Chemical Properties Of Substrates Research Articles

Physical and Chemical Properties of Substrates Containing Earthworm Castings and Effects on Marigold Growth

The effects of various substrates with or without earthworm [Eisenia fetida (Savigny, 1826] castings on growth of marigolds were evaluated. In addition, the physical and chemical properties of such substrates were determined. Castings had a greater nutrient content than the remaining substrates. The 4 pine bark: 1 sand treatment (v/v) (PBS) had higher P, K, and Zn than 7 peat moss: 3 perlite (v/v) (PP). PP had the lowest nutrient content of all substrates. Castings (C) had the highest pH followed by 1 PBS: 1 C (v/v), 2 PBS: 1C (v/v) and 3 PBS: 1C (v/v). Sunshine Mix 1 and PP had the lowest pH. EC (ER) was increased by castings, which had high ER. Castings and PP had the greatest percentage pore space. Water-holding capacity was greatest for 2 PBS: 1C (v/v) compared with Sunshine Mix 1 followed by castings. Earthworm castings increased plant growth index, stem diameter, root growth, dry weight, and flower number of marigolds compared with PP, Sunshine Mix 1, and PBS. All mixtures of castings (C) with PP, PBS, except 3 PBS: 1C (v/v), increase the growth index of plants. 1 PP: 1 C (v/v), increased flower number compared with all substrates without castings. Castings alone increased number of open flowers, but did not differ from 1 PP: 1 C or 3 PP:1 C.

Thermo‐Responsive Gating Characteristics of Poly(N‐isopropylacrylamide)‐Grafted Membranes

AbstractBoth hydrophilic Nylon‐6 membranes and hydrophobic poly(vinylidene fluoride) (PVDF) membranes, with a wide range of grafting yields of poly(N‐isopropylacrylamide) (PNIPAM), were prepared using the plasma‐graft pore‐filling polymerization method. The effect of the physical and chemical properties of the substrates on the thermo‐responsive gating characteristics of the PNIPAM‐grafted membranes was investigated experimentally. For both the PVDF and Nylon‐6 membranes, the grafted PNIPAM polymers were found not only on the membranes outer surface, but also on the inner surfaces of the pores throughout the entire thickness of the membrane. The thermo‐responsive gating characteristics of the PNIPAM‐grafted membranes were heavily affected by the physical and chemical properties of the porous membrane substrates. The PNIPAM‐g‐Nylon‐6 membranes exhibited a much larger thermo‐responsive gating coefficient than the PNIPAM‐g‐PVDF membranes. Furthermore, to achieve the largest thermo‐responsive gating coefficient, the corresponding optimum grafting yield of PNIPAM for the PNIPAM‐g‐Nylon‐6 membranes was also larger than that for the PNIPAM‐g‐PVDF membranes.

Caracterização física e química de alguns substratos comerciais

The objective of the this work was to evaluate physical and chemical properties of the substrates Germina (10%), Germina (20%), F3, F8, F12, Fibra Flor, Garden Plus and Turf. The experimental design was entirely randomized, with eight treatments and five repetitions. Physical analysis (total porosity, space of aeration, available water, remaining water, dry bulk density and particle diameter) as well as chemical analyses (pH, OM, P, K, Ca, Mg, H+Al), were carried out and (BS, T and V%) calculated. The substrates presented different physical characteristics. The F3, F8, F12 and Fibra flor showed smaller water availability greater aeration space. The chemical properties of substrates varied according to the components and were, in general, adequate to commercial substrates.

Atributos físicos e químicos de substratos compostos por biossólidos e casca de arroz carbonizada

O objetivo deste trabalho foi estudar os atributos físicos e químicos de substratos com diferentes doses de biossólido (BIO) e de casca de arroz carbonizada (CAC), com vistas em obter um meio de crescimento adequado para o desenvolvimento de mudas. Desta forma, utilizando biossólido proveniente da SABESP, estação de Franca (SP), estabeleceu-se um ensaio com os seguintes tratamentos (proporções BIO/CAC): 100/0, 90/10, 80/20, 70/30, 60/40, 50/50, 40/60, 30/70, 20/80, 10/90 e 0/100, os quais foram comparados ao substrato comercial Multiplant®. Foram realizadas análises para determinação dos atributos físicos, como: densidade aparente do substrato, macro e microporosidade, porosidade total, capacidade máxima de retenção de água, e dos atributos químicos dos substratos, como: teores totais de macro e micronutrientes, pH, relação C/N e condutividade elétrica. Com a elevação da dose de BIO no substrato houve aumento da densidade e do percentual de microporos e, conseqüentemente, da capacidade de retenção de água. O BIO apresentou teores razoáveis de nutrientes com destaque para N e P, mas baixos teores de K. Não foram detectados teores de metais pesados superiores aos limites estabelecidos pela Legislação Brasileira no biossólido usado. Comparando-se os valores considerados adequados para o desenvolvimento de mudas encontrados na literatura com os obtidos neste trabalho, encaixaram-se na faixa adequada os substratos cujas doses de biossólido variaram de 30 a 60 %. Nenhum substrato testado, incluindo o do tratamento com substrato comercial, apresentou valores ideais em todas as propriedades estudadas.

