Decline in tree-ring growth of Picea mongolica and its intra-annual eco-physiological responses to drought and CO_(2) enrichment in semi-arid China

Episodes of drought-induced decline in tree growth and mortality are becoming more frequent as a result of climate warming and enhanced water stress in semi-arid areas.However,the ecophysiological mechanisms under-lying the impact of drought on tree growth remains unre-solved.In this study,earlywood and latewood tree-ring growth,δ^(13)C,andδ^(18)O chronologies of Picea mongolica from 1900 to 2013 were developed to clarify the intra-and inter-annual tree-ring growth responses to increasingly fre-quent droughts.The results indicate that annual basal area increment residuals(BAI_(res)),which removed tree age and size effects,have significantly decreased since 1960.How-ever,the decreasing trend of earlywood BAI_(res) was higher than that of latewood.Climate response analysis suggests that the dominant parameters for earlywood and latewood proxies(BAI_(res),δ^(13)C andδ^(18)O)were drought-related climate variables(Palmer drought severity index,temperature,rela-tive humidity,and vapor pressure deficit).The most signifi-cant period of earlywood and latewood proxies’responses to climate variables were focused on June-July and July-August,respectively.BAI_(res),andδ^(13)C were significantly affected by temperature and moisture conditions,whereasδ^(18)O was slightly affected.Decreasing stomatal conduct-ance due to drought outweighed the influence of increasing CO_(2) on intrinsic water use efficiency(iWUE),and ultimately led to a decline in BAI_(res).Compared to latewood,the faster decreasing BAI_(res) and smaller increasing iWUE of early-wood suggested trees were more vulnerable to water stress in the early growing season.Our study provides insights into the inter-and intra-annual mechanisms of tree-ring growth in semi-arid regions under rising CO_(2) and climate change.

Analysis of Occurrence and Mixed Infection of Sugarcane Bacilliform Virus Disease in Hainan Sugarcane-growing Area

[Objectives]The paper was to explore the occurrence and mixed infection of sugarcane bacilliform virus disease in Hainan sugarcane-growing area.[Methods]A total of 348 sugarcane leaf samples were collected from 7 sugarcane-growing areas in Hainan Province.Molecular detection of sugarcane bacilliform virus(SCBV)was carried out by PCR using specific primers.[Results]SCBV was detected in 244 out of 348 sugarcane samples,with an average detection rate of 70.11%.The highest detection rate was 76.66%in the Danzhou sugarcane-growing area,while the lowest was 57.14%in the Baisha sugarcane-growing area.The SCBV-positive samples were subjected to testing for SCYLV,SCSMV,SrMV,and SCMV,respectively.The results indicated that 106 out of 244 positive samples exhibited a single infection with SCBV,while 138 samples exhibited mixed infections with SCBV and other sugarcane viruses.The proportion of mixed infections among the SCBV-positive samples was as high as 56.56%.Among the various types of mixed infections,two-virus and three-virus mixed infections were the most prevalent.[Conclusions]SCBV has emerged as a significant threat to the secure production of sugarcane in the Hainan sugarcane-growing region.It presents an explosive infection in the Hainan sugarcane-growing region and frequently combines with other sugarcane viruses to infect sugarcane.The findings of this study will provide a theoretical foundation for the prevention and control of sugarcane bacilliform virus disease.

Zr（HPO4）2/浇铸尼龙6复合材料的制备及结晶性能

采用原位聚合法制备磷酸氢锆/浇铸尼龙6(Zr(HPO4)2/MCPA6)复合材料。X射线衍射和差示扫描量热研究表明,当Zr(HPO4)2的质量分数为1.5%时,复合材料的结晶度由纯MCPA6的15.1%增加到22.2%,少量的Zr(HPO4)2对复合材料能起到结晶成核剂的作用,诱导γ(200)晶型的产生;偏光显微镜对复合材料等温结晶的观察进一步验证了上述对复合材料结晶度表征的结果。摆锤冲击试验和热重分析显示,随着Zr(HPO4)2的加入,复合材料的冲击强度和热稳定性有所增加。

