Investigations into the reactions of enamines and imines.

Thesis (Ph.D.)-University of Natal, Durban, 1990.The alkylation of 2-methylcyclohexanone imines using methyl acrylate has been investigated with a view to optimising the reaction conditions. The mechanism of this alkylation reaction has been investigated and it has been shown that the alkylation does not proceed via a 2,6-intermediate which subsequently undergoes a rearrangement to the 2,2-product, but rather proceeds directly to the 2,2-product. As it had been shown that the alkylation of 2-substituted cyclohexanone imines in dry methanol occurred at the more substituted position, it was decided, in the light of certain apparently anomolous patent work, to investigate the alkylation of unsubstituted cyclohexanone imines using a variety of electrophilic alkenes. The results show that in certain instances, 2,2-bis-alkylation occurs and in others, mono-alkylation and that it is the strength of the electron-withdrawing group attached to the alkene which determines whether 2,2-bis-alkylation occurs or not. The reasons for this are discussed in the text. The preparation of a number of novel 2,2-bis-eyclohexanones and an octahydroquinoline are described. The reaction of I-phenyl-2-propen-l-one (phenyl vinyl ketone) with the benzylaluine imines of 2-butanone and I-phenyl-2-propanone in methanol gave gave two novel bicyclic diones, whereas the reaction between the benzylamine imine of 3-pentanone with I-phenyl-2-propen-l-one gave only mono-eyclic products only even though there appeared to be no impediment to the formation of the bicyclic compound. The structures were determined using nuclear magnetic resonance and confirmed by X-ray crystallography. The reaction between I-phenyl-2-propen-l-one and N-(l-phenyl-l-ethylidene)benzylamine gave after hydrolysis only the mono-substituted product, 1,5-diphenyl-l ,5-pentandione

An application and generating methods for Mellin transforms

Properties of Mellin transforms are applied to the summation of infinite series. A specific example of this application leads to the establishment of certain properties of a generalization of Lerch's zeta function. Nine powerful methods of generating new tables of Mellin transforms from existing tables of Mellin and other integral transforms are described and illustrated. A table of over 200 examples, which were derived from one of the above mentioned methods, is included

Hardware implementation algorithm and error analysis of high-speed fluorescence lifetime sensing systems using center-of-mass method

A new, simple, high-speed, and hardware-only integrationbased fluorescence-lifetime-sensing algorithm using a center-of-mass method CMM is proposed to implement lifetime calculations, and its signal-to-noise-ratio based on statistics theory is also deduced. Compared to the commonly used iterative least-squares method or the maximum-likelihood-estimation–based, general purpose fluorescence lifetime imaging microscopy FLIM analysis software, the proposed hardware lifetime calculation algorithm with CMM offers direct calculation of fluorescence lifetime based on the collected photon counts and timing information provided by in-pixel circuitry and therefore delivers faster analysis for real-time applications, such as clinical diagnosis. A real-time hardware implementation of this CMM FLIM algorithm suitable for a single-photon avalanche diode array in CMOS imaging technology is now proposed for implementation on field-programmable gate array. The performance of the proposed methods has been tested on Fluorescein, Coumarin 6, and 1,8- anilinonaphthalenesulfonate in water/methanol mixture

A single nucleotide mutation in Nppc is associated with a long bone abnormality in lbab mice

BACKGROUND: The long bone abnormality (lbab) mouse is a new autosomal recessive mutant characterized by overall smaller body size with proportionate dwarfing of all organs and shorter long bones. Previous linkage analysis has located the lbab mutation on chromosome 1 between the markers D1Mit9 and D1Mit488. RESULTS: A genome-based positional approach was used to identify a mutation associated with lbab disease. A total of 122 genes and expressed sequence tags at the lbab region were screened for possible mutation by using genomic DNA from lbabl/lbab, lbab/+, and +/+ B6 mice and high throughput temperature gradient capillary electrophoresis. A sequence difference was identified in one of the amplicons of gