Sun drying of cocoa with firebrick thermal storage materials

The thin-layer drying process of N38 cocoa beans using open-sun and a solar drying (SD) system with firebrick heat storage materials (FTSM) has been modeled. The 10 kg capacity force convective SD system was developed and used to carry out the experiments. The choice of the best model was based on a comparison of statistical indicators including determination coefficient (R²), reduced chi-square (χ²), root mean square error (RMSE), sum of square error (SSE), and normalized root mean square error (NRMSE) after fitting the experimental results to 11 common thin layer models in the literature. The results revealed that under open-sun drying and SD processes, the Midilli et al model provided the best drying characteristics of cocoa beans. Therefore, in the experimental context, this model can be assumed to reflect the solar/sun drying behavior of cocoa. The effective diffusivity values for the open-sun and SD of cocoa with FTSMA and FTSMB were 4.25× 10⁻¹¹, 6.64× 10⁻¹¹, and 5. 95 × 10⁻¹¹ m²/s respectively. The predicted pre-exponential factor and activation energy were 5.81 × 10⁻¹¹ m²/s and 22.79 kJ/mol respectively.     

Fungi and mycotoxins in cowpea (Vigna unguiculata L) on Nigerian markets

ABSTRACT

In this study, 81 samples of two cowpea varieties (brown: 54; white: 27) collected from various markets in southwestern Nigeria were examined for fungal and mycotoxin contamination. Moulds belonging to Aspergillus, Fusarium, and Penicillium were recovered from 99% of the samples. In both cowpea varieties, Aspergillus (52–53%) dominated Fusarium (29–30%) and Penicillium (17–20%). The interactive effect of cowpea variety and sampled location was significant (p = .013) on the occurrence of Fusarium species. Aflatoxins were detected in one brown and two white cowpea samples at concentrations reaching 209 and 84 µg/kg, respectively. Additionally, beauvericin was found in two samples of each cowpea variety, albeit at low concentrations. Cowpea presents as an alternative vegetable protein source to groundnuts in household nutrition with respect to mycotoxin contamination. Simple techniques to prevent mycotoxins in dry cowpeas are discussed.     

Tri-calcium phosphate ceramics and allografts as bone substitutes for spinal fusion in idiopathic scoliosis as bone substitutes for spinal fusion in idiopathic scoliosis: comparative clinical results at four years

The authors present the results of a comparative study of two series of posterolateral arthrodeses for scoliosis performed using COTREL DUBOUSSET instrumentation. Fifty-four consecutive patients underwent surgery for idiopathic scoliosis using the same technique. Thirty received a graft consisting of a mixture of corticocancellous autologous and allogenic bone frozen at -80 degrees, and 24 patients were grafted with a mixture of cortico-cancellous autologous bone and sticks of tricalcium phosphate (TCP, Biosorb, SBM, Lourdes, France). All patients were seen at three, six and twelve months, then once a year for at least four years with clinical and radiological evaluation at each visit. At the final follow up visit, no radiologic signs of pseudoarthrosis were found in either group with a minimum follow-up of 4 years. The appearance of bone callus was considered satisfactory at 6 months in all cases; moreover callus seemed to be more important in the TCP series, although this assessment was subjective. TCP resorption was total after 2 years, while allograft fragments were visible on x-rays after 2 years. Minor mechanical complications occurred but did not influence the results. Loss of correction was 8% of that initially obtained in the allograft group and 2% in the TCP group. Loss of correction did not progress after 6 months in the TCP group and after 2 years in the allograft group. Based upon this experience, the use of synthetic bone substitutes such as TCP would appear to be a valuable alternative to allografts in posterolateral spinal arthrodesis for idiopathic scoliosis, and it would eliminate the risk of viral contamination inherent to allograft implantation. To our knowledge, there have been no previous comparative studies concerning the use of tricalcium phosphate versus allograft in the literature.     

In pigs, inhaled nitric oxide (NO) counterbalances PAF-induced pulmonary hypertension

In 6 anesthetized mechanically ventilated pigs we have studied the effects of inhalation of 80 ppm of nitric oxide (NO) before and after platelet-activating factor (PAF) administration (50 ng/kg iv). Our results show that NO inhalation causes a decrease in pulmonary arterial pressure and in heart rate without affecting other circulatory parameters. PAF administration causes a pulmonary hypertension and a prompt and brief decrease in systemic pressure. Inhalation of NO reduces the pulmonary hypertension, without completely reversing PAF-dependent vasoconstriction. PAF administration to pigs pretreated with indomethacin produces a lesser increase in pulmonary vascular pressure. In this case, NO inhalation can restore to baseline values. Pretreatment of 3 of the 6 pigs with NG-nitro-L-arginine-methyl-ester did not prevent the prompt and brief PAF-induced systemic hypotension. In conclusion, our results show that NO reduces basal pulmonary vascular tone, acts as a pulmonary vasodilator on PAF-preconstricted vessels and is not involved in the brief systemic hypotension consequent to PAF administration.     

A reasonably practical XUV laser for applications

We describe a laboratory-scale 109 nm Xe Auger laser pumped by an all-commercial high-repetition-rate Nd:YAG laser system. The Xe laser provides pulse energies up to 1 μJ, and an average flux of 3×10 ¹² photons/s at 11.5 eV. Measurements of the gain, output energy, and output beam shape are reported, along with an investigation of the time dependence of the gain     

Order and mechanical properties of the γ matrix of superalloys

Single crystals of the γ matrix of the superalloy MC2 have a higher yield stress than that of the γ matrix of a similar alloy AM3, both being nickel-based but of complex composition. Diffuse neutron scattering indicates that in the matrix of MC2 long-range order of L1₂ type is stronger than in AM3. Local order of the DO22 type, as compared with AM3 enhanced in MC2 because of the higher tungsten content, appears to cause the higher yield stress.     

A focal stress gradient-dependent mass transfer mechanism for atherogenesis in branching arteries

A new arterial wall permeability function, based on the local wall shear stress gradient, has been developed and employed to simulate enhanced low density lipoprotein transfer across the endothelium. the atherosclerotic model used is that of the aorto-celiac junction of rabbits. The experimentally validated computer simulation model for convection mass transfer provides further evidence that the wall shear stress gradient is a reliable predictor of critical atherogenic sites in branching arteries. Some of the underlying biological aspects of atherogenesis due to locally significant and sustained wall shear stress gradient values are briefly discussed.