Pt-Re/rGO bimetallic catalyst for highly selective hydrogenation of cinnamaldehyde to cinnamylalcohol

In the present work, a series of Pt-based catalysts, alloyed with a second metal, i.e., Re, Sn, Er, La, and Y, and supported on activated carbon, ordered mesoporous carbon, N-doped mesoporous carbon or reduced graphene oxide(rGO), have been developed for selective hydrogenation of cinnamaldehyde to cinnamylalcohol. Re and rGO were proved to be the most favorable metal dopant and catalyst support, respectively. Pt_(50) Re_(50)/rGO showed the highest cinnamylalcohol selectivity of 89% with 94% conversion of cinnamaldehyde at the reaction conditions of 120 °C, 2.0 MPaH_2 and 4 h.

Elaborate Forecast about Fire Risk Grade in Forest and Grassland of Inner Mongolia Based on Intelligent Grid

Based on the fire and meteorological data of forest and grassland in Inner Mongolia in recent 30 years,a forest and grassland fire risk grade forecast model is established,and a refined forest and grassland fire risk level forecast system based on smart grid is developed. The results show that predictors are determined about forest and grassland fire risk grade,such as precipitation,minimum relative humidity,maximum temperature,maximum wind speed,number of sunny or rainy days,and forest and grassland combustible stock. According to fire risk division conclusion,forest and grassland areas are divided into 5 forecast areas. By using discriminant analysis and weighted factor overlay method,an elaborate fire risk grade forecast model is established in different forecast areas of Inner Mongolia forest and grassland. By using smart grid forecast field data,an elaborate fire risk grade forecasting system is established for making fire risk grade forecast during 24,48 and 72 h.

Application Analysis of Energy Saving Measures in Oilfield Electrical Engineering

With the rapid development of the social economy,people are paying more and more attention to environmental issues.If society wants sustainable development,it must put energy conservation and emission reduction on the agenda.At this stage,China has vigorously promoted energy conservation and emission reduction,and all walks of life have gradually embarked on the green road of energy conservation.In recent years,energy saving measures has been widely used in China's oilfield electrical engineering.The author explores and analyzes the basic principles of energy saving measures applied in oilfield electrical engineering,and proposes an effective way to apply energy saving measures in oilfield electrical engineering,hoping to contribute to the energy saving effect of oilfield electrical engineering.

Insight to the enhanced microwave absorption of porous N-doped carbon driven by ZIF-8:Competition between graphitization and porosity

Porous carbon-based materials are promised to be lightweight dielectric microwave absorbents.Deeply understanding the influence of graphitization grade and porous structure on the dielectric parameters is urgently required.Herein,utilizing the low boiling point of Zn,porous N-doped carbon was fabricated by carbonization of ZIF-8(Zn)at different temperature,and the microwave absorption performance was investigated.The porous N-doped carbon inherits the high porosity of ZIF-8 precursor.By increasing the carbonization temperature,the contents of Zn and N elements are decreased;the graphitization degree is improved;however,the specific surface area and porosity are increased first and then decreased.When the carbonization temperature is 1000°C,the porous N-doped carbon behaves enhanced microwave absorption.With an ultrathin thickness of 1.29 mm,the ideal RL reaches-50.57 dB at 16.95 GHz and the effective absorption bandwidth is 4.17 GHz.The mechanism of boosted microwave absorption is ascribed to the competition of graphitization and porosity as well as N dopants,resulting in high dielectric loss capacity and good impedance matching.The porous structure can prolong the pathways and raise the contact opportunity between microwaves and porous carbon,causing multiple scattering,interface polarization,and improved impedance matching.Besides,the N dopants can induce electron polarization and defect polarization.These results give a new insight to construct lightweight carbon-based microwave absorbents by regulating the graphitization and porosity.

Origins,timing and introgression of domestic geese revealed by whole genome data

Background Geese are among the most important poultry species in the world.The current generally accepted hypothesis is that the European domestic geese originated from greylag geese(Anser anser),and Chinese domestic geese have two origins,most of which originated from swan geese(Anser cygnoides),and the Yili goose originated from greylag geese.To explain the origin and demographic history of geese,we selected 14 goose breeds from Europe and China and wild populations of swan and greylag geese,and whole genome sequencing data were obtained for 74 samples.Results Population structure analysis and phylogenetic trees showed that the wild ancestor of Chinese domestic geese,except for Yili,is the swan geese,and the wild ancestor of Chinese Yili and European domestic geese is greylag geese.Analysis of the demographic history suggests that the domestication of Chinese geese occurred~3499 years ago and that of the European geese occurred~7552 years ago.Furthermore,gene flow was observed between domestic geese and their wild ancestors.Analysis of introgression showed that Yili geese had been introgressed by Chinese domestic geese,and the body size of Yili geese may be influenced by introgression events of some growthrelated genes,including IGF-1.Conclusions Our study provides evidence for the origin of geese at the genome-wide level and advances the understanding of the history of goose domestication and the traits affected by introgression events.

