Microstructural analysis of surface and interface zones in concrete

Several of OPC paste and concrete specimens, with different mix proportions, were cast against CPF and impermeable formwork (IF) and the profiles of pore structure, microhardness and scratch hardness of the cover zone were established. The chloride ingress and the depth of carbonation of the surface zone of concrete cast against CPF and IF were investigated. The main mechanisms controlling the ECR processes and the factors affecting such treatment were critically reviewed. Subsequently, as a means of restoring passivation of steel embedded in carbonated concrete, such HCP specimens were subjected to ECR. The influence of ECR on the chemistry of the pore solution and the microstructure of the surface and the steel/cement past interface zones were also studied. The main findings of this investigation were as follows: (a) The thickness of the microstructure gradient of cover concrete is significantly decreased with increasing period of water curing but is relatively unaffected by curing temperature, w/e ratio and the use of cement replacement materials. (b) The scratch hardness technique was shown to be potentially useful for characterising the microstructure and microhardness gradients of the surface zone. (c) A relationship between the microstructure gradient and mass transport properties of the surface zone was established. (d) The use of CPF resulted in a significant reduction in porosity of both the cement paste matrix and the aggregate/cement paste transition zone, and a marked improvement in the resistance of the surface zone to carbonation and the ingress of chloride ions. (e) The ECR treatment resulted in a marked densification of the pore structure and in changes to the pore solution chemistry and the cement phases of near-surface and steel/cement paste transition zones. This effect was more pronounced with current density, period of treatment and particularly with the use of sodium phosphate as an electrolyte

Isolation and identification of native microalgae for biodiesel production

La demande croissante en carburants, ainsi que les changements climatiques dus au réchauffement planétaire poussent le monde entier à chercher des sources d’énergie capables de produire des combustibles alternatifs aux combustibles fossiles. Durant les dernières années, plusieurs sources potentielles ont été identifiées, les premières à être considérées sont les plantes oléagineuses comme source de biocarburant, cependant l’utilisation de végétaux ou d’huiles végétales ayant un lien avec l’alimentation humaine peut engendrer une hausse des prix des denrées alimentaires, sans oublier les questions éthiques qui s’imposent. De plus, l'usage des huiles non comestibles comme sources de biocarburants, comme l’huile de jatropha, de graines de tabac ou de jojoba, révèle un problème de manque de terre arable ce qui oblige à réduire les terres cultivables de l'industrie agricole et alimentaire au profit des cultures non comestibles. Dans ce contexte, l'utilisation de microorganismes aquatiques, tels que les microalgues comme substrats pour la production de biocarburant semble être une meilleure solution. Les microalgues sont faciles à cultiver et peuvent croitre avec peu ou pas d'entretien. Elles peuvent ainsi se développer dans des eaux douces, saumâtres ou salées de même que dans les terres non cultivables. Le rendement en lipide peut être largement supérieur aux autres sources de biocarburant potentiel, sans oublier qu’elles ne sont pas comestibles et sans aucun impact sur l'industrie alimentaire. De plus, la culture intensive de microalgues pour la production de biodiesel pourrait également jouer un rôle important dans l'atténuation des émissions de CO2. Dans le cache de ce travail, nous avons isolé et identifié morphologiquement des espèces de microalgues natives du Québec, pour ensuite examiner et mesurer leur potentiel de production de lipides (biodiesel). L’échantillonnage fut réalisé dans trois régions différentes du Québec: la région de Montréal, la gaspésie et le nord du Québec, et dans des eaux douces, saumâtres ou salées. Cent souches ont été isolées à partir de la région de Montréal, caractérisées et sélectionnées selon la teneur en lipides et leur élimination des nutriments dans les eaux usées à des températures différentes (10 ± 2°C et 22 ± 2°C). Les espèces ayant une production potentiellement élevée en lipides ont été sélectionnées. L’utilisation des eaux usées, comme milieu de culture, diminue le coût de production du biocarburant et sert en même temps d'outil pour le traitement des eaux usées. Nous avons comparé la biomasse et le rendement en lipides des souches cultivées dans une eau usée par apport à ceux dans un milieu synthétique, pour finalement identifié un certain nombre d'isolats ayant montré une bonne croissance à 10°C, voir une teneur élevée en lipides (allant de 20% à 45% du poids sec) ou une grande capacité d'élimination de nutriment (>97% d'élimination). De plus, nous avons caractérisé l'une des souches intéressantes ayant montré une production en lipides et une biomasse élevée, soit la microalgue Chlorella sp. PCH90. Isolée au Québec, sa phylogénie moléculaire a été établie et les études sur la production de lipides en fonction de la concentration initiale de nitrate, phosphate et chlorure de sodium ont été réalisées en utilisant de la méthodologie des surfaces de réponse. Dans les conditions appropriées, cette microalgue pourrait produire jusqu'à 36% de lipides et croitre à la fois dans un milieu synthétique et un milieu issu d'un flux secondaire de traitement des eaux usées, et cela à 22°C ou 10°C. Ainsi, on peut conclure que cette souche est prometteuse pour poursuivre le développement en tant que productrice potentielle de biocarburants dans des conditions climatiques locales.The continuing increase in fuel demands, the dramatic situation in climate changes and the global warming are bringing the worldwide attention to the identification of alternative energy source for the production of combustibles that can replace fossil fuel. In last years, a lot of potential sources have been identified: the first potential biofuel feedstock that have been evaluated were oleaginous plants, but the utilization of vegetable, or vegetable oils, that may also be used for human feeding, could lead to the increase of food-grade oils costs and also generate ethic questions. Nevertheless, also using as biofuel sources not-edible oils, like oils from jatropha, tobacco seed or jojoba, the common problem for both edible and not-edible crops is the need to subtract arable land from agriculture and food industry. In this context, the utilization of aquatic microorganisms like microalgae as substrate for the production of biofuel seems to be the better solution. Microalgae are easy to cultivate and can grow with little or no attention, they can grow in fresh, brackish or salt water and in non-arable lands, moreover they are not edible with no consequences on food industry, and the oil productivity, with respect to the other potential biofuel sources, can be much higher. In addition, the intensive cultivation of microalgae for biodiesel production could also play an important role in CO2 mitigation. In this study, we isolated and morphologically identified Québec native micro algal species, surveyed and screened their potential for lipid (biodiesel) production. The sampling efforts made in three different regions of Québec: Montreal area, Gaspesie and Northern of Quebec; on fresh, brackish or saline water. One hundred strains were isolated from the Montreal area, characterized and screened for their lipid content and wastewater nutrient removal under different temperatures (10±2 ºC and 22±2 ºC). The high potential lipid producing algal species were selected. The use of wastewater as a substrate media decreases the economic cost realted to the biofuel production from microalgae as well as an interesting tool for wastewater treatment. We compared the biomass and lipid productivity of these strains on wastewater to a synthetic medium and identified a number of isolates that showed good growth at 10 ºC, gave a high lipid content (ranging from 20% to 45% of dry weight) or a high capacity for nutrient removal (>97% removal). Furthermore, we characterized one of the interesting strains that revealed high lipid and biomass productivity, the novel microalga Chlorella sp. PCH90. Its molecular phylogeny was established and lipid production studies as a function of the initial concentrations of nitrate, phosphate, and sodium chloride were carried out using Response Surface Methodology. Under the appropriate conditions this microalga could produce up to 36% lipid and grew well in both synthetic medium and secondary effluent from a wastewater treatment plant at both 22°C and 10°C. Thus, this strain is promising for further development as a potential biofuels producer under local climatic conditions

