Transverse Swelling Research Articles

High-Strength, High-Swelling-Resistant, High-Sensitivity Hydrogel Sensor Prepared with Wood That Retains Lignin.

Wood-derived hydrogels possess satisfactory longitudinal strength but lack excellent swelling resistance and dry shrinkage resistance when achieving high anisotropy. In this study, we displayed the preparation of highly dimensional stable wood/polyacrylamide hydrogels (wood/PAM-Al3+). The alkali-treated wood retains lignin as the skeleton of the hydrogel. Second, Al ions were added to the metal coordination with lignin. Finally, by employing free radical polymerization, we construct a conductive electronic network using polyaniline within the wood/PAM-Al3+ matrix to create the flexible sensor. This approach leverages lignin's integrated structure within the middle lamella to provide enhanced swelling resistance and stronger binding strength in the transverse direction. Furthermore, coordination between lignin and Al ions improves the mechanical strength of the wood hydrogel. Polyaniline provides stable linear pressure and temperature responses. The wood/PAM-Al3+ exhibits a transverse swelling ratio of 3.90% while achieving a longitudinal tensile strength of 20.5 MPa. This high-strength and high-stability sensor is capable of monitoring macroscale human behavior. Therefore, this study presents a simple yet innovative strategy for constructing tough hydrogels while also establishing an alternative pathway for exploring lignin networks in new functional materials development.

Observing bamboo dimensional change caused by humidity

Bamboo is a kind of natural biomaterials sensitive to moisture. The change of moisture content in bamboo leads to the cracking and deformation of bamboo. To understand the mechanism of swelling due to moisture change, the swellings were measured on bamboo blocks as well as separated fiber and parenchyma tissue under different humidity conditions in situ by using a dynamic vapor sorption (DVS) instrument and a charge-coupled device (CCD) camera. The results showed that when the relative humidity (RH) was above 40%, the main types of moisture in the bamboo blocks changed, and the area swelling of the bamboo blocks increased rapidly. When equilibrium moisture content (EMC) was 11.91%, the area swellings of the fibers (BF) and the vascular bundles (BV) in the bamboo blocks, and the bamboo blocks were 42.00%, 25.69%, and 4.26%, respectively. The content of the bamboo fiber plays a decisive role in bamboo swelling. For the separated fibers and parenchymal cells, when RH changed from 0% to 90%, the transverse swellings of the fibers and parenchymal cells were 7.24% and 2.22%, respectively. The longitudinal swellings of the fibers and parenchymal cells were 0.62% and 1.24%, respectively. The fibers had a higher transverse swelling rate than that of the parenchyma cells.

Anisotropic swelling of anisotropic elastic panels.

While isotropic in-plane swelling problems for thin elastic sheets have been studied extensively in recent years, many shape-programmable materials, including nematic solids and 3D-printed structures, are anisotropic, as are most industrial sheet materials. In this theoretical work, we consider central swelling and shrinkage of plates of aspect ratio and material properties relevant to the manufacture of engineered wood composite panels in which both in-plane swelling and material stiffness are highly orthotropic, leading to multiple separations in energy scales. With transverse swelling in the soft direction, and gradients in the stiff direction, the warped plates adopt two distinct types of configurations, axisymmetric and twisted, which we illustrate with toy models. We employ a two-parameter family of isometries to embed the metric programmed by the swelling, thus reducing the problem to one of minimizing bending energy alone. A simple argument is seen to closely predict averaged axisymmetric curvatures. While purely cylindrical shapes are unobtainable by pure in-plane swelling, they can be closely approximated in a highly anisotropic system. However, anisotropy can favor twisting, and breaks a degenerate soft deformation mode associated with minimal surfaces in isotropic materials. Bifurcations from axisymmetric to twisted shapes can be induced by anisotropy or by certain attributes of a central shrinkage profile. Finally, we note how our findings indicate practical limitations on the diagnosis of moisture inhomogeneities in manufactured panels by observation of warped conformations, due to the sensitivity of the qualitative response to specifics of the profile.

