Crystalline Structure Research Articles

Wave-Assisted Techniques, a Greener and Quicker Alternative to Synthesis of Cyclodextrin-Based Nanosponges: A Review.

The ever-increasing applications of cyclodextrin and cyclodextrin-based nanosponges in formulation development has gained much attention from researchers towards needed research in this arena. Nanosponges are three-dimensional nanoporous versatile carriers in the pharmaceutical research field because of their capability to encapsulate lipophilic and hydrophilic drugs both in their crystalline structure by inclusion and non-inclusion phenomenon. This review sheds light on the advancements made in this field and the associated patents with regard to their synthesis while zooming in on the utilization of two novel energies (Microwave and ultrasonic) in accomplishing this goal and its future thereof. Microwave and ultrasound-assisted manufacturing of cyclodextrin-based nanosponges (CDNS) has been found superior to conventional heat-dependent methods due to rapid/homogenous heating and fast kinetics, which ultimately provide the final product with high yield and crystallinity relatively rapidly. The review article also defines several facets of microwave and ultrasound-assisted nanosponge synthesis including the synergism of microwave and ultrasonic energy and the theories behind them. This hitherto unexplored microwave-ultrasonic coupling technology could be a future technology to synthesize CD-NS with a better outcome. In the recent past, these novel energy processes have been used successfully in material synthesis at an industrial scale due to their swift and streamlined synthesis attributes. Likewise, these wave-assisted methods have the full potential to materialize the concept of CD-NS from lab scale to industrial scale as a competent and versatile drug carrier, having all the prerequisite characteristics, for commercialization.

Silk nanoribbon films with enriched silk II structure and enhanced piezoelectricity for self-powered implantable and wearable devices

Piezoelectric biomaterials are intrinsically suitable to convert mechanical energy to electrical output and achieve electricity generation, in vivo/in vitro real-time monitoring, and sensing in biological systems. However, the inability to fabricate piezoelectric bio-materials with excellent piezoelectricity, full biodegradability, and good biocompatibility remains a challenge toward practical applications. As a solution, we present a bio-piezoelectric thin film with macroscopic piezoelectric output, high stability, fast response ability, flexibility, biocompatibility, and biodegradability based on nascent silk nanoribbons (SNRs) with high silk II-type structure. The solvent systems influence the meso/nanostructure and the piezoelectric performance of silk materials. Compared with other silk materials, the SNR fabricated by 2,2,6,6-tetramethylpiperidine-1-oxyl oxidation system (T-SNR) maintains higher silk II-type structure and more stable crystalline structure. The T-SNR film possesses electrostriction effect without electrical poling treatment. It presents an apparent piezoelectric constant (d33) of 7.7 pm/V and a piezoelectric voltage coefficient (g33) of 0.58 Vm/N, such values are superior to most reported bio-films. The piezoelectric T-SNR film can realize in vivo/in vitro real-time monitoring, sensing, and self-power ability. With its natural compatibility and degradability, the T-SNR film exhibits the potential for various implantable and wearable applications and may enable the development of fully biodegradable transient electromechanical devices.

Development of Multifunctional Sustainable Packaging from Acetylated Cellulose Micro-Nanofibrils (CMNF)

Cellulose micro-nanofibrils (CMNF) with different fibrillation levels were partially acetylated while preserving their morphological and native crystalline structure. The morphological changes due to fibrillation and chemical modification were observed using Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) and optical profilometry. The change in tensile and burst strength, barrier, and biodegradability profile were investigated which revealed that the mechanical properties of the unmodified CMNF films increased with increase in extent of fibrillation. However, the mechanical strength of the acetylated film decreased with the increase in degree of acetylation. The stretching or folding property of the film increased with the increase in both the fibrillation and acetylation. The contact angle value increased due to a higher degree of fibrillation and acetylation because they increased the hydrophobicity and consequently enhanced the air and water vapor resistance of the unmodified and modified CNF films. Furthermore, all films exhibited the highest resistance against oil and grease, and the biodegradability test substantiated that CNF films were compostable in soil. In total, this work expresses new pathways to enhance the barrier properties of biodegradable CNF films by regulating the degree of fibrillation and acetylation, thus can emerge as sustainable alternatives to for packaging and agriculture applications.

