Crystallinity Research Articles

Thermo-mechanical performance of nanostructured electrospun composites produced from poly(vinyl alcohol) and cellulosic compounds for potential uses as wound dressings

The purpose of this research was to analyze the morphology, thermal and mechanical properties of poly(vinyl alcohol) (PVA)-based electrospun mats reinforced with cellulose acetate (CA) or cellulose nanocrystalline (CNC) for potential applications in wound dressings. Bead-free and water-stable electrospun nanofibers made of blends of PVA and CA or CNC were successfully produced and crosslinked with glutaraldehyde vapor. Crosslinking slightly increased the nanofibers' diameters in order of 43 and 13% for 80/20 PVA/CA and PVA/CNC electrospun mats, respectively, while maintaining their bead-free morphology. Thermogravimetry (TGA) and differential scanning calorimetry (DSC) evaluations were employed to determine the miscibility and the thermal response of the uncrosslinked and crosslinked mats, reporting a reduction in mass loss upon addition of CA and CNC and upon crosslinking process. Polymers' powder and mats (before and after crosslinking) crystallinity was assessed by X-ray diffraction analysis (XRD). Crosslinked mats experienced a slight reduction in crystallinity compared to the uncrosslinked. Static and dynamic tensile strength tests revealed that CA and CNC doped mats enhanced the Young's modulus and lowered deformation at failure compared to pristine PVA electrospun mats. Data from storage modulus (E′) demonstrated the strength of the physical interactions formed between PVA and the cellulosic derivatives (either before and after crosslinking), highlighting the stiffness of CA (231.58 MPa for the 80/20 mat) and, particularly, CNC (742.04 MPa for the 80/20 mat). This research uncovered important information concerning the chemical and physical relation between polymeric matrices and additives, essential for the proper selection of materials for wound dressings production.

Structural, optical and Judd-Ofelt analyses of Gd2-xEuxSi2O7 nanocrystals for lighting applications

A series of Eu3+-doped silicate-based red light-emitting nanocrystalline materials is fabricated via the solution combustion technique. Triclinic crystalline powders with a P-1 space group are formed containing irregularly sized grains. Three-lifetime values indicates the presence of three different local environments surrounding the Eu3+ ion. Upon near-UV excitation, the photoluminescence (PL) spectrum shows a red emission owing to the electronic band at ∼612 nm, consistent with the electronic transition 5D0 → 7F2. The energy bandgap is probed using diffuse reflectance spectroscopy. The critical distance between adjacent Eu3+ ions was evaluated to be ∼18.70 Å and multipolar exchanges were found accountable for the concentration quenching. The obtained chromaticity coordinates fall in the red regime of the CIE (1931) triangle, which replicates the potency of designated nanomaterials in the design and architecture of R-G-B (red–green–blue) phosphor-based LEDs.

Preparing of Nano-Hydroxyapatite from Seashell and Mixed with Gold to Repair Bony Defect of Mandibular Bone in Rabbits

The objectives of the present study were undertaken to prepared hydroxyapatite powder from seashell and convert this to nano size and then added to gold nanoparticles. Materials and Methods: The seashells was cleaned and the phosphoric acid was added. The product was inserted in oven then calcined in the muffled furnace, to evaporate CO2 and getting the white crystalline powder which indicated presence of hydroxyapatite. This powder was converted to nanoparticle. Gold 1% mixed with prepared seashell nano hydroxyapatite. The characteristics of the prepared nano hydroxyapatite from seashell, were studied by the FTIR infrared spectrophotometer. The most biocompatible nano hydroxyapatite estimation by chemical test and examine prepared nano hydroxyapatite from seashell alone or when mixed with gold 1% in vivo to detect the effectiveness on reparing bone defect in mandibulare rabbits. Results: The results of an infrared measurement (FTIR Spectroscopy) for prepared nano hydroxyapatite showed that the chemical structure and band have the same FTIR spectrum of standard nano hydroxyapatite and have the same nano traits as the chemical test showed a yellow precipitation consisting in the nHA seashells. As an indication of biocompatibility and increase Bone Mineral Density by repairing bone defect in rabbits. And when added gold to nano hydroxyapatite, increased the efficacy of bone remodeling and repair bone. Conclusions: The possibility of preparing nanoparticles for hydroxyapatite from seashell are simple and inexpensive feedstock's and can be successfully produced by chemical precipitation technology from seashells with a phosphoric acid solution.

