Size Of Constituent Particles Research Articles

Drawing 3D fluid patterns in beverages using a robotic nozzle

Existing three-dimensional (3D) printing technologies assume the production of solid structures on a platform, regardless of whether they are edible. In contrast, we establish a technology that enables the construction of a 3D structure made of liquid into a liquid matrix, where both liquids are edible as beverages. The blur caused by the diffusion of ink is suppressed by a constituent particle size design without resorting to macroscopic plasticity, whereas sedimentation or floating is prevented by tuning the mass density. Mixing by the drawing motion is suppressed by the design of the robotic nozzle motion, where the dynamic positioning and orientation of the nozzle are controlled alongside the injection flow rate of the edible ink. As a demonstration, we draw a complex 3D structure of a fish in tea within 40 s, and the pattern maintained apparent clarity over several hours.

Fate Determination and Characterization of Food Additive Silicon Dioxide and Titanium Dioxide in Commercial Foods.

Silicon dioxide (SiO2) and titanium dioxide (TiO2) are ones of the most widely used food additives as an anti-caking and a coloring agent, respectively, in the food industry. Understanding particle, aggregate, or ionic fates of two additives in commercial products is of importance to predict their potential toxicity. Triton X-114 (TX-114)-based cloud point extraction (CPE) methods for two additives were optimized in food matrices. Their particle or ionic fates in various commercial foods were determined by the CPE, and the physico-chemical properties of separated particles were further characterized. SiO2 and TiO2 were primarily present as particle forms without changes in constituent particle size, size distribution, and crystalline phase. The maximum solubilities of SiO2 and TiO2 were 5.5% and 0.9%, respectively, depending on food matrix type, supporting their major particle fates in complex food matrices. These findings will provide basic information about the fates and safety aspects of SiO2 and TiO2 additives in commercial processed foods.

Quantifying Agglomerate-to-Wall Impaction in Dry Powder Inhalers.

The probability of agglomerate-to-wall collision was quantified using a unique image processing technique applied to high-speed microscopic images. The study aimed to investigate the effects of flow rate and particle size on the percentage of colliding agglomerates detected within an in-house powder dispersion device. The device consists of a swirl chamber and two tangential inlets in various configurations, designed to emulate the geometric features of commercial devices such as the Aerolizer® and Osmohaler®. The test cases were conducted with constant flow rates of 30 SLPM and 60 SLPM. Four powder samples were tested, including carrier Respitose® SV010 (median volume diameter 104µm, span 1.7) and mannitol of three constituent primary particle sizes (3µm, 5µm and 7µm; span 1.6 - 1.9). At the lower flow rate of 30 SLPM, collision frequencies were significantly different between powders of different constituent particle sizes, but the effects of powder properties diminished on increasing the flow rate to 60 SLPM. At the higher flow rate, all powders experienced a significant increase in the proportion of colliding particles. Analysis of collision events showed that the probability of collision for each agglomerate increased with agglomerate diameter and velocity. Experimental data of agglomerate-to-wall collision were utilised to develop a logistic regression model that can accurately predict collisions with various powders and flow rates.

Displacement Correlations in Disordered Athermal Networks

We derive exact results for correlations in the displacement fields \(\{ \delta \mathbf {r} \} \equiv \{ \delta r_{\mu = x,y} \}\) in near-crystalline athermal systems in two dimensions. We analyze the displacement correlations produced by different types of microscopic disorder, and show that disorder at the microscopic scale gives rise to long-range correlations with a dependence on the system size L given by \(\langle \delta r_{\mu } \delta r_{\nu } \rangle \sim c_{\mu \nu }(r/L,\theta )\). In addition, we show that polydispersity in the constituent particle sizes and random bond disorder give rise to a logarithmic system size scaling, with \(c_{\mu \nu }(\rho ,\theta ) \sim \text {const}_{\mu \nu } - \text {a}_{\mu \nu }(\theta )\log \rho + \text {b}_{\mu \nu }(\theta ) \rho ^{2} \) for \(\rho ~(=r/L) \rightarrow 0\). This scaling is different for the case of displacement correlations produced by random external forces at each vertex of the network, given by \(c^{f}_{\mu \nu }(\rho ,\theta ) \sim \text {const}^{f}_{\mu \nu } -( \text {a}^{f}_{\mu \nu }(\theta ) + \text {b}^{f}_{\mu \nu }(\theta ) \log \rho ) \rho ^2 \). Additionally, we find that correlations produced by polydispersity and the correlations produced by disorder in bond stiffness differ in their symmetry properties. Finally, we also predict the displacement correlations for a model of polydispersed soft disks subject to external pinning forces, that involve two different types of microscopic disorder. We verify our theoretical predictions using numerical simulations of polydispersed soft disks with random spring contacts in two dimensions.

