Design and analysis of environmentally safe cooling systems for machine tools

Many cooling systems of metal cutting and both their advantages and disadvantages have been reviewed. The cutting forces\u27 relationships, stress distribution, energy consumption and heat generation of orthogonal processes are discussed. A two-dimensional finite element model has been developed to design and analyze a new proposed cooling device, which comes from the idea of A Novel Cooling Device proposed by Billatos et al. First, a thermal calculation is completed to compare the temperature difference between two different shapes of coiled pipe. Then, three different cutting conditions, which were considered in the experiments by Childs et al, are conducted under three varying cooling environment: Dry Cutting, New Cooling Device, and Wet Cutting for case studies. The corresponding temperature distributions around the cutting edge have been obtained by using the ANSYS package. Results showed that the proposed new cooling device does reduce the temperature of cutting tool comparing with the Dry Cutting, but it increases the temperature and temperature boundary of cutting tool comparing with Wet Cutting. This makes the proposed cooling device to be suitable under some cutting conditions when: 1. it is necessary to eliminate the cutting fluids and; 2. the maximum temperature of tool by using the device is below the temperature of tool thermal failure

A clinical study of drugs associated with acute kidney injury in the Chinese population

Purpose: To carry out a study aimed at comprehensive identificat6ion of classes of drugs which cause acute kidney injury (AKI).Methods: A total of 110,508 patients enrolled in Weihai Central Hospital, Weihai, Shandong, China between March 2014 to April 2018 were asked to provide information on comprehensive prescription drug coverage including antivirals, antibiotics, NSAIDs, diuretics and anti-cancer drugs. Only the active user  of these classes of drugs were included in the study. Daily prescription dose, duration, date and time of each drug were recorded. Furthermore, the characteristics and other conditions of the patients such as hypertension, congestive heart failure, diabetes, liver disease,  angiotensin receptor blockers (ARBs), alpha-receptor blockers, beta-receptor blockers, and calcium channel-blockers were included.Results: A total of 1230 patients presented with AKI during the first 60 days of follow-up, while 1546 (58 %) patients were diagnosed with AKI in the secondary endpoint. Indomethacin, valacyclovir, fluorouracil, levofloxacin, ibuprofen and rofecoxib produced higher frequencies of AKI than the control drug, celecoxib. Indomethacin (OR = 2.97 ; 95 % CI= 1.94 - 3.89) and valacyclovir (OR = 2.85 ; 95 % CI = 1.56 - 3.42) were mostly responsible for AKI, followed by rofecoxib (OR = 2.48 ; 95 % CI = 2.32 - 2.71), fluorouracil (OR = 2.58 ; 95 % CI = 1.94 - 3.11), ibuprofen (OR = 1.68 ; 95 % CI = 1.28 - 2.21) and levofloxacin (OR = 1.58 ; 95 % CI = 1.48 - 2.73), in that orderConclusion: This study has identified various classes of drugs which frequently induced AKI. Therefore, physicians should exercise caution in prescribing these drugs, and should consider other medicines to minimize the risk of AKI. Keywords: Acute kidney injury, Antiviral, NSAID, Toxicit

Optimization of Polling Systems and Dynamic Vehicle Routing Problems on Networks

We consider the problem of optimizing a polling system, i.e., of optimally sequencing a server in a multi-class queueing system with switch-over times in order to minimize a linear objective function of the waiting times. The problem has important applications in computer, communication, production and transportation networks. We propose nonlinear programming relaxations that provide strong lower bounds to the optimal cost for all static policies. We also obtain lower bounds for dynamic policies as well, which are primarily useful under light traffic conditions and/or small switch-over times. We conjecture that the lower bounds developed in this paper for the class of static policies are also valid for dynamic policies under heavy traffic conditions. We use the information from the lower bound and integer programming techniques to construct static policies that are very close (0-3%) to the lower bounds. We compare numerically our proposed policies with static policies proposed in the literature as well as with dynamic policies and find that the policies we propose outperform all static policies proposed in the literature and at least in heavier traffic outperform dynamic policies as well

