Storage Of Powders Research Articles

Microbial and chemical stability of Acheta domesticus powder during one year storage period at room temperature

The sustainability of food systems is of growing concern worldwide, so insects are a growing source of animal proteins for food and feed. Among insect species, the house cricket, Acheta domesticus, is a promising option from a sustainability point of view. This study aimed at evaluating both microbiological and chemical stability of A. domesticus powders during one year of storage at room temperature. Our study was conducted on cricket powders obtained by three different processes: drying at 80°C (P80), drying at 120°C (P120), and lyophilization (PL). Regarding microbiological profile, the pathogens Listeria monocytogenes and Salmonella were not detected, while total viable count and lactic acid bacteria tended to decrease during the storage period. Bacillus cereus was detected at low counts during the entire storage period, but only one replicate of P80 exceeded the limit set for A. domesticus by the European Commission Implementing Regulation 2017/2470. The measured protein contents of the cricket powders immediately after production ranged between 60.6 and 64.3%. The peroxide values were far higher than the limit established by the EU Regulation in all samples. Higher amounts of hexanal and pentanal were detected in P80 and P120 than in PL, indicating that oven drying could enhance lipid oxidation. In conclusion, a one year shelf-life can suitably be ascribed to the analyzed cricket powders from a microbiological point of view, but lacked chemical stability and had a clear early tendency toward rancidity. The samples dried at 120°C and lyophilized never exceeded the limit set by European Commission for B. cereus count in A. domesticus powder. In addition, lyophilized samples showed the lowest values of hexanal and pentanal, the aldehydes that are primarily responsible for the rancid smell. The oxidative status of the final products could be strongly influenced by the powder processing, so for this reason, edible insect species-specific post-rearing protocols should be implemented. These results open an interesting scenario for a long period of storage of insect powder in the absence of a cold chain, making the insect market an increasingly sustainable sector.

ИЗУЧЕНИЕ ПРОЦЕССОВ АГРЕГИРОВАНИЯ И ДЕЗАГРЕГИРОВАНИЯ ЧАСТИЦ ВЫСОКОДИСПЕРСНОГО ПОРОШКА ЦИРКОНИЯ

During long-term storage of wet fine zirconium metal powder under certain conditions the process of particles aggregation may start, which leads to powder transformation into a solid lumpy material, which significantly limits its application range. The purpose of this work was to establish the probable causes leading to the aggregation of zirconium powder particles during long-term storage, and to assess the possibility of transferring the lumpy material to its initial powdery state while preserving its basic physical and chemical properties. Particles aggregation most likely happens due to participation of zirconium atoms of the metal layers in formation of oxo-bridging bonds in acidic medium. Lumpy material formed in the process of storage of sodium-thermal zirconium metal powder (PZrN-A) was used as an example for testing the method of particles disaggregation by means of sodium hydroxide solution treatment, which makes it possible to transform the lumpy material into a stable powdery state typical for standard powder. The mechanism of alkaline treatment consists in the irreversible rupture of oxo-bridging bonds in the material, and the formation of hydroxyl groups on the surface of zirconium particles, which is accompanied by the destruction of aggregates and their disintegration into individual particles. Treatment with sodium hydroxide solution of different concentration demonstrates no significant changes in chemical composition of particles surface layers and makes it possible to maintain the main physical and chemical characteristics of zirconium powder. Samples of zirconium powder were studied by scanning electron microscopy, X-ray spectral microanalysis. The content of total and active zirconium, the value of the specific surface area of the powders was determined. Their sensitivity to friction and electric spark is evaluated.

Metabolomics-based response of Salmonella to desiccation stress and skimmed milk powder storage.

