Vacuum Applications Research Articles

Application of microwave vacuum drying with process management in extract drying of personalized traditional Chinese medicine preparations

Extracts are important intermediates in the production of traditional Chinese medicines preparations. The drying effect of extracts will directly affect the subsequent production process and the quality of the preparation. To meet the requirements of high drug loading, short time consumption, and simple production process of personalized traditional Chinese medicine preparations, this study explored the application of multi-program microwave vacuum drying process in the extract drying of personalized traditional Chinese medicine preparations. The influencing factors of microwave vacuum drying process were investigated for 5 excipients and 40 prescriptions. Taking the feasibility of drying, drying rate, drying time, and dried extract status as indicators, this study investigated the feeding requirements of microwave vacuum drying. With the dried extract status as the evaluation indicator, the three drying programs(A, B, and C) were compared to obtain the optimal drying condition. The experimental results showed that the optimal feeding conditions for microwave vacuum drying were material layer thickness of 2 cm and C program(a total of 7 drying processes), which solved the problem of easy scorching in microwave drying with process management. Furthermore, the preset moisture content of the dried extract in microwave drying should be 4%-5%, so that the dried extract of traditional Chinese medicine preparation had uniform quality, complete drying, and no scorching. This study lays a foundation for the application of microwave drying in the production of traditional Chinese medicine preparations, promoting the high-quality development of personalized traditional Chinese medicine preparations.

Cation exchange synthesis of AgBiS2 quantum dots for highly efficient solar cells.

Silver bismuth sulfide (AgBiS2) nanocrystals have emerged as a promising eco-friendly, low-cost solar cell absorber material. Their direct synthesis often relies on the hot-injection method, requiring the application of high temperatures and vacuum for prolonged times. Here, we demonstrate an alternative synthetic approach via a cation exchange reaction. In the first-step, bis(stearoyl)sulfide is used as an air-stable sulfur precursor for the synthesis of small, monodisperse Ag2S nanocrystals at room-temperature. In a second step, bismuth cations are incorporated into the nanocrystal lattice to form ternary AgBiS2 nanocrystals, without altering their size and shape. When implemented into photovoltaic devices, AgBiS2 nanocrystals obtained by cation exchange reach power conversion efficiencies of up to 7.35%, demonstrating the efficacy of the new synthetic approach for the formation of high-quality, ternary semiconducting nanocrystals.

Evaluation of the efficacy of vacuum sealing drainage in combination with silver-containing dressings for the improvement of chronic refractory wounds.

The aim of this study was to explore the clinical efficacy of vacuum sealing drainage in combination with silver-containing dressings for the treatment of chronic refractory wounds. In this retrospective study, 80 patients with chronic refractory wounds who were treated in the hospital were retrospectively selected as the study objects. Based on the treatment modalities, the patients were divided into the study group (SG; n = 40, receiving vacuum sealing drainage combined with silver-containing dressings) and the control group (CG; n = 40, receiving vacuum sealing drainage alone). The total effective rate of the SG was 92.5%, significantly higher than the 75% in the CG. After treatment, the SG exhibited lower positive rates in bacterial culture, as well as decreased levels of C-reactive protein and erythrocyte sedimentation rate compared to the CG. Starting from the sixth day of treatment, the SG reported statistically significant lower pain intensity scores than the CG. Additionally, the SG exhibited significantly lower dimension scores in terms of scar thickness, color, tenderness, and vascular distribution compared to the CG. The combined application of vacuum sealing drainage and silver-containing dressings demonstrated a positive treatment efficacy for patients with chronic refractory wounds.

Low Parts Per Trillion Detection of Iodinated Disinfection Byproducts in Drinking Water and Urine using Vacuum-Assisted Sorbent Extraction and GC-MS/MS.

