Longitudinal Orientation Research Articles

Atypical longitudinal self-inflicted incised wounds as a cause of death in an ecstasy user.

A 32-year-old chronic drug abuser was found dead at the entrance to his home, covered in blood. Pools of blood, bloody footprints and bloodstains were found across the apartment. A double-edged razor was recovered from the scene. Autopsy revealed multiple incised wounds: two on the palmar aspect of both forearms (37cm and 33cm long, oriented longitudinally). The cuts extended into the subcutaneous adipose tissue, muscles and blood vessels. There was an additional 30cm cut extending across the middle of the torso anteriorly and two more cuts on the anteromedial aspect of the lower legs, set symmetrically (about 23 and 25cm long). These three cuts were more shallow than the upper extremity wounds. No hesitation wounds were identified. Toxicological analysis identified MDMA (ecstasy). The cause of death was exsanguination. The deceased has been using ecstasy for the previous five years and had a history of inpatient psychiatric treatment due to psychosis with delusions and hallucinations. These self-inflicted incised wounds had many atypical features: location (torso, legs and arms), longitudinal orientation and symmetrical distribution, absence of hesitation injuries, use of both dominant and non-dominant hand. The absence of previous suicide attempts and suicide note suggest that these self-inflicted injuries were not planned beforehand, but were abrupt. We hypothesize that this injury pattern is associated with both acute and chronic effects of MDMA.

Using potential of filament-wound carbon/glass polymeric composites as rocket motor thermal insulation

The study aim is to develop hybrid filament-wound polymeric composites based on flame retardant polyester resin (UPe) and multi-layer structured glass or combined carbon and glass fibers for use as ablative thermal insulation of rocket motor by wet filament winding technique. The composites have a multi-layered structure consisting of two layers of carbon (CF) or glass woven fabric (GF) and one layer of carbon or glass direct roving (CR or GR, respectively), repeated in three cycles. Structural analysis, performed using FTIR spectroscopy and dynamical-mechanical analysis, confirm highly polymerized network. Lower values of the tanδ peak height indicate improved interfacial adhesion between carbon/glass fibers and UPe. The improvements of thermal insulation index of 37% and erosion rate of 38.6% at 180°C are achieved for combined carbon/glass fiber–based composite compared to the neat UPe. Tensile and interlaminar shear properties are investigated according to the fiber orientation and the highest values of tensile and interlaminar shear strengths are obtained for composites with longitudinal orientation, 417.48 MPa and 22.30 MPa, respectively. Compared to the neat UPe, which degrades after 50 s at 3000°C, the composites are stable up to 192 s.

Experimental investigation of bending characteristics of hybrid composites fabricated by hand layup method

The extensive applications of hybrid composite materials in the field of transportation and structural domine provide prominent advantages in the order of stiffness, strength even cost. However extend the advantages of hybrid campsites in several field such as aviation and marine even more additional properties should be inculcate in them. During production of such profitable composites poses some problems at time at decompose and processing. It’s better to develop environment friendly and reusable composites, bio hybrid composite materials such of the one. In this paper, focused on development of Eco-friendly hybrid bio composites with the ingredients of drumstick fibers, glass fiber along with polyester resin. This hybrid bio composites subjected to bending test and evaluate the characteristics of bending properties, this research evident that bending characteristics of hybrid composites with longitudinal fiber orientation better than transverse.

A fully resolved multiphysics model of gastric peristalsis and bolus emptying in the upper gastrointestinal tract