SYNTHESIS AND UTILITY OF NEW POLYCYCLIC COMPOUNDS AS POTENTIAL ANTIMICROBIALS BASED ON CHROMENE MOIETY

Objective: The present research aims to synthesize some new polycyclic compounds including chromene moiety and study their antimicrobial activity. Methods: Several new polycyclic systems including chromene scaffold incorporated with pyridine, pyrimidine, imidazopyrimidine, and imidazodiazocine were achieved via condensation reaction of chromene derivative under the proper condition with various reagents namely; cyanothioacetamide, phenyl isothiocyanate, malononitrile, carbon disulfide, benzaldehyde, triethyl orthoformate, and 1,4-dichlorobutane. Moreover, a chlorodiazenyl chromene derivative was reacted with some substances possessing active–CH2-bridge such as ethyl cyanoacetate and malononitrile to end up with hydrazono compounds. Such compounds were eventually cyclized with hydrazine hydrate to form pyrazole and oxopyrazole derivatives. Moreover, compound 1 was treated with benzoyl acetone, and then followed by cyclization with malononitrile to provide the corresponding 2-amino14-(4-methoxyphenyl)-4-methy-5-phenyl-14H-benzo[5,6] chromeno [2,3H][1,6]naphthyridine-3-carbonitrile (20). Results: The results of the antimicrobial screening in vitro revealed that the inhibition zone (mm) of the synthesized compounds 1-3, 5 and 8 implied their optimum antibacterial activity, while the compounds 4, 6 and 9-13, 15 showed a moderate to weak antibacterial activity against multiple species of B. subtilis, S. aureus, E. coli and P. aeruginosa. In contrast, the compounds 1, 6, 11, 15 showed high antifungal activities against different species of A. flavinand C. albicans, while the other compounds exhibit a moderate to poor antifungal activity. Conclusion: It is remarkable that a series of chromene derivatives synthesized by a simple and available method leads to a molecule of promising antimicrobial activity. Further research is recommended to approve the importance of polycyclic systems for various applications

