6,463 research outputs found
Development of Microelectrode techniques for analytical and environmental applications
No full textAs a result of several unique advantages of microelectrodes, there has been a great deal of interest in their development for electrochemical measurements. The aim of this study was to develop microelectrode techniques for analytical and environment applications.It is well established that dilute aqueous solutions of acids show a wave for H+ ion reduction, this feature has since been employed analytically. By analogy, an oxidation wave would be expected from dilute solutions to bases. The voltammetric behaviour for the electrochemical oxidation of aqueous solutions containing strong bases was studied with microdisc electrodes and rotating disc electrode (RDE). A well-defined wave for OH- oxidation was obtained at the foot of the current increase due to O2 evolution. The limiting current of this wave was tested against OH- concentrations, the microdisc radius and RDE rotation speed. The characteristic features of the OH- oxidation wave, which include the wave split, the position and shape of the wave, were also examined as a function of the microdisc radius, RDE rotation speed and OH- concentrations. The results reported in this study provide the first experimental evidence for the diffusion-controlled electrochemical oxidation of OH- ions in aqueous solutions. The exact mechanism of the oxidation process occurs through a complex pathway which involves multiple electron transfer steps; the scanning electrochemical microscopy technique was used to investigate OH- ions oxidation by probing the release and consumption of the species that accompany the oxidation process.</p
Genetic variations of CYP2R1 (rs10741657) in Bangladeshi adults with low serum 25(OH)D level—A pilot study
No full textBackground Some studies revealed that despite having sufficient sun exposure and dietary supply, the level of serum 25(OH)D in Bangladeshi adults is lower than its normal range. Genetic pattern of an individual is also an essential factor that regulates the level of serum 25(OH)D. However, the genetic variations of CYP2R1 (rs10741657) and their association with low serum 25(OH)D level in Bangladeshi adults are yet to be explored. Objective This study was conducted to determine the frequency of variants of rs10741657 of CYP2R1 gene and its association with low serum 25(OH)D level among Bangladeshi adults. Method This pilot study was conducted among thirty individuals with low serum 25(OH)D level as the study population and ten subjects with sufficient serum 25(OH)D level as controls based on the inclusion and exclusion criteria. Genetic analysis of rs10741657 of CYP2R1 including primer designing, DNA extraction, PCR of target region with purification and Sanger sequencing of the PCR products were done accordingly. For statistical analysis, One-way ANOVA followed by LSD test, Freeman-Halton extension of Fisher’s exact test, Chi-square test (χ2) test and unpaired student t-test were performed. Results In this study, genetic variants of CYP2R1 (rs10741657) among the study population were genotype GG (63.30%), GA (30%) and AA (6.7%). Minor allele frequency of the study population was 0.217. The association between GG and GA genotypes of CYP2R1 (rs10741657) with low serum 25(OH)D level among the study population was found and it was statistically significant. Statistically significant differences were also observed between the genotypes and alleles of the study population and controls. Conclusions The presence of ‘GG’ and ‘GA’ genotypes of rs1041657 in CYP2R1 gene is associated with low serum 25(OH)D level among Bangladeshi adults in this pilot study
Genetic variations of CYP2R1 (rs10741657) in Bangladeshi adults with low serum 25(OH)D level—A pilot study
