Soil Chemical Analysis

Dietary strategies to counteract the effects of mycotoxins: a review.

A strategy to achieve ortho substitution of phenols initiated by an ortho-palladation to create coumarins was examined Indeed, treatment of alkynoates with electron-rich phenols in the presence of a palladium catalyst and an acid does generate coumarins The scope of the reaction with respect to the phenol and the alkynoates is defined With unsymmetrical aromatic substrates, generally good regioselectivity that reflects the HOMO coefficients can be observed In the course of these studies, numerous important naturally occurring coumarins have been synthesized, including fraxinol methyl ether, ayapin, herniarin, xanthoxyletin, and alloxanthoxyletin The fact that a Pd(0) is the precatalyst rather than a Pd(+2) species and that an acid that reduces Pd(+2) salts, formic acid, functions better than other carboxylic acids raises doubts about the initial working hypothesis A novel mechanism involving a palladium phenoxide formed from a hydridopalladium carboxylate and phenol is invoked to rationalize the results

Atom economy. Palladium-catalyzed formation of coumarins by addition of phenols and alkynoates via a net C-H insertion.

A number of naturally occurring substances, including hamigerans, contain ring systems which are fused to an aromatic nucleus A general and streamlined method for the construction of such benzannulated bi- and polycyclic carbon frameworks has been developed, and its scope and limitations were explored On the basis of the photoenolization of substituted benzaldehydes and subsequent Diels-Alder (PEDA) trapping of the generated hydroxy-o-quinodimethanes, this method was optimized to set the stage for the total synthesis of several naturally occurring members of the hamigeran class Specifically, the developed synthetic technology served as the centerpiece process for the successful asymmetric synthesis of hamigerans A (2), B (3), and E (7) In addition to the PEDA reactions, several other novel reaction processes are described, including a high-yielding decarbonylative ring contraction and an oxidative decarboxylation of a hydroxyl beta-keto ester to afford an alpha-diketone A number of analogues of these biologically active natural products were also prepared by application of the developed technology

Total synthesis of hamigerans and analogues thereof. Photochemical generation and Diels-Alder trapping of hydroxy-o-quinodimethanes.

. Transparent conducting tin oxide thin films have been prepared by electron beam evaporation and spray pyrolysis methods. Structural, optical and electrical properties were studied under different preparation conditions like substrate temperature, solution flow rate and rate of deposition. Resistivity of undoped evaporated films varied from 2.65× $10^{-2}$ $\Omega-cm$ to 3.57× $10^{-3}$ $\Omega-cm$ in the temperature range 150–200°C. For undoped spray pyrolyzed films, the resistivity was observed to be in the range 1.2 × $10^{-1}$ to 1.69 × $10^{-2}$ $\Omega-cm$ in the temperature range 250–370°C. Hall effect measurements indicated that the mobility as well as carrier concentration of evaporated films were greater than that of spray deposited films. The lowest resistivity for antimony doped tin oxide film was found to be 7.74×$10^{-4}$ \Omega-cm, which was deposited at 350°C with 0.26 g of $SbCl_3$ and 4 g of $SnCl_4$ $(SbCl_3/SnCl_4 = 0.065)$ .Evaporated films were found to be amorphous in the temperature range up to 200°C, whereas spray pyrolyzed films prepared at substrate temperature of 300–370°C were polycrystalline. The morphology of tin oxide films was studied using SEM.

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Studies on tin oxide films prepared by electron beam evaporation and spray pyrolysis methods

Thin films of SnO2 were prepared using a spray pyrolysis technique. Films were irradiated with Nd:YAG laser pulses of various energy densities (2–50 mJ cm−2) with varying number of pulses from 1–50. X-ray diffraction studies were made to investigate the structural changes due to laser irradiation. An improvement in crystallinity and an increase in grain size were observed in laser-irradiated films. Hall coefficient and Hall mobility studies were made in the temperature range 77–300 K for the as-grown as well as laser-irradiated films. An increase in mobility and a decrease in carrier concentration were observed in the films after laser irradiation. Optical transmission studies revealed that the refractive index increased as a result of laser irradiation.

Effect of laser irradiation on structural, electrical and optical properties of SnO2 films

Chemoprevention of carcinogen-DNA binding: the relative role of different oxygenated substituents on 4-methylcoumarins in the inhibition of aflatoxin B1-DNA binding in vitro

A homoisoflavanone from Pterocarpus marsupium

A crop absorbing enough of plant nutrients is expected to yield higher than a crop accumulates lower nutrients. Thus estimating nutrient concentrations is essentially an important task to have strategies for sustained higher yields. Nitrogen is one of the major plant nutrients and is an essential constituent of all living cells. It plays a number of functions in the plant growth as it is a constituent of proteins, enzymes and chlorophyll, and takes part in metabolic processes involved in the synthesis and transfer of energy. Its importance in crop production is emphasized by the knowledge that nitrogen generally occurs in relatively small quantities in soils in the available forms and is used in large quantities. However, continuous heavy application of only one nutrient disturbs the nutrient balance and leads to depletion of other nutrients as well as the underutilization of nutrients supplied through fertilizers. Single nutrient approach has often caused reduced fertilizer use efficiency and consequent problems of multiple nutrients deficiencies in cerealbased cropping systems. Accelerated depletion of micronutrients from soil reserve due to enhanced food grain production has accentuated the micronutrients deficiencies in many parts of India, which has brought sharp reduction in the macronutrient (NPK) use efficiencies Shukla [1-3].

https://biomedres.us/pdfs/BJSTR.MS.ID.000576.pdf

S. K. Sharma

Papers

Effect of laser irradiation on structural, electrical and optical properties of SnO2 films

Chemoprevention of carcinogen-DNA binding: the relative role of different oxygenated substituents on 4-methylcoumarins in the inhibition of aflatoxin B1-DNA binding in vitro

A homoisoflavanone from Pterocarpus marsupium

Effect of Nitrogen, Zinc and Boron on Nutrient Concentrationat Maximum Tillering of Wheat

Effect of hydrogen annealing on electrical and optical properties of SnO2 thin films