Changes in the oxygen content,morphology, and microstructure of Mo-10Nb composite powders during mechanical alloying

The prefabrication of Mo-Nb composite powders is an effective way of improving the homogeneity of Mo-10Nb targets, which have broad application prospects in the photoelectric sensor industry. However, this aspect has been rarely addressed so far. Therefore, we prepared Mo-10Nb composite powders by mechanical alloying (MA), and investigated the effects of the experimental parameters such as the milling speed and duration on the particle morphology, size distribution, compositional homogeneity, crystallite size, inner strain, and oxygen content. High-quality Mo-10Nb composite powders with 3-μm spherical particles of narrow size distribution, homogeneous elemental distribution, and nanometric crystalline structure were obtained by implementing optimum MA parameters, viz., a milling speed of 250 rpm and duration of 36 h using an MITR QM-QX-4L omnidirectional ball mill. The mechanically alloyed Mo-10Nb composite powders were prone to oxidation when exposed to air, which led to a sharp increase in the oxygen content to ~5400 ppm. X-ray photoelectron spectroscopic analysis revealed the presence of Nb₂O₅, MoO₂, and MoO₃ on the surface of the Mo-10Nb particle. We believe that this study demonstrates an interesting strategy for the fabrication of high-quality Mo-10Nb targets.     

Recent breakthroughs and perspectives of high-energy layered oxide cathode materials for lithium ion batteries

Ni-rich layered oxides (NRLOs) and Li-rich layered oxides (LRLOs) have been considered as promising next-generation cathode materials for lithium ion batteries (LIBs) due to their high energy density, low cost, and environmental friendliness. However, these two layered oxides suffer from similar problems like capacity fading and different obstacles such as thermal runaway for NRLOs and voltage decay for LRLOs. Understanding the similarities and differences of their challenges and strategies at multiple scales plays a paramount role in the cathode development of advanced LIBs. Herein, we provide a comprehensive review of state-of-the-art progress made in NRLOs and LRLOs based on multi-scale insights into electrons/ions, crystals, particles, electrodes and cells. For NRLOs, issues like structure disorder, cracks, interfacial degradation and thermal runaway are elaborately discussed. Superexchange interaction and magnetic frustration are blamed for structure disorder while strains induced by universal structural collapse result in issues like cracks. For LRLOs, we present an overview of the origin of high capacity followed by local crystal structure, and the root of voltage hysteresis/decay, which are ascribed to reduced valence of transition metal ions, phase transformation, strains, and microstructure degradation. We then discuss failure mechanism in full cells with NRLO cathode and commercial challenges of LRLOs. Moreover, strategies to improve the performance of NRLOs and LRLOs from different scales such as ion-doping, microstructure designs, particle modifications, and electrode/electrolyte interface engineering are summarized. Dopants like Na, Mg and Zr, delicate gradient concentration design, coatings like spinel LiNi_0.5Mn_1.5O₄ or Li₃PO₄ and novel electrolyte formulas are highly desired. Developing single crystals for NRLOs and new crystallographic structure or heterostructure for LRLOs are also emphasized. Finally, remaining challenges and perspectives are outlined for the development of NRLOs and LRLOs. This review offers fundamental understanding and future perspectives towards high-performance cathodes for next-generation LIBs.     

Characterization of solid-electrolyte/active-material composite particles with different surface morphologies for all-solid-state batteries

In all-solid-state lithium-ion batteries (ASS-LIBs), the electrode structure is an important factor that determines the battery performance; in particular, the formation of contact interface between the active material (AM) and solid electrolyte (SE) is an important issue associated with ASS-LIBs. Although we previously reported the formation of interfacial contacts between AM and SE by dry coating, the influence of the surface morphologies of composite particles on the performance of ASS-LIB was not revealed. In this study, we investigated the effects of the surface morphologies of composite particles on the performance of ASS-LIB. The surface morphologies of composite particles changed from “discrete” to “continuous” as the dry coating progressed. The cell prepared with composite particles showed higher ionic conductivity due to well-percolated ionic path than that prepared with simple mixture. Comparing the composite particles with different surface morphologies, the cell prepared with discrete-coating particles showed lower internal resistance due to higher ionic/electrical conductivity than that prepared with continuous-coating particles. Further, the cells prepared with discrete- and continuous-coating particles showed the highest charge and discharge capabilities, respectively. The results suggest that the contact areas of AM-SE and AM-AM were critical structural factors for the discharge and charge rate capability, respectively.     

