Snap-through behaviour of a bistable structure based on viscoelastically generated prestress

A novel form of shape-changing bistable structure has been successfully developed through the use of viscoelastically generated prestress. Bistability is achieved through pairs of deflecting viscoelastically prestressed polymeric matrix composite (VPPMC) strips, which are orientated to give opposing cylindrical configurations within a thin, flexible resin-impregnated fibreglass sheet. This arrangement enables the structure to ‘snap through’ between one of two states by external stimulation. Deflection from the VPPMC strips occurs through compressive stresses generated from the non-uniform spatial distribution of nylon 6,6 fibres undergoing viscoelastic recovery. In this study, snap-through behaviour of the bistable structure is investigated both experimentally and through finite element (FE) analysis. By using experimental results to calibrate FE parameter values, the modelling has facilitated investigation into the development of bistability and the influence of modulus ratio (fibreglass sheet: VPPMC strip) on the snap-through characteristics. Experimental results and FE simulation show good agreement with regard to snap-through behaviour of the bistable structure and from this, the bistability mechanisms are discussed

ALMA Observations of Ethyl Formate toward Orion KL

Orion KL is one of the prime templates of astrochemical and prebiotic chemical studies. We wish to explore more organic molecules with increasing complexity in this region. In particular, we have searched for one of the most complex organic molecules detected in space so far, ethyl formate (C$_{2}$H$_{5}$OCHO). This species is the next step in chemical complexity after the simplest member of esters (methyl formate, CH$_{3}$OCHO). The mechanisms leading to its formation are still poorly known. We have used high angular resolution ($\sim$ 1.$^{\prime\prime}$5) ALMA observations covering a large bandwidth from 214 to 247 GHz. We have detected 82 unblended lines of C$_{2}$H$_{5}$OCHO (49 and 33 of the trans and gauche conformers, respectively). The line images showed that C$_{2}$H$_{5}$OCHO arises mainly from the compact ridge and the hot core-southwest regions. The derived rotational temperatures and column densities are 122 $\pm$ 34 K, (0.9 $\pm$ 0.3) $\times$ 10$^{16}$ cm$^{-2}$ for the hot core-SW, and 103 $\pm$ 13 K, (0.6 $\pm$ 0.3) $\times$ 10$^{16}$ cm$^{-2}$ for the compact ridge. The comparison of spatial distribution and abundance ratios with chemically related molecules (methyl formate, ethanol and formic acid) indicates that C$_{2}$H$_{5}$OCHO is likely formed on the surface of dust grains by addition of CH$_{3}$ to functional-group radicals (CH$_{2}$OCHO) derived from methyl formate (CH$_{3}$OCHO)

Fully integrated InGaAs/InP single-photon detector module with gigahertz sine wave gating

InGaAs/InP single-photon avalanche diodes (SPADs) working in the regime of GHz clock rates are crucial components for the high-speed quantum key distribution (QKD). We have developed for the first time a compact, stable and user-friendly tabletop InGaAs/InP single-photon detector system operating at a 1.25 GHz gate rate that fully integrates functions for controlling and optimizing SPAD performance. We characterize the key parameters of the detector system and test the long-term stability of the system for continuous operation of 75 hours. The detector system can substantially enhance QKD performance and our present work paves the way for practical high-speed QKD applications.Comment: 11 pages, 6 figures. Accepted for publication in Review of Scientific Instrument

An evaluation of the scanning electron microscope mirror effect to study viscoelastically prestressed polymeric matrix composites

