Lower Mean Particle Size Research Articles

Microwave-assisted enzymatic hydrolysis: A sustainable approach for enhanced structural and functional properties of broken rice protein

Design experiments having three levels of each processing parameter i.e.,α-amylase concentration (0.25–0.75%), extraction time (30–180 min), and temperature (30–60 °C) were conducted to investigate the effect of enzymatic pre-treatment on protein content and extracted yield from broken rice, an industrial by-product. Enzymatically pre-treated broken rice under optimal conditions (0.72% α-amylase concentration, 141 min extraction time, and 43°C of temperature) were subjected to microwave treatment followed by varying degrees (3%, 6%, 9%, and 12%) of enzymatic hydrolysis. The study revealed that the strongest free radical scavenging activity (72.35 ± 4.31 and 93.47 ± 1.25 μmol Trolox equivalent/g), highest magnitude of zeta potential (−24.95 ± 0.64 mV), and lowest mean particle size (446 ± 6.43 nm) were observed at MDH 12%. The FTIR analysis of MDH 12% (1650.08 cm−1) indicated a shift from random coil to β-turn, resulting unfolding of the rice protein structure and increased protein solubility. However, with an increase in DH, a negative effect on the foaming and emulsification properties of rice protein was observed. This study revealed that microwave-assisted enzymatic treatment with a 12% degree of hydrolysis can improve the functional properties of extracted protein and meet the demand for rice protein applications in different food formulations.

Evidencing the synergistic effects of carbonization temperature, surface composition and structural properties on the catalytic activity of biochar/bimetallic composite

The effect of pyrolysis temperature on biochar properties is more exacerbated when combined with the presence of metallic dopants on the surface of the lignocellulosic material. Herein, we investigate the relationship between the surface composition (SC), the graphitization degree (GD), the particle size (PS) and the catalytic activity of mandarin peel biochar decorated with copper and nickel alloy. All biochar samples were prepared by a wet impregnation of the metal ions followed by slow pyrolysis of the Cu2+/Ni2+-loaded biomass at temperatures ranging from 300° to 700 °C, for 15 min and under N2 atmosphere. Interestingly, the biochar with the highest GD was obtained at 300 °C; its surface contained CuNi alloy and NiO, whereas it contained only the bimetallic alloy for all samples fabricated at 500 and 700 °C. The 300 °C and 500 °C samples have mean PSs in the nanoscale regime, 71 ± 12 nm and 54 ± 12 nm, respectively. On contrast, the 700 °C biochar composites have very broad PS distributions in the 30–400 nm size range. They were also found to be the least graphitized samples. Practically, the 300 °C nanocomposite was the most active catalyst for the oxidative degradation of Methylene Blue, chosen as a model reaction for the catalytic performance testing. The degradation was total under H2O2 conditions, and the kinetic experimental data fitted the pseudo-first-order with degradation apparent constant 0.071 min-1. Despite its lowest mean particle size and graphitization degree, higher than the graphitization degrees of the 700 °C nanocomposites, the sample elaborated at 500 °C was the least active catalyst. Its highest K to C atomic ratio suggests that potassium emerging from the biochar surface had a poisoning effect which deactivated the CuNi alloy. Conclusively, these findings permitted to gain more insights into the synergistic effects of surface composition, particle size and graphitization degree on the catalytic activity of Biochar-supported CuNi alloy elaborated at different pyrolysis temperatures.

Multidrug-loaded liposomes prevent ischemic stroke through intranasal administration

