Miracle-dz/UniFAR-FTUs huggingface dataset:
The phenomenon of thermal channelling in countercurrent gas-solid heat exchangers

Maldistributed flow in moving-bed reactors and heat exchangers is recognized to be a serious problem. Heat exchanger equations do not provide a clue to the cause. In this paper it is shown that maldistributed flow can occur even in perfectly homogeneous packed beds and that this arises because of inherent temperature non-uniformities. The term thermal channelling is introduced to describe this effect. It is shown that simultaneous consideration of both the heat and the mechanical energy (the Ergun equation) balances predicts that the gas, in cooling a hot bed, divides into a multiplicity of stable channels with significantly differing mass velocities. This does not, however, occur for the inverse case of heating the bed. Further, it is shown that the system conditions where a multiplicity of states is stable can be defined in terms of an integral mean temperature and two dimensionless variables, NTU and the bed Reynolds number. In general tall beds with large temperature differences are most prone to thermal channelling. La mauvaise distribution de l'ecoulement dans les reacteurs a lits mobiles et les echangeurs de chaleur s'avere ětre un probleme serieux. Les equations des echangeurs de chaleur ne fournissent aucune indication permettant d'en determiner la cause. On montre dans cette etude qu'une mauvaise distribution de l'ecoulement peut se produire měme dans des lits garnis parfaitement homogenes et qu'elle est due a une non-uniformite inherente de la temperature. On introduit le terme de renardage thermique pour decrire cet effet. En utilisant simultanement les bilans de chaleur et d'energie mecanique (loi d'Ergun), il est possible de predire que le gaz, lors du refroidissement d'un lit chaud, se divise en de multiples canaux stables ayant des debits massiques qui different de maniere significative. Cependant, ceci ne se produit pas dans le cas inverse du chauffage d'un lit. En outre, on montre que les conditions dans lesquelles le systeme comporte une multiplicite stable d'etats peuvent ětre definies a l'aide d'une temperature moyenne integrale et de deux variables adimensionnelles, a savoir le nombre d'unites de transfert (NTU) et le nombre de Reynolds du lit. En general, les lits de grande hauteur ayant des differences de temperatures importantes sont les plus enclins au renardage thermique.
Study of polyethylene photodegradation in formulations with a system of interacting photostabilizers and antioxidants

The accelerated UV photodegradation process of low-density polyethylene films, formulated with two photostabilizers and two antioxidants, was studied to evaluate the effect of different combinations of UV stabilizers and antioxidants on the overall photodegradation process. An experimental design, consisting of 33 formulations with different additive ratios and a blank, was used to evaluate the performance of the four mixed additives. From each formulation, 200 micron-thick films were produced by the extrusion-blowing process. Samples from these films were submitted to accelerated UV aging, and the polymer degradation was measured by carbonyl group evolution, molecular weight distribution changes, and maximum elongation loss. The effect of the additive combination on the different degradation reactions is discussed qualitatively by using relative variables and a triangular diagram.
Desulfurization and Deashing of Adiyaman-Gölbaşi Lignite by Flotation

Abstract In this study, desulfurization and deashing of Adiyaman-Gölbaşi lignite by the flotation method were studied. For this purpose, the study was performed in three groups. The effects of solid concentration, NaOH, and HCI on the desliming before flotation were investigated in the first group of experiments. The effects of some parameters that markedly influence the effectiveness of flotation, such as grinding time, solid concentration, pH, collector type and amount, depressant type and amount, and frother type and amount on the flotation were investigated in the second group of experiments. The effects of lake water and sea water on the flotation were investigated in the third group of experiments. The influences of the Aegean Sea water and soda lake water on the removal of total sulfur were found to be important.
Orientational order parameters of a binary mixture showing both induced smectic and re-entrant nematic phases