Hetero-Janus Nanofibers as an Ideal Framework for Promoting Water-pollutant Photoreforming Hydrogen Evolution

Photoreforming hydrogen evolution(Pr-HE)of a water-pollutant system could simultaneously achieve efficient hydrogen production and pollutant degradation.It provides a new way to solve energy and environmental issues,but the poor internal charge separation still limits its performance.This work designed hetero-Janus nanofibers(HJNFs)with ordered electric field distribution and separated redox surfaces to promote Pr-HE of the water-pollutant system.Taking ZnO/NiO heterojunction as an example,the hetero-Janus structures were prepared via"Dual-channel"electrospinning and further confirmed by the element morphology analysis and asymmetric distribution of the XPS spectra.The theoretical simulation showed that Janus structures could effectively inhibit the electron trap and hole trap generation,then accelerate the directional carrier migration to the surface.Experimental investigations also confirmed that Janus structures could effectively suppress internal exciton luminescence and accelerate surface charge transfer.The Pr-HE amount and the corresponding propranolol(PRO)degradation rate of HJNFs were 7.9 and 1.5 times higher than hetero-mixed nanofibers(HMNFs).The enhancement factor of Pr-HE in water-PRO to pure water was about 3.1,but nearly zero for HMNFs.This prominent synergistic effect was due to the enhancement of charge separation and the inhibition of cascade side reaction from hetero-Janus structures.Furthermore,the synchronous Pr-HE and degradation reactions were significantly promoted by selective introducing Ag nanoparticles in one side of the HJNFs for enlarging the interfacial Fermi energy level difference.The hetero-Janus strategy offers a new perspective on designing efficient photoreforming photocatalysts for energy and environment applications.

基于教学立方和视频直播的在线教学探索

由新型冠状病毒引起的传染性肺炎的疫情导致国内大中小学普遍推迟了2020年春季学期的开学时间。为了落实教育部提出的“停课不停教、停课不停学”的要求,我们提出基于教学立方配合视频直播平台的在线教学方案,并用于有机化学课程的在线教学实践。利用教学立方,学生进行课前预习和课后复习;利用视频直播间作为虚拟教室进行课上教学,并使用教学立方进行互动。该方案不仅可以保证疫情防控期间教学进度和教学质量,基本做到在线学习与线下课堂教学质量实质等效。而且,疫情过后,仍然可以作为在线教学或者线上线下混合教学方案继续使用,为打造“金课”奠定基础。

Mapping QTL for flowering time-related traits under three plant densities in maize

Flowering time is an indicator of adaptation in maize and a key trait for selection in breeding.The genetic basis of flowering time in maize,especially in response to plant density,remains unclear.The objective of this study was to identify maize quantitative trait loci(QTL)associated with flowering time-related traits that are stably expressed under several plant densities and show additive effects that vary with plant density.Three hundred recombinant inbred lines(RIL)derived from a cross between Ye 478 and Qi 319,together with their parents,were planted at three plant densities(90,000,120,000,and 150,000 plants ha^(-1))in four environments.The five traits investigated were days to tasseling(DTT),days to silking(DTS),days to pollen shed(DTP),interval between anthesis and silking(ASI),and interval between tasseling and anthesis(TAI).A high-resolution bin map was used for QTL mapping.In the RIL population,the DTT,DTS,and DTP values increased with plant density,whereas the ASI and TAI values showed negligible response to plant density.A total of 72 QTL were identified for flowering time-related traits,including 15 stably expressed across environments.Maize flowering time under different densities seems to be regulated by complex pathways rather than by several major genes or an independent pathway.The effects of some stable QTL,especially qDTT8-1 and qDTT10-4,varied with plant density.Fine mapping and cloning of these QTL will shed light on the mechanism of flowering time and assist in breeding earlymaturing maize inbred lines and hybrids.

