Chemometrics analysis of the flow and thermal properties of cardaba banana starch.

BACKGROUND: Starch from a non-conventional source such as cardaba banana is relatively underexplored compared to conventional sources such as potato, maize or tapioca. Its high amylose content, however, suggests its suitability for specific industrial uses. Understanding the flowability, rheology and thermal properties of cardaba banana starch could lead to its novel application in food product formulation and pharmaceutical industry. Therefore, the present study aimed to examine the effect of modification on the bulk material characterization (powder flowability), granule size and shape (measured by light microscope), rheology and thermal properties of cardaba banana starch. RESULTS: The flowability of cross-linked starch was affected significantly by the granule size (105 892.7 µm), shape (circularity 0.78) and compressibility (0.20), making it a more free-flowing powder than other starch powders. The rheological behavior of the starch paste revealed that the Herschel-Bulkley model best predicts the rheological behavior with the highest coefficient of determinant (R2 > 0.9). CONCLUSION: Cross-linked Cardaba banana starch with an excellent characteristic will find good application in food products that require free-flowing behavior. © 2024 Society of Chemical Industry.

Comprehensive investigation of recycled PVC powder.

This study constitutes a comprehensive investigation centred on comprehending the behaviour and characteristics of recycled polyvinyl chloride (PVC) powders. The overarching objective is to successfully conclude the initial research phase, during which PVC-coated fabric offcuts undergo a transformation into PVC powder while achieving complete separation from polyethylene terephthalate fibres. The study entails a qualitative description of the morphology of PVC powder particles, employing an optical microscope to distinguish the diverse shapes exhibited by these particles. The optical microscope observations of PVC powder reveal a distinct array of non-spherical particles characterized by flat, elongated shapes. These high-magnification images unveil the intricate morphological features of the particles, highlighting their irregular shapes. Subsequently, a quantitative analysis of PVC particle size distribution is performed, comparing results from optical microscopy with those obtained through mechanical sieving. The qualitative and quantitative findings obtained provide robust evidence supporting the correlation and confirm that most particles are smaller than 600 µm (93.6%) using an optical microscope and the sieving process (96.39%). The greatest fraction (83.44%) is in the size range between 200 and 600 µm. Assessing flowability, another significant aspect in the evaluation of powders, provides insights into its behaviour and interparticle interactions. The flowability results indicate a Compressibility Index of approximately 26.84%, which suggests poor flowability. This means that the powder is likely to encounter difficulties in flowing freely. This finding is in line with the Hausner ratio, which measures 1.37. This investigation of recycled PVC powder will offer insights into the potential applications and processing considerations of this powder. More concretely, the use of recycled PVC powder shows promise as a viable alternative to conventional PVC resin in plastisol formulations, offering the potential to maintain the properties of the final PVC product without adverse effects.

Selection of Silica Type and Amount for Flowability Enhancements via Dry Coating: Contact Mechanics Based Predictive Approach.

PURPOSE: To investigate the effect of dry coating the amount and type of silica on powder flowability enhancement using a comprehensive set of 19 pharmaceutical powders having different sizes, surface roughness, morphology, and aspect ratios, as well as assess flow predictability via Bond number estimated using a mechanistic multi-asperity particle contact model. METHOD: Particle size, shape, density, surface energy and area, SEM-based morphology, and FFC were assessed for all powders. Hydrophobic (R972P) or hydrophilic (A200) nano-silica were dry coated for each powder at 25%, 50%, and 100% surface area coverage (SAC). Flow predictability was assessed via particle size and Bond number. RESULTS: Nearly maximal flow enhancement, one or more flow category, was observed for all powders at 50% SAC of either type of silica, equivalent to 1 wt% or less for both the hydrophobic R972P or hydrophilic A200, while R972P generally performed slightly better. Silica amount as SAC better helped understand the relative performance. The power-law relation between FFC and Bond number was observed. CONCLUSION: Significant flow enhancements were achieved at 50% SAC, validating previous models. Most uncoated very cohesive powders improved by two flow categories, attaining easy flow. Flowability could not be predicted for both the uncoated and dry coated powders via particle size alone. Prediction was significantly better using Bond number computed via the mechanistic multi-asperity particle contact model accounting for the particle size, surface energy, roughness, and the amount and type of silica. The widely accepted 200 nm surface roughness was not valid for most pharmaceutical powders.