Fluidized bed reactor for 4-chlorophenol photodegradation via solar and visible radiation using ZnO/g-C3N4/carbon xerogel as a photocatalyst

This study investigates the feasibility of employing a fluidized bed reactor for the degradation of 4-chlorophenol (4CP), considering multiple operational parameters (type of radiation, fresh inlet flow rate and recycle flow rate). The selection of the ZnO/g-C3N4/carbon xerogel as photocatalyst, a choice motivated by the improved charge transfer and increased catalyst activity under visible radiation provided by the presence of carbon xerogel and g-C3N4, was previously determined through tests conducted in a jacketed batch reactor under visible radiation, in which the ternary material efficiency was compared to their constituting counterpart materials. The semiconductors constituting the unary, binary, and ternary materials were chosen based on considerations of availability, sustainability, and abundance in nature. The use of the proposed fluidized bed reactor brings advantages in scalability, distribution of irradiated light and overall costs when compared to commonly used batch reactors, whereas the investigation of the flow parameters involved in such process is of great importance to understand and optimize the efficiency of the pollutant degradation process. Regarding the ternary photocatalyst, X-ray diffractometry (XRD) revealed the presence of zinc oxide's hexagonal crystalline structure. Moreover, additional characterization using Raman spectroscopy, Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive spectroscopy (EDS) confirmed the presence not only of ZnO but also of carbon xerogel and g-C3N4 in the composite. From the photodegradation experiments, it was determined that the optimal fresh inlet flow rate to achieve the best degradation, as well as the recycle flow rate for this purpose, were 0.07 and 25 L h−1, respectively. Mathematical simulations described that the model that best fits the system's behavior considers the specific reaction rate as dependent on the concentration of the catalyst in the medium.

Sputter Deposited Crystalline MoO2 Films as a High-Capacity and Stable Electrode Material for Supercapacitors: Mechanistic/Electrochemical Insights

In this work, we have optimized and fabricated pristine molybdenum dioxide (MoO2) electrodes over the Silicon (Si) substrate and examined the impact of various ion-loaded aqueous electrolytes on their electrochemical behavior. The sputtered electrodes exhibited a high crystalline structure and a very low resistivity. These highly conductive electrodes were tested in three different aqueous electrolytes (acidic, neutral, and alkaline) to establish a relation between the electrode and the nature of the electrolyte to achieve optimal electrochemical performance and cyclability. The electrochemical kinetics showed that the charge storage mechanism was unique for all the electrolytes. The capacitive current was dominant in the neutral electrolyte, whereas it was diffusive dominant in alkaline and 70% capacitive in the acidic electrolyte. Our findings indicated that the MoO2@Si electrode exhibited superior electrochemical activity in an acidic electrolyte. The electrode showed a voltage window of 0.6 V with an areal capacity of 24 mF/cm2 at 0.1 V/s scan rate. Moreover, the electrode also demonstrated excellent cyclability and capacitance retention (∼145%) till 5000 cycles. These results highlighted that the binder-free MoO2@Si electrode showed outstanding electrochemical activity and stability, which makes it suitable for sulfuric acid electrolyte-based energy storage systems.