Disinfection byproducts (DBPs) are ubiquitous environmental contaminants, which are present in virtually all drinking water and linked to detrimental health effects. Iodinated-DBPs are more cytotoxic and genotoxic than chloro- and bromo-DBPs and are formed during disinfection of iodide-containing source water. Liquid-liquid extraction (LLE) paired with gas chromatography (GC)-mass spectrometry (MS) has been the method of choice in the study of low molecular weight iodinated-DBPs; however, this method is laborious and time-consuming and struggles with complex matrices. We developed an environmentally friendly method utilizing headspace solid phase extraction with the application of vacuum to measure six iodinated-trihalomethanes (I-THMs) in drinking water and urine. Vacuum-assisted sorbent extraction (VASE) has the ability to exhaustively and rapidly extract volatile and semivolatile compounds from liquid matrices without the use of solvent. Using VASE with GC-MS/MS provides improved analyte recovery and reduced matrix interference compared to LLE. Additionally, VASE enables extraction of 30 samples simultaneously with minimal sample handling and improved method reproducibility. Using VASE with GC-MS/MS, we achieved quantification limits of 3-4 ng/L. This technique was demonstrated on drinking water from four cities, where five I-THMs were quantified at levels 10-33 times below comparable LLE methods with 10 times lower volumes of sample (10 mL vs 100 mL).

Application of Vacuum and Convective Drying Processes for the Valorization of Pisco Grape Pomace to Enhance the Retention of its Bioactive Compounds

Application of Vacuum and Convective Drying Processes for the Valorization of Pisco Grape Pomace to Enhance the Retention of its Bioactive Compounds

(Invited) Multifunctional Plasma-Enabled Low Dimensional Nanoarchitectures: From Synthesis to Devices

In this presentation, we will give an overview on our last advances in the exploitation of plasma and vacuum deposition methods for the nanoengineering of thin films and supported low-dimensional materials. A key step in the development of such nanoarchitectures is the implementation of a soft-template procedure based on the use of single-crystal small-molecule nanowires grown on processable substrates under mild conditions. We will demonstrate the application of vacuum and plasma-assisted deposition techniques to develop complex nanowires (NWs) and nanotubes (NTs) with a core@multishell morphology where each shell adds functionality or multifunctionality to the system. The steps required for the integration of these nanomaterials as supported or in-device applications will be presented. Two final applications will drive the presentation, namely, the development of multisource energy harvesters (and self-powered sensors) and novel approaches for smart and efficient de-icing by acoustic waves covering the topics of the 3DScavengers and SOUNDofICE EU projects. The universal character of vacuum and plasma methods allows for the deposition of an unprecedented variety of possibilities, including, organic (small-molecules, organic nanocomposites, polymeric layers), inorganic (metal and metal oxides), hybrid (hybrid perovskite) materials acting as conducting, semiconducting, dielectric, photo-absorbent, piezoelectric or plasmonic components in a multilayer or radial configuration. We will share the results accomplished during the last years in the field of energy harvesting (solar cells,[1-4] piezoelectric and triboelectric nanogenerators[5-7]), semi-transparent nanoelectrodes,[8] wetting [9], de-icing and anti-icing.[10-11] References Filippin, A., Sanchez-Valencia, J., Borras, A. et al. (2017) Nanoscale, 9:8133-8141.Barranco, A., Borras, A., Sanchez-Valencia J. R. et al. (2020) Adv. Ener. Mater 10:1901524.Castillo, J., Borras, A., Sanchez-Valencia J.R. et al. (2022) Adv. Mater. 34:2107739.Obrero, J., Borras A., Barranco, A. (2022) Adv. Ener. Mater. 12:2200812.Filippin, A. N., Borras, A. et al. (2019) Nano Energy 58:476-483.García-Casas, X., Borras, A. et al. (2022) Nano Energy 91:106673.García-Casas, X. Borras, A. et al. Patent application Self-powered triboelectric transductor device for drops and liquids. EP23382176.8Castillo-Seoane, J., Borras, A. et al. (2021) Nanoscale 13:13882.Montes, L., Borras, A. et al. (2021) Adv. Mater. Interf. 21:2100767.Lopez-Santos, C., Borras, A. et al. (2019) Langmuir 35:16876.Del Moral, J., Montes, L., Borras, A. et al. (2023) Adv. Funct. Mater. 2023, 2209421