Over the past few decades, in silico modeling of organ systems has significantly furthered our understanding of their physiology and biomechanical function. In spite of the relative importance of the digestive system in normal functioning of the human body, there is a scarcity of high-fidelity models for the upper gastrointestinal tract including the esophagus and the stomach. In this work, we present a detailed numerical model of the upper gastrointestinal tract that not only accounts for the fiber architecture of the muscle walls, but also the multiphasic components they help transport during normal digestive function. Construction details for 3D models of representative stomach geometry are presented along with a simple strategy for assigning circular and longitudinal muscle fiber orientations for each layer. We developed a fully resolved model of the stomach to simulate gastric peristalsis by systematically activating muscle fibers embedded in the stomach. Following this, for the first time, we simulate gravity-driven bolus emptying into the stomach due to density differences between ingested contents and fluid contents of the stomach. Finally, we present a case of retrograde flow of fluid from the stomach into the esophagus, resembling the phenomenon of acid reflux. This detailed computational model of the upper gastrointestinal tract provides a foundation for future models to investigate the biomechanics of acid reflux and probe various strategies for gastric bypass surgeries to address the growing problem of obesity.

Mechanical Properties of a Biocomposite Based on Carbon Nanotube and Graphene Nanoplatelet Reinforced Polymers: Analytical and Numerical Study

Biocomposites based on thermoplastic polymers and natural fibers have recently been used in wind turbine blades, to replace non-biodegradable materials. In addition, carbon nanofillers, including carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs), are being implemented to enhance the mechanical performance of composites. In this work, the Mori–Tanaka approach is used for homogenization of a polymer matrix reinforced by CNT and GNP nanofillers for the first homogenization, and then, for the second homogenization, the effective matrix was used with alfa and E-glass isotropic fibers. The objective is to study the influence of the volume fraction Vf and aspect ratio AR of nanofillers on the elastic properties of the composite. The inclusions are considered in a unidirectional and random orientation by using a computational method by Digimat-MF/FE and analytical approaches by Chamis, Hashin–Rosen and Halpin–Tsai. The results show that CNT- and GNP-reinforced nanocomposites have better performance than those without reinforcement. Additionally, by increasing the volume fraction and aspect ratio of nanofillers, Young’s modulus E increases and Poisson’s ratio ν decreases. In addition, the composites have enhanced mechanical characteristics in the longitudinal orientation for CNT- reinforced polymer and in the transversal orientation for GNP-reinforced polymer.

Radiological Evaluation of Postsurgical Course of Perforators in Retrograde Posterior Tibial Fasciocutaneous Flaps for Distal Leg and Foot Defects.

Background Mapping of vascular perforators by various methodologies have been described for planning of a variety of flaps in the lower limbs. We attempted to assess the changes in posterior tibial perforators after transfer of fasciocutaneous flaps for leg defects. Methods 20 patients with distal leg and foot defects were studied by computed tomography angiography (CTA) and preoperative audio Doppler to ascertain perforators of posterior tibial artery. Fasciocutaneous flaps were raised, based on these perforators, depending on the site and size of soft-tissue defects. The number of perforators and their distance from the medial malleolus were also studied. Postoperative CTA was performed on the 7th to 10th day, with emphasis on postoperative changes of the perforators on which the flaps were based. Results One to four posterior tibial perforators were found between 5 cm and 8 cm proximal to the medial malleolus. After flap transfer, the perforators could be traced to variable distance through the total length of the flap. The perforators formed small vascular loop in 12 patients, following retrograde posterior tibial flap transfer. The height of the loop, the number of such loops, the dilatation and tortuosity of the perforators, and their longitudinal orientation were studied in detail. Most of the findings can be explained by mechanical realignment of perforators as well as by the delay phenomenon associated with retrograde fasciocutaneous flaps. Conclusion It was concluded that the morphological changes associated with the perforators explained the vascular rationality and success of these flaps.

