母猪饲喂关键营养技术

母猪的生产性能影响整个猪场的效益,营养调控是改善母猪生产性能的重要途径。文章结合国内外母猪营养研究的最新报道,概述了母猪后备期、妊娠期和泌乳期的关键营养技术,为养猪生产中的营养调控提供参考。

Quadrilateral isoparametric finite elements for plane elastic Cosserat bodies

4-node, 8-node and 8（4）-node quadrilateral plane isoparametric elements are used for the solution of boundary value problems in linear isotropic Cosserat elasticity. The patch test is applied to validate the finite elements. Engineering problems of stress concentration around a circular hole in plane strain condition and mechanical behaviors of heterogeneous materials with rigid inclusions and pores are computed to test the accuracy and capability of these three types of finite elements.

Multiplexed Profiling of Extracellular Vesicles for Biomarker Development

Extracellular vesicles(EVs)are cell-derived membranous particles that play a crucial role in molecular trafficking,intercellular transport and the egress of unwanted proteins.They have been implicated in many diseases including cancer and neurodegeneration.EVs are detected in all bodily fluids,and their protein and nucleic acid content offers a means of assessing the status of the cells from which they originated.As such,they provide opportunities in biomarker discovery for diagnosis,prognosis or the stratification of diseases as well as an objective monitoring of therapies.The simultaneous assaying of multiple EV-derived markers will be required for an impactful practical application,and multiplexing platforms have evolved with the potential to achieve this.Herein,we provide a comprehensive overview of the currently available multiplexing platforms for EV analysis,with a primary focus on miniaturized and integrated devices that offer potential step changes in analytical power,throughput and consistency.

Two-dimensional MXene hollow fiber membrane for divalent ions exclusion from water

Two-dimensional material membranes with fast transport channels and versatile chemical functionality are promising for molecular separation.Herein,for the first time,we reported design and engineering of two-dimensional Ti_(3)C_(2)Tx MXene(called transition metal carbides and nitrides)membranes supported on asymmetric polymeric hollow fiber substrate for water desalination.The membrane morphology,physicochemical properties and ions exclusion performance were systematically investigated.The results demonstrated that surface hydrophilicity and electrostatic repulsion and size sieving effect of interlayer channels synergistically endowed the MXene hollow fiber membrane with fast water permeation and efficient rejection of divalent ions during nanofiltration process.

Highly efficient and stable perovskite solar cells with strong hydrophobic barrier via introducing poly(vinylidene fluoride)additive

Perovskite solar cells(PSCs)have become the promising next-generation photovoltaic devices due to their excellent photoelectric performances,and the power conversion efficiencies(PCEs)have experienced unprecedented rapid increase in recent years.However,to realize the practical application of PSCs,high performance and long-term stability are required and the preparation of high-quality perovskite film is the key.Herein,we adopt a simple and effective method to prepare high-quality perovskite films by introducing the poly(vinylidene fluoride)(PVDF)polymer additive with abundant hydrophobic F.As the growth template,the PVDF promotes the growth of perovskite crystal,improves the crystallinity and film morphology,thus reducing defect density and inhibiting carrier recombination.The results show that the photovoltaic performances of the perovskite device with PVDF are meaningfully improved,and a high PCE of 21.42%is achieved with an improvement of 10.87%,More importantly,the PVDF-based perovskites display greatly enhanced humidity and heat stability due to the protection of strong hydrophobic barrier from F and PVDF long chain.Aging at 45%±5%relative humidity(RH)for 2400 h and 850 C for300 h,respectively,the unsealed PVDF devices can maintain over 90%of the initial PCE.It indicates that suitable polymer additives can improve the film quality to acquire high-performance and stable PSCs and lay a foundation to design new perovskite light absorption layer with different polymers for the further development of PSCs.