Influence of the ratio of nozzle inlet to nozzle throat areas on the performance of a jet pump for vacuum applications using computational fluid dynamics

The nozzle design is one of the most important issues because it determines the pressure range and the other dimensions to guarantee an adequate performance of a jet_pump. An incorrect design of this part can cause shock waves and unnecessary overexpansion of the power fluid. The nozzle’s main purpose is to allow the high-pressure, low-velocity primary fluid to be accelerated in such a way as to substantially decrease the fluid pressure while increasing its velocity. This is achieved because the subsonic flow accelerates when entering the convergent part of the nozzle, obtaining a sonic or supersonic flow at the nozzle throat that accelerates even more when entering the divergent part of the nozzle. Therefore, to achieve the highest possible nozzle discharge velocity, the nozzle must be able to change the flow conditions from subsonic to supersonic. Considering the high importance of the nozzle design in the jet_pump performance, five cases are simulated in the present work, where the ratio of nozzle inlet to nozzle throat areas is modified (10,15,20,25 y 30), to study the behavior of three performance parameters, namely, drag coefficient (Cd), pressure ratio (PR) and Energy Efficiency (η), as well as the Mach number (Ma) and velocity fields.

Vac-and-fill: A micromoulding technique for fabricating microneedle arrays with vacuum-activated, hands-free mould-filling

We report a simple and reproducible micromoulding technique that dynamically fills microneedle moulds with a liquid formulation, using a plastic syringe, triggered by the application of vacuum (‘vac-and-fill’). As pressure around the syringe drops, air inside the syringe pushes the plunger to uncover an opening in the syringe and fill the microneedle mould without manual intervention, therefore removing inter-operator variability. The technique was validated by monitoring the plunger movement and pressure at which the mould would be filled over 10 vacuum cycles for various liquid formulation of varying viscosity (water, glycerol, 20% polyvinylpyrrolidone (PVP) solution or 40% PVP solution). Additionally, the impact of re-using the disposable syringes on plunger movement, and thus the fill pressure, was investigated using a 20% PVP solution. The fill pressure was consistent at 300–450mbar. It produced well-formed and mechanically robust PVP, poly(methylvinylether/maleic anhydride) and hydroxyethylcellulose microneedles from liquid formulations. This simple and inexpensive technique of micromoulding eliminated the air entrapment and bubble formation, which prevent reproducible microneedle formation, in the resultant microneedle arrays. It provides a cost-effective alternative to the conventional micromoulding techniques, where the application of vacuum (‘fill-and-vac’) or centrifugation following mould-filling may be unsuitable, ineffective or have poor reproducibility.

Observations of wrinkling in Non-Crimp Fabrics during multi-ply stack forming using in situ XCT scanning

This paper shows the internal evolution of wrinkles occurring in a single diaphragm forming process using time-resolved in situ XCT scanning. Forming trials were carried out over a curved C-spar geometry using Non-Crimp Fabric (NCF) plies of 45°/135°, 0°/90° and 0°/45° orientations arranged in single-orientation and mixed-orientation stacks. Results show most of the diaphragm movement and change in wrinkle size, shape, and location occurs in the early application (<0.1 bar) of vacuum. The further application of vacuum shows consolidation, with wrinkle size decreasing but shape and location remaining largely unchanged. Single-orientation stacks of 45°/135° plies showed the closest resemblance between initial and final wrinkling, while mixed-orientation stacks showed complex wrinkling due to the 0° plies creating internal ply separation due to excess length. Overall, the study shines a light on the internal interaction between layers that occurs during wrinkling, showing mechanisms only observable with XCT.

