Solution combustion synthesis of cerium oxide nanoparticles as corrosion inhibitor

In this study, combustion synthesis of cerium oxide nanoparticles was reported using cerium nitrate hexahydrate as starting material as well as urea, glycine, glucose, and citric acid as fuels. The influence of fuel type on structure, microstructure, band gap, and corrosion inhibition was investigated. X-ray diffraction (XRD) patterns and scanning electron microscopy micrographs showed that CeO₂ nanoparticles with different morphologies were obtained depending on the fuel type. Microstructural changes from unreacted gel to sponge-like morphologies were resulted by varying the fuel type from urea, glycine, and glucose to citric acid. In addition to Ce–O bonds, Fourier transform infrared analysis showed carbon bonds of carbonaceous compositions from incomplete combustion which were declined during combustion reaction. Furthermore, corrosion analyses showed that samples synthesized using urea fuel released the most Ce⁺⁴ ions and could have better protection than other samples.     

Reverse iodine transfer polymerization of vinyl acetate and vinyl benzoate: synthesis and characterization of homo‐ and copolymers

Homo‐ and copolymers of vinyl esters including vinyl acetate (VAc) and vinyl benzoate (VBz) were synthesized via the reverse iodine transfer radical polymerization technique. Polymerization was carried out in the presence of iodine as the in situ generator of the transfer agent and 2,2′‐azobis(isobutyronitrile) as the initiator at 70 °C. Reverse iodine transfer radical homopolymerization of VAc and VBz led to conversions of 76 and 57%, number‐average molecular weights of 8266 and 9814 g mol^?1 and molecular weight distributions of 1.58 and 1.49, respectively. The microstructure of the synthesized polymers was investigated in detail using gel permeation chromatography, ¹H NMR, ¹³C NMR and distortionless enhancement of polarization transfer (135° decoupler pulse) techniques. Relatively narrow molecular weight distribution and controlled and predictable trend of molecular weight versus conversion were observed for the synthesized polymers, showing that reverse iodine transfer radical homo‐ and copolymerization of VAc and VBz proceeded with controlled characteristics. Results of molecular weight and its distribution along with the ¹H NMR spectra recorded for homo‐ and copolymers indicated that side reactions can occur during the course of polymerization with a significant contribution when VAc, even in a small amount, was present in the reaction mixture. This can result in polymer chains with aldehyde dead end and broadening of the molecular weight distribution. © 2015 Society of Chemical Industry     

A novel way to production yttrium glass microspheres for medical applications

In this paper a novel method of producing yttrium aluminum silicate microspheres is reported. Yttrium aluminum silicate microspheres around 20–50 μm in size were obtained when an aqueous solution of Y(NO₃)₃ and Al(NO₃)₃ was added to tetraethyl orthosilicate (TEOS) and pumped into stirred silicone oil. The particles produced by this method are regularly shaped and very close to spherical. The amorphous structure, Y-O-Si bonds, spherical shapes, composition, and element distribution were investigated by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray fluorescence spectroscopy (XRF), carbon/sulfur analysis, and SEM/EDS mapping analysis. The results obtained demonstrate that the silicone oil spheroidization method is suitable for the production of yttrium aluminum silicate microspheres. This study also reveals that a high temperature is not required for the production of yttrium aluminum silicate microspheres.     

Open-cell polyvinylidene fluoride foams as carriers to promote biofilm growth for biological wastewater treatment

This article reports the design and fabrication of open-cell polyvinylidene fluoride (PVDF) foams as carriers that can promote biofilm growth and organic removal efficiency for biological wastewater treatment in attached growth bioreactors. Open-cell PVDF foams were fabricated by a manufacturing approach that integrated compression molding and particulate leaching. PVDF carriers were structured with two governing factors of leaching agent types (e.g., sodium chloride [NaCl] and sodium acetate [NaOAc]) and contents (e.g., 80 and 90 wt%). Open-cell PVDF foams possessed high porosity and high protected surface area (i.e., more than ×10 to ×20 of the areas of commercialized carriers), which promoted biofilm growth in these carriers. As a successful advantage, PVDF carriers used in the moving bed biofilm reactors (MBBR) were entirely covered by biofilm in both interior and exterior parts without clogging. This provides strong evidence of the bacterial compatibility of the fabricated open-cell PVDF foam carriers. Moreover, the specific morphology of the PVDF carriers in this article provided superior biofilm protection from the detachment in MBBR. Experimental results revealed that PVDF open-cell foams fabricated by 80 wt% of NaCl demonstrated higher mechanical strength with an organic removal efficiency of 77% ± 7% in the corresponding bioreactor containing them.     