Some physical and chemical properties of substrates designed for container production of spruce (Picea abies (L) Karst)

Efficient nursery production of woody plants, as well as the level of their successful application in urban green spaces, greatly depends upon properties of substrates in which these individuals grow, develop and endure. Furthermore, quality of substrate does not only affect the quality of future product (plant individual or green space), but distinctly determines its price. This element, extremely significant for all countries in transition, thus Serbia as well, commands finding ways of making qualitative, but least expensive substrate. The most logical solution is to use mixtures/substrates of precisely defined properties, composed of domestic components. Results presented in this paper imply that it is possible to create precisely such standard mixtures from domestic resources at relatively low cost, adjusted to needs of particular species, which would ultimately lead to successful, non-expensive nursery production and application of produced stock, both on domestic and foreign markets.

Substrates for gallium nitride epitaxy

In this review, the structural, mechanical, thermal, and chemical properties of substrates used for gallium nitride (GaN) epitaxy are compiled, and the properties of GaN films deposited on these substrates are reviewed. Among semiconductors, GaN is unique; most of its applications uses thin GaN films deposited on foreign substrates (materials other than GaN); that is, heteroepitaxial thin films. As a consequence of heteroepitaxy, the quality of the GaN films is very dependent on the properties of the substrate—both the inherent properties such as lattice constants and thermal expansion coefficients, and process induced properties such as surface roughness, step height and terrace width, and wetting behavior. The consequences of heteroepitaxy are discussed, including the crystallographic orientation and polarity, surface morphology, and inherent and thermally induced stress in the GaN films. Defects such as threading dislocations, inversion domains, and the unintentional incorporation of impurities into the epitaxial GaN layer resulting from heteroepitaxy are presented along with their effect on device processing and performance. A summary of the structure and lattice constants for many semiconductors, metals, metal nitrides, and oxides used or considered for GaN epitaxy is presented. The properties, synthesis, advantages and disadvantages of the six most commonly employed substrates (sapphire, 6H-SiC, Si, GaAs, LiGaO2, and AlN) are presented. Useful substrate properties such as lattice constants, defect densities, elastic moduli, thermal expansion coefficients, thermal conductivities, etching characteristics, and reactivities under deposition conditions are presented. Efforts to reduce the defect densities and to optimize the electrical and optical properties of the GaN epitaxial film by substrate etching, nitridation, and slight misorientation from the (0 0 0 1) crystal plane are reviewed. The requirements, the obstacles, and the results to date to produce zincblende GaN on 3C-SiC/Si(0 0 1) and GaAs are discussed. Tables summarizing measures of the GaN quality such as XRD rocking curve FWHM, photoluminescence peak position and FWHM, and electron mobilities for GaN epitaxial layers produced by MOCVD, MBE, and HVPE for each substrate are given. The initial results using GaN substrates, prepared as bulk crystals and as free-standing epitaxial films, are reviewed. Finally, the promise and the directions of research on new potential substrates, such as compliant and porous substrates are described.

Mechanism of cyanamide hydration catalyzed by carbonic anhydrase II suggested by cryogenic X-ray diffraction.

