Anticorrosion Effect of Silicon Nitride and Zirconium Diboride Composite on Ni–P– Zn Electroless Deposition on Mild Steel

Electroless nicked-based deposition on mild steel surface from a nickel–zinc phosphate bath with NiSO4·6H2O, ZnSO4·7H2O, and NaH2PO2·H2O salt in the presence of silicon nitrides and zirconium diboride as additives at a constant time was studied. The structural evolution of electroless deposited mild steel surface was characterized for crystal change formation using a scanning electron microscope (SEM) and elemental quantification done using energydispersive spectroscopy (EDS). The electrochemical corrosion analysis of the deposited mild steel with and without composite additives was analyzed using linear polarization resistance and open circuit potential in both H2SO4 and NaCl solution. From the results, significant presence and the effect of wt% of additives were noticeable on the electroless mild steel surface. Ni–P–Zn in the presence of 10ZrBr2 and 10Si3N4 actively provide an induced weight gain of 0.0974 g and 0.0973 g, respectively. A correspondent, 0.034 g/m2 coating per unit area of zirconium diboride additives, was obtained against 0.030 g/m2 for silicon nitrides. The structural evolution shows proper homogeneous crystal formation and stable packed additive concentrated at the lattices with EDS showing the presence of induced peak. From the corrosion assessment result, electroless deposited mild steel with Ni–P–Zn–10ZrBr2 and Ni–P–Zn– 10Si3N4 with optimum particle concentration shows better corrosion resistance performance with a corrosion rate of 0.5048 mm/year, and 5.1347 mm/year, as against the unadditive deposition with 11.393 mm/year in NaCl solution

Experimental studies and influence of process factor on zinc-nickel based coating on mild steel

Sulphate-rich electrolytic bath containing ZnSO4.7H2O in NiP solution was used to develop coating with Ni-P-Zn matrix under optimised process parameter. The major considerations are to examine the factor variance and the effect of varying time parameter between 10, 15, 20 and 25 min on the developed coating. Wear loss evolution was examined using reciprocating sliding wear tester with a force of 10 N and 20 N. The microhardness behaviour was examined using durascan microhardness tester with diamond indenter. The change in the structural build-up and the corrosion performance trend was observed using a scanning electron microscope enhanced with energy dispersive spectroscopy and potentiodynamic polarisation route. From the result we observe that time-dependant factors impact maximally on the crystal growth which rightly influences the coating hardness performance. For wear performance, the counter with external forces couldn’t penetrate wholly into the lattice of the developed coating due to the resilient formation of stable flakes. The microstructure formation shows stable dispersed crystal build-up and homogeneous growth. An excellent corrosion resistance characteristic was noticed with Ni-P-Zn-25 min matrix

Characterization of different FAD-dependent glucose dehydrogenases for possible use in glucose-based biosensors and biofuel cells

In this study, different flavin adenine dinucleotide (FAD)-dependent glucose dehydrogenases (FADGDHs) were characterized electrochemically after “wiring” them with an osmium redox polymer [Os(4,4′-dimethyl-2,2′-bipyridine)2(PVI)10Cl]+ on graphite electrodes. One tested FADGDH was that recently discovered in Glomerella cingulata (GcGDH), another was the recombinant form expressed in Pichia pastoris (rGcGDH), and the third was a commercially available glycosylated enzyme from Aspergillus sp. (AspGDH). The performance of the Os-polymer “wired” GDHs on graphite electrodes was tested with glucose as the substrate. Optimal operational conditions and analytical characteristics like sensitivity, linear ranges and current density of the different FADGDHs were determined. The performance of all three types of FADGDHs was studied at physiological conditions (pH 7.4). The current densities measured at a 20 mM glucose concentration were 494 ± 17, 370 ± 24, and 389 ± 19 μA cm−2 for GcGDH, rGcGDH, and AspGDH, respectively. The sensitivities towards glucose were 2.16, 1.90, and 1.42 μA mM−1 for GcGDH, rGcGDH, and AspGDH, respectively. Additionally, deglycosylated rGcGDH (dgrGcGDH) was investigated to see whether the reduced glycosylation would have an effect, e.g., a higher current density, which was indeed found. GcGDH/Os-polymer modified electrodes were also used and investigated for their selectivity for a number of different sugars

Prader-Willi syndrome: A primer for clinicians

The advent of sensitive genetic testing modalities for the diagnosis of Prader-Willi syndrome has helped to define not only the phenotypic features of the syndrome associated with the various genotypes but also to anticipate clinical and psychological problems that occur at each stage during the life span. With advances in hormone replacement therapy, particularly growth hormone children born in circumstances where therapy is available are expected to have an improved quality of life as compared to those born prior to growth hormone