Towards a generic protocol for measuring the constituent particle size distribution of E171 in food by electron microscopy

Food additive E171 (titanium dioxide, TiO 2 ) is authorized to be used as food colorant in the European Union. E171 is a particulate material, containing a fraction of nanoparticles. A major challenge for food control laboratories is the lack of harmonized, validated analytical methods for measuring the physicochemical properties of nanoparticles in food. This study proposes a generic method for the determination of the number-based size distribution of the constituent particles of E171 in food products based on transmission electron microscopy (TEM). As proof of concept, the protocol was evaluated on 20 food products containing E171 and one personal care product containing titanium dioxide. The total titanium concentration in the products measured by inductively coupled plasma - mass spectrometry (ICP-MS) ranged from 0.1 to 4.0 g/kg, corresponding to 0.2–6.7 g TiO 2 /kg. The required initial mass of starting product needed for TEM analysis was estimated from the ICP-MS concentration. Sample preparation included matrix digestion, a first centrifugation step to remove the remaining food matrix, sonication to reduce agglomeration, and a second centrifugation step to concentrate the sample. Descriptive TEM analysis showed that five food products, labelled to contain E171, contained smaller rutile TiO 2 particles (20–40 nm) coated with mica, which are potassium aluminium silicate-based pearlescent pigments. For 14 other food products and the personal care product, the protocol resulted in a homogenous distribution of the TiO 2 particles over the grid surface. In general, variation between products in the number of particles on the grids was limited; on average, 672 ± 173 particles were measured in 10 images. The median of the minimum Feret diameter distribution varied from 72 ± 7 nm to 135 ± 14 nm. The percentage of nanoparticles (minimum Feret diameter smaller than 100 nm) ranged from 23% to 82%. The corresponding mass percentages of these fractions ranged from 3% to 41%. The percentages of E171 particles smaller than 30 nm was very low (3% or less) while corresponding mass fractions were negligible. For only one food product, the TiO 2 concentration was too low to apply the protocol without adaptations. • A generic protocol for particle size measurement of E 171 in food is proposed. • The protocol is designed for transmission electron microscopy. • The protocol was evaluated on 20 food products and one personal care product. • The median Fmin varied from 72 ± 7 nm to 135 ± 14 nm. • The percentage of nanoparticles (<100 nm) ranged from 23% to 82%.

Understanding of the Key Factors Determining the Activity and Selectivity of CuZn Catalysts in Hydrogenolysis of Alkyl Esters to Alcohols

CuZn catalysts are perspective catalysts for esters hydrogenolysis, but more knowledge is needed to optimize their catalytic performance. In this work, we consider the impact of CuZn catalysts composition on their structure, activity, selectivity, and stability in esters hydrogenolysis. Four catalysts with various Cu/Zn ratio were synthesized by a co-precipitation and characterized in as-prepared, calcined, reduced, and spent state by XRF, XRD, N2 physisorption, CO2-TPD, NH3-TPD, and N2O chemisorption. XRD data revealed the effect of the composition on the size of Cu and ZnO particles. The catalytic performance was investigated using an autoclave. All catalysts exhibited high methyl hexanoate conversion about 48–60% after 3 h but their activity and selectivity were found to be dependent on Cu/Zn ratio. The conversion of methyl hexanoate and hexyl hexanoate was compared to explain the observed product selectivity. Moreover, the catalysts stability was investigated in three consecutive reaction cycles and correlated with changes in the size of constituent particles. Moreover, when different esters were tested, a slight decrease in conversion and increase in alcohol selectivity with a growth in molecule size was observed. Obtained results allow making a conclusion about the optimal composition that provides the good performance of CuZn catalysts in ester hydrogenolysis.

