Exploring the Origin of Maximum Entropy States Relevant to Resonant Modes in Modern Chladni Plates

The resonant modes generated from the modern Chladni experiment are systematically confirmed to intimately correspond to the maximum entropy states obtained from the inhomogeneous Helmholtz equation for the square and equilateral triangle plates. To investigate the origin of maximum entropy states, the inhomogeneous Helmholtz equation is modified to consider the point interaction coming from the driving oscillator. The coupling strength associated with the point interaction is characterized by a dimensionless factor α. The δ potential of the point interaction is numerically modelled by a truncated basis with an upper index N. The asymptotic behavior for the upper index N is thoroughly explored to verify that the coupling strength of α = 1.0 can make the theoretical resonant modes agree excellently with the maximum entropy states as N→∞. It is further authenticated that nearly the same resonant modes can be obtained by using a larger coupling strength α when a smaller upper index N is exploited in the calculation.     

Broadband Light-Emitting Diodes with One-Dimensional Photonic Crystal Layer

In this article, a broadband gallium-nitride-based light-emitting diode with a one-dimensional photonic crystal layer is investigated. The broadband light-emitting diode using the proposed backside reflector has high reflectance (>95%) over a 270-nm bandwidth in visible light at an arbitrary incidence angle. A broadband light-emitting diode of high output power due to the high reflectivity is achieved. Also reported are the results for light-emitting diodes by the transistor outline can (TO-can) package. The proposed light-emitting diodes possess broadband high reflected spectra, high output power for light extraction, and a good view angle.     

Combretastatin A-4 derivatives: synthesis and evaluation of 2,4,5-triaryl-1H-imidazoles as potential agents against H1299 (non-small cell lung cancer cell)

A number of 2,4,5-triaryl-1H-imidazole derivatives were synthesized and evaluated for their antiproliferative activities against the growth of five cell lines including three non-small cell lung cancers (H460, H1299, and A549), one breast cancer (MCF-7), and one normal diploid embryonic lung cell line (MRC-5). Preliminary results indicated that both 2-(5-bromofuran-2-yl)-4,5-bis{4-[3-(dimethylamino) propoxy] phenyl}-1H-imidazole (10f) and 4,5-bis{4-[3-(dimethylamino)propoxy]phenyl}-2-(5-nitrofuran-2-yl)-1H -imidazole (10g) were selectively active against the growth of H1229 with an IC₅₀ of less than 0.1???M, thus were more active than topotecan (IC₅₀ >?10.0??? M). However, both 10f and 10g exhibited only marginal cytotoxicity against H460, A549, MCF-7, and MRC-5 requiring an IC ₅₀ of at least 4.16???M. Our results also indicated that 10f induced H1299 cell cycle arrest at G0/G1 through the inactivation of p38 MAPK, JNK, ERK, as well as the expression of SIRT1 and survivin. These results suggested that 10f might have therapeutic potential against H1299 (non-small cell lung cancer cell).     

Sodium hydroxide as pretreatment and fluorosurfactant-capped gold nanoparticles as sensor for the highly selective detection of cysteine

A sensor for detecting cysteine (Cys) in a solution of fluorosurfactant (FSN)-capped gold nanoparticles (AuNPs) has been developed. Under acidic conditions, FSN-capped AuNPs are aggregated in the presence of homocysteine (HCys) and Cys but not in the presence of cysteinylglycine, glutathione, and gamma-glutamycysteine. When adding NaOH to a solution of HCys, the five-membered ring transition state is formed through intramolecular hydrogen abstraction. By contrast, it is difficult for Cys to form a four-membered ring transition state after Cys has been pretreated with NaOH. As a result, the HCys-induced aggregation of the FSN-capped AuNPs is suppressed because the five-membered ring transition state exhibits relatively larger steric hindrance and has stronger interaction with the FSN molecules. Thus, we can discriminate between Cys and HCys on the basis of different aggregation kinetics. Under the optimum condition, the selectivity of the probe for Cys in aqueous solutions is remarkably high over the other aminthiols. Note that HCys and Cys have very similar structure and pK(a) value. We have validated the applicability of our method through the analyses of Cys in urine samples. It is believed that this approach has great potential for the detection of Cys in biological samples.     

