DOPS/TPT复配阻燃环氧树脂的性能

单一的磷杂菲或三嗪类阻燃剂的阻燃效果有限,为了提高阻燃剂在环氧树脂(EP)中的阻燃效率,将9,10-二氢-9-氧杂-10-磷杂菲-10-硫化物(DOPS)与2,4,6-三苯氧基-1,3,5-三嗪(TPT)复配应用于EP中,通过协同阻燃作用来提高EP的阻燃性能,以期获得优异的阻燃效果。文中将DOPS与TPT进行复配,采用熔融共混法制备了阻燃EP复合材料。通过热重分析、垂直燃烧、极限氧指数、锥形量热和力学性能测试研究了复合阻燃剂DOPS/TPT对阻燃EP复合材料的热稳定性、阻燃性能及力学性能的影响,并采用扫描电镜、热重-红外光谱联用分析了材料的残炭形貌和热解气体,探究了其阻燃机理。结果表明,当阻燃剂的总添加量为9%,DOPS在复合阻燃剂DOPS/TPT中的质量分数为8%时,复合材料EP/DOPS/TPT的LOI值为30.5%,达到UL-94 V-0级,而且其平均热释放速率(av-HRR)、总热释放量(THR)值最低,其阻燃性能、成炭性能和力学性能均优于单独添加DOPS或TPT。从阻燃机理看,2种阻燃剂在气相和凝聚相发挥了协效阻燃作用,弥补了单一阻燃剂的不足,能够进一步提高阻燃效果。

双基阻燃剂DOPS-TEAIC的合成及阻燃环氧树脂的性能

以9,10-二氢-9-氧杂-10-磷杂菲-10-硫化物(DOPS)与三(2-丙烯酰氧乙基)异氰脲酸酯(TEAIC)为原料,合成了一种新型双基阻燃剂三(2-(9,10-二氢-9-氧杂-10-磷杂菲-10-硫化物)-丙酸乙酯基)三嗪三酮(DOPS-TEAIC)。采用傅里叶变换红外光谱、核磁共振和质谱确定其结构,并将其应用于环氧树脂(EP)制备了EP/DOPS-TEAIC。采用热重分析、垂直燃烧、极限氧指数、锥形量热、热重-红外光谱联用和热裂解-气相色谱/质谱联用等手段研究了阻燃剂DOPS-TEAIC对EP的热稳定性、阻燃性能及热降解行为的影响,并深入分析了其阻燃机理。结果表明,阻燃剂DOPS-TEAIC能够提高EP的热稳定性、残炭量和阻燃性能,降低其热释放速率峰值(PHRR)和平均热释放速率(av-HRR)。当DOPS-TEAIC的质量分数为10.0%时,EP/DOPS-TEAIC的LOI值提高至33.4%,达到UL-94 V-0级,其PHRR和av-HRR值比纯EP分别降低了34.2%和22.8%。阻燃剂DOPS-TEAIC主要通过稀释作用和自由基猝灭作用在气相发挥阻燃作用。

PEO coating on Mg-Ag alloy:The incorporation and release of Ag species

In the present study,the distribution of Ag in the coating formed on Mg-Ag alloy by plasma electrolytic oxidation(PEO)and its ionic release kinetics when exposed to a 0.9 wt.%Na Cl solution at 37℃have been investigated.Both metallic Ag and Ag oxide particles with~5 to~40 nm in diameters were observed in the PEO coating.Further,an Ag-enriched layer of~20 nm in thickness at the substrate/coating interface was also observed.The PEO coating on the Mg-Ag alloy not only increases its corrosion resistance with the corrosion current density decreasing by up to 3 orders of magnitude from 8.04×10^(-3)to 4.03×10^(-6)A/cm^(2),but also controls the release of Ag+to the level that is sufficient for anti-infective efficacy without causing cytotoxicity to mammal cells.

