Anaerobic degradation of organic materials - significance of the substrate surface area

In anaerobic degradation of substrates containing mainly particulate organic matter, solids hydrolysis is rate-limiting. In these investigations, the particle size of various substrates was reduced by comminution to support hydrolysis. Two positive effects of comminution were observed. For substrates with high fibre content, which are particularly resistant to biodegradation, a significant improvement of the degradation degree was observed as a result of comminution. Secondly, for all substrates tested, and particularly for those rich in fibres, the degradation rate of comminuted samples was significantly higher. The first reason for both effects is an increase of the sample surface area. Several methods for measuring the specific surface area of organic materials, including particle size analysis, Nitrogen-adsorption and enzyme adsorption, were used and compared for the purpose of this study, where the surface area accessible to microbial enzymes is critical. The significance of the surface area in anaerobic degradation of particulate substrates was investigated through a kinetic model where the hydrolysis rate was based on the sample surface area. Good agreements were obtained between model and experiments carried out with samples of various specific surface areas. These results reinforced the significance of the sample surface area in anaerobic degradation processes. However, other effects of comminution responsible for the increased degradation degree and degradation rate were identified and discussed. These include: the increase of dissolved compounds due to cell rupture, exposition of surface areas previously inaccessible for microbial degradation, and alteration of the sample structure such as the lignin-cellulose arrangements.

Synthesis of high surface area amorphous tin-zinc oxides by a sol-gel method

A new method to synthesize conducting oxide nanoparticles with low photocatalytic activity was investigated. Initially, the preparation of amorphous ZnO-SnO2 solid solution nanoparticles was studied using a sol-gel technique. It was found that X-ray amorphous nanopowders with low photocatalytic activity were produced when the precipitates were heat treated below 500 °C. However, FT-IR data showed that the sample may not be an oxide semiconductor. A mixture of ZnO and SnO2 crystalline nanoparticles was also produced at 800 °C and found to have much reduced photoactivity than commercial ZnO nanoparticles having a similar specific surface area.

Glomerular hypertrophy in subjects with low nephron number: contributions of sex, body size and race

Background. We have shown that low nephron number (Nglom) is a strong determinant of individual glomerular volume (IGV) in male Americans. However, whether the same pattern is present in female Americans remains unclear. The contributions of body surface area (BSA) and race to IGV in the context of Nglom also require further evaluation. Methods. Kidneys without overt renal disease were collected at autopsy in Mississippi, USA. The extremes of female Nglom were used to define high and low N glom for both sexes. Nglom and IGV were estimated by design-based stereology. A total of 24 African and Caucasian American females (n = 12 per race; 6 per Nglom extreme) were included. These subjects were subsequently matched to 24 comparable males by age and Nglom and to 18 additional males by age, Nglom and BSA. Results. IGV average and variance were very similar in female African and Caucasian Americans with high and low Nglom. Males with low Nglom from both races showed greater IGV average and variance than comparable females matched by age and Nglom. These differences in IGV between sexes were not observed in Caucasian Americans with low Nglom that were matched by age, Nglom and BSA. In contrast, glomeruli from African Americans were larger than those from Caucasian Americans, especially in subjects with high Nglom. Conclusions. While female Americans with low Nglom did not show glomerular hypertrophy, comparable males with low Nglom showed marked glomerular hypertrophy that was closely associated with high BSA. Glomerular size in African Americans may be confounded by multiple additional factors. © The Author 2014. Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved.

Brain development during adolescence: A mixed-longitudinal investigation of cortical thickness, surface area, and volume.

