Influence of ZnO nanorod morphology on optical confinement--finite-difference time-domain numerical simulation study

We studied the influence of nanorod (NR) morphology on the optical confinement. In order to understand the optical field confinement by the ZnO NR, we obtained the spatial intensity distribution inside/outside the NR by solving Maxwell equations using the finite-difference time-domain numerical simulation. The hexagonal cylinder-shaped NR exhibits a strong confinement and the circular cylinder-shaped NR shows also similar confinement effect. Meanwhile, the rectangular cylinder-shaped NR, the tapered NR, and the NR with sharp cone show a weak confinement of optical field as compared to that of the hexagonal cylinder-shaped NR. Next, as the rod length and/or the rod diameter increase, the high intensity region increases. This suggests that longer nanorod will exhibit more efficient lasing action.     

A Novel Algebraic Framework for Analyzing Finite Population DS/SS Slotted ALOHA Wireless Network Systems with Delay Capture

A new analytic framework based on a linear algebra approach is proposed for examining the performance of a direct sequence spread spectrum (DS/SS) slotted ALOHA wireless communication network systems with delay capture. The discrete-time Markov chain model has been introduced to account for the effect of randomized time of arrival (TOA) at the central receiver and determine the evolution of the finite population network performance in a single-hop environment. The proposed linear algebra approach applied to the given Markov problem requires only computing the eigenvector II of the state transition matrix and then normalizing it to have the sum of its entries equal to 1. MATLAB computation results show that systems employing discrete TOA randomization and delay capture significantly improves throughput-delay performance and the employed analysis approach is quite easily and staightforwardly applicable to the current analysis problem.     

Frequency detuning effects in a loop-back WDM-PON employing gain-saturated RSOAs

We report that, in a loop-back wavelength-division-multiplexed passive optical network link with gain-saturated reflective semiconductor optical amplifiers, the upstream performance is strongly affected not only by the gain saturation but also by the selective spectral filtering caused by the frequency difference between the optical downstream signal and the cascaded filter's passband. We experimentally investigate these effects and propose to use an additional negatively detuned optical filter at an optical network terminal to improve the upstream transmission performance.     

The effect of swirling flow in the mixing chamber of atomizer and the length/diameter ratio of atomizer exit on the distribution of coal particles in CWM spray

This research is aimed to investigate how the swirling phenomena in an atomizer and the ratio of length/diameter of the atomizer exit affect the size distribution of coal particle in spray. CWM slurries are injected by a swirling twin-fluid atomizer. Five different caps and a swirler are designed and fabricated into an existing twin fluid atomizer. The droplets are sampled by test tubes and microscope slides coated with magnesium oxide. The data analysis are done by photo technique and Malvern particle sizer. The experimental results reveal that there are many droplets which do not have any coal particles. Those are simply water droplets. The population ratio of droplets without coal particles to total sampled CWM droplets is increased as the sampling position moves outward in the radial direction from the axis of spray. The length/ diameter ratio of an atomizer exit and the swirling phenomena in an atomizer affect a lot the spray pattern and the spray angle but they make no noticeable effects on the size distribution of coal particles in droplets and spray.     

Phenolics and eudesmanolide from aged common sage exudate with sugar

Nineteen compounds including one new flavanone were isolated from the juice of aged common sage exudate with sugar (ACSE). The isolated compounds were identified by NMR and MS analyses as levodopa methyl ester (1), 3,4-dihydroxybenzoic acid (2), (S)-8-hydroxy-4-hydroxy-phenylpropanoic acid (3), 4-hydroxybenzoic acid ethyl ester (4), cis-caffeic acid (5), trans-caffeic acid (6), esculetin (7), (S)-8-hydroxy-3,4-dihydroxy-phenylpropanoic acid ethyl ester (8), cis-rosmarinic acid (9), trans-rosmarinic acid (10), trans-rosmarinic acid methyl ester (11), 6-methoxy-7,8,3′,5′-tetrahydroxyflavanone (12), nepetin (13), trans-caffeic acid ethyl ester (14), luteolin (15), cis-caffeic acid ethyl ester (16), 6-methoxynaringenin (17), 1α-acetoxy-2-oxo-eudesman-3,7(11)-dien-8β,12-olide (18), and hispidulin (19). Compound 12 was isolated for the first time from nature and seven compounds (1, 3, 4, 7, 8, 14, and 18) were newly identified from common sage. Of them, 15 isolated phenolic compounds (1–3, 5–8, 10–15, 17, and 19) were detected in ACSE juice, while only 10 was detected in the fresh common sage.     

