Ultra-wide-band (UWB) technology combined with multiple transmit and receive antennas (MIMO) is a viable way to achieve data rates of more than 1 Gb/s for wireless communications. UWB is typically ...applied to short-range and therefore mainly indoor communications in environments characterized usually by dense multipath propagation. For this type of environment, MIMO systems allow for a substantial increase of spectral efficiency by exploiting the inherent array gain and spatial multiplexing gain of the systems. In this paper, we provide a brief overview for UWB-MIMO wireless technology. The overview covers channel capacity, space-time coding (STC), and beamforming. It is shown that the spectral efficiency is increased logarithmically and linearly , respectively, for single transmit and multiple receive antennas (SIMO) and MIMO systems. For multiple transmit and single receive antenna (MISO) systems, a threshold for the data transmission rate exists such that the spatial multiplexing gain can be obtained if the data rate is lower than this threshold, but it is not beneficial to deploy multiple transmit antennas if the required data rate is higher than the threshold. Two STC schemes for UWB-MIMO are briefly discussed, and their performance comparison is presented. A discussion about antenna selection is also presented, and the performance comparison between antenna selection and equal gain combiner is provided showing the diversity gain for some scenarios. For the beamforming, it is shown that the optimal beamformer is obtained if all the weighting filters in each antenna branch are identical. About the optimal beamformer, it is found that the amplitude of the side lobe is independent of the ray incidence angle, and the amplitude of the main lobe is increased by a fold of the element number in the array. Three kinds of beam patterns are defined, and the beamwidth of the main lobe is given. Experimental results based on an offline testbed are provided to verify some analytical results presented in this paper. Since UWB-MIMO is still in its research infancy, the aim of this paper is to present some first results on spatial multiplexing, STC, and beamforming to illustrate the potential of UWB-MIMO.
The catalytic conversion of alcohols under mild conditions is a great challenge because it is constrained by low selectivity and low activity. Herein, we demonstrate a hollow nanotube Fe2O3/MoO3 ...heterojunction (FeMo‐2) for the photoelectrocatalytic conversion of small‐molecule alcohols. Experimental and theoretical analyses reveal that the optical carrier transfer rate is enhanced by constructing interfacial internal electric fields and Fe‐O‐Mo charge transfer channels. For the formox process, heterojunctions possess superior HCHO‐selective reaction paths and free energy transitions, optimizing the selectivity of HCHO and enhancing the reactivity. FeMo‐2 shows a greatly improved performance compared to single Fe2O3; the photocurrent density of FeMo‐2 reaches 0.66 mA cm−2, which is 3.88 times that of Fe2O3 (0.17 mA cm−2), and the Faraday efficiency of the CH3OH‐to‐HCHO conversion is 95.7 %. This work may deepen our understanding of interfacial charge separation and has potential for the production of HCHO and for conversion reactions of other small‐molecule alcohols at cryogenic temperatures.
A Z‐Scheme Fe2O3/MoO3 hollow nanotube with a CH3OH‐to‐HCHO selectivity of 95.7 % was developed. The thin‐walled hollow structure facilitates a fast transfer of photogenerated carriers and enhances light utilization. The Fe‐O‐Mo charge transfer channel and internal electric field in the Fe2O3/MoO3 interface improve the charge transfer efficiency. PEC experiments and calculations demonstrate that C−H bond breaking is the rate‐determining step.
Long nanopore reads are advantageous in de novo genome assembly. However, nanopore reads usually have broad error distribution and high-error-rate subsequences. Existing error correction tools cannot ...correct nanopore reads efficiently and effectively. Most methods trim high-error-rate subsequences during error correction, which reduces both the length of the reads and contiguity of the final assembly. Here, we develop an error correction, and de novo assembly tool designed to overcome complex errors in nanopore reads. We propose an adaptive read selection and two-step progressive method to quickly correct nanopore reads to high accuracy. We introduce a two-stage assembler to utilize the full length of nanopore reads. Our tool achieves superior performance in both error correction and de novo assembling nanopore reads. It requires only 8122 hours to assemble a 35X coverage human genome and achieves a 2.47-fold improvement in NG50. Furthermore, our assembly of the human WERI cell line shows an NG50 of 22 Mbp. The high-quality assembly of nanopore reads can significantly reduce false positives in structure variation detection.
