Dry State Research Articles

Generational Wanderers

After the start World War, the United States found that manpower for agricultural work was limited, and thus began to outsource its seasonal labor to migrant farm workers. Despite the hardship of moving from place to place, and American citizen's prickly acceptance of migrant families, these laborers all over the country during harvest seasons, often leaving their homes for months at a time. Drawing from the oral history of Natividad “Nati” Castillo, his families migration around the United States during the spring and summer months became a generational pilgrimage. Ultimately three generations of Castillos would follow the same migration pattern with little variation. While Nati’s personal migratory experience ends just before the Agricultural Workers Movement lead by Cesar Chavez, Nati's oral history conceptualizes the migrants necessity of agricultural labor. Nati’s family, like many others, traveled on a seasonal, migrational track that moved out of the dry southern states, to northern states with plentiful crops waiting to be harvested.

Moisture dependent bending mechanical properties of Chinese fir

ABSTRACT Predicting the long-term deformation and failure of wood under varying environmental conditions is challenging due to the complex rheological behaviour of wood. In this study, the bending failure mechanism and moisture-dependent viscoelastic creep behaviours of Chinese fir (Cunninghamia lanceolata [Lamb.] Hook.) were explored. The digital image correlation technique was used to monitor strain field changes during the bending process. The results revealed that wood in a dry state was more brittle than in a moist state. Strain field variations showed that the tensile load on the tension side primarily governs bending failure. There are distinct differences between tension and compression regions by fracture morphology analysis. The study further developed the time-moisture-stress superposition principle to integrate the effects of time, moisture, and stress on wood's creep behaviour in bending. These findings provide critical insights into how moisture affects wood’s mechanical behaviour, guiding more efficient design and manufacturing practices for long-term structural performance in the timber-construction industry.

Exploration of failure mechanisms in a novel basalt fiber-reinforced phthalonitrile composite under extreme temperature conditions

As composites become increasingly prevalent in aerospace structures, their resistance to high temperatures in extreme environments has captured the attention of numerous scholars. This paper discussed the development of a new basalt fiber-reinforced phthalonitrile matrix (BFRPN) composite, examining its mechanical performance across a spectrum of temperatures, including -55 °C low-temperature dry state (CTD), 23 °C room-temperature dry state (RTD), 250 °C, 350 °C, and 450 °C. The reliability of the mechanical properties was assessed by calculating the B-basis value. Additionally, optical and scanning electron microscope (SEM) photos were employed to analyze the damage morphology and elucidate the failure mechanisms at both high and low temperatures. The study revealed that the BFRPN composites maintained functional integrity from -55 °C to 350 °C. For representative unnotched plate tensile (UPT) and unnotched plate compression (UPC) specimens, the retention of UPT strength and UPC strength stayed above 100% and 83% respectively. At 450 °C, the retention rate of UPT strength consistently exceeds 78%, while the matrix undergoes significant oxidative decomposition, with delamination being the main observed damage mode.

Biobased hydrophobic liquid mulch film from soybean oil and starch for enhanced terraced field cultivation.

Terraced agriculture faces soil loss during rainstorms leading to natural disasters and crop growth impediments. This study describes a novel biobased hydrophobic liquid mulch film comprised of waste soybean oil, starch, and acrylate monomers that can be used to enhance terraced field cultivation. The novel film, optimized at a 3:7 soybean oil to acrylate monomers ratio, exhibited superior spray ability, reduced wicking, and excellent film formation, which are crucial for its effectiveness as a water erosion barrier. The wet state of the SOSA film demonstrated optimal impact resistance, with increased elongation at break and reduced breaking strength compared to its dry state, facilitating seedling emergence. It significantly improved soil moisture retention (4.8-5.7 %) and temperature (0.9-5.6 °C) and boosted maize seed germination by 28 %. Under extreme conditions of a 24° slope and 90 mm/h rainfall, the SOSA film achieved an 80.6 % reduction in soil loss and a 57.4 % increase in pakchoi yield over bare soil. This study's comprehensive analyses confirmed the film's formation mechanism and provided a scientific basis for its practical application performance, highlighting the film's unprecedented success in using waste materials for sustainable terrace farming and its potential as a transformative approach to soil conservation and crop productivity.

