Coupling of nuclear wavepacket motion and charge separation in bacterial reaction centers

AbstractThe mechanism of the charge separation and stabilization of separated charges was studied using the femtosecond absorption spectroscopy. It was found that nuclear wavepacket motions on potential energy surface of the excited state of the primary electron donor P* leads to a coherent formation of the charge separated states P+BA−, P+HA− and P+HB− (where BA, HB and HA are the primary and secondary electron acceptors, respectively) in native, pheophytin-modified and mutant reaction centers (RCs) of Rhodobacter sphaeroides R-26 and in Chloroflexus aurantiacus RCs. The processes were studied by measurements of coherent oscillations in kinetics at 890 and 935 nm (the stimulated emission bands of P*), at 800 nm (the absorption band of BA) and at 1020 nm (the absorption band of BA−) as well as at 760 nm (the absorption band of HA) and at 750 nm (the absorption band of HB). It was found that wavepacket motion on the 130–150 cm−1 potential surface of P* is accompanied by approaches to the intercrossing region between P* and P+BA− surfaces at 120 and 380 fs delays emitting light at 935 nm (P*) and absorbing light at 1020 nm (P+BA−). In the presence of Tyr M210 (Rb. sphaeroides) or M195 (C. aurantiacus) the stabilization of P+BA− is observed within a few picosseconds in contrast to YM210W. At even earlier delay (∼40 fs) the emission at 895 nm and bleaching at 748 nm are observed in C. aurantiacus RCs showing the wavepacket approach to the intercrossing between the P* and P+HB− surfaces at that time. The 32 cm−1 rotation mode of HOH was found to modulate the electron transfer rate probably due to including of this molecule in polar chain connecting PB and BA and participating in the charge separation. The mechanism of the charge separation and stabilization of separated charges is discussed in terms of the role of nuclear motions, of polar groups connecting P and acceptors and of proton of OH group of TyrM210

Modeling of spacecraft interaction with environment

At ITM (NASU and NSAU) investigations of various aspects, processes and phenomena related to spacecraft environment interactions are carried out in plasma electrodynamic facilities. The results presented illustrate the efficiency of physical modeling to solve the problems formulated.В ИТМ НАНУ и НКАУ на плазмодинамическом стенде проводятся исследования различных процессов и явлений, характеризующих взаимодействие КА с околоспутниковой средой. Представленные результаты демонстрируют эффективность физического моделирования для решения поставленных задач

Formation of a Long-Lived P Ba-State in Plant Pheophytin-Exchanged Reaction Centers of Rhodobacter sphaeroides R26 at Low Temperature

Femtosecond transient absorption spectroscopy in the range of 500-1040 nm was used to study electron transfer at 5 K in reaction centers of Rhodobacter sphaeroides R26 in which the bacteriopheophytins (BPhe) were replaced by plant pheophytin a (Phe). Primary charge separation took place with a time constant of 1.6 ps, similar to that found in native RCs. Spectral changes around 1020 nm indicated the formation of reduced bacteriochlorophyll (BChl) with the same time constant, and its subsequent decay in 620 ps. This observation identifies the accessory BChl as the primary electron acceptor. No evidence was found for electron transfer to Phe, indicating that electron transfer from B(A

Physical research of microgravity influence on physical phenomenon in cryogenic liquids and general-purpose onboard cryogenic facility for realization of this researchaboard International Space Station

The united research plan named "Boiling" is created on the basis of several cryogenic research projects developed by experts in Russia and Ukraine for International Space Station. The "Boiling" plan includes 8 first experiments aimed at investigating the influence of microgravity on boiling processes, heat transfer and hydrodynamics in liquid helium being either under normal or superfluid conditions. The experiments are supposed to be carried out with individual cells collected inside a single cryogenic onboard experimental facility. The international research program experiments are characterized by the following features: utilization of several artificially simulated microgravity levels, owing to rotation of the experimental helium cryostat; visualization of the processes that occur in liquid helium; research of boiling and hydrodynamics both in a large volume of stationary liquid, and in a liquid flow running through a channel. Upon completion of the "Boiling" research plan, the cryogenic onboard facility created for International Space Station would be able to find its application in further scientific and experimental researches with helium

国际化十年：一家澳大利亚零售银行的经验之谈

上个世纪最后四十年见证了国际银行业务和跨国银行业务显著增长的历程。推动这一发展的力量包括全球化、解除管制以及信息技术的发展。在19世纪及20世纪初发生的第一次现代意义上的跨国银行业务发展浪潮中，那些来自殖民宗主国的银行领导了时代潮流。而在最近的这次跨国银行业务扩张中，美国的金融机构占据了领导地位，这是与第一次明显不同的。因此，许多学术文章都着重研究美国的银行，包括他们的动机、经营战略以及国际化经验。此外，与银行业国际化的第一阶段相比，此次银行业的国际化扩张更大程度地突出了批发和机构银行业务，而不是零售银行业务（除了少数例外）。这一特点在近年来对跨国银行经营的学术研究中也体现得十分明显[ 有关调查，见Bain,et al (2001)。]。译者单位：厦门大学经济学院国际经济与贸易系（361005

Low temperature photochemistry and spectral properties of a photosystem 2 reaction center complex containing the proteins D1 and D2 and two hemes of Cyt b-559

AbstractA D1/D2/Cyt b-559 complex isolated from spinach chloroplasts contained 4 chlorophylls, 2 pheophytins and 2 hemes of Cyt b-559 with different redox potentials measured to be +70 mV(LP) (pH 7.2) and about −500 mV (XLP). Prereduced Cyt(LP) is photooxidized at 77 K due to the interaction with the state P680+ Ph − which produces the accumulation of Cyt+ P680 Ph−. Another Ph molecule is reduced with a midpoint potential of −450 mV and can interact with Cyt (XLP) forming a second electron transfer chain