Enhancement on the generation of amplified spontaneous emission in thulium-doped silica fiber at 2 μ m

This paper investigates the generation of the amplified spontaneous emission (ASE) from thulium-doped silica fiber pumped at 1570 nm and 793 nm. The developed model provides the ASE spectral power as functions of the fiber length and the pump power under single-pass forward (SPF) and double-pass bi-directional (DPB) pumping schemes. A broadband ASE source generated by solving a set of rate and propagation equations for 1570 nm and 793 nm pumping transitions, and taking into account the influences of cross relaxation (CR) in both pump schemes. Our findings reveal that for 1570 nm pumping scheme, CR transition reduces the ASE generation. In addition, longer fluorescent lifetime increases the ASE power and reduces the pump power threshold. We numerically enhanced the generation of ASE broadband source from 1570 nm/1570 nm DPB pumping scheme. Our results show that 1570 nm/1570 nm DPB produces broadband ASE source with high slope efficiency and broader spectral bandwidth than that in SPF configuration. As a result, a 1570 nm/1570 nm DPB pump scheme is a suitable configuration to obtain higher power efficiency and a wider broadband source for the chosen thulium-doped silica fiber characteristics

Thermal and experimental analysis of cross-flow closed cooling tower

Background: Cross-flow closed cooling towers (CCCT) are an indirect-contact evaporative cooler in which ambient air, spray water, and process fluid work together. The thermal performance of this cooling tower has significant impact on the thermal performance of the system in which it is implemented. CCCT introduces considerable difficulty in its thermal analysis particularly because it has two-dimensional analysis in its heat characteristics. Methods: In this work, a novel correlation between the tower effectiveness (ε) and its number of transfer units (NTU) was developed to simulate analytically the thermal performance/design of CCCT. This relationship is featured by its simplicity in use and has non-iterative procedure to be employed as the traditional one in the literature. Results: The new relationship was verified through comparison with experimental work. The simulated results from the new model show a satisfactory agreement with those obtained from the our experimental work of less than ±5%, less than ±2% difference from experimental work done by Jiang et al. [8], and with deviation of −3.89% from those obtained by Krӧger [9]. On the other hand, there is a good agreement between the present model and those obtained from the traditional ԑ-NTU method with maximum deviation of −4.56%. Conclusions: These new correlations are handy to be used by the process engineer or CCCT designer and they are featured by direct input parameters and no need for iterative process

Adsorption Studies of the Effect of Thiosemicarbazides on the Corrosion of Steel in Phosphoric Acid

The corrosion inhibition of steel in phosphoric acid by thiosemicarbazide derivatives has been studied using different chemical and electrochemical techniques. The observed order of increasing inhibition efficiency was correlated with changes in the molecular structures of the inhibitors. Potentiodynamic polarization curves indicate that the compounds are mixed-type inhibitors. Electrochemical impedance spectroscopy has been used successfully to evaluate the performance of the inhibitors. AC measurements showed that the dissolution process was activation-controlled. The kinetic–thermodynamic model and the Flory–Huggins adsorption isotherm described the experimental findings well. The number of active sites, binding constant and change in free energy were computed for all the inhibitors studied. It was found that the inhibitor molecule was adsorbed through more than one active centre and occupied more than one active site on the steel surface

Saponin content in alfalfa landraces and cultivars in Ismailia, Egypt

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Spectrophotometric analysis of two eye preparations, vial and drops, containing ketorolac tromethamine and phenylephrine hydrochloride binary mixture and their ternary mixture with chlorphenirmaine maleate

