Search Results (14)

Background: Dark-base hair fibers with Curl Pattern (CP) types 2 and 3 from Asian and European populations, respectively, are very similar, although each presents different behaviors regarding water diffusion and cosmetic treatments, including in relation to dyeing. This study aims to identify the key drivers of water diffusion in hair, particularly the role of lipids in the diffusion processes. Methods: Virgin, externally delipidized, and internally delipidized CP2 and CP3 hair strands were subjected to Dynamic Vapor Sorption (DVS) and ATR-FTIR investigations. In addition, external and internal lipid extracts were quantified and analyzed via thin-layer chromatography–flame ionization detection (TLC/FID). Results: The results obtained indicate that CP2 hairs present lower water regain at all humidity steps and a different diffusion behavior depending on the humidity. Lower diffusion was obtained at low humidity and higher diffusion at high humidity. TLC/FID analyses indicate that CP2 fibers present a significantly higher amount of external lipids (1.4% vs. 0.4%) and internal lipids (3.2% vs. 2.6%) as compared with the CP3 fibers. Conclusions: The higher amount of internal lipids is mainly due to the greater amount of polar lipids (ceramides). Lipid extraction tends to modify the water content, leading to a more hydrated and less permeable lipid-depleted fiber. The similar water properties of the two types of lipid fiber support the fundamental role of lipids, even when present in small quantities, in the differentiation of hair types. This study highlights a potential link between the lipid composition of CP3 and CP2 hair fibers and their differences in behaviors regarding water diffusion, which could also explain varying responses to cosmetic treatments. Full article

Brine purification is an important process unit in chlor-alkali industrial plants for the production of sodium hydroxide, chlorine, and hydrogen. The membrane cell process requires ultrapure brine, which is obtained through mechanical filtration, chemical precipitation and fine polishing, and ion exchange using polymer resins. Temperature variations can lead to the degradation of the exchange properties of these resins, primarily causing a decrease in their exchange capacity, which negatively impacts the efficiency of the brine purification. After multiple ion exchange regeneration cycles, significant quantities of spent resins may be generated. These must be managed in accordance with resource efficiency and hazardous waste management to ensure the sustainability of the industrial process. In this paper, a comparative study is conducted to characterize the long-term stability of a new commercial chelating resin used in the industrial electrolysis process. The spectroscopic methods of physicochemical characterization included: scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX) and attenuated total reflectance–Fourier transform infrared spectroscopy (ATR-FTIR). The thermal behavior of the polymer resins was evaluated using the following thermogravimetric methods: thermogravimetry (TG), derivative thermogravimetry (DTG), and differential thermal analysis (DTA), while the moisture behavior was studied using dynamic vapor sorption (DVS) analysis. To assess the energy potential, the polymer resins were analyzed to determine their calorific value and overall energy content. Full article

Polymeric scaffolds are promising in tissue engineering due to their structural similarity to extracellular matrix components. This study aimed to design freeze-dried hydrogels based on chitosan (CHT) and hyaluronic acid (HA). Chitosan-based gels were crosslinked with oxidized maltodextrin (MDo) before the freeze-drying step, resulting in spongy porous scaffolds. Based on the state-of-the-art, our hypothesis was that crosslinking would increase scaffold stiffness and delay the degradation of the CHT:HA resorbable scaffolds swelled in a hydrated physiological environment. The physicochemical and mechanical properties of crosslinked CHT- and CHT:HA-based scaffolds were analyzed. Hygroscopic and swelling behavior were assessed using dynamic vapor sorption analysis and batch studies. Degradation was evaluated under different conditions, including in phosphate-buffered saline (PBS), PBS with lysozyme, and lactic acid solutions, to investigate scaffold resistance against enzymatic and acidic degradation. The porosity of the spongy materials was characterized using scanning electron microscopy, while dynamic mechanical analysis provided information on the mechanical properties. Crosslinked scaffolds showed reduced swelling, slower degradation rates, and increased stiffness, confirming MDo as an effective crosslinking agent. Scaffolds loaded with ciprofloxacin (CFX) demonstrated their ability to deliver therapeutic agents, as the CFX loading capacity was promoted by CHT–CFX interactions. Microbiologic investigation confirmed the results. Finally, cytotoxicity tests displayed no toxicity. In conclusion, MDo-crosslinked CHT and CHT:HA scaffolds exhibit enhanced stability, functionality, and mechanical performance, making them promising for cartilage tissue engineering. Full article

