Ion implantation into aluminum and copper by a beam of carbon nanoparticles from regenerative sooting discharges

We present a new technique to generate light carbon nanoparticles from regenerative sooting discharges and its use for ion implantation on aluminum and copper surfaces at an energy of 40 keV. Films formed at fluences up to 3 × 10¹⁵ C⁺/cm² for aluminum and 10¹⁶ C⁺/cm² for copper are studied using Raman spectroscopy, X-ray diffraction and atomic force microscopy. Raman spectroscopy reveals the existence of graphite and diamond like structures in all samples. Precipitates of Al₄C₃ of rhombohedral and hexagonal types were found in the nanometer ranges from the X-ray diffraction pattern for aluminum samples and the probable formation of body-centered cubic diamond and hexagonal carbon in copper samples. The average grain sizes of Al₄C₃ were calculated ～40 nm for Al and ～35 nm for Cu. Mass spectra from a graphite hollow cathode duoplasmatron ion source are also presented. Atomic force microscopy images of a Cu sample also support the existence of 46 nm structures. Light carbon nanoparticles are readily available from the ion source in which a special carbonaceous environment creates regenerative soot. Support gas Ar produces more C₃ than Ne.     

Effect of temperature on the formation and dissolution of anodic oxide films on titanium in acid solutions

The effect of electrolyte and current density on the growth rate of the oxide film on titanium were studied by following the voltage-time characteristics. The barrier oxide grows to greater thickness at lower pH and higher current density. The growth of the oxide in acid medium is lowered by an increase in temperature. In 0.5n H₂SO₄ the oxide grows to greater thicknesses than that grown in 0.5n HCLO₄. This is due to a relatively higher rate of dissolution in HClO₄ during the oxide-growth/oxide-dissolution process during the anodization. The effect of temperature on the dissolution of the oxide previously grown to 12.5 V is followed in 0.5n H₂SO₄ by impedance and potential measurements. The oxide, which is of duplex nature, dissolves with a rate that increases with increasing temperature. The results indicate that the rate of dissolution of the outer layer is affected by temperature more than that of the inner layer, probably owing to higher porosity of the former. The heat of activation, -H, was estimated to be 110.5 kJ mol^–1.     

Formation of porous α-alumina from ammonium aluminum carbonate hydroxide whiskers

Ammonium aluminum carbonate hydroxide (AACH) whiskers prepared by hydrothermal technique were employed as precursor material for development of porous alumina. After compaction of AACH whiskers at 8 bars, calcination was performed at 650?°C followed by sintering at different temperatures. The sintered samples were characterized by XRD, FTIR, SEM and mercury intrusion porosimetry. Mechanical strength was determined by compression testing. At sintering temperatures of 1200?°C to 1400?°C, the % age porosity was around 80%. At 1500?°C, the percentage porosity decreased to 71%. The as-prepared AACH consisted of bundles of whiskers with diameters as thick as 0.7?µm, while an individual whisker had a diameter of about 100?nm with an aspect ratio of about 33. A two-phase mixture consisting of θ- and α-alumina was obtained at 1100?°C, while at 1200?°C and above, single phase α-alumina was formed. θ-alumina retained the bundle-like morphology. However, transformation to α-alumina was accompanied by formation of bead-like morphology. These beads were joined together through necks/stems within the whiskers as well as across the parallel-lying whiskers. These necks grew at 1300?°C to form aggregates with smooth surfaces. At 1400?°C, these aggregates started joining with each other by neck formation and at 1500?°C, a three-dimensional network was formed. For sintering temperatures of up to 1400?°C, pores with sizes around 260?nm were very stable. At 1500?°C, significant pore growth took place along with an overall densification. Therefore, number of pores with sizes of around 260?nm decreased and those with sizes around 10?µm, 1?µm and 5?nm increased. The compression strength of samples sintered at 1100?°C to 1300?°C was in the range of 3.4–4.3?MPa. At 1400?°C, the strength increased to 5.2?MPa, while at 1500?°C, it jumped to 10.8?MPa due to the formation of three-dimensional network.     

Silicon Coating on Maize Seed Mitigates Saline Stress in Yermosols of Southern Punjab

Silicon - Silicon (Si) has been identified as a key nutrient in plants to lower the pressures of environmental stress. In pot experiment, seeds of different maize hybrids (Pioneer-1543,...     