Surface Energy and Thermal Stability Studies of Poly(dimethyl siloxane)–Poly(alkyl(meth)acrylate) Copolymers

The correlation between the surface energy and thermal stability of polymers plays an important role in engineering of plastic materials. In this work, microstructural characteristics of copolymers of poly(dimethyl siloxane) with benzyl methacrylate, ethyl methacrylate, and methyl acrylate are correlated with their surface energy and thermal stability. The poly(dimethyl siloxane) segments in the copolymer chains affected the hydrophobic behavior. The surface energy of the synthesized copolymers decreased by increasing segments of alkyl methacrylates. The thermal stability of copolymers suggesting that heat resistance of poly(dimethyl siloxane) copolymers used in this correlation can be improved by adjusting the units of alkyl methacrylates in copolymers.     

Synthesis of polybutadiene nanoparticles by emulsion polymerization: The effect of electrolyte and initiator type on particle size and reaction kinetics

Emulsion polymerization of the butadiene (Bu) was performed in the presence of disproportionate potassium rosinate (DPR) as anionic emulsifier, potassium hydroxide (KOH), and potassium carbonate (K₂CO₃) as electrolytes, and three different initiators including potassium persulfate (KPS), 2,2^′-azobisisobutyronitrile (AIBN) or 4,4′-azobis(4-cyanovaleric acid) (ACVA, also known as VAZO) at 70 °C. Latexes were prepared with a solid content of about 30 wt%. The particle size and its distribution were measured by dynamic light scattering (DLS) analysis, while the polymerization conversion was determined gravimetrically at different time intervals. Results on the emulsion polymerization of Bu in the presence of KOH and K₂CO₃ co-electrolytes showed that adding KOH to the reaction media decreases the polymerization rate. Positive effect of co-electrolytes on the control over polybutadiene latex (PBL) particles size and its distribution was also confirmed, where K₂CO₃ played roles as electrolyte and pH buffer and KOH served double roles as electrolyte and alkaline supplier of the reaction media. Complete solubility of the AIBN in Bu resulted in higher rate of polymerization in the presence of AIBN in comparison to other initiators, i.e., VAZO or KPS. The results showed that initiator type plays a significant role on the formation of PBL nanoparticles and kinetics of the polymerization. The kinetic studies revealed that emulsion polymerization of Bu follows case 1 (i.e., \(\bar{n}\) ?0.5, where \(\bar{n}\) indicates average number of the propagating chains per particle) of the Smith-Ewart kinetics.     

Clinical and hemodynamic criteria for use of the intra-aortic balloon pump in patients requiring cardiac surgery