The morphology of wheat starch granules with different damaged starch (DS) content was analyzed using a particle size analyzer and scanning electron microscopy (SEM); the granular structure was studied using FT-IR spectroscopy and X-ray diffraction (XRD); and the granule–water interaction was evaluated by thermogravimetric analysis (TGA) and dynamic vapor sorption (DVS). The increase in the level of DS shifted the population of B-type granules towards larger particle diameters and shifted the population of A-type granules towards smaller particle diameters. The appearance of the surface of the starch-damaged granules was rough and flaky (SEM images). Crystallinity reductions were related to higher mechanical damage levels of the granular structure (FT-IR and XRD). Higher DS increased the liquid-water absorption capacity of the granules. Higher DS was associated with increments in less-bound water proportions and reductions in more strongly bound water proportions and related to reductions in the evaporation temperature of these water populations (TGA analyses). Concerning DVS data, the results suggested that the driving force for water–monolayer attachment to the starch granules decreased as DS increased. Therefore, it was suggested that the changes in granule structure led to a weaker water–starch polymer chain interactions due to the increase in DS. The results contribute to a better understanding of the influence of mechanical damage on the starch granular structure, which could be related to the rheological and thermal behavior of starch-based systems with different DS. Full article

Metal–organic frameworks (MOFs) are hybrid inorganic–organic 3D coordination polymers with metal sites and organic linkers, which are a “hot” topic in the research of sorption, separations, catalysis, sensing, and environmental remediation. In this study, we explore the molecular mechanism and kinetics of interaction of the new copper porphyrin aluminum metal–organic framework (actAl-MOF-TCPPCu) compound 4 with a vapor of the volatile organic sulfur compound (VOSC) diethyl sulfide (DES). First, compound 4 was synthesized by post-synthetic modification (PSM) of Al-MOF-TCPPH₂ compound 2 by inserting Cu²⁺ ions into the porphyrin ring and characterized by complementary qualitative and quantitative chemical, structural, and spectroscopic analysis. Second, the interaction of compound 4 with DES vapor was analyzed dynamically by the novel method of in situ time-dependent attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy at controlled humidity levels. The sorbent–adsorbate interactions, as analyzed by the shifts in IR peaks, indicate that the bonding includes the hydroxy O-H, carboxylate COO⁻, and phenyl groups. The kinetics of sorption obeys the Langmuir pseudo-first-order rate law. The pre-adsorption of water vapor by compound 4 at the controlled relative humidity under static (equilibrium) conditions yields the binary stoichiometric adsorption complex (Al-MOF-TCPPCu)_1.0(H₂O)_8.0. The pre-adsorption of water vapor makes the subsequent sorption of DES slower, while the kinetics obey the same rate law. Then, static pre-adsorption of water vapor was followed by static sorption of DES vapor, and the ternary adsorption complex (Al-MOF-TCPPCu)_1.0(H₂O)_8.0(DES)₃.₈ was obtained. Despite the pre-adsorption of significant amounts of water, the binary complex adsorbs a large amount of DES: ca. 36.6 wt. % (per compound 4). Finally, the ternary complex is facilely regenerated by gentle heating under vacuum. Compound 4 and related MOFs are promising for adsorptive removal of vapor of DES and related VOSCs from dry and humid air. Full article

Palm leaf manuscripts are a valuable part of world cultural heritage. Studying the mechanical properties of palm leaf manuscripts and their changes due to environmental influences is of great significance for understanding the material characteristics, aging mechanisms, and preventive conservation of these manuscripts. This study used dynamic vapor sorption (DVS) and a thermomechanical analyzer (TMA) to investigate the changes to the mechanical properties of palm leaf manuscripts in response to different relative humidity conditions and different time periods. The short-term study results show that exposure to varying relative humidities leads to changes in the equilibrium moisture content (EMC) of palm leaf manuscripts, causing the bending strength of the samples to decrease significantly with increasing humidity. The bending modulus initially increases and then decreases as the humidity increases. Moreover, the greater the desorption hysteresis of the samples, the more pronounced the changes to the mechanical properties. Therefore, a stable environment in terms of humidity can prevent changes in the mechanical properties of palm leaf manuscripts, thereby preventing the onset of degradation. The results of the long-term aging studies indicate that prolonged exposure to either very dry or very humid conditions greatly affects the mechanical properties of palm leaf manuscripts, which is detrimental to their preservation. The samples kept at 50% RH did not exhibit significant signs of deterioration, with no notable changes in their mechanical properties or chemical structure. This suggests that 50% RH is a relatively optimal humidity condition for the preservation of palm leaf manuscripts. Full article

