Hydrogen peroxide and lime based oxidative pretreatment of wood waste to enhance enzymatic hydrolysis for a biorefinery: Process parameters optimization using response surface methodology

Response surface methodology (RSM) was adopted for the optimization of process variables in the alkaline peroxide oxidation (APO) pretreatment of Vitellaria paradoxa sawdust based on central composite design (CCD) experiments. A 23 five level CCD with central and axial points was used to develop a statistical model for the optimization of process variables. Maximum response for the pretreatment was obtained when applying the optimum values for temperature (150 �C), time (45 min), and 1% (v/v) H2O2. At the optimum conditions, up to 70% of the initial hemicellulose was removed in treatments, which also caused some delignification (up to 11% of the initial lignin was removed), whereas cellulose was almost quantitatively retained in the solid phase. Alkaline peroxide assisted wet air oxidation (APAWAO) pretreatment at the optimum conditions resulted in enrichment up to 60% cellulose content along with solubilization of 80% hemicellulose and 17% of lignin initially present in the raw sawdust. Reducing sugars yield after 72 h enzymatic hydrolysis of pretreated biomass at optimized APO conditions was 177.89 mg equivalent glucose g�1 dry biomass. Addition of 10 bar air pressure at the optimized pretreatment conditions increased the sugars yield to 263.49 mg equivalent glucose g�1 dry biomass

Efficiency of molecular markers to select for Striga gesnerioides resistance in cowpca [Vigna unguiculata (L.)Walp]

Striga gesnerioides (Willd) Vatke is a major biological constraint to cowpea productivity in the dl) savannas of sub-Saharan Africa. Over the last two decades, the use of molecular markers in crop improvemem has gained prominence owing to its ability to sh0l1en the breeding cycle. The available molecular markel techniques are being improved upon and continuously tested for higher preci sion, shOl1er duration of application and better cost effectiveness. [n the present study, a total of four molecular markers developed for selecting Slriga resistant cowpea were used to genotype F2 population derived from a cross between Borno Brown and [T97K-499-35 to identify markers more close ly linked to S. gesnerioides resistance. SSRI and 2 were found 10 be tight ly linked to Striga gesnerioides with a genetic distance of 1 and 2cM.The selection efficiency of SS~I and SSR-2 were 99 and 98 % and was better than that of C42-B 85.5%

Modelling of sweet gas flaring and the resultant gaseous emissions with their emission factors

Data from literature and a stoichiometric material balance model were employed to estimate associated emissions with flaring of sweet gas in Nigerian oil and gas companies. Emission factors were obtained using AP 42 formula. Results showed that thousands of tonnes, ranging from 6500 to 22,000 tonnes of natural gas were flared from 1997 to 2016. At flaring stack efficiencies of 97% and 98%, the associated emissions are: CH4, C2H6, C3H8, iC4H10, nC4H10, iC5H12, nC5H12, C6H14, C7H16, C8H18, C9H20, CO2, and N2 from unburnt natural gas and in addition to CO2, CO, N2, NO, NO2, H2O and H2 from incomplete combustion. At both flaring stack efficiencies, the amount of emissions from unburnt condition ranged from1,608 tonnes N2 to 9,146 tonnes CO2 all higher than any emission standards in the world, while the amounts of emissions from incomplete combustion ranged from 467,964 tonnes for CO2 the lowest to 2,476,011 tonnes for N2 the highest all higher than any emission standards in the globe. Emission factors of emissions from unburnt natural gas ranged from 0.000090 tonne/tonne for C10H22 to 0.026235 tonne/tonne for CH4 while those of the emissions from incomplete combustion ranged from 0.10285 tonne/tonne for H2 to 1.13137 for CO2 tonne/tonne. It was observed that thousands of tonnes of emissions are released into the atmosphere during flaring of sweet natural gas either at complete or incomplete combustion. It is recommended that flaring of natural gas should be reduced to a minimal level to safeguard the environment

The training and professional expectations of medical students in Angola, Guinea-Bissau and Mozambique

<p>Abstract</p> <p>Background</p> <p>The purpose of this paper is to describe and analyze the professional expectations of medical students during the 2007-2008 academic year at the public medical schools of Angola, Guinea-Bissau and Mozambique, and to identify their social and geographical origins, their professional expectations and difficulties relating to their education and professional future.</p> <p>Methods</p> <p>Data were collected through a standardised questionnaire applied to all medical students registered during the 2007-2008 academic year.</p> <p>Results</p> <p>Students decide to study medicine at an early age. Relatives and friends seem to have an especially important influence in encouraging, reinforcing and promoting the desire to be a doctor.</p> <p>The degree of feminization of the student population differs among the different countries.</p> <p>Although most medical students are from outside the capital cities, expectations of getting into medical school are already associated with migration from the periphery to the capital city, even before entering medical education.</p> <p>Academic performance is poor. This seems to be related to difficulties in accessing materials, finances and insufficient high school preparation.</p> <p>Medical students recognize the public sector demand but their expectations are to combine public sector practice with private work, in order to improve their earnings. Salary expectations of students vary between the three countries.</p> <p>Approximately 75% want to train as hospital specialists and to follow a hospital-based career. A significant proportion is unsure about their future area of specialization, which for many students is equated with migration to study abroad.</p> <p>Conclusions</p> <p>Medical education is an important national investment, but the returns obtained are not as efficient as expected. Investments in high-school preparation, tutoring, and infrastructure are likely to have a significant impact on the success rate of medical schools. Special attention should be given to the socialization of students and the role model status of their teachers.</p> <p>In countries with scarce medical resources, the hospital orientation of students' expectations is understandable, although it should be associated with the development of skills to coordinate hospital work with the network of peripheral facilities. Developing a local postgraduate training capacity for doctors might be an important strategy to help retain medical doctors in the home country.</p

