Total Void Volume Research Articles

Porosity of green body: A potential essential factor regulating the making of sintered ceramsite from aluminum-based drinking water treatment residuals

Ceramsite is commonly applied in filtration systems for water treatment and aluminum (Al)-based drinking water treatment residue (DWTR) has been widely reported to have high potential to be recycled as main ingredient to make the sintered ceramsite. Various key factors affecting ceramsite making (e.g., composition and sintering temperature) have been identified to promote the beneficial recycling; however, according to sintering processes, this study hypothesized that porosity of green body was also a potential key factor, and then moisture content of green body (33 %-40 %) and particle size of DWTR (< 425 μm), which were the parameters initially considered for ceramsite making, were adopted to regulate the porosity for affecting characteristics and mechanisms investigation. The results verified the hypothesis and showed that increasing moisture content tended to decrease loss on ignition, apparent density, and bulk density, to increase water absorption, and to cause rougher surface of ceramsites, promoting the maximum Cu adsorption capacity of the ceramsite (estimated by Langmuir model); while at medium level of moisture content (e.g., 35 %), a relatively high compressive strength, strong Cu adsorbability (evaluated by Freundlich model), and low solubility in hydrochloric acid were found. Moreover, larger sized DWTR tended to increase loss on ignition, broken rate, solubility in hydrochloric acid, silt content, and water absorption, to reduce apparent density and compressive strength, and to cause rougher surface of the ceramsite, promoting the maximum adsorption capacity and decreasing the adsorbability of Cu. Further analysis suggested that moisture content was mainly through regulating total volume of voids and amount of raw materials to affect sintering, while particle size was mainly through regulating the contacting of particles. These results demonstrated the importance of the moisture contents of green body and the particle size of DWTR on affecting sintered ceramsite making, and porosity of green body was recommended to be taken as an essential factor when determining the optimal condition to make sintered ceramsite making.

Experimentally-guided finite element modeling on global tensile responses of AA6061-T6 aluminum alloy joints by laser welding

There are still some technical issues involved in laser welding of aluminum alloys, such as porosity, cracking, deformation, and so forth. In this study, AA6061-T6 sheets of 2.54 mm in thickness were welded by a disk laser in the bead-on-plate with two different welding parameter sets. Full penetration depths were achieved with decent surface appearances for both cases. The digital image correlation method was successfully applied in experiments to identify material model parameters of tensile welded specimens from various weldment regions. The identified parameters were utilized to numerically simulate the uniaxial tensile tests of laser-welded specimens. The effect of welded joint geometry on global tensile responses was investigated in experimentally-guided finite element modeling. With the help of X-ray computed microtomography, internal defects of the welded bead were detected and used as an input variable in the simulations. Strain development was observed through experimental and numerical data. The results showed that axial deformation was initiated at the top surface of welded metals. The considerable axial deformation occurred at the bottom surface (weld root) of the welded joint just before failure. The numerical results indicated that the geometry of welded joints greatly affected tensile responses. The results also concluded that the diameter of a single void significantly influenced tensile responses compared to its distributed location and the total volume of multiple voids with smaller sizes. Compared between the two sets of welding parameter sets used in this study, the welded joints of this particular AA6061-T6 material with the first parameter set of 2.40 kW laser power and 1.27 m/min traveling speed employed could give better tensile properties and be verified by both experimental and numerical results.

Proposed automated contrast-enhanced microscopical method for evaluating air void structure in compacted asphalt concrete mixtures

