Powder flowability and density ratios: the impact of granules packing

The empty world - a view from the free volume concept and Eyring's rate process theory

The many-body problem is a common issue, irrespective of the scale of entities under consideration. From electrons to atoms, small molecules like simple inorganic or organic structures, large molecules like proteins or polymers, nanometer- or micrometer-sized particles, granular matter, and even galaxies, the precise determination or estimation of geometrical locations and momentum energy of individual entities, and interaction forces between these millions of entities, is impossible but unfortunately important for understanding the collective physical properties like mechanical and electrical characteristics of the whole system. Despite foreseeable difficulties and complexities, attempts to estimate "interparticle" forces have never stopped using traditional Newtonian models, quantum mechanical approaches, and density functional theory. In this review, a simple approach integrating the free volume and Eyring's rate process theory is summarized and its application across a wide range of scales from electrons to the universe is presented in a unified manner. The focus is on comparisons between theoretical predictions and experimental results.

Influence of weevil on the physicochemical characteristics, functional properties, and nutritional value of rice (Oryza sativa L.) produced at Yagoua (far-north Cameroon)

The infestation of rice by pests during the post-harvest phase is one of the consequences of the deterioration of its technological and nutritional quality. Therefore, the present study was carried out to determine the physico-chemical characteristics, functional properties and nutritional value of uninfested and weevil-infested rice during storage. To this end, rice samples were collected from a rice production unit in the Far North Region of Cameroon. The physico-chemical and functional properties of uninfested and infested rice flours were determined using standard methods. The results showed that among the functional properties, only porosity showed a significant difference (p˂0.05) between infested (13.88 %) and uninfested (17.30 %) rice flours. Concerning the proximate composition, except for the carbohydrate content, where a significant decrease (p˂0.05) was observed between infested (68.15 %) and non-infested (58.43 %) rice flours, no significant difference (p > 0.05) was observed for the other nutrients evaluated. It was also observed that weevil infestation had a significant (p < 0.05) effect on the mineral content of the rice samples. Furthermore, scanning electron microscopy analysis revealed the presence of smaller granules with imprecise shapes in non-infested rice flour. Thus, this study showed that weevil infestation had a significant negative impact on the nutritional quality of rice and that good practices must be adopted by producers to ensure the quality of rice grains during storage.

Enhancing Quality Control: Image-Based Quantification of Carbides and Defect Remediation in Binder Jetting Additive Manufacturing

While binder jetting (BJ) additive manufacturing (AM) holds considerable promise for industrial applications, defects often compromise part quality. This study addresses these challenges by investigating binding mechanisms and analyzing common defects, proposing tailored solutions to mitigate them. Emphasizing defect identification for effective quality control in BJ-AM, this research offers strategies for in-process rectification and post-process evaluation to elevate part quality. It shows how to successfully process metallic parts with complex geometries while maintaining consistent material properties. Furthermore, the paper explores the microstructure of AISI M2 tool steel, utilizing advanced image processing techniques like digital image analysis and SEM images to evaluate carbide distribution. The results show that M2 tool steel has a high proportion of M6C carbides, with furnace-cooled samples ranging from ~2.4% to 7.1% and MC carbides from ~0.4% to 9.4%. M6C carbides ranged from ~2.6% to 3.8% in air-cooled samples, while water-cooled samples peaked at ~8.52%. Sintering conditions also affected shrinkage, with furnace-cooled samples showing the lowest rates (1.7 ± 0.4% to 5 ± 0.4%) and water-cooled samples showing the highest (2 ± 0.4% to 14.1 ± 0.4%). The study recommends real-time defect detection systems with autonomous corrective capabilities to improve the quality and performance of BJ-AM components.

