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.

Effect of Irradiation process on mango

Mango (Mangifera indica L.) is one of the choicest tropical fruit of the world and rightly designated as "King" of all fruits. It is a nutritionally important fruit being a good source of vitamin A, B and C and minerals. Post-harvest losses in mangoes have been estimated in the range of 25 to 40% from harvesting to consumption stage. Improved practices and preservation have a great impact on retaining mango fruit quality and on the supply chain. Nowadays food irradiation process is an engrained technology for the preservation of foods and food products. Three different kinds of ionizing radiation are applicable for food irradiation processes (Gamma-rays which is emitted from the radio-isotopes Cobalt-60 and Caesium-137, or electron beams and X-rays). Food irradiation can be considered an evolving technique that is capable of increasing the shelf-life, deferring the ripening and senescence of fruits, and thwart of microorganism activity along with insect infestation. Irradiated food is save for human health. This review article is focusing on irradiation effects on mango and the adoption of improved practices by the farmer for export besides that of food safety.

Role of thermal history on atomic structure and ductility of ion-irradiated metallic glasses

Maximizing the structural rejuvenation and ductility is one of the most heated debates in the field of metallic glasses (MGs). In this work, molecular dynamics (MD) simulation was implemented to model the ion irradiation effects on the Cu60Zr40 MG with different thermal histories and varied structural heterogeneities. The initial results indicated that the performance of an annealing-quench treatment on the MG induces the atomic configurations with different heterogeneities and potential energy values. The subsequent ion irradiation process also demonstrated that an optimized atomic structure was occurred for achieving maximum rejuvenation and ductility in the CuZr glassy alloy. It was unveiled that the intermediate initial heterogeneity provides an efficient pathway for maximizing the atomic rearrangements under the ion irradiation. It was also suggested that the medium population of Cu-centered clusters in the initial state facilitated the atomic rearrangements during the ion irradiation process. The structural characteristics and atomic reconfigurations for attaining the optimum ductility is discussed in details.

The Efficacy of a Diode Laser on Titanium Implants for the Reduction of Microorganisms That Cause Periimplantitis

The paper presents the optimisation of a safe diode laser irradiation process applied to the surface of titanium implants in order to reduce microbial numbers in the treatment of inflammation classified as periimplantitis. The study comprised isolation and identification of microorganisms inhabiting surfaces of dental implants, crowns, teeth and saliva from patients with fully symptomatic periimplantitis. Microorganisms were detected by a culture-dependent method and identified with the use of MALDI-TOF mass spectrometry. The isolated microorganisms were inoculated on the surface of a new implant and then irradiated by a diode laser (wavelength of 810 ± 10 nm) in one, two or three repetitions and biocidal efficacy was assessed. To evaluate impact of laser irradiation on roughness, morphology and structure of the implant surface, optical profilometry, scanning electron microscopy and optical microscopy were used. Examination of the tested surfaces and saliva revealed the presence of Gram-positive and Gram-negative bacteria and one fungal species. In all patients, cultures from the endosseous part of the implant revealed the presence of the pathogenic and pyogenic bacterium Streptococcus constellatus. In 13 out of 20 samples laser-irradiated in duplicate and triplicate, all microorganisms were eliminated. The irradiation used did not cause any changes in the properties of the implant surface.

Electron-Beam-Induced Grafting of Chitosan onto HDPE/ATZ Composites for Biomedical Applications

The surface functionalisation of high-density polyethylene (HDPE) and HDPE/alumina-toughened zirconia (ATZ) surfaces with chitosan via electron-beam (EB) irradiation technique was exploited for preparing materials suitable for biomedical purposes. ATR–FTIR analysis and wettability measurements were employed for monitoring the surface changes after both irradiation and chitosan grafting reaction. Interestingly, the presence of ATZ loadings beyond 2 wt% influenced both the EB irradiation process and the chitosan functionalisation reaction, decreasing the oxidation of the surface and the chitosan grafting. The EB irradiation induced an increase in Young’s modulus and a decrease in the elongation at the break of all analysed systems, whereas the tensile strength was not affected in a relevant way. Biological assays indicated that electrostatic interactions between the negative charges of the surface of cell membranes and the –NH3+ sites on chitosan chains promoted cell adhesion, while some oxidised species produced during the irradiation process are thought to cause a detrimental effect on the cell viability.

Investigations at the Product, Macromolecular, and Molecular Level of the Physical and Chemical Properties of a γ-Irradiated Multilayer EVA/EVOH/EVA Film: Comprehensive Analysis and Mechanistic Insights

Chemically and biologically safe storage of solutions for medical uses is a daily concern for industry since decades and it appeared even more dramatic during the last two years of pandemia. Biological safety is readily reached by sterilization using γ-irradiation process. However, such a type of irradiation induces the degradation and the release of chemicals able to spoil the biological solutions. Surprisingly, there are no investigations on multi-layer films combining multi-technique and multi-method approaches to unveil the events occurring during γ-irradiation. Furthermore, our investigations are focuses on properties/events occurring at product, macromolecular, and molecular levels.

ANALYSIS OF PACKAGING PRINT QUALITY WITH CTF AND CTCP PLATE MAKING SYSTEMS USING DUPLEX PAPER MATERIALS

Comparative analysis of packaging print quality was carried out on the printed output with reference to using Computer to Film (CtF) and Computer to Conventional Plate (CtCP). The comparison of the print results from the two systems is analyzed from cost, durability, and dot gain. In this analysis, 400 gram duplex paper was used and two types of print references were used, namely CtF and CtCP. The pre-printing equipment used is the manufacture of conventional printing plates and plates. What is achieved when observing is comparing two print references with the help of a quality control (QC) tool. Before comparing the two print references, direct printing is done with the two print references, using an offset machine. The differences that exist in CtF and CtCP are caused by different irradiation processes. CtF goes through two irradiation processes while CtCP is in the irradiation process using only lasers. The irradiation process using a laser is uneven and makes the plate not get a raster (neat) result. This process is very influential with the result of the trigger. CtF goes through an iterative process but the results appear better than CtCP.Keywords— Print packaging, Duplex, CtF, CtCp

Research on the Homogenized Postirradiation Elastoplastic Constitutive Relations for Composite Nuclear Fuels

A multi-scale finite element method is developed to simulate the irradiation process and postirradiation uniaxial tensile tests for metal-matrix composite fuels with representative volume elements (RVEs). The simulations of irradiation process are implemented under a wide range of burnup levels, with the irradiation effects on the mechanical constitutive relations of fuel particles and matrix taken into account comprehensively. The simulation results for the macroscopic postirradiation true stress/strain curves are obtained, excluding the irradiation-induced macroscopic deformations. The effects of particle fission density, temperature, and initial particle volume fraction are investigated and analyzed. The research results indicate that 1) a quasi-elastic stage appears during the postirradiation tension, which is mainly induced by the creation of high residual compressive stresses in the particles and matrix after irradiation; 2) with the increase of effective strains, new plastic deformations increase in the particles and matrix to result in the macroscale plastic stage; 3) the macroscale irradiation softening and hardening phenomena appear, which mainly stem from the weakened deformation resistance by the irradiation-induced plastic deformations in the matrix, the enlarged particle volume fraction after irradiation, and the irradiation hardening effects of metal matrix.