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Purpose Piston ring dynamic problem plays an important role in the lubricant characteristics of a reciprocating engine, which lead to engine wear and the increased consumption of lubricating oil. A cavitation analysis of the piston ring lubrication with two-dimensional Reynolds equation has rarely been reported owing to the complex working condition. The purpose of this study is to establish a precise model that can provide guidance for the design of the piston ring.Design/methodology/approach In this paper, a cavitation model and its effect on the piston ring lubrication was studied in a simulation program based on the mass-conserving theory which is solved by means of the Newton–Raphson method. In this study, some models such as mixed lubrication, asperity contact, blow-by/blow-back flow and cavitation have been coupled with the lubrication model.Findings The established model has been compared with the traditional model that deals with cavitation by using the Reynolds boundary condition algorithm. The cavitation zone, pressure distribution and density distribution between the piston ring and the cylinder have also been predicted. Studies of the changing trend for the pressure distribution and the cavitation zone at few typical crank angles have been listed to illustrate the cavitation changing rule. The analysis of the results indicates that the developed simulation model can adequately illustrate the lubrication problem of the piston ring system. All the analyses will provide guidance for the oil film rupture and the reformation process.Originality/value A two-dimensional cavitation model based on the mass-conserving theory has been built. The cavitation-forming and -developing process for the piston ring–liner lubrication has been studied. Non-cavitation occurs in the vicinity of top dead center and bottom dead center. The non-cavitation period will be longer in the vicinity of 360° of crank angle. The density distribution in the cavitation zone can be obtained. [ABSTRACT FROM AUTHOR]

As one of the most critical issues for target track, a-jerk model is an effective maneuver target track model. Non-Gaussian noises always exist in the track process, which usually lead to inconsistency and divergence of the track filter. A novel Kalman filter is derived and applied on a-jerk tracking model to handle non-Gaussian noise. The weighted least square solution is presented and the standard Kalman filter is deduced firstly. A novel Kalman filter with the weighted least square based on the maximum correntropy criterion is deduced. The robustness of the maximum correntropy criterion is also analyzed with the influence function and compared with the Huber-based filter, and, moreover, the kernel size of Gaussian kernel plays an important role in the filter algorithm. A new adaptive kernel method is proposed in this paper to adjust the parameter in real time. Finally, simulation results indicate the validity and the efficiency of the proposed filter. The comparison study shows that the proposed filter can significantly reduce the noise influence for a-jerk model. [ABSTRACT FROM AUTHOR]

We report on the fabrication of multiscale three-dimensional (3D) micropatterning of 0.5Ba(Zr 0.2 Ti 0.8 )O 3 − 0.5(Ba 0.7 Ca 0.3 )TiO 3 (BZT − BCT) electroceramic material using soft lithographic PDMS moulds. The ceramic microcomponents were successfully consolidated by Epoxy Gel Casting from stable aqueous suspension of BZT-BCT material. A successful aqueous processing of electroceramic material was employed with surface protection of powder particles against hydrolysis as considerably an important parameter to achieve high solid loading suspension with pseudoplastic behaviour suitable for casting in micro scale moulds. The process to obtain micro sized pattern of material was divided in two steps: (i) production of high quality SU-8 master moulds and the respective negative replicas in PDMS (soft mould) by photolithography and soft mould replication, respectively; (ii) casting the soft moulds by stable high solid loading BZT-BCT suspensions in presence of gelation agents followed by de-moulding, drying and sintering. The resulting green micropattern structures show interesting features, including complex structures with a periodic variations through their length and, multiscale array of hexagonal shaped pillars of different aspect ratios (AR) (max AR ≈ 8 with approx ∼320 μm of height and side length ∼40 μm) with smooth side wall features along height. The green pillar arrays were further sintered to show the suitability of aqueous processing of material and proposed casting method. [ABSTRACT FROM AUTHOR]

