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Zhang D.,Northwestern Polytechnical University | Qi L.,Northwestern Polytechnical University | Luo J.,Northwestern Polytechnical University | Yi H.,Northwestern Polytechnical University | And 2 more authors.
Journal of Materials Processing Technology | Year: 2017

Micro metal droplet deposition manufacturing shows great potential applications in many industrial areas such as micro circuits printing, thin-wall metal parts, porous metal parts, and heterogeneous material parts. However, excessive overlapping of metal droplets in corners deteriorates the quality of printed parts. To solve this problem, the droplet center-to-center distance must always keep uniform and be in an ideal range. First, reasons of excessive overlapping in corners are analyzed and a mathematical model is proposed. Then droplet center-to-center distance is optimized and compensated according to corner angle of contour lines and number total of droplets so that the distance between adjacent droplets is proper. The coordinate of rearranged droplets is obtained by calculation. To verify this method, uniform solder droplets were ejected and deposited on a flat substrate. A series of deposition experiments were carried out. Some triangle contours were formed. The results show that quality of the formed parts had been significantly improved by using the proposed method. © 2017 Elsevier B.V.

Di Stefano M.,A-Life Medical | Di Stefano M.,Royal Free Hospital | Loreto A.,A-Life Medical | Loreto A.,University of Cambridge | And 13 more authors.
Current Biology | Year: 2017

Axons require the axonal NAD-synthesizing enzyme NMNAT2 to survive. Injury or genetically induced depletion of NMNAT2 triggers axonal degeneration or defective axon growth. We have previously proposed that axonal NMNAT2 primarily promotes axon survival by maintaining low levels of its substrate NMN rather than generating NAD; however, this is still debated. NMN deamidase, a bacterial enzyme, shares NMN-consuming activity with NMNAT2, but not NAD-synthesizing activity, and it delays axon degeneration in primary neuronal cultures. Here we show that NMN deamidase can also delay axon degeneration in zebrafish larvae and in transgenic mice. Like overexpressed NMNATs, NMN deamidase reduces NMN accumulation in injured mouse sciatic nerves and preserves some axons for up to three weeks, even when expressed at a low level. Remarkably, NMN deamidase also rescues axonal outgrowth and perinatal lethality in a dose-dependent manner in mice lacking NMNAT2. These data further support a pro-degenerative effect of accumulating NMN in axons in vivo. The NMN deamidase mouse will be an important tool to further probe the mechanisms underlying Wallerian degeneration and its prevention. © 2017 The Authors

Johnson M.F.,University of NottinghamNottingham
Water Resources Research | Year: 2015

Rising water temperature (Tw) due to anthropogenic climate change may have serious consequences for river ecosystems. Conservation and/or expansion of riparian shade could counter warming and buy time for ecosystems to adapt. However, sensitivity of river reaches to direct solar radiation is highly heterogeneous in space and time, so benefits of shading are also expected to be site specific. We use a network of high-resolution temperature measurements from two upland rivers in the UK, in conjunction with topographic shade modeling, to assess the relative significance of landscape and riparian shade to the thermal behavior of river reaches. Trees occupy 7% of the study catchments (comparable with the UK national average) yet shade covers 52% of the area and is concentrated along river corridors. Riparian shade is most beneficial for managing Tw at distances 5-20 km downstream from the source of the rivers where discharge is modest, flow is dominated by near-surface hydrological pathways, there is a wide floodplain with little landscape shade, and where cumulative solar exposure times are sufficient to affect Tw. For the rivers studied, we find that approximately 0.5 km of complete shade is necessary to off-set Tw by 1°C during July (the month with peak Tw) at a headwater site; whereas 1.1 km of shade is required 25 km downstream. Further research is needed to assess the integrated effect of future changes in air temperature, sunshine duration, direct solar radiation, and downward diffuse radiation on Tw to help tree planting schemes achieve intended outcomes. © 2015. American Geophysical Union. All Rights Reserved.

Cortellino F.,University of NottinghamNottingham | Hyde T.H.,University of NottinghamNottingham | Sun W.,University of NottinghamNottingham
Energy Materials: Materials Science and Engineering for Energy Systems | Year: 2013

This paper reports the results of elastic–creep finite element (FE) analyses of a P91 steel pipe weld with two external ‘type IV’ circumferential cracks, subjected to internal pressure and end (system) load using creep properties obtained at 650uC. Numerical contour integral calculations have been performed to obtain both transient and stationary high temperature fracture mechanics parameters. A mesh sensitivity analysis was performed in order to ensure the accuracy of FE analyses in the transient creep stage. The effects of load magnitude, the material mismatch near the crack surfaces and the crack depth on the stationary creep C* contour integrals have been investigated, and corresponding analytical correlations are presented. © W. S. Maney and Son Ltd. 2013.

Brew I.F.,Leeds Community Healthcare NHS TrustLeeds UK | Williamson J.,Leeds Community Healthcare NHS TrustLeeds UK | Miners A.,London School of Hygiene and Tropical Medicine | Irving W.L.,University of NottinghamNottingham | And 4 more authors.
Hepatology | Year: 2016

