Outer Wall Thickness Research Articles

Genomic characterization and comparative genomics of Chlorella sp. CH2018 from Musi River water, India

Microalgae, a diverse class of photosynthetic eukaryote, can provide food and energy sustainably. Selecting productive strains is crucial for commercial viability. Here, we isolated an axenic microalgal species from Musi River water, and based on its morphology, molecular makeup, and cell wall composition identified it as Chlorella sp. CH2018. Scanning electron microscopy was used to measure the size of cells, which were found to be 3-, 4-, or 5-μm in diameter with a discernible thick outer cell wall. The characterization of algal genomes is imperative for comprehending species, studying metabolic pathways, and modifying genetics. In this study, we sequenced the entire genome of Chlorella sp. CH2018, yielded genome size of 56.83 Mb with 11,143 functionally annotated protein-coding gene models. The Gene Ontology (GO) analysis revealed that Chlorella's predominant metabolic pathway is carbohydrate metabolism. Ortholog comparative analysis of species of phylum Chlorophyta with Chlorella sp. CH2018 showed that the isolated species possesses unique protein families with a maximum number of 6292 ortholog groups with Chlorella sorokiniana. The phylogenetic tree created by concatenating single-copy ortholog sequences demonstrates the uniqueness of Chlorella sp. CH2018, and its genome sequence serves as a genetic resource for future research.

Crash resistance analysis and optimization of sponge like thin-walled pipes under multiple working conditions

The crashworthiness of bionic thin-walled structures has been the subject of considerable research interest. In this article, we emulate the bi-diagonal skeletal structure of deep-sea glass sponges and construct sponge-like multicellular thin-walled tubes (SLMTT) with a parameterized ratio of the number of two distinct single-celled organisms (CSS I and CSS II). Thin-walled sponge-like tubes of varying dimensions were manufactured using selective laser melting (SLM) technology. The crashworthiness of these structures was evaluated under axial compression, transverse compression, and three-point bending conditions through experimental and computational approaches, including parametric analyses of the inner and outer wall thicknesses. The results show that SLMTT I has better crashworthiness under the three working conditions, and the SEA of BLMESI is 40.9 and 26.13% higher than that of BLMESII. under transverse compression and three-point bending conditions, respectively. Finally, a multi-objective optimization design of SLMTT I under multiple operating conditions is carried out by the second generation of Non-dominated Sorting Genetic Algorithm (NSGA-II) with the aim of obtaining the ideal structure with maximum specific energy absorption and minimum initial peak crushing force. This study offers novel insights into the design of bionic energy-absorbing structures under diverse operational scenarios.

Model Test on Acoustic Emission Monitoring of Loess Slope Failure.

The three stages of loess collapse are characterized by notable concealment and sudden onset due to the sudden nature of loess collapse and the prolonged duration of the peristaltic deformation stage. Traditional displacement monitoring methods struggle to detect early signals of instability and failure, leading to poor timeliness in disaster warnings. This project begins by examining non-force field information related to the loess collapse process. It focuses on acoustic emission monitoring and employs model tests to identify effective waveguide rods for monitoring loess collapse. Additionally, the project investigates the evolution anomalies of acoustic emission parameters before and after loess collapse failure, aiming to establish early warning criteria for loess collapse based on acoustic emission. This work provides a theoretical basis for monitoring and early warning of loess collapses. This study evaluates five parameters of the active waveguide system: sensor installation method, filling material, waveguide rod wall thickness, outer wrapping material, and outer wrapping wall thickness. The densities of the filler materials were tested using the optimal parameters derived from the tests to identify the best configurations for active acoustic emission (AE) waveguide systems suitable for monitoring loess collapse. Subsequently, a one-sided connected loess collapse model was employed for indoor tests, integrating real-time AE monitoring with the active waveguide method. This model facilitates the exploration of AE response characteristics during loess collapse and the analysis of destructive forms of loess collapse and time-sequence evolution of AE ringing counts throughout the deformation and destruction process. Results indicate that using filler materials with high elasticity modulus, high compactness, and low Poisson's ratio, along with thin outer wrapping and waveguide rod walls, leads to strong AE signals. As deformation damage of loess collapse intensifies, the number of AE ringing counts notably increases. A rapid rise in cumulative ringing counts can indicate a "sudden increase", or the b-value may stabilize, providing precursor information for loess collapse.

