Normal Particle Size Research Articles

Numerical simulation on the bomb case effects of non‐ideal aluminized explosive

AbstractThe detonation process of non‐ideal explosives is influenced by the casing of the bomb. Non‐ideal charges in the process of the explosion of live ammunition energy output mechanism and distribution ratio, the impact of the case on the explosion flow field, and other issues cannot be obtained through the existing theoretical analysis and testing techniques to obtain specific values. This paper establishes a “detonation+afterburning” energy output model to characterize the energy release characteristics of non‐ideal charges, using step‐by‐step numerical simulation of the near and middle, and far fields of the explosion, and verify simulation results through experiments, quantitative analysis the case of a type of earth penetrator on the normal particle size (4 μm) and two times the normal particle size (8 μm) of non‐ideal charges of aluminum powder explosion process. The results indicate that the presence of the casing enhances the energy output of aluminum powder with 4 μm by ≈5 %. When the particle size of aluminum powder is doubled, the maximum reaction rate and the peak of the shock wave are merely around 35 % and 75 %, respectively, compared to those of normal particle size. The detonation products, case fragments, and air constitute 49 %, 48 %, and 3 % of the overall explosion energy, respectively. The proportional equation of the conversion between the chemical energy of the explosion and the kinetic energy of the case fragments is obtained. These conclusions can provide data support for the design of non‐ideal charge warheads, lethality assessment, and establishment of engineering protection standards.

Green synthesis of nanocomposite based on magnetic hydroxyapatite using Falcaria vulgaris Bernh leaf extract to remove tartrazine dye from aqueous solution

To mitigate the adverse impacts of water pollution, the application of nanotechnology in dye removal and by-product reduction has the potential to establish a sustainable potable water supply. For these methodologies, the materials must involve exhibit qualities such as simplicity, high efficiency, eco-friendliness, reusability, and affordability. This study presents a novel porous magnetic hydroxyapatite nanocomposite coated with zinc oxide (Fe3O4@HAP@ZnO). Initially, zinc oxide nanoparticles were generated via a green synthesis method, where a zinc nitrate solution was combined with an aqueous extract from the Falcaria Vulgaris Bernh plant, serving as a reducing and stabilizing agent. These were then coated onto the magnetic hydroxyapatite.Verification of successful nanocomposite synthesis was obtained through X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and X-ray spectroscopy (EDS), vibrating-sample magnetometer (VSM), High-resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM) images further substantiated these results. The synthesized nanocomposite exhibited a normal particle size distribution of approximately 89 nm. To achieve maximal decolorization efficiency, pertinent parameters were scrutinized and optimized through a detailed experimental design. Under optimal conditions, the nanocomposite's ability to decolorize tartrazine dye in an aqueous solution was evaluated. Remarkably, the highest observed efficiency approached 98 %, employing 0.07 g of the nanocomposite at 90 degrees Celsius, pH 6.4, over a span of 30 min. Further exploration of the nanocomposite's reusability revealed it could sustain an efficiency exceeding 90 % across 11 successive cycles, boasting an impressive capacity of 1398 (mgg-1).

Stick‐Slip Nucleation and Failure in Uniform Glass Beads Detected by Acoustic Emissions in Ring‐Shear Experiments: Implications for Identifying the Acoustic Emissions of Earthquake Foreshocks

AbstractStress accumulation and release reflected by acoustic emissions (AEs) during shearing of granular materials provide important information on failure mechanisms in seismic faults and landslides controlled by stick‐slip. Among many characteristics (amplitude, energy, counts, and frequency) of AE signals generated by stick‐slip, stress changes corresponding to various frequency AEs in different stages of the stick‐slip process are not clear, which limits our knowledge of the characteristics of precursory signals before stick‐slip failure. To better understand the physical mechanisms of granular stick‐slip, we monitored the mechanical and AE signals using high‐frequency (2 MHz) synchronous acquisition during constant‐speed shear of packs of uniform glass beads with different sizes at different normal stresses. The release rate of AE energy was found to accelerate with the dilatation of the sample volume, and the stress drop of stick‐slip was augmented with the increase of normal stress and particle size. Three characteristic events of single cycle stick‐slip were observed in this study: main slip, minor slip, and microslip. We analyzed the AE frequency spectra of these three event types. Both main slip and minor slip corresponded to stress drop and generated high‐frequency AEs (about several hundred kHz), while the AE frequencies generated by microslip were lower (about tens of kHz) and exhibited stress strengthening, which were not apparent in previous studies due to the low frequency of acquisition. We propose that the microslip is mainly due to sliding on grain contacts, while the main slip and minor slip resulted from breakage and reforming of force chains. Low‐frequency AEs from microslip may suggest a crucial precursor of seismic faults and landslides.