Modulation of Physical and Thermal Properties in Wild Banana (Musa balbisiana Colla) Seed Powder by Moisture Variations

Engineering and flow properties of banana seed powder as a function of moisture content are important for processing, handling, packaging, and transport processes. The bulk density, tapped density, and porosity increased from 377.37 to 427.36 kg m-3, 622.08 to 746.33 kg m-3, and 38.99-43.74%, respectively, within the increasing moisture content range. The Hausner ratio (Hr) and Carr's compressibility index (CI) significantly (p < 0.05) increased with an increase in moisture content (6.16-19.56% db) of banana seed powder, whereas HR fell in the range of 1.4-2.0, indicating cohesive characteristics of banana seed powder. The angle of repose, angle of spatula, and angle of fall exhibited a linear increase, ranging from 40.6° to 49°, 33.4° to 39.4°, and 35.6° to 42.6°, respectively, with increasing moisture content. The static coefficient of friction was found to be highest for aluminium and glass surfaces and least for stainless steel. The water activity and swelling power of banana seed powder showed a significant increase, while the solubility and oil absorption capacity exhibited a significant decrease within the range of increasing moisture content. The thermal characteristics of wild banana seed powder, such as thermal conductivity (0.16 to 0.20 Wm-1 K-1) and volumetric specific heat (0.58 to 0.99 MJm-3 K-1), demonstrated an increasing trend as the moisture content increased. However, the thermal diffusivity showed a decrease from 0.31 to 0.19 (×10-6 m2s-1) with the increase in moisture content.

A concise summary of powder processing methodologies for flow enhancement

The knowledge of powder properties has been highlighted since the 19th century since most formulations focus on solid dosage forms, and powder flow is essential for various manufacturing operations. A poor powder flow may generate problems in the manufacturing processes and cause the plant's malfunction. Hence these problems should be studied and rectified beforehand by various powder flow techniques to improve and enhance powder flowability. The powder's physical properties can be determined using compendial and non-compendial methods. The non-compendial practices generally describe the powder response under the stress and shear experienced during their processing. The primary interest of the current report is to summarize the flow problems and enlist the techniques to eliminate the issues associated with the powder's flow properties, thereby increasing plant output and minimizing the production process inconvenience with excellent efficiency. In this review, we discuss powder flow and its measurement techniques and mainly focus on various approaches to improve the cohesive powder flow property.

Ultraslow Settling Kinetics of Frictional Cohesive Powders

Using discrete element method simulations, we show that the settling of frictional cohesive grains under ramped-pressure compression exhibits strong history dependence and slow dynamics that are not present for grains that lack either cohesion or friction. Systems prepared by beginning with a dilute state and then ramping the pressure to a small positive value P_{final} over a time τ_{ramp} settle at packing fractions given by an inverse-logarithmic rate law, ϕ_{settled}(τ_{ramp})=ϕ_{settled}(∞)+A/[1+Bln(1+τ_{ramp}/τ_{slow})]. This law is analogous to the one obtained from classical tapping experiments on noncohesive grains, but crucially different in that τ_{slow} is set by the slow dynamics of structural void stabilization rather than the faster dynamics of bulk densification. We formulate a kinetic free-void-volume theory that predicts this ϕ_{settled}(τ_{ramp}), with ϕ_{settled}(∞)=ϕ_{ALP} and A=ϕ_{settled}(0)-ϕ_{ALP}, where ϕ_{ALP}≡.135 is the "adhesive loose packing" fraction found by Liu et al. [Equation of state for random sphere packings with arbitrary adhesion and friction, Soft Matter 13, 421 (2017)SMOABF1744-683X10.1039/C6SM02216B].

Morphological distribution mapping: Utilisation of modelling to integrate particle size and shape distributions

The aim of this work was to develop approaches to utilize whole particle distributions for both particle size and particle shape parameters to map the full range of particle properties in a curated dataset. It is hoped that such an approach may enable a more complete understanding of the particle landscape as a step towards improving the link between particle properties and processing behaviour. A 1-dimensional principal component analysis (PCA) approach was applied to create a 'morphological distribution landscape'. A dataset of imaged APIs, intermediates and excipients encompassing particle size, particle shape (elongation, length and width) and distribution shape was curated between 2008 and 2022. The curated dataset encompassed over 200 different materials, which included over 150 different APIs, and approximately 3500 unique samples. For the purposes of the current work, only API samples were included. The morphological landscape enables differentiation of materials of equivalent size but varying shape and vice versa. It is hoped that this type of approach can be utilised to better understand the influence of particle properties on pharmaceutical processing behaviour and thereby enable scientists to leverage historical knowledge to highlight and mitigate risks associated to materials of similar morphological nature.