Flexible composite films with enhanced piezoelectric properties for energy harvesting and wireless ultrasound-powered technology

In the last years, ultrasound energy harvesting has emerged as the most promising technique for wireless power supply of implanted medical devices. These devices require flexible piezoelectric materials with high piezoelectric response in the ultrasonic range. Here we report on bio-compatible NBT-BT/PVDF flexible composites, with variable filler content up to 50 vol%, prepared by a properly designed and optimized process, which incorporates in a complex connectivity pattern fully sintered NBT-BT crystalline powders in a PVDF matrix. The dielectric constant of the flexible composites increased from 10 of pure PVDF polymer to 110 of composite films with 50 vol% NBT-BT content, while the high frequency piezoelectric d33 constant increased from 0.2 pC/N to 33 pC/N for the same samples. The composite with 50 vol% NBT-BT exhibits the figure of merit for the harvested ultrasound energy d33g33 ≅ 1.54 × 10−12 m3/J, which is comparable to the figure of merit for the NBT-BT piezoelectric ceramic (1.8 × 10−12 m3/J) and higher than other reported results for random composites. Based on these results, this study provides an easy method to fabricate random flexible piezoelectric composites with enhanced high frequency piezoelectric response and high energy density harvested from an ultrasound source.

Porous Salts Containing Cationic Al24 -Hydroxide-Acetate Clusters from Scalable, Green and Aqueous Synthesis Routes.

The solution chemistry of aluminum is highly complex and various polyoxocations are known. Here we report on the facile synthesis of a cationic Al24 cluster that forms porous salts of composition [Al24 (OH)56 (CH3 COO)12 ]X4 , denoted CAU-55-X, with X=Cl- , Br- , I- , HSO4 - . Three-dimensional electron diffraction was employed to determine the crystal structures. Various robust and mild synthesis routes for the chloride salt [Al24 (OH)56 (CH3 COO)12 ]Cl4 in water were established resulting in high yields (>95 %, 215 g per batch) within minutes. Specific surface areas and H2 O capacities with maximum values of up to 930 m2 g-1 and 430 mg g-1 are observed. The particle size of CAU-55-X can be tuned between 140 nm and 1250 nm, permitting its synthesis as stable dispersions or as highly crystalline powders. The positive surface charge of the particles, allow fast and effective adsorption of anionic dye molecules and adsorption of poly- and perfluoroalkyl substances (PFAS).

CrB-type, ordered α-MnB: Single crystal structure and spin-canted magnetic behavior

Manganese monoboride has a low- (α) and a high-temperature (β) modification, as well as a defect-rich low-temperature variant (α′). The crystal structure (FeB-type structure, s.g. Pnma) and properties of high-temperature MnB are well-known. In this work, single crystals were grown via chemical vapor transport reactions, both of β-MnB and the low-temperature modification, α-MnB. This allowed for determining the crystal structure of defect-free α-MnB [CrB-type structure, s.g. Cmcm, a = 3.0098(6) Å, b = 7.6390(2) Å, and c = 2.94620(6) Å]. Furthermore, α′-MnB, the stacking fault-dominated CrB-variant, was obtained as crystalline powder and characterized by X-ray powder diffraction and transmission electron microscopy. Direction-resolved measurements of the magnetic properties of α-MnB revealed spin-canted magnetic behavior along c and ferromagnetism along a and b with a Curie temperature of 456 K; ferromagnetic β-MnB has a Curie temperature of 568 K.

