Biological hydrogen production by anaerobic fermentation

Considering the energy security and the global environment, there is a pressing need to develop non-polluting and renewable energy sources. Alternatively, hydrogen is a clean energy carrier, producing water as its only by-product when it burns. Anaerobic bioconversion of organic wastes to hydrogen gas is an attractive option that not only stabilizes the waste/wastewater, but also generates a benign renewable energy carrier. The purposes of this study were to determine the kinetics of hydrogen production using different characteristics of substrates and to evaluate hydrogen production potential from different operating conditions in continuous operation;The growth kinetics of hydrogen-producing bacteria using three different substrates including sucrose, non-fat dry milk (NFDM), and food waste were investigated through a series of batch experiments. The results demonstrated that hydrogen production potential and hydrogen production rate increased with an increasing substrate concentration. The maximum hydrogen yields from sucrose, NFDM, and food waste were 234, 119, and 101 mL/g COD, respectively. The low pH (pH \u3c 4) inhibited hydrogen production and resulted in lower carbohydrate fermentation at high substrate concentrations. The Michaelis-Menten equation was employed to model the hydrogen production rate at different substrate concentrations. The equation gave a good approximation of the maximum hydrogen production rate and the half saturation constant (KS) with correlation coefficient (R2) over 0.85. The values of half saturation constant (KS) for sucrose, NFDM, and food waste were 1.4, 6.6, and 8.7 g COD/L, respectively. Based on the Ks values, the substrate affinity of the enriched hydrogen-producing culture was found to depend on the carbohydrate content of the substrate. The substrate containing high carbohydrates showed a lower KS value. The maximum hydrogen production rate was governed by the complexity of carbohydrates in the substrate. Biological hydrogen production from sucrose-rich substrate was investigated in an anaerobic sequential batch reactor (ASBR). The goal of this study was to investigate the effect of different hydraulic retention times (HRT) (8, 12, 16, 24, and 48 h), pHs (4.9, 5.5, 6.1, and 6.7), substrate concentrations (15, 25, and 35 g COD/L), and cyclic durations (4, 6, and 8 h) on biological hydrogen production. The maximum hydrogen yield of 2.53 mol H2/mol sucrose consumed and the maximum hydrogenic activity of 538 mL H2/g VSS-d were obtained at HRT of 16h, pH 4.9, sucrose concentration of 25 g COD/L, and feeding cycle of 4 h. Methane was detected in the biogas when solids retention time (SRT) exceeded 100 h at pH of 6.7. Based on the low ethanol concentration of nearly 300 mg/L, the metabolic pathway shift to solvent fermentation was not observed at pH of 4.9. The ratios of butyrate (HBu) to acetate (HAc) decreased from 1.25 to 0.54 mol/mol, when the sucrose concentration was increased from 15 to 35 g COD/L. This suggests that the metabolic pathway of acetate fermentation was predominant at higher sucrose concentrations. Hydrogen production was found to improve at a shorter feeding cycle of 4 h;Fluorescent in situ hybridization (FISH) was applied for identifying and quantifying the specific microbial populations in the study. Most bacteria successfully identified by an EUB338 probe were counted and the percentages of 16S rDNA of EUB338 to DAPI at different reactor operating conditions were determined. Due to the false positive hybridization results, the ARC915 probe was found unsuitable for identifying cells belonging to the domain Archaea in this study. FISH results using the probe CLOST I were not fully determined because of the difficulty of recognizing the hybridized clostridia cluster I. Therefore, a correlation between hydrogen production and the number of Clostridium belonging to clostridia cluster I was not determined

Management practices and influences on IT architecture decisions: a case study in a telecom company

The study aims to analyze the IT architecture management practices associated with their degree of maturity and the influence of institutional and strategic factors on the decisions involved through a case study in a large telecom organization. The case study allowed us to identify practices that led the company to its current stage of maturity and identify practices that can lead the company to the next stage. The strategic influence was mentioned by most respondents and the institutional influence was present in decisions related to innovation and those dealing with a higher level of uncertainties

Experience Sharing and Evaluation Results of Adaptation Technologies Due to Global Climate Change in Water Shortage Irrigation Zone of Taiwan

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchive

Large Scale Model Test for Pile-Supported Wharf in Liquefied Sand

Pile-supported wharf is a general option in port design to provide lateral resistance and bearing capacity under both static and dynamic loadings. In situ large-scale physical modeling using surface wave generator was performed to study the dynamic soil-structure interactions in pile-supported wharves and to serve as a prototype for in situ monitoring station. A wharf model consisting of 2 steel pipe piles welded on a steel slab was installed on a reconstituted underwater embankment. Due to screening of stress wave, the two piles are subjected to different loading conditions. Data reduction procedures were developed to analyze coupled shear strain-pore pressure generation behavior, pile responses, and soil-pile interaction characteristics. The results proved that the physical modeling can capture the interactions among the induced shear strain, generated excess pore pressure, and dynamic p-y behavior around piles. Preliminary results also show that evolutions of dynamic p-y curve with excess pore pressure variations should be included in soil-pile interaction modeling

A Bayesian measurement error model for two-channel cell-based RNAi data with replicates

