High Hygroscopicity Research Articles

Effects of partial precipitation and freeze-drying on morphology and physicochemical properties of rice starch hydrolysates

Agricultural bio-catalysis is of immense scientific interest due to its increasing importance in the efforts for more sustainable agriculture while optimizing environmental impacts. In our studies, native rice starch was hydrolyzed with various alpha-amylase concentrations (0, 0.1, 0.2, and 0.3% w/w of starch) at 50°C for 20 min; then purified by partial precipitation (PP) with organic solvents, or freeze-drying (FD) without further purification. The rice starch hydrolysates (RSH) produced by different methods (PP or FD) were determined for dextrose equivalent (DE), morphology, and some physicochemical properties including bulk density, moisture content, hygroscopicity, and water solubility. The results showed that at the same alpha-amylase treatment conditions, the RSH obtained by the PP method had lower DE values and production yields than those of RSH obtained by FD method. The FD-RSH had higher DE values, lower bulk densities and moisture contents, higher hygroscopicity and water solubility. In morphology, the PP-RSH (DE 10.2) had a larger particle size and more condensed microstructure compared to the FD-RSH of almost similar DE 13.5. These findings showed that the PP method resulted in lower-DE RSH with different morphological and physicochemical properties compared to those obtained by the FD method.

Substantiation of the composition of sublingual tablets for the treatment of CNS disorders

Aim. To develop the composition of sublingual tablets with L-tryptophan, glycine and a dry peony extract. Materials and methods. L-tryptophan, glycine and a dry peony extract were used as active pharmaceutical ingredients; Lactose GranuLac 200, MCC 102, HPMC methocel K4M CR Premium, HPMC methocel E4M CR Premium, aspartame, maltodextrin, sorbitol, sucralose, Mint cloroph FLV PDR, Strawberry FLV PDR, Apple FLV PDR, Plasdone K-25, crospovidone XL-10, nonessylin and calcium stearate were used as excipients. The pharmacotechnological studies were conducted in accordance with the methods of the State Pharmacopoeia of Ukraine. Results and discussion. The studies of the pharmacotechnological properties of APIs showed unsatisfactory results (poor fluidity, poor cohesive properties; high hygroscopicity of the peony extract), so it was decided to improve the technological properties of the active substances by wet granulation. Plasdone K-25 (15% aqueous solution) was chosen as a binder. The next step was to select a flour adhesive to improve the bioavailability of the active ingredients. According to the literature, HPMC was included in the composition of the test samples: HPMC methocel E4M CR Premium and HPMC methocel K4M CR Premium. According to the research results, HPMC methocel K4M CR Premium was included in the composition. The tablets developed had a bitter taste due to the presence of tryptophan and the peony extract. To correct the taste and odor, aspartame and Mint cloroph FLV PDR were used. Their optimal content in the formulation was experimentally determined. Conclusions. As a result of the studies conducted, the following substances have been selected: the binder for granulating the tablet mixture – Plasdone K-25; the flour adhesive to improve bioavailability – HPMC methocel K4M CR Premium; flavors for taste and odor to mask the bitter taste of sublingual tablets – aspartame and Mint cloroph FLV PDR.

Synthesis of Tetrabutylammonium Tri(1,1,1,3,3,3-hexafluoro-2-propanol)-Coordinated Fluoride and Its Application to Anodic Fluorination