Enabling simultaneous CO2 and water vapor removal by MOF-801/Pebax mixed matrix membranes: Molecular simulation and experimental study

Dehydration and CO2 removal are two important gas separation processes. An efficient membrane enabling simultaneous reduction of water vapor and CO2 levels from humid gas streams, such as natural gas and power plant flue gas, may advance these processes. In this study, a water-harvesting metal-organic framework, MOF-801, was synthesized with an average particle size of 120 nm, which was then dispersed in a Pebax matrix to fabricate mixed matrix membranes (MMMs). The potential of the MOF-801 as a filler in MMMs was evaluated for water and CO2 separation from CO2/N2 and CO2/CH4 mixed gas streams. Compared with the neat Pebax membrane, 70% enhancement in the water permeability was achieved for an MMM of 20 wt.% MOF loading at 10 bar with a humid feed composition of CO2/CH4. A considerable CO2/N2 separation factor (108) and CO2 permeability (270 Barrer) were also obtained, exceeding the Robeson upper bound at both dry and humid states. A molecular simulation study was performed to reveal the adsorption sites in the MOF lattice and favorable interactions with gases. Interestingly, competition between gas components close to the Zr atom was observed, which is the favorable site for both CO2 and water. Competitive adsorption was found to be the dominating transport mechanism for the selective transport of CO2 and H2O in MOF-801, revealing the role of MOF-801 in MMMs for CO2 and water vapor separation under both humid and dry conditions.

Study on flexural resilience of composite foam sandwich structures under hygrothermal environment

Under hygrothermal environments, the structural stability and strength of all-fiber composite aircraft are significantly affected during long-term flight use. The wing skin, as a critical structural component, plays a vital role in bearing and transmitting aerodynamic loads. Therefore, it is crucial to investigate the structural compressive stability and strength of the wing skin throughout the aircraft's entire life cycle under these conditions. This study employs a real wing carbon fiber foam sandwich structure to investigate the compressive stability and strength of the wing skin structure of a new energy aircraft under actual flight conditions, specifically during the entire process of the room temperature dry state (RTD) and elevated temperature wet state (ETW). Initially, three-point bending tests were conducted on carbon fiber reinforced polymer (CFRP) laminates, foam cores, and CFRP reinforced foam sandwich structures. The CFRP laminates fully rebounded after bending damage in both the RTD and ETW environments. While CFRP reinforced foam sandwich structures also rebounded fully in the RTD environment, their rebound performance diminished in hygrothermal conditions due to the thermoplastic mobility of the foam cores, resulting in only weak rebound capabilities. In hygrothermal environments, the thermoplastic mobility of the foam core leads to diminished resilience after bending damage, resulting in only weak rebound capabilities. Subsequently, compressive instability tests were conducted on the wing skin foam sandwich structure. The results indicated that the basic test study effectively predicted the structural test outcomes. Structural components in the RTD environment exhibited overall flexural instability under compressive load, with damage morphology resembling a circular curve; the damaged specimens fully rebounded after unloading. Conversely, specimens in the ETW environment displayed localized instability, characterized by a wrinkled damage profile, resulting in only weak rebound capabilities after unloading.

Comparative study of physical and mechanical properties of a light plaster mortar based on the "SPADAR" foam ceramic granules and similar light fillers