Warmer temperature during asexual reproduction induce methylome, transcriptomic, and lasting phenotypic changes in Fragaria vesca ecotypes

Plants must adapt with increasing speed to global warming to maintain their fitness.One rapid adaptation mechanism is epigenetic memory,which may provide organisms sufficient time to adapt to climate change.We studied how the perennial Fragaria vesca adapted to warmer temperatures(28◦C vs.18◦C)over three asexual generations.Differences in flowering time,stolon number,and petiole length were induced by warmer temperature in one or more ecotypes after three asexual generations and persisted in a common garden environment.Induced methylome changes differed between the four ecotypes from Norway,Iceland,Italy,and Spain,but shared methylome responses were also identified.Most differentially methylated regions(DMRs)occurred in the CHG context,and most CHG and CHH DMRs were hypermethylated at the warmer temperature.In eight CHG DMR peaks,a highly similar methylation pattern could be observed between ecotypes.On average,13%of the differentially methylated genes between ecotypes also showed a temperature-induced change in gene expression.We observed ecotype-specific methylation and expression patterns for genes related to gibberellin metabolism,flowering time,and epigenetic mechanisms.Furthermore,we observed a negative correlation with gene expression when repetitive elements were found near(±2 kb)or inside genes.In conclusion,lasting phenotypic changes indicative of an epigenetic memory were induced by warmer temperature and were accompanied by changes in DNA methylation patterns.Both shared methylation patterns and transcriptome differences between F.vesca accessions were observed,indicating that DNA methylation may be involved in both general and ecotype-specific phenotypic variation.

Recent Progress of Two-Dimensional Thermoelectric Materials

Thermoelectric generators have attracted a wide research interest owing to their ability to directly convert heat into electrical power.Moreover,the thermoelectric properties of traditional inorganic and organic materials have been significantly improved over the past few decades.Among these compounds,layered two-dimensional(2D)materials,such as graphene,black phosphorus,transition metal dichalcogenides,IVA–VIA compounds,and MXenes,have generated a large research attention as a group of potentially high-performance thermoelectric materials.Due to their unique electronic,mechanical,thermal,and optoelectronic properties,thermoelectric devices based on such materials can be applied in a variety of applications.Herein,a comprehensive review on the development of 2D materials for thermoelectric applications,as well as theoretical simulations and experimental preparation,is presented.In addition,nanodevice and new applications of 2D thermoelectric materials are also introduced.At last,current challenges are discussed and several prospects in this field are proposed.

Sulfide mineral dissolution microbes: Community structure and function in industrial bioleaching heaps

Heap bioleaching is one of the most clean and economical processes for recovery of low-grade and complex ores, because the sulfide minerals are natural habitats for acidophiles capable of iron-and sulfur-oxidation. The most exciting advances in heap bioleaching are occurring in the field of microbiology, especially with the development of advanced molecular biology approaches. These chemolithotrophic microorganisms living in the acid mine environment fix N_2 and CO_2 and obtain energy for growth from soluble ferrous iron and reduced inorganic sulfur compounds during oxidation of sulfide minerals. The ferric iron as oxidant and sulfuric acid are a result of microbial activity and provide favorable conditions for the dissolution of sulfide minerals. Various microbial consortia were applied successfully in commercial bioleaching heaps around the world, and microbial community and activity were adapted related to the local climatic conditions, ore characteristics and engineering configuration. This review focuses on diversity of bioleaching microbes, their role in heap bioleaching processes, their community structure and function in industrial heaps and the relation to the ore characteristics and the engineering configuration, to give implications for optimizing leaching efficiency of heap bioleaching.

Recent Advances in Strain-Induced Piezoelectric and Piezoresistive Effect-Engineered 2D Semiconductors for Adaptive Electronics and Optoelectronics

The development of two-dimensional(2D)semiconductors has attracted widespread attentions in the scientific community and industry due to their ultra-thin thickness,unique structure,excellent optoelectronic properties and novel physics.The excellent flexibility and outstanding mechanical strength of 2D semiconductors provide opportunities for fabricated strain-sensitive devices and utilized strain tuning their electronic and optic–electric performance.The strain-engineered one-dimensional materials have been well investigated,while there is a long way to go for 2D semiconductors.In this review,starting with the fundamental theories of piezoelectric and piezoresistive effect resulted by strain,following we reviewed the recent simulation works of strain engineering in novel 2D semiconductors,such as Janus 2D and 2D-Xene structures.Moreover,recent advances in experimental observation of strain tuning PL spectra and transport behavior of 2D semiconductors are summarized.Furthermore,the applications of strain-engineered 2D semiconductors in sensors,photodetectors and nanogenerators are also highlighted.At last,we in-depth discussed future research directions of strain-engineered 2D semiconductor and related electronics and optoelectronics device applications.

