Mechanical and physical properties of poly(vinyl alcohol) microfibers fabricated by a microfluidic approach

A microfluidic platform was used to fabricate continuous and non-rounded polyvinyl alcohol (PVA) microfibers. We showed that the size and cross-section of the PVA fibers can be controlled by changing the PVA concentration in dimethyl sulfoxide (DMSO) and flow rate ratio between the core and sheath fluids. The PVA concentration was varied from 6% to 12%, and the sheath-to-core flow rate ratio used for this study was in the range of 500:5 to 500:20. The aspect ratio of the fibers became larger when the PVA concentration increased and the flow rate ratio decreased. Additionally, we simulated the microfluidic fiber fabrication process and the results were consistent with the experimental results. The dissolution of the PVA fibers fabricated with different characteristics was also studied. It was shown that increasing the PVA concentration and decreasing the flow rate ratio increased the dissolution time of the fibers in DI water. A tensile test was conducted to obtain the stress–strain curves for different types of fibers. The results showed that a wide range of mechanical properties can be achieved by changing the PVA concentration and the flow rate ratio. The increase of PVA concentration from 6% to 12% enhanced the tensile stress at break and Young\u27s modulus by a factor of 4.9 and 2.02, respectively. The mechanical strength of the fibers was shown to drop when the flow rate ratio decreased

On-chip development of hydrogel microfibers from round to square/ribbon shape

We use a microfluidic approach to fabricate gelatin fibers with controlled sizes and cross-sections. Uniform gelatin microfibers with various morphologies and cross-sections (round and square) are fabricated by increasing the gelatin concentration of the core solution from 8% to 12%. Moreover, the increase of gelatin concentration greatly improves the mechanical properties of gelatin fibers; the Young\u27s modulus and tensile stress at break of gelatin (12%) fibers are raised about 2.2 and 1.9 times as those of gelatin (8%) fibers. The COMSOL simulations indicate that the sizes and cross-sections of the gelatin fibers can be tuned by using a microfluidic device with four-chevron grooves. The experimental results demonstrate that the decrease of the sheath-to-core flow-rate ratio from 150 : 1 to 30 : 1 can increase the aspect ratio and size of ribbon-shaped fibers from 35 μm × 60 μm to 47 μm × 282 μm, which is consistent with the simulation results. The increased size and shape evolution of the cross-section can not only strengthen the Young\u27s modulus and tensile stress at break, but also significantly enhance the tensile strain at break

Effect of expression levels of multidrug resistance gene related protein 1, P-glycoprotein and topoisomerase II on paclitaxel, gemcitabine and vinorelbine sensitivity in pulmonary cancer

Purpose: To investigate the possible correlation between drug resistance gene expression and development of drug sensitivity, and the possible clinical significance of this relationship. Methods: A total of 100 cancer samples were surgically obtained. MTT assay was employed to determine drug sensitivity. The expression levels of drug resistance genes, multidrug resistance generelated protein 1 (MRP1), P-glycoprotein (P-gp), and topoisomerase II (Topo II) were measured by immunohistochemistry. Results: The expression levels of MRP1, P-gp, and Topo II genes in lung cancer were 70.0, 65.0, and 50.0 %, respectively. No significant statistical differences were observed in the expressions of MRP1, Pgp, and Topo II between human adenocarcinoma and squamous cell carcinoma (p > 0.05), but a significant difference was found in MRP1 and Topo II expressions between human adenocarcinoma or squamous carcinoma cell and small-cell lung cancer (p < 0.05). A significant positive correlation was observed between P-gp expression and resistance cisplatin, gemcitabine, vinorelbine, and paclitaxel (p < 0.05). A significant positive correlation was also found between MRP1 expression and the development of resistance to cisplatin, gemcitabine, and vinorelbine (p < 0.05), but no significant correlation was observed between MRP1 expression and the development of resistance to paclitaxel and ifosfamide (p > 0.05). Conclusion: The up-regulated expression of MRP1 and P-gp, and the down-regulated expression of Topo II may be positively correlated with drug resistance in lung cancer patients. Thus, gene tests are recommended to guide the administration of chemotherap

Query Twice: Dual Mixture Attention Meta Learning for Video Summarization

Video summarization aims to select representative frames to retain high-level information, which is usually solved by predicting the segment-wise importance score via a softmax function. However, softmax function suffers in retaining high-rank representations for complex visual or sequential information, which is known as the Softmax Bottleneck problem. In this paper, we propose a novel framework named Dual Mixture Attention (DMASum) model with Meta Learning for video summarization that tackles the softmax bottleneck problem, where the Mixture of Attention layer (MoA) effectively increases the model capacity by employing twice self-query attention that can capture the second-order changes in addition to the initial query-key attention, and a novel Single Frame Meta Learning rule is then introduced to achieve more generalization to small datasets with limited training sources. Furthermore, the DMASum significantly exploits both visual and sequential attention that connects local key-frame and global attention in an accumulative way. We adopt the new evaluation protocol on two public datasets, SumMe, and TVSum. Both qualitative and quantitative experiments manifest significant improvements over the state-of-the-art methods.Comment: This manuscript has been accepted at ACM MM 202

Microwave spectroscopy and Zeeman effect of cesium (n+2)D5/2→nFJ(n+2)D_{5/2}\rightarrow nF_{J} Rydberg transitions