Compression Characteristics of Liquid Ring Compressors With Fixed and Freely Rotating Casings

Abstract Liquid ring compressors (LRC) are used for a wide range of compression and vacuum applications, including corrosive or flammable gases for which other compression technologies may not be feasible. The presence of a surrounding liquid ring may offer the possibility of polytropic compression due to incremental heat loss to the liquid. This aspect may play a critical role in compression (and expansion) processes of heat engine cycles toward approaching the targeted Carnot efficiencies. To date, published research addressing the physical phenomena behind LRC is highly limited. Experimentally studying these machines will result in a demonstration of aggregate performance. In order to improve our understanding of LRC with and without freely rotating casings and to be able to analyze the complex inner workings, a numerical approach using computational fluid dynamics (CFD) tools, supported by available experimental data for validation purposes, has been established. Physical parameters such as water–air interface, temperature, pressure, entropy production, vorticity, and shear strain rate are presented for a baseline geometry taken from the open literature. Finally, temperature-entropy paths and isothermal and isentropic efficiencies are presented. The significant performance gain from the freely rotating casing is highlighted. Detailed results present insights into work addition processes of such machines.

A new controllable capillary-type standard leak for vacuum applications

A new controllable capillary-type standard leak for vacuum applications

Peruvian carrot chips obtained by microwave and microwave-vacuum drying

Peruvian carrot is a root from South America. Despite its nice taste and health-promoting effects, commercialization of Peruvian carrot is restricted due to its short shelf life and post-harvest losses. This study aimed to obtain Peruvian carrot chips at different drying processes. The comparison with convective drying at 70 °C (CD-70) showed that the microwave (MW) and microwave vacuum (MWV) technologies improved the quality of the chips (at 100, 250, and 400 W). It was found that a shortening in the drying time caused by the microwave power level partially controlled the textural collapse and crispness, besides reducing hardness and shrinkage characteristics and preserving β-carotene content. However, it also promoted phenolic compound degradation and color changes. The vacuum application in microwave drying (MWV) maintained the physical improvement observed in MW besides aiding in preserving phenolic compounds, β-carotene, and color changes. The results suggested that MWV-100 drying of Peruvian carrots was able to produce chips with suitable physical and nutritional quality.

Fluorinated Silane-Modified Filtroporation Devices Enable Gene Knockout in Human Hematopoietic Stem and Progenitor Cells.

Intracellular delivery technologies that are cost-effective, non-cytotoxic, efficient, and cargo-agnostic are needed to enable the manufacturing of cell-based therapies as well as gene manipulation for research applications. Current technologies capable of delivering large cargoes, such as plasmids and CRISPR-Cas9 ribonucleoproteins (RNPs), are plagued with high costs and/or cytotoxicity and often require substantial specialized equipment and reagents, which may not be available in resource-limited settings. Here, we report an intracellular delivery technology that can be assembled from materials available in most research laboratories, thus democratizing access to intracellular delivery for researchers and clinicians in low-resource areas of the world. These filtroporation devices permeabilize cells by pulling them through the pores of a cell culture insert by the application of vacuum available in biosafety cabinets. In a format that costs less than $10 in materials per experiment, we demonstrate the delivery of fluorescently labeled dextran, expression plasmids, and RNPs for gene knockout to Jurkat cells and human CD34+ hematopoietic stem and progenitor cell populations with delivery efficiencies of up to 40% for RNP knockout and viabilities of >80%. We show that functionalizing the surfaces of the filters with fluorinated silane moieties further enhances the delivery efficiency. These devices are capable of processing 500,000 to 4 million cells per experiment, and when combined with a 3D-printed vacuum application chamber, this throughput can be straightforwardly increased 6-12-fold in parallel experiments.

Use of coconut sugar as an alternative agent in osmotic dehydration of strawberries.