Quantitative Study on the Grade of Forest Combustibles Based on "3S" Technology

Based on a comprehensive and systematic analysis of the temporal and spatial distribution,periodic changes,and influencing factors of forest fires in Inner Mongolia,through fixed-point observations and experiments on the ground,forest combustibles are divided into the ground litter layer,ground standing litter,and living plants.The combustibles are divided into various grades according to their load,dryness and combustibility.By determining the influencing factors of each combustible grade,a forecast model of the combustibility grade of combustibles is established.The forecast model has been widely used in the mid-and long-term forecast model of fire danger grade,and the accuracy rate of the fall area forecast through back-generation fitting verification is above 88.43%.

Credible Routing Scheme of SDN-Based Cloud Using Blockchain

Software-defined networks (SDN) have been widely used in Cloud Data Centers in recent years. With the development of cloud technologies, different organizations need to share network resources to achieve common business goals, which requires distributed SDN controllers to collaboratively manage cloud networks and realize cross-domain routing. However, existing distributed controller cooperative routing schemes require a third-party trust center to establish trusted relationships for controllers. Since both trust centers and certified entities are vulnerable to various attacks and security risks, the existing works cannot effectively ensure cross-domain routing is credible. To address this problem, Blockchain is employed to establish trusted relationships between distributed controllers, then a cross-domain routing mechanism was devised based on the trusted relationships. Security analysis and experiments indicate that the proposed scheme can establish trust relationships and provide credible cross-domain routing cooperation for distributed SDN controllers. Besides, the required overhead of storage and bandwidth are very limited, which implies good practicability.

Provable secure authentication key agreement for wireless body area networks

Wireless body area networks(WBANs)guarantee timely data processing and secure information preservation within the range of the wireless access network,which is in urgent need of a new type of security technology.However,with the speedy development of hardware,the existing security schemes can no longer meet the new requirements of anonymity and lightweight.New solutions that do not require complex calculations,such as certificateless cryptography,attract great attention from researchers.To resolve these difficulties,Wang et al.designed a new authentication architecture for the WBANs environment,which was claimed to be secure and efficient.However,in this paper,we will show that this scheme is prone to ephemeral key leakage attacks.Further,based on this authentication scheme,an anonymous certificateless scheme is proposed for lightweight devices.Meanwhile,user anonymity is fully protected.The proposed scheme is proved to be secure under a specific security model.In addition,we assess the security attributes our scheme meets through BAN logic and Scyther tool.The comparisons of time consumption and communication cost are given at the end of the paper,to demonstrate that our scheme performs prior to several previous schemes.

An efficient and authenticated key establishment scheme based on fog computing for healthcare system

Because of its closeness to users,fog computing responds faster than cloud computing.Thus,it has been deployed to various applications,such as healthcare system.Recently,to ensure the secure communication of the fog-based healthcare system,Jia et al.proposed an authenticated key agreement scheme.Moreover,in view of the high computation cost existing in Jia et al.’s scheme,Ma et al.presented an efficient one using elliptic curve cryptography.In this paper,we observe that both the two schemes may potentially risk ephemeral key compromise attacks and need improving.Therefore,to overcome this potential risk,we propose a new authenticated scheme based on Jia et al.’s scheme using elliptic curve computational Diffie-Hellman hypothesis and hash functions.Additionally,we provide provable security under the adopted adversarial model and ProVerif simulation,and also analyze the performance in terms of computation and communication costs by comparisons.The analysis results show that the improved scheme resists the common attacks,reduces computation overhead,and has a certain significance.

Dynamically observing the formation of MOFs-driven Co/N-doped carbon nanocomposites by in-situ transmission electron microscope and their application as high-efficient microwave absorbent

