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31.
Fungal biogeochemical activity over a long-term scale may have negative environmental consequences for the management of barrier materials used in nuclear waste disposal. Fungal deterioration of barrier concrete was studied in microcosms simulating a heterogeneous environment with an external source of nutrients for the fungi. Fungi successfully colonized barrier concrete, generally avoiding granite aggregates, and biochemically (by excretion of protons and ligands) and biomechanically deteriorated the concrete. Fungi dissolved the cement matrix leaching structural elements and accumulating them within the fungal biofilm and associated microenvironment. Oxalate-excreting Aspergillus niger formed abundant calcium oxalate crystals on the concrete and encrusting fungal hyphae.  相似文献   
32.
利用一株分离自传统发酵酸马奶中的益生干酪乳杆菌(Lactobacillus casei Zhang)进行固态发酵(Solid State Fermentation,SSF)。以发酵物中的活菌数为主要指标,采用九因素四水平(L32(4^9))的正交试验优化固态发酵培养基,并在优化的培养基基础上研究不同的初始含水量及培养时间对Lactobacillus casei Zhang活菌数的影响。实验结果表明,在固态发酵培养基组成为4g豆粕、5g麸皮、0.6g乳清粉、0.3g葡萄糖、0.3g碳酸钙、0.02g硫酸铵、0.01g硫酸镁,初始含水量为55%的优化条件下,37℃发酵60h,发酵物中Lactobacillus casei Zhang活菌数可达到4.08×10^10CFU/g。  相似文献   
33.
Connexins had been considered to be the only class of the vertebrate proteins capable of gap junction formation; however, new candidates for this function with no homology to connexins, termed pannexins were discovered. So far three pannexins were described in rodent and human genomes: Panx1, Panx2 and Panx3. Expressions of pannexins can be detected in numerous brain structures, and now found both in neuronal and glial cells. Hypothetical roles of pannexins in the nervous system include participating in sensory processing, hippocampal plasticity, synchronization between hippocampus and cortex, and propagation of the calcium waves supported by glial cells, which help maintain and modulate neuronal metabolism. Pannexin also may participate in pathological reactions of the neural cells, including their damage after ischemia and subsequent cell death. Recent study revealed non-gap junction function of Panx1 hemichannels in erythrocytes, where they serve as the conduits for the ATP release in response to the osmotic stress. High-throughput studies produced some evidences of the pannexin involvement in the process of tumorigenesis. According to brain cancer gene expression database REMBRANDT, PANX2 expression levels can predict post diagnosis survival for patients with glial tumors. Further investigations are needed to verify or reject hypotheses listed.  相似文献   
34.
基于农业生态服务价值的农业绿色GDP核算——以安塞县为例   总被引:23,自引:0,他引:23  
陈源泉  高旺盛 《生态学报》2007,27(1):250-259
将传统GDP绿色化,也就是“绿色GDP”是国民经济核算研究和探索的热点。从微观层面对农业生产进行绿色GDP核算,认为农业绿色GDP不仅包含传统的产品价值,还应包括农业对人类社会经济系统的生态服务价值,并以基于生态系统服务价值的“农业绿色GDP=农业常规GDP+农业生态GDP”的公式核算了安塞县的绿色GDP。结果表明:(1)安塞县2000年的农业生产总值为29187万元,减去中间消耗为18972万元;(2)若考虑农业生态环境代价,则农业生产产值仅为6272.30万元,是农业常规GDP的33.06%,农业常规GDP背后至少隐含着66.94%的农业生态环境代价;(3)应用市场价值法、机会成本法、替代工程法、影子价格法等核算农业生态系统服务价值结果为504218.37万元,把农业生态系统服务价值作为农业系统的间接产出,则该县2000年的农业绿色GDP为510490.67万元。安塞县农业经济的获得背后至少有66.94%生态环境代价是依靠其农业生态系统的服务来提供和补偿的。  相似文献   
35.
摘要 目的:探讨不同剂量艾司氯胺酮对腹腔镜全子宫切除术患者术后疼痛和情绪状态的影响。方法:按照随机数表法,选择2022年1月至2023年4月我院行腹腔镜全子宫切除术患者120例分为对照组(A组,n=40)、艾司氯胺酮0.25 mg/kg组(B组,n=40)、艾司氯胺酮0.5 mg/kg组(C组,n=40)。比较三组组围术期指标、术后1、4、8、24 h和48 h的疼痛评定数字量表(NRS)评分及术前1天(PRE1)、术后第1天(POD1)、术后第2天(POD2)的焦虑自评量表(SAS)评分、抑郁自评量表(SDS)评分、血流动力学指标及不良反应。结果:B组和C组术后24 h舒芬太尼镇痛药物用量、补救镇痛例数小于A组,A组、B组苏醒时间、拔管时间短于C组(P<0.05)。B组、C组术后1 h的NRS评分低于A组(P<0.05),B组术后4 h、8 h、24 h的NRS评分低于A组,术后4 h、8 h的NRS评分低于C组(P<0.05)。与组内PRE1相比,三组POD1的SAS、SDS评分均升高(P<0.05)。B组、C组POD1、POD2的SAS、SDS评分均低于A组,且C组低于B组(P<0.05)。与组内PRE1相比,A组POD2的SAS、SDS评分升高(P<0.05)。与组内PRE1相比,B组POD2的SDS与C组POD2的SAS、SDS均降低(P<0.05)。在T3时刻,B组和C组的平均动脉压(MAP)、心率(HR)低于A组(P<0.05)。B组和C组术后恶心呕吐发生率低于A组(P<0.05);A组和B组术后头晕、苏醒延迟的发生率低于C组(P<0.05);三组术后苏醒期躁动和呼吸抑制的差异无统计学意义(P>0.05)。结论:0.25 mg/kg的艾司氯胺酮对减轻腹腔镜全子宫切除术患者术后疼痛,减少阿片类药物用量,改善负面情绪的临床效果更佳。  相似文献   
36.