Evaluation of Methods for the Analysis of Untreated and Processed Lignocellulosic Biomasses

The overall efficiency of the transformation of lignocellulosic materials to usable products as chemicals and fuels must be governed by adequate analysis of products before and after treatments. Using some promising technologies, lignocelluloses which are biomasses from marine plant and trees, grains, food and non-food crops, and woodbased can give products as fuel alcohol and other chemicals. Various methods of transformation from feedstock to valuable end products are discussed in the scientific literature. Therefore, yields must justify methods used for biomass transformations. As a result, adequate compositional analysis of these processing stages is needed. In this chapter, standard common methods such as gravimetric, chromatography, spectroscopic and their variations for analysis on both untreated and treated lignocelluloses are highlighted. The ease of the use and challenges with recommendations to their applicability to quantifying lignocelluloses fractionations for reproducibility and to be representative are discussed. With biomass technology, virtually all and even more products that can be produced from fossil energy can also be produced from biomass energy. Adequate analysis is therefore necessary

Assessment of the Performance of Osmotically Driven Polymeric Membrane Processes

The universal water scarceness and the extensive ordeals with energy cost in conjunction with the undesirable ecological effects have advanced the improvement of novel osmotically driven membrane processes. Membrane processes which are osmotically driven are developing type of membrane separation procedures that apply concentrated brines to separate liquid streams. They are adaptable in various applications; hence, allow them to be an attractive substitute for drug release, wastewater treatment and the production and recovery of energy. Although, internal concentration polarization (ICP) occurs in membrane practises which are osmotically driven as a consequence of hindered diffusion of solute in a porous stratum, their interest has even increased. Here we review two natural membrane processes that are osmotically driven; Forward osmosis (FO) and Pressure retarded osmosis (PRO). Thus, the major points are as follows: 1) it was highlighted in this review, that the major developments in FO process, important for the process efficiency is to choose a suitable membrane and draw solution. 2) The recent evaluation, understanding and optimizing the activities of fouling throughout the osmotic dilution of seawater employing FO was discussed. 3) Recent advancements of FO in the application of food processing was reviewed. 4) It was highlighted that the main concept of PRO for power generation is the energy of mixing that offers great assessment of the nonexpansion work which could be generated from mixing; nonetheless, the development of effective membranes with appropriate arrangement and performance is needed for the advancement of PRO process for power generation. 5) One major challenge of osmotically driven membrane processes, most recent developments and model development to predict their performances were discussed

Mortality and pulmonary complications in patients undergoing surgery with perioperative sars-cov-2 infection: An international cohort study

Background The impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on postoperative recovery needs to be understood to inform clinical decision making during and after the COVID-19 pandemic. This study reports 30-day mortality and pulmonary complication rates in patients with perioperative SARS-CoV-2 infection. Methods This international, multicentre, cohort study at 235 hospitals in 24 countries included all patients undergoing surgery who had SARS-CoV-2 infection confirmed within 7 days before or 30 days after surgery. The primary outcome measure was 30-day postoperative mortality and was assessed in all enrolled patients. The main secondary outcome measure was pulmonary complications, defined as pneumonia, acute respiratory distress syndrome, or unexpected postoperative ventilation. Findings This analysis includes 1128 patients who had surgery between Jan 1 and March 31, 2020, of whom 835 (740%) had emergency surgery and 280 (248%) had elective surgery. SARS-CoV-2 infection was confirmed preoperatively in 294 (261%) patients. 30-day mortality was 238% (268 of 1128). Pulmonary complications occurred in 577 (512%) of 1128 patients; 30-day mortality in these patients was 380% (219 of 577), accounting for 817% (219 of 268) of all deaths. In adjusted analyses, 30-day mortality was associated with male sex (odds ratio 175 [95% CI 128-240], p&lt;00001), age 70 years or older versus younger than 70 years (230 [165-322], p&lt;00001), American Society of Anesthesiologists grades 3-5 versus grades 1-2 (235 [157-353], p&lt;00001), malignant versus benign or obstetric diagnosis (155 [101-239], p=0046), emergency versus elective surgery (167 [106-263], p=0026), and major versus minor surgery (152 [101-231], p=0047). Interpretation Postoperative pulmonary complications occur in half of patients with perioperative SARS-CoV-2 infection and are associated with high mortality. Thresholds for surgery during the COVID-19 pandemic should be higher than during normal practice, particularly in men aged 70 years and older. Consideration should be given for postponing non-urgent procedures and promoting non-operative treatment to delay or avoid the need for surgery. Funding National Institute for Health Research (NIHR), Association of Coloproctology of Great Britain and Ireland, Bowel and Cancer Research, Bowel Disease Research Foundation, Association of Upper Gastrointestinal Surgeons, British Association of Surgical Oncology, British Gynaecological Cancer Society, European Society of Coloproctology, NIHR Academy, Sarcoma UK, Vascular Society for Great Britain and Ireland, and Yorkshire Cancer Research