Ferroptosis is a necrotic form of regulated cell death that was associated with lipid peroxidation and free iron‐mediated Fenton reactions. It has been reported that iron deficiency had been ...implicated in the pathogenesis of intervertebral disc degeneration (IVDD) by activating apoptosis. However, the role of ferroptosis in the process of IVDD has not been illuminated. Here, we demonstrate the involvement of ferroptosis in IVDD pathogenesis. Our in vitro models show the changes in protein levels of ferroptosis marker and enhanced lipid peroxidation level during oxidative stress. Safranin O staining, hematoxylin‐eosin staining, and immunohistochemical were used to assess the IVDD after 8 weeks of surgical procedure in vivo. Treatment with ferrostatin‐1, deferoxamine, and RSL3 demonstrate the role of ferroptosis in tert‐butyl hydroperoxide (TBHP)‐treated annulus fibrosus cells (AFCs) and nucleus pulposus cells (NPCs). Ferritinophagy, nuclear receptor coactivator 4 (NCOA4)‐mediated ferritin selective autophagy, is originated during the process of ferroptosis in response to TBHP treatment. Knockdown and overexpression NCOA4 further prove TBHP may induce ferroptosis of AFCs and NPCs in an autophagy‐dependent way. These findings support a role for oxidative stress‐induced ferroptosis in the pathogenesis of IVDD.
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Ferroptosis is a necrotic form of regulated cell death that was associated with lipid peroxidation and free iron‐mediated Fenton reactions. It has been reported that iron deficiency had been implicated in the pathogenesis of intervertebral disc degeneration (IVDD) by activating apoptosis. However, the role of ferroptosis in the process of IVDD has not been illuminated. Here, we demonstrate the involvement of ferroptosis in IVDD pathogenesis.
An imidazolium‐type room‐temperature ionic liquid containing silsesquioxane frameworks is successfully prepared. The polar ionic liquid products are grafted onto the surface of prepared aromatic ...polyamide (PA) membranes to improve water flux of PA membranes. Membranes grafted with an ionic liquid exhibit a water flux of 1.89 L m−2 h−1 bar−1), 48% higher than that of pure PA membranes while the salt rejection still remains at 96%. This improvement can be attributed to the enhanced hydrophilicity of the membrane surface, as evidenced by the reduced water contact angle.
Imidazolium‐type ionic liquids containing silsesquioxane frameworks are prepared and grafted onto the surface of polyamide membranes to enhance the water flux of polyamide membranes. The results show that the water flux of membranes grafted with ionic liquid is increased by 48% compared with pure polyamide membranes while salt rejection is still high at 96%.
Pancreatic cancer (PC) is a serious malignancy with high mortality and poor prognosis due to nonspecific incipient symptoms and early metastasis. Also, increasing evidence indicates that a panel of ...genes is newly identified in the pathogenesis of PC. As is a regulatory subunit, elevated cyclin B1 (CCNB1) expression has been detected in different cancers including PC. This study is designed to investigate the effects of CCNB1 silencing on cell cycle, senescence, and apoptosis through the p53 signaling pathway in PC. PC tissues and normal pancreatic tissues were collected. Cells were transfected and assigned into different groups. The expressions of CCNB1, p53, MDM2, Bax, caspase‐9, caspase‐3, and p21 in tissues and cells were detected by reverse transcription quantitative polymerase chain reaction and western blot analysis. β‐Galactosidase staining, MTT assay, and flow cytometry were conducted to test cell senescence, proliferation, cell cycle, and apoptosis. PC tissues showed higher expressions of CCNB1 and MDM2 and lower expressions of Bax, caspase‐9, caspase‐3, and p21. Cells transfected with shCCNB1 had lower expressions of CCNB1 and MDM2, whereas higher expressions of Bax, caspase‐9, caspase‐3, p53, and p21. The shCCNB1 group had decreased proliferation and S‐phase cell proportion and increased apoptosis, senescence, and G0/G1‐phase cell proportion. The PFT‐α group showed higher expressions of MDM2 and lower expressions of Bax, caspase‐9, caspase‐3, p53, and p21. The PFT‐α group had increased proliferation and S‐phase cell proportion and declined apoptosis, senescence, and G0/G1‐phase cell proportion. CCNB1 silencing inhibits cell proliferation and promotes cell senescence via activation of the p53 signaling pathway in PC.
CCNB1 silencing inhibits cell proliferation and promotes cell senescence via activation of the p53 signaling pathway in pancreatic cancer.
Physical Properties of 5 Root Canal Sealers Zhou, Hui-min, PhD; Shen, Ya, DDS, PhD; Zheng, Wei, PhD ...