Characterization and Determination of Nanoparticles in Commercial Processed Foods.

A wide variety of foods manufactured by nanotechnology are commercially available on the market and labeled as nanoproducts. However, it is challenging to determine the presence of nanoparticles (NPs) in complex food matrices and processed foods. In this study, top-down-approach-produced (TD)-NP products and nanobubble waters (NBWs) were chosen as representative powdered and liquid nanoproducts, respectively. The characterization and determination of NPs in TD-NP products and NBWs were carried out by measuring constituent particle sizes, hydrodynamic diameters, zeta potentials, and surface chemistry. The results show that most NBWs had different characteristics compared with those of conventional sparkling waters, but nanobubbles were unstable during storage. On the other hand, powdered TD-NP products were found to be highly aggregated, and the constituent particle sizes less than 100 nm were remarkably observed after dispersion compared with counterpart conventional bulk-sized products by scanning electron microscopy at low acceleration voltage and cryogenic transmission electron microscopy. The differences in chemical composition and chemical state between TD-NPs and their counterpart conventional bulk products were also found by X-ray photoelectron spectroscopy. These findings will provide basic information about the presence of NPs in nano-labeled products and be useful to understand and predict the potential toxicity of NPs applied to the food industry.

Determination of Two Differently Manufactured Silicon Dioxide Nanoparticles by Cloud Point Extraction Approach in Intestinal Cells, Intestinal Barriers and Tissues.

Food additive amorphous silicon dioxide (SiO2) particles are manufactured by two different methods—precipitated and fumed procedures—which can induce different physicochemical properties and biological fates. In this study, precipitated and fumed SiO2 particles were characterized in terms of constituent particle size, hydrodynamic diameter, zeta potential, surface area, and solubility. Their fates in intestinal cells, intestinal barriers, and tissues after oral administration in rats were determined by optimizing Triton X-114-based cloud point extraction (CPE). The results demonstrate that the constituent particle sizes of precipitated and fumed SiO2 particles were similar, but their aggregate states differed from biofluid types, which also affect dissolution properties. Significantly higher cellular uptake, intestinal transport amount, and tissue accumulation of precipitated SiO2 than of fumed SiO2 was found. The intracellular fates of both types of particles in intestinal cells were primarily particle forms, but slowly decomposed into ions during intestinal transport and after distribution in the liver, and completely dissolved in the bloodstream and kidneys. These findings will provide crucial information for understanding and predicting the potential toxicity of food additive SiO2 after oral intake.

Effect of constituent particle polydispersion on VSSA-based equivalent particle diameter: Theoretical rationale and application to a set of eight powders with constituent particle median diameters ranging from 9 to 130 nm

Volume Specific Surface-Area (VSSA) has been identified as a relevant and alternative method to electron microscopy (EM) to determine whether a material is or not a nanomaterial. VSSA is an integral measurement method that provides an indirect representation of particle size. When this conversion into particle diameter is carried out, constituent particles are supposed to be monodisperse, which can be considered far from reality, materials being composed of polydisperse constituent particles. The way particle polydispersion affects the VSSA of a material, and thus the equivalent particle diameter deduced, is investigated in this paper. In particular, the specific case of normally-distributed, spherical constituent particles, is considered. A theoretical study has led to the introduction of a correction polydispersion-based factor. From experimental VSSA data obtained for eight powders covering a range of constituent particle median diameters from 9 to 130 nm, the VSSA-based constituent particle median diameters were compared to the median constituent particle size obtained from electron microscopy analysis, considered as the reference method. Integrating constituent particle polydispersion through the use of the correction factor improves the accuracy of particle size stemming from the VSSA approach, the relative discrepancies being within ±20% from the reference diameter.

