bluuebunny/crossref_metadata_2025 huggingface dataset:
English Reading Proficiency and Academic Performance Among Lower Primary School Children in Ghana
Authors: Nyarko Kingsley , Kugbey Nuworza , Kofi Collins Courage , Cole Yaa Adubea , Adentwi Kobina Impraim
Published: August 2018

There have been several issues about the reading skills and abilities of children in Ghana, and how reading proficiency might influence the academic performance of children. In view of the above, this study examined the influence of reading proficiency on the academic performance of lower primary school children in Accra. Using a cross-sectional survey design, 383 participants (Grades 1-3) were sampled in Accra. The children were administered questionnaires that measured their English reading proficiency, paternal involvement, maternal involvement, financial situation, and demographic characteristics as well as their academic performance. Results showed that reading proficiency was significantly and positively related with children’s performance on all standard performance tests after controlling for paternal involvement, maternal involvement, financial situation, and age. Type of school significantly affected academic performance, however, no gender differences were observed in the children’s academic performance. The implications for educational practice and research are espoused.
Physical Activity and Psychological Well-Being in Older University Office Workers: Survey Findings
Authors: Qi Meiling , Moyle Wendy , Jones Cindy , Weeks Benjamin
Published: August 2018

Prolonged sitting time has been reported among university workers which can have adverse health effects. The aim of this study was to examine the sitting time, physical activity, and psychological well-being reported by older university office workers. An online self-reported survey was distributed to all office workers 55 years and older at one university in Australia. Sixty-six office workers were recruited. They reported an average sitting time of 7.5 hours per day on weekdays. In all, 72.7% of the sample reported both moderate and high physical activity levels. A high percentage of the office workers reported depression (25.8%) and anxiety (12.1%). Lower education levels were significantly related to higher perceived stress and more depressive symptomatology ( p = .03 and .02, respectively). Significant associations were found between stress, depression, and anxiety ( p < .001) among this group of workers.
Thirty-Day Perioperative Complications, Prolonged Length of Stay, and Readmission Following Elective Posterior Lumbar Fusion Associated With Poor Nutritional Status
Authors: Phan Kevin , Ranson William , White Samuel J. W. , Cheung Zoe B. , Kim Jun , Shin John I. , Ukogu Chierika , Lee Nathan J. , Kothari Parth , Cho Samuel K.
Published: August 2018

Study Design:

Retrospective study.

Objective:

To determine the rates of early postoperative mortality and morbidity in adults with hypoalbuminemia undergoing elective posterior lumbar fusion (PLF).

Methods:

The American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) was examined from 2005 to 2012. Current Procedural Terminology (CPT) codes were used to query the database for adults (≥18 years) who underwent PLF and/or posterior/transforaminal lumbar interbody fusion (PLIF/TLIF). Patients were divided into those with normal albumin concentration (≥3.5g/dL) and those with hypoalbuminemia (<3.5 g/dL). Both univariate and multivariate analyses were performed.

Results:

A total of 2410 patients were included, of whom 2251 (93.4%) were normoalbuminemic and 159 (6.6%) were hypoalbuminemic. Patients with preoperative serum albumin levels <3.5 g/dL were older with a higher American Society of Anesthesiologists (ASA) score, and more comorbidities, including anemia, diabetes, dependent functional status, and preoperative history of chronic steroid therapy. Hypoalbuminemic patients had higher rates of any 30-day perioperative complication ( P < .001), unplanned readmission ( P = .019), and prolonged length of stay (LOS) >5 days ( P < .001). However, hypoalbuminemia was not significantly associated with any specific perioperative complication. On multivariate analysis, preoperative hypoalbuminemia was found to be an independent predictor of prolonged LOS (OR 2.4, 95% CI 1.7-3.5; P < .001) and unplanned readmission (OR 2.7, 95% CI 1.1-6.3; P = .023).

Conclusion:

Hypoalbuminemia was found to be an important predictor of patient outcomes in this population. This study suggests that clinicians should consider nutritional screening and optimization as part of the preoperative risk assessment algorithm.

Level of Evidence:

III
A Case of Delayed-Onset Posthypoxic Leukoencephalopathy in a Pediatric Patient
Authors: Smolinsky Kristen , Sediva Ivona
Published: August 2018

We present a 16-year-old female status post traumatic brain injury from severe motor vehicle crash with prolonged extrication. Initially with a Glasgow Coma Scale of 4 and blood pressure of 80/40, she required emergent intubation. Head computed tomography was notable for skull fracture with hematoma, diffuse axonal injury, and 6-mm midline shift with right uncal herniation. On hospital day 1, she underwent decompressive R hemicraniectomy. She received neuroprotective treatment including a hypocarbic, hypernatremic state with close blood pressure monitoring for appropriate cerebral perfusion. On hospital day 4, patient was extubated and weaned off pressors and hypertonic saline. On hospital day 6, she was able to get out of bed to a chair, was speaking some words, following commands, and tolerating bites of food. On hospital day 8, she developed sudden agitation, combativeness, confusion, and could no longer follow commands. Magnetic resonance imaging now demonstrated confluent restricted diffusion consistent with acute changes. Imaging and examination findings were consistent with delayed-onset posthypoxic leukoencephalopathy.
Imaging high-resolution velocity and attenuation structures from walkaway vertical seismic profile data in a carbonate reservoir using visco-acoustic waveform inversion
Authors: Takam Takougang Eric M. , Bouzidi Youcef
Published: August 2018