Baicalin (BA), a multi-target neuroprotective agent, has poor solubility resulting in low bioavailability. In this study, multidrug-loaded liposomes were prepared by encapsulating BA, borneol (BO) and cholic acid (CA) to prevent ischemic stroke. BBC-LP were administered intranasally (i.n.) to deliver into the brain for neuroprotection. Finally, potential mechanism of BBC treating ischemic stroke (IS) was explored by network pharmacology. In this study, BBC-LP was prepared by reverse evaporation method, and the encapsulation efficiency (EE) of the optimized liposomes was 42.69% and the drug loading (DL) was 6.17%. The liposomes had low mean particle size (156.62 ± 2.96 nm), polydispersity index (PDI) (0.195) and zeta potential (−0.99 mv). Compared to BBC, pharmacodynamic studies revealed that BBC-LP significantly improved neurological deficits, brain infarct volume, and cerebral pathology in MCAO rats. Toxicity studies showed that BBC-LP was not irritating to the nasal mucosa. These results suggest that BBC-LP can safely and effectively ameliorate IS injury by i.n. administration. Moreover, it's neuroprotective function may be related to the anti-apoptotic and anti-inflammatory effects exerted by phosphatidylinositol-3-kinase (PI3K)/Akt signaling pathway and mitogen-activated protein kinase (MAPK) signaling pathway.

Enzymatically preparation of starch nanoparticles using freeze drying technique – Gelatinization, optimization and characterization

Starch nanoparticles (SNPs) in colloidal forms were prepared using enzymatically pretreatment and four different gelatinization methods based on autoclave, microwave, ultrasonication and normal heating with stirring. Furthermore, SNPs in powder form were prepared using freeze drying technique. Results indicated that the formed SNPs using starch solution (1 % W/V) and ultrasonication technique had lowest mean particle size (151 nm) and PDI (0.173), and highest zeta potential (−8.8 mV) values. Optimization procedure using response surface methodology, based on central composite design, indicated that using 1.5 mL of α-amylase and sonication time of 15 min, SNPs with lowest particle size (49.3 nm) and highest zeta potential (−10.8 mV) were produced. Using prepared colloidal solution under optimal conditions, SNPs powder were produced by freeze dryer, adjusted at pressure and temperature of 100 Pa and − 70 °C, for 24 h. Results indicated that formed SNPs powder with squared-shape, had particle size, zeta potential, specific surface area, decomposition temperature of 197 nm, −13.9 mV, 1.9 m2g−1 and 162 °C, respectively. While, for native starch these values were 5018 nm, −6.01 mV, 0.68 m2g−1 and 170.2 °C, respectively. Results revealed that emulsification ability of SNPs powder was three times higher than that of the native starch.

Fabrication and optimization of BSA-PEG-loaded phenethyl isothiocyanate (PEITC) nanoparticles using Box-Behnken design for potential application in subcutaneous infection condition

Phenethyl Isothiocyanate (PEITC) has good pharmacological activities in treating many diseases. However, its application has been limited due to its high hydrophobicity, low dissolution profile, storage stability difficulties, and rapid clearance. The current study aimed to make PEITC-loaded biocompatible low-toxic nanoparticles (NPs) and evaluate their physicochemical features and anti-bacterial potential. BSA and PEG were utilized as biodegradable polymers to fabricate NPs by emulsification procedure, which was then optimized using the Box-Behnken design (BBD). The fabricated optimized PEITC NPs (Run: 12) showed lower mean particle size (185.6 ± 0.8nm), good polydispersity index (0.22 ± 0.02), and Zeta potential (−23.3 ± 0.5mV), with higher entrapment efficiency (94.36 ± 0.16%) and drug loading (80.14 ± 0.13%) suggesting higher colloidal stability and a larger amount of drug can be delivered at the target site. Drug-loaded BSA-PEG NPs showed a prolonged release of PEITC (89.72% in 24 h) from the BSA matrix following the Higuchi model (R2 value = 0.987). The optimized NPs and the free drug were further screened for anti-bacterial activity, where NPs exhibited more potent anti-bacterial activity than free PEITC against all four bacterial strains by presenting higher killing efficiency. In contrast, free PEITC elicited bacteriostatic activity only. Of all the strains, S. aureus alone was more susceptible to drug-loaded NPs/free drugs. These convincing results helped to further exploration for in vivo anti-bacterial activity. Prior to the in vivo bacterial eradication studies, the doses of NPs administered to the animals are ensured for safety and biocompatibility in both in vitro and in vivo studies. Finally, in a S. aureus-induced mice infection model, PEITC NPs showed a very significant decrease in the area of infection (n=4, p < 0.05) than the control, blank NPs and free drug-treated animal groups. The PEITC NPs decreased the bacterial infection to almost negligible, with approximately 15.2 folds decreased bacterial viability than the free drug.