What we know about cortical development during adolescence largely stems from analyses of cross-sectional or cohort-sequential samples, with few studies investigating brain development using a longitudinal design. Further, cortical volume is a product of two evolutionarily and genetically distinct features of the cortex - thickness and surface area, and few studies have investigated development of these three characteristics within the same sample. The current study examined maturation of cortical thickness, surface area and volume during adolescence, as well as sex differences in development, using a mixed longitudinal design. 192 MRI scans were obtained from 90 healthy (i.e., free from lifetime psychopathology) adolescents (11-20 years) at three time points (with different MRI scanners used at time 1 compared to 2 and 3). Developmental trajectories were estimated using linear mixed models. Non-linear increases were present across most of the cortex for surface area. In comparison, thickness and volume were both characterised by a combination of non-linear decreasing and increasing trajectories. While sex differences in volume and surface area were observed across time, no differences in thickness were identified. Furthermore, few regions exhibited sex differences in the cortical development. Our findings clearly illustrate that volume is a product of surface area and thickness, with each exhibiting differential patterns of development during adolescence, particularly in regions known to contribute to the development of social-cognition and behavioral regulation. These findings suggest that thickness and surface area may be driven by different underlying mechanisms, with each measure potentially providing independent information about brain development. Hum Brain Mapp, 2016. © 2016 Wiley Periodicals, Inc.

Effect of Jersey type on thermoregulatory responses during exercise in a warm humid environment

The thermoregulatory responses of subjects wearing two different forms of rugby league jersey, one with plastic sponsorship recognition and numbering (trial Gl) and one without (trial G2), and a lightweight alternative (trial G3), were compared with a trial without any form of upper body garment (trial GO). Ten male volunteers, mean age 20.9 (±2.3) years, height 179.8 (±4.7) cm, weight 80.2 (±8.9) kg, and body surface area 1.99 (±0.13) m2, participated in this study. Subjects had a mean maximal oxygen uptake capacity of 56.0 (±6.3) ml.kg.min-1 and a sum of 8 skinfolds of 80.6 (±23.8) mm. Subjects were exercised at approximately 50% of maximal oxygen uptake in a warm humid environment for 50 minutes. Mean ambient temperature was 27.6°C (±0.32) with a relative humidity of 64.7% (±1.44). Measurements of core and skin (7 sites) temperature, heart rate, oxygen uptake, plasma volume, peak lactate concentration, and pre- and post-trial body weight, hematocrit and garment weight were recorded. The statistical results showed that all subjects experienced significant (p ≤.0001) decreases in body weight representing a percentage decrease ranging from 1.2-1.3%. No significant difference was found between trials with respect to body weight change. No significant effect of garment type was found on pre- and post-trial hematocrit, plasma volume changes or peak blood lactic acid concentration. However, mean peak lactate was highest for trial Gl (5.6 mmol.L-1 ±2.2) and lowest for trial G3 (4.6 mmol.L-1 ±1.27). Post-trial core temperature was significantly (p≤ .0001) higher than the resting value; no significant difference was found between trials. The mean absolute increase for all experimental trials was 0.9°C. A significant (p≤.005) difference between mean total (7 sites) skin temperature was found with a post-hoc test revealing that trials Gl and G2 were significantly higher than trial GO; no significant difference was found when comparing trial G3 with trial GO or when comparing the garments between each other. Mean skin temperature under the garment (4 sites) was found to be significantly (p≤.05) higher for all trials involving a garment when compared with mean skin temperature outside (3 sites) the garment; no significant difference was found between trials. Mean oxygen uptake was significantly different between trials (p≤.005), with trial Gl and G3 found to be significantly lower than trial GO; no difference was found when comparing the garments with each other. Post-trial garment weights were significantly (p≤.001) heavier than pre-trial and were significantly (p≤.0001) different when compared with each other. There was no significant effect on heart rate, haematocrit, plasma volume changes, peak blood lactic acid concentration, or core temperature due to garment type. However, differences in skin temperature suggest that the garment used in trial G3 may have a benefit. Further research should consider the impact of increased exercise intensity and/or environmental temperature and humidity on the measured parameters while wearing the garments described in this study.

Comparing mortality outcomes of major burns and toxic epidermal necrolysis in a tertiary burns centre

 Introduction
Our aim was to provide descriptive information to burn clinicians, who have extensive experience treating major burns and determining prognosis, as to whether significant differences in mortality exist between major burns injuries and the comparatively less common toxic epidermal necrolysis for a given age and total body surface area percentage.