The strong survival ability of Salmonella in low-moisture foods (LMFs) has been of public concern, and is considered a threat to people's health. Recently, the development of omics technology has promoted research on the molecular mechanisms of the desiccation stress response of pathogenic bacteria. However, multiple analytical aspects related to their physiological characteristics remain unclear. We explored the physiological metabolism changes of S. enterica Enteritidis exposed to a 24 h-desiccation treatment and a subsequent 3-month desiccation storage in skimmed milk powder (SMP) with an approach of gas chromatography-mass spectrometry (GC-MS) and ultra-performance liquid chromatography-Q Exactive-mass spectrometry (UPLC-QE-MS). A total of 8,292 peaks were extracted, of which 381 were detected by GC-MS and 7,911 peaks were identified by LC-MS/MS, respectively. Through analyses of differentially expressed metabolites (DEMs) and key pathways, a total of 58 DEMs emerged from the 24 h-desiccation treatment, which exhibited the highest relevance for five metabolic pathways, involving glycine, serine, and threonine metabolism, pyrimidine metabolism, purine metabolism, vitamin B6 metabolism, and pentose phosphate pathway. After 3-month SMP storage, 120 DEMs were identified, which were related to several regulatory pathways including arginine and proline metabolism, serine and threonine metabolism, β-alanine metabolism, glycerolipid metabolism, and glycolysis. The analyses of key enzyme activities of XOD, PK, and G6PDH and ATP content provided further evidence that supported the metabolic responses such as nucleic acid degradation, glycolysis, and ATP production played an important role in Salmonella's adaptation to desiccation stress. This study enables a better understanding of metabolomics-based responses of Salmonella at the initial stage of desiccation stress and the following long-term adaptive stage. Meanwhile, the identified discriminative metabolic pathways may serve as potentially useful targets in developing strategies for the control and prevention of desiccation-adapted Salmonella in LMFs.

Recombinant Alpha-1 Antitrypsin as Dry Powder for Pulmonary Administration: A Formulative Proof of Concept.

Alpha-1 antitrypsin (AAT) deficiency is a genetic disorder associated with pulmonary emphysema and bronchiectasis. Its management currently consists of weekly infusions of plasma-purified human AAT, which poses several issues regarding plasma supplies, possible pathogen transmission, purification costs, and parenteral administration. Here, we investigated an alternative administration strategy for augmentation therapy by combining recombinant expression of AAT in bacteria and the production of a respirable powder by spray drying. The same formulation approach was then applied to plasma-derived AAT for comparison. Purified, active, and endotoxin-free recombinant AAT was produced at high yields and formulated using L-leucine and mannitol as excipients after identifying compromise conditions for protein activity and good aerodynamic performances. An oxygen-free atmosphere, both during formulation and powder storage, slowed down methionine-specific oxidation and AAT inactivation. This work is the first peer-reviewed report of AAT formulated as a dry powder, which could represent an alternative to current treatments.

Effect of Intake position on powder fluidization and conveying characteristics in powder supply device

In this work, a novel built-in intake channel powder supply device was developed for the piston-driven powder fuel feeding system, and a multi-physical coupling model of the gas-powder-moving wall was established using the User Defined Function. A numerical study of powder fluidization and conveying characteristics in a novel powder supply device was presented by using a two-fluid model, and the effects of different intake positions on the flow characteristics in terms of dense gas-solid two-phase in the powder supply process were studied. The results show that the gas phase region is mainly distributed around the intake channel. The powder outlet flow rate fluctuation and the powder layer (εp = 0.1) area peak decreased by 36.6% and 62.5%, respectively, when the intake position is moved forward from 153.9 mm to 172.2 mm in the axial. The area-averaged gas velocity increases and the area-averaged powder volume fraction decreases at the two-phase throat with the forward movement of the intake position. There is a stable stage of the pressure change in the powder storage tank and in the delivery pipeline when the intake channel is arranged at 153.9 mm in the axial, which is more beneficial to the stable conveying of powder.

