Solutions Of Various Concentrations Research Articles

Separation of aliphatic amino acids from aqueous media with an aminophosphonic ion exchanger

The sorption of the aliphatic amino acids glycine and α-alanine by an aminophosphonic ion exchanger is studied and the dynamics of sorption is described using a kinetic equation. Experimental studies were carried out on a designed experimental setup with a fixed ion exchanger layer, in which the purified and regenerating solutions are passed through the sorbent layer in various directions. The heterogeneous ion exchange process includes the transport of sorbent ions in the liquid phase to the grain surface and the removal of desorbed ions from it, interphase transfer, diffusion of sorbed and desorbed ions inside the grain, since not all functional groups of the sorbent are localized on the surface, and a reversible ion exchange reaction. The kinetic equation of the Thomas model takes into account the multistage sorption and adequately describes the dependence of the degree of extraction of the component on the duration of contact of the solution with the ion exchanger layer. The equation of the Thomas model has been modernized taking into account the effect on the dynamics of the process of diffusion resistances in the channels of the layer and the grains of the ion exchanger in a column with a fixed loading. The upgraded model is applied to describe the dynamics of ion exchange of aliphatic amino acids on an aminophosphonic ion exchanger and the possibility of using a one-dimensional capillary flow model to estimate the diffusion resistance during fluid movement in the channels of the ion exchanger layer is shown. The agreement of the calculated and experimental output curves of sorption of aliphatic amino acids from aqueous solutions of various concentrations has been verified. It is shown that the upgraded model adequately describes the dependence of the degree of amino acid extraction on the duration of contact of the solution with the polyampholite layer at different feed rates of the purified solution.

Centrifugal spinning of polymeric solutions: Experiments and modelling

We assess some of the main parameters affecting the performance of Centrifugal Spinning (CS), a method for making nanofibres, using laboratory experiments and modelling. Rheologically characterized polymer solutions of various concentrations are propelled into curved jet trajectories by an in-house CS device and they are visualized via high speed imaging, while final dried fibre morphology diameter distributions are characterized by scanning electron microscopy. Our experiments provide validations of a comprehensive string model, based on the viscoelastic upper convected Maxwell (UCM) constitutive equation for the polymer, allowing us to examine dependence of the CS process on the key dimensionless numbers. We experimentally analyze the effects of the polymer concentration, rotation speed, nozzle diameter, spinneret radius and nozzle angle, and correspondingly use the model to analyze the effects of the Weissenberg number (Wi), Rossby number (Rb), nozzle diameter ratio (ϵa0), spinneret radius ratio (ϵs0), and nozzle angle (α0) on the fibre trajectory and radius. Finally, we use a simple scaling analysis to classify the flow regimes into stable and unstable with respect to jet instabilities and breakup. The results of this analysis agree with the experiments in finding fibres stable at large capillary and Weissenberg numbers.

Preparation and Characterization of Catalyst Zn/Al2O3 Catalyst Using Dry and Wet Impregnation Method

Metal supported catalysts are used in many catalytic cracking processes. Experiments have shown that the increasing of metal loaded within the catalyst support may affected the increasing of cracking process conversion and selectivity. Therefore, a fundamental understanding of increasing the metal loaded is needed. In this study, Zinc on Alumina supported catalyst was prepared using the dry and wet impregnation methods to obtain the best amount of Zn metal content in Al2O3 as catalyst support with good characteristics for catalytic cracking. The prepared precursor solution in wet impregnation method was varied in concentration. While the dry impregnation method was varied in drying temperature. The Atomic Absorption Spectroscopy test results the metal content of Zn on the variation of precursor solution concentration on 0,5 M; 2,5 M; 4,5 M are 1,06%; 9,65%; 15,91% and in the variation of the drying temperature at 25ºC, 50ºC, and 80ºC respectively are 18,32%; 12,48%; and 39,07%. Characteristics analysis through X-Ray Diffraction, Brunauer-Emmet-Teller, and Scanning Electron Microscopy tests have also been carried out on samples with the highest metal content of 39,07% and samples with the lowest metal content of 1,06%.