Prisoners have a high prevalence of hepatitis C virus (HCV), but case-finding may not have been cost-effective because treatment often exceeded average prison stay combined with a lack of continuity of care. We assessed the cost-effectiveness of increased HCV case-finding and treatment in UK prisons using short-course therapies. A dynamic HCV transmission model assesses the cost-effectiveness of doubling HCV case-finding (achieved through introducing opt-out HCV testing in UK pilot prisons) and increasing treatment in UK prisons compared to status quo voluntary risk-based testing (6% prison entrants/year), using currently recommended therapies (8-24 weeks) or interferon (IFN)-free direct-acting antivirals (DAAs; 8-12 weeks, 95% sustained virological response, £3300/week). Costs (British pounds, £) and health utilities (quality-adjusted life years) were used to calculate mean incremental cost-effectiveness ratios (ICERs). We assumed 56% referral and 2.5%/25% of referred people who inject drugs (PWID)/ex-PWID treated within 2 months of diagnosis in prison. PWID and ex-PWID or non-PWID are in prison an average 4 and 8 months, respectively. Doubling prison testing rates with existing treatments produces a mean ICER of £19,850/quality-adjusted life years gained compared to current testing/treatment and is 45% likely to be cost-effective under a £20,000 willingness-to-pay threshold. Switching to 8-week to 12-week IFN-free DAAs in prisons could increase cost-effectiveness (ICER £15,090/quality-adjusted life years gained). Excluding prevention benefit decreases cost-effectiveness. If >10% referred PWID are treated in prison (2.5% base case), either treatment could be highly cost-effective (ICER<£13,000). HCV case-finding and IFN-free DAAs could be highly cost-effective if DAA cost is 10% lower or with 8 weeks' duration. Conclusions: Increased HCV testing in UK prisons (such as through opt-out testing) is borderline cost-effective compared to status quo voluntary risk-based testing under a £20,000 willingness to pay with current treatments but likely to be cost-effective if short-course IFN-free DAAs are used and could be highly cost-effective if PWID treatment rates were increased. © 2016 The Authors. Hepatology published by Wiley Periodicals, Inc., on behalf of the American Association for the Study of Liver Diseases.

Tracy S.R.,University of NottinghamNottingham | Sturrock C.J.,University of NottinghamNottingham | Crout N.M.J.,University of NottinghamNottingham | Mooney S.J.,University of NottinghamNottingham
Water Resources Research | Year: 2015

We demonstrate the application of a high-resolution X-ray Computed Tomography (CT) method to quantify water distribution in soil pores under successive reductive drying. We focus on the wet end of the water release characteristic (WRC) (0 to -75 kPa) to investigate changes in soil water distribution in contrasting soil textures (sand and clay) and structures (sieved and field structured) and to determine the impact of soil structure on hydraulic behavior. The 3-D structure of each soil was obtained from the CT images (at a 10 μm resolution). Stokes equations for flow were solved computationally for each measured structure to estimate hydraulic conductivity. The simulated values obtained compared extremely well with the measured saturated hydraulic conductivity values. By considering different sample sizes we were able to identify the smallest possible representative sample size which is required to determine a globally valid hydraulic conductivity. © 2015 American Geophysical Union.

Yaghi A.H.,Manufacturing Technology Center | Hyde T.H.,University of NottinghamNottingham | Becker A.A.,University of NottinghamNottingham | Sun W.,University of NottinghamNottingham
Energy Materials: Materials Science and Engineering for Energy Systems | Year: 2013

Finite element (FE) simulations of the welding of two high grade steel pipes are described. The first is a P91 steel pipe welded with a similar P91 weld consumable, and the second is a P92 steel pipe welded with dissimilar nickel–chromium based weld consumables. Both welds are multipass circumferential butt welds, having 73 weld beads in the P91 pipe and 36 beads in the P92 pipe. Since the pipes and welds are symmetric around their axes, the FE simulations are axisymmetric, allowing high FE mesh refinement and residual stress prediction accuracy. The FE simulations of the welding of the P91 and P92 pipes comprise thermal and sequentially coupled structural analyses. The thermal analyses model the heat evolution produced by the welding arc, determining the temperature history throughout the FE models. Structural analyses use the computed temperature history as input data to predict the residual stress fields throughout the models. Post-weld heat treatment (PWHT) of both pipes has also been numerically simulated by assuming that the FE models obey the Norton creep law during the hold time period at 760uC. The residual stresses presented here have all been validated by corresponding experimental measurements. Before PWHT, it has been found that, at certain locations in the weld region and heat affected zone (HAZ) in the pipes, tensile hoop and axial residual stresses approach the tensile strength of the material, presenting a high risk of failure. It has also been found that PWHT substantially reduces the magnitude of residual stresses by varying degrees depending on the material. © 2013, Chinese Journal of Ecology All Rights Reserved.

PubMed | University of British Columbia, University of NottinghamNottingham and University of Nottingham
Type: Journal Article | Journal: American journal of translational research | Year: 2016

There has been an escalating interest in the medicinal use of Cannabis sativa in recent years. Cannabis is often administered orally with fat-containing foods, or in lipid-based pharmaceutical preparations. However, the impact of lipids on the exposure of patients to cannabis components has not been explored. Therefore, the aim of this study is to elucidate the effect of oral co-administration of lipids on the exposure to two main active cannabinoids, (9)-tetrahydrocannabinol (THC) and cannabidiol (CBD). In this study, oral co-administration of lipids enhanced the systemic exposure of rats to THC and CBD by 2.5-fold and 3-fold, respectively, compared to lipid-free formulations. In vitro lipolysis was conducted to explore the effect of lipids on the intestinal solubilisation of cannabinoids. More than 30% of THC and CBD were distributed into micellar fraction following lipolysis, suggesting that at least one-third of the administered dose will be available for absorption following co-administration with lipids. Both cannabinoids showed very high affinity for artificial CM-like particles, as well as for rat and human CM, suggesting high potential for intestinal lymphatic transport. Moreover, comparable affinity of cannabinoids for rat and human CM suggests that similar increased exposure effects may be expected in humans. In conclusion, co-administration of dietary lipids or pharmaceutical lipid excipients has the potential to substantially increase the exposure to orally administered cannabis and cannabis-based medicines. The increase in patient exposure to cannabinoids is of high clinical importance as it could affect the therapeutic effect, but also toxicity, of orally administered cannabis or cannabis-based medicines.

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