Metal-organic frameworks(MOFs)derived magnetic carbon-based nanocomposites have drawn widespread attentions due to the well distributed nanocrystals in carbon matrix.Dynamically observing the formation process is urgently needed.Herein,taking zeolitic imidazolate framework(ZIF)-67 as an example,the pyrolysis process is investigated by in-situ transmission electron microscopy(TEM)assisted with ex-situ characterizations.Co nanocrystals are evenly distributed in carbon at the initial stage of carbonization.By increasing pyrolysis temperature,the nanocrystals grow bigger and migrate to carbon surface.The carbon texture transfers from amorphous to crystalline at 600°C,and thoroughly converts at 800°C.In-situ heating TEM shows that more tiny Co nanocrystals move out from the carbon texture by increasing temperature from 700 to 800°C.At 1,000°C,some escaped tiny Co nanocrystals are volatilized and disappeared.The residual escaped Co nanocrystals catalyze the formation of carbon nanotubes(CNTs).Due to the synergistic effect between Co and carbon as well as porous structure,the nanocomposites show high-efficient microwave absorption performance,which can be tuned by pyrolysis temperature,heating rate,and mass fraction.When the mass fraction is 30 wt.%,the nanocomposites obtained at 600 or 700°C display remarkable microwave absorption with optimal reflection loss(RL)smaller than−70 dB and effective absorption band larger than 4.9 GHz.Combining the in-situ and ex-situ techniques,some key findings were observed:(1)graphitization of carbon;(2)volatilization of Co nanocrystals;(3)formation process of CNTs by Co catalyst.These findings are helpful to understand the formation of MOFs derived carbon-based composites and expand their practical applications,especially for microwave absorption.

Spatial and frequency multimode in the dressing parametric amplified multiwave mixing process

The quantum multimode of correlated fields is essential for future quantum-correlated imaging.Here we investigate multimode properties theoretically and experimentally for the parametric amplified multiwave mixing process.The multimode behavior of the signals in our system stems from spatial phase mismatching caused by frequency resonant linewidth.In the spatial domain,we observe the emission rings with an uneven distribution of photon intensity in the parametric amplified four-wave mixing process,suggesting different spatial modes.The symmetrical distribution of spatial spots indicates the spatial correlation between the Stokes and anti-Stokes signals.While in the frequency domain,the multimode character is reflected as multiple peaks splitting in the signals'spectrum.A novelty in our experiment,the number of multimodes both in the spatial and frequency domains can be controlled by dressing lasers by modifying the nonlinear susceptibility.Finally,we extend the multimode properties to the multiwave mixing process.The results can be applied in quantum imaging.

Field assessment of straw pellet combustion in improved heating stoves in rural Northeast China

Straw pellets are widely promoted and expected to be a cleaner alternative fuel to unprocessed crop residues and rawcoal in rural China.However,the effectiveness of these dissemination programs is not well evaluated.In this field study,emission characteristics of burning strawpellets,rawcoal,and unprocessed corn cobs in heating stoveswere investigated in a pilot village in Northeast China.Emission measurements covering the whole combustion cycle(ignition,flaming,and smoldering phases)shows the promotion of improved heating stoves and straw pellets could reduce pollutant emissions(e.g.,SO_(2) and CO),but increase NO_(X) and PM_(2.5) emissions compared to the initial stove-fuel use pattern in the studied area.There is a significant variance in emission characteristics between different combustion phases.The normalized emission concentrations of the different stove-fuel combinations were higher than the limits in the Chinese national standard for heating stoves,indicating that the standard is not met for real-world emissions.Coal consumption was lower than official data.Household surveys were conducted to identify the barriers to fuel and stove access associated with existing promotion strategies,management,and policies.The pilot program was of the typical“subsidy-and-policy-dependence”pattern and was unlikely to be implemented on a large scale.Technological innovation,operational optimization,and proper policies considering the local socioeconomic factors are needed to sustain the promotion of biomass straw pellets and stoves.

A fine-grained privacy protection data aggregation scheme for outsourcing smart grid

Compared with the traditional power grid,smart grid involves many advanced technologies and applications.However,due to the rapid development of various network technologies,smart grid is facing the challenges of balancing privacy,security,efficiency,and functionality.In the proposed scheme,we design a privacy protection scheme for outsourcing smart grid aided by fog computing,which supports fine-grained privacy-protected data aggregation based on user characteristics.The fog server matches the encrypted characteristics in the received message with the encrypted aggregation rules issued by the service provider.Therefore,the service provider can get more fine-grained analysis data based on user characteristics.Different from the existing outsourcing smart grid schemes,the proposed scheme can achieve real-time pricing on the premise of protecting user privacy and achieving system fault tolerance.Finally,experiment analyses demonstrate that the proposed scheme has less computation overhead and lower transmission delay than existing schemes.