Influence of input parameters on the measurement accuracy of external clamp-on ultrasonic flowmeters: An experimental study

Abstract This study comprehensively evaluated the performance of clamp-on ultrasonic gas flowmeters at a natural gas field. The research focused on the influence of key input parameters on flow measurement accuracy during practical application of the instrument and proposed specific measures to improve measurement results. It was found that errors in outer diameter and wall thickness not only lead to flow calculation inaccuracies but also directly impact the propagation path of ultrasonic waves. Therefore, accurate input parameters are crucial to ensure precise flow results. Additionally, the study revealed that changes in installation distance have minimal effects on flow measurement results and adjustments can be made as needed to obtain better signal parameters. Variations in input temperature and pressure mainly affect the conversion coefficient from operating conditions to standard conditions, with minor impacts on flow velocity and operating flow rate. Thus, the velocity ratio method can be considered during on-site calibration to mitigate the effects of temperature and pressure changes.

Variability of morphometric characteristics of cerebral arteries in children aged 3-7 years

Objective: to identify bilateral and sexual variability, as well as the average morphometric characteristics of the cerebral arteries in children during the first childhood are normal. Material and methods. The material for the study was samples of brain arteries obtained during autopsy of 35 children 3-7 years old. Transverse millimeter sections of the anterior (АСА), wedge-shaped parts of the middle (MCA), pre-communication segments of the posterior cerebral (PCA), intracranial parts of the vertebral arteries (VA) and cerebral internal carotid arteries (ICA) under a microscope determined the external diameter, wall thickness, internal diameter. Results. The above parameters of the arteries in the right and left hemispheres of the brain ranged from 0.2 to 7.9% (p>0.05); in boys and girls — from 0.5 to 15.4% (p>0.05). The average values of the outer diameter, wall thickness and inner diameter were: ICA—2.65±0.04, 0.16±0.005 and 2.33±0.04 mm; АСА— 1.90±0.02, 0.14±0.004 and 1.61±0.03 mm; MCA—2.25±0.03, 0.15±0.005 and 1.95±0.03 mm; PCA— 1.81±0.03, 0.14±0.004 and 1.54±0.03 mm; VA —2.23±0.03, 0.16±0.005 and 1.91±0.04 mm. Conclusion. In the first period of childhood, bilateral and sexual differences in the value of the studied parameters of ICA and main cerebral arteries were not found. In this regard, arterial mean values are presented excluding sex and arterial circle side. In the first period of childhood, the lumen of АСА is 86.0%, MCA—80.4%, PCA—79.0%, VA—79.9% of the size of similar arteries in an adult.

Shear failure characteristics and stress-strain relationship of Moso bamboo parallel to the fibers

Bamboo is susceptible to longitudinal splitting, which is mainly driven by its shear properties parallel to the fibers. In this work, bowtie tests including 124 Moso bamboo internode and node specimens were conducted to investigate the shear behaviors of Moso bamboo in shear parallel to the fibers. Based on the test results, the difference in shear strength between internode and node specimens using the analysis of variance (ANOVA) was quantitatively evaluated. The distribution of shear strength was fitted using Normal, Log-normal, and Weibull distributions, and the corresponding standard value was calculated using the non-parametric method. The design value was obtained based on reliability analysis. Additionally, prediction formulas for shear strength were fitted using univariate and multiple regression analyses based on outer diameter, wall thickness, and density. Various shear stress-strain constitutive models were established and validated. The research results indicated that there is no statistically significant difference in shear strength between internode and node specimens with the value of 17.17 MPa and 17.48 MPa, respectively. The distribution of shear strength followed the Normal and Log-normal distributions, but not the Weibull distribution. The standard value and design value of shear strength were 14.91 and 9.47 MPa, respectively. The shear strength was found to be negatively correlated with the outer diameter and wall thickness, but positively correlated with the density. The recommended strength prediction formulas and stress-strain constitutive models match well with the test results. This study can serve as a reference for the improvement of bamboo standard and design basis of Moso bamboo.