The preparation, characterization, and application of porous core-shell composite particles produced with laboratory-scale spray dryer.

OBJECTIVE: To prepare porous core-shell composite particles (PCPs) in order to improve the flowability and compactibility of powder materials for direct compaction (DC), as well as the dissolution of tablets. SIGNIFICANCE: The results obtained are meaningful to boosting the development and further research of PCPs on DC. Methods: In this study, hydroxypropyl methylcellulose (HPMC E3) and polyvinylpyrrolidone (PVP K30) were selected as shell materials, the Xiao Er Xi Shi formulation powder (XEXS) was used as the core materials, ammonium bicarbonate (NH4HCO3), and sodium bicarbonate (NaHCO3) were employed as pore-forming agent. Using co-spray drying method to prepare composite particles (CPs). Then, the physical properties and comparison between different CPs were characterized comprehensively. Finally, the different CPs were directly compacted as tablets to explore the effect on the dissolution behavior of DC tablets, respectively. RESULTS: (i) The XEXS PCPs were prepared successfully by co-spray drying, and the yield of PCPs is almost 80%; (ii) The TS values of PCP-X-P-Na, PCP-X-P-NH4, PCP-X-H-Na and PCP-X-P-Na were 5.70, 7.56, 3.98, and 6.88 times higher than that of raw material (X); (iii) The disintegration time of PCPs tablets decreased 10-25% when compared with CPs tablets; (iv) The values of Carr's index (CI), Hausner ratio (HR), Caking strength (CS), and Cohesion index (CoI) of PCP-X-H-NH4 were 19.16%, 19.29%, 40.14%, and 6.39% lower than that of X, respectively. CONCLUSIONS: The PCPs prepared by co-spray drying did improve the flowability and compactibility of powder, as well as the dissolution of tablets.

Preparation of Free-Flowing Spray-Dried Amorphous Composites Using Neusilin®.

A highly porous additive, Neusilin®, with high adsorption capability is investigated to improve bulk properties, hence processability of spray-dried amorphous solid dispersions (ASDs). Griseofulvin (GF) is applied as a model BCS class 2 drug in ASDs. Two grades of Neusilin®, US2 (coarser) and UFL2 (finer), were used as additives to produce spray-dried amorphous composite (AC) powders, and their performance was compared with the resulting ASDs without added Neusilin®. The resulting AC powders that included Neusilin® had greatly enhanced flowability (flow function coefficient (FFC) > 10) comparable to larger particles (100 µm) yet had finer particle size (< 50 µm), hence retaining the advantage of fast dissolution rate of finer sizes. Dissolution results demonstrated that achieved GF supersaturation for AC powders with Neusilin® was as high as 3 times that of crystalline GF concentration and was achieved within 30 min. In addition, 80% of drug was released within 4 min. The flowability improvement for AC powders with Neusilin® was more significant as compared to spray-dried ASDs without Neusilin®. Thus, the role of Neusilin® in flowability improvement was evident, considering that spray-dried AC with Neusilin® UFL2 has higher FFC than ASDs having a similar size. Lastly, the AC powders retained a fully amorphous state of GF after 3-month ambient storage. The overall results conveyed that the improved flowability and dissolution rate could outweigh the loss of drug loading resulted by addition of Neusilin®.

Application of co-processed excipients for developing fast disintegrating tablets: A review.

The introduction of tablet dosage forms has brought a revolution in the pharmaceutical drug delivery system. Different forms of tablets have been developed based on the target site, the onset of action, and therapeutic drug delivery methods. Fast-disintegrating tablets (FDTs) are the most promising pharmaceutical dosage form, especially for pediatric and geriatric patients having difficulty swallowing. The key feature of FDTs is quick drug release soon after their administration through the oral cavity. With innovations in the formulation of FDTs, the demand for excipients with better functionalities, particularly in terms of flow and compression characteristics, has increased. Co-processed excipients are a mixture of 2 or more conventional excipients that provides significant benefits over the individual excipients while minimizing their shortcomings. Such multifunctional co-processed excipients minimize the number of excipients that are to be incorporated into tablets during the manufacturing process. The present review discusses FTDs formulated from co-processed excipients, their manufacturing techniques, and the latest research, patents and commercially available co-processed FDTs.

