Challenges and Advances in Chemical Science Vol. 7

Biochemical  methods,  usually  microbial or enzymatic, are  suitable  for  the  production  of  unnatural  or  rare monosaccharides.  D-Arabitol was produced from D-glucose by fermentation with Candida famata R28.  D-xylulose can be produced from D-arabitol using Acetobacter aceti IFO 3281. D-Lyxose was produced enzymatically from D-xylulose using L-ribose isomerase (L-RI). Ribitol was oxidized to L-ribulose by microbial bioconversion with Acetobacter aceti IFO 3281 whereas L- ribulose was epimerized to L-xylulose by the enzyme D-tagatose-3-epimerase. L- Lyxose was produced by isomerization of L-RI. Moreover, L-ribose and L-arabinose were prepared biochemically from ribitol by oxidation using Acetobacter aceti IFO 3281 and isomerization using L- RI and L-arabinose  isomerase  (L-AI),  respectively. Other pentoses can be produced as well by cell or enzyme bioconversions. This study provides important information for rare sugar preparation and importance.

Catalysts Ni/Mg_1-xCe_x⁴⁺O and Ni,Pd,Pt/Mg_1-xCe_x⁴⁺O were developed using the co-precipitation–impregnation methods. Catalyst characterization took place using XRD, H₂-TPR, XRF, XPS, Brunauer–Emmett–Teller (BET), TGA, TEM, and FE-SEM. Testing the catalysts for the dry reforming of CH₄ took place at temperatures of 700–900°C. Findings from this study revealed a higher CH₄ and CO₂ conversion using the tri-metallic Ni,Pd,Pt/Mg_1-xCe_x⁴⁺O catalyst in comparison with Ni monometallic systems in the whole temperature ranges. The catalyst Ni,Pd,Pt/Mg_0.85Ce⁴⁺_0.15O also reported an elevated activity level (CH₄; 78%, and CO₂; 90%) and outstanding stability. Carbon deposition on spent catalysts was analyzed using TEM and Temperature programmed oxidation-mass spectroscopy (TPO-MS) following 200 h under an oxygen stream. The TEM and TPO-MS analysis results indicated a better anti-coking activity of the reduced catalyst along with a minimal concentration of platinum and palladium metals. The objective of this work is to examine the role of the Pt and Pd metals on the catalysts, as well as evaluating the stability of the catalysts and investigate the effects of reactant feed ratio, the catalysts concentration, the prepared catalysts conversion temperature, the efficacy of the catalysts in DRM process, and to inspect the enhancement of methane conversion through passing oxygen gas stream across the reaction.

Catalysts based on (R, R)-1,2-diphenylethylenediamine are as chiral organic catalysts, applied to the asymmetric Michael addition to \(\alpha\), \(\beta\)-unsaturated nitroalkenes under neutral conditions. The role of an aqueous medium for organic catalytic activity can be reversed concerning hydrophilic-hydrophobic function depending on the reaction conditions. In this study, to provide an environmentally friendly system, the thiourea-based catalyst substituted with 3,5-(CF₃)₂-Ph was used in water solvents. The hydrophobic effect of the substituent, provides fast reaction, high chemical yield, and mirror-image selectivity. This reaction allowed the preparation of GABA_B agonists in an optically pure manner. Besides, GABA (\(\gamma\)-aminobutyric acid) analogs such as baclofen and phenibut were synthesized as R-type S-type with high optical purity. We demonstrated that R-baclofen induced a higher intracellular Ca²⁺ release than RS-baclofen. Taken together, our data show that as a drug, baclofen RS-type may induce differential calcium release activity depending on R and S-types. This will in turn induce differential GABA_B receptor activation.

In present days many types of materials are used to reduce the environmental pollution in the world which includes nanomaterials. Nanopesticides increase the efficacy, durability and reduction in the amount of active constituent. The potential objectives of nanotechnology in pesticides are quick decomposition in soil or plant, targeted delivery, apparent solubility and controlled release. In this communication the author reported a neonicatonoid insecticide called as Nano-acetamiprid and it is widely used to control fungal infections in different crops like cotton, leafy vegetables, citrus fruits, pome etc. Nano-acetamiprid is highly active at lower level concentration and reduces toxicity in agricultural fields. The author reported a facile method i.e. a new Nano-acetamiprid for plant disease control and its subsequent characterization of encapsulated complex using polycaprolactone as an encapsulated agent. Nano-acetamiprid encapsulated particles were characterized by dynamic light scattering (DLS), ultraviolet spectroscopy and scanning electron microscopy (SEM). To ascertain the formation and the stability of nanoencapsulated acetamiprid pesticide, the maximum absorption spectra formulated at 421 nm and unformulated pesticide at 520 nm were observed. The size distribution was noted at 40 - 50 nm. The bioactivity study was conducted against various Aspergillus niger. The performance of nano particles was many fold times effective when compared to the original parental particles. The bio-assay of Nano-acetamiprid shows better results when compared to the normal commercial acetamiprid.

