Miracle-dz/UniFAR-FTUs huggingface dataset:
Highly sensitive adsorption stripping voltammetric method for determination of trace vanadium

Differential pulse adsorptive cathodic stripping voltammetric method for determination of trace Vanadium(V) has been developed. In the determination hydroxy naphthol blue was used as complexing agent. 0.2 mol L - 1 acetate buffer of pH 5.0 served as the supporting electrolyte. At the potential of-0.35 V a well-defined voltammetric peak was formed. Ligand concentration, accumulation time, drop size, scan rate, pulse amplitude, etc. have been optimised. Under optimum conditions detection limit was 0.1 μg L - 1 for V(V). The developed method was highly selective and sensitive, and has been applied to the determination of vanadium in water spiked with V(V), in effluents, and in standard alloy samples.
Galactochemistry. II: Interstellar deuterium chemistry

Le modele presente dans l'article precedent (ibid., 405-428) est etendu pour inclure la chimie du deuterium. Les resultats sont en bon accord avec les observations et avec un rapport D/H galactique de 0,7-1,5.10 -5 . On en deduit que l'univers est «ouvert»
Analytical models of polymer nucleation

In this thesis we investigate and develop analytic models for polymer nucleation and other barrier crossing problems. Our most broadly appealing method for certain multi dimensional barrier crossing problems is a one-dimensional projection which includes a novel technique to extract rate kinetics from simulations [M J Hamer et al., Soft Matter, 2012, 8, 11396-11408]. The scenarios we expect our method to be potentially useful are situations where barrier crossings are rare, and the dominant mechanism is through a series of unlikely incremental steps. The rate kinetics extraction technique is also reliant on the equilibrium energy barrier being relevant to non-equilibrium system, but is not appropriate when strong kinetic contributions dominate the process, and enable crossings over highly unfavourable energetic pathways. We explore and significantly enhance the Graham-Olmsted (GO) polymer nucleation simulation [R S Graham and P D Olmsted, Phys. Rev. Lett. , 2009, 103, 115702], producing a combinatorial calculation to obtain exact energy landscapes from it’s basic stochastic rules of monomer attachment [M J Hamer et al., J. Non-Newton. Fluid. , 2010, 165, 1294-1301]. We apply our rate kinetics extraction technique to the GO model and find that for most flow rates in purely long chain melts, nuclei tend to grow along similar paths over energy landscapes. The technique reveals a clear signature when this pattern is disobeyed, as in the case of blends of long and short chain polymer melts, some of which display highly anisotropic growth. In addition, we design several one-dimensional barrier crossing models with distinct characteristics, predicting the average and the distribution of crossing times with great accuracy. That finally enables us to completely describe the GO simulation’s nucleation rates with analytic theory, by presenting a model of polymer nucleation featuring crystal rotation, which vastly impacts nucleation rates when polymer melts are subject to flow.
The effect of mesoporous silica nanoparticle surface chemistry and concentration on the α-synuclein fibrillation