There is no direct, less expensive, and practical method to measure the interconnectivity and parameters of air voids in asphalt mixtures other than the total air void volume calculated traditionally using bulk and maximum theoretical specific gravities. Unlike the conventional method, this paper proposes a method that is suitable for advanced applications and studies, such as for the evaluation of air void distribution and air void gradient to model and simulate long-term aging, predict top-down fatigue cracking, evaluate the effectiveness of compaction of thick lifts, and satisfy the representative volume element (RVE) requirements (a homogenous and representative specimen) for performance tests. Developing the proposed compact asphalt evaluation method included modifying the sample preparation methods and analysis from the American Society of Testing & Materials (ASTM), C457 Method C, and recently applied in the analyses of two independent studies at the Federal Highway Administration (FHWA). The first study was focused on checking the air void distribution within the small specimen for dynamic modulus and uniaxial cyclic fatigue tests using AASHTO TP 132 and TP 133, respectively. Results of air void analyses conducted on the interior and exterior sides of several slices sawn from different compacted asphalt mixtures consistently showed that the air void contents on the external sides are higher than on the interior. The second study was to evaluate whether the thicker-than-typical lift thickness to nominal maximum aggregate (NMAS) ratio was causing any top-to-bottom air void gradient in the pavement. Results showed that air void sizes and contents are consistently higher along the top ends of all the cores, and the total air void contents measured using the new method on several specimens from the field were comparable with the indirectly calculated air void percent with up to ± 0.4 percent random error. Overall, the new method is practical to apply to larger-size samples and is a tool that both agencies and contractors can use for confirming in situ void uniformity. Its application can support innovations and improve performance in asphalt pavement construction.

The effect of X-ray computed tomography scan parameters on porosity assessment of carbon fibre reinfored plastics laminates

Combinations of X-ray Computed Tomography (XCT) scan times, from 30 s to 60 min, and voxel sizes, from 6 to 50 µm, were investigated for their effect on the porosity measurements of a unidirectional carbon fibre epoxy composite volume. The sample had a total void volume of around 2%, which is typical of the tolerance expected in the aerospace industry. The volume contained localised voids that create sub-volumes with representative high (5%) and low (1%) porosity regions. The ability to detect small-size voids in the lower porosity regions decreased as the voxel size increased. Scan resolutions above 25 µm resulted in a coarser segmentation and overestimation of the porosity due to the presence of partial volume effects. Scan times shorter than 2 min resulted in noisy images, requiring aggressive filtering that affected the segmentation of voids. Porosity segmentation was performed by thresholding and Deep Learning methods. Deep Learning segmentation was found to recognise noise better, providing more consistent and cleaner segmented data than thresholding. To capture micro-voids that contribute to porosity levels at the typical aerospace tolerance of 2%, scan parameters with a voxel size equal to or smaller than 25 µm, scan times of 2 to 8 min, and deep learning segmentation were found to be the most promising. These shorter scan times can be used to increase the productivity of CT scanning for porosity or observing time-resolved events. The data provided here contributes to the body of knowledge studying X-ray hardware settings and optimising image segmentation.

Evidence that methylglyoxal and receptor for advanced glycation end products are implicated in bladder dysfunction of obese diabetic ob/ob mice.

Glycolytic overload in diabetes causes large accumulation of the highly reactive dicarbonyl compound methylglyoxal (MGO) and overproduction of advanced glycation end products (AGEs), which interact with their receptors (RAGE), leading to diabetes-associated macrovascular complications. The bladder is an organ that stays most in contact with dicarbonyl species, but little is known about the importance of the MGO-AGEs-RAGE pathway to diabetes-associated bladder dysfunction. Here, we aimed to investigate the role of the MGO-AGEs-RAGE pathway in bladder dysfunction of diabetic male and female ob/ob mice compared with wild-type (WT) lean mice. Diabetic ob/ob mice were treated with the AGE breaker alagebrium (ALT-711, 1 mg/kg) for 8 wk in drinking water. Compared with WT animals, male and female ob/ob mice showed marked hyperglycemia and insulin resistance, whereas fluid intake remained unaltered. Levels of total AGEs, MGO-derived hydroimidazolone 1, and RAGE in bladder tissues, as well as fluorescent AGEs in serum, were significantly elevated in ob/ob mice of either sex. Collagen content was also markedly elevated in the bladders of ob/ob mice. Void spot assays in filter paper in conscious mice revealed significant increases in total void volume and volume per void in ob/ob mice with no alterations of spot number. Treatment with ALT-711 significantly reduced the levels of MGO, AGEs, RAGE, and collagen content in ob/ob mice. In addition, ALT-711 treatment normalized the volume per void and increased the number of spots in ob/ob mice. Activation of AGEs-RAGE pathways by MGO in the bladder wall may contribute to the pathogenesis of diabetes-associated bladder dysfunction.NEW & NOTEWORTHY The involvement of methylglyoxal (MGO) and advanced glycation end products (AGEs) in bladder dysfunction of diabetic ob/ob mice treated with the AGE breaker ALT-711 was investigated here. Diabetic mice exhibited high levels of MGO, AGEs, receptor for AGEs (RAGE), and collagen in serum and/or bladder tissues along with increased volume per void, all of which were reduced by ALT-711. Activation of the MGO-AGEs-RAGE pathway in the bladder wall contributes to the pathogenesis of diabetes-associated bladder dysfunction.

