Carbon nanotubes growth on sub-surface catalyst layer of Cu–Ni nanoparticles thin film

Cu–Ni nanoparticles (NPs) thin films were prepared by Direct Current (DC) magnetron sputtering with Cu and Ni targets. The products were used as catalysts for Thermal CVD (TCVD) growing of carbon nanotubes (CNTs) from acetylene gas at 825°C. In order to characterize the nano catalysts, X-ray Diffraction (XRD) and Atomic Force Microscopy (AFM) and to study the synthesized CNTs Scanning Electron Microscopy (SEM) and Raman Spectroscopy were applied. A remarkable CNT grown on the sub-surface of catalyst layer compared to its top is deduced from SEM images. Despite the poor catalytic activity of the top-surface, these considerations led us to conclude more catalytic activity of the sub-surface.     

Impaired final follicular maturation in heifers after superovulation with recombinant human FSH

The aim of this study was to investigate whether human FSH without contaminating LH can exert a normal superovulation response in cows. One group of heifers (n = 9) was stimulated with recombinant human FSH (rhFSH), an FSH source without any LH activity, and another group (n = 9) was treated with equine chorionic gonadotrophin (eCG), an FSH source with high LH activity. Daily transrectal ultrasonography showed that eCG- and rhFSH-stimulated heifers (n = 9 per group) had the same follicular growth characteristics and equal numbers of follicles > 8 mm in diameter after 3 days of stimulation. The treatment groups differed considerably in steroid production: rhFSH-treated heifers produced much lower oestradiol concentrations than did eCG-stimulated heifers during the first days of stimulation and much lower progesterone concentrations in the period after the LH surge. During the 27-35 h after prostaglandin injection, rhFSH-treated heifers had fewer LH pulses than did eCG-treated heifers (0.3 versus 3.0 per heifer, respectively; n = 3 per group). All rhFSH-treated heifers (n = 6) underwent a preovulatory LH surge, but this occurred significantly later than in the eCG-treated heifers (n = 4; 39.4 +/- 1.9 h versus 47.1 +/- 1.5 h in rhFSH- and eCG-treated heifers, respectively). Multiple ovulations occurred in only three of six rhFSH-treated heifers, but in all four eCG-treated heifers with an LH surge. At 24 h after the LH surge, the percentage of metaphase II stage oocytes with cortical granules distributed close to the oolemma was significantly lower in the rhFSH group (7.3%) than in the eCG group (55.9%). In conclusion, final follicular maturation is impaired in heifers treated with rhFSH, which might be due to the combination of a lack of LH activity in the gonadotrophin preparation and the severe suppression of LH pulsatility.     

Isolation and purification of type A spermatogonia from the bovine testis

The aim of this study was to isolate and purify bovine type A spermatogonia. Testes from 5-7-month-old calves were used to isolate germ cells using a two-step enzymatic digestion. During the isolation and purification steps, the viability of cells was determined using live/dead staining. The identity of type A spermatogonia during isolation and purification was determined under a light microscope equipped with a Nomarski lens. Isolated cells were characterized further by using specific markers for type A spermatogonia, including Dolichos biflorus agglutinin (DBA) and c-kit. The cell suspension was transplanted into immunodeficient recipient mouse testes and the colonization was assessed 1-3 months after transplantation, to assess the stem cell population among the isolated cells. After isolation, a cell suspension was obtained containing about 25% type A spermatogonia, which was enriched further by differential plating and separation on a discontinuous Percoll gradient. Finally, fractions containing 65-87% pure type A spermatogonia were obtained. Large and small type A spermatogonia with different numbers and sizes of nucleoli were found. DBA stained both large and small type A spermatogonia and its application in fluorescence-activated cell sorting (FACS) resulted in comparable percentages of type A spermatogonia to those determined by morphological examination under a light microscope equipped with a Nomarski lens. Nearly all of the large type A spermatogonia showed strong c-kit immunoreactivity, indicating that these cells had undergone at least an initial differentiation step. In contrast, approximately half of the small type A spermatogonia were negative for c-kit, indicating the presence of the spermatogonial stem cells in this population. At 3 months after transplantation, groups of bovine type A spermatogonia were found in most tubule cross-sections of the recipient mouse testes, showing the presence of spermatogonial stem cells among the isolated cells.     