Exploring the Diversity of Physiology for Applications in Wastewater Treatment and Biofuels Production

A recently established strain collection of freshwater microalgae native to Quebec was examined for physiological diversity. The 100 strains appeared very heterogeneous in terms of growth when they were cultured at 10±2 °C or 22±2 °C on the secondary effluent from a municipal wastewater treatment plant (WW) and defined BBM medium. Scatterplots were used to examine the diversity in physiology that might be present in the collection. These showed a number of interesting results. There was a fair amount of dispersion in growth rates by media type independent of temperature. Surprisingly considering that all the isolates had been initially enriched on BBM, the distribution was quite symmetrical around the iso-growth line, suggesting that enrichment on BBM did not seem to bias the cells for growth on this medium versus WW. As well, considering that all the isolates had been initially enriched at 22 °C, it is quite surprising that the distribution of specific growth rates was quite symmetrical around the iso-growth line with roughly equal numbers of isolates found on either side. Thus enrichment at 22 °C does not seem to bias the cells for growth at this temperature versus 10°C. The scatterplots obtained when the percentage lipid of cultures grown on BBM were compared with cultures grown on WW at either 10 °C or 22 °C made it apparent that lipid production was favored by growth on WW at either temperature and that lipid production does not seem to be particularly favored by one temperature over the other. When the collection was queried for differences with respect to sampling location, statistical analysis showed that roughly the same degree of physiological diversity was found with samples from the two different aggregate locations.This research was supported by a grant from FQRNT (Le Fonds Québécois de la recherche sur la nature et les technologies), programme de recherche en partenariat contribuant à la séquestration des gaz à effet de serre (2011-GZ-141307) to P.C.H

Algal Biofuels: Challenges and Opportunities

Biodiesel production using microalgae is attractive in a number of respects. Here a number of pros and cons to using microalgae for biofuels production are reviewed. Algal cultivation can be carried out using non-arable land and non-potable water with simple nutrient supply. In addition, algal biomass productivities are much higher than those of vascular plants and the extractable content of lipids that can be usefully converted to biodiesel, triacylglycerols (TAGs) can be much higher than that of the oil seeds now used for first generation biodiesel. On the other hand, practical, cost-effective production of biofuels from microalgae requires that a number of obstacles be overcome. These include the development of low-cost, effective growth systems, efficient and energy saving harvesting techniques, and methods for oil extraction and conversion that are environmentally benign and cost-effective. Promising recent advances in these areas are highlighted

A Molecular Dynamics Study of Water Confined In Between Two Graphene Sheets Under Compression

Several studies have demonstrated interest in creating surfaces with improved water interaction and adaptive properties because the behavior of water confined at the nanoscale plays a significant role in the synthesis of materials for technological applications. Remarkably, confinement at the nanoscale significantly modifies the characteristics of water. We determine the phase diagram of water contained by graphene stack sheets in slab form, at T=300 K, and for a constant pressure using molecular dynamics simulations. We discover that, as shown in the simulation, water can exist in both the liquid and vapor phases depending on the confining geometry and compressibility ratio. We also pay attention to how stable the interacting liquid is in relation to the pressure of compression that is perpendicular to the graphene sheets. To build this system and analyze its surface interface properties, we also used analytical and electronic scale modeling approaches. The impact of nanoconfinement on internal pressure may be seen in water, and this can be used to create interfacial materials for the creation of environmentally friendly solar cell materials. Our research highlights the intricate, seemingly random behavior of nanoconfined water—behavior that is difficult for graphene to understand. The results obtained offer crucial direction for system design and configuration of materials at the graphene/water interface that can be utilized as a benchmark for other future designs

Solar-wind ventilation to enhance the cabinet dryer performance for medicinal herbs and horticultural products

This paper presents the design, construction and performance evaluation of a mixed-mode solar cabinet dryer (SCD) for medicinal herbs and horticultural products.  Solar- wind ventilation system is used to enhance the cabinet dryer performance.  The solar cabinet is equipped with a vertical blackened solar chimney and a flat plate solar collector to enhance buoyancy force.  The chimney is provided with suction axial fan that can rotate smoothly by wind power.  The performance of SCD was evaluated without load (empty) and with load (potato chips and peppermint).  After performing various standardized pretreatments, products were dried separately under open sun, SCD and electric oven.  Results of parametric studies indicated that, highest drying air temperature was achieved at 60° collector tilt angle followed by 30°, when the dehydration system tracked the sun.  The developed SCD exhibited sufficient ability to dry the chips and peppermint reasonably to a safe moisture level within 9-10 and 5-6 hrs (≈1 clear sunny day), respectively.  The best chips colour was achieved at 15 s frying time.  All the fried chips and dried peppermint were well accepted by the panelists.  The SCD ensures a superior quality of the dried products.  In terms of electricity requirement, frying time, health conscious and utilization of solar energy, the enhanced SCD is considered a suitable method for drying potato chips as well as peppermint. Keywords: solar cabinet, solar collector, windmill, drying, chips, peppermint

