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This study focused on the state, forms and the availability of potassium in the saline soils in the middle and southern parts of Iraq (The holy Karbala, Babil, Diwaniyah, Kut, Nasiriyah and Basrah). The availability of potassium was evaluated based on the thermodynamic criterion. Representing samples (3 replicates) were collected from the studied areas from 0 to 30 cm depth. The samples were dried and winnowed by a 2-mm sieve, thermodynamic criteria represented by (ionic force, efficacy coefficient, efficacy, potassium potential, ARK, free energy. The thermodynamic criterion results showed that the values of the ionic force ranges from 0.07 to 1.14 mol L-1, while the values of the potassium efficacy coefficient ranges from 0.23 to 0.97 and the potassium efficacy ranged from 0.0006 to 0.0032 mol L-1, this indicates that the concentration of remaining potassium in the soil is inactive. The values of the potassium potential ranged from 3.22 to 2.49, hence, the potassium potential is considered sufficient in the studied sites including Karbala, Babil, Al-Basrah, while there is a lack of potassium potential in Diwaniyah, Kut and Nasiriyah from salinity according to the suggested classification by the Woodruff 1955 for determination of potassium potential in the soil. The values of ARK ranged from 0.001 to 0.017 mol L-1 and the values of the free energy ranged from 2410 to 3813 cal mol-1, hence, all the studied soils suffered from potassium deficiency according to the classification by the Woodruff 1955 except the site of the holy Karbala in which the potassium was moderately available. [ABSTRACT FROM AUTHOR]

This article describes an extension of the quantum supercharger library (QSL) to perform quantum mechanical (QM) gradient and optimization calculations as well as hybrid QM and molecular mechanical (QM/MM) molecular dynamics simulations. The integral derivatives are, after the two-electron integrals, the most computationally expensive part of the aforementioned calculations/simulations. Algorithms are presented for accelerating the one- and two-electron integral derivatives on a graphical processing unit (GPU). It is shown that a Hartree-Fock ab initio gradient calculation is up to 9.3X faster on a single GPU compared with a single central processing unit running an optimized serial version of GAMESS-UK, which uses the efficient Schlegel method for [ABSTRACT FROM AUTHOR]

The influence of maltose-modified poly(propylene imine) (PPI) dendrimers on dimyristoylphosphatidylcholine (DMPC) or dimyristoylphosphatidylcholine/dimyristoylphosphatidylglycerol (DMPC/DMPG) (3%) liposomes was studied. Fourth generation (G4) PPI dendrimers with primary amino surface groups were partially (open shell glycodendrimers — OS) or completely (dense shell glycodendrimers — DS) modified with maltose residues. As a model membrane, two types of 100 nm diameter liposomes were used to observe differences in the interactions between neutral DMPC and negatively charged DMPC/DMPG bilayers. Interactions were studied using fluorescence spectroscopy to evaluate the membrane fluidity of both the hydrophobic and hydrophilic parts of the lipid bilayer and using differential scanning calorimetry to investigate thermodynamic parameter changes. Pulsed-filed gradient NMR experiments were carried out to evaluate common diffusion coefficient of DMPG and DS PPI in D 2 O when using below critical micelle concentration of DMPG. Both OS and DS PPI G4 dendrimers show interactions with liposomes. Neutral DS dendrimers exhibit stronger changes in membrane fluidity compared to OS dendrimers. The bilayer structure seems more rigid in the case of anionic DMPC/DMPG liposomes in comparison to pure and neutral DMPC liposomes. Generally, interactions of dendrimers with anionic DMPC/DMPG and neutral DMPC liposomes were at the same level. Higher concentrations of positively charged OS dendrimers induced the aggregation process with negatively charged liposomes. For all types of experiments, the presence of NaCl decreased the strength of the interactions between glycodendrimers and liposomes. Based on NMR diffusion experiments we suggest that apart from electrostatic interactions for OS PPI hydrogen bonds play a major role in maltose-modified PPI dendrimer interactions with anionic and neutral model membranes where a contact surface is needed for undergoing multiple H-bond interactions between maltose shell of glycodendrimers and surface membrane of liposome. [ABSTRACT FROM AUTHOR]

The original method is developed for producing the new inorganic sorption material of akaganeite bgr-FeO(OH). The material in question is characterized relative to arsenic contained in aqua. The possibility is established for removing arsenate ions from water by contemporary physicochemical methods. [ABSTRACT FROM AUTHOR]