Influence of structural parameters on fluidization effect of typical fluidization unit of metal powder fuel

The metal powder fuel supply system is a critical technology for achieving multiple starts of a solid rocket engine. The supply system has a direct impact on the performance of the engine, which is one of the main problems to be solved. Therefore, the Eulerian continuous medium method is used to research the influence of structural parameters on fluidization effect of typical fluidization unit of metal powder fuel. The influence of the angle between the inlet of fluidization gas and the powder storage tank and the outlet diameter of the fluidization unit on the response characteristics and stability of the powder supply is investigated. The distributions of metal powder in the storage tank, fluidization region and outlet pipe are analyzed. From the results, it is concluded that the fluidization unit with an angle of 40° to 45° takes less time to reach a steady supply state. The outlet mass flow rate oscillates after the outlet diameter is 7 mm, and the oscillation frequency is 12 Hz. When the average mass flux of the powder at the outlet of the powder fluidization unit is 10610.32 kg/m2·s, a suitable tank pressure drop can sustain the powder fluidization unit.

(Invited) Electrochemical Stability of Prussian Blue Analogs and Implications for Energy Storage and Water Desalination Applications

The increasing share of renewables in our electricity grid requires affordable and scalable battery technology that uses sustainable materials and has long lifetime. At the same time, growing water scarcity necessitates new desalination technologies with a similar requirement for sustainability and lifetime. Prussian blue analogs (PBAs), e.g., manganese hexacyanoferrate, MnFe(CN)6, or nickel hexacyanoferrate, NiFe(CN)6, are promising intercalation materials for secondary batteries.1–4 Recently, this material class has been shown to be suitable for a novel energy-efficient water desalination approach, based on sodium intercalation into PBAs, sometimes referred to as battery desalination.5–8 Hence, PBAs are potentially suitable electrode materials for, both, energy storage and water desalination, but it is important to investigate the materials’ stability to processing conditions and repeated ion intercalation. Prussian blue analogs like NaxMnFe(CN)6, 0<x<2, show high sensitivity towards moisture, which results in structural change and loss of sodium from the structure.9,10 Different approaches can be utilized to mitigate this issue, such as surface coating or handling of the material under strictly inert conditions, starting from the storage of powder to slurry preparation and electrode processing.9,11 In this study, we investigated the changes in surface chemistry during ambient storage, water exposure and subsequent heating of stored PBAs. Infrared spectroscopy (ATR-FTIR) and thermal analysis (TGA-MS) of materials stored for different times ranging from one hour to one week show a sharp increase in the moisture content of the active material. X-ray diffraction of exposed materials shows a clear trend between hydration state and crystal structure. Furthermore, surface hydroxides and carbonates are found by ATR-FTIR. A reheating step at relatively low temperature shows the release of adsorbed and interstitial water, but hydroxides and carbonates remain on the surface of the active material.The moisture stability of PBAs has important implications for aqueous electrode processing in energy storage applications and water-based device operation in desalination applications. We demonstrate effective drying strategies of electrodes made with aqueous slurries and appropriate binders. The as-prepared water-based electrodes show similar cycling stability as their non-aqueous counterparts. In the desalination context, exposure of the active material to water is unavoidable and may reduce performance and lifetime since the material remains hydrated during operation. We quantify performance and lifetime metrics of the novel battery desalination cells that employ NiFe(CN)6 electrodes at opposite state-of-charge separated by an anion exchange membrane.12 Using objective metrics like retention of specific capacity (mAh/g), energy consumption (Wh/l) and productivity (l/h/m2) we show that these cells achieve vastly different performance for removal of monovalent and divalent ions. Stable charge/discharge cycling can be achieved for over 500 cycles with NaCl feed water, but rapid aging is observed with CaCl2 feeds. Synchrotron-based characterization of NiFe(CN)6 electrodes from the battery desalination cells is used to elucidate the reason for capacity fade (see Figure 1). X-ray absorption spectroscopy and X-ray fluorescence spectroscopy reveal Fe dissolution from the NiFe(CN)6 active material as a primary aging mode with CaCl2 water feeds. Based on the performance of Prussian blue analogs in, both, energy storage and water desalination, we will discuss potential synergies between these fields and strategies for efficient device design.13 References C. D. Wessells, S. V. Peddada, R. A. Huggins, and Y. Cui, Nano Lett., 11, 5421–5425 (2011).C. D. Wessells et al., ACS Nano, 6, 1688–1694 (2012).M. Pasta et al., Nat. Commun., 5, 1–9 (2014).A. Firouzi et al., Nat. Commun., 9 (2018).M. Pasta, C. D. Wessells, Y. Cui, and F. La Mantia, Nano Lett., 12, 839–843 (2012).J. Lee, S. Kim, and J. Yoon, ACS Omega, 2, 1653–1659 (2017).T. Kim, C. A. Gorski, and B. E. Logan, Environ. Sci. Technol. Lett., 4, 444–449 (2017).S. Porada, A. Shrivastava, P. Bukowska, P. M. Biesheuvel, and K. C. Smith, Electrochim. Acta, 255, 369–378 (2017).D. O. Ojwang et al., ACS Appl. Mater. Interfaces, 13, 10054–10063 (2021).J. Song et al., J. Am. Chem. Soc., 137, 2658–2664 (2015).L. Yang et al., J. Power Sources, 448, 227421 (2020).M. M. Besli et al., Desalination, 517, 115218 (2021).M. Metzger et al., Energy Environ. Sci., 13, 1544–1560 (2020). Figure 1. (a) Three-electrode cells for evaluation of electrochemical stability of NiFe(CN)6 towards mono- and divalent ion intercalation. (b) Specific capacity versus cycle number for 1C cycling with high and low concentrations of NaCl or CaCl2. (c) Visual inspection of electrolyte, revealing strong discoloration and brown precipitate after 300 cycles with 1 M CaCl2, and no discoloration after 400 cycles with 1 M NaCl. Figure 1