(Ba 0.7 Ca 0.3 )TiO 3 , (Ba 0.7 Ca 0.3 ) 0.995 Ti 0.99 Nb 0.01 O 3 and (Ba 0.7 Ca 0.3 )Ti 0.99 Mg 0.01 O 2.99 ceramics were prepared employing a solid state sintering method. The presence of Ti 4+ and structural changes were revealed by X-ray diffraction patterns and X-ray absorption spectra. Upon substitution of Nb 5+ and Mg 2+ ions, a decrease of the ferroelectric transition temperature near room temperature and relaxor-like features of the dielectric properties were observed in correlation with decreased tetragonality. The change in phase transition temperature affected significantly piezoelectricity and ferroelectricity of doped ceramics. The doping could enhance the dielectric properties near room temperature of BCT ceramic. The results here suggest that dielectric, piezoelectric and ferroelectric properties of BCT may be largely tunable by Nb and Mg dopants, and BCT could be an alternative material for ferroelectric devices. [ABSTRACT FROM AUTHOR]

In this work a method for sensitive anodic stripping voltammetric determination of Pb(II) ions using a poly xylenol orange film modified electrode (PXOFME) has been proposed. Poly xylenol orange film (PXOF) was formed on a paraffin impegrenated graphite electrode (PIGE) using electro polymerization method by scanning the potential between −0.5 V to 1.3 V, at a scan rate of 50 mV/s for 30 segments in 0.1 M phosphate buffer solution (PBS) of pH 7. The PXOFME was characterized by scanning electron microscopy (SEM), ATR-IR spectroscopy, cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). The modified electrode has been used to develop a sensitive method for the determination of Pb(II) ions by anodic stripping voltmmetry (ASV). The PXOFME was used to preconcentrate Pb(II) ions through complexation, the complexed metal ions were reduced electrochemically and then stripped anodically from the surface of the electrode. A linear range of 5 μg/L to 413 μg/L with a limit of detection (S/N=3) of 1.6 μg/L was observed for the determination of Pb(II) ions. The method was applied to lead determination in sea water and tap water samples and the results were found to be satisfactory. [ABSTRACT FROM AUTHOR]

Fourhorn sculpins ( Myoxocephalus quadricornis ) and shorthorn sculpins ( Myoxocephalus scorpius ) have been considered suitable local bioindicators for environmental monitoring studies in the Arctic. Because these species share many characteristics, data from the two species have previously been pooled when assessing marine metal contamination. A chemical and histological study was conducted on fourhorn and shorthorn sculpins collected around a contaminated lead-zinc mine at East Greenland to investigate whether there were any differences in the residues of metals, histopathology and parasites in liver and gills between the two sculpin species. The results demonstrated that concentrations of copper (Cu), zinc (Zn), mercury (Hg) and lead (Pb) were significantly higher in the fourhorn sculpins ( p <0.001) while there were no significant differences for arsenic (As) or cadmium (Cd). Furthermore, density of blood vessel fibrosis ( p =0.028), prevalence and density of chondroplasia ( p =0.002 and p =0.005, respectively), number of mucin-containing mucous cells ( p <0.001) and chloride cells ( p <0.001) and mean intensity of colonial Peritricha ( p <0.001) were significantly higher in fourhorn sculpin. Based on these results we suggest that pooling the two species when conducting environmental assessments is not recommended as it can lead to incorrect conclusions. We propose that a larger study investigating the biological effects of zinc-lead mining in Greenland is needed. [ABSTRACT FROM AUTHOR]

