by pointing observations for known sources or scanning observations to unveil new sources, and to monitor the gamma-ray sky in 0.2-3 MeV. This paper presents the design and performance of the HE instruments. Results of the on-ground calibration experiments are also reported., Comment: Accepted by SCIENCE CHINA Physics, Mechanics & Astronomy

Cell patterning technology is an effective technique to understand cell behaviors by precisely controlling the position of cells revealing the major contributions of cells in basic and applied biological research in vitro. Therefore, this technology has led to the development of various micro-nano manufacturing methods. In recent years, various methods have been continuously improved and innovated based on existing methods to overcome shortcomings. We outline the latest developments in cell patterning technology, including stencil patterning, microfluidics-based on traps and droplets, and surface modification techniques such as photolithography, microcontact printing, and laser technology. In the end, we introduce the application and future prospects of cell patterning in biological research.

A novel virulent bacteriophage, vB_BbrM_PHB04, infecting Bordetella bronchiseptica was isolated from wastewater collected at a swine farm in China. Phage vB_BbrM_PHB04 exhibited growth over a wide range of temperature and pH conditions and showed different efficiency of plating values and lytic spectra within the same strains at 25 °C and 37 °C. High-throughput sequencing revealed that vB_BbrM_PHB04 has a linear double-stranded DNA genome with 124 putative open reading frames. Overall, the genome of vB_BbrM_PHB04 showed very low similarity (the highest nucleotide identity 82%, 1% coverage) to other phage sequences in the GenBank database. Phylogenetic analysis indicated that vB_BbrM_PHB04 is a new member of the family Myoviridae. In addition, polymerase chain reaction-based detection of phage genes in phage-resistant B. bronchiseptica variants revealed no evidence of lysogenic activity of phage vB_BbrM_PHB04. Electronic supplementary material The online version of this article (10.1007/s00705-018-4034-0) contains supplementary material, which is available to authorized users.

With its high theoretical capacity, Si has attracted great attention as an ideal anode material for the realization of Li-ion batteries with high energy density. The huge volume expansion and significant capacity fading of Si electrode are the biggest problems hindering its actual use. In this paper, an intricate hollow Si nanocomposite is designed involving two carbon layers, one void space, and one SiO2 layer as an electrode material to resolve the two issues mentioned above. The two carbon layers can increase the electric conductivity of the electrode. Besides, the void space and SiO2 layer in the Si/C/void/SiO2/C composite can provide multiple guarantees for the preservation of whole structure of the electrode. As a result, this novel structure can deliver a capacity of 900 mA h g-1 after 100 cycles at a current density of 100 mA g−1.

Exploring new perovskite-related solid-state materials and the investigating composition-dependent structural and physical properties are highly important for advanced functional material development. Herein, we present the successful hydrothermal synthesis of tetragonal CsPb2Cl5 and the anion-exchange phase formation of CsPb2(Cl1-xBrx)5 (x = 0-1) solid solutions. The CsPb2(Cl1-xBrx)5 crystal structures, which crystallize in the tetragonal system, space group 14/mcm, with parameters similar to those of CsPb2Cl5, have been determined by Rietveld analysis. The optical band gap was obtained by UV-vis spectroscopy, and the band structure was further calculated by the full-potential method within the generalized gradient approximation. It was revealed that the band gap in CsPb2(Cl1- xBrx)5 solid solutions can be tuned over the range of 4.5-3.8 eV by anion substitution.

Controlling the resistive switching parameters by using external fields is of great importance in the application of the resistive memory devices. In this work, we investigate the effect of light illumination and oxygen atmosphere on the resistive switching of the anatase phase polycrystalline TiO2 thin film using the in-situ conductive atomic force microscopy and Kelvin probe force microscopy. A forming free bipolar resistive switching effect with ON/OFF ratio over 104 was achieved in nanoscale uniformly on the film. The conduction characteristics can be changed from the non-rectifying behavior in vacuum to the Schottky rectifying behavior in oxygen gas with nearly the same ON/OFF ratio. The reversible surface potential shift accompanied by the resistance switching was also observed. Furthermore, the resistance states and the surface potential contrast can be erased by 395 nm near-UV illumination, demonstrating a good optical erasing performance of the device. Combining the surface potential shift and the response to the illumination and oxygen gas, a charge trapping/detrapping mechanism was confirmed to account for the observed switching behavior. These results provide a new way to fabricate the controllable and optical erasable resistive switching devices in nanoscale.

Pasteurella multocida is a leading cause of respiratory disease in pigs worldwide. In this study, we determined the genetic characteristics of 115 P. multocida isolates from the lungs of pigs with respiratory disease in China in 2015 using capsular typing, lipopolysaccharide (LPS) genotyping, and virulence genotyping based on the detection of virulence-associated genes. The results showed that the isolates belonged to three capsular types: A (49.6%), D (46.1%), and nontypable (4.3%); and two LPS genotypes: L3 (22.6%) and L6 (77.4%). When combining the capsular types with the LPS genotypes, a genotype group D: L6 (46.1%) was the most prevalent among the strains. Among the 23 virulence-associated genes detected in this study, a small number of them displayed a certain level of "genotype-preference". We found that pfhA, hgbA, and hgbB had a close association with P. multocida LPS genotypes, while tadD was more associated with P. multocida capsular types. In addition, multilocus sequence typing (MLST) on 40 P. multocida isolates identified four sequence types: ST3, ST10, ST11, and ST16, and the distribution of ST11 was significantly higher than the other MLST genotypes. Interestingly, all of the ST11 isolates detected in this study were genotype D: L6 strains and they were 100% positive for hgbB. Our data suggest that a capsule/LPS/MLST genotype D/L6/ST11 is likely to be strongly associated with respiratory clinical manifestation of the disease in pigs.