Experimental study on an alternative to suturing the laparotomy wound with a mesh thread

BACKGROUND: Incisional ventral hernias (IVH) in abdominal surgery remain relevant because the frequency of their formation after laparotomy reaches 10%30.7%.
 AIM: This study aimed to develop a method for the primary closure of a laparotomy wound via mesh endoprosthesis, which is superior to laparorrhaphy with traditional suture materials in terms of morphophysical properties.
 MATERIALS AND METHODS: Laparorrhaphy with a mesh thread was developed (Patent for invention RUS No 2714439 02/14/2020) as an alternative to preventive prosthetics with narrow indications to avoid herniation. An experimental work was conducted to investigate the wound process in the suture area on days 14 and 60 and determine the effectiveness and safety of the proposed method.
 RESULTS: Video laparoscopy data showed that no cases of adhesions were observed between the internal organs and the area of laparorrhaphy on days 14 and 60 of the postoperative period. Defects in the area of the application of sutures on the aponeurosis of the white line were absent. In the wound, the mesh thread fully integrated into the regenerating tissue, including at the site of the knot. The tissue also grew through the meshed cells. On day 14, the strength of the regenerating tissue with the sutured mesh thread was greater than that sutured without it (11.198 1.499, p 0.01). This finding was confirmed by the larger area of granulations and fibrosis in cases of mesh suture than that of the checkerwise-reinforcing suture, suture with a mesh thread, and suture with a strip of mesh endoprosthesis. Another peculiarity of the connective tissue newly formed in the area of the mesh endoprosthesis in the form of the mesh thread was that collagen fibrils were arranged concentrically. By contrast, the mesh strip had collagen fibrils arranged in a longitudinal orientation parallel to the endoprosthesis. On day 60 of the experiment, all the series showed signs of maturation of the connective tissue in the form of the predomination of fibrils in cellular elements and their compaction. The area of fibrosis and granulations still prevailed in cases of the mesh suture, where neocollagenogenesis in the cells of the endoprosthesis was more pronounced than that after the application of a reinforcing suture, a mesh thread, and a strip of mesh endoprosthesis.
 CONCLUSION: The absence of wound complications and negative impact on the surrounding tissues indicated the safety of using the mesh suture. The strengthened characteristics associated with the peculiarities of the wound process showed that the mesh suture was effective in preventing the occurrence of postoperative hernia. Therefore, this method could be used in clinical practice.

Direct observation of plastic shear strain concentration in the thick GLARE laminates under bending loading

The results of the digital image correlation (DIC) analysis for the three-point bending tests with GLARE1-9/8 laminates (9 aluminum and 8 unidirectional GFRP layers) are presented in this paper. The findings show that, in samples with a small span-to-thickness ratio, an intensive concentration of the plastic shear strain arises inside the GFRP layers, which significantly affects the load-bearing capacity and apparent interlaminar shear strength of GLARE. Previously, such effects were predicted based on numerical simulations. In the present paper, we validate these theoretical predictions based on the full-field DIC analysis of the shear strain distribution across the GLARE thickness. For this analysis, samples with longitudinal and transverse orientation of glass fibers in the GFRP layers were studied and compared. For the transverse samples, we also found that the matrix cracking in the GFRP layers becomes an additional source for the overall non-linear behavior of GLARE, such that the pure failure mode related to the interlaminar shear cannot be achieved.

PATH TRACKING FOR AN AUTONOMOUS VEHICLE DURING EMERGENCY CONDITION

An autonomous vehicle's primary function is detecting and tracking the road course precisely and correctly without a driver's assistance. As a result, implementing appropriate controllers is critical for improving the vehicle's stability and movement responsiveness. The performance of adaptive Stanley controlled is evaluated in this paper using numerical simulations. The Stanley controller's most common geometric controller for vehicle path tracking algorithms is compared based on their trajectory tracking analyses on various vehicle speed maneuvers. Stanley calculates steering based on the difference between the vehicle's lateral position and heading angle. The difference between desired coordinates and present coordinates of the vehicle along the path is used to calculate lateral, longitudinal, and vehicle heading orientation angle using the future prediction control technique. The results demonstrate that the Stanley controller outperforms the emergency trajectory with more consistent trajectory tracking and steady-state error.