Improving the Effectiveness of the Conical Screen Mill as a Dry-Coating Process at Lab and Manufacturing Scale.

The conical screen mill (comill) is investigated as a dry-coating process for flowability and bulk density enhancement of pharmaceutical powders. In this study, the effectiveness of the comill is improved by using modified screens with reduced open area. In comparison to the screens provided by the comill manufacturer, the modified screens increase mean residence time of the process and improve the extent of flowability and bulk density enhancement. The effectiveness of the comill as a dry-coating process is demonstrated using Avicel PH 105, a fine grade of microcrystalline cellulose, as a model cohesive powder. The process is evaluated thoroughly using a lab scale comill and scalability is demonstrated using a manufacturing scale model. The use of the modified screens is also compared against the so-called "multi-pass" approach in which material is passed through the comill, collected, and passed through once or several times. While the "multi-pass" approach is offered as a simple method to increase mean residence time and to improve process effectiveness, the use of the modified screens is shown to be the superior approach. Due to the ubiquitous use of the comill and the improvement in effectiveness attained in this study, dry-coating is shown to be a practical and readily implemented process for the pharmaceutical industry.

Improving the Manufacturability of Cohesive and Poorly Compactable API for Direct Compression of Mini-tablets at High Drug Loading via Particle Engineering.

PURPOSE: To utilize a particle engineering strategy to improve the manufacturability of a cohesive and poorly compactable API at high drug loading for direct compression of mini-tablets. METHODS: A high-shear mixer was used for wet milling during the API manufacturing process to obtain target particle size distributions. The targeted particles were characterized and formulated into blends by mixing with excipients. The formulated blends were compressed directly into mini-tablets using a compaction simulator. The tablet hardness, weight variation, and friability of the mini-tablets were characterized and compared with mini-tablets prepared with hammer milled APIs. RESULTS: Compared to the hammer milled APIs, the wet milled APIs, had smoother surface, narrower particle size distributions and demonstrated a better flow properties. Moreover, the mini-tablets produced with the wet milled APIs exhibited better weight uniformity, robust tablet mechanical strength and ultimately better friability. In addition, unlike the hammer milled process, the wet milling process is controllable and easy to scale up. CONCLUSIONS: This study successfully implemented API particle engineering through a high shear wet milling process to produce particles suitable for robust drug product manufacturing.

Investigating particle-size-induced changes in composition, physical, rheological, and bioactive properties of black tea powder.

BACKGROUND: People brew tea to drink an infusion that only contains 25% water-soluble constituents, leading to most of the insoluble materials being wasted. Tea powder could be drunk directly by mixing with water without producing any waste. Tea powder can also be used as a natural additive to improve the flavour and taste in beverages and foods. Much detailed information on the particle properties of tea powder is required with its increasing consumption. The aim of this study was to investigate the effects of particle size ranging from median diameter D50  = 4.32 to 26.59 µm on the composition, physical, rheological, and bioactive properties of black tea powder. RESULTS: The results indicate that large powder sizes had high bulk density and flowability, whereas small powder sizes possessed good swelling ability and wettability. The contents of water extract, total polyphenols, crude fibre, catechins, and thearubigins reduced with a decrease in particle size. To change the particle size and concentration could adjust the elastic modulus and the viscous modulus of the black tea powder suspension. Moreover, black tea powder with small particle size could regulate blood lipids in a hyperlipidaemic rat model by lowering triacylglycerols and elevating high-density lipoprotein cholesterol, whereas large particles presented an advantage in reducing body weight. CONCLUSION: Our investigation extended the knowledge of commercial black tea powder in composition, physical, rheological, and bioactive properties. These results lay the foundation for future exploration of the use of tea powder in the food industry. © 2022 Society of Chemical Industry.