蒙脱土改性超支化聚酰胺6纳米复合材料的结晶与流变性能

采用原位聚合法制备超支化聚酰胺6(PA6)/蒙脱土(MMT)纳米复合材料。利用自动黏度仪、傅里叶变换红外光谱仪、热重分析仪、差示扫描量热仪、X射线衍射仪、毛细管流变仪、力学万能试验机等对超支化PA6/蒙脱土纳米复合材料进行表征。研究表明,上述复合材料的剪切黏度与剪切速率流变曲线符合幂律流体的特征,便于成型加工;复合材料晶型(α、γ)在加入MMT后没有发生变化,结晶度由纯超支化PA6的36.49%降低至33.54%;另外,随着MMT加入基体,纳米复合材料的热稳定性、拉伸强度、断裂伸长率和冲击强度显著增加。

Isolation,Screening and Identification of Antagonistic Actinomycetes against Ustilago scitaminea Syd

[Objectives] This study was conducted to obtain actinomycetes strains having antagonistic effect on Ustilago scitaminea Syd.[Methods] At first, actinomycetes strains were isolated from 22 soil samples in Hainan sugarcane regions. Then, antagonistic actinomycetes against U. scitaminea were screened by confrontation culture. Finally, the taxonomic status of antagonistic actinomycetes was determined using 16S rDNA.[Results] From the 22 samples, 984 actinomycetes strains were isolated. From all the isolated strains, 23 antagonistic actinomycetes strains were obtained through primary screening, and one strains with better antagonistic effect was then obtained through secondary screening, and designated FAS. 16S rDNA identification showed that strain FAS shared 99% sequence similarity with Streptomyces cealestis US24. A phylogenetic tree was built with MAGE 7.0 software, and the results showed that strain FAS had the shortest genetic distance with S. caelestis US24. Therefore, the actinomycetes FAS was determined as S. caelestis .[Conclusions] This study provides a new biocontrol method for the biological control of sugarcane smut, thereby ensuring sustainable development of sugarcane industry and sugar industry.

Spatiotemporal variability in tree ring's δ^(13)C of Picea crassifolia in the Qilian Mountains:climatic significance and responses to rising CO_2

Abstract：The carbon isotopic composition （δ13C） of tree rings was used to assess changes in intrinsic water-use efficiency （Wi） to increasing atmospheric CO2 and climate change during the period of 1891–2003. Five Qinghai spruce （Picea crassifolia） stands were selected in the Qilian Mountains, growing along a precipitation gradient. All five δ13C were correlated to each other, but two sites （DDS and CLS）, which are far from the main body of the mountains, show relative weak connections to other sites. Although trees at all sites had improved their Wi in response to increasing atmospheric CO2 concentration, spruce growing in the regions far away from the main body of the mountains were less sensitive to improved Wi than those of other sites. Based on the correlation between carbon isotope discrimination （Δ） and Palmer Drought Severity Index （PDSI）, the drought history covering the period of 1891–2003 was reconstructed in the study region. The two most severe drought epochs of the late 1920s and the last decade were caused by reduced precipitation and climate warming, respectively. Our results will be useful in assessing any further spatial climate-related bioclimatic information.

Optimization of Streptomyces caelestis Culture Conditions and Preliminarily Determination of Its Antifungal Components

Streptomyces caelestis FAS is an actinomyces strain isolated with Ustilago scitaminea as an indicator. With GAUZE s medium as the basic medium, carbon source and nitrogen source in the medium and ventilation volume were optimized, and the antifungal substances produced by S. caelestis FAS were preliminarily determined through organic solvent extraction and ammonium sulfate precipitation. The results showed that the antifungal components produced by S. caelestis FAS were proteins, and the optimal culture conditions were using corn flour as carbon source and KNO 3 as nitrogen source and culturing in 250 ml triangular flask added with 70 ml of culture medium. The crude protein obtained under these culture conditions had the best antifungal effect with an inhibition zone diameter of 25 mm. This study will provide a scientific basis for further study on the antifungal mechanism and application of S. caelestis FAS.