Numerical Analysis of the Damage Evolution of DP600 Steel Using Gurson–Tvergaard–Needleman Model

This research models the ductile fracture in DP600 steel sheets by using Gurson–Tvergaard–Needleman (GTN) damage model with experimentally obtained parameters. Uniaxial tensile tests are carried out to determine the deformation behavior of the material and obtain GTN model parameters. Further, SEM investigations on the fractured surface of the material display a dimpled surface, which indicates ductile fracture. Also, density measurements are carried out to define the critical and final volume fractions. A finite element model (FEM) of the tensile testing is developed. Then, the experimental parameters of the GTN model are verified by comparing load–displacement curves and porosity values for different zones. The results put forth that the experimental parameters can be used to model the deformation behavior of the DP 600 steel. Further, the growth of total void volume fraction increases exponentially, attributed to the increasing value of stress triaxiality. Also, the shift in the void volume fraction after the critical void volume fraction is explained with the void coalescence. Finally, the thickness of the sheet has a power‐law relationship and the porosity level of the material can be predicted for a known thickness value.

Effect of mass flow rate on bubble size distribution in boiling flow in temperature-controlled annular test section

Subcooled flow boiling experiments were performed in an annular horizontal channel with inner diameter of 12 mm and the gap of 2 mm. The annular channel is designed as a double-pipe heat exchanger, where the inner tube of the channel is heated by a water flow, providing a temperature-controlled boiling surface. The influence of mass flow rate of the working fluid R245fa on flow boiling patterns and heat transfer has been studied. Subcooled flow boiling patterns were recorded with a high-speed camera. The recorded images of the flow patterns were then further processed to determine the bubble size distributions, characterized as distributions of the void (vapour) volume given per bubble size. The observed bubble size distributions followed two distinct distribution functions: the Rayleigh distribution at larger and bimodal distribution at smaller mass flow rates. This indicates the existence of two distinct boiling flow regimes at different mass flow rates. The heat flux was estimated by local temperature measurements with thermocouples positioned along the boiling surface and in the heating water. The heat flux increased moderately with increasing mass flow rate, apparently without disruption at the observed change in the flow regime. On the contrary, the total void volume in the observed part of the test section is declining moderately with increased refrigerant mass flow rate, which, in this mode of operation of the test section, acts as a prevailing mechanism. The experimental setup, methods of experimental analysis and the results are presented and discussed.

Surface Assessment via Grid Evaluation (SuAVE) for Every Surface Curvature and Cavity Shape.

The surface assessment via grid evaluation (SuAVE) software was developed to account for the effect of curvature in the calculations of structural properties of chemical interfaces regardless of the chemical composition, asymmetry, and level of atom coarseness. It employs differential geometry techniques, enabling the representation of chemical surfaces as fully differentiable. In this article, we present novel developments of SuAVE to treat closed surfaces and complex cavity shapes. These developments expand the repertoire of curvature-dependent analyses already available in the previous version of SuAVE (e.g., area per lipid, density profiles, membrane thickness, deuterium-order parameters, volume per lipid, and surface curvature angle) to include new functionalities applicable to soft matter (e.g., sphericity, average radius, principal moment of inertia, and roundness) and crystalline porous materials (e.g., pore diameter, internal void volume, total area, and the total void volume of the unit cell structure). SuAVE can accurately handle chemical systems with high and low atom density as demonstrated for two distinct chemical systems: the lipid A vesicle and a set of selected metal–organic frameworks. The SuAVE software v2.0 is fully parallel and benefits from a compiler that supports OpenMP. SuAVE is freely available from https://github.com/SuAVE-Software/source and https://www.biomatsite.net/.