CFD-PBM Simulation for Continuous Hydrothermal Flow Synthesis of Zirconia Nanoparticles in a Confined Impinging Jet Reactor.

Computational fluid dynamics (CFD) and population balance models (PBM) were coupled together for the first time to simulate the synthesis of zirconia nanoparticles in a continuous hydrothermal flow synthesis (CHFS) system with a self-designed confined impinging jet mixing (CJM) reactor. The hydrodynamic and thermodynamic behaviors within the CJM reactor strongly influenced the formation of the ZrO2 nanoparticles. Crucial parameters, such as velocities, temperatures, mixing conditions, and reaction rates, were analyzed under various supercritical conditions. Temperature and velocity measurements as functions of distance were also investigated. Normal particle size distribution (PSD) patterns were observed in all cases. The mean particle sizes in this study were calculated and compared using PBM aggregation analysis.

Evaluation of particle models of corn kernels for discrete element method simulation of shelled corn mass flow

Bulk handling behavior of grains can be studied experimentally, but large-scale investigations of grain flow especially at the commercial scale are expensive, time consuming, and are therefore limited in the treatment factors that can be evaluated in any one study. Recent research has demonstrated the potential of discrete element method (DEM) in simulating grain flow in handling operations. However, application of DEM for simulating grain flow, requires development of appropriate particle models for each grain type. In this study, particle models comprised of one to four overlapping spheres were developed for shelled corn and tested. With these models, measurement of bulk properties, namely bulk density and angle of repose, both involving bulk flow were simulated using EDEM™ software with published data of material and interaction properties of shelled corn as inputs associated with each particle shape. Predicted time for the complete outflow from the bulk density test hopper (hopper emptying time), designated as simulation time in the study, was also recorded as another discriminant for model selection. Variable inputs into the simulation modeling were material properties particle shape, particle size distribution, Poisson's ratio, shear modulus, and density and interaction properties particle coefficients of restitution, static friction, and rolling friction. Computation time is critical in DEM modeling so single sphere particle models were emphasized over multi-sphere particles in the research even though multi-sphere particles represent the corn kernel shape more precisely because their simplicity can provide markedly reduced computation times to complete simulations. Predicted results for hopper emptying time, bulk density, and angle of repose were compared to experimental results or published data to select the most appropriate particle models for simulating bulk behavior of corn kernels in free-flowing grain applications using DEM. From the study, the most appropriate particle model (particle shape/physical properties combination) for corn kernels involved a single-sphere shape particle shape with a particle coefficient of restitution of 0.30, particle coefficients of static friction of 0.30 for corn-corn contact and 0.20 for corn-steel contact, particle coefficient of rolling friction of 0.05, normal particle size distribution with a standard deviation factor of 0.4, and particle shear modulus of 20 MPa.

PMON73 Lipid profile in patients with Cushing's syndrome and the impact of surgical treatment