Organofluorine compounds are widely used in pharmaceuticals, agrochemicals, and functional materials due to their specific properties. However, organofluorine compounds are rarely found in nature. Therefore, organofluorine compounds must be synthesized using fluorinating agents. While Hydrogen fluoride (HF) is the most typical nucleophilic fluorinating agent, it is toxic and corrosive. Furthermore, HF is a gas at room temperature, making it difficult to handle in the ordinary laboratory. On the other hand, potassium fluoride (KF) is one of the safest and cheapest fluorinating agents, but KF is insoluble in most organic solvents. In contrast, 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) dissolves KF at high concentrations.Tetrabutylammonium fluoride (TBAF) is a highly reactive fluorinating agent that is soluble in organic solvents. However, preparation of anhydrous TBAF is difficult, because TBAF readily forms hydrates due to its high hygroscopicity. The reaction of tetrabutylammonium cyanide with hexafluorobenzene is one of the most promising methods for the synthesis of TBAF. On the other hand, TBAF-alcohol complexes such as TBAF(t-BuOH)4 have been reported as fluorinating agents with low hygroscopicity. With these facts in mind, we investigated the synthesis of TBAF from KF based on the ion exchange reaction between KF and tetrabutylammonium bromide (TBABr) in HFIP in this work.First, TBAF was synthesized by the ion exchange reaction between KF and TBABr in HFIP. 1H and 19F NMR measurements of the obtained product revealed that it is not TBAF but TBAF(HFIP)3 with three molecules of HFIP coordinated to TBAF. The TBAF(HFIP)3 was obtained in excellent yield without complicated operations. Next, anodic fluorination of a sulfide was investigated using TBAF hydrate or TBAF-alcohol complexes. As results, the corresponding fluorinated product was obtained in good yield only when TBAF(HFIP)3 was used. These results may be due to the low nucleophilicity and oxidation resistance of HFIP. From these results, TBAF(HFIP)3 would be a promising new supporting electrolyte and fluorinating agent. Figure 1

Scintillation Properties of Yb2+-Doped LiBr Single Crystals

As neutron detectors, 3He proportional counters have generally been used in security, environmental monitoring, medicine, and well-logging fields. The 3He is a product produced during β-decay of 3H. The 3H has generally been used in nuclear weapons, and the supply of 3He decreased due to nuclear disarmament and prohibition of nuclear experiment. However, the demand of the neutron detectors rapidly became high in the security field after September 11th terrorist attacks in 2001, and the demand of 3He became higher than the supply. Therefore, scintillators for neutron detection have been required as alternative detectors for 3He proportional counters. The required properties of scintillators for neutron detection are high light yield (LY), neutron-γ discrimination capability, large cross section for neutron capture, small effective atomic number (Z eff), non-hygroscopicity, and high transparency etc. 6Li-based inorganic scintillators have been focused because 6Li has a large cross section for neutron capture (940 barn) and high Q-value (4.8 MeV) in the 6Li (n, α) 3H nuclear reaction. In this reaction, α-ray and 3H with the total energy of 4.8 MeV were generated, and these charged particles produce numerous secondary electrons. Finally, the luminescence is caused by recombination of electrons and holes in luminescence centers. Up to now, Ag-doped ZnS/LiF, Ce-doped Li-glass, Eu-doped LiCaAlF6, Eu-doped LiI, and Ce-doped Cs2LiYCl6 have been developed as commercial 6Li-based inorganic scintillators. However, these scintillators do not fully satisfy all the required properties, and research activities have continued to find new scintillators for neutron detection. Lithium halide compounds are one of the promising hosts for neutron detection because of high Li-concentration. Among them, Eu-doped LiI has been intensely researched because of high LY but underutilized compared with other commercial scintillators due to high hygroscopicity. LiBr shows less hygroscopicity and has smaller Z eff (Z eff=34) than those of LiI. From the reasons, LiBr is one of promising candidates as neutron scintillators. So far, photoluminescence and scintillation properties of Eu-doped LiBr were evaluated in our previous study. The LY of Eu-doped LiBr was 4,600 ph/n under 252Cf neutron irradiation, and the LY was lower than that of commercial scintillators for neutron detection. Therefore, the improvement of the LY is required by optimization of the luminescence center elements. Yb2+ shows broad band due to 4f135d1–4f14 transition which is electric-dipole allowed for the free ion. Two emission bands are sometimes observed because the excited states of Yb2+ are divided into low energy level with reversed spin states and high energy level preserves spin states. These emission bands are spin-forbidden and spin-allowed transitions, respectively. So far, there are no reports about photoluminescence and scintillation properties of Yb-doped LiBr. In this study, LiBr doped with various concentration of Yb2+ were synthesized by the vertical Bridgman method, and the photoluminescence and scintillation properties were evaluated. According to scintillation spectra under X-ray irradiation, all the samples showed two emission bands at 420 and 450 nm. These emission bands would be ascribed to spin-forbidden and spin-allowed 4f135d1–4f14 transition of Yb2+. In this presentation, we will report results of the luminescence properties under UV and X-ray irradiation and pulse height spectra under γ-ray and neutron irradiation.