RNA interference (RNAi) is an endogenous cellular process in which small double-stranded RNAs lead to the destruction of mRNAs with complementary nucleoside sequence. With the production of RNAi libraries, large-scale RNAi screening in human cells can be conducted to identify unknown genes involved in a biological pathway. One challenge researchers face is how to deal with the multiple testing issue and the related false positive rate (FDR) and false negative rate (FNR). This paper proposes a Bayesian hierarchical measurement error model for the analysis of data from a two-channel RNAi high-throughput experiment with replicates, in which both the activity of a particular biological pathway and cell viability are monitored and the goal is to identify short hair-pin RNAs (shRNAs) that affect the pathway activity without affecting cell activity. Simulation studies demonstrate the flexibility and robustness of the Bayesian method and the benefits of having replicates in the experiment. This method is illustrated through analyzing the data from a RNAi high-throughput screening that searches for cellular factors affecting HCV replication without affecting cell viability; comparisons of the results from this HCV study and some of those reported in the literature are included.Comment: Published in at http://dx.doi.org/10.1214/11-AOAS496 the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

One-stage reconstruction of large lower lip defect and oral competence with free composite anterolateral thigh-tensor fasciae latae flap

SummaryReconstruction for a large lower lip defect is a challenge to reconstructive surgeons. The most challenging problem is to maintain oral competence and prevent sialorrhea. We present three cases of such a defect reconstructed with composite anterolateral thigh-tensor fascia lata free flaps in one stage. The patients reported in this communication had advanced squamous cell carcinoma in the lower lip. A large lower lip defect (>90%) resulted in each case from wide excision of the tumor. A composite anterolateral thigh-tensor fasciae latae free flap was used to reconstruct the defect and to restore the dynamic oral competence in one stage. A tensor fasciae latae sling was attached by two strips sutured together to the upper orbicularis oris muscle in the first case. The four-strip method, a modification of the method described by Serkan,1 was adopted in the second case. The upper two strips bilaterally sutured to the orbicularis oris muscles in a mode somewhat different from Serkan’s method. The tensor fasciae latae sling was attached by two strips sutured to the periosteum of both zygomatic eminences in the third case. The tensor fasciae latae sling of Case 1 failed with persistent sialorrhea. The second case had good oral competence and comprehensible speech ability without sialorrhea. The third case had an acceptable result before he was lost to follow-up. A composite anterolateral thigh-tensor fasciae latae free flap is a good choice for a large lower lip defect to achieve oral competence reconstruction in one stage. Simultaneous dynamic and static suspensions are suggested to maintain oral competence and prevent sialorrhea

Dynamic Mechanical Response of Biomedical 316L Stainless Steel as Function of Strain Rate and Temperature

A split Hopkinson pressure bar is used to investigate the dynamic mechanical properties of biomedical 316L stainless steel under strain rates ranging from 1 × 103 s−1 to 5 × 103 s−1 and temperatures between 25°C and 800°C. The results indicate that the flow stress, work-hardening rate, strain rate sensitivity, and thermal activation energy are all significantly dependent on the strain, strain rate, and temperature. For a constant temperature, the flow stress, work-hardening rate, and strain rate sensitivity increase with increasing strain rate, while the thermal activation energy decreases. Catastrophic failure occurs only for the specimens deformed at a strain rate of 5 × 103 s−1 and temperatures of 25°C or 200°C. Scanning electron microscopy observations show that the specimens fracture in a ductile shear mode. Optical microscopy analyses reveal that the number of slip bands within the grains increases with an increasing strain rate. Moreover, a dynamic recrystallisation of the deformed microstructure is observed in the specimens tested at the highest temperature of 800°C

Biomechanical comparison of lumbar spine instability between laminectomy and bilateral laminotomy for spinal stenosis syndrome – an experimental study in porcine model

<p>Abstract</p> <p>Background</p> <p>The association of lumbar spine instability between laminectomy and laminotomy has been clinically studied, but the corresponding <it>in vitro </it>biomechanical studies have not been reported. We investigated the hypothesis that the integrity of the posterior complex (spinous process-interspinous ligament-spinous process) plays an important role on the postoperative spinal stability in decompressive surgery.</p> <p>Methods</p> <p>Eight porcine lumbar spine specimens were studied. Each specimen was tested intact and after two decompression procedures. All posterior components were preserved in Group A (Intact). In Group B (Bilateral laminotomy), the inferior margin of L4 lamina and superior margin of L5 lamina were removed, but the L4–L5 supraspinous ligament was preserved. Fenestrations were made on both sides. In Group C (Laminectomy) the lamina and spinous processes of lower L4 and upper L5 were removed. Ligamentum flavum and supraspinous ligament of L4–L5 were removed. A hydraulic testing machine was used to generate an increasing moment up to 8400 N-mm in flexion and extension. Intervertebral displacement at decompressive level L4–L5 was measured by extensometer</p> <p>Results</p> <p>The results indicated that, under extension motion, intervertebral displacement between the specimen in intact form and at two different decompression levels did not significantly differ (<it>P </it>> 0.05). However, under flexion motion, intervertebral displacement of the laminectomy specimens at decompression level L4–L5 was statistically greater than in intact or bilateral laminotomy specimens (<it>P </it>= 0.0000963 and <it>P </it>= 0.000418, respectively). No difference was found between intact and bilateral laminotomy groups. (<it>P </it>> 0.05).</p> <p>Conclusion</p> <p>We concluded that a lumbar spine with posterior complex integrity is less likely to develop segment instability than a lumbar spine with a destroyed anchoring point for supraspinous ligament.</p