Frequency domain visco-acoustic waveform inversion is applied to multi-offsets vertical seismic profile data acquired over a carbonates reservoir in an oil field offshore Abu Dhabi in the United Arab Emirates, to produce high resolution seismic velocity and attenuation structures. The starting velocity and attenuation models are obtained from traveltime tomography, and from the centroid frequency-shift method, respectively. Waveform tomography is performed between the frequencies 4 and 50 Hz. To reduce coupling between velocity and attenuation parameters during model updates, a two stage inversion strategy is adopted. During the first stage, only the velocity model is recovered and, during the second stage, velocity and attenuation models are recovered. The density is estimated from empirical correlation derived from sonic and density logs at the borehole location. A judicious selection of the time-damping constant [Formula: see text], used to suppress late arrivals in the Laplace-Fourier domain is critical to mitigate nonlinearities. Prior to the inversion, data preconditioning is done to transform the data in a form convenient for the visco-acoustic wave equation. High resolution final velocity and attenuation models are obtained. Extracted 1D profiles from the final models generally correlate well with the sonic log and estimated clay content from the gamma-ray log. These observations give confidence to the results. A comparison of the synthetic data generated from the final models and the field data shows a high degree of similarity. The high resolution of the results enables us to readily identify layers and provide a geologic interpretation from Quaternary to Late Jurassic. The inverted models show a stack of layers with alternating relatively high and low velocity values associated with relatively high- and low-attenuation values defining anticlines, as we progressed deeper into the subsurface. The two main reservoirs units in the Lower Cretaceous are clearly identified.
Depression, memory and electroconvulsive therapy
Authors: Coetzer Rudi
Published: August 2018

Current neuroscience suggests that although short-term memory difficulties frequently occur immediately after electroconvulsive therapy (ECT), longer-term problems are less common. However, gaps in our knowledge remain regarding longer-term cognitive problems after ECT, including memory function. Some of these relate to the complexities surrounding cognitive testing and interpretation of test results. An important question in clinical decision-making is why, despite current evidence suggesting long-term memory problems are less frequent, some patients still report subjective memory difficulties. To further advance clinical practice and the neuroscience surrounding post-ECT cognitive function, assessment of cognitive function, possibly including neuropsychological testing, should potentially become more routine as part of clinical practice.

Declaration of interest

None
Does Exercise Alter Gut Microbial Composition? A Systematic Review
Authors: MITCHELL CASSIE M. , DAVY BRENDA M. , HULVER MATTHEW W. , NEILSON ANDREW P. , BENNETT BRIAN J. , DAVY KEVIN P.
Published: August 2018

Purpose

The objective of this systematic review of literature was to evaluate and summarize published research that has investigated the association between exercise and gut microbial composition in mammals.

Methods

This review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The databases searched for this review included: PubMed; PubMed Central; Medline; Cumulative Index of Nursing and Allied Health Literature; Web of Science; Commonwealth Agricultural Bureaux Direct; Health Source: Nursing Academic Edition; Clinicaltrials.gov; International Prospective Register of Systematic Reviews (PROSPERO); and the Cochrane Library.

Results

Twenty-five articles met the inclusion criteria: 17 rodent, one canine, two equine, and five human studies. All studies in rodents and equines included control groups; whereas only one study in humans included a control group. The remaining were cross-sectional or cohort studies. All studies in rodents controlled for dietary intake and one study in humans implemented a 3-d dietary control. Eleven studies assessed voluntary exercise and 13 studies used forced exercise. Diversification within the Firmicutes phylum was consistently observed in exercise groups across studies. There were no consistent trends within Bacteroidetes, Actinobacteria, or Proteobacteria phyla. In general, the potential interactions between exercise and diet composition and their respective influences on the intestinal microbiome were not well characterized.

Conclusions

Exercise was associated with changes in gut microbial composition, an increase in butyrate producing bacteria and an increase in fecal butyrate concentrations independent of diet in rodents and humans. The overall quality of evidence in the studies in humans was low and the risk of bias was unclear. Future studies with standardized reporting and rigorous dietary control in larger samples are needed to further determine the influence of exercise on gut microbial composition.
Brain-derived Neurotrophic Factor Pathway after Downhill and Uphill Training in Rats
Authors: PEDARD MARTIN , CEFIS MARINA , ENNEQUIN GAËL , QUIRIÉ AURORE , GARNIER PHILIPPE , PRIGENT-TESSIER ANNE , PERNET NICOLAS , MARIE CHRISTINE
Published: August 2018

Introduction

The elevation of brain-derived neurotrophic factor (BDNF) levels in the brain and the subsequent phosphorylation of its cognate tropomyosin-related kinase B (TrkB) receptors at tyrosine 816 (pTrkBtyr816) are largely involved in the positive effect of aerobic exercise on brain functioning. Although BDNF levels were reported to increase in proportion with exercise intensity, the effect of the type of contraction is unknown. Therefore, the cerebral BDNF/TrkB pathway was investigated after uphill and downhill treadmill activities at equivalent intensity to preferentially induce eccentric and concentric contractions, respectively.

Methods

A treadmill activity (30 min·d−1 for seven consecutive days) either in a horizontal position at two different speeds to modulate intensity (experiment 1) or at three different inclinations (null, −10%, and +5%) but at equivalent intensity to modulate the type of contraction (experiment 2) was induced in rats. Both experiments included sedentary rats. Levels of BDNF, pTrkBtyr816, synaptophysin (marker of synaptogenesis), endothelial nitric oxide synthase phosphorylated at serine 1177 (peNOSser1177), and c-fos levels (indicators of elevation in blood flow in the cerebrovasculature and neuronal activity, respectively) were measured in motor- and cognition-related brain regions using Western blotting analysis.

