Miracle-dz/UniFAR-FTUs huggingface dataset:
Fragmentation of Ziegler‐Natta Catalyst Particles During Propylene Polymerization

Summary: Analyzing polymer particles by microscopy technique at different polymerization times provided information regarding the catalyst support break-up rate and degree of fragmentation during polymerization. Polymer samples were prepared at different polymerization times and melted under a video microscope to track the progress of fragmentation. Studies focused on effect of the catalyst support on the process and degree of catalyst fragmentation. Fragmentation behaviors of both a catalyst without an external support and a silica supported Ziegler-Natta catalyst were compared. Fragmentation of catalyst was observed to occur in the whole catalyst matrix at the very beginning of polymerization. In the case of the catalyst without an external support, fragmentation was faster and more uniform than that of the silica supported catalyst. Results corresponded to the activity distribution of single catalyst particles as determined by video microscopy. The catalyst without an external support having particles of similar activities showed similar degrees of fragmentation. Conversely, silica supported catalyst having particles of different growth behavior produced particles having different degrees of fragmentation. The rate of increase in the number of catalyst fragments and their surface area with time during polymerization was investigated. Results correlated the catalyst activation period during the initial stage of polymerization to catalyst fragmentation. Poly(propylene) particles produced with silica supported (upper image) and non-supported (lower image) Ziegler-Natta catalysts.
Mechanisms of Chemical Phosphorus Removal II: Iron (III) Salts

A series of jar tests using iron (III) chloride were carried out to identify factors affecting phosphorus removal. Mixing conditions and the extent of iron hydrolysis prior to reaction with phosphate ions were explored using crude sewage as a medium. Somewhat surprisingly, the mixing conditions appeared to have little affect on the phosphorus removal performance. As expected, there was a strong link between phosphorus removal and iron:phosphate ratio during standard jar tests with iron (III) chloride. Total phosphorus removal of 80% was achieved at a dose of 1.48:1 molar ratio Fe:P. When a mixture of pre-hydrolysed iron and iron chloride was added, 80% total phosphorus removal was achievable at a dose of 1.86:1 molar ratio Fe:P. These findings could make a considerable difference to the cost of iron (III) chloride addition for phosphorus removal, if the hydrolysed product is formed preferentially to the phosphate. Increased costs could amount to more than £60,000 for a site treating a population equivalent of 200,000 and requiring a 1 mg l –1 total phosphorus effluent target. In reality, the hydrolysed product is unlikely to form to this extent but the results suggest that the formation of hydroxide may not only take place when the phosphorus removal reactions are complete as the relative reaction rates are more similar than perhaps was previously thought. Metal hydroxides have the capability to remove phosphorus by absorption but less efficiently.
Ultrafiltration of black tea using diafiltration to recovery valuable components

AbstractUltrafiltration of black tea liquor in a constant volume diafiltration regime has been carried out to remove the haze characteristically associated with this product. Commercial polymeric membranes with a range of molecular weight cut-offs (25, 50, and 100 kDa) fabricated from both polysulphone (PS) and fluoropolymer (FP) were used to assess the total solids throughput of the system. A shortfall in the amount of polyphenols transmission over the amount of residual tea solids transmission is the main driver for operating in this regime. The result of this shortfall means membrane permeates are impaired in terms of colour, flavour and health-giving properties. From an initial tea concentration of 1.0 wt. %, diafiltration was carried out, with rejection coefficients for total solids and total solids being assessed continuously. An acceptable (but not ideal) permeate product was the result, which showed excellent clarity (<2.0 nephelometric turbidity units (NTU) in the majority of cases) although the a.
Landscape and Land‐Use Effects on the Spatial Variation of Soil Chemical Properties