Improving Adsorption Efficiency of Recycled Activated Carbon from Household Water Purifiers through Sonication

Objectives:This study evaluated the potential of recycled activated carbon from household water purifiers as an adsorbent for removing methylene blue. It aimed to achieve resource recycling and dyeing wastewater treatment through the sonication modification of recycled activated carbon.Methods:After sieving recycled activated carbon from water purifiers to a particle size of 75-150μm, the material, in this paper referred to as PCB-S, was processed using sonication to enhance its adsorption capacity. The characteristics of PCB-S were analyzed using SEM, XRD and BET analysis. To evaluate its efficacy, adsorption experiments were carried out varying the following parameters: PCB-S dosage (0.05-0.6gL-1), pH (2.0-10.0), initial concentration of methylene blue (100mgL-1), reaction time (1440 min), and temperature (298 K). The data from these experiments were analyzed using first and second-order kinetic models to understand the reaction kinetics, and the adsorption efficiency was further compared using Langmuir and Freundlich isotherm models. Finally, the thermodynamic properties of the adsorption process between PCB-S and methylene blue were studied to determine its endothermic nature and spontaneity.Results and Discussion:The analysis of the surface characteristics of PCB and PCB-S revealed that sonication significantly altered the pore structure of the activated carbon, leading to increases in both the specific surface area and pore volume. XRD analysis, indicated that sonication had no impact on the crystalline or amorphous structure of the activated carbon. PCB-S demonstrated superior porosity and adsorption capabilities compared to PCB. With a dosage of 0.6gL-1, PCB-S was able to remove 65% of methylene blue from the solution. The adsorption kinetics were best described by a pseudo-second-order kinetic model, with the Langmuir adsorption isotherm fitting the data most accurately. The Gibbs free energy (-1.90~-1.32kJ mol-1) and enthalpy change (7.44 kJ mol-1) confirmed that the adsorption reaction was endothermic.Conclusion:This study confirmed that recycled activated carbon from water purifiers exhibits excellent effectiveness as a dye removal adsorbent when subjected to sonication treatment. Therefore, the possibility of utilizing recycled household water purifier filters as adsorbents is expected to contribute to reducing waste disposal costs by promoting resource recycling.

Increased Fluorohydroxyapatite across Dentin after Fluoride Iontophoresis.

Due to the multiple factors contributing to dentin demineralization and hypersensitivity among individuals, the effectiveness of the available treatments in the long term remains unclear. A recent study reported a simple strategy to potentially mimic natural remineralization with increased crystallization on the enamel caries using fluoride iontophoresis. Such an effect is also ideal for accomplishing dentin biomineralization and structural strength. This study aimed to investigate structural and compositional characteristics and permeability changes after fluoride iontophoresis with different polarities, cathodal iontophoresis (CIP), anodal iontophoresis (AIP), and the control without iontophoresis for the treatment of etched dentin under simulated pulpal pressure. The 24 premolars were divided into 3 groups: CIP, AIP, and topical application of 5% sodium fluoride (NaF) for 40 s. Relative to before treatment, iontophoresis with both polarities significantly decreased the permeability with a visible increase in occluding tubules containing crystal formation and growth throughout the dentin structure and depth. The CIP not only restored the etched dentin surface into a sound condition but also reinforced the dentin across the structure and depth by the synergistic effects of remineralization, increasing crystal formation and transformation toward the more crystalline structure of fluorohydroxyapatite. Following topical treatment, X-ray diffraction analysis and Raman spectra revealed a significant reduction in the crystal size and crystallinity associated with the raised B-type carbonate substitution into the hydroxyapatite compared with that in the sound dentin. The result was the first to reveal the ideal strategy to rapidly restore the etched dentin surface into a sound condition, including reinforcing the dentin across the structure and depth by the synergistic effects of decreasing permeability, increasing crystal formation, and transformation toward the more crystalline structure of fluorohydroxyapatite using the 5% NaF applied with the DC cathode iontophoresis. The technique is noninvasive and simple and deserves further development for clinical application.

