Characterization of Avidin and Case9 Single Protein Molecules by a Solid-state Nanopore Device

The shape and charge of a protein play significant roles in protein dynamics in the biological system of humans and animals. Characterizing and quantifying the shape and charge of a protein at the single-molecule level remains a challenge. Solid-state nanopores made of silicon nitride (SiNx) have emerged as novel platforms for biosensing such as diagnostics for single-molecule detection and DNA sequencing. SSN detection is based on measuring the variations in ionic conductance as charged biomolecules translocate through nanometer-sized channels driven by an external voltage applied across the membrane. In this paper, we observe the translocation of asymmetric cylindrical structure CRISPR-Cas9 protein and symmetric cylindrical structure Avidin protein driven by an electric field through the solid-state nanopore. We also observe how glycerol impacts on the time durations and current blockage amplitudes produced by the translocation of two proteins in nanopore by using different glycerol concentrations

Application of bioabsorbable screw fixation for anterior cervical decompression and bone grafting

OBJECTIVES: To examine the application of bioabsorbable screws for anterior cervical decompression and bone grafting fixation and to study their clinical effects in the treatment of cervical spondylosis. METHODS: From March 2007 to September 2012, 56 patients, 36 males and 20 females (38-79 years old, average 58.3±9.47 years), underwent a novel operation. Grafts were fixed by bioabsorbable screws (PLLA, 2.7 mm in diameter) after anterior decompression. The bioabsorbable screws were inserted from the midline of the graft bone to the bone surface of the upper and lower vertebrae at 45 degree angles. Patients were evaluated post-operatively to observe the improvement of symptoms and evaluate the fusion of the bone. The Japanese Orthopaedic Association (JOA) score was used to evaluate the recovery of neurological functions. RESULTS: All screws were successfully inserted, with no broken screws. The rate of symptom improvement was 87.5%. All of the grafts fused well with no extrusion. The average time for graft fusion was 3.8±0.55 months (range 3-5 months). Three-dimensional reconstruction of CT scans demonstrated that the grafts fused with adjacent vertebrae well and that the screws were absorbed as predicted. The MRI findings showed that the cerebrospinal fluid was unobstructed. No obvious complications appeared in any of the follow-up evaluations. CONCLUSIONS: Cervical spondylosis with one- or two-level involvement can be effectively treated by anterior decompression and bone grafting with bioabsorbable screw fixation. This operative method is safe and can avoid the complications induced by metal implants

A network‐based variable selection approach for identification of modules and biomarker genes associated with end‐stage kidney disease

AimsIntervention for end‐stage kidney disease (ESKD), which is associated with adverse prognoses and major economic burdens, is challenging due to its complex pathogenesis. The study was performed to identify biomarker genes and molecular mechanisms for ESKD by bioinformatics approach.MethodsUsing the Gene Expression Omnibus dataset GSE37171, this study identified pathways and genomic biomarkers associated with ESKD via a multi‐stage knowledge discovery process, including identification of modules of genes by weighted gene co‐expression network analysis, discovery of important involved pathways by Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses, selection of differentially expressed genes by the empirical Bayes method, and screening biomarker genes by the least absolute shrinkage and selection operator (Lasso) logistic regression. The results were validated using GSE70528, an independent testing dataset.ResultsThree clinically important gene modules associated with ESKD, were identified by weighted gene co‐expression network analysis. Within these modules, Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses revealed important biological pathways involved in ESKD, including transforming growth factor‐β and Wnt signalling, RNA‐splicing, autophagy and chromatin and histone modification. Furthermore, Lasso logistic regression was conducted to identify five final genes, namely, CNOT8, MST4, PPP2CB, PCSK7 and RBBP4 that are differentially expressed and associated with ESKD. The accuracy of the final model in distinguishing the ESKD cases and controls was 96.8% and 91.7% in the training and validation datasets, respectively.ConclusionNetwork‐based variable selection approaches can identify biological pathways and biomarker genes associated with ESKD. The findings may inform more in‐depth follow‐up research and effective therapy.SUMMARY AT A GLANCEThis gene–gene network analysis to identify genes associated with end‐stage renal disease is an important step, albeit early, towards the discovery of biomarkers using peripheral blood cells. The findings also provide insight on disease pathophysiology at the molecular level, and hence therapeutic targets for future research.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/162799/2/nep13655.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/162799/1/nep13655_am.pd