The current study addressed the spatial variation of soil organic matter (SOM), total nitrogen (TN), extractable phosphorus (EP), and extractable potassium (EK) in agricultural soils of a representative region, northeast China. Soil cation exchange capacity (CEC) and the effects of landscape attributes and land use were also investigated. The techniques used included conventional statistics, geostatistics, and geographic information systems (GIS). Our study demonstrated that EP had the greatest coefficient of variation (CV), and CEC had the least CV. The experimental semivariograms of the five soil chemical properties included in this study were all fitted with exponential models. The five soil variables all showed moderate spatial dependence. The SOM, EK, and CEC decreased with increasing altitude. Significant negative relationships were found between the slope gradient and EP, EK, and CEC. Relatively steeper slopes might result in greater soil erosion, which leads to a decline in soil nutrients. Soil types had significant impacts on all soil chemical properties, which reflect the effect of the parent soil material. In general, the mean values of soil variables for vegetable land were statistically greater than those for upland and paddy fields. After being divided into two parts along the Yinma River, soil samples of the western part have statistically greater SOM, EP, EK, and CEC values than those collected from the eastern part.
Controlling emission color through Förster resonance energy transfer in hybrid colloidal particles

Hybrid particles from insoluble luminescent π-conjugated polymers were formed through a miniemulsion approach. The color characteristics of the PL for the particles could be tuned by exploiting the Förster resonance energy transfer between the polymers within a particle, while suppressing energy transfer between particles, and exhibited 1931 CIE x,y-color coordinates that ranged from 0.153, 0.071 to 0.267, 0.559 with corresponding dominant wavelengths of 466 nm to 536 nm with an excitation energy at a wavelength of 389 nm.
Exercício aeróbico de diferentes intensidades e respostas cardiovasculares agudas e subagudas em pacientes com hipertensão arterial resistente

Regular aerobic exercise is a useful intervention in hypertension management, promoting acute and chronic benefits in patients with hypertension. However, little is known about its shortterm effects on patients with resistant hypertension. Accordingly, we aimed to compare post exercise hemodynamics and ambulatory blood pressure in different intensities of aerobic sessions and a non-exercise control session in patients with resistant hypertension. After a cardiopulmonary exercise test, 18 subjects (54.0 ±5.7 years, 30.2 ±4.9 kg/m, 125 ±17.1/73.5 ±9.6 mm Hg) participated in three intervention sessions in random order, crossover design, and on separate days: control session (45’ of rest), light intensity session and moderate intensity session (45’ of aerobic exercise at 50% and 75% of maximum heart rate or perceived-exertion equivalent, respectively). Ambulatory blood pressure (19h), forearm blood flow, vascular resistance and reactive hyperemia were measured before and after all sessions. Forearm blood flow decreased only 50 minutes after light intensity (p<0.05). In control and light intensity sessions, forearm vascular resistance increased at the final minutes of 1h recovery period and in moderate intensity session, decreased immediately after the intervention (p<0.05). Exercise sessions reduced ambulatory systolic blood pressure in a 5h period (p<0.05), when compared with control session. In addition, light intensity session induced lower values in ambulatory diastolic blood pressure during nighttime and total time (p<0.05). A single aerobic exercise session in light or moderate intensities is capable of inducing beneficial changes in ambulatory blood pressure in resistant hypertension, with advantages in effect length choosing lighter intensities.
Anodic Adsorptive Stripping Voltammetry at a Carbon Paste Electrode for Determination of Trace Thorium

Abstract A sensitive adsorptive stripping voltammetric procedure for trace measurement of thorium, based on the oxidation peak of thorium(IV)–alizarin complexan complex at a carbon paste electrode (CPE) during a positive-going potential scan from −0.1 V to 0.9 V (vs. SCE), is described. Optimum experiment conditions include the use of 0.12 M acetate–0.03 M potassium biphthalate buffer solution (pH4.6), 3.2 × 10−6 M alizarin complexon (ALC), an accumulation potential of −0.1 V, and a scan rate of 150 mV s−1. The detection limit after a 180 s preconcentration is 4.0 × 10−10 M (S/N=3), a linear current–concentration relationship is observed up to 3.0 × 10−7 M, and the relative standard deviation is 4.2% for 15 successive determinations on the same electrode surface at the 4.0 × 10−8 M level. Possible interferences are evaluated. The electrode processes of the adsorbed complex are proposed. The method has been applied to determination of trace thorium in ores with good results.
Reservoir Analysis by Well Log Data

Abstract The aim of this research is to describe and characterize the reservoir sections by well log data. Well logs are used to examine the porosity, water saturation and true resistivity properties of the reservoir. Throughout the project, the data is processed using geostatistical tests that are frequency, histograms, auto-correlation, cross-correlations, linear and multiple regression analysis to find the relations between the variables. Statistical analyses are performed using SPSS software. From the output of the software, the data of the reservoir section would be improved resulting in a higher efficiency in the usage of the data.
Factors affecting the removal of geosmin and MIB in drinking water biofilters