Boron quantum dots all-optical modulator based on efficient photothermal effect

All-optical devices without external electronic components have drawn extraordinary attentions in all-optical communication.In this work,boron quantum dots(BQDs)were synthesized by a facile liquid-phase exfoliation method.The as-prepared BQDs showed good structural homogeneity and crystallinity,broadband optical absorption as well as excellent photothermal properties.Femtosecond-resolved transient absorption further revealed the short carrier relaxation time of BQDs.Inspired by the outstanding photothermal properties and ultrafast carrier dynamic of BQDs,we fabricated BQDsbased all-optical modulator.The phase shift with a slope efficiency of 0.032π/m W and response time of 0.97 ms can be achieved.The modulator was used in laser resonance cavity to achieve all-optical actively Q-switched laser operation with control repetition rate.This prototypical BQDs-based all-optical modulator shows a great potential to be applied in all-optical information processing and communication.

Thermal Behavior,Sensitivity,Detonation Velocity and Pressure of a Nitrogen-Rich Compound

The nitrogen content of tetrazolo triazines is 68.9%.In this paper,tetrazolotriazines was synthetized.The TG-DSC test indicated its decomposition process in detail.The non-isothermal kinetic parameters were speculated by Kissinger and Ozawa methods.It revealed the mechanism function of thermal decomposition.The impact and friction sensitivity were tested.The detonation pressure and velocity were calculated.It has a wide range of potential applications as a kind of energetic material.

Water‑Dispersible CsPbBr_(3) Perovskite Nanocrystals with Ultra‑Stability and its Application in Electrochemical CO_(2) Reduction

Thanks to the excellent optoelectronic properties,lead halide perovskites(LHPs)have been widely employed in highperformance optoelectronic devices such as solar cells and lightemitting diodes.However,overcoming their poor stability against water has been one of the biggest challenges for most applications.Herein,we report a novel hot-injection method in a Pb-poor environment combined with a well-designed purification process to synthesize water-dispersible CsPbBr_(3) nanocrystals(NCs).The as-prepared NCs sustain their superior photoluminescence(91%quantum yield in water)for more than 200 days in an aqueous environment,which is attributed to a passivation effect induced by excess CsBr salts.Thanks to the ultra-stability of these LHP NCs,for the first time,we report a new application of LHP NCs,in which they are applied to electrocatalysis of CO_(2) reduction reaction.Noticeably,they show significant electrocatalytic activity(faradaic yield:32%for CH4,40%for CO)and operation stability(>350 h).

Effects of Different NH_4^+/NO_3^- Ratio and Water Condition on Physiological Characteristics of Rice Seedlings

[Objective] This study aimed to further explore the dynamics of related physiological indexes of rice seedlings under different NH4＋ /NO3- ratio and different water condition. [Method] Under the hydroponic condition in laboratory, 3 NH4＋/NO3- ratios （0/100, 50/50 and 100/0） and 2 water conditions （＋PEG,-PEG） were designed for Fengliangyou 7203. [Result] The root-canopy ratio of rice seedlings increased under any of the NH4＋/NO3- ratios and water conditions. Under water stress, the root-canopy ratio of rice seedlings changed most greatly at the NH4＋/NO3- ratio of 0/ 100; the overall water potential of rice seedlings reached the lowest at the NH4＋/ NO3- ratio of 100/0; and the changes of water potential and xylem flow pH were relatively stable at the NH4＋/NO3- ratio of 50/50. Under the condition of no water stress, the growth of rice seedlings was best at the NH4＋/NO3- ratio of 50/50, followed by the NH4＋/NO3- ratios of 0/100 and 100/0. [Conclusion] This study will pro- vide a basis for understanding the relationship between water potential and xylem flow.

Effects of Comprehensive Control Technology on Heavy Metal Content and Rice Yield in Northern Guangdong Province

In order to explore the application effect of the comprehensive control technology of"soil conditioning-organic planting-foliar control"in the rice area of northern Guangdong,the effects of combined application of different dosages of soil conditioner,bio-organic fertilizer and foliar control agent on heavy metal contents and yields of early and late rice were investigated based on field experiments.The results showed that different treatments of early rice and late rice all increased the yield.The yield increase rates of treatments 2,3 and 4 reached 4.9%,7.2%and 8.7%in early rice,respectively,and those in late rice reached 7.7%,7.8%and 9.7%,respectively.And the cadmium contents of early rice and late rice in treatments 2,3 and 4 were significantly reduced below the safe value.Taking into account factors such as cost,yield increase rate,and heavy metal compliance rate,the recommended application rate for early and late rice is conventional fertilization+soil conditioner 6000 kg/hm^(2)+bio-organic fertilizer 1800 kg/hm^(2)+foliar control agent 6000 ml/hm^(2).

