An ICP-MS study on metal content in biodiesel and bioglycerol produced from heated and unheated canola oils.

This study addresses the challenges of biodiesel production costs and waste oil disposal by investigating the use of low-cost waste oil as a feedstock. The impact of heating temperature on biodiesel yield and trace metal levels is examined using response surface methodology (RSM). Optimal conditions for high biodiesel yields (95-98%) from canola oil are determined with a methanol/oil ratio of 12:1, 1 wt% catalyst, and 60-min reaction time. For crude bioglycerol, the optimal conditions involve a methanol/oil ratio of 4.25:1, 2.93 wt% catalyst, and 119.15-min reaction time. Elemental analysis reveals the presence of high-concentration metals like Cu and Zn and low-concentration ones such as Pb, As, Se, and Zr in both oil feedstocks and their respective biodiesel and bioglycerol products. The study demonstrates that thermal stress on canola oil significantly impacts biodiesel and bioglycerol yields and trace metal levels during the transesterification process. The findings contribute to enhancing cost-effectiveness and environmental sustainability in biodiesel production.

Synthesis of Mesoporous Carbon Adsorbents Using Biowaste Crude Glycerol as a Carbon Source via a Hard Template Method for Efficient CO2 Capture.

Biowaste utilization as a carbon source and its transformation into porous carbons have been of great interest to promote environmental remediation owing to biowaste's cost-effectiveness and useful physicochemical properties. In this work, crude glycerol (CG) residue from waste cooking oil transesterification was employed to fabricate mesoporous crude glycerol-based porous carbons (mCGPCs) using mesoporous silica (KIT-6) as a template. The obtained mCGPCs were characterized and compared to commercial activated carbon (AC) and CMK-8, a carbon material prepared using sucrose. The study aimed to evaluate the potential of mCGPC as a CO2 adsorbent and demonstrated its superior adsorption capacity compared to AC and comparable to CMK-8. The X-ray diffraction (XRD) and Raman results clearly depicted the structure of carbon nature with (002) and (100) planes and defect (D) and graphitic (G) bands, respectively. The specific surface area, pore volume, and pore diameter values confirmed the mesoporosity of mCGPC materials. The transmission electron microscopy (TEM) images also clearly revealed the porous nature with the ordered mesopore structure. The mCGPCs, CMK-8, and AC materials were used as CO2 adsorbents under optimized conditions. The mCGPC adsorption capacity (1.045 mmol/g) is superior to that of AC (0.689 mmol/g) and still comparable to that of CMK-8 (1.8 mmol/g). The thermodynamic analyses of the adsorption phenomena are also carried out. This work demonstrates the successful synthesis of a mesoporous carbon material using a biowaste (CG) and its application as a CO2 adsorbent.

Prevalence and Risk Factors of Hypertension in Hargeisa, Somaliland: A Hospital-Based Cross-Sectional Study.

Hypertension is the leading risk factor for cardiovascular diseases and represents a major public health challenge worldwide. There is a paucity of information regarding the hypertension status of adults in Somaliland. We aimed to assess the magnitude of, and factors associated with, hypertension among adult patients seeking care at Hargeisa group hospital in Hargeisa city, Somaliland. We conducted a health facility-based cross-sectional study enrolling adult outpatients. We used the World Health Organization (WHO) STEPwise surveillance approach to obtain patient information. A total of 319 participants (54.2% males; mean age 40.4 ± 14.0 years) had complete data records. The prevalence of hypertension was 22.6% (95% confidence interval; 18.2-27.6%). The prevalence of hypertension increased with age and was higher in males (24.9%) than in females (19.9%). Age, cholesterolaemia and obesity were significantly associated with hypertension. Separate analyses for females and males revealed that obesity was significantly associated with hypertension in females but not in males. On the contrary, cholesterolaemia was significantly associated with hypertension in males but not in females. We found a high prevalence of hypertension and multiple risk factors for non-communicable diseases (NCDs) in outpatients seeking care in Hargeisa. Our findings emphasise the need for enhanced focus on the prevention and management of NCDs in Somaliland.

Carbon dioxide adsorbents from flame-made diesel soot nanoparticles.