No full textBackground: Some studies revealed that despite having sufficient sun exposure and dietary supply, the level of serum 25(OH)D in Bangladeshi adults is lower than its normal range. Genetic pattern of an individual is also an essential factor that regulates the level of serum 25(OH)D. However, the genetic variations of CYP2R1 (rs10741657) and their association with low serum 25(OH)D level in Bangladeshi adults are yet to be explored.Objective: This study was conducted to determine the frequency of variants of rs10741657 of CYP2R1 gene and its association with low serum 25(OH)D level among Bangladeshi adults.Method: This pilot study was conducted among thirty individuals with low serum 25(OH)D level as the study population and ten subjects with sufficient serum 25(OH)D level as controls based on the inclusion and exclusion criteria. Genetic analysis of rs10741657 of CYP2R1 including primer designing, DNA extraction, PCR of target region with purification and Sanger sequencing of the PCR products were done accordingly. For statistical analysis, One-way ANOVA followed by LSD test, Freeman-Halton extension of Fisher's exact test, Chi-square test (χ2) test and unpaired student t-test were performed.Results: In this study, genetic variants of CYP2R1 (rs10741657) among the study population were genotype GG (63.30%), GA (30%) and AA (6.7%). Minor allele frequency of the study population was 0.217. The association between GG and GA genotypes of CYP2R1 (rs10741657) with low serum 25(OH)D level among the study population was found and it was statistically significant. Statistically significant differences were also observed between the genotypes and alleles of the study population and controls.Conclusions: The presence of 'GG' and 'GA' genotypes of rs1041657 in CYP2R1 gene is associated with low serum 25(OH)D level among Bangladeshi adults in this pilot study
Hierarchically porous 3D-printed akermanite scaffolds from silicones and engineered fillers
No full textThe present investigation is dedicated to the manufacturing of reticulated three-dimensional akermanite scaffolds, developed by direct reaction between silica, from the oxidation of a commercial silicone resin and oxide fillers, forming pastes for direct ink writing. Crack-free scaffolds, with dense and regular struts, were due to the use of CaCO3 (micro) and MgO nano-particles as reactive fillers. An excellent phase purity was obtained, with the help of the liquid phase provided by anhydrous sodium borate (Na2B4O7), upon firing. The structure of the scaffolds, finally, was successfully modified by using Mg(OH)2 and hydrated sodium borate: besides macro-porosity from direct ink writing, the new scaffolds exhibited homogenous ‘spongy’ struts (owing to water vapor release in the heating step), with no crack. Both types of scaffolds (with dense or porous struts) exhibited remarkable strength-to-density ratios
Thermodynamic and Transport Properties of H<sub>2</sub>/H<sub>2</sub>O/NaB(OH)<sub>4</sub> Mixtures Using the Delft Force Field (DFF/B(OH)<sub>4</sub><sup>-</sup>)
No full textSodium borohydride (NaBH4) has a high hydrogen (H2 ) gravimetric capacity of 10.7 wt %. NaBH4 releases H2 through a hydrolysis reaction in which aqueous NaB(OH)4 is formed as a byproduct. NaB(OH)4 strongly influences the thermophysical properties of aqueous solutions (i.e., densities, viscosities, and electrical conductivities) and the hydrolysis reaction kinetics and conversion of NaBH4. Here, molecular dynamics (MD) simulations are performed to compute viscosities, electrical conductivities, and self-diffusivities of H2 , Na+, and B(OH)4- for a temperature and concentration range of 298-353 K and 0-5 mol NaB(OH)4/kg water, respectively. Continuous fractional component Monte Carlo (CFCMC) simulations are used to compute the solubilities of H2 and activities of water in aqueous NaB(OH)4 solutions for the same temperature and concentration range. A new force field is developed (Delft force field of B(OH)4-: DFF/B(OH)4-) in which B(OH)4- is modeled as a tetrahedral structure with a scaled charge of −0.85. The OH group in B(OH)4- is modeled as a single interaction site. This force field is based on TIP4P/2005 water and the Madrid-2019 Na+ force field. The MD simulations can accurately capture the densities and viscosities within 2.5% deviation from available experimental data at 298 K up to a concentration of 5 mol NaB(OH)4/kg water. The computed electrical conductivities deviate by ca. 10% from experimental data at 298 K for the same concentration range. Based on the molecular simulations results, engineering equations are developed for shear viscosities, self-diffusivities of H2, Na+, and B(OH)4-, and solubilities of H2, which can be used to design and model NaBH4 hydrolysis reactors.Engineering ThermodynamicsComplex Fluid ProcessingTeam Poulumi De
