Microcrystalline Particles Research Articles

NiFe2O4 magnetic nanoparticles supported on MIL-101(Fe) as bimetallic adsorbent for boosted capture ability toward levofloxacin

Levofloxacin (LVX) capture with microcrystalline particles of monometallic metal-organic frameworks (MOFs) is definitely restricted and challenged by its difficulties in solid-liquid separation and enhanced of adsorption capacity issues. Meanwhile, the development of magnetic MOFs with excellent adsorption capabilities and outstanding recyclability is crucial. Herein, a novel magnetic Fe/Ni bimetal MOFs composite (MIL-101(Fe)@NiFe2O4, MNFO) for LVX capture has been effectively fabricated for LVX capture, utilizing MIL-101(Fe) as the primary adsorbent and NiFe2O4 nanoparticles as the magnetic element. Attributed to the synergistic ability of bimetal ions (Fe2+ and Ni2+), MNFO exhibits a significant adsorption capacity (335 mg/g) and rapid adsorption rate (10 min) towards LVX. The adsorption capacity indicates an increasing-then-decreasing trend with an increase of the pH values. Additionally, the adsorption data are well fitted by the Freundlich and pseudo-second-order kinetic models. Thermodynamic studies indicated that the adsorption process was spontaneous and endothermic. In addition, the adsorbent demonstrated excellent reusability, as it could be readily recovered from the liquid phase through the magnetic properties of NiFe2O4. Remarkably, it retained approximately 90 % of its adsorption capacity of the uptakes after 5 cycles. This study offers a innovative approach to the development of highly efficient adsorbents for capturing LVX from water.

Highly enhanced cationic dye adsorption from water by nitro-functionalized Zn-MOF nano/microparticles and biomolecular binder for improving the reusability

Zinc-metal organic frameworks (Zn-MOFs) of phthalic acid (ZnPA) and nitro-phthalic acid (ZnNPA) microcrystalline particles were fabricated and utilized for the removal of organic cationic dyes (crystal violet (CV), methylene blue...

Fusion Extraction of Base Metals (Al, Cr, Fe, Ti and V) Using Ammonium Phosphate Salt as Flux

The fusion method of using ammonium phosphate salt as flux was assessed for its ability to precipitate metaphosphate compounds containing trivalent ions M3+ = Al, Cr, Fe, Ti, and V as M(PO3)3 in inorganic salts and a certified reference material (CRM) mineral ore sample. Fusion analysis using mixtures of inorganic salts containing AlCl3, CrCl3, FeCl3, and VCl3 showed variable amounts of precipitates isolated as metaphosphate compounds in the order of iron (12%) < vanadium (13%) < chromium (30%) < (44%) aluminum. However, an analysis of the CRM (AMIS 0368) where magnetite (Fe3+/Fe2+) and ilmenite (Ti4+) are the dominant phases, showed that the obtained precipitates were in the order of chromium (less than 0.1%) < vanadium (1%) < aluminum (2%) < titanium (9%) < iron (68%). The metaphosphate compounds isolated via the use of this method were identified using XRD analysis. SEM–EDX analysis showed micro-crystalline particles from the inorganic salts that were irregular and clustered, contrary to the amorphous micro particles which were produced from the CRM. The degree of specificity improved considerably using CRM ore (AMIS 0368) with high iron content (~76%, Fe3+/Fe2+). This method was shown to be highly selective towards metals with a stable trivalent oxidation state. No other elements of a different oxidation state were precipitated.

Isolation of Cellulase from Selected Fungal Strains and Its Use for Manufacture Microcrystal Cellulose from Kapuk Cortex (Ceiba Pentandra (L.) Gaertn)

This study aims to obtain cellulase enzymes from selected molds for microcrystalline cellulose preparation from ????-cellulose of kapok cortex. Alpha-cellulose was obtained by biodelignification, and the purified cellulase was obtained from the selected mold. The Microcrystalline cellulose obtained from enzymatic hydrolysis was then identified FTIR and DSC, followed by characterization of microcrystalline cellulose, Particle Size and Distribution Analysis (PSA), and Scanning Electron Microscope-Energy Dispersive X-ray (SEM-EDX), Loss on drying, pH, bulk density, tapped density, and flow rate. Biodelignification produced 14.88% ????-cellulose, Penicillium sp. the selected mold had the highest cellulase activity, with a cellulolytic index of 4.83. FTIR identification was similar to Avicel PH 101 with a melting point of 244.580°C. Loss on drying was 3.74%, pH was 7.0, particle size ranged from 13.06 to 196.79 ????m, bulk density and tapped density were 0.11 g/cm3 and 0.23 g/cm3, respectively flow rate character is quite good. SEM-EDX was showed that the morphological shape of the microcrystalline cellulose of the kapok cortex is elongated. Microcrystalline cellulose has shown a quite similar in character and can be furthered.