One of the major environmental issues that have severe adverse effect on sustainable agriculture productivity is soil salinization. A research was conducted at Ho-Keta plain in the Volta Region of Ghana to assess the extent of degradation of salt-affected agricultural soils. Two soil series, Oyebi and Ada in three salt-affected areas within the Lower Volta basin in the Ho-Keta plain were selected from Anyako, Anyenui and Atiehife. Soil sampling was done randomly at the depth of 0-30 cm from the soil sites and transported to the laboratory for analysis and measurement of pH (4.61) Calcium (5.60meq/l), Magnesium (3.17meq/l), Sodium (6.95meq/l), Potassium (1.83meq/l) and Electrical Conductivity (5.13dS/m) respectively. The mean values of Ca, Mg, Na and K were used to estimate Sodium Adsorption Ratio (SAR) and Exchangeable Sodium Percentage (ESP) respectively. The mean values of SAR and ESP in the three selected areas were: 43.89, 52.02, 42.85 and 33.87%, 40.77% and 37.83 5% respectively. The results revealed land degradation in the study area as a result of high levels of SAR and ESP leading to low soil chemical properties. The fertility level of the soil was very low and requires management practices that promote accumulation of organic matter. Further investigation to show the extent and the nature of soils in the study area is highly recommended.

The objective of this work is to determine and quantify the inorganic compounds of PM_2.5 aerosols; collected using a two-stage Dekati® PM10 impactor; in educational establishments in Tiaret-city "Algeria". It also aimed to follow the dispersion of these particles in sites near the forest, urban fabric and urban sites exposed to dense road traffic, as well as to determine the source of this type of pollution. 23 primary schools were chosen as sampling sites in Tiaret city. The collection of PM_2.5 was carried out in the winter and summer period. The spectroscopic analysis carried out by FTiR-ATR shows that the sulfate ions recorded their maximum in the summer period than in the winter, as well as the nitrate and ammonium ions which do not show a large seasonal difference. The dominant species in urban areas are NO₃^-, SO₄^-2 which due to the presence of a very important source of NOx and SO2 which, by gas-particle conversion, transform into nitrate and sulfate ions respectively. These species present a lower proportion in sites close to the forest. However, the same order of abundance of these ions exists in the two sampling periods. The main sources of NOx in urban sites are combustion phenomena linked in particular to the transport system, which is characterized by very dense traffic in the city's agglomeration.

The objective of this study is to fabricate reusable nanostructured materials based on Ag/TiO₂ at low cost for photocatalysis applications. Vertical Ag_x/TiO₂ nanorods were successfully grown by a simple oxidation method of a Ti-Ag coating. The samples were grown in the phase of ceramic-like materials, which can be reusable for many cycles for photocatalysis applications. These ceramic-like Ag_x/TiO₂ nanostructures were prepared by the spin-coating of silver nitrate onto Ti sheets. The presence of silver on the surface of the Ti sheet during the oxidation process helped in the growth of one-dimensional nanostructures. The physical properties of the fabricated ceramic-like nanostructures were studied by varying the concentration of silver on the Ti-sheet before the oxidation. One-dimensional nanostructures with an average size varying within the range of 200–500 nm were grown. The presence of silver made the nanostructure vertically directed. The nanorods were dense at the low and medium concentrations of 5, 10, and 20 mM of silver in contrary to high silver concentrations, where the nanorods were very sparse at 40 mM. Structural analysis showed the anatase and rutile structure of pure TiO₂ with distinguishing diffraction lines A(101) and R(110); however, Ag_x/TiO₂ showed a dominant orientation of A(101), confirming the 1D growth. Raman spectra confirmed the presence of TiO₂ via the observation of its corresponding phonon modes. The photocatalysis properties of the fabricated ceramic-like nanostructures were performed on methylene blue (MB) as a known target dye. The low- and medium-silver-concentration samples showed a high photocatalytic activity compared to the pure and high-silver-concentration samples.