Results

Experiment 1 indicated that treadmill activity induces an intensity-dependent increase in peNOSser1177, c-fos, and BDNF levels. Experiment 2 showed that intensity of exercise as well as activation of the cerebral BDNF pathway, and synaptogenesis did not differ among horizontal, uphill, and downhill treadmill activities.

Conclusion

The cerebral response of the BDNF pathway to a treadmill activity is dependent on exercise intensity, but not on the type of contraction (eccentric vs concentric).
Phylogeny and biogeography of the hyper–diverse genus Eugenia (Myrtaceae: Myrteae), with emphasis on E. sect. Umbellatae, the most unmanageable clade
Authors: Fernanda Mazine Fiorella , Quintino Faria Jair Eustaquio , Giaretta Augusto , Vasconcelos Thais , Forest Félix , Lucas Eve
Published: August 2018

Eugenia, comprising ca. 1100 species, is the largest genus of Neotropical Myrtaceae. Eugenia sect. Umbellatae (formerly referred to as “clade 9”) is the most speciose lineage of Eugenia. This study aims to better delimit E. sect. Umbellatae, to identify and understand relationships between manageable subgroups of this large clade for future discrete systematic studies and to explain biogeographical patterns in the genus. In total, 103 samples were used in this study. These include representatives of the nine clades of the “Eugenia group” with a particular focus on Eugenia clade 9, representing the morphological and geographical diversity found in the genus. Phylogenetic reconstructions were performed using maximum likelihood (ML) and Bayesian inference (BI) for the combined dataset, using the markers ITS, rpl16, psbA–trnH, rpl32–trnL, trnQ–rps16. The resultant tree was fossil calibrated and used for historical biogeographical analysis using DEC implemented in RASP. The mid Oligocene is the most likely period in which the crown node of Eugenia s.l. diversified. The earliest Eugenia appear to be associated with dry biomes and to have arisen from non–tropical southern South America, as did ancestors of the earliest American Myrteae. Eugenia subg. Pseudeugenia also most likely diversified in dry biomes, while E. subg. Hexachlamys and E. subg. Eugenia are likely to have diverged in the Atlantic Forests biome. Eugenia sect. Umbellatae is morphologically very variable; some clades can be circumscribed based on morphology while some remain morphologically undiagnosable. The study presented here provides discussion of the earliest origins of Eugenia and its response to climate–driven changes in the Neotropics as humid, forest biomes became more widespread in the Miocene. In addition, important practical conclusions are drawn regarding relationships within Eugenia. Three clades are newly classified as subgenera: E. subg. Pseudeugenia (including species of E. sect. Pseudeugenia); E. subg. Hexachlamys (including E. sect. Hexachlamys) and E. subg. Eugenia (including E. sect. Umbellatae,E. sect. Jossinia,E. sect. Phyllocalyx,E. sect. Pilothecium,E. sect. Racemosae,E. sect. Schizocalomyrtus, E. sect. Speciosae and Eugenia sect. Excelsae). Two previously unidentified clades are published as E. sect. Excelsae and recognized as E. sect. Jossinia, the latter consisting entirely of Old World species.
Changes of Complex Carbohydrates of White Jack Bean (Canavalia Ensiformis) During Autoclaving-Cooling Cycles
Authors: Rahmawati Atina , Murdiati Agnes , Marsono Yustinus , Anggrahini Sri
Published: August 2018

The extraction of white jack bean (Canavalia ensiformis) protein isolate frequently leaves a lot of precipitates containing complex carbohydrates such as starch, dietary fiber, and resistant starch. Repeated autoclaving – cooling cycles can increase the content of soluble fiber and resistant starch. The aim of this study was to determine changes of dietary fiber and resistant starch content of complex carbohydrates of white jack bean during autoclaving-cooling cycles and characterization of its chemical composition and functional properties. The experiment was conducted by applying the autoclaving process at 121oC for 15 minutes followed by cooling at 4oC for 24 hours up to 5 times. Sample was taken from each cycle of autoclaving – cooling. The best treatment was the sample with the highest total soluble fiber and resistant starch content. The best sample will be determined its chemical composition and functional properties. This study used a one-way analysis of variance to subject the data according to Completely Randomized Design. Duncan’s Multiple Range Test was applied to determine significant differences among 5 treatment means at the 5% significance level. The highest value of total soluble fiber and resistant starch content was obtained from autoclaving-cooling cycles of 3 times. The treatment increased the soluble fiber and resistant starch by 14.37% and 18.34%, respectively, but decreased 14.41% insoluble fiber. The complex carbohydrates of white jack bean treated with autoclaving-cooling cycles of 3 times had chemical composition: 10.68% moisture content, 0.92% ash content, 0.02% fat content, 1.85% protein content, 97.20% carbohydrate content (by difference), 68.42% starch content, and 14.90 ppm HCN. It also had functional properties: 351.67% WHC, 115.67% OHC, 775.33% SC, 84.63 meq/kg CEC. The conclusion was the white jack bean carbohydrate complex treated with 3 times autoclaving-cooling cycles was the best treatment to produce the highest value of total soluble fiber and resistant starch content. We suggest to examine another autoclaving temperature and cooling time to compare the result.
Prevalence and Associated Factors of Hypertension among Adults in Rural Uttarakhand: A Community Based Cross Sectional Study
Authors: Thapliyal Vinita , Singh Karuna , Joshi Anil
Published: August 2018