Abstract Introduction Cushing syndrome (CS) patients have an increased mortality rate, primarily due to increased cardiovascular and cerebrovascular disease. We postulated that lipoprotein or lipid profiles might underlie this risk. Methods We measured traditional lipid panels (Cholesterol, TC; calculated low density lipoprotein, LDL; triglycerides, TG; high density lipoprotein, HDL) by Abbot enzymatic assay and lipoprotein particles (particle size and number for HDL, LDL and VLDL) by nuclear magnetic resonance spectroscopy in CS patients before and after surgical remission. Values are shown as median (IQR or range). Results After initial evaluation, 41 subjects (median age 53 (IQR 39-63) years; 27 female) had presumed Cushing's disease (CD, n=23), ectopic ACTH secretion (EAS, n=17), or adrenal adenoma (AA, n=1). Fourteen were on chronic statin therapy. All median lipid values were normal except HDL, at 55mg/dl (range 27 - 59mg/dl, normal (RR) <60). Twenty-six patients had decreased HDL; of these, other abnormal values included TC and LDL (n=4), TG (n=4), TC, LDL, TG (n=2), LDL and TG (n=2) or LDL only (n=2). Other elevated LDL levels occurred alone (n=1) or with TC (n=2). Three patients had only an increase in TC, LDL, or TG. Median LDL particle number was increased at 1015 (IQR 809-1353; RR <1000), with normal particle size. Eighteen patients had increased LDL particle number (1005 - 2989); 7/18 had increased TC and/or LDL. The median particle size and number for HDL and VLDL were normal in all patients except for one with an increased VLDL particle number of 199.7 (RR 6.8 - 126.1; TGs 302mg/dl, LDL 61 mg/dl, HDL 36 mg/dl, Chol 158 mg/dl). Sixteen subjects with CD (n=10), EAS (n=5) or AA (n=1) (13 females, median age 53 (IQR 40-58) years) had data at last study visit (LSV) after surgical remission. At LSV (median 13 months, range 3-26 months) abnormal preoperative LDL particle size persisted in 5/10, with new abnormalities (to 1450nm) in 3 patients. Initially high LDL and TC normalized in 3/6 and 4/5 patients. Abnormal HDL values were new in 2 patients and persisted in 7/8 from baseline. HDL particle number was low in two of these patients, while one with an HDL of 90mg/dl had increased particle size (10.6nm). TG and VLDL particle number and size remained normal except for one patient with low values. A statistically significant decrease (p=0.03) of median VLDL particle size from 49.5 nm (IQR 47.8-52.5) to 45.5nm (IQR 43.3–49.6), was noted at LSV. Conclusions While the numbers are small, these data suggest that the moderate cardiovascular risk conferred by elevated LDL particle size and low HDL persisted for up to 26 months of remission. Improved initiation and modification of treatment for these abnormalities might improve outcomes. Presentation: Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.

Multi dye degradation, antibacterial, antidiabetic and antioxidant assessment of silver nanoparticles (Ag-NPs) derived via leaves of Smilax aspera

Biosynthesized nanomaterials are in high demand due to their potential in medical applications and the search for efficient biosynthesized nanomaterials continues. The endeavor of this research work is to synthesize silver nanoparticles (Ag-NPs) utilizing an aqueous extract of Smilax aspera (S. aspera) leaves. Several analytical techniques were used to investigate the shape, morphology and size of NPs. UV–visible spectroscopy exhibited a band at 472 nm indicating the formation of Ag-NPs, phytoconstituents functioning as capping or reducing agent are revealed by FT-IR, XRD (X-Ray diffraction) verified cubic crystalline structure having (h,k,l) values at (1 1 1), (2 0 0), (2 2 0), (3 1 1) and (2 2 2). Energy dispersive X-rays spectroscopy confirmed the purity of elemental silver, Scanning electron microscopy as well as Transmission electron microscopy (TEM) reported that particles are in a spherical shape with a normal particle size of 34 nm. Furthermore, in DLS data two peaks at 5.89 nm (5%) and 39.99 nm (95%) were observed, which supports the TEM finding. The Synthesized Ag-NPs have shown significant antibacterial activity against pathogens due to the capping of the bioactive components of Smilax aspera leaves. Furthermore, The antioxidant potential of synthesized Ag-NPs was calculated performing 2,2 diphenyl-1-picrylhydrazyl hydrate (DPPH) free radical scavenging assay. Moreover, Methylene blue, Rose bengal, and Acridine orange dyes have also been degraded employing Ag-NPs as a catalyst. Inhibition of carbohydrate hydrolyzing enzymes, in addition to the previously mentioned actions, emphasized the antidiabetic efficacy of these produced Ag-NPs. Overall, Ag-NP’s efficient bioactivities indicate their promising future in biomedical and environmental remediation applications.

Influence of Cold Plasma on Sesame Paste and the Nano Sesame Paste Based on Co-occurrence Matrix

The aim of the research is to investigate the effect of cold plasma on the bacteria grown on texture of sesame paste in its normal particle and nano particle size. Starting by using the image segmentation process depending on the threshold method, it is used to get rid of the reflection of the glass slides on which the sesame samples are placed. The classification process implemented to separate the sesame paste texture from normal and abnormal texture. The abnormal texture appears when the bacteria has been grown on the sesame paste after being left for two days in the air, unsupervised k-mean classification process used to classify the infected region, the normal region and the treated region. The bacteria treated with cold plasma, the time exposure is two minutes. The textural features related to gray level co-occurrence matrix are calculated for the normal, abnormal and the treated texture, it is obvious that the treated texture class has the best features compared with the other classes. The result shows the sesame paste treated with plasma has good result compared with nano sesame paste treated with plasma. This is because the plasma provides the sesame paste with heat and makes the sesame nano particle congregate together.