The phase diagram of a new binary system of two polar nematic compounds, 4-cyanophenyl [4′ (4″-n-heptylphenyl)] benzoate(7CPB) and 4-cyanophenyl 4-nonylbenzoate (9.CN), shows the presence of both the induced smectic and re-entrant nematic phases in a certain concentration range 0.4 < x 9.CN < 0.87. The results of X-ray diffraction and density measurements are reported here. Orientational order parameters have been determined in the induced smectic, normal nematic and re-entrant nematic phases from X-ray diffraction measurements. The order parameters have been fitted to those calculated from modified McMillan's theory as proposed by Luckhurst and Timimi. The agreement is found to be closer to the modified model. The experimental variation of the layer thickness with mole fraction of 9.CN has also been explained fairly well by assuming the presence of two types of homo dimers (7CPB + 7CPB, 9.CN + 9.CN) and one type of hetero dimer (7CPB + 9.CN).
High-mobility Carbon-nanotube Thin-film Transistors on a Polymeric Substrate

We report the development of high-mobility carbon-nanotube thin-film transistors fabricated on a polymeric substrate. The active semiconducting channel in the devices is composed of a random two-dimensional network of single-walled carbon nanotubes (SWNTs). The devices exhibit a field-effect mobility of 150cm2∕Vs and a normalized transconductance of 0.5mS∕mm. The ratio of on-current (Ion) to off-current (Ioff) is ∼100 and is limited by metallic SWNTs in the network. With electronic purification of the SWNTs and improved gate capacitance we project that the transconductance can be increased to ∼10–100mS∕mm with a significantly higher value of Ion∕Ioff, thus approaching crystalline semiconductor-like performance on polymeric substrates.
Effect of vacuum and relaxation periods and solution concentration on the osmotic dehydration of apples

Summary The effect of the sucrose solution concentration (SSC) and vacuum–relaxation periods on vacuum osmotic dehydration of apples (Gala var.) was investigated. All experiments were carried out at 30 °C, with SSC ranging from 0 to 65 °Bx. The apple samples with 11.5 ± 1.4 °Bx gained water for an SSC as high as 40 °Bx and gained solids for an SSC as low as 5 °Bx, depending on the applied vacuum and relaxation periods. The results obtained with isotonic solutions indicated that there is an optimum value for the relaxation and vacuum periods. It was shown that the vacuum and relaxation periods can be used to obtain the desired process result, a higher impregnation or a higher dehydration.
1H and 13C spectral assignment of o‐chloroformyl substituted 1,4‐dihydropyridine derivatives

The 1H and 13C NMR spectroscopic data for alkyl 4‐aryl‐6‐chloro‐5‐formyl‐2‐methyl‐1,4‐dihydopyridine‐3‐carboxylates were fully assigned by combination of one‐ and two‐dimensional experiments (DEPT, HMBC, HMQC, COSY, NOE). Copyright © 2002 John Wiley & Sons, Ltd.
Determination of Cu in Tequila by Anodic Stripping Voltammetry

Abstract Concentrations of metals such as copper in alcoholic beverages must be strictly regulated due to negative effects ranging from beverage spoilage and hazing, to sensorial and health consequences. In this paper, a voltammetric alternative is presented for the analysis of copper in tequila, a Mexican spirituous alcoholic beverage. Anodic Stripping Voltammetry is applied and the standard addition method is used to quantify copper in this beverage at concentrations commonly present in tequila (<10 ppm) without sample pretreatment. Copper can be reduced and then oxidized quantitatively and reproducibly. A comparison of Anodic Stripping Voltammetry with Atomic Absorption Spectrometry is presented.
Influence of Hydrocolloids on Batter Properties and Textural Kinetics of Sponge Cake during Storage

The influence of hydrocolloids, including hydroxypropyl methylcellulose (HPMC), xanthan gum (XG) and sodium alginate (AG) at 0.5 and 1.0% (w/w, based on the wheat flour), on batter properties and textural kinetics of sponge cake during storage was studied. It was found that the addition of XG and AG dose-dependently increased the batter density and the viscosity of all the samples and also decreased the cake specific volume but increased the crumb moisture. The firmness change of sponge cake at different storage temperatures followed a first-order kinetic reaction, where the activation energy (Ea) decreased in the following order: HPMC > AG > XG, which is in contrast to the firmness change rate constant (k). Addition of 0.5% (w/w) HPMC gave the lowest k (0.1156 day−1) and highest Ea (11.23 kJ/mol) values, reflecting its better firmness retarding property. However, the use of HPMC at 1.0% (w/w) gave an adverse effect. Practical Applications Convenient baked snack foods, such as sponge cakes, are in increasing demand as a result of the changing lifestyles and economics of the global populations. However, the quality of sponge cakes changes (deteriorate) during storage. This study evaluated the use of three different hydrocolloids as potential firmness retarding agents during cake storage. Kinetics measurements were the key parameter used to describe the rate of reaction. Hydrocolloids that help to improve the texture of sponge cake are of a significant interest in the baked goods industry, and such archived research will benefit the industrial cake production for better distribution and marketing of these products.
Electron attachment to the chlorosilanes and chloromethanes