Powder X-ray diffraction intensities of corundum calculated by conventional and density functional theory methods and extracted by deconvolutional treatment on experimental data

Least-squares analysis on the diffraction intensity values certified for NIST SRM676a and SRM1976c α-Al2O3 (corundum) have shown that the intensities of SRM1976c can be simulated by the March-Dollase preferred orientation model along the (001)-direction. Diffraction intensities of randomly oriented corundum crystallites have been calculated from electron density data obtained by conventional and density functional theory (DFT) calculations, on the assumption of independent and similar atomic displacements for Al and O atoms. The results of DFT calculations support that the strongest peak of randomly oriented α-Al2O3 crystalline powder should be 113-reflection, though the intensities simulated by DFT calculations are not closer to NIST SRM676a intensities than those expected for a fully ionized model ${\rm Al}_2^{3 + } {\rm O}_3^{2-}$. Diffraction data of two types of relatively fine (nominally 2–3 μm and ca 0.3 μm) α-Al2O3 powder have been collected and processed by a deconvolutional treatment (DCT). Integrated peak intensities extracted from the DCT data by an individual peak profile fitting method also support that the 113-reflection is the strongest reflection of randomly oriented α-Al2O3 crystalline powder.

Identification of erythropoietin mimetic peptide 1 linear form in a sealed vial and its administration study in horses for doping control purpose.

The erythropoietin mimetic peptide 1 linear form (EMP1-linear), GGTYSCHFGPLTWVCKPQGG-NH2 , was identified in an unknown preparation consisting of white crystalline powder contained in sealed glass vials using ultrahigh performance liquid chromatography-high-resolution mass spectrometry (UPLC-HRMS). The white crystalline powder, allegedly used for doping racehorses, was found to contain around 2% (w/w) of EMP1-linear. EMP1-linear can be cyclised in equine plasma at physiological temperature of 37°C by forming an intramolecular disulfide bond to give EMP1, which is a well-known erythropoiesis stimulating agent that can bind to and activate the receptor for cytokine erythropoietin (EPO). Thus, EMP1-linear is a prodrug of EMP1, which is a performance-enhancing doping agent that can be misused in equine sports. In order to identify potential target(s) for detecting the misuse of EMP1-linear in horses, an in vitro metabolic study using horse liver S9 fraction was performed. After incubation, EMP1-linear mainly existed in its cyclic form as EMP1, and four N-terminus truncated in vitro metabolites TYSCHFGPLTWVCKPQGG-NH2 (M1), SCHFGPLTWVCKPQGG-NH2 (M2), WVCKPQGG-NH2 (M3) and VCKPQGG-NH2 (M4) were identified. An intravenous administration study with the preparation of white crystalline powder containing EMP1-linear was also conducted using three retired thoroughbred geldings. EMP1 was detectable only in the postadministration plasma samples, whereas the four identified in vitro metabolites were detected in both postadministration plasma and urine samples. For controlling the misuse of EMP1-linear in horse, its metabolite M3 gave the longest detection time in both plasma and urine and could be detected for up to 4 and 27 h postadministration, respectively.

Efficient radioactive gas detection by scintillating porous metal–organic frameworks

Natural and anthropogenic gas radionuclides such as radon, xenon, hydrogen and krypton isotopes must be monitored to be managed as pathogenic agents, radioactive diagnostic agents or nuclear activity indicators. State-of-the-art detectors based on liquid scintillators suffer from laborious preparation and limited solubility for gases, which affect the accuracy of the measurements. The actual challenge is to find solid scintillating materials simultaneously capable of concentrating radioactive gases and efficiently producing visible light revealed with high sensitivity. The high porosity, combined with the use of scintillating building blocks in metal–organic frameworks (MOFs), offers the possibility to satisfy these requisites. We demonstrate the capability of a hafnium-based MOF incorporating dicarboxy-9,10-diphenylanthracene as a scintillating conjugated ligand to detect gas radionuclides. Metal–organic frameworks show fast scintillation, a fluorescence yield of ∼40%, and accessible porosity suitable for hosting noble gas atoms and ions. Adsorption and detection of 85Kr, 222Rn and 3H radionuclides are explored through a newly developed device that is based on a time coincidence technique. Metal–organic framework crystalline powder demonstrated an improved sensitivity, showing a linear response down to a radioactivity value below 1 kBq m−3 for 85Kr, which outperforms commercial devices. These results support the possible use of scintillating porous MOFs to fabricate sensitive detectors of natural and anthropogenic radionuclides.

The Elusive Structure of Levocetirizine Dihydrochloride Determined by Electron Diffraction.