Developing a Virtual Flowability Sensor for Monitoring a Pharmaceutical Dry Granulation Line

Current technologies to measure granule flowability involve at-line methods that can take hours to perform. This is problematic for a continuous dry granulation tableting line, where the quality assurance and control of the final tablet products depend on real-time monitoring and control of powder flowability. Hence, a real-time alternative is needed for measuring the flowability of the granular products coming out of the roller compactor, which is the unit operation immediately preceding the tablet press. Since particle analyzers have the potential to take inline measurements of the size and shape of granules, they can potentially serve as real-time flowability sensors, given that the size and shape measurements can be used to reliably predict flowability measurements. This paper reports on the use of Partial Least Squares (PLS) regression to utilize distributions of size and shape measurements in predicting the output of three different types of flowability measurements: rotary drum flow, orifice flow, and tapped density analysis. The prediction performance of PLS had a coefficient of determination ranging from 0.80 to 0.97, which is the best reported performance in the literature. This is attributed to the ability of PLS to handle high collinearity in the datasets and the inclusion of multiple shape characteristics-eccentricity, form factor, and elliptical form factor-into the model. The latter calls for a change in industry perspective, which normally dismisses the importance of shape in favor of size; and the former suggests the use of PLS as a better way to reduce the dimensionality of distribution datasets, instead of the widely used practice of pre-selecting distribution percentiles.

A Ternary Model for Particle Packing Optimization

Powder packing in metal powders is an important aspect of additive manufacturing (otherwise known as 3-D printing), as it directly impacts the physical and mechanical properties of materials. Improving the packing density of powder directly impacts the microstructure of the finished 3D-printed part and ultimately enhances the surface finish. To obtain the most efficient packing of a given powder, different powder blends of that material must be mixed to minimize the number of voids, irrespective of the irregularities in the particle morphology and flowability, thereby increasing the density of the powder. To achieve this, a methodology for mixing powder must be developed, for each powder type, to obtain the maximum packing density. This paper presents a model that adequately predicts the volumetric fraction of the powder grades necessary for obtaining the maximum packing density for a given powder sample. The model factors in the disparity between theoretical assumptions and the experimental outcome by introducing a volume reduction factor. We outline the model development steps in this paper, testing it with a real-world powder system.

Manufacturing and Assessing the New Orally Disintegrating Tablets, Containing Nimodipine-hydroxypropyl-β-cyclodextrin and Nimodipine-methyl-β-cyclodextrin Inclusion Complexes

The aim of the present study was to manufacture new orally disintegrating tablets containing nimodipine-hydroxypropyl-β-cyclodextrin and nimodipine-methyl-β-cyclodextrin inclusion complexes. For obtaining a better quality of the manufactured tablets, three methods of the preparation of inclusion complexes, in a 1:1 molar ratio, were used comparatively; namely, a solid-state kneading method and two liquid state coprecipitation and lyophilization techniques. The physical and chemical properties of the obtained inclusion complexes, as well as their physical mixtures, were investigated using Fourier transformed infrared spectroscopy, scanning electron microscopy, X-ray diffraction analyses, and differential scanning calorimetry. The results showed that the lyophilization method can be successfully used for a better complexation. Finally, the formulation and precompression studies for tablets for oral dispersion, containing Nim-HP-β-CD and Nim-Me-β-CD inclusion complexes, were successfully assessed.