Fragmentation dynamics of single agglomerate-to-wall impaction

The de-agglomeration characteristics of single agglomerate-wall impaction are examined using high-resolution shadowgraph imaging. Experiments are performed to investigate the effects of constituent particle size (D50 from 3 to 7 μm) and air velocity on the individual size and velocity of de-agglomerated fragments at conditions relevant to dry powder inhalation systems. De-agglomerated fragment area and trajectories were used to differentiate between pseudo-elastic and inelastic collisions during de-agglomeration. Advanced image processing techniques have enabled provision of joint population distributions of fragment area and aspect ratio, which identify a bimodal dispersion of fragments during de-agglomeration. The bimodality is destroyed with increasing air velocity and also generally diminishes with time after impact. The experiment presented forms a platform for the detailed quantitative characterisation of de-agglomeration behaviour and can be useful towards the development and validation of related computational models for pharmaceutical dry powder inhalers.

Challenges in sample preparation for measuring nanoparticles size by scanning electron microscopy from suspensions, powder form and complex media

Commercial products containing nanomaterials are already a part of our everyday life. The dimensional parameters play an important role for identifying nanoparticles. Various techniques are available for measuring the particles size and shape. However, electron microscopy-based techniques are often considered as the preferred methods for characterizing their dimensional properties. Samples preparations remain a key step but no standardized protocol is currently available. Scanning electron microscopy measurements require well-dispersed particle population corresponding to a statistically representative sample. This work presents a new approach, to prepare samples based on spincoating technique in order to measure in a reliable manner the constituent particle size. This method consists of three key processing steps: (i) extraction from complex media, (ii) redispersion by means of probe sonication and (iii) deposition by spincoating. The approach combines several factors such as pH, zeta potential, duration, concentration, sonication and spin coater parameters, that can influence agglomeration state of nanoparticles.

Cobalt and molybdenum co-doped Ca2Fe2O5 cathode for solid oxide fuel cell

Recently, Brownmillerite oxides Ca2Fe2-xMxO5 (0 ≤ x ≤ 0.2) (M = transition metal such as Co, Mo), have been drawing attention as they possess mixed ionic and electronic conductivity. Fe site of parent Ca2Fe2O5 (CFO) structure is partially substituted by Co and/or Mo as well as CoMo co-doping and tested as cathodes in SOFC. Physical characterizations such as X-ray diffraction (XRD), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscope (TEM), and Brunauer–Emmett–Teller (BET) have been carried out to assess the phase formation, microstructure, presence of constituent elements, particle size, and surface area of the cathode, respectively. The Co doped CFO cathodes have better percolation, large surface area, and extended triple phase boundary. Further, the doped CFO cathodes exhibited chemical compatibility with other cell components during fabrication and cell testing as evident from SEM micrographs. The Ca2Fe2-xMxO5 (0 ≤ x ≤ 0.2) oxides show a semiconductor behaviour having sufficient electrical conductivity values in the SOFCs operating temperature 600–800 °C range. The best electrical conductivity, 0.47 S/cm at 800 °C and the corresponding activation energy of 0.17 eV is exhibited by Ca2Fe1.8Co0.2O5 (CFCO), whereas Ca2Fe1.8Mo0.2O5 (CFMO) and Ca2Fe1.8Mo0.1Co0.1O5 (CFMCO) cathode shows electrical conductivity 0.11 S/cm and 0.15 S/cm at 800 °C, respectively. CFMO performed better with SDC than YSZ electrolyte between 600 and 700 °C although the lowest area specific resistance (ASR) of 1.28 Ω cm2 at 800 °C is observed for CFMO with YSZ electrolyte. Similarly, CFMCO provided low ASR at lower temperature with SDC than that with YSZ electrolyte but exhibited lowest ASR of 0.41 Ω cm2 at 800 °C with YSZ. The CFCO cathode shows lower ASR with YSZ than that with SDC for all the temperature and provided lowest value of ASR 0.21 Ω cm2 at 800 °C. CFCO cathode has been tested in 900 μm thick electrolyte (SDC/YSZ) supported solid oxide fuel cell (SOFC) CFCO-SDC/SDC/NiO-SDC and CFCO-YSZ/YSZ/NiO-YSZ provided maximum power densities of 171 and 506 mW/cm2 (i-R corrected) at 800 °C, respectively.