Copper oxide nanoparticles modified electrodes for high-sensitivity detection of uric acid in athletes

This study introduces an innovative electrochemical sensor leveraging copper oxide nanoparticles for detecting uric acid levels in athletes with enhanced sensitivity and selectivity. Employing a novel synthesis protocol, uniform copper oxide nanoparticles were integrated into a chitosan-glutathione biogel matrix, creating a high-performance sensing electrode. The nanoparticles were extensively characterized using XRD, SEM, FTIR, and XPS techniques, confirming their crystalline structure, morphology, and purity. The average crystallite size was determined to be 18 nm. Electrochemical evaluation of the sensor using cyclic voltammetry and electrochemical impedance spectroscopy revealed significantly improved electron transfer kinetics and catalytic activity towards uric acid oxidation. The sensor exhibited a wide linear detection range from 1 μM to 1.2 mM, encompassing both physiological and pathological uric acid levels. Notably, the limit of detection was found to be 0.27 μM, surpassing the performance of most existing metal oxide based uric acid sensors. The sensor also demonstrated excellent anti-interference capability against commonly coexisting species in biological fluids. Furthermore, the practical applicability of the sensor was validated by successfully determining uric acid concentrations in human serum, plasma, and sweat samples, with impressive recovery rates ranging from 96% to 102%. The stability, reproducibility, and cost-effectiveness of the developed sensor make it a promising tool for routine health monitoring and early intervention in athletes, facilitating personalized training and preventing complications associated with uric acid imbalances. The present work offers a significant advancement in non-invasive, reliable, and efficient assessment of uric acid, with potential for widespread implementation in sports medicine and general healthcare.

Multienzyme Mimicking Cascade Mn3O4 Catalyst to Augment Reactive Oxygen Species Elimination and Colorimetric Detection: A Study of Phase Variation upon Calcination Temperature.

Over decades, nanozyme has served as a better replacement of bioenzymes and fulfills most of the shortcomings and intrinsic disadvantages of bioenzymes. Recently, manganese-based nanomaterials have been highly noticed for redox-modulated multienzyme mimicking activity and wide applications in biosensing and biomedical science. The redox-modulated multienzyme mimicking activity was highly in tune with their size, surface functionalization, and charge on the surface and phases. On the subject of calcination temperature to Mn3O4 nanoparticles (NPs), its phase has been transformed to Mn2O3 NPs and Mn5O8 NPs upon different calcination temperatures. Assigning precise structure-property connections is made easier by preparing the various manganese oxides in a single step. The present study has focused on the variation of multienzyme mimicking activity with different phases of Mn3O4 NPs, so that they can be equipped for multifunctional activity with greater potential. Herein, spherical Mn3O4 NPs have been synthesized via a one-step coprecipitation method, and other phases are obtained by direct calcination. The calcination temperature varies to 100, 200, 400, and 600 °C and the corresponding manganese oxide NPs are named M-100, M-200, M-400, and M-600, respectively. The phase transformation and crystalline structure are evaluated by powder X-ray diffraction and selected-area electron diffraction analysis. The different surface morphologies are easily navigated by Fourier transform infrared, field-emission scanning electron microscopy, and high-resolution transmission electron microscopy analysis. Fortunately, for the mixed valence state of Mn3O4 NPs, all phases of manganese oxide NPs showed multienzyme mimicking activity including superoxide dismutase (SOD), catalase, oxidase (OD), and peroxidase; therefore, it offers a synergistic antioxidant ability to overexpose reactive oxygen species. Mn3O4 NPs exhibited good SOD-like enzyme activity, which allowed it to effectively remove the active oxygen (O2•-) from cigarette smoke. A sensitive colorimetric sensor with a low detection limit and a promising linear range has been designed to detect two isomeric phenolic pollutants, hydroquinone (H2Q) and catechol (CA), by utilizing optimized OD activity. The current probe has outstanding sensitivity and selectivity as well as the ability to visually detect two isomers with the unaided eye.

