Effect of growth hormone treatment on the healing of left colonic anastomoses in protein-malnourished rats

BACKGROUND: Malnutrition is known to affect wound healing but it is not known with certainty whether or not postoperative hyperalimentation can reverse this defect. The present study was designed to examine the effects of recombinant human growth hormone (hGH) on left colonic anastomoses in malnourished rats. METHODS: Experimental animals were allocated randomly into four groups. In groups 1 and 2 animals were fed with normal diet for 10 days before surgery. In groups 3 and 4 animals were fed with a low-protein diet. Left colonic anastomoses were performed in all animals. Following surgery, rats in groups 1 and 3 received hGH whereas rats in groups 2 and 4 were injected with saline as control. Bursting pressure and hydroxyproline levels on day 4 after operation were used to determine anastomotic healing. Results: Bursting pressure was lower in the malnourished rats than those fed with normal diet (P< 0.05). Bursting pressure was higher in normally fed rats which were given hGH. No significant differences could be noted between malnourished control rats and those receiving hGH. CONCLUSION: These results suggest that hGH strengthened the left colonic anastomoses in rats fed a normal diet, but could not reverse the negative effects of malnutrition on colonic anastomoses.     

Microstructural characterizations and mechanical properties of NbB2 and VB particulate-reinforced eutectic Al-12.6 wt% Si composites via powder metallurgy method

Mechanical alloying of elemental Al, Si, NbB₂ and VB powder mixtures constituting the matrix alloy composition of Al-12.6?wt% Si and particulate-reinforced compositions of Al-12.6?wt% Si-x NbB₂ and Al-12.6?wt% Si-x VB (x?=?1, 2 and 5?wt%) were carried out for 2, 4 and 8?h in a high-energy ball mill. Mechanically alloyed (MA’d) powders were subjected to cold pressing (450?MPa), cold isostatic pressing (400?MPa) and pressureless sintering (570?°C/2?h) processes. Powder particle morphologies changed from flaky to equiaxed shape after the optimum MA duration of 4?h. 1?wt% NbB₂ and 1?wt% VB particulate-reinforced Al-12.6?wt% Si based composites exhibited better mechanical properties than the Al-12.6?wt% Si matrix alloy and Al-12.6?wt% Si-x NbB₂ and Al-12.6?wt% Si-x VB (x?=?2 and 5?wt%) composite samples. In particular, Al-12.6?wt% Si-1?wt% NbB₂ had the highest yield strength (378?MPa), compressive strength (491?MPa) and hardness (1.86?GPa) values. Investigations on the wear behaviors of the composites revealed that significant amount of wear loss occurred as a result of debris formation due to pull-outs of reinforcing boride (NbB₂ and VB) and oxidized Al (Al₂O₃) particles.     

Nanocrystalline cobalt–nickel–boron (metal boride) catalysts for efficient hydrogen production from the hydrolysis of sodium borohydride

Innovative metal boride nanocatalysts containing crystalline Co–Ni based binary/ternary boride phases were synthesized and used in the hydrolysis of NaBH₄. All the as-prepared catalysts were in high-purity with average particle sizes ranging between ~51 and 94 nm and consisting of different crystalline phases (e.g. CoB, Co₂B, Co₅B₁₆, NiB, Ni₄B₃, Ni₂Co_0·67B_0.33). The synergetic effect of the different binary/ternary boride phases in the composite catalysts had a positive role on the catalytic performances thus, while the binary boride containing phases of unstable cobalt borides or single Ni₄B₃ were not showing any catalytic activity. The Co–Ni–B based catalyst containing crystalline phases of CoB–Ni₄B₃ exhibited the highest H₂ production rate (500.0 mL H₂ min^?1 g_cat^?1), with an apparent activation energy of 32.7 kJ/mol. The recyclability evaluations showed that the catalyst provides stability even after the 5th cycle. The results suggested that the composite structures demonstrate favorable catalytic properties compared to those of their single components and they can be used as alternative and stable catalysts for efficient hydrogen production from sodium borohydride.     