Bench‐scale experiments were conducted using four parallel dual‐media filter columns containing biologically active anthracite or granular activated carbon media and sand. The factors under investigation were low‐ (8°C) and high‐ (20°C) temperature operations, geosmin and 2‐methylisoborneol (MIB) concentration, media type, and biodegradable organic matter (BOM) level. Source water consisted of dechlorinated tap water to which geosmin and MIB were added, as well as a cocktail of easily biodegradable organic matter (i.e., typical ozonation by‐products). Phase 1 experiments used a high BOM level (280 μg/L carbon [C]) to simulate water that had been subjected to ozonation before filtration. Phase 2 experiments used a low BOM level (28 μg/L C) to simulate nonozonated water. Factorial design experiments showed that all four main factors (temperature, concentration, media, and BOM level) were important to both geosmin and MIB removal. Temperature and media interaction and concentration and BOM level interaction were significant for geosmin removal only. Temperature and BOM level interaction as well as media and BOM level interaction were significant for the removal of both geosmin and MIB. Overall, removals of geosmin and MIB were lower in phase 2 (low BOM level), in particular in the anthracite media filters. Biomass levels in the filters appeared to have a significant effect upon the removal efficiencies of both odor compounds.
Determination of trace amounts of copper in natural water samples by flame atomic absorption spectrometry coupled with flow injection on-line solid phase extraction on ambersorb 563 adsorption resin

Ambersorb 563 adsorption resin was used for on-line separation/preconcentration and determination of copper by flow injection flame atomic absorption spectrometry. Copper was quantitatively recovered from the model solutions on mini column at the appropriate pH without adding chelating reagent. The elution step was performed with a stream of 0.25 mol L - 1 HNO 3 at 5.0 mL min-', which introduced copper directly into the nebuliser of the flame atomic absorption spectrometer. The proposed method was successfully applied to the determination of copper in natural water samples. The detection limit (3σ) was 1.0 μg L - 1 for preconcentration at the flow rate 5.0 mL min - 1 . The recoveries of spike additions to water samples exceeded 95%.
Photodegradation of a herbicide derivative, 2,4-dichlorophenoxy acetic acid in aqueous suspensions of titanium dioxide

The photocatalytic degradation of a herbicide derivative, 2,4-dichlorophenoxy acetic acid (2,4-D, 1), has been investigated in aqueous suspensions of titanium dioxide. The degradation was studied by monitoring the change in substrate concentration employing UV spectroscopic analysis and decrease in Total Organic Carbon (TOC) content as a function of irradiation time in the presence of UV light source. The degradation kinetics was investigated under a variety of conditions, such as different types of TiO2, pH, catalyst and substrate concentrations. Higher photonic efficiencies were observed with Degussa P25 as compared with other photocatalysts. The degradation products were analysed by GC-MS and probable pathways for the formation of different products were proposed.
A feasibility study quantifying in vivo human α-tocopherol metabolism