Stabilizing effect of the cyclodextrins additive to spray-dried particles of curcumin/polyvinylpyrrolidone on the supersaturated state of curcumin

Although curcumin is considered to have various therapeutic effects, its use as a functional food or supplement is restricted owing to its low water solubility and bioavailability. To increase the solubility of curcumin in water, the use of polyvinylpyrrolidone (PVP) and vinylpyrrolidone-vinyl acetate copolymers with a pyrrolidone skeleton was noted to be promising. In particular, the bi-component formulations of curcumin/PVP prepared through spray drying exhibited an amorphous state in powder X-ray diffraction observations and temporally increased the apparent solubility of curcumin to over 5000 times that of untreated curcumin; nevertheless, after 24 h, the solubility decreased owing to the unstable supersaturated state of curcumin. The addition of α-cyclodextrin (α-CyD) in the bi-component curcumin/PVP formulation helped maintain the supersaturated state of curcumin, whereas the addition of β- and γ-CyD led to the collapse of the supersaturated state. The addition of α-CyD can likely help inhibit the nucleation and crystal growth of curcumin, through the interaction among the solubilized units of curcumin/PVP and α-CyD.     

Designing amorphous formulations of polyphenols with naringin by spray-drying for enhanced solubility and permeability

Naringin (NAR), a major flavanone (FVA) glycoside, is a component of food mainly obtained from grapefruit. We used NAR as a food additive to improve the solubility and permeability of hydrophobic polyphenols used as supplements in the food industry. The spray-dried particles (SDPs) of NAR alone show an amorphous state with a glass transition temperature (T_g) at 93.2 °C. SDPs of hydrophobic polyphenols, such as flavone (FVO), quercetin (QCT), naringenin (NRG), and resveratrol (RVT) were prepared by adding varying amounts of NAR. All SDPs of hydrophobic polyphenols with added NAR were in an amorphous state with a single T_g, but SDPs of hydrophobic polyphenols without added NAR showed diffraction peaks derived from each crystal. The SDPs with NAR could keep an amorphous state after storage at a high humidity condition for one month, except for SDPs of RVT/NAR. SDPs with NAR enhanced the solubility of hydrophobic polyphenols, especially NRG solubility, which was enhanced more than 9 times compared to NRG crystal. The enhanced solubility resulted in the increased membrane permeability of NRG. The antioxidant effect of the hydrophobic NRG was also enhanced by the synergetic effect of NAR. The findings demonstrated that NAR could be used as a food additive to enhance the solubility and membrane permeability of hydrophobic polyphenols.     

Improving hydrothermal performance of hybrid nanofluid in double tube heat exchanger using tapered wire coil turbulator

Tapered wire coil insert is proposed as a novel enhancer in the double tube heat exchanger and experimental studies on Al₂O₃ + MgO hybrid nanofluid flowing under the turbulent condition are performed to investigate the hydrothermal characteristics. Effects of using tapered wire coil turbulator and hybrid nanofluid on the hydrothermal behaviors are examined for different coil configurations (Converging (C) type, Diverging (D) type and Conversing-Diverging (C-D) type) and hybrid nanofluid inlet temperatures and volume flow rates. Results show that D-type wire coil insert promotes better hydrothermal performance as compared to C-type and C-D type. Nusselt number and friction factor of hybrid nanofluid using D-type, C-D type and C-type wire coil inserts enhance up to 84%, 71% and 47%, and 68%, 57% and 46%, respectively than that of water in tube without insert. The entropy generation of hybrid nanofluid is lower than that of base fluid in all cases. The thermal performance factor for hybrid nanofluid is found more than one with all inserts. The thermal performance factor is observed a maximum of 1.69 for D-type coil. The study reveals that the hybrid nanofluid and tapered wire coil combination is promising option for improving the hydrothermal characteristics of double pipe heat exchanger.     

