The internal rotation, geometry, energy, vibrational spectra, dipole moments and molecular mean polarizabilities of poly(vinylidene fluoride–tetrafluoroethylene) (P(VDF–TeFE)) of α- and β-chain ...models were studied with density functional theory at B3PW91/6-31G(d) level and compared with those of poly(vinylidene fluoride) homopolymer and P(VDF–TrFE) copolymer. The electric properties, chain conformation and stability of the copolymer influenced by the chain length and TeFE content were examined. Based on the internal rotation curves of P(VDF–TeFE) dimer models (HCH2CF2–CF2CF2H and HCF2CH2–CF2CF2H), the conformational angles, relative stabilities of α- and β-conformation, and the transition energy barriers of β→α and α→β were discussed. The results show that the β-conformation is more stable than the α-conformation thermodynamically and the β→α transition in P(VDF–TeFE) is more difficult than that in PVDF. Thus the copolymer should be in favor of preventing the piezoelectric phase from depolarization. The ideal β-chains are curved with a radius of about 30Å, which is very close to those in both PVDF and P(VDF–TrFE). Similar to P(VDF–TrFE), the α-chain P(VDF–TeFE) containing 0.50 mole fraction of TeFE is also a helical structure. However, the α-chain with 0.33–0.20 mole fraction of TeFE are almost linear in structure, which might be responsible for enhancing crystallinity of the copolymer. The contribution of average dipole moment per monomer unit in the β-chain is affected by the chain curvature and TeFE content, and there is a weakly parabolic dependence on the VDF content. The chain length and TeFE content will not significantly affect the mean polarizability per monomer unit. The calculations show that there are some characteristic vibrational modes that may be used in the identification of the α- and β-phase P(VDF–TeFE) with different TeFE contents.
Prostacyclin (PGI(2)) is one of the major vascular protectors against thrombosis and vasoconstriction, caused by thromboxane A(2). Understanding the molecular mechanisms of PGI(2) biosynthesis and ...signaling is crucial to the development of therapeutic approaches to regulate PGI(2) functions. This review provides information regarding the most current advances in the findings of the molecular mechanisms for PGI(2) biosynthesis in the endoplasmic reticulum (ER) membrane through the coordination between PGI(2) synthase and its upstream enzymes, cyclooxygenase-1 (COX-1) or -2 (COX-2), and for PGI(2) signaling through its cell membrane receptors and nuclear peroxisome proliferator-activated receptors. The substrate presentation from the COXs to PGI(2) synthase and its cell membrane receptor/G protein coupling sites, as characterized by our group, are discussed in detail. The association between the regulation of the biosynthesis and signaling of PGI(2) with the pathophysiological processes of PGI(2)-related diseases is also discussed. The molecular knowledge of PGI(2) biosynthesis and signaling will help to design the next generation of drugs, specifically targeting the regulation of PGI(2) functions, which will undoubtedly provide advances in cardiovascular protection and the treatment of PGI(2)-related diseases.
Sensors and algorithms are two fundamental elements to construct intelligent systems. The recent progress in machine learning (ML) has produced great advancements in intelligent systems, owing to the ...powerful data analysis capability of ML algorithms. However, the performance of most systems is still hindered by sensing techniques that typically rely on rigid and bulky sensor devices, which cannot conform to irregularly curved and dynamic surfaces for high‐quality data acquisition. Skin‐like stretchable sensing technology with unique characteristics, such as high conformability, low modulus, and light weight, has been recently developed to solve this issue. Here, the recent progress in the fusion of emerging stretchable electronics and ML technology, for bioelectrical signal recognition, tactile perception, and multimodal integration is summarized, and the challenges and future developments are further discussed. These efforts aim to accelerate various perception and reasoning tasks for advanced intelligent applications, such as human–machine interfaces, healthcare, and robotics.
Fusing stretchable sensing technology with machine learning (ML) is expected to unlock novel opportunities in healthcare, extend human–machine interactions, and enhance the functionalities of prostheses and robots. Here, the recent progress, challenges, and prospects of stretchable sensing‐ML systems are discussed. It offers clues to fully take advantage of the two emerging technologies for future intelligent systems.