Curved water flow characteristics and its influence on navigation

The ship movement is mainly affected by the circulation current in curve channel. In this paper, the curve circulation is taken as the research object, 3D model is established and scientific numerical simulation is carried out. In order to study and analyze the difference, three curve models with different bending degrees are established in this simulation. Finally, according to the simulation results, the measures for safe navigation are proposed

Medium access control for inter-gateway handoff support in multi-hop wireless mesh networks

Wireless mesh networks (WMNs) have emerged to be a key wireless technology to support large-scale wireless Internet access. Seamless inter-gateway handoff support is an essential issue to ensure continuous communications in multi-hop WMNs. When the movement of a mobile mesh node (MN) causes its attachment point change in the Internet, the complete handoff process may include two steps: the link-layer handoff and the network-layer handoff. During the network-layer handoff, network- layer signaling packets need to be transmitted between the MN and the Internet via the multi-hop wireless mesh backbone. Due to the multi-hop transmission of network- layer handoff signaling packets, the handoff performance in WMNs can be largely degraded by the long queueing delay and medium access delay at each mesh router, especially when the backbone traffic volume is high. However, this critical issue is ignored in existing handoff solutions of multi-hop WMNs. In addition, the channel contention between data packets and handoff signaling packets is not considered in existing medium access control (MAC) designs. In this research, the seamless handoff support is addressed from a different perspec- tive. By eliminating channel contentions between data and handoff signaling pack- ets, the queueing delay and channel access delay of signaling packets are reduced, while data throughput is maintained. Since various WMNs have different channel resources and hardware cost requirements, four MAC schemes are proposed to im- prove the multi-hop handoff performance in single-channel single-radio, single-channel multi-radio, multi-channel single-radio, and multi-channel multi-radio WMNs. With the proposed MAC schemes, the inter-gateway handoff performance can be improved significantly in multi-hop WMNs

Experimental Comparison of Constitutive Models for Magnetorheological Fluids Under Different Conditions

The accurate prediction of the viscosity and shear stress for magnetorheological (MR) fluids provides the basis for the preparation of MR fluids and the design of MR devices, where a proper model is a key. How to quickly choose an appropriate model to describe its rheological properties is important for the application of MR fluids. In this work, MR fluids with different mass fractions are prepared and their apparent viscosities and shear stresses are measured under different magnetic fields and shear rates. The obtained rheological parameters are fitted by the Bingham model, the Herschel–Bulkley model, and the Casson model to evaluate their fitting effects. It is found that the MR fluid can be regarded as a Newtonian fluid only if its mass fraction is less than 30 wt%, and there is no magnetic field. The shear thinning effect is the main cause of the constitutive model errors, and it is more likely to occur for the MR fluids with higher mass fractions but increasing magnetic field strength will inhibit it. However, the shear thinning effect caused by the high-rate shear is even stronger than the inhibition through increasing magnetic field strength. The highest shear yield stress is obtained with the Bingham model, followed by the Carson model, and finally the Herschel–Bulkley model. This work provides a guidance to accurately predict the shear stress of MR fluids through a suitable constitutive model.acceptedVersionPeer reviewe

Temperature effects and temperature-dependent constitutive model of magnetorheological fluids

The knowledge of the temperature effect on magnetorheological fluid is critical for accurate control of magnetorheological devices, since the temperature rise during operation is unavoidable due to coil energization, wall slip, and inter-particle friction. Based on a typical commercial magnetorheological fluid, this work investigates the effect of temperature on magnetorheological properties and its mechanisms. It is found that temperature has a significant effect on the zero-field viscosity and shear stress of magnetorheological fluid. The Herschel-Bulkley model that has high accuracy at room temperature does not describe accurately the shear stress of magnetorheological fluids at high temperatures, as its relative error is even up to 21% at 70 °C. By analyzing the sources of shear stress in magnetorheological fluids, a novel constitutive model with temperature prediction is proposed by combining the Navier–Stokes equation and viscosity-temperature equation. The experimental results show that the error of the novel constitutive model decreases by 90% at different temperatures and magnetic field strengths, exhibiting an excellent accuracy. This temperature-dependent constitutive model allows the properties of an MR fluid to be widely characterized only in a few experiments.acceptedVersionPeer reviewe