Host range, damage and seasonality of fruit flies in Sennar State, Sudan

    Fruit flies (Diptera: Tephritidae) are one of the most economically important groups of insects in the afrotropical region because they cause damage to fruits and vegetables. Integrated fruit fly (FF) control program requires accurate data about taxonomy, incidence, distribution and seasonality of the members of this pest. Surveys and collection missions were carried out in Sennar State during January  2006- January 2008. Yellow sticky traps were used for adult collection. Trapped  fruit flies were labeled, identified and counted monthly to estimate their abundance throughout the year. In addition, infested fruits of mango, guava, grapefruit, orange, banana, melons, pumpkin, watermelon, and the wild magad (Cucurbitaceae) were collected monthly from the surveyed areas. Larvae were reared till the adult stage and identified. Field infestation rate of FF species was determined on mango and guava at Singa area. Percentage of FF infestation on mango Baladi cultivar was 10% in March, 15% in April and 20% in May. During the period from June to August, Abu Samaka cultivar was the only mango cultivar available, and accordingly, was subjected to a heavy attack by the FF. The infestation reached 30% in June and 50% in July. The FF moved to guava, during the period from October to December. The rate of FF infestation on guava was very high during this period and ranged from 80% to 90%. Mango fruits in Singa area were infested by Bactrocera invadens (Drew, Tsuruta and White) (80%), C. cosyra (19.8%) and Dacus longistylus (Wiedemann) (0.2%) of the total emerged adults. This was the first record for the latter species in a host other than Calotropis procera (Apocynaceae). Guava fruits were infested by B. invadens (84.5%), C. cosyra (15.3%), and C. quinaria (Bezzi) (0.2%) of the total emerged adults. B. invadens seemed to out-compete and replace the indigenous species. Cucurbit fruits hosted D. ciliatus (Leow) only. The wild magad fruits hosted B. invadens and B. cucurbitae  (Coquillet). The highest population of B.invadenss was observed during July and  December (254 and 253 adults/trap, respectively). March and April showed the lowest population due to higher temperatures and low relative humidity. &nbsp

Microbiological Profile of Neonatal Sepsis at a Maternity Hospital in Omdurman, Sudan

Background: Neonatal sepsis is a clinical syndrome characterized by systemic signs of infection and accompanied by bacteremia in the first month of life. It is a major cause of morbidity and mortality in neonatal period. The study was conducted to determine microbiological profile and antibiogram of neonatal sepsis at Omdurman Maternity Hospital. Methods: This was a cross-sectional hospital-based study involving 202 neonatal blood cultures at Omdurman Maternity Hospital during the period from April 2017 to April 2018. Specimens were cultured in Brain Heart Infusion broth followed by subculture of isolates on blood agar, MacConkey agar, and Chocolate agar and incubated aerobically at 37ºC for 24 h. The isolates were tested for their susceptibility to antimicrobial agents using the Kirby Bauer disc diffusion method. Results: Of 202 positive blood cultures, 130 cases (64.4%) were early onset and 72 cases (35.6%) were recorded for late onset sepsis. Gram-negative pathogens approaching (123, 60.9%). Staphylococcus aureus was the most common organism in both groups of neonatal sepsis being isolated from (71, 35.7%), followed by Klebsiella pneumoniae (43, 21.2%). Gram-negative organisms were sensitive to Imepenem (97.3%) and Meropenem (80.5%) and resistant to third-generation Cephalosporins (65.3%) and Amoxicillin/Clavulanic acid (91.4%). Gram-positive organisms were resistant to Cefotaxime (75%), Amoxicillin/Clavulanic acid (65.4%), and Clindamycin (68.2%); 91.6% of gram-positive isolates were sensitive to Vancomycin. Conclusion: Gram-negative pathogens took the major spectrum of isolates. Klebsiella pneumoniae (21.2%) was the most frequent gram-negative organism. Methicillinresistant Staphylococcus aureus (MRSA) (33.7%) was the most common isolate. Most of the isolates were multidrug resistant. The best choice for treatment is Vancomycin (8.4%) and Imepenem (2.7%) for gram-positive and gram-negative, respectively. Adherence to antibiotic policy, antimicrobial surveillance, and policy updating is necessary

Patient Optimization is the Key in Surgical Repair of Ruptured Umblical Hernia in Cirrhotic Patients and Tense Ascitis

Background: Ulceration, leakage, and rupture are considered as the most common complications of umbilical hernias in patients with refractory ascites due to advanced cirrhosis. We aim to determine optimal management and outcome after umbilical herniorrhaphy or hernioplasty in those patients