Miracle-dz/UniFAR-FTUs huggingface dataset:
INVESTIGATION OF SUPERCRITICAL FLUID EXTRACTION OF PUERARIN FROM PUERARIA LOBATA

Puerarin, which is the most abundant isoflavone in Pueraria lobata, has many pharmacological effects. In this study, supercritical carbon dioxide extraction was employed as a novel and efficient technique to extract puerarin from Pueraria lobata. Effects of four variables (pressure, temperature, time and co-solvent amount) on the puerarin yield of Pueraria lobata were investigated. Up to a certain value, the puerarin yield increased with increasing pressure; thereafter, puerarin yield decreased as pressure increased. A similar effect of temperature was also found. When the temperature was at 50C or the pressure was at 20 MPa, the highest puerarin yield obtained was 5.8 ± 0.3 mg/g. Positive effects of time and co-solvent amount were observed on the puerarin yield. However, when the time was longer than 100 min or the co-solvent amount was greater than 120 g, no significant improvement was detected in the puerarin yield. It was therefore important to define the level of each variable for an efficient preparation of puerarin. From the results obtained, supercritical carbon dioxide extraction was proved to be an efficient technique for extraction of puerarin from Pueraria lobata. PRACTICAL APPLICATIONS Pueraria lobata is a famous Chinese traditional medicinal herb which has been consumed by many people all over the world. Puerarin is the most abundant isoflavone in this herb, and it has been proven to have some important pharmacological properties. In this study, a novel technique called supercritical carbon dioxide extraction was employed to prepare puerarin from Pueraria lobata. Effects of pressure, temperature, time and co-solvent amount on the puerarin yield were evaluated. The results were helpful in understanding the extraction process of puerarin and could give evidence for further developments on this special medicinal herb.
Thermoluminescence (TL) of europium-doped ZrO2 obtained by sol–gel method

This article reports the preparation and characterization of europium-doped zirconium oxide (ZrO2:Eu3+) formed by homogeneous precipitation from propoxyde of zirconium [Zr(OC3H7)4]. The alkoxide sol gel process is an efficient method to prepare the zirconium oxide matrix by the hydrolysis of alkoxide precursors followed by condensation to yield a polymeric oxo-bridged ZrO2 network. All compounds were characterized by thermal analysis and the X-ray diffractometry method. The thermoluminescence (TL) emission properties of ZrO2:Eu3+ under beta radiation effects are studied. The europium-doped sintered zirconia powder presents a TL glow curve with two peaks (Tmax) centered at around 204 and around 292 °C, respectively. TL response of ZrO2:Eu3+ as a function of beta-absorbed dose was linear from 2 Gy up to 90 Gy. The europium ion (Eu3+)-doped ZrO2 was found to be more sensitive to beta radiation than undoped ZrO2 obtained by the same method and presented a little fading of the TL signal compared with undoped zirconium oxide.
Sheet Polymeric Iron (III) Porphyrin Complexes Catalytic Oxidation of Styrene with Molecular Oxygen

The sheet polymrtic iron (III) porphyrin complex [PFe (III)TPP] was prepared and charactrtized by FT-IR, TG-DTA and DTG, SEM and XPS. It was applied to catalytic oxidation of styrene with molecular oxygen and exhibited excellent catalytic activity. The results showed that the conversion reached to 50.5% in mild concitions, the major products of benzaldhyde (65.2% at 90°C) were obtained, and the catalyst could be efficiently reused five times.
A Solution Selection Model for Coaxial Electrospinning and Its Application to Nanostructured Hydrogen Storage Materials

Coaxial electrospinning was used to encapsulate the complex hydride ammonia borane in polystyrene to improve its properties as a hydrogen storage material. A solvent selection system was developed by using the Hansen solubility parameters to facilitate the choice of compatible solvents for core and shell. This enabled systematic optimization of the parameters needed for successful coelectrospinning. This approach has general application for any multiphase electrospinning system, including ones where the core is highly conducting or nonpolymeric. The resulting fiber morphologies depend strongly on the degree of miscibility of core and shell solutions. Fibers spun from immiscible core−shell solutions had a classic coaxial structure. Fibers produced from semimiscible core−shell solutions were highly porous, with inclusions extending through the fiber and an ordered radial and longitudinal distribution of nanoscale pores on the fiber surface. We suggest that this type of porosity may be due to an instability .
CuO/Graphene Nanohybrids: Preparation and Enhancement on Thermal Stability and Smoke Suppression of Polypropylene