Stability of acidified milk drinks: Comparison of high hydrostatic pressure (HHP) and thermal treatments

There is a search for effective stabiliser activity and alternative pasteurisation techniques for acidified milk drinks (AMD). In the present study, AMD were prepared at three different pH (4.0, 4.5 and 5.0) and high methoxyl pectin (HMP) levels (0.2, 0.5 and 0.8%) by thermal (75 °C, 15 min) and high hydrostatic pressure (HHP) (100, 300 and 500 MPa, 5 min) treatments. To achieve minimum steric stability, 0.5% HMP was required. HMP at 0.5%, pH 4.0 and 4.5, produced high protein solubility (60–70%), low storage sedimentation (10–15%) and mean particle size values in the range of 1.70–3.00 μm for all samples. Heat treatment induced lower particle size variation than HHP treatment. Heat-treated samples also showed lower Turbiscan stability index (TSI) values and smaller delta backscattering (ΔBS) variations. Nonetheless, HHP could replace heat treatment at 0.5% HMP concentration and pH 4.0–4.5.

Effect of steaming and roasting on the quality and resistant starch of brown rice flour with high amylose content

The high-amylose rice cultivar Dodamssal (DDS), a potentially nutritious functional food, contains resistant starch (RS). However, its RS content varies with the processing method used. In this study, heat treatment was used to produce rice powder with enhanced RS content. The rice powder quality was improved by steaming rough rice and brown rice for 30 min and roasting the brown rice at 240 °C for 10 min. Brown rice flour (BRF) made from steamed rough rice and roasted DDS (SRRD) had higher RS content (14%), ratio of fine particle sizes (0–20 μm), and gelatinization degree (GD), as well as lower mean particle size (51 μm) and in vitro glycemic index than did roasted DDS. Contrastingly, BRF prepared from steamed brown rice and roasted DDS with high GD had low RS content (12%) and high mean particle size (56 μm). Hence, SRRD-BRF improves powder quality and may be beneficial for nutritious functional food production.

Evaluation of apparent viscosity and syneresis of dairy dessert enriched of vitamin D 3 ‐loaded nanoniosomes produced by different surfactant

In this study, vitamin D3 in the niosomes based on various surfactants and cholesterol with different ratios was encapsulated using thin layer hydration-sonication method. It was found that the niosomes with Tween-20 and Tween-80 with ratio (80:20, w/w) had the lowest mean particle size and polydispersity index and the highest zeta potential magnitude. After preparing nanosystems containing vitamin D3, they were added to milk dessert, their apparent viscosity and syneresis were investigated. The impacts of different percentages of nano-niosomes used in the formulation of desserts indicated that at constant sugar to grape juice ratios, the apparent viscosity of all samples decreased. Moreover, it was determined that at a constant level of nano-niosomes, increasing grape juice to sugar ratio increased the viscosity of the samples while as the ratio increased the apparent viscosity of samples significantly decreased. Also, changes in the amount of syneresis were significantly dependent on the percentage of nano-niosomes. Practical applications The role of vitamin D3 deficiency in many diseases has been proven. On the contrary, due to the advantages that niosomes have over liposomes to successfully and efficiently delivering nutraceutical and bioactive compounds to the body, in this study, vitamin D3 was loaded in the structure of niosomes. Then, the best structure in terms of the highest yield and percentage of vitamin D3 was formulated to beneficial dairy dessert that prepared with grape juice in order to reduce the adverse effects of vitamin D deficiency in human societies.

