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 Rs,Rn and R_(a).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 R_(n) 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 R_(n) 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.

Moso bamboo expansion decreased soil heterotrophic respiration but increased arbuscular mycorrhizal mycelial respiration in a subtropical broadleaved forest

Moso bamboo(Phyllostachys Pubescens)expansion into adjacent forests has been widely reported to affect plant diversity and its association with mycorrhizal fungi in subtropical China,which will likely have significant impacts on soil respiration.However,there is still limited information on how Moso bamboo expansion changes soil respiration components and their linkage with microbial community composition and activity.Based on a mesh exclusion method,soil respirations derived from roots,arbuscular mycorrhizal(AM)mycelium,and free-living microbes were investigated in a pure Moso bamboo forest(expanded),an adjacent broadleaved forest(nonexpanded),and a mixed bamboo-broadleaved forest(expanding).Our results showed that bamboo expansion decreased the cumulative CO_(2)effluxes from total soil respiration,root respiration and soil heterotrophic respiration(by 19.01%,30.34%,and 29.92%on average),whereas increased those from AM mycelium(by 78.67%in comparison with the broadleaved forests).Bamboo expansion significantly decreased soil organic carbon(C)content,bacterial and fungal abundances,and enzyme activities involved in C,N and P cycling whereas enhanced the interactive relationships among bacterial communities.In contrast,the ingrowth of AM mycelium increased the activities ofβ-glucosidase and N-acetyl-β-glucosaminidase and decreased the interactive relationships among bacterial communities.Changes in soil heterotrophic respiration and AM mycelium respiration had positive correlations with soil enzyme activities and fungal abundances.In summary,our findings suggest that bamboo expansion decreased soil heterotrophic respiration by decreasing soil microbial activity but increased the contribution of AM mycelial respiration to soil C efflux,which may potentially increase soil C loss from AM mycelial pathway.

Response of soil respiration to short-term changes in precipitation and nitrogen addition in a desert steppe

Changes in precipitation and nitrogen(N)addition may significantly affect the processes of soil carbon(C)cycle in terrestrial ecosystems,such as soil respiration.However,relatively few studies have investigated the effects of changes in precipitation and N addition on soil respiration in the upper soil layer in desert steppes.In this study,we conducted a control experiment that involved a field simulation from July 2020 to December 2021 in a desert steppe in Yanchi County,China.Specifically,we measured soil parameters including soil temperature,soil moisture,total nitrogen(TN),soil organic carbon(SOC),soil microbial biomass carbon(SMBC),soil microbial biomass nitrogen(SMBN),and contents of soil microorganisms including bacteria,fungi,actinomyces,and protozoa,and determined the components of soil respiration including soil respiration with litter(RS+L),soil respiration without litter(RS),and litter respiration(RL)under short-term changes in precipitation(control,increased precipitation by 30%,and decreased precipitation by 30%)and N addition(0.0 and 10.0 g/(m^(2)·a))treatments.Our results indicated that short-term changes in precipitation and N addition had substantial positive effects on the contents of TN,SOC,and SMBC,as well as the contents of soil actinomyces and protozoa.In addition,N addition significantly enhanced the rates of RS+L and RS by 4.8%and 8.0%(P<0.05),respectively.The increase in precipitation markedly increased the rates of RS+L and RS by 2.3%(P<0.05)and 5.7%(P<0.001),respectively.The decrease in precipitation significantly increased the rates of RS+L and RS by 12.9%(P<0.05)and 23.4%(P<0.001),respectively.In contrast,short-term changes in precipitation and N addition had no significant effects on RL rate(P>0.05).The mean RL/RS+L value observed under all treatments was 27.63%,which suggested that RL is an important component of soil respiration in the desert steppe ecosystems.The results also showed that short-term changes in precipitation and N addition had significant interactive effects on the rates of RS+L,RS,and RL(P<0.001).In addition,soil temperature was the most important abiotic factor that affected the rates of RS+L,RS,and RL.Results of the correlation analysis demonstrated that the rates of RS+L,RS,and RL were closely related to soil temperature,soil moisture,TN,SOC,and the contents of soil microorganisms,and the structural equation model revealed that SOC and SMBC are the key factors influencing the rates of RS+L,RS,and RL.This study provides further insights into the characteristics of soil C emissions in desert steppe ecosystems in the context of climate change,which can be used as a reference for future related studies.

