The ortho-to-para conversion in solid hydrogen,catalyzed by hydrogen atoms

The combined techniques of ESR and NMR were used to investigate the process of ortho-para conversion in solid molecular hydrogen, containing small amounts ( 500 ppm) of hydrogen atoms as impurity. Although the impurity atoms catalyze the effective conversion of the neighboring ortho-H₂, the total catalyzed conversion rate at temperatures from 2.2 K to 4.4 K is much less than expected from the rate of the H atoms recombination. A possible explanation is given in terms of the diffusion of H atoms, which is confined to some defects in the crystal.     

Correction to: Embrittlement Analysis of Σ5[210]/(-1-20) FeAl Grain Boundary in Presence of Defects: An Ab Initio Study

Metallurgical and Materials Transactions A -     

Fixation of distal femoral osteotomies with self-reinforced poly(L/DL)lactide 70 : 30/bioactive glass composite rods. An experimental study on rats

Self-reinforced poly(L/DL)lactide 70:30/bioactive glass [SR-P(L/DL)LA/bioactive glass] composite rods, 2 mm in diameter and 36 mm in length, were implanted into the dorsal subcutaneous tissue of 16 rats. Osteotomies of the distal femur were fixed with these rods (2 x 15 mm) in 64 other rats. The follow-up times varied from one week to one year. After sacrifice, three-point bending and shear tests, and molecular weight measurements were performed for subcutaneously placed rods. Radiological, histological, histomorphometrical, microradiographic, and oxytetracycline-fluorescence studies of the osteotomized and intact control femora were performed. At 24 weeks the mechanical properties had decreased significantly. Thirty-nine osteotomies healed uneventfully. One of the 64 evaluated osteotomies showed signs of infection at six weeks, and there were 19 non-unions and six delayed unions. In 20 operations the fixation was loose and out of these 14 non-unions were observed. No gross signs of inflammatory or foreign-body reactions were observed. The present investigation showed that the mechanical strength and fixation properties of SR-P(L/DL)LA/bioactive glass composite rods are suitable for fixation of cancellous bone osteotomies in rats as long as the operative technique is correct. The present article is the first report on the application of SR-P(L/DL)LA/bioactive glass composite rods for fixation of cancellous bone osteotomies.     

Evaluating Off-Peak Traffic Signal Control Strategies

This article discusses the evaluation of flashing yellow as an off-peak traffic signal control strategy by establishing an interface between a real-time traffic simulation software HUTSIM (Helsinki University of Technology Simulation Model) and a standard NEMA (National Electrical Manufacturers Association) traffic signal controller. The analysis was performed as part of research dealing with evaluation of different off-peak traffic signal operation strategies and their relative impacts on delay, fuel consumption, vehicle emissions, and driver safety. Because of its widespread use, the main emphasis was on the flashing yellow signal control. Delay field study was performed to obtain and analyze real-world data and compare the efficiency of flashing yellow and fixed time control strategies. To widen the research effort and eliminate inaccuracies due to certain assumptions made during the field study, computer simulation was chosen as an effective tool for comparison of different control strategies. Four different strategies were evaluated: fixed time, fully and semiactuated, and flashing yellow. Flashing yellow was found to be the most efficient of the signal strategies. The impact of this type of off-peak signal control on driver safety also was studied, and a summary of results is presented.     