Effects of Nutrients on Growth and Yield of Shatian Pomelo Trees with Huanglongbing

[Objectives]In order to effectively alleviate Huanglongbing of Shatian pomelo trees,a nutrient preparation was developed and its effect on the growth and yield of Shatian pomelo was explored.[Methods]A field experiment was carried out with four treatments:control group,nutrient solution group,agent group,and nutrient solution+agent group,and the liquids were infused into the fruit trees through the trunk using a hanging bag.[Results]Through field trials,it was found that the nutrient solution treatment of fruit trees significantly increased the leaf chlorophyll content and nitrogen content,which increased by 17%and 12%compared with the control group,respectively,reaching(70.80±1.57)and(5.53±0.1)mg/kg,respectively;and the combined application of the nutrient solution and powder agents greatly alleviated the symptoms of Huanglongbing in Shatian pomelo plants,and significantly improved the bacterial disease index,photosynthetic intensity and yield,which increased by 152%,158%and 213.53%respectively,reaching(371.00±7.22),(406.67±7.09)and 23.15 kg/hm^2.[Conclusions]The use of the nutrient solution and agents greatly alleviated the symptoms of Huanglongbing of Shatian pomelo plants,and significantly improved the chlorophyll content,nitrogen content,bacterial disease index and photosynthetic intensity.Meanwhile,the number of fruit per plant and the weight of single fruit were better than other treatment groups and the control group,the technical operation was simple and the effect was obvious.This provides a certain reference basis for the prevention and control measures of Huanglongbing in Shatian pomelo plants.

Study on the Passivation Effect of Ca-Si Soil Conditioner on Heavy Metal Absorption by Rice

[Objectives] In order to solve the problem of heavy metal pollution in paddy fields,field experiments were carried out to study the effect of Ca-Si soil conditioner on heavy metal remediation in paddy fields. [Methods] A conventional planting mode( CK) was used as the control,and a Ca-Si soil conditioner( Ca-Si) treatment was set to analyze the differences in soil pH and heavy metal contents in different treatments. [Results]The content of cadmium in the paddy field exceeded the soil pollution risk control value of agricultural land by 59. 33%. The Ca-Si soil conditioner increased the pH value of paddy field soil by 0. 58 unit. The fixation rates of Ca-Si soil conditioner on chromium,arsenic,cadmium and plumbum reached 75. 96%,14. 09%,18. 93% and 7. 81% compared with the CK,respectively,and the available cadmium and lead contents were reduced by 82. 35% and 80. 00%,respectively. [Conclusions]This study provides ideas and references for the remediation of heavy metal pollution in paddy soil.

Study on Formula Optimization of Huangjing Zhima Pills

[Objectives]With Polygonati Rhizoma steamed and sundried for 9 times as the main raw material, a type of Huangjing Zhima Pills was developed and its optimal formula was studied. [Methods] The Huangjing Zhima Pills was developed with nine-steamed nine-sundried Polygonati Rhizoma as the main raw material by adding black sesame, black beans, and honey. Taking sensory score and texture properties as evaluation indexes, the optimal formula parameters of Huangjing Zhima Pills were determined by single factor experiments and an orthogonal test combined with a formula scoring method. [Results] The best formula of Huangjing Zhima Pills was addition amount of nine-steamed nine-sundried Polygonati Rhizoma 25%, addition amount of black bean powder 15%, addition amount of honey added 17%, and addition amount of black sesame powder 30%. The moisture content in the finished product was(13.367±0.056) g/100 g, and the total colony count, Escherichia coli, mold and yeast and other microbial indexes all met the standards. The Huangjing Zhima Pills prepared under these conditions had pleasant sesame flavor and Polygonati Rhizoma flavor, delicate and sweet tasted, and a slight aftertaste of sweetness. Meanwhile, Polygonatum, black sesame and black beans are all medicinal and food homologous plants with certain health care effects, and the Huangjing Zhima Pills prepared from them are healthy snacks that people can carry and eat easily. [Conclusions] This study further enhances the added value of Polygonatum and provides a new way for the high-value utilization of Polygonatum.