Advances in FRET-based biosensors from donor-acceptor design to applications

Fluorogenic biosensors are essential tools widely used in biomedicine,chemical biology,environmental protection and food safety.Fluorescence resonance energy transfer(FRET)is a crucial technique for developing fluorogenic biosensors that provide mechanistic insight into bioprocesses through time-spatial bioimaging in living cells and organisms.Although extensive FRET-based sensors have been developed for detecting or imaging analytes of interest over the past decade,few comprehensive reviews have summarized the recent studies from the fundamental chemical angle about the design and application.In this work,the recent advance in the discovery of FRET biosensors using donor-acceptor dye combinations is described and they are classified based on different types of analytes,such as mall molecules,proteins,enzymes,nucleic acids and metal ions.This review provides molecular-level inspiration for the design of FRET-based biosensors,aiding in their application in biosensing and bioimaging.

Special RCA based sensitive point-of-care detection of HPV mRNA for cervical cancer screening

Developing the sensitive point-of-care testing(POCT)of oncogenic nucleic acids from human papillomavirus(HPV)infection is essential in preventing cervical can-cer,especially in resource-limited settings.Rolling circle amplification(RCA)is attractive in achieving POCT via nucleic acid-based aggregation under isothermal conditions.However,the influence of RCA product structure on the aggregation remains unexplored resulting in limited sensitivity.Here,a minimum secondary structured RCA technique(MSS-RCA)is developed by designing a unique circu-lar template,demonstrating significantly enhanced detection sensitivity with only one amplification step and one primer under isothermal conditions.The amplifi-cation efficiency of MSS-RCA could be kinetically manipulated by controlling the secondary structure of the circular template.Introducing the invertase probe to MSS-RCA,HPV16 E6/E7 nucleic acid target was detected with a personal glucose meter(PGM)with a sensitivity of 5 fM(50 zmol in 10µL).This integrated MSS-RCA-PGM detection system was successfully applied to detect HPV16 E6/E7 mRNA extracted from 54 cervical swab samples reaching a positive predictive value of 100.00%and negative predictive values of 96.00%(77.77%to 99.40%,95%CI).MSS-RCA-PGM provides a sensitive POCT platform for the detection of nucleic acid biomarkers for screening of cervical cancer or other diseases.

高配位数金属有机框架膜的通道构筑与应用研究

高渗透性、高选择性和高稳定性的膜材料是提高膜分离过程的核心.高配位数金属有机框架膜具有规整的纳米通道、孔道可调节、稳定性优异等特点,近十年来研究表明,其是一类极具潜力的分子尺度分离膜材料.本文系统综述了高配位数金属有机框架膜的传质通道精密构筑及其在分子尺度分离应用方面的研究进展,并深入探讨了该研究领域所面临的机遇和挑战,同时也对其未来发展方向进行了展望.

Thermoregulatory molecular sieving in crystals

Sub-nanometer channels for the selective recognition of the components in chemical mixtures from others play a crucial role in the adsorption and membrane separation[1].It remains a grand challenge to separate small molecular pairs with minor size/shape difference owing to the undesirable pore structure.

HBsAg Loss with Peg-interferon Alfa-2a in Hepatitis B Patients with Partial Response to Nucleos(t)ide Analog:New Switch Study