Morphological Evolution of Gold Nanoparticles Synthesized via Solution Plasma Sputtering: Effect of Sodium Chloride Concentration and Storage Time

Morphological control of gold nanoparticles (AuNPs) is vital for tuning their optical, chemical, physical, and catalytic properties for desired specific applications. Despite numerous efforts dedicated in recent years, controlling the morphology of AuNPs synthesized via solution plasma sputtering (SPS) remains a challenge, requiring further investigation. Herein, AuNPs were synthesized via SPS in sodium chloride (NaCl) solutions of various concentrations (0.5, 1, 2, and 5 mM). Evolutions of localized surface plasmon resonance and morphology of AuNPs over a 30 day storage period were thoroughly examined using ultraviolet–visible spectroscopy and field-emission transmission electron microscopy. The formation and growth mechanisms of AuNPs during and after synthesis provide more insights into this nascent field. At the initial storage time, AuNPs with chain-like structures were observed at all the NaCl concentrations. Their size tended to increase from 6 to 10 nm with a broader size distribution with increasing NaCl concentration. At a prolonged storage time of 15 days, AuNPs became smaller and more isolated at all NaCl concentrations owing to the oxidative etching effect. After 30 days of storage, the number of Au ions dissolved from etching slowly reduced and grew on the AuNPs, affording increased particle sizes. The interplay between etching and growth processes proceeded until reaching equilibrium. AuNPs exhibited good colloidal stability at low NaCl concentrations (i.e., 0.5, 1, and 2 mM); however, coalescence and sedimentation occurred at a high NaCl concentration of 5 mM owing to a considerable reduction in the electrical double-layer thickness. These results demonstrated that the NaCl concentration and storage time crucially affect the morphological evolution and stability of AuNPs synthesized via SPS.

Wearable Localized Surface Plasmon Resonance-Based Biosensor with Highly Sensitive and Direct Detection of Cortisol in Human Sweat

Wearable biosensors have the potential for developing individualized health evaluation and detection systems owing to their ability to provide continuous real-time physiological data. Among various wearable biosensors, localized surface plasmon resonance (LSPR)-based wearable sensors can be versatile in various practical applications owing to their sensitive interactions with specific analytes. Understanding and analyzing endocrine responses to stress is particularly crucial for evaluating human performance, diagnosing stress-related diseases, and monitoring mental health, as stress takes a serious toll on physiological health and psychological well-being. Cortisol is an essential biomarker of stress because of the close relationship between cortisol concentration in the human body and stress level. In this study, a flexible LSPR biosensor was manufactured to detect cortisol levels in the human body by depositing gold nanoparticle (AuNP) layers on a 3-aminopropyltriethoxysilane (APTES)-functionalized poly (dimethylsiloxane) (PDMS) substrate. Subsequently, an aptamer was immobilized on the surface of the LSPR substrate, enabling highly sensitive and selective cortisol capture owing to its specific cortisol recognition. The biosensor exhibited excellent detection ability in cortisol solutions of various concentrations ranging from 0.1 to 1000 nM with a detection limit of 0.1 nM. The flexible LSPR biosensor also demonstrated good stability under various mechanical deformations. Furthermore, the cortisol levels of the flexible LSPR biosensor were also measured in the human epidermis before and after exercise as well as in the morning and afternoon. Our biosensors, which combine easily manufactured flexible sensors with sensitive cortisol-detecting molecules to measure human stress levels, could be versatile candidates for human-friendly products.