EFFECT OF NANO-SILICA ADDITION ON PHYSICO-MECHANICAL PROPERTIES AND DURABILITY OF CONCRETE

This paper presents the results of an experimental investigation into the effect of nano-silica addition on the mechanical properties and durability of concrete. Three mixes of concrete containing 0%, 2%, and 4% nano-silica by weight of cement were tested. The slump of fresh concrete as well as compressive strength, dynamic modulus of elasticity at 2, 7, 28, 90, and 180 days, and flexural strength at 2, 28, and 90 days of hardened concrete were determined. As for indicators of concrete durability, the total volume of permeable voids, water absorption, the rate of water absorption, and the freeze-thaw scaling resistance were determined. Test results showed that the incorporation of nano-silica in concrete resulted in an improvement of all mechanical properties of concrete, as well as concrete durability parameters that are tested.

Root-end resection with or without retrograde obturation after orthograde filling with two techniques: A micro-CT study.

To evaluate the filling ability of two orthograde obturation techniques followed by the apical resection with or without retrograde obturation through micro-computed tomography (CT). Thirty-two single-rooted permanent teeth were prepared and randomised into four groups (n=8) according to the orthograde obturation technique (single cone technique [SCT] and mineral trioxide aggregate placement) combined or not with retrograde obturation. The volume of voids (VoV) within the entire endodontic space, the apical 3 mm, and 1 mm after root resection was calculated by micro-CT. Statistical analysis showed no significant difference among the groups regarding the total VoV in all root canals, as well as within the apical 1 mm after root resection. The SCT and apical resection without retrograde filling showed significantly better results in terms of VoV at the apical 3 mm after root resection. Within the study limitations, SCT associated with apical resection without retrograde preparation exhibited a similar or less amount of voids than the other groups.

A Graphical Representation of Membrane Filtration

We analyze the performance of membrane filters represented by pore networks using two criteria: (1) total volumetric throughput of filtrate over the filter lifetime and (2) accumulated foulant concentration in the filtrate. We first formulate the governing equations of fluid flow on a general network, and we model transport and adsorption of particles (foulants) within the network by imposing an advection equation with a sink term on each pore (edge) as well as conservation of fluid and foulant volumetric flow rates at each pore junction (network vertex). Such a setup yields a system of partial differential equations on the network. We study the influence of three geometric network parameters on filter performance: (1) average number of neighbors of each vertex, (2) initial total void volume of the pore network, and (3) tortuosity of the network. We find that total volumetric throughput depends more strongly on the initial void volume than on average number of neighbors. Tortuosity, however, turns out to be a universal parameter, leading to almost perfect collapse of all results for a variety of different network architectures. In particular, the accumulated foulant concentration in the filtrate shows an exponential decay as tortuosity increases.

Comparison of capsule-mixed versus hand-mixed glass ionomer cements Part II: Porosity

Glass ionomer restorative cements (GIC) are routinely used in dental practice. During mixing, air incorporation may lead to higher porosity with subsequent weakening of the cement. The degree of porosity will determine whether capsule-mixed or hand-mixed GIC are mechanically stronger for clinical use. To compare the porosity of four commercially available dental glass ionomer cements, supplied in both hand mix and capsule-mix formulations, by evaluating number of voids (%), total volume of voids (mm3 ) and volume percentage of voids (%). Eighty samples were manufactured from hand-mixed GIC: Riva Self Cure; Fuji IX GP ; Ketac Universal, Ketac Molar Easymix, and equivalent capsule-mixed GIC: Riva Self Cure; Fuji IX GP ; Ketac Universal Aplicap and Ketac Molar Aplicap. Micro-CT scanning was used to evaluate porosity. The number of voids (mm3 ), total volume of voids (mm3 ) and the volume percentage of voids (%) were calculated.