Micellar electrokinetic biofluid analysis of biogenic amines using on-line sample concentration and UV laser-induced native fluorescence detection

A simple and sensitive sweeping micellar electrokinetic chromatography method coupled with UV laser-induced native fluorescence detection has been developed for quantitative analysis of biogenic amines in biofluids. The background electrolyte comprised 30 mmol L⁻¹ phosphoric acid and 20 mmol L⁻¹ sodium dodecyl sulfate. The concentration limits of detection of analytes using sweeping-micellar electrokinetic chromatography (sweeping-MEKC) were in the range 7–100 nmol L⁻¹, which were 250–3600-fold improvement for dopamine, DOPA and epinephrine compared with conventional capillary zone electrophoresis. An improvement of approximately 20-fold was observed for all analytes compared with typical micellar electrokinetic chromatography conditions. Baseline separation was achieved for the all analytes within 12 min and migration-time and peak-area repeatability were better than RSD 0.35% and 5.68%, respectively. The developed method was applied to measure the biogenic amines in biofluids extracted from wheat phloem sap, human plasma and human urine.     

Enantioselective organocatalytic formal [3 + 3]-cycloaddition of alpha,beta-unsaturated aldehydes and application to the asymmetric synthesis of (-)-isopulegol hydrate and (-)-cubebaol

[reaction: see text] The first highly enantioselective organocatalyzed carbo [3 + 3] cascade cycloaddition of alpha,beta-unsaturated aldehydes is reported. Using this methodology, crotonaldehyde is converted to 6-hydroxy-4-methylcyclohex-1-enecarbaldehyde, which is used in the synthesis of (-)-isopulegol hydrate, (-)-cubebaol, and p-tolualdehyde as well as (-)-6-hydroxy-4-methyl-1-cyclohexene-1-methanol acetate, an intermediate in the total synthesis of lycopodium alkaloid magellanine. Other alpha,beta-unsaturated aldehydes give rise to chiral cyclohexadienes via formal [4 + 2] reactions.     

Electrical interaction between two cylinders with an ion-penetrable charged membrane in an oil/water interface

The electrical interaction between two long, parallel cylinders each is covered by an ion-penetrable charged membrane immersed in an oil/water interface is investigated. The effects of contact angle, radius of cylinder, and membrane thickness on the electrical interaction force are examined. The results of numerical simulation reveal that the following conditions lead to a greater electrical interaction force: (i) a larger contact angle, i.e. a larger fraction of a cylinder in the oil phase; (ii) a larger cylinder radius; and (iii) a thinner membrane. For a fixed ionic strength, the electrical interaction force is insensible to the type of electrolytes in the water phase, in general. However, if two cylinders are close enough, then the higher the valence of counterions the greater the electrical interaction force.     

Role of Microporosity of Activated Carbons on Their Adsorption Abilities for Phenols and Dyes

The amounts of adsorption of two commercial dyes, phenol, and 4-chlorophenol from water on activated carbons were measured at 30°C. The carbons were prepared from cane (bagasse) piths and were activated by steam. The activation temperature and time were in the ranges of 750–840°C and 2 h, respectively. It was shown that the isotherm data of all four solutes could be well fitted by the Langmuir equation under the conditions studied. The adsorption capacities of the solutes were correlated with the microporosity properties of the activated carbons including micropore volume and external surface area. Finally, the adsorption characteristics of the present carbons was compared with those prepared from various agricultural wastes.     

Efficient acid catalytic synthesis of pyrazolopyrimidines from 1H-pyrazol-5-yl-N,N-dimethylformamidines with cyanamide

The efficient acid catalytic synthesis of pyrazolo [3,4-d]pyrimidine was developed by treating 1H-pyrazol-5-yl-N,N-dimethylformamidine with various aminating agents including N,O-bis(trimethylsilyl)hydroxylamine (NHSiMe₃(OSiMe₃)), cyanamide (NH₂CN), hydroxylamine (NH₂OH), methoxyamine (NH₂OMe), hydrazine (NH₂NH₂), and urea (NH₂C(O)NH₂) in acidic solution at reflux. Based on the experimental result, cyanamide (NH₂CN) and methanesulfonic acid were indicated the best aminating agent and acid mediated solvent. On the other hands, the reactivity tendency was involved the activity of original leaving species grafting on the aminating agents, such as –OH, –OMe, –OSiMe₃, –NH₂, –OSiMe₃, –C(O)NH₂, and –CN, in acid catalytic heterocyclic reaction.     

Electrophoretic mobility of a particle covered with an ion-penetrable membrane

The electrophoretic behavior of a planar particle covered by an ion-penetrable membrane, which simulates a biological entity, is investigated. We show that, in general, a point charge model will overestimate the electrophoretic mobility of a particle and the deviation increases with the increase in the concentration of fixed charge and with the decrease in the thickness of membrane layer. As in the case of a point charge model, the present model also predicts a local maximum in the absolute mobility as the thickness of membrane layer varies. If the sizes of counterions of various valences are the same, then the lower the valence of counterions, the larger the mobility, and the larger the counterions, the greater the mobility. The latter is consistent with the experimental observations in the literature. For the level of the concentration of fixed charge examined, the effect of coions on the mobility is negligible.