Multiple metal coordinating behaviour of the tetrapodal ligand 1,1,1,1-tetrakis[(salicylaldimino)methyl]methane

The tetrapodal ligand 1,1,1,1-tetrakis[(salicylaldimino)methyl]methane (H₄tsam) has been introduced for the first time for metal complexation. Two zinc(II) complexes[Zn₂(tsam)] (1) and [Zn₃(Htsam)₂]·2C₇H₈ (2) have been obtained by reacting zinc acetylacetonate with the ligand in the presence of triethylamine, while a cobalt(III) complex [Co(Htsam)]·CH₃CN·H₂O (3) is obtained when Co(ClO₄)₂·6H₂O is reacted in air. All the compounds have been characterized by their elemental analyses and ESI-MS, IR, UV-VIS and ¹H NMR spectra. The X-ray crystal structures of H₄tsam, 2 and 3 have been determined. Compounds 1 and 2 exhibit fluorescence in solution and the lifetimes of their luminescence decay have been measured. Thermal analysis (TGA, DTA) of 2 with regard to loss of encapsulated toluenes and redox behaviour of 3 have been studied.     

Minimum fluidization velocity at elevated temperature in tapered fluidized bed

Very little data of minimum fluidization velocity at elevated temperatures of tapered bed are available in the literature. This study was undertaken to provide some data under elevated temperature conditions in tapered bed. Data on minimum fluidization velocity have been obtained experimentally for temperature up to 800 °C in case of 0.5 mm diameter of sand particles and up to 500 °C in case of 1 mm diameter of glass beads in tapered bed. An equation valid for the bed has been developed in terms of Archimedes number and Reynolds number. The experimental values for minimum fluidization velocity at elevated temperatures have been compared with the calculated values obtained from present equation and from earlier equations developed by other authors for ambient conditions in conventional (cylindrical) bed and tapered bed. Fairly good agreement was found to exist between the calculated (from present equation) and the experimental values.     

Degradation of light emitting diodes:a proposed methodology

Due to their long lifetime and high efficacy,light emitting diodes have the potential to revolutionize the illumination industry.However,self heat and high environmental temperature which will lead to increased junction temperature and degradation due to electrical overstress can shorten the life of the light emitting diode.In this research,a methodology to investigate the degradation of the LED emitter has been proposed.The epoxy lens of the emitter can be modelled using simplified Eyring methods whereas an equation has been proposed for describing the degradation of the LED emitters.     

Model reductions with special CSP data

The model reduction methodology of computational singular perturbation (CSP) is enhanced for chemical kinetics problems. The leading order converged CSP-refined fast basis vectors are obtained analytically by exploiting the special format of the given reaction-specific chemical kinetics data. The leading order net reaction rates of the fast reactions (after they are exhausted) are also obtained analytically. Taking advantage of these leading order analytical results, a new model reduction strategy is advocated. The implementation of this new strategy is very straightforward, and extraction of general insights on the reaction system is also easier.     

Enhanced bioaccessibility of β‐carotene from yellow‐orange vegetables and green leafy vegetables by domestic heat processing

Effect of heat treatment involved in domestic cooking on the bioaccessibility of β‐carotene from yellow‐orange as well as green leafy vegetables was evaluated. Heat treatment of these vegetables by pressure‐cooking, stir‐frying and open‐pan boiling had a beneficial influence on the bioaccessibility of β‐carotene. The extent of increase in the per cent bioaccessibility of β‐carotene as a result of pressure‐cooking was 21–84%. Stir‐frying in presence of a small quantity of oil brought about an enormous increase in the bioaccessibility of β‐carotene from these vegetables, the extent of increase being 67–191%. Open‐pan boiling of vegetables increased the bioaccessibility of β‐carotene in the range 23–36%. Thus, among the three domestic heat processing methods, stir‐frying results in maximum bioaccessibility of this provitamin. The use of suitably heat‐processed vegetable sources of β‐carotene could form a dietary strategy to derive this micronutrient maximally by the population dependent on plant foods.     

Iterative phase retrieval strategy of transient events

Important nuances of a process or processes in action can be obtained from the phase retrieval of diffraction patterns for analysis of transient events. A significant limitation associated with the iterative approach is that predictive input functions are needed and can result in situations of nonconvergence. In dealing with a transient event recorded as a series of Fourier magnitude patterns, such a hit-and-miss characteristic, on the surface, appears computationally daunting. We report and demonstrate a strategy here that effectively minimizes this by using a prior retrieved frame as the predictive function for the current retrieval process.     

Performance analysis of serial cooperative communications with decode-and-forward relaying and blind-EGC reception under nakagami fading channels

We analyze a serial cooperative transmission system with DF relaying over Nakagami fading channels. We consider a system in which the simple receivers will not estimate the amplitude of the received signals. Hence, signals are combined with equal gain before decoding. Moreover, the relays use a simple protocol when relaying the messages ? they re-transmit the message if they can decode the received message correctly; otherwise, they do not transmit anything and remain idle. We will derive an exact expression for the asymptotic symbol error rate of the system and evaluate the diversity properties.     

Selective excitation of individual plasmonic hotspots at the tips of single gold nanostars

Plasmonic hotspots in single gold nanostars are located at the tips and can be excited selectively by laser light as evidenced by photoelectron emission microscopy. Selectivity is achieved through wavelength and polarization of the excitation light. Comparing photoelectron emission intensity and dark-field scattering spectra of the same individual nanostars reveals differences in terms of observable plasmon resonance wavelengths and field enhancements. Differences are explained with the underlying near- and far-field processes of the two techniques.     

A review of passive thermal management of LED module

Recently, the high-brightness LEDs have begun to be designed for illumination application. The increased electrical currents used to drive LEDs lead to thermal issues. Thermal management for LED module is a key design parameter as high operation temperature directly affects their maximum light output, quality, reliability and life time. In this review, only passive thermal solutions used on LED module will be studied. Moreover, new thermal interface materials and passive thermal solutions applied on electronic equipments are discussed which have high potential to enhance the thermal performance of LED Module.     

A review of passive thermal management of LED module

Recently,the high-brightness LEDs have begun to be designed for illumination application.The increased electrical currents used to drive LEDs lead to thermal issues.Thermal management for LED module is a key design parameter as high operation temperature directly affects their maximum light output,quality,reliability and life time.In this review,only passive thermal solutions used on LED module will be studied.Moreover,new thermal interface materials and passive thermal solutions applied on electronic equipments are discussed which have high potential to enhance the thermal performance of LED Module.