BACKGROUND Quantitation of human vitamin E metabolism is incomplete, so we quantified RRR- and all-rac-alpha-tocopherol metabolism in an adult. OBJECTIVE The objective of the study was to quantify and interpret in vivo human vitamin E metabolism. DESIGN A man was given an oral dose of 0.001821 micromol [5-14CH3]RRR-alpha-tocopheryl acetate (with 101.5 nCi 14C), and its fate in plasma, plasma lipoproteins, urine, and feces was measured over time. Data were analyzed and interpreted by using kinetic modeling. The protocol was repeated later with 0.001667 micromol [5-14CH3]all-rac-alpha-tocopheryl acetate (with 99.98 nCi 14C). RESULTS RRR-alpha-tocopheryl acetate and all-rac-alpha-tocopheryl acetate were absorbed equally well (fractional absorption: approximately 0.775). The main route of elimination was urine, and approximately 90% of the absorbed dose was alpha-2(2'-carboxyethyl)-6-hydroxychroman. Whereas 93.8% of RRR-alpha-tocopherol flow to liver kinetic pool B from plasma was returned to plasma, only 80% of the flow of all-rac-alpha-tocopherol returned to plasma; the difference (14%) was degraded and eliminated. Thus, for newly digested alpha-tocopherol, the all-rac form is preferentially degraded and eliminated over the RRR form. Respective residence times in liver kinetic pool A and plasma for RRR-alpha-tocopherol were 1.16 and 2.19 times as long as those for all-rac-alpha-tocopherol. Model-estimated distributions of plasma alpha-tocopherol, extrahepatic tissue alpha-tocopherol, and liver kinetic pool B for RRR-alpha-tocopherol were, respectively, 6.77, 2.71, and 3.91 times as great as those for all-rac-alpha-tocopherol. Of the lipoproteins, HDL had the lowest 14C enrichment. Liver had 2 kinetically distinct alpha-tocopherol pools. CONCLUSIONS Both isomers were well absorbed; all-rac-alpha-tocopherol was preferentially degraded and eliminated in urine, the major route. RRR-alpha-tocopherol had a longer residence time and larger distribution than did all-rac-alpha-tocopherol. Liver had 2 distinct alpha-tocopherol pools. The model is a hypothesis, its estimates are model-dependent, and it encourages further testing.
Hydrogen Storage Properties of Space-Confined NaAlH4 Nanoparticles in Ordered Mesoporous Silica

A method that is used by space-confining NaAlH4 into the as-synthesized ordered mesoporous silica (OMS) is presented in the present work. NaAlH4 in the pores of OMS is obtained by impregnation and drying techniques. It has been found that the space-confined NaAlH4 in the pores of OMS shows the lower temperature and faster kinetics for dehydrogenation than that of the pristine NaAlH4. Moreover, in the absence of a catalyst, the rehydrogenation in a dehydrogenated NaAlH4 system with nanoscale particles and phases can be achieved even with the temperatures of 125−150 °C and the hydrogen pressures of 3.5−5.5 MPa. The physical limitation of the NaAlH4 particles, as well as the resulting Al and NaH phases, to be nanoscale in size by the pores of OMS is believed to be responsible for these.
Changes of Dextrose Particles with Pneumatic Conveying: Analysis of Size and Shape

When conveying particulate materials, changes in size and shape of individual particles can be observed. These changes can have a great impact on the bulk powder and affect its flow properties in the pipeline. Changes can be wanted or unwanted depending on the whole process chain and final use of the powder. In this investigation, dextrose monohydrate particles were pneumatically conveyed repetitively in a pilot plant–scale rig, and the size and shape of the particles were characterized by a semiautomatic image analysis method. This characterization was done qualitatively by observing micrographs and quantitatively for each individual particle (a total of 16,120 dextrose crystals) by using two statistical diameters and two shape factors. The effect of the changes in shape and size of the particles on the mass flow rate in the system was studied. It was concluded that the mass flow rate of the pneumatic conveying tests was not affected considerably by the changes of the dextrose particles.
High heat-resistant linear propargyl ether-terminated polymers containing Si–H group: synthesis, characterization, and properties

Two kinds of novel linear propargyl ether-terminated polymers containing Si–H group, poly[(phenylsilylene)propargyl-bisphenol A] and poly[(phenylsilylene)propargyl-bisphenol S], were synthesized successfully by the dehydrogenative cross-coupling reaction of dipropargyl ethers of different bisphenols and phenylsilane. The structures of the resulting polymers were confirmed by Fourier transform infrared (FT-IR) and proton nuclear magnetic resonance (1H NMR) spectroscopy. The molecular weights of the polymers were estimated by gel permeation chromatography. The polymers had excellent solubility and outstanding processability. Thermal curing behavior of the polymers was studied by differential scanning calorimetry (DSC) and FT-IR spectra. Thermal stability of the cured polymers was also investigated by DSC and thermogravimetric analysis. The results showed that the values of glass transition temperature of the cured polymers are above 380°C.
DENSITIES AND DERIVED THERMODYNAMIC PROPERTIES OF THE BINARY SYSTEMS OF BENZENE WITH BUTYL METHACRYLATE, ALLYL METHACRYLATE, METHACRYLIC ACID, AND VINYL ACETATE AT 298.15 K