Study on Wide Antifungal Property of Bacillus subtilis HAS

Bacillus subtilis HAS is a biocontrol strain with better inhibitory effect on Sporisorium scitaminea Sydow. In order to further understand its action range,with fungal pathogens in sugarcane production as targets,confrontation tests and tests of inhibitory effect of secondary metabolites on growth of pathogens were carried out. The results showed that B. subtilis HAS not only had better inhibitory effect on S. Scitaminea,but also inhibited the growth of various fungal pathogens in sugarcane production. The inhibitory effect was the best on Ceratocystis adiposum,Thielaviopsis paradoxa,Fusarium moniliforme and Colletotrichum fuleatum,which was reflected by the radius of inhibitory zone over 10 mm. The inhibitory rates of the secondary metabolites were about 70%. It indicates that B. subtilis HAS has wide antifungal property,providing reference for further application of this strain.

Relative humidity reconstruction for northwestern China's Altay Mountains using tree-ring δ^(18)O

Relative humidity is an important factor in water and water vapor feedback cycles.In this study,we established a 222-year annual tree-ring δ^(18)O chronology for Siberian larch(Larix sibirica Ldb.)from the Altay Mountains in northwestern China.Climate response analyses revealed that the relative humidity was the primary factor limiting tree-ring δ^(18)O fractionation.Based on our analysis,tree-ring δ^(18)O can be used to reconstruct the July–August relative humidity based on both a reasonable mechanism of tree-ring δ^(18)O fractionation and a statistically significant regression model.We used this model to reconstruct variations in the July–August relative humidity,and the model explained 47.4% of the total variation in the measured relative humidity data from 1961 to 2011.The relative humidity in the study area increased from 1900 to the 1990s and decreased thereafter.Two regime-shift dry periods were detected during the study period(one from 1817 to 1830 and the other from 2004 to 2011).

Trend of declining stroke mortality in China:reasons and analysis

Introduction There is a downward trend of stroke-related mortality in the USA.By reviewing all published articles on stroke mortality in China,we analysed its trend and possible factors that have influenced the trend.Methods Both English and Chinese literatures were searched on the mortality of stroke or cerebrovascular diseases in China.Potential papers related to this topic were identified from PubMed,Medline,Embase,Cochrane Library,Wanfang Database,SINOMED and China National Knowledge Infrastructure databases.Results Comparing the results from the most recent population-based epidemiological survey and databank from the national Center for Disease Control and Prevention,the age-adjusted stroke mortality rate has shown a downward trend among both urban and rural population in the past 30 years in China.Comparing with 30 years ago,the rate of stroke mortality has decreased by more than 31%in urban/suburban population and 11%in rural population.In men,the age-adjusted stroke mortality rate decreased by 18.9%and in women by 24.9%between 1994 and 2013.Factors that may have contributed to the trend of decreased stroke mortality rate include(1)improved healthcare coverage and healthcare environment;(2)improved treatment options and medical technology;(3)support by government to educate the public on stroke and stroke prevention;and(4)improved public knowledge on stroke.Conclusions The age-adjusted stroke mortality rate in China has shown a downward trend among both urban and rural population in the past 30 years.The major influencing factors that helped in reducing stroke mortality in China included improved healthcare coverage,healthcare environment,the updated treatment options and modern medical technology.