Granulométrie des rations et nutrition du ruminant

Cette revue a pour but de dégager les principaux effets nutritionnels quantitatifs des variations de la granulométrie des aliments et des rations des ruminants. La granulométrie est évaluée par tamisages successifs et résumée par le diamètre médian des particules (d50). D’autres paramètres peuvent être utilisés comme la proportion de particules retenue sur un tamis de 2 ou de 4 mm. Ces différents critères ne sont pas linéairement liés. Une réduction d’1 mm de d50 sous les seuils de 3-4 et 1 mm diminue les durées de mastication d’environ 100 et 500 min/j chez les bovins et les ovins respectivement. La granulométrie influence plus les durées de rumination que d’ingestion. Une granulométrie plus fine améliore l’ingestibilité des fourrages pour les ovins ; pour les bovins, les résultats semblent être moins nets. Dans le rumen, le pH et le rapport acétate/propionate sont diminués de 0,5 (si le pH initial est inférieur à 6,2) lorsque d50 diminue de 1 mm en dessous d’un seuil de 3-4 mm chez les bovins. La dégradabilité ruminale des fractions amylacées et protéiques est significativement influencée par le d50 à raison d’environ 12 points de dégradabilité par mm de d50. Les données relatives aux métabolismes protéique et énergétique sont encore trop rares et dispersées pour permettre de dégager des lois quantitatives. Par contre, le taux butyreux du lait chute significativement, d’environ 2 g/kg par mm de d50 en dessous d’une valeur de 4-5 mm.

Effects of source and concentration of neutral detergent fiber from roughage in beef cattle diets on feed intake, ingestive behavior, and ruminal kinetics.

The objectives of this research were to evaluate the effects of source and concentration of α-amylase-treated neutral detergent fiber (aNDF) from roughage on feed intake, ingestive behavior, and ruminal kinetics in beef cattle receiving high-concentrate diets. Six ruminally cannulated Nellore steers (408 ± 12 kg of body weight) were randomly assigned to a 6 × 6 Latin square design with six diets: 10% aNDF from corn silage (10CS); 20% aNDF from corn silage (20CS); or four diets containing 10% aNDF from corn silage and 10% aNDF from one of the following sources: sugarcane (SC), sugarcane bagasse (SCB), soybean hulls (SH), or low oil cottonseed hulls (LOCH). The parameters of passage and degradation kinetics were estimated based on a two-compartmental model with gamma- and exponential-distributed residence times. The nonlinear models were fitted by nonlinear least squares, and a linear mixed-effects model was fitted to all variables measured from the Latin square design that were related to intake, digestibility, digestion kinetic parameters, and residence times. Mean particle size (MPS) between roughage sources (CS, SCB, and SC) and coproducts (SH and LOCH) was affected (P < 0.05). Dry matter intake (DMI) was not affected (P > 0.05) by 20CS, SC, SH, or LOCH. Steers fed 20CS or LOCH diets had 16% and 20% greater DMI, respectively, (P < 0.05) than steers fed 10CS diet. Steers fed SCB consumed the least dry matter (DM). The SH and LOCH diets had lower MPS values (about 8.77 mm) in comparison to 20CS, SCB, and SC diets (about 13.08 mm) and, consequently, affected (P < 0.05) rumen content, ruminal in situ disappearance, nutrient digestibility, and solid fractional passage rate. Chewing time was affected (P < 0.05) by roughage sources and concentration. Lower values of distance travel inside the rumen (min/cm) were observed (P < 0.05) for the SCB and SC diets in comparison with any other diet. Except for SCB, there was no difference (P > 0.05) in rumen fill, among other treatments. Mean daily ruminal pH was not affected (P > 0.05) by 20CS, SCB, SC, and LOCH diets, and it ranged from 6.1 to 6.23. Total short-chain fatty acids concentration was affected (P < 0.05) by roughage source and concentration. Based on our results, we recommend that under Brazilian finishing diets, replacing roughage sources, except for SCB, based on aNDF concentration of the roughage in high-concentrate diets containing finely ground flint corn does not affect DMI.