Spatial and temporal controls on the solute behavior of rivers in arid watersheds: The Okavango River, NW Botswana

Solute cycling models for rivers in arid watersheds must identify solute sources and their spatial and temporal connectivity to rivers to assess the processes that control the solute behavior in these rivers. In this study, we collected hourly time series of total dissolved ions (TDI) concentrations, water levels, water temperatures and air temperatures at select stations distributed longitudinally in a river in an arid watershed. Our objectives were to: (1) document the spatial and temporal variations in solute concentrations and (2) determine the processes controlling the spatial and temporal variations in solute concentrations. We conducted this investigation over a two-year period at four stations along the Okavango River flowing through the Okavango Delta (Delta) in the middle Kalahari Desert, Botswana. At the spatial scale, we observed progressive downriver enrichment in TDI concentrations associated with evapotranspiration of river water because of the 5 months river transit across the hot Delta. At a temporal scale, the TDI concentrations increased seasonally from evapoconcentration and sub-seasonally from solute transfer from the watershed to the river. We analyzed sub-seasonal TDI concentration perturbations using the slope (β) of the relationship between TDI concentrations and normalized water level (C-NWL) relationships. We find that at low discharge during flow recession and at the beginning of rising discharge from flooding, the solute enrichment anomalies with β > 0 are related to hydrologic connectivity between the river and solute stores in the river floodplains, hundreds of thousands of salt islands and isolated evapoconcentrated wetland pools. Our findings indicate that hydrologically-driven river connectivity to solute stores in the local watershed and evapotranspiration jointly control the solute behavior at variable spatial and temporal scales in rivers in arid watersheds. We anticipate that our findings will inform solute transport and solute cycling models for rivers in arid watersheds.

Anodic instability of carbon in non-alkaline Zn-air batteries.

Although non-alkaline rechargeable Zn-air batteries (RZABs) are promising for energy storage, their chemistry is still underdeveloped and unclear. It was suggested that using Zn(OAc)2 or Zn(OTf)2 aqueous solutions as electrolytes enables reversible, corrosion-free charge-discharge processes, but the anodic stability of carbon in these cells has remained poorly studied. We report that CO2 evolution is manifested during the oxygen evolution reaction in non-alkaline RZABs, which is associated with the corrosion of carbon scaffolds. This corrosion is observed for different electrolyte compositions, such as Zn(OAc)2, ZnSO4 and Zn(OTf)2 solutions of various concentrations. The corrosion rate decreases when the overpotentials during the oxygen evolution reaction are lower. This study underlines the importance of addressing the anodic instability of carbon in non-alkaline RZABs.

Кинетика самосборки кластеров эндоэдральных металлофуллеренов в полярном растворителе

The evolution of the morphological properties of solutions of endohedral metallofullerene La@C82 in N,N-dimethylformamide in the presence of a coagulant was studied by dynamic and static light scattering methods. Based on the experimental results, the time evolution of the light scattering intensity, and the hydrodynamic radius of endohedral metallofullerene clusters, their association constants and aggregation rates are determined. Based on the analysis of the angular dependences of light scattering in solutions of endohedral metallofullerenes, the fractal dimension of La@C82 clusters in solutions of various concentrations at the initial and final stages of their aggregation was estimated.

Исследование экологических и агрохимических показателей осадков сточных вод методом фитотестирования

Purpose: to assess environmental and agrochemical indicators of sewage sludge from municipal wastewater treatment plants through phytotesting. Materials and methods. Sewage sludge from municipal wastewater treatment plants with a three-year stay on the sludge map was studied. The examined sludge contains a high amount of sulfate ions (0.720 g/100 g) with a content of calcium ions of 0.350 g/100 g. The remaining salt ions and heavy metals are in small quantities. Phytotesting was carried out by studying the phytoresponse of the test plants seeds in contact with an aqueous extract and directly with precipitation. In the first variant, solutions of various concentrations were prepared: an aqueous extract of sediments, its two-fold dilution and four-and eight-fold dilution. To control the indicators, the distilled water and one-component model solutions of sodium sulfate with concentrations identical to the tested solutions were used. Testing was carried out on the seeds of oats and vetch. In the second variant, under laboratory conditions, seeds of oats, vetch, white mustard, radish and watercress were sown in vegetation vessels with sewage sludge. Results and discussion. Phytotesting allowed revealing the complex effect of precipitation due to their composition. In the variant of undiluted aqueous extract from sewage sludge, the inhibitory effect of sulfates on seed germination and biomass growth is revealed. In the variant with two-fold dilution, the stimulating effect of precipitation components on seed germination and biomass growth was noted. To clarify the effect of the stimulating effect of sewage sludge, an experiment on sowing test plants directly into the sludge was carried out. The best indicators were noted in the variants with oats sowing. Conclusions. The inhibitory effect of sewage sludge from municipal wastewater treatment plants in Novocherkassk is due to the content of sulfates in them. The best comparability of indicators in both variants was noted for oat seeds.