A relative complete study on the mechanisms of the proton transfer reactions of 2-thioxanthine was carried out with density functional theory. The models were designed with monohydrated and ...dihydrated microsolvent catalyses either with or without the presence of water solvent considered with the polarized continuum model (PCM). A total number of 114 complexes and 67 transition states were found with the B3LYP/6-311+G** calculations. The energies were refined with both B3LYP/aug-cc-pVTZ and PCM-B3LYP/aug-cc-pVTZ methods. The activation energies were reported with respect to the Gibbs free energies obtained in conjunction with the standard statistical thermodynamics. Possible reaction pathways were confirmed with the intrinsic reaction coordinates. Pathways
via
C8 atom on the imidazole ring,
via
the bridged C4 and C5 atoms between pyrimidine and imidazole rings and
via
N, O and S atom on the pyrimidine ring were examined. The results show that the most feasible pathway is the proton transfers within the long range solvent surrounding
via
the N, O and S atoms in the pyrimidine ring with di-hydrated catalysis: N(7)H + 2H
2
O → IM89 → IM90 → P13 + 2H
2
O → IM91 → IM92 → P6 + 2H
2
O → IM71 → IM72 → P7 + 2H
2
O → IM107 → IM108 → P18 + 2H
2
O → IM111 → IM112 → P19 + 2H
2
O → IM113 → IM114 → P17 + 2H
2
O → IM105 → IM106 → N(9)H + 2H
2
O that has the highest energy barrier of 44.0 kJ mol
−1
in the transition of IM89 to IM90
via
TS54. The small energy barrier is in good agreement with the experimental observation that 2-TX tautomerizes at room temperature in water. In the aqueous phase, the most stable intermediate is found to be IM21
N(7)H
+ 2H
2
O and the possible co-existing species are the monohydrated IM1, IM9, IM39 and IM46, and the di-hydrated IM5, IM8, IM13, IM16, IM81, IM89, IM90, IM91 and IM106 complexes that have a relative concentration larger than 10
−6
(1 ppm) with respect to IM21.
Figure
Mechanisms of the proton transfer reactions of 2-thioxanthine were investigated with both B3LYP/aug-cc-pVTZ//B3LYP/6-311+G** and PCM-B3LYP/aug-cc-pVTZ//B3LYP/6-311+G**. The models were designed with monohydrated and dihydrated microsolvent either with or without the presence of water solvent. The results show that the most feasible pathway is the reactions within the long range solvent surrounding
via
the N, O and S atoms in the pyrimidine ring with di-hydrated catalysis: N(7)H + 2H
2
O → IM90 → IM91 → P13 + 2H
2
O → IM92 → IM93 → P6 + 2H
2
O → IM72 → IM73 → P7 + 2H
2
O → IM109 → IM110 → P18 + 2H
2
O → IM113 → IM114 → P19 + 2H
2
O → IM115 → IM116 → P17 + 2H
2
O → IM107 → IM108 → N(9)H + 2H
2
O that has the highest barrier of 44.0 kJ mol
−1
in the transition of IM90 to IM91
via
TS54. The barrier is adequate for a reaction at room temperature that consists well with the experimental observations.