Ketorolac tromethamine, KTC and phenylephrine hydrochloride, PHE binary mixture is co-formulated as eye vial, while their ternary mixture with chlorpheniramine maleate is co-formulated as eye drops. The existing work utilizes different spectrophotometric methods which are considered to be simple and rapid for the determination of both mixtures. These methods include: zero-order (D0), first derivative (D1), derivative (DR) or difference ratio (R.D), delta absorbance (ΔA) and finally convolution of derivative data using discrete Fourier functions (FFD). In the binary mixture, KTC is assayed using D0, D1 and ΔA methods with no interference from PHE, while PHE needed some spectroscopic treatments for its analysis due to the spectral overlap of KTC with its maximum wavelength (λmax) at 273 nm. Such treatments involve D1 R.D, D2R, FFD2 and ΔA methods. In the ternary mixture, KTC is assayed using D0 and D1 with no interference from both PHE and CPM, while R.D, D1R and FFD2 are used to assay both PHE and CPM to resolve the overlap in their spectra. Linear regression lines were obtained over the concentration ranges 1–18 and 6–48 μg.mL−1 for KTC and PHE (binary mixture), respectively and 2–9, 1–18 and 2–9 μg.mL−1 for CPM, KTC and PHE (ternary mixture), respectively yielding high correlation coefficients values (higher than 0.999). The lowest LOQ value for KTC (0.46 μg.mL−1) was obtained upon using the D1 method in the binary mixture while the R.D method yielded the lowest LOQ values for both PHE (0.34 μg.mL−1) and CPM (0.97 μg.mL−1) in the ternary mixture

The Metabolic Impact of Vitamin D on the Context of Metabolic Syndrome

Vitamin D deficiency is one of the major affecting factors on metabolic syndrome, cancer, cardiovascular diseases, and type 2 diabetes mellitus. So we aimed in our study to show the anti-diabetic effects of vitamin D on type 2 diabetic rats. Therefore, 45 rats were divided into three groups (15 rats per each group). The first group served as a control and fed on a standard chow diet while the other two groups served as diabetic groups as they fed on high fructose, high fat, and high sucrose diet and for 12 weeks then they injected with intraperitoneal single dose (45 mg/kg b.wt) of STZ dissolved in cold 0.01 M citrate buffer (pH 4.5) to develop type 2 diabetes mellitus. After one week of injection the third diabetic group was treated for 4 weeks with two intramuscular (20,000 IU/Kg) of vitamin D dissolved in sesame oil. The obtained results demonstrated that administration of vitamin D could improve serum glucose and insulin levels with an increase in serum calcitonin and calcium in correlation with the decrease in parathyroid hormone, phosphorus and lipids levels in the presence of significant upregulation of gene expression in liver (PPARα, GLP-1, and IGF-1) and in adipose tissue (Ptch, Smo, Gli-1, and hhip). In conclusion, vitamin D administration can improve insulin resistance by improving blood glucose and insulin levels

The Metabolic Impact of Vitamin B12 in The Context of Metabolic Syndrome

Metabolic syndrome (Mets) refers to a group of symptoms that increasing the risk of heart disease, stroke and type 2 diabetes (T2DM). One of the most difficult health issues facing the world today is diabetes mellitus (DM). In diabetes, chronic hyperglycemia can cause both immediate and delayed consequences. Cobalamin, or vitamin B12, is a water-soluble vitamin essential for proper neuronal and vascular function, normal hemopoiesis, and DNA synthesis. The aim of this study was to determine the impact of vitamin B12 in the streptozotocin (STZ)-induced diabetic rats. In this study, 30 males’ rats were divided into three groups, for a period of 9 weeks, the rats were injected with vitamin B12. Serum lipid levels, some biochemical, molecular parameters and histopathology of liver and brain tissues were determined. Our results demonstrated that compared to rats in the diabetic groups, the vitamin B12 reduced glucose, insulin, HOMA-IR, glycated haemoglobin (HbA1c), cholesterol, triacylglycerol (TAG), high density lipoprotein-cholesterol (HDL-c), low-density lipoprotein-cholesterol (LDL-c) levels, and Malondialdehyde (MDA), while vitamin B12 increased vitamin 12, glutathione peroxidase (GPx), catalase (CAT), and superoxide dismutase (SOD) levels (P < 0.05). An upregulation was found in the gene expression in the homogenate of hepatocyte growth factor (HGF), leptin receptor (LEPR), and glucose transporter -2 (GLUT-2). On the other hand, there was a significant downregulation in the mRNA expression of Janus kinase3 (JAK3), signal transducer and activator of transcription3 (STAT3), Transforming growth factor–β (TGF-β), and protein tyrosine phosphatase 1B (PTPN1). In conclusion our findings suggested that vitamin B12 supplementation can mitigate the Impact of an STZ in diabetic rats. This new research provides further evidence that vitamin B12 may be useful as a treatment for diabetes