A meta-analysis of the impacts of forest logging on soil CO2 efflux

Soil CO2 efflux,the second largest flux in a forest carbon budget,plays an important role in global carbon cycling.Forest logging is expected to have large effects on soil CO2 efflux and carbon sequestration in forest ecosystems.However,a comprehensive understanding of soil CO2 efflux dynamics in response to forest logging remains elusive due to large variability in results obtained across individual studies.Here,we used a meta-analysis approach to synthesize the results of 77 individual field studies to determine the impacts of forest logging on soil CO2 efflux.Our results reveal that forest logging significantly stimulated soil CO2 efflux of the growing season by 5.02%.However,averaged across all studies,nonsignificant effect was detected following forest logging.The large variation among forest logging impacts was best explained by forest type,logging type,and time since logging.Soil CO2 efflux in coniferous forests exhibited a significant increase(4.38%)due to forest logging,while mixed and hardwood forests showed no significant change.Logging type also had a significant effect on soil CO2 efflux,with thinning increasing soil CO2 efflux by 12.05%,while clear-cutting decreasing soil CO2 efflux by 8.63%.The time since logging also had variable effects,with higher soil CO2 efflux for 2 years after logging,and lower for 3-6 years after logging;when exceeded 6 years,soil CO2 efflux increased.As significantly negative impacts of forest logging were detected on fine root biomass,the general positive effects on soil CO2 efflux can be explained by the accelerated decomposition of organic matter as a result of elevated soil temperature and organic substrate quality.Our results demonstrate that forest logging had potentially negative effects on carbon sequestration in forest ecosystems.

Processes of runoff in seasonally-frozen ground about a forested catchment of semiarid mountains

Climate warming increases the variability in runoff of semiarid mountains where seasonally-frozen ground is widely distributed.However,what is not well understood are the processes of runoff,hydrological drivers,and freeze-thaw cycles in seasonally-frozen ground in semiarid mountains.To understand how freeze-thaw cycles affect runoff processes in seasonally-frozen ground,we monitored hydrological processes in a typical headwater catchment with seasonally-frozen ground in Qilian Mountain,China,from 2002 to 2017.We analyzed the responses of runoff to temperature,precipitation,and seasonally-frozen ground to quantify process characteristics and driving factors.The results show that annual runoff was 88.5 mm accounting for 25.6%of rainfall,mainly concentrated in May to October,with baseflow of 36.44 mm.Peak runoff occurred in June,August,and September,i.e.,accounting for spring and summer floods.Runoff during the spring flood was produced by a mix of rainfall,melting snow,and melting seasonally-frozen ground,and had a significant correlation with air temperature.Runoff was mainly due to precipitation accumulation during the summer flood.Air temperature,average soil temperature at 0−50 cm depth,and frozen soil depth variable explained 59.60%of the variation of runoff in the thawing period,while precipitation variable explained 21.9%.Thawing-period runoff and soil temperature had a>0.6 correlation coefficient(P<0.05).In the rainfall-period,runoff was also affected by temperature,soil moisture,and precipitation,which explained 33.6%,34.1%and 18.1%,respectively.Our results show that increasing temperature and precipitation will have an irreversible impact on the hydrological regime in mountainous basins where seasonally-frozen ground is widely distributed.

Characterizing stand structure in a spruce forests:effects of sampling protocols

Spatial heterogeneity is an inherent characteristic of natural forest landscapes, therefore estimation of structural variability, including the collection and analyzing of field measurements, is a growing challenge for monitoring wildlife habitat di- versity and ecosystem sustainability. In this study, we investigated the combined influence of plot shape and size on the accuracy of assessment of conventional and rare structural features in two young-growth spruce-dominated forests in northwestern China. We used a series of inventory schemes and analytical approaches. Our data showed that options for sampling protocols, especially the selection of plot size considered in structural attributes measurement, dramatically af- fect the minimum number of plots required to meet a certain accuracy criteria. The degree of influence of plot shape is related to survey objectives; thus, effects of plot shape differ for evaluations of the ＂mean＂ or ＂representative＂ stand structural conditions from that for the range of habitat （in extreme values）. Results of Monte Carlo simulations suggested that plot sizes 〈0.1 ha could be the most efficient way to sample for conventional characteristics （features with relative constancy within a site, such as stem density）. Also, 0.25 ha or even larger plots may have a greater likelihood of capturing rare structural attributes （features possessing high randomness and spatial heterogeneity, such as volume of coarse woody debris） in our forest type. These findings have important implications for advisable sampling protocol （plot size and shape） to adequately capture information on forest habitat structure and diversity; such efforts must be based on a clear definition of which types are structural attributes to measure.

mRNA疫苗脂质纳米颗粒递送系统的专利发展状况分析

本文分析了全球范围内mRNA疫苗脂质纳米颗粒递送技术的专利申请现状和进展,深入挖掘该领域的技术发展动态,分析对比国内外申请人的相关情况,以期为国内医药领域从事mRNA递送系统研究人员提供参考与启示。