Petrophysical Properties Estimation of Euphrates Reservoir in Qayyarah Oil Field Using Core and Well Log Data

The Early Miocene Euphrates Formation is characterized by its oil importance in the Qayyarah oil field and its neighboring fields. This study relied on the core and log data analyses of two wells in the Qayyarah oil field. According to the cross-plot’s information, the Euphrates Formation is mainly composed of dolomite with varying proportions of limestone and shale. Various measurements to calculate the porosity, permeability, and water saturation on the core samples were made at different depths in the two studied wells Qy-54 and Qy-55. A relationship between water saturation and capillary pressure has been plotted for some core samples to predict sites of normal compaction in the formation. The line regression for this relationship was considered as a function of the ratio of large voids to the total volume of voids in the sample. The coefficient of determination parameter was used in estimating the amount of homogeneity in the sizes of the voids, as it was observed to increase significantly at the sites of shale. After dividing the formation into several zones, the well log data were analyzed to predict the locations of oil presence in both wells. The significance of the negative secondary porosity in detecting the hydrocarbon sites in the Euphrates Formation was deduced by its correspondence with the large increase in the true resistivity values in both wells. More than 90% of the formation parts represent reservoir rocks in both wells, but only about 75% of them are oil reservoirs in the well Qy-54 and nearly 50% of them are oil reservoirs in the well Qy-55.

Influence of Hydrostatic Pressure on the Formation of Voids in Gelled Crude Oil

Production of waxy crude oil from offshore fields has increased in the last decade. However, the operation is being challenged with the high wax content of crude oil that tends to precipitate at lower temperature. This paper presents the effects of hydrostatic pressure on the voids formed in waxy crude oil gel. A flow loop rig that simulates offshore waxy crude oil transportation was used to produce the gel. A Magnetic Resonance Imaging of 3-Tesla system was used to scan the gelled samples in horizontal and vertical pipes. The hydrostatic pressure effect was found to be most significant near the pipe wall as a change in percent voids volume of 0.53% was observed at that region. In particular, the voids volume reduction was more pronounced in the lower half side of the pipe. The total volume of voids in the vertical pipe was lower than that in the horizontal pipe, and this suggests that the gel in the vertical pipe became denser due to the effects from the hydrostatic pressure. Conversely, the voids volume around the pipe core in the vertical pipe was higher when compared to that in the horizontal pipe. The change in voids volume near the pipe core and wall shrunk to a minimum and converged to 0.18% voids volume at larger duration of the hydrostatic effect. Further, hydrostatic pressure was observed to have significant influences for higher duration making the void size to be distributed across and along the pipeline; however, it was found to have insignificant effects on voids size distribution for smaller duration. The findings of this study can help for better understanding of voids formation in vertical pipelines that would further assist in developing a model predicting restart pressure accurately.

Numerical Study about the Influence of Superimposed Hydrostatic Pressure on Shear Damage Mechanism in Sheet Metals

It is generally accepted that the superimposed hydrostatic pressure increases fracture strain in sheet metal and mode of fracture changes with applying pressure. Void growth is delayed or completely eliminated under pressure and the shear damage mechanism becomes the dominant mode of fracture. In this study, the effect of superimposed hydrostatic pressure on the ductility of sheet metal under tension is investigated using the finite element (FE) method employing the modified Gurson–Tvergaard–Needleman (GTN) model. The shear damage mechanism is considered as an increment in the total void volume fraction and the model is implemented using the VUMAT subroutine in the ABAQUS/Explicit. It is shown that ductility and fracture strain increase significantly by imposing hydrostatic pressure as it suppresses the damage mechanisms of microvoid growth and shear damage. When hydrostatic pressure is applied, it is observed that although the shear damage mechanism is delayed, the shear damage mechanism is dominant over the growth of microvoids. These numerical findings are consistent with those experimental results published in the previous studies about the effect of superimposed hydrostatic pressure on fracture strain. The numerical results clearly show that the dominant mode of failure changes from microvoid growth to shear damage under pressure. Numerical studies in the literature explain the effect of pressure on fracture strain using the conventional GTN model available in the ABAQUS material behavior library when the mode of fracture does not change. However, in this study, the shear modified GTN model is used to understand the effect of pressure on the shear damage mechanism as one of the individual void volume fraction increments and change in mode of fracture is explained numerically.

