Classical chemical sciences
Cefazolin sodium, a β-lactam antimicrobial agent belonging to the first generation cephalosporins, has a broad spectrum of action, acting against gram positive and gram negative bacteria. Stands out over other cephalosporins for its ability to also act against some species of Enterobacter, and have a long half-life, thus reducing the frequency of administrations. A simple, fast and reproducible method by visible spectrophotometry was developed and validated for quantification of cefazolin sodium in the lyophilized powder. This technique is widely used in the pharmaceutical industry due to its ease of execution, low cost, safety and high precision and accuracy. It has been employed in the quality control routine of numerous pharmaceuticals in order to identify them and quantify their active principles. The method was capable of detecting and quantifying the cefazolin sodium obtaining satisfactory results regarding selectivity, precision, accuracy and robustness, on linear range of 32.0 to 92.0 μg mL-1, showing the correlation coefficient of 0.9993 when analyzed at 767 nm. Due to the environmental impacts caused by global economic development, green chemistry has come up with a proposal to minimize and/or eliminate the use of harmful solvents, which generate large amounts of toxic waste to the environment and the health of operators, as well as reducing expenses with costly processes. The proposed method does not use toxic solvent, proving to be effective, low cost, easy to apply and safe for the analyst and environment.
Keywords: Cefazolin sodium; quality control; visible spectrophotometry; green technique; eco-friendly method
Thienopyrimidines derivatives continue to attract great interest due to the wide variety of interesting biological activities observed for compounds characterized by this heterocyclic system. This review results from the literature survey containing the synthesis of thieno[2,3-d]pyrimidines, thieno[3,2-d]pyrimidines and thieno[3,4-d]pyrimidines from thiophene ring then build pyrimidine ring and from pyrimidine ring then build thiophene ring.
Keywords: thieno[3,4-d]pyrimidines; thieno[3,2-d]pyrimidines; thieno[2,3-d]pyrimidines
Materials and environmental chemistry
Corrosion resistance of Ni-Ti, Thermoactive alloy, and SS 316 L alloy in artificial saliva (AS) in the absence and presence of coffee has been evaluated by electrochemical studies such as polarization study and AC impedance spectroscopy. The polarization and AC impedance spectroscopy studies lead to the conclusion that corrosion resistance of the alloys decreases in the following order: SS 316 L alloy > Thermoactive alloy> Ni-Ti alloy. In all the three cases, the corrosion resistance of the wires increases in the presence of coffee. Among the three orthodontic wires, SS316L alloy is the best candidate.
Keywords: artificial saliva; corrosion; metals; coffee; polarization study; AC impedance spectra
A composite of CdS and ZnS was prepared by simple solid state mechanochemical method and it was used for photocatalytic degradation of Evan’s blue. The photocatalytic efficiency of CdS-ZnS composite was compared with pure CdS and ZnS. The effect of various parameters such as pH, the concentration of dye, amount of semiconductor and light intensity was observed. The optimum conditions obtained for this degradation were: Evan’s blue = 1.3 × 10‾5 M, pH = 5.5, amount of composite = 0.12 g and light intensity = 50.0 mWcm‾2. It was found that coupled chalcogenide CdS - ZnS shows better photocatalytic activity as compared with pure CdS and ZnS for the degradation of Evan’s blue in the presence of visible light.
Keywords: ZnS; CdS; composite; photocatalytic activity; Evan’s blue
Chemical and biological aspects of life
A new possibility is shown for the study of the microcirculatory bed of human breast cancer tissue embedded in Epoxy resins. Using current method - staining the material by Azur II - it becomes possible the obtaining 3D images of blood vessels of human breast cancer tissue which gives new opportunities for further study of this disease.
Keywords: human breast cancer; angiogenesis; light optical microscopy; epoxy resins
Caffeine, a purine alkaloid, was not detected in leaves of two Mascarocoffea species, Coffea millotii and Coffea perrieri. Trigonelline, a pyridine alkaloid, occurred in these species, but the levels (3−4 μmol g-1 fresh weight) were much lower than that of Robusta coffee (Coffea canephora) (36 μmol g-1 fresh weight). Feeding experiments with [8-14C]adenine indicated that purine alkaloid biosynthesis was terminated at 7-methylxanthine formation and as a consequence theobromine and caffeine were not produced in Coffea millotii and Coffea perrieri. The adenine salvage activity was lower, but its degradation activity was higher in leaves of these Mascarocoffea species than those in Coffea canephora. The metabolic fate of the purine nucleosides, [8-14C]inosine, [8-14C]guanosine and [8-14C]xanthosine was investigated in leaves of Coffea millotii. The biosynthesis of 7-methylxanthine, but not theobromine or caffeine, from these precursors was detected. Large amounts of these purine nucleosides were catabolized via allantoin. Limited amounts of [8-14C]inosine and [8-14C]guanosine were salvaged and utilized for RNA synthesis, however, no [8-14C]xanthosine salvage was observed. Little or no 14C-metabolites were observed when [8-14C]theobromine and [8-14C]caffeine were applied to leaf disks of Coffea millotii. From the results obtained in this study, possible metabolic pathways of purines in Mascarocoffea species are discussed.
Keywords: Coffea canephora, Coffea millotii, Coffea perrieri, Mascarocoffea, caffeine, trigonelline, adenine, purine salvage, biosynthesis, metabolism
Industrial and engineering chemistry, biotechnology
Different contents of high abrasion furnace black filler [HAF] and white filler [silica are mixed with ethylene-propylenediene monomer rubber [EPDM] cured by the conventional sulfur system. The thermogravimetric analysis (TGA) characteristics, physico-mechanical properties and swelling measurements of the prepared samples have been investigated. EDAX analyses were done to define the chemical composition of the investigated samples and to locate the dispersion of the fillers and theirs intensity. Comparison of the black and white fillers was performed and it was found that filler incorporation into the rubber matrix was one of the major parameters that enhanced the tensile strength and swelling resistance. The hardness of the investigated samples increased with increasing the filler concentration up to 40/60 phr (part per hundred parts of rubber). This increase can be attributed to greater and more uniform dispersion of filler into the rubber system. Carbon/silica are extensively used in the industry as cheapening filler with high reinforcing effect. Finally, the addition of precipitated silica at the expanse of toxic carbon black (CB) is the main step in decreasing the health risk associated with the presence of CB-filled EPDM composites.
Keywords: Black filler; white filler; swelling measurements; mechanical properties; physico-chemical properties
Theoretical and computational chemistry
The consistent calculations of bond energy in cluster water nanostructures have been performed following the P-parameter methodology and quantum-mechanical methods. The formation of high energy bonds in the process of hydrocarbon hydrogen containing fuel preparation has been explained.
Keywords: Spatial-energy parameter, cluster water nanostructures, high energy bonds