Crashworthiness design of additively manufactured lattice-reinforced sandwich tube

A body-centered cubic lattice reinforced sandwich tube structure is designed, and the specimens are prepared using Selective laser melting (SLM) technology with integrated printing and split assembly. The effects of inner and outer wall thickness, loading rate and interaction on the deformation pattern and crashworthiness of the structures were investigated through experiments and numerical simulations. The results indicate that when subjected to axial compression, the integrated printed lattice reinforced sandwich tube (IPLT) forms more folds, and its specific energy absorption increases by 17.61% in comparison to the split assembly lattice filled sandwich tube (SALT). Under transverse compression, the integrated printed lattice reinforced sandwich tube showed no separation of the lattice from the thin-walled tube, and the specific energy absorption increased by 103.78% compared with the split assembly structure. It is noteworthy that the specific energy absorption of the designed reinforced sandwich tube under axial compression (transverse compression) increased by 294.83% (1233.95%) compared with the outer thin-walled tubes. This paper provides new ideas for the production of energy-absorbing components that are light-weight and have good crashworthiness.

The structural organization of the outer tissues in the gametophytic stem of the umbrella moss Hypnodendron menziesii optimizes load bearing.

The ultrastructural design and biochemical organization of the significantly thickened outer tissues of the gametophytic stem of Hypnodendron menziesii optimizes load bearing of the stem. Hypnodendron menziesii is a bryoid umbrella moss growing in high humid conditions on the forest floors of New Zealand. The erect gametophyte bears up to eight whorls of branches in succession, spreading across the stem that bears the heavy weight of branches with highly hydrated leaves. Our investigation using a combination of light microscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and TEM-immunolabeling techniques provided novel information on the structural design and biochemical organization of greatly thickened cell walls of epidermal, hypodermal, and outermost cortical tissues, comparing underlying thin-walled cortical tissues in the gametophytic stem. Probing into the ultrastructure of the cell wall architecture of these target tissues by TEM and SEM revealed the cell walls to display a multilamellar organization, in addition to demonstrating the presence of an electron-dense substance in the cell wall, presumably flavonoids. The pattern of distribution and concentration of rhamnogalacturonan, homogalacturonan, and heteromannan, as determined by immunogold labeling, suggests that it is the combination of structural and molecular design of the cell wall that may optimize the mechanical function of the epidermal, hypodermal, and outer cortical tissues. Statistical relationships between the overall thickness of epidermal, hypodermal, and outer cortical cell walls, the lumen area of cells and the percentage area of cell wall occupied in these tissues at different heights of the stem, and thickness of secondary cell wall layers (L1-L4/5) were explored. The results of these analyses unequivocally support the contribution of outer tissues to the mechanical strength of the resilient stem.

Analysis of variance and grey relational analysis application methods for the selection and optimization problem in 6061-T6 flange friction stir welding process parameters

A study was carried out to investigate and enhance the effects of friction stir welding on the mechanical characteristics of a flange composed of 6061-T3 aluminum alloy. The pipes possess an outer diameter and wall thickness of 6 mm, while the plates are sized at 100 x 100 × 6 mm. Nine unique experiments were planned using the Taguchi orthogonal array method, with the welding tool remaining constant. Three independent variables (travel speed, rotation speed, and shoulder diameter) were altered at three different levels for each variable. The research analyzed the influence of various FSW factors on the weld flange joint. Analysis of variance (ANOVA) and grey relational analysis (GRA) were employed to determine the impact of each FSW underwater parameter. Moreover, the statistical Taguchi technique (TM) was used to predict the optimal combination of welding parameters to improve tensile properties, including tensile strength (UTS), yield strength (YS), elongation (EI%), and bending load (BL) of welded joints. Additionally, the actual tests demonstrated a high level of agreement with the results obtained from the proposed mathematical model. The validation results obtained indicate that the optimization method is a dependable tool for enhancing the quality responses of friction stir welding.