Hygrothermal characterization of cement mortar composites incorporating micronized miscanthus fibers

This work investigates both the moisture dependence of thermal properties and the hygric behavior of cement mortars incorporating different proportions of micronized miscanthus fibers up to ∼7 wt%. The experimental program encompasses thermal characterization at dry (10 % RH), moderate (50 % RH), and saturated (100 % RH) states of samples, along with hygric characterization of the various mortar specimens through sorption-desorption tests, water vapor permeability assessment, Moisture Buffer value (MBV) determination, and capillary absorption tests. Thermal measurements showed a significant decrease in thermal conductivity with the addition of fibers. For a given biobased mortar composition, conductivity values were almost identical at dry/moderate RH level but exhibited an increase at saturation. This shift was attributed to the fibers' absorptive properties, which lead to a higher water content within the samples in saturated humidity environments. Collectively, the moisture sorption, moisture buffering capacities, water vapor permeability, and capillary absorption properties demonstrated consistent enhancement with rising fiber content, confirming the significant impact of plant fibers on the material's hygrothermal properties. In addition, the GAB model (Guggenheim- Anderson- de Boer) was used to fit the sorption and desorption isotherms, yielding a good correspondence with experimental data. Finally, mortars with the higher fiber contents (M7.5 F and M10F with 5.70 wt% and 6.94 wt% of fibers, respectively) combined high hygroscopicity and low thermal conductivity values (even under moisture-saturated conditions), making them promising candidates for applications requiring both good hygric performance and effective insulation properties.

Quality assessment of yellow mealworm (Tenebrio molitor L.) powders processed by pulsed electric field and convective drying

Edible insects offer opportunities for food production, as they are an interesting source of many nutrients. In this study, the effect of pulsed electric field (PEF) and convective drying on the chemical composition with emphasizing the fat properties as well as physical, techno-functional, and thermal properties of yellow mealworm powders was investigated. The chemical composition of the yellow mealworm powders differed by PEF. When PEF was applied at 20 and 40 kJ/kg, the moisture, ash, and protein content were significantly lower, while the fat extraction yield significantly increased compared to the control sample. Furthermore, the fat extracted from these samples was characterized by a higher proportion of saturated and monounsaturated fatty acids as well as a higher thrombogenicity index, which is not beneficial from a nutritional point of view. After treatment with PEF at 5 kJ/kg, the powder was the lightest, redness and yellowness. Moreover, the highest hygroscopicity, water activity, and water and oil binding capacity for this powder were determined. The results revealed that yellow mealworm powders are a good source of macronutrients and exhibit beneficial techno-functional properties, nevertheless, the drawback is their high cohesiveness (1.27–1.44), which can be difficult to apply under industrial conditions.

Improving the solid–liquid phase transition of low energy-consuming biphasic solvent through the introduction of H2O

Non-aqueous biphasic absorbents have excellent energy-saving features in capturing CO2. However, the high hygroscopicity of chemical absorbents and the moisture content in flue gas can alter the moisture content of absorbents, thereby affecting their carbon capture performance and stability. In this research, an absorbent for solid–liquid phase transition composed of N-Aminoethylpiperazine (AEP) and dimethyl sulfoxide (DMSO) was developed. The influence of H2O content on CO2 capture capacity and phase transition behavior was explored. The introduction of H2O could not only reduce the viscosity to achieve fast CO2 capture and large CO2 absorption capacity (1.05 mol·mol−1) but also generate dispersed solid particles, allowing for quick sedimentation of the solids, thus enhancing the rate of phase separation. The desorption efficiency of this biphasic solvent was maintained above 83 % after four cycles. It could be desorbed in the middle stage of absorption without waiting for absorption saturation, greatly saving time and cost. Finally, the principle of the CO2 absorption process in this system and the regulatory effect of H2O on the solid–liquid phase were studied through characterization and quantum calculation.