Mechanical behavior of chemically-treated hemp fibers reinforced composites subjected to moisture absorption

Natural Fibers Reinforced Composites (NFRC) are finding much interest as substitutes for glass- or carbon-reinforced composites thanks to their lightness, easy handling, processing and recyclability. However, their polarity makes them incompatible with hydrophobic thermoplastic matrices, leading to extended moisture adsorption which causes the debonding between fibers and matrix, affecting, thus, the mechanical properties of NFRCs. In the present work, NFRCs were manufactured using hemp fibers previously chemically treated with NaOH alkali solutions or (3-Glycidyloxypropyl) trimethoxysilane (GPTMS) solutions of various concentrations. To assess the effectiveness of the used chemical treatments in hindering the moisture adsorption and the entailed mechanical failure of the NFRCs, untreated and treated hemp fibers based composites were subjected to moisture adsorption test and then to tensile testing as a function of the chemical treatment, temperature and concentration of reagents. The results show that the treatments with 5 wt% of both NaOH and GPTMS are the most effective, reducing composites' water uptake from 7.74% to 6.46% and 5.58% respectively at room temperature, and from 9.67% to 8.19% and 8.13% respectively at 50 °C. Moreover, the comparison between the mechanical testing results carried out before and after the moisture adsorption test, shows that the water uptake induces mainly a stiffness decrease (about 50% when alkali treatments were used and about 60% using silane treatment), while not significantly affect the loading capability of the composites regardless of chemical treatment. However, the specimen obtained using 5 wt% GPTMS is more effective in the prevent the failure of the composite induced by water uptake.

Фазовые переходы сгущенного молока с сахаром в расширенных температурных диапазонах хранения

Sweetened condensed milk is a popular food in various climatic zones, including those regions where average winter temperature falls below –30°C. Such low temperatures can trigger crystallization because they disrupt the native structure of biopolymers. These processes spoil the quality of sweetened condensed milk. However, no scientific publications feature the cryoscopic temperature of sweet condensed milk or systematize the data on its low-temperature storage.
 Sugar, sugar-milk, and milk solutions of various concentrations were frozen to determine their cryoscopic temperature by the thermographic method using a Testo 176T4 meter (Germany) with K-type probes (NiCr-Ni) at –78.5°C. The phase transitions were studied using a Mettler Toledo DCS 822e DSC analyzer.
 The nucleation temperature, the cryoscopic temperature, and the subcooling degree depended on the concentration and the type of the solute. For sugar solutions, the cryoscopic temperature varied from –0.4 ± 0.1 to –6.4 ± 0.1°C; for sugar-milk solutions, it ranged from –2.1 ± 0.1 to –10.9 ± 0.1°C; for whole milk solutions, it was from –0.4 ± 0.1 to –4.6 ± 0.1°C. The thermographic method failed to obtain the phase transition and the cryoscopic temperature in analogue models of sweetened condensed milk. The loss of fluidity was about –30°C when the storage time exceeded 2 h. This effect was comparable to 54 min of storage at –35°C. The differential scanning calorimetry meth od showed that the phase transition occurred at –80°C.
 This research opens new prospects for differential scanning calorimetry studies of phase transitions in condensed sweetened dairy products.