The voiding pattern of aterm neonates

Introduction: The concept of voiding patterns in neonates had not been completely understood. The voiding pattern in neonates was physiologically different from that in older children. The brain's development affects voiding patterns in frequency, bladder volume, and post-void residual bladder volume, as the child keeps growing. This study aims to understand the physiological neonates' voiding system in Indonesian newborns.Materials and methods: We evaluate ten normal-born and 12 perinatology-hospitalized aterm neonates without anatomical or physiological urologic abnormalities at RSUP Haji Adam Malik from October to November 2019. We used an observational study, assessing the voiding physiology in newborns, including voiding frequency and urine volume. Infants with a history of urinary tract infection or present bacteriuria confirmed by urine culture were excluded. Voiding volume, frequency, bladder capacity, and residual volume were measured. Results: We collected a total of 22 patients, with 12 patients were perinatology-hospitalized and ten patients were healthy neonates with ten subjects were male, and 12 subjects were female. There was no correlation between voiding frequency and total voiding volume with perinatology-hospitalized, healthy neonates, and sex. (p&gt;0.05). Independent T-test was performed with a p-value for volume, frequency, bladder capacity, and residual volume of 0.225, 0.112, 0.031, and 0.663. We got a significant difference in bladder capacity between healthy neonates and perinatology-hospitalized. No significant differences were noted in other variables. Pearson correlation analysis was performed to determine the correlation between total voiding volume and age of gestation, body weight, length, head circumference, abdominal circumference, and chest circumference. The correlation coefficients were 0.772, 0.869, 0.623, 0.698, 0.079, 0.523 in order, with significant p-value in the age of gestation, body weight, length, head circumference, and chest circumference. There were correlations between total voiding volume and age of gestation, body weight, length, head circumference, and chest circumference. Conclusion: In conclusion, we found there was a significant difference in bladder capacity between healthy neonates and perinatology-hospitalized.

Micro-CT Evaluation of Four Root Canal Obturation Techniques.

Purpose The aim of this in vitro study was to evaluate the quality of four root canal obturation techniques using microcomputed tomography (micro-CT). Materials and Methods A total of 36 mandibular first premolars with mostly round canals were decoronated, then instrumented up to a size F3 rotary file, and dressed with an epoxy resin-based sealer. Subsequently, they were divided into 4 different groups (n = 9) based on the method of obturation: lateral condensation using 0.02 tapered master cone (LC2), lateral condensation using 0.04 tapered master cone (LC4), matched single-cone technique (MS), and matched single cone-mediated ultrasonic activation (MSUA). All the teeth were scanned using micro-CT (resolution of 19 μm), and the percentage volume of voids was calculated. One-way analysis of variance and Tukey test were used to analyze the data (α = 0.05). Results The total percentage volume of voids was significantly lower in the MSUA group compared to all other groups (P < 0.05). The total percentage volume of voids was significantly lower in the MS group compared to the LC4 (P < 0.001) and LC2 (P < 0.001) groups. However, there was no significant difference between the LC2 and LC4 groups (P < 0.65). Conclusions MSUA, significantly, showed the least root canal filling voids amongst all the obturation techniques studied. MSUA can be considered an effective method for the filling of the round root canals. In general, lateral condensation using either 0.02 or 0.04 tapered master cones had significantly the highest volume percentage of voids amongst the experimental groups.