Background and Aims:Hepatitis B surface antigen(HBsAg)loss is seldom achieved with nucleos(t)ide analog(NA)therapy in chronic hepatitis B patients but may be enhanced by switching to finite pegylated-interferon(Peg-IFN)alfa-2a.We assessed HBsAg loss with 48-and 96-week Peg-IFN alfa-2a in chronic hepatitis B patients with partial response to a previous NA.Methods:Hepatitis B e antigen(HBeAg)-positive patients who achieved HBeAg loss and hepatitis B virus DNA<200 IU/mL with previous adefovir,lamivudine or entecavir treatment were randomized 1:1 to receive Peg-IFN alfa-2a for 48(n=153)or 96 weeks(n=150).The primary endpoint of this study was HBsAg loss at end of treatment.The ClinicalTrials.gov identifier is NCT01464281.Results:At the end of 48 and 96 weeks'treatment,14.4%(22/153)and 20.7%(31/150)of patients,respectively,who switched from NA to Peg-IFN alfa-2a cleared HBsAg.Rates were similar irrespective of prior NA or baseline HBeAg seroconversion.Among those who cleared HBsAg by the end of 48 and 96 weeks'treatment,77.8%(14/18)and 71.4%(20/28),respectively,sustained HBsAg loss for a further 48 weeks.Baseline HBsAg<1500 IU/mL and week 24 HBsAg<200 IU/mL were associated with the highest rates of HBsAg loss at the end of both 48-and 96-week treatment(51.4%and 58.7%,respectively).Importantly,extending treatment from 48 to 96 weeks enabled 48.3%(14/29)more patients to achieve HBsAg loss.Conclusions:Patients on long-term NA who are unlikely to meet therapeutic goals can achieve high rates of HBsAg loss by switching to Peg-IFN alfa-2a.HBsAg loss rates may be improved for some patients by extending treatment from 48 to 96 weeks,although the differences in our study cohort were not statistically significant.Baseline and on-treatment HBsAg may predict HBsAg loss with Peg-IFN alfa-2a.

New-type highly stable 2D/3D perovskite materials:the effect of introducing ammonium cation on performance of perovskite solar cells

Perovskite solar cells(PSCs) have drawn wide attention due to the rapidly rising efficiency which presently attains over 23%. However, problems of instability continue to plague the high-efficiency devices impairing their practical applications. Here, by firstly introducing smaller-size NH4+ into(FAPbI3)0.85(MAPbBr3)0.15(FA/MA) to form a novel 2D-3D mixed structure, we designed and prepared new-type hybrid perovskite materials of [(NH4)2.4(FA)n-1PbnI3n+1.4]0.85(MAPbBr3)0.15(n=3, 5, 7, 9 and 11)(A/FA/MA) and used them as absorber in solar cells. Especially, unlike the reported 2D/MD perovskite perovskites based on larger-size ammonium salts;A/FA/MA perovskites are the first to display red-shift light absorption and decreased band gaps in comparison to normal perovskites. Consequently, when n=9, the A/FA/MA device shows outstanding performance with a solar to electric power conversion efficiency(PCE) of 18.25% and negligible hysteresis. When the encapsulated A/FA/MA perovskite device was soaked in full sunlight for 1,000 h, the PCE remains almost unchanged. Moreover, the unsealed A/FA/MA PSCs maintain 90% of their initial PCE when aged at high humidity conditions over the same 1000-h time period. Our findings provide a guide for the future development of such novel perovskites and it is helpful to select more suitable ammonium salt to obtain highly efficient and stable 2D-3D PSCs.

Incidence and prevalence of moyamoya disease in urban China: a nationwide retrospective cohort study

Background and objective Moyamoya disease(MMD)is an increasingly recognised cause of stroke,mainly described in East Asia.China is the largest nation in Asia,but few studies reported the epidemiology of MMD,especially at a national level.We aimed to estimate the incidence and prevalence of MMD in China.Methods We performed a population-based study using data from the national databases of Urban Basic Medical Insurance between 2013 and 2016,covering approximately 0.50 billion individuals.MMD cases were identified by diagnostic code(International Classification of Diseases,10th Revision I67.5)or related diagnostic text.Results A total of 1987 MMD patients(mean age 44.45±14.30 years,female-to male ratio 1.12)were identified,representing a national crude incidence of 0.59(95%CI:0.49 to 0.68)and a prevalence of 1.01(95%CI:0.81 to 1.21)per 100000 person-years in 2016.Rates were higher in females than in males for the incidence(0.66 vs 0.52)and prevalence(1.05 vs 0.90).And the age-specific rates showed a bimodal distribution,with the highest peak in middle-aged group and the second peak in child group.Conclusions Our results confirm that MMD is relatively common in East Asians,but the rates in China were lower than those in other East Asian countries such as Japan and Korea.The unique epidemiological features,including a relatively weak female predominance and a shift in the highest peak of incidence from children to adults,revealed new sight into MMD.Further research is expected to explore the potential pathogenesis of MMD.