Histochemical structure and tensile properties of birch cork cell walls

Tensile tests of birch cork were performed in the tangential direction. Birch cork in the wet state showed significantly higher extensibility than those in the dried state. The histochemical structure of birch cork was investigated by microscopic observation and spectroscopic analysis. Birch cork cell walls showed a two-layered structure and the inner material bordering cell wall. In transmission electron micrographs, osmium tetroxide stained the outer layer and inner material, whereas potassium permanganate stained the inner layer and inner material. After removal of suberin and lignin, only inner layer remained and Fourier-transformed infrared spectra showed the cellulose I pattern. Polarizing light micrographs indicated that molecular chains in the outer layer and inner material were oriented perpendicular to suberin lamination, whereas those in the inner layer showed longitudinal orientation. These results suggested that the outer layer and inner material mainly consist of suberin, whereas the inner layer and compound middle lamella consist of lignin, cellulose, and other polysaccharides. We hypothesized a hierarchical model of the birch cork cell wall. The lignified cell wall with helical arrangement of cellulose microfibrils is sandwiched between suberized outer layer and inner material. Cellulose microfibrils in the inner layer bear tensile loads. In the wet state, water and cellulose transfer tensile stress. In the dried state, this stress-transferal system functions poorly and fewer cells bear stress. Suberin in the outer layer and inner material may prevent absolute drying to maintain mechanical properties of the bark and to bear tensile stress caused by trunk diameter growth.

A study of ellipsoidal and spherical particle flow, clogging and unclogging dynamics

To study ellipsoidal and spherical particle flow, clogging behavior and unclogging dynamics, a series of numerical simulations were carried out using our validated 3-D coupled computational fluid dynamics–discrete element method (CFD–DEM) model. For the first time, the strength of clogging arches is assessed in terms of fluid pressure gradient, which can effectively break up the clog. The main findings are as follows. In a clogged assembly, only when the flushing fluid reaches the unclogging pressure gradient, the ellipsoidal and spherical particles can flow in a continuous state. For the ellipsoids and spheres with the same equivalent volume, the unclogging pressure gradient of an ellipsoidal assembly is 11.8 times higher than that of a spherical assembly. Clogging arches at the outlet show the highest strength when the longitudinal orientations of the ellipsoids are perpendicular to the outlet plane. In contrast, the formed arch has the lowest stability when the longitudinal orientations of the ellipsoids are in the same direction as the long side of the outlet, as shown in the graphical abstract. The unclogging pressure gradient of the former case is 1.9 times greater than that of the latter case. The granular arches observed in our 3-D model are categorized as complex 3-D backbone arches. In the flowing region, particles rotate nearly perpendicular to the outlet plane, especially those approaching the outlet. Moreover, triangular stagnant zones are formed on both sides of the bottom of the rectangular box. The model presented here offers a great promise for future investigation of various granular systems at the particle scale.

Investigation of the Ablative Properties of an EPDM\Kevlar Insulator in a Solid Rocket Motor

AbstractA study of the influence of the reinforced fiber orientation and the propellant aluminum content on the ablation and erosion performance of Ethylene Propylene Diene Monomer type insulation is presented. A subscale solid rocket motor has been used, with ammonium perchlorate and hydroxyl‐terminated polybutadiene propellant composition. Seven static firing tests were conducted: six with low Al and one with high Al content. The EPDM articles had four different Kevlar fiber orientations: circumferential, longitudinal, diagonal (45°), and random. Numerical simulations were supplemented to decipher the experimental outcome. The numerical results exhibit an over‐prediction tendency, yet they show that the examination of post‐fire charring of the insulation is insignificant. The test results indicate that the longitudinal fiber orientation has the least ablative resistance.