A viscoelastically prestressed polymeric matrix composite (VPPMC) is produced by applying tensile creep to polymeric fibres, the creep load being removed before the fibres are moulded into a resin matrix. Following matrix curing, the viscoelastically strained fibres impart compressive stresses to the surrounding matrix, counterbalanced by residual tension in the fibres. VPPMCs based on nylon 6,6 fibres in polyester resin have previously demonstrated improvements in mechanical properties of up to 50% compared with control (unstressed) counterparts. Although the associated viscoelastic recovery forces are understood, little is known of the fibre-matrix interactions relating to prestress within VPPMCs. This is addressed by investigating composite samples with the scanning electron microscope mirror effect (SEMME). By comparing results from VPPMC samples with their control counterparts, the findings suggest that there are ∼30% fewer trapped negative charges in the former, implying that the VPPMCs possess higher fibre-matrix interfacial strengths. Tensile test results on similar composite samples support these findings. The effects of resin porosity in SEMME data are also evaluated and our findings suggest that porosity can significantly increase charge trapping

MiRNA-145 increases therapeutic sensibility to gemcitabine treatment of pancreatic adenocarcinoma cells.

Pancreatic adenocarcinoma is one of the most leading causes of cancer-related deaths worldwide. Although recent advances provide various treatment options, pancreatic adenocarcinoma has poor prognosis due to its late diagnosis and ineffective therapeutic multimodality. Gemcitabine is the effective first-line drug in pancreatic adenocarcinoma treatment. However, gemcitabine chemoresistance of pancreatic adenocarcinoma cells has been a major obstacle for limiting its treatment effect. Our study found that p70S6K1 plays an important role in gemcitabine chemoresistence. MiR-145 is a tumor suppressor which directly targets p70S6K1 for inhibiting its expression in pancreatic adenocarcinoma, providing new therapeutic scheme. Our findings revealed a new mechanism underlying gemcitabine chemoresistance in pancreatic adenocarcinoma cells

PO-096 Correlation between Muscle oxygen and Cardiopulmonary of young cyclists at Ventilation threshold