Particle Size Controlled Magnetic Loss in Magnetite Nanoparticles in RF-Microwave Region

Frequency-dependent complex magnetic permeability (μ*) is used to understand RF-microwave behaviour of magnetic nanoparticles in the frequency range 250 MHz to 3 GHz. Four stable dispersions of Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> nanoparticles with mean size varying between 11 and 16 nm are prepared for this purpose. The effect of mean particle size and external static magnetic field over dielectric properties of magnetic fluid is studied. The results are explained in the aspect of relaxation and resonance as a consequence of interaction of electromagnetic wave with magnetic fluid. The frequency of ferrimagnetic resonance (f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">res</sub> ) and frequency of maximum absorption (f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</sub> ) increases to higher frequency as the mean particle size increases in the fluid. The maximum loss tangent (tan δ) increases, and minimum reflection loss (RL) decreases with mean particle size. The f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">res</sub> , f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</sub> , and the maximum tan δ is observed to increase by 55.6%, 15%, and 25.2%, respectively, and minimum RL is observed to decrease by 34.5% by increasing the mean size of Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> nanoparticles from approximately 11 to 16 nm in magnetic fluid. By the application of external static magnetic field, structural arrangements of Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> nanoparticles can be induced in the fluid. The dielectric properties μ*, tan δ, and RL are reported for increasing field strength 0-915 Oe. The effect of increasing field strength on these properties is also size dependent. As the field strength increases, f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">res</sub> shifts to higher frequencies and the spreading bandwidth is comparatively larger for fluid with the highest mean particle size. The maximum tan δ drops as the field strength increases in the fluid with the highest mean particle size while it raises up to critical field strength then onwards it decreases in the fluid with the lowest mean particle size. The mean particle size and mean anisotropy constant affect the field profiles of dielectric propertiesproperties of the magnetic fluid. This kind of study can be useful for radio-microwave devices like tunable attenuator, EM sheilder, and other microwavemicrowave heating application like hyperthermia.

Central Composite Design for Optimization of Zoledronic Acid Loaded PLGA Nanoparticles

Zoledronic acid (ZA) is one of the drugs used clinically for the treatment of osteoporosis, and its therapeutic effect is due to the inhibition of osteoclastic cells leading to bone resorption. The aim of this study is developing an optimization method for poly(lactide-co-glycolide) (PLGA) nanoparticles of ZA which is intended for local application to enable guided bone regeneration. Three formulation parameters (ZA content, PLGA/Pluronic F68 ratio, and organic to aqueous phase ratio) were optimized to evaluate their effects on particle size (Y1), polydispersity index (PDI) (Y2), zeta potential (Y3), and entrapment efficiency (Y4) utilizing central composite experimental design (CCD). Interaction among components was studied by Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), and X-ray diffraction analysis. Morphology of nanoparticles was visualized with transmission electron microscopy (TEM). Stability studies of nanoparticles were also carried out for 6 months. The results revealed that formulation parameters significantly affected Y1, Y2, Y3, and Y4 of the nanoparticles. The developed quadratic model showed high correlation (R2 > 0.84) between predicted response and evaluated parameters. Spherical nanoparticles with low mean particle size ( 39.54%) were obtained with the optimized nanoparticle formulation and maintained colloidal stability for 6 months. The use of CCD for the optimization of ZA-loaded PLGA nanoparticles has provided accessibility to the formulation with optimum properties with less experimental procedure and therefore presents an important model for predicting the properties of nanoparticles prepared with PLGA polymer commonly used in the field of drug delivery.

