Egg attributes and hatchling mass as predictors of hatchling growth on a Nile crocodile (Crocodylus niloticus) farm

Rapid growth of Nile crocodile (Crocodylus niloticus) hatchlings on farms shortens the time to slaughter for skins, thus reducing costs and improving farm efficiency. The aims with the project were to assess the utility of various egg attributes (length, width, volume, mass and density) as predictors of hatchling mass (HMinitial) for 269 eggs from 15 clutches and to assess these egg attributes, HMinitial and egg productivity as predictors of the mass of the hatchlings 68–75 days after hatching (HMend). Hatchlings heavier than 61,5 g were individually marked and assigned to five pens according to HMinitial until the HMend of 129 hatchlings was determined. Strong and meaningful positive, linear relationships existed between HMinitial and all egg attributes except egg density, where the relationship was strong and negative (P < 0,001). HMend varied widely across as well as within clutches. It is most compatible with the data that HMinitial (P = 0,08) and egg productivity (P = 0,02) have meaningful negative relationships with HMend when all five pens are included in the model. Considering pens separately, the direction of the relationship between HMinitial and HMend was negative for three pens and neutral for two. The direction of the relationship between egg productivity and HMend was negative for four pens and positive for one. The models that each included one predictor as well as pen only explained 8–14% of the variation in HMend, suggesting that factors other than those studied largely affected growth.Nylkrokodilbroeilinge (Crocodylus niloticus-broeilinge) wat vinniger groei op plase kan vroeër geslag word vir hulle velle, wat koste verminder en plaasdoeltreffendheid verhoog. Die projek se doel was om die nut van verskeie eierattribute (lengte, wydte, volume, massa en digtheid) as voorspellers van broeilingmassa (BMbegin) vir 269 eiers van 15 broeisels te bepaal, en om hierdie eierattribute, BMbegin en eierproduktiwiteit as voorspellers van die massa van die broeilinge 68–75 dae ná uitbroeiing (BMeinde) te beoordeel. Broeilinge swaarder as 61,5 g is individueel gemerk en volgens BMbegin aan vyf hokke toegewys, totdat die BMeinde van 129 broeilinge bepaal is. Sterk, betekenisvolle, positiewe, lineêre verbande bestaan tussen BMbegin en al die eierattribute behalwe eierdigtheid, waar die verband sterk en negatief was (P < 0,001). BMeinde het baie tussen en binne broeisels gevarieer. Dit is die beste versoenbaar met die data dat BMbegin (P = 0,08) en eierproduktiwiteit (P = 0,02) betekenisvolle negatiewe verbande met BMeinde het wanneer al vyf hokke by die model ingesluit is. Vir hokke wat afsonderlik beoordeel is, was die rigting van die verband tussen BMbegin en BMeinde negatief vir drie hokke en neutraal vir twee. Die rigting van die verband tussen eierproduktiwiteit en BMeinde was negatief vir vier hokke en positief vir een. Die modelle wat elk slegs een voorspeller en hok as koveranderlike ingesluit het, verklaar 8–14% van die variansie in BMeinde, wat aandui dat ander faktore as dié wat bestudeer is groei grootliks beïnvloed.The National Research Foundation.http://www.satnt.ac.zaam2022Production Animal Studie

Kinetics of solid-state reactions between zirconium thin film and silicon carbide at elevated temperatures

Solid state reactions between a thin film (133 nm) of Zr and bulk single crystalline 6H-SiC substrates have been studied at temperatures between 600 °C and 850 °C for durations of 30, 60 and 120 min under high vacuum conditions. The deposited film and reaction zones were investigated by Rutherford backscattering spectrometry (RBS) and X-ray diffraction. The RBS spectra were simulated in order to obtain the deposited layer thickness, reaction zone compositions and reaction zone thickness. The as-deposited spectra fit well with those annealed at 600 °C, thus showing there were no reactions taking place. At temperatures of 700 °C and above, Zr reacted with the SiC substrate and formed a mixed layer of Zr carbide (ZrCx) and Zr silicides (ZrSi, Zr2Si and Zr5Si3). Annealing at 850 °C for 240 min revealed that all the deposited Zr had completely reacted. The interface reaction follows the parabolic growth law thereby indicating diffusion controlled reaction kinetics. The activation energy for the diffusion process obtained was 1.6 eV in the relatively narrow temperature range 700–850 °C.http://www.elsevier.com/locate/nimbhb201

In-situ RBS studies of strontium implanted glassy carbon

The diffusion behaviour of strontium in glassy carbon was investigated using in-situ real time Rutherford backscattering spectrometry. The sample was annealed in vacuum from room temperature to 650 oC. Diffusion of the implanted strontium towards the bulk was observed after annealing at temperatures ranging from 450 oC – 560 oC. The diffusion depth was limited to the end-of-ion-range region where there were still some radiation damage present.No diffusion into the pristine glassy carbon was observed suggestion that diffusion of Sr in glassy carbon can only occur in regions with radiation damage. Annealing the sample at higher temperatures higher than 560 oC resulted in migration of the implanted strontium towards the surface of the glassy carbon substrate. The amount of the accumulated strontium at the surface increased as the annealing temperature is increased. The RBS spectra obtained after annealing the sample isothermally at 650 oC for 2 hours show that there was no further diffusion and accumulation of the strontium during this period.http://www.journals.elsevier.com/vacuum2017-04-30hb2017Physic

