Electronic excitation transport in photosynthesis and crystal and molecular structures of porphyrin compounds

The excitation energy transfer in three photosynthetic organism samples, Bacteriochlorophyll a-protein from Prosthecochloris aestuarii, and Chl/P700~60 and Chl/P700~200 from spinach, have been investigated by pump-probe ultrafast spectroscopy. The isotropic photobleaching profiles were best described by two exponential decay components in Bchl a-protein and Chl/P700~60, and three exponential decay components in Chl/P700~200. The experimental results from the three samples show that nonrandom chromophore orientations exist and Sauer\u27s pebble mosaic model is an appropriate one for excitation transfer in these samples. The polarized pump-probe transients have been analyzed in terms of an exciton hopping model that incorporates the known geometry of the Bchl a-protein;The crystal and molecular structures of four metalloporphyrins have been determined by X-ray diffraction and molecular mechanics. The results are summarized as follows: (H[subscript]2O)MgT(OME)PP.HCCl[subscript]3: monoclinic, a = 15.966(5), b = 9.192(1), c = 14.882(4) A, and [beta] = 100.38(2)°; space group I2; R = 0.068, R[subscript] w = 0.070. Intermolecular hydrogen bonding results in the formation of two-dimensional infinite polymers; (cis-(ala)[subscript]2DPE) Ni(II).ChCl[subscript]3.CH[subscript]3OH: monoclinic, a = 14.195(5), b = 12.175(6), c = 28.071(1), and [beta] = 98.97(3)°; space group P2[subscript]1/n; R = 0.085, and R[subscript] w = 0.089. The average Ni-N distance is 1.92 A and N-Ni-N bond angles range from 88.1(4)° to 92.3(4)° indicating that the Ni environment is essentially square planar; (Ni(DPE)) -(py)[subscript]2.2CHCL[subscript]3: triclinic, a = 14.306(4), b = 14.719(5), c = 14.296(5) A, [alpha] = 94.86°, [beta] = 98.97(3)° and [gamma] = 63.452°; space group P1; R = 0.049, and R[subscript] w = 0.064. The average Ni-N distance is 1.92 A and N-Ni-N bond angles range from 88.5(1)° to 91.9(1)°. The distance between the two terminal nitrogen atoms is 11.4 A; (Ni(DPE)) -(py)[subscript]2.H[subscript]2O: monoclinic, a = 14.240(2), b = 25.418(4), c = 14.725(5) A, and [beta] = 96.38(3)°; space group P2[subscript]1/n; R = 0.081, and R[subscript] w = 0.107. The average Ni-N distance and N-Ni-N bond angle are 1.93 A and 90.2°, respectively. The distance between the two terminal nitrogen atoms is 7.6 A

BIOMECHANICAL STUDY OF THE TRANSmON TECHNIQUE OF EXCELLENT MALE SHOT-PUTTERS

All sports events have undergone many innovations during the 100 years development of Olympic Games. In particular track and field events, ,in which skill development is much more obvious, have been characterized by rapid improvements in human performance. Within the field events, the shot put is a complex event that has prompted many skill innovations from throwing in place to side sliding shot putting, to back sliding throwing, and to rotational shot putting. The outcomes of all these innovations seem to add to the duration of the acceleration phase, which then increase the velocity of release. Because shot put belongs to "cast events", According to trajectory principles, its descriptive mechanical formula is S = v02Sin2a/g with S being affected by the velocity of release. So the key to improving performance in the shot put is to increase its velocity of release. Building of the velocity of the shot begins at the slide stage, and then it passes to the transition stage to transform the velocity into motion of the shot put at release. So skill in the transition phase is very important during throwing the shot put. How to minimize the loss of velocity during the throw is the aim of the present study with a particular emphasis on the transition skill

Effects of taurine on male reproduction in rats of different ages

<p>Abstract</p> <p>Background</p> <p>It has been demonstrated that taurine is one of the most abundant free amino acids in the male reproductive system, and can be biosynthesized by male reproductive organs. But the effect of taurine on male reproduction is poorly understood.</p> <p>Methods</p> <p>Taurine and β-alanine (taurine transport inhibitor) were offered in water to male rats of different ages. The effects of taurine on reproductive hormones, testis marker enzymes, antioxidative ability and sperm quality were investigated.</p> <p>Results</p> <p>The levels of T and LH were obviously increased by taurine supplementation in rats of different ages, and the level of E was also significantly elevated in baby rats. The levels of SOD, ACP, SDH and NOS were obviously increased by taurine administration in adult rats, but the levels of AKP, AST, ALT and NO were significantly decreased. The levels of SOD, ACP, LDH, SDH, NOS, NO and GSH were significantly elevated by taurine administration in aged rats, but the levels of AST and ALT were significantly decreased. The motility of spermatozoa was obviously increased by taurine supplement in adult rats. The numbers and motility of spermatozoa, the rate of live spermatozoa were significantly increased by taurine supplement in aged rats.</p> <p>Conclusions</p> <p>The present study demonstrated that a taurine supplement could stimulate the secretion of LH and T, increase the levels of testicular marker enzymes, elevate testicular antioxidation and improve sperm quality. The results imply that taurine plays important roles in male reproduction especially in aged animals.</p

