A force-measuring and behaviour-recording system consisting of 24 individual 3D force plates for the study of single limb forces in climbing animals on a quasi-cylindrical tower

This study describes the design of a new force measuring array with a quasi-cylindrical surface for measuring the 3D ground reaction forces of animals climbing on a surface with high curvature. This force-measuring array was assembled from 24 individual 3D force sensors, each with a resolution at the millinewton (mN) level, which were installed from top to bottom in four columns and six rows, with sensors in neighbouring columns staggered in height. Three cameras were used to simultaneously record the climbing behaviours of animals (in these experiments tree frogs) on the cylinder-like force measuring array. We were thus able to simultaneously record the ground reaction forces of each of the four limbs of tree frogs (here six individuals of the Chinese gliding or flying frog, Rhacophorus dennysi, with forelimb spans in the range 163-201 mm) climbing or descending both smooth and rough surfaces on a quasi-cylindrical structure with an overall diameter of 79 mm. We describe the design and calibration of the individual force sensors, their installation and arrangement on the quasi-cylindrical climbing tower, the recording of ground reaction forces and climbing behaviour, data transformations necessitated by the angular relationship of neighbouring sensors, and data processing using MATLAB scripts. Additionally, we present preliminary data on the use of a clamping grip by climbing frogs and the existence of small pull-off forces that aid toe-pad detachment at the end of each locomotor stance phase.

Identification of key pathways and gene changes in primary pancreatic stellate cells after cross-talk with pancreatic cancer cells (BXPC-3) using bioinformatics analysis

It is well known that as the king of cancer, pancreatic ductal adenocarcinoma (PDAC) has relatively malignant biological behavior and poor prognosis. The interaction between pancreatic stellate cells and PDAC cells promotes the development of PDAC. The aim of this study was to describe gene characteristics in pancreatic stellate cell (PSCs) after cross-talked with BXPC-3 and unravel their underlying mechanisms. The expression profiling analysis of genes in PSCs was completed after co-cultured with primary BXPC-3 for 48h. The Kyoto Encyclopedia of Genes and Genomes pathway (KEGG) enrichment analysis and gene ontology (GO) analysis were performed, and the differentially expressed genes (DEGs) were identified by Agilent GeneSpring GX program. In total, 1804 DEGs were filtered out in PSCs, including 958 up-regulated genes and 846 downregulated genes. GO analysis showed that the up-regulated DEGs were significantly enriched in biological processes (BP) such as defense response, immune system process and immune response; the down-regulated DEGs were significantly enriched in biological regulation and cytoskeleton organization. KEGG pathway analysis showed that 28 pathways were upregulated and 5 were downregulated. By constructing PPI network, we selected out 10 key genes (IL6，IL8, IL1B, BCL2, CCL2, CSF2, KIT, ICAM1, PTPRC and IGF1) and significant enriched pathways. In conclusion, the current study suggests that the filtered DEGs contribute to our understanding of the molecular mechanisms underlying the interaction between PSCs and pancreatic cancer cells, and might be used as molecular targets to further the study the role of tumor microenvironment in the progression of PDAC.

Enhanced Adhesion of Carbon Nanotubes by Dopamine Modification

According to the fact that gecko-inspired vertically aligned carbon nanotubes (VA-CNTs) exhibit ultrastrong adhesion, dopamine is utilized to make a modification to this traditional biomimetic material. The composite material is tested for adhesion performance under different environmental conditions by an atomic force microscope. The adhesion force of the modified VA-CNTs does not show obvious fluctuation during the gradual heating process; however, the material gains improved adhesion when increasing the ambient humidity. In addition, the modified CNTs show a stronger adhesion force than the original CNTs in their performance tests. The dopamine polymer has a good combination with CNTs, which is responsible for the aforementioned excellent performance. Overall, this modification method is simple, convenient, efficient, and environmentally friendly, which all indicates a promising future in its application. The modified CNTs are expected to be used for super-adhesion in harsh environments, as well as in the field of microelectronics.