Transcriptome Analysis Reveals New Insights into the Respiration Metabolism Mechanism of Different Feeding Rations of Sea Cucumber(Apostichopus japonicus)

Sea cucumber(Apostichopus japonicus)is an excellent model for investigating effects of bottom-dwellers on carbon mig-ration and transformation.However,the molecular mechanism of respiratory metabolism process variation caused by feeding rations is poorly understood.In this study,treatment groups set as 1%(about 0.63g),3%,and 7%of total body weight(named F1,F3 and F7 groups respectively).The potential molecular mechanisms behind the functions of respiratory tree and body wall were investigated by RNA-Seq.A total of 52411 expressed genes were identified from 89342 expressed transcripts.The results showed 759,254 and 334 genes were up-regulated,and 334,445 and 992 genes were down-regulated in respiratory tree of F1 vs.F3,F1 vs.F7 and F3 vs.F7,respectively.Meanwhile,2070,1601 and 896 genes were up-regulated,and 1303,1337 and 1144 genes were down-regulated in body wall between F1 vs.F3,F1 vs.F7 and F3 vs.F7,respectively.Differentially expressed genes were enriched in salivary secretion and ECM-receptor interaction pathways in respiratory tree,and in various types of N-glycan biosynthesis,ribosome and sphingolipid metabolism pathways in body wall.These results suggested respiratory tree and body wall were involved in activation of respiratory metabolisms in response to different feeding rations.Our research provided valuable knowledge for physiological differences in res-piratory metabolism.

Accuracy of Mean Value of Central Venous Pressure from Monitor Digital Display: Influence of Amplitude of Central Venous Pressure during Respiration

Background A simple measurement of central venous pressure(CVP)-mean by the digital monitor display has become increasingly popular.However,the agreement between CVP-mean and CVP-end(a standard method of CVP measurement by analyzing the waveform at end-expiration)is not well determined.This study was designed to identify the relationship between CVP-mean and CVP-end in critically ill patients and to introduce a new parameter of CVP amplitude(ΔCVP=CVPmax-CVPmin)during the respiratory period to identify the agreement/disagreement between CVP-mean and CVP-end.Methods In total,291 patients were included in the study.CVP-mean and CVP-end were obtained simultaneously from each patient.CVP measurement difference(|CVP-mean-CVP-end|)was defined as the difference between CVP-mean and CVP-end.TheΔCVP was calculated as the difference between the peak(CVPmax)and the nadir value(CVPmin)during the respiratory cycle,which was automatically recorded on the monitor screen.Subjects with|CVP-mean-CVP-end|≥2 mm Hg were divided into the inconsistent group,while subjects with|CVP-mean-CVP-end|2 mm Hg were divided into the consistent group.ResultsΔCVP was significantly higher in the inconsistent group[7.17(2.77)vs.5.24(2.18),P0.001]than that in the consistent group.There was a significantly positive relationship betweenΔCVP and|CVP-mean-CVP-end|(r=0.283,P 0.0001).Bland-Altman plot showed the bias was-0.61 mm Hg with a wide 95%limit of agreement(-3.34,2.10)of CVP-end and CVP-mean.The area under the receiver operating characteristic curves(AUC)ofΔCVP for predicting|CVP-mean-CVP-end|≥2 mm Hg was 0.709.With a high diagnostic specificity,usingΔCVP3 to detect|CVP-mean-CVP-end|lower than 2mm Hg(consistent measurement)resulted in a sensitivity of 22.37%and a specificity of 93.06%.UsingΔCVP8 to detect|CVP-mean-CVPend|8 mm Hg(inconsistent measurement)resulted in a sensitivity of 31.94%and a specificity of 91.32%.Conclusions CVP-end and CVP-mean have statistical discrepancies in specific clinical scenarios.ΔCVP during the respiratory period is related to the variation of the two CVP methods.A highΔCVP indicates a poor agreement between these two methods,whereas a lowΔCVP indicates a good agreement between these two methods.