Methods
Retrospective data was analyzed of all deceased patients admitted to the Victorian Adult Burns Service in Melbourne, Australia over a period of 10 years with greater than 30% total body surface area burned or greater than 30% total body surface area epidermal detachment in the case of toxic epidermal necrolysis. Retrospective data was also collected on all patients, survivors and deceased, with toxic epidermal necrolysis and these patients were matched with burns patients by age and % total body surface area burned. Comparisons in outcomes were performed with mortality being the primary variable of interest.

Results
Toxic epidermal necrolysis patients that died were older (median: 68.5 vs 57 yrs; P = 0.04), had a longer length of hospital stay (36.5 vs 0.8 days; P = 0.001) and significantly longer periods of mechanical ventilation (1404 vs 14.5 h; P = 0.011) than major burns patients that died. When toxic epidermal necrolysis patients were matched to major burns patients by age and total body surface area burned, there were no significant differences between the two groups with respect to mortality.

Conclusion
Palliative care approaches are more frequently administered at the time of presentation for major burns patients in comparison to toxic epidermal necrolysis patients. This may be due to a perception that if toxic epidermal necrolysis patients can survive their initial systemic injury, they are likely to survive, as opposed to major burns patients who often undergo extensive surgery and for whom other factors should be taken into account in the context of end-of-life decision making.

A systematic review of the management and outcome of toxic epidermal necrolysis treated in burns centres

Introduction
Toxic epidermal necrolysis (TEN) is a rare condition characterised by mucocutaneous exfoliation of greater than 30% total body surface area (%TBSA), increasingly being treated in burns centres. The rate of mortality varies significantly in the literature, with recent prospective studies in non-burns centres reporting percentage mortality of approximately 45%. We undertook a systematic review of published studies that included TEN patients treated specifically in burns centres to determine a cumulative mortality rate.

Methods
Electronic searches of MEDLINE, EMBASE and The Cochrane Library (Issue 4, 2010) databases from 1966 onwards were used to identify English articles related to the treatment of TEN in burns centres.

Results
The systematic literature search identified 20 studies which specifically described patients with TEN grater than 30% %TBSA. Treatment regimens varied amongst studies, as did mortality. The overall percentage mortality of the combined populations was 30%. Risk factors commonly described as associated with mortality included age, %TBSA and delay to definitive treatment.

Conclusion
The review highlights the variation between principles of treatment and mortality amongst burns centres. It offers a standard that burns centre can use to internationally compare their mortality rates. The review supports the ongoing reporting of outcomes in TEN patients with epidermal detachment greater than 30%.

Mortality and use of the auxiliary score in extensive toxic epidermal necrolysis patients admitted to an adult burns referral centre

 Background: Toxic epidermal necrolysis (TEN) is a rare but fatal condition characterised by cutaneous exfoliation of the dermoepidermal layer and mucosal surfaces. Extensive TEN with epidermal detachment >30% of the total body surface area has been associated with a high mortality. Objective: This study aims to evaluate factors associated with mortality in extensive TEN. In the absence of data to qualify scoring systems such as SCORTEN, this study also aims to evaluate the use of the auxiliary score as a tool for calculating expected mortality. Methods: A retrospective chart review of all patients presenting to our burns service with extensive TEN was undertaken. Application and evaluation of the auxiliary score was also undertaken for this patient population. Results: In extensive TEN, age and delay in admission to a burns centre were factors associated with mortality. Applying the auxiliary score to our patient population, there were no significant differences between expected mortality and observed mortality. Conclusion: Mortality was associated with age and delay in definitive treatment in extensive TEN. Whilst SCORTEN is the gold standard prognostic tool for patients with TEN, in the absence of SCORTEN values, the auxiliary score provides an alternative scoring system to evaluate expected mortality.