The cross sections for dissociative attachment in the chlorosilanes and chloromethanes for electrons in the energy range 0.2–5.0 eV have been measured. In addition, measurements of the total electron scattering cross sections of the chloromethanes in the 0.2–12.0 eV range are reported. It is observed that dissociative attachment is much more probable in the chloromethanes than the chlorosilanes. This is explained by quantum mechanical calculations which reveal qualitative differences in the nature of the electron–molecule complex for the silanes as compared to the methanes.
Magnesium availability from kieserite and calcined magnesite on five soils of different pH

Five soils from the South of England were incubated with additions of magnesium fertilizers ; two also received magnesian limestone. After two years, the recovery of the added magnesium by 0.5 h extraction with 1 M ammonium nitrate was 75-89% for kieserite granules, 64-84% for calcined magnesite powder (<1 mm), but only 20-41% for calcined magnesite granules (1-3 mm) and 26-32% for ground magnesian limestone. These were all much greater than the Mg dissolved by extracting the fertilizers directly in I M ammonium nitrate. In calcareous soils, recovery of Mg was less from the calcined magnesite but most of this reduction was due to its particle size rather than to soil pH. The four magnesium sources are evaluated as fertilizers for agriculture. Kieserite is the most reliable means of raising low soil Mg status.
Migration of Cyclic Monomer and Oligomers from Polyamide 6 and 66 Food Contact Materials into Food and Food Simulants: Direct Food Contact

Cyclic monomer and oligomers are the major migrating substances from polyamide (PA) food contact materials. An increase of caprolactam (+44%) and cyclic oligomer content (+27%, incl. caprolactam) in PA6 was observed by thermal treatment, here by extrusion of a PA6 film from a granulate. Migration experiments with a PA6 and a PA66 packaging film were carried out into food simulants according to directives 85/572/EEC and 82/711/EEC. Contact conditions (2 h/100°C) were chosen for a heat treatment of the food in the packaging, in this case production of scalded sausage. Aqueous and ethanolic food simulants clearly revealed to be the worst case for migration of cyclic PA6 and PA66 monomer and oligomers. Migration of cyclic oligomers into oil was one order of magnitude lower. No migration could be observed into isooctane (<8 µg dm−2). The substitutes for oil, 95% ethanol and isooctane, were inapplicable for simulating migration of cyclic oligomers into oil. Caprolactam showed different migration behaviour compared with cyclic oligomers, migrating into oil and water to the same extent depending on contact conditions. Fifty percent of the extractable caprolactam migrated from a PA6 sausage casing into scalded sausage (4.2 mg kg−1), residual 41% apparently were extracted by the boiling medium or during pretreatment (soaking) of the casing. Potential migration of caprolactam and cyclic oligomers from a PA6 tea bag was found to be 18% of the specific migration limit for caprolactam and 36% of the overall migration limit. Copyright © 2014 John Wiley & Sons, Ltd.
Physical Vapour Deposition and Bioactivity of Crystalline Titanium Dioxide Thin Films

Lack of interfacial stability is one of the causes behind the need for revision surgery of metallic implants. Thin films of titanium oxide have recently been proven to be bioactive ( in vitro ) and non-resorbable. The objective of the paper is to investigate the relationship between deposition parameters of thin crystalline titanium oxide films (using reactive sputtering), their microstructure and the in vitro bioactivity. The relative amounts of anatase and rutile were hard to control via the deposition parameters tested. No direct coupling between the hydroxylapatite layer and the crystalline films from different deposition runs could be derived from this investigation. © Society for Biomaterials and Artificial Organs (India), 20080314-15.
Optimization of immobilization parameters of Thermoanaerobacterium thermosaccharolyticum W16 on a new carrier for enhanced hydrogen production