Diagnosis on the Problem of the Human Resources Management of State-owned Enterprises

With the reform of the state-owned enterprises, the level of the human resources management of a lot of state-owned enterprises has been gradually improved. However, because of the macroscopic system, history, culture and their own reasons, there are still a series of problems in the human resources management of state-owned enterprises. In order to promote the reform of state-owned enterprises and to improve the competitiveness of enterprises, we should critically research these urgent problems. The paper will take an example of one company which was investigated by state-owned enterprises will be listed and analysed. the author, and the common problems which exist in most state-owned enterprises will be listed and analysed.

Effect of Mn Addition and Heat Treatment on the Corrosion Behaviour of Mg-Ag-Mn Alloy

The high corrosion sensitivity and the potential bio-toxicity of Mg-Ag alloys limit their wide applications for the production of implanted devices. In the present work, Mn is added into the Mg-Ag alloy to optimize its corrosion behaviour. The corrosion behaviour of Mg-Ag-Mn alloys is investigated with the underlying microstructural factors examined. The Mg-Ag alloy with 2 wt% Mn exhibits the highest corrosion resistance after post-casting heat treatment at 440 ℃. The addition of Mn results in α-Mn phase with the incorporation of Fe, which suppresses the cathodic activity of impurity Fe. Further, heat treatment of the cast alloys homogenizes the distribution of Ag and promotes the precipitation of α-Mn phase. The former removes Ag segregations as potential cathodes;the latter promotes a more uniform distribution of cathodes and, therefore, prevents localized corrosion.

Reconfigurable memristor based on SrTiO_(3) thin-film for neuromorphic computing

Neuromorphic computing aims to achieve artificial intelligence by mimicking the mechanisms of biological neurons and synapses that make up the human brain.However,the possibility of using one reconfigurable memristor as both artificial neuron and synapse still requires intensive research in detail.In this work,Ag/SrTiO_(3)(STO)/Pt memristor with low operating voltage is manufactured and reconfigurable as both neuron and synapse for neuromorphic computing chip.By modulating the compliance current,two types of resistance switching,volatile and nonvolatile,can be obtained in amorphous STO thin film.This is attributed to the manipulation of the Ag conductive filament.Furthermore,through regulating electrical pulses and designing bionic circuits,the neuronal functions of leaky integrate and fire,as well as synaptic biomimicry with spike-timing-dependent plasticity and paired-pulse facilitation neural regulation,are successfully realized.This study shows that the reconfigurable devices based on STO thin film are promising for the application of neuromorphic computing systems.

Recent biotechnological advances and future prospective of Bacillus licheniformis as microbial cell factories

Bacillus licheniformis is a characteristic Gram-positive bacterium originally found in soil.This microorganism has long been utilised as a workhorse for production of industrial enzymes or high value-added chemicals.With ever-increasing understand-ing on this strain and the maturation of the genetic technique,important advances have recently been made in developing B.licheniformis as an excellent chassis cell for synthetic biology.Here,we provide an overview of updated understanding on genome information,anaerobic metabolism,industrial applications of this strain.The state-of-art B.licheniformis genetics,especially its synthetic biology advances in biosensor,expression system and artificial metabolic pathways are illustrated.Finally,perspectives are offered for the limitations and challenges to be addressed to improve B.licheniformis as microbial cell factories.

Mental health, health-related quality of life, and lung function after hospital discharge in healthcare workers with severe COVID-19: a cohort study from China

Coronavirus disease 2019(COVID-19)is an acute respiratory infectious disease caused by severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)infection.It is highly contagious and can cause death in severe cases.As reported by the World Health Organization(WHO),as of 6:36 pm Central European Summer Time(CEST),12 August 2022,there had been 585950285 confirmed cases of COVID-19,including 6425422 deaths(WHO,2022).According to previous studies,healthcare workers(HCWs)have a higher risk of developing COVID-19 compared with the general community,and the severity of COVID-19 is closely related to the health-related effects after discharge(Huang et al.,2021).