Fetal intracranial hemorrhage. Imaging by ultrasound and magnetic resonance imaging

OBJECTIVE: To describe the magnetic resonance imaging (MRI) findings associated with fetal intracranial hemorrhage and to compare them with ultrasound findings. STUDY DESIGN: In four pregnancies complicated by fetal intracranial hemorrhage, fetal imaging was carried out using T2-weighted fast spin echo sequences and T1-weighted fast low angle shot imaging sequences and by transabdominal ultrasonography. RESULTS: An antepartum diagnosis of hemorrhage was made by ultrasound in one case and by MRI in two. Retrospectively, the hemorrhagic area could be identified from the MRI images in an additional two cases and from the ultrasound images in one case. In the cases of intraventricular hemorrhage, the MRI signal intensity in the T1-weighted images was increased in the hemorrhagic area as compared to the contralateral ventricle and brain parenchyma. In a case with subdural hemorrhage, T2-weighted MRI signals from the hemorrhagic area changed from low-to high-intensity signals during four weeks of follow-up. Better imaging of the intracranial anatomy was possible by MRI than by transabdominal ultrasonography. CONCLUSION: MRI can be used for imaging and dating fetal intracranial hemorrhages. Variable ultrasound and MRI findings are associated with this complication, depending on the age and location of the hemorrhage.     

Bioconversion of crude glycerol from biodiesel production to hydrogen

This study evaluates the potential of bioconversion of crude glycerol, discharged from biodiesel production plant, to hydrogen (H₂) by an enriched microbial community. Microbial community was enriched from activated sludge in a medium amended with 2.5 g/L of crude glycerol. Optimal cultivation parameters for H₂ production such as initial pH, cultivation temperature and substrate concentration were investigated. H₂ yields from raw glycerol at optimal conditions (pH 6.5; 40 °C and 1 g/L raw glycerol) were 1.1 ± 0.1 mol-H₂/mol-glycerol_consumed. H₂ production was associated with acetate-butyrate type fermentation, along with ethanol as one of the end products. Kinetic experiments on H₂ production from pure and crude glycerol indicated the absence of any inhibitory effects from the impurities present in crude glycerol. The community analysis revealed that the enriched microbial consortium was dominated mainly by Clostridium species.     

Development of an Efficient Acid Digestion Procedure Utilizing High-Pressure Asher Technique for the Determination of Iodine and Metallic Elements in Milk Powder

An effective wet digestion procedure for the determination of total iodine contents in milk powder samples was developed utilizing a high-pressure asher technique. The optimized method based on a two-stage digestion procedure. In the first stage, 500 mg samples were digested at 300 °C for 2 h using 15.2 mol L^?1 HNO₃ (5 mL) and 30 % H₂O₂ (3 mL). After the first digestion stage, digestion vessels were allowed to cool down and 1.2 mL of 20 % (w/v) Na₂S₂O₈ solution was added as an additional oxidizing agent to the samples. After that, the vessels were closed, and they were heated at 100 °C for 30 min, resulting in clear and colorless sample solutions. Iodine concentrations in the digested samples were measured with inductively coupled plasma mass spectrometry. The accuracy of the optimized method was confirmed by analyzing milk powder reference material (BCR-151, milk powder). The obtained value for iodine (5.29?±?0.37 mg kg^?1, n?=?6) was in good agreement with the certified value (5.35?±?0.14 mg kg^?1). Furthermore, the results obtained for reference material showed that the developed method can be applied also for the determination of other elements, e.g., copper, iron, and lead in the digested milk powder samples.     

Effect of Trichoderma reesei tyrosinase on rheology and microstructure of acidified milk gels

The aim of this work was to study the potential of tyrosinase enzymes in structural engineering of acid-induced milk protein gels. Fat free raw milk, heated milk or a sodium caseinate solution were treated with tyrosinases from Trichoderma reesei (TrTyr) and Agaricus bisporus (AbTyr) and the reference enzyme transglutaminase (TG) prior to acid-induced gelation. TrTyr treatment increased the firmness of raw milk and sodium caseinate gels, but not that of heated milk gels, even though protein cross-linking was detected in heated milk. AbTyr did not cross-link proteins in any of the studied milk protein systems. TG was superior to TrTyr in gels prepared of heated milk. In acidified heated milk and sodium caseinate, TrTyr and TG treatment resulted in a decrease of the pore size. Scanning electron microscopy revealed more extensive particle interactions in the heated milk gels with TG than with TrTyr.