Transverse colon invasion from intrahepatic cholangiocarcinoma with lymph node metastasis in the regional mesocolon: a case report

BackgroundIntrahepatic cholangiocarcinoma (ICC) is an aggressive cancer with high frequency of extrahepatic metastasis at diagnosis. However, there have been very few reports of direct invasion to transverse mesocolon with lymph node metastasis in the regional mesocolon.Case presentationA 71-year-old man presented to our hospital with anorexia and weight loss. Abdominal computed tomography (CT) revealed enlarged gallbladder wall with intrahepatic tumor extended from the gallbladder. The transverse colon was located adjacent to the gallbladder and its wall was thickened, indicating tumor invasion. Some enlarged lymph nodes were observed in the transverse mesocolon, suggesting metastatic or inflammatory lymph node swelling. Percutaneous liver biopsy detected poorly differentiated adenocarcinoma. After confirming the absence of remote metastasis and peritoneal dissemination, surgical resection including right hepatectomy and right hemicolectomy was performed. The pathological diagnosis was adenosquamous carcinoma of the liver and lymph node metastasis in the transverse mesocolon. The surgical margins were negative and R0 resection was achieved. Although adjuvant chemotherapy was administered, follow-up CT detected multiple metastases to the lung 4 months after surgery. The patient died 12 months after the operation.ConclusionsDirect colon invasion from ICC may cause lymph node metastasis in the regional mesocolon. Careful assessment is necessary for the diagnosis of enlarged lymph nodes in ICC with direct colon invasion.

Transient 3D finite element method for predicting extrudate swell of domains containing sharp edges

A new transient 3D finite element method for predicting extrudate swell of domains containing sharp edges is proposed. Here, the sharp edge is maintained over a large distance in the extrudate by describing the corner lines as material lines. The positions of these lines can be used to describe the transverse swelling of the 2D free surfaces and expand the domain over which a 2D height function on the free surfaces is applied. Solving the 2D height functions gives the positions of the free surfaces. First a 2D axisymmetric case was tested for comparison, using three different constitutive models. The Giesekus, linear Phan-Thien Tanner (PTT) and exponential PTT constitutive models all showed convergence upon mesh- and time-step refinement. It was found that convergence remains challenging due to the singularity at the die exit. The new method is validated by comparing the final volume change of the extrudate of a 3D cylinder to the final volume change of a reference mesh of the 2D axisymmetric case. Finally, simulations were performed for different, complex, die shapes for a viscous fluid and for viscoelastic fluids. The results compared favorably with literature. Viscoelastic results, using the Giesekus model and the exponential PTT model, were compared for different Weissenberg numbers and different values for the non-linear parameters of the constitutive models. It was found that the swell is highly dependent on the rheological parameters and the constitutive model used.

Probing Additive Loading in the Lamellar Phase of a Nonionic Surfactant: Gibbs Ensemble Monte Carlo Simulations Using the SDK Force Field.

Understanding solute uptake into soft microstructured materials, such as bilayers and worm-like and spherical micelles, is of interest in the pharmaceutical, agricultural, and personal care industries. To obtain molecular-level insight on the effects of solutes loading into a lamellar phase, we utilize the Shinoda-Devane-Klein (SDK) coarse-grained force field in conjunction with configurational-bias Monte Carlo simulations in the osmotic Gibbs ensemble. The lamellar phase is comprised of a bilayer formed by triethylene glycol mono- n-decyl ether (C10E3) surfactants surrounded by water with a 50:50 surfactant/water weight ratio. We study both the unary adsorption isotherm and the effects on bilayer structure and stability caused by n-nonane, 1-hexanol, and ethyl butyrate at several different reduced reservoir pressures. The nonpolar n-nonane molecules load near the center of the bilayer. In contrast, the polar 1-hexanol and ethyl butyrate molecules both load with their polar bead close to the surfactant head groups. Near the center of the bilayer, none of the solute molecules exhibits a significant orientational preference. Solute molecules adsorbed near the polar groups of the surfactant chains show a preference for orientations perpendicular to the interface, and this alignment with the long axis of the surfactant molecules is most pronounced for 1-hexanol. Loading of n-nonane leads to an increase of the bilayer thickness, but does not affect the surface area per surfactant. Loading of polar additives leads to both lateral and transverse swelling. The reduced Henry's law constants of adsorption (expressed as a molar ratio of additive to surfactant per reduced pressure) are 0.23, 1.4, and 14 for n-nonane, 1-hexanol, and ethyl butyrate, respectively, and it appears that the SDK force field significantly overestimates the ethyl butyrate-surfactant interactions.