Intestine-specific ablation of the Hepatocyte Nuclear Factor 4a (Hnf4a) gene in mice has minimal impact on serum lipids and ileum gene expression profile due to upregulation of its paralog Hnf4g

Ablation of the gene encoding the nuclear receptor Hepatocyte Nuclear Factor 4a (Hnf4a) in the liver strongly affects HDL concentration, structure and functionality but the role of this receptor in the intestine, the second organ contributing to serum HDL levels, has been overlooked. In the present study we show that mice with intestine-specific ablation of Hnf4a (H4IntKO) had undetectable levels of ΗΝF4A in ileum, proximal and distal colon but normal expression in liver. H4IntKO mice presented normal serum lipid levels, HDL-C and particle size (α1-α3). The expression of the major HDL biogenesis genes Apoa1, Abca1, Lcat was not affected but there was significant increase in Apoc3 as well as in Hnf4g, a paralog of Hnf4a. RNA-sequencing identified metabolic pathways significantly affected by Hnf4a ablation such as type II diabetes, glycolysis, gluconeogenesis and p53 signaling. Chromatin immunoprecipitation assays showed that HNF4G bound to various apolipoprotein gene promoters in control mice but its binding affinity was reduced in the ileum of H4IntKO mice suggesting a redundancy but also a cooperation between the two factors. In the distal colon of H4IntKO mice, where both HNF4A and HNF4G are absent and in a mouse model of DSS-induced colitis presenting decreased levels of HNF4A, most lipoprotein genes were strongly downregulated. In conclusion, Hnf4a ablation in mice does not significantly affect serum lipid levels or lipoprotein gene expression in ileum possibly due to compensatory effects by its paralog Hnf4g in this tissue.

Preparation and Characterization of Cellulose and Microcrystalline Cellulose from Sugarcane Bagasse and Assessment of the Microcrystalline Cellulose as a Directly Compressible Excipient

Cellulose, the most abundant biomass material in nature finds wide applications in the pharmaceutical industry. Sugarcane bagasse (SCB) is one of the main agricultural lignocellulose byproducts. The objective of this study was to prepare and characterize native and microcrystalline cellulose (MCC) from SCB and evaluate the MCC as a directly compressible pharmaceutical excipient. Cellulose was extracted from SCB by chlorine-free methods with or without dewaxing. MCC was prepared from the cellulose by hydrolysis using hydrochloric acid, and subsequently oven-dried (OD) or spray-dried (SD). The as-obtained cellulose and MCC were characterized in terms of yield, degree of polymerization (DP), chemical functionality, crystallinity, morphology and thermal stability. The chemical composition, particle size, densities and direct compressibility of MCCs were also determined. Cellulose yields on a dry weight basis were found to be 42.8 ± 1.10% and 43.5 ± 0.5% from non-dewaxed and dewaxed SCB, respectively. Dewaxed SCB cellulose (DSCBC) provided higher yield of MCC (DSCB-MCCOD, 83 ± 0.74%) than non-dewaxed SCB cellulose (SCBC) (SCB-MCCOD; 78 ± 1.07%). The DP of SCBC and DSCBC were 580.56 and 592.75, respectively, while the DP of MCC ranged from 230.10 - 251.40. The FTIR spectra of both cellulose and MCC were similar with that of Avicel PH-101. The degree of crystallinity of the dewaxed cellulose (77.34%) and MCCOD (79.56%) and MCC-SD (81.87%) were higher than non-dewaxed cellulose (74.50%) and MCC-OD (78.11%) and MCC-SD (79.62%). Scanning electron micrographs (SEM) showed a fibrous structure for DSCBC and rod-shaped for DSCB-MCC. Thermogravimetric analysis (TGA) revealed dewaxed products exhibited better thermal stability than non-dewaxed products. All MCC samples exhibited monomodal normal particle size distributions. The Hausner ratio and Carr’s index of DSCB-MCCOD and Avicel PH-101 were not significantly different (p < 0.05) indicating similar flow property and compressibility of the materials, respectively. Also, plain tablets prepared from SCB-MCC showed reasonably high crushing strengths (MCC-SD > MCC-OD), although tablets of Avicel PH-101 showed the highest crushing strengths. Thus, SCB could be an alternative source of cellulose and MCC for pharmaceutical applications.