India is in a state of transition epidemiological, economic, and demographic and nutrition transition. And all these transitions are leading to non communicable diseases like obesity, hypertension and insulin resistance. The study was aimed to estimate the Prevalence of hypertension and its associated risk factors among adults of rural Uttrakhand. It is a cross sectional community based study. Survey was conducted in rural areas of Uttrakhand, to make a sample size of 300 adults (18-45yr), using WHO STEPS questionnaire. Waist Circumference, Blood pressure, Body Mass Index of the participants was calculated. P value < 0.05 was considered significant. In the sample population based on systolic BP, 61.3% were non-hypertensive, 29.7% were pre-hypertensive and 9% were hypertensive. Based on diastolic BP, 43.3% were non-hypertensive, 32.7% were pre-hypertensive and 24% were hypertensive. Subjects with hypertension and pre-hypertension have higher BMI and waist circumference. A high prevalence rate of pre-hypertension and hypertension was depicted in rural areas of Uttrakhand region.4.8% of the female participants had systolic high blood pressure compared to the 11.9% of the male participants. On the other hand, 21.8% of the female participants had diastolic high blood pressure compared to the over 25% of the male participants.
Profiling of Microbial Content and Growth in Fermented Maize Based Products from Western Kenya
Authors: Mwizerwa Herve , Ooko Abong George , Kuria Mbugua Samuel , Wandayi Okoth Michael , Gacheru Patrick , Muiru Maina , Obura Brenda , Viljoen Bennie
Published: August 2018

In most parts of Africa, the process of fermentation is not controlled and does not adhere to good manufacturing practices, therefore spoilage and pathogenic microorganisms can alter the quality of the end product and may cause foodborne illness.Traditional fermented products are mostly processed in an environment which creates a selection of microorganisms that produce the desired end product. In an attempt to find Lactobacilli which have probiotic properties and can be used in the development of starter culture for controlled fermentation of cereal products, the microbial populations of maize flour, overnight soaked dough, fermented cooked porridge, Mkarango and Busaawere enumerated and the inherent lactobacilli isolated. The microbial and biochemical profiles of the 6 days spontaneous Mkarangofermentation process were determined.The total viable count was 6.93 log cfu/g for fermented cooked porridge, 7.70 log cfu/g in Mkarango and 8.58 log cfu/g forBusaa. Lactobacillicounts were higher in maize flour with 7.43 log cfu/g whileEnterobactericeae were lower in Mkarango.The highest moulds and yeasts counts were observed forBusaa, 7.25 log cfu/g.The lactobacilli isolates from fermented maize based products from western Kenya were predominantly Lactobacillus fermentum andLactobacillus Plantarum.During fermentation time, Lactobacilliincreased from 6.62 to 12.46 log cfu/gafter 3 daysof fermentation. From day 4, an increase in moulds and yeast count was observed, varying from 8.42 to 10.53 log cfu/g. Enterobactericeae count decreased from 5.99 log cfu/g on day 1 to less than 1 log cfu/g on day 6.Titratable acidity increased from 0.32% to 0.73% on day 5. Inversely, the pH of Mkarangodecreased sharply from 6.64 to 3.64 on day 5 and slightly increased on the last day of fermentation. The microbial status of finished fermented maize based products is predominated by Lactobacilli and their isolates are predominantly Lactobacilli especially Lactobacillus fermentum andLactobacillus Plantarumthough further molecular tests are needed to confirm the species.
Phytochemical Investigation and Antioxidant Activity of Leaf Extract of Withania somnifera from Konso, South Ethiopia
Authors: Tebeka Simur Tesfaye
Published: August 2018

Withania somnifera is endemic to Ethiopia where its leaf and root is traditionally used for the treatment of malaria in south Ethiopia. The main purpose of this study was to investigate phytochemicals and antioxidant activity of the leaf extract of Withania somnifera. The anti-oxidant potential and total antioxidant potential was determined by using reducing power determination method and phosphomolb date method respectively. As per the phytochemical tests, the methanol extract revealed that presence of tannins, phenolics, flavonoids, saponins and, alkaloids while all are absent in hexane extract. The antioxidant capacity of methanol, acetone and hexane leaf extracts of Withania somnifera were found to be 494.088±0.230, 104.190±0.020 and 3.413±0.023 mg of ascorbic acid per 10 mg of dry weight of antioxidant in the reducing power, respectively and it’s total antioxidant capacity of these extracts were 45.41±0.018, 8.70±0.004 and 0.38±0.002mg of ascorbic acid per 10 mg of dry weight of the crude extract. Thus, the results of the present investigation infer that this plant extracts possess potent antioxidant. Therefore it is strongly recommended to isolate the antioxidant components.
Anticancer Activity of Graphene Oxide/5-FU on CT26 dsRED Adenocarcinoma Cell Line
Authors: Afarideh Behrooz , Rajabibazl Masoumeh , Omidi Meisam , Yaghmaee Bahram , Rahimpour Azam , Khodabakhshi Reza , Sarvarian Saeeideh
Published: August 2018

Cancer is one of the greatest health challenges in the world. Every year, many people die because of cancer. Chemotherapy is one of the treatment options in cancer disease. Fluorouracil )5-FU( is one of the chemotherapy dr0075gs, but it has relatively low toxic effect on tumor cells when it is used on free form, which also results in its poor efficacy. GO (graphene oxide) has a single-atomic layer and has several functional groups such as epoxide, carbonyl, carboxyl and hydroxyl which makes it a suitable carrier for drug loading. In the present study, we loaded 5-FU on GO nanocarrier to produce GO/5-FU, and characterized it by FT-IR. CT26 Ds-Red adenocarcinoma cell line was treated with GO/5-FU, free 5-FU, GO, and PBS (Phosphate buffer saline). The results showed significant inhibition of the CT26 Ds-Red cells using GO/5-FU compared to free 5-FU (P<0.05). Therefore, loaded 5-FU on GO (GO/5-FU) could be a new approach for optimization of 5-FU tumor cytotoxicity.
Excess Molar Quantities of Binary Mixture of Dipropyl amine with Aliphatic Alcohols at 298.15 K
Authors: A. H. Al-Dulaimy Zainab , T. A. Al-Heetimi Dhafir , Saleem Khalaf Husam , Mohammed Abbas Ahmed
Published: August 2018