Heartbeat and Respiration Rate Prediction Using Combined Photoplethysmography and Ballisto Cardiography

Owing to the recent trends in remote health monitoring,real-time appli-cations for measuring Heartbeat Rate and Respiration Rate(HARR)from video signals are growing rapidly.Photo Plethysmo Graphy(PPG)is a method that is operated by estimating the infinitesimal change in color of the human face,rigid motion of facial skin and head parts,etc.Ballisto Cardiography(BCG)is a non-surgical tool for obtaining a graphical depiction of the human body’s heartbeat by inducing repetitive movements found in the heart pulses.The resilience against motion artifacts induced by luminancefluctuation and the patient’s mobility var-iation is the major difficulty faced while processing the real-time video signals.In this research,a video-based HARR measuring framework is proposed based on combined PPG and BCG.Here,the noise from the input video signals is removed by using an Adaptive Kalmanfilter(AKF).Three different algorithms are used for estimating the HARR from the noise-free input signals.Initially,the noise-free sig-nals are subjected to Modified Adaptive Fourier Decomposition(MAFD)and then to Enhanced Hilbert vibration Decomposition(EHVD)andfinally to Improved Var-iation mode Decomposition(IVMD)for attaining three various results of HARR.The obtained values are compared with each other and found that the EHVD is showing better results when compared with all the other methods.

减氮施炭对温室膜下滴灌黄瓜土壤呼吸和氮素气态损失的影响

为降低温室蔬菜过量施氮的不利影响,明确减氮施炭条件下温室膜下滴灌黄瓜土壤呼吸和氮素气态排放特征,以不覆膜不施炭(CK)为对照,设置覆膜(M)、覆膜施炭(MB)、覆膜施炭减氮(MBN_(80%))共4个处理,对覆膜条件下减氮施炭处理对黄瓜产量、耗水量、土壤养分动态、土壤呼吸、N_(2)O排放和氨挥发的影响进行探讨。结果表明:与CK相比,M可降低温室膜下滴灌黄瓜全生育期耗水量20.95%,提高水分利用效率41.03%,降低0~20 cm表层土铵态氮48.12%,降低全生育期氨挥发32.35%、N_(2)O排放量14.34%和CO_(2)排放量12.68%(<0.05)。施炭后,与CK相比,MB可降低耗水量28.37%,提高水分利用效率55.60%,降低表层土铵态氮30.0%,提升硝态氮12.37%,有机质56.28%,降低氨挥发36.68%、N_(2)O排放18.64%,但却显著增大了CO_(2)排放4.66%(p<0.05)。同M对比,MB可在M基础上,进一步提升表层土有机质和铵态氮含量,降低氨挥发,但促进了CO_(2)排放。覆膜施炭减氮20%后,与CK相比,MBN_(80%)可增产25.47%,降低耗水量32.43%,提升水分生产率72.67%,降低表层土铵态氮56.33%,增加有机质51.72%,降低氨挥发40.48%、N_(2)O排放20.79%(p<0.05)。CK全生育期全球增温潜势(global warming potential,GWP)和活性氮排放分别为13.57 t·CO_(2)-eq·hm^(-2)和6.54 kg·hm^(-2),M可显著降低GWP(14.15%)和活性氮排放(27.37%);在M基础上施炭,将进一步降低活性氮排放,但导致GWP显著增大;而在MB基础上减氮20%,可同时显著降低GWP和活性氮排放(p<0.05)。与CK相比,MBN80%在通过施炭20 t·hm^(-2),减氮20%条件下,实现增产25.47%,降低耗水量32.43%,增加有机质51.72%,增加收入17.52%,降低活性氮排放35.32%和GWP 2.28%,也可在MB的基础上,进一步实现增产,降低氨挥发,并破解M和MB处理CO_(2)排放增大的问题(p<0.05)。研究揭示了减氮施炭条件下温室膜下滴灌黄瓜土壤呼吸和氮素气态排放特征,为实现温室蔬菜节水增产固碳减排提供理论依据和技术支撑。