Machine learning aided nanoindentation: A review of the current state and future perspectives

The solution of instrumented indentation inverse problems by physically-based models still represents a complex challenge yet to be solved in metallurgy and materials science. In recent years, Machine Learning (ML) tools have emerged as a feasible and more efficient alternative to extract complex microstructure-property correlations from instrumented indentation data in advanced materials. On this basis, the main objective of this review article is to summarize the extent to which different ML tools have been recently employed in the analysis of both numerical and experimental data obtained by instrumented indentation testing, either using spherical or sharp indenters, particularly by nanoindentation. Also, the impact of using ML could have in better understanding the microstructure-mechanical properties-performance relationships of a wide range of materials tested at this length scale has been addressed.The analysis of the recent literature indicates that a combination of advanced nanomechanical/microstructural characterization with finite element simulation and different ML algorithms constitutes a powerful tool to bring ground-breaking innovation in materials science. These research means can be employed not only for extracting mechanical properties of both homogeneous and heterogeneous materials at multiple length scales, but also could assist in understanding how these properties change with the compositional and microstructural in-service modifications. Furthermore, they can be used for design and synthesis of novel multi-phase materials.     

Screening of sugars and cyclodextrins as carriers in montelukast dry powder inhalers processed by spray freeze drying

The purpose of this study was to develop a site targeting montelukast sodium (MTK) microparticles as a respiratory drug delivery system using the spray freeze drying (SFD) process. A range of sugars and cyclodextrins (CDs) were screened as carrier in order to find compatible excipients for the preparation of dry powder inhalers (DPIs). The physical characteristics of collected powders were studied by scanning electron microscopy (SEM), laser light scattering, differential scanning calorimetry (DSC), and X-ray diffraction (XRD). The aerodynamic behavior of the particles was also assessed using twin stage impinge (TSI). In the presence of simple sugars as carriers, highly porous particles in irregular shapes were produced. The use of CDs resulted in the formation of spherical particles with high porosity. Among all carriers that were used during the preparation of powders, raffinose had the best aerodynamic behavior with a fine particle fraction (FPF) of 60 % in sugar groups, while the lowest FPF was related to trehalose as carrier. Powders containing CDs mostly showed proper aerodynamic behavior, especially in formulations containing alfa-cyclodextrin (A-CD), beta-cyclodextrin (β-CD), and highly branched cyclic dextrin (HBCD). Overall, data indicated that the CDs were excellent excipients for use with MTK for respiratory drug delivery.     

pH-responsive dual-functional hydrogel integrating localized delivery and anti-cancer activities for highly effective therapy in PDX of OSCC

As one of the most promising localized drug delivery systems for enhancing therapeutic efficacy and reducing systemic toxicity, supramolecular hydrogels self-assembled from natural products have recently attracted tremendous attention. However, the intricate drug loading process, limited drug entrapment efficacy, and lack of stimulus responsiveness considerably impede their potential for biological applications and raise the need for advanced hydrogel-based delivery systems. Therefore, the development of updated materials that integrate localized delivery and drug activity into a single system is extremely desired and has great potential to overcome the aforementioned shortcomings. In this study, a pH-responsive dual-functional isoG-based supramolecular hydrogel with both localized delivery and anti-cancer activity in one molecule is successfully developed in one pot by following a simple and green procedure. The isoguanosine-phenylboronic-guanosine (isoGPBG) hydrogel exhibits exceptional stability (more than one year), outstanding pH-responsiveness and excellent sustained release capability. Both in vitro and in vivo experiments demonstrate that the isoGPBG hydrogel not only shows acceptable biocompatibility and biodegradability but also significantly inhibit tumor growth (approximately 60% inhibition of tumor growth) and improve overall survival, especially in preclinical patient-derived xenograft (PDX) model of oral squamous cell carcinoma (OSCC). Therefore, the isoGPBG hydrogel, to the best of our knowledge, is the first example of pH-responsive dual-functional isoG-based supramolecular hydrogel integrating localized delivery and anti-cancer activity in one molecule. It is implied that the isoGPBG hydrogel could act as a smart dual-functional localized delivery system in the future for clinical cancer therapy.     

