Malvern Instruments Research Articles

Thermal properties of some Egyptian kaolin pastes for pelotherapeutic applications: Influence of particle geometry on thermal dosage release

Abstract The present study aims to evaluate the potentiality of 7 selected structural highly ordered kaolinite-rich samples from Egyptian Carboniferous sedimentary deposits (located at Abu Zenima district, west central Sinai peninsula) to use them in medicinal semisolid formulations as peloids. The effect of particle geometry and kaolinite crystallite size are studied to check their influence on thermal dosage performance. The studied samples exhibit a variable mineralogy. Kaolinite is the main constituent (ranging from 81 to 94%), followed by quartz (up to 14%), lesser amounts of anatase and halite, and traces of hematite, magnetite, alunite and gypsum. The kaolinite order “Hinckley Index” varies from 1.28 to 1.50. 1:1 (w/w) kaolin mud pastes were prepared with purified water in Eppendorf tubes using a touch vibration vortex mixer for 2 min. The cooling kinetics of pastes were measured by using a differential scanning calorimetry equipment (Shimadzu DSC-50Q). Specific heats were calculated, following Cara et al. (2000). The granulometry and geometric surface area were measured by laser diffraction (Mastersizer 2000LF, Malvern Instruments) in the range 0.02 and 1500 μm. All analyzed samples showed a clear predominance of particles under 4 μm (ranging from 82 to 94%), with median size (D50) ranging from 0.93 to 1.35 μm. The heat retention time during cooling from 50 °C to 32 °C reached up to 30.82 min, oscillating around an average of 28.72 min, and the temperature corresponding to the minimal dosage time (T20) was not exceed below 34.7 °C. A good correlation (R2 = 0.875) was found between heat retention time and specific heats. There is no correlation between kaolinite content and thermal properties, but R2 values around 0.6 are found with granulometry (finer the particles, greater the heat retention time t32 and the specific heat). Even if sample H5 (Gabal Hazbar deposit) is not the richest in kaolinite, it exhibits the best thermal dosage performance, in accordance with the granulometry (D50 = 0.93 μm), and geometric surface area (3.73 m2/g).

Soil Particle Size Analysis by Laser Diffractometry: Result Comparison with Pipette Method

Soil texture as the basic soil physical property provides a basic information on the soil grain size distribution as well as grain size fraction representation. Currently, there are several methods of particle dimension measurement available that are based on different physical principles. Pipette method based on the different sedimentation velocity of particles with different diameter is considered to be one of the standard methods of individual grain size fraction distribution determination. Following the technical advancement, optical methods such as laser diffraction can be also used nowadays for grain size distribution determination in the soil. According to the literature review of domestic as well as international sources related to this topic, it is obvious that the results obtained by laser diffractometry do not correspond with the results obtained by pipette method. The main aim of this paper was to analyse 132 samples of medium fine soil, taken from the Nitra River catchment in Slovakia, from depths of 15-20 cm and 40-45 cm, respectively, using laser analysers: ANALYSETTE 22 MicroTec plus (Fritsch GmbH) and Mastersizer 2000 (Malvern Instruments Ltd). The results obtained by laser diffractometry were compared with pipette method and the regression relationships using linear, exponential, power and polynomial trend were derived. Regressions with the three highest regression coefficients (R2) were further investigated. The fit with the highest tightness was observed for the polynomial regression. In view of the results obtained, we recommend using the estimate of the representation of the clay fraction (<0.01 mm) polynomial regression, to achieve a highest confidence value R2 at the depths of 15-20 cm 0.72 (Analysette 22 MicroTec plus) and 0.95 (Mastersizer 2000), from a depth of 40-45 cm 0.90 (Analysette 22 MicroTec plus) and 0.96 (Mastersizer 2000). Since the percentage representation of clayey particles (2nd fraction according to the methodology of Complex Soil Survey done in Slovakia) in soil is the determinant for soil type specification, we recommend using the derived relationships in soil science when the soil texture analysis is done according to laser diffractometry. The advantages of laser diffraction method comprise the short analysis time, usage of small sample amount, application for the various grain size fraction and soil type classification systems, and a wide range of determined fractions. Therefore, it is necessary to focus on this issue further to address the needs of soil science research and attempt to replace the standard pipette method with more progressive laser diffraction method.