Levocetirizine is an orally administrated, second-generation antihistaminic active pharmaceutical ingredient that has been used to treat allergy symptoms and long-term hives for over 25 years. Despite the wide use of this compound, its crystal structure has remained unknown. Here we report the application of 3D electron diffraction (3D ED)/microelectron diffraction (MicroED) to determine the crystal structure of Levocetirizine dihydrochloride directly from crystalline powders extracted from commercially available tablets containing the compound. We also showcased the utility of dynamical refinement to unambiguously assign absolute configuration. The results highlight the immense potential of 3D ED/MicroED) for structure elucidation of components of microcrystalline mixtures that obviates the need to grow large-size single crystals and the use of complementary analytical techniques, which could be important for identification as well as for primary structural characterization.

Levocetirizin‐Dihydrochlorid: Die Aufklärung einer lang verborgenen Struktur mittels Elektronenbeugung

AbstractLevocetirizin ist ein oral verabreichtes Antihistaminikum der zweiten Generation, dass seit über 25 Jahren zur Behandlung von Allergiesymptomen und langanhaltender Nesselsucht eingesetzt wird. Trotz der weiten Verbreitung dieser Verbindung war ihre Kristallstruktur bisher unbekannt. Hier berichten wir über die Anwendung der 3D‐Elektronenbeugung (3D ED)/Mikrokristallbeugung (MicroED) zur Bestimmung der Kristallstruktur von Levocetirizindihydrochlorid direkt aus kristallinen Pulvern, handelsüblicher Tabletten, die diese Verbindung enthalten. Weiterhin zeigen wir auch den Nutzen der dynamischen Verfeinerung zur eindeutigen Zuordnung der absoluten Konfiguration. Die Ergebnisse unterstreichen das immense Potenzial der 3D‐ED/MicroED für die Strukturaufklärung von Komponenten mikrokristalliner Gemische, wodurch sich die Züchtung großer Einkristalle und der Einsatz ergänzender Analysetechniken erübrigt. Dies wird nicht nur dazu beitragen, dass die Methode für die Identifizierung, sondern auch für die primäre strukturelle Charakterisierung neuer Verbindungen in Zukunft an Bedeutung gewinnt.

Controlling Phase Transitions in Two-Dimensional Perovskites through Organic Cation Alloying

We demonstrate control over the phase transition temperature of Ruddlesden-Popper two-dimensional (2D) perovskites by alloying alkyl organic cations of varying lengths. By blending hexylammonium with pentylammonium or heptylammonium cations in different ratios, we continuously tune the phase transition temperature of 2D perovskites from approximately 40 to -80 °C in both crystalline powders and thin films. Correlating temperature-dependent grazing incidence wide-angle X-ray scattering and photoluminescence spectroscopy, we also demonstrate that the phase transition in the organic layer couples to the inorganic lattice, impacting PL intensity and wavelength. We take advantage of changes in PL intensity to image the dynamics of this phase transition and show asymmetric phase growth at the microscale. Our findings provide the necessary design principles to precisely control phase transitions in 2D perovskites for applications such as solid-solid phase change materials and barocaloric cooling.

Bioconversion of Sargassum wightii to ethanol via consolidated bioprocessing using Lachnoclostridium phytofermentans KSM 1203

Contemporary studies suggest that macroalgal biomass is an attractive and alternate source for ethanol production to replace fossil fuel. Sargassum wightii, a brown macroalgae, rich in cellulose is suitable for bioethanol production. This investigation focused on the pretreatment, enzyme saccharification and fermentation for bioethanol production through consolidated bioprocessing (CBP) using Lachnoclostridium phytofermentans KSM 1203 isolate. The cellulose extraction from S. wightii biomass and essential medium components for L. phytofermentans KSM 1203 were optimized using Response Surface Methodology. The alkali pretreatment on S. wightii biomass removed lignin and hemicelluloses with the cellulose recovery of 82.35%. The sodium hyphochlorite treatment removes other contaminants, results the semi crystalline to amorphous cellulose structure. The optimized medium components for L. phytofermentans KSM 1203 was found to be pre-treated biomass 3.92 g/L, peptone 2.21 g/L, dipotassium hydrogen phosphate 1.84 g/L and sodium chloride 2.03 g/L and for the growth and co-production of cellulase activity and ethanol productivity. The maximum bioethanol yield was obtained under the optimal conditions to be 13.75 ± 0.687 g/L for L. phytofermentans KSM 1203 from pre-treated S. wightii biomass. Hence, this investigation suggests that wild type L. phytofermentans KSM 1203 strain could be exploited for the utilization of cellulose for production ethanol in a single-step CBP procedure.

