黄丘区特色治理开发小流域土壤侵蚀变化对景观格局演变的响应

研究土壤侵蚀与景观格局变化的关系对小流域的治理开发具有重要的指导意义。本研究以实施退耕还林草、生态农业、生态旅游及科技示范的黄土高原安塞南沟特色治理小流域为研究对象,基于GIS平台和通用土壤流失方程,分析小流域1981—2018年景观格局和土壤侵蚀量的时空演化特征,并利用主成分回归法,从斑块类型水平和景观水平两个尺度分析土壤侵蚀模数与3类9个景观格局指标的关系。结果表明: 研究期间,在5种景观类型中,耕地和林地面积的时空变化主导了南沟小流域景观格局的演化,并且影响整个小流域的聚集分散程度;南沟小流域的土壤侵蚀量逐年减少,1981—2018年土壤侵蚀面积减少29.7%,侵蚀模数减少61.2%,且有73.4%的区域土壤侵蚀强度减轻;耕地和林地面积的变化决定了整个小流域土壤侵蚀模数的变化,其景观格局指数的变化方向与该景观类型土壤侵蚀的变化方向一致;退耕还林草工程是流域景观格局变化、土壤侵蚀减轻的主要原因,特色开发治理可以减弱局部地区土壤侵蚀强度。景观类型的合理化配置能有效地防治小流域土壤侵蚀,将其与特色治理开发相结合有助于实现小流域可持续高质量发展。     

无创性皮肤屏障功能检测在朗格汉斯细胞组织细胞增生症中的应用

摘要 目的：探讨无创性皮肤屏障功能检测在朗格汉斯细胞组织细胞增生症(Langerhans cell histiocytosis,LCH)中的应用价值。方法：研究时间为2017年1月到2020年12月,选择在本院诊治的朗格汉斯细胞组织细胞增多症患者72例作为LCH组,同期选择健康体检者72例作为对照组。采用无创性皮肤屏障功能检测皮肤水分、经皮水分丢失(Transdermal water loss,TEWL)、油脂水平,同时检测所有入选者的免疫功能、皮肤菌群并进行相关性分析。结果：LCH组的皮肤水分低于对照组(P<0.05),TEWL、油脂水平高于对照组(P<0.05)。LCH组的乳酸杆菌(La)阳性率低于对照组(P<0.05),表皮葡萄球菌(Se)、痤疮丙酸杆菌(Pa)、金黄色葡萄球菌(Sa)阳性率高于对照组(P<0.05)。LCH组的CD163、ki-67表达阳性率分别为77.8 %、52.8 %,高于对照组的19.4 %和6.9 %(P<0.05)。在LCH组中,Pearson相关性分析显示皮肤水分与乳酸杆菌呈现正相关性(P<0.05),TEWL、油脂与表皮葡萄球菌、痤疮丙酸杆菌、金黄色葡萄球菌、CD163、ki-67呈现正相关性(P<0.05)。结论：无创性皮肤屏障功能检测在朗格汉斯细胞组织细胞增生症中的应用可反映患者的皮肤水分与油脂状况,也可间接反映患者的皮肤微生态与免疫功能状况。     

Interaction between eggshell temperature and carbon dioxide concentration after day 8 of incubation on broiler chicken embryo development

Carbon dioxide (CO₂) is considered to be an important factor during incubation of eggs. Effects attributed to higher CO₂ concentrations during experiment might be due to confounding effects of other environmental conditions, such as incubation temperature. To disentangle effects of eggshell temperature (EST) and CO₂ concentration, an experiment was conducted. A total of 630 Cobb 500 hatching eggs from 37 to 45 wk commercial breeder flocks were collected and incubated according to treatments. The experiment was setup as a complete randomized 2 × 3 factorial design, resulting in 6 treatments. From day 8 of incubation onward, broiler eggs were exposed to one of two EST (37.8 or 38.9 °C) and one of three CO₂ concentrations (0.1, 0.4 or 0.8%). Eggs were incubated in climate-respiration chambers and metabolic heat production was determined continuously. At day 18 of incubation and at 6 h after hatching, embryo and chicken quality were determined by evaluation of organ weights, navel condition, blood metabolites and hepatic glycogen. Hatching time and chicken length at 6 h after hatching showed an interaction between EST and CO₂ concentration (both P = 0.001). Furthermore, no effect of CO₂ concentration was found on embryo development or chicken quality. Metabolic heat production between day 8 and 18 of incubation was not affected by either EST or CO₂. At day 18 of incubation, an EST of 38.9 °C resulted in a higher egg weight loss, longer embryos, higher yolk free body mass (YFBM) and lower heart weight than an EST of 37.8 °C (all P < 0.008). At 6 h after hatching, an EST of 38.9 °C resulted in a higher residual yolk weight and lower YFBM, liver weight and heart weight than an EST of 37.8 °C (all P < 0.003). Lactate, uric acid and hepatic glycogen were not affected by EST at either day 18 of incubation or at hatch. Glucose was not affected by EST at day 18 of incubation, but at hatch, it was higher at an EST of 37.8 °C than at an EST of 38.9 °C (P = 0.02). It can be concluded that effects of CO₂ concentration (at concentrations ≤0.8%) on embryonic development and chicken quality appear to be limited when EST is maintained at a constant level. Moreover, a higher EST from day 8 of incubation onward appears to negatively affect chicken quality at hatch.     