Introduction. Plasters are still one of the most popular materials for finishing of facades of buildings. Modern plasters are produced mainly in the form of ready-to-use dry mixes. Manufacturers set themselves the task of obtaining not only plaster mixtures meeting standards, but also having hydrophobicity, low density, thermal conductivity and other features that determine the functionality of the plaster coating. In this regard, there is a need to develop and implement plaster mixtures based on new types of light aggregates. Aim. To conduct comparative studies of the physical and mechanical properties of a light plaster mortar using the "SPADAR" foam ceramic granules and plaster mortars with similar fillers as a light filler. Materials and methods. The research was carried out on light plaster mortars using as light fillers: "SPADAR" and foam ceramic granules from another manufacturer ("KERWOOD"), foam glass granules, expanded perlite sand. The parameters of density, strength under axial compression, water absorption during capillary suction and thermal conductivity of a light plaster mortar in a dry state were studied. The tests were carried out according to standard methods. Results. The comparative technical characteristics of the studied plaster compositions are determined. During the analysis of the data obtained, the advantages of plaster compositions using foam ceramic granules as a light filler were revealed. Based on the data obtained, the composition of a light plaster mortar with a density of up to 700 kg/m3 using the "SPADAR" foam ceramic granules was developed. Conclusions. The composition of the plaster based on the "SPADAR" foam ceramic granules turned out to be the most effective by the obtained values of the studied characteristics in total. In many ways, the obtained values of the technical characteristics of this plaster studied in this work are provided precisely by the "SPADAR" foam ceramic granules. Based on the results obtained, it is necessary to investigate other properties of the developed compositions of light plaster mixtures (adhesion, vapor permeability, moisture-proof properties with respect to the mineral base, frost resistance, etc.).

Green synthesis of starch/chitosan complex via ozone-mediated Schiff reaction: Structure, thermal behaviors and surface properties

Ozone was used as a green and environmentally friendly initiator to directly induce a Schiff base cross-linking reaction between chitosan and waxy rice starch (CS) in the present investigation. The effects of oxidation on the structure of chitosan/starch bio-based composite, along with the cross-linked structure formation via Schiff base reaction, were investigated and confirmed using FTIR, XRD, and XPS characterization techniques. The formation of new bonds (C=N) along with other attributes imparted by the cross-linking reaction were evaluated and characterized. Notably, the ozone-induced cross-linking reaction significantly altered the water retention capabilities of CS, especially in the case of aqueous ozone treatment, which significantly improved its swelling power, water holding capacities, and water adsorption. Additionally, aqueous ozone treatment facilitated the formation and stabilization of the gel network. Gaseous ozone in dry state proved more effective in promoting the formation of CN groups, leading to enhanced surface hydrophobicity, while aqueous ozone offered better oxidation uniformity for the coexistence system of chitosan and starch. This work provides a novel and environmentally friendly approach for fabricating the chitosan/starch chemically cross-linking materials through ozone-induced direct Schiff base reaction, which simplifies the preparation process of the complex and minimizing the utilization of solvents.

Modeling spider silk supercontraction as a hydration-driven solid-solid phase transition

Spider silks have attracted significant interest due to their exceptional mechanical properties, which include a unique combination of high strength, ultimate strain, and toughness. A notable characteristic of spider silk, still debated from both mechanical and functional viewpoints, is supercontraction–a pronounced contraction of up to half its original length when an unconstrained silk thread is exposed to a wet environment. We propose a predictive model for the hygro-thermo-mechanical behavior of spider silks, conceptualizing this phenomenon as a solid–solid phase transition, similar to the glass transition in rubber, but driven by humidity. As wetting increases, the system undergoes a transition, at the network scale, from a hard, highly crystalline, dry state–where the material behavior is governed by stiff chains elongated along the fiber axis–to a soft, amorphous, wet state, regulated by a rubber-like response. We model these states using a two-well free energy function dependent on molecular stretch, with transition energy modulated by humidity. Based on the methods of Statistical Mechanics, we deduce that supercontraction can be interpreted as a solid–solid phase transition. We elucidate the important role of thermal fluctuations. In particular, the decrease of the critical humidity needed for supercontraction as temperature grows results as an effect of entropic stabilization of the softer rubbery phase. Our model quantitatively predicts the observed experimental behavior, capturing the temperature dependence of humidity-induced supercontraction effects and related cooperative properties.

"The More, the Better?": The Impact of Sugar-to-Protein Molar Ratio in Freeze-Dried Monoclonal Antibody Formulations on Protein Stability.