Effect of ageing on microstructure and fracture behavior of cortical bone as determined by experiment and Extended Finite Element Method (XFEM)

Bone fracture is a severe health concern; therefore, understanding the causes of bone fracture are crucial. This paper investigates the microstructure and fracture behaviour of cadaveric cortical bone of two different groups (Young, n= 6; Aged, n=7). The microstructure is obtained from µ-CT images, and the material parameters are measured with nanoindentation. Fracture behaviour in transverse and longitudinal orientations is investigated experimentally and numerically. The results show that the Haversian canal (HC) size increases and the osteon wall thickness (OWT) decreases significantly in the aged group, whereas a nonsignificant difference is found in tissue properties. The crack initiation (Jic) and crack growth (Jgrow) toughness of the aged group are found to be significantly lower (p<0.01) than the young group in the transverse orientation; however, for the longitudinal orientation, only the value of Jic in the aged group is found significantly lower. Further, a 4-phase XFEM (based on micro-CT image) model is developed to investigate the crack propagation behaviour in both orientations. For the transverse orientation, results show that in the aged group, the crack initially follows the cementline and then penetrates the osteon, whereas, in the young group, it propagates along the cementline. These results are in agreement with experimental results where the decrease in Jgrow is more significant than the Jic in the aged group. This study suggests that ageing leads to a larger HC and reduced OWT, which weakens the crack deflection ability and causes fragility fracture. Further, the XFEM results indicate that the presence of a small microcrack in the vicinity of a major crack tip causes an increase in the critical stress intensity factor.

Load-to-failure characteristics of patellar tendon allograft superior capsule reconstruction compared with the native superior capsule.

BackgroundThe potential use of a patellar tendon allograft for superior capsular reconstruction has been demonstrated biomechanically; however, there are concerns regarding compromised fixation strength owing to the longitudinal orientation of the fibers in the patellar tendon. Therefore, the purpose of this study was to compare the fixation strength of superior capsule reconstruction using a patellar tendon allograft to the intact superior capsule.MethodsThe structural properties of the intact native superior capsule (NSC) followed by superior capsular reconstruction using a patellar tendon allograft (PT-SCR) were tested in eight cadaveric specimens. The scapula and humerus were potted and mounted onto an Instron testing machine in 20 degrees of glenohumeral abduction. Humeral rotation was set to achieve uniform loading across the reconstruction. Specimens were preloaded to 10 N followed by cyclic loading from 10 N to 50 N for 30 cycles, then load to failure at a rate of 60 mm/min. Video digitizing software was used to quantify the regional deformation characteristics.ResultsDuring cyclic loading, there was no difference found in stiffness between PT-SCR and NSC (cycle 1 – PT-SCR: 12.9 ± 3.6 N/mm vs. NSC: 22.5 ± 1.6 N/mm; P = .055 and cycle 30 – PT-SCR: 27.3 ± 1.4 N/mm vs. NSC: 25.4 ± 1.7 N/mm; P = .510). Displacement at the yield load was not significantly different between the two groups (PT-SCR: 7.0 ± 1.0 mm vs. NSC: 6.5 ± 0.3 mm; P = .636); however, at the ultimate load, there was a difference in displacement (PT-SCR: 20.7 ± 1.1 mm vs. NSC: 8.1 ± 0.5 mm; P < .001). There was a significant difference at both the yield load (PT-SCR: 71.4 ± 2.2 N vs. NSC: 331.6 ± 56.6 N; P = .004) and the ultimate load (PT-SCR: 217.1 ± 26.9 N vs. NSC: 397.7 ± 62.4 N; P = .019). At the yield load, there was a difference found in the energy absorbed (PT-SCR: 84.4 ± 8.9 N-mm vs. NSC: 722.6 ± 156.8 N-mm; P = .005), but no difference in energy absorbed was found at the ultimate load.ConclusionsPT-SCR resulted in similar stiffness to NSC at lower loads, yield displacement, and energy absorbed to ultimate load. The ultimate load of the PT-SCR was approximately 54% of the NSC, which is comparable with the percent of the ultimate load in rotator cuff repair and the intact supraspinatus at time zero.

Progress in the esophagogastric anastomosis and the challenges of minimally invasive thoracoscopic surgery.