Lactose crystallization and Maillard reaction in simulated milk powder based on the change in water activity.

Maillard reaction (MR) and lactose crystallization (LC) are important reactions in the storage of milk powder. In this study, three models with different proteins based on skimmed milk powder were established to investigate the relationship between MR and LC at different water activities (aw ). Moisture sorption isotherm, glass transition temperature (Tg ), and glycation products were evaluated, and the protein structure and lactose crystallinity were determined. The results indicated that MR product content, browning, and LC subsequently enhanced with the increase in aw . The Tg value dropped lower than 0 at aw 0.43 in whey protein isolate-lactose (WP-Lac) model and at aw 0.54 in casein-whey protein isolate-lactose (CN-WP-Lac) model and casein-lactose (CN-Lac) model. The crystallinity of α-lactose monohydrate and anhydrous β-lactose in WP-Lac model was more significant than CN-WP-Lac and CN-Lac models (p<0.05). The molecular band of whey protein gradually blurred in the Sodium dodecyl-sulfate polyacrylamide gel electrophoresis image, and the content of α-helix of WP-Lac model increased by 45.15% from aw 0.33 to 0.53 (p<0.05), while that of CN-WP-Lac model increased by only 3.95% (p<0.05). With the increase in aw , WP-Lac model formed more browning and crystallization products than CN-WP-Lac model, indicating that the presence of micelle macromolecules and the interaction between casein and whey proteins limited the browning and crystallization in CN-WP-Lac model. Practical Application Maillard reaction and lactose crystallization are important reactions in the storage of milk powder, and the result will provide theoretical guidance for the development of milk powder in the food industry.