Informing the improvement of forest products durability using small angle neutron scattering

A better understanding of how wood nanostructure swells with moisture is needed to accelerate the development of forest products with enhanced moisture durability. Despite its suitability to study nanostructures, small angle neutron scattering (SANS) remains an underutilized tool in forest products research. Nanoscale moisture-induced structural changes in intact and partially cut wood cell walls were investigated using SANS and a custom-built relative humidity (RH) chamber. SANS from intact wood sections cut from each primary wood orientation showed that although wood scattered anisotropically across 1.3–600 nm length scales, measurement of elementary fibril spacing and low-q surface scattering were independent of orientation. Water sorption caused spacing between elementary fibrils to increase with RH, and this swelling accounted for over half the transverse swelling in S2 secondary wood cell walls. Elementary fibril spacing in longitudinally cut wood cells, which were designed to mimic cells near wood-adhesive bondlines, was greater than the spacing in intact cells above 90 % RH. This suggested that some cell wall hoop constraint from the S1 and S3 cell wall layers on the S2 layer was released by cutting the cells. Furthermore, increased spacing between elementary fibrils may also create diffusion channels that are hypothesized to be responsible for the onset of fungal decay in wood. Protocols were established to use SANS in future research to study adhesives and protection treatments to improve moisture durability in forest products.

Hygroscopic swelling and shrinkage of latewood cell wall micropillars reveal ultrastructural anisotropy

We document the hygroscopic swelling and shrinkage of the central and the thickest secondary cell wall layer of wood (named S2) in response to changes in environmental humidity using synchrotron radiation-based phase contrast X-ray tomographic nanoscopy. The S2 layer is a natural fibre-reinforced nano-composite polymer and is strongly reactive to water. Using focused ion beam, micropillars with a cross section of few micrometres are fabricated from the S2 layer of the latewood cell walls of Norway spruce softwood. The thin neighbouring cell wall layers are removed to prevent hindering or restraining of moisture-induced deformation during swelling or shrinkage. The proposed experiment intended to get further insights into the microscopic origin of the anisotropic hygro-expansion of wood. It is found that the swelling/shrinkage strains are highly anisotropic in the transverse plane of the cell wall, larger in the normal than in the direction parallel to the cell wall's thickness. This ultrastructural anisotropy may be due to the concentric lamellation of the cellulose microfibrils as the role of the cellulose microfibril angle in the transverse swelling anisotropy is negligible. The volumetric swelling of the cell wall material is found to be substantially larger than the one of wood tissues within the growth ring and wood samples made of several growth rings. The hierarchical configuration in wood optimally increases its dimensional stability in response to a humid environment with higher scales of complexity.

Full-field moisture induced deformation in Norway spruce: intra-ring variation of transverse swelling

The transverse hygro-expansion of Norway spruce wood is studied on the growth ring level using digital image correlation. This non-destructive technique offers the possibility for a contactless study of deformation fields of relatively large areas. The measured full-field strains are segmented into individual growth rings. Whereas radial strains closely follow the density progression with the maximum in the dense latewood (LW), tangential and shear strain remain constant except for positions around the edges of the sample. A simple FE three phase growth ring model is in good agreement with the experimental values. The selective activation of individual phases like earlywood (EW), transition wood and LW demonstrates that the radial hygro-expansion is dominated by the EW deformation, whereas tangential deformation is a complex interplay of expansion and compression that needs all tissues to fully develop.

Vertex-element models for anisotropic growth of elongated plant organs.

New tools are required to address the challenge of relating plant hormone levels, hormone responses, wall biochemistry and wall mechanical properties to organ-scale growth. Current vertex-based models (applied in other contexts) can be unsuitable for simulating the growth of elongated organs such as roots because of the large aspect ratio of the cells, and these models fail to capture the mechanical properties of cell walls in sufficient detail. We describe a vertex-element model which resolves individual cells and includes anisotropic non-linear viscoelastic mechanical properties of cell walls and cell division whilst still being computationally efficient. We show that detailed consideration of the cell walls in the plane of a 2D simulation is necessary when cells have large aspect ratio, such as those in the root elongation zone of Arabidopsis thaliana, in order to avoid anomalous transverse swelling. We explore how differences in the mechanical properties of cells across an organ can result in bending and how cellulose microfibril orientation affects macroscale growth. We also demonstrate that the model can be used to simulate growth on realistic geometries, for example that of the primary root apex, using moderate computational resources. The model shows how macroscopic root shape can be sensitive to fine-scale cellular geometries.