Pressure/Thermo-Induced Hypsochromic-Shifted and Enhanced Luminescence Based on Carbazole Emitter

Most organic mechanochromic luminogens show bathochromic-shifted and quenched emission with increasing pressure. Design of turn-on mechanochromic material with hypsochromic-shifted luminescence is still a challenge. Herein, a novel emitter (namely DCzPy) was prepared through laboratory-synthesized carbazole to study its stimuli-responsive luminescence. The crystalline powders of DCzPy emitted blue-green fluorescence at 490 nm. Upon gently grinding, the fluorescence intensity of DCzPy was dramatically enhanced with a hypsochromic shift by 33 nm. Further heavily grinding, its emission wavelength returned to 490 nm. Powder X-ray diffraction patterns indicated that such behaviors were attributed to the solid-state morphology transition from crystal to crystal. Interestingly, a large bathochromic-shifted and weakened fluorescence was achieved under isotropic compression. Moreover, thermoresponsive behavior of DCzPy was studied in the film to find that its emission turned from green to blue as the temperature increased. Given the thermo-induced fluorescence switching of DCzPy, a two-dimensional code was fabricated for information anticounterfeiting.

Agitated thin film drying of non-centrifugal sugars: Impact of processing parameters on the crystallinity and dissolution rates of NCS powder

Agitated thin film drying of non-centrifugal sugars: Impact of processing parameters on the crystallinity and dissolution rates of NCS powder

Comprehensive characterisation of the flurbiprofen/β-cyclodextrin inclusion complex using X-ray techniques and NMR spectroscopy

A new pharmaceutical form of a nonsteroidal anti-inflammatory drug complex composed of racemic flurbiprofen (FP) with a macrocyclic compound, forming a guest-host complex, was investigated. As with the other propionic acid compound, ketoprofen, three methods (co-precipitation, evaporation and heating-under-reflux) were used to prepare the β-cyclodextrin (β-CD) complex with FP. 1HNMR and X-ray powder diffraction (XRPD) in solution and solid state, respectively, were used to monitor the guest-host interactions. Only the heating-under-reflux method turned out to be suitable for host-guest complex formation. For the prospective method, a complex was prepared in the form of a crystalline powder, which was used as a starting material for the preparation of monocrystals suitable for X-ray crystallographic studies. The selected crystal was used to collect the diffraction data, which enabled the crystal and the molecular structure of the complex to be solved. This work is a connecting element in understanding the complete view of the interaction of FP with β-CD, mainly due to the results obtained with the X-ray single-crystal diffraction technique.

Bioactive hybrid membrane-based cellulose acetate/bioactive glass/hydroxyapatite/carbon nanotubes nanocomposite for dental applications

The present work aimed to fabricate a set of hybrid bioactive membrane in the form of bio-nanocomposite films for dental applications using the casting dissolution procedures. The formulation of the targeted materials was consisting of cellulose acetate/bioactive glass/hydroxyapatite/carbon nanotubes with a general abbreviation CA-HAP-BG-SWCNTs. The nanocomposites were characterized using XRD, FTIR, SEM-EDX and Raman spectroscopy. XRD, FTIR and SEM characters confirm the nanocomposites formation with good compatibility. The fabricated materials had a semi crystalline structure. The mechanical and thermal properties, as well as contact angle and bioactivity of the fabricated nanocomposites were investigated. The SEM images for showed beehive-like architectures with a thicker frame for the second material. All fabricated materials showed good thermal behaviors. Furthermore, the agar diffusion antimicrobial study showed that the prepared nanocomposites do not exhibit an antibacterial activity against five pathogenic bacterial strains. Additionally, cytotoxicity of a dental nanocomposite filling agent was evaluated. Vero normal cells were incubated with test materials for 72h at 37 °C and 5% CO2. Cell viability was detected using a SRB assay. All nanocomposites were mildly to non-cytotoxic to Vero cells at high concentration in contrast to the inhibitory effect of doxorubicin which was added at 10-fold lower concertation than the nanocomposites. Hence, the proposed nanocomposite is promising candidates for dental applications.