A facile solvothermal method for high-quality Gd2Zr2O7 nanopowder preparation

A facile solvothermal method has been developed to synthesize Gd2Zr2O7 nanopowders with well-controlled particle size and dispersion. The nanopowders were consolidated into dense ceramic pellets by pressureless sintering, and effects of the solvothermal method in microstructure control are demonstrated by comparison with conventional precipitation approach. X-ray diffraction, electron microscopy, gas adsorption, and a standard operating procedure (SOP) in Malvern Instruments were employed to investigate crystallite/grain sizes and structural morphology evolutions of nanopowders and ceramics. Well-crystallized Gd2Zr2O7 nanopowders with little agglomeration and narrow size distribution synthesized by this method have an average crystallite size of 3.5nm and high surface area of 162m2/g. This method also allows the formation of homogeneous and dense Gd2Zr2O7 ceramic with bulk density over 94% of the theoretical value achieved after sintering at 1500°C for 6h.

Automated counting of sand‐sized particles in marine records

AbstractContent and fluxes of ice‐transported sand‐sized and gravel‐sized, lithic particles in marine sediment cores are a common tool used to reconstruct glacial variability. Ice‐rafted debris data sets are currently acquired in several different and often time‐consuming ways, and within various grain‐size fractions. This article proposes a novel workflow using an automated method to count ice‐rafted debris to reduce analysis time and subjectivity. The described method is based on the instrument ‘Morphologi G3’ from Malvern Instruments Limited and includes all pre‐processing and post‐processing steps. This particle characterization tool is an automated microscope combined with a proprietary software package. In this study, the analysis was performed on the 150 to 1000 μm fraction. If desired, grain counts can be carried out on the entire sand and silt fractions. However, this would result in a considerably greater turnover time. A total of 350 sediment samples from core MD99‐2283, taken on the upper continental slope at the southern part of the north‐east Atlantic margin, were counted with this automated method. In addition, a total of 161 samples were counted manually as a control on the reliability of the scanning. The comparison of automated versus manually counted biogenic and lithic material shows a convincing correlation between the two methods. The turnover time per automatically counted sample is around 20 min, the method requiring less experience and skills than manual counting. The results yield a promising, time‐saving new technique to achieve high‐resolution ice‐rafted debris counting records with acceptable error margins.

Microstructural and dynamic oscillatory aspects of yogurt as influenced by hydrolysed guar gum

SummaryThe objective of the current study was to explore the influence of crude, purified and hydrolysed guar gum at low and high concentrations on gel structure stability of yogurts at 4 °C throughout 21 days of storage. The rheology and microstructure of yogurts had been perceived by Bohlin rheometer (Malvern Instrument, UK) and cryo‐scanning electron microscopy (Cryo‐SEM), respectively. The viscoelastic behaviour of yogurts characterised at 25 °C exhibited weak gel structural properties (Gʺ &gt; Gʹ). Cryo‐SEM had been used for microstructural image processing. The acidic and enzyme hydrolysed guar gum at low (0.3%) and high (1%) concentrations led to yogurt gels with fine‐stranded microstructure, while gelation with crude, purified and basic hydrolysed guar gum demonstrated diverse behaviour of depletion flocculation, visually observed even at low concentrations of crude guar gum (0.1%) as a thin layer of phase‐separated material. Conclusively, guar gum in its hydrolytic form enhances better structural and rheological properties.