New Beauveria bassiana aerial conidia-based bioinsecticide obtained by spray-dried microencapsulation of the entomopathogenic fungi in biopolymers for crop protection

BackgroundDue to their environmentally friendly character, entomopathogenic fungi (EPF) are becoming increasingly used as microbial agents in biological pest control over chemical pesticides. However, EPF are sensitive to the influence of abiotic factors, such as temperature, radiation, and humidity. To improve their efficiency as bioinsecticides, in this work, the development of a new microparticles-based formulation loading EPF conidia (B. bassiana aerial conidia) into sodium alginate/maltodextrin microparticles obtained by spray-drying was proposed. Different concentrations of both polysaccharides were tested to reach the optimal ratio and ensure a high viability of encapsulated conidia.ResultsAll the produced formulations showed a moisture content < 10% and water activity (aw) < 0.4. Microparticles obtained with 2% sodium alginate and 8% maltodextrin were able to retain 89.5% of the viability of encapsulated conidia, thus being selected for further characterization. Scanning electron microscopy showed microparticles with a smooth surface, varied sizes, and irregular morphology. Microparticles retained 5.44 × 108 conidia/g, presented high hygroscopicity and high suspensibility rate, yet low wettability and water activity (aw) of 0.33. The pH value ranged from 6.46 to 6.62. Microparticles were able to complete release the loaded conidia after 30 min, under constant stirring. When exposed to thermal stress (45 °C), microparticles promoted thermal protection to conidia. Enhanced pathogenicity of B. bassiana conidia against P. xylostella was also confirmed achieving 83.1 ± 5.5%, whereas non-encapsulated conidia reached only 64.8 ± 9.9%.ConclusionsThis study confirms that the encapsulation of B. bassiana fungus conidia in sodium alginate/maltodextrin microparticles by spray-drying is a promising technological approach for the biological control of agricultural pests.

Design strategy of super tough hydrophobic bamboo framework composites with internal network entanglement reinforcing structure

The low strength and high hygroscopicity of natural bamboo limit its use in structural building materials. Herein, lignin and hemicellulose were partially removed from natural bamboo in order to create bamboo frameworks featuring well-aligned bamboo fibers. Subsequently, these bamboo frameworks (BF) are infused with epoxy resin (EP) modified with PDMS and subjected to hot-pressing to fabricate bamboo-epoxy composites (PDMS-EP/BF). The incorporation of flexible PDMS chains facilitated intermolecular chain entanglement, which inhibited crack propagation and improved the bonding between bamboo and EP. The findings of the research indicated that the PDMS-EP/BF composites exhibited a significant enhancement in flexural strength by 98%, modulus of elasticity by 129%, toughness by 399%, and tensile strength by 177% when compared to natural bamboo. Additionally, the modification led to a decrease in the surface energy of the composites, resulting in increased hydrostatic contact angle and imparting water repellency to the material. Compared to natural bamboo, PDMS-EP/BF has 309% higher water contact angle and 143% lower surface energy. In addition, large composites have been prepared and their interface strength was tested. The findings of the study offer insights into the potential enhancement of bamboo composites to achieve increased flexural strength, modulus, and toughness. This could expand the utilization and significance of bamboo in the realm of construction materials.

Application of functional compounds from agro-industrial residues of Brazilian's tropical fruits extracted by sustainable methods in alginate-chitosan microparticles

The extraction and encapsulation of bioactive compounds have emerged as promising strategies to enhance their utility in various industrial applications. This study explores functional compounds derived from tropical fruit waste, including grape pomace, jabuticaba, and dragon fruit. These compounds were extracted using sustainable methods such as ultrasound-assisted extraction, maceration, and pressurized liquid extraction for incorporation into alginate and chitosan microparticles. Among the extraction methods employed, pressurized liquid extraction demonstrated the highest efficiency in recovering phenolic compounds, anthocyanins, and betalains. The optimized microparticles were tailored to specific fruit sources, with chitosan concentrations of 0.19%, 0.27%, and 0.34%, and alginate concentrations of 2.26%, 1.79%, and 1.73% for grape pomace, dragon fruit husk, and jabuticaba peel, respectively. These microparticles exhibited encapsulation efficiencies ranging from 98.43% to 99.78%. Furthermore, they displayed low solubility (0.23%–0.39%) and high hygroscopicity (38.92%–41.01%). In vitro gastrointestinal digestibility tests showed that the bioaccessibility of the phenolic compounds reached up to 95%. This finding suggests that the encapsulated bioactive compounds remain highly bioavailable, making them potentially valuable in the development of pharmaceutical and health products as well as functional foods. In conclusion, this research underscores the significance of valorizing tropical fruit by-products in Brazil through pressurized liquid extraction, followed by their efficient encapsulation within alginate and chitosan matrices. This process not only reduces waste but also opens up exciting avenues for applications in the food and pharmaceutical sectors.