High-strength hydrogels:Fabrication,reinforcement mechanisms,and applications

With the continuous appearance and expansion of high-strength hydrogels in emerging fields such as industry,medicine,and green development,the synthesis and application of high-strength hydrogels have developed dramatically and achieved remarkable results from the aspects of raw materials,preparation methods,and reinforcement mechanisms.However,there is still a lack of systematic reviews on high-strength hydrogels.Herein,we first discuss the advantages of natural and synthetic materials,and the characteristics of high-strength hydrogels prepared from different raw materials;we then expound on the influence mechanism of physical interactions or chemical bonds on the strength of the hydrogel from three aspects:physical cross-linking,chemical cross-linking,and dynamic chemical cross-linking;at last,we systematically expound the strengthening strategies,including double network/multi-network,nanocomposite,topology,supramolecular polymerization,and characteristics and strengthening mechanisms of such high-strength hydrogels.In addition,based on the development status of high-strength hydrogels,we combined the application requirements and the existing drawbacks of high-strength hydrogels to propose their possible development directions in the future.

Chinese Stroke Association guidelines for clinical management of cerebrovascular disorders:executive summary and 2019 update of the management of high-risk population

Aim Cerebrovascular disease is the leading cause of death and disability in China,causing a huge burden among patients and their families.Hence,stroke prevention is critical,especially in the high-risk population.Here,we present the evidence-based guideline suitable for the Chinese population.Methods Literature search of PubMed and Cochrane library(from January 1964 to June 2019)was done.After thorough discussion among the writing group members,recommendations were listed and summarised.This guideline was reviewed and discussed by the fellow writing committees of the Chinese Stroke Association’s Stroke.Results This evidence-based guideline was written in three parts:controlling the risk factors of stroke,utilisation of antiplatelet agents and assessing the risks of first-ever stroke.All recommendations were listed along with the recommending classes and levels of evidence.Conclusions This guideline provides recommendations for primary prevention of cerebrovascular disease among high-risk population in China.Controlling related risk factors,appropriately using antiplatelet agents,assessing the risk of developing first-ever stroke should help reduce the rate of cerebrovascular disease in China.

Tranexamic acid for acute intracerebral haemorrhage growth based on imaging assessment (TRAIGE): a multicentre, randomised, placebo- controlled trial

Background Studies show tranexamic acid can reduce the risk of death and early neurological deterioration after intracranial haemorrhage.We aimed to assess whether tranexamic acid reduces haematoma expansion and improves outcome in intracerebral haemorrhage patients susceptible to haemorrhage expansion.Methods We did a prospective,double-blind,randomised,placebo-controlled trial at 10 stroke centres in China.Acute supratentorial intracerebral haemorrhage patients were eligible if they had indication of haemorrhage expansion on admission imaging(eg,spot sign,black hole sign or blend sign),and were treatable within 8 hours of symptom onset.Patients were randomly assigned(1:1)to receive either tranexamic acid or a matching placebo.The primary outcome was intracerebral haematoma growth(>33% relative or>6 mL absolute)at 24 hours.Clinical outcomes were assessed at 90 days.Results Of the 171 included patients,124(72.5%)were male,and the mean age was 55.9±11.6 years.89 patients received tranexamic acid and 82 received placebo.The primary outcome did not differ significantly between the groups:36(40.4%)patients in the tranexamic acid group and 34(41.5%)patients in the placebo group had intracranial haemorrhage growth(OR 0.96,95% CI 0.52 to 1.77,p=0.89).The proportion of death was lower in the tranexamic acid treatment group than placebo group(8.1%vs 10.0%),but there were no significant differences in secondary outcomes including absolute intracranial haemorrhage growth,death and dependency.Conclusions Among patients susceptible to haemorrhage expansion treated within 8 hours of stroke onset,tranexamic acid did not significantly prevent intracerebral haemorrhage growth.Larger studies are needed to assess safety and efficacy of tranexamic acid in intracerebral haemorrhage patients.