A sub-critical barrier thickness normally-off AlGaN/GaN MOS-HEMT

A new high-performance normally-off gallium nitride (GaN)-based metal-oxide-semiconductor high electron mobility transistor that employs an ultrathin subcritical 3 nm thick aluminium gallium nitride (Al0.25Ga0.75N) barrier layer and relies on an induced two-dimensional electron gas for operation is presented. Single finger devices were fabricated using 10 and 20 nm plasma-enhanced chemical vapor-deposited silicon dioxide (SiO2) as the gate dielectric. They demonstrated threshold voltages (Vth) of 3 and 2 V, and very high maximum drain currents (IDSmax) of over 450 and 650 mA/mm, at a gate voltage (VGS) of 6 V, respectively. The proposed device is seen as a building block for future power electronic devices, specifically as the driven device in the cascode configuration that employs GaN-based enhancement-mode and depletion-mode devices

Effect of scopoletin on fascia-wrapped diced cartilage grafts

Purpose: To evaluate the effect of scopoletin (SL) on fascia-wrapped diced cartilage grafts in rhinoplasty surgery.Methods: Cartilage grafts (2 × 2 cm) from the ears of New Zealand rabbits were diced into sections (1 mm3) and then wrapped in muscle fascia taken from the right rear leg. Each graft was placed on the back of the animal after measuring its weight, and then the rabbits were separated into two groups, viz, control and the SL-treated groups {10 mg/kg, per os (p.o.)}. The treatments were administered for 3 months, the rabbits were sacrificed, and the histopathological features and weight of the grafts were examined.Results: The weight of the grafts in the two groups did not significantly (p < 0.05) differ but the histopathological results suggested that there was a pronounced increase in the viability of the graft tissues in the SL-treated group compared to the control group. Treatment with SL decreased the resorption rate and enhanced basophilia relative to the control group. However, fibrosis, inflammation, and bone metaplasia- and calcification-like factors did not significantly differ (p < 0.05).Conclusion: Treatment with SL significantly enhances the viability of the grafts, and thus may have a beneficial effect on fascia-wrapped diced cartilage grafts.Keywords: Scopoletin, Rhinoplasty surgery, Fascia-wrapped diced cartilage graft, Histopathology, Basophilia, Inflammatio

Effect of histone deacetylase inhibitor, trichostatin A, on cartilage regeneration from free perichondrial grafts in rabbits

Purpose: To evaluate the effect of histone deacetylase (HDAC) inhibitor, trichostatin A (TCA), on cartilage regeneration in a rabbit perichondrial graft model.Methods: Perichondrial grafts (20 × 20 mm2) were derived from the ears of New Zealand rabbits and transplanted onto the paravertebral muscle of the face of each rabbit. The rabbits were separated into three groups: non-treated control group, vehicle-treated control group that received 0.3 mL of saline, and TCA-treated group administered 0.3 mL of TCA (500 ng/mL). Rabbits in all three groups were further divided into subgroups according to the duration of treatment after transplantation: 2, 4, 6, and 8 weeks (n = 12 rabbits each). The effect of TCA on cartilage regeneration was determined histologically by evaluating the thickness of the cartilage plate in the grafted rabbits.Results: TCA increased the amount of immature cartilage 4 and 6 weeks after perichondrial graft implantation. Mature cartilage was seen in the TCA-treated rabbits 8 weeks after transplantation. The thickness of the cartilage plate was significantly (p < 0.01) higher in TCA group (905 ± 36) than in either the non-treated (632 ± 22) or the vehicle-treated control (639 ± 22) group.Conclusion: Treatment with trichostatin A, an HDAC inhibitor, enhances cartilage regeneration in rabbit recipients of a perichondrial graft. Furthermore, the findings of this study should be helpful in exploring the clinical use of trichostatin A.Keywords: Histone deacetylase inhibitor, Perichondrial graft, TrichostatinA, Cartilage regeneration, Transplantatio