The objective of this study is related to the leaching study of the phosphate glass fertilizers with different compositions under Soxhlet distillation conditions. Glass fertilizers in the phosphate systems were melted at 900-950\(^{\circ}\)C with a soaking period of 1 h. Leaching study of these glasses with a maximum time period of 300 h was conducted under Soxhlet distillation condition with distilled water. Weight loss and the leach rates of the glass fertilizer samples were calculated from BET surface area measurements. They were in the range of 6.3x10-3 to 2.3x10-3 g.m-2.h-1 at 90\(^{\circ}\)C. The effect of different modifier ions like Na+, Fe3+, Mg2+, Ca2+, and K+ in the basic phosphate networks on melting and time of melting has been found to be evident. The pH determination ranging from 4.80 up to 7.50 of the leachate solution at ambient temperature under varying time intervals showed interesting and regular variations. The leaching study of such glasses under Soxhlet condition showed Ca2+, Mg2+, and K+ to be good candidates as modifier towards faster leaching. The findings have been corroborated in terms of ionic size, ionic radius, and hence the ionic potential of the modifier ions incorporated into the glass structure. The application of glass fertilizers was made on kharif paddy. The addition of alkaline earth oxides increases the corrosion of phosphate glasses, whereas the addition of intermediate oxides decreases the corrosion of phosphate glasses. It was shown that after the application of the glass fertilizer, the growth and production of the khariff paddy was better than the normal application of the conventional fertilizers.

Conductance values of a complex, N-[(benzoyl-amino) thioxomethyl] serine copper (II) chloride was estimated in methanol-water mixed solvents, viz., X_methanol=0.0000-1.0000 at temperature ranges 283.15 to 313.15 K. From the experimental results, the ion association constants (K_A ) and limiting equivalent conductance (\(\Lambda\)₀ ) were determined by analyzing conductivity data concerning Shedlovsky equations for the electrolytes. The Walden product, (\(\Lambda\)₀ \(\eta\)₀ ) values were calculated in various water + methanol mixtures at 283.15 to 313.15 K. It was observed that the increase in the percentage of methanol results in an increase in association constant values. It was also found that with the increase in K_A values dielectric constant values were also increased. Increase in K_A values with the increase in the dielectric constants of the mixtures. \(\Lambda\)₀values linearly increased as the increased in temperature. Thermodynamic factors were calculated from the K_A s and the results we got were examined.

Various parameters such as percent covalency (\(\delta\)), the Slater-Condon (F_k), the Nephelauxetic ratio (\(\beta\)), bonding parameters (b^1/2), Lande orbit-spin coupling (\(\xi\)_4f), have been estimated for the Nd(III)-L-histidine complex using their absorption spectra as a probe. Divergent solvents namely acetonitrile, DMF, methanol, dioxane were used and investigated the effect of Zn(II) ion in the complexation.  The variations based on these parameter values disclose and reveal the bond formation between L-histidine and Nd(III). From the bond formation, we confirm that the DMF solvent promotes the 4f-4f dipole electric intensities compared to the other solvents investigated. The Judd-Ofelt parameter, given by T_\(\Lambda\) (\(\Lambda\) = 2,4,6),  gives the electronic dipole transition and theoretical calculations have been carried out to obtain the oscillator strength for Nd(III) complexation with L-histidine in the presence and the absence of Zn(II) in various aquated solvents which are organic, i.e., acetonitrile, 1,4-dioxane, N,N-dimethylformamide(DMF), and methanol.

Considerable attention has been focused on the synthesis of 7,-dimethyl-4-phenyl tetrahydroquinazalones- (1H, 3H)-2, 5-diones derivatives due to having a broad spectrum of biological activities such, antibacterial activity and fungicidal. As a part of our research work in this area the present investigation of efficient and cost-effective method for the synthesis of 7,7-dimethyl-4-phenyl tetrahydroquinazalones-(1H,3H)-2,5-diones derivatives employing  dimedone, urea and substituted aromatic  aldehyde using Methanesulfonic acid as catalyst under solvent free condition. Characterization and structural elucidation of the products was realized based on chemical, analytical and spectral analyses .The newly synthesized compounds were analyzed by ¹H-NMR &¹³CNMR, Mass spectral and Elemental analysis. Antimicrobial activities of the titled compounds were also examined by various strains and exhibited mild to moderate anti-bacterial and anti-fungal activities.