Rice protein hydrolysates as natural emulsifiers for an effective microencapsulation of orange essential oil by spray drying

This study aimed to identify the influence of rice protein hydrolysates (RPH) (degree of hydrolysis DH of 2, 6, and 10%) and rice protein isolate (RPI) on the formation and stabilization of the volatile oil droplets and to verify how protein hydrolysate affects the distribution of components on the surface and physicochemical properties of the spray-dried microparticles. In general, RPHs could reduce the interfacial tension (3.78–4.04 mN/m) compared to non-hydrolyzed protein (4.74 mN/m). However, no significant difference was observed between RPH samples. A positive correlation was observed between the interfacial tension and the oil droplet size, in which RPH emulsions showed 8.29–8.66 µm while RPI was 9.06 µm. DH influenced the surface composition of the spray-dried RPH emulsions. RPH10 powder showed a greater presence of protein (3.3%) on the particle surface and consequently exhibited high oil retention (50.0%). In contrast, this sample presented high hygroscopicity attributed to the protein surface. This study provides insights into differences between RPH powders, which can potentially impact the powder functionality and protection of the active compound.

A novel diamond-like carbon based photocathode for PICOSEC Micromegas detectors

The PICOSEC Micromegas (MM) detector is a precise timing gaseous detector based on a MM detector operating in a two-stage amplification mode and a Cherenkov radiator. Prototypes equipped with cesium iodide (CsI) photocathodes have shown promising time resolutions as precise as 24 picoseconds (ps) for Minimum Ionizing Particles. However, due to the high hygroscopicity and susceptibility to ion bombardment of the CsI photocathodes, alternative photocathode materials are needed to improve the robustness of PICOSEC MM. Diamond-like Carbon (DLC) film have been introduced as a novel robust photocathode material, which have shown promising results. A batch of DLC photocathodes with different thicknesses were produced and evaluated using ultraviolet light. The quantum efficiency measurements indicate that the optimized thickness of the DLC photocathode is approximately 3 nm. Furthermore, DLC photocathodes show good resistance to ion bombardment in aging test compared to the CsI photocathode. Finally, a PICOSEC MM prototype equipped with DLC photocathodes was tested in muon beams. A time resolution of around 42 ps with a detection efficiency of 97% for 150 GeV/c muons were obtained. These results indicate the great potential of DLC as a photocathode for the PICOSEC MM detector.

Preparation of Hollow Silica Nanoparticles with Polyacrylic Acid and Their Moisture Sorption Properties

Hollow silica nanoparticles (HSNPs) have hygroscopic properties because of their high specific surface area and surface hydroxyl groups. However, compared with other hygroscopic materials, their hygroscopic properties are relatively weak, which limits the further application of HSNPs. One feasible method to enhance their hygroscopic properties is by combining highly hygroscopic materials with hollow silica nanoparticles. To take advantage of the high hygroscopicity of polyacrylic acid (PAA) when combined with the high specific surface area of the hollow particles, PAA was coated on the inner and outer surfaces of the silica shell of the nanoparticles in this study to prepare hollow nanoparticles with a PAA/silica/PAA multilayer structure. The size of the PAA/silica/PAA multi-layer nanoparticles is about 85 nm, and the shell thickness is 25 nm. The specific surface area of the multi-layer nanoparticles is 58 m2/g. The water vapor adsorption capacity of multi-layer structure hollow nanoparticles was increased by 160% compared with the HSNPs (increased from 45.9 cm3/m2 to 109.1 cm3/m2). Meanwhile, at the same content of PAA, the PAA/silica/PAA-structured particles will adsorb 9% more water vapor than the PAA/silica-structured particles. This indicates that the high specific surface area structure of the hollow particles will enhance the adsorption ability of PAA toward water vapor. This novel structure of PAA-HSNPs is expected to be used as a humidity-regulating material for filler in environmental and architectural applications.