减氮配施生物炭对北疆小麦产量品质及固碳减排的影响

为研究生物炭在北疆灌区农田应用的稳产增产及固碳减排综合潜力,探索农田氮肥优化施用途径,该研究于2021年4月—2022年7月在新疆奇台设置常规施氮(N1:300 kg/hm^(2))、氮肥减量15%(N2:255 kg/hm^(2))、氮肥减量30%(N3:210 kg/hm^(2))、单施生物炭(B:20 t/hm^(2))、常规施氮+生物炭(N1B)、氮肥减量15%+生物炭(N2B)、氮肥减量30%+生物炭(N3B)7个处理,分析两季小麦(春小麦、冬小麦)种植期间不同处理下麦田土壤有机碳含量、土壤呼吸速率、小麦品质及产量变化。结果表明,与单施常规氮肥相比,施用生物炭后土壤总有机碳(soil total organic carbon,SOC)、活性有机碳(active organic carbon,AOC)、碳库管理指数(carbon pool management index,CPMI)和小麦产量、籽粒水分及蛋白(干基)含量均呈提高趋势。综合表现以氮肥减量15%配施生物炭(N2B)处理最优,较氮肥常规单施(N1)相比,AOC、SOC均有显著提高,2 a产量分别显著提高22.12%、36.17%(P<0.05)。与常规施氮相比,氮肥减量15%配施生物炭(N2B)处理下,2022年冬小麦蛋白(干基)、面筋(湿基)、Zeleny沉降值均有提高,而2021年各处理间差异不显著(P>0.05)。同时,除单施生物炭(B)处理(2021年)和除单施生物炭(B)及减氮15%(N2)处理外(2022年),其他处理下土壤CO_(2)累积排放量较单施常规氮肥均有所升高。综上,氮肥减量15%(255 kg/hm^(2))配施20 t/hm^(2)生物炭时其农田土壤固碳减排效果及小麦产量品质综合表现较好,建议作为北疆灌区麦田氮肥优化配施生物炭的理想施肥方案。

水雾粒子特性对呼吸性粉尘降尘效率影响研究

为有效去除工业生产中的呼吸性粉尘,提高水雾粒子对呼吸性粉尘的捕捉效率,基于三相流理论建立了高速气流中单颗粒雾-尘碰撞耦合数值模型。研究高速气流中单颗粒雾-尘碰撞耦合过程,分析雾-尘粒径比及相对速度对尘粒表面线积分润湿度的影响。结果表明,对于不同粒径等级的呼吸性粉尘,达到最佳润湿度对应的雾-尘粒径比不同,k(PM1)=15、k(PM2.5)=2和k(PM5)=1。在高速气流中雾-尘相对运动状态不同时,粉尘颗粒的最佳润湿度随雾-尘相对速度U增大而增大。搭建仿真试验模型,研究不同情况下水雾粒子的捕尘效率。结果表明,超音速雾化喷嘴对呼吸性粉尘的降尘效率为95.95%,单流体喷嘴降尘效率为82.98%。结合现场试验对比分析,验证雾-尘粒径比及相对速度对尘粒表面线积分润湿度的影响规律。结果表明,越符合粉尘粒子被捕捉的最佳粒径比的喷嘴的降尘效率越高,提高尘雾粒子碰撞速度可以提高对粉尘粒子的捕捉效率,为治理呼吸性粉尘及清洁化工业生产提供理论依据。