Chinese fir (Cunninghamia lanceolata [Lamb.] Hook.) is a widely planted species of plantation forest in China, and heat treatment can improve its dimensional stability defects and improve its performance. The wood samples were heat-treated at various temperatures (160, 180, 200, and 220 °C) for 2 h. To clarify the effect of heat treatment on wood hygroscopicity, the equilibrium moisture content (EMC) was measured, the moisture adsorption and desorption rates were determined, the hygroscopic hysteresis was examined, and the Guggenheim, Anderson, and de Boer (GAB) model was fitted to the experimental data. The moisture absorption isotherms of all samples belonged to the Type II adsorption isotherm, but the shape of the desorption isotherm was more linear for heat-treated wood samples, especially when the heat treatment temperature was higher. According to the results analyzed with ANOVA, there were significant differences in equilibrium moisture content between the control samples and the heat-treated samples under the conditions of 30%, 60%, and 95% relative humidity (RH, p < 0.05), and the results of multiple comparisons were similar. The decrease in hygroscopicity was more pronounced in wood treated at higher temperatures. The EMC of the 160–220 °C heat-treated samples of the control samples was 14.00%, 22.37%, 28.95%, and 39.63% lower than that of the control sample at 95% RH. Under low RH conditions (30%), water is taken up mainly via monolayer sorption, and multilayer sorption gradually predominates over monolayer sorption with the increase in RH. The dynamic vapor sorption (DVS) analysis indicated that the heat-treated wood revealed an increase in isotherm hysteresis, which was due to the change in cell wall chemical components and microstructure caused by heat treatment. In addition, the effective specific surface area of wood samples decreased significantly after heat treatment, and the change trend was similar to that of equilibrium moisture content. Full article

The excellent biological properties of chitosan (CS) together with the increased oxygen permeability of polyvinyl alcohol (PVA) were the prerequisites for the creation of a wound healing dressing that would also function as a system for L-arginine (L-arg) and caffeine (Caff) delivery. Using the freezing/thawing method, 12 hydrogels were obtained in PVA:CS polymer ratios of 90:10, 75:25, and 60:40, and all were loaded with L-arg, Caff, and the mixture of L-arg and Caff, respectively. Afterwards, an inorganic material (zeolite–Z) was added to the best polymeric ratio (75:25) and loaded with active substances. The interactions between the constituents of the hydrogels were analyzed by FTIR spectroscopy, the uniformity of the network was highlighted by the SEM technique, and the dynamic water vapor sorption capacity was evaluated. In the presence of the inorganic material, the release profile of the active substances is delayed, and in vitro permeation kinetics proves that the equilibrium state is not reached even after four hours. The synergy of the constituents in the polymer network recommends that they be used in medical applications, such as wound healing dressings. Full article

This study experimentally and numerically investigates the hygrothermal behavior of a wall made of washing fines hemp composite under typical French and Tunisian summer climates. Actually, insulating bio-based building materials are designed in order to reduce energy and non-renewable resources consumptions. Once their multiphysical properties are characterized at material scale, it is necessary to investigate their behavior at wall scale. Washing fines hemp composite shows low thermal conductivity and high moisture buffer ability. The test wall is implemented as separating wall of a bi-climatic device, which allows simulating indoor and outdoor climates. The numerical simulations are performed with WUFI Pro 6.5 Software. The results are analyzed from the temperature, relative humidity and vapor pressure kinetics and profiles and from heat and moisture transfer and storage. The thermal conductive resistance calculated at the end of the stabilization phase is consistent with the theoretical one. The hygric resistance is consistent for simulation up to steady state. The dynamic phase under daily cyclic variation shows that for such cycles two thirds of the thickness of the wall on the exterior side are active. It also highlights sorption-desorption phenomena in the wall. Full article

The use of agricultural by-products in the building engineering realm has led to an increase in insulation characteristics of biobased materials and a decrease in environmental impact. The understanding of cell wall structure is possible by the study of interactions of chemical compounds, themselves determined by common techniques like Van Soest (VS). In this study, a global method is investigated to characterise the cell wall of hemp shiv. The cell wall molecules were, at first, isolated by fractionation of biomass and then analysed by physical and chemical analysis (Thermal Gravimetric Analysis, Elementary Analysis, Dynamic Sorption Vapor and Infra-Red). This global method is an experimental way to characterise plant cell wall molecules of fractions by Thermal Gravimetric Analysis following by a mathematical method to have a detailed estimation of the cell wall composition and the interactions between plant macromolecules. The analyzed hemp shiv presents proportions of 2.5 ± 0.6% of water, 4.4 ± 0.2% of pectins, 42.6 ± 1.0% (Hemicellulose–Cellulose), 18.4 ± 1.6% (Cellulose–Hemicellulose), 29.0 ± 0.8% (Lignin–Cellulose) and 2.0 ± 0.4% of linked lignin. Full article

