Influence of the grain size on the quality of standardless WDXRF analysis of river Nile sediments

In multichannel wavelength-dispersive X-ray fluorescence spectrometry (WDXRF) the fluorescence intensity might depend on grain size and heterogeneity of the sample. Six river Nile sediment samples were collected two meters below the water surface from different locations covering the greater Cairo, Egypt. Each sample was dried at 65 °C for 48 h and divided into four grain size fractions: < 32 μm, 32–63 μm, 63–125 μm and 125–200 μm using different sieves. The dry sediment samples were mixed with low contamination binder (Wax, C₆H₈O₃N₂) in a mass ratio of wax:sample = 4:0.9 g. Sample pellets were made using a hydraulic press at a pelletizing pressure of 120 KN cm^{− 2}. The results show that the XRF intensities of the K_α radiation might increase or decrease with decreasing grain size, depending on the atomic number of the analyte. In the present thick pelletized samples, the penetration depth of the characteristic radiation increases at low grain sizes, and consequently the probability of the grain-size effect on the characteristic radiation decreases. Depending on the experimental data, a general theoretical equation, relating fluorescence intensity, grain size and atomic number, was derived by using cubic spline interpolation. The fractions were identified by WDXRF using standardless quantitative analysis, depending on the fundamental parameter approach. According to the present statistical analysis and the Certified Reference Material (CRM) results, the quantitative analysis results were found acceptable when the grain size of the river Nile sediments less than 32 μm. At a grain size > 63 μm, standardless analysis using fundamental parameter approach was found to be useful for qualitative and semi-quantitative analysis only whereas there are a strong positive correlations.     

The behavior of natural biomass materials as drug carriers in releasing loaded Gentamicin sulphate

Pharmaceutical and clinicians researchers are looking for novel drug carriers to maintain the drug level in the body in low and effective dose. Thus, the present research concerned with studying the behavior of some natural biomass materials, namely microcrystalline cellulose, MCC, nanocrystalline cellulose, NCC, nanomethylcellulose, MC, and carboxymethyl cellulose, CMC, as a drug carrier materials for the Gentamicin sulphate, GM, by following up their rate of releasing the loaded drug with the time. Knowing of the initial rate of the releasing to each one and the sustaining rate along the period of the treatment, helps in choosing the best carrier for the drug that matches the patients requirements either whom are in need for a rapid dose (high level) of the drug followed by slow (low level) dose or those in need to start with the low level of the drug followed by high level of the drug. We chose MCC, NCC, MC and CMC, as natural, nontoxic biodegradable and renewable biomass materials, beside their low cost, to carry out this study. The results of the drug release, which measured by UV spectra, showed that the MCC, NCC, MC and CMC loaded with 0.025 g of the GM drug released 27.2%, 42.1%, 29.7%, 28.5% of the drug, respectively, along 10 days. All of them achieved the slow of the drug release but their behavior were different, where MCC, NCC and CMC started with low release then increased, and inversely, MC gave high rate of drug release and then decreased. The cause of this behavior was concerned to the adsorbing of the drug particles on the surface of the biomass materials or absorbing of the drug particles into the pores of the biomass materials. This was indicated by the study of their morphological image using the SEM, as well as indicating the presence of the functional group using the FT-IR study. The XRD, EDX and Agar Diffusion Assay, i.e. antimicrobial activity, against Staphylococcus aureus, Escherichia Coli, Pseudomonas aeruginosa and Bacillus subtilis were carried out to make help in choosing of the best carrier convenient to the case of the illness requirement.     

A new steroid from the Red Sea soft coral Lobophytum lobophytum

Chemical investigation of the soft coral Lobophytum lobophytum collected from the Red Sea led to the isolation of a new compound gorgostan-5,25-dien-3β-ol (1), and two known compounds gorgosterol (2), and alismol (3). Structures were elucidated by employing extensive NMR and HR-ESI-MS experiments.     

Synthesis and characterization of transition metal complexes of N′-[(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)methylene]thiophene-2-carbohydrazide

A hydrazone ligand (HL) containing the thiophene moiety has been prepared via condensation of thiophene-2-carbohydrazide with 1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazole-4-carbaldehyde. The complexes of copper(II), nickel(II), cobalt(II), manganese(II), zinc(II), palladium(II), iron(III), ruthenium(III), uranyl(VI), and titanium(IV) with the ligand were prepared in good yield from the reaction of the ligand with the corresponding metal salts. The ligand and complexes were characterized using infrared, mass spectra, nuclear magnetic resonance, electronic absorption spectra, electron spin resonance, and magnetic moment measurements as well as elemental and thermal analyses. The results showed that the complexes are enolic by nature, whilst the ratio between the metal ion and the ligand depends on the acidity of the metallic ions and their oxidation numbers.     