Front Cover: Synthesis and Characterization of a Calcium‐Pyrazolonato Complex. Observation of In‐Situ Desolvation During Micro‐Electron Diffraction (Z. Anorg. Allg. Chem. 5/2023)

The cover picture shows the microcrystalline particle size of the Ca-pyrazolonato complex with its diffraction pattern under micro-ED conditions. The pattern could be identified to show a Ca-pyrazolonato complex with an axial water ligand. The indicated shift along the b-axis of the diffraction pattern which was attributed to the loss of a water ligand from the Ca-pyrazolonato complex under the applied conditions of the microED measurement resulted in a second structure solution. This underlines that these conditions can result in the desolvation of highly electrophilic and oxophilic metal complexes (Ca) (DOI: 10.1002/zaac.202200294).

Sonication‐Responsive Organic Afterglow Emulsions

AbstractIn contrast to their fluorescence counterparts, stimuli‐responsive organic afterglow materials display distinct advantages to function normally in the presence of strong fluorescence background. However, most of the stimuli‐responsive afterglow materials can only work in their solid states with those in aqueous medium being rarely reported. In addition, the types of these materials are limited to mechanical force‐, pH‐, ion‐, and temperature‐responsive ones. Here, a serendipitous finding of sonication‐responsive organic afterglow emulsions in aqueous medium is reported. The afterglow emulsions are produced by dopant‐matrix strategy and emulsion technique. In‐depth studies reveal that the key to achieve the sonication responsiveness is the selection of a specialized organic matrix that can form microcrystalline particles in aqueous medium with the aid of surfactants. In matrix's microcrystalline state, the triplet excited states of luminescent dopant within the matrix can be protected to exhibit room‐temperature afterglow. Under sonication, matrix's microcrystalline structure can be disrupted and consequently the triplet excited states of luminescent dopants lose protection to show afterglow quenching. To the best of the authors’ knowledge, this study represents the first report of sonication‐responsive afterglow materials in aqueous medium, which show promising biomedical applications.

Cobalt metal–organic framework microcrystalline particles with strong electrocatalytic activity: amine controlled morphology and OER activity

Cobalt MOF microcrystalline particles showed an unusual amine-dependent morphology and an enhanced OER activity.

Surface Quantum-Dimensional Photocarrier Recombination in <i>CdTe</i> Microcrystals

The scope of the study is the spectra of low-temperature (T = 2K) photoluminescence of a p-CdTe/n-CdS film heterostructure comprising a monolayer of CdTe microcrystals, where a single microcrystalline particle is typically one micron in size. Focus is made on the dominant band of “super-hot” emission appearing in the spectral region located in energy above the fundamental absorption edge of a CdTe bulk crystal. A theoretical model has been developed that assumes the existence of a space-charge layer inside a microcrystal, which leads to the formation of a triangular potential well for an electron near the surface. The anomalous emission band arises as a result of the optical transitions of electrons from near-surface levels of spatial quantization to valence band states.

Correction: Cobalt metal–organic framework microcrystalline particles with strong electrocatalytic activity: amine controlled morphology and OER activity

Correction for ‘Cobalt metal–organic framework microcrystalline particles with strong electrocatalytic activity: amine controlled morphology and OER activity’ by Gunasekaran Arunkumar et al., New J. Chem., 2023, https://doi.org/10.1039/d3nj01457f.

Superfine HMX Prepared by a Gas‐Solid Method with Reduced Sensitivity and Enhanced Mechanical Performance

AbstractMany superfine processing techniques have been applied on desensitization of HMX. However, large‐scale production of superfine HMX is still a big challenge due to the overloaded parameters, poor stability and capacity issue. Here, we developed a novel and facile gas‐solid method to prepare superfine HMX, based on a process of solvent vapor permeation and removal. Superfine HMX with structure of stacking microcrystalline particles was achieved conveniently. Compared to pristine HMX, the characteristic height for impact initiation of the resultant superfine HMX increased from 23.30 cm to 112.20 cm. Moreover, the largely increased surface area of superfine HMX enhanced the interfacial interaction between HMX and binder, which remarkably enhanced the comprehensive mechanical performance of HMX‐based polymer bonded explosives (PBXs). The compressive and tensile strength of the superfine HMX based PBXs were improved by 57.14 % and 120.27 %, respectively. This simple and reliable method can shed light on the design and preparation of energetic materials with better safety performance and optimized mechanical performance.