Introduction Lead exposure in shooting ranges has been under scrutiny for decades, but no information in this regard is available in respect of African settings, and in South Africa specifically. The aim of this study was to determine the blood lead levels in the users of randomly selected private shooting ranges in South Africa's Gauteng province. Methods An analytical cross sectional study was conducted, with participants recruited from four randomly selected shooting ranges and three archery ranges as a comparator group. Results A total of 118 (87 shooters and 31 archers) were included in the analysis. Shooters had significantly higher blood lead levels (BLL) compared to archers with 36/85 (42.4%) of shooters versus 2/34 (5.9%) of archers found to have a BLL ≥10 μg/dl (p<0.001). Conclusion Shooting ranges may constitute an import site of elevated exposure to lead. Improved ventilation, low levels of awareness of lead hazards, poor housekeeping, and inadequate personal hygiene facilities and practices at South African shooting ranges need urgent attention. [ABSTRACT FROM AUTHOR]

This paper deals with the occurrence of lead figurines of the goddess Venus in the area between the two cities of Sirmium and Viminacium. A classification into five types, based on stylistic and iconographic features, has been proposed. Although these types show features in common with products of other workshops in the Danubian basin, it has been observed that such products were not exchanged among the centres in the area. This paper puts forward the hypothesis that there were two centres of worship of the goddess Venus, in Sirmium and Viminacium, where these figurines could have been manufactured. [Projekat Ministarstva nauke Republike Srbije, br. 177007: Romanization, urbanization and transformation of urban centres of civil, military and residentialcharacter in Roman provinces on territory of Serbia]

Colloidal nanocrystals of lead halide perovskites have recently received great attention due to their remarkable performance in optoelectronic applications (e.g., light-emitting devices, flexible electronics, and photodetectors). However, the use of lead remains of great concern due to its toxicity and bioaccumulation in the ecosystem; herein we report a strategy to address this issue by using tetravalent tin (Sn4+) instead of divalent lead (Pb2+) to synthesize stable Cs2SnI6 perovskite nanocrystals. The shapes of as-synthesized Cs2SnI6 nanocrystals are tuned from spherical quantum dots, nanorods, nanowires, and nanobelts to nanoplatelets via a facile hot-injection process using inexpensive and nontoxic commercial precursors. Spherical aberration corrected scanning transmission electron microscopy (Cs-corrected STEM) and simulation studies revealed a well-defined face-centered-cubic (fcc) perovskite derivative structure of Cs2SnI6 nanocrystals. The solution-processed Cs2SnI6 nanocrystal-based field effect transistors (FETs) displayed a p-type semiconductor behavior with high hole mobility (>20 cm²/(V s)) and high I-ON/I-OFF ratio (>104) under ambient conditions. We envision that this work will pave the way to produce new families of high-performance, stable, low-cost and nontoxic nanocrystals for optoelectronic applications. [ABSTRACT FROM AUTHOR]

Purpose: This paper will give an overview of LCA studies on lead metal production and use recently conducted by the International Lead Association. Methods: The lead industry, through the International Lead Association (ILA), has recently completed three life cycle studies to assess the environmental impact of lead metal production and two of the products that make up approximately 90 % of the end uses of lead, namely lead-based batteries and architectural lead sheet. Results and discussion: Lead is one of the most recycled materials in widespread use and has the highest end-of-life recycling rate of all commonly used metals. This is a result of the physical chemical properties of the metal and product design, which makes lead-based products easily identifiable and economic to collect and recycle. For example, the end-of-life collection and recycling rates of lead automotive and industrial batteries and lead sheet in Europe are 99 and 95 %, respectively, making them one of the few products that operate in a true closed loop. These high recycling rates, coupled with the fact that both lead-based batteries and architectural lead sheet are manufactured from recycled material, have a beneficial impact on the results of LCA studies, significantly lowering the overall environmental impact of these products. This means that environmental impacts associated with mining and smelting of lead ores are minimised and in some cases avoided completely. The lead battery LCA assesses not only the production and end of life but also the use phase of these products in vehicles. The study demonstrates that the technological capabilities of innovative advanced lead batteries used in start-stop vehicles significantly offset the environmental impact of their production. A considerable offset is realised through the savings achieved in global warming potential when lead-based batteries are installed in passenger vehicles with start-stop and micro-hybrid engine systems which have significantly lower fuel consumption than regular engines. Conclusions: ILA has undertaken LCAs which investigate the environmental impact associated with the European production of lead metal and the most significant manufactured lead products (lead-based batteries used in vehicles and architectural lead sheet for construction) to ensure up-to-date and robust data is publically and widely available. [ABSTRACT FROM AUTHOR]