Electrochemical treatment of soil-washing effluent with boron-doped diamond electrodes: A review

In recent years, electrochemical technologies have been widely used to remove contaminants at lab-scale and semi-pilot scale. Boron-doped diamond (BDD) electrodes have been considered as efficient materials for the abatement of persistent organic pollutants owing to their outstanding properties, such as rapid rates of electron-transfer for soluble redox systems, wide electrochemical potential window for water discharge reactions in aqueous and non-aqueous electrolytes, and high stability. Similar to other applications of electrochemical technology, wastes display medium to high ionic conductivity. Therefore, one of the applications highlighted for the electrolysis with these new electrodes is the treatment of soil-washing fluids, because in the polluted streams, washing of polluted soils provides a suitable conductivity to the effluent. In this context, this review summarizes the application of conductive diamond anodes for the electrochemical treatment of soil-washing effluents contaminated with different persistent organic pollutant such as pesticides, hydrocarbons, dyes, and organochlorine compounds, in single anodic oxidation processes and in other more complex processes such as electro-Fenton, photoelectrolysis, or sonoelectrolysis. Finally, the challenges and future research directions of electrochemical technology are discussed and outlined at pilot and prototype scale.     

Synthesis,structure, and mechanical response of Cr0.26Fe0.24Al0.5 and Cr0.15Fe0.14Al0.30Cu0.13Si0.28 nanocrystallite entropy alloys

The present research work has concentrated to synthesize nanocrystalline (NC) Cr_0.26Fe_0.24Al_0.5 (medium entropy alloy, 3E-MEA) and Cr_0.15Fe_0.14Al_0.30Cu_0.13Si_0.28 (high-entropy alloy, 5E-HEA) non-equiatomic (equal weight fraction) alloys through mechanical alloying (MA); which studied the influence of entropy effect on structural properties, microstructural characterization, and mechanical behaviour. Further, the same non-equiatomic ratio of two coarse grain alloys (CGAs) was manufactured by conventional powder metallurgy (PM) route (blending method, 3E-CGA, 5E-CGA) for comparison. All synthesized powders were hot-pressed (HPed) at 723 k for 30 min subsequently mechanical properties in terms of compressive stress-strain and hardness were examined. The samples of as-milled powders, HPed, and fractured were investigated using X-ray diffraction (XRD) and advanced electron microscopes. The HPed sample of 3E-MEA of Cr_0.26Fe_0.24Al_0.5 produced 94% BCC and 6% FCC crystal structures due to more dissolution of Al atoms in the stronger bonding atoms of Cr-Fe lattice. Whereas 5E-HEA of Cr_0.15Fe_0.14Al_0.30Cu_0.13Si_0.28 sample has exhibited 72.1% FCC phase and 27.9% BCC phase due to balance between the dissolution of FCC elements (Al, Cu, Si) and BCC elements (Cr, Fe). Further, 3E-MEA and 5E-HEA have exhibited the ultimate compressive strength (UCS) of 1278 ± 6.75 MPa and 2060 ± 2.8 MPa respectively whereas the corresponding conventionally blended alloys produced 268 ± 5 MPa and 615 ± 3 MPa for 3E-CGA and 6E-CGA respectively. Vicker’s hardness strength (VHS) of 5E-HEA of Cr_0.15Fe_0.14Al_0.30Cu_0.13Si_0.28 has exhibited 68% more when compared to 3E-MEA of Cr_0.26Fe_0.24Al_0.5, 3.26 times higher compared to blended alloys. Further, several strengthening mechanisms on the mechanical behaviour of MEA and HEA were investigated in which dislocation strengthening mechanisms followed by solid solution strengthening mechanisms have influenced more as compared to grain boundary strengthening mechanisms.     

Steel slag waste combined with melamine pyrophosphate as a flame retardant for rigid polyurethane foams

To explore the potential application of industrial waste, steel slag powder in combination with melamine pyrophosphate (MPP) was adopted to improve the flame retardancy of rigid polyurethane foam (RPUF). The incorporation of steel slag slightly reduced the thermal conductivity of the resulting flame-retardant RPUF samples. The addition of MPP and/or steel slag did not significantly alter the thermal stability in terms of T_-10% and T_max but did obviously increase the T_-50% value, suggesting the improved thermal resistance of the residues. The coaddition of MPP and steel slag into RPUF resulted in higher LOI values and lower peak heat release rates than the samples incorporating either MPP or steel slag alone. The superior flame retardancy could be attributed to MPP promoting char formation, which then acted as a barrier at the beginning of RPUF thermal decomposition; simultaneously, the thermally stable inorganics in the steel slag powder strengthened the thermal resistance of this char layer.     