Syndrome of hyperosmolar hypohydration in the experiment: features of morphological disorders in brain tissues of rats with homeostasis disorders of different degrees of severity

Annotation. In neurosurgical patients, damage to the hypothalamic-pituitary region in 30% of cases can be complicated by the development of central diabetes insipidus, manifested by gross disturbances of the water-salt balance: the development of hypertonic hypohydration, which leads to functional and structural damage to organs and tissues. The purpose of the study was to simulate in an experiment the syndrome of hyperosmolar hypohydration, to investigate the peculiarities of morphological changes in brain tissues of animals depending on the level of osmolarity of blood plasma. To simulate hyperosmolar hypohydration, laboratory rats were injected intraperitoneally with furosemide solution (5.0 mg per kg-1), and under anesthesia intravenously – 2.0 ml of hyperosmolar sodium chloride solution of various concentrations (from 1.8% to 9%). The degree of hypohydration of the body, degree of hyperosmolarity, duration of coma, and lethality were studied. Pieces of the brain tissue were taken for histological examination, and their processing was carried out according to generally accepted methods. Histological slides were studied using a SEO SСAN light microscope. In hyperosmolar coma, under the conditions of administration of 7.2% sodium chloride solution to rats, blood-filled vessels with moderate perivascular edema were found in the brain tissues. Heterogeneous changes were characteristic of neurocytes, among them there were normochromic, isolated hypochromic and a significant number of hyperchromic neurocytes, and pericellular edema was detected. In brain tissues in hyperosmolar coma caused by the administration of 8.1% sodium chloride solution, an increase in amount of blood in vessels with pronounced erythrostasis was found, and small isolated hemorrhages were identified. Perivascular edema was significant in most of the vessels. Karyopyknosis and hyperchromatosis were characteristic of neurocytes, significant pericellular edema was also detected. In the tissues of the brain, in hyperosmolar coma, caused by the introduction of 9.0% sodium chloride solution, an increased amount of blood-filled vessels with pronounced erythrostasis was observed. Vessels walls were with pevascular edema, plasmarrhagia was also marked. In most fields of vision, hyper- and sharply hyperchromic neurocytes were identified, which were characterized by compaction, pyknosis, and pericellular edema. In brain tissue in hyperosmolar coma caused by intravenous administration of 7.2%, 8.1% and 9.0% solutions of sodium chloride, the appearance and progression of the following histological changes were established: blood-filled vessels, erythrostasis, small diapedesis hemorrhages, significant pevascular edema due to plasmarrhagia. Heterogeneous changes in neurocytes, with the appearance and predominance of hyper- and sharply hyperchromic cells, and significant pericellular swellings were established.

Drop deformation during diffusiophoresis

Diffusiophoresis refers to the motion of a colloidal particle in a solute concentration gradient, animated by particle–solute interactions. We present a theoretical analysis of the diffusiophoretic motion of a viscous drop in a gradient of neutral solute at zero Reynolds number. In a spatially uniform gradient, the translational velocity of a spherical drop was found by Anderson et al. (J. Fluid Mech., vol. 117, 1982, pp. 107–121). Here, we show additionally that the drop experiences no tendency to deform, regardless of the magnitude of the interfacial tension at the interface of the drop and suspending fluid. Next, we consider a non-uniform gradient, where the ambient solute concentration takes the form of a quadrupole around the drop centroid. This gradient does not induce drop translation, due to symmetry, but does induce a deformation in the drop shape, which is spheroidal to first order in the capillary number $Ca=\beta k_B T R^2 K/\gamma$ , where $\beta$ is the magnitude of the quadrupolar variation in solute concentration, $k_B T$ is the thermal energy, $R$ is the drop radius, $K$ is the Gibbs adsorption length, and $\gamma$ is the interfacial tension. Whether the drop becomes prolate or oblate depends on whether the solute–drop interaction is attractive or repulsive. Therefore, our work shows that in principle, a drop could undergo deformation during diffusiophoresis in a non-uniform solute gradient.