Study of the concentrations of Kr and Ar in high-purity nitrogen of JUNO

Purpose In the JUNO,the LS serves as the medium for detecting neutrinos.When purifying the LS using HPN,it is essential to ensure low background levels of radioactive krypton and argon in the HPN Methods Using the low-temperature physical adsorption properties of activated carbon to adsorb and separate radioactive gases such as radon,krypton,and argon from nitrogen in a liquid nitrogen environment.Results Our results indicated that the Kr concentration in the HPN purified by HP activated carbon is 6.84μBq/m,and the Ar concentration is 3.6μBq/m for overground HPN,while the Kr concentration is 31.4μBq/m for underground HPN.The^(85)Kr concentration in the nitrogen purified by coconut shell activated carbon is 0.46μBq/m.Conclusions After adsorption with activated carbon,the content of^(39)Kr and Ar in HPN is lower than the 50μBq/m required by JUNO.This work validates that the^(85)Kr and^(39)Ar concentrations in HPN is fit the JUNO requirement.

(-)-Epicatechin gallate serves as a novel new delhi metallo-β-lactamase-1(NDM-1)inhibitor

Theβ-lactam antibiotic resistance caused by NDM-1 has become a major crisis of global public health.We have previously screened out(-)-epicatechin gallate(ECG)as a potent NDM-1 inhibitor.We further discussed its inhibitory effect and action mode in the present study.According to our results,ECG reversibly inactivated NDM-1 in a non-competitive mode,with an IC50 value of 4.48μM.ECG effectively recovered the activity of severalβ-lactam antibiotics against resistant strain harboring blaNDM-1.Especially,the effects on carbapenems were worth mentioning.The zinc supplement assay indicated a zinc-related mechanism of ECG.Different from traditional chelating agents,it showed low toxicity both in vivo and in vitro.In a word,our findings provided a promising NDM-1 inhibitor,ECG,which was able to assist carbapenems against NDM-1-producing strain.

Dechlorination of 2,2＇,4,4＇,5,5＇-hexachlorobiphenyl by thermal reaction with activated carbon-supported copper or zinc

Activated carbon （AC）-supported copper or zinc made from ion exchange resin （IRCu-C and IRZn-C） have an increased metal load of 557.3 mg·g^-1 and 502.8 mg·g^-1 compared to those prepared by the traditional method involving impregnation with AC and copper （II） citrate or zinc citrate solution （LaCu-C and LaZn-C） of 12.9 mg·g^-1 and 46.0 mg·g^-1 respectively. When applied to decompose 2,2＇,4,4＇,5,5＇-hexachlorobiphenyl at 250 ℃, IRCu-C achieved higher activity of 99.0% decomposition efficiency than LaCu-C of 84.7%, IRZn-C of 90.5% and LaZn-C of 62.7%. When the reaction temperature rose to 350 ℃, all the four kinds of reactants can decompose PCB- 153 with efficiency above 90%. Further, X-ray photoelec- tron spectroscopy characterization of IRCu-C before and after the reaction indicated transformation of 19.1% of Cu atoms into Cu^2＋, illustrating that Cu is the active ingredient or electron donor promoting the decomposition of PCB- 153. The mechanism underlying this process differs from a traditional H donor. However, there is no significant change on the surface of IRZn-C before and after the reaction, suggesting that Zn acts as catalyst during the process of PCB-153 decomposition.

Cation ratio and oxygen defects for engineering the magnetic transition of monodisperse nonstoichiometric zinc ferrite nanoparticles

Monodisperse nonstoichiometric zinc ferrite nanoparticles with a tunable size of 4.1–32.2 nm are fabricated via thermal decomposition. An extrinsic impurity phase of the ZnO component is present in the zinc ferrite nanoparticles with a size of <10 nm, but this phase can be eliminated after the air annealing treatment. The atom ratio of Zn/Fe and concentration of oxygen vacancies decrease as the particle size of zinc ferrite increases, causing magnetic transition from superparamagnetism to ferromagnetism. The X-ray magnetic circular dichroism spectra reveal that the spin magnetic moments of Fe^(3+)are reduced, and the orbital magnetic moments are frozen with the increasing atom ratio of Zn/Fe. Therefore,saturation magnetization decreases. The saturation magnetizations of all the zinc ferrite nanoparticles decrease after the air annealing treatment, suggesting that oxygen vacancies considerably influence the magnetic properties. The air annealing treatment can minimize the number of oxygen defects,which trigger some of the Fe^(3+)–OV–Fe^(3+)ferrimagnetic couplings to transfer into the Fe^(3+)–O^(2-)–Fe^(3+)antiferromagnetic couplings. This work provides new insights regarding the magnetic performance of spinel ferrites by tuning the stoichiometric ratio and oxygen defects.