Cu/graphene nanohybrids were successfully prepared using a simultaneous chemical reduction method. Successful oxidation of Cu nanoparticles was carried out by the melt blending during preparation of the nanocomposites. Cu nanoparticles were well dispersed on graphene with a diameter of 3–7 nm. XRD and TGA results revealed successful oxidation of Cu nanoparticles during processing. TEM results indicated that PP nanocomposites decorated with CuO/graphene were better dispersed than those added with graphene because the CuO acted as a spacer to keep graphene layers separated. The thermal property of the PP/G-Cu-1 and PP/G-Cu-2 was efficiently improved by around 30 °C compared with native PP. Moreover, the smoke suppression property of PP/graphene, PP/G-Cu-1, and PP/G-Cu-2 nanocomposites were also improved by 28.9%, 35.8%, and 47.2%, respectively. The main reasons for the improvements were due to two factors: the good mass barrier effect of graphene and being easily reduced or the catalytic charring effect of .
Gas Solubilities in Aqueous Solutions of Organic Substances

The solubilities of He, N2, O2, CH4, and CO2 in aqueous solutions of glycerol, acetic acid, glucose, sucrose, and lactose were measured at 303.2 K. Additional data were generated for CO2 at 293.2 K and 323.2 K. The present results and literature data were analyzed to develop an empirical model. The parameter set allows predictions for 15 gases and 63 organic substances at temperatures between 273 K and 343 K.
Ultrafine hydrogel fibers with dual temperature‐ and pH‐responsive swelling behaviors

Ultrafine hydrogel fibers that were responsive to both temperature and pH signals were prepared through the electrospinning of poly(N-isopropylacrylamide) (PNIPAAm) and poly(acrylic acid) mixtures in dimethylformamide. Both the diameters (700 nm to 1.2 μm) and packing of the fibers could be controlled through changes in the polymer compositions and PNIPAAm molecular weights. These fibers were rendered water-insoluble by the addition of either Na2HPO4 or poly(vinyl alcohol) (PVA) to the solution, followed by the heat curing of the fibers. The fibers crosslinked with Na2HPO4 swelled to 30–120 times in water; this was significantly higher than the swelling of those crosslinked with PVA. The PVA-crosslinked hydrogel fibers, however, exhibited faster swelling kinetics; that is, they reached equilibrium swelling in less than 5 min at 25 °C. They were also more stable after 1 week of water exposure; that is, they lost less mass and retained their fibrous form better. All the hydrogel fibers showed a drastic increase in the swelling between pH 4 and 5. The PVA-crosslinked hydrogel fibers exhibited distinct temperature-responsive phase-transition behavior of PNIPAAm, whereas the Na2HPO4-crosslinked hydrogel fibers showed altered two-stage phase transitions that reflected side-chain modification of PNIPAAm. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 6331–6339, 2004
Computer Simulation of Zeolites : Adsorption, Diffusion and Dealumination

Zeolites are microporous materials with pores that have about the same size as small molecules like water or benzene. They are important catalysts in the petrochemical industry, for example for catalytic cracking, and isomerization- and alkylation reactions. This thesis deals with molecular aspects of the application of zeolite catalysis for the production of cumene via benzene alkylation with propene using Mordenite (MOR-type zeolite). We will use classical force field based molecular simulations to study properties at the atomistic scale. In Chapter 1, an overview is given of the various properties of zeolites, as well as the simulation methods to study the adsorption and diffusion of guest molecules adsorbed in zeolites. In Chapter 2, it is shown that the adsorption and diffusion properties of alkanes in MOR strongly depend on the distribution of non-framework Al atoms. A model is presented to accurately describe this effect. A new method to efficiently compute the heat of adsorption for guest molecules adsorbed in zeolites with non-framework cations is presented in Chapter 3. It is found that this method is much more efficient than the existing methods. Furthermore, it is shown that for the simulation of polar molecules in zeolites, the Ewald summation is superior compared to the recently proposed Wolf-method. In Chapter 4, we study the adsorption selectivity of benzene/propene mixtures in various zeolites, and we evaluate their use as a potential catalysts for benzene alkylation. In Chapter 5, we propose an efficient method to accurately compute pore size distributions. This method is extensively used in Chapter 6, in which we study the dealumination mechanism of MOR-type zeolite using Kinetic Monte Carlo simulations. The results of these dealumination simulations are in very good agreement with various experiments. It is found that the pore size of the main channels is significantly increased. Finally, we propose several criteria for potential catalysts for the production of cumene from benzene and propene.
Nanocontainer‐Based Anticorrosive Coatings: Effect of the Container Size on the Self‐Healing Performance