柔性可穿戴湿敏传感器制备及呼吸检测实验

该文以壳聚糖/导电炭黑复合薄膜作为敏感层,构建了高性能湿度传感器,并研究了传感器件微结构薄膜对呼吸检测敏感的机理。该文展开实验测试了传感器的湿度及呼吸响应特性,使用灵敏度、响应恢复特性、重复性等参数评价传感器性能,同时基于LabVIEW技术实现了湿敏/呼吸信号的实时读取与处理、单片机与电脑终端通信、呼吸波形显示等功能。该检测平台成本低、易操作,为传感器检测技术的实际应用提供了借鉴,同时可促进学生对柔性可穿戴传感器检测实验与应用的深度理解,有效提升课堂教学效果和学生的学习积极性。

凋落物处理对华山松人工林土壤呼吸的影响

【目的】通过探讨凋落物添加和去除处理对土壤呼吸速率的影响,为人工林土壤碳库管理提供理论依据。【方法】以神农架林区华山松人工林为研究对象,2021年4月—2022年3月通过设置对照(CK)、凋落物去除(LR)和凋落物添加(LA)3种处理,采用Li-8100A土壤碳通量测量系统测定土壤呼吸速率和土壤温湿度,研究土壤呼吸速率对凋落物处理的响应规律。【结果】1)3种处理间的土壤温度和土壤含水量均无显著差异(P>0.05),土壤呼吸速率与土壤温度的变化趋势一致,最大值均出现在7月,最小值均出现在2月;2)3种处理下土壤呼吸速率的年平均值为LA(2.17μmol·m^(-2)·S^(-1))>CK(1.69μmol·m^(-2)·S^(-1))>LR(1.25μmol·m^(-2)·S^(-1)),与对照相比,凋落物去除使土壤呼吸速率年均降低了26.02%,凋落物添加使土壤呼吸速率年均提高了29.48%;3)不同凋落物处理的土壤呼吸速率与土壤温度均呈极显著正相关(P<0.01),土壤温度分别解释了3种处理下土壤呼吸速率97.31%、99.18%和95.37%的变异。而土壤呼吸速率与土壤含水量相关性不显著(P>0.05),华山松人工林土壤呼吸速率的主要影响因子是土壤温度;4)土壤呼吸温度敏感性指数(Q10)为CK(2.98)>LR(2.91)>LA(2.88),凋落物去除和添加处理均降低了土壤呼吸温度敏感性。【结论】凋落物输入量的改变对土壤呼吸速率具有重要影响,且不同处理方式对土壤呼吸影响程度不一致。

水分及秸秆覆盖对夏玉米土壤呼吸及碳平衡的影响

【目的】充分发挥秸秆覆盖与适宜灌溉对作物增产及土壤固碳减排的各自优势及二者协同效应,建立减排增产节水的高效农田管理模式。【方法】以豫东地区夏玉米为研究对象,设置覆盖方式(秸秆覆盖(S)和无覆盖(N))和灌水控制下限(田间持水率(FC)的50%(W1)、60%(W2)、70%(W3)、80%(W4))两因素试验,系统研究水分及秸秆覆盖对土壤碳排放总量、土壤微生物异氧呼吸碳释放量和农田净初级生产力固碳量影响。【结果】秸秆覆盖和灌水增加了土壤呼吸、农田净初级生产力固碳量和土壤微生物异氧呼吸碳释放量,其中SW4处理均最高,与SW3、NW4处理差异不显著。SW3处理净生态系统生产力(NEP)和碳排放效率均最高,分别较其他处理高3.99%~245.74%和2.35%~138.80%。与SW4处理相比,SW3处理在节约灌水的前提下,农田净生态系统生产力提高2.99%,碳排放效率提高2.35%。【结论】综合考虑农田净生态系统生产力和碳排放效率,SW3处理(灌水控制下限为70%FC+秸秆覆盖)可以作为节水、减排、增产的农田管理模式。

