Organic‐Free Synthesis of Silicoaluminophosphate Molecular Sieves

Silicoaluminophosphate (SAPO) molecular sieves are an important class of microporous materials and are useful for industrial catalysis and separations. They have been synthesized exclusively by the use of expensive and environmentally unfriendly organic structure‐directing agents. Now the synthesis of SAPO molecular sieves is reported with MER, EDI, GIS, and ANA topologies under wholly inorganic conditions. Multinuclear MAS NMR analyses demonstrate the presence of Si, Al, and P atoms in their frameworks. These SAPO materials all have unusually high framework charge densities (0.25–0.46), owing to the small size of alkali metal cations used as an inorganic structure‐directing agent. A continuous Si increase in the synthesis gel for MER‐type SAPO molecular sieves led to the formation of framework Si(0Al) units, decreasing the number of extra‐framework cations per unit cell and thus making the resulting solid useful for CO₂ adsorption.     

Development of a scalable synthetic route towards a 2,2,6-trisubstituted chiral morpholine via stereoselective hydroalkoxylation

A scalable synthetic route towards a chiral 2,2,6-trisubstituted chiral morpholine, which is a known opioid antagonist, was developed. The synthetic route involves incorporating an aryl group via Suzuki-Miyaura coupling and stereoselective hydroalkoxylation catalyzed by trifluoromethanesulfonic acid. Late stage incorporation of both the aryl and N-alkyl groups make this route suitable for further SAR studies on this molecule.     

Specimen and Grain Size Effects of Al1100 on Strain and Strain Rate Hardening at Various Strain Rates for Al1100

This paper is concerned with comparison of the tensile properties of Al1100 thin film in a micro-scale to that of Al1100 sheet in a macro-scale. The material properties of Al1100 film and sheet with a thickness of 96 μm and 1 mm respectively have been investigated at strain rates ranging from 0.001 to 100 s^?1. The experiments were conducted with Static Micro-Material Testing Machine (SMMTM) and High Speed Micro-Material Testing Machine (HSMMTM) for micro-specimens and with Instron 5583 and high speed material testing machine (HSMTM) for macro-specimens. A reliable jig system for SMMTM and HSMMTM has been newly developed for easy installation of a specimen and accurate alignment between a specimen and the jig system to enhance the reproducibility of tests. The digital image correlation (DIC) method is employed to measure the axial strain of the specimens. In order to obtain a fine speckle pattern for the DIC method, a novel technique is employed to print the speckle pattern with fine particles by blowing sprayed particles before printing. The grain sizes of two Al1100 specimens have been compared and the number of grains in the gauge cross-section has been calculated to obtain the grain number which is related to the specimen size effect. Electron Back Scattered Diffraction (EBSD) images were obtained for both micro-specimens and macro-specimens and analyzed to measure the grain size. The Al1100 film with a smaller average grain size shows larger strain hardening than the Al1100 sheet with a larger average grain size.     

In situ grown epitaxial YBa2Cu3O7 − x thin films by pulsed laser deposition under reduced oxygen pressure during cool-down time

We report novel pulsed laser deposition conditions that were used to obtain superconducting epitaxial YBCO thin films, grown in situ using an oxygen pressure lower than the usual one during the cool-down time. We studied the influence of the PLD conditions as substrate temperature, oxygen pressure, laser fluence, and number of laser pulses on the crystallographic and morphological features, and on the superconducting properties of the films. Good superconducting properties were obtained without a high temperature post-deposition annealing process. A maximum critical temperature of 88.6 K was obtained.     

Second-order conditional moment closure modeling of a turbulent CH4/H2/N2 jet diffusion flame

The second-order CMC model for a detailed chemical mechanism is used to model a turbulent CH₄/H₂/N₂ jet diffusion flame. Second-order corrections are made to the three rate limiting steps of methane–air combustion, while first-order closure is employed for all the other steps. Elementary reaction steps have a wide range of timescales with only a few of them slow enough to interact with turbulent mixing. Those steps with relatively large timescales require higher-order correction to represent the effect of fluctuating scalar dissipation rates. Results show improved prediction of conditional mean temperature and mass fractions of OH and NO. Major species are not much influenced by second-order corrections except near the nozzle exit. A parametric study is performed to evaluate the effects of the variance parameter in log-normal scalar dissipation PDF and the constants for the dissipation term in conditional variance and covariance equations.     