Morphological, physiological and anatomical traits in durum wheat (Triticum durum Desf.) as affected by semi-arid conditions

Durum wheat (Triticum durum Desf.) is one of Algeria's primary cereal crops. Although the areas reserved for this species are estimated at approximately 40%, the production remains low to meet national grain requirements. This shortfall is primarily due to the impact of biotic and abiotic stresses, particularly drought, which significantly limit wheat yields. For that, this study assessed the behavior of five genotypes of durum wheat (Waha, Acsad1361, Vitron, Oued Zenati and Langlois) under water stress conditions. The experiment was carried out in Tiaret (Western Algeria). The studied parameters are morpho-physiological and anatomical of the flag leaf. The obtained results showed that the water deficit greatly affected the dimensions of the plant and triggered a decrease in the water content. Structural modifications due to cellular resizing of the structural constituents of the last leaf, reflected by variations in the rate of the outer epidermal wall thickness and reductions of leaf mesophiles. These modifications remain effective in maintaining the hydration of the aerial part by limiting water loss and increasing the hydraulic resistance of the leaves. According to this study, it seems that an inter-varietal difference has been highlighted. However, a genetic cross is recommended to combine the maximum number of resistant genes into a single variety. This strategy is considered as an effective solution for mitigating the effects of abiotic stresses, especially in semi-arid regions.

A conjugate heat transfer investigation of outer-wall cooling performance in double-wall vane pressure side

Double wall cooling has significant potential for high-pressure turbine vane cooling technology. Geometric parameters of the double-wall vane play a crucial role in determining the cooling performance. This paper presents a double-wall cooling model with five outer wall thicknesses and three injection angles, using the curvature of the actual pressure side of the engine as a reference. The overall cooling effectiveness is investigated over the range of blowing ratio from 0.5 to 2.5. Results indicate that, at injection angles of 20° and 30°, an outer-wall thickness of 1.5D f maximizes the combined benefits of film cooling and thermal conductivity in solid domains. At an injection angle of 40°, the blowing ratio becomes a determining factor in selecting the optimal outer wall thickness. Additionally, a reasonable arrangement of pin fins promotes a more uniform outer wall temperature distribution. A thinner outer wall at higher blowing ratios provides optimum overall cooling effectiveness.

Adaptive Morpho-Anatomical Characteristics of Leaves and Cones in Juniperus seravschanica Kom.: Studies of Polyphenolic Parenchyma Cells, Secretory Tissues, Sclereids and Tracheids

Conifers are long-lived species that cope with multiple abiotic and biotic stresses. To defend themselves, they have evolved a wide array of morphological, anatomical and chemical traits. Morpho-anatomical traits of Juniperus seravschanica, particularly in male and female cones, have not been studied. Thus, in this survey, these structures were studied to investigate the adaptative traits. The species is frost- and drought-tolerant and grows at a 2200-3800 m altitude on normal, chalky, calcareous, rocky, and mountainous outcrops with other species or as pure patches. The seedlings and young plant leaves were small and needle-like, while the main leaves of adult plants were scale-like and overlapping; there was a conspicuous resin gland (duct) in the outer surface of scale-like leaves secreting a white and sticky resinous substance, particularly in damaged leaves. The epidermis was thick with thicker outer walls and sunken stomata; the hypodermis showed 1-3 layers of lignified cells with a narrow lumen. The palisade parenchyma was observed on both sides. Sclereids, phenolic- and starchy cells were observed in leaves, particularly scale-like ones. Male cones were small with overlapping and decussate scales, in which resin glands (ducts) and phenolic cells were also observed. Similarly, female cones had overlapping and decussate scales converting to fleshy, berry-like, and bluish appearance during development. They revealed the presence of several resin glands, a thick epidermis, phenolic cells in young cones, and numerous sclereid cells in mature cones. Tracheids were narrow in leaves and cones. The features such as high sclerophylly, resin glands, phenolic cells, narrow tracheids, sunken stomata, increasing thickness of the epidermis, cuticle, hypodermis, as well as the presence of palisade parenchyma on both sides enable the species to survive in hard conditions.