Innovative Microstructural Transformation upon CO2 Supercritical Conditions on Metal-Nucleobase Aerogel and Its Use as Effective Filler for HPLC Biomolecules Separation.

This work contributes to enlightening the opportunities of the anisotropic scheme of non-covalent interactions present in supramolecular materials. It provides a top-down approach based on their selective disruption that herein has been employed to process a conventional microcrystalline material to a nanofibrillar porous material. The developed bulk microcrystalline material contains uracil-1-propionic acid (UPrOH) nucleobase as a molecular recognition capable building block. Its crystal structure consists of discrete [Cu(UPrO)2 (4,4′-bipy)2 (H2 O)] (4,4′-bipy=4,4′-bipyridine) entities held together through a highly anisotropic scheme of non-covalent interactions in which strong hydrogen bonds involving coordinated water molecules provide 1D supramolecular chains interacting between them by weaker interactions. The sonication of this microcrystalline material and heating at 45 °C in acetic acid–methanol allows partial reversible solubilization/recrystallization processes that promote the cross-linking of particles into an interlocked platelet-like micro-particles metal–organic gel, but during CO2 supercritical drying, the microcrystalline particles undergo a complete morphological change towards highly anisotropic nanofibers. This unprecedented top-down microstructural conversion provides a nanofibrillar material bearing the same crystal structure but with a highly increased surface area. Its usefulness has been tested for HPLC separation purposes observing the expected nucleobase complementarity-based separation.

The Crystal Structure of 5‐Aminouracil and the Ambiguity of Alternative Polymorphs

AbstractThe nucleobase derivative 5‐aminouracil (AUr, C4H5N3O2) is of interest for its biological activity, yet the solid state structure of this compound has remained elusive owing to its propensity to crystallize as aggregates of microcrystalline particles. Here we report the first single‐crystal structure of AUr determined from synchrotron x‐ray diffraction data. An early crystal structure prediction effort, which assumed that AUr was rigid in the isolated molecule optimized conformation, provided several poor matches to the simulated PXRD pattern. Revisiting these crystal structures, by periodic electronic level modelling (PBE‐TS optimization) gave more realistic relative lattice energies, but a good match to the experimental powder pattern required using the experimental cell parameters. PXRD and Raman spectroscopy suggest that phase impurities may be present in the bulk crystallization product, though the identity of alternative polymorphs could not be confirmed on the basis of the data available.

Filler Content Effect on Water Uptake and Thermal Stability of Poly(3‐Hydroxybutyrate‐Co‐3‐Hydroxyhexanoate)/Microcrystalline Cellulose Biocomposites

AbstractIn this study, biocomposites of poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate) (PHBHHx)/cellulose microcrystalline (MCC) extracted from olive husk flour are prepared by melt compounding at various filler content ratios, i.e., 10, 20, and 30 wt%. The effect of the MCC content on the morphology, thermal stability, crystallinity, and water uptake of the PHBHHx biocomposites is investigated. The results showed that the addition of MCC to PHBHHx decreased the thermal stability of the biocomposites compared to that of neat polymer, however more pronounced at a higher filler content. This is due probably to the tendency of MCC particles to agglomerate, inducing heterogeneities and defects within the polymer matrix observed by scanning electron microscopy. Furthermore, both crystallinity and water uptake after 24 h of immersion increased with the filler content.

Breakdown Voltage of Transformer Oil Containing Cellulose Particle Contamination With and Without Bridge Formation Under Lightning Impulse Stress

This study investigates the effect of cellulose bridge formation on insulating oil. Such effect influences the breakdown voltage and strength of mineral oil (MO) under standard lightning impulse (LI) voltage. A cylindrical test vessel fitted with spherical–spherical electrodes with a 2 mm gap distance between them was used to generate a quasi-uniform field and observe bridge formation between the gaps. A positive LI waveform (1.2/ $50~\mu \text{s}$ ) generated by an impulse generator was applied during the breakdown tests. The rising-voltage method was used to measure the breakdown voltage in accordance with the IEC 60897 standard test method. Weibull cumulative breakdown probability was applied to present the breakdown results statistically, and the outcome was compared with clean oil (CO). Commercial cellulose microcrystalline particles were dispersed into the transformer oil to act as bridge. The concentrations of the samples were 0.004%, 0.008% and 0.012% by weight. The breakdown test results showed that the cellulosic particles reduced the LI breakdown voltage (LIBV) of MO by up to 10%. The influence of cellulose particles on LIBV was also more prominent during bridge formation, with a further reduction of 14%. Evidently, the presence of the cellulose bridge exerted a detrimental effect on the breakdown voltage of MO under LI stress, yielding a reduction of 24% and 27% at 0.004 wt% and 0.012 wt%, respectively. Finite element analysis also indicated that the electrical field strength of cellulosic particle contamination of 0.004 wt% and 0.012 wt% without a bridge skeleton exceeded the critical electric field strength of CO by 20% and 61%, respectively. The presence of cellulosic contamination at any concentration, i.e. either with or without a bridge structure, clearly decreased the breakdown strength of transformer oil. However, the breakdown is not occurred instantaneously. The LI breakdown was initiated and established only at a certain impulse stress level, when the electric field strength along the bridge lines exceeded the critical electric field strength of the oil. Thus, this finding potentially contributes to the formulation of guidelines for condition assessment and contamination monitoring to minimise common issues in power transformer failures that are attributable to the insulation system, and consequently, achieve optimum transformer insulation integrity.