Enhancing the microstructure and surface texture of recycled concrete fine aggregate via magnesium-modified carbonation

Investigations on the carbonation of recycled concrete aggregates have been extensively carried out. In this work, recycled concrete fine aggregates (RCFs) were firstly treated with magnesium nitrate solutions of various concentrations and then carbonated. Extensive techniques were employed to characterize the changes of physical properties, pore structures, surface morphologies and phase assemblages of the RCFs after carbonation. Besides, the influences of carbonated RCFs on the hydration, compressive strength and phase assemblages of new cement systems were also evaluated. The results suggested that the magnesium-modified carbonation was more effective than pure carbonation in enhancing the microstructures of RCFs considering the reduction of total pore volume and water absorption. The refinement of microstructure was attributed to the formation of magnesium-calcite, hydromagnesite, etc. as a result of four sequential steps: adsorption of Mg2+ into RCF matrices, precipitation of magnesium hydroxide, enhanced dissolution of Ca2+ and the carbonation of magnesium hydroxide and calcium hydroxide mixes. In addition, the magnesium-modified carbonation was also found to significantly change the morphologies of carbonation products by generating spear-like magnesium-calcite, rosette-like hydromagnesite, plate-like hydrotalcite/mononitrate and spheroidal vaterite. The certain morphological changes of reaction products could promote the formation of an intersected 3D surface texture for RCFs. This particular surface texture could establish a well-connected interface with enhanced interlocking effects when the RCFs were used in new mortars, contributing to the bonding strength and compressive strength enhancement, and the best enhancement was achieved at low Mg2+ dosages (e.g., 0.05 M and 0.1 M).

Comparative Study of Molecular Interaction in Ternary Liquid Mixtures of Polar and Non-Polar Solvents

Ultrasonic velocity measurements, density measurements, and viscometric studies were conducted for the ternary mixture of pyridine and toluene separately with N, N-dimethylformamide (DMF) in butanol, at different temperatures and for different concentrations of component liquids. Using these basic experimental data, various acoustic and thermodynamic parameters, such as adiabatic compressibility (β), free length (Lf,), free volume (Vf), etc. were calculated. Also, Excess thermo-acoustical parameters were calculated from the experimentally measured data. The outcomes were expressed in terms of the molecular interactions and the variations in parameters under varying solute concentrations. A comparative study is discussed. Variation in the above parameters for the different mixtures is indicative of the nature of the interactions between the components in the liquid mixture. Concluding remarks regarding intermolecular interactions are provided.

Substantiation of application technology of hygroscopic materials for dust prevention of roads with the lowest type of surfaces

The article presents the results of experimental study for types of loose soils are easily subject to dusting. In connection with this problem, the task is the study and study of the causes and structure of the formation of dustiness in the roadside zone of roads with common types of coatings or without coatings. The experimental study aims to determine the drying time of chemical dust prevention solutions under the influence of solar radiation and the norm of their distribution. The object of the research is dust generated on roads with low transport and operational performance (temporary roads in places of road repair work, roads to quarries, etc.), and materials used for dedusting road surfaces. The problem to be solved is to reduce the emission of a large amount of dust on roads without pavements or with inferior types of pavements, which adversely affects the human body. The results obtained are the identification of a way to combat dust on road surfaces, ensuring a decrease in wear when vehicles move on roads without pavements. At the same time, the classification of dust according to their sources of formation is expected at the output result. Due to their features and characteristics, these results allowed the author to solve this problem - effective ways to combat dust on road surfaces are: treating them with dust-removing materials that reduce wear; maintaining the original evenness; reduction of air pollution; improvement of traffic conditions for cars and the sanitary and hygienic condition of roads near settlements. For experimental tests, traditional salt solutions of various concentrations (NaCl, MgCl2, CaCl2, MgCl2×6H2O, etc.) and solutions of foreign–made stabilizing additives Durasoil and Soiltac from SOILWORKS were taken.