Kajian Karakteristik Kimia dan Fisika Abu Layang yang Menjadi Penentu Kekuatan Mekanik Perekat Geopolimer Berbahan Dasar Abu Layang

Conversion of fly ash into geopolymers is one of the right ways to reduce the problem of coal ash waste which is hazardous and poisonous waste while its production continues to increase every year. In this study, fly ash from Pacitan power plant, Semen Gresik, Petrokimia Gresik, and Australia were used as the raw materials for making geopolymers. The geopolymers were made based on previous research. Geopolymer compressive strength that was measured at 7 days after curing was 46.71; 42.6; 42.6; 9.55 MPa, respectively. Analyses of phase composition and crystallinity, morphology and particle size and composition of fly ash constituents showed that the factor that had the strongest influence in this study was the size of fly ash particles. Fly ash with the largest particle size produces geopolymers with the lowest compressive strength. High calcium content produces a short setting time and all geopolymers that have high compressive strength are made from fly ash with a high content of Fe 2 O 3

Enhanced thermoelectric properties of flexible aerosol-jet printed carbon nanotube-based nanocomposites

Aerosol-jet printing allows functional materials to be printed from inks with a wide range of viscosities and constituent particle sizes onto various substrates, including the printing of organic thermoelectric materials on flexible substrates for low-grade thermal energy harvesting. However, these materials typically suffer from relatively poor thermoelectric performance, compared to traditional inorganic counterparts, due to their low Seebeck coefficient, S, and electrical conductivity, σ. Here, we demonstrate a modified aerosol-jet printing technique that can simultaneously incorporate well-dispersed high-S Sb2Te3 nanoflakes and high-σ multi-walled carbon nanotubes (MWCNTs) providing good inter-particle connectivity to significantly enhance the thermoelectric performance of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate structures on flexible polyimide substrates. A nominal loading fraction of 85 wt. % yielded a power factor of ∼41 μW/mK2, which is among the highest for printed organic-based structures. Rigorous flexing and fatigue tests were performed to confirm the robustness and stability of these aerosol-jet printed MWCNT-based thermoelectric nanocomposites.

On the corrosion of additively manufactured aluminium alloy AA2024 prepared by selective laser melting

The microstructure, and electrochemical properties of additively manufactured Al-alloy AA2024 (AM2024, Al-Cu-Mg) produced by selective laser melting are reported. In-depth microstructural characterisation was conducted to compare the resultant microstructure, including phase identification, size and distribution, against the wrought counterpart AA2024-T3. The prospect of producing net shape Al-alloys via additive manufacturing (AM) has the potential to provide cost effective and high specific strength components. It was revealed that the dominant second phase formed in AM2024 was Al2Cu (θ–phase), in contrast to the typical Al2CuMg (S-phase) observed in AA2024-T3. The AM2024 also revealed a refined microstructure, with an average constituent particle size < 1 μm. Thermodynamic calculations revealed that the preferential formation of θ-phase was influenced by the Si content of AM2024 (0.78 wt. %). Atomic emission spectroelectrochemistry (AESEC) measurements revealed a lower Al dissolution rate (5 times) in the case of AM2024. Anodic polarisation revealed that AM2024 was capable of forming an appreciable surface oxide relative to AA2024-T3. The findings herein demonstrate the possibilities of AM as applied to a high strength Al-alloy.