Prophage Diversity of 'Candidatus Liberibacter asiaticus' Strains in California

Huanglongbing (HLB) is a highly destructive citrus disease and is associated with a nonculturable bacterium, 'Candidatus Liberibacter asiaticus'. 'Ca. L. asiaticus' in the United States was first found in Florida in 2005 and is now endemic there. In California, 'Ca. L. asiaticus' was first detected in Hacienda Heights in Los Angeles County in 2012 and has now been detected in multiple urban locations in southern California. Knowledge of 'Ca. L. asiaticus' strain diversity in California is important for HLB management. In this study, genomic diversity among 10 'Ca. L. asiaticus' strains from six California locations were analyzed using a next-generation sequencing (NGS) (Illumina MiSeq and HiSeq) approach. Draft genome sequences of 'Ca. L. asiaticus' strains were assembled. Sequences of the 16S ribosomal RNA gene and nrdB confirmed 'Ca. L. asiaticus' identity. Prophages were detected in all 'Ca. L. asiaticus' strains. The California 'Ca. L. asiaticus' strains formed four prophage typing groups (PTGs): PTG1, with type 1 prophage only (strains from Anaheim, San Gabriel, and Riverside); PTG2, with type 2 prophage only (strains from Hacienda Heights); PTG1-3, with both type 1 and 3 prophages (a strain from Cerritos); and PTG1-2, with both type 1 and type 2 prophages (a strain from La Habra). Analyses of the terL sequence showed that all California 'Ca. L. asiaticus' strains were not introduced from Florida but likely from locations in Asia. Miniature inverted-repeat transposable elements were found in all 'Ca. L. asiaticus' strains, yet, a jumping-out event was detected in the 'Ca. L. asiaticus' strain from Cerritos. Altogether, this study demonstrated that the NGS approach focusing on prophage variation was sensitive and effective in revealing diversity of 'Ca. L. asiaticus' strains in California.

[Differential expressions analysis of piwi-interacting RNAs in hepatocellular carcinoma]

Objective: To investigates the role of piwi-interacting RNAs (piRNA) in the occurrence and development of hepatocellular carcinoma. Methods: Second-generation small RNA sequencing was performed on cancer and paracancerous tissues, metastatic and non-metastatic liver cancer tissues of patients with liver cancer, and the sequencing data were filtered out for the common RNA sequences to be repeated. The piRNA predictor was used to forecast the possible new piRNA merged with the downloaded known piRNA to screen out distinction. A miRanda algorithm was used to predict the corresponding target genes and functional enrichment analysis. piRNA was selected for experimental functional (migration) analysis. An independent t-test was used to compare means between the two groups. Results: 66 772 piRNAs (known 149) were obtained by sequencing. 241 piRNAs were found in cancer and paracancerous tissues, and 1 634 piRNAs were found in metastatic and non-metastatic tumors. Analysis of the GO and KEGG pathways of the target genes of differential piRNAs revealed that they were mainly involved in cell adhesion. An experimental functional analysis was performed on the selected Pirna (PIR1/97), which showed that it promoted the migration of hepatoma cells (LM3: t = 8.829, P < 0.05; PLC: t = 7.318, P < 0.05). Conclusion: The expression levels of piRNA in hepatocellular carcinoma patients with cancer and paracancerous tissues, metastasis and non-metastatic liver cancer tissues are different and it could be entailed in the metastasis process of hepatocellular carcinoma. Hence, experimental functional analysis is required for research and experimental confirmation.

Lateral undulation of the flexible spine of sprawling posture vertebrates

Sprawling posture vertebrates have a flexible spine that bends the trunk primarily in the horizontal plane during locomotion. By coordinating cyclical lateral trunk flexion and limb movements, these animals are very mobile and show extraordinary maneuverability. The dynamic and static stability displayed in complex and changing environments are highly correlated with such lateral bending patterns. The axial dynamics of their compliant body can also be critical for achieving energy-efficient locomotion at high velocities. In this paper, lateral undulation is used to characterize the bending pattern. The production of ground reaction forces (GRFs) and the related center of mass (COM) dynamics during locomotion are the fundamental mechanisms to be considered. Mainly based on research on geckos, which show unrestricted movement in three-dimensional space, we review current knowledge on the trunk flexibility and waveforms of lateral trunk movement. We investigate locomotion dynamics and mechanisms underlying the lateral undulation pattern. This paper also provides insights into the roles of this pattern in obtaining flexible and efficient walking, running, and climbing. Finally, we discuss the potential application of lateral undulation patterns to bio-inspired robotics.