Determination of yarn and fiber diameters after swelling using a capillary rise method

Capillary kinetics of textile knitted fabrics are investigated considering the effect of transverse swelling in fiber and yarn scales. A mathematical model was developed based on the industrial construction parameters, the capillary mechanism and the swelling ratio on both porosity scales: macro and micro. The capillary kinetics are used to determine the yarn and fiber diameters after swelling and compared to those determined using a microscopic method. In order to validate our model, a series of experiments was conducted on jersey knitted fabric using raw materials with different swelling ratios: cotton and PET. The results showed good agreement between the two methods of diameter determinations.

Nano-based surface treatm effects on swelling, water sorption and hardness of wood

Untreated and nano-based compound treated chestnut, wild cherry, fir, and black pine wood samples were immersed in water at four different temperature levels. It was found that the nano-based compound was a very effective agent for lowering both the initial and maximum equilibrium transverse swelling of wood. However, the latter were found to have similar trends as the initial swelling properties. The surface treatment appeared not to improve the maximum water absorption. The highest average activation energy was calculated for chestnut (23.1 kJ/mole), followed by pine (20.2 kJ/mole), cherry (18.1 kJ/mole), and fir (16.2 kJ/mole). However, the nano-based treatment resulted in a small increase in activation energies of all wood species. It was found that absorption of water into wood as well as increasing temperature had a lowering effect on shore D hardness.

Revision and Analysis of Pseudosaldula Cobben (Insecta: Hemiptera: Saldidae): A Group with a Classic Andean Distribution

Abstract The genus Pseudosaldula Cobben, which is restricted to the Andean Subregion of South America, is revised. Fourteen valid species are recognized, nine of them being described as new and 10 previously published names are treated as junior synonyms based on the examination of approximately 3500 specimens from Colombia, Ecuador, Peru, Bolivia, Argentina, and Chile. All taxa are described or redescribed. A key to the species is provided. Color habitus illustrations, distributional maps, and detailed measurements are provided for all species. Scanning electron micrographs of the vestiture, parameres, parandria, face, and pretarsus are provided for representative species, as are color views of the face and the nymphs. The concept of a postclypeus in the Saldidae is questioned and the term transverse swelling, as coined by Parsons, is applied in discussing distinctive aspects of facial morphology in Pseudosaldula. A previously unreported, presumably glandular, pore is documented on the parameres in the S...

Contraction of the microfibrils of wood treated with aqueous NaOH: evidence from changes in the anisotropy of the longitudinal and transverse swelling rates of wood

Previously, we reported that wood samples contract longitudinally, although the detailed mechanism for this contraction was undetermined. Stockmann reported that wood cells contract longitudinally and twist into S-helixes while lignin and hemicelluloses are removed in pulping, and according to Nakano et al., the longitudinal contraction of Yezo spruce (Picea jezoensis) increases with both the concentration of the NaOH solution and temperature. Based on experimental results, Nakano et al. proposed that the longitudinal contraction of samples resulted from the contraction of microfi brils via an entropy–elastic force. For Yezo spruce, Fujimoto and Nakano reported that the fi bril angle increased from 13o to 17o as the concentration of aqueous NaOH solution increased from 10% to 15%, while tracheid length decreased by about 10%. Other than these reports showing indirect evidence that the longitudinal contraction of the microfi brils themselves infl uences the longitudinal contraction of wood samples, no defi nitive evidence has been presented. This study sought to clarify the contribution of microfi bril contraction to the longitudinal contraction of wood samples by examining the basis of the anisotropic changes in the longitudinal and transverse swelling rates of wood samples. Materials and methods

Transverse swelling behavior of hinoki (Chamaecyparis obtusa) revealed by the replica method

Transverse swelling and its anisotropy in hinoki (Chamaecyparis obtusa) in several kinds of organic liquids and in water were investigated by means the replica method. There was more cross-sectional swelling of cell walls and cell wall thickness in earlywood than in latewood. Marked swelling toward cell lumens was observed in wood swollen in liquids that had higher swelling potentials than water. This suggests that the swelling of cell walls in these liquids is much greater than the external swelling. Feret's diameters of the cell lumens were reduced by swelling in all the observed cases except in the tangential direction of earlywood, suggesting that cell walls swell to a much less extent in width than in thickness. Deformation of cell shapes caused by the tensile force from the latewood were observed in the earlywood and in the transitional region from earlywood to latewood. When swollen in water, transverse swelling anisotropy caused only by the swelling in cell wall thickness were calculated to be 1.2 for the whole region over an annual ring and 1.4 for the earlywood. These values could not account for the external swelling anisotropy of 2.1. Considering obvious deformations of cell shapes in the earlywood and in the transitional region, we conclude that the interaction between earlywood and latewood is one of the prime factors contributing to the transverse swelling anisotropy of coniferous wood.