Densities of the binary systems of benzene with butyl methacrylate, allyl methacrylate, methacrylic acid, and vinyl acetate have been measured as a function of the composition, at 298.15 K and atmospheric pressure, using an Anton Paar DMA 5000 oscillating U-tube densimeter. The calculated excess molar volumes were correlated with the Redlich-Kister equation and with a series of Legendre polynomials. The excess molar volumes are positive for the four binaries studied.
Improved adhesion properties of poly-p-phenyleneterephthamide fibers with a rubber matrix via UV-initiated grafting modification

In this research, ultraviolet (UV) irradiation induced graft polymerization of glycidyl methacrylate (GMA) was performed to modify the surface properties of poly-p-phenyleneterephthamide (PPTA) fibers. The improvement of adhesion with a rubber matrix was achieved due to the introduction of epoxy groups. The successful grafting of GMA on the PPTA fiber surface was ascertained by characterization using X-ray photoelectron spectroscopy (XPS), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), and scanning electron microscopy (SEM). The tensile properties of PPTA fibers after each stage of surface modification were determined by tensile testing of single-filaments. A single-fiber pull-out test was applied to evaluate the adhesion of PPTA fibers with the rubber matrix. The pull-out force of grafted PPTA fibers exceeded that of the pristine fibers by 53.7%. Resorcinol–formaldehyde–latex (RFL) dipping was applied to further improve the adhesion properties. As a result, the fibers with GMA grafting followed by RFL dipping exhibited a 80.8% improvement compared with the pristine fibers and achieved much higher adhesion strength with rubber matrix, compared to the PPTA fibers modified with conventional industrial method of isocyanate (NCO) and RFL two bath dipping.
CONCENTRATION AND DISTRIBUTION OF IRON AND MANGANESE FRACTIONS IN ALABAMA ULTISOLS

Information on metal forms and contributions of soil properties on metal distribution in Alabama soils is either limited or meager. This study chemically partitioned and evaluated soil Fe and Mn distributions and applied stepwise multiple regressions to identify the soil properties influencing their distributions in some Alabama Ultisols. Iron and Mn distributions among metal fractions were generally dependent on total metal content, soil properties, and degree of chemical weathering. Distributions among metal fractions showed that Fe was mainly in the residual fraction (> 85%), whereas Mn was predominantly oxide-bound and in the residual fraction (> 90%). The proportion of Fe fractions in the soils was in the order: residual > oxides (crystalline FeO, amorphous FeO, MnO) > organic > exchangeable, whereas Mn was in the order: oxide-bound (MnO, amorphous FeO, crystalline FeO,) > residual > exchangeable > organic fraction. Stepwise multiple regression analysis showed that pH accounted for 33% of the total variability in exchangeable Fe, whereas SOM accounted for 47.1% of the total variability in exchangeable Mn. Clay and sand contents accounted for 42.2 and 52.3%, respectively, of the total variability in the residual Fe fraction, whereas silt accounted for 19.7% of the total variability in residual Mn distribution in these soils.
Liquid crystals for twisted nematic display devices

This article describes the use of nematic liquid crystals in the Twisted Nematic Liquid Crystal Display (TN-LCD) since the large majority of instruments manufactured currently incorporating a liquid crystal display (LCD) utilise this type of device. The correlation between the electro-optical performance of these devices and the invention and synthesis of nematic liquid crystals with a continually improved property spectrum in order to meet constantly changing specifications is illustrated using the TN-LCD as an example of general trends and relationships.
Effect of dissolved oxygen on the surface tension of liquid iron

AbstractThe oscillating drop technique was used to measure the surface tension of liquid iron-oxygen alloys in the temperature range 1560–1645°C. No noticeable temperature dependence of the surface tension was observed. The surface activity of oxygen in iron was determined to be 2.1 × 106 dynes/cm. This value is twice as large as the accepted value in the literature. According to the monolayer approximation, the liquid iron surface becomes saturated with oxygen when each adsorbed oxygen atom occupies an area of 11.4 A2. Data-analysis suggests that saturation of the surface of liquid iron with oxygen results from the formation of a two-dimensional ionic compound. This compound seems to correspond to Fe2O or FeVO, where V stands for a vacancy. Resume La technique de la goutte oscillante a et e employ ee pour mesurer la tension superficielle des alliages liquides fer-oxyg ene entre 1560°C et 1645°C. Aucune variation de la tension superficielle avec la temperature n'a ete observee. L'activite suferficielle de.