Carbon dioxide (CO2) is the top contributor to global warming. On the other, soot particles formed during fuel combustion and released into the atmosphere are harmful and also contribute to global warming. It would therefore be highly advantageous to capture soot and make use of it as a feedstock to synthesize carbon-based materials for applications such as carbon dioxide adsorption. In this work, flame-made diesel soot nanoparticles were used to produce a variety of activated carbons by combined oxidative treatment with hydrogen peroxide (H2O2) and potassium hydroxide (KOH), and their performance towards CO2 adsorption was evaluated. The effect of the chemical activation of soot with H2O2 for different reaction times and with KOH on the physicochemical properties of the activated carbons was investigated and compared to fresh soot. Interestingly, hollow aggregates of carbonaceous nanoparticles of a high interplanar distance, reduced polycyclic aromatic hydrocarbons (PAH) size, shorter PAH stacks, mesoporous structure, and a high content of oxygen functionalities along with other structural defects in PAHs were obtained in the synthesized activated carbons. Among the various analysis techniques employed, Raman spectroscopy indicated that the ID/IG ratio in soot decreased after simultaneous chemical treatment, though it did not indicate any enhancement in the graphitic character since the carbonyl and carboxylic containing PAHs and monovacancies (which cause defects in PAHs) also contribute to the increase in the intensity of the graphitic band. The activated carbons possessed promising CO2 adsorption capacities, adsorption kinetics and CO2/N2 selectivity. For example, one of the activated carbons, following H2O2 treatment for 9 h and a subsequent KOH activation, exhibited a CO2 adsorption capacity of 1.78 mmol/g at 1 bar and 25 °C, representing an increase of 161 % in capacity as compared to fresh soot. Hollow aggregates of carbonaceous nanoparticles consisting of shorter PAHs with a larger number of defects led to enhanced CO2 adsorption rate and CO2/N2 selectivity on activated carbons.

Implementation of two multiphase flow methods in modeling wetting of microporous hydrophobic membranes.

Pore wetting phenomenon plays a critical role in a porous media and is critical in various processes. For instance, liquid entry pressure (LEP) is one of the critical characteristics of hydrophobic membranes used in membrane distillation (MD) processes. In this study, pore-scale models were developed to assess the accuracy of two multiphase flow computational fluid dynamics (CFD) methods, as modeling tools for predicting two-phase flow in microporous MD membranes. Finite element method (FEM)-based phase field (PF) method (which was applied in the COMSOL package) and finite volume method (FVM)-based volume of fluid (VOF) method (which was applied in Star-CCM+) were the selected CFD tools for the implementation. The boundary conditions of the models were first set based on the experimental procedure for measuring the LEP, as given in the literature. Then, the models were used to capture the LEP under the gradually increased water pressure. Critical tuning of CFD parameters of each tool (such as mesh size, mesh type, and interface thickness) was conducted to investigate their influence on the LEP prediction accuracy and the water/air interface representation at the pore entrance. CFD model results were presented and compared with both experimental LEP data and the calculated value using the Young-Laplace equation (YLE). Both CFD tools were capable of capturing the water/air interface. LEP result from the VOF model showed good agreement with the experimental data, but the PF model overestimated the LEP value closer to the theoretical YLE value. For both approaches, the adjustment of the interface thickness was critical. In the VOF method, a realistic interface thickness could be achieved by adjusting both mesh size and time step simultaneously. In contrast, PF simulations were less mesh sensitive. The accuracy of the VOF model was better due to its mass conservation condition at the interface.

Variable refrigerant flow cooling assessment in humid environment using different refrigerants.

Variable Refrigerant Flow (VRF) is a cooling system developed to anticipate and minimize operating and maintenance costs. VRF allows personalized control and maximizes flexibility to accommodate changing tenants in high rise and compound buildings in hot and humid environments. Although many studies have previously modeled VRF systems from an energy perspective, minor attempts have been made to analyze the exergy performance of this technology. The aim of this paper is to present an exergy/energy analysis of VRF technology to address the effect of refrigerant flow as well as the cooling-air flow rates on the electric energy saving in the hot and humid zones. This analysis will be then used to investigate its performance in humid areas, particularly the Gulf region. VRF is an advanced air conditioning system that is developed to manage load variability by controlling the compressor speed and the expansion valve opening. It is proposed that the system be implemented at Masdar City buildings, located in Abu Dhabi. In this study, VRF units from different manufacturers were modeled and compared using engineering equation solver (EES) and IPSEpro software. The models, which were mainly developed on EES were repeated for validation on similar models that have been developed using the IPSEpro software, and the results were in agreement within 6% uncertainty. Parametric studies were done after modeling the system on EES, where both the high and low pressures in the cycle were varied to obtain the corresponding COP and second law efficiency operating range. It was noticeable that COP and second law efficiency are significantly affected by the evaporator and condenser temperatures and pressures. In addition, as significant concern has been raised due to the impact of refrigerants on global warming, different refrigerants were considered and the results showed that refrigerant R-410a would be the second most efficient refrigerant, after ammonia, for such systems. Finally, an effectiveness NTU evaporator model was implemented to minimize the overall power consumption of the VRF system under various zone loads. It was found that, under a typical set of zone loads, the optimal refrigerant evaporating temperature is 11 °C, when the sum of indoor fan power and outdoor unit power is minimized using the exergy balance. These results helped decision makers to install the VRF system for the first time in that hot and humid area. The preliminary results for May and June sowed an average energy saving of 32% with variable evaporators and condenser speed and variable compressor frequency.

Incidence, genetics, and clinical phenotype of permanent neonatal diabetes mellitus in northwest Saudi Arabia.