METHODOLOGY FOR CONDUCTING AN EXPERIMENTAL STUDY TO RESTORE THE CHARACTERISTICS OF PYROXYLIN POWDERS

One of the components of the problem of national security of Ukraine is the loading of warehouses with ammunition with an exhausted warranty period.&#x0D; Experience in the operation of ammunition shows that during long-term storage, pyroxylin powders used in ammunition are capable of spontaneously undergoing various physical and chemical transformations, which negatively affects the ballistic characteristics of ammunition. The lack of production of ammunition in Ukraine has led to the fact that ammunition is currently in operation, the storage time of which is more than 30 years.&#x0D; This article analyzes publications devoted to scientific research related to the problems of safe operation of pyroxylin powders. It is shown that one of the main problems in evaluating the properties of pyroxylin powders is the effective physical and chemical monitoring of their state and the prediction of changes occurring during long periods of operation. The relevance of studies of physical and chemical changes in the process of long-term storage of pyroxylin powders, as well as the determination of the possibility of their recovery and effective further use, is indicated.&#x0D; Various methods for assessing the chemical resistance of gunpowder and their analysis are given.&#x0D; A method is proposed for determining changes in the characteristics of pyroxylin powders, as well as a method for conducting an experiment to determine the possibility of regenerating powder charges for long periods of operation by treating them with hydrogen peroxide, and, consequently, changing the energy and ballistic characteristics of gunpowder.&#x0D; An experimental setup for controlling the calorimetric properties of gunpowder is presented. This experiment is carried out in order to determine the strength of gunpowder based on the balance ratios of the energy of gunpowder. The main balance equation underlying the proposed technique is given.&#x0D; Based on the results of the experiments, it is supposed to obtain the strength of the gunpowder processed according to the developed method, and corresponding to the storage life of the powder charge of ammunition.&#x0D; It has been determined that on the basis of solving the problem of long-term nitrocellulose powders, theoretical and methodological foundations for the regeneration of powder charges for homologation of the ballistic and energy characteristics of ammunition can be developed.

A comparison of benchtop and micro NIR spectrometers for infant milk formula powder storage time discrimination and particle size prediction using chemometrics and denoising methods

This study compared benchtop and micro NIR spectrometers in diffuse reflection mode (1158–2169 nm) to (i) discriminate infant milk formula (IMF) powder samples (n = 500) by storage time (0–12 months) and to (ii) predict IMF powder particle size parameters. Reference particle size parameters were determined using laser-light-scattering. Fast Fourier transform (FFT) and wavelet transform (WT) denoising methods were employed on micro NIR spectra to remove noise and enhance spectral features. Partial least square discriminant analysis (PLS-DA) and partial least squares regression (PLSR) modelling approaches were used to discriminate IMF by storage time and predict powder particle size, respectively. The models developed using the micro NIR denoised spectra had correct identifications (CI p ) of 89–100% for IMF storage time discrimination and RPDPs of 2.29–2.98 for particle size prediction, which were comparable to the model performances achieved using the benchtop NIR spectra (CI p values of 81.3–100% for IMF storage time discrimination and RPDPs of 2.08–3.07 for particle size prediction). This study demonstrated that the potential of micro NIR spectroscopy combined with chemometrics and denoising methods as a suitable process analytical technology (PAT) tool for IMF powder storage time discrimination and particle size prediction along the IMF distribution chain from production to consumer. • Benchtop and micro NIR models can assess IMF powder storage time and particle size. • IMF powder storage time was discriminated using PLS-DA modelling. • IMF powder particle size was predicted using PLSR modelling. • FFT and WT denoising methods are suitable to remove micro NIR spectral noise. • Micro NIR models had overall better performance than benchtop NIR models.

Anti-hygroscopic effect of wheat gluten on freeze-dried apple powder

To solve the problem of apple powder strong hygroscopicity, wheat gluten was selected as a natural anticaking agent and added into apple powder in different proportions. The moisture absorption data of the samples was monitored in different relative humidity environments at 25 °C and 35 °C. The results showed that the addition of wheat gluten could reduce the equilibrium moisture content and the size and number of agglomerates of freeze-dried apple powder. The fitting parameters of the Guggenheim-Anderson-DeBoer and the low-field nuclear magnetic resonance results revealed that the existence of wheat gluten restricted the water migration, which was conducive to maintain a good particle state of powder. To sum up, the wheat gluten as an anticaking agent could not only have the effect of inhibiting moisture absorption during the storage of freeze-dried apple powder, but also possess the potential to be used in various fruit powder production.