Donor Bone Marrow-Derived T Cells Inhibit GVHD Induced by Donor Lymphocyte Infusion in Established Mixed Allogeneic Hematopoietic Chimeras

Delayed administration of donor lymphocyte infusion (DLI) to established mixed chimeras has been shown to achieve anti-tumor responses without graft-vs.-host disease (GVHD). Herein we show that de novo donor BM-derived T cells that are tolerant of the recipients are important in preventing GVHD in mixed chimeras receiving delayed DLI. Mixed chimeras lacking donor BM-derived T cells developed significantly more severe GVHD than those with donor BM-derived T cells after DLI, even though both groups had comparable levels of total T cells at the time of DLI. Post-DLI depletion of donor BM-derived T cells in mixed chimeras, as late as 20 days after DLI, also provoked severe GVHD. Although both CD4 and CD8 T cells contributed to the protection, the latter were significantly more effective, suggesting that inhibition of GVHD was not mainly mediated by CD4 regulatory T cells. The lack of donor BM-derived T cells was associated with markedly increased accumulation of DLI-derived alloreactive T cells in parenchymal GVHD target tissues. Thus, donor BM-derived T cells are an important factor in determining the risk of GVHD and therefore, offer a potential therapeutic target for preventing and ameliorating GVHD in the setting of delayed DLI in established mixed chimeras

Quantitative Fractal Evaluation of Herbicide Effects on the Water-Absorbing Capacity of Superabsorbent Polymers

The water absorption capacity of superabsorbent polymers (SAPs) is important for agricultural drought resistance. However, herbicides may leach into the soil and affect water absorption by damaging the SAP three-dimensional membrane structures. We used 100-mesh sieves, electron microscopy, and fractal theory to study swelling and water absorption in SAPs in the presence of three common herbicides (atrazine, alachlor, and tribenuron-methyl) at concentrations of 0.5, 1.0, and 2.0 mg/L. In the sieve experiments it was found that 2.0 mg/L atrazine reduces the capacity by 9.64–23.3% at different swelling points; no significant diminution was observed for the other herbicides or for lower atrazine concentrations. We found that the hydrogel membrane pore distributions have fractal characteristics in both deionized water and atrazine solution. The 2.0 mg/L atrazine destroyed the water-retaining polymer membrane pores and reduced the water-absorbing mass by modifying its three-dimensional membrane structure. A linear correlation was observed between the fractal analysis and the water-absorbing mass. Multifractal analysis characterized the membrane pore distribution by using the range of singularity indexes Δα (relative distinguishing range of 16.54–23.44%), which is superior to single-fractal analysis that uses the fractal dimension D (relative distinguishing range of 2.5–4.0%)

Mono- and Dinuclear Complexes of a New Binucleating Porphyrin, α,α-5,15-Bis(ο-(Nicotinoylamino)Phenyl)-2,8,12,18-Tetraethyl-3,7,13,17-Tetramethylporphyrin. Crystal Structures of a Mononuclear Nickel(II) Complex and a Binuclear Copper-Platinum Complex

The synthesis and characterization of a new binucleating porphyrin ligand, a,a-5, 1 5-bis(o-(nicotinoylamido)phenyl)-2,8, 12,18- tetraethyl-3,7,13,17-tetramethylporphyrin, [H2(DPE)]-(pyh is reported. Treatment of [H 2(DPE)]-(pyh with methanol solutions of Ni(II) or Cu(II) leads to the formation of mononuclear metal complexes, [M(DPE)]-(pyh, in which the metal has inserted into the porphyrin core, leaving the pyridine binding site free. Addition of a second metal to form a binuclear complex, [M( DPE)]-(pyhM\u27Cl2, can be accomplished using the reagent M\u27(DMSOhCI2, M\u27 = Pd, Pt, and Zn. [Ni(DPE)]-(pyh and [Cu(DPE)]-(pyhPtCI2 have been characterized by single-crystal X-ray analysis. Crystal data for [Ni(DPE)]-(pyh: Ni02N 8- C56H52·2CHCI3, triclinic, PI, a= 14.306 (4) A, b = 14.719 (5) A, c = 14.296 (5) A, a= 94.86 (3) 0 , {J = 96.38 (3) 0 , -y = 63.45 (2) 0 , Z = 2, R = 0.049, and Rw = 0.064. Crystal data for [Cu(DPE)]-(pyhPtCI2: CuPt02N 8C 56H 52, triclinic, PI, a= 19.333 (1) A, b = 23.74 (I) A, c = 12.984 (5) A, a= 103.28 (4) 0 , fJ = 108.29 (3) 0 , -r = 76.47 (3) 0 , Z = 4, R = 0.073, and Rw = 0.085. Pt-Pt distances between the two molecules in the asymmetric unit are 3.766 (3) A