Interface reactions between Pd thin films and SiC by thermal annealing and SHI irradiation

The solid-state reactions between Pd thin films and 6H-SiC substrates induced by thermal annealing, room temperature swift heavy ion (SHI) irradiation and high temperature SHI irradiation have been investigated by in situ and real-time Rutherford backscattering spectrometry (RBS) and Grazing incidence X-ray diffraction (GIXRD). At room temperature, no silicides were detected to have formed in the Pd/SiC samples. Two reaction growth zones were observed in the samples annealed in situ and analysed by real time RBS. The initial reaction growth region led to formation of Pd3Si or (Pd2Si+Pd4Si) as the initial phase(s) to form at a temperature of about 450 °C. Thereafter, the reaction zone did not change until a temperature of 640 °C was attained where Pd2Si was observed to form in the reaction zone. Kinetic analysis of the initial reaction indicates very fast reaction rates of about 1.55×1015 at.cm-2/s and the Pd silicide formed grew linear with time. SHI irradiation of the Pd/SiC samples was performed by 167 MeV Xe26+ ions at room temperature at high fluences of 1.07×1014 and 4×1014 ions/cm2 and at 400 °C at lower fluences of 5×1013 ions/cm2. The Pd/SiC interface was analysed by RBS and no SHI induced diffusion was observed for room temperature irradiations. The sample irradiated at 400 °C, SHI induced diffusion was observed to occur accompanied with the formation of Pd4Si, Pd9Si2 and Pd5Si phases which were identified by GIXRD analysis.http://www.elsevier.com/locate/nimb2017-03-31hb2016Physic

Diffusion of a mono-energetic implanted species with a Gaussian profile

The implanted profile in an isotropic substrate of a mono-energetic ion species is usually very near a Gaussian profile. An exact solution to the time-dependent Fick diffusion equation of an initially Gaussian profile is presented. This solution is a general one also covering the diffusion within the two limiting cases usually considered in solutions to the Fick equation, viz. a perfect sink at the surface and a perfectly reflecting surface plane at the surface. An analysis of the solutions for these two cases shows that at small diffusion times the main effect of annealing is a nearly symmetric broadening of the implanted profile. At the origin and for longer diffusion times the profile deviates significantly from Gaussian. A review is also given of past attempts to extract diffusion coefficients by fitting experimental data to approximate equations based on simplified initial profiles.http://www.elsevier.com/locate/nimb2018-09-01hj2018Physic

Surface and interface modification of Zr/SiC interface by swift heavy ion irradiation

In this study thin Zr films (135 nm) were deposited on 6H-SiC substrate at room temperature by sputter deposition. The Zr/SiC couples were irradiated by 167 MeV Xe26+ ions at room temperature at fluences of 5.0 1012, 1.0 1013, 5.0 1013, 2.0 1014, 3.1 1014 and 6.3 1014 ions/cm2. The samples were analysed before and after irradiation using Rutherford backscattering spectroscopy (RBS), atomic force microscopy (AFM) and secondary electron microscopy (SEM). The surface morphology from SEM analysis revealed a homogeneous Zr surface which did not vary with increasing fluences of irradiation. AFM analysis revealed that the Rrms surface roughness did increase from the as-deposited value of 1.6 nm and then decrease at higher SHI irradiation fluences to 1.4 nm. RBS results indicate that interface mixing between Zr and SiC interface occurred and varied linearly with irradiation ion fluence. The value obtained for diffusivity of Zr shows that the mixing was due to interdiffusion across the interface during a transient melt phase according to the thermal spike model.http://www.elsevier.com/locate/nimb2016-07-01hb201

Endoscopic lung volume reduction in severe emphysema

Therapeutic options in severe emphysema are limited. Endoscopic lung volume reduction (ELVR) refers to bronchoscopically inducing volume loss to improve pulmonary mechanics and compliance, thereby reducing the work of breathing. Globally, this technique is increasingly used as treatment for advanced emphysema with the aim of obtaining similar functional advantages to surgical lung volume reduction, while reducing risks and costs. There is a growing body of evidence that certain well-defined subgroups of patients with advanced emphysema benefit from ELVR, provided that a systematic approach is followed and selection criteria are met. In addition to endobronchial valves, ELVR using endobronchial coils is now available in South Africa. The high cost of these interventions underscores the need for careful patient selection to best identify those likely to benefit from such procedures

Recommendations for the use of endoscopic lung volume reduction in South Africa: Role in the treatment of emphysema.

Emphysema is a very common cause of morbidity and mortality in South Africa (SA). Therapeutic options in severe emphysema are limited. Endoscopic lung volume reduction (ELVR) is increasingly being used internationally for the treatment of advanced emphysema in a subset of patients with advanced disease, aiming to obtain the same functional advantages as surgical lung volume reduction while reducing risks and costs. In addition to endobronchial valves, ELVR using endobronchial coils is now available in SA. The high cost of these interventions underscores the need for careful patient selection to best identify those who may or may not benefit from ELVR-related procedures. The Assembly on Interventional Pulmonology of the South African Thoracic Society appointed a committee comprising both local and international experts to extensively review all relevant evidence and provide advice on the use of ELVR in SA based on published evidence, expert opinion and local access to the various devices

Structural modification of indium implanted glassy carbon by thermal annealing and SHI irradiation

Please read abstract in the article.The National Research Foundation (NRF) (grant no. 110363) of South Africahttp://www.journals.elsevier.com/vacuum2018-10-30hj2017Physic