Lyophilization is widely used to ensure the stability of protein drugs by minimizing chemical and physical degradation in the dry solid state. To this end, proteins are typically formulated with sugars that form an amorphous immobilizing matrix and stabilize hydrogen bonds replacing water molecules. The optimal amount of sugar required and protein stability at low excipient-to-protein molar ratios are not well understood. We investigated this by focusing on the physical stability of formulations, reflecting highly concentrated monoclonal antibody (mAb) lyophilizates at low sucrose to mAb ratios between 25:1 and 360:1. Additionally, the impact of different excipient types, buffer concentrations, and polysorbates was studied. The mAb stability was evaluated over up to three months at 25 and 40 °C. We investigated the "the more, the better" approach regarding excipient usage in protein formulation and the existence of a potential stabilizing threshold. Our findings show efficient monomeric content preservation even at low molar ratios, which could be explained based on the water replacement theory. We identified an exponential correlation between the sucrose to protein molar ratio and aggregate formation and found that there is no molar ratio threshold to achieve minimum stabilization. Sucrose demonstrated the best stabilization effect. Both mannitol, used as a cryoprotectant at low concentrations, and arginine reduced aggregation compared to the pure mAb formulation. The higher ionic strength of 5 mM histidine buffer enhanced protein stability compared to that of 0.1 mM histidine buffer, which was more pronounced at lower molar ratios. The addition of polysorbate 20 contributed an additional interfacial stabilizing effect, complementing the cryoprotective and lyoprotective properties of sucrose. Overall, a model could be developed to optimize the quantity of sugar required for protein stabilization and facilitate a more rational design of protein lyophilizates. The molar ratio of sugar to protein for high-concentration mAb products is limited by the acceptable tonicity, but we showed that sufficient stabilization can be achieved even at low molar ratios.

The significant influence of the sea surface temperature anomalies over North Atlantic and the Maritime Continent on maize yield in Northeast China

Northeastern China (NEC) is the largest grain base in China. Improving understanding of the effect of climate change on grain production over NEC is conducive to providing immediate response strategies for grain production. In this study, the relationships of the maize production with the dry state during the different maize growth stage have been investigated using the year-to-year increment method. Results showed that the severe drought that occurred from the jointing to maturity period have exerted severe effects on the maize growth. Further analysis indicated that the sea surface temperature (SST) anomalies over North Atlantic and Maritime Continent in later spring are the important factors affecting the summer droughts over NEC. The late spring SST anomaly over North Atlantic can excite the Rossby waves from the western North Atlantic and propagate eastward to NEC. The snow anomaly over western Siberia in late spring and the soil moisture anomaly over NEC in summer are key factors linking the SST anomaly to drought over the NEC. On the other hand, the Maritime Continent SST anomaly in late spring can modulate the activity of the East Asian jet stream via the East Asia-Pacific (EAP) teleconnection, which can provide the favorable conditions for the soil moisture reduction over NEC. Eventually, a predictive model for maize yield over NEC is successfully developed by using the predictive indices of the North Atlantic and the Maritime Continental SST during late spring. Both the cross-validation and independent sample tests show that the calibrated prediction model is robust and exhibits high skill in predicting maize yield over NEC.

Seed responses to change in ambient humidity and the consequences for storability

The study of seed moisture sorption isotherms helps us to understand the response of seeds to changes in moisture in their environment and how this might impact their longevity. A seed moisture isotherm shows the relationship between moisture content (MC) and water activity (aw) at a constant temperature. Seed MC is higher when it dries from a hydrated state (desorption) than when it rehydrates from a very dry state (adsorption) to the same RH, an effect known as hysteresis. Seeds on the desorption isotherm will age faster than seeds on the adsorption isotherm at the same RH due to higher MC, resulting in a more rapid decline in seed viability and vigour. In this study, moisture isotherms of seeds from diverse species were determined and modeled using the Guggenheim-Anderson-de Boer (GAB) model; the hysteresis effect was then quantified. The maximum hysteresis magnitude varied between 0.3 and 2.7% MC (occurring between 49 and 57% RH) when seeds were dried over silica gel (below 11% RH) and rehydrated. Cycling seeds between 30 and 50%, 20 and 50%, and 15 and 50% RH, it was found that seeds of barley, lupin, buckwheat, wheat and pea switch to the adsorption isotherm upon rehydration after drying at intermediate moisture levels. Thus, adsorbing seeds of these species have greater longevity than desorbing seeds at the same RH. In contrast, seeds of oilseed rape and yellow mustard do not show a hysteresis effect unless they are dried to very low MC (over silica gel), so the adsorbing seed longevity remains the same as desorbing seeds at a constant RH. It is important to consider the moisture history of seeds depending on species for better seed storage management.