The recent cloning of the special calcium channels TRPV5 and TRPV6 (transient receptor potential vanilloid channels) has provided a molecular basis for studying previously unidentified calcium influx channels in electrically nonexcitable cells. In the present work using RT-PCR, we obtained the endogenous expression of mRNAs of genes trpv5 and trpv6 in lymphoblast leukemia Jurkat cells and in normal human T lymphocytes. Additionally, by immunoblotting, the presence of the channel-forming TRPV5 proteins has been shown both in the total lysate and in crude membrane fractions from Jurkat cells and normal T lymphocytes. The use of immunoprecipitation revealed TRPV6 proteins in Jurkat cells, whereas in normal T lymphocytes, this protein was not detected. The expression pattern and the selective Ca2+ permeation properties of TRPV5 and TRPV6 channels indicate the important role of these channels in Ca2+ homeostasis, as well as most likely in malignant transformation of blood cells.  相似文献   
37.
38.
Phagocytosis by neutrophils, macrophages, and other professional phagocytes requires rapid remodeling of actin. Early phagosomes are surrounded by a rim of F-actin that is disassembled during phagosomoal maturation. Breakdown of periphagosomal F-actin and phagolysosome fusion are calcium dependent processes in neutrophils interacting with serum-opsonized prey, but appears to be calcium independent in macrophages interacting with serum- or IgG-opsonized prey. In the present study, we found that calcium was necessary for phagocytosis, breakdown of periphagosomal F-actin, and phagosomal maturation in J774 macrophages interacting with unopsonized prey. We also observed that lipophosphoglycan (LPG) from Leishmania donovani promastigotes required calcium to exert its inhibitory effect on macrophage phagocytosis and periphagosomal F-actin breakdown. We conclude that calcium is essential for phagocytosis, depolymerization of periphagosomal F-actin, and phagosomal maturation in J774 macrophages interacting with unopsonized prey, as well as for proper functioning of LPG.  相似文献   
39.
Salinomycin is a polyether antibiotic with properties of an ionophore, which is commonly used as cocciodiostatic drug and has been shown to be highly effective in the elimination of cancer stem cells (CSCs) both in vitro and in vivo. One important caveat for the potential clinical application of salinomycin is its marked neural and muscular toxicity. In the present study we show that salinomycin in concentrations effective against CSCs exerts profound toxicity towards both dorsal root ganglia as well as Schwann cells. This toxic effect is mediated by elevated cytosolic Na+ concentrations, which in turn cause an increase of cytosolic Ca2+ by means of Na+/Ca2+ exchangers (NCXs) in the plasma membrane as well as the mitochondria. Elevated Ca2+ then leads to calpain activation, which triggers caspase-dependent apoptosis involving caspases 12, 9 and 3. In addition, cytochrome c released from depolarized mitochondria directly activates caspase 9. Combined inhibition of calpain and the mitochondrial NCXs resulted in significantly decreased cytotoxicity and was comparable to caspase 3 inhibition. These findings improve our understanding of mechanisms involved in the pathogenesis of peripheral neuropathy and are important to devise strategies for the prevention of neurotoxic side effects induced by salinomycin.  相似文献   
40.
Biosorption is a surface-dependent phenomenon. Surface modifications by chemical treatment methods could either improve or reduce the biosorption capacity of potential biosorbents. In the present work, pristine Pteris vittata L. pinnae (PPV) powder was treated separately with sodium hydroxide (NaOH), calcium chloride (CaCl2), and nitric acid (HNO3). The pristine and treated biosorbents were used to assess the biosorption of Pb(II), Cd(II), and Cr(VI) as a function of pH. Kinetics and adsorption isotherms were studied. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy and scanning electron microscope combined with energy dispersive x-ray (SEM-EDX) spectroscopic techniques were used to characterize the biosorbents before and after chemical treatments. The possible functional groups contributing to the metal sorption were identified. Results revealed favorable biosorption of Pb(II), Cd(II), and Cr(VI) described by pseudo-second order kinetics. NaOH-treated P. vittata (NPV) showed higher biosorption capacity for Pb(II) and Cd(II) compared to that of PPV. ATR-FTIR studies indicated that -OH, -COOH, and -NH2 groups were mainly involved in Cr(VI) and -OH in Pb(II) and Cd(II) biosorption. The enhanced efficiency of NPV and CaCl2 treated P. vittata (CPV) in the uptake of Pb(II) and Cd(II) compared to PPV can be associated with their altered physicochemical characters.  相似文献   
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