The aggregation of an amyloid protein, α-synuclein (α-Syn), has been suggested as a potential cause of Parkinson's and several other neurodegenerative diseases. To explore the possibility of using nanoparticle-based therapeutic agents for the treatment of such diseases, we investigated the influence of surface chemistry and concentration of mesoporous silica nanoparticles (MSNPs) on the fibrillation of recombinant human α-Syn protein in the present work. Bare MSNPs as well as MSNPs of different surface functionalities, including 3-(2-aminoethyl amino) propyltrimethoxysilane (AAS), succinic anhydride (carboxyl), and polyethyleneimine (PEI) were prepared and characterized by electron microscopy, zeta potential measurement, Brunauer–Emmett–Teller (BET) isotherms, and FT-IR analyses. The process of α-Syn fibril formation was monitored by Thioflavin T (ThT) assay, atomic force microscopy (AFM) and fluorescence microscopy imaging. The conformation of α-Syn molecules in fibrillar forms and upon adsorption onto MSNPs was investigated by circular dichroism (CD) analysis, and an MTT assay was employed to evaluate the cytotoxicity effects of α-Syn fibrils on a PC12 cell line in the absence and presence of MSNPs. The synthesized MSNPs were spherical and monodisperse with an average size of 83 ± 6 nm. Our results showed that the fibril formation is reduced considerably in the presence of positively-charged MSNPs, i.e. AAS- and PEI-MSNPs, and is enhanced while treated with negatively-charged MSNPs, i.e. bare and carboxyl-MSNPs. Furthermore, it was also demonstrated that increasing the concentration of the MSNPs regardless of their surface chemistry results in greater effects on the fibril formation—promoting or inhibiting for negatively and positively-charged MSNPs respectively. Subsequently, the cytotoxicity of the formed aggregates was noticed to be significantly reduced in the presence of AAS- and PEI-MSNPs in comparison to that in the absence of these MSNPs. These results suggest that the electrostatic charges and concentration of MSNPs play important regulatory roles in the fibrillation process of α-Syn. Thus, the present study contributes towards the better understanding and control of protein fibrillation by nanoparticles which can lead to development of nanoparticle-mediated therapies.
Synthesis and NMR Analysis of 1,4-Disubstituted 1,2,3-Triazoles Tethered to Pyridine, Pyrimidine, and Pyrazine Rings†

A combinatorial modular approach based on the “click” copper(I)-catalysed azide–alkyne cycloaddition reaction was used to prepare a library of selected 1,4-disubstituted 1,2,3-triazoles differently functionalized with heteroaryl groups including pyridine, pyrimidine, and pyrazine. Three different copper(I) sources, i.e., CuSO4/sodium ascorbate, CuBr(PPh3)3, and (CuOTf)2·C6H6 were used to promote the coupling reactions of a range of aryl, heteroaryl, and heteroarylmethyl azides with alkyne “click” partners. As the target heteroaryl triazoles were designed to serve as advanced ligands or ligand precursors for metal coordination, they were fully characterized by 1H, 13C, and 15N NMR spectroscopy. The resonances were assigned on the basis of 1D and 2D NMR experiments. 1H–15N gs-HMBC was used as a practical tool to determine 15N NMR chemical shifts at the natural abundance level of the 15N isotope.
Neuroprotection by Chitosan and Chitosan Nanoparticles

Chen, Bojun Ph.D., Purdue University, December 2013. Neuroprotection by Chitosan and Chitosan Nanoparticles. Major Professor: Richard B. Borgens. In the U.S., about 200,000 people are currently living with spinal cord injury (SCI). An estimated of 50%-70% of all SCI cases occurs in the range of ages between 15-35 years old. The destructive neurotrauma results in the majority of adult disability, even after patients suffering with SCI survived from the acute death. There are two stages involved in the progression of SCI, the primary stage and the secondary stage. The primary stage is mainly the mechanical damage to the central nervous system. The rapid collapse of the integrity of cell membrane and tissue is often one of the initial onsets. Centered by the cascade of biochemical disruption, such as aldehyde toxins, the secondary injury is responsible for the major clinical deficits in sensory and motor functions. Available pharmacological treatment for SCI includes high doses of steroids. However, the side effects of steroid therapy leave patients more susceptible for complications, such as infections, chronic pain and blood clots. The absence of “standard of care” have triggered waves of intense research leading to “finding a cure for SCI”. Based on our previous successful explorations of the neuroprotection by chitosan and chitosan nanoparticles (Chi-NPs) in SCI related cell and tissue studies, we further investigated the neuroprotective effects based on two major characteristics of chitosan: (1) molecular weight (MW) and (2) degree of acetylation (DA). Our results demonstrated that chitosan polymer blocked the random exchange of a probe, tetramethyl-rodamine (TMR) and an endogenous protein, lactate dehydrogenase (LDH), across mechanically compromised cell membrane, while a significant difference of the membrane “sealing” effect was not suggested among different MWs and DAs of chitosan polymer. A similar affinity
Electrodeposition of magnesium from CaCl2-NaCl-KCl-MgCl2 melts