ESPECTRO DAS GOTAS PRODUZIDAS POR PONTAS DE JATO PLANO DUPLO DEFASADO COM INDUÇÃO DE AR

Os fabricantes de pontas de pulverização constantemente disponibilizam novos modelos no mercado na tentativa de aumentar a eficiência das aplicações, entretanto muitas vezes seu comportamento é desconhecido em relação ao espectro das gotas produzidas. Sendo assim, este trabalho foi conduzido com o objetivo de avaliar o espectro de gotas proporcionado pelas pontas AI3070-015VP e AI3070-02VP. Estas apresentam dois jorros de pulverização defasados em relação à vertical (30 e 70°), ambos com indução de ar. Na análise do espectro, utilizou-se um analisador de partículas a laser (Spraytec, Malvern Instruments Co.) dotado de lente focal de 750 mm. Construiu-se um sistema para analisar individualmente os jorros produzidos pelas pontas. Realizaram-se as análises dos parâmetros técnicos da pulverização (DV0,1, DV0,5, DV0,9, Índice Span, %V &lt; 100 μm e %V &gt; 650 μm) empregando-se quatro pressões de trabalho (200, 300, 400 e 500 kPa). O experimento foi conduzido em delineamento inteiramente ao acaso, em esquema fatorial (2 x 2 x 4), sendo dois modelos de pontas hidráulicas dois leques e quatro pressões de trabalho. Para a ponta AI3070-015VP o jorro produzido com ângulo de 70° produziu gotas com maior diâmetro da mediana volumétrica (DMV) em relação ao de 30° ao passo que, para a ponta AI3070-02VP, o comportamento foi o inverso. As pontas testadas apresentaram gotas com baixo potencial de deriva, com %V

Effect of geometric parameters on spray characteristics of pressure swirl atomizers

Experimental study on the effects of the geometric ratios of pressure swirl atomizers on the spray characteristics such as spray cone angle and SMD has been conducted. Twelve atomizers of different geometric configurations have been used for this purpose. The atomizers have been divided into three groups, each containing four nozzles, based on the variation in three geometric ratios i.e. Ds/Do, Lo/Do and Ls/Ds.These ratios have been varied from 3 to 7.5, 0.81 to 2.69 and 1.25 to 5.0 respectively for the examination of their influence on the spray cone angle and SMD. Spray cone angle was measured through high speed camera while SMD was measured by using Malvern instruments. The experiments were performed at two injection pressures of 0.8 MPa and 1.2 MPa by using water as the test liquid. The results show that the spray cone angle continuously decreases with the increase in ratio Ds/Do, however, an optimal value 3.75 of this ratio has been recognized during the measurements of SMD. Furthermore, SMD has been observed to continuously increase with the increase in Lo/Do, while an optimal value 1.44 of this ratio has been identified during the measurements of spray cone angle. Similarly, an optimal value 3.75 of the ratio Ls/Ds has also been determined from the experimental measurements of spray cone angles and SMD.

Variability of suspended sediment grain size distribution in winter floods

Abstract Variability of suspended sediment grain size distribution in winter floods. The work presents the results of research concern variability of suspended sediment grain size, transported during the winter floods in agricultural catchment, in the period of hydrological years 2012-2015. The information about grain size distribution from nine winter flood events were collected over the study period, which allowed to analyze the variability of suspended sediment particle size during the various events. Grain size of sediment was determined using a laser particle size analyzer Mastersizer Microplus from Malvern Instruments Ltd. Variability of individual particle size classes were observed in each flood. Sand fraction dominated in seven of nine measured events. There was no significant increase of suspended sediment size in relation to the maximum of discharge. It can be explain by a relatively low discharge of recorded events. The percentage of material classified as clay (&lt;4 μm) ranged from 0.08 to 1.01%, silt-sized material (&gt;4 and &lt;63 μm) ranged between 9.31 and 67.17% and sand-size material (&gt;63 μm) ranged from 32.01 to 90.61%. The relationship between the particle size and the discharge requires further studies. The diameter d10, d50 and d90 and a standard deviation were calculated for each flood. Mean values of d50 for individual flood ranged between 41.05 and 191.32 μm with average value of 99.01 μm and average standard deviation of 32.57.