电化学还原高压CO_(2)捕集溶液制太阳能燃料

本文突破单一考虑CO_(2)转化的局限,从CO_(2)捕集-转化-利用集成的角度提出了直接光/电化学还原高压CO_(2)捕集溶液制太阳能燃料,在捕集端避免高温条件气相CO_(2)再生步骤;在产无端利用CO_(2)和CO溶解度的巨大差异,实现零能耗气体产物分离;在转化过程中,本文建立了考虑压力的光/电化学CO_(2)还原多尺度方法.本文建立了微观第一性原理计算-介观动力学模拟-宏观输运模型耦合的多尺度模型,以基元反应参数、分电流密度作为跨接参数,以电极表面CO_(2)浓度、pH作为迭代参数,实现了多尺度模拟计算;研究了宏观压力变化对界面微环境(电极表面分子覆盖度和局域pH)的作用机制,发现分子覆盖度对CO_(2)还原反应的促进作用与局域pH对析氢反应的抑制作用相协同,实现了CO_(2)高效、高选择性转化.本文研制了直接光/电化学还原高压CO_(2)捕集溶液制太阳能燃料原理样机,太阳能制燃料效率达到16.8%,超过了文献报道的饱和CO_(2)溶液供给的太阳能制燃料系统.

iVenomDB: A manually curated database for insect venom proteins

DearEditor,Venomous animals,such as snakes,insects(wasps,bees,ants,and some bugs),spiders,scorpions,and cone snails,use venom for predation and/or defense.Venom is mostly composed of proteinsand peptides.Because of their high potency and selectivity,venom components have been developed into valuable resources,such as research tools,bioinsecticides(Heep et al.,2019),and drug leads(Badawi,2021).The advent of high-throughput sequencing and mass spectrometry enabled exploration of venom components to new depths and at an unprecedented pace.To be useful to the scientific community,knowledge on these proteins must be stored in a retrievable manner,annotated,and curated.Currently,several databases are dedicated to venoms from a wide range of animals,such as Arachnoserver(Pineda et al.,2018),Conoserver(Kaas et al.,2012),and the Tox-Prot program within UniprotKB(Jungo et al.,2012).

Long-term thinning decreases the contribution of heterotrophic respiration to soil respiration in subalpine plantations

Interest in the dynamics of soil respiration(R_(S))in subalpine forest ecosystems is increasing due to their high soil carbon density and potential sensitivity to environmental changes.However,as a principal silvicultural practice,the long-term impacts of thinning on R_(S) and its heterotrophic and autotrophic respiration components(R_(h) and Ra,respectively)in subalpine plantations are poorly understood,espe-cially in winter.A 3-year field observation was carried out with consideration of winter CO_(2) efflux in middle-aged sub-alpine spruce plantations in northwestern China.A trench-ing method was used to explore the long-term impacts of thinning on R,Rn and Ra.Seventeen years after thinning,mean annual Rs,Rn and R_(a) increased,while the contribu-tion of R_(h) to R_(s) decreased with thinning intensity.Thinning significantly decreased winter R,because of the reduction in Rn but had no significant effect on Ra.The temperature sensitivity(Q_(10))of R_(h) and R_(a) also increased with thinning intensity,with lower Q_(10) values for R_(h)(2.1-2.6)than for Ra(2.4-2.8).The results revealed the explanatory variables and pathways related to Rn and R_(a) dynamics.Thinning increased soil moisture and nitrate nitrogen(NO_(3)^(-)-N),and the enhanced nitrogen and water availability promoted R_(h) and R_(a) by improving fine root biomass and microbial activity.Our results highlight the positive roles of NO_(3)^(-)-N in stimulating R_(s) components following long-term thinning.Therefore,applications of nitrogen fertilizer are not recommended while thinning subalpine spruce plantations from the perspective of reducing soil CO_(2) emissions.The increased Q_(10) values of R_(s) components indicate that a large increase in soil CO_(2) emissions would be expected following thinning because of more pronounced climate warming in alpineregions.

Analysis of a 1 kW organic Rankine cycle using a scroll expander for engine coolant and exhaust heat recovery

The development of engine waste heat recov- ery technologies attracts ever increasing interests due to the rising strict policy requirements and environmental con- cerns. This paper presented the study of engine coolant and exhaust heat recovery using organic Rankine cycle （ORC）. Eight working fluids were selected to evaluate and compare the performance of the integrated waste heat recovery system. Rather than the conventional engine ORC system mainly focusing on the utilization of exhaust energy, this work proposed to fully use the engine coolant energy by changing the designed parameters of the ORC system. The case study selected a small engine as the heat source to drive the ORC system using a scroll expander for power production. The evaluation results suggest that under the engine rated condition, the solution to fully recover the engine coolant energy can achieve a higher power generation performance than that of the conven- tional engine ORC system. The results suggest that adding a recuperator to the ORC system can potentially improve the system performance when the working fluids are dry and the overall dumped heat demand of the system can be reduced by 12% under optimal conditions. When the ORC evaporating and condensing temperature are respectivelyset at 85℃ and 30℃, the integrated engine waste heat recovery system can improve the overall system efficiency by 9.3% with R600, R600a or n-Pentane as the working fluid.