Nanomaterials for Biomedical Applications: Production,Characterisations, Recent Trends and Difficulties

Designing of nanomaterials has now become a top-priority research goal with a view to developing specific applications in the biomedical fields. In fact, the recent trends in the literature show that there is a lack of in-depth reviews that specifically highlight the current knowledge based on the design and production of nanomaterials. Considerations of size, shape, surface charge and microstructures are important factors in this regard as they affect the performance of nanoparticles (NPs). These parameters are also found to be dependent on their synthesis methods. The characterisation techniques that have been used for the investigation of these nanomaterials are relatively different in their concepts, sample preparation methods and obtained results. Consequently, this review article aims to carry out an in-depth discussion on the recent trends on nanomaterials for biomedical engineering, with a particular emphasis on the choices of the nanomaterials, preparation methods/instruments and characterisations techniques used for designing of nanomaterials. Key applications of these nanomaterials, such as tissue regeneration, medication delivery and wound healing, are also discussed briefly. Covering this knowledge gap will result in a better understanding of the role of nanomaterial design and subsequent larger-scale applications in terms of both its potential and difficulties.     

Ultrasonic dyeing of cationized cotton fabric with natural dye. Part 1: cationization of cotton using Solfix E

The dyeing of cationized cotton fabric with Solfix E using colouring matter extracted from Cochineal dye has been studied using both conventional and ultrasonic techniques. Factors affecting dye extraction such as ultrasound power, particle size, extraction temperature and time were studied. The results indicated that the extraction by ultrasound at 300 W was more effective at lower temperature and time than conventional extraction. The effect of various factors of dye bath such as pH, salt concentration, ultrasound power, dyeing time and temperature were investigated. The colour strength values obtained were found to be higher with ultrasound than with conventional techniques. The results of fastness properties of the dyed fabrics were fair to good. The scanning electron microscope (SEM) images of the morphological and X-ray analyzes were measured for cationized cotton fabrics dyed with both conventional and ultrasound methods, thus showing the sonicator efficiency.     

Lead telluride nanocrystalline thin films: Structure,optical characterization and a broadband dielectric spectroscopy study

Nanocrystalline PbTe thin films were deposited on a glass substrate by thermal evaporation technique with two thicknesses namely, 45 and 250 nm. The structural studies revealed that the films have nanocrystalline cubic structure and the particle size was found to be 11 and 20.7 nm, for low and high thicknesses respectively. The FE-SEM study shows that the surface grains increase for higher thickness film. This indicates that samples lying under the strong regime of confinement for PbTe thin films. The optical properties confirm the occurrence of confinement process as the optical band gap are 1.67 and 0.9 eV for 45 and 250 nm films, respectively. The dielectric results indicated that the conductivity increases by about two orders of magnitude with increasing the thickness from 45 to 250 nm. Moreover, the permittivity shows a higher dispersion step at lower frequencies in both samples due to the hopping conduction mechanism in addition to the interfacial polarization in such heterogeneous structures. Another small dispersion step is noticed in case of the lower thickness. It is attributed to the polarization of the accumulated charge carriers near the grain boundaries interfaces. No indication of any electrode phenomena in both samples is shown here.     

Determination of the radiation yield of hydrogels crosslinking

The ability of polymer to crosslink or exposure to radiation is frequently represented by a G value, the number of crosslinks per 100 eV absorbed. Several methods are available for its determination, the most frequent being the dose D_g required to form an incipient network since (with many systems) this corresponds to one crosslinked unit per weight average molecular (δ = 1). Its determination therefore depends on a knowledge of the molecular weight of the starting polymer. An alternative method, far less frequently used, is to measure the degree of swelling of a crosslinked network. This involves a knowledge of the Flory-Huggins interaction parameter μ and of the initial number average M_n(0). However if the concentration V_e of effective chains (deduced from swelling) is plotted against dose D, the slope gives G(X) directly, independent of M_n(0). This applies only when the system is very largely crosslinked. It may also be used to determine G(X) even when starting from the monomer itself (i.e. combining polymerization and crosslinking). It is shown that, for a series of polymers, irradiated either as liquids or in solution, the theoretical relation between swelling and crosslink density is followed, and the G(X) values derived from swelling compare well with those given in the literature, and based on gel fraction.     

Benzyl ether from phase transfer catalyzed strongly alkaline hydrolysis of benzyl chloride

The overall rate equation for the production of benzyl ether by phase transfer catalyzed strongly alkaline hydrolysis of benzyl chloride in the pseudo-steady state was derived. The effects of the concentrations and the sizes of the alkyl substituents of the catalysts, the concentration of hydroxide ions in the aqueous phase, the volume-fraction of the organic phase, the reaction temperature and the stirring speed on the production rate of benzyl ether can be explained with the derived rate equation. Under the conditions of 0.842 mol benzyl chloride, 50% aq. NaOH (2.5 mol NaOH), 42.2 mmol Bz(C₂H₅)₃NCl, 70 °C and 500 rpm, the reactions proceeded to nearly 100% benzyl ether within 2 h. The cocatalyst, NaI, is effective for improving the reaction rate, suitable amounts being ~ 5% of the substrate, benzyl chloride. The decomposition rate of the practical catalyst, Bz(C₂H₅)₃NCl, in 30% aq. NaOH at 70 °C is only about 3% per day. The conditions for producing benzyl ether by phase transfer catalyzed hydrolysis of benzyl chloride can be obtained from the rate equation and the experimental data.