Refractive indices (nD), viscosities (η) and densities (ρ) were deliberated for the binary mixtures created by dipropyl amine with 1-octanol, 1-heptanol, 1-hexanol, 1-pentanol and tert-pentyl alcohol at temperature 298.15 K over the perfect installation extent. The function of Redlich-Kister were used to calculate and renovated of the refractive index deviations (∆nD), viscosity deviations (ηE), excess molar Gibbs free energy (∆G*E) and excess molar volumes (VmE) The standard errors and coefficients were respected by this function. The values of ∆nD, ηE, VmE and ∆G*E were plotted against mole fraction of dipropyl amine. In all cases the obtained ηE, ∆G*E, VmE and ∆nD values were negative at 298.15K. Effect of carbon atoms number in the chain of alcohol and hydroxyl groups' position on molecular interactions in these mixtures has also been discussed.
Estimation of Preptin in Serum of Thyroid dysfunction Patients and its Relationship with other Parameters
Authors: A. Alubaidi Tamara , U. Mohammd Taghreed , N. ALkarawi Isam
Published: August 2018

The research includes a clinical study of Preptin with other parameters. The normal value of preptin in hypothyroidism (2638.4 ± 280.0 ) in female while (2960.4 ± 256.6) in male, in hyperthyroidism ( 589.0 ± 90.1 ) in male, while in female (993.2 ± 103.9), diabetes (2465.6 ± 282.4 ) in female, in male (2085.5 ± 282.8), in diabetes & hypothyroidism (3314.3 ± 177.3) in male, (3179.4 ± 265.7) in female, but control group in female (427.8 ± 60.4), in male ( 384.7 ± 62.4) at age (20-45) years they were divided into five groups: group one (G1) consisted of 30 hypothyroidism. The two group (G2) consisted of 30 patients with hyperthyroidism. And three group (G3) consisted of 30 healthy group, four group (G4) consisted of 30 patient with diabetes, and five group (G5) consisted of 30 patient with diabetes & hypothyroidism. The result show BMI where the results showed higher females compared with male in all groups, and a rise in the TSH in hypothyroidism and diabetes & hypothyroidism compared with other group, while shown low result in hyperthyroidism compared with other groups. But calcium, vitamin D3, FSH, and LH were non- significant because of people with osteoporosis and heart disease were excluded as did women with multiple polycystic ovaries. The aim of this study is to estimate the efficacy of preptin hormone for thyroid patients with diabetes.
Synthesis Gas Production by Methane Partial Oxidation on Ni/Fe3O4-Ce0.75Zr0.25O2 Catalysts: Kinetic Study
Authors: Vazquez M. I. Sosa , Gutierrez J. Salinas , Vigil D. Delgado , Collins-Martinez V. , Ortiz A. Lopez
Published: August 2018

Fe3O4-Ce0.75Zr0.25O2 (FeCZ) is an oxygen carrier material aimed to produce syngas through methane partial oxidation in absence of oxygen gas feed. The objective of the present research is to study the catalytic effect of Ni on FeCZ using an evaluation of the global kinetics (activation energy, reaction rate, order and constant) of its reaction with methane for syngas production. FeCZ and 0.05NiFeCZ (Ni/Fe = 0.05 molar ratio) were synthesized through co-precipitation of their precursor nitrate salts, while 2NiFeCZ was prepared by impregnation of FeCZ with a nickel nitrate solution to obtain a 2 %W Ni material. Samples were calcined at 950°C during 4 hours in air. Kinetic study of oxygen carriers (FeCZ, 0.05NiFeCZ and 2NiFeCZ) reduction with methane was followed through thermogravimetric analysis (TGA) at 5, 7.5 and 10% CH4/Ar and 600, 650 and 700°C. Initial reaction rate was obtained from the slope of the linear region of the weight change signal as a function of time. Results indicate a first order global reaction rate for all materials. Activation energies for samples FeCZ, 0.05NiFeCZ and 2NiFeCZ were 52.2, 39.5 and 28.3 Kcal/mol, respectively. Thus, reflecting the catalytic effect of Ni over the FeCZ global reaction rate.
Synthesis of Size-controllable LiFePO4/C Cathode Material by Controlled Crystallization
Authors: Yang G. , Jiang C.Y. , He X.M. , Ying J.R. , Gao J. , Wan C.R.
Published: August 2018

The preparation of LiFePO4/C materials with particle size ranging from 10 π m to 100-200nm was attempted by controlled crystallization-carbothermal reaction, which has been experienced as an effective process for mass production of electrode materials. The structure, morphology and electrochemical performance of different materials were carefully characterized. With the decrease of particle size for LiFePO4 powders, the LiFePO4/C composite exhibit better capacity performance at high current density. This paves an effective way to synthesize size-controllable LiFePO4/C materials by mass production.
Graphene-Polythiophene Nanocomposite as Novel Supercapacitor Electrode Material
Authors: Alvi Farah , Basnayaka Punya A. , Ram Manoj K. , Gomez Humberto , Stefanako Elias , Goswami Yogi , Kumar Ashok
Published: August 2018