Organic coatings based on inhibitor loaded inorganic containers for smart corrosion inhibition are presented. The overall coating performance is strongly influenced by the containers as well as their inhibitor capacity, compatibility with the coating matrix, and size. The important effect of container size is described for the first time in this work by investigating two types of mesoporous silica containers of different diameters: 80 and 700 nm. The coating physical properties (thickness and adhesion) are comparable for both container types. In contrast, the coating barrier properties are strongly influenced by the container size as assessed with electrochemical impedance spectroscopy (EIS). The incorporation of bigger containers reduces the coating resistance by a factor of two. Surprisingly, despite the similar amounts (20 wt%) of loaded inhibitor (2‐mercaptobenzothiazole), different active inhibition ability is detected with the scanning vibrating electrode technique (SVET). Therefore, it is found that coatings with smaller containers exhibit better self‐healing performance.
Nuclear magnetic resonance studies of 7Li ionic motion in alkali silicate and borate glasses

Nuclear magnetic resonance (NMR) studies of 7Li ionic motion in four lithium and lithium‐potassium silicate glasses of the R2O·4SiO2 and R2O·2SiO2 composition were made before and after heat treatment, and a newly developed equation was used for the analysis of the data. Other data from alkali borate glasses of the 3R2O·7B2O3 composition were reanalyzed using the equation, which eliminates the problem of a distribution of ionic relaxation times. It is shown how heterogeneities in the form of barriers to alkali ion motion in the glasses can be detected and studied by NMR. Although all glasses with higher alkali contents appear to be homogeneous, both the borates and silicates with lower alkali contents appear to be heterogeneous. These heterogeneities appear to be on a smaller scale in the borates than in the silicates. In addition to long‐range 7Li ionic motion observed in homogeneous glasses (and intermediate‐range motion in heterogeneous glasses), there is evidence of short‐range motion within severely .
Obtenção de biopolímeros de gelatina por radiação ionizante

The gelatin (GEL) is a biocompatible and biodegradable biopolymer, which naturally forms semi-solid colloids or hydrogels in aqueous solutions. As a hydrophilic polymer, the GEL has structural and physico-mechanical properties that distinguish it from synthetic hydrophilic polymers. The study of these properties led to the development of the present work. Thus, GEL-based films and hydrogels were developed using ionizing radiation technology by different techniques: irradiation with Co, electron beam (EB) and/or pulsed EB. The GEL based-films enriched with different additives, such as glycerol (GLY), polyvinyl alcohol (PVA), butylated hydroxytoluene (BHT), acrylamide and/or vegetal fiber, were irradiated with doses from 10 to 60 kGy, depending on the additive; some parameters like mechanical properties, color, and water absorption were analyzed. In the radio-induced synthesis of GEL nanohydrogels, polyethylene glycol (PEG) and the mixture (MIX) of additives, PEG and GEL, the size, molar mass and surface morphology of the nanohydrogels were analyzed. There was a significant increase of gel fraction with increase of the radiation dose for the GEL/fiber samples. The GEL based-films with 10% PVA irradiated at 20 kGy showed the highest puncture strength. The addition of antioxidant BHT affected on some GEL based-films properties on applied conditions. Regarding the nanohydrogels, there was a decrease of hydrodynamic radius of MIX irradiated with Co from 68 ± 25 nm (2 kGy) to 35 ± 4 nm (5 kGy). The radiation proved to be a convenient tool in the modification of polymeric materials for both, GEL films and hydrogels. Keys words: Gelatin, Co, electron beam, pulsed electron beam, biomaterials, nanohydrogels.
Magnetic separation of antibiotics by electrochemical magnetic seeding