Isolation and Physico‐chemical Characterization of Triticum Decocum Starch

AbstractEthiopian oat (Triticum decocum) starch has been isolated and examined for its chemical composition and physicochemical properties. The proximate composition of the starch on a dry weight basis is found to be 0.23% ash, 0.26% protein, 1.54% fat, and 56.31% starch. The total amylose content is 28.4% with 20.11% apparent amylose and 29.19% lipid complexed amylose. SEM showed oval, spherical shaped granules. The particle size distributions of the starch showed monomodal normal particle size distribution with the average volumetric particle diameters being about 23.03 µm, and specific surface area 0.7186 m2 g−1. XRD showed a pattern that is typical of A‐type with a distinctive maximum peak at around 17° 2θ. At all relative humidities, its water sorption properties resemble that of maize starch. It has unique swelling power and solubility in water at different temperatures. Viscosity curves of 10% of starch paste showed a peak viscosity of 1926cP. Its cold paste viscosity and hot paste viscosity are 4236 and 1720 cP, respectively. The breakdown and set back viscosities of Ethiopian oat starch are 206 and 2647cP, respectively. The FTIR showed the characteristic features of prominent starch peaks. Physicochemical characteristics of the oat starch have shown that it has similar properties with maize starch which could make it fit for use in food and pharmaceutical industries, especially in the area where oat is produced as endogenous crop like in Ethiopia.

Research on feasibility of in vitro inflammatory wound microenvironment simulated by using inflammatory wound tissue homogenate of mice

Research on feasibility of in vitro inflammatory wound microenvironment simulated by using inflammatory wound tissue homogenate of mice

Investigation of the chord length Markovian probability distribution for self-shielding treatment on double heterogeneity problem

The existing methods on the double heterogeneity self-shielding problem adopt the Markovian distribution to describe the spatial distribution of dispersed particles. However, the applicability of Markovian distribution for the practical Fully-Ceramic-Microencapsulated (FCM) fuel still needs to be discussed. This work aims to evaluate the effect caused by the approximation of Markovian distribution on the resonance self-shielding treatment in the situation of filled particles with different sizes in FCM fuel design. To be compared with the Markovian distribution, a series of practical chord length distributions are depicted by the Chord-Length-Sampling method. We implemented the analytical average Dancoff method and the Sanchez-Pomraning Subgroup method for 2D cylindrical FCM fuel. A series of average Dancoff factors and resonance cross-sections are calculated with the reference of results provided by the Monte Carlo method. The results show that the Markovian distribution can be accepted with the normal particle size. In contrast, the Markovian distribution affects the accuracy of resonance calculation severely in terms of extremely large particle size of the dispersed particles.

Preparation and Evaluation of Sodium Alginate Microparticles using Pepsin

Aim: The main aim of this article is to prepare and evaluate sodium alginate microparticles and evaluate on the basis of their characterization. The drug is dissolved, encapsulated or attached to a microparticles matrix. Depending upon method of preparation microparticles were obtained. Microparticles were developed as a carrier for vaccines and other disease like rheumatoid arthritis, cancer etc. Microparticles were developed to increase the efficacy of active pharmaceutical ingredient to a specific targeted site.
 Material and Method: Microparticles of Sodium Alginate, Pepsin and Calcium Chloride were prepared in six batches (A-F) with different ratio of sodium alginate and calcium chloride respectively i.e. (0.25:2.5), (0.25:5), (0.25:7.5), (0.5:2.5), (0.5:5), (0.5:7.5) by using a homogenizing method. Microparticles were evaluated for particle size distribution, zeta potential and morphology.
 Result and Discussion: The normal particle size of each of the six batches were analyzed by Zeta Sizer (Delsa C Particle Analyzer) and it was found that the Batch B (0.25:5) delivered the best microparticles with size distribution of 1.2731 (µm). All batches were seen under Motic magnifying microscope by using the Sulforhodamine B (M.W. 479.02) color as staining dye. Microparticles was found to be semi spherical in shape.
 Conclusion: Results of all the six batches was contrasted based on particle size investigation, zeta potential and morphology. Batch B (0.25:5) was considered as the best formulation.
 Key words: Micro Particle, Pepsin, Sodium Alginate and Calcium Chloride, Sulforhodamine B, Zeta Sizer.