Synthesis and properties of polyimide nanocomposite containing dopamine-modified graphene oxide

Polyimide (PI)/graphene oxide (GO) nanocomposites with different loads of polydopamine-modified graphene oxide (PI/PDA-GO) were prepared. Meanwhile, the as-prepared PI/PDA-GO nanocomposites were compared with pure PI in terms of their morphologies, thermal and mechanical properties. Only a minor mass fraction of PDA-GO was required to enhance the mechanical and thermal properties of PI. The tensile strength of 1 wt% PDA-GO/PI was increased by 12% and the tensile modulus of 1 wt% PDA-GO/PI nanocomposites was increased by 25% compared to those of pure PI. Vickers hardness of the PI hybrid films increased with PDA-GO load and the maximum enhancement in Vickers hardness was observed at 2 wt% PDA-GO loading. On the other hand, the storage modulus of 1 wt% PDA-GO/PI was increased by 54% than that of neat PI. In consideration of the facile preparation of PDA-coated GO, superior physical properties over neat PI, PI/PDA-GO nanocomposites showed promising applications as functional films or composites.

Facile preparation of epoxy based elastomers with tunable T gs and mechanical properties

In this work, a secondary amine-capped polyaspartic ester (PAE-D230) was synthesized using diethyl maleate and amine-terminated polyether (D230) via Michael addition reaction. By modulating the molar ratio of preliminary amine containing D230 and secondary amine-capped PAE-D230 during the curing process with epoxy precursor E44, we obtained epoxy shape memory polymers with tunable T _gs(-12-20 °C), controllable mechanical properties with tensile stress from 0.8 to 14.1 MPa, tensile modulus from 0.7 to 872.0 MPa, and elongation at break from 45.2 to 195.1%. The influence of the composition of curing components on the thermal properties, thermomechanical, mechanical properties, shape memory effect were systematically studied by DSC, TGA, DMA, tensile-stress measurements.

The use of clamping grips and friction pads by tree frogs for climbing curved surfaces

Most studies on the adhesive mechanisms of climbing animals have addressed attachment against flat surfaces, yet many animals can climb highly curved surfaces, like twigs and small branches. Here we investigated whether tree frogs use a clamping grip by recording the ground reaction forces on a cylindrical object with either a smooth or anti-adhesive, rough surface. Furthermore, we measured the contact area of fore and hindlimbs against differently sized transparent cylinders and the forces of individual pads and subarticular tubercles in restrained animals. Our study revealed that frogs use friction and normal forces of roughly a similar magnitude for holding on to cylindrical objects. When challenged with climbing a non-adhesive surface, the compressive forces between opposite legs nearly doubled, indicating a stronger clamping grip. In contrast to climbing flat surfaces, frogs increased the contact area on all limbs by engaging not just adhesive pads but also subarticular tubercles on curved surfaces. Our force measurements showed that tubercles can withstand larger shear stresses than pads. SEM images of tubercles revealed a similar structure to that of toe pads including the presence of nanopillars, though channels surrounding epithelial cells were less pronounced. The tubercles' smaller size, proximal location on the toes and shallow cells make them probably less prone to buckling and thus ideal for gripping curved surfaces.