三江平原退化湿地不同恢复方式对土壤呼吸的影响

通过对2种人工恢复湿地、自然恢复湿地和天然湿地土壤呼吸及环境因子的测定,探讨了不同恢复方式对土壤呼吸的影响。结果表明,4种湿地类型土壤呼吸通量分别为420.77(人工恢复大叶章湿地)、270.46(人工恢复瘤囊薹草湿地)、916.1(自然恢复湿地)和413.6 mg·m-2h-1(天然湿地),人工恢复大叶章湿地和自然恢复湿地土壤呼吸无显著差异(P>0.05),其他湿地类型之间差异显著(P<0.01)。DOC、NH4+-N、NO3--N、pH和V是不同恢复方式湿地土壤生态差异的主要贡献变量。土壤呼吸与pH和T存在显著正相关关系(P<0.01),与DOC、NO3--N和V存在显著负相关关系(P<0.05)。本研究中的2种人工恢复湿地土壤呼吸均低于自然恢复湿地,从减少土壤碳排放的角度来看人工恢复措施是可行且有效的。

乙酰半胱氨酸辅助治疗重症支气管肺炎患儿的疗效及对潮气呼吸肺功能、免疫功能的影响

目的探讨乙酰半胱氨酸辅助治疗重症支气管肺炎患儿的疗效及对潮气呼吸肺功能、免疫功能的改善作用。方法选取西华县人民医院重症支气管肺炎患儿90例(2021年1月至2023年8月),按照随机数字表法分为试验组(45例)和常规组(45例)。常规组给予阿奇霉素,试验组给予阿奇霉素联合乙酰半胱氨酸。比较两组临床疗效、症状消失时间、潮气呼吸肺功能[潮气量(VT/kg)、达峰时间比(TPTEF/TE)、达峰容积比(VPEF/VE)]、免疫功能(CD3^(+)、CD4^(+)、CD4^(+)/CD8^(+))、炎症指标[白介素1受体1型(IL-1R1)、活化蛋白C(APC)]及不良反应。结果试验组治疗有效率88.89%高于常规组71.11%,差异有统计学意义(P<0.05);试验组发热、咳嗽、气促及肺部啰音消失时间短于常规组,差异有统计学意义(P<0.05);与治疗前相比,两组治疗7 d后VPEF/VE、TPTEF/TE、VT/kg均明显升高,试验组高于常规组,差异有统计学意义(P<0.05);与常规组相比,观察组治疗7 d后CD3^(+)、CD4^(+)、CD4^(+)/CD8^(+)均明显升高,差异有统计学意义(P<0.05);试验组治疗7 d后血清IL-1R1水平低于常规组,APC高于常规组,差异有统计学意义(P<0.05);治疗期间,试验组不良反应发生率(11.11%)与常规组(6.67%)相比,差异无统计学意义(P>0.05)。结论乙酰半胱氨酸联合阿奇霉素能调节重症支气管肺炎患儿免疫失衡,减轻炎症,有效缓解病情,改善潮气呼吸肺功能,增强疗效。

多导睡眠图辅助药物诱导睡眠内镜正压呼吸机压力滴定的操作要点

识别阻塞性睡眠呼吸暂停(OSA)患者上气道阻塞和狭窄情况对于决定后续治疗方案至关重要。药物诱导睡眠内镜(DISE)是可提供OSA患者麻醉后“睡眠”状态时上呼吸道解剖学结构的三维可视化评估技术,通过内镜安全而快速地观察上呼吸道阻塞及塌陷的动态情况,为制定手术方案、进行气道正压(PAP)干预治疗等提供重要参考。在多导睡眠图(PSG)辅助下,DISE对优化OSA个体化治疗方案发挥重要作用。该文介绍了多导睡眠图辅助药物诱导睡眠内镜正压呼吸机压力滴定的操作要点。