Magnetic separation of several classes of antibiotics was investigated using electrochemical magnetic seeding. Electrocoagulation with a sacrificial anode followed by addition of magnetite particles was applied for the magnetic seeding of antibiotics. With electrochemical magnetic seeding using an iron anode, tetracycline antibiotics (oxytetracycline, chlortetracycline, doxycycline and tetracycline) and cephalosporin antibiotic (cefdinir) were rapidly removed from synthetic wastewater by magnetic separation using a neodymium magnet. Iron and aluminium anodes were suitable for magnetic seeding of the antibiotics. The results indicated that the ability of antibiotics to form strong complex with iron and aluminium allowed the higher removal by magnetic separation. This method would be appropriate for rapid treatment of antibiotics in wastewater.
Imprint lithography issues in the fabrication of high electron mobility transistors

In earlier work we described procedures for the fabrication of High Electron Mobility Transistors (HEMTs) using nanoimprint lithography to produce T-shaped resist profiles for gate metallization. For reliable liftoff the T-gate process requires a clear undercut in resist, and this is intrinsically impossible with imprint lithography. In addition, the imprinting process resulted in fracture defects in the resist unless release was carried out at elevated temperatures. Both these problems required improvement. In this article we describe an improved method for obtaining metallized imprinted T-gates by creating resist undercut using a double angled evaporation. HEMTs with self-aligned gate structures were fabricated using this procedure. Multilayer resist stacks were used to investigate resist flow during imprinting and we show that such stacks are not suitable for liftoff enhancement of T-gates. We further show how resist fracture defects can be minimized by increasing the pattern density on the die.
Arjunolic acid: A renewable template in supramolecular chemistry and nanoscience

Abstract Arjunolic acid, a triterpenoid, renewably resourced from Terminalia arjuna sawdust, has the potential of being used as a structural molecular framework in supramolecular chemistry and nanoscience. The nanosized chiral triterpenoid on derivatization could immobilize varieties of organic solvents at low concentrations. The low-molecular-mass organic compounds self-assembled in organic media to form fibrous network structures having fibers of nano- to micrometer diameters. A dual-component supramolecular gelation has been demonstrated, exhibiting interesting thermochromic property. An arjunolic acid-derived crown ether showed efficient binding to monovalent cations, including a primary ammonium ion paving the way for chiral recognition of amino acids.
Hydration of Na+, Ni2+, and Sm3+ in the Interlayer of Hectorite: A Quasielastic Neutron Scattering Study

Quasielastic neutron scattering experiments were performed with Na−hectorite, Ni−hectorite, and Sm−hectorite samples in order to find out whether Sm3+ is present in the clay interlayer as a fully hydrated cation (outer-sphere complex), or, as it follows from neutron diffraction data analysis, it is dehydrated and bound to the clay surface (inner-sphere complex). The results obtained for the Sm−hectorite were compared with other interlayer cations: strongly hydrated Ni2+ and relatively weakly hydrated Na+. It was found that water mobility in the Sm−hectorite sample is very close to the water mobility in Ni−hectorite. This is only possible if the Sm3+ ion is fully hydrated. It was shown that water molecules hydrating Ni2+ and Sm3+ exhibit diffusion mobility measurable with backscattering spectrometers. The diffusion coefficients of the exchangeable cations were found using the slow exchange approximations DNi = (0.05 − 0.14) × 10−9 m2/s and DSm = (0.04 − 0.18) × 10−9 m2/s.
Applications of carbon nanotubes to electrochemical DNA sensors: a new strategy to make direct and selective hybridization detection from SWNTs

In this paper, we first review different strategies reported in the literature to elaborate electrochemical DNA sensors based on carbon nanotubes. Then we report a new strategy to graft both redox and DNA probes onto carbon nanotubes to make a label-free DNA sensor. Oxidized single-walled carbon nanotubes are first immobilized on a self-assembled monolayer of cysteamine. Then a redox probe, a quinone derivative 3-[(2-aminoethyl) sulfanyl-5-hydroxy-1,4-naphthoquinone], is grafted onto the free carboxylic groups of the nanotubes. After that, for DNA probe grafting, new carboxylic sites are generated via an aryl diazonium route. After hybridization with a complementary sequence, the conformational changes of DNA could influence the redox kinetics of quinone, leading to a current increase in the redox signal, detected by square wave voltammetry. The system is selective, as it can distinguish a single mismatched sequence from the complementary one.
Bewertung und iterative Verbesserung von rigoros‐empirischen Hybridmodellen