Sensing of picric acid with a glassy carbon electrode modified with CuS nanoparticles deposited on nitrogen-doped reduced graphene oxide

We describe the preparation of a nanohybrid consisting of nitrogen doped reduced graphene oxide and CuS nanoparticles (N-rGO/CuS) by in-situ microwave irradiation at weight ratios of 25/75, 50/50, and 75/25. The resulting nanohybrids were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, FTIR, spectroscopy, scanning electron and transmission electron microscopy, electrochemically by cyclic voltammetry and electrochemical impedance analysis. It is shown that the CuS nanoparticles are evenly decorated onto the N-rGO surface. The nanohybrids was placed on glassy carbon electrode (GCE) where they showed electro-reductive activity towards picric acid, typically at working voltages between ?0.2 and ?0.8 V (vs. SCE). Effects of pH value and scan rate were evaluated, and it is shown that two electrons are involved in electro-reduction. The detection limits of the GCE modified with various N-rGO/CuS hybrids (with 25/75, 50/50, and 75/25 wt%) are 6.2, 3.2, and 0.069 μM respectively. The method demonstrates its applicability in sensing of picric acid with good reproducibility.

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Graphical abstract Nitrogen doped reduced graphene oxide nanohybrids was synthesized for the detection of picric acid. A straightforward and preconcentration free analysis of picric acid was successfully demonstrated at nanomolar levels using the nanohybrids.

     

Identification of genetically modified DNA found in Roundup Ready soybean using gold nanoparticles

The authors describe an SPR sensor chip coated with gold nanoparticles (AuNPs) that enables highly sensitive determination of genetically modified (GM) crops. Detection is based on localized surface plasmon resonance (LSPR) with its known sensitivity to even minute changes in refractive index. The device consists of a halogen light source, a light detector, and a cuvette cell that contains a sensor chip coated with AuNPs. It is operated in the transmission mode of the optical path to enhance the plasmonic signal. The sample solution containing target DNA (e.g. from the GM crop) is introduced into the cuvette with the sensor chip whose surface was functionalized with a capture DNA. Following a 30-min hybridization, the changes of the signal are recorded at 540 nm. The chip responds to target DNA in the 1 to 100 nM concentration range and has a 1 nM detection limit. Features of this sensor chip include a short reaction time, ease of handling, and portability, and this enables on-site detection and in-situ testing.

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Graphical abstract A localized surface plasmon resonance (LSPR)-based nanoplasmonic spectroscopic device enabling a highly sensitive biosensor is developed for the detection of genetically modified (GM) DNA founded in Roundup Ready (RR) soybean.

     

Analysis of shifting performance of power shuttle transmission

This study was conducted to investigate the effects on the shifting performance of the design parameters of a power shuttle tractor using a computer simulation technique. The EASY 5 models of the hydraulic control system and power shuttle transmission were developed, and combined with a tractor model to complete a simulation model for a power shuttle tractor. The models for the hydraulic control system and power shuttle transmission were verified using an experimental power train constructed for the validation purpose.The design parameters included the terminal pressure and time for the modulation of the hydraulic control system, and forward speed, weight, shuttle gear ratio and torsional damping of the tractor. The shift performance was evaluated in term of the peak torques of the input shaft of the transmission and tractor axles, and power transmitted per unit area of the clutch and the time required for the power transmission.     

Crosstalk between FLS and chondrocytes is regulated by HIF-2α-mediated cytokines in arthritis

Rheumatoid arthritis (RA) and osteoarthritis (OA), two common types of arthritis, affect the joints mainly by targeting the synovium and cartilage. Increasing evidence indicates that a significant network connects synovitis and cartilage destruction during the progression of arthritis. We recently demonstrated that hypoxia-inducible factor (HIF)-2α causes RA and OA by regulating the expression of catabolic factors in fibroblast-like synoviocytes (FLS) or chondrocytes. To address the reciprocal influences of HIF-2α on FLS and chondrocytes, we applied an in vitro co-culture system using a transwell apparatus. When co-cultured with HIF-2α-overexpressing chondrocytes, FLS exhibited increased expression of matrix metalloproteinases and inflammatory mediators, similar to the effects induced by tumor-necrosis factor (TNF)-α treatment of FLS. Moreover, chondrocytes co-cultured with HIF-2α-overexpressing FLS exhibited upregulation of Mmp3 and Mmp13, which is similar to the effects induced by interleukin (IL)-6 treatment of chondrocytes. We confirmed these differential HIF-2α-induced effects via distinct secretory mediators using Il6-knockout cells and a TNF-α-blocking antibody. The FLS-co-culture-induced gene expression changes in chondrocytes were significantly abrogated by IL-6 deficiency, whereas TNF-α neutralization blocked the alterations in gene expression associated with co-culture of FLS with chondrocytes. Our results further suggested that the observed changes might reflect the HIF-2α-induced upregulation of specific receptors for TNF-α (in FLS) and IL-6 (in chondrocytes). This study broadens our understanding of the possible regulatory mechanisms underlying the crosstalk between the synovium and cartilage in the presence of HIF-2α, and may suggest potential new anti-arthritis therapies.