Effect of Storage of Skim Milk Powder, Nonfat Dry Milk and Milk Protein Concentrate on Functional Properties

The physicochemical changes during the storage of high protein powders, such as skim milk powder (SMP), nonfat dry milk (NDM), and milk protein concentrates (MPC), can result in a variation in the functional properties of the powders. The objective of this study was to evaluate the effects of the storage of various milk powders (SMP, NDM, MPC40, and MPC70) on their functional properties. Three different lots of the powders were collected from US manufacturers and were analyzed for functional properties after 3, 9, and 15 months of storage at 25 °C. Additionally, this study also evaluated the effects of seasonal variation on the functionality of SMP and NDM. Functional properties, such as solubility, emulsification ability index (EAI), foaming, and surface hydrophobicity index (SHI), were evaluated at each storage time point. The solubility of MPC70 and the foam overrun of SMP, MPC40, and MPC70 decreased significantly (p &lt; 0.05) with an increase in the storage time. The emulsification properties of MPC70 were significantly higher than other powders. Except for foam drainage, there was no effect of the season on the SMP and NDM functional properties. The storage of milk powders has an impact on some functional properties, and a proper selection of powders based on end-use is recommended.

Deciphering the impact of whey protein powder storage on protein state and powder stability

Whey protein concentrate powders can be strongly affected by storage conditions inducing both chemical and structural protein modifications. In the present work, a combination of different storage conditions were evaluated, leading to the evaluation of 6 different batches that were chosen in order to evaluate the impact of the following parameters: storage temperature, storage duration and storage heat load (°C.days). In each set the relative humidity was maintained at 70%. To estimate the impact of the three parameters, whey protein lactosylation, denaturation and aggregation were followed. It was shown that the highest temperatures (60 vs 55.5 °C and 41 vs 36 °C) led to greater protein modification, whereas the duration (17 vs 14 days and 33 vs 30 days) and the total heat load (low vs high C°.days) did not affect protein modification. Lactose content is known to be an important parameter for powder browning. Here, we show that if lactose content is crucial for the level of initial process induced browning of the powder, the additional browning that occurs during storage is mostly independent of lactose content. In addition, during storage, detected lactosylated proteins were found to be inversely proportional to powder browning indicating the occurrence of advanced Maillard reaction steps ( e.g. dicarbonyl and AGEs formation and production of melanoidins). Protein aggregates contained both β-lactoglobulin and α-lactalbumin and were mostly formed by non-disulphide covalent bonds. Interestingly, despite protein structure being strongly impacted, good powder rehydration properties were obtained for the studied conditions. • Whey powder functionality is not impacted by storage. • Maillard-induced protein modification is repeatable between powder productions. • Initial protein lactosylation content drives powder aging. • Browning during storage is not related to lactose content.

Insights into surface chemistry induced powder layer characteristic evolutions in additive manufacturing