Modulation of the Kinetic Stability of Immunoglobulin G by Solvent Additives

Stability of Immunoglobulin G (IgG) is a crucial parameter that affects important aspects of this multidomain protein such as its production, storage and usability. The complex thermal and isothermal transitions of IgGs as well as their irreversibilities pose a significant challenge to the proper determination of parameters describing the stability of IgGs. Here, we have examined the effects of additives on the kinetic stability of IgGs by differential scanning calorimetry (DSC). The thermal denaturation of full-length IgGs was examined by three-step model, simulating the observed three consecutive transitions (one reversible, two irreversible), while the kinetic stability of the corresponding Fab fragments was analyzed according to the Lumry-Eyring model specifying a single irreversible transition. Ten additives were analyzed: polyols (sorbitol, sucrose and trehalose), salts (sodium perchlorate, chloride and sulfate, including arginine) and methylamines (betaine, sarcosine and trimethylamine oxide). Osmolytes (polyols and methylamines) and salts were found to affect the stability of IgGs differently as seen both in different DSC profiles and in the diverse effects of the additives on parameters characterizing the irreversible step. Our findings highlight the influence of both the additives as well as stabilizing mutations in the Fab fragment on the kinetic stability of the whole IgG. These conclusions could only be reached through proper analyses of thermal denaturations of IgGs using the appropriate model simulating their irreversible thermal transitions, and may help in the development of more predictive strategies for formulation development. Acknowledgements The authors thank Dr. Yuguang Zhao (Wellcome Trust Centre for Human Genetics, Oxford University) for his help in IgG expression and Dr. Peter Gimeson (Malvern Instruments, Uppsala, Sweden) for his help in performing DSC experiments. This work was supported by grants from CELIM (316310) funded by 7FP EU Programs REGPOT and PCUBE.

The In-Situ One-Step Synthesis of a PDC Macromolecular Pro-Drug and the Fabrication of a Novel Core-Shell Micell.

The development of slow release nano-sized carriers for efficient antineoplastic drug delivery with a biocompatible and biodegradable pectin-based macromolecular pro-drug for tumor therapy has been reported in this study. Pectin-doxorubicin conjugates (PDC), a macromolecular pro-drug, were prepared via an amide condensation reaction, and a novel amphiphilic core-shell micell based on a PDC macromolecular pro-drug (PDC-M) was self-assembled in situ, with pectin as the hydrophilic shell and doxorubicin (DOX) as the hydrophobic core. Then the chemical structure of the PDC macromolecular pro-drug was identified by both Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy ((1)H-NMR), and proved that doxorubicin combined well with the pectin and formed macromolecular pro-drug. The PDC-M were observed to have an unregularly spherical shape and were uniform in size by scanning electron microscopy (SEM). The average particle size of PDC-M, further measured by a Zetasizer nanoparticle analyzer (Nano ZS, Malvern Instruments), was about 140 nm. The encapsulation efficiency and drug loading were 57.82% ± 3.7% (n = 3) and 23.852% ±2.3% (n = 3), respectively. The in vitro drug release behaviors of the resulting PDC-M were studied in a simulated tumor environment (pH 5.0), blood (pH 7.4) and a lysosome media (pH 6.8), and showed a prolonged slow release profile. Assays for antiproliferative effects and flow cytometry of the resulting PDC-M in HepG2 cell lines demonstrated greater properties of delayed and slow release as compared to free DOX. A cell viability study against endothelial cells further revealed that the resulting PDC-M possesses excellent cell compatibilities and low cytotoxicities in comparison with that of the free DOX. Hemolysis activity was investigated in rabbits, and the results also demonstrated that the PDC-M has greater compatibility in comparison with free DOX. This shows that the resulting PDC-M can ameliorate the hydrophobicity of free DOX. This work proposes a novel strategy for in-situ one-step synthesis of macromolecular pro-drugs and fabrication of a core-shell micelle, demonstrating great potential for cancer chemotherapy.