The esophagogastric anastomosis is most commonly performed to restore digestive tract continuity after esophagectomy for cancer. Despite a long history of clinical research and development of high-tech staplers, this procedure is still feared by most surgeons and associated with a 10% leakage rate. Among specific factors that may contribute to failure of the esophageal anastomosis are the absence of serosa layer, longitudinal orientation of muscle fibers, and ischemia of the gastric conduit. It has recently been suggested that the gut microbiome may influence the healing process of the anastomosis through the presence of collagenolytic bacterial strains, indicating that suture breakdown is not only a matter of collagen biosynthesis. The esophagogastric anastomosis can be performed either in the chest or neck, and can be completely hand-sewn, completely stapled (circular or linear stapler), or semi-mechanical (linear stapler posterior wall and hand-sewn anterior wall). Because of the lack of randomized clinical trials, no conclusive evidence is available, and the debate between the hand-sewn and the stapling technique is still ongoing even in the present era of robotic surgery. Centralization of care has improved the overall postoperative outcomes of esophagectomy, but the esophagogastric anastomosis remains the Achille’s heel of the procedure. More research and network collaboration of experts is needed to improve safety and clinical outcomes.

Promoting Neuronal Outgrowth Using Ridged Scaffolds Coated with Extracellular Matrix Proteins.

Spinal cord injury (SCI) results in cell death, demyelination, and axonal loss. The spinal cord has a limited ability to regenerate, and current clinical therapies for SCI are not effective in helping promote neurologic recovery. We have developed a novel scaffold biomaterial that is fabricated from the biodegradable hydrogel oligo(poly(ethylene glycol)fumarate) (OPF). We have previously shown that positively charged OPF scaffolds (OPF+) in an open spaced, multichannel design can be loaded with Schwann cells to support axonal generation and functional recovery following SCI. We have now developed a hybrid OPF+ biomaterial that increases the surface area available for cell attachment and that contains an aligned microarchitecture and extracellular matrix (ECM) proteins to better support axonal regeneration. OPF+ was fabricated as 0.08 mm thick sheets containing 100 μm high polymer ridges that self-assemble into a spiral shape when hydrated. Laminin, fibronectin, or collagen I coating promoted neuron attachment and axonal outgrowth on the scaffold surface. In addition, the ridges aligned axons in a longitudinal bipolar orientation. Decreasing the space between the ridges increased the number of cells and neurites aligned in the direction of the ridge. Schwann cells seeded on laminin coated OPF+ sheets aligned along the ridges over a 6-day period and could myelinate dorsal root ganglion neurons over 4 weeks. This novel scaffold design, with closer spaced ridges and Schwann cells, is a novel biomaterial construct to promote regeneration after SCI.

On the Structural Peculiarities of Self-Reinforced Composite Materials Based on UHMWPE Fibers.

The structure of self-reinforced composites (SRCs) based on ultra-high molecular weight polyethylene (UHMWPE) was studied by means of Wide-Angle X-ray Scattering (WAXS), X-ray tomography, Raman spectroscopy, Scanning Electron Microscopy (SEM) and in situ tensile testing in combination with advanced processing tools to determine the correlation between the processing conditions, on one hand, and the molecular structure and mechanical properties, on the other. SRCs were fabricated by hot compaction of UHMWPE fibers at different pressure and temperature combinations without addition of polymer matrix or softener. It was found by WAXS that higher compaction temperatures led to more extensive melting of fibers with the corresponding reduction of the Herman’s factor reflecting the degree of molecular orientation, while the increase of hot compaction pressure suppressed the melting of fibers within SRCs at a given temperature. X-ray tomography proved the absence of porosity while polarized light Raman spectroscopy measurements for both longitudinal and perpendicular fiber orientations showed qualitatively the anisotropy of SRC samples. SEM revealed that the matrix was formed by interlayers of molten polymer entrapped between fibers in SRCs. Moreover, in situ tensile tests demonstrated the increase of Young’s modulus and tensile strength with increasing temperature.

