Study in the variation of mechanical properties of nodular cast iron depending upon section thickness

Cast iron has become a popular cast metal material which is widely used in modern industry and today's technology because of its low cost and desirable properties such as good castability, convenient machining properties, better wear resistance, etc. This paper is concerned with the variation of mechanical properties depending on section thickness of nodular cast iron. Firstly manufacturing process of GGG40 (EN‐GJS‐400‐15/DIN 1693 or 60‐40‐18/ASTM A536) nodular (ductile) cast iron was performed. Sand mould casting was only used as a molding process. Following, convenient moulds were prepared and the casting process was carried out in moulds that have different diameters (≤30 mm) to examine the cooling rate effects to the mechanical properties. Finally, tensile, hardness, metallography and fatigue tests were applied to cast materials test specimens. The results show that the cooling rate which is related to the section thickness affects the mechanical properties clearly.     

Synthesis and Caracterization of Mesoporous FePO<Subscript>4</Subscript> as Positive Electrode Materials for Lithium Batteries

Mesoporous iron phosphates were synthesized using sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB) as surfactants. The material synthesized in the presence of SDS was not applied as a positive electrode active material of a lithium battery. The results show that the obtained FePO₄ has a mesoporous structure with a specific surface area of 70 m² g^?1 and a dominant pore diameter of 3 nm. Those mesoporous were characterized by different microstructural and electrochemical analyzes. Among the materials studied under different conditions, those calcined at 450°C preserve mesoporous structures and exhibit the best electrochemical performance when used as active materials of the positive electrodes of lithium batteries. Effectively, a relatively high specific capacity of 135 and 122 mAh g^?1 was registered at C/20 collected experimentally by the samples synthesized in the presence of SDS and CTAB, respectively.     

Chitotriosidase as a novel biomarker of early atherosclerosis in hemodialysis patients

Introduction: Increasing evidence suggests that inflammation and increased macrophage activity have a central role in pathogenesis of atherosclerosis. It is shown that chitotriosidase (CHIT‐1) is a marker of macrophage activity in atherosclerotic plaque, and is found associated with severity of atherosclerotic lesion. There is no data about CHIT‐1 activity of hemodialysis patients in the literature. Thus, we hypothesized that in hemodialysis patients, CHIT‐1 levels might be a novel biomarker in early atherosclerosis. Methods: Forty‐five hemodialysis patients were included in the study (age: 61.93 ± 13.34). Intima media thickness (IMT) was evaluated with high‐resolution B‐mode ultrasonography. Biomarker levels were measured in serum of patients. Findings: We found positive correlation among IMT, age (R: 0.426, P: 0.004) and, CHIT‐1 value (R: 0.462, P: 0.001) in spearman correlation analysis. When age, CRP, creatinine, P, Alb, CHIT‐1 were chosen as measures that can effect IMT in multiple regression model, IMT level was related with CHIT‐1 (Beta: 0,396, P: 0.012) and age (Beta: 0,313 P: 0,048) independently. Discussion: In conclusion, this is the first report showing that serum CHIT‐1 level was related independently with carotid IMT in hemodialysis patients. This biomarker might have an unknown role in the development of atherosclerosis during uremia.     

Intraoperative intravenous ketamine in combination with epidural analgesia: postoperative analgesia after renal surgery

We designed this double-blinded, randomized, controlled study to evaluate the effect of small-dose ketamine IV in combination with epidural morphine and bupivacaine on postoperative pain after renal surgery. An epidural catheter was inserted, and the administration of morphine and bupivacaine was started before surgery. Forty patients were assigned to one of two groups (ketamine or control). The ketamine group was administered a ketamine bolus and infusion during surgery. The median visual analog pain scale (VAS) scores at rest were significantly lower in the ketamine group during the first 6 h (P < 0.01). VAS pain scores on coughing were also significantly lower in the ketamine group (P < 0.01). Cumulative postoperative total analgesic consumption was less in the ketamine group on Days 1 and 2 (P < 0.001). The first analgesic demand time was shorter in the control group (9.2 +/- 11.5 min) than in the ketamine group (22.3 +/- 17.1 min) (P < 0.0001). The incidence of nausea and pruritus was more frequent in the control group (P < 0.05). In conclusion, postoperative analgesia was more effective when spinal cord and brain sensitization were blocked by a combination of epidural morphine/bupivacaine and IV ketamine. IMPLICATIONS: Renal nociception conducted multisegmentally by both the spinal nerves (T10 to L1) and the vagus nerve cannot be blocked by epidural analgesia alone. We demonstrated that IV ketamine had an improved analgesic or opioid-sparing effect when it was combined with epidural bupivacaine and morphine after renal surgery.     

Contribution of polyaniline coating to the stability and performance of nickel hydroxide based electroactive materials

This study has been conducted for investigating the contribution of polyaniline (PANI) to the electroactivity of nickel hydroxide (NH) by using a combination of electrochemical, structural and morphological characterization techniques. NH, PANI and nickel hydroxide/PANI composite (NHP) electrodes were produced on nickel foam substrates. Electrodeposition and chemical bath deposition methods were used for the preparation of NH and PANI, respectively. All the electrochemical experiments were conducted in alkaline solutions. NH and PANI were used as reference materials and exhibited properties in accordance with the literature. Namely, for NH electrode capacity decayed by cycling because of the phase transformation from α to β-Ni(OH)₂, and particles growth from 350 to 850 nm. Also, flower-like structure of the as prepared Ni(OH)₂ faded after 2000 cycles. On the other hand, PANI electrode although exhibited a decrease in the conductivity because of its degradation retained its capacity over cycling because of swelling and shrinking that led to an increased surface area. Composite electrode consisting of PANI and NH resulted in an improvement of capacity retention. At the beginning of cycling capacitance of the composite electrode was 0.64 F/cm², capacity decreased to 0.47 F/cm² after 500 cycles then, continuously increased and finally reached to 0.54 F/cm² after 2000 cycles. Presence of PANI in combination with NH, limited the particle growth and contributed to the preservation of flower like structure of NH. Contrary to both NH and PANI electrodes, charge transfer resistance of NHP exhibited a decrease with cycling indicating a synergy between NH and PANI in addition to morphological changes.