Inversion of friction anisotropy in a bio-inspired asymmetrically structured surface

Friction anisotropy is an important property of many surfaces that usually facilitate the generation of motion in a preferred direction. Such surfaces are very common in biological systems and have been the templates for various bio-inspired materials with similar tribological properties. So far friction anisotropy is considered to be the result of an asymmetric arrangement of surface nano- and microstructures. However, here we show by using bio-inspired sawtooth-structured surfaces that the anisotropic friction properties are not only controlled by an asymmetric surface topography, but also by the ratio of the sample-substrate stiffness, the aspect ratio of surface structures, and by the substrate roughness. Systematically modifying these parameters, we were able to demonstrate a broad range of friction anisotropies, and for specific sample-substrate combinations even an inversion of the anisotropy. This result highlights the complex interrelation between the different material and topographical parameters on friction properties and sheds new light on the conventional design paradigm of tribological systems. Finally, this result is also of great importance for understanding functional principles of biological materials and surfaces, as such inversion of friction anisotropy may correlate with gait pattern and walking behaviour in climbing animals, which in turn may be used in robotic applications.

Silane coupling agent modified BN–OH as reinforcing filler for epoxy nanocomposite

Boron nitride-hydroxyl (BN–OH) was synthesized with silane coupling agent (KH550) in order to achieve epoxy/BN nanocomposites with excellent thermal, tribological, and mechanical properties. This is an efficient method to improve epoxy nanocomposite properties. These properties were investigated by friction and wear test, thermogravimetric analysis, and dynamic mechanical analysis. The wear mechanisms were studied by scanning electron microscopy. Surface modification of BN–OH with silane coupling agent significantly enhanced its thermal stability. Storage modulus of the nanocomposite with 2% epoxy/BN increased by nearly 300% in comparison with that of pure epoxy. The results exhibit outstanding performance of the epoxy/BN nanocomposites compared with pure epoxy resin.

Strength of silk attachment to Ilex chinensis leaves in the tea bagworm Eumeta minuscula (Lepidoptera, Psychidae)

Silks play an important role in the life of various arthropods. A highly neglected prerequisite to make versatile use of silks is sufficient attachment to substrates. Although there have been some studies on the structure and mechanics of silk anchorages of spiders, for insects only anecdotal reports on attachment-associated spinning behaviour exist. Here, we experimentally studied the silk attachment of the pupae and last instar caterpillars of the tea bagworm Eumeta minuscula (Butler 1881) (Lepidoptera, Psychidae) to the leaves of its host plant Ilex chinensis We found that the bagworms spin attachment discs, which share some structural features with those of spiders, like a plaque consisting of numerous overlaid, looped glue-coated silk fibres and the medially attaching suspension thread. Although the glue, which coats the fibres, cannot spread and adhere very well to the leaf surface, high pull-off forces were measured, yielding a mean safety factor (force divided by the animal weight) of 385.6. Presumably, the bagworms achieve this by removal of the leaf epidermis prior to silk attachment, which exposes the underlying tissue that represents a much better bonding site. This ensures a reliable attachment during the immobile, vulnerable pupal stage. This is the first study on the biomechanics and structure of silk attachments to substrates in insects.

Validation of EORTC QLQ-OES18 for Chinese patients with esophageal cancer

The aim of this study is to evaluate the reliability, validity, and acceptability of the Chinese version of the EORTC QLQ-OES18 in patients with esophageal cancer. The questionnaire was translated according to the guideline of the EORTC. One hundred and forty-nine patients with esophageal cancer from Tianjin Medical University Cancer Institute and Hospital completed the Karnofsky performance scale (KPS) and the simplified Chinese EORTC QLQ-C30/OES18 scales during July 2013 to January 2014. The results were statistically analyzed by Cronbach's α coefficient, Spearman correlation test with multiple strengthen analysis, and Wilcoxon Rank Sum test. The internal consistency (Cronbach's α coefficient) of all four scales (dysphagia, eating, reflux, and pain) was 0.689-0.822, which were satisfactory or near satisfactory. The absolute values of correlation of each scale between EORTC QLQ-OES18 and EORTC QLQ-C30 were 0.002-0.750 while there was no significant difference between groups divided by KPS scores. We confirmed the Chinese version of EORTC QLQ-OES18 appears to be a reliable, valid, and acceptable instrument for measuring the health-related quality of life of patients with esophageal cancer in mainland China.