Volumetrics of Hydrogen Storage by Physical Adsorption

Physical adsorption remains a promising method for achieving fast, reversible hydrogen storage at both ambient and cryogenic conditions. Research in this area has recently shifted to focus primarily on the volumetric (H2 stored/delivered per volume) gains achieved within an adsorptive storage system over that of pure H2 compression; however, the methodology for estimating a volumetric stored or delivered amount requires several assumptions related to the ultimate packing of the adsorbent material into an actual storage system volume. In this work, we critically review the different assumptions commonly employed, and thereby categorize and compare the volumetric storage and delivery across numerous different porous materials including benchmark metal-organic frameworks, porous carbons, and zeolites. In several cases, there is a significant gain in both storage and delivery by the addition of an adsorbent to the high-pressure H2 storage system over that of pure compression, even at room temperature. Lightweight, low-density materials remain the optimal adsorbents at low temperature, while higher density, open metal-containing frameworks are necessary for high-density room temperature storage and delivery.

Spray-Congealing and Wet-Sieving as Alternative Processes for Engineering of Inhalation Carrier Particles: Comparison of Surface Properties, Blending and In Vitro Performance

PURPOSE

Traditionally, α-lactose monohydrate is the carrier of choice in dry powder inhaler (DPI) formulations. Nonetheless, other sugars, such as D-mannitol, have emerged as potential alternatives. Herein, we explored different particle engineering processes to produce D-mannitol carriers for inhaled delivery.

METHODS

Wet-sieving and spray-congealing were employed as innovative techniques to evaluate the impact of engineering on the particle properties of D-mannitol. To that end, the resulting powders were characterized concerning their solid-state, micromeritics and flowability. Afterwards, the engineered carrier particles were blended with inhalable size beclomethasone dipropionate to form low dose (1 wt%) DPI formulations. The in vitro aerosolization performance was evaluated using the NEXThaler®, a reservoir multi-dose device.

RESULTS

Wet-sieving generated D-mannitol particles with a narrow particle size distribution and spray-congealing free-flowing spherical particles. The more uniform pumice particles with deep voids and clefts of wet-sieved D-mannitol (Pearl300_WS) were beneficial to drug aerosolization, only when used in combination with a ternary agent (10 wt% of 'Preblend'). When compared to the starting material, the spray-congealed D-mannitol has shown to be promising in terms of the relative increase of the fine particle fraction of the drug (around 100%), when used without the addition of ternary agents.

CONCLUSIONS

The wet-sieving process and the related aerosolization performance are strongly dependent on the topography and structure of the starting material. Spray-congealing, has shown to be a potential process for generating smooth spherical particles of D-mannitol that enhance the in vitro aerosolization performance in binary blends of the carrier with a low drug dose.

Powder flow from an intermediate bulk container - Discharge predictions and experimental evaluation

Powders are usually dispensed, blended, and transferred between different manufacturing steps in so-called Intermediate Bulk Containers (IBCs), and discharge from an IBC plays a critical role in the ability to manufacture high-quality tablets. To better understand IBC discharge, the flow behavior of selected excipients was comprehensively characterized using a number of techniques including the Hausner ratio/Carr's index, Erweka flow test, FlowPro flow test, shear test and wall friction test as well as FT4 powder rheometer experiments. Jenike's hopper design methodology was then used to predict the minimum non-arching outlet diameter and the mode of flow. Furthermore, the discharge rate from an IBC was predicted using a simple model that takes into account gravity and aerodynamic drag. The predictions were experimentally verified by measuring the discharge rate from a 20 L IBC using five commonly-used excipients. The small-scale Erweka flow test provided the best prediction of the full-scale IBC discharge experiment. Furthermore, a simple model that relied only on the particle size of the material and the diameter of the discharge opening was found to predict the IBC discharge rate remarkably well.