Objective To investigate the relationship between Near-infrared spectroscopy (NIRS)-derived muscle oxygen saturation (SmO2) and Cardiopulmonary indexes at the Ventilatory threshold (VT1 and VT2) during Cardiopulmonary exercise test (CPET) ofyoung cyclists. Methods 12 young cyclists performed a maximal incremental exercise test to exhaustion on a friction-braked cycle ergometer (Monark 839E, Sweden).Heart rate (Polar RS400, Finland) and respiratory gas exchange were measured during the Resting and exercise phases using a breath-by-breath system. SmO2 of active muscles during cycling was measured by NIRS monitors (Fortiori Design LLC, USA), and three of the monitors were placed on both vastus lateralis (VLL & VLR) and left gastrocnemius lateralis (GLL) of left leg. The resting value of the SmO2 of the GLL (SmO2-GLL), the left vastus lateralis (SmO2-VLL), and the right vastus lateralis (SmO2-VLR) was recorded as a baseline.  Then after VT1 and VT2 of each subject were measured by the V-slope method during a CPET, values of muscle oxygen corresponding to the three lower limb sites at two ventilation thresholds was recorded to reflect the muscle oxygenation level at the anaerobic threshold; And the change of muscle oxygen relative to the baseline was calculated to reflect the degree of muscle deoxygenation, which is termed as deoxygenation indexes(ΔSmO2-GLL, ΔSmO2-VLL, ΔSmO2-VLR); As well, Cardiopulmonary indexes including Heart rate (HR), Minute ventilation (VE), Relative oxygen uptake (VO2R), Carbon dioxide production (VCO2) and Respiratory exchange rate (RER) at the Ventilatory threshold were measured. All Results were expressed as mean ± standard deviation. Finally, Pearson correlation analysis was used to determine the relationship between multi-site muscle oxygen saturation of lower extremities and Cardiopulmonary indexes (HR, VE, VO2R, VCO2, RER). The significance level was defined as p<0.05. Results Each subject performed their best to complete the aerobic capacity test. The average VO2peak of the 12 subjects was 42.77 ± 9.69 ml/kg/min (Male: 47.38 ± 9.41 ml/kg/min; Female: 36.31 ± 3.33 ml/kg/min). At rest, the calf and thigh SmO2 were 67.92%± 6.84% (SmO2-GLL), 61.42% ± 13.77% (SmO2-VLL), 64.83% ± 10.62% (SmO2-VLR)respectively; HR, VE, VO2, VO2R, VCO2 and RER were 112.08 ± 14.38, 25.96 ± 8.74 L / min 0.94 ± 0.32 L/min, 15.82 ± 4.30 ml/kg/min, 0.81 ± 0.24 L/min,0.88 ± 0.12 L/min, and 0.38 ± 0.07, respectively. Correlation analysis shows that when adolescent athletes reached the anaerobic threshold level, there was a significant correlation between muscle oxygen and cardiopulmonary: At the time of VT1, for Oxygenation index, SmO2 of GLL was highly negatively correlated with HR (r=-0.69,p<0.05), VE (r=-0.71, p<0.01), VO2R (r=-0.65, p<0.05), VCO2 (r=-0.66, p<0.05) and RER (r=-0.58, p<0.05); SmO2-VLL was also highly negatively correlated with VE (r=-0.70, p<0.05), VO2R (r=-0.70, p<0.05), VCO2 (r=-0.66, p<0.05); Additionally, there is also high inverse correlation between SmO2-VLR and HR (r=-0.66, p<0.05), VE (r=-0.70, p<0.05), VO2R (r=-0.66, p<0.05), VCO2 (r=-0.68, p<0.05), RER (r=-0.60, p<0.05). In terms of deoxygenation indexes, ΔSmO2-GLL was highly negatively correlated with VE (r=-0.61, p<0.05), VO2R  (r=-0.64, p<0.05) and VCO2 (r=-0.59, p<0.05); While, ΔSmO­2-VLL was highly negatively correlated with HR (r=-0.62, p<0.05), VE (r=-0.72, p<0.01),VO2R (r=-0.80, p<0.01) and VCO2(r=-0.84, p<0.01); ΔSmO2-VLR was correlated with HR (r=-0.75, p<0.01), VE (r=-0.62, p<0.05), VO2R (r=-0.58, p<0.05) and RER (r=-0.74, p<0.01), and it also shows highly negative correlation. When VT2 occurred, only SmO2 of the GLL in the oxygenation indexes was highly positively correlated with HR (r=0.65, p<0.05), there was no correlation between GLL-SmO2 and any other gas exchange indexes. In terms of muscle deoxygenation indexes, only ΔSmO2 in the thigh VLR was significantly negatively correlated with RER (r=-0.75, p<0.01). Conclusions Based on these results, there is a high correlation between NIRS-derived regional muscle oxygen saturation (Oxygenation and Deoxygenation indexes) of lower extremities and cardiopulmonary index (HR, VE, VO2R, VCO2, RER) during CPET of young cyclists at first Ventilatory threshold, however, it is still unclear whether there is a significant correlation between muscle oxygen saturation of lower extremities and other cardiopulmonary indexes when second Ventilatory threshold occurs except Heart rate or Minute ventilation

Novel composite meshes to evaluate their structural property and in vivo biocompatibility for tissue repair

Composite meshes of different types have been prepared and used for tissue repair in pelvic floor disorder. An interlocking texture mesh (inter-mesh) and a membrane coated mesh (electro-mesh) have been used based on their structural property and biocompatibility. The proportion of degradation material in inter-mesh (69.6%) is found extremely higher than that of electro-mesh (3.22%), thus leading to higher product weight (65.50±2.31 g/m2) and thickness (0.500±0.025 mm). After 4 weeks of implantation in animal experiment, inter-mesh with surrounding tissues is observed to have higher breaking strength in tensile behavoir and better flexibility. Tissues on inter-mesh are found to grow faster with larger thickness (0.76±0.033 mm). The surface area loss of inter-mesh (2.49±0.25%) is much less than that of electro-mesh (7.49±0.63 %) within the first 2 weeks of implantation. However, the material’s degradation is accelerated after 2 weeks, leading to a higher shrinkage of 13.12±1.48 %