Coaxial 3D printed Al2O3 ceramic continuous-flow fixed-bed reactor with bionic core-shell structure

Continuous-flow fixed-bed reactors (CFBR) have attracted considerable attention owing to their high efficiency and low energy consumption; however, the integrated fabrication of CFBR with core-shell structures remains a great challenge at present. Herein, a facile coaxial three-dimensional (3D) printing strategy was developed for the first time to rapidly and efficiently construct a CFBR with Al2O3 powder and aluminum dihydrogen phosphate (AP) as the outer shell ink, and Al2O3 powder, AP, and polymethyl methacrylate as the inner core ink that is extruded through a customized coaxial needle. Coaxial 3D printing realizes the integral fabrication of ceramic shells and inner porous ceramic carriers. CFBR with an outer wall thickness of 1.2 mm, core diameter of 3.7 mm, and variable length were fabricated, which were enabled with excellent catalytic properties by simply impregnating precious metal particles. The catalytic efficiencies for the reducing of 4-nitrophenol (4-NP) in the 3-cm-length Pd/CFBR, Pt/CFBR, and Ag/CFBR were found 96.9 %, 97.4 %, and 93 % after 10 min, respectively. Combining integrated fabrication, rapid prototyping, and complex architecture formation, coaxial 3D printing provides a novel strategy for directly integrating multifunctional CFBR.

Positive Echocardiographic Association between Carotid Artery and Coronary Artery Diameter and Z-Score in a Mouse Model of Kawasaki Disease.

LCWE was intraperitoneally injected into 5-week-old male C57BL/6 mice to induce CALs. We studied the longitudinal status of the carotid and coronary arteries and analyzed the Z-score of coronary artery diameter. Carotid artery wall thickness (day 7) and diameter (day 14) significantly increased in the LCWE group with a dose-dependent effect (p < 0.05). Aortic diameter and wall thickness demonstrated significant increases on day 28 and day 7, respectively (p < 0.05). Carotid artery outer diameter and wall thickness were positively associated with coronary artery diameter on day 28 (p < 0.01). Coronary artery diameter significantly increased in the LCWE group after day 7 (p < 0.05). The percentage of Z > 3.0 indicated was more than 80% in the high-dose LCWE group and 0% in the control group. This report is the first to use coronary artery Z-score in a mouse model of KD by echocardiography and to find a positive association between carotid artery and coronary artery diameter.

Experimental research and engineering application on bearing capacity of concrete-filled steel tube circular arch

The bearing property and deformation failure law of the CFST circular arch were investigated in order to provide direction for the optimization of the concrete-filled steel tube (CFST) support. The flexural bearing capacity test of the 194 mm × 10 mm CFST was performed initially in this study. It was primarily explored how bearing capacity and deformation of circular arches were affected by the slip of the arch foot and anti-bending strengthening, and the neutral layer migration rule and anti-bending strengthening mechanism of circular arches were examined. The bearing performance of the circular arch under the condition of the concentrated load of the vault and the usual uniform load of the entire span is then simulated in an orthogonal test by numerical simulation in order to extend the experimental investigation. The effect of variables including the steel tube’s outer diameter, thickness, slip of the arch foot, and the ratio of the arch rise to span on the bearing capacity of the circular arch is examined. The study demonstrates that under focused stress on the arch top or full-span normal uniform loading, the arch foot slip is the most important element impacting the CFST support’s bearing capacity. In steel tubes with the same outer diameter and wall thickness, the vector span ratio has a bigger influence than anti-bending strengthening. When the span ratio is the same, the influence of the outer diameter and wall thickness are equal and outweigh the influence of bending strengthening. The circular arch with an outside diameter of 168 mm, a wall thickness of 10 mm, and a rise-span ratio of 0.207 has the best performance characteristics under the influence of concentrated load, and the ultimate failure mechanism is local waist drum deformation failure. Based on the aforementioned study findings, the circular CFST support’s buckling deformation and drum deformation are examined, and a composite support consisting of “anchor net spray + CFST support” is directed for the north three deep track downhill of Yangcheng Coal Mine. Two failure types expose the failure mechanism and provide a technique for optimization. The support had contributed to the circular CFST arc arch’s best bearing performance in the event of waist drum deformation and failure.