Lead-free piezoelectric ceramics belonging to the pseudo-binary system (1 − x )BaTi 0.8 Zr 0.2 O 3 - x Ba 0.7 Ca 0.3 TiO 3 (BCTZ, x = 0.32 and 0.5) were prepared using conventional sintering and spark plasma sintering. This comparative study shows how the macroscopic properties of ferroelectric BCTZ perovskites are affected when the grain size is decreased. The crystallographic structure and the microstructural characteristics are thoroughly investigated for ceramic samples obtained by both sintering methods. We clearly demonstrate that the dielectric, piezoelectric, pyroelectric and ferroelectric properties in SPS ceramics are strongly affected by the grain size and the structural defects leading to local strain fields which undermine the polarisation flexibility. This confirms that the critical compositions showing remarkably large piezoelectric coefficients are extremely sensitive to external and internal stresses. [ABSTRACT FROM AUTHOR]

Accumulation of heavy metals in unconsolidated soils can prove toxic to proximal environments, if measures are not taken to stabilize soils. One way to minimize the toxicity of metals in soils is the use of materials capable of immobilizing these contaminants by sorption. Biochar (BC) can retain large amounts of heavy metals due to, among other characteristics, its large surface area. In the current experiment, sugarcane-straw-derived biochar, produced at 700 °C, was applied to a heavy-metal-contaminated mine soil at 1.5, 3.0, and 5.0 % ( w/ w). Jack bean and Mucuna aterrima were grown in pots containing a mine contaminated soil and soil mixed with BC. Pore water was sampled to assess the effects of biochar on zinc solubility, while soils were analyzed by DTPA extraction to confirm available metal concentrations. The application of BC decreased the available concentrations of Cd, Pb, and Zn in the mine contaminated soil leading to a consistent reduction in the concentration of Zn in the pore water. Amendment with BC reduced plant uptake of Cd, Pb, and Zn with the jack bean uptaking higher amounts of Cd and Pb than M. aterrima. This study indicates that biochar application during mine soil remediation could reduce plant concentrations of heavy metals. Coupled with this, symptoms of heavy metal toxicity were absent only in plants growing in pots amended with biochar. The reduction in metal bioavailability and other modifications to the substrate induced by the application of biochar may be beneficial to the establishment of a green cover on top of mine soil to aid remediation and reduce risks. [ABSTRACT FROM AUTHOR]

A double-water-in-oil-emulsion procedure was designed to synthesize cadmium, lead and copper alginate nanobeads less than 200 nm diameter under mild conditions. The cadmium, lead and copper alginate nanobeads can be activated to immobilize biomacromolecules and can directly produce distinctive electrochemical signals. Using the novel alginate nanobeads labeled with antibodies as electrochemical probes, a sandwich-type immunosensor was constructed using AFP, CEA and PSA as model analytes. This proposed immunosensor shows wide linear range with detection limits of 0.01, 0.0086 and 0.0075 ng mL −1 for AFP, CEA and PSA, respectively. Analysis of clinical serum samples using this immunosensor was well consistent with the data determined by the enzyme-linked immunosorbent assay (ELISA). It suggested that the alginate nanobeads electrochemical probes could be generally extended to other multiple analytes detection. [ABSTRACT FROM AUTHOR]