A new biological carrier mycelia pellet was adopted for enhanced hydrogen production by Thermoanaerobacterium thermosaccharolyticum W16. Immobilization parameters were optimized by response surface methodology for achieving maximum hydrogen yield. To our best knowledge, this is the first report detailing the interaction of immobilization parameters of this bacterium on a mycelia pellet.
Microevolution in action : a quantitative case study on natural populations of Artemia spp.

Getting a comprehensive understanding of microevolution in natural populations requires proper quantification of the important selective forces exerted on these populations. Over the last decade, long-term studies and resurrection-ecology (revival of resting stages) have been the main approaches to study life history trait evolution over many generations in the wild. My work aims at understanding how simple ecological factors (e.g. temperature) and complex interactions between and within species (host-parasite and male-females antagonistic interactions) shape evolutionary processes in natural populations. To this end, I used the brine shrimp Artemia as a model system and combined laboratory and field studies. First, I investigated thermal niche evolution with a resurrection ecology approach, using dormant-egg time series from an Artemia population introduced from temperate to tropical salterns in the mid-80's. This experiment shows that survival at the high temperatures typical of the new environment increased linearly through time after the introduction, suggesting a sustained rate of adaptation over more than 100 generations. Second, I used the same approach to study adaptation between sexes in another Artemia population. I found that sexual conflicts result in fluctuating male-female coevolutionary dynamics in natura, over a time scale of ~100 generations. Third, I studied the relative role of one cestode and two microsporidian parasites in mediating the competition between a native asexual host and an invasive bisexual host. I found that all three parasites were either host- or genotype-specific and that the castrating cestode parasite specifically infected the native species, suggesting that this parasite actually played a major role in the competition between native and invasive hosts. Interestingly, all three parasites manipulated the swarming behavior of their host, most likely to increase their transmission. Fourth, I performed population genetic studies of diploid and polyploid Artemia parthenogenetica and their Asian bisexual close relatives. Diploid asexual Artemia produce rare males and I found indication that these males allow some rare sex in this otherwise parthenogenetic species. In addition, hybridization between divergent Artemia species has led to the origin of at least three independent polyploid lineages.
Investigation of the correlation between structural relaxation time and configurational entropy under high pressure in a chlorinated biphenyl

Dielectric relaxation measurements on a chlorinated biphenyl (PCB62) were carried out over a broad frequency range, with variation of both temperature and pressure. In combination with calorimetric determinations of the configurational entropy, these data could be described using the Adam–Gibbs model. Specifically, the experimental results were interpreted using a recently introduced equation for both the temperature and pressure dependencies of the structural relaxation time. The τ(T,P) data for PCB62 yielded values of the fitting parameters consistent with known physical properties of the material. A change of the dynamics was evident in isobaric measurements at atmospheric pressure, corresponding to a value of the relaxation time τB∼5×10−5 s. A related change of dynamics was observed in isothermal experiments at varying pressures. It is noteworthy that the latter transpired at a very similar τ∼τB. Moreover, the shape of the relaxation function depended only on the value of τ. We believe this is the fir.
Essential oils yield and heavy metals content of some aromatic medicinal plants grown in Ash-Shoubak region, south of Jordan.