Ultrathin 2D Alloyed Cu−Ga−Zn−S Curved Nanobelts for Boosting Visible‐Light Photocatalytic Hydrogen Evolution

Abstract2D semiconductor nanomaterials have received significant attention as photocatalysts for solar‐to‐hydrogen conversion due to their robust light absorption capacity, large specific surface area, and superior electron transport characteristics. Nevertheless, it is challenging to develop 2D quaternary copper‐based sulfides (QCSs) with functional integration of conducive structural features for photocatalysis from multiple elements and intricate control conditions. Herein, ultrathin 2D alloyed Cu−Ga−Zn−S (CGZS) curved nanobelts (NBs) are fabricated by using a facile one‐pot colloidal method. Subsequently, the derived Cu31S16‐CGZS Janus heterostructures are designed by increasing Cu concentrations. The formation mechanism of 2D curved alloys and Janus heterostructures is systematically investigated. Without cocatalysts, curved alloyed CGZS NBs demonstrated superior photocatalytic activities of 1264.2 µmol g−1 h−1 compared to Janus heterostructured Cu31S16−CGZS (463.1 µmol g−1 h−1) under visible light (> 400 nm). Experimental and theoretical results unveiled that the improved photocatalytic activities of curved CGZS NBs can be attributed to enhanced charge–carrier separation efficiency resulting from high crystallinity and ultrathin 2D structure, abundant active sites from curved structure, high‐active (0001) crystal facet with the lowest reaction Gibbs energy, work function, and metal‐like properties. This work offers new insights into functional integration into ultrathin 2D QCSs with enhanced visible‐light photocatalytic performance.

Solvent-Induced Structural Rearrangement in Ultrasound-Assisted Synthesis of Metal-Organic Frameworks.

Metal-organic frameworks (MOFs) are crystalline extended structures featuring permanent porosity, assembled from metal ions and organic ligands, often synthesized by the solvothermal method (50-260°C, 12-72h). Here, an alternative synthetic approach-solvent-induced structural rearrangement in ultrasound-assisted synthesis is presented. Six representative Zn-based MOFs, each composed of distinct secondary building units, are synthesized within 2-180min consuming less solvent (>0.03m) at room temperature. It is observed that ultrasonication induces the construction of a coordination network, and subsequent solvent exchange triggers structural rearrangement to yield MOFs of high crystallinity and porosity. Furthermore, the scalability of this method is demonstrated through the bulk synthesis of MOF-5, MOF-74, ZIF-8, and MFU-4l within 90min. The initiation of nucleation through ultrasound and the subsequent transformation induced by solvent exchange offer an alternative method for efficiently synthesizing MOFs in bulk, potentially broadening their range of applications.

Exclusion-zone water inside and outside of plant xylem vessels

The fourth phase of water has garnered increased attention within the scientific community due to its distinct properties that differentiate it from regular water. This unique state seems to arise potentially from a liquid crystalline structure, which has been observed near various hydrophilic surfaces to possess the capability of excluding microspheres. Consequently, it has been labeled as exclusion zone (EZ) water. When in contact with hydrophilic surfaces, water could exhibit the ability to form organized layers of EZ water. In this study, we investigated the quick buildup of EZ water exposed to xylem vessels of four vegetable plants: cabbage, celery, asparagus, and pumpkin. Among them, pumpkin vessels showed larger EZs, up to 240 ± 56 μm in width. The width of EZ water found near the xylem vessels of the other plants ranged from 133 ± 22 to 142 ± 20 μm. EZ water generally excludes a wide range of particles, including polystyrene microspheres with various surface modifications, as well as silica microspheres. This implies that the formation of EZ water is not an artificial result of using specific microsphere types but rather demonstrates EZ’s ability to exclude particles regardless of their composition. Inside single xylem vessels of the pumpkin, we could observe the dynamics of EZ buildup, growing from the inside edge of the vessel toward the center. The relationship between vessel diameter, vessel length, and salt concentration on EZ generation inside the xylem vessel was also explored. The results showed that EZ water can build up both inside and outside the xylem vessels. Our findings suggest that EZ generation inside xylem vessels is associated with water flow, likely driven by a proton gradient. Further research is warranted to elucidate the role of EZ water in the physiology of living plants, particularly considering the limitations of the current experiments conducted on cut-out xylem vessel samples.