Predicting the behavior of unbound granular materials under repeated loads based on the compact shakedown state

Abstract The behavior of unbound granular material under repeated loads primarily depends on the nature and arrangement of constituent particles, particle size and shape. However, very few analytical models are available for predicting the behavior of unbound granular material under repeated loads. This paper presents a generalized failure criterion with a non-associated flow rule which uses from the concept of compact shakedown state for predicting the stress–strain behavior of unbound granular material. At the compact shakedown state, the response of the unbound granular sample to a stress change is reversible and behaves as an elastic material. In an extension to original CANAsand constitutive model, two concepts namely critical state and compact shakedown state play paramount roles as all of the moduli and coefficients are related to these states. In contrast to the critical state, the unbound granular material samples do not experience any plastic deformation at the compact shakedown state and behaves as a purely elastic material and the response to a stress change is reversible. For stress reversal two additional concepts as reflected plastic potential and bounding surface are employed which distinguishes between virgin loading and secondary loading. The extended model is examined by simulating different typical drained tests in conventional tri-axial tests. The applicability of the present model is evaluated through comparisons between the predicted and the measured results.

Aggregation in particle rich environments: a textural study of examples from volcanic eruptions, meteorite impacts, and fluidized bed processing

Aggregation is a common process occurring in many diverse particulate gas mixtures (e.g. those derived from explosive volcanic eruptions, meteorite impact events, and fluid bed processing). It results from the collision and sticking of particles suspended in turbulent gas/air. To date, there is no generalized model of the underlying physical processes. Here, we investigate aggregates from 18 natural deposits (16 volcanic deposits and two meteorite impact deposits) as well as aggregates produced experimentally via fluidized bed techniques. All aggregates were analyzed for their size, internal structuring, and constituent particle size distribution. Commonalities and differences between the aggregate types are then used to infer salient features of the aggregation process. Average core to rim ratios of internally structured aggregates (accretionary lapilli) is found to be similar for artificial and volcanic aggregates but up to an order of magnitude different than impact-related aggregates. Rim structures of artificial and volcanic aggregates appear to be physically similar (single, sub-spherical, regularly-shaped rims) whereas impact-related aggregates more often show multiple or irregularly shaped rims. The particle size distributions (PSDs) of all three aggregate types are similar (< 200 μm). This proves that in all three environments, aggregation occurs under broadly similar conditions despite the significant differences in source conditions (particle volume fraction, particle size distribution, particle composition, temperature), residence times, plume conditions (e.g., humidity and temperature), and dynamics of fallout and deposition. Impact-generated and volcanic aggregates share many similarities, and in some cases may be indistinguishable without their stratigraphic context.

Effect of He+ fluence on surface morphology and ion-irradiation induced defect evolution in 7075 aluminum alloys

The evolution of microstructure for 7075 aluminum alloys with 50 Kev helium ions irradiation were studied by using optical microscopy (OM), scanning electron microscopy (SEM), x-ray diffraction (XRD) and transmission electron microscopy (TEM). The fluences of 1 × 1015, 1 × 1016 and 1 × 1017 ions cm−2 were selected, and irradiation experiments were conducted at room temperatures. The transmission process of He+ ions was simulated by using SRIM software, including distribution of ion ranges, energy losses and atomic displacements. Experimental results show that irradiated pits and micro-cracks were observed on irradiation sample surface, and the size of constituent particles (not including Mg2Si) decreased with the increasing dose. The x-ray diffraction results of the pair of peaks is better resolved in irradiated samples might indicate that the stressed structure consequence due to crystal defects (vacancies and interstitials) after He+ implantation. TEM observation indicated that the density of MgZn2 phase was significantly reduced after helium ion irradiation which is harmful to strength. Besides, the development of compressive stress produced a large amount of dislocation defects in the 1015 ions cm−2 sample. Moreover, higher fluence irradiation produced more dislocations in sample. At fluence of 1016 ions cm−2, dislocation wall formed by dislocation slip and aggregation in the interior of grains, leading to the refinement of these grains. As fluence increased to 1017 ions cm−2, dislocation loops were observed in pinned dislocation. Moreover, dislocation as effective defect sink, irradiation-induced vacancy defects aggregated to these sinks, and resulted in the formation of helium bubbles in dislocation.