The graphene (G)-polythiophene (PTh) nanocomposite was synthesized by a chemical oxidative polymerization technique and characterized using Field Emission Scanning Electron Microscopy (FESEM), High-Resolution Transmission Electron Microscopy (HRTEM), Raman Spectroscopy, Fourier transform Infrared spectroscopy (FTIR), X-ray-diffraction (XRD), Electrochemical Impedance spectroscopy(EIS) and cyclic voltammetry (CV) techniques. The electrochemical properties of G-PTh nanocomposite supercapacitor electrodes were investigated in different electrolytes solutions and a specific discharge capacitance of 154 F/g was estimated from different charge/discharge current cycles. Our proposed research is transformative as the G-conducting polymer based electrode material with unique and excellent properties, such as, high conductivity, wider tunable potential window, high stability of the electrode material in doped form, faster charge transfer rate, and short charging times, that allows the fabrication of high performance supercapacitors for practical applications.
Effect of WOx Over Ni/Hydrotalcite Catalysts to Produce Hydrogen from Ethanol
Authors: Contreras J.L. , Ortiz M.A. , Fuentes G.A. , Ortega M. , Luna R. , Gordon M. , Salmones J. , Zeifert B. , Nuño L. , Vázquez T.
Published: August 2018

The effect of WOx over Ni-hydrotalcite catalysts to produce H2 by ethanol steam reforming was studied. The catalysts were characterized by N2 physisorption (BET area), X-ray diffraction, Infrared and UV-vis spectroscopies. The W concentration ranged from 0.5 to 3 wt%. As W concentration increased, the intensity of XRD reflections of the Ni catalysts decreased. The porous structure of the materials consisted of parallel layers with a monomodal mesoporous distribution. The surface groups detected by IR were: -OH, Al-OH, Mg-OH, W=O and CO32-. UV-vis results suggested that Ni2+ ions were substituted by W ions. The catalytic evaluations were made in a fixed bed reactor using a water/ethanol mol ratio of 4 at 450°C. Catalysts with low loadings of W (0.5 and 1%) showed the highest H2 production and stability. W promoted the conversion of ethanol towards hydrogen in the case of the Ni-hydrotalcite catalysts. The reaction products were; H2, CO2, CH3CHO, CH4 and C2H4. The catalysts did not produce CO.
Combined Hydrogen Generation from Al/NiCl2 Powder and Alkaline NaBH4 Solution for Portable Fuel Cell
Authors: An Yan Ling , Li Chao , Tang Bin Hong , Xiao Xia , Zhang Tian Zhe , Xing Hu Wei , Tang Lei , Fan Mei Qiang
Published: August 2018

Hydrolysis of Al and NaBH4 for hydrogen generation has obtained considerable attention as a portable hydrogen source system. In this paper, we report a new combined hydrogen generation from Al powder and alkaline NaBH4 solution activated by NiCl2 additive. The system is characterized as the followed features: the interaction of Al/NaBH4 hydrolysis, catalytic effect of Ni2B for Al and NaBH4, Al hydrolysis stimulated by NaOH solution. The effects which affect the hydrogen generation performance of the system were studied. The results showed that a favorable combination of high hydrogen yield and high hydrogen generation rate might be obtained via the optimized composition design. Therefore, the system may be developed as a portable hydrogen source system.
Influence of Preparation Conditions on the Properties of Lithium Titanate Fabricated by a Solid-state Method
Authors: Zhang Guo-Qing , Li Wenjuan , Yang Hongwei , Wang Yahui , Rapole Sowjanya B. , Cao Yanli , Zheng Chunbao , Ding Keqiang , Guo Zhanhu
Published: August 2018

Lithium titanate (Li4Ti5O12) was prepared by a quasi solid-state method using water and ethanol as the solvents, in which Li2CO3 and TiO2 were used as the starting materials. In this work, the calcination temperature, molar ratio of Li to Ti, and sintering time were all well investigated. The obtained samples were thoroughly characterized by XRD and SEM, revealing that the above three factors not only affected the crystal structure, but also the morphologies of the resultant samples. Galvanostatic charge discharge curves were also employed to evaluate the electrochemical performance of the samples. The best electrochemical performance of the samples was observed when the molar ratio of Li to Ti, sintering temperature and time are 6:5, 850 oC and 12 hours, respectively. It was revealed that the smaller particle size and the higher crystallinity of the resultant samples were favorable to enhance the electrochemical performance.
Structural Modification, Strengthening Mechanism and Electrochemical Assessment of the Enhanced Conditioned AA6063-type Al-Mg-Si Alloy
Authors: Fayomi O. S.I. , Gbenebor O. P. , Abdulwahab M. , Bolu C. A. , Popoola A. P.I.
Published: August 2018

Enhancement of engineering materials is essential for averting service failure and corrosion attack in the industries. The impact of Ni as inoculant and solidification process on the corrosion resistance of an Al-Mg-Si alloy has been investigated in 3.65% NaCl solution using potentiodynamic polarization measurement. The alloying compositions and phase change were determined with energy dispersive spectroscopy (EDX) and x-ray diffraction (XRD). The surface morphology of the alloyed sample using scanning electron microscope (SEM) showed that Ni particles were well dispatched along the interface. The addition of Ni to Al-Mg-Si alloy led to the precipitation and crystallization of Al2Ni and AlNi2 formed at the grain boundaries. Equally, as the percentage of Ni content increases in the alloy, the corrosion rate decreased due to the presence of Al2Ni3 which proceeded at active regions. Inoculation of Ni particles coupled with increase in solidification reduces the possibility of corrosion penetration within the structural interface.
Preparation and Proton Conductivity of a Novel Polymer Composite Membrane PVDF- CsAl(SO4)2·12H2O
Authors: Wang X.D. , Shen H.Y. , Yang L.B. , Ning W.S. , Guo B. , Huang Y.X. , Maekawa H. , Shu K.Y.
Published: August 2018