Salt formation is a useful technique for improving the solubility of active pharmaceutical ingredients (APIs). For instance, a nonsteroidal anti-inflammatory drug, diclofenac (DIC), is used in a sodium salt form, and it has been reported to form several hydrate forms. However, the crystal structure of the anhydrous form of diclofenac sodium (DIC-Na) and the structural relationship among the anhydrate and hydrated forms have not yet been revealed. In this study, DIC-Na anhydrate was analyzed using single-crystal X-ray diffraction (XRD). To determine the solid-state dehydration/hydration mechanism of DIC-Na hydrates based on both the present and previously reported crystal structures (4.75-hydrate and 3.5-hydrate), additional experiments including simultaneous powder XRD and differential scanning calorimetry, thermogravimetry, dynamic vapor sorption measurements, and a comparison of the crystal structures were performed. The dehydration of the 4.75-hydrate form was found to occur in two steps. During the first step, only water molecules that were not coordinated to Na⁺ ions were lost, which led to the formation of the 3.5-hydrate while retaining alternating layered structures. The subsequent dehydration step into the anhydrous phase accompanied a substantial structural reconstruction. This study elucidated the complete landscape of the dehydration/hydration transformation of DIC-Na for the first time through a crystal structure investigation. These findings contribute to understanding the mechanism underlying these dehydration/hydration phenomena and the physicochemical properties of pharmaceutical crystals. Full article

The article presents experimental results of the metal-based and carbon nanotube additives influence on sorption kinetics of a silica-gel-based adsorption bed in an adsorption chiller. The purpose of the doping is to improve the efficiency of sorption processes within the bed by use of metallic and non-metallic additives characterized by higher thermal diffusivity than basic adsorption material. The higher the thermal conductivity of the bed, the faster the sorption processes take place, which directly translates into greater efficiency of the refrigerator. In this study, sorption kinetics of pure silica gel sorbent doped with a given amount of aluminum (Al) and copper (Cu) powders and carbon nanotubes (CNT) were analyzed. The tests were performed on DVS Dynamic Gravimetric Vapor Sorption System apparatus used for dynamic vapor sorption measurements. A decrease in the amount of adsorbed water was observed with an increase in the mass share of the additives in the performed studies. Experimental results show that, CNTs seems to be the most promising additive as the sorption process time was reduced with the smallest decrease in water uptake. Any significant reduction of adsorption time was noted in case of the Al addition. Whereas, in case of Cu doping, delamination of the mixture was observed. Full article

Replacing greenhouse gas-intensive building materials with wood products from sustainable forestry contributes to the implementation of current climate conventions such as the Paris Agreement. Hardwood products, such as laminated veneer lumber made of beech (e.g., BauBuche), are an alternative to conventional building materials. For the application of wood products in the construction sector, a precise knowledge of the mechanical and physical properties is essential. Therefore, the aim of the present study was to investigate the sorption behavior and associated dimensional changes of the product BauBuche. This was done by applying a manual testing procedure (climatic chamber, balance and caliper) as well as a dynamic vapor sorption analyzer equipped with a camera. During initial moistening after production, due to the irreversible spring back (approximately 2 mm at 50 mm; i.e., 4%), Baubuche shows an extremely strong swelling in the radial direction. Once the maximum spring back is reached, Baubuche shows sorption behavior in the radial and tangential direction, which is comparable to that of solid beech wood in the radial direction. Consequently, the dimensional changes caused by moisture changes must be taken into account in the dimensioning of Baubuche components in order to avoid damage to building structures. Full article

Water absorption capacity is a key characteristic of cellulosic pulps used for different commodities. This property is influenced by the affinity of the pulp fiber surface with water, chemical composition of the pulp, morphology, and organization of fibers in the network. In this study, surface properties of six industrial Eucalyptus bleached kraft pulps (fluff pulps) dry-defiberized in a Hammermill, which were obtained by wood pulping and pulp bleaching under different production conditions, were studied while employing dynamic water vapor sorption and contact angles measurements. The absorption properties of air-laid pulp pads were analyzed following the absorbency testing procedure and the relationship between these properties and pulp’s chemical composition and fiber network structure were assessed by multivariate analysis. The results showed that the accessibility of the fiber surface is related to the reduction of the contact angles, but, at the same time, to the longer absorption time and less absorption capacity of the fiber network. Therefore, the absorption properties of the pulps are not necessarily directly related to their surface properties. Indeed, absorptivity is related to the surface chemical composition, fiber morphology, and fiber network structure. Thus, surface carboxylic groups promote total water uptake, resulting in better absorption capacity. Greater fiber coarseness and deformations (curl and kink) provide a less wettable surface, but a more porous network with higher specific volume, resulting in more absorbent air-laid formulations. Full article