Compared with large amount of work on the powder layer characteristics in powder-bed-based additive manufacturing (AM) under different operating conditions and powder properties, the significant effects of powder surface chemistry on the quality of the powder layer were less investigated. To further enhance people's insights in this aspect so as to obtain superior powder layer for subsequent process, Ti-6Al-4 V powders with different surface chemistries (e.g., the as received powder without any treatment, the moistened powder with surface H2O molecule, the exsiccated powder with grown nano-scaled oxides film) were firstly prepared, where the surface chemistry state of each powder was characterized and corresponding flowability and spreadability were measured in physical experiments. On this basis, systematic numerical investigations on the evolution of different surface chemistry induced powder layer characteristics during spreading were conducted. The results demonstrate that the surface moistened powder would deteriorate powder layer quality due to the strong cohesion effect between particles. However, the increase of the surface roughness on exsiccated powder could facilitate a greater deposition rate compared to that of the as-received powder during spreading, and therefore result in a powder layer with more pronounced apparent density. The mechanism lies in that high friction from the rough surface film could restrict the scattered motion behavior of sticky particles caused by the breakdown of cluster structure during the blade movement, and thus facilitate the most prominent deposition rate of this kind of particles during spreading. Nevertheless, the simultaneous increase of interactions within exsiccated powder also diminishes the boundary effect with blade and substrate, resulting in abnormal elevation of powder layer thickness, enlargement of internal pore volume, and depressed packing fraction correspondingly. Consequently, the powder with grown surface film is not ideal for printing, and the chemical reactions on powder that causes intensive film roughness should be prevented in powder storage and treatment process.

The Influence of Physical Activation of Portland Cement in the Electromagnetic Vortex Layer on the Structure Formation of Cement Stone: The Effect of Extended Storage Period and Carbon Nanotubes Modification

The article presents research of the influence of the electromagnetic vortex layer on the structure formation of cement stone during the activation of portland cement, both without additives and with carbon nanotubes modification. It has been shown that the storage of portland cement powders in open air for 60 days after activation in the electromagnetic mill leads to partial carbonization, wherein the role in absorption reducing of the super plasticizer additive is increased since there is more uniformly localization of the additive on the surface of the portland cement particles. The processing of portland cement in the electromagnetic mill leads to the physical activation of portland cement, which is accompanied by an increase in the amount of heat generated by the hydration of portland cement and the rate of hydration. Thus, the rate of hydration of compositions activated in the electromagnetic mill isincreased 1.615 times at the temperature of the thermostat 22 °C; 1.85 times at 40 °C; 2.71 times at 60 °C; 2.3 times at 80 °C. The modification of cement stonewith carbon nanotubes, which was obtained from portland cement activated in an electromagnetic mill, leads to a higher quantity of silicate phase of portland cement (by 12–39%), as confirmed by a decrease in the number of portlandite in these compositions by 8% in comparison with control composition.

Green synthesis of novel in situ micro/submicron-Cu paste for semiconductor interconnection

A green method for the synthesis of in situ Cu paste is developed. Cu particles are prepared through chemical reduction by selecting a special copper source, reducing agent, and solvent. Then the reaction solution is directly concentrated to obtain an in situ Cu paste. The synthesis of Cu particles and the preparation of Cu paste are conducted simultaneously, and the process of separation, purification, drying, storage, and re-dispersion of powder are reduced. Particles are not directly exposed to air, thus the oxidation of micro/submicron -Cu is effectively prevented, and the agglomeration of particles caused by drying and dispersion operations is simultaneously reduced. Furthermore, the proposed method has a certain universality, and different types of Cu sources can be used to prepare in situ paste with different sizes and morphologies. The entire preparation process is simple, efficient, green, and the yield can reach 99.99%, which breaks through the bottleneck of the application of traditional micro/submicron-Cu materials. Copper acetate-based in situ paste is sintered for 30 min at 260 °C and 2 MPa in a reducing atmosphere. The shear strength, resistivity, and thermal conductivity reach 55.26 MPa, 4.01 × 10–8 Ω·m, and 92.75 W/(m·K), respectively, which could meet the interconnection application of power semiconductor devices.