Die modellbasierte Optimierung ist ein wichtiges Werkzeug zur Steigerung der Wirtschaftlichkeit, Sicherheit und ökologischen Verträglichkeit eines verfahrenstechnischen Prozesses. Die Modellierung ist jedoch aufwändig, wenn in dem Prozess komplizierte und teilweise unverstandene physikalische Phänomene ablaufen. Als illustrierendes Beispiel betrachten wir den in Abb. 1 skizzierten Prozess zur Herstellung von Ethylenglykol (EG) aus Ethylenoxid (EO) und Wasser (H2O). Die Edukte reagieren im Reaktor zu EG, Diethylenglykol (DEG) und Triethylenglykol (TEG). Unverbrauchte Edukte werden im Phasentrennapparat von den Glykolen getrennt und zum Reaktor rückgeführt. Im Rahmen dieser Arbeit nehmen wird an, dass allein die Reaktionskinetik in diesem Prozess nicht exakt bekannt ist. Unbekannte Reaktionskinetiken sind typisch für biotechnologische Prozesse sowie katalysierte Reaktionen, bei denen die Aktivität der Katalysatoren von zahlreichen Einflussgrößen abhängen kann. Für eine modellbasierte Optimierung des Prozesses ist es notwendig, die chemischen Reaktionen zu modellieren. Da eine rigorose Modellierung der Kinetik mittels einer Laboranalyse kostenund zeitaufwändig ist, wird diese hier durch ein leicht zu erstellendes empirisches Kinetikmodell beschrieben. Hierzu wurden in dieser Arbeit neuronale Netze [4] verwendet, da sie im Gegensatz zu den häufig verwendeten Potenzmodellen kein a priori Wissen in das Identifikationsproblem einbringen und flexibel an Messdaten angepasst werden können. Das resultierende stationäre Prozessmodell f(u,x,p) = 0 besteht somit aus zwei verschiedenen Modellarten: den rigorosen Teilmodellen für bekannte Phänomene, wie z.B. die
Ionic liquids with dual biological function: sweet and anti-microbial, hydrophobic quaternary ammonium-based salts

The dual nature of ionic liquids has been exploited to synthesize materials that contain two independent biological functions by combining anti-bacterial quaternary ammonium compounds with artificial sweetener anions. The synthesis and physical properties of eight new ionic liquids, didecyldimethylammonium saccharinate ([DDA][Sac]), didecyldimethylammonium acesulfamate ([DDA][Ace]), benzalkonium saccharinate ([BA][Sac]), benzalkonium acesulfamate ([BA][Ace]), hexadecylpyridinium saccharinate ([HEX][Sac]), hexadecylpyridinium acesulfamate ([HEX][Ace]), 3-hydroxy-1-octyloxymethylpyridinium saccharinate ([1-(OctOMe)-3-OH-Py][Sac]), and 3-hydroxy-1-octyloxymethylpyridinium acesulfamate ([1-(OctOMe)-3-OH-Py][Ace]), are reported, as well as the single crystal structures for [HEX][Ace] and [1-(OctOMe)-3-OH-Py][Sac]. Determination of anti-microbial activities is described for six of the ILs. While some exhibited decreased anti-microbial activity others showed a dramatic increase. For two of the ionic liquids, [DDA][Sac] and [DDA][ACE], oral toxicity, skin irritation, and deterrent activity was also established. Unfortunately, both ILs received a Category 4 (harmful) rating for oral toxicity and skin irritation. However, deterrent activity experiments point to use as an insect deterrent, as both ILs scored either “very good” or “good” against several types of insects.
Monte Carlo simulation of polyelectrolyte gels: Effects of polydispersity and topological defects

Volumes and other structural properties of polyelectrolyte gels in equilibrium with pure water have been determined by Monte Carlo simulations. The role of chain length polydispersity and topological network defects of four different networks with varying cross-linking density, monomer charge, and chain stiffness have been investigated. Generally, a chain length polydispersity reduced the gel volume, whereas the presence of chains with one end detached from the cross-linker (severed chains) led to an increased gel volume. Polyelectrolyte networks displayed the largest and uncharged polymer networks the smallest dependence on chain length polydispersity. The effect of severed chains was strongest for flexible polyelectrolyte gels and weakest for uncharged networks and stiff polyelectrolyte gels. Mechanical properties of uncharged and charged polymer gels were also investigated through uniaxially stretching and compared with theory.