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.     

Physical and chemical comparison of soot in hydrocarbon and biodiesel fuel diffusion flames: A study of model and commercial fuels

Data are presented to compare soot formation in both surrogate and practical fatty acid methyl ester biodiesel and petroleum fuel diffusion flames. The approach here uses differential mobility analysis to follow the size distributions and electrical charge of soot particles as they evolve in the flame, and laser ablation particle mass spectrometry to elucidate their composition. Qualitatively, these soot properties exhibit a remarkably similar development along the flames. The size distributions begin as a single mode of precursor nanoparticles, evolve through a bimodal phase marking the onset of aggregate formation, and end in a self preserving mode of fractal-like particles. Both biodiesel and hydrocarbon fuels yield a common soot composition dominated by C_x ions, stabilomer PAHs, and fullerenes in the positive ion mass spectrum, and and C_2xH⁻ in the negative ion spectrum. These ion intensities initially grow with height in the diffusion flames, but then decline during later stages, consistent with soot carbonization. There are important quantitative differences between fuels. The surrogate biodiesel fuel methyl butanoate substantially reduces soot levels, but soot formation and evolution in this flame are delayed relative to both soy and petroleum fuels. In contrast, soots from soy and hexadecane flames exhibit nearly quantitative agreement in their size distribution and composition profiles with height, suggesting similar soot precursor chemistry.     

Prospecting hydrogen production of Escherichia coli by metabolic network modeling

Genome-scale model was applied to analyze the anaerobic metabolism of Escherichia coli. Three different methods were used to find deletions affecting fermentative hydrogen production: flux balance analysis (FBA), algorithm for blocking competing pathways (ABCP), and manual selection. Based on these methods, 81 E. coli mutants possessing one gene deletion were selected and cultivated in batch experiments. Experimental results of H₂ and biomass production were compared against the results of FBA. Several gene deletions enhancing H₂ production were found. Correctness of gene essentiality predictions of FBA for the selected genes was 78% and 77% in glucose and galactose media, respectively. 33% of the mutations that were predicted by FBA to increase H₂ production had a positive effect in experiments. Batch cultivation is a simple and straightforward experimental way to screen improvements in H₂ production. However, the ability of FBA to predict the H₂ production rate cannot be evaluated by batch experiments. Metabolic network models provide a method for gaining broader understanding of the complicated metabolic system of a cell and can aid in prospecting suitable gene deletions for enhancing H₂ production.     

Fermentative hydrogen production by Clostridium butyricum and Escherichia coli in pure and cocultures

The effect of coculture of Clostridium butyricum and Escherichia coli on hydrogen production was investigated. C. butyricum and E. coli were grown separately and together as batch cultures. Gas production, growth, volatile fatty acid production and glucose degradation were monitored. Whilst C. butyricum alone produced 2.09 mol-H₂/mol-glucose the coculture produced 1.65 mol-H₂/mol-glucose. However, the coculture utilized glucose more efficiently in the batch culture, i.e., it was able to produce more H₂ (5.85 mmol H₂) in the same cultivation setting than C. butyricum (4.62 mmol H₂), before the growth limiting pH was reached.     

Internal leachate quality in a municipal solid waste landfill: vertical, horizontal and temporal variation and impacts of leachate recirculation

The aim of this study was to monitor and characterise internal leachate quality at a Finnish municipal solid waste landfill (Lahti, Kujala, in operation for approximately 50 years) to provide information about its horizontal and vertical variation as well as effects of leachate recirculation on leachate quality. The study area (approximately 4 h) of the landfill had 14 monitoring wells for leachate quality monitoring over a 2-year period. The leachate was monitored for COD, BOD, TKN, NH₄–N, Cl, pH and electric conductivity. The results showed high horizontal and vertical variability in leachate quality between monitoring wells, indicating that age and properties of waste, local conditions (e.g., water table) and degradation and dilution processes have a marked effect on local leachate quality. The mean COD values (642–8037 mg/l) and mean BOD/COD ratios (0.08–0.17) from the different monitoring wells were typical of landfills in the methanogenic phase of degradation. The leachate in the monitoring wells was notably more concentrated than the leachate effluent used for leachate recirculation. In the landfill as a whole the effects of the leachate recirculation on leachate quality, although difficult to distinguish from those caused by other factors, appeared to be minor during the study period.     

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.     

Systematic synthesis of functional unsymmetric FeZn model complexes for plant purple acid phosphatases

The heterodinuclear complexes [FeZn(L)(CH₃CO₂)₂]⁺ (L = ICIMP or IPCPMP) are structural models for the dinuclear active sites of plant purple acid phosphatases. They can be systematically synthesized from mononuclear iron complexes and enhance the rate of transesterification of 2-hydroxypropyl p-nitrophenyl phosphate, an assay for the catalytic hydrolysis performed by purple acid phosphatases.     

Tectonics and architectonic quality in recently published Finnish log architecture: Corresponding architects’ perceptions

Due to the global increase in wood construction, it is crucial for architects to understand wood. In Finland, log building, a special subset of industrially manufactured massive timber construction materials is experiencing a renaissance. Cultural aspects combined with newer technical developments make log a complex material from the viewpoint of architectonic expression. To inform practicing architects, the aim of this study is to explore how the tectonics of logs contribute to the architectonic quality of log architecture. Semi-structured interviews among architects of twelve recently published log buildings are conducted. The results describe how architectonic quality is perceived among participants, and features of logs related to tectonics that they consider to be of importance in terms of architectonic quality. These features include the statics of log construction and log's nature as a simultaneously insulating, load-bearing and visual material. Differences between industrial and hand-hewn logs, as well as other architectural aspects of using logs in contemporary architecture are discussed. Especially the “non-settling” log was perceived to have manifold implications for the architectonic possibilities of log architecture. The results are of practical importance to designing architects and the log industry. Theoretical implications include tangible information on architectonic quality and tectonics of log building.