应对可转移多黏菌素耐药性--饲料添加剂来源的白屈菜红碱具有双重效应

The emergence and spread of the mobile colistin-resistance gene,mcr-1,and its variants pose achallenge to the use of colistin,a last-resort antibiotic used to treat severe infections caused by extensively drug-resistant(XDR)Gram-negative pathogens.Antibiotic adjuvants are a promising strategy to enhance the efficacy of colistin against colistin-resistant pathogens;however,few studies have considered the effects of adjuvants on limiting resistance-gene transmission.We found that chelerythrine(4 mg·L^(-1))derived from Macleaya cordata extract,which is used as an animal feed additive,reduced the minimal inhibitory concentration(MIC)of colistin against an mcr-1 positive Escherichia coli(E.coli)strain by 16-fold(from 2.000 to 0.125 mg·L^(-1)).eliminated approximately 10^(4) colony-forming units(CFUs)of an mcr-1-carrying strain in a murine intestinal infection model,and inhibited the conjugation of an mcr-1-bearing plasmid in vitro(by>100-fold)and in a mouse model(by up to 5-fold).A detailed analysis revealed that chelery-thrine binds to phospholipids on bacterial membranes and increases cytoplasmic membrane fluidity,thereby impairing respiration,disrupting proton motive force(PMF),generating reactive oxygen species(ROS),and decreasing intracellular adenosine triphosphate(ATP)levels,which subsequently downregu-lates mcr-1 and conjugation-associated genes.These dual effects of chelerythrine can expand the use of antibiotic adjuvants and may provide a new strategy for circumventing mobile colistin resistance.

Multi-focus optical fiber lens based on all-dielectric metasurface

A multi-focus optical fiber lens is numerically demonstrated based on an all-dielectric metasurface structure.The metasurface consists of an array of rectangular silicon resonators with varying widths in order to obtain the required phase distribution.The core diameter of the multimode fiber is large enough to contain sufficient resonance units.The spatial distribution of the dielectric resonators is dictated by spatial multiplexing,including interleaving meta-atoms and lens aperture division,to achieve multi-focus properties.The proposed optical fiber metalens can produce two or three focal points along the longitudinal direction with high focusing efficiency.The size of every focal point is close to the diffraction limit,and the relative intensity on each focus can be controlled by adjusting the number of the respective resonators.The proposed optical fiber lens will have a great potential in the fields of integrated optics and multifunctional micro/nano devices.

Simultaneous evaluation of two branches of a multifunctional integrated optic chip with an ultra-simple dual-channel configuration

We propose an ultra-simple dual-channel configuration for simultaneously evaluating two branches of a multifunctional integrated optic chip(MFIOC). In the configuration, the MFIOC is employed as a beam splitter to construct the demodulation interferometer together with a 2 × 2 fiber coupler. Interference happens between polarization modes traveling through different channels of the MFIOC. The cross-couplings of each channel are respectively characterized by the interference peaks which distribute on opposite sides of the central interference peak. Temperature responses of the MFIOC are experimentally measured from-40°C to 80°C. Results show that the proposed configuration can achieve simultaneous dual-channel transient measurements with resolution of-90 d B and dynamic range of 90 d B. In addition, the two channels of the configuration have consistent measuring performance, and the two branches of the MFIOC have different responses to temperature variation.

Characterization of NDM-1-producing carbapenemase in Acinetobacter spp.and E.coli isolates from diseased pigs

In recent years,the mobile metallo-β-lactamase(MBL)genes have been found to correspond to one of the most important resistance characters identified in Gramnegative bacteria,severely affecting clinical chemotherapy and threatening public health.The prevalence of mobile MBL genes and their flanking regions in Gram-negative bacteria from diseased pigs in China was investigated.A total of 334 lung samples from diseased pigs were screened for Gram-negative bacteria classified as non-susceptible to meropenem(MIC≥4mg·L^(–1)).Six isolates,including three Escherichia coli,two Acinetobacter baumanii and one A.calcoaeticus,exhibitedMBL production and carried the blaNDM-1 gene.S1-PFGE and Southern blot analysis showed that the blaNDM-1 gene was located on the chromosome of one A.baumanii isolate and on plasmids of various sizes in the other five isolates.MIC testing using broth microdilution revealed that all blaNDM-1-carrying isolates and some of their transconjugants exhibited resistance to almost allβ-lactams tested.Whole genome sequencing revealed that the flanking region of the blaNDM-1 gene from all porcine isolates had high levels of similarity with the corresponding regions in human isolates.One porcine E.coli isolate carrying blaNDM-1 was typed as ST48,a common sequence type in human E.coli isolates.These results suggest the possibility of human-tofood animal transfer of blaNDM-1-producing E.coli,highlighting the need for surveillance of carbapenemase producers among bacteria from food animals.In addition,the prudent use of antimicrobial agents to decrease the opportunities for co-selection of carbapenemase genes in food animals is also urgently needed.