Alleviation of diabetic nephropathy by zinc oxide nanoparticles in streptozotocin‐induced type 1 diabetes in rats

This study examines the effect of nanoparticles with zinc oxides (ZnONPs) on diabetic nephropathy, which is the primary cause of mortality for diabetic patients with end‐stage renal disease. Diabetes in adult male rats was induced via intraperitoneal injection of streptozotocin. ZnONPs were intraperitoneally administered to diabetic rats daily for 7 weeks. Diabetes was associated with increases in blood glucose level, 24‐h urinary albumin excretion rate, glomerular basement membrane thickness, renal oxidative stress markers, and renal mRNA or protein expression of transforming growth factor‐β1, fibronectin, collagen‐IV, tumour necrosis factor‐α and vascular endothelial growth factor‐A. Moreover, the expression of nephrin and podocin, and the mRNA expression of matrix metalloproteinase‐9 were decreased in the diabetic group. These changes were not detected in the control group and were significantly prevented by ZnONP treatment. These results provide evidence that ZnONPs ameliorate the renal damage induced in a diabetic rat model of nephropathy through improving renal functionality; inhibiting renal fibrosis, oxidative stress, inflammation and abnormal angiogenesis; and delaying the development of podocyte injury. The present findings may help design the clinical application of ZnONPs for protection against the development of diabetic nephropathy.     

Anions effect on the low temperature growth of ZnO nanostructures

Seed mediated aqueous chemical growth (ACG) route was used for the growth of ZnO nanostructures on Si substrate in four different growth mediums. The growth medium has shown to affect the morphology and the size of the different nanostructures. We observed that the medium containing zinc nitrate anions yields the nanorods, in a medium containing zinc acetate anions nano-candles are obtained. While in a medium containing zinc chloride anions ZnO nano-discs were obtained and in a medium containing zinc sulfate anions nano-flakes are achieved. Growth in these different mediums has also shown effect on the optical emission characteristics of the different ZnO nanostructures.     

Effect of chitosan penetration on physico-chemical and mechanical properties of bacterial cellulose

Bacterial cellulose-chitosan composites (BC-Ch) were prepared in order to obtain the BC-Ch composites with improved physico-mechanical characteristics. BC sheets were immersed in a Ch solution hoping that the Ch penetrates into the BC sheet. Ch penetration was observed according to variations in temperature, operation mode and treatment time. The morphological changes due to enhanced penetration were observed through FE-SEM, FT-IR and XRD analysis. FE-SEM analyses confirmed the formation of three dimensional multilayered structures in BC-Ch, whose thickness increased with Ch penetration. The FT-IR analysis showed intermolecular hydrogen bonding interaction between the BC and Ch molecules. XRD results revealed a slight decrease in the crystallinity index of the BC-Ch composites compared to pure BC. The mechanical properties, water holding capacity (WHC) and water release rate (WRR) of the BC-Ch composites were significantly improved compared to pure BC. The superior mechanical properties, WHC and water release rate would make the BC-Ch composites suitable for wound dressing and other biomedical applications.     

Effect of substrate biasing and temperature on AlN thin film deposited by cathodic arc ion

Aluminum nitride (AlN) films have been grown in pure N₂ plasma using cathodic arc ion deposition process. The films were prepared at different substrate bias voltages and temperatures. The aim was to investigate their influence on the Al macro-particles, structural and optical properties of deposited films. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, Scanning electron microscope (SEM) and Rutherford backscattering spectrometry (RBS) were employed to characterize AlN thin films. XRD patterns indicated the formation of polycrystalline (hexagonal) films with preferential orientation of (002), which is suppressed at higher substrate bias voltage. FTIR and Raman spectroscopic analysis were used to assess the nature of chemical bonding and vibrational phonon modes of AlN thin films respectively. FTIR spectra depicted a dominant peak around 850 cm^?1 corresponding to the longitudinal optical (LO) mode of vibration. A shift in this LO mode peak towards higher wavenumbers was observed with the increase of substrate bias voltage and temperature, showing the upsurge of nitrogen concentration in the deposited film. Raman spectra illustrated a peak at 650 cm^?1 corresponding to E₂ (high) phonon mode depicting the c-axis oriented (perpendicular to substrate) AlN film. SEM analysis showed the AlN film deposited at higher substrate bias voltage contains fewer amounts of Al macro-particles.     

RBS depth profiling and optical characterization of multilayers of TiO2 (20 nm) and Ge (15 nm)

Rutherford Backscattering Spectrometry (RBS) has been employed for studying inter-layer diffusion and mixing of TiO₂ and germanium in the multi-layers grown on the soda lime glass substrate. TiO₂ layers were grown by electron-beam evaporation of titanium in an oxygen atmosphere and Ge layers were grown by resistive heating. UV–visible and Raman spectroscopy were carried out for optical characterization. RBS spectra were analyzed by SIMNRA which confirmed the successful formation of alternate layers of TiO₂ and Ge with a thickness of 20 nm and 15 nm, respectively. Annealing caused interface mixing. The approximate stoichiometry of interfaces was of GeTiO₂. The thickness of these layers increased with annealing temperature. Two to five top Ge layers also underwent oxidation to form GeO and GeO₂, depending on annealing temperature. Nuclear Reaction Analysis (NRA) signal of oxygen from top layers was also recorded to confirm the pick-up of oxygen from the annealing atmosphere. An increase in the transmission efficiency with blue shift of the absorption edge was also observed with annealing temperature, as associated with the decrease in the effective thickness of Ge layers. Shift of Raman peaks confirmed the stoichiometric changes as a result of annealing.