Photobiological hydrogen production and artificial photosynthesis for clean energy: from bio to nanotechnologies.

Global energy demand is increasing rapidly and due to intensive consumption of different forms of fuels, there are increasing concerns over the reduction in readily available conventional energy resources. Because of the deleterious atmospheric effects of fossil fuels and the uncertainties of future energy supplies, there is a surge of interest to find environmentally friendly alternative energy sources. Hydrogen (H2) has attracted worldwide attention as a secondary energy carrier, since it is the lightest carbon-neutral fuel rich in energy per unit mass and easy to store. Several methods and technologies have been developed for H2 production, but none of them are able to replace the traditional combustion fuel used in automobiles so far. Extensively modified and renovated methods and technologies are required to introduce H2 as an alternative efficient, clean, and cost-effective future fuel. Among several emerging renewable energy technologies, photobiological H2 production by oxygenic photosynthetic microbes such as green algae and cyanobacteria or by artificial photosynthesis has attracted significant interest. In this short review, we summarize the recent progress and challenges in H2-based energy production by means of biological and artificial photosynthesis routes.

Fragments of layered manganese oxide are the real water oxidation catalyst after transformation of molecular precursor on clay.

A binuclear manganese molecular complex [(OH2)(terpy)Mn(µ-O)2Mn(terpy)(OH2)](3+) (1) is the most prominent structural and functional model of the water-oxidizing Mn complex operating in plants and cyanobacteria. Supported on montmorillonite clay and using Ce(IV) as a chemical oxidant, 1 has been reported to be one of the best Mn-based molecular catalysts toward water oxidation. By X-ray absorption spectroscopy and kinetic analysis of the oxygen evolution reaction, we show that [(OH2)(terpy)Mn(µ-O)2Mn(terpy)(OH2)](3+) is transformed into layered type Mn-oxide particles which are the actual water oxidation catalyst.

Nano-sized manganese-calcium cluster in photosystem II.

Cyanobacteria, algae, and plants are the manufacturers that release O2 via water oxidation during photosynthesis. Since fossil resources are running out, researchers are now actively trying to use the natural catalytic center of water oxidation found in the photosystem II (PS II) reaction center of oxygenic photosynthetic organisms to synthesize a biomimetic supercatalyst for water oxidation. Success in this area of research will transcend the current bottleneck for the development of energy-conversion schemes based on sunlight. In this review, we go over the structure and function of the water-oxidizing complex (WOC) found in Nature by focusing on the recent advances made by the international research community dedicated to achieve the goal of artificial water splitting based on the WOC of PS II.

Calcium manganese oxides as oxygen evolution catalysts: O2 formation pathways indicated by 18O-labelling studies.

Oxygen evolution catalysed by calcium manganese and manganese-only oxides was studied in (18)O-enriched water. Using membrane-inlet mass spectrometry, we monitored the formation of the different O(2) isotopologues (16)O(2), (16)O(18)O and (18)O(2) in such reactions simultaneously with good time resolution. From the analysis of the data, we conclude that entirely different pathways of dioxygen formation catalysis exist for reactions involving hydrogen peroxide (H(2)O(2)), hydrogen persulfate (HSO(5)(-)) or single-electron oxidants such as Ce(IV) and [Ru(III) (bipy)(3)](3+) . Like the studied oxide catalysts, the active sites of manganese catalase and the oxygen-evolving complex (OEC) of photosystem II (PSII) consist of µ-oxido manganese or µ-oxido calcium manganese sites. The studied processes show very similar (18)O-labelling behaviour to the natural enzymes and are therefore interesting model systems for in vivo oxygen formation by manganese metalloenzymes such as PSII.

A possible evolutionary origin for the Mn4 cluster in photosystem II: from manganese superoxide dismutase to oxygen evolving complex.

The recently published X-ray absorption fine structure of photosystem II provides a more detailed architecture of the oxygen-evolving complex (OEC) and the surrounding amino acids. In this paper, a comparison between manganese superoxide dismutase, dinuclear manganese catalase enzymes and the oxygen evolving complex in photosystem II is reported. The author suggests that the development of oxygenic photosynthesis occurred in steps, the first of which involved only one manganese ion (Mn(II)) that oxidized two water molecules to hydrogen peroxide and then oxygen.

4,4'-Bipyridine-butane-1,2,3,4-tetra-carboxylic acid (1/1).