Electrodeposition of magnesium from calcium chloride-based melts was studied on metallic (tungsten and molybdenum) and glassy carbon electrodes. Pure CaCl 2 melt and different alkali chloride solvents including binary CaCl 2 -NaCl, equimolar composition, and ternary CaCl 2 -NaCl-KCl melts with compositions 35:55:10 mol %, containing different MgCl 2 concentrations, were used. In the case of the binary mixture, the operating temperature was both above and below the melting point of metallic magnesium (923 K) so that solid and liquid deposits were obtained. Underpotential deposition of calcium is an important process in melts containing CaCl 2 due to formation of Ca-Mg alloys, which affects the magnesium electrodeposition process. Three-dimensional magnesium deposits that grow macroscopically on the studied substrates were found. This influences determination of the diffusion coefficient of Mg(II) ions. Formation of a magnesium monolayer on both electrodes, and especially on tungsten, was a stable process in the ternary mixture containing MgCl 2 , which was related to the presence of 10 mol % KCl. Moreover, in this melt a remarkable pseudopassivation process was found at high overpotentials.
Promoting the Usage of Ict in Clusters for Business Process Re-Engineering Within Sido Settings

There has been considerable interest and activities in clustering and the concomitant link to the regional development in recent times. The study wanted to help promoting of ICT usage in clusters for business process re-engineering within SIDO settings. This is due to challenges faced by SMEs clusters in performing business activities such as promoting their products outside their locality, using ICT in their businesses and gain other more benefits provided by the use of ICT technology. The study was conducted in Morogoro Municipal in Morogoro region with the main purpose of examining the extents to which SMEs clusters promote the usage of ICT within cluster environments. Precisely, the study sought to find out whether the use of ICT provides benefits and opportunities among the SMEs clusters, to assess the level of awareness on the usage of ICT in promoting business and its impact to the development of SMES clusters and to investigate the efficiency and effectiveness of the use of ICT tools to SMEs clusters in promoting business. About 88 SMEs dealing with clusters of (Metal work, Food processing, Clothes and Cereal flour) were involved in this study to understand the relationship between the use of ICT and business process re-engineering promotion among SMEs, the extent of SMEs clusters awareness of ICT usage in promoting their business and the extent of using it in business process re-engineering in improving the service and customer satisfaction. Statistical Package for Social Sciences (SPSS) version 20 was used to analyze the data collected.
A neutron diffraction and isotopic substitution measurement of the structure of liquid Cu2Se

The partial structure factors and pair distribution functions of liquid Cu2Se have been determined by neutron diffraction with isotopic substitution. The structure shows characteristics typical of those of an ionic 2:1 melt consisting of Cu+ and Se2- ions with the cations moving through a more ordered Se2- sub-structure. A detailed comparison has been made with recent results obtained for liquid Ag2Se. The structure is similar although there is no evidence of the double peak structure in the cation-cation partial structure factor, SCuCu(Q), as has been found in SAgAg(Q) for liquid Ag2Se and, to a more limited extent, for liquid Ag2Te. There is also less order in the Se2- sub-structure based on a comparison of SSeSe(Q) and the Bhatia-Thornton concentration-concentration structure factor, SCC(Q), for the two liquids.
Molecular mechanisms of kinetochore microtubule attachment

