118 research outputs found
Coupled Oxidation-Extraction Desulfurization : A Novel Evaluation for Diesel Fuel
This work was financially supported by the National Science Foundation of China (21176021, 21276020, 2187081257). We extend our appreciation to the Deanship of Scientific Research at King Saud University for funding the work, through Research Group Project No. RG-1436-026.Peer reviewedPostprin
Mcm5 Represses Endodermal Migration through Cxcr4a-itgb1b Cascade Instead of Cell Cycle Control
Minichromosome maintenance protein 5 (MCM5) is a critical cell cycle regulator; its role in DNA replication is well known, but whether it is involved in the regulation of organogenesis in a cell cycle-independent way, is far from clear. In this study, we found that a loss of mcm5 function resulted in a mildly smaller liver, but that mcm5 overexpression led to liver bifida. Further, the data showed that mcm5 overexpression delayed endodermal migration in the ventral–dorsal axis and induced the liver bifida. Cell cycle analysis showed that a loss of mcm5 function, but not overexpression, resulted in cell cycle delay and increased cell apoptosis during gastrulation, implying that liver bifida was not the result of a cell cycle defect. In terms of its mechanism, our data proves that mcm5 represses the expression of cxcr4a, which sequentially causes a decrease in the expression of itgb1b during gastrulation. The downregulation of the cxcr4a-itgb1b cascade leads to an endodermal migration delay during gastrulation, as well as to the subsequent liver bifida during liver morphogenesis. In conclusion, our results suggest that in a cell cycle-independent way, mcm5 works as a gene expression regulator, either partially and directly, or indirectly repressing the expression of cxcr4a and the downstream gene itgb1b, to coordinate endodermal migration during gastrulation and liver location during liver organogenesis
TRANSIENT VOLTAGE SUPPRESSOR BASED ON DIODE-TRIGGERED LOW-VOLTAGE SILICON CONTROLLED RECTIFIER
Transient voltage suppressor (TVS) has been widely used for electronic system ESD protection. A good TVS is usually costive as it needs some special processes and with extra masking layers for fabrication. A novel TVS design based on the standard CMOS process will be much attractive. This work proposes a new TVS device using a CMOS compatible diode-triggered silicon controlled rectifier (DLVTSCR) as the core device. Due to the available of multiple trigger mechanisms and the dual current paths for bypassing the ESD current, the newly proposed device is able to sink an ESD current of over 10 A. In addition, the holding voltage is promoted up to 6.83 V and the trigger voltage is lowered down to 10.8 V which is well suit for most portable device applications
Portable wireless electrocorticography system with a fexible microelectrodes array for epilepsy treatment
In this paper, we present a portable wireless electrocorticography (ECoG) system. It uses a high
resolution 32-channel fexible ECoG electrodes array to collect electrical signals of brain activities and to
stimulate the lesions. Electronic circuits are designed for signal acquisition, processing and transmission
using Bluetooth Low Energy 4 (LTE4) for wireless communication with cell phone. In-vivo experiments
on a rat show that the fexible ECoG system can accurately record electrical signals of brain activities
and transmit them to cell phone with a maximal sampling rate of 30 ksampling/s per channel. It
demonstrates that the epilepsy lesions can be detected, located and treated through the ECoG system.
The wireless ECoG system has low energy consumption and high brain spatial resolution, thus has great
prospects for future application
Emulsion Electrospinning of Polytetrafluoroethylene (PTFE) Nanofibrous Membranes for High-Performance Triboelectric Nanogenerators
Electrospinning
is a simple, versatile technique for fabricating
fibrous nanomaterials with the desirable features of extremely high
porosities and large surface areas. Using emulsion electrospinning,
polytetrafluoroethylene/polyethene oxide (PTFE/PEO) membranes
were fabricated, followed by a sintering process to obtain pure PTFE
fibrous membranes, which were further utilized against a polyamide
6 (PA6) membrane for vertical contact-mode triboelectric nanogenerators
(TENGs). Electrostatic force microscopy (EFM) measurements of the
sintered electrospun PTFE membranes revealed the presence of both
positive and negative surface charges owing to the transfer of positive
charge from PEO which was further corroborated by FTIR measurements.