Random lasing of CsPbBr3 perovskite thin films pumped by modulated electron beam

Aiming at the application requirements of information optics,this Letter proposed a perovskite quantum dot random lasing pumping method suitable for high-speed modulation.At the same time,the luminescence characteristics of perovskite quantum dot films under electron beam pumping conditions are analyzed,and the random lasing mechanism of electron beam pumping CsPbBr3 quantum dot films is revealed.Finally,it is confirmed that perovskite quantum dots are easy to realize random lasing under electron beam pumping conditions.

Cation-diffusion controlled formation of thin graphene oxide composite membranes for efficient ethanol dehydration

Structural manipulation of graphene oxide (GO) building blocks has been widely researched. Concerning GO membranes for separation applications, the validity and maintenance of their microscopic structures in the chemical environment are pivotal for effective separation at the molecular scale. Cationic interactions with both aromatic rings and oxygenated functional groups of GO make metal ions intriguing for physically and chemically structural reinforcement. By filtrating GO suspension through the substrate loaded with cations, stacking o f GO nanosheets and diffusion of cations steadily evolve simultaneously in an aqueous environment without flocculation. Thus, thin and homogeneous GO membrane is obtained. Divalent and monovalent cations were studied regarding their interactions with GO, and the performance of correspondingly functionalized membranes was evaluated. The divalent cation-stabilized membranes have favorable stability in the separation of water/ethanol. This facile fabrication and functionalization method may also be applicable for structure construction of other two-dimensional materials.

On-chip structure-switching aptamer-modified magnetic nanobeads for the continuous monitoring of interferon-gamma ex vivo

Cytokines are cell signaling molecules that indicate the health status of the body.In this study,we developed a microfluidic device integrated with structure-switching aptamers capable of continuously tracking the concentration of the cytokine interferon gamma(IFN-γ)in cell culture medium and blood serum.First,a ferrocene(Fc)-labeled structure-switching signaling aptamer with a hairpin structure targeting IFN-γwas immobilized on magnetic nanobeads by the strongest noncovalent interactions between streptavidin and biotin.The aptamer-modified magnetic nanobeads were trapped on a customized microfluidic chip by a magnetic field to form the sensing interface.The binding of IFN-γcould trigger the hairpin structure of the aptamer to unfold,pushing Fc redox molecules away from the sensing interface and consequently switching off the electrochemical signal.The change in the redox current of Fc was quantitatively related to the concentration of IFN-γin a linear range of 10–500 pg mL^(−1)and with the lowest detection limit of 6 pgmL^(−1).This microfluidic device was specific to IFN-γin the presence of overabundant serum proteins and allowed the continuous monitoring of IFN-γwithout adding exogenous reagents.It provided a universal point-of-care biosensing platform for the real-time detection of a spectrum of analytes.

Electrochemical micro-aptasensors for exosome detection based on hybridization chain reaction amplification