Biomimetic mineralization of metal-organic frameworks as protective coatings for biomacromolecules

Enhancing the robustness of functional biomacromolecules is a critical challenge in biotechnology, which if addressed would enhance their use in pharmaceuticals, chemical processing and biostorage. Here we report a novel method, inspired by natural biomineralization processes, which provides unprecedented protection of biomacromolecules by encapsulating them within a class of porous materials termed metal-organic frameworks. We show that proteins, enzymes and DNA rapidly induce the formation of protective metal-organic framework coatings under physiological conditions by concentrating the framework building blocks and facilitating crystallization around the biomacromolecules. The resulting biocomposite is stable under conditions that would normally decompose many biological macromolecules. For example, urease and horseradish peroxidase protected within a metal-organic framework shell are found to retain bioactivity after being treated at 80 °C and boiled in dimethylformamide (153 °C), respectively. This rapid, low-cost biomimetic mineralization process gives rise to new possibilities for the exploitation of biomacromolecules.Kang Liang, Raffaele Ricco, Cara M. Doherty, Mark J. Styles, Stephen Bell, Nigel Kirby, Stephen Mudie, David Haylock, Anita J. Hill, Christian J. Doonan, Paolo Falcar

Diffusion Monte Carlo Study of Para -Diiodobenzene Polymorphism Revisited

We revisit our investigation of the diffusion Monte Carlo (DMC) simulation of p-DIB molecular crystal polymorphism. [J. Phys. Chem. Lett. 2010, 1, 1789-1794] We perform, for the first time, a rigorous study of finite-size effects and choice of nodal surface on the prediction of polymorph stability in molecular crystals using fixed-node DMC. Our calculations are the largest which are currently feasible using the resources of the K computer and provide insights into the formidable challenge of predicting such properties from first principles. In particular, we show that finite-size effects can influence the trial nodal surface of a small (1×1×1) simulation cell considerably. We therefore repeated our DMC simulations with a 1×3×3 simulation cell, which is the largest such calculation to date. We used a DFT nodal surface generated with the PBE functional and we accumulated statistical samples with ∼6.4×105 core-hours for each polymorph. Our final results predict a polymorph stability consistent with experiment, but indicate that results in our previous paper were somewhat fortuitous. We analyze the finite-size errors using model periodic Coulomb (MPC) interactions and kinetic energy corrections, according to the CCMH scheme of Chiesa, Ceperley, Martin, and Holzmann. We investigate the dependence of the finite-size errors on different aspect ratios of the simulation cell (k-mesh convergence) in order to understand how to choose an appropriate ratio for the DMC calculations. Even in the most expensive simulations currently possible, we show that the finite size errors in the DMC total energies are far larger than the energy difference between the two polymorphs, although error cancellation means that the polymorph prediction is accurate. Finally, we found that the T-move scheme is essential for these massive DMC simulations in order to circumvent population explosions and large time-step biases.Chemistry and Chemical Biolog

Reliability of rapid diagnostic tests in diagnosing pregnancy and infant-associated malaria in Nigeria

SummaryBackgroundThe effective management of maternal and infant malaria requires rational and prompt diagnosis. This study aims to determine the diagnostic efficiency of malaria RDT in infants and pregnant women.MethodsThe study was conducted on infants (n=200), pregnant women (n=80) and non-pregnant women (n=100) who were recruited from two hospitals in Lagos, Nigeria. Plasmodium falciparum infections were assessed in the febrile subjects by microscopic examinations of blood smears and by RDT.ResultsThe lowest (44.3%) and the highest (83.3%) sensitivity (SS) values were recorded in the infants and pregnant women, respectively. Other diagnostic parameters, including the specificity (SP, 97.5%), positive predictive value (PPV, 92.1%) and negative predictive value (NPV, 72.8%), in the infants were greater than the values recorded in non-pregnant (SP=77.5%, PPV=83.9%, NPV=70.5%) and pregnant women populations (SP=65.6%, PPV=78.4%, NPV=72.4%). The diagnostic efficiency of malaria RDT exhibited higher sensitivity in women in early gestational stages (1st trimester=78.6% and 2nd trimester=88.0%) compared with those in the 3rd trimester (71.4%). The sensitivity of malaria RDT (100.0%) was significantly higher in the multigravid women than in the primigravida (78.6%) and secundigravida women (77.8%, P<0.05). The sensitivity of the RDT significantly increased with the intensity of the malarial parasites (P<0.05).ConclusionMalaria is endemic in the study populations. Malaria RDT can serve as a first-line of diagnosis for pregnant women in early gestational stages and multigravid women and can aid the differential diagnoses of other diseases due to its high specificity in infants