Experimental and Computational Analysis of Slurry‐Based Manufacturing of Solid‐State Battery Composite Cathode

The rheological properties of the electrode slurry significantly influence the manufacturing process of solid‐state batteries, affecting coating quality and the resulting cathode microstructure. The correlation between slurry attributes and final electrode characteristics is analyzed using particle size and solid content as key metrics. The performed coarse‐grained molecular dynamics simulations of LiNi0.8Mn0.1Co0.1O2 and Li6PS5Cl composite electrodes closely fit experimental viscosity, indicating the model's suitability for predicting slurry behavior. Then the microstructural properties of the dry and calendered electrodes are calibrated with the experiments. The simulation workflow is fitted completely using only two sets of force fields, one for the slurry and the other for the dry state of the electrode. The effective electronic conductivities are contingent on the particle size, without showing significant limitation on cathode rate capabilities. This comprehensive study highlights the intricate interplay between slurry solid content, microstructure design, and manufacturing processes in optimizing solid‐state battery performance. Consistent slurry characteristics are crucial for uniform electrode coating while optimizing particle size and solid content improves electrode porosity. The findings provide valuable insights for enhancing solid‐state battery design and manufacturing processes for the adaptation of already established scaling up technologies.

Porous PEG Scaffold Fabricated via Emulsion-Templating Technique Towards Immobilization of Saccharomyces cerevisiae Cells

The cell immobilization technique, which restricts living cells to a certain space, has received widespread attention as an emerging biotechnology. In this study, a yeast (Saccharomyces cerevisiae)-loaded highly open-cell emulsion-templated polyethylene glycol (PEG-polyHIPE) was synthesized to be a reusable enzymatic catalyst. An emulsion was prepared with polyethylene glycol diacrylate (PEGDA) aqueous solution, cyclohexane, and polyethylene-polypropylene glycol (F127) as the continuous phase, dispersed phase, and surfactant, respectively. Then PEG-polyHIPE was obtained by polymerization of the PEGDA in emulsion. The highly porous materials obtained by the emulsion-templating method are suitable for use as carrier materials for yeast immobilization, due to their favorable structural designability. During the activation process, the yeast S. cerevisiae can readily gain access to the interior of the material via the interconnected pores and immobilize itself inside the voids. The yeast-loaded polyHIPE was then used to ferment glucose for ethanol production. The yeast immobilized inside the polyHIPE has high fermentation efficiency, good recoverability, and storage stability. After seven cycles, the yeast maintained 70% initial fermentation efficiency. The S. cerevisiae kept more than 90% of the initial cellular activity after one week of storage both in the dry state and in yeast extract peptone dextrose medium (YPD) at 4 °C. This study strongly demonstrates the feasibility of using high-throughput porous materials as cell immobilization carriers to efficiently osmotically immobilize cells in polyHIPEs for high-performance fermentation.

Alginate-gelatin based nanocomposite hydrogel scaffold incorporated with bioactive glass nanoparticles and fragmented nanofibers promote osteogenesis: From design to in vitro studies

The current study proposes fragmented nanofibers of polycaprolactone (FNF) with bioactive glass nanoparticles (nBG) incorporated into a polymeric matrix of alginate-gelatin for the creation of a hydrogel scaffold. Four groups were prepared: control, bioactive glass containing scaffold (BG), fragmented nanofibers with bioactive glass scaffold (FNF(PCL) + BG), and fragmented composite nanofibers scaffold (FNF (PCL + BG)). FNF (PCL + BG) scaffolds revealed a more controlled degradation rate, with approximately 20 % degradation occurring after 28 compared. The FNF(PCL) + BG scaffolds had the highest compressive strength in both dry and wet states. Following 14 days of incubation in simulated body fluid, hydroxyapatite formation had occurred on the surface of scaffolds containing nBG, and after 28 days on other groups tested. Cell studies revealed that the FNF(PCL) + BG scaffolds had superior cell viability without inhibiting cell proliferation. The FNF(PCL) + BG and FNF(PCL + BG) scaffolds had the highest alkaline phosphatase (ALP) activity and FNF(PCL) + BG scaffolds showed to support osteogenic differentiation.