Puerarin-Na Chelate Hydrate Simultaneously Improves Dissolution and Mechanical Behavior.

Puerarin monohydrate (PUEM), as the commercial solid form of the natural anti-hypertension drug puerarin (PUE), has low solubility, poor flowability, and mechanical properties. In this study, a novel solid form as PUE-Na chelate hydrate was prepared by a reactive crystallization method. Crystal structure analysis demonstrated that PUE-Na contains PUE-, Na+, and water in a molar ratio of 1:1:7. It crystallizes in the monoclinic space group P21, and Na+ is linked with PUE- and four water molecules through Na+ ← O coordination bonds. Another three crystal water molecules occupy channels along the crystallographic b-axis. Observing along the b-axis, the crystal structure features a distinct tubular helix and a DNA-like twisted helix. The complexation between Na+ and PUE- in aqueous solution was confirmed by the Na+ selective electrode, indicating that PUE-Na chelate hydrate belongs to a type of chelate rather than organic metal salt. Compared with PUEM, PUE-Na exhibited a superior dissolution rate (i.e., ∼38-fold increase in water) owing to its lower solvation free energy and clear-enriched exposed polar groups. Moreover, PUE-Na enhanced the tabletability and flowability of PUEM, attributing to its better elastoplastic deformation and lower-friction crystal habit. The unique PUE-Na chelate hydrate with significantly enhanced pharmaceutical properties is a very promising candidate for future product development of PUE.

The Influence of Relative Humidity and Storage Conditions on the Physico-chemical Properties of Inhalation Grade Fine Lactose.

Dry powder inhalers (DPIs) are favorable devices for the delivery of dry formulations to the lungs; still, they largely fail to deliver higher doses of active pharmaceutical ingredient (API) to the lower airways. Addition of fine particles of excipient (fines) to the blend of API and carrier was shown to improve aerosolization performance. Lactose monohydrate is ubiquitous excipient used for this purpose. Lactose exists in a thermodynamically stable crystalline form; however, processes like milling, sieving, or even mixing may induce alteration of crystalline structure and introduce amorphous domains, which could further affect the physico-chemical properties of the material. Therefore, the aim of this work is a detailed characterization of two commercially available types of inhalation grade fine lactose powders (Inhalac 400 and Inhalac 500) prepared using different air-jet milling parameters, with a focus on impact of storage conditions on material properties. We found that the different milling parameters resulted in variable particle size distribution (PSD), and thus surface areas, variable initial amorphous content, cohesivity, flowability, and moisture sorption of materials. In addition, exposure of fine powders to higher humidity reduced the amorphous content present in the materials, but also affected agglomeration tendency and dispersion behavior of both powders. We believe the obtained findings to be important for the aerosolization performance of carrier-based DPIs containing fines and thus need to be duly considered during formulation development.

Development of yoghurt powder using microwave-assisted foam-mat drying.

Yoghurt powder is widely used in industries of confectionery and baking. The production of yoghurt powder can be made by several drying methods, including freeze, spray, microwave vacuum, convective and foam-mat. In this study, the effect of varying concentrations of egg albumin (EA) on foam and powder characteristics of yoghurt were determined. Besides, microwave-assisted foam-mat drying of yoghurt was carried out to examine the effects of three microwave output powers (100, 180 and 300 W) on powder properties of yoghurt. Increased in EA concentration resulted in an increase in foam expansion and decrease in foam density. Higher foam stability (after 120 min.) was observed for foams containing 10 and 15% EA (both found as 88.24%). As powder properties, wettability and solubility times were significantly decreased with the addition of EA, while water holding capacity was increased. Change in EA concentration was significantly (p ≤ 0.05) effective on all powder properties dried at 100 W. Carr Index and Hausner Ratio values were in the range of 0.99-13.89 and 1.01-1.17, respectively. Microwave powers were significantly (p ≤ 0.05) effective on the flowability of powders containing 0, 5 and 10% EA. Yoghurt powders showed mostly excellent flow characteristics (for all concentrations of EA and microwave output powers).