To enhance the ensuing triboelectric surface charge, a facile negative
charge-injection process was carried out onto the electrospun (ES)
PTFE subsequently. The fabricated TENG gave a stabilized peak-to-peak
open-circuit voltage (<i>V</i><sub>oc</sub>) of up to ∼900
V, a short-circuit current density (<i>J</i><sub>sc</sub>) of ∼20 mA m<sup>–2</sup>, and a corresponding charge
density of ∼149 μC m<sup>–2</sup>, which are ∼12,
14, and 11 times higher than the corresponding values prior to the
ion-injection treatment. This increase in the surface charge density
is caused by the inversion of positive surface charges with the simultaneous
increase in the negative surface charge on the PTFE surface, which
was confirmed by using EFM measurements. The negative charge injection
led to an enhanced power output density of ∼9 W m<sup>–2</sup> with high stability as confirmed from the continuous operation of
the ion-injected PTFE/PA6 TENG for 30 000 operation cycles,
without any significant reduction in the output. The work thus introduces
a relatively simple, cost-effective, and environmentally friendly
technique for fabricating fibrous fluoropolymer polymer membranes
with high thermal/chemical resistance in TENG field and a direct ion-injection
method which is able to dramatically improve the surface negative
charge density of the PTFE fibrous membranes
Potential Novel Prediction of TMJ-OA: MiR-140-5p Regulates Inflammation Through Smad/TGF-β Signaling
Temporomandibular joint osteoarthritis (TMJ-OA), mainly exhibit extracellular matrix loss and condylar cartilage degradation, is the most common chronic and degenerative maxillofacial osteoarthritis; however, no efficient therapy for TMJ-OA exists due to the poor understanding of its pathological progression. MicroRNA (miR)-140-5p is a novel non-coding microRNAs (miRNAs) that expressed in osteoarthritis specifically. To investigate the molecular mechanisms of miR-140-5p in TMJ-OA, primary mandibular condylar chondrocytes (MCCs) from C57BL/6N mice were treated with interleukins (IL)-1β or transfected with miR-140-5p mimics or inhibitors, respectively. The expression of matrix metallopeptidase (MMP)-13, miR-140-5p, nuclear factor (NF)-kB, Smad3 and transforming growth factor (TGF)-β3 were examined by western blotting or quantitative reverse-transcription polymerase chain reaction (qRT-PCR). The interaction between the potential binding sequence of miR-140-5p and the 3′-untranslated region (3′UTR) of Smad3 mRNA was testified by dual-luciferase assay. Small Interfering RNA of Smad3 (Si-Smad3) was utilized to further identify the role of Smad3 mediated by miR-140-5p. The data showed MMP13, miR-140-5p and NF-kB increased significantly in response to IL-1β inflammatory response in MCCs, meanwhile, Smad3 and TGF-β3 reduced markedly. Moreover, transfection of miR-140-5p mimics significantly suppressed the expression of Smad3 and TGF-β3 in MCCs, while miR-140-5p inhibitors acted in a converse manner. As the luciferase reporter of Smad3 mRNA observed active interaction with miR-140-5p, Smad3 was identified as a direct target of miR-140-5p. Additionally, the expression of TGF-β3 was regulated upon the activation of Smad3. Together, these data suggested that miR-140-5p may play a role in regulating mandibular condylar cartilage homeostasis and potentially serve as a novel prognostic factor of TMJ-OA-like pathology
Charge Crowding in Graphene-Silicon Diodes
The performance of nanoscale electronic devices based on a two-three
dimensional (2D-3D) interface is significantly affected by the electrical
contacts that interconnect these materials with external circuitry. This work
investigates charge transport effects at the 2D-3D ohmic contact coupled with
the thermionic injection model for graphene/Si Schottky junction. Here, w e
focus on the intrinsic properties of graphene-metal contacts, paying particular
attention to the nature of the contact failure mechanism under high electrical
stress. According to our findings, severe current crowding (CC) effects in
highly conductive electrical contact significantly affect device failure that
can be reduced by spatially varying the contact properties and geometry. The
impact of electrical breakdown on material degradation is systematically
analyzed by atomic force, Raman, scanning electron, and energy dispersive X-ray
spectroscopies. Our devices withstand high electrostatic discharge spikes over
a longer period, manifesting high robustness and operational stability. This
research paves the way towards a highly robust and reliable graphene/Si
heterostructure in futuristic on-chip integration in dynamic switching. The