Haemostatic therapy in spontaneous intracerebral haemorrhage patients with high-risk of haematoma expansion by CT marker: a systematic review and meta- analysis of randomised trials

Background and purpose Current randomised controlled trials(RCTs)showed an uncertain benefit of haemostatic therapy on preventing haematoma expansion and improving the outcome in patients with intracerebral haemorrhage(ICH).This meta-analysis aims to systematically evaluate the effect of haemostatic agents on the prevention of haemorrhage growth in patients with high-risk spontaneous ICH predicted by CT signs in RCTs.Methods A comprehensive search of PubMed,EMBASE and Cochrane library from 1 January 2005 to 30 June 2021 was conducted.RCTs that compared haemostatic agents with placebo for the treatment of spontaneous patients with ICH with high-risk haemorrhage growth were included.The primary endpoint was haematoma expansion at 24 hours.Other major endpoints of interest included 90-day functional outcome and mortality.Results The meta-analysis included four RCTs that randomised 2666 patients with ICH with high-risk haemorrhage growth.Haemostatic therapy reduced the rate of haematoma expansion at a marginally statistically significant level when compared with placebo(OR 0.84;95% CI 0.70 to 1.00;p=0.051).Subgroup analysis for patients with black hole sign on CT revealed a significant reduction of haematoma expansion with haemostatic therapy(OR 0.61;95% CI 0.39 to 0.94;p=0.03).However,both the primary analysis and subgroup analyses showed that haemostatic therapy could not reduce the rate of poor functional outcome(modified Rankin Scale>3)or death.Conclusions Haemostatic therapy showed a marginally significant benefit in reducing early haematoma expansion in patients with high-risk spontaneous ICH predicted by markers on CT scan.However,no significant improvement in functional outcome or reduction of mortality was observed.

Quantification of SARS-CoV-2 antigen levels in the blood of patients with COVID-19

Dear Editor,Severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)has caused the global outbreak of coronavirus disease 2019(COVID-19).By far,more than 35 million people had been infected by SARS-CoV-2,resulting in more than 1 million deaths globally.It is well recognized that SARSCoV-2 preferentially attacks pulmonary epithelial cells,leading to acute respiratory distress syndrome(ARDS).

Synthesis and luminescence properties of Tb^(3+)/Eu^(3+) co-doped GdAlO_3 phosphors with enhanced red emission

he（Gd0.97-xEuxTb0.03）AIO3（x= 0.005-0.07） phosphors were synthesized by the co-precipitation method,using ammonium bicarbonate as a precipitant.The combined technologies of FT-IR,XRD,FESEM,PLE/PL and photo luminescence decay analysis were used to study the phase evolution,morphologies and luminescent properties.The phosphors with good dispersion exhibit strong vivid red emission located at 617 nm（5 D0-7 F2 transition of Eu3＋） under the optimal excitation wavelength of 275 nm（4 f8-4 f75 d1 transition of Tb3＋,8 S7/2→6IJ transition of Gd3＋）.The presence of Gd3＋ and Tb3＋ excitation bands on the PLE spectra monitoring the Eu3＋ emission directly gives an evidence of Tb3＋ → Eu3＋ and Gd3＋ → Eu3＋ energy transfer,The emission intensity varies with the Eu3＋ amount,and the quenching concentration is ～5 at% which is close to the calculated value.The quenching mechanism is determined to be the exchange reaction between Eu3＋.The temperature-dependent PL analysis indicates that the best（Gd0.92Eu0.05Tb0.03）AlO3 sample possesses good thermally stable properties.All the（Gd0.97-xEuxTb0.03）AIO3 phosphors in this work have similar CIE chromaticity coordinates and color temperatures,which are（0.65 ± 0.02,0.35 ± 0.02） and ～2558 K,respectively.Fluorescence decay analysis shows that the lifetime for～617 nm emission decreases with the content of Eu3＋ and temperature increasing.Owing to the Tb3＋→ Eu3＋ energy transfer,the luminescent properties of the（Gd0.92Eu0.05Tb0.03）AlO3 phosphors are superior to the single Eu3＋ doped sample（Gd0.95Eu0.05）AlO3.As a result,the prepared phosphors may be widely used in solid-state display and light emitting devices.