This study aimed to evaluate coconut sugar (CS) as an alternative osmotic agent to sucrose for the osmotic dehydration (OD) of strawberries. OD was performed by immersing strawberries cut into 13.6±0.4mm edge cubes in osmotic solutions of CS or sucrose, at two different concentrations (40% and 60%, w/w), with and without application of vacuum (AV) in the first 20min of the process. The total OD time was 300min. Evaluations of the kinetics of solid gain (SG), water loss (WL), and weight reduction (WR) were performed at 30, 60, 120, 180, 240, and 300min. SG, WL, and WR increased over the OD time and showed values of up to 7.94%, 63.40%, and 55.94%, respectively. AV increased WL, WR, shrinkage, pH, and total color difference and decreased anthocyanin, ascorbic acid (AA), phenolic, and antioxidant contents. The higher concentration led to higher SG, WL, WR, shrinkage, hardness, and lower moisture content, water activity, anthocyanin, AA, phenolic, and antioxidant contents. The use of CS instead of sucrose had little influence on strawberry properties, except pH and color responses. The optimal treatment was using a 60% CS solution without AV, showing a very distinct color change, hardness increased by approximately 4.5 times and maintenance of acidity, anthocyanins, AA, total phenolics, and antioxidants of 38.0%, 39.6%, 11.8%, 30.0%, 31.1%, and 30.3%, respectively, compared to fresh strawberries. PRACTICAL APPLICATION: Osmotic dehydration of fruit is a process traditionally carried out using sucrose. However, increasing health concerns have made consumers seek alternative sugars to sucrose. The use of coconut sugar made it possible to produce osmo-dehydrated strawberries different from the traditional one, maintaining product quality and process efficiency.

Yeast cell vacuum infusion into fungal pellets as a novel cell encapsulation methodology

Immobilized yeast cells are used industrially in winemaking processes such as sparkling wine and Sherry wine production. Here, a novel approach has been explored for the infusion and immobilization of yeast cells into filamentous fungal pellets, which serve as a porous natural material. This was accomplished through vacuum application to force the yeast cells towards the core of the fungal pellets followed by culture in YPD medium to promote their growth from the interior. This method represents an improved variation of a previous approach for the assembly of “yeast biocapsules,” which entailed the co-culture of both fungal and yeast cells in the same medium. A comparison was made between both techniques in terms of biocapsule productivity, cell retention capacity, and cell biological activity through an alcoholic fermentation of a grape must. The results indicated a substantial increase in biocapsule productivity (37.40-fold), higher cell retention within the biocapsules (threefold), and reduction in cell leakage during fermentation (twofold). Although the majority of the chemical and sensory variables measured in the produced wine did not exhibit notable differences from those produced utilizing suspended yeast cells (conventional method), some differences (such as herbaceous and toasted smells, acidity, bitterness, and persistence) were perceived and wines positively evaluated by the sensory panel. As the immobilized cells remain functional and the encapsulation technique can be expanded to other microorganisms, it creates potential for additional industrial uses like biofuel, health applications, microbe encapsulation and delivery, bioremediation, and pharmacy.Key points• New approach improves biocapsule productivity and cell retention.• Immobilized yeast remains functional in fermentation.• Wine made with immobilized yeast had positive sensory differences.

Effects of seed treatments on the germination of Golkoy palm (Phoenix theophrasti Greuter subsp. golkoyana Boydak)

Datça palm (Phoenix theophrasti Greuter) is the only palm taxa in the European continent. Its subspecies, Golkoy palm (Phoenix theophrasti Greuter subsp. golkoyana Boydak) was recorded only in Turkey. This subspecies, which spreads in sensitive ecosystems, needs to be carefully protected. Although there are three natural populations of Datça palm in Turkey, there is only one population of Gölköy palm. This population is under threat due to factors such as tourism, pollution, urbanization, use of groundwater and forest fires. In this respect, the continuity of the species should be ensured by taking in-situ and ex-situ protection measures immediately. One of the ex-situ conservation measures involves the propagation of the species from seed. Cold-wet stratification is applied to remove dormancy in Gölköy palm seeds. In this study, GA3, ultrasound and vacuum applications at different times were applied to remove dormancy in seeds and shorten germination time. At the end of the study that lasted for 10 weeks, it was determined that GA3, vacuum and ultrasonic applications increased the germination rate of the seeds and shortened the germination period. While the highest germination rate was reached in the seeds treated with GA3, (91.4%), the germination rate was 88.3% and 88.6%, respectively, in 60 and 120 min ultrasound applications. The germination rate of the seeds in which vacuum was applied for 60 and 120 minutes was found to be 29.9% and 48%, respectively. The lowest germination was 6.3% in the control group seeds.

Engineering application of vacuum preloading combined with electroosmosis technique in excavation of soft soil on complex terrain.