Synthesis of orange emitting Sm3+ doped sodium calcium silicate phosphor by sol-gel method for photonic device applications

Samarium (Sm3+) doped sodium calcium silicate (Na2CaSiO4: NCS) phosphors have been synthesized by employing a sol-gel technique. The structural, morphological, excitation and emission spectral studies have been carried out for the as-prepared phosphors. The phase purity in synthesized NCS phosphor with cubic structure has been confirmed by X-ray diffraction (XRD) pattern. The scanning electron microscopic images depict the irregular morphology and non-uniform microcrystalline particles in synthesized phosphor. The excitation spectra of NCS: Sm3+ phosphors disclose strong absorption in UV (ultraviolet), n-UV (near UV) and blue spectral regions. The emission spectra recorded under 402 nm excitation exhibit peaks at 565, 602 and 649 nm attributed to characteristic 4f-4f transitions of Sm3+ ions. The Sm3+ concentration optimized for NCS host as 1.0 mol%, and concentration quenching phenomenon has been discussed in detail. The chromaticity coordinates (0.579, 0.419) for optimized NCS: Sm3+ phosphor lie in the pure orange region. The temperature-dependent photoluminescence studies demonstrate that luminescence intensity even at 423 and 463 K persists up to 85.4 and 79.6% of the intensity at room temperature, respectively. Above mentioned results substantiate the potentiality of NCS: Sm3+ phosphor to use as a thermally stable orange emitting component in photonic devices.

Luminescence characteristics of O6+ ion beam and γ-ray irradiated Ca9La(PO4)5(SiO4)F2:Eu phosphor

ABSTRACTFluorapatite Ca9La(PO4)5(SiO4)F2: Eu with variable molar concentrations of Eu3+ (0.05–1.0 mol%) were synthesised by the solid-state reaction method and their photoluminescence (PL), thermoluminescence (TL) characteristics were studied after irradiating the samples with γ-rays and 75 MeV O6+ ion beam. The formation of the material was confirmed using X-ray diffraction pattern followed by Scanning electron microscopy and Fourier transform infra-red (FTIR) spectrum. The morphology of the synthesised powder was observed to be polycrystalline constituted by microcrystalline particles. FTIR spectrum shows characteristic bands, 563 cm−1 for bending vibration υ4 and 1035 cm−1 for stretching vibration υ3. PL spectra show absorption bands at 395 and 466 nm corresponding to 7F0→5L6 and 7F0→5D2 transitions and the emission band was seen at around 595 and 616 nm describing 5D0→7Fj transitions (j = 1,2). Furthermore, TL glow curves of both γ-rays and 75 MeV O6+ ion beam irradiated samples show a prominent peak at around 145°C with a small hump at around 245°C. The concentration 0.2 and 1 mol% was found to be the best concentration for studying TL properties of Ca9La(PO4)5(SiO4)F2: Eu irradiated with γ-rays and 75 MeV O6+ ion-beam respectively.