Can combined high-resolution vessel wall imaging and multiple post-labeling delay 3D pseudo-continuous arterial spin labeling differentiate moyamoya disease from atherosclerotic moyamoya syndrome?

PurposeTo investigate whether moyamoya disease (MMD) and atherosclerotic moyamoya syndrome (AS-MMS) differ in vascular morphology and perfusion characteristics using T1w-CUBE imaging and multiple post-labeling delay 3D pseudo-continuous arterial spin labeling imaging (MP 3D-PcASL), and to explore the potential of the combined techniques for accurate diagnosis of both diseases. MethodThis prospective study enrolled 51 patients with moyamoya vasculopathy, including 26 with MMD and 25 with AS-MMS. All patients underwent digital subtraction angiography (DSA)/magnetic resonance angiography (MRA), T1w-CUBE imaging, and MP 3D-PCASL examinations. Morphological parameters, including the outer diameter, maximum wall thickness, luminal stenosis morphology, degree of wall enhancement, number of collateral vessels, and perfusion parameters, such as cerebral blood flow (CBF) and arterial transit time (ATT), were measured. After univariate analysis between the two groups, logistic regression models based on the derived parameters of T1w-CUBE imaging, MP 3D-PCASL, and combined imaging were implemented, and receiver operating characteristic (ROC) curves were generated to compare the discriminatory power of the different imaging methods for the diagnosis of MMD. ResultsWith T1w-CUBE imaging, MMD showed a smaller outer diameter (2.76 ± 0.39 vs. 3.07 ± 0.49 mm) and maximum wall thickness (1.27 ± 0.19 vs. 1.49 ± 0.24 mm) than AS-MMS (both P < 0.05). Using MP 3D-pcASL, the resultant CBF (36.64 ± 14.28 vs. 28.77 ± 8.63 mL/100 g/min) was higher in MMD relative to AS-MMS, while an opposite pattern was shown for ATT (1.61 ± 0.09 vs. 1.72 ± 0.13 s; both P < 0.05). Robust diagnostic efficacies for disease differentiation, confirmed by high areas under the ROC curve (AUCs) (>0.808), were separately shown with T1w-CUBE and MP 3D-pcASL derived parameters. However, the combined multivariate logistic regression model showed optimaldiagnostic efficacy(AUC: 0.938; P < 0.05). ConclusionsCombined T1w-CUBE imaging and MP 3D-PCASL provides distinctive morphological and functional features to evaluate vessel walls and cerebral perfusion, and might help distinguish MMD from AS-MMS.

Forming characteristics of thin-walled tubes manufactured by free bending process-based nontangential rotation bending die

The free-bending process of a metal tube involves a geometric relationship between the eccentricity, the rotation angle of the bending die, the deformation zone length, and the bending radius. Ideally, during the forming process, the contact position between the bending die, and the outer bend of the tube remains tangent. However, due to factors such as the clearance of the bending die and material properties, the rotation angle can be adjusted within a specific range while still ensuring smooth tube formation. The tangential state is disrupted when the rotation angle changes, resulting in overbending or underbending. Thus, in this study, a new theoretical analysis of the free bending process, accounting for clearance, was developed to analyze the material flow and changes in the bending radius during the nontangential contact between the bending die and the tube. In addition, the reasons for achieving smooth tube bending even after adjusting the rotation angle were explained, and the deformation mechanism of the tube under the combined effects of additional tangential force from the bending die and axial propulsive force was analysed. Furthermore, the impact of the rotation angle on the bending radius and the displacement of the strain neutral layer (strain NL) was determined. Afterwards, finite element (FE) modeling and forming experiments were conducted to verify the proposed theoretical analysis under different deformation zone lengths and eccentricities conditions. Besides, the distribution of the inner and outer wall thicknesses of the tube under the nontangential rotation of the bending die was further analysed. The simulation and experimental results fit well with that obtained from theoretical analysis.