Linshuichonetes gen. nov., a new rugosochonetid (Brachiopoda) genus from the Liangshan Formation (Early Permian) in Sichuan, China, and its ecology

A new genus and species, Linshuichonetes elfinis, belonging to the Rugosochonetidae, is described from the Early Permian (Late Artinskian or early Kungurian) Liangshan Formation of the Yangtze block. The new genus is defined externally by the presence of fine, but delayed, capillation and a weak or absent median sulcus and fold and by the presence of a distinct posteromedian sinus on the ventral umbo; and internally by a lack of median, lateral and accessory septa in the dorsal interior; absence of vascular trunks in the ventral interior and the presence of distinct radiating rows of papillae in the interior of both valves, particularly an unusual clustered arrangement of papillae on the posteromedian portion of the dorsal interior. The local environment during the deposition of the Liangshan Formation appears to have been a restricted tidal flat or lagoon which experienced frequent sealevel fluctuations associated with the onset of the Yanghsingian transgression. The new species, L. elfinis, appears to have several morphological adaptations enabling successful exploitation of this environment. It was typically a very small and thin-valved species with a high surface area to volume ratio, an advantage in an oxygen restricted environment. The small size and numerous body spinules would have aided individuals to remain suspended at the top of the fine, soft substrate. It also dominated the brachiopod assemblage in the Liangshan Formation, comprising up to 94%of specimens within a bed. These factors indicate that the new species appears to be an opportunistic species.

Influence of particle concentration on initial collection efficiency and surface coverage in porous media filtration

Four sizes (0.095, 0.53, 1.0 and 2.01 μm) of polystyrene latex particles were used to prepare monodispersed suspensions at three different ionic strengths (10−3, 10−2.5 and 10−2M KCl). Filtration experiments were conducted using those suspensions in a filter column with glass beads as porous medium. The filter bed depth and the filtration velocity were kept at 5 cm and 1 m/h, respectively. When suspensions with equal mass concentrations (0.2 mg/L) or equal surface area concentrations (0.12 cm2/mL) were filtered through the system, the largest particles exhibited higher initial single collector efficiency, η. The difference between the η of largest particles and the smaller particles was prominent for suspensions with equal surface area concentrations at higher ionic strengths. The collision efficiency, α of those particles exhibits higher values at higher ionic strengths. Both at equal mass concentration and equal surface area concentration, α is only slightly dependent on particle sizes when compared to its dependence on ionic strength. Further, it was found that the specific surface coverage was similar for 0.095 μm, 0.53 μm and 1.0 μm particles during the transient stage of filtration at any ionic strength when the surface area concentrations of those suspension were equal.

Surface coverage of filter medium in deep bed filtration : mathematical modelling and experiments

This paper highlights the importance of surface coverage in modeling the removal of particles in deep bed filtration. A model that considers the saturation of sites on which particle deposition occurs is used. Experimental results obtained with monodispersed suspensions of 0.46 and 0.816 μm latex particles at different influent concentrations and ionic strengths were used to calculate the fraction of filter grain surface (β1) on which actual particle deposition occurs. This will be useful in evaluating the filter performance in terms of the utilization of available surface area of the filter medium. Further, the level of dendrite formation of particles on filter grains during filtration is expressed in terms of β1 and the specific surface coverage, θT (the fraction of a filter grain surface that is covered by particles at time T, assuming that the filter grain is covered by a monolayer of particles). This can be used to compare the contribution of deposited particles in the removal efficiency of deep bed filtration for suspensions with different physical and chemical characteristics.

Superhydrophobic nanofibre membranes : effects of particulate coating on hydrophobicity and surface properties

Superhydrophobic electrospun polyacrylonitrile nanofibre membranes have been prepared by surface coating of silica nanoparticles and fluorinated alkyl silane. The coated membranes were characterised by scanning electron microscopy, water contact angle, thermogravimetry analysis, Brunauer–Emmett–Teller, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and atomic force microscopy. It was shown that the loading of nanoparticle on the nanofibre membrane was controlled by the particle concentration in the coating solution, which played a critical role in the formation of superhydrophobic surface. Increased particle loading led to higher surface roughness and WCA. The nanoparticle coating had little influence on the porosity of the nanofibre membranes. However, overloading of the particles would affect the specific surface area of the nanofibre membrane.