生态系统多功能性的指标选择与驱动因子: 研究现状与展望

全球变化和人类活动正以空前的速度在世界范围内改变着生物多样性, 这导致了全球生物多样性的锐减以及生产力的下降、病虫害的增加和抗入侵能力的减弱等生态问题。近30年来, 生态学家开始对于生物多样性的持续丧失是否以及如何影响生态系统功能的问题越来越感兴趣, 生物多样性与生态系统功能(biodiversity and ecosystem functioning, BEF)关系的研究应运而生, 并成为生态学研究的热点之一。但长期以来, 研究者更多地关注单一生态系统功能, 而忽略了生态系统能够同时提供多种生态系统功能的能力, 即生态系统多功能性(ecosystem multifunctionality, EMF)。本文综述了EMF研究中功能指标的选择、生物多样性的不同维度、微生物多样性对EMF的影响以及其他非生物因子对EMF的驱动等进展。因只考虑单一功能可能会低估生物多样性对整体生态系统功能的影响, 故生物多样性与生态系统多功能性(BEMF)关系的研究成为BEF关系研究的重点。近年来, BEMF关系的研究发展较快, 在不同生态系统(包括水生、草地、森林、旱地、农业等)、不同研究尺度(从区域到全球尺度)、BEMF关系的驱动机制(从单一驱动机制到多种驱动机制共同作用)、研究方法(包括新概念以及新的量化方法的提出和应用)等方面均取得了新的进展。但仍有不足之处, 如对于EMF研究中功能指标的选取没有统一的标准、对地下微生物多样性的关注度不够、涉及多营养级水平下的BEMF关系研究较少、驱动EMF的机制仍存在争论等。未来应加强对于功能指标选取的标准研究, 综合分析地上、地下生物多样性以及非生物因子对EMF的整体影响, 加强生态系统多服务性(ecosystem multiserviceability, EMS)方法的研究和应用。     

Is there any relationship between decreased AgNOR protein synthesis and human hair loss?

Argyrophilic nucleolar organizing region associated proteins (AgNORs) play roles in cell proliferation and a variety of diseases. We attempted to determine whether decreased NOR protein synthesis causes human hair loss. We studied 21 healthy males who suffered hair loss on the frontal/vertex portion of the head. Hair root cells from normal and hair loss sites were stained for AgNOR. One hundred nuclei per site were evaluated and the AgNOR number and NORa/TNa proportions of individual cells were determined using a computer program. The cells from normal sites had significantly higher AgNOR counts than those from hair loss sites. Also, the cells from the normal sites had significantly higher NORa/TNa than cells from the hair loss sites. In the normal sites, the cells demonstrated more NOR protein synthesis than cells in hair loss sites. Therefore, decreased NOR protein synthesis appears to be related to hair loss in humans.     

Stain Solubilities Part III

Ethylenediaminetetraacetic acid (EDTA) solution is used to decalcify bone specimens for histological examination. Sodium hydroxide (NaOH) has been used to dissolve EDTA and to bring EDTA solutions to neutral pH. This solution, however, requires several weeks to decalcify bone specimens. We investigated a new de-calcification fluid using concentrated ammonium hydroxide (NH₄OH) to dissolve EDTA and to adjust the pH to neutral. Decalcification was performed using a magnetic stirrer with and without vacuum, or with a sonic cleaner. Decalcification end point was confirmed using both the weight loss and X-ray methods. After decalcification, specimens were processed through paraffin and sections were stained with hematoxylin and eosin. Decalcification employing NH₄OH required an average of six days. Light microscopy indicated good retention of cellular detail.     

Influence of steam and dry heat pretreatment on fibre properties and cellulase degradation of cellulosic fibres

Cellulosic fabric samples of cotton, viscose, lyocell and modal were pretreated with steam and dry heat in the range of 100–190°C. The samples were then treated with a Trichoderma reesei cellulase preparation (total culture filtrate – TC), with mechanical agitation, at a high enzyme dosage of 75% by weight of fabric, for 8 hours. Generally, viscose proved to be easily degradable, followed by cotton and modal. The degree of hydrolysis was the least for Lyocell. Dry heat pretreatments exerted a lower influence on degradation rate than steam pretreatments which showed a distinct maximum at a steam temperature of 130°C. The hydrolysis rate varied strongly depending on treatment conditions and fibre type. Water retention values in treated substrates were changed by up to 20% of initial values.     