Extraction of polyphenolic dyes from henna,pomegranate rind,and Pterocarya fraxinifolia for nylon 6 dyeing

Acid and disperse dyes are two well‐known synthetic materials that are primarily used for dyeing of nylon 6 fibres. Despite their good performance, several negative impacts on the environment, including air and water pollution, are major concerns to researchers. An alternative ecofriendly approach to the dyeing of nylon 6 is the use of natural dyes, given their abundant natural sources, biocompatibility, biodegradability, non‐toxicity, non‐allergic responses, and non‐carcinogenic effects on human life. Based on these advantages, we extracted polyphenolic dyes from henna leaves, pomegranate rind, and Pterocarya fraxinifolia leaves and studied the dyeability on nylon 6 fabric using three compounds of aluminium sulfate, tannic acid, and tin chloride as toxic and non‐toxic mordants before dyeing. Fourier transform infrared spectra of the nylon 6 fabric confirmed the coordination complexes and π–π bonding between the mordants and the dyes. Colorimetric and fastness results showed that the mordants increased the colour strength and improved the fastness properties of the fibres. Our results suggest that tin chloride and aluminium sulfate as metal mordants can be successfully replaced with tannic acid as a biomordant in the natural dyeing of nylon 6. Also, cost assay showed that dyeing of nylon 6 with extracted natural dyes from waste leaves could be a sustainable and economical substitute for synthetic dyeing.     

Autologous and homologous transplantation of bovine spermatogonial stem cells

The aim of this study was to develop a method for spermatogonial stem cell transplantation into the bovine testis. Five-month-old Holstein-Friesian calves were used and half of the calves were hemicastrated to allow autologous transplantation and the other half were used for homologous transplantation. Approximately 20 g of each testis was used for cell isolation. On average 106 cells per gram of testis containing about 70% type A spermatogonia were isolated. The cells were frozen in liquid nitrogen until transplantation. Testes were irradiated locally with 10-14 Gy of X-rays to deplete endogenous spermatogenesis. At 2 months after irradiation, cells (approximately 10 x 10(6) were injected into the rete testis through a long injection needle (18 gauge), using ultrasonography and an ultrasound contrast solution. At 2.5 months after transplantation, calves were castrated and samples of testes were taken for histological examination. After 2.5 months in the irradiated non-transplanted control testes, only 45% of the tubules contained type A spermatogonia. However, after autologous spermatogonial transplantation, >80% of the tubule cross-sections contained type A spermatogonia. In addition, only 20% of the tubules of the control testes contained spermatocytes and, except for a few tubules (5%) with round spermatids, no more advanced germ cells were found. After autologous spermatogonial transplantation, about 60% of the tubules contained spermatocytes; 30% contained spermatids and in about 15% of tubules spermatozoa were found. No improvement in spermatogonial repopulation was found after homologous transplantation. The results of this study demonstrate, for the first time, successful autologous transplantation of bovine spermatogonial stem cells resulting in a complete regeneration of spermatogenesis.     

Selective Degradation of Lignin Polymer by Chlorine Dioxide During Chemical Pulp Delignification in Flow Through Reactor

The delignification of pulp in a conventional batch reactor provides convenient conditions for inutile secondary reactions in which ClO₂ reacts with oxidized aromatic units of lignin. In this study the flow-through reactor was applied to minimize secondary reactions. The obtained results showed that the removal of oxidized lignin from the reaction zone significantly enhanced the ClO₂ reaction toward non-oxidized units of lignin. Application of an organic solvent-water solution, bleaching liquor, significantly increased the removal of oxidized lignin and decreased considerably the secondary reactions. Although this technique considerably improved ClO₂ effective efficiency, large amounts of chlorate formation decreased the overall effect of improved ClO₂ global efficiency.     

Prevailing Cu-C Nanocomposite over Cu NPs for CNTs Growth: A Catalyst Study on Silicon Substrate

Silicon - Copper nanoparticles in carbon thin films (Cu NPs @ a-C: H) were prepared with various copper and carbon content by co-deposition of RF-sputtering and RF-PECVD method to use as catalysts...