Observation of the Swelling Behavior of Coniferous Cells Using a Confocal Scanning Laser Microscope and a Digital Image Correlation Method

The transverse swelling behavior of coniferous wood cells was observed using a confocal scanning laser microscope and a digital image correlation method (DIC). Since the laser microscope has great depth of focus and high resolution, it was possible to observe the deformation of cells precisely. In order to observe the swelling behavior of specimens (Douglas-fir, Pseudotsuga menziessi) on the stage of the microscope, moisture was supplied using a humidifier. Digital image data of the cells taken by the laser microscope were used to measure the swelling behavior using DIC.The outside diameter of latewood tracheids swelled or changed almost isotropically with increasing moisture content, but the inside diameter (lumen) shrank greatly and anisotropically. Earlywood tracheids expanded a little but underwent great changes in shape. Thickness expansion of cell walls was less than circumferential expansion (perpendicular to the thickness direction), so that we concluded that the anisotropy of expansion was mainly based on thickness swelling. In latewood, circumferential expansion of radial cell walls (changes in length of the middle lamella) was great, but tangential cell walls expanded less than radial walls (in some cases the expansion was nearly zero). The angles between a radial wall and the adjacent tangential wall increased both in latewood and in earlywood by swelling.

Use of the environmental scanning electron microscope for the observation of the swelling behaviour of cellulosic fibres

AbstractWe have developed a method for observing transverse swelling of cellulosic fibres in the environmental scanning electron microscope (ESEM). The presence of liquid water in the ESEM specimen chamber allows the observation of in situ hydration without the need for coating, freezing, or drying of the sample. For reproducibility of the hydration and dehydration process, specialised mounting techniques are required and control of the conditions for condensation and evaporation of liquid water is necessary. The sensitivity of these cellulosic materials to the electron beam was investigated, showing that some damage mechanisms are enhanced by the continual presence of water vapour in the chamber. A discussion is presented of the effect of various experimental parameters on the extent and time of onset of the damage, and we outline steps to maximise the amount of useful experimental time for these fibres.

Enhanced Bleaching and Softening of Jute Pretreated with Polysaccharide Degrading Enzymes

Treating jute fibers with enzymes effects an increase in pore volume (46.2%), which leads to an increased capacity to retain peroxide (25.5%) and a larger surface area of lignin accessible to the oxidant (∼30%). Improved bleaching is therefore achieved. Enzyme treatment increases transverse swelling (14%) and reduces bulk torsional rigidity (12.5%), making the fibers more flexible and therefore softer. The removal of cementing materials such as hemicellulose and lignin by bleaching is enhanced by enzyme pretreatment, resulting in better filamentation and fineness. Scanning electron micrographs confirm this. Experiments with purified enzyme preparations have shown that xylanase pretreatment predominates in facilitating bleaching, and cellulase in the swelling or softening. An appropriate combination of the two is required to obtain optimal effects.

Deformation of surface cladding and matrix of tungsten-fiber-reinforced superalloy under thermomechanical loading

A surface cladding is required to maintain structural integrity for tungsten-fiber-reinforced superalloys exposed to air at high temperatures. Under thermomechanical loading, surface crenulations appear in the cladding as a result of extensive plastic flow caused by thermal expansion and modulus mismatch with the composite. These crenulations eventually lead to transverse cracks which show stable propagation. In addition, transverse swelling occurred in the hot section of the specimen, reflective of extensive plastic flow and void formation in the matrix.

The influence of transverse differential swelling stresses on the kinetics of sorption of penetrants by polymer membranes

The influence of transverse differential swelling stresses on the kinetics of sorption of a penetrant in a polymer membrane exhibiting linear viscoelasticity is described by a model developed from the much simpler one of Crank. Sorption and transverse swelling kinetic curves are computed numerically. The character of absorption and desorption curves is examined systematically mainly as a function of (i) the magnitude of the stresses set up and of the stress-dependence of the diffusion coefficient, (ii) the relative rates of stress relaxation and of diffusion, and (iii) the degree of plasticization or “softening” of the polymer by the penetrant. It is shown that important general features of experimental sorption kinetic curves can be reproduced satisfactorily under well defined conditions. Attention is also given to transverse swelling kinetic curves. Their correlation with the corresponding sorption curves is examined briefly but systematically and discussed with reference to experimental data.