This paper presents the design and construction of vacuum preloading incorporated with electroosmosis (VPE) engineering application for the treatment of soft soil on complex terrain for sluice foundation excavation in order to reduce the amount of cement used in construction. Monitoring was conducted during the VPE treatment and laboratory geotechnical tests were carried out once the treatment came to an end. Results show that the electrification mode has a significant influence on electric energy consumption. Stepped-up voltage helped in saving electric energy while electrode conversion consumed a lot of electric energy. The dispersion of soil parameters became larger after VPE treatment. The stability of physical parameters is better than the mechanical parameters, and the latter is better than the deformation parameters. Soil water content has a linear relationship with density and compression coefficient. The given linear fitting equations can help in simplifying the calculation and acquisition of these indexes. Although the mean values of the soil index parameters slightly improved, their coefficient of variation (COV) significantly increased. These locations with improved index parameters scattering in the construction site ensured that the subsequent construction tasks such as pit slope and excavation were successfully realized in this area.

Dynamic N2 Binding at High-Spin Co(I) Supported by N,N,C Heteroscorpionates

Controlling N2 binding at transition-metal centers is essential in facilitating its rapid functionalization. Herein, we report the synthesis of high-spin four-coordinate Co–N2 complexes bound by our recently developed class of N,N,C heteroscorpionate ligands. End-on bridging and terminal binding modes for Co-bound N2 are both readily accessed by adjusting the steric profile of the supporting ligand. In the reported complexes, N2 is only weakly bound and is reversibly lost upon application of vacuum or an Ar atmosphere, with concomitant formation of an unusual Co–C–Si 3-center–2e– interaction. This work further demonstrates the power of steric control in modulating small-molecule binding at low valent centers.

INTERACTION OF HEAT TRANSFER METHODS, STORAGE TEMPERATURE AND PACKAGING ATMOSPHERE ON QUALITY OF PROCESSED CHICKEN MEAT

This research investigated the combined effects of cooking methods (household griddle (C1), household conventional oven (C2), industrial oven (C3), storage temperature (refrigeration /freezing) and packaging system (aerobic and vacuum), on quality of chicken burgers. The results show that refrigeration storage favours the retention of moisture content and the juiciness of chicken burgers, but the application of vacuum (RV) was the best option to maintain the juiciness and moisture content (p &lt; 0.05) of the samples prepared in an industrial oven with forced-air convection. The highest protein content was observed in the samples that were frozen in vacuum packaging (FV), and the lipid content was highest in the samples chilled in conventional packaging (RC) at 1 atm. Regardless of the cooking method used and the internal pressure of the packages (≤ 1 atm), refrigerated storage contributed to the best scores (p &lt; 0.05) for color and flavor attributes. The treatments that presented the highest sensory acceptance index were the frozen samples in vacuum packaging prepared in the industrial oven, conventional oven, and grill (90%, 82.66%, and 74.33%, respectively).

Systematic investigation of wear-induced cold welding in ultrahigh vacuum piezoelectric motors with non-metallic coatings.

Piezoelectric motors are widely used in various applications where both precision positioning and miniaturization are required. Inertial or quasi-static motors are commonly employed because of their high accuracy, which demands consistent sliding friction between moving sliders and their static counterparts for reliable operation. In general, slider wear is unavoidable after long-term use. This wear can often lead to more serious cold welding in vacuum, which is also referred to as friction welding induced by direct contact between similar metal surfaces. Non-metallic coatings can prevent such unwanted cold welding in ultrahigh vacuum (UHV) applications. However, the practical reliability of available coatings under UHV conditions still remains to be elucidated. Here, we systematically investigate the practical reliability of commonly used, UHV-compatible lubricant coatings for piezoelectric motors in vacuum. We demonstrate that polytetrafluoroethylene (PTFE) shows the most reliable long-term operation in vacuum, while other coatings eventually lead to wear-induced cold welding and motor failure. Our findings provide a simple and effective method to improve the long-term performance of UHV piezoelectric motors by coating the slider surface with PTFE.