Single fiber dual-functionality optical tweezers based on graded-index multimode fiber

We propose and demonstrate single fiber dual-functionality optical tweezers based on a graded-index multimode fiber. By using the multi-angle fiber grinding and polishing technology, we fabricate the multimode fiber tip to be a special tapered shape, contributing to focus the outgoing beam with a large intensity gradient for the first functionality--three-dimensional contactless trapping of a microparticle. By adjusting the radial direction offset between the lead-in single mode fiber and the graded-index multimode fiber, we perform the second functionality--axial shift of the trapped microparticle with respect to the fiber tip without need of moving the fiber probe itself. It is convenient for practical applications, The theoretical and experimental results about the relationship between the radial offset and the equilibrium positions of the microparticle have the good consistency. Tailoring the trap and axial shift of the microparticle based on the graded-index multimode fiber provides convenient avenues for fiber optical tweezers a~）Dlied in practical researches.

The SARS-CoV-2 spike L452R-E484Q variant in the Indian B.1.617 strain showed significant reduction in the neutralization activity of immune sera

To assess the impact of the key non-synonymous amino acid substitutions in the RBD of the spike protein of SARS-CoV-2 variant B.1.617.1(dominant variant identified in the current India outbreak)on the infectivity and neutralization activities of the immune sera,L452R and E484Q(L452R-E484Q variant),pseudotyped virus was constructed(with the D614G background).The impact on binding with the neutralizing antibodies was also assessed with an ELISA assay.Pseudotyped virus carrying a L452R-E484Q variant showed a comparable infectivity compared with D614G.However,there was a significant reduction in the neutralization activity of the immune sera from non-human primates vaccinated with a recombinant receptor binding domain(RBD)protein,convalescent patients,and healthy vaccinees vaccinated with anmRNA vaccine.In addition,there was a reduction in binding of L452R-E484Q-D614G protein to the antibodies of theimmune sera fromvaccinated nonhuman primates.These results highlight the interplay between infectivity and other biologic factors involved in the natural evolution of SARS-CoV-2.Reduced neutralization activities against the L452R-E484Q variant will have an impact on health authority planning and implications for the vaccination strategy/newvaccine development.

In-fiber integrated optics： an emerging photonics integration technology [Invited]

In-fiber integrated optics is an attempt to use silica fiber as a substrate, integrating various optical paths or optical components into a single fiber, to build a functional optical device or component, and to realize a micro optical system, achieving various functions. In-fiber integrated optics is expected to he a new branch of photonics integration. This integration technique enables convenient light beams control and manipulation inside in one fiber. It also provides a research platform with micro and nano scale for interaction between light wave and microfluidic materials. In this review, we briefly summarize the main ideas and key technologies of the in-fiber integrated optics by series integration examples.

Intelligent all-fiber device: storage and logic computing

The typical functions of the optical fiber are communication and sensing. However, the fiber functions need to extend to meet the requirements of the development of artificial intelligence. This paper achieves an all-fiber device with storage and logic computing functions using a single-mode fiber and Ge_(2)Sb_(2)Te_(5)(GST) material.We use the pulse amplitude modulation(the switching energy is about 50 nJ) to switch the GST state for performing the eight-level data storage(3-bit). The all-fiber memory device has the advantages of high optical contrast(about 38%), good reversibility, and high repeatability. We implement the all-optical logic operations(“AND”and “OR”) by using two memory cells in series and parallel. For the first time, we use the single-mode optical fiber to realize storage and computing functions, and this intelligent fiber has tremendous application potential in intelligent optical fiber communication and portends a new paradigm for brain-like computing.

Dual-channel microfluidic sensor based on side-hole fiber with two long-period fiber gratings

We propose and demonstrate a dual-channel microfluidic sensor based on a side-hole fiber(SHF)with two longperiod fiber grating(LPFG)structures.There are two air holes in the SHF,which are natural microfluidic channels.We fabricate two LPFGs(long-period gratings LPG-A and LPG-B)in the SHF with the resonance wavelengths of 1268.7 nm and 1385.8 nm,respectively.Results show that the refractive index sensitivities of LPG-A and LPG-B are?76.0 nm/RIU and?71.1 nm/RIU,respectively.One can measure the refractive index of liquid samples in two channels simultaneously.The proposed dual-channel microfluidic sensor has advantages of good linearity response,fluidic technology compatibility,and easy light input/output coupling and system integration,which helps the sensor to have a potential application in environmental detection and food safety detection.

Laser-induced rotary micromotor with high energy conversion efficiency

Light is a precious resource that nature has given to human beings.Converting green,recyclable light energy into the mechanical energy of a micromotor is undoubtedly an exciting challenge.However,the performance of current light-induced micromotor devices is unsatisfactory,as the light-to-work conversion efficiency is only10-15–10-12.In this paper,we propose and demonstrate a laser-induced rotary micromotor operated byΔα-type photopheresis in pure liquid glycerol,whose energy conversion ratio reaches as high as 10-9,which is 3–6 orders of magnitude higher than that of previous light-induced micromotor devices.In addition,we operate the micromotor neither with a light field carrying angular momentum nor with a rotor with a special rotating symmetrical shape.We just employ an annular-core fiber to configure a conical-shaped light field and select a piece of graphite sheet(with an irregular shape)as the micro-rotor.TheΔα-type photophoretic force introduced by the conicalshaped light field drives the rotation of the graphite sheet.We achieve a rotation rate up to 818.2 r/min,which can be controlled by tuning the incident laser power.This optical rotary micromotor is available for twisting macromolecules or generating vortex and shear force in a medium at the nanoscale.