Journal of endodontics,
10/2013, Letnik:
39, Številka:
10
Journal Article
Recenzirano
Abstract Introduction The aim of this study was to evaluate the pH change, viscosity and other physical properties of 2 novel root canal sealers (MTA Fillapex and Endosequence BC) in comparison with ...2 epoxy resin-based sealers (AH Plus and ThermaSeal), a silicone-based sealer (GuttaFlow), and a zinc oxide-eugenol–based sealer (Pulp Canal Sealer). Methods ISO 6876/2001 specifications were followed. The pH change of freshly mixed and set sealers was evaluated during periods of 1 day and 5 weeks, respectively. The viscosity was investigated at different injection rates (72, 10, and 5 mm/min) at room temperature by using a syringe-based system that was based on the Instron 3360 series universal testing system. Results The flow, dimensional change, solubility, and film thickness of all the tested sealers were in agreement with ISO 6876/2001 recommendations. The MTA Fillapex sealer exhibited a higher flow than the Endosequence BC sealer ( P < .05). The MTA Fillapex and Endosequence BC sealers showed the highest film thicknesses among the tested samples. The Endosequence BC sealer exhibited the highest value of solubility, which was in accordance with 3% mass fraction recommended by the ISO 6876/2001, and showed an acceptable dimensional change. The MTA Fillapex and Endosequence BC sealers presented an alkaline pH at all times. The pH of fresh samples of the AH Plus and ThermaSeal sealers was alkaline at first but decreased significantly after 24 hours. The viscosity of the tested sealers increased with the decreased injection rates. Conclusions The tested sealers were pseudoplastic according to their viscosities as determined in this study. The MTA Fillapex and Endosequence BC sealers each possessed comparable flow and dimensional stability but higher film thickness and solubility than the other sealers tested.
High dose and long‐term steroid treatment can alter antioxidative ability and decrease the viability and function of osteoblasts, leading to osteoporosis and osteonecrosis. Ferroptosis, a new type of ...cell death characterized by excessive lipid peroxidation due to the downregulation of GPX4 and system Xc−, is involved in glucocorticoid‐induced osteoporosis. Endothelial cell‐secreted exosomes (EC‐Exos) are important mediators of cell‐to‐cell communication and are involved in many physiological and pathological processes. However, the effect of EC‐Exos on osteoblasts exposed to glucocorticoids has not been reported. Here, we explored the role of EC‐Exos in glucocorticoid‐induced osteoporosis. In vivo and in vitro experiments indicated that EC‐Exos reversed the glucocorticoid‐induced osteogenic inhibition of osteoblasts by inhibiting ferritinophagy‐dependent ferroptosis.
Here, we explored the role of EC‐Exos in glucocorticoid‐induced osteoporosis. In vivo and in vitro experiments indicated that EC‐Exos reversed the glucocorticoid‐induced osteogenic inhibition of osteoblasts by inhibiting ferritinophagy‐dependent ferroptosis.
The trapping reactions of carbene analogs G14F2 (G14 = group 14 element) by the benzene‐bridged B/P‐Rea frustrated Lewis pair (FLPs) molecule are studied using density functional theory ...(B3LYP‐D3(BJ)/def2‐TZVP). Our theoretical investigations predict that only the CF2 intermediate rather than other heavy carbene analogs can be trapped by the B/P‐Rea FLP‐type molecule. Energy decomposition analysis‐natural orbitals for chemical valence (EDA‐NOCV) analyses indicate that the bonding nature of the G14F2 catching reactions by the B/P‐Rea FLP‐type molecule is a donor–acceptor (singlet–singlet) interaction rather than an electron‐sharing (triplet–triplet) interaction. Moreover, EDA‐NOCV and frontier molecular orbital (FMO) theory findings strongly suggest that the lone pair (LP) (P) → vacant p–π‐orbital (G14F2) interaction rather than the empty σ‐orbital (B) ← sp2‐σ‐orbital (G14F2) interaction plays a predominant role in establishing its bonding condition during the G14F2 trapping reaction with the B/P‐Rea FLP‐associated molecule. Our activation strain model findings reveal that the atomic radius of the G14 element of G14F2 plays a key role in determining the activation barrier of the G14F2 trapping reactions by the benzene‐bridged B/P‐Rea FLP. The valence bond state correlation diagram (VBSCD) model developed by Shaik is used to rationalize the calculated results. The VBSCD findings demonstrate that in the present trapping reactions, the singlet triplet splitting of G14F2 plays a significant role in influencing its reaction barrier and reaction enthalpy. Our theoretical results demonstrate that the relationship between the geometrical parameters of the transition states and the corresponding reaction free energy barriers agrees well with the findings based on the Hammond postulate.
The present theoretical examinations predict that only the B/P‐based FLP‐type molecule can catch the CF2 species rather than other carbene analogs containing a heavy group 14 element.
Abstract
AC asymmetry grid conditions put forward higher requirements for the stability control and performance of MMC-HVDC transmission systems. This thesis proposes a small-signal modeling method ...of an MMC-HVDC transmission system with differential flat control for AC asymmetry grid conditions, incorporating dynamic models of MMC internal characteristics, new control systems, circulation suppressors, and DC lines. To prove the accuracy of the pre-sended small-signal model, a two-terminal MMC-HVDC test system with differential flat control is constructed on the PSCAD/EMTDC platform.
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