Al–Al2O3 powder composites obtained by hydrothermal oxidation method: Powders and sintered samples characterization

The aluminum powder composites based on Al–Al2O3 were obtained by the advanced in–situ partial hydrothermal oxidation method. The opportunity to obtain the controlled amount of alumina on the particle’s surfaces was studied. The water vapor temperature fixed at 90 °C and 120 °C gave the possibility to obtain two composites with the amount of Al2O3 at 9.90 wt % (OAP–1) and 18.75 wt % (OAP–2). Their median diameters were 41–42 μm with normal particle size distribution. The comparison with atomized 7068 alloy (AP–7068) powder showed their better particle sphericity. The OAP–1 sintered sample has the highest hardness of 471 MPa that provided by the highest density of 97.1% and the finest grain structure.

A thermodynamic model to simulate the thermo-mechanical behavior of fine-grained gassy soil

Fine-grained gassy soil is a special kind of unsaturated soil, with the gas in the form of discrete big bubbles within the saturated matrix. These gas bubbles are sealed and considerably larger than the normal particle size. Based on the conceptual model of soil containing large gas bubbles proposed by Wheeler (Geotechnique 38(3):389–397, 1988a) and the granular solid hydrodynamics (GSH) theory, a thermodynamic model is presented to describe the mechanical properties and temperature effect of fine-grained gassy soil in this paper. The model assumes that the gas pressure is related to total stress and pore water pressure of soil, and the behavior of saturated matrix is controlled by “quasi-effective stress.” In addition, the effect of gas on the plastic deformation of soil skeleton is considered. Comparing with the experimental results, the ability of the model to describe the consolidation and undrained shear properties of fine-grained gassy soil is verified. What is more, the effect of temperature on fine-grained gassy soil considering the various responses for different drainage conditions and overconsolidation ratios is discussed and simulated by the proposed model. It is concluded that for fine-grained gassy soil with different overconsolidation ratios, the increase of temperature can increase the compressibility and thermal contraction under drained conditions, as well as the pore water pressure under undrained conditions, while the temperature effect on undrained shear properties depends on the initial conditions.

Application of normal essential oil and loaded-solid lipid nanoparticles as antioxidant

The industry adds antioxidants in the formulation of meat products to prevent or delay meat oxidation reactions. Therefore, this investigation was carried out to study the effect of normal essential oil and loaded-solid lipid nanoparticles as antioxidants and the effect of the abovementioned volatile oils on chemical properties (TBA) and shelf life of frozen beef burger. The antioxidant activity of volatile oils (cinnamon and ginger) normal and nano particle size at different concentrations were assessed. Also, the effect of the above mentioned volatile oils addition with different concentrations on chemical properties and shelf life of frozen beef burger was investigated. Results indicated that, the diphenylpicrylhydrazyl free radical scavenging activity increased by increasing the volatile oil concentrations for all studied treatments. Moreover, the antioxidant activity of volatile oils (cinnamon and ginger) nanoparticles was higher than that of the same concentrations of normal volatile oil. The chemical properties values thiobarbituric acid value (TBA) of beef burger decreased by increasing volatile oils concentrations and essential oils nanoparticles reduced chemical properties (TBA) values more than normal essential oils, beside extending the shelf life of beef burger treatments up to 6 months in comparison with control sample which have a four-month shelf life. In conclusion, the transformation of essential oils into nanoparticle size can affect their antioxidant activity and promote the chemical properties and shelf life of beef burger.

Formulation and characterization of chlorhexidine HCl nanoemulsion as a promising antibacterial root canal irrigant: in-vitro and ex-vivo studies.