桉树人工林土壤呼吸昼夜变化及其对环境因子的响应

以雷州半岛地区尾叶桉人工林为研究对象,采用LI-8150土壤碳通量测量系统,连续测定其土壤呼吸速率及相关环境因子的昼夜变化规律,分析土壤呼吸的时间变化特征及其对环境因子变化的响应,旨在为桉树人工林生态系统土壤碳排放估算提供数据支持。结果表明:尾叶桉人工林土壤呼吸速率昼夜变化为双峰趋势,最大值和最小值分别在4:00和16:00取得,分别为3.95μmol·m^(-2)·s^(-1)和3.29μmol·m^(-2)·s^(-1),日均值为3.61μmol·m^(-2)·s^(-1)。从昼夜变化来看,土壤呼吸与土壤温度、土壤热通量呈极显著负相关。从月变化来看,土壤呼吸与土壤温、湿度均存在极显著正相关关系。土壤日碳排放量为2.59~4.56 g·m^(-2)。可见,对人工林土壤碳排放进行估算时应考虑不同时间尺度环境因子对土壤呼吸影响的方向和强度。

生草对贵州高海拔区苹果园土壤呼吸及水热环境的影响

【目的】探明西南冷凉高地苹果产区果园不同草种覆盖条件土壤呼吸特征及其与土壤水热的关系,为筛选苹果园适宜生草类型提供参考依据。【方法】设置鼠茅草(Vulpia myuros)、鸭茅(Dactylis glomerata)、黑麦草(Lolium perenne)、白三叶(Trifolium repens)、光叶紫花苕(Vicia villosa)、鼠茅草+鸭茅+白三叶混播、黑麦草+白三叶+鸭茅混播、鼠茅草+黑麦草+白三叶混播8个苹果园生草处理,以清耕作对照(CK),利用LI-6400XT便携式光合测定系统配套使用土壤呼吸气室(6400-09)测定果园土壤呼吸速率,采用非线性回归和指数模型,分析不同生草处理对土壤呼吸与土壤水热环境的影响。【结果】生草显著提高果园土壤呼吸速率,较清耕提高0.07%~256.39%,其中,黑麦草+白三叶+鸭茅混播处理提高幅度最高。生草覆盖显著提高土壤水分保持能力,对0~20 cm土层的影响最明显,相同月份不同生草处理间土壤水分差异明显,生草混播处理提高土壤水分能力优于生草单播处理。生草覆盖后显著降低夏季(5—7月)表层土壤(0~5 cm)温度。不同生草覆盖处理土壤水分含量与土壤呼吸以二次函数拟合效果最佳,决定系数R 2在0.242~0.989,拟合度较高。各生草处理土壤温度与土壤呼吸速率呈指数函数关系,0~5 cm和5~10 cm土层拟合模型决定系数R 2平均值高于10~15 cm和15~20 cm土层。土壤温度、水分及二者的交互作用对土壤呼吸的协同影响高于土壤单因子的影响。【结论】苹果园生草处理可显著提高土壤呼吸速率,显著增加0~20 cm土层土壤的水分保持能力,降低果园夏季表层土壤(0~5 cm)温度,有效改善苹果根系生长环境,有利于树体发育。不同生草模式中以黑麦草+白三叶+鸭茅混播处理效果最优。