Insight to hydrophobic SiO2 encapsulated SiO2 gel: Preparation and application in fire extinguishing

Micron-sized hydrophobic SiO₂ encapsulated SiO₂ gel (HSESG) was prepared successfully by using SiO₂ gel as the solid core and hydrophobic nano-SiO₂ particle as the shell under high-speed shear stirring. The flowability, stability, particle size distribution, bulk density and water repellency of the powder were measured separately, and it was concluded that this type of product can exhibit smaller static angle, larger flow rate and lower bulk density. After the formation of a stable spatial network of SiO₂ gel in its interior, relevant fire extinguishing experiments were carried out and HSESG exhibits higher efficiency in suppressing wood stack fires than that of ordinary dry water (DW) and ABC dry powder. As a high-efficiency fire-extinguishing material, it also exhibits excellent environmental friendliness and non-toxicity, which will make it have the potential to develop a new application market.

Material Reuse in Laser Powder Bed Fusion: Side Effects of the Laser—Metal Powder Interaction

Metal additive manufacturing is changing the way in which engineers and designers model the production of three-dimensional (3D) objects, with rapid growth seen in recent years. Laser powder bed fusion (LPBF) is the most used metal additive manufacturing technique, and it is based on the efficient interaction between a high-energy laser and a metal powder feedstock. To make LPBF more cost-efficient and environmentally friendly, it is of paramount importance to recycle (reuse) the unfused powder from a build job. However, since the laser–powder interaction involves complex physics phenomena and generates by-products which might affect the integrity of the feedstock and the final build part, a better understanding of the overall process should be attained. The present review paper is focused on the clarification of the interaction between laser and metal powder, with a strong focus on its side effects.

Neural Image Analysis and Electron Microscopy to Detect and Describe Selected Quality Factors of Fruit and Vegetable Spray-Dried Powders-Case Study: Chokeberry Powder

The study concentrates on researching possibilities of using computer image analysis and neural modeling in order to assess selected quality discriminants of spray-dried chokeberry powder. The aim of the paper is the quality identification of chokeberry powders on account of their highest dying power, the highest bioactivity, as well as technologically satisfying looseness of the powder. The article presents neural models with vision techniques backed up by devices such as digital cameras, as well as an electron microscope. The reduction in size of input variables with PCA has an influence on improving the processes of learning data sets, thus increasing the effectiveness of identifying chokeberry fruit powders included in digital pictures, which is shown in the results of the conducted research. The effectiveness of image recognition is presented by classifying abilities, as well as low Root Mean Square Error (RMSE), for which the best results are achieved with a typology of network type Multi-Layer Perceptron (MLP). The selected networks type MLP are characterized by the highest degree of classification at 0.99 and RMSE at 0.11 at most at the same time.

Use of seed gums from Tamarindus indica and Cassia fistula as controlled-release agents

Most seed gums have been widely used in oral and topical pharmaceutical formulations, cosmetics, and food products because of their hydrophilic properties. Gums from Tamariudus indica and Cassia fistula seeds were chemically modified by carboxymethylation to improve their functionalities. The objective of the present study was to characterize  and evaluate crude and carboxymethylated gums from T. indica and C. fistula seeds to achieve the controlled-release of diclofenac sodium (DS) in matrix tablet form. Both crude and carboxymethylated gums were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. The results revealed that the gums were successfully modified by carboxymethylation and that the modified gums were amorphous in structure and had better flow properties. The carboxymethylated gums from both plant seeds did not exhibit cytotoxicity at concentrations lower than 0.5 mg/ml. All gum samples used as polymeric controlled-release agents were formulated into DS matrix tablets. Hardness and thickness tests were conducted as in-process tests. Drug content estimation and in vitro drug release studies were carried out to evaluate the matrix tablets. Increasing the concentration of gums increased compression time and hardness while it reduced the thickness. Furthermore, the results fitted well with the Korsmeyer–Peppas model. Moreover, the DS tablets were found to release the drug by super case II transport (relaxation).  In summary, the carboxymethylated gum from T. indica and C. fistula seeds is an excellent, naturally sourced gum with high physicochemical and functional qualities, and can potentially be used in pharmaceutical applications as a disintegrant, diluent, and drug release-controlling agent.