Green Synthesis of Polyurethane Sponge-Grafted Calcium Alginate with Carbon Ink Aerogel with High Water Vapor Harvesting Capacity for Solar-Driven All-Weather Atmospheric Water Harvesting.

Atmospheric water harvesting (AWH) technology is a new strategy for alleviating freshwater scarcity. Adsorbent materials with high hygroscopicity and high photothermal conversion efficiency are the key to AWH technology. Hence, in this study, a simple and large-scale preparation for a hygroscopic compound of polyurethane (PU) sponge-grafted calcium alginate (CA) with carbon ink (SCAC) was developed. The PU sponge in the SCAC aerogel acts as a substrate, CA as a moisture adsorber, and carbon ink as a light adsorber. The SCAC aerogel exhibits excellent water absorption of 0.555-1.40 g·g-1 within a wide range of relative humidity (40-80%) at 25 °C. The SCAC aerogel could release adsorbed water driven by solar energy, and more than 92.17% of the adsorbed water could be rapidly released over a wide solar intensity range of 1.0-2.0 sun. In an outdoor experiment, 57.517 g of SCAC was able to collect 32.8 g of clean water in 6 h, and the water quality meets the drinking water standards set by the World Health Organization. This study suggests a new approach to design promising AWH materials and infers the potential practical application of SCAC aerogel-based adsorbents.

A Highly Hygroscopic, Weakly Adsorbable, and Peroxide Scavenging Ionomer for Low‐Pt Proton Exchange Membrane Fuel Cells

AbstractAn ionomer strategy is introduced to deal with two major performance‐limiting issues for the proton exchange membrane fuel cells (PEMFCs) operating under low platinum (Pt) and low humidity. Specifically, the highly hydrophilic multiple‐valence Anderson‐type polyoxometalate (POM) cluster, [MnMo6O18(OH)6]3−, is chosen to covalently graft the perfluorinated polymer, substituting for sulfonate groups as proton carriers in perfluorosulfonic acid (PFSA). The structural and electrochemical characterizations indicate that this POM cluster, with large size, charges delocalization among multiple terminal oxygen atoms, and high hygroscopicity, can prevent the ionomer adsorption, which is believed to induce dense backbone crystallization to hinder O2 permeation at Pt/PFSA interface, and lead to ionomer assemblies with large and well‐connected hydrophilic domains, which are recognized as the channels for efficient oxygen transport as well as proton conduction. Besides, the involvement of redox Mn ions in POM clusters makes the ionomer have capability to scavenge peroxides, which are known as the major chemical agents to degrade the MEA components. Consequently, fuel‐cell cathodes using the POM‐grafted ionomers exhibit significantly lower local O2 transport resistance and higher proton conductivity as compared with the PFSA‐based electrodes; and accordingly, the fuel cells exhibit much‐increased output performance at 50% relative humidity and impressive performance stability.

Preparation of ADN-based energetic composite microspheres with excellent anti-moisture absorption and safety