Granulation of ibuprofen/isonicotinamide co-crystals by continuous spray granulator (CTS-SGR)

The importance of granulation is paramount for tablet manufacturing, and is based on the fact that granulated powders are characterized by improved flowability, compressibility, segregation, and dust reduction. The aim of this study was to prepare and characterize continuous granules of high drug content by using a continuous-spray granulator (CTS-SGR). Ibuprofen (IBU), a drug of low-flowability, was selected as the model drug. As IBU has a low melting point and cannot easily granulate on its own, we employed isonicotinamide (INA) as a coformer that would allow us to prepare co-crystal granules containing 60 % IBU. The results of the undertaken differential scanning calorimetry and powder X-ray diffraction revealed that the IBU and the INA in the granules formed co-crystals. The granulation conditions affected the particle size and the yield of the granules; in fact, a low air supply temperature, a low atomizing air rate, and a high solution flow rate ensured a high granulation efficiency. Moreover, continuous granulation increased the yields of the formulations compared to those obtained through a short-run granulation, and high yields were obtained after applying a low atomizing air rate. The circularity of the granules exceeded 90 %, and their flowability improved when compared to that of the IBU bulk. The undertaking of dissolution studies revealed no change in the elution amount of IBU as a result of the co-crystallization. Our study shows that it is possible to produce high-content IBU granules in a direct and continuous manner through the co-crystallization of IBU and the use of a CTS-SGR.     

Virus meet metal-organic frameworks: A nanoporous solution to a world-sized problem?

Laboratory diagnosis of pathologies caused by virus plays a critical role in outbreak response efforts and establishing safe and expeditious testing strategies. Detection of pathogenic virus using commercial solutions require specific tools and laborious laboratory procedures. This makes the day-to-day on time detection of virus infections the limiting step in any outbreak. The need for new diagnostic tools easily available to poor and rural underdeveloped areas where health infrastructure and trained personnel are scarce is highly desirable. The widely known intrinsic properties of Metal-Organic Frameworks (MOFs) embody them with the potential to overcome some of the challenges inherent to virus detection. MOFs are already components of functional devices capable of perform an uninterrupted detection of molecular targets in real time. In this review, we summarise the few studies concerning the reported MOFs used as sensors for pathogenic virus. We emphasise the structural and physical properties of these materials which can open the possibility for their use in this type of sensors and conclude on how the field can progress to envisage the usage of MOFs by the pharmaceutical industry to develop new sensors for these sub-microscopic infectious agents.     

Powder flow and mixing in different tablet press feed frames

Tablets can be manufactured using a rotary tablet press, which consists of a feed frame followed by the compression and compaction of the powder and subsequent ejection of the tablets. From Quality by Design (QbD) perspectives the feed frame plays a critical role and effects products critical quality attributes (CQAs). Thus optimizing this stage is of huge interest. It is preferable to achieve narrow residence time distributions of the powder in the feed frames as well as homogeneous tablets with respect to their height, weight and tensile strength. In the present study three design approaches of feed frames are simulated using the Discrete Element Method (DEM). We investigate the influence of operational input parameters (i.e., rotational rates) on the behaviour of a free flowing and a cohesive material. The detailed simulation data allows us to compare the mentioned setups in terms of residence times, tablet masses and occurring deviations. Therefore, we are able to determine the optimal feed frame and process settings for both free-flowing and cohesive powders.     

CFD modelling and simulation of an industrial scale continuous fluidized bed roaster

In the present work, computational fluid dynamics (CFD) based modelling of an industrial scale continuous fluidised bed roaster (FBR) has been carried out to study its performance at different operating conditions, so that the sulphide-sulphur content in the product is within 0.4% at the designed feed rate of 39.75 DMT/h. Eulerian-Eulerian multiphase model, considering four granular phases and one gas phase has been implemented to investigate the velocity and mass fraction profile of the particles in the FBR. The heat and species mass balance calculations have been performed external to CFD, by dividing the roaster into several sections. The conversion of ZnS to ZnO at various sections of the roaster has been estimated using reaction kinetics under isothermal condition (1203 K). The heat liberated and possible temperature rise at each section was predicted based on the heat of reaction and sensible heat of the solid and gaseous products. The CFD model was validated with the plant data for a feed rate of 36.5 DMT/h, air flow rate of 65,000 Nm³/h and O₂ content of 21%. The proposed model predicted the sulphide-sulphur content in the product to be 0.4% for the designed feed rate of 39.75 DMT/h, when the O₂ content in the inlet air was increased to 25%.     