The combined effects of different fat replacers and rennet casein on the properties of reduced-fat processed cheese.

Reduced-fat food products can help to prevent obesity and other diet-related diseases. However, the removal of fat often impairs the sensory and textural properties of foods, leading to low consumer acceptance. In this study, we tested various concentrations of fat replacers (inulin, corn dextrin, polydextrose, and microparticulated whey protein) combined with rennet casein to investigate their effects on the melting behavior, dynamic rheological properties, and hardness of reduced-fat processed cheese. We found that increasing concentrations of inulin and corn dextrin reduced the flowability of cheese in the melting test and can thus be used to inhibit flow during heating. Microparticulated whey protein did not affect flowability but caused an increase in the storage and loss moduli as well as the temperature at gel-sol transition. A similar effect was also shown for rennet casein, whereas inulin and polydextrose had little or no effect on these rheological parameters. Corn dextrin had no effect on the storage and loss moduli, but affected the gel-sol transition temperature. No changes in hardness were detected for any concentration of the fat replacers, but increasing the rennet casein content also increased the hardness of the samples, regardless of the fat replacer used. Our results indicate the different concentrations and combinations of fat replacers and rennet casein that can be included in reduced-fat processed cheese to develop products with specific rheological properties, thus meeting future demand for reduced-fat products with attractive sensory attributes.

Evaluation of Weight Variation in Mini-Tablets Manufactured by a Multiple-Tip Tool.

Recently, owing to their pharmaceutical and clinical utility, mini-tablets have been well studied by researchers. Mini-tablets are usually manufactured by compression molding using a multiple-tip tool in a rotary tableting machine. Owing to their special structure, ensuring uniformity is a very important challenge in the manufacturability of mini-tablets using the multiple-tip tool. In this study, we aimed to evaluate the weight variation in mini-tablets produced by a multiple-tip tool, which is considered to be the root cause affecting the uniformity, and to investigate the physical properties of drug granules and tableting conditions in a rotary tableting machine that could reduce this weight variation. In addition, the relationship between these factors and response was visualized using response surface analysis. It was shown that the weight variation in mini-tablets produced by a multiple-tip tool was reduced when using a forced feeder compared with an open feeder. Furthermore, in the case of an open feeder, the optimal range of the average particle size diameter of drug granules and the rotational speed of the rotating disc in the rotary tableting machine were determined from response surface analysis. It was suggested that it is possible to reduce the weight variation in the mini-tablets by selecting drug granules with an average particle size diameter of 100-150 µm and using tableting conditions with a rotational speed of 40-60 rpm. This study elucidated the factors that affect uniformity and determined their optimal range for the manufacture of mini-tablets.

Preparation and optimization of multi-functional directly compressible excipient: an integrated approach of principal component analysis and design of experiments.

Developing a new excipient and obtaining its market approval is an expensive, time-consuming, and complex process. The application of a multivariate analytical approach - principal component analysis (PCA) - in combination with the design of experiments (DoE) approach can make the process of developing co-processed excipient cost-effective and rapid. The present investigation was aimed to demonstrate the applicability of the DoE approach and PCA in developing a co-processed excipient by using the spray drying technique. The preliminary studies suggested a significant effect of inlet air temperature (X 1) and polymer ratio [chitosan chlorhydrate (CC): mannitol - X 2) on critical product characteristics so they were selected as independent variables in 32 full factorial design. The result of regression analysis suggested a significant effect of both independent variables on all response variables. The PCA of practically obtained value suggested a strong effect of all the selected response variables on the model. The prepared co-processed excipient had better tableting properties compared to the physical mixture of excipients and was able to accommodate more than 80% drug without compromising the flow property and compressibility. The present investigation successfully proved the applicability PCA and DoE approach as an effective and rapid tool for optimizing process parameters and formulation composition for preparing a directly compressible co-processed excipient.

Designing high-performance colour cosmetics through optimization of powder flow characteristics.