Oh Holly, The Fish is Dead
No full textFrom Kurt Vonnegut to Stephen King, many novelists use metanarrative techniques to insert fictional versions of themselves in the stories they tell. The function of deploying such techniques is often to draw attention to the liminal space between the fictional constructs inherent in the novel as a form, and the real world from which the constructs draw inspiration, and indeed, are read by an audience. For emerging writers working in short form narratives, however, the structural demands of the short story or flash fiction make the use of similar techniques problematic in the level of depth to which they can be deployed.\ud
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‘Oh Holly, the fish is dead’ is the fourth in a series of short stories that work to overcome the structural limitations of a succinct form by developing a fractured fictional version of the author over a number of pieces and published across a range of sites. The accumulative affect is a richer metanarrative textual arrangement that also allows for the individual short stories to function independently
Continuous Hamiltonian dynamics and area-preserving homeomorphism group of D2
No full textThe main purpose of this paper is to propose a scheme of a proof of the nonsimpleness of the group {\rm Homeo}^\Omega(D^2,\del D^2) of area preserving homeomorphisms of the 2-disc . We first establish the existence of Alexander isotopy in the category of Hamiltonian homeomorphisms. This reduces the question of extendability of the well-known Calabi homomorphism \Cal: {\rm Diff}^\Omega(D^1,\del D^2) \to \R to a homomorphism \overline \Cal: {\rm Hameo(}D^2,\del D^2) \to \R to that of the vanishing of the basic phase function , a Floer theoretic graph selector constructed in \cite{oh:jdg}, that is associated to the graph of the topological Hamiltonian loop and its normalized Hamiltonian on that is obtained via the natural embedding . Here {\rm Hameo(}D^2,\del D^2) is the group of Hamiltonian homeomorphisms introduced by M\"uller and the author \cite{oh:hameo1}. We then provide an evidence of this vanishing conjecture by proving the conjecture for the special class of \emph{weakly graphical} topological Hamiltonian loops on via a study of the associated Hamiton-Jacobi equation.1111Ysciescopuskc
Asarum chungbuensis B. U. Oh. Since 2005
No full textAsarum chungbuensis (C.S. Yook & J.G. Kim) B.U. Oh (2005: 24) Basionym: Asiasarum sieboldii Miq. f. chungbuensis C.S. Yook & J.G. Kim (1996: 343) Type (neotype, designated here):— KOREA. Gyeonggi-do: Pocheon-si, Mt. Gwangdeoksan, 294 m, 38°04′51″N, 127°25′18″E, 27 April 2020, H. D.Jang & G. H. Nam 506 (KB! barcode NIBRVP774931)(Fig. 1). Notes: —Regarding the scientific name of this taxon, Yamaki (Feb. 1996) published the name of Asiasarum sieboldii (Miq.) F. Maek. var. versicolor (1996: 1), and Yook & Kim (Nov. 1996) published the name of Asiasarum sieboldii (Miq.) F. Maek. f. chungbuensis in the same year. Later, Lee & Lee (2000) republished it with a new combination name Asarum versicolor (Yamaki) Y.N. Lee (2000: 19). Oh et al. (2005) made a new combination name Asarum chungbuensis (C.S. Yook & J.G. Kim) B.U. Oh. Since then, A. versicolor (Yamaki) Y.N. Lee has been accepted as the legitimate name, having priority (Yamaji et al. 2007, So & Kim 2008, Oh 2008, National Institute of Biological Resources 2011). In contrast, A. chungbuensis (C.S. Yook & J.G. Kim) B.U. Oh has been treated as a superfluous name of A. versicolor. However, we detected problems regarding the scientific name A. versicolor (Yamaki) Y.N. Lee. Lee (2000) referred to the basionym as “ Asiasarum sieboldii Miq. var. versicolor Yamaki, J. Jap. Bot. 71: 1–10, 1995”; thus, the name has