Moisture sorption isotherms and estimation of isosteric heat of sorption of donkey milk powder

The moisture sorption isotherms of donkey milk powder were studied at 20, 25 and 30°C for 0.22 to 0.93 aw through gravimetric method. GAB, Peleg, Smith and Oswin mathematical models were fitted to experimental data. Equilibrium moisture content of the sample increased from 0.0499 to 0.3255, 0.0447 to 0.2904, 0.0426 to 0.2618 kg.kg−1 solid at 20, 25 and 30°C with increasing aw from 0.22 to 0.93. Isotherm curves showed type II behavior. Monolayer moisture content decreased from 0.0373 to 0.0301 g.100 g−1 solids at 20 to 30°C. The net isosteric heat of sorption decreased from 98.55 to 0.74 kJ.mol−1 with increased moisture content from 2 to 20% (d.b.). The adsorption isotherm curves suggest that the sample requires more attention when handled in RH higher than 24, 33 and 42% at 20, 25 and 30°C. Novelty impact statement Donkey milk powder was stable below 42% RH at 30°C. The best-fitting Oswin model equation provides a solid foundation for future research on drying and storage of donkey milk powder. Isosteric heat of sorption of donkey milk powder decreases with increase in moisture content.

Exploration of the Effects of Metallic Powder Handling and Storage Conditions on Flowability and Moisture Content for Additive Manufacturing Applications

Metal powder-based additive manufacturing (AM) relies on consistently successful processing of feedstock powder, necessitating through-process predictability in powder properties and behavior. However, routine powder handling and storage may degrade powder performance by influencing flowability and moisture content through exposure to ambient conditions. Therefore, this study aimed to evaluate the effects of repeated environmental exposure on the flowability and moisture content of Al 5056 and Ta powders for AM applications. Using Carney Funnel flow tests, thermogravimetric analysis, and particle size/shape analysis, powder characterization helped elucidate powder property and behavioral changes with exposure. Results indicated inconsistent flowability and moisture content changes for both material types when exposure conditions were altered. Correlational statistics highlighted the most influential particle characteristics on powder behavior after exposure; particle morphology was most impactful for the semi-spherical Al 5056, whereas moisture content and particle size were most significant for the angular Ta. While exposure to laboratory conditions minimally changed powder performance in this study, caution is advised when handling and storing powders in more “extreme” environments. Powder users are urged to implement quality controls alongside powder characterization to pinpoint how specific powders should be treated, handled, and stored in a given environment for successful processing in AM.

Effect of initial turbulence on explosion behavior of stoichiometric methane-ethylene-air mixtures in confined space

The turbulent explosion process of stoichiometric CH4/C2H4/air mixtures was experimentally studied by using a standard 20 L sphere explosion system and it’s powder storage tank as the turbulence generator. Taking the initial turbulent environment and ethylene volume fraction as variables, the effects of turbulence intensity and fuel composition on explosion characteristics were studied. The results show that both turbulence intensity and ethylene content promote the explosion of the mixtures and increase the severity of the explosion, but the influence of turbulence intensity on combustion evolution mainly focuses on heat loss, while the influence of ethylene content mainly focuses on adiabatic explosion. When the ethylene ratios increase to 0.5 or more, the increase of explosion severity caused by turbulence is not obvious. The analysis of experimental results and numerical simulation shows that the influence of initial turbulence generated by powder storage tank on explosion is the result of the combined action of turbulent kinetic energy and combustible gas redistribution.

Identifying glycation hot-spots in bovine milk proteins during production and storage of skim milk powder

We investigated protein glycation in a complex milk system under controlled conditions representative of real-life consumer products, analysing intermediate and final products from skim milk powder production, and aged powder samples. We combined protein-centric LC-MS(/MS) with peptide-centric multi-protease LC-MS/MS focusing on the six most abundant bovine milk proteins. This strategy resulted in the identification of glycated proteoforms and of the extent of glycation per protein, high protein sequence coverage, and identification and relative occupancy of the glycation sites. We identified new glycation hot-spots additionally to the ones already described in literature. Primary sequence motif analysis revealed that glycation hot-spots were preceded N-terminally by a stretch rich in basic amino acids, and followed C-terminally by a stretch enriched in aliphatic and hydrophobic amino acids. Our study considerably extends the current understanding of milk protein glycation, discussing glycation hot-spots and their localisation in relation to the primary sequences and higher-order protein structures.