Porous 3,4-di(3,5-dicarboxyphenyl)phthalate-based Cd2+ coordination polymer and its potential applications

Porous coordination polymers with organic aminium as one of the guest species possess a potential application in dye adsorption and white-light material manufacture. Polycarboxylic acid with multiple COOH substituents tends to form this type of porous material (with metal ion). Here the solvothermal self-assembly between Cd2+ and a hexacarboxylic acid creates such a porous material [(CH3)2NH2]6[Cd3(L)2]·5DMF·3H2O (H6L = 3,4-di(3,5-dicarboxyphenyl)phthalic acid) 1. Total potential guest accessible void volume in 3-D 1 is found to be 4327 Å3. Based on its better porous structure and stability, the ability of 1 to adsorb organic dyes is investigated. It has been proved that (i) 1 can selectively adsorb cationic dyes as Azure A (AA+) and/or Methylene Blue (MB+), rather than neutral and anionic ones; (ii) the maximum adsorption capacity is 698.2 mg·g−1 for AA+ and 573.2 mg·g−1 for MB+, respectively; and (iii) to the adsorption of AA+, it can be recycled for at least five rounds. Also, it is utilized to fabricate the while-light emitting material. Based on the blue-light emission of 1, the trace Eu3+ and Tb3+ ions are introduced into the pores of 1 successfully, obtaining a white-light emitting material Eu3+/Tb3+@1 (CIE chromaticity coordinates: (0.33, 0.32)). Meanwhile, Eu3+/Tb3+@1 is found to be a potential fluorescence photochromic material, showing a yellow-white-blue light emission. According to these investigations, the relationship between material structure and its adsorption property for dyes, the points that should be paid attention to in the construction of white-light emitting materials as well as the potential adsorption mechanism for dyes and rare earth ions are deeply discussed.

Spinal Dopaminergic Mechanisms Regulating the Micturition Reflex in Male Rats with Complete Spinal Cord Injury.

Traumatic spinal cord injury (SCI) often causes micturition dysfunction. We recently discovered a low level of spinally-derived dopamine (DA) that regulates recovered bladder and sphincter reflexes in SCI female rats. Considering substantial sexual dimorphic features in the lower urinary tract, it is unknown if the DA-ergic mechanisms act in the male. Histological analysis showed a similar distribution of tyrosine hydroxylase (TH)+ neurons in the lower cord of male rats and the number increased following thoracic SCI. Subsequently, focal electrical stimulation in slices obtained from L6/S1 spinal segments of SCI rats elicited detectable DA release with fast scan cyclic voltammetry. Using bladder cystometrogram and external urethral sphincter (EUS) electromyography in SCI male rats, intravenous (i.v.) administration of SCH 23390, a D1-like receptor (DR1) antagonist, induced significantly increased tonic EUS activity and a trend of increased residual volume, whereas activation of these receptors with SKF 38393 did not influence the reflex. Meanwhile, blocking spinal D2-like receptors (DR2) with remoxipride had no effect but stimulating these receptors with quinpirole elicited EUS bursting to increase voiding volume. Further, intrathecal delivery of SCH 23390 and quinpirole resulted in similar responses to those with i.v. delivery, respectively, which indicates the central action regardless of delivery route. In addition, metabolic cage assays showed that quinpirole increased the voiding frequency and total voiding volume in spontaneous micturition. Collectively, spinal DA-ergic machinery regulates recovered micturition reflex following SCI in male rats; spinal DR1 tonically suppress tonic EUS activity to enable voiding and activation of DR2 facilitates voiding.

Evaluation of the performance of integrated bioreactors for anaerobic digestion of organic wastes to biogas

The evaluation of the performance of an integrated bioreactor was carried out using organic municipal waste as the substrate. The test rig of the coupled bioreactor was designed and fabricated for experimented studies of anaerobic digestion of organic fraction of municipal waste. The first module up-flow bioreactor (UASB), has volume of 76 liter, the second module which was designed as twin in bioreactor with central dispensing unit has a total void volume of 76 liters. The test rig has a control panel which can be switch off and on from the experiment the maximum biogas yield was obtained in OLR3 module 11 with 1577 ml/stp followed by OLR1 module 1 with 1572 ml/stp. The least was noticed from the twin reactor OLR2 module 11 with 895 ml/stp. The accumulative biogas yield and R-values obtained show close agreement between observed and theoretical postulate.