Comprehensive overview of how to fade into succinate dehydrogenase dysregulation in cancer cells by naringenin-loaded chitosan nanoparticles.

Mitochondrial respiration complexes play a crucial function. As a result, dysfunction or change is intimately associated with many different diseases, among them cancer. The epigenetic, evolutionary, and metabolic effects of mitochondrial complex IΙ are the primary concerns of our review. Provides novel insight intothe vital role of naringenin (NAR) as an intriguing flavonoid phytochemical in cancer treatment. NAR is a significant phytochemical that is a member of the flavanone group of polyphenols and is mostly present in citrus fruits, such as grapefruits, as well as other fruits and vegetables, like tomatoes and cherries, as well as foods produced from medicinal herbs. The evidence that is now available indicates that NAR, an herbal remedy, has significant pharmacological qualities and anti-cancer effects. Through a variety of mechanisms, including the induction of apoptosis, cell cycle arrest, restriction of angiogenesis, and modulation of several signaling pathways, NAR prevents the growth of cancer. However, the hydrophobic and crystalline structure of NAR is primarily responsible for its instability, limited oral bioavailability, and water solubility. Furthermore, there is no targeting and a high rate of breakdown in an acidic environment. These shortcomings are barriers to its efficient medical application. Improvement targeting NAR to mitochondrial complex ΙΙ by loading it on chitosan nanoparticles is a promising strategy.

Saccharification and structural changes in Areca catechu husk fiber

AbstractAreca nut husk (ANH) holds promise as a viable biomass source for xylose production. Xylose is a precursor for various biochemicals. However, the recalcitrant nature of ANH makes saccharification more complex. To address this, lime and acid pretreatments were carried out to enhance the susceptibility of biomass to saccharification. Before this, a compositional analysis was conducted to determine the initial constituents of the feedstock. Saccharification was conducted under the following conditions: 2% (wV−1) substrate loading, 100 rpm agitation, and 30 °C hydrolysis temperature for 12 h hydrolysis time at pH 4.5 to 5.0. However, parameters like xylanase enzyme loading were varied to enhance the saccharification of the ANH. The results demonstrated that acid‐treated husk (ATH), lime‐treated husk (LTH), and raw husk (RH) achieved the highest yield (gg−1) of reducing sugar, approximately 90, 83, and 15%, respectively, at an enzyme loading of 15.0 IUg−1. Various analytical techniques, including Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), zeta potential, thermogravimetric analysis (TGA), X‐ray diffraction (XRD), and field emission scanning electron microscopy (FESEM) were used to examine structural changes in the native, pretreated, and saccharified residues of ANH. The analysis revealed that a significant amount of partial crystalline and amorphous cellulose in the ANH biomass was hydrolyzed during the saccharification process. However, saccharification also led to the removal of amorphous substances, disruption of the crystalline structure, and conversion of crystalline regions into amorphous domains.

Optimizing machining efficiency: a comprehensive study on PVD cathodic arc evaporation coated turning tool inserts with TiAlN/AlCrN multilayer coatings

Abstract The effectiveness of turning processes in manufacturing depends on the efficiency of cutting tool inserts. Coating these inserts is one common method that has been used to prolong their life span, reduce friction and increase wear resistance. The main purpose of the present study was to enhance the efficiency of turning tool inserts by exploring different combinations of coating substances such as TiAlN, AlCrN, and TiAlN/AlCrN. Cutting speed, feed rate, cutting depth and type of coating material were important input parameters for optimization. It was observed that tools with coatings like TiAIN and AlCrN had higher performance than those with single-layered ones. The use of multilayer coated inserts comprising TiAlN/AlCrN increased the hardness but reduced the wear thereby enhancing machining effectiveness. For Taguchi Grey Relation Analysis (GRA) optimization technique with L27 array for hardness and flank wear output parameters aimed at enhancement of input process parameters in turning operations. The coatings’ crystalline structure, phase composition and other crucial details for their performance were analyzed using Energy Dispersive (EDS) Spectroscopy and Scanning Electron (SEM) Microscopy techniques. The TiAlN/AlCrN coatings showed greater machinability than those with only TiAlN or AlCrN, even at high spindle speeds. The best processes were identified using the Taguchi and Grey relational optimization techniques. Some of these parameters include a speed of 600 m/min, a feed rate of 0.10 mm/rev, a depth of 1.5 mm, and a TiAlN/AlCrN coating. This meant that the hardness was at 3772 HV while flank wear is 6.45 mm for optimum parameters among others obtained from experiments. Various relationships can be displayed using contour plots which are usually visual representation between several factors in an experiment such as hardness and wear resistance which is shown by multilayer coating compared to single-layer coatings.