A quality-by-design study to develop Nifedipine nanosuspension: examining the relative impact of formulation variables, wet media milling process parameters and excipient variability on drug product quality attributes

Wet milling is a multifunctional and the most common method to prepare a drug nanosuspension for improving the bioavailability of poorly water soluble drugs. A suitable way of preparing a high drug-loaded nifedipine nanosuspension using wet stirred media milling was investigated in the present study. Nifedipine, a poorly water soluble drug, was selected as a model drug to enhance its dissolution rate and oral bioavailability by preparing an appropriate crystalline nanosuspension. Process parameters, such as milling media volume, milling speed and milling time, were optimized using the one variable at a time (OVAT) approach. A similar method was used to select an appropriate polymeric stabilizer and a surfactant from different categories of polymeric stabilizers (HPC SL, HPC SSL Soluplus®, Kollidon® VA 64 and HPMC E 15) and surfactants (Poloxamer 407, Kolliphor TPGS and Docusate sodium). A systematic optimization of critical formulation parameters (such as drug concentration, polymer concentration and surfactant concentration) was performed with the aid of the Box-Behnken design. Mean particle size, polydispersity index and zeta potential as critical quality attributes (CQAs) were selected in the design for the evaluation and optimization of the formulation and validation of the improved product. The nifedipine nanosuspension that was prepared using HPC and poloxamer 407 was found to be most stable with the lowest mean particle size as compared with the formulations prepared using other polymeric stabilizers and surfactants. The optimized formulation was further spray-dried and characterized using the Fourier Transform Infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), polarized light microscopy (PLM) and in-vitro dissolution study. Results have shown no interaction between the drug particles and stabilizers, nor a reduction in the crystallinity of drug, nor an increase in the saturation solubility and rapid in vitro dissolution as compared with pure nifedipine crystals. Thus, the current study supports the suitability of the wet stirred media milling method and a combination of HPC SSL and poloxamer 407 as stabilizers for the preparation of nifedipine nanosuspension.

Influence on properties and phase structure of single gas-phase reactor made impact polypropylene copolymers

Impact polypropylene copolymers (IPC) are materials important for many commercial applications. These materials are usually synthetized by different methods involving two consecutive reactions: in liquid, gas or liquid-gas phase. This work presents a method of synthesis in a laboratory scale based on two sequential steps in only one reactor in gas phase. Variables such as H2 addition, reaction time, and composition during the second step were studied, and their influence on the formation of propylene-ethylene copolymer materials with different properties was analyzed. The IPC materials so obtained were characterized by analytical temperature rising elution fractionation (TREF), calorimetric methods (DSC), 13C nuclear magnetic resonance (13C NMR), gel permeation chromatography with an infrared detector (GPC-IR5), Charpy impact, and scanning electron microscopy (SEM).The isotactic polypropylene matrix (iPP) obtained in the first step of the gas-phase process displays spherical morphology and lower mean particle size than those obtained in the liquid-phase process, even though the polymer grains experimented a certain tendency to agglomerate.In particular, hydrogen addition caused a significant decline in the catalyst productivity and dramatically shortened the length of the propylene homopolymer chains. Similarly, the presence of hydrogen on the synthesis of ethylene-propylene copolymers was demonstrated to lead to materials with very low molecular weight, low ethylene incorporation, and rubbery phases irregularly distributed along the iPP matrix and therefore with poor impact properties.On the other hand, ethylene-propylene copolymers synthesized without hydrogen yielded a suitable combination of molecular weights and molecular weight distribution that can contribute to good polymer processing and were proven to incorporate adequate amounts of ethylene mainly randomly distributed into the iPP matrix. SEM measurements revealed that the amorphous rubbery phase was homogeneously dispersed in the iPP matrix, and the Charpy test allowed to rank these materials as IPC.Finally, fractionation of IPC materials by preparative TREF provided information about the microstructure formation. Subsequent studying of molecular weights and composition of the fractions by GPC-IR, analytical TREF, and DSC measurements based on the ethylene-propylene composition and ethylene distribution in the molar mass molecules was shown to enable the design of IPC materials. Additionally, the optimal IPC material was compared with the best IPC using liquid-phase polymerization, and the results showed that the range of ethylene-propylene composition, as well as the ethylene distribution in IPC molar mass molecules, correlated with IPC mechanical behavior.