OBJECTIVE: Explore the impact of powder flow properties such as flow energy and compressibility on the performance characteristics of foundation powders such as cake strength and pay-off. METHODS: FT4 Powder Rheometer from Freeman Technology was utilized to explore various powder compositions. The three major tests performed were flowability test, compressibility test and shear cell test. RESULTS: The results highlight that the sample which has higher compressibility has the better cake strength, and the sample which requires lower total energy has better pay-off. Particles or samples with lower total flow energy, should have easier flow, therefore, should have better pay-off. Samples and components with higher compressibility, should hold the structure better, therefore, should have better cake strength. Talc has the highest compressibility and lowest flow energy. Foundation sample 5 has the highest concentration of talc and also has the best performance. CONCLUSION: The lower the total flow energy, the easier it is for the powder to flow, and have better pay-off. Powder compressibility correlates with cake strength which means that a sample with better compressibility consequently has the better cake strength. Samples 5 and 10 require less total flow energy, have lower shear stress, and higher compressibility, therefore, have better final performance. Both samples 5 and 10 have higher talc concentrations compared to other formulations.

OBJECTIF: Explorer l'impact des propriétés d'écoulement des poudres, comme l'énergie d'écoulement et la compressibilité, sur les caractéristiques de performance des fond de teint en poudres comme la quantité de poudre prélevée (rendement) et la résistance au choc. MÉTHODÉS: Le rhéomètre à poudre FT4 de Freeman Technology a été utilisé pour explorer différentes compositions de poudre. Les trois principaux tests effectués étaient le test de fluidité, le test de compressibilité et le test des cellules de cisaillement. RÉSULTATS: Les résultats mettent en évidence que l'échantillon qui a une compressibilité plus élevée a la meilleure résistance au choc, et l'échantillon qui nécessite une énergie totale inférieure aura un meilleur rendement. Les particules ou les échantillons avec une énergie de flux totale inférieure, devraient avoir un écoulement plus facile, par conséquent, devraient avoir un meilleur rendement. Les échantillons et les composants avec une compressibilité plus élevée devraient mieux maintenir leur structure, par conséquent, devraient avoir une meilleure résistance au choc. Le talc a la compressibilité la plus élevée et l'énergie d'écoulement la plus faible. Le fond de teint 5 a la plus forte concentration en talc et présente également les meilleures performances. CONCLUSION: Plus l'énergie d'écoulement totale est faible, plus la poudre pourra s'écouler et aura un meilleur rendement. La compressibilité de la poudre est corrélée à la résistance au choc, ce qui signifie qu'un échantillon avec une meilleure compressibilité a par conséquent la meilleure résistance au choc. Les échantillons 5 et 10 nécessitent moins d'énergie d'écoulement totale, ont une contrainte de cisaillement plus faible et une compressibilité plus élevée, donc de meilleures performances finales. Les échantillons 5 et 10 ont des concentrations de talc plus élevées que les autres formulations.

The Fundamental and Functional Property Differences Between HPMC and PVP Co-Processed Herbal Particles Prepared by Fluid Bed Coating.

Core-shell composite particles (CPs) are the most preferred choice for direct compaction (DC), but their application in herbal tablets is limited. Hydroxypropyl methylcellulose (HPMC) and polyvinylpyrrolidone (PVP) are usually employed as the shell materials, but there are few, if any, researches exploring the different effects of HPMC and PVP on the properties of herbal CPs. In this study, the CPs containing HPMC (CP X-H) and CPs containing PVP (CP X-P) were prepared based on herbal powders (X). Their physical properties were characterized comprehensively. The differences in properties between CP X-H and CP X-P were explored, and their mechanism analysis was also performed profoundly. The results demonstrated that (i) CP X-H and CP X-P exhibited similar flowability; (ii) CP X-H generally exhibited better compactibility, larger particle size, and more uniform particle size distribution, and lower bulk density, tap density, and hygroscopicity than CP X-P; (iii) compared with the tablets produced with CP X-P, ones with CP X-H exhibited similar weight variation (%), lower friability, and longer disintegration time. The mechanism analysis manifested that the differences in physical properties between HPMC and PVP were the important and fundamental factors, which led to the differences in structure and surface morphology of particles, and in fundamental properties of CPs. These findings are beneficial to the development of herbal core-shell CPs for DC.