Highly flexible SCOF proton exchange membrane reinforced with PTFE to enhance fuel cell power density

Sulfonated covalent organic frameworks (SCOFs) facilitate rapid proton conduction through densely ordered sulfonic acid groups, however, the brittleness of COFs self-supporting membranes often makes potential difficulty in fuel cell assembly and limits their power density. Herein, a highly flexible SCOF proton exchange membrane is developed through in-situ growth of a continuous BD(SO3H)2–COF microphase within porous PTFE networks. The strong hydrogen bonding between PTFE and BD(SO3H)2–COF contributes to the defect-free morphology of the BD(SO3H)2/PTFE membrane. The reinforce of PTFE network makes the membrane extremely high flexibility, achieving an elongation at break of 124.4 % even with a remarkably high SCOF mass proportion of 90 wt% (BD(SO3H)2/PTFE-0.9). This allows the membrane to be folded repeatedly, even in dry state. The swelling ratio in water at 80 °C is effectively restricted to 8.6 %, even with a high ion exchange capacity of 3.6 mmol g−1 and a water uptake of 68.2 %. The densely ordered sulfonic acid groups in continuous BD(SO3H)2–COF microphase contribute to a high proton conductivity up to 249.2 mSꞏcm−1 at 80 °C, approximately 1.5 folds that of Nafion 212. As a result, the BD(SO3H)2/PTFE-0.9 membrane achieves a fuel cell power density of 1195.3 mWꞏcm−2 at 80 °C, along with a high open circuit voltage of 1.01 V, surpassing the-state-of-the-art COF-based proton exchange membranes. This work provides a novel strategy to fabricate COFs into flexible and size scalable membranes, enhancing the performance of fuel cells.

Imaging with a twist: Three-dimensional insights of the chiral nematic phase of cellulose nanocrystals via SHG microscopy.

Cellulose nanocrystals (CNCs) are bio-based nanoparticles that, under the right conditions, self-align into chiral nematic liquid crystals with a helical pitch. In this work, we exploit the inherent confocal effect of second-harmonic generation (SHG) microscopy to acquire highly resolved three-dimensional (3D) images of the chiral nematic phase of CNCs in a label-free manner. An in-depth analysis revealed a direct link between the observed variations in SHG intensity and the pitch. The highly contrasted 3D images provided unprecedented detail into liquid crystal's native structure. Local alignment, morphology, as well as the presence of defects are readily revealed, and a provisional framework relating the SHG response to the orientational distribution of CNC nanorods within the liquid crystal structure is presented. This paper illustrates the numerous benefits of using SHG microscopy for visualizing CNC chiral nematic systems directly in the suspension-liquid phase and paves the road for using SHG microscopy to characterize other types of aligned CNC structures, in wet and dry states.

Polyfluorene-based conjugated nanocomposites with in-situ gold nanoparticles: Synthesis via rational chemical passivation and characterization of supramolecular fibrillar structures

We present a rational and innovative chemical approach for synthesizing and characterizing conjugated polymer nanocomposites as direct passivation of gold nanoparticles (AuNPs), highlighting intrinsic morphologies and distinct photophysical properties in the solid state. The pioneering synthesis of polyfluorene with thiol, LaPPS79.10, revolutionized its application as a direct passivator of AuNPs, resulting in stable nanocomposites with the capacity for storage in the dry state and subsequent redispersion in organic solvent. The presence of AuNPs with average diameters of 3.5 ± 1.3 nm induced the formation of an interconnected fibrillar supramolecular network (ribbon-like) and several microdomains in the nanocomposite (LaPPS79.10+AuNPs), correlated by XRD, TEM and SEM measurements. Characterization of the polyfluorene precursor derivative, LaPPS10, revealed bundle-like morphologies with aggregation-induced emission (AIE). Introducing thiol groups into the intermediate structure induced polymer chain organization (LaPPS79.10), leading to unique straw-like and lenticular bundle morphologies, disrupting the non-planar π-π packing and quenching the emission, a case of aggregation-caused quenching (ACQ). In LaPPS79.10+AuNPs, the proximity of the π system to the Au localized surface plasmon resonance (LSPR) resulted in high absorption, negligible self-absorption, and efficient emission quenching, as well as improved thermal resistance compared to the original polymer. The unprecedented discovery of the properties resulting from the electronic interaction between the π system of the AuNPs passivating polymer and the effects of plasmonic resonance represents a significant advance in nanoscience, opening new perspectives for exciting applications in organic photovoltaic devices and metamaterials.