Elastohydrodynamic Film Formation and Sol/Gel Transition of Aqueous Fluids

One of the most widely used water soluble lubricants is PolyAlkylene Glycol (PAG). PAG aqueous solutions can form a gel depending on the concentration and temperature, which affects the formation and friction of lubricating films. This experimental work combined rheological measurements and in-situ film-forming analysis in pure rolling conditions using PAG aqueous solutions of various concentrations. It shows that the pure PAG behaved classically as a piezoviscous fluid, while its aqueous solutions behaved as isoviscous fluids. This was confirmed by the establishment of a film formation map. In addition, the aqueous solutions exhibited two behaviors, characteristic of either sol or gel. A detailed analysis of the film thickness evolution, based on Moes–Venner’s predictions, allowed us to calculate the effective viscosity in the inlet zone and to discuss the origin of the two families, sol vs gel.Graphical

Effect of two-step annealing on photoelectrochemical properties of hydrothermally prepared Ti-doped Fe2O3 films

Hematite (α-Fe2O3, bandgap ~2.1 eV) is a potential photoanode candidate for photoelectrochemical water splitting. In this work, we report the preparation of Fe2O3 with Ti4+ doping by hydrothermal treatment at 393 K and then annealing in the air at 873 K, with a second round of annealing in argon at 473 K. The two-step annealing process increased the photoelectrochemical performance of Ti-doped Fe2O3 on a fluorine-doped tin oxide (FTO)-coated glass substrate (FTO/Ti-Fe2O3) for water oxidation in 0.1 mol L−1 NaOH solution. Ti4+ doping was sourced from TiCl4 in ethanol solutions of various concentrations. An energy-dispersive X-ray spectrometer (EDS) analysis confirmed that the optimized Ti/Fe atomic ratio in the solution was ~3%, which showed the highest photocurrent densities in the linear sweep voltammetry and chronoamperometry measurements. The two-step annealed FTO/Ti-Fe2O3 generated a photocurrent density of 0.55 mA cm−2 at 1.50 V vs. reversible hydrogen electrode (RHE) under simulated one-sun illumination, which was approximately 3 times higher than that of the photoanodes annealed in air. Four-point probe resistivity measurements revealed that the two-step annealing resulted in a higher electrical conductivity than that of the samples annealed in air. The conductivity improvements induced by additional argon annealing at 473 K were ascribed to the increased donor density, which was confirmed by Mott–Schottky analysis and diffuse reflectance UV–visible–near-infrared spectra. We found that the strategy of Ti4+ doping and two-step annealing helped fabricate Fe2O3-based photoanode materials with better photocurrent density attributed to high electrical conductivity successfully.

Variation in refractive index of sugar solution with concentration using Newton’s rings

Refractive index or index of refraction is an important physiochemical property of an optical medium. Here we report its value for sugar solution of various concentrations (0%, 5%, 10% and 20%) using the Newton’s rings set up for yellow light from sodium lamp (λ=5893Å). Newton’s Rings are an interference pattern generated via division of amplitude principle. The set-up used in our study is easily available in an undergraduate laboratory. The study correctly presents effect of increasing number of particles in a liquid on its refractive index. KEY WORD: Newton’s Rings, refractive index, interference and sugar solution.

Quantitative x-ray fluorescence imaging system for non-destructive 3D tumor histology.

An in-house dual-modality x-ray fluorescence tomography (XFT) and x-ray computed tomography (XCT) system was developed to quantify iodine contrast distribution through the whole tumor volume ex vivo. The quantitative XFT was calibrated with water phantoms containing iodine solutions of various concentrations (0.0175-1.4 wt.%). The vasculature distribution was reflected by the iodine perfusion, which was validated with histology. This technique may open a new, to the best of our knowledge, route to the non-destructive three-dimensional-imaging-based histological analysis of tumor samples.