Designing behenic acid microcapsules as novel phase change material for thermal energy storage applications at medium temperature

Fatty acids are bio-based materials that can be used as phase change materials (PCMs). Microencapsulation of low carbon number fatty acids for mainly building applications have been realized in previous studies. In this study, behenic acid (BA), a fatty acid with medium melting range (65°C-85°C), has been microencapsulated for the first time. PMMA and its three copolymers were used as shell material of these novel encapsulated PCMs prepared by emulsion polymerization technique. The influences of using different comonomers in shell materials on the thermal, morphological, and chemical properties were investigated. Melting phase change temperature ranges were found as 65°C to 85°C for all capsule candidates. Capsules had uniform spherical geometry with size ranges under 500 nm. The capsules are suggested as novel PCM candidates in this temperature range that has potential applications in industrial waste heat, electronics, solar residential heating, lithium-ion batteries, and automotive application.     

Comprehensive investigation of butyl stearate as a multifunctional smart concrete additive for energy‐efficient buildings

Using of phase change materials (PCM) for increasing energy savings in sustainable buildings is receiving a lot of interest in commercial applications. Butyl stearate (BS), as PCM, can be used to maintain ambient temperature in the human comfort zone and prevent temperature fluctuations by enhancing the thermal properties of concrete. The long‐term effects of BS on concrete are not well known. In this study, the applicability of BS, as a smart concrete additive, by direct incorporation in the concrete structure was investigated comprehensively including thermal, rheological, and corrosion behaviour. The thermal characterization of PCM was achieved using DSC, TGA, thermal conductivity, and thermal buffering experiments. Thermal storage capacity of BS was measured to be 134.2 J/g, which is high enough to be used for passive solar energy storage in buildings. The fresh concrete experiments revealed that workability and flowability of fresh concrete mixes were improved. The maximum hydration temperature was reduced, and a retarding effect was observed by the addition of BS. Moreover, the corrosion behaviour of steel embedded in concrete with BS as PCM was studied in a solution of NaCl (3.5 wt%) representing an aggressive environment by utilizing electrochemical impedance spectroscopy (EIS) for long‐term corrosion tests that lasted for 1 year. The open circuit potential of steel in concrete with BS showed noble potential indicating low corrosion probability. The FESEM images and polarization resistance (R_p) values showed that the addition of BS in concrete decreases corrosion of the rebar in comparison with concrete without BS. Addition of BS not only enhances thermal capacity but also exhibits corrosion protection of rebar by hindering penetration of chloride ions into the concrete.     

Impacts of electrification & automation of public bus transportation on sustainability—A case study in Singapore

Forschung im Ingenieurwesen - Electrification and automation are attracting interest from the public-transportation sector for their potential to improve energy efficiency, cost efficiency, and...     

Omental fibroma: CT and US findings

The US, CT, and X-ray findings in a patient with omental fibroma of the lesser omentum are described. Ultrasound showed a solid mass with cystic areas in the central region. At CT the lesion showed peripheral enhancement and central hypodensity. On X-ray studies with barium, there was border distortion in the lesser curvature of the stomach. The mass was resected surgically. A pathologic diagnosis of fibroma was confirmed.     

Supply chain optimisation with U-type assembly line balancing

In supply chain optimisation problems, determining the location and number of facilities is considered at a strategic level, while mid-term and short-term decisions such as those concerning assembly policy, inventory levels, lot sizes and scheduling are handled at the tactical and operational levels. However, considering these decisions simultaneously is almost always ignored during the optimisation of distribution/production processes. The aim of the study is to optimise the supply chain network (strategic level), including manufacturers, assemblers and customers, while simultaneously balancing the U-type assembly lines (tactical level) in assemblers. A nonlinear mixed integer mathematical model is proposed to minimise the total costs and the number of assembly stations while minimising the total fixed costs of stations. To show the validity and usefulness of the proposed model, a numerical example with different scenarios and sensitivity analyses is given and discussed.