Highly Elastic Graphene‐Based Electronics Toward Electronic Skin

Epidermal electronics are extensively explored as an important platform for future biomedical engineering. Epidermal devices are typically fabricated using high‐cost methods employing complex vacuum microfabrication processes, limiting their widespread potential in wearable electronics. Here, a low‐cost, solution‐based approach using electroconductive reduced graphene oxide (RGO) sheets on elastic and porous poly(dimethylsiloxane) (PDMS) thin films for multifunctional, high‐performance, graphene‐based epidermal bioelectrodes and strain sensors is presented. These devices are fabricated employing simple coatings and direct patterning without using any complicated microfabrication processes. The graphene bioelectrodes show a superior stretchability (up to 150% strain), with mechanical durability up to 5000 cycles of stretching and releasing, and low sheet resistance (1.5 kΩ per square), and the graphene strain sensors exhibit a high sensitivity (a gauge factor of 7 to 173) with a wide sensing range (up to 40% strain). Fully functional applications of dry bioelectrodes in monitoring human electrophysiological signals (i.e., electrocardiogram, electroencephalography, and electromyogram) and highly sensitive strain sensors for precise detection of large‐scale human motions are demonstrated. It is believed that our unique processing capability and multifunctional device platform based on RGO/porous PDMS will pave the way for low‐cost processing and integration of 2D materials for future wearable electronic skin.     

Generation of New Complestatin Analogues by Heterologous Expression of the Complestatin Biosynthetic Gene Cluster from Streptomyces chartreusis AN1542

The heterologous expression of the biosynthetic gene cluster (BGC) of natural products enables the production of complex metabolites in a well‐characterized host, and facilitates the generation of novel analogues by the manipulation of the genes. However, the BGCs of glycopeptides such as vancomycin, teicoplanin, and complestatin are usually too large to be directly cloned into a single cosmid. Here, we describe the heterologous expression of the complestatin BGC. The 54.5 kb cluster was fully reconstituted from two overlapping cosmids into one cosmid by λ‐RED recombination‐mediated assembly. Heterologous expression of the assembled gene cluster in Streptomyces lividans TK24 resulted in the production of complestatin. Deletion of cytochrome P450 monooxygenase genes (open reading frames 10 and 11) and heterologous expression of the modified clusters led to the production of two new monocyclic and linear derivatives, complestatins M55 and S56.     

Phenolics,acyl galactopyranosyl glycerol,and lignan amides from <Emphasis Type="Italic">Tetragonia tetragonioides</Emphasis> (Pall.) Kuntze

Eleven antioxidative compounds, including five lignin amides, were isolated from the aerial part of Tetragonia tetragonioides (New Zealand spinach) using 1,1-diphenyl-2-picrylhydrazyl radicalscavenging assay-guided purification. The structures were determined by nuclear magnetic resonance and electrospray ionization-mass spectroscopy. These compounds were identified as methyl linoleate (1), methyl coumarate (2), methyl ferulate (3), 1-O-stearoyl-3-O-β-D-galactopyranosyl-sn-glycerol (4), 1-O-caffeoyl-β-D-glucopyranoside (5), N-trans-caffeoyltyramine (6), cannabisin B (7), cannabisin A (8), Ntrans-feruloyltyramine (9), N-cis-feruloyltyramine (10), and N-trans-sinapoyltyramine (11). Compounds 1, 2, 4, 5, and 8-11 were isolated for the first time from this plant.