Does leaf morphoanatomy corroborate systematics and biogeographic events in the Paleotropical genus Acridocarpus (Malpighiaceae)?

The Paleotropical genus Acridocarpus stands out among the lineages recovered in the most recent phylogeny of the Malpighiaceae. Its 30 species occur disjunctively in Africa and only one species in New Caledonia, exhibiting a coincidence between the period of dispersion/diversification with the increase of arid areas in Africa. This study aims to investigate whether the anatomical leaf of the Acridocarpus can support the hypothesis of diversification of the genus in response to environmental, besides the contribution to systematic approaches. Leaves from 21 species were submitted to the usual methodologies for analysis under light microscope. Coded anatomical characters were also mapped in the phylogenetic tree of Acridorcarpus. Ericoid leaves, compact mesophyll, adaxial epidermis with elongated cells, epidermal cells with thick outer periclinal walls, were found in most species. These xeromorphic features would be correlated to the arid environments where the species occurs. The presence, distribution, and position of nectaries on the leaf, the contour of both petiole and midrib, the conformation of both petiole and midrib vascular system, the presence of sheath extending laterally between the palisade and spongy parenchyma, the presence and location of druse crystal in the petiole and mesophyll, the presence of stomatal ridges and distribution of stomata on the blade were recognized as useful characters for the taxonomy that contribute to the interspecific distinction. The lateral extension of the bundle sheath in the mesophyll was interpreted as a synapomorphy for the genus and amphistomatic leaves were considered an autapomorphy in A. spectibilis. These findings allowed the construction of an identification key and may contribute to new evolutionary interpretations in Malpighiaceae.

Investigations into 3D-printed nautiloid-inspired pressure housings

The shell of the chambered nautilus is one of the few examples in nature of a biologically derived one-atmosphere pressure housing, which the animal uses to maintain neutral buoyancy via a series of sealed chambers. Extant species such as Nautilus pompilius live at depths from 200 to 800 m, and similar depth ranges have been hypothesized for their hyper diverse but extinct relatives, the ammonoids. Given the evolutionary success of these molluscan clades, their complex shell morphologies may reveal pressure-tolerant geometries comparable to the ‘ideal’ ones currently used in deep-sea marine robotics: simple spheres and cylinders, which have minimized surface area to volume ratio and easier manufacturability. We modeled and empirically tested 3D-printed bioinspired pressure housings for deep-sea applications using high resolution stereolithography 3D printing. These designs were modeled on the shells of N. pompilius and were compared to conventional 3D-printed spheres with similar wall thicknesses and implodable volumes. Two nautilus-inspired models with internal supports designed after their septal walls (one concave, one convex) had a higher-pressure tolerance compared to hollow models, but none outperformed spherical models with the same outer-wall thickness. Although spheres outperform the nautilus-inspired housings, the methods developed here show that pressure housings with complex geometries can be printed by additive manufacturing and empirically tested. From a biological perspective, this method can be a new tool for empirically testing viable depth tolerances for extinct coiled cephalopod morphologies.

Experimental study and numerical analysis on the dynamic response of steel tube confined concrete with a circular hollow section (STCC-CHS) under transverse impact loading

The dynamic response to lateral impact of steel tube confined concrete with a circular hollow section (STCCCHS) was investigated via pendulum impact tests in the laboratory. Nine STCCCHS columns and two concrete-filled double skin steel tubes (CFDST) were tested under lateral impact. The hollow ratio, the thickness of the outer steel tube, the impact height, and axial load ratio were varied. The failure pattern was observed along with the time histories of the impact force and the mid-span deflection. Strain development in the outer steel tube was quantified. The failure mechanism was integral bending and local buckling under lateral impact. Increasing the outer wall thickness and adopting an appropriate hollow ratio can effectively improve the impact resistance of such columns. Changes in impact energy have a significant influence on the plastic deformation of the members. Modest axial loading has little effect on the impact resistance. The test results were used to tune a finite element simulation of the process. A whole dynamic response investigation of STCCCHS columns under impact loads was carried out, and compared with the impact resistance of CFDST columns.