DNA barcoding reveals commercial fraud related to yak jerky sold in China

Dear Editor, Instances of food mislabeling and adulteration scandals fo- cus public attention on food safety and market fraud. Such scandals force the authorities to enforce stringent regula- tions on food adulteration. The Chinese government and consumers are paying more attention to food resource qual- ity and safety regulation than ever before. The growing food market requires food authenticity at all stages of product processing, while species identification of raw materials is fundamental for food safety. Species substitution causes economical loss to consumers and may negatively affect public sanitation because of possible presence of toxic and parasite-infected species （Galimberti et al., 2013）.

Revealing the interlaminar shear failure behavior of unidirectional laminate under combined compression-shear loads

Due to the coupling effects between stresses in different directions,the mechanical behavior of an ad-vanced composite material under multiaxial loading is extremely complex.In this study,the influence of through-thickness compressive stress on the interlaminar shear performance of a carbon fiber-reinforced composite was experimentally investigated.Hollow cylindrical unidirectional laminate specimens were fabricated to conduct combined compression-shear tests,and the fracture morphologies of the specimens were characterized to reveal their failure behavior.The results indicate that a moderate compression load significantly enhanced the shear properties of the laminate by inhibiting crack propagation and improv-ing the friction effect.The shear strength and modulus of a laminate specimen subjected to combined stresses improved up to a maximum of 76%and 231%,respectively,over those of an equivalent specimen subjected to pure shear.However,as the applied through-thickness load approached the compressive strength of the laminate,the specimen shear capacity began to decline owing to the transition of frac-ture mechanisms.Indeed,the specimens exhibited mixed failure modes corresponding to the different stress states,which were induced by the combined effects of through-thickness compressive and shear stresses.As the applied through-thickness compressive stress increased,the dominant failure mode of the laminate specimen changed from fiber-matrix debonding to fiber shearing and then to fiber break-age,resulting in various shear performances.

Controlling factors of Dengying Formation reservoirs in the central Sichuan paleo-uplift

Macroscopic and microscopic characteristics revealed that the Dengying Formation reservoir in the central Sichuan paleo-uplift belonged to the compound genetic reservoir of the mound-shoal facies and karst.Development of the reservoir was controlled by the mound-shoal facies,and dissolution-enlarged or added pores(vugs)due to superimposed karstification modification were favorable reservoir spaces.The karst of the Dengying Formation in Tongwan stage was the stratabound-weathered crust karst of the early diagenesis stage,the extensive superimposition of mound-shoal facies and regional karstification in the central Sichuan paleo-uplift area was the key to develop the large-scale continuous Dengying Formation reservoirs.Due to differences in the development degree of mound-shoal facies and in the intensity of karst modification,the reservoir development degree varied in different zones in the paleouplift area.The NS-extending zone on the western side of the Gaoshiti-Moxi area was the sweet spot for reservoir development.Effective identification of mound-shoal facies and fine depiction of karst landform was the key for reservoir prediction of the Dengying Formation to discovery the superimposed area of the mound-shoal facies and the karst monadnock-karst steep slope which similar to Moxi-Gaoshiti area.

Constructing supramolecular polymers from phototrigger containing monomer

A new type of photo-induced supramolecular polymer was fabricated by host-guest interaction from a phototrigger containing building block. A dibenzo-24-crown-8 （DB24C8） macrocycle and dibenzylammonium （DBA） site containing linear monomer was designed and synthesized. The coumarin, as a photocleavable protector, was introduced to the terminal of the monomer. When exposed to the UV light, the coumarin unit would be cleavaged and the monomer without terminal coumarin can self-assemble into supramolecular polymers via the host-guest interaction between DB24C8 moieties and DBA units. Increasing the concentration of the monomer, the supramolecular polymers will convert to supramolecular organogel by cross-linking with each other.