To ensure equal chromosome segregation during mitosis, the macromolecular kinetochore must remain attached to depolymerizing microtubules, which drive poleward chromosome movement. Microtubules are highly dynamic structures that undergo dramatic structural changes during depolymerization. The results presented in this thesis define essential functions of the Astrin-SKAP-LC8 and Skal complexes at the kinetochore-microtubule interface. First, we demonstrate that the Astrin-SKAP-LC8 complex localizes preferentially to kinetochores of bioriented sister chromatids. Localization of the Astrin-SKAP-LC8 complex to kinetochores is controlled by a key regulator of kinetochore-microtubule attachments, Aurora B kinase. The Astrin-SKAP-LC8 complex is essential for mitotic progression and directly associates with microtubules. Furthermore, the microtubule polymerization factor CLASP requires the Astrin-SKAP-LC8 complex to localize to kinetochores. Second, we demonstrate that the Skal complex has many of the biochemical and biophysical properties of a molecular machine that can couple microtubule depolymerization to chromosome movement. The Skal complex diffuses on and tracks with depolymerizing microtubules and its microtubule binding activity is necessary to maintain kinetochore-fibers and power chromosome oscillations during metaphase. Importantly, we demonstrate that the Skal complex directly interacts with the peeling protofilaments present at the depolymerizing microtubule end, suggesting a unique mechanism by which the Skal complex remains attached to depolymerizing microtubules. Finally, we demonstrate that the Skal microtubule-binding domain has two conserved basic regions that are required for microtubule binding and are subject to regulation by Aurora B kinase. In total, we define essential properties of the Astrin-SKAP-LC8 and Skal complex required for the formation of kinetochore microtubule attachments. Thesis Supervisor: lain M. Cheeseman, Associate Professor of Biology
Oblique impact of a smooth body on a thin layer of inviscid liquid

The two-dimensional motion of a rigid body with a smooth surface is studied during its oblique impact on a liquid layer. The problem is coupled: the three degrees of freedom of the moving body are determined together with the liquid flow and the hydrodynamic pressure along the wetted part of the body surface. The impact process is divided into two temporal stages. During the first stage, the wetted region expands at a high speed with jetting flows at both ends of the wetted region. In the second stage, the free surface of the liquid is allowed to separate from the body surface. The position of the separation point is determined with the help of the Brillouin–Villat condition. Calculations are performed for elliptic cylinders of different masses and with different orientations and speeds before the impact. The horizontal and vertical displacements of the body, as well as its angle of rotation and corresponding speeds are investigated. The model developed remains valid until the body either touches the bottom of the liquid or rebounds from the liquid.
Determination of dissimilatory sulfate reduction rates in marine sediment via radioactive 35S tracer

Rates of dissimilatory sulfate reduction in aquatic sediments have been measured over many years with 35S‐radiotracer, and the method has been continuously modified and optimized. This article discusses the sequence of procedures that constitutes the method from sediment handling before incubation, via incubation and distillation, to statistical analysis of the results. We test modifications that have been added since previous method descriptions, and we recommend sound experimental procedures. We discuss the measurement of extremely low sulfate reduction rates whereby only one count per minute labeled sulfide may be produced. We show by numerical modeling that the measured rates are mostly representative for a small volume around the point where 35SO42− is injected and that this can be used as an advantage to avoid edge effects. Finally, we show that oxidation will spoil samples during storage unless the samples are stored frozen. The main focus is on marine sediment, but the discussions are equally relevant for freshwater.
Explaining the Enhanced Performance of Pulsed Bioreactors by Mechanistic Modeling

In this work, steady-state mass balance based models were applied to two UASB reactors and three UAF for a better understanding of the role of pulsation on the efficacy improvement. Models were defined taking into account the hydraulic behavior of each digester and the limiting mechanism of the overall process kinetics (mass transfer or biochemical reaction rate). The application of the model allows to identify that mass transfer was the controlling step in all the reactors, except for the nonpulsed UASB, where methanogenic activity controlled the reactor performance in the last operation steady states. Mass transfer coefficients were higher for pulsed reactors and, in general, a good agreement between those estimated by an empirical correlation and from the model was obtained. Damkohler number values supported that the external mass transfer resistance was not negligible with respect to the process kinetic and in addition, in most cases, it controls the overall process in the reactors. The relative importance of external and internal mass transfer rate was calculated through the Biot number. The values of this dimensionless module indicated that external transport was the main contributor to overall mass transfer resistance. © 2008 American Institute of Chemical Engineers AIChE J, 2008
Menisci at a free liquid surface: surface tension from the maximum pull on a rod