Characterization of micro-crystalline structure and particle size distribution of soot generated from MILD-OCC flame

Two types of coals and CH4 were burned with O2 in MILD-OCC mode while taking CO2 as diluted gas. By setting the sampling point in the flame, the flame temperature distribution was obtained by thermocouple. The TSPD-TEM system was used to sample at different points and obtain the TEM images, Digital Micrograph, ImageJ and MATLAB software were resorted to analyze the micro-crystalline structure and PSD of soot generated from MILD-OCC. The results showed that the radial flame temperature was a nearly constant value in center area and a decreased trend in outer edge area, while the temperature presented decreasing trend along the height above burner (HAB) at axial direction. When HAB = 10 mm, the soot particles were all exist in single state and there were oil drop-like substances attached to the surface of the particles. When HAB = 20 mm, soot grew bigger and were obviously spherical, and the edges of the particles were relatively clear. Starting from HAB = 30 mm, the soot particles aggregated to chain-like clusters. Both of PSD for the soot generated from two types of coal were between 0.02 and 0.04 μm, and all had the tendency of increasing at first and then decreasing, the micro-crystalline curvature (C) occurred at 1.0–1.5, layer spacing (d) was mainly distributed between 0.32 and 0.45 nm, and the micro-crystalline length (La) peak was between 0.4 and 2.2 nm. C and d were all deceasing tendency while La was roughly increasing trend with the increase of HAB.

Effects of micrite microtextures on the elastic and petrophysical properties of carbonate reservoirs

Apparent differences in sedimentation and diagenesis exist between carbonate reservoirs in different areas and affect their petrophysical and elastic properties. To elucidate the relevant mechanism, we study and analyze the characteristics of rock microstructure and elastic properties of carbonates and their variation regularity using 89 carbonate samples from the different areas The results show that the overall variation regularities of the physical and elastic properties of the carbonate rocks are controlled by the microtextures of the microcrystalline calcite, whereas the traditional classification of rock- and pore- structures is no longer applicable. The micrite microtextures can be divided, with respect to their morphological features, into porous micrite, compact micrite, and tight micrite. As the micrites evolves from the first to the last type, crystal boundaries are observed with increasingly close coalescence, the micritic intercrystalline porosity and pore-throat radius gradually decrease; meanwhile, the rigidity of the calcite microcrystalline particle boundary and elastic homogeneity are enhanced. As a result, the seismic elastic characteristics, such as permeability and velocity of samples, show a general trend of decreasing with the increase of porosity. For low-porosity rock samples (φ 5%) dominated by tight micrite, the micritic pores have limited contributions to porosity and permeability and the micrite elastic properties are similar to those of the rock matrix. In such cases, the macroscopic physical and elastic properties are more susceptible to the formation of cracks and dissolution pores, but these features are controlled by the pore structure. The pore aspect ratio can be used as a good indication of pore types. The bulk modulus aspect ratio for dissolution pores is greater than 0.2, whereas that of the intergranular pores ranges from 0.1 to 0.2. The porous and compact micrites are observed to have a bulk modulus aspect ratio less than 0.1, whereas the ratio of the tight micrite approaches 0.2.

Photochemical synthesis of nano- and micro-crystalline particles in aqueous solutions

UV irradiation of aqueous solutions containing various metal ions (Ag, Rh, Cu, Pb, Ba, …) and sensitizers was performed in order to synthesize a large variety of solid nano- or microcrystalline materials in the irradiated solutions and illustrate the chemical and photochemical reactions leading to their formation. Acetone was shown to be a very effective sensitizer and photoreducing agent when coupled with propan-2-ol, whereas formate HCOO– was introduced either mainly as a reducing agent in deaerated solution or as a source of nascent CO2 in the presence of air. It was shown that UV irradiation allows for the preparation of a wide variety of inorganic materials. Moreover, reactions mechanisms discussed may occur during Laser Ablation in Liquid processes.

Effect of dipping time on the properties of Sb2S3/Si heterojunction prepared by chemical bath deposition

The effect of dipping time on the structural, optical and electrical properties of Sb2S3 film deposited on the glass and silicon substrates by chemical bath deposition technique was studied. The values of the optical energy gap determined from optical absorption were in the range 2–2.5 eV indicating good tunability of the film energy gap in the visible region. X-ray diffraction XRD result confirms that the all deposited films are crystalline in nature with orthorhombic phase and the reflection peak intensity was found to be decreased as dipping time increase. Scanning electron microscope SEM investigation reveals that the film morphology and grain size are depending on the dipping time. The film deposited at 3 min reveals a porous structure and spherical microcrystalline particles distributed over plate-like crystallites structure was observed for a film deposited at a longer time. The elemental analysis of the film as a function of dipping time was investigated using energy dispersive x-ray EDX. The Hall mobility of the film has increased from 2 to 4.75 cm2V−1 s−1 as dipping time increased from 3 to 9 min. It was found that the dipping time playing a vital role in controlling the figures of merit of n-Sb2S3/p-Si heterojunction photodetectors namely dark and illuminated current-voltage, responsivity and specific detectivity. Spectral responsivity findings show that the photodetectors have two peaks of response located at 500 and 700 nm. Energy band diagram of the Sb2S3/Si heterojunction was constructed.