The study of degradation and mechanical properties of poly(lactic) acid (PLA) based 3D printed filament

Abstract Additive manufacturing, commonly known as 3D printing technology, has become one of the mainstream processes in the manufacturing industry due to its advantages over conventional manufacturing, which have piqued the public's interest. This study aims to focus on the influence of thermal conditions on crystallization towards mechanical properties of 3D printed poly(lactic) acid (PLA) degradation samples with 100% infill. As for the degradation profile, the highest weight loss recorded by the samples was 0.7%, observed in samples buried in soil with an abiotic medium for one month. The exposure of degraded samples to high temperature during drying affected their crystallinity, resulting in significant changes in strains, particularly between week 1 and week 2, where strains dropped significantly from 7.33% to 4.28%, respectively. In conclusion, it has been demonstrated that degradation for PLA material still can occur in an abiotic medium, albeit at a slower rate compared to a biotic medium due to the presence of additional microorganisms and bacteria. Besides, the post-heat treatment process on PLA degradation samples affects their crystalline structure, resulting in significant changes in mechanical properties, particularly especially strains. Therefore, it can be concluded that different materials exhibit distinct mechanical properties.

Vapor/Vapor‐Solid Interfacial Growth of Covalent Organic Framework Membranes on Alumina Hollow Fiber for Advanced Molecular Separation

Covalent organic frameworks (COFs), known for their chemical stability and porous crystalline structure, hold promises as advanced separation membranes. However, fabricating high‐quality COF membranes, particularly on industrial‐preferred hollow fiber substrates, remains challenging. This study introduces a novel vapor/vapor‐solid (V/V‐S) method for growing ultrathin crystalline TpPa‐1 COF membranes on the inner lumen surface of alumina hollow fibers (TpPa‐1/Alumina). Through vapor‐phase monomer introduction onto polydopamine‐modified alumina at 170 °C and 1 atm, efficient polymerization and crystallization occur at the confined V‐S interface. This enables one‐step growth within 8 h, producing 100 nm thick COF membranes with strong substrate adhesion. TpPa‐1/Alumina exhibits exceptional stability and performance over 80 h in continuous cross‐flow organic solvent nanofiltration (OSN), with methanol permeance of about 200 L m‐2 h‐1 bar‐1 and dye rejection with molecular weight cutoff (MWCO) of approximately 700 Da. Moreover, the versatile V/V‐S method synthesizes two additional COF membranes (TpPa2Cl/Alumina and TpHz/Alumina) with different pore sizes and chemical environments. Adjusting the COF membrane thickness between 100‐500 nm is achievable easily by varying the growth cycle numbers. Notably, TpPa2Cl/Alumina demonstrates excellent OSN performance in separating the model active pharmaceutical ingredient glycyrrhizic acid (GA) from dimethyl sulfoxide (DMSO), highlighting the method’s potential for large‐scale industrial applications.