BACKGROUND: Permanent neonatal diabetes mellitus (PNDM) in European population has an incidence of at least 1 in 260 000 live births and is most commonly due to mutations in KCNJ11 and ABCC8. However, data on this condition in other populations are limited. OBJECTIVE: To define the incidence, genetic aetiology, and clinical phenotype of PNDM in Al-Madinah region, northwest Saudi Arabia. METHODS: Patients with PNDM diagnosed between 2001 and 2010 were identified and clinically phenotyped. Sequencing of KCNJ11, ABCC8, and INS were performed initially on all subjects, and EIF2AK3, GLIS3, SLC2A2, SLC19A2, GCK, IPF1, and NEUROD1 genes were sequenced according to the clinical phenotype. RESULTS: In total, 17 patients from 11 consanguineous families were diagnosed with PNDM and the incidence was 1 in 21 196 live births. Six different mutations in four genes were identified, of which two GLIS3 and one SLC2A2 were novel and no patient had KCNJ11, ABCC8, or INS mutations. Fourteen (82.4%) patients had identifiable genetic aetiology and their PNDM was part of known autosomal-recessive syndromes including Wolcott Rallison (41.1%), neonatal diabetes and hypothyroidism (29.4%), Fanconi-Bickel (5.8%), and thiamine-responsive megaloblastic anaemia (5.8%). Two patients with isolated PNDM and one with intermediate developmental delay, epilepsy and neonatal diabetes had no identifiable cause. CONCLUSIONS: Al-Madinah region has the highest reported incidence of PNDM worldwide. In this region with high consanguinity, PNDM has different genetic aetiology and in the majority of cases presents as a part of rare familial autosomal-recessive syndrome rather than in isolation.

Generation and analysis of expressed sequence tags (ESTs) for marker development in yam (Dioscorea alata L.).

BACKGROUND: Anthracnose (Colletotrichum gloeosporioides) is a major limiting factor in the production of yam (Dioscorea spp.) worldwide. Availability of high quality sequence information is necessary for designing molecular markers associated with resistance. However, very limited sequence information pertaining to yam is available at public genome databases. Therefore, this collaborative project was developed for genetic improvement and germplasm characterization of yams using molecular markers. The current investigation is focused on studying gene expression, by large scale generation of ESTs, from one susceptible (TDa 95-0310) and two resistant yam genotypes (TDa 87-01091, TDa 95-0328) challenged with the fungus. Total RNA was isolated from young leaves of resistant and susceptible genotypes and cDNA libraries were sequenced using Roche 454 technology. RESULTS: A total of 44,757 EST sequences were generated from the cDNA libraries of the resistant and susceptible genotypes. Greater than 56% of ESTs were annotated using MapMan Mercator tool and Blast2GO search tools. Gene annotations were used to characterize the transcriptome in yam and also perform a differential gene expression analysis between the resistant and susceptible EST datasets. Mining for SSRs in the ESTs revealed 1702 unique sequences containing SSRs and 1705 SSR markers were designed using those sequences. CONCLUSION: We have developed a comprehensive annotated transcriptome data set in yam to enrich the EST information in public databases. cDNA libraries were constructed from anthracnose fungus challenged leaf tissues for transcriptome characterization, and differential gene expression analysis. Thus, it helped in identifying unique transcripts in each library for disease resistance. These EST resources provide the basis for future microarray development, marker validation, genetic linkage mapping and QTL analysis in Dioscorea species.

Mechanical ventilation in patients with Guillain-Barré syndrome.

BACKGROUND: Patients with Guillain-Barré syndrome are commonly exposed to prolonged mechanical ventilation. Specific data on ventilatory management of these patients have been limited. OBJECTIVE: To describe the practice of mechanical ventilation in patients with Guillain-Barré syndrome and evaluate risk factors for morbidity and mortality. METHODS: We describe a historical cohort of mechanically ventilated patients with Guillain-Barré syndrome in a tertiary-care center. We extracted database information on demographics, severity of illness, pulmonary function, and ventilatory management for the period 1976 to 1996. Primary outcomes were development of pulmonary complications, duration of ventilatory support, and mortality. RESULTS: Fifty-four patients met the inclusion criteria. After 1990, lower tidal volume (p = 0.031) and higher positive end-expiratory pressure (p = 0.003) were used than during the 1976 to 1990. Outcomes did not change significantly during the studied period. Forty-six patients (85%) survived to hospital discharge, and 39 (72%) were alive at 1-year follow-up. Ventilator-associated pneumonia was the most frequent complication (56%) and was associated with prolonged mechanical ventilation (p < 0.01). Atelectasis developed in 49%, and acute lung injury in 13%. All but 6 patients (89%) received tracheostomy. In 14 patients (30%) tracheostomy was placed > or = 14 days after intubation. When adjusted for atelectasis and severity of illness in a stepwise logistic regression analysis, delayed tracheostomy was associated with the development of ventilator-associated pneumonia (odds ratio 8.2, p = 0.029). CONCLUSIONS: Changes in ventilator practice did not affect outcomes of mechanically ventilated patients with Guillain-Barré syndrome. The majority of patients received tracheostomy, which should be considered early in the course of respiratory failure.