Deposition of intranasal glucocorticoids--preliminary study.

Intranasal glucocorticoids are the treatment of choice in the therapy of rhinitis. The differences in efficiency of particular medications proven by therapeutic index may result from differences in composition of particular formulations as well as from diverse deposition in nasal cavities. Intranasal formulations of glucocorticoids differ in volume of a single dose in addition to variety in density, viscosity and dispenser nozzle structure. The aim of this report was to analyze the deposition of most often used intranasal glucocorticoids in the nasal cavity and assessment of the usefulness of a nose model from a 3D printer reflecting anatomical features of a concrete patient. Three newest and most often used in Poland intranasal glucocorticoids were chosen to analysis; mometasone furoate (MF), fluticasone propionate (FP) and fluticasone furoate (FF). Droplet size distribution obtained from the tested formulations was determined by use of a laser aerosol spectrometer Spraytec (Malvern Instruments, UK). The model of the nasal cavity was obtained using a 3D printer. The printout was based upon a tridimensional reconstruction of nasal cavity created on the basis of digital processing of computed tomography of paranasal sinuses. The deposition of examined medications was established by a method of visualization combined with image analysis using commercial substance which colored itself intensively under the influence of water being the dominant ingredient of all tested preparations. On the basis of obtained results regions of dominating deposition of droplets of intranasal medication on the wall and septum of the nasal cavity were compared. Droplet size of aerosol of tested intranasal medications typically lies within the range of 25-150 µm. All tested medications deposited mainly on the anterior part of inferior turbinate. FP preparation deposited also on the anterior part of the middle nasal turbinate, marginally embracing a fragment of the central part of this turbinate as well together with deposition in the middle and superior nasal meatus reaching the region of nasal ceiling and olfactory field. MF preparation deposited on the anterior part of the inferior turbinate and central part of this turbinate alike. The area of mucous membrane of lateral wall of nasal cavity on which MF deposited was similar to the area achieved after the application of FP preparation but much greater than in the case of FF preparation. FF drug deposition concentrates only on the anterior part of the inferior turbinate. Despite directing the drug to the lateral wall of the nasal cavity a great proportion of examined preparations deposit also on the nasal septum. The practical application of tridimensional representation (3D printout) of actual geometry of nasal cavity to establish the deposition of inGKS was proven. Droplet size and the geometry of the aerosol cloud introduced into the nostril determine the significant deposition of medication droplets in the anterior part of the nasal cavity. Both physical properties of the drug as well as spraying system applied influence spatial distribution of the drug. The interaction of the air flow with the layer of deposited fluid plays a major role in the deposition of the drug in the nasal cavity, therefore it is so important that the drug does not drain by gravity but remains at the site of deposition which may be reinforced by thixotropic properties of the preparation.

Optimization of Process Parameters for Development of Camptothecin Loaded Poly (Methacylic Acid-Co-Methyl Methyacrylate) Nanoparticles Using Plackett-Burman Factorial Design Methodology

Objective: The aim of the present study was to develop Camptothecin loaded poly (methacylic acid-co-methyl methyacrylate) nanoparticles and to optimize the process parameters for the preparation of polymeric nanoparticles using Plackett-Burman factorial design. The relationship between design factor and experimental data was evaluated. Method: In this study, Camptothecin loaded poly (methacylic acid-co-methyl methyacrylate) nanoparticles were prepared by nanoprecipitation method. The prepared nanoparticles were optimized using Plackett-Burman method. Critical formulation variables were optimized in this study in terms of their corresponding effects on the preparation of nanoparticles. The characterization of the optimized nanoformulations with respect to particle size distribution, particle morphology were carried out using malvern instrument and transmission electron microscope (TEM). Results: Factorial design results have shown that (a) Except, β-cyclodextrin concentration, poloxamer concentration and the process all other parameters significantly influenced the average particle size; (b) Except, stirring time, stirring speed and stirring mode all other process parameters significantly influence the particle size uniformity; (c) Except, volume of organic phase and stirring speed all other process parameters significantly influence the surface area. Conclusion: The average particle size, particle size uniformity and surface area of the optimized formulation were found to be 99.29 nm, 0.242 and 65.2 m 2 g -1 respectively. Surface morphology examination has shown that the prepared nanoparticles were spherical in shape. Characterization of optimized formulation provided by evaluation of experimental data showed no significant difference between observed and predicted value. Key words: Camptothecin, Nanoparticles, Optimization, Plackett-Burman design, Process parameters.