Ammonium dinitramide (ADN) is an ideal solid composite propellant oxidizer. But it also exhibits high hygroscopicity and low safety. Solving these issues will be crucial of ADN in practical applications. In this study, three ADN-based energetic composite microspheres were prepared by suspension assembly process coating ADN with different polymeric materials (glycidyl azide polymer (GAP), fluorine rubber(F2602), and hydroxyl-terminated block copolyether(HTPE)). The experimental results showed that the three prepared samples were spherical particles with regular morphology and uniform particle size. The crystal structure was not changed. The contact angle, moisture absorption and mechanical sensitivity test showed that the ADN-based energetic composite microspheres have low moisture absorption and mechanical sensitivity. In particular, the ADN/F2602 sample, which possesses a lotus-like hydrophobic effect, exhibits a 57.24 % reduction in water absorption compared to the raw ADN, and the contact angle of ADN/F2602 (93.91°) is 4.24 times higher than that of the raw ADN (22.15°). The critical friction susceptibility of ADN/F2602 (168 N) is 2.1 times higher than that of raw ADN (80 N), and the critical impact susceptibility of ADN/F2602 (17 J) is 2.43 times higher than that of raw ADN (7 J). The combustion test showed that the combustion duration of ADN/F2602 increased from 1.353 s to 1.578 s for the raw ADN, and the flame intensity was enhanced. The successful ignition and flame stabilization of ADN/F2602 samples after 24 h storage under a relative humidity of 60 % indicates its good energy release performance in a propellant. Through this study, F2602 as a capping material has good anti-hygroscopic effect, mechanical insensitivity and combustion stability for ADN, which can support the application of ADN as an oxidizer in composite solid propellants.

Design of an antioxidant powder additive based on carvacrol encapsulated into a multilayer chitosan-alginate-maltodextrin emulsion

Carvacrol has demonstrated antioxidant activity; however, its high volatility and low water solubility limit its direct application in food matrices. Then, an effective encapsulation system is required to protect it. This study aimed to design and characterize a carvacrol-based additive encapsulated in a spray-dried multilayer emulsion based on chitosan/sodium alginate/maltodextrin. Spray-drying temperature of 120 °C and 3 %(w/w) maltodextrin content maximized both encapsulation efficiency (~97 %) and loading capacity (~53 %). The powder's antioxidant properties were evaluated in two food simulant media: water (SiW) and water-ethanol (SiD). The highest antioxidant activity was observed in SiW for both ABTS•+ (8.2 ± 0.3mgEAG/g) and FRAP (4.1 ± 0.2mgEAG/g) methods because of the reduced release of carvacrol in SiD vs. SiW, as supported by micro- and macrostructural observations by SAXS and microscopy, respectively. An increase from 143 to 157 °C attributable to carvacrol protection and Tg = 44.4 °C (> ambient) were obtained by TGA and DSC, respectively. FT-IR confirmed intermolecular interactions (e.g. -COO− and -NH3+) as well as H-bonding formation. High water solubility (81 ± 3 %), low hygroscopicity (8.8 ± 0.2 %(w/w), poor flowability (CI:45 ± 4), and high cohesiveness (HR:1.8 ± 0.1) between particles were achieved, leading to a powdered antioxidant additive with high potential for applications which required avoiding/reducing oxidation on hydrophilic and hydrophobic food products.

Synthesis of linear polyesters bearing amino groups via lipase-catalyzed polymerization of N-protected monomer and deprotection

Linear biodegradable polyesters with a controlled number of side chains of amino groups have been synthesized. Such polyesters with a large number of amino side groups can be conjugated with a wide variety of functional molecules to obtain multi-functional biodegradable polyesters. In this study, poly(1,3-propylene-co-2-amino-1,3-propylene) adipate) (P(P-co-AP)A) was synthesized by enzymatic polymerization of divinyl adipate, 1,3-propanediol, and N-Boc-2-amino-1,3-propanediol (BocAPDO), and subsequent deprotection under strong acidic conditions. The mild reaction conditions and the specificity of the enzymatic polymerization could effectively inhibit side reactions, while the protecting groups of the monomers prevented polymer branching from the amino groups. It was found that the introduction rates of BocAPDO in the polymers could be well-controlled as the feeding rates changed from 0 to 100 mol%. After the deprotection and desalting, the ester groups in the main chain gradually converted into amide groups by intramolecular ester aminolysis at room temperature for a few days due to nucleophilic free amino groups. It was also found that the synthesized functional copolymers were all amorphous, since the random component of amino groups disrupted the crystallinity of poly(1,3-propylene adipate) (PPA). The glass transition temperature gradually increased with the increase in the content of 2-amino-1,3-propylene adipate (APA), eventually reaching −0.4 °C at the APA content of 100 mol% due to the intermolecular hydrogen bonding. Moreover, P(P-co-AP)A shows high hygroscopicity, where 3.9 wt% and 8.1 wt% of water were absorbed in the polymers with the APA contents of 50 and 100 mol%, respectively, when left in air at 60–70 % humidity for 6 h. Thus, the hydrophilicity dramatically improved with the increase in the APA content, eventually resulting in the acquisition of water solubility. The model post-polymerization modification using butyric acid was also conducted, and it was confirmed that carboxylic acids could be conjugated to the polymers by simple condensation reaction. Since polymerization of functional monomers is generally susceptible to the polarity of metal catalysts, the mild and selective reaction employed in this study could realize a higher content of various functional groups in the side chains of polyesters leading to a newly designed multi-functional polyester.