Exosomes are cell-derived nanovesicles that have recently gained popularity as potential biomarkers in liquid biopsies due to the large amounts of molecular cargo they carry,such as nucleic acids and proteins.However,most existing exosome-based analytical sensing methods struggle to achieve high sensitivity and high selectivity simultaneously.In this work,we present an electrochemical micro-aptasensor for the highly sensitive detection of exosomes by integrating a micropatterned electrochemical aptasensor and a hybridization chain reaction(HCR)signal amplification method.Specifically,exosomes are enriched on CD63 aptamer-functionalized electrodes and then recognized by HCR products with avidin-horseradish peroxidase(HRP)attached using EpCAM aptamers as bridges.Subsequently,the current signal that is generated through the enzyme reaction between the HRP enzyme and 3,3,,5/5,-tetramethylbenzidine(TMB)/H_(2)0_(2) directly correlates to the amount of bound HRP on the HCR products and thus to the number of target exosomes.By introducing anti-EpCAM aptamers,micro-aptasensors can detect cancerous exosomes with high specificity.Due to the micropatterned electrodes and HCR dual-amplification strategy,the micro-aptasensors achieve a linear detection response for a wide range of exosome concentrations from 2.5×10^(3) to 1×10^(7) exosomes/mL,with a detection limit of 5×10^(2) exosomes/mL.Moreover,our method successfully detects lung cancer exosomes in serum samples of early-stage and late-stage lung cancer patients,showcasing the great potential for early cancer diagnosis.

Transcriptional Characteristics of Xa21-mediated Defense Responses in Rice

Bacterial blight,caused by Xanthomonas oryzae pv.oryzae（Xoo）,is the most destructive bacterial disease of rice.The cloned rice gene Xa21 confers resistance to a broad spectrum of Xoo races.To identify genes involved in Xa21-mediated immunity,a whole-genome oligonucleotide microarray of rice was used to profile the expression of rice genes between incompatible interactions and mock treatments at 0,4,8,24,72 and 120 h post inoculation（hpi） or between incompatible and compatible interactions at 4 hpi,respectively.A total of 441 differentially expressed genes,designated as XDGs（Xa21 mediated differentially expressed genes）,were identified.Based on their functional annotations,the XDGs were assigned to 14 categories,including defense-related,signaling,transcriptional regulators.Most of the defense-related genes belonged to the pathogenesis-related gene family,which was induced dramatically at 72 and 120 hpi.Interestingly,most signaling and transcriptional regulator genes were downregulated at 4 and 8 hpi,suggesting that negative regulation of cellular signaling may play a role in the Xa21-mediated defense response.Comparison of expression profiles between Xa21- and other R gene-mediated defense systems revealed interesting common responses.Representative XDGs with supporting evidences were also discussed.

Improved electrical and magnetic transport properties of La(0.8)Ba(0.2)MnO3 thin films by oxygen annealing

Dear Editors, The properties of mixed-valence manganites are sensmve to the synthesis conditions [ 1 ]. For oxide films grown by pulsed laser deposition （PLD）, the physical properties are affected obviously by the growth oxygen pressure and annealing treat- ment [2-5]. Using the PLD method, manganite oxides are usually grown at different oxygen pressures to investigate the effects of oxygen content on their properties. However,

Protein microarray:A key approach of proteomics

Proteins are vital parts of living organisms,for they consist of the main components of physiological metabolic pathways.The expression and modification status of proteins in cells are time-and space-dependent based upon functions as well as responses to stress.A subject aiming at understanding of protein status under certain physiological condition in a large scale,termed proteomics,is fundamentally important in life science.Although the proteomic investigation mainly relies on electrophoresis,liquid chromatography,and mass spectrometry,protein microarray is emerging as one of new techniques,and its power is being recognized in the field recently.Herein,we highlight progress in protein microarray,both its generation and application.

Application of facile solution-processed ternary sulfide Ag_8SnS_6 as light absorber in thin film solar cells

Light absorber is critical to the further applications of thin film solar cells. Here, we report a facile solution-processed method with an annealing temperature below250°C to fabricate Ag8 SnS6(ATS) light absorber for thin film solar cells. After optimization, the ATS-based thin film solar cells exhibited a reproducible power conversion efficiency(PCE) of about 0.25% and an outstanding long-term stability with 90% of the initial PCE retained after a more than 1,000 h degradation test. This research revealed the potential application of ATS as an earth-abundant, low toxic and chemically stable light absorber in thin film solar cells.