In order to establish criteria for elective use of the intra-aortic balloon pump (IABP) in patients having cardiac surgery, we conducted a retrospective study of 43 patients who required counterpulsation, because of inability to be weaned from cardiopulmonary bypass, between May, 1972, and June, 1974. Patients in cardiogenic shock preoperatively were excluded. The 43 patients included 23 (Group A) who had severe preoperative left ventricular dysfunction with a mean cardiac index less than 1.8 L. per minute per square meter, ejection fraction less than 30 per cent, and end-diastolic pressure greater than 22 mm. Hg; 20 patients (Group B) had a combination of moderate cardiac dysfunction (cardiac index less than 2.2, ejection fraction less than 40, end-diastolic pressure less than 18) in the presence of acute infarction or severe aortic stenosis (gradient greater than 80 mm. Hg) with or without coronary disease. An inverse relationship was noted between survival and delay from completion of operation to the use of 1ABP. Thirty-two of 43 patients were weaned off bypass and were balloon assisted for 12 to 96 hours postoperatively; 25 patients were discharged (58 per cent). In Subgroup A, 14 of 23 (60 per cent) and, in Subgroup B, 9 of 20 (45 per cent) were long-term survivors. Based on these findings, 45 patients were operated upon between June, 1974, and December, 1975, with elective use of 1ABP and were assessed by serial hemodynamic studies. Sixteen had severe preoperative left ventricular dysfunction similar to Subgroup A and 29 had moderate dysfunction in combination with pathology similar to Subgroup B. Fifteen of these patients were hemodynamically unstable at time of arrival in the operating room; 1ABP was inserted under local anesthesia. Thirty-nine patients (87 per cent) were weaned off bypass and were hospital survivors. In Subgroup A, 13 of 16 (81 per cent) and, in Group B, 21 of 29 (72 per cent) were long-term survivors. Criteria for elective use of 1ABP in cardiac surgery should include severe preoperative left ventricular dysfunction or a combination of moderate dysfunction with coronary or valvular pathology. Elective 1ABP improves the survival with trivial iatrogenic morbidity.     

LENGTH OF WORK-WEEK IN THE USA IN THE FUTURE

There is a growing concern in die labor sector to reduce stresses in the work place and the associated strains and adverse effects on health which result from newer forms of tasks that workers are increasingly called upon to perform. One approach to reducing stresses is to reduce the work-week (fewer hours per week). Social expectation of longer vacations and leisure time, demographic changes, and changes in the nature of die work and attitudes towards work also support this trend. The objective of this position paper is to consider the implication of such a move and the feasibility of this approach. Specifically, we consider the effects of a shorter work-week on productivity and economy and discuss the various patterns of shorter work-week. Finally, we present our position on die pattern of the shorter work-week in the United States in the future.     

Latent-space variational bayes

Variational Bayesian Expectation-Maximization (VBEM), an approximate inference method for probabilistic models based on factorizing over latent variables and model parameters, has been a standard technique for practical Bayesian inference. In this paper, we introduce a more general approximate inference framework for conjugate-exponential family models, which we call Latent-Space Variational Bayes (LSVB). In this approach, we integrate out model parameters in an exact way, leaving only the latent variables. It can be shown that the LSVB approach gives better estimates of the model evidence as well as the distribution over latent variables than the VBEM approach, but in practice, the distribution over latent variables has to be approximated. As a practical implementation, we present a First-order LSVB (FoLSVB) algorithm to approximate this distribution over latent variables. From this approximate distribution, one can estimate the model evidence and the posterior over model parameters. The FoLSVB algorithm is directly comparable to the VBEM algorithm and has the same computational complexity. We discuss how LSVB generalizes the recently proposed collapsed variational methods [20] to general conjugate-exponential families. Examples based on mixtures of Gaussians and mixtures of Bernoullis with synthetic and real-world data sets are used to illustrate some advantages of our method over VBEM.     

Analysis, design, and development model: a case study of an internet-based system for insert and parameter selection

Abstract. The analysis, design, and development model (ADDM) is based on the systems lifecycle process (SLCP) in which analysts begin to understand external client requirements and internal client specifications as they are designing and developing a complex system. In the ADDM, clients and system analysts (SA) continuously interact as the system is being designed, developed, tested and maintained. In the design phase, system development can be altered when it is most cost‐effective. Depending on the type of environment and SA preference and expertise, various interfaces and software and hardware configurations are created during the SLCP. The SLCP ensures effective standardization and continuous quality improvements throughout development. The model follows modern information technology principles to integrate and monitor SLCP phases. A case is presented that describes an application of the ADDM. This case outlines the architecture of an e‐commerce production system (ECPS). The system has a three‐tier structure consisting of the client interface, Java server page (JSP) and database module. The model assists in designing economic production operations in an industrial setting by allowing a client to retrieve current production data needed for operations through the internet.