Investigation of thermochemical Features of Gamma Irradiated Tryptophan Stereoisomers

In this work, the use of differential scanning calorimetry (DSC) is demonstrated as a powerful technique that can provide accurate thermodynamic property values of nutritional supplements such as tryptophan. Nutritional supplements require a decontamination procedure and irradiation appears as a promising technique for this purpose. The valuable properties of tryptophan for food and pharmaceutical industry as dietary supplement have led to increasing interest in its technological behaviour. L-, D- isomers and DL-racemic mixture of tryptophan irradiated and non-irradiated were studied by DSC. Irradiation was performed at room temperature with gamma radiations using a 137Cs source, the irradiation dose range was between 0.6- 10 kGy. Two steps decomposition pattern for both irradiated and non-irradiated samples up to 350 oC was found. Fourier transform infrared spectroscopic studies were performed. The obtained results indicate that the irradiation process does not inhibit the thermal properties of tryptophan when irradiated up to 10 kGy. The HPLC method was employed to evidence the degradation of the irradiated material. Resumen. En este trabajo, se demuestra el uso de calorimetría diferencial de barrido (DSC) como una técnica poderosa que puede proporcionar valores precisos de propiedades termodinámicas de suplementos nutricionales como el triptófano. Los suplementos nutricionales requieren un procedimiento de descontaminación y la irradiación aparece como una técnica prometedora para este propósito. Las valiosas propiedades del triptófano para la industria alimentaria y farmacéutica como suplemento dietético han provocado un creciente interés por su comportamiento tecnológico. Los isómeros L-, D- y la mezcla racémica DL- de triptófano irradiado y no irradiado fueron estudiados por DSC. La irradiación se realizó a temperatura ambiente con radiaciones gamma utilizando una fuente de 137Cs, el rango de dosis de irradiación estuvo entre 0.6 - 10 kGy. Se encontró un patrón de descomposición de dos pasos para muestras irradiadas y no irradiadas hasta 350 ºC. Se realizaron estudios espectroscópicos de infrarrojos por la transformada de Fourier. Los resultados obtenidos indican que el proceso de irradiación no inhibe las propiedades térmicas del triptófano cuando se irradia hasta 10 kGy. Se empleó el método HPLC para evidenciar la degradación del material irradiado.

Structure and Performance Attributes Optimization and Ranking of Gamma Irradiated Polymer Hybrids for Industrial Application

The selection of suitable composite material for high-strength industrial applications, from the list of available alternatives, is a tedious task as it requires an optimized structural performance-based solution. This study aimed to optimize the concentration of fillers, i.e., vinyl tri-ethoxy silane and absorbed gamma-dose, to enhance the properties of an industrial scale polymer, i.e., ultra-high molecular weight polyethylene (UHMWPE). The UHMWPE hybrids, in addition to silane, were treated with (30, 65, and 100 kGy) gamma dose and then tested for ten application-specific structural and performance attributes. The relative importance of attributes based on an 11-point fuzzy conversation was used for establishing the material assessment graph and corresponding adjacency matrix. Afterwards, the normalized values of attributes were used to establish the decision matrix for each alternative. The normalization was performed after the identification of high obligatory valued (HOV) and low obligatory valued (LOV) attributes. After this, suitability index values (SIVs) were calculated for ranking the hybrids that revealed hybrids 65 kGy irradiated the hybrid as the best choice and ranked as first among the existing alternatives. The major responsible factors were higher oxidation strength, a dense cross-linking network, and elongation at break. The values of the aforementioned factors for 65 kGy irradiated hybrids were 0.24, 91, and 360 MPa, respectively, as opposed to 0.54, 75, and 324 MPa for 100 kGy irradiated hybrids, thus placing the latter in second place regarding higher values of Yield Strength and Young Modulus. Finally, it is believed that the reported results and proposed model in this study will improve preoperative planning as far as considering these hybrids for high-strength industrial applications including total joint arthroplasty, textile-machinery pickers, dump trucks lining ships, and harbors bumpers and sliding, etc.

Improving photoluminescence, optical and electrical characteristics of PMMA films with gamma irradiation

Polymeric materials are macromolecules, essentially a combination of numerous repeated subunits. Polymers are innovative and advanced materials that currently have a strong impact on our daily lives. In recent years, polymer use has been prominent due to the materials’ distinctive properties; thus, they entered different fields of science, technology and industrial-biomedical applications.The improvement of photoluminescence, optical and electrical characteristics of non-conducting Poly(methyl methacrylate) (PMMA) films was studied. Upon gamma irradiation of various doses, the photophysical and electrical properties of PMMA films were investigated using photoluminescence spectroscopy, ultraviolet–visible (UV-Vis) spectroscopy and the LCR Meter Bridge Circuit technique. The fluorescent response improved the photoluminescence (PL) spectral emission peaks according to gamma values. Strong fluorescence peaks appeared with the highest gamma dose. The UV–Vis results revealed a significant red-shift in the absorption edge as gamma doses increased. This shift exhibits a continuous decrease in the energy band gap values (from 3.50 to 2.60 eV for direct transition and from 3.05 to 1.55 eV for indirect transition). This was due to the formation of carbon clusters, which led to an increase in the electrical conductivity and improved the dielectric parameters of the irradiated PMMA films. Among a variety of measurements presented and discussed in the present study, the electrical measurements showed improved electrical characteristics of gamma-irradiated PMMA films.