Novel preparation approach with a 2-step process for spherical particles with high drug loading and controlled size distribution using melt granulation: MALCORE®

A novel approach for preparing drug-containing particles (DCPs) with controlled size distribution and high drug loading was developed using melt granulation. This approach comprises two steps. First, melting component adsorbed particles (MAs) were prepared by mixing and heating the melting components with a porous carrier using a high shear granulator. Second, DCPs were prepared by layering the drug on MAs using a fluidized bed rotor granulator. The time taken for both steps was within 30 min. Adding the polymer in the second step remarkably increased the viscosity of the mixture of melting components and the polymer. Therefore, DCPs could be successfully loaded with a high amount of drug (70% w/w). The particle size distribution of the DCPs was narrow, and it depended on that of the MAs. The flowability of the DCPs was excellent, and the sphericity was close to 1. A unique particle formulation mechanism was suggested based on the observation of DCPs using scanning electron microscopy. The manufacturing time and DCP characteristics were not affected by the manufacturing scale. In conclusion, we have successfully developed a highly efficient novel approach for preparing optimal DCPs through melt granulation, named “Melt Adsorption and Layering with Porosity Core” (MALCORE®).     

Understanding the formation of ultrafine maltodextrin particles under simultaneous convective drying and antisolvent vapour precipitation

Research on simultaneous antisolvent-vapour-induced precipitation and convective drying of a solute-containing droplet was extensively conducted since this technique was introduced. However, the internal droplet compositions, which were suggested to be related to the formation of particle morphologies, had not been explored. Herein, the ethanol-vapour-induced precipitation of multi-solvent droplets containing maltodextrin as the solute was used to analyse internal droplet compositions. The droplet mass and diameter profiles were obtained via an established single-droplet drying experiment, which mimicked the spray drying of droplets. Analysis revealed that the antisolvent concentration increased with time and was higher than solvent concentration towards the end of the process. It is interesting to find out that the final particle morphology was profoundly impacted by the ambient ethanol humidity and also how spontaneous the subsequent drying was during ethanol-vapour-induced precipitation of the solutes. The formation of the porous structure was favoured with the occurrence of spontaneous vaporization once the ethanol was present for precipitation. Therefore, low ethanol humidity (20% ERH in this study) was sufficient. In contrast, higher ethanol humidity (>70% ERH) was preferable to produce spherical particles. This study provides an insight into particle engineering to unveil the internal droplet conditions and physical phenomena during this unique process.     

Immersed-boundary/soft-sphere method for particle–particle-fluid interaction in a viscous flow: An OpenFOAM solver

We developed a stable OpenFOAM solver for Immersed Boundary Method based on direct forcing and regularized delta function. The soft-sphere model and a lubrication model were implemented to consider particle–particle collision in a viscous flow. We proposed a fluid–structure interaction (FSI) coupling method to accurately calculate the fluid forcing term and particle velocity. Our solver was validated for fixed and moving bodies, including rotation. The accuracy of various FSI schemes was evaluated in predicting the solid and fluid flow behavior in a viscous flow. It was demonstrated that neglecting or simplifying the fluid momentum change affects the accuracy of the solid velocity and fluid flow dynamic; for higher solid-to-fluid density ratios, a larger deviation was predicted. Furthermore, the FSI schemes highly influenced the behavior of the formed vortices.The solver was validated to predict the effective restitution coefficient of particles in a viscous flow as a function of the Stokes number. We also thoroughly analyzed the dynamic flow behavior of colliding particles through the pressure and velocity field and fluid force. This analysis helped us accurately determine the rebound velocity of particles in case of high Stokes numbers when the effect of viscous force is significant.