The use of aromatic medicinal herbs to relieve and treat many human diseases is increasing in Jordan and worldwide due to their mild features and low side effects. It is important to have a good quality control for aromatic medicinal herbs in order to protect consumers from contamination. The aim of the present study was to carry out a comparative evaluation of essential oils yield and heavy metals content in some medicinal herbs such as Thymus vulgaris L. , Thymus serpyllum L. and salvia officinallis L. grown in Ash-Shoubak region-south of Jordan. The essential oils were hydro-distilled from studied dried aerial herbs using Clevengertype system. The heavy metals content in collected herbal samples were analyzed by using atomic absorption flame emission spectrometry by method described by Al-Alawi & mandiwana . Analytical results have evaluated by statistical analysis system. The mean values of essential oils yields of T.vulgaris, T. serpyllum , and S. officinalis were 4.0, 2.5 and 1.9 %, respectively. The contents of heavy metals in the samples were determined in the ranges of 1.26-32.03, 0.47-23.85, 7.66-13.23, 14.7-44.0, 15.8-114.91, 141.3-756.17ppm for Pb, Ni, Cu, Mn, Zn, Fe, respectively . Cobalt has been detected only in T. serpyllum, while Cd and Cr were not detectable in all studied samples. The highest Pb, Ni and Cu content has been detected in T. vulgaris (32.03ppm, 23.85ppm and 13.23 ppm, respectively. S. officinalis had The highest Mn, Zn and Fe content 44.0ppm, 114.91ppm and 756.17 ppm, respectively. The essential oils and heavy metals contents in studied plants are affected by environmental conditions. Moreover, the obtained results showed that the studied plants grown in Ash-shoubak region (with respect to the lead content in T.vulgaris) can safely be used for pharmaceutical and ethno-pharmacological purposes without any hazardous effect.
Stabilization of zwitterions in solution: γ-aminobutyric acid (GABA)

The stabilization of γ-aminobutyric acid (GABA) zwitterions in aqueous solution is investigated at the HF/6-31+G*, B3LYP/6-31+G*, and MP2/6-31+G* levels of theory using explicitly bound water molecules to model short-range solvent effects and the conductor-like screening solvation model (COSMO) to estimate long-range solvent interactions. B3LYP and MP2 yield similar structures, relative energies and overall trends whereas HF theory does not provide a realistic description of GABA. The only approaches yielding zwitterionic structures consistent with experiment are the application of COSMO to GABA·2H2O or GABA·5H2O. An accurate description of aqueous phase GABA therefore requires both explicit interaction with at least two water molecules and long-range dielectric interactions with the solvent. Both types of interaction preferentially stabilize zwitterionic over neutral structures and stabilize extended zwitterions with respect to folded conformers. No stable neutral GABA·5H2O tautomers are obtained, sugges.
Radio Soundings On Trapridge Glacier, Yukon Territory,Canada

As part of a program to study surge-type glaciers, a radar-depth survey, using a frequency of 620 MHz, has been made of Trapridge Glacier, Yukon Territory. Soundings were taken at 26 locations on the glacier surface and a maximum ice thickness of 143 m was measured. A rapid change in surface slope in the lower ablation region marks the boundary between active and stagnant ice and is suggestive of an “ice dam” or the water “collection zone” postulated by Robin and Weertman for surging glaciers.
A study on the possible impact of constructive lease capitalisation on selected listed South African companies' financial statements, in light of IFRS 16 leases

This study analyses the possible effects of constructive lease capitalisation on all companies in four sectors of the Johannesburg Stock Exchange (JSE) namely Industrial Transportation, Food and Drug Retailers, General Retailers and Travel and Leisure, in light of the impending adoption of IFRS 16.1 The capitalisation is performed using a model developed by Imhoff Jr., Lipe, & David, (1997) & Imhoff Jr., Lipe, & Wright, (1991) as well as further refinements in Dillon, (2014) & Fulbier, Silva, & Pferdehirt, (2006). The analysis looks at the effects of constructive capitalisation on key leverage and profitability ratios, and line items in the financial statements. The study also assesses the impact on disclosed loan covenants and whether constructive capitalisation will result in the breach of any covenants. The results show that the adoption of IFRS 16 has an impact on key ratios and line items specifically leverage ratios and earnings before interest, tax, depreciation and amortisation (EBITDA) margin. The sector most impacted is the Food and Drug Retailers. No loan covenants were breached as a result of constructive capitalisation, however the impact on the covenants was both positive and negative. 1 International Financial Reporting Standard 16: Leases iii TABLE OF CONTENTS ABSTRACT . II TABLE OF CONTENTS . III LIST OF TABLES. VI ILLUSTRATIVE EXAMPLES . VI