A novel polymer composite membrane PVDF-CsAl(SO4)2·12H2O with high conductivity within a wide temperature range (30-140 °C) is synthesized by composing PVDF and conductors CsAl(SO4)2·12H2O. A sharp increase of the conductivity has been observed at around 90 °C, which was due to the release of the crystal water in the CsAl(SO4)2·12H2O. The highest conductivity of 0.45×103 S·cm-1 was obtained at 140°C , The novel polymer composite membrane PVDF-CsAl(SO4)2·12H2O described here can be an attractive candidate as electrolyte in the low and medium fuel cell.
Facile Synthesis of Donut-like TiO2-SnO2 Nanocomposite Microspheres by a Two-step Hydrothermal Reaction and Subsequent Spray Drying Process and Its Electrochemical Lithium Storage Properties
Authors: Tian Mengyao , Lv Chunju , Xu Jie , Guo Bing , Chen Da , Shu Kangying
Published: August 2018

Donut-like TiO2-SnO2 nanocomposite microspheres were successfully synthesized via a facile two-step hydrothermal reaction and subsequent spray drying. The protonated titanate nanowires with H2Ti3O7 phase in the nanocomposite precursor transformed into not anatase TiO2 but TiO2(B) crystal structure even after calcination at 400 ?. And the substitutional solid solution (Sn, Ti)O2 with the same tetragonal rutile structure as SnO2 was formed. Moreover, the hierarchical donut-like structure in TiO2-SnO2 nanocomposite microspheres constructed by the second-step hydrothermal and spray drying treatment was maintained after calcination at 400 ?. The electrochemical test showed that the as-obtained TiO2-SnO2 nanocomposite microspheres reached an initial discharge capacity of 640 m Ah g-1 at a current density of 40 mA.g-1, which is much higher than the theoretical capacity of TiO2(B).
Effect of Carbon Pososity on the Electrochemical Properties of Carbon/Polyaniline Supercapacitor Electrodes
Authors: Torre M. A. , Del Río C. , Morales E.
Published: August 2018

Supercapacitors have attracted great attention in power source applications, due to their high power density, elevated charge/discharge rate, good reversibility and long life. Activated carbons are the most frequently used electrode material, due to their high accessibility, non-toxicity, high chemical stability, good electrical conductivity, high surface area and low cost, but in practice the capacitance values are limited by the material microstructure. In this work we report on the synthesis and electrochemical characterization of carbon/polyaniline composites, synthesized by in-situ polymerization in acid media of aniline monomer on the surface of two activated carbons having different textural properties, and on the effect of the carbon porosity on the electrochemical properties of the electrodes. Results obtained indicate that the BET specific surface of the composites decreases sharply due to the collapse of the porous structure (mainly the micropores) of the carbon by the polyaniline chains. Regarding capacitance values, Csp increases on increasing polyaniline loading in the composite, however high polymer concentration lead to a decrease on capacitance when high current were applied, probably due to diffusion restrictions of the electrolyte anions and cations to the carbon surface.
Microwave Assisted Synthesis of Ru3Pd6Pt Cathode Catalyst in a PEM Fuel Cell
Authors: Leyva-Noyola F. , Solorza-Feria O.
Published: August 2018

Nanoparticles of Ru3Pd6Pt have been previously produced by different synthesis routes that involve high temperatures and relative high pressures and long time. The usage of a conventional microwave assisted synthesis reduces environmental risk impact as well as the cost effective production in large scale with minimum set up modifications. These features are the motivations for the use of microwaves in the synthesis of the Ru3Pd6Pt catalyst for PEM fuel cell applications to reduce the Pt loading. In this communication a tri-metallic electrocatalyst was produced by the reduction of the corresponding metallic salts, RuCl3, PdCl2, and H2PtCl6 in ethylene glycol using a modified conventional microwave device. Oxygen reduction reaction kinetic analysis results conducted to a Tafel slope, (-b = 41.2 ± 1.7 mV dec-1) at low overpotential, and exchange current density (i0 = 3.01 ± 0.39 × 10-5 mA cm-2) in 0.5M H2SO4. This electrocatalyst exhibited good performance and stability in a single H2/O2PEM fuel cell.
Synthesis of MgMnSiO4 and Its Application as Cathode Material for Magnesium Battery
Authors: Sun Jianzhi , Jiang Zhen
Published: August 2018

Orthosilicate MgMnSiO4 was prepared by sol-gel route and a subsequent heating procedure as a cathode material for rechargeable magnesium batteries. XRD patterns showed that MgMnSiO4 has a orthorhombic system with space group Pbnm(62). MgMnSiO4 presents good electrochemical behaviors at 10 mAg-1 discharge current density with specific capacity 130.1 mAhg-1 after 20 cycles. The results show that MgMnSiO4 could be a potential cathode material for high-energy magnesium secondary battery.
Synthesis of Nanoporous TiO2 Thin Films for Photocatalytic Degradation of Methylene Blue
Authors: Estrada M. , Reza C. , Salmones J. , Wang J.A. , Manríquez M. E. , Mora J. M. , Hernández M. L. , Zúñiga A. , Contreras J. L.
Published: August 2018