Finite element analysis of peri-implant bone volume affected by stresses around Morse taper implants: effects of implant positioning to the bone crest

Abstract

Objectives: The purpose of the present study was to evaluate the distribution and magnitude of stresses through the bone tissue surrounding Morse taper dental implants at different positioning relative to the bone crest. Materials and Methods: A mandibular bone model was obtained from a computed tomography scan. A three-dimensional (3D) model of Morse taper implant-abutment systems placed at the bone crest (equicrestal) and 2?mm bellow the bone crest (subcrestal) were assessed by finite element analysis (FEA). FEA was carried out on axial and oblique (45°) loading at 150 N relatively to the central axis of the implant. The von Mises stresses were analysed considering magnitude and volume of affected peri-implant bone. Results: On vertical loading, maximum von Mises stresses were recorded at 6-7?MPa for trabecular bone while values ranging from 73 up to 118?MPa were recorded for cortical bone. On oblique loading at the equiquestral or subcrestal positioning, the maximum von Mises stresses ranged from 15 to 21?MPa for trabecular bone while values at 150?MPa were recorded for the cortical bone. On vertical loading, >99.9vol.% cortical bone volume was subjected to a maximum of 2?MPa while von Mises stress values at 15?MPa were recorded for trabecular bone. On oblique loading, >99.9vol.% trabecular bone volume was subjected to maximum stress values at 5?MPa, while von Mises stress values at 35?MPa were recorded for >99.4vol.% cortical bone. Conclusions: Bone volume-based stress analysis revealed that most of the bone volume (>99% by vol) was subjected to significantly lower stress values around Morse taper implants placed at equicrestal or subcrestal positioning. Such analysis is commentary to the ordinary biomechanical assessment of dental implants concerning the stress distribution through peri-implant sites.     

Effect of environmental conditions on decomposition in eight woody species of a dry tropical forest

Litter decay is a significant part of carbon budget. Due to strong environmental control, the changes in the environment may drastically influence the litter decay rates. Litter decomposition of eight dry tropical woody species, viz. Shorea robusta, Buchanania lanzan, Diospyros melanoxylon, Lagerstroemia parviflora, Lannea coromandelica, Terminalia tomentosa, Holarrhena antidysenterica and Lantana camara was studied to document the effect of intra-annual changes in the environment. Litter decomposition was monitored at monthly intervals at five sites using litter bag technique over an annual cycle in a dry tropical deciduous forest of Vindhyan highland, India. Weight loss differed among species and through months, and ranged from 15.38% in L. camara at Kotwa site in January to 30.72% in T. tomentosa at Hathinala site in August. Peak weight loss occurred in August and averaged 46.2% across species and sites. Nitrogen and phosphorus mineralization rates also varied significantly from species to species. T. tomentosa having higher nitrogen content and lower C/N ratio than other species exhibited faster weight loss. Nitrogen and phosphorus contents of litter showed significant positive correlation with weight loss. C/N ratio was negatively related to decay constant, and the weight loss was positively related to the soil surface temperature as well as soil moisture content.     

Plant diversity does not buffer drought effects on early‐stage litter mass loss rates and microbial properties

Human activities are decreasing biodiversity and changing the climate worldwide. Both global change drivers have been shown to affect ecosystem functioning, but they may also act in concert in a non‐additive way. We studied early‐stage litter mass loss rates and soil microbial properties (basal respiration and microbial biomass) during the summer season in response to plant species richness and summer drought in a large grassland biodiversity experiment, the Jena Experiment, Germany. In line with our expectations, decreasing plant diversity and summer drought decreased litter mass loss rates and soil microbial properties. In contrast to our hypotheses, however, this was only true for mass loss of standard litter (wheat straw) used in all plots, and not for plant community‐specific litter mass loss. We found no interactive effects between global change drivers, that is, drought reduced litter mass loss rates and soil microbial properties irrespective of plant diversity. High mass loss rates of plant community‐specific litter and low responsiveness to drought relative to the standard litter indicate that soil microbial communities were adapted to decomposing community‐specific plant litter material including lower susceptibility to dry conditions during summer months. Moreover, higher microbial enzymatic diversity at high plant diversity may have caused elevated mass loss of standard litter. Our results indicate that plant diversity loss and summer drought independently impede soil processes. However, soil decomposer communities may be highly adapted to decomposing plant community‐specific litter material, even in situations of environmental stress. Results of standard litter mass loss moreover suggest that decomposer communities under diverse plant communities are able to cope with a greater variety of plant inputs possibly making them less responsive to biotic changes.