226 EFFECTS OF MICROVESICLES SECRETED FROM EQUINE AMNIOTIC-DERIVED PROGENITOR CELLS ON IN VITRO LIPOPOLYSACCHARIDE-TREATED TENDON AND ENDOMETRIAL CELLS

Administration of horse amniotic mesenchymal cell conditioned medium (AMC-CM) improves the in vivo recovery of spontaneous equine tendon lesions. This effect may involve paracrine mechanisms whose nature remains unknown. It has recently been demonstrated that microvesicles (MV) released from cells are an integral component of cell-to-cell communication during tissue regeneration. Aims of this study were to investigate the presence and type of MV secreted by AMC using Nanosight instrument (Malvern Instruments, Malvern, UK) and transmission electron microscopy (TEM) and the incorporation of MV in equine tendon and endometrial cells by fluorescence semiquantitative analysis. Tendon cells were used to understand the in vitro role of MV on stressed cells compared with the in vivo results previously obtained, while the endometrial cells were investigated in view of the prospective use of AMC-CM or MV in in vivo inflammatory endometrial diseases. Moreover, the ability of MV to counteract in vitro inflammation of tendon and endometrial cells induced by lipopolysaccharide (LPS) was also evaluated. The MV were obtained by ultracentrifugation at 100 000 × g for 1 h at 4°C of the media obtained by culturing AMC isolated from 3 different placentas. Tendon and endometrial cells were obtained from collagenase digestion for 17 and 3 h, respectively and cultured in HG-DMEM with 10% fetal calf serum. To study the ability of tendon and endometrial cells to incorporate MV, a dose-response curve was performed adding 10, 20, 30, 40, and 50 × 106 MV mL–1 labelled with PKH-26 for 24, 48, and 72 h. The uptake of MV was evaluated by an Olympus BX51 microscope (Olympus, Tokyo, Japan) equipped with software for image acquisition. A dose-response curve of LPS was also investigated by apoptotic and MTT tests showing that 100 ng mL–1 at 48 h on tendon cells and 10 ng at 24 h on endometrial cells were the doses and times most effective in inducing cellular stress. RT-qPCR expression of pro-inflammatory genes such as metallopeptidase (MMP) 1 and 13 was evaluated in the in vitro LPS stress by Mann-Whitney U-test. Results by Nanosight Instrument showed that AMC secrete MV in the range of 100 to 200 nm; TEM showed budding of the AMC membrane, proving that these MV fall within the shedding vesicles category. The same semiquantitative fluorescence uptake signal was obtained when 50 × 106 MV were incorporated at 24 h, or 40 × 106 MV at 48 h, and 30 × 106 MV at 72 h, suggesting that an inverse correlation between concentration and time was found in MV uptake equally by tendon and endometrial cells. The MV induced a significant (P &lt; 0.05) down-regulation of MMP1 and MMP13 expression in both cell lines after in vitro LPS stress. Our data suggest that these MV can be incorporated in tendon and endometrial cells and have a role in modulating inflammatory genes in vitro.