The maximum force on a vertical rod supporting a stable meniscus, at equilibrium, formed at the free surface of a liquid, is shown to be a characteristic property of the system. This maximum force depends only on the rod radius, the density of the liquid, the gravitational acceleration and the surface tension.The maximum force represents the product of the maximum volume of liquid held above the general level, the gravitational acceleration and the density. The maximum volume of the meniscus has been derived theoretically as a function of rod radius in the form of a parametric equation with a table of coefficients. Thus from the measured rod radius and maximum force, the surface tension is derived.The surface tensions of water and of other liquids have been measured using this method and are found to agree very well with other methods given in the literature. However, this method is believed to be accurate to ±0.1 mN m–1, and it is an absolute method in that it requires no arbitrary end corrections involving a prior knowledge of the surface tension.It is important that the rod should be level and have a radius not so large that the angle of contact became a limitation on the maximum force measurable.The method does not involve detachment of the rod from the surface. It is an equilibrium method the position of which may be approached from both directions.
Effect of hydrogen plasma treatment on transparent conducting oxides

The effect of hydrogen plasma treatment on indium tin oxide (ITO), fluorine‐doped tin oxide (FTO), and indium‐doped zinc oxide (IZO) films has been studied. X‐ray photoelectron spectroscopy analysis shows that ITO and FTO surfaces get reduced to yield elemental indium and tin, respectively. Annealing of the plasma treated films in air leads to re‐oxidation of the reduced surface and the electro‐optical properties are recovered. In contrast, IZO films are not reduced by plasma treatment and show no changes in the electrical and optical properties. The surface of plasma treated IZO films shows a higher binding energy O(1s) peak probably due to OH or OH.O species which appear to form a protective layer against plasma degradation.
CFD simulation coupled with population balance equations for aerated stirred bioreactors

Mammalian cells have been widely used to produce therapeutic proteins in stirred bioreactors in suspension culture. Local hydrodynamics can have a great impact on cell proliferation and protein synthesis, but there are few reports on spatial heterogeneity of nutrients, gas bubbles, and mass transfer coefficients. We have employed computational fluid dynamics (CFD) coupled with population balance equations to study local hydrodynamics in a 20 L stirred bioreactor. The flow patterns, energy dissipation rates, gas volume fraction, gas bubble size distribution and local mass transfer coefficient have been displayed throughout the whole bioreactor. Their implications for mammalian cell culture have been discussed. This study provides an insight into rational design and optimum operation conditions in a stirred bioreactor for mammalian cell cultivation.
Characteristics and Application of Soybean Hull Fractions Obtained by Microparticulation/Air-Classification

Soybean hull was microparticulated at cut-off wheel speed of 9,000 rpm and air-classified into fine and coarse fraction at air classifying wheel speeds (ACWS) of 10.000, 15,000 and 20,000 rpm. respectively. Proximate analysis of the coarse and fine fractions of the microparticulated/air-classified soybean hull showed that ash, protein and lipid were enriched in the coarse fractions and carbohydrates in the fine fraction. Dietary fiber were enriched in coarse fractions and dietary fiber and dietary fiber content increased with decreasing ACWS. Mean particle size of fine fractions ranged from that of coarse fractions ranged from and both increased with decreasing ACWS. The particles were mostly oval-shaped regardless of the fractions. Generally the fraction of low ACWS showed higher viscosity. In water holding capacity, oil absorption and emulsion capacity, there was significant difference between coarse and fine fractions while there was no significant difference as a function of different ACWS. Oil absorption of flying batter was decreased significantly in the fraction of ACWS 15,000. when cakes and cooking were prepared partially substituted with soybean hull fraction, there was no significant changes on their physical and sensory properties up to 10% substitution.
Magnetic nanoparticles containing labeling reagents for cell surface mapping

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Crystal and liquid crystalline polymorphism in 1-alkyl-3-methylimidazolium tetrachloropalladate(II) salts

1-Alkyl-3-methylimidazolium tetrachloropalladate(II) salts ([Cn-mim]2[PdCl4], n = 10, 12, 14, 16, 18) containing a single, linear alkyl-chain substituent on the cation have been synthesised and their behaviour characterised by differential scanning calorimetry, polarising optical microscopy and small-angle X-ray scattering. The salts display thermotropic polymorphism, exhibiting both crystal–crystal transitions and, for n = 14–18, the formation of a thermotropic smectic liquid crystalline phase.