Introduction and aim: Chlorhexidine Hydrochloride [Chx.HCl] has a broad-spectrum antibacterial effect, sustained action and low toxicity so it has been recommended as a potential root canal irrigant. The aim of this study was to improve the penetration ability, cleansing and antibacterial effect of Chx.HCl using a newly formulated Chx.HCl nanoemulsion and use it as root canal irrigant.Methods: Chx.HCl nanoemulsions were prepared using two different oils; Oleic acid and Labrafil M1944CS, two surfactants; Tween 20 and Tween 80 and co-surfactant; Propylene Glycol. Pseudoternary phase diagrams were constructed to designate the optimum systems. The prepared nanoemulsion formulae were evaluated for their drug content, emulsification time, dispersibility, droplet size, in-vitro drug release, thermodynamic stability, In-vitro antibacterial activity and ex-vivo study for the selected formula. Comparisons were made of Chx.HCl nanoemulsion with two different concentrations 0.75% and 1.6% vs Chx.HCl normal particle size as root canal irrigant for their penetration ability, cleansing effect and antibacterial effect.Results: The selected formula was F6 with composition of 2% Labrafil, 12% Tween 80 and 6% Propylene glycol. It has small particle size (12.18 nm), short emulsification time (1.67 seconds), and fast dissolution rate after 2 minutes. It was found to be a thermodynamically/physically stable system. The higher concentration of Chx.HClnanoemulsion1.6% shows the best penetration ability compared to Chx.HCl normal particle size due to the smaller particle size. Chx.HCl nanoemulsion 1.6% has the lowest mean value of the remaining debris surface area (2001.47 µm2) when compared to normal particle size material (2609.56 µm2).Conclusion: Chx.HCl nanoemulsion preparation has better cleansing ability and antibacterial effect with high efficacy on Enterococcus faecalis, where high reduction rate or complete eradication of bacterial cells has been achieved.

Polyacrylic acid-coated iron oxide magnetic nanoparticles: The polymer molecular weight influence

Magnetic nanoparticles (MNPs), in particular, magnetic iron oxide-based nanoparticles were found to be useful as catalysts and as devices for data storage, environmental remediation and several biomedical applications, due to their excellent properties, such as biocompatibility and high magnetic moment. Polyacrylic acid (PAA) is a weak polyelectrolyte that can be used to stabilize the MNPs. To the best of our knowledge, the influence of PAA molecular weight and PAA concentration over the magnetic and structural properties of iron oxide nanoparticles has not been previously reported. The aim of this paper is to describe the differences evidenced in the properties of different magnetic materials by using PAA for iron oxides stabilization by one-pot coprecipitation synthesis. Iron oxide-based magnetic nanoparticles stabilized by polyacrylic acid (PAA) polymers were efficiently prepared and exhaustively characterized. The influence on the employment of two different low PAA molecular weights, Mw 1800 g/mol and 5000 g/mol, in three different iron salts: PAA ratios was analyzed. In summary, the main results showed that: for a certain PAA reactor feed higher oligomer quantities are present in MNPs as higher is the involved molecular weight of the polymeric chain; when molecular weight raises the contribution of loops and tails also does it, allowing having higher polymer contents. For both PAA’s Mw employed as the adsorbed PAA increases particles hydrodynamic diameters decreases, and their distribution becomes narrower; the PAA adsorbs onto iron oxides by chemisorption (the most probable interaction is the bidentate bridging). For the studied cases z potential values depend much more on the PAA’s quantity adsorbed onto the iron oxides than on the PAA’s Mw. MNPs are superparamagnetic and choosing the right shape of particle distribution is not central for getting estimates of the magnetization saturation, the average particle diameter and its standard deviation, while better fits are found with Normal and Log-Normal particle size distributions.

Application of a flexible membrane to DEM modelling of axisymmetric triaxial compression tests on sands

An innovative flexible membrane algorithm was developed and applied to the 3-D DEM modelling of axisymmetric triaxial compression tests on sands. This proposed flexible membrane was made of simply packed single spheres. The vertical and side extensions of the membrane were bounded by a series of boundary walls. These measures equipped the membrane with enough flexibility to contain local deformations of the cylindrical specimen which was comprised of un-bonded particles. With the application of the flexible membrane, the specimens failed with bulging shapes which were typical of axisymmetric triaxial tests. A comprehensive parametric sensitivity study indicated that the normal stiffness and particle size of the membrane spheres had limited influence on the test results, while the shear stiffness of the membrane spheres substantially enhanced the residual strength of the specimen. To examine the effectiveness of the flexible membrane algorithm, the numerical specimen was characterised on the macroscopic, mesoscopic and microscopic scales. The stress and strain response of the specimen well matched the laboratory test, and the volumetric strain presented apparent contraction and expansion stage. More importantly, the characterisation on the local void ratio clearly indicated the flexible membrane enabled full development of strain localisation inside the specimen.