The three-dimensional structure of a possible intermediate in the hydration reaction of cyanamide to urea catalyzed by human carbonic anhydrase II (hCAII) has been determined by cryocrystallographic techniques. The crystal structure shows that two different adducts are formed under the experimental conditions and that they have different occupancy in the crystal. The high occupancy form consists of a binary hCAII-cyanamide complex where the substrate has replaced the zinc-bound hydroxide anion present in the native enzyme, maintaining the tetrahedral geometry around the metal ion. The second, low-occupancy form consists of a hCAII-cyanamide-water ternary complex where the catalytic zinc ion, still being bound to cyanamide, is approached by a water molecule in a five-coordinate adduct. While the first form can be considered a nonproductive complex, the second form may represent an intermediate state of the catalyzed reaction where the water molecule is about to perform a nucleophilic attack on the zinc-activated cyanamide substrate. The structural evidence is consistent with the kinetic data previously reported about this recently described hydrolytic reaction catalyzed by hCAII, and indicates that a different mechanism with respect to that generally accepted for the physiologic carbon dioxide hydration reaction may be adopted by the enzyme, depending on the substrate chemical properties.

Substrate dependence of initial growth of microcrystalline silicon in plasma-enhanced chemical vapor deposition

Very thin microcrystalline silicon films have been deposited by plasma-enhanced chemical vapor deposition (CVD) from hydrogen diluted SiH4 gas in order to study its initial growth mechanism. The dependence of the crystallinity and the Si-H bonding configuration on electrical and chemical properties of substrates have been studied using a high sensitivity Raman spectrometer. It is found that conductive and oxygen free substrates provide good crystallinity in the initial stage. The origin of the substrate dependence is explained in terms of the ion bombardment from the plasma and the chemical nature of the substrate surface.

Rat peritoneal macrophage adhesion to hydroxyethyl methacrylate-ethyl methacrylate copolymers and hydroxystyrene-styrene copolymers.

Macrophage adhesion to a wide variety of substrates has been measured, but no systematic study of the influence of specific substrate chemical properties on adhesion is available. These studies were conducted using two series of materials, copolymers of hydroxyethyl methacrylate (HEMA) and ethyl methacrylate (EMA) and copolymers of hydroxystyrene and styrene, to determine the effect of a single chemical property, polar character, on adhesion. Rat peritoneal macrophages were allowed to contact polymer substrates for periods ranging from 1 to 240 min before being subjected to a shear stress of 60-120 dynes/cm2 in a thin-channel flow cell. Percentage adhesion was calculated from the number of cells that remained adherent to the substrate after 30 s of applied shear stress. Macrophages remained adherent to 100% EMA and all hydroxystyrene-styrene copolymer surfaces after only 1 min of contact. In copolymers of the HEMA-EMA series, the time required to attain peak adhesion levels increased with increasing substrate hydrophilicity (increasing HEMA content). Cells did not attach to the 20% EMA/80% HEMA copolymer and the 100% HEMA polymer. The results demonstrate that there is a time delay between contact and adhesion of the cells to surfaces of increasing hydrophilicity within the HEMA-EMA series and no time delay with the hydroxystyrene-styrene series. The time delay is thought to be a function of the excluded volume provided by polymers that are able to undergo significant chain rotation and or swelling in the solvent, water. Small excluded volumes present in copolymers of high EMA content and all hydroxystyrene-styrene copolymers offer little or no resistance to formation of adhesive bonds by macrophages, whereas copolymers with large excluded volumes (high HEMA content) prevent contact and/or adhesion. A mechanism based on the net excluded volumes of both the cell and substrate surface macromolecule is proposed to explain this phenomenon.

Submerged fermentation of amylase enzyme by <i>Aspergillus flavus</i> using <i>Cocos nucifera</i> meal

Soil samples were collected from the coastal region of Neendakara, along the West cost of Kerala, India. 15 fungal species were isolated and identified by using lacto phenol cotton blue staining method. From this, Aspergillus flavus was tested in Starch Hydrolysis Agar Medium for its amylase enzyme production under sumerged aerobic fermentation with different physico- chemical properties of substrates. Cocos nucifera meal was used as a carbon source. Heavy metals were added to these medium and were used as a modified medium. The effect of different carbon source, nitrogen compound and physico-chemical conditions like temperature, pH and incubation periods were studied for derivation of amylase enzyme. The molecular weight of enzyme was determined by SDS –PAGE. The role of heavy metals was determined by ion exchange chromatography. Cocos nucifera meal medium with dextrose has shown the highest amylase production at pH 6.0 and temperature of 30ºC with protein content of 201μg/ml; 98.4μg/ml and dry biomass of 1.28μg/ml. Keywords: Soil samples; A. flavus; amylase; SDS-PAGE; Ion exchange chromatography; submerged aerobic fermentation DOI: 10.3126/kuset.v6i2.4015Kathmandu University Journal of Science, Engineering and Technology Vol.6. No II, November, 2010, pp.75-87