Crushing mechanical responses of natural wood columns and wood-filled composite columns

Composite structures with high crushing characteristics are drawing great attention in the structuraldesign due to their excellent lightweight and high strength. This paper aims to investigate mechanical responses of natural wood columns and wood-filled aluminum or carbon fiber reinforced plastics (CFRP) columns under axial crushing load. Parametric studies are performed on the material of the external wall, the grain orientations (longitudinal, tangential, and radial) and the growth rings’ gradient of the wood (Toona Sinensis) by experimental test. Experimental results show that grain orientations of the wood and the material of the external wall have remarkable influences on the collapse mode and the crushing force, and the wood column with longitudinal grain orientation presents the best energy absorption. In addition, the plastic buckling process, collapse mode and crushing force response of wood-filled composite specimens are comprehensively investigated under axial crushing load. It is found that wood-filled aluminum composite columns present progressive collapse mode and higher crushing force level than wood-filled CFRP composite columns. Furthermore, the synergistic behavior between the external wall and wood filler is evaluated. This study offers insights on designing novel energy absorber with high crashworthiness capacity by applying novel wood fiber materials.

Use of polymer concrete for large-scale 3D printing

Purpose This paper aims to focus on the evaluation of a polymer concrete as a three-dimensional (3D) printing material. An associated company has developed plastic concrete made from reused unrecyclable plastic waste. Its intended use is as a construction material. Design/methodology/approach The concrete mix, called PolyBet, composed of polypropylene and glass sand, is printed by the fused deposition modelling process. The process of material and parameter selection is described. The mechanical properties of the filled material were compared to its cast state. Samples were made from castings and two different orientations of 3D-printed parts. Three-point flex tests were carried out, and the area of the break was examined. Computed tomography of the samples was carried out. Findings The influence of the 3D printing process on the material was evaluated. The mechanical performance of the longitudinal samples was close to the cast state. There was a difference in the failure mode between the states, with cast parts exhibiting a tougher behaviour, with fractures propagating in a stair-like manner. The 3D-printed samples exhibited high degrees of porosity. Originality/value The results suggest that the novel material is a good fit for 3D printing, with little to no degradation caused by the process. Layer adhesion was shown to be excellent, with negligible effect on the finished part for the longitudinal orientation. That means, if large-scale testing of buildability is successful, the material is a good fit for additive manufacturing of building components and other large-scale structures.

Stage-dependent sequential organization of nascent smooth muscle cells and its implications for the gut coiling morphogenesis in Xenopus larva

In vertebrates, gut coiling proceeds left-right asymmetrically during expansion of the gastrointestinal tract with highly organized muscular structures facilitating peristalsis. In this report, we explored the mechanisms of larval gut coiling morphogenesis relevant to its nascent smooth muscle cells using highly transparent Xenopus early larvae. First, to visualize the dynamics of intestinal smooth muscle cells, whole-mount specimens were immunostained with anti-smooth muscle-specific actin (SM-actin) antibody. We found that the nascent gut of Xenopus early larvae gradually expands the SM-actin-positive region in a stage-dependent manner. Transverse orientation of smooth muscle cells was first established, and next, the cellular longitudinal orientation along the gut axis was followed to make a meshwork of the contractile cells. Finally, anisotropic torsion by the smooth muscle cells was generated in the center of gut coiling, suggesting that twisting force might be involved in the late phase of coiling morphogenesis of the gut. Administration of S-(–)-Blebbistatin to attenuate the actomyosin contraction in vivo resulted in cancellation of coiling of the gut. Development of decapitation embryos, trunk ‘torso’ explants, and gut-only explants revealed that initial coiling of the gut proceeds without interactions with the other parts of the body including the central nervous system. We newly developed an in vitro model to assess the gut coiling morphogenesis, indicating that coiling pattern of the nascent Xenopus gut is partially gut-autonomous. Using this gut explant culture technique, inhibition of actomyosin contraction was performed by administrating either actin polymerization inhibitor, myosin light chain kinase inhibitor, or calmodulin antagonist. All of these reagents decreased the extent of gut coiling morphogenesis in vitro. Taken together, these results suggest that the contraction force generated by actomyosin-rich intestinal smooth muscle cells during larval stages is essential for the normal coiling morphogenesis of this muscular tubular organ.