Pure phase BiFeO3 thin films sputtered over Si: A new route towards high magnetization

We have investigated the structural and magnetic properties of BiFeO3 (BFO) thin films grown over (100)-oriented Si substrates by rf magnetron sputtering in a new route under O2 free low pressure Ar atmosphere. Single-phase BFO films were deposited in a heated substrate and post-annealed in situ. The new routed allows high deposition rate and produce polycrystalline BFO pure phase, confirmed by high resolution X-ray diffraction. Scanning electron and atomic force microscopy reveal very low surface roughness and mean particle size of 33 nm. The BFO phase and composition were confirmed by transmission electron microscopy and line scanning energy-dispersive X-ray spectroscopy in transmission electron microscopy mode. The surface chemistry of the thin film, analyzed by X-ray photoelectron spectroscopy, reveals the presence of Fe3+ and Fe2+ in a 2:1 ratio, a strong indication that the film contains oxygen vacancies. An hysteretic ferromagnetic behavior with room temperature high saturation magnetization ∼165 × 103 A/m was measured along the film perpendicular and parallel directions. Such high magnetization, deriving from this new route, is explained in the scope of oxygen vacancies, the break of the antiferromagnetic cycloidal order and the increase of spin canting by change in the surface/volume ratio. Understanding the magnetic behavior of a multiferroic thin films is a key for the development of heterogeneous layered structures and multilayered devices and the production of multiferroic materials over Si substrates opens new possibilities in the development of materials that can be directly integrated into the existent semiconductor and spintronic technologies.

Hybrid waterborne polyurethane/acrylate dispersion synthesized with bisphenol A-glicidylmethacrylate (Bis-GMA) grafting agent

New hybrid waterborne polyurethane/acrylate (WPUA) dispersions were synthesized by grafting with bisphenol-A-glycidyl dimethacrylate (Bis-GMA) in order to create chemical bonds between polyurethane and polyacrylate chains. WPUAs were prepared by using prepolymer self-emulsifying method with isophorone diisocianate, poly(tetramethylene ether) glycol, dimethylolpropionic acid, and ethylenediamine in the polyurethanic part, and styrene and n-butyl acrylate in the polyacrylate portion. A redox pair system consisting of ascorbic acid and hydrogen peroxide were used as polymerization initiator. The particle size of the WPUA dispersions increased by increasing the Bis-GMA/1,4 butanediol ratio, stable dispersions of negatively charged particles were obtained, and they had low viscosity (around 1.3 mPa.s) in spite of the relatively high solids content (27 wt%). Higher thermal stability was obtained when 50 mol% of chain extension was carried out with Bis-GMA. Using Bis-GMA/BD, instead of HEMA, as grafting agent, allowed obtaining hybrid polyurethane dispersions with the lowest mean particle size and better colloidal stability. Finally, the addition of 35 wt% Bis-GMA increased noticeably the cross-cut adhesion of polyurethane/acrylate coatings to stainless steel.

Nanofiber cellulose di- and tri-acetate using ferric chloride as a catalyst promoting highly efficient synthesis under microwave irradiation

ABSTRACTAn efficient method for the generation of cellulose di- and tri-acetate nano-structures is obtained through testing ferric chloride hydrate (FeCl3·6H2O) as a valuable Lewis acid catalyst with acetic anhydride under microwave irradiation. Our target was to evaluate the effects of the reaction conditions on the products' properties such as surface area and particle size distribution. It was found that changes in the degree of substitution (DS), the surface area, the degree of polymerization and the particle size distribution of the products correlated with reaction conditions. Cellulose tri-acetate nanofibers with DS of 2.94 with 98.03% yield was prepared using 200 mg of FeCl3·6H2O, 25 ml of Ac2O and 4 minutes of microwave irradiation. Also, cellulose di-acetate nanofibers were prepared with DS values ranged between 2.37 and 2.72 with yield ranged between 78.92 and 90.58%. The percentage of acetyl groups (Ac%) as well as the BET specific surface area, total pore volume, mean pore diameter, mono layer volume and the mean particle size of the products were determined. The maximum specific surface area obtained for the acetylated cellulose was about ten times larger than that measured for the commercial cotton cellulose and about six times larger than that of the commercial cellulose acetate. The lowest mean particle size (34.90 nm) was about eleven times smaller than the mean particle size of the commercial cellulose acetate (394 nm). The present work has proved that FeCl3·6H2O was a highly active catalyst for the esterification of cellulose with unexpected yields and for the formation of nanofibers with low molecular weight.