Green biosynthesis of silver nanoparticles using Quercus brantii (oak) leaves hydroalcoholic extract

Context: There is an ever-growing need to develop green, non-toxic, and eco-friendly procedures for synthesis and assembly of nanoparticles (NPs) with the desired morphologies and sizes. The hydroalcoholic extract of Persian oak leaves [Quercus brantii Lindl. (Fagaceae)] contains high content of phenolic and flavonoid compounds with strong antioxidant activities, and it seems that this plant can be considered a good candidate for metal nanoparticle synthesis.Objective: The potential of Q. brantii leaves in the production of silver NPs and the effect of the extract ethanol concentration on the produced NPs were studied.Materials and methods: Quercus brantii leaves were freshly collected, air-dried at room temperature, powdered, and sieved. Hydroalcoholic extracts (70% and 96%) were prepared by percolation of the plant powder. The reaction mixtures contained (final concentrations): AgNO3 (1 mM) as the substrate, plant extract as the biocatalyst, and phosphate buffer (pH = 7, 100 mM) as the reaction medium. Silver ions were determined using atomic absorption analysis. Particle size distribution of NPs was analyzed using Nano-Zeta Sizer (Malvern Instruments Ltd, Malvern, UK). Samples for TEM were prepared by drop-coating the silver nanoparticle suspensions onto carbon-coated copper grids.Results: Hydroalcoholic extract (96%) of Q. brantii successfully produced quite small (as small as 0.83 nm and the mean size of 6 nm), spherical, and poly-dispersed NPs with low aggregates. The conversion was fast and completed in 5 h.Discussion and conclusion: This plant and the extraction method seem to be quiet attractive for industrial scale production of NPs.

The Surface Modification and Antimicrobial Activity of Basic Magnesium Hypochlorite Nanoparticles.

The basic magnesium hypochlorite (BMH) nanoparticles were prepared by two micro-emulsion techniques and modified with sodium stearate. The influences of the main technical parameters such as the addition amount of sodium stearate, reaction temperature and reaction time on the Lipophilic degree (LD) of the modified BMH nanoparticles were investigated. The characteristics of the BMH nanoparticles were analysed by means of Malvern Instruments, transmission electron microscopy (TEM), water contact angle measurements, Fourier transform infrared spectroscopy (FTIR) and thermogravimetry analysis (TGA). The antimicrobial activity of the modified BMH nanoparticles was investigated with the antibacterial circle test. The results showed that the average size of the BMH nanoparticles was 305 nm. The BMH nanoparticles had been successfully modified by sodium stearate and the LD of.the modified BMH nanoparticles was 8.4% when the addition amount of sodium stearate was 0.15 g, the reaction temperature was 10 °C and the reaction time was 5 h. The dispersibility and hydrophobicity of the modified BMH nanoparticles were improved and the contact angle was up to 103 °, the modified BMH nanoparticles still had excellent antimicrobial activity after modification.

Electrochemical performance of Al2O3 pre-coated spinel LiMn2O4

Al2O3-coated spinel LiMn2O4 cathode materials, presintered LiMn2O4 (P-LMO), and calcined LiMn2O4 (C-LMO) were synthesized by chemical deposition and thermal treating method using presintered and calcined LiMn2O4 as precursors. The crystal structure, morphology, the thickness of the coating layer, and particle size of prepared samples were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and Malvern instruments. The average particle size of P-LMO with like-spheres (0.3 μm) is much smaller than that of C-LMO (0.5 μm). The Al2O3 layer of P-LMO can effectively reduce the charge transfer resistance and inhibit the Mn dissolution. The electrochemical performance of P-LMO is better than that of C-LMO. It is found that the LiMn2O4 cathode materials have excellent electrochemical cyclability by coated 2 mol% Al2O3 at the surface of presintered material. The initial discharge capacity of the material with 2 mol% Al2O3-coated is 114.0 mAh·g−1 at 0.1C rate and 55 °C, and the capacity retention is 87.3 % at 0.5C rate.