AIM2炎性小体与胸腔镜下肺叶切除术肿瘤患者单肺通气相关肺损伤的关系及预测价值

目的 评价肺组织AIM2炎性小体与胸腔镜下肺叶切除术肿瘤患者单肺通气相关肺损伤的关系及预测价值。方法 选取2019年9月—2021年12月在保定市第一中心医院和河北大学附属医院择期全麻下拟行胸腔镜下行肺叶切除术的肺癌手术全麻患者750例,术中切除肺叶时取远离病变处>8 cm以上肺组织。采用Western blot法检测肺组织黑色素瘤缺如因子2(AIM2),凋亡相关微粒蛋白(ASC)和半胱天冬酶-1前体(pro-Caspase1)的表达。采用急性肺损伤/急性呼吸窘迫综合征诊断和治疗指南提出的诊断标准判断是否发生单肺通气相关肺损伤。采用Logistic回归分析筛选单肺通气相关肺损伤的危险因素。采用ROC曲线和精确率召回率曲线(PR曲线)预测相关危险因素诊断单肺通气相关肺损伤的准确程度。结果 最终纳入678例胸腔镜下肺癌手术患者。根据患者是否发生术后单肺通气相关肺损伤,将患者分为单肺通气肺损伤组(I组,115例)和单肺通气非肺损伤组(NI组,563例)。术后单肺通气肺损伤发生率是16.9%。I组和NI组相比较,年龄、FEV_(1)/FVC、单肺通气时间、手术时间、AIM2、ASC和pro-Caspase1的差异有统计学意义(P<0.05)。多因素Logistic回归分析结果显示:年龄、FEV_(1)/FVC、单肺通气时间、AIM2、ASC和pro-Caspase1是单肺通气肺损伤的危险因素,并且通过二次敏感性分析结果发现,AIM2、ASC和pro-Caspase1蛋白表达仍是发生术后单肺通气肺损伤独立危险因素。ROC曲线和PR曲线分析显示,AIM2炎性小体预测单肺通气相关肺损伤的发生有较高的准确性。结论 肺组织AIM2炎性小体升高是胸腔镜下肺叶切除术肺癌患者单肺通气相关肺损伤的独立危险因素,且肺组织AIM2炎性小体可准确预测单肺通气相关肺损伤。

碳中和背景下的海洋微生物呼吸速率测定方法研究进展

全球气候变化与人类活动导致的CO_(2)排放息息相关。海洋是净吸收大气CO_(2)的重要环境,因此影响海洋碳存储能力的生物地球化学过程成为研究热点。海洋微生物的呼吸作用是调节碳“源-汇”转换的关键生物过程之一,呼吸速率是海区碳收支研究的重要参照指标。依据不同生物化学原理,海洋领域研发了多种微生物呼吸速率测定方法。依据海洋水文环境和微生物群落等不同应用场景的差异,使得采用一种或多种方法准确测定呼吸速率具有重要意义。文章着重陈述了各种呼吸速率测定的原理、优缺点和适用范围等,系统分析了常规测定方法和前沿测定技术,为碳中和背景下的海洋碳汇关键过程解析提供技术选择的理论支撑。

无创机械通气联合呼吸训练在AECOPD合并呼吸衰竭患者中的应用评价

目的:探讨无创机械通气联合呼吸训练对慢性阻塞性肺疾病急性加重期(AECOPD)合并呼吸衰竭患者的效果。方法:前瞻性纳入2019年2月—2022年2月桂林医学院附属医院急诊科收治的AECOPD合并呼吸衰竭患者共67例,采用随机数字表法将患者分为两组。对照组(n=33)接受间断无创机械通气治疗,观察组(n=34)在对照组基础上增加主动呼吸训练(包括上肢弹力带阻抗训练、缩唇腹式呼吸、呼吸训练器使用)。记录两组2 d内撤机成功率、不良反应发生率,比较两组氧合指数(OI)、动脉血二氧化碳分压(PaCO_(2))、改良版英国医学研究委员会(mMRC)呼吸困难问卷分级、呼吸频率(RR)、自主呼吸潮气量。结果:对照组2 d内撤机成功率为60.6%,观察组为82.4%,观察组的撤机成功率高于对照组(P<0.05);观察组咳痰乏力、呼吸疲劳发生率均低于对照组(P<0.05);与治疗前相比,两组患者治疗2 d后的OI和PaCO_(2)均有显著改善,差异均有统计学意义(P<0.05);治疗2 d后,观察组PaCO_(2)低于对照组(P<0.05),但两组OI比较,差异无统计学意义(P>0.05);与治疗前相比,两组患者治疗2 d后的mMRC呼吸困难问卷分级和RR均有明显下降,自主呼吸潮气量均有明显提升,差异均有统计学意义(P<0.05);治疗2 d后,两组mMRC呼吸困难问卷分级和RR比较,差异均无统计学意义(P>0.05),但观察组患者自主呼吸潮气量明显高于对照组(P<0.05)。结论:AECOPD合并呼吸衰竭患者进行无创机械通气联合呼吸训练,能有效改善呼吸肌疲劳,增加肺通气,提高撤机成功率。