The aim of the present study was to examine the apoptosis of the hepatocellular carcinoma cell line, HepG2, induced by treatment with folic acid-conjugated silica-coated gold nanorods (GNRs@SiO2-FA) ...in combination with radiotherapy, and to determine the involvement of apoptosis-related proteins. An MTT colorimetric assay was used to assess the biocompatibility of GNRs@SiO2-FA. The distribution of GNRs@SiO2-FA into the cells was observed using transmission electron microscopy (TEM). HepG2 cells cultured in vitro were divided into the following 4 groups: i)the control group (untreated), ii) the GNRs@SiO2-FA group, iii) the radiotherapy group (iodine 125 seeds) and iv) the combination group (treated with GNRs@SiO2-FA and iodine 125 seeds) groups. The apoptosis of the HepG2 cells was detected by flow cytometry. The concentration range of <40 µg/ml GNRs@SiO2-FA was found to be safe for the biological activity of the HepG2 cells. GNRs@SiO2-FA entered the cytoplasm through endocytosis. The apoptotic rates of the HepG2 cells were higher in the GNRs@SiO2-FA and radiotherapy groups than in the control group (P<0.05). The apoptotic rate was also significantly higher in the combination group than the GNRs@SiO2-FA and radiotherapy groups (P<0.05). Taken together, these findings demonstrate that the combination of GNRs@SiO2-FA and radiotherapy more effectively induces the apoptosis of HepG2 cells. These apoptotic effects are achieved by increasing the protein expression of Bax and caspase-3, and inhibiting the protein expression of Bcl-2 and Ki-67. The combination of GNRs@SiO2-FA and radiotherapy may thus prove to be a new approach in the treatment of primary liver cancer.
In this study, three
taxa were identified, associated with leaves of
,
and
.
Based on morphology and multi-gene analyses of the internal transcribed spacer (ITS), beta-tubulin (TUB2) and translation ...elongation factor 1-alpha (TEF1), the five strains of
represent two novel and one known species. They are introduced with descriptions, illustrations and notes herein.
Large-scale object-oriented（OO） software systems have recently been found to share global network characteristics such as small world and scale free,which go beyond the scope of traditional software ...measurement and assessment methodologies.To measure the complexity at various levels of granularity,namely graph,class（and object） and source code,we propose a hierarchical set of metrics in terms of coupling and cohesion-the most important characteristics of software,and analyze a sample of 12 open-source OO software systems to empirically validate the set.Experimental results of the correlations between cross-level metrics indicate that the graph measures of our set complement traditional software metrics well from the viewpoint of network thinking,and provide more effective information about fault-prone classes in practice.
We report on the preparation and superconductivity of metastable γ-Ga islands on Si （111） substrate. The Ga grows in a typical Volmer-Weber mode at a low temperature of 110 K, resulting in formation ...of Ga nanoislands at various sizes with the identical γ-phase. In-situ low temperature scanning tunneling spectra reveal quantized electronic states in ultrathin Ga islands. It is found that both the lateral size and thickness of the Ga islands strongly suppress the superconductivity. Due to substantial surface energy contribution, the transition temperature Tc scales inversely with the island thickness and the minimum thickness for the occurrence of superconductivity is calculated to be two monolayers.
We report on molecular beam epitaxy growth of stoichiometric and superconducting FeSe crystalline thin films on double-layer graphene. Layer-by-layer growth of high-quality films has been achieved in ...a well-controlled manner by using Se-rich condition, which allow us to investigate the thickness-dependent superconductivity of FeSe. In situ low-temperature scanning tunneling spectra reveal that the local superconducting gap in the quasiparticle density of states is visible down to two triple layers for the minimum measurement temperature of 2.2 K, and that the transition temperature T{sub c} scales inversely with film thickness.
In this paper, we propose an ultra-reliable multiuser multiple-input multiple-output (MU-MIMO) detector based on deep learning for the fifth-generation and beyond the fifth-generation (5G/B5G) ...enabled Internet of Things (IoT), where the system is operating in interfering environments correlated over the time or frequency domain. For this system, we employ an iterative detection framework of a conventional symbol-by-symbol detector and a deep convolutional neural network (DCNN), where the DCNN is used to suppress the interfering signals by capturing the characteristics through deep learning. The conventional detector in the framework can be either ZF-MLD or MMSE-MLD, where the conventional zero-forcing (ZF) or minimum mean square error (MMSE) is initially used and then the near-by signal candidates are searched through the maximum likelihood detection (MLD). Thus, the proposed MU-MIMO detector can suppress the influence of the correlated interferences with low computational complexity and finally improve the reliability of the practical MU-MIMO systems in the presence of correlated interferences. To further enhance the system detection performance, user scheduling is employed, where several user selection criteria are proposed to choose one best user among multiple ones. Simulation results are finally presented to show that an ultra-reliable detection performance can be achieved for the 5G/B5G-enabled IoT.
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