methods we employed here can be extended for other nanoscale electronic devices
based on 2D-3D interface
Mutations in influenza A virus neuraminidase and hemagglutinin confer resistance against a broadly neutralizing hemagglutinin stem antibody
Influenza A virus (IAV), a major cause of human morbidity and mortality, continuously evolves in response to selective pressures. Stem-directed, broadly neutralizing antibodies (sBnAbs) targeting influenza hemagglutinin (HA) are a promising therapeutic strategy, but neutralization escape mutants can develop. We used an integrated approach combining viral passaging, deep sequencing, and protein structural analyses to define escape mutations and mechanisms of neutralization escape in vitro for the F10 sBnAb. IAV was propagated with escalating concentrations of F10 over serial passages in cultured cells to select for escape mutations. Viral sequence analysis revealed three mutations in HA and one in neuraminidase (NA). Introduction of these specific mutations into IAV through reverse genetics confirmed their roles in resistance to F10. Structural analyses revealed that the selected HA mutations (S123G, N460S, and N203V) are away from the F10 epitope but may indirectly impact influenza receptor binding, endosomal fusion, or budding. The NA mutation E329K, which was previously identified to be associated with antibody escape, affects the active site of NA, highlighting the importance of the balance between HA and NA function for viral survival. Thus, whole genome population sequencing enables the identification of viral resistance mutations responding to antibody-induced selective pressure.IMPORTANCE Influenza A virus is a public health threat for which currently available vaccines are not always effective. Broadly neutralizing antibodies that bind to the highly-conserved stem region of influenza hemagglutinin (HA) can neutralize many influenza strains. To understand how influenza virus can become resistant or escape such antibodies, we propagated influenza A virus in vitro with escalating concentrations of antibody and analyzed viral populations with whole genome sequencing. We identified HA mutations near and distal to the antibody binding epitope that conferred resistance to antibody neutralization. Additionally, we identified a neuraminidase (NA) mutation that allowed the virus to grow in the presence of high concentrations of the antibody. Virus carrying dual mutations in HA and NA also grew under high antibody concentrations. We show that NA mutations mediate the escape of neutralization by antibodies against HA, highlighting the importance of a balance between HA and NA for optimal virus function
Asymmetry in Species Regional Dispersal Ability and the Neutral Theory
The neutral assumption that individuals of either the same or different species share exactly the same birth, death, migration, and speciation probabilities is fundamental yet controversial to the neutral theory. Several theoretical studies have demonstrated that a slight difference in species per capita birth or death rates can have a profound consequence on species coexistence and community structure. Whether asymmetry in migration, a vital demographic parameter in the neutral model, plays an important role in community assembly still remains unknown. In this paper, we relaxed the ecological equivalence assumption of the neutral model by introducing differences into species regional dispersal ability. We investigated the effect of asymmetric dispersal on the neutral local community structure. We found that per capita asymmetric dispersal among species could reduce species richness of the local community and result in deviations of species abundance distributions from those predicted by the neutral model. But the effect was moderate compared with that of asymmetries in birth or death rates, unless very large asymmetries in dispersal were assumed. A large difference in species dispersal ability, if there is, can overwhelm the role of random drift and make local community dynamics deterministic. In this case, species with higher regional dispersal abilities tended to dominate in the local community. However, the species abundance distribution of the local community under asymmetric dispersal could be well fitted by the neutral model, but the neutral model generally underestimated the fundamental biodiversity number but overestimated the migration rate in such communities
Isoflavone Content of Soybean Cultivars from Maturity Group 0 to VI Grown in Northern and Southern China
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