The title compound, C(10)H(8)N(2)·C(8)H(10)O(8), is an example of a system with a short O⋯H⋯N hydrogen bond [O⋯N = 2.565 (3) Å]. The crystal structure comprises a 1:1 adduct between 4,4'-bipyridine and butane-1,2,3,4-tetra-carboxylic acid, where both components are centrosymmetric. The component mol-ecules are linked through strong O⋯H⋯N hydrogen bonds, forming chains extending approximately along [11]. The chains are inter-connected by O⋯H⋯O hydrogen bonds and weak stacking inter-actions involving the pyridyl rings of the 4,4'-bipyridine mol-ecules [centroid-centroid distance = 3.73 (2) Šand inter-planar distance = 3.35 (1) Å]. The H atom of the short O⋯H⋯N hydrogen bond is disordered over two positions with site occupancy factors of ca 0.6 and 0.4. One methylene group is disordered over two positions; the site occupancy factors are ca 0.9 and 0.1.

Bis(guanidinium) trans-diaqua-bis(malonato-κO,O')cobaltate(II).

In the title compound, (CH(6)N(3))(2)[Co(C(3)H(2)O(4))(2)(H(2)O)(2)], the anions lie on crystallographic centres of inversion. The crystal structure adopts a layered structure, stabilized by an extensive network of N-H⋯O and O-H⋯O hydrogen bonds. One H atom of the guanidinium cation does not participate in any strong hydrogen bonds.

The Effect of Prednisolone on miR 15a and miR16-1 Expression Levels and Apoptosis in Acute Lymphoblastic Leukemia Cell Line: CCRF-CEM.

BACKGROUND: Glucocorticoids are probably the most important drugs in the treatment of childhood acute lymphoblastic leukemia (ALL). Prednisolone exerts its effect by induce apoptosis in lymphoid lineage cells. Micro RNAs are 18-24 nucleotides RNA implicated in the control of essential biological functions, including apoptosis. In the following study, the effect of prednisolone on the expression of miR 15a & miR16-1 and apoptosis in the CCRF-CEM cell line is investigated. METHODS: The cell line of CCRF-CEM was cultured in standard conditions. The changes in the miR 15a and miR 16-1 expression levels were determined by Real Time-PCR technique. Also, the apoptosis is evaluated by flow cytometry using Annexin V and PI staining. RESULTS: This study revealed that, the prednisolone induced apoptosis in a time dependent manner. Prednisolone in concentration of 700 µM was significantly increased the expression of miR 16-1 and miR 15a after 24 h and 48 h treatment (p<0.05). CONCLUSION: prednisolone-induced apoptosis might be mediated by up-regulation of these 2 miRNAs in CCRF-CEM cells.

Platelet-rich plasma in the treatment of subcutaneous venous access device scars: a head-to-head patient survey.

INTRODUCTION: Platelet-rich plasma (PRP) is a product widely used in sports medicine, tissue repair, and general surgery. A recent meta-analysis showed this product to be beneficial when introduced into a wound area, be it intra-articular (i.e., joint-injections) or direct introduction onto the wound surface. METHODS: Between the years of 2012 and 2014 a questionnaire evaluating surgical outcome after port (venous access device) removal was answered by 100 patients in the control group and 20 patients in a PRP group, leading to a total of 120 patients in this single center, retrospective, subjective outcome evaluation. RESULTS: No statistical difference was shown in postsurgical complication rates, postsurgical pain, decreased mobility, and overall quality of life. A significant difference was shown in overall patient satisfaction and the desire to further improve port area scarring. Results differed significantly in favor of the PRP group. Interestingly, approximately 40.2% of patients are dissatisfied with the surgical outcome after port removal in the control group. This result, though surprising, may be improved to 10% dissatisfaction when a PRP product is used. CONCLUSION: PRP products such as Arthrex ACP are safe to use and present an additional option in improving surgical outcome.

Synthesis, characterization, DFT studies and catalytic activities of manganese(II) complex with 1,4-bis(2,2':6,2''-terpyridin-4'-yl) benzene.

A new di-manganese complex with "back-to-back" 1,4-bis(2,2':6,2''-terpyridin-4'-yl) benzene ligation has been synthesized and characterised by a variety of techniques. The back-to-back ligation presents a novel new mononuclear manganese catalytic centre that functions as a heterogeneous catalysis for the evolution of oxygen in the presence of an exogenous oxidant. We discuss the synthesis and spectroscopic characterizations of this complex and propose a mechanism for oxygen evolution activity of the compound in the presence of oxone. The di-manganese complex also shows efficient and selective catalytic oxidation of sulfides in the presence of H(2)O(2). Density functional theory calculations were used to assess the structural optimization of the complex and a proposed reaction pathway with oxone. The calculations show that middle benzene ring is distorted respect to both of metallic centers, and this in turn leads to negligible resonance of electrons between two sides of complex. The calculations also indicate the unpaired electron located on oxyl-ligand emphasizes the radical mechanism of water oxidation for the system.