Nanoindenting the Chelyabinsk Meteorite to Learn about Impact Deflection Effects in asteroids

Abstract The Chelyabinsk meteorite is a highly shocked, low porosity, ordinary chondrite, probably similar to S- or Q-type asteroids. Therefore, nanoindentation experiments on this meteorite allow us to obtain key data to understand the physical properties of near-Earth asteroids. Tests at different length scales provide information about the local mechanical properties of the minerals forming this meteorite: reduced Young’s modulus, hardness, elastic recovery, and fracture toughness. Those tests are also useful to understand the potential to deflect threatening asteroids using a kinetic projectile. We found that the differences in mechanical properties between regions of the meteorite, which increase or reduce the efficiency of impacts, are not a result of compositional differences. A low mean particle size, attributed to repetitive shock, can increase hardness, while low porosity promotes a higher momentum multiplication. Momentum multiplication is the ratio between the change in momentum of a target due to an impact, and the momentum of the projectile, and therefore, higher values imply more efficient impacts. In the Chelyabinsk meteorite, the properties of the light-colored lithology materials facilitate obtaining higher momentum multiplication values, compared to the other regions described for this meteorite. Also, we found a low value of fracture toughness in the shock-melt veins of Chelyabinsk, which would promote the ejection of material after an impact and therefore increase the momentum multiplication. These results are relevant to the growing interest in missions to test asteroid deflection, such as the recent collaboration between the European Space Agency and NASA, known as the Asteroid Impact and Deflection Assessment mission.

Characterization of the mesostructural organization of cement particles in fresh cement paste

Comparative study on the mesostructures of fresh cement paste (FCP) in different dispersion mediums was carried out aiming at characterizing the structural organization of cement particles in FCP at a mesoscopic scale and establishing the correlation of mesostructure with rheological properties. For the first time, Morphologi G3 was adopted to in-situ characterize the mesostructure of FCP. Several dispersion mediums including air, deionized water, ethanol and an aqueous solution of ethanol were chosen to study the dispersion of cement particles in the selected mediums. Superplasticizers, as dispersing aids for cement particles, were added to change the dispersion of cement particles. Results show that Morphologi G3 with the high sensitivity and the high resolution is a powerful tool for in-situ characterization of the mesostructure of FCP by providing high-quality images associated with structural parameters. The structural parameters including particle size, circularity and fractal dimension of particle spatial distribution (Dpd) allow to quantitatively characterize the organization of cement particles in FCP at a mesoscopic scale, through which the relationship between the mesostructure and the rheological behavior of FCP was established. Higher fluidity signifies larger Dpd and circularity but a lower mean particle size. Moreover, the mean particle size and Dpd are more sensitive to indicate the fluidity change.

Effect of Ultrasound Treatment on Particle Size, Rheology, Microstructure, Colour and Water Holding Capacity of a Soy-Based Dessert

Power ultrasound has vast potential in the food industry; however, there are no works on its effects on desserts. Thus, the objectives of this study were to investigate the effect of ultrasound as a mixing or homogenization step or as a tool to modify the texture of the soy-based desserts without reformulating the product. Different properties of soybased desserts were evaluated and the behaviour of the samples during storage under refrigeration (60 days) was monitored. The samples were treated with an ultrasound probe for 1, 3, and 5 min. The treated samples showed lower mean particle size, lower consistency index, higher flow index, and clear difference in their microstructure. However, water holding capacity and particle size dispersion index values did not differ among untreated and treated soy based desserts for 1 and 3 minutes, and none of the treatments caused visible colour differences among the samples. Periodically, rheological properties, pH, soluble solids content, colour, particle size, and water holding capacity were determined. After 60 days, all evaluated properties differed significantly, except for the pH.