Synthesis,Characterization and Catalytic Activities of Palladium(II) Nitroaryl Complexes

Two palladium(II) nitroaryl complexes trans-[bromo(p-nitrophenyl)bis(triphenylphosphine)palladium(II)] 1 and trans-[bromo(2,4-dinitrophenyl)bis(triphenylphosphine)palladium(II)] 2 have been synthesized. The complexes were characterized by FTIR and NMR (¹H, ¹³C and ³¹P) spectroscopy and elemental analysis. The molecular structure of complex 2, as confirmed by X-ray crystallography, reveals that the Pd atom and its neighboring groups (two PPh₃, Br and phenylene group) lie in a slightly distorted square plane. In the UV–Vis spectra of the complexes 1 and 2, the palladium to aryl charge transfer bands were observed. The emission peaks from the singlet excited states (S₁ → S₀) were observed in the photoluminescence spectra of the complexes. The thermal stability of the complexes has been studied by thermal gravimetric analysis (TGA). TGA data showed that both complexes are thermally stable up to 200 °C, and complex 1 is more stable than 2. The catalytic efficiency of the new palladium(II) complexes was studied as demonstrated using the Sonogashira coupling reactions with good yields. The experimental results suggest that the Sonogashira coupling reactions can be performed at moderate temperature (50 °C) using these new palladium(II) complexes as catalysts.     

Tooling device design for vibration-assisted high speed shaping of PMMA

PMMA optical components that are used as one of the most important parts of high precision equipments and machines are increasingly replacing the glass due to the various advantages of PMMA. Especially in Light Guide Panels, the PMMA sheet that is used in Liquid Crystal Displays plays an important role in scattering the incident light and requires very fine machining as the sheet is directly related to the optical characteristics of the panels. The High Speed End milling and High Speed Shaping processes that are widely adopted and applied to the precise machining of Light Incident Plane still have quality problems, such as cracks, breakages, poor waviness, and straightness. This paper presents the tooling device design for machining a Light Incident Plane through vibration-assisted High Speed Shaping for increasing the optical quality by minimizing the above-mentioned problems. The cutting tool and the tool post presented in this paper are designed by the authors to increase the magnitude of the cutting stroke by adopting the resonant frequency without weakening the stiffness and to reduce vibrations during even high speed feeding. The dynamic characteristics of the cutting tool and the tool post are evaluated through simulation and experiment as well. The results reveal very appropriate dynamic characteristics for vibration-assisted High Speed Shaping.     

Testing and evaluating virus detectors for handheld devices

The widespread use of personal digital assistants and smartphones gives securing these devices a high priority. Yet little attention has been placed on protecting handheld devices against viruses. Currently available antivirus software for handhelds is few in number. At this stage, the opportunity exists for the evaluation and improvement of current solutions. By pinpointing weaknesses in the current antivirus software, improvements can be made to properly protect these devices from a future tidal wave of viruses. This research evaluates four currently available antivirus solutions for handheld devices. A formal model of virus transformation that provides transformation traceability is presented. Two sets of ten tests each were administered; nine tests from each set involved the modification of source code of two known viruses for handheld devices. The testing techniques used are well established in PC testing; thus the focus of this research is solely on handheld devices. Statistical analysis of the test results show high false negative production rates for the antivirus software and an overall false negative production rate of 47.5% with a 95% confidence interval between 36.6% and 58.4%. This high rate shows that current solutions poorly identify modified versions of a virus. The virus is left undetected and capable of spreading, infecting and causing damage.     

Adsorption of proteins on electro-conductive polymer films

Shapable electro-conductive (SEC) polymer films (polyanion-doped polypyrrole films) show several interesting properties for bioelectrochemical applications. The SEC film can be used as an inert, stable and hydrophobic electrode in aqueous solution over a wide potential range. In this study, the physical and the potential-assisted adsorption of various proteins on the SEC film is described. Because of the hydrophobic surface characteristic proteins easily adsorb and retain on the film surface by strong hydrophobic interactions. The amount of the adsorbed protein varies from 2.2 to 4.8 μg cm⁻² depending on the protein when the film is incubated for 22 h in the protein solution. The adsorption is effectively accelerated and enhanced by applying a positive potential in the range from 0.4 V to 1.0 V (vs. Ag/AgCl). The potential-assisted adsorption process is completed by 10–15 min and the amount of the adsorbed protein is nearly doubled as compared to the adsorption without potential. The adsorbed protein is chemically very stable in comparison with the protein in solution. More than 85% of the initial adsorbed proteins retains on the surface after three weeks of incubation in buffer solution. The initial adsorption rate is studied by quartz crystal micro-balance measurements on a thin polymer film coated quartz crystal. In addition, the SEC film surface is etched with air plasma which leads to a four-fold increase of the adsorption of proteins.     

