Effect of PMMA Molecular Weight on Its Localization during Crystallization of PVDF in Their Blends

In miscible crystalline/amorphous polymer blends, the exclusion behaviors of the latter with various molecular weights during the crystallization of the former were investigated by the combination of SAXS and DSC by taking a PVDF/PMMA blend as an example. The ratio between internal crystallinity from SAXS and overall crystallinity of the entire blend from DSC was employed to characterize the exclusion of PMMA. Our results indicate that the molecular weight of the amorphous component produces a remarkable influence on the diffusion coefficient (D) and the crystal growth rate (G) of the crystalline component. There are both inter-lamellar and inter-fibrillar structures when PVDF blended with lower-molecular-weight PMMA. With increasing molecular weight of PMMA, the decrease in crystal growth rate (G) dominates the enhanced exclusion behaviors of PMMA, resulting in bigger pores after extraction. Our results are significant not only for the basic understanding of crystallization in polymer blends, but also for the fabrication and structure control of porous structures based on crystallization templates.

The Use of ZrO2 Waste for the Electrolytic Production of Composite Ni–P–ZrO2 Powder

Ni–P–ZrO2 composite powder was obtained from a galvanic nickel bath with ZrO2 powder. Production was conducted under galvanostatic conditions. The Ni–P–ZrO2 composite powder was characterized by the presence of ZrO2 particles covered with electrolytical nanocrystalline Ni–P coating. The chemical composition (XRF method), phase structure (XRD method) and morphology (SEM) of Ni–P–ZrO2 and the distribution of elements in the powder were all investigated. Based on the analyses, it was found that the obtained powder contained about 50 weight % Zr and 40 weight % Ni. Phase structure analysis showed that the basic crystalline component of the tested powder is a mixed oxide of zirconium and yttrium Zr0.92Y0.08O1.96. In addition, the sample contains very large amounts of amorphous compounds (Ni–P). The mechanism to produce the composite powder particles is explained on the basis of Ni2+ ions adsorption process on the metal oxide particles. Current flow through the cell forces the movement of particles in the bath. Oxide grains with adsorbed nickel ions were transported to the cathode surface. Ni2+ ions were discharged. The oxide particles were covered with a Ni–P layer and the heavy composite grains of Ni–P–ZrO2 flowed down to the bottom of the cell.

Effects of Zoledronic Acid on Bone Structure and Organization of Nanocomposites in Rats with Glucocorticoid-Induced Osteoporosis

Continuous use of methylprednisolone (Mps) is one of the most common causes of secondary osteoporosis resulting in alterations of the skeleton microstructure and increased fracture risk. The aim of the research was to assess the influence of zoledronic acid on mineral mass, micro- and nanostructure of the bones in rats, which received glucocorticoids. Wistar rats were randomly divided into three groups: vehicle control, the introduction of methylprednisolone, 3 mg/kg/day (Mps), and Mps combined with zoledronic acid, 0.025 mg/kg (Mps+Zol.). The relative amount of a crystalline component and collagen in the bones was detected by means of X-ray diffraction, microstructure, and calcium level through atomic absorption spectroscopy. Methylprednisolone caused a decrease in the amount of a mineral component in the femoral neck (to -39.8%) in group Mps than vehicle control. It should be emphasized that the introduction of Zol. did not allow a significant decrease in a mineral component of the bone during the experiment (-11.7% on the 24th day) compared with Mps group, and indices were almost at the same level as in the control group. Zoledronic acid can partially inhibit harmful consequences of glucocorticoids for bone structure in rats and improve mineralization without impairment of crystal parameters of hydroxyapatite lattice.

Effects of mechanical stimuli on structure and organization of bone nanocomposites in rats with glucocorticoid-induced osteoporosis

Objective. Clinical use of glucocorticoids is a frequent cause of secondary osteoporosis, which reduces the mineral density of bones and results in pathological fractures. Mechanical stimulation as non-physiological high-frequency vibration with low acceleration prevents the loss of a crystalline component and stimulates the anabolic remodeling of the bone. The aim of the present research was to assess the impact of mechanical vibration on the bone structure in rats, which received glucocorticoids. Methods. Wistar rats were randomized into three groups: Vehicle control (Veh), Methylprednisolone sodium succinate (Mps), and Mps combined with whole-body vibration (WBV). Rats of Mps+WBV and Mps groups received 3 mg/kg/day of methylprednisolone every other day for 24 weeks and rats of Veh group received 0.9% saline (sodium chloride). The group of rats Mps+WBV was subjected to WBV for 30 minutes per day for five days a week with parameters 0.3 g and frequency 50 Hz. Relative amount of crystalline component and collagen in the bones was determined by X-ray diffraction (XRD) and calcium level – by atomic absorption spectroscopy. Bone tissue metabolism was assessed by determining the concentration of markers, in particular osteocalcin and Tartrate-resistant acid phosphatase (TRAP5b). Results. Glucocorticoids induced a considerable increase in the rats body mass (+13%) and decreased the content of mineral component in the femoral neck (–17%) in Mps group compared with Veh. The process of the bone metabolism was significantly accelerated, which is proven by an increased level of remodeling markers. It should be mentioned that WBV did not allow significant decrease in mineral component of the bone to 16th week of the experiment compared with Mps group, although these parameters did not achieve the indices in the Vehicle control group (–10%). Our investigation allows to suggest that mechanical high-frequency vibration of low intensity can partially inhibit the harmful consequences of glucocorticoids on bone structure in rats. Despite the positive impact of vibration on the bone tissue after Mps introduction in the 8th–16th week, this influence was not statistically reliable in the 24th week of the experiment. Conclusions. The results of our investigation on animal model indicate that non-physiological vertical mechanical vibrations are an effective means to prevent loss of a mineral bone component during treatment with glucocorticoids.