Mechanical and suture-holding properties of a UV-cured atelocollagen membrane with varied crosslinked architecture

The mechanical competence and suturing ability of collagen-based membranes are paramount in guided bone regeneration (GBR) therapy, to ensure damage-free implantation, fixation and space maintenancein vivo. However, contact with the biological medium can induce swelling of collagen molecules, yielding risks of membrane sinking into the bone defect, early loss of barrier function, and irreversibly compromised clinical outcomes. To address these challenges, this study investigates the effect of the crosslinked network architecture on both mechanical and suture-holding properties of a new atelocollagen (AC) membrane. UV-cured networks were obtained via either single functionalisation of AC with 4-vinylbenzyl chloride (4VBC) or sequential functionalisation of AC with both 4VBC and methacrylic anhydride. The wet-state compression modulus (Ec) and swelling ratio (SR) were significantly affected by the UV-cured network architecture, leading up to a three-fold reduction in SR and about two-fold increase inEcin the sequentially functionalised, compared to the single-functionalised, samples. Electron microscopy, dimensional analysis and compression testing revealed the direct impact of the ethanol series dehydration process on membrane microstructure, yielding densification of the freshly synthesised porous samples and a pore-free microstructure with increasedEc. Nanoindentation tests via spherical bead-probe atomic force microscopy (AFM) confirmed an approximately two-fold increase in median (interquartile range (IQR)) elastic modulus in the sequentially functionalised (EAFM= 40 (13) kPa), with respect to single-functionalised (EAFM= 15 (9) kPa), variants. Noteworthy, the single-functionalised, but not the sequentially functionalised, samples displayed higher suture retention strength (SRS = 28 ± 2-35 ± 10 N∙mm-1) in both the dry state and following 1 h in phosphate buffered saline (PBS), compared to Bio-Gide® (SRS: 6 ± 1-14 ± 2 N∙mm-1), while a significant decrease was measured after 24 h in PBS (SRS= 1 ± 1 N∙mm-1). These structure-property relationships confirm the key role played by the molecular architecture of covalently crosslinked collagen, aimed towards long-lasting resorbable membranes for predictable GBR therapy.

Influence of rubber aggregates from the recycled tires on the physico-mechanical and durability properties of compressed earth blocks

To meet sustainable development goals, global policies are strongly oriented toward valorizing alternative resources such as local materials and waste from different sectors of activity. This study aims to evaluate the influence of adding rubber aggregates from used/recycled tires (GPU) on the physico-mechanical and durability properties of compressed earth bricks (CEB). The CEB were made with an earthen matrix containing 8% cement, and 0 to 2% mass of GPU. The CEB were cured under ambient conditions (30±5°C) for 28 days. The results showed a real improvement in physical and mechanical performance and durability indicators of CEB with increasing GPU content. The apparent density changed slightly from 1697 kg/m3 to 1733 kg/m3. Total water absorption decreased from 21% to 19% with a slight decrease in water-accessible porosity from 35.7% to 33.1%. The capillary absorption coefficient at 10 minutes also decreased from 14 g/cm2.min1/2 to 10 g/cm2.min1/2 The increase of 29% was noted on the compressive strength in the dry state ranging from 3.5 to 4.5 MPa and of 60% on the compressive strength in the wet state ranging from 1.1 MPa to 1.7 MPa. This resulted in the improvement of the structural efficiency coefficient by 27% ranging from 2080 to 2651 Pa.m3/kg. Abrasion resistance coefficient increased more than 50% ranging from 10.8 to 16.9 cm2/g. By comparing the results to the normative references, the CEB containing GPU can be classified as CEB usable in load-bearing walls in a dry environment and resistant to abrasion.