نتایج جستجو برای: مولکول h2
تعداد نتایج: 27881 فیلتر نتایج به سال:
Molecular hydrogen (H2) metabolism in bacteria and algae has been well studied from an industrial perspective because H2 is viewed as a potential future energy source. A number of clinical trials have recently reported that H2 is a therapeutic antioxidant and signaling molecule. Although H2 metabolism in higher plants was reported in some early studies, its biological effects remain unclear. In...
We report measurements of the deuterium content of molecular hydrogen (H2) obtained from a suite of air samples that were collected during a stratospheric balloon flight between 12 and 33 km at 40 N in October 2002. Strong deuterium enrichments of up to 400‰ versus Vienna Standard Mean Ocean Water (VSMOW) are observed, while the H2 mixing ratio remains virtually constant. Thus, as hydrogen is p...
In barley (Hordeum vulgare), PHOTOPERIOD1 (Ppd-H1) acts as a major positive regulator of flowering under long-day conditions, while VERNALIZATION2 (VRN-H2) is a strong repressor of flowering under long days before vernalization. By contrast, CONSTANS (CO) plays a key role in the photoperiodic regulation of flowering in Arabidopsis (Arabidopsis thaliana). Here, we study the role of the closest b...
BACKGROUND Biological fermentation routes can provide an environmentally friendly way of producing H2 since they use renewable biomass as feedstock and proceed under ambient temperature and pressure. In particular, photo-fermentation has superior properties in terms of achieving high H2 yield through complete degradation of substrates. However, long-term H2 production data with stable performan...
Bifunctional EH activation offers a promising approach for the design of two-electron-reduction catalysts with late first-row metals, such as Ni. To this end, we have been pursuing H2 activation reactions at late-metal boratranes and herein describe a diphosphine-borane-supported Ni-(H2 ) complex, [((Ph) DPB(iPr) )Ni(H2 )], which has been characterized in solution. (1) H NMR spectroscopy confi...
We theoretically investigate the ground-state properties of a molecular para-hydrogen (p-H2) film in which crystallization is energetically frustrated by embedding sodium (Na) atoms periodically distributed in a triangular lattice. In order to fully deal with the quantum nature of p-H2 molecules, we employ the diffusion Monte Carlo method and realistic semiempirical pairwise potentials describi...
Microbe-mediated soil uptake is the largest and most uncertain variable in the budget of atmospheric hydrogen (H2 ). The diversity and ecophysiological role of soil microorganisms that can consume low atmospheric abundances of H2 with high-affinity [NiFe]-hydrogenases is unknown. We expanded the library of atmospheric H2 -consuming strains to include four soil Harvard Forest Isolate (HFI) Strep...
To achieve economically competitive biological hydrogen production, it is crucial to consider inexpensive materials such as lignocellulosic substrate residues derived from agroindustrial activities. It is possible to use (1) lignocellulosic materials without any type of pretreatment, (2) lignocellulosic materials after a pretreatment step, and (3) lignocellulosic materials hydrolysates originat...
پورفیرین ها از دسته پروتئینهای مزدوج غیرپپتیدی می باشند که بعلت اهمیت زیست شیمیایی مورد توجه فراوان قرار گرفته اند. ترکیب هیم موجود در خون مهره داران نیز جزو پورفیرین ها می باشد که در اثر اکسیداسیون به ملکول بیلی وردین تبدیل می شود. ملکول بیلی وردین ممکن است درشکلهای تاتومری مختلفی وجود داشته باشد که می تواند در شرایطی مناسب اکسید شده بصورت دایمر مارپیچی درآید. این پروژه از محاسبات نیمه تجربی ا...
دراین کار تحقیقاتی ، فعالیتهای متفاوتی صورت گرفته که بطور خلاصه به شرح زیر می باشند. در قسمت نخست، در فصل دو، هدف اصلی بهبود توصیف اربیتال ملکولی می باشد. در این تحقیق از روش اربیتال گوسینی کروی شناور fsgo استفاده شده است. در قسمت دوم مفهوم مستقر بودن و غیرمستقر بودن اربیتال ملکولی توسط دو روش scf و fsgo بررسی شده است. این قسمت بطور واضح نشان می دهد که روش scf تنها حالت غیر مستق...
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