Sensitivity of SARS-CoV-2 to different temperatures

This study was designed to investigate the sensitivity of SARS-CoV-2 to different temperatures,to provide basic data and a scientific basis for the control of COVID-19 epidemic.The virus was dispersed in 1 mL basal DMEM medium at a final concentration of 103.2 TCID 50/mL and then incubated at 4,22,30,35,37,38,39 and 40°C for up to 5 days.The infectivity of residual virus was titrated using the Vero E6 cell line.The results showed that the virus remained viable for 5 days at 4°C,and for 1 day only at 22 and 30°C.We found that the infectivity of the virus was completely lost after less than 12 hours at 37,38 and 39°C,while at 40°C,the inactivation time of the virus was rapidly reduced to 6 hours.We show that SARS-CoV-2 is sensitive to heat,is more stable at lower temperatures than higher temperature,remains viable for longer at lower temperatures,and loses viability rapidly at higher temperatures.

Sequentially immune-induced antibodies could cross-neutralize SARS-CoV-2 variants

Background:The Omicron(B.1.1.529)SARS-COV-2 variant has raised serious concerns because of its unprecedented rapid rate of spreading and the fact that there are 36 mutations in the spike protein.Since the vaccine-induced neutralizing antibody targets are the spike protein,this may lead to the possibility of vaccine-induced hu-moral immunity escape.Methods:We measured the neutralizing activity in vitro for Omicron and compared this with wild type(WH-09)and Delta variants in human and monkey sera from different types of immunity.The monkey sera samples were collected at 1 and 3 months post three-dose inactivated(PiCoVacc)and recombinant protein(ZF2001)vaccination.Human sera were collected from 1 month post three-dose inactivated vaccination.Results:In inactivated vaccine sera,at 1/3 months post three-dose,geometric mean titers(GMTs)of neutralization antibody(NAb)against the Omicron variant were 4.9/5.2-fold lower than those of the wild type.In recombinant protein vaccine sera,GMTs of NAb against Omicron were 15.7/8.9-fold lower than those of the wild type.In human sera,at 1 month post three-dose inactivated vaccination,GMTs of NAb against Omicron were 3.1-fold lower than those of the wild type.Conclusion:This study demonstrated that despite a reduction in neutralization titers,cross-neutralizing activity against Omicron and Delta variants was still observed after three doses of inactivated and recombinant protein vaccination.

Space-confined vapor deposition synthesis of two dimensional materials

Two dimensional （2D） nanomaterials are promising fundamental building blocks for use in the next-generation semiconductor industry due to their unique geometry and excellent （opto）-electronic properties. However, large scale high quality fabrication of 2D nanomaterials remains challenging. Thus, the development of controllable fabrication methods for 2D materials is essential for their future practical application. In this review, we will discuss the importance of the space-confined vapor deposition strategy in the controllable fabrication of 2D materials and summarize recent progress in the utilization of this strategy for the synthesis of novel materials or structures. Using this method, various high quality ultrathin 2D materials, including large-area graphene and boron nitride, ReS2/ReSe2 HfS2, pyramid-structured multilayer MoS2, and the topological insulators BiaSe3 and BiaTe3, have been successfully obtained. Additionally, by utilizing van der Waals epitaxy growth substrates such as mica or other 2D materials, patterned growth of 2D nanomaterials can be easily achieved via a surface-induced growth mechanism. Finally, we provide a short prospect for future development of this strategy.

Approaching ohmic contact to two-dimensional semiconductors

Two-dimensional semiconductors have attracted immense research interests owing to their intriguing properties and promising applications in electronic and optoelectronic devices.However,the performance of these devices is drastically hindered by the large Schottky barrier at the electric contact interface,which is hardly tunable due to the Fermi level pinning effect.In this review,we will analyze the root causes of the contact problems for the two-dimensional semiconductor devices and summarize the strategies on the basis of different contact geometries,aiming to lift out the Fermi level pinning effect and achieve the ohmic contact.Moreover,the remarkable improvement of the device performance thanks to these optimized contacts will be emphasized.At the end,the merits and limitations of these strategies will be discussed as well,which potentially gives a guideline for handling the electric contact issues in two-dimensional semiconductors devices.

On a class of almost regular Landsberg metrics

There is a long existing "unicorn" problem in Finsler geometry: whether or not any Landsberg metric is a Berwald metric? Some classes of metrics were studied in the past and no regular non-Berwaldian Landsberg metric was found. However, if the metric is almost regular(allowed to be singular in some directions),some non-Berwaldian Landsberg metrics were found in the past years. All of them are composed by Riemannian metrics and 1-forms. This motivates us to ?nd more almost regular non-Berwaldian Landsberg metrics in the class of general(α, β)-metrics. In this paper, we ?rst classify almost regular Landsberg general(α, β)-metrics into three cases and prove that those regular metrics must be Berwald metrics. By solving some nonlinear PDEs,some new almost regular Landsberg metrics are constructed which have not been described before.

Sequential immunizations confer cross-protection against variants of SARS-CoV-2,including Omicron in Rhesus macaques

Variants of concern(VOCs)like Delta and Omicron,harbor a high number of mutations,which aid these viruses in escaping a majority of known SARS-CoV-2 neutralizing antibodies(NAbs).In this study,Rhesus macaques immunized with 2-dose inactivated vaccines(Coronavac)were boosted with an additional dose of homologous vaccine or an RBD-subunit vaccine,or a bivalent inactivated vaccine(Beta and Delta)to determine the effectiveness of sequential immunization.The booster vaccination significantly enhanced the duration and levels of neutralizing antibody titers against wild-type.

Strain-sensitive ferromagnetic two-dimensional Cr_(2)Te_(3)

Searching for room temperature magnetic two-dimensional(2D)materials is a charming goal,but the number of satisfied materials is tiny.Strain can introduce considerable deformation into the lattice structure of 2D materials,and thus significantly modulate their intrinsic properties.In this work,we demonstrated a remarkable strain-modulated magnetic properties in the chemical vapor deposited Cr_(2)Te_(3) nanoflakes grown on mica substrate.We found the Curie temperature of Cr_(2)Te_(3) nanoflakes can be positively and negatively modulated under tensile and compressive strain respectively,with a maximum varied value of -40 and-90 K,dependent on the thickness of samples.Besides,the coercive field of Cr_(2)Te_(3) nanoflakes also showed a significant decrease under the applied strain,suggesting the decrease of exchange interaction or the change of the magnetization direction.This work suggests a promise to employ interfacial strain to accelerate the practical application of room temperature 2D magnetics.

Modulation of the Anisotropic Electronic Properties in ReS_(2) via Ferroelectric Film

Anisotropic response in two-dimensional materials has emerged with attractive potential applications in angle-sensitive areas.However,the challenge with current studies on anisotropic response is due to the main use of the structural materials of pristine to examine the physical properties in different direc-tions,which cause restriction of the anisotropic ratio within a narrow range,thereby,limiting their practical applications.