Experimental Study on the Adsorption of Heavy Metal Ions in Wastewater by Modified Bentonite

This is an article in the field of ceramics and composites. In order to study the adsorption effect of modified bentonite on heavy metal ions in sewage, the effects of pH value, initial concentration, time, solid-liquid ratio, temperature and particle size on the adsorption effect of bentonite were analyzed. And microscopic means were used to study the changes of the internal mineral composition of the bentonite before and after the adsorption of heavy metal ions and the change law of the infrared spectra. The results showed that when the modified bentonite content was 0.2 g, the adsorption time was 1.5 h, the temperature was set to 40 ℃, the pH value was set to 6, the initial concentration was set to 200 mg/L and the solid-to-liquid ratio was set to 0.8 g/L, the adsorption effect was the best. After the modified bentonite had undergone an adsorption test, an obvious CuSO4 diffraction peak could be detected. However, other mineral components inside the modified bentonite remained unchanged, which also showed that the modified bentonite could effectively adsorb copper ions in sewage

New control strategy against temperature sudden-drop in the initial stage of pad cooling process in poultry houses

Preliminary field measurements have shown substantial temperature sudden-drop (ΔTsd) at bird level in the initial stage of pad cooling process in arid regions of China. Such sudden temperature fluctuation can cause thermal stress to laying hens and this problem is attracting increasing concerns. The purpose of this study was to develop a new control strategy (NCS) to avoid or minimize ΔTsd while simplify the operational process. Theoretical calculation and field test were conducted in this study. The key ambient thermal factor affecting ΔTsd was analysed by calculating temperature drop of cooled air existing the cooling pad (ΔTd). A countermeasure was applied by controlling the wetted pad area at each startup of the water supply pump. Field test was carried out to demonstrate application of the NCS in a poultry house. The theoretical arithmetic results showed that ambient relative humidity (RHo) was the main factor affecting ΔTd, and ΔTsd occurred when RHo ≤ 60%. Temperature fluctuation at the bird level (Tdb,b) could be controlled within 4°C when the wetted pad area increased by 25%. The NCS operated based on RHo that was divided into three regions. For RHo \u3e 80%, the pump would not be turned on because of poor cooling effect. For 60% \u3c RHo \u3c 80%, no ΔTsd would occur and the pump would be controlled by “on-off” regulation. For RHo ≤ 60%, ΔTsd occurred and the pump was turned on intermittently. Then, 4-stage cooling would be applied. Results of the field test were generally consistent with the theoretical simulation with regards to alleviation of ΔTsd that was controlled within 3.5°C. Further field verification of the NCS on the flock health and production performance is warranted

Effects of Superabsorbent Polymers on the Hydraulic Parameters and Water Retention Properties of Soil

Superabsorbent polymers (SAPs) are widely applied in dryland agriculture. However, their functional property of repeated absorption and release of soil water exerts periodic effects on the hydraulic parameters and water-retention properties of soil, and as this property gradually diminishes with time, its effects tend to be unstable. During the 120-day continuous soil cultivation experiment described in this paper, horizontal soil column infiltration and high-speed centrifugation tests were conducted on SAP-treated soil to measure unsaturated diffusivity D and soil water characteristic curves. The experimental results suggest that the SAP increased the water retaining capacity of soil sections where the suction pressure was between 0 and 3,000 cm. The SAP significantly obstructed water diffusion in the soil in the early days of the experiment, but the effect gradually decreased in the later period. The average decrease in water diffusivity in the treatment groups fell from 76.6% at 0 days to 1.2% at 120 days. This research also provided parameters of time-varying functions that describe the unsaturated diffusivity D and unsaturated hydraulic conductivity K of soils under the effects of SAPs; in future research, these functions can be used to construct water movement models applicable to SAP-treated soil