A discrete-sectional model for particle growth in aerosol reactor: Application to titania particles

A one-dimensional discrete-sectional model has been developed to simulate particle growth in aerosol reactors. Two sets of differential equations for volume and surface area, respectively, were solved simultaneously to determine the size distributions of agglomerates and primary particles. The surface area equations were derived in such a way that the coagulation integrals calculated for the volume equations could be used for the surface area equations as well, which is new in this model. The model was applied to a production of TiO₂ particles by oxidation of titanium tetrachloride. Model predictions were compared with experimental data and those of a two-dimensional sectional model. Good agreement was shown in calculated particle size distributions between the present model and the two-dimensional model, which is more rigorous but demands a large amount of computer time and memory. Compared to experimental data, the primary particle size calculated by the model was more sensitive to the variation of reactor temperature.     

Model representation of secondary organic aerosol in CMAQv4.7

Numerous scientific upgrades to the representation of secondary organic aerosol (SOA) are incorporated into the Community Multiscale Air Quality (CMAQ) modeling system. Additions include several recently identified SOA precursors: benzene, isoprene, and sesquiterpenes; and pathways: in-cloud oxidation of glyoxal and methylglyoxal, particle-phase oligomerization, and acid enhancement of isoprene SOA. NO(x)-dependent aromatic SOA yields are also added along with new empirical measurements of the enthalpies of vaporization and organic mass-to-carbon ratios. For the first time, these SOA precursors, pathways and empirical parameters are included simultaneously in an air quality model for an annual simulation spanning the continental U.S. Comparisons of CMAQ-modeled secondary organic carbon (OC(sec)) with semiempirical estimates screened from 165 routine monitoring sites across the U.S. indicate the new SOA module substantially improves model performance. The most notable improvement occurs in the central and southeastern U.S. where the regionally averaged temporal correlations (r) between modeled and semiempirical OC(sec) increase from 0.5 to 0.8 and 0.3 to 0.8, respectively, when the new SOA module is employed. Wintertime OC(sec) results improve in all regions of the continental U.S. and the seasonal and regional patterns of biogenic SOA are better represented.     

2D Metal Oxyhalide‐Derived Catalysts for Efficient CO2 Electroreduction

Electrochemical reduction of CO₂ is a compelling route to store renewable electricity in the form of carbon‐based fuels. Efficient electrochemical reduction of CO₂ requires catalysts that combine high activity, high selectivity, and low overpotential. Extensive surface reconstruction of metal catalysts under high productivity operating conditions (high current densities, reducing potentials, and variable pH) renders the realization of tailored catalysts that maximize the exposure of the most favorable facets, the number of active sites, and the oxidation state all the more challenging. Earth‐abundant transition metals such as tin, bismuth, and lead have been proven stable and product‐specific, but exhibit limited partial current densities. Here, a strategy that employs bismuth oxyhalides as a template from which 2D bismuth‐based catalysts are derived is reported. The BiOBr‐templated catalyst exhibits a preferential exposure of highly active Bi () facets. Thereby, the CO₂ reduction reaction selectivity is increased to over 90% Faradaic efficiency and simultaneously stable current densities of up to 200 mA cm^?2 are achieved—more than a twofold increase in the production of the energy‐storage liquid formic acid compared to previous best Bi catalysts.     

Nanoparticle–Plant Interactions: Two‐Way Traffic

In this Review, an effort is made to discuss the most recent progress and future trend in the two‐way traffic of the interactions between plants and nanoparticles (NPs). One way is the use of plants to synthesize NPs in an environmentally benign manner with a focus on the mechanism and optimization of the synthesis. Another way is the effects of synthetic NPs on plant fate with a focus on the transport mechanisms of NPs within plants as well as NP‐mediated seed germination and plant development. When NPs are in soil, they can be adsorbed at the root surface, followed by their uptake and inter/intracellular movement in the plant tissues. NPs may also be taken up by foliage under aerial deposition, largely through stomata, trichomes, and cuticles, but the exact mode of NP entry into plants is not well documented. The NP–plant interactions may lead to inhibitory or stimulatory effects on seed germination and plant development, depending on NP compositions, concentrations, and plant species. In numerous cases, radiation‐absorbing efficiency, CO₂ assimilation capacity, and delay of chloroplast aging have been reported in the plant response to NP treatments, although the mechanisms involved in these processes remain to be studied.