High-Molecular-Weight Hypromellose from Three Different Suppliers: Effects of Compression Speed, Tableting Equipment, and Moisture on the Compaction.

Use of higher tableting speeds is gaining increasing importance for pharmaceutical industry. There is a profound lack of new studies of mechanical properties of hypromellose, and none of them evaluate different suppliers. Thus, the objective of this study was to investigate flow and compaction properties of different grades of hypromellose (type 2208) from three different suppliers, with particular focus on the effect of the compression speed. The flow properties were determined using flow time, shear cell, Carr index, and constant B from initial part of Heckel profile. Compaction properties were quantified using "out-of-die" Heckel, Walker, and Kuentz-Leuenberger models; two tensile strength profiles (tabletability and compactibility); and elastic recovery. Compaction was performed by both an instrumented single-punch press and a high-speed rotary press simulator. Due to larger, rounder, and smoother particles, both Methocel™ DC grades together with Benecel™ K4M showed better flow properties compared with other materials, with Metolose® K100M having the worst flow. Overall, Benecel™ K100M and Metolose® K100M showed the best compaction properties, closely followed by Metolose® K4M. Heckel analysis showed the highest compressibility of Benecel™ K100M, followed by both Methocel™ DC grades. Kuentz-Leuenberger model showed to have no practical superiority in comparison with Heckel model in the compression pressure range used. Results of strain rate sensitivity showed that Methocel™ K4M DC was the least susceptible to change of tableting speed, followed by Methocel™ K100M DC and both grades of Benecel™, and in contrast, both grades of Metolose® were the most sensitive. Effect of moisture on compaction was also studied.

Exploring the influence of particle shape and air velocity on the flowability in the respiratory tract: a computational fluid dynamics approach.

Dry powder inhalers (DPIs) are considered a main drug delivery system through pulmonary route. The main objective of this work is to study the flow of differently shaped microparticles in order to find the optimum shape of drug particles that will demonstrate the best flow to the deep lung. The flowability of particles in air or any fluid depends particularly on the drag force which is defined as the resistance of the fluid molecules to the particle flow. One of the most important parameters that affect the drag force is the particles' shape. Computational simulations using COMSOL Multi Physics 5.2 software were performed for investigating the particles flow in the air pathways of lung, and the drag force was calculated for different particles shapes. This was accomplished by screening a set of 17 possible shapes that are expected to be synthesized easily in the micro-scale. In addition, the macro-scale behavior of the investigated shapes was also simulated so as to compare the behavior of the flowing particles in both cases. A very big difference was found between the behavior of particles' flow in the micro and macro scales, but a similar behavior can be obtained if the flow velocity of the microparticles is very high. It was also found that the micro-triangle with aspect ratio 2:1 has the least drag force in both deep and upper lung; so, it should be the shape of choice during the process of particle synthesis for pulmonary drug delivery.

Waste resources recycling in controlled low-strength material (CLSM): A critical review on plastic properties.

The exponential growth of waste generation is posing serious environmental issues and thus requires urgent management and recycling action to achieve green sustainable development. Controlled low-strength material (CLSM) is a highly flowable cementitious backfill material with self-consolidating properties. The CLSM efficiency during construction and final performance at the site depends on its plastic properties. Plastic properties are responsible for workability, pumpability, stability, and lateral pressure on adjacent soils. This paper presents a critical review to date on the use of waste materials and/or by-products and their impacts on the plastic properties of the CLSM. Extensive previous studies demonstrated that the basic properties and content of waste materials as well as the amount of water in the mix design, play a dominant role in determining the plastic properties of CLSM. The discussed plastic properties of CLSM include flowability, bleeding, segregation, and hardening time, which are found to be inter-related. Proper mix design adjustment to accommodate the use of waste materials is possible to produce sustainable CLSM with acceptable plastic properties. Additionally, the discussion and analysis presented in this paper could provide a basis for future research advances and the development of sustainable CLSM prepared with waste materials.