Influence of geometry on the thermal performance of water pit seasonal heat storages for solar district heating

The aim of the study is to investigate the influence of geometry on the thermal capacity and stratifications of a water pit heat storage for solar district heating.A TRNSYS component model for a truncated cone water pit was developed based on the coordinate transformation method and validated by experimental results from the water pit heat storage in Huangdicheng in 2018.The thermal performance of 26 water pits with different heights and side wall slopes was calculated for 10 consecutive years.It takes four to six years for the water pit to reach steady-state operation.The operation data from the tenth year was selected to evaluate the thermal performance of each configuration.The results show that because of the thermal insulation on top of the water pit,the height to diameter ratio of a water pit with minimum annual heat loss was always smaller than 1.0.The annual storage efficiency of a water pit increases with side wall slope due to the reduced side wall area.There is an almost linear increase in the thermal stratification number of a water pit with height.With an increase in the height,thermal stratification in water pits with a steeper slope increased more gradually than water pits with a lower slope.The findings in this paper are relevant for the design optimization of water pits as seasonal thermal energy storages.

In silico Analysis of the Potential Infection Mechanisms of Magnaporthe grisea from Horizontal Gene Transfer Hypothesis

Horizontal gene transfer （HGT） has long been considered as a principal force for an organism to gain novel genes in genome evolution. Homology search, phylogenetic analysis and nucleotide composition analysis are three major objective approaches to arguably determine the occurrence and directionality of HGT. Here, 21 genes that possess the potential to horizontal transfer were acquired from the whole genome of Magnaporthe grisea according to annotation, among which three candidate genes （corresponding protein accession numbers are EAA55123, EAA47200 and EAA52136） were selected for further analysis. According to BLAST homology results, we subsequently conducted phylogenetic analysis of the three candidate HGT genes. Moreover, nucleotide composition analysis was conducted to further validate these HGTs. In addition, the functions of the three candidate genes were searched in COG database. Consequently, we conclude that the gene encoding protein EAA55123 is transferred from Clostridium perfringens. Another HGT event is between EAA52136 and a certain metazoan＇s corresponding gene, but the direction remains uncertain. Yet, EAA47200 is not a transferred gene.

The TMRT K band observations towards 26 infrared dark clouds:NH_3, CCS, and HC_3N

We present one of the first Shanghai Tian Ma Radio Telescope (TMRT) K Band observations towards a sample of 26 infrared dark clouds (IRDCs).We observed the (1,1),(2,2),(3,3),and (4,4) transitions of NH_(3) together with CCS (2_(1)–>1_(0)) and HC_(3)NJ=2-1,simultaneously.The survey dramatically increases the existing CCS-detected IRDC sample from 8 to 23,enabling a better statistical study of the ratios of carbon-chain molecules (CCM) to N-bearing molecules in IRDCs.With the newly developed hyperfine group ratio (HFGR) method of fitting NH_(3) inversion lines,we found the gas temperature to be between 10 and18 K.The column density ratios of CCS to NH_(3) for most of the IRDCs are less than 10^(-2),distinguishing IRDCs from low-mass star-forming regions.We carried out chemical evolution simulations based on a three-phase chemical model NAUTILUS.Our measurements of the column density ratios between CCM and NH_(3) are consistent with chemical evolutionary ages of 10^(5) yr in the models.Comparisons of the data and chemical models suggest that CCS,HC_(3)N,and NH_(3) are sensitive to the chemical evolutionary stages of the sources.

Touchable cell biophysics property recognition platforms enable multifunctional blood smart health care

As a crucial biophysical property,red blood cell(RBC)deformability is pathologically altered in numerous disease states,and biochemical and structural changes occur over time in stored samples of otherwise normal RBCs.However,there is still a gap in applying it further to point-of-care blood devices due to the large external equipment(high-resolution microscope and microfluidic pump),associated operational difficulties,and professional analysis.Herein,we revolutionarily propose a smart optofluidic system to provide a differential diagnosis for blood testing via precise cell biophysics property recognition both mechanically and morphologically.Deformation of the RBC population is caused by pressing the hydrogel via an integrated mechanical transfer device.The biophysical properties of the cell population are obtained by the designed smartphone algorithm.Artificial intelligence-based modeling of cell biophysics properties related to blood diseases and quality was developed for online testing.We currently achieve 100%diagnostic accuracy for five typical clinical blood diseases(90 megaloblastic anemia,78 myelofibrosis,84 iron deficiency anemia,48 thrombotic thrombocytopenic purpura,and 48 thalassemias)via real-world prospective implementation;furthermore,personalized blood quality(for transfusion in cardiac surgery)monitoring is achieved with an accuracy of 96.9%.This work suggests a potential basis for next-generation blood smart health care devices.