In Vitro Liberation of Indomethacin from Chitosan Gels Containing Microemulsion in Different Dissolution Mediums

The objective of this research is to outline the liberation of indomethacin from different chitosan gels containing O/W microemulsion. The influence of surfactant, sodium lauryl sulfate, in two concentrations (0.5% and 0.75%, w/w) was determined in dissolution medium on the release of indomethacin, which was used as poor water-soluble model drug. Chitosan gels were prepared in four different concentrations of chitosan-1%, 1.5%, 2%, and 3% (w/w). Microemulsion enhanced the liberation of the indomethacin from chitosan gels into all dissolution mediums. Adding the surfactant into phosphate-buffered saline decreased the amount of liberated indomethacin from microemulsion, gel mixture, but increased the drug liberation from pure chitosan gels. It was detected that with the increased concentration of chitosan in the samples, the amount of indomethacin liberated (p < 0.05) also increased. A conclusion was drawn that the liberation of indomethacin from chitosan gels was influenced by increased pH of the samples. The high viscosity induced a higher release of indomethacin from 3% (w/w) chitosan hydrogel at pH 5.8 as compared with 3% (w/w) chitosan hydrogel at pH 3.8. The highest percentage of released indomethacin was determined when a mixture of microemulsion gel with higher chitosan content was used.

Dynamic and shear stress rheological properties of guar galactomannans and its hydrolyzed derivatives

Guar galactomannan from seed of Cyamopsis tetragonolobus was hydrolyzed using acid (HCl), base [Ba(OH)2] and enzyme (mannanase) method to obtain depolymerized substances with possible functional applications as soluble dietary fiber. Rheological behavior of crude, purified, and depolymerized guar gum solutions was studied at 25°C, using shear stress and dynamic oscillatory measurements, performed with controlled stress rheometer Bohlin CVO (Malvern Instruments) fitted with cone-and-plate geometry. The various guar gums solutions with different viscosities exhibited shear-thinning behavior at high shear rate and Newtonian behavior at low shear rate. At low shear rate, sigma crude guar gum (SCGG), crude guar gum (CGG), acid hydrolyzed guar gum (AHGG) and enzyme hydrolyzed guar gum (EHGG) exhibited viscosities of 18.59, 1.346, 0.149 and 0.022Pas, respectively. Oscillatory experiments (G″, G′) of gums solutions showed typical behavior of weak viscoelastic gel. All investigated guar gums were further used for glucose bio-accessibility using a novel in vitro small intestinal model (SIM). All gums solutions resulted in 20% reduction in simulated glucose absorption, indicating a non-significant functionality difference between various guar gums. So, it can be concluded that hydrolyzed guar gums without disturbing their rheological and physiological behavior would be useful for incorporation in various food products as soluble dietary fiber.

Role of the Cytoplasmic N-terminal Cap and Per-Arnt-Sim (PAS) Domain in Trafficking and Stabilization of Kv11.1 Channels

The N-terminal cytoplasmic region of the Kv11.1a potassium channel contains a Per-Arnt-Sim (PAS) domain that is essential for the unique slow deactivation gating kinetics of the channel. The PAS domain has also been implicated in the assembly and stabilization of the assembled tetrameric channel, with many clinical mutants in the PAS domain resulting in reduced stability of the domain and reduced trafficking. Here, we use quantitative Western blotting to show that the PAS domain is not required for normal channel trafficking nor for subunit-subunit interactions, and it is not necessary for stabilizing assembled channels. However, when the PAS domain is present, the N-Cap amphipathic helix must also be present for channels to traffic to the cell membrane. Serine scan mutagenesis of the N-Cap amphipathic helix identified Leu-15, Ile-18, and Ile-19 as residues critical for the stabilization of full-length proteins when the PAS domain is present. Furthermore, mutant cycle analysis experiments support recent crystallography studies, indicating that the hydrophobic face of the N-Cap amphipathic helix interacts with a surface-exposed hydrophobic patch on the core of the PAS domain to stabilize the structure of this critical gating domain. Our data demonstrate that the N-Cap amphipathic helix is critical for channel stability and trafficking.

Extending the options for particle characterisation

Pauline Carnell, product manager at Malvern Instruments, discusses how Nanoparticle Tracking Analysis can improve the characterisation of metal powders.