not been validly published because whole pages of the protologue have been cited. According to Article 41.5 of the ICN (Turland et al. 2018), a new combination name is not validly published unless its basionym is clearly indicated, and a full and direct reference is given to its author and place of valid publication, with page or plate reference and date on or after January 1, 1953. In addition, according to Article 11.2 of the ICN, although Asiasarum sieboldii var. versicolor Yamaki was published before A. sieboldii f. chungbuensis C.S. Yook & J.G. Kim, neither of these names have any priority outside the rank at which they were published. Consequently, A. versicolor (Yamaki) Y.N. Lee is unacceptable, and A. chungbuensis (C.S. Yook & J.G. Kim) B.U. Oh is accepted as the legitimate name of this taxon.Published as part of Jang, Hyun-Do, Nam, Gi-Heum, Oh, Hyun-Kyung & Leem, Hyosun, 2021, Typification of the names Asarum chungbuensis and A. maculatum (Aristolochiaceae), pp. 295-299 in Phytotaxa 508 (3) on page 298, DOI: 10.11646/phytotaxa.508.3.5, http://zenodo.org/record/542599
Serum 25-hydroxyvitamin D and cognitive decline in the very old: The Newcastle 85+ study
No full textBackground and purpose:
Studies investigating the association between 25-hydroxyvitamin D [25(OH)D] and cognition in the very old (85+) are lacking.
Methods:
Cross-sectional (baseline) and prospective data (up to 3 years follow-up) from 775 participants in the Newcastle 85+ Study were analysed for global (measured by the Standardized Mini-Mental State Examination) and attention-specific (measured by the attention battery of the Cognitive Drug Research test) cognitive performance in relation to season-specific 25(OH)D quartiles.
Results:
Those in the lowest and highest season-specific 25(OH)D quartiles had an increased risk of impaired prevalent (1.66, 95% confidence interval 1.06–2.60, P = 0.03; 1.62, 95% confidence interval 1.02–2.59, P = 0.04, respectively) but not incident global cognitive functioning or decline in functioning compared with those in the middle quartiles adjusted for sociodemographic, health and lifestyle confounders. Random effects models showed that participants belonging to the lowest and highest 25(OH)D quartiles, compared with those in the middle quartiles, had overall slower (log-transformed) attention reaction times for Choice Reaction Time (lowest, b = 0.023, P = 0.01; highest, b = 0.021, P = 0.02), Digit Vigilance Task (lowest, b = 0.009, P = 0.05; highest,b = 0.01, P = 0.02) and Power of Attention (lowest, b = 0.017, P = 0.02;highest, b = 0.022, P = 0.002) and greater Reaction Time Variability (lowest,b = 0.021, P = 0.02; highest, b = 0.02, P = 0.03). The increased risk of worse global cognition and attention amongst those in the highest quartile was not observed in non-users of vitamin D supplements/medication.
Conclusion:
Low and high season-specific 25(OH)D quartiles were associated with prevalent cognitive impairment and poorer overall performance in attention-specific tasks over 3 years in the very old, but not with global cognitive decline or incident impairment
Volume 10, Number 27
No full textThis is an 8-page weekly magazine for children in Catholic religious education. Pages 6-7 are given to "Gospel Activity." Six cartoon panels are filled with black-and-white line drawings. Pupils are urged to draw in the last two empty panels. The story is presented as "The Porcupine and the Moles" telling one of Aesop's fables. Porcupine asks the moles if he could share their cave for the winter, and the welcome him. After a week, the moles are suffering from the porcupine's needles. They decide to talk with the porcupine and ask him to leave. "Oh, no! This place suits me well." Pupils are asked to talk through with each other how the porcupine and moles can solve their problem. Five questions help. They are to write or draw their group's solution into the two empty panels. I would say that this is a good challenge. Mom wrote on a post-it note "I wish you could have heard the solutions my students gave to this problem."No Autho
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