Hygroscopic paper enhanced using hydroxyapatite coating for wearable TENG sensors

Wearable triboelectric nanogenerators (TENGs) have attracted considerable attention in the field of self-powered sensors that can be worn on the skin directly without packaging because of their breathability, conformability, and sensitivity to collect biomechanical energy. However, high humidity on the skin can affect the wearable TENG output performance, substantially affecting the sensor performance and stability. When worn for a long time, humidity can even cause skin inflammation. Thus, for a wearable TENG, moisture control and biocompatibility are also key factors that need to be addressed. Herein, we report a hygroscopic and biocompatible paper-based TENG using a hydroxyapatite (HAP) mineral coating to enhance the paper fiber. The mineral coating can maintain the surface of the paper fiber, which will not cause large external deformation of the paper fiber under a force, avoid squeezing out excess water, and keep the friction surface dry, avoiding humidity affecting the output performance. Without interfering with the performance of the TENG, the maximum water absorption of the HAP composite paper is ∼8 μL. The HAP composite paper–based TENG (4 cm2) has an open-circuit voltage and short-circuit current 5.8 times and 4.2 times that of pure paper, respectively, and can obtain 80.4 mW/m2 output and directly light 117 LEDs. At relative humidity values of 25.7 %, 43.1 %, and 58.8 %, the performance retained the peak values of 80.2 %, 68 %, and 63.7 %, respectively. Even at a high relative humidity of 71.7 %, the triboelectric performance of HAP composite paper is retained 59.3 %, and the stability under humidity is better than that of pure paper (45.6 %). In addition, the mineral paper can even work with tissue fluid and output performance decreases by 43.8 %. The mineral-enhanced paper TENG with high power generation performance, hygroscopicity, biocompatibility, and degradability provides a new perspective for disposable wearable sensors, even in medical treatment.

Impact of Anthropogenic Aerosol Transport on Cloud Condensation Nuclei Activity During Summertime in Qilian Mountain, in the Northern Tibetan Plateau

AbstractIn this study, we conducted field campaigns at two mountain‐top observatories on the Qilian Mountains (QLM) in the northeastern Tibetan Plateau of China, which plays a vital role in sustaining water resources for the downstream arid and semi‐arid regions. The two observatories, Waliguan Baseline Observatory (WLG) and Laohugou station (LHG), are situated on the eastern and western edge of the QLM, respectively. The objectives of this study were to examine the properties of atmospheric aerosols, CCN concentrations (NCCN) at varying supersaturation levels (SS = 0.2%–1.0%), and the hygroscopic nature of aerosols in the QLM, especially during the formation of orographic cloud. Notably, the average aerosol concentration and NCCN was approximately 2–3 factors higher at WLG compared to LHG. The chemical compositions of aerosols were primarily dominated by sulfate and organic aerosol (OA) at these two sites. A very high hygroscopicity parameter of aerosol calculated using chemical composition was observed at these two sites (0.37 ± 0.03 at LHG vs. 0.30 ± 0.04 at WLG). Enhanced aerosol loading episodes impacted by anthropogenic emission were observed at these two sites. Exploration on high‐loading cases at each site, we found that the CCN activity was dominated by aerosol size, but the chemical processes of aerosol during the formation of orographic cloud could also be important in CCN activity, especially for low SS conditions. These findings collectively underscore the significant impact of anthropogenic air plumes on CCN concentrations in the QLM and their potential influence on precipitation patterns.