Finite-Temperature Mechanical Properties of Organic Molecular Crystals from Classical Molecular Simulation

The mechanical properties of crystalline materials can have an impact on different aspects of solid dosage form design and manufacturing. Experimental determination of these quantities is known to pose difficulties and can be time-consuming. Instead, first-principles predictions of such materials have the potential for accelerating drug formulation development. We calculated elastic constants and several derived mechanical properties for the crystalline phase of a set of 18 small organic molecules with available experimental data, using molecular dynamics simulations based on the widely used GAFF2 force field. Attempts to further improve the accuracy of the predicted mechanical properties were made by fitting the force field parameters to the energies and forces determined by DFT calculations. We determine that DFT-based optimization of the force field parameters were unable to improve the accuracy of the mechanical property predictions over the currently established GAFF2 force field, which already provides reasonably accurate results with mean unsigned errors of individual elastic constants of around 2–3 GPa, or lower, in the majority of cases. Also, the elastic anisotropy is correctly predicted, at least qualitatively. The method used here can be a simple and fast means for the approximate determination of mechanical properties of a crystalline drug powder─material properties that can be used to guide decisions during formulation development.

Impact of Solid-State Properties on the Aerosolization Performance of Spray-Dried Curcumin Powders

Amorphous and crystalline active pharmaceutical ingredients (APIs) are both widely studied for pulmonary delivery. The past research mainly studied the impact of solid-state properties on pharmacokinetic attributes; however, the influence of solid-state properties on aerosolization performance was much less studied. This study aimed to investigate the different aerosolization performances of amorphous and crystalline curcumin (Cur) stabilized with L-leucine. Cur was spray-dried with different concentrations of L-leucine (0, 5, 20, 35, and 50%, w/w) as both solution-based and suspension-based formulations to acquire amorphous and crystalline Cur powders. The physicochemical properties of the spray-dried powders, including particle size, morphology, and solid-state characteristics, were studied. The aerosolization performance as well as dissolution properties were evaluated. It was found that 35% (w/w) L-leucine or above led to the formation of amorphous Cur in the spray-dried powders, and the amorphous Cur powders exhibited higher FPF (70.8%, with 50% L-leucine, w/w) than the crystalline Cur formulations with an FPF at 56.3% (with 50% L-leucine, w/w). In conclusion, with a high concentration of L-leucine (35% or above) in the formulations, amorphous Cur would exhibit higher aerosolization efficiency than crystalline Cur. However, with a low concentration of L-leucine (20% or less) in the formulations, crystalline Cur would be preferred for more enhanced consideration.

Tunable Synthesis of Metal-Rich and Phosphorus-Rich Nickel Phosphides and Their Comparative Evaluation as Hydrogen Evolution Electrocatalysts.

Flexible synthetic routes to crystalline metal-rich to phosphorus-rich nickel phosphides are highly desired for comparable electrocatalytic HER studies. This report details solvent-free, direct, and tin-flux-assisted synthesis of five different nickel phosphides from NiCl2 and phosphorus at moderate temperatures (500 °C). Direct reactions are thermodynamically driven via PCl3 formation and tuned through reaction stoichiometry to produce crystalline Ni-P materials from metal-rich (Ni2P, Ni5P4) to phosphorus-rich (cubic NiP2) compositions. A tin flux in NiCl2/P reactions allows access to monoclinic NiP2 and NiP3. Intermediates in tin flux reactions were isolated to help identify phosphorus-rich Ni-P formation mechanisms. These crystalline micrometer-sized nickel phosphide powders were affixed to carbon-wax electrodes and investigated as HER electrocatalysts in acidic electrolyte. All nickel phosphides show moderate HER activity in a potential range of -160 to -260 mV to achieve current densities of 10 mA/cm2 ordered as c-NiP2 ≥ Ni5P4 > NiP3 > m-NiP2 > Ni2P, with NiP3 activity showing some particle size influence. Phosphorus-rich c/m-NiP2 appears most stable under acidic conditions during extended reactions. The HER activity of these different nickel phosphides appears influenced by a combination of factors such as particle size, phosphorus content, polyphosphide anions, and surface charge.