Pharmaceutico-analytical Study of Kushtae Shangarf Prepared with Jozbua (Myristica fragrans Houtt.) and Phitkari (Alum).

Introduction:Kushta of Shangarf (KS) is in therapeutic use since long time in Unani and Ayurvedic medicine. It requires extensive assessment with respect to its safety and processing because of the presence of mercury. KS prepared with Shangarf (HgS), Phitkari (alum), and Jozbua (Myristica fragrans Houtt.) was selected for the study. It is indicated as tonic, increases blood production, and improves complexion of face. Preparation of KS by classical and contemporary method and its comparative physicochemical analysis was attempted in this work.Materials and Methods:Kushta was prepared by incinerating the drugs kept inside Buta in Bhatti with 24kg of Uple (cow-dung cakes) and also in muffle furnace. Samples obtained were evaluated by Unani specifications (test), powder characterizations, loss on drying, pH, ash value, solubility, particle size, and qualitative estimation of organic and inorganic constituents, X-ray diffraction (XRD), quantitative estimation by inductively coupled plasma–mass spectrometry and inductively coupled plasma–optical emission spectrometry, and so on.Results:Physicochemical standards set in were comparable in KS prepared by classical method (KSCM) and in KS prepared by muffle furnace method (KSMFM), except water-soluble ash and solubility in water were found slightly more in KSMFM. XRD study revealed the presence of aluminum oxide phase and absence of mercury in both the samples. Quantitative estimation of elements in both the samples in decreasing order are as follows: sulfur > aluminum > calcium > iron > arsenic. Arsenic was found more than iron in KSCM at parts per million level.Conclusion:Preliminary understanding suggests that muffle furnace method could be a better option with respect to safety and ease of preparation. Shangarf incinerated above 900°C with Phitkari and Jaiphal did not show presence of mercury in both the samples, indicating KS prepared by incinerating at higher temperature can be safer than unroasted preparation. Studied formulation can be recommended or used for its indications without the concern of mercury toxicity.

Tailoring the optical properties of poly(diallyl dimethyl ammonium chloride) polyelectrolyte by incorporation of 2-mercaptoethanol capped CdSe nanoparticles

The present work deals with the preparation and characterization of 2-mercaptoethanol capped cadmium selenide (CdSe) nanoparticles, dispersed in poly(diallyl dimethyl ammonium chloride) (PDADMAC) polyelectrolyte aqueous solution. X-ray diffraction spectra, scanning electron microscopy and energy-dispersive x-ray have been used to determine the structure, particle size (d), surface morphology and composition of various constituents. The absorption spectra of pure PDADMAC and the CdSe/PDADMAC polymer nanocomposite (PNC) are analyzed to determine the values of the absorption coefficient (α) and energy band gap (Eg) which are found to be 4 eV and 3.26 eV respectively. A red shift in the spectrum of the PNC, as compared to the pure polymer, has been observed. With the addition of CdSe nanoparticles in the PDADMAC polyelectrolyte, a remarkable change in the optical parameters of the pure polymer has been observed. The refractive index (n) obtained by using Swanepoel’s method decreases in the case of the PNC as compared to the pure polymer. The value of the static refractive index (n0) is found to be 4.29 for the pure polymer and 1.52 for the PNC. The extinction coefficient, dielectric constants, optical conductivity and relaxation time have been evaluated. The Wemple–DiDomenico model has been used to evaluate the dispersion parameters such as the average energy gap (E0) and dispersion energy (Ed). The values of the nonlinear refractive index (n2) of the pure polymer and PNC have been determined using the theoretical approaches suggested by Boling and Tichy and Ticha. n2 increases in the case of PNC, which relates to the decreased energy band gap. Photoluminescence (PL) spectra have been studied to explore the energy band structure and interaction between CdSe nanoparticles and PDADMAC. The PL peaks obtained at 437 nm and 461 nm correspond to the pure polymer whereas the peak at 577 nm is attributed to CdSe.