Synthesis of Glibenclamide-Oxalic Acid Cocrystal using ThermalSolvent-Free Method

Solubility is an important parameter affecting the bioavailability of drugs. The solubility of an active pharmaceutical ingredient (API) could be improved through the formation of cocrystal, which is a crystalline complex composed of two or more different molecules. Glibenclamide (GCM) is an API with poor solubility in water, which belongs to class II, characterized as highly permeable with low solubility. Therefore, this study aimed to synthesize and characterize the cocrystal of GCM-oxalic acid (OA) using the melting method. The interaction between GCM-OA complexes was predicted using the in silico method. Also, the cocrystal complexes were characterized by differential scanning calorimetry (DSC), infrared (IR) spectrophotometry, and powder X-ray diffraction (PXRD), as well as, through solubility and dissolution tests. The result showed that GCM and OA have the potential of forming cocrystal through the in silico method. Also, the cocrystal of GCM-OA with a molar ratio 1:2, significantly improved the solubility and dissolution profile of GCM. In addition, the spectrum IR of cocrystal exhibited a shifting peak at 1,700 cm-1 indicating the presence of intermolecular interaction between GCM and OA. Furthermore, the DSC and PXRD analyses showed a new single endothermic peak and new diffraction peak pattern, respectively, indicating the formation of a new crystalline component.

THE EFFECT OF LONG EXPOSURE OF BIRCH, ASPEN AND PINE SAWDUST IN WATER ON YIELD AND SPECIF-IC SURFACE AREA OF THE CARBON PRODUCT

The article presented researches concerning the effect of prolonged exposure in water of wood of different species - birch, aspen and pine, on the formation of carbon materials structure during carbonization. The possibility of using wood waste of different species, subject to long exposure in water, to obtain more porous carbon materials than using original wood is shown. It was established that the aging of different species in water stimulates the disclosure of the porous structure of the carbon product. This particularly applies to the carbon product of pine wood, the specific surface area which increases from 10 to 455 m2 g-1. It was shown that the yield of the carbon product, increases by 15–25 wt.% using wood prolonged exposure in water. Using XRD and electron microscopy, features of the structural transformation of birch, aspen and pine wood subjected to water treatment were revealed. Prolonged exposure of different wood species in the water affects the degree of crystallinity of the cellulose fiber in wood. The crystalline component of pine is exposed to the greatest destruction under the action of water. It was noted that after water treatment of wood, the part of the amorphous component in the carbon product increases, regardless of the type of wood used.

The Influence of Temperature of Electrodeposition on the Electrochemical Properties of Ni+MoS2 Composite Coatings

The Ni+MoS2composite coatings were prepared by electrodeposition under galvanostatic conditions from the Ni-plating bath containing suspended MoS2powder (100 mesh). Investigations of hydrogen evolution reaction (HER) were carried out using steady-state polarization measurements and electrochemical impedance spectroscopy (EIS) in 5 M KOH solution on the coatings obtained at 30, 40, and 50°C. It was found that the kinetics of the HER on the Ni+MoS2coatings decreases with the increase in the electrodeposition temperature of the coatings. This effect is attributed to decreasing content of MoS2(from 26.4 to 18.0 wt.%) embedded into the Ni matrix as composite crystalline component having the electrocatalytic properties towards the HER and/or surface development of the coatings. The higher amount of MoS2was embedded, the more porous electrodes containing pear-shape pores on the surface were produced what was detected by EIS.

Physical and Chemical Characterization of Ni+MoO2 Composite Electrocoatings

This work deals with the development of new electrochemical ways to improve the cathode activity towards hydrogen evolution reaction. Anin situcomposite electrodeposition technique has been proposed to obtain the porous Ni+MoO2coatings by simultaneous co-deposition of Ni and MoO2onto a Cu substrate from a nickel plating bath containing 10 g dm-3of MoO2powder suspended by magnetic stirring. Electrodeposition was conducted at 30°C at the deposition current density ofjd= 50-250 mA cm-2. SEM, EDS, and XRD measurements, were applied for physical and chemical characterization of the obtained coatings. It was found that by controlling the deposition conditions it was possible to obtain porous Ni+MoO2coatings containing from 10 to 15 at.% of MoO2. The XRD results confirmed their diphase structure with a polycrystalline Ni matrix into which a crystalline component in the form of MoO2particles was built-in.

Identification of α-phase crystallization Pigment Red 254 in artist's paints by powder x-ray diffraction

Diketopyrrolopyrrole (DPP) is a pigment widely used in modern paints for industrial and artistic applications. Identification of this pigment in paint for art authentication and forensics has previously been accomplished with gas chromatography/mass spectrometry or Laser Raman. Three commercial artist's paints containing DPP were analyzed by x-ray diffraction (XRD). Alpha phase DPP was identified in two of the samples, barite extender the only crystalline component identified in the other sample. In conclusion, XRD analysis of paint samples can identify DPP, as can other organic analyses, but has the advantage of being non-destructive and also identifying the crystal structure. However, the fact that in one sample only extender could be identified does impose some limitations on the analysis of paints.