This work reports a structure and photocatalytic activity of nanoporous titania (TiO2) thin films by an anodizing approach. Xray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM) studies showed that tetragonal anatase was the main phase in the thin films that consisted of countless disordered nanopores in the order of 10 to 15 nm. In the photocatalytic degradation of methylene blue, the titania thin films showed a good photocatalytic activity. 82.2 % methylene blue could be photodegraded by titania thin films with UV radiation. XPS results indicate that during the degradation of methylene blue, some Ti3+ may be partially oxidized to Ti4+ in the TiO2 films and the surface hydroxyls directly participate in the reaction. Our nanoporous titania thin films is commensurable to Degussa-25 TiO2 powders because the latter requires filtration in each treatment; it is also much superior to the direct photolysis approach with respect to photoactivity.
Fabrication of Carbon Graphite-supported Pt–SiW12O40 Catalysts Effect of the Pt Loading on the Electrooxidation of Cyclohexane
Authors: Saleh M. S.A. , Aouissi A. , Al-Suhybani A. A. , Al-Mayouf A. M.
Published: August 2018

H4SiW12O40 (abbreviated as SiW) and Pt supported on carbon graphite (CG) with different Pt/SiW ratios were prepared and characterized by FTIR, XRD, ICP-OES, polarography, and TEM. The prepared catalysts were then after successfully attached onto glassy carbon electrodes by using polyvinylidene difluoride (PVDF) as binder. The resulting electrocatalysts were characterized by cyclic voltammetry (CV) and tested for the electrooxidation of cyclohexane. It has been found that the addition of SiW to the catalyst increased the dispersion of the Pt particles. The results of the electrocatalytic tests showed that cyclohexanone, cyclohexanol, and cyclohexyl hydroperoxide are formed as major products of the reaction. Higher Pt loadings promoted cyclohexanone production.
Effects of Palladium Doping on the Structure and Electrochemical Properties of LiFePO4/C Prepared using the Sol-gel Method
Authors: Talebi-Esfandarani M. , Savadogo O.
Published: August 2018

LiFePO4/C, LiFe0.98Pd0.02PO4/C, and LiFe0.96Pd0.04PO4/C composite cathode materials were synthesized using the sol-gel method. The effect of palladium on the structure and electrochemical properties of LiFePO4/C have been investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), surface area measurement (BET), charge/discharge testing, and cyclic voltammetry (CV). The results indicate that palladium doping facilitates the formation of impurities, like Li3PO4. Also, the lattice parameters of the LiFePO4 structure decrease in size as the palladium content increases. In addition, the particles become larger and agglomerated by palladium incorporation. The electrochemical results show that palladium doping decreases the electrochemical performance of LiFePO4/C, owing to shrinking lattice parameters and the difficulty of achieving the diffusion of lithium ions into the structure during the intercalation/de-intercalation process. These results suggest that palladium doping by sol-gel method changes significantly the LiFePO4 structure which may impact it performances as cathode for the lithium ion battery applications.
Potential Applications of Phase-change Materials (PCM) in Building Energy Efficiency
Authors: Li Yancang , Sang Guanglei , Shi Huawang
Published: August 2018

Phase-change material with high thermal capacity savings density is of great importance in building energy conservation, waste heat recovery, peak load shifting and other fields. We aim to guide the researchers of these problems and provide an underlying basis for the development of this new energy-saving material. We extensively reviewed the development history, classification, research methods and existing problems of the phase change materials system and discussed some potential research topics for the future. This study can promote the related research of the Phase-change materials.
In-Situ Preparation of Si@C Composite Anode Materials for Lithium Ion Batteries
Authors: Cui Qingwei , Cao Jiang , Fang Mou , Li Jianjun , Lian Fang , Wang Li , He Xiangming
Published: August 2018

A Si@C nanocomposite material is prepared via in-situ polymerization of acrylonitrile on the surface of silicon nanoparticles,and followed by carbonization in an inert atmosphere. The obtained Si@C nanocomposite material is composed of a nanosized Si core anda casting carbon shell. Its structure and electrochemical properties are characterized by XRD, TG, Raman, SEM, TEM and chargedischargeperformance test. The results obtained in this study show that Si@C nanocomposite is coated by a layer of amorphous carbonwhich provides a conductive matrix and relieves the dramatically morphological changes of Si upon lithium insertion and extraction. Thecomposite exhibits good capacity retention for use as anode in lithium-ion batteries. This study also paves a facile and industrial scalableway to prepare core/shell structure for high performance anode materials for lithium-ion batteries.
Low Resistance, Carbon Black-free Magnetite Anode for Li-ion Batteries Obtained by One-step Attachment of Carbon Nanotubes
Authors: Półrolniczak P. , Surendran A. Arunthathy , Walkowiak M. , Thomas S. , Stephan A. M.
Published: August 2018

The paper describes a simple, one-step synthetic route for the fabrication of nanometric iron (III) oxide attached to multiwalled carbon nanotubes (MWCNT). TEM images show that magnetite nanoparticles with primary particle sizes of ca. 10 nm are preferentially located on the outer walls of carbon nanotubes. The obtained nanocomposites have been examined on reversible electrochemical insertion of lithium cations in a Li-ion cell. The presence of MWCNT brings about a substantial increase of the magnetite reversible capacities in the absence of any additional carbonaceous conductivity enhancing agent. With increasing MWCNT content in the material, reversible capacity consistently rises from 207 mAhg-1 for pure iron (III) oxide up to 763 mAhg-1 for the composite with 40 % of MWCNT. Cyclic voltammetry measurements reveal the expected large hysteresis between the reduction and oxidation peaks associated with Li+ insertion/deinsertion into magnetite crystal lattice. The reductive current peak maxima steadily rise with increasing MWCNT content from 0.15 A g-1 for pure iron (III) oxide up to 0.4 A g-1 for the composite with 40 % of MWCNT which confirms faster kinetics of electrochemical processes. EIS measurements directly proved the internal resistance decrease connected with the incorporation of MWCNT.