The title compound, [Pb(C4H3N2S)2] n, was prepared by the reaction of [Pb(OAc)2]·3H2O (OAc is acetate) with pyrimidine-2-thione in the presence of triethylamine in methanol. In the crystal structure, the PbII atom has an N4S4 coordination environment with four ligands coordinated by N- and S-donor atoms. This compound shows that the pyrimidine-2-thiolate anion can lead to a three-dimensional network when the coordination number of the metal ion can be higher than 6, as is the case with the PbII ion. This compound presents only covalent bonds, showing that despite the possibility of the hemidirected geometries of PbII, the eight-coordinated ion does not allow the formation of an isolated molecular structure with pyrimidine-2-thiolate as the ligand. [ABSTRACT FROM AUTHOR]

Electrochemistry of lead telluride stationary electrode was studied in nitric acid solutions of pH 1.5-3.0. E-pH diagram for Pb-Te-H2O system was calculated. Results of cyclic voltammetry of Pb, Te and PbTe were discussed in correlation with thermodynamic predictions. Anodic dissolution of PbTe electrode at potential approx. -100÷50 mV (SCE) resulted in tellurium formation, while above 300 mV TeO2 was mainly produced. The latter could dissolve to HTeO+2 under acidic electrolyte, but it was inhibited by increased pH of the bath. [ABSTRACT FROM AUTHOR]

Further to the previously published work in this journal 'Towards a new coating for heritage lead', a coating has been trialled with samples replicating aged lead artefacts. Lead was corroded in an oak environment to simulate storage or display in a wooden case then coated with ethanolic solutions of tetradecanoic and octadecanoic acid. X-ray diffraction and electrochemical impedance data suggests an better-quality coating is formed leading to improved corrosion resistance.[Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Abstract: Recently, we reported substrate-based β-secretase (BACE1) inhibitors with a hydroxymethylcarbonyl (HMC) isostere as a substrate transition-state mimic. These inhibitors showed potent BACE1 inhibitory activities (∼1.2nM IC50). In order to improve in vivo enzymatic stability and permeability across the blood–brain barrier, these penta-peptidic inhibitors would need to be further optimized. On the other hand, non-peptidic inhibitors possessing isophthalic residue at the P2 position were reported from other research groups. We selected isophthalic-type aromatic residues at the P2 position and an HMC isostere at the P1 position as lead compounds. On the basis of the design approach focused on the conformer of docked inhibitor in BACE1, we found novel non-peptidic and small-sized BACE1 inhibitors possessing a 2,6-pyridinedicarboxylic, chelidamic or chelidonic residue at the P2 position. [Copyright &y& Elsevier]

Hierarchical eight-arm, star-shaped PbS single crystals have been successfully synthesized by the controlled release of sulfide ions from thioacetamide (TAA) at 80 °C in aqueous solutions of lead acetate and acetic acid. The unique star-shaped PbS crystals have eight symmetric arms along the 〈111〉 directions, each of which shows a trident-like, dendritic structure and consists of parallel PbS nanoleaflets. It has been revealed that the presence of acetate ions as well as appropriate pH and temperature are crucial for the formation of the unusual star-shaped PbS crystals. Moreover, other morphologies of PbS nanocrystals, such as nanorods, nanostrips, and nanosheets, have been obtained facilely at 40 °C by using similar synthetic procedures. [ABSTRACT FROM AUTHOR]

Thrombotic thrombocytopenic purpura (TTP)/hemolytic uremic syndrome (HUS) is a disease syndrome, and its history exemplifies how small observational studies lead to hypotheses that spawn randomized control trials (RCTs). Moschowitz's original case report coupled with the case findings of Bukowski and Byrne led to the RCT of Rock and the Canadian Apheresis Group that proved plasma exchange was superior to plasma infusion for the treatment of adults with TTP/HUS. Our single case report of continuous plasma exchange coupled with the observations about the pathogenic role of von Willebrand multimer protease of Tsai and Furlan strengthened by a 25-year observational study of plasma exchange treatment for TTP/HUS has led to a proposal to initiate a new RCT. [ABSTRACT FROM AUTHOR]