“Microwave approach and thermal decomposition: A sustainable way to produce ZnO nanoparticles with different chemo-physical properties”

Two different synthetic approaches such as thermal decomposition method and microwave-assisted procedure were compared for the synthesis of nanosized ZnO. The two procedures were tested using zinc acetate as precursor as is, or in the presence of two coadjutants, one of anthropic origin (melamine) and one derived from the reuse of agricultural waste (wine extracts). All the samples were physico-chemically characterized in order to evaluate the influence of the synthesis conditions on the properties of the materials that were characterized by N2 adsorption/desorption at 77 K and Field Emission-Scanning Electron microscopy measurements for evaluating the morphology, X-ray diffraction for examining the crystalline structure and X-Ray photoelectron spectroscopy for evidencing the surface composition of the nanoparticles. In order to verify the influence of the synthesis procedure on the electrical and optical properties of the ZnO nanoparticles, forecasting their use in photocatalytic applications, also the band gap of materials was evaluated by means of UV–Vis spectroscopy and Tauc plot. A final comparison of all the results allowed to evidence advantages and disadvantages of the procedures under study pointing out the importance of deepen the study of microwave-based synthetic approaches.

Vapor/Vapor-Solid Interfacial Growth of Covalent Organic Framework Membranes on Alumina Hollow Fiber for Advanced Molecular Separation.

Covalent organic frameworks (COFs), known for their chemical stability and porous crystalline structure, hold promises as advanced separation membranes. However, fabricating high-quality COF membranes, particularly on industrial-preferred hollow fiber substrates, remains challenging. This study introduces a novel vapor/vapor-solid (V/V-S) method for growing ultrathin crystalline TpPa-1 COF membranes on the inner lumen surface of alumina hollow fibers (TpPa-1/Alumina). Through vapor-phase monomer introduction onto polydopamine-modified alumina at 170 °C and 1 atm, efficient polymerization and crystallization occur at the confined V-S interface. This enables one-step growth within 8 h, producing 100 nm thick COF membranes with strong substrate adhesion. TpPa-1/Alumina exhibits exceptional stability and performance over 80 h in continuous cross-flow organic solvent nanofiltration (OSN), with methanol permeance of about 200 L m-2 h-1 bar-1 and dye rejection with molecular weight cutoff (MWCO) of approximately 700 Da. Moreover, the versatile V/V-S method synthesizes two additional COF membranes (TpPa2Cl/Alumina and TpHz/Alumina) with different pore sizes and chemical environments. Adjusting the COF membrane thickness between 100-500 nm is achievable easily by varying the growth cycle numbers. Notably, TpPa2Cl/Alumina demonstrates excellent OSN performance in separating the model active pharmaceutical ingredient glycyrrhizic acid (GA) from dimethyl sulfoxide (DMSO), highlighting the method's potential for large-scale industrial applications.

Multi-Scale Traditional and Non-Traditional Machining of Bulk Metallic Glasses (BMGs)—Review of Challenges, Recent Advances, and Future Directions

Bulk metallic glasses (BMGs) are growing in popularity prominently due to their potential in micro-electromechanical systems (MEMSs) and aerospace applications. BMGs have unique mechanical properties, i.e., high strength, hardness, modulus of elasticity, and wear resistance, due to their disordered atomic structure. Due to their unique mechanical properties and amorphous structures, machining of BMGs remains a challenge. This paper aims to carry out a detailed literature review on various aspects of the machining of bulk metallic glasses using both conventional and non-conventional processes, including experimental approaches, modeling, statistical findings, challenges, and guidelines for machining this difficult-to-machine material. Conventional machining processes were found to be challenging for machining bulk metallic glasses due to their high hardness, brittleness, and tendency to convert their amorphous structure into a crystalline structure, especially at the machined surface and sub-surface. Although their high electrical conductivity makes them suitable for machining by non-conventional processes, they impose new challenges such as heat-affected zones and crystallization. Therefore, the successful machining of BMGs requires more in-depth analysis of cutting forces, tool wear, burr formation, surface finish, recast layers or heat-affected zones, crystallization, and mechanical property changes among different varieties of BMGs. This review paper provides guidelines emerging from in-depth analysis of previous studies, as well as offering directions for future research in the machining of BMGs.