We report on high-resolution microwave spectroscopy of cesium Rydberg $(n+2)D_{5/2}\rightarrow nF_{J}$ transitions in a cold atomic gas. Atoms laser-cooled and trapped in a magnetic-optical trap are prepared in the $D$ Rydberg state using a two-photon laser excitation scheme. A microwave field transmitted into the chamber with a microwave horn drives the Rydberg transitions, which are probed via state selective field ionization. Varying duration and power of the microwave pulse, we observe Fourier side-band spectra as well as damped, on-resonant Rabi oscillations with pulse areas up to $\gtrsim 3 \pi$. Furthermore, we investigate the Zeeman effect of the clearly resolved $nF_J$ fine-structure levels in fields up to 120~mG, where the transition into $nF_{7/2}$ displays a thee-peak Zeeman pattern, while $nF_{5/2}$ shows a two-peak pattern. Our theoretical models explain all observed spectral characteristics, showing good agreement with the experiment. Our measurements provide a pathway for the study of high-angular-momentum Rydberg states, initialization and coherent manipulation of such states, Rydberg-atom macrodimers, and other Rydberg-atom interactions. Furthermore, the presented methods are suitable for calibration of microwave radiation as well as for nulling and calibration of DC magnetic fields in experimental chambers for cold atoms

Synthesis of Er3+/Yb3+ codoped NaMnF3 nanocubes with single-band red upconversion luminescence

We have developed a facile low-temperature synthetic method for the preparation of NaMnF3 nanocubes with Er3+ and Yb3+ ions homogeneously incorporated in the host lattice. The effects of the reaction temperature, and the volume ratio between ethanol and DI water on the morphology of NaMnF3 nanocubes are systematically investigated. The NaMnF3 nanocubes can be produced in the low temperature range (25–80 °C), and the higher reaction temperature (80 °C) is favorable for the formation of a smooth surface. The formation of NaMnF3 nanocubes strongly depends on the ethanol solvent. The morphology and single-phase of the obtained samples could be well maintained by controlling the doping concentration (Yb3+ ≤ 20 mol%). Single-band red upconversion emission can be generated in Er3+/Yb3+ codoped NaMnF3 nanocubes due to the energy transfer between host Mn2+ and dopant Er3+ ions. It is revealed that our NaMnF3:Er3+/Yb3+ nanocubes irradiate the brightest red luminescence at the dopant concentrations of Er3+ (2 mol%) and Yb3+ (15 mol%), which is stronger than that of the hexagonal-phase NaYF4:Er3+/Yb3+ phosphor

Effect Of Type And Quantity Of Inherent Alkali Cations On Alkali-silica Reaction

In this study, the macroscopical expansion induced by alkali-silica reaction (ASR) and its corresponding ASR products are investigated using ordinary Portland cement (OPC) mortar specimens with a gradient of boosted alkalis. Experimental results show that the expansion increases with the concentration of inherent alkalis. Sodium-boosted samples expand approximately three times as much as potassium-boosted samples. ASR gels that are present in aggregate veins are calcium-free and amorphous; the atomic ratios of ASR gels are nearly independent of the type and quantity of alkali cations. Aggregate ASR gel exudation occurs in high (≥2.5 %) sodium cases and produces potential Na-shlykovite. Crystalline and amorphous calcium-containing ASR products are present in aggregate vicinities in either Na- or K-boosted samples. The higher hydrophilicity of Na-gel in aggregate veins accounts for the larger expansion. Boosted alkali cations are more effective in ASR products formation than in exposing solution. A new observation that NaOH exposure inhibits ASR in K-boosted samples (zero expansion) is reported

Origin and Characteristics of the Crude Oils and Condensates in the Callovian-Oxfordian Carbonate Reservoirs of the Amu Darya Right Bank Block, Turkmenistan

AbstractThe Amu Darya Right Bank Block is located northeast of the Amu Darya basin, a large petroliferous sedimentary basin, with abundant natural gas resources in carbonate rocks under the ultra-thick gypsum-salt layer. Oil fields producing crude oils have recently been found around large gas fields. Unraveling the origins of the crude oils is crucial for effective petroleum exploration and exploitation. The origin of gas condensates and crude oils was unraveled through the use of comprehensively analytical and interpretative geochemical approaches. Based on oil-source correlation, the reservoir forming process has been restored. The bulk geochemical parameters of the local source rocks of the ADRBB indicated that the local sources have hydrocarbon generation and accumulation potential. The middle-lower Jurassic coal-bearing mudstone is gas prone, while the mudstone of the Callovian-Oxfordian gap layer is oil prone, and the organic matter type of Callovian-Oxfordian carbonate rocks is the mixed type between the two previous source rocks. The interpretation schemes for compositions of n-alkanes, pristane and phytane, C27–C28–C29 sterane distributions, C19+C20–C21–C23 tricyclic terpane distributions, extended tricyclic terpane ratio, and δ13C indicated that crude oil is likely from marine organic matter, while condensates mainly originate from terrestrial organic matter. However, from the perspective of the 18α-trisnorneohopane/17α-trisnorhopane and isomerization ratio of C29 sterane, condensates are too mature to have originated in the local source rocks of the ADRBB, whose maturity is well comparable with that of crude oils. The geochemical, geologic, and tectonic evolutions collectively indicate that the crude oils were most likely generated and migrated from the relatively shallow, lowly mature gap layer and Callovian-Oxfordian carbonate rocks of the ADRBB, while the condensates mostly originated from the relatively deep and highly mature middle-lower coal-bearing mudstone and Callovian-Oxfordian carbonate rocks in the Murgab depression in the southeast of the basin. Basement faults are the key factors affecting the types of oil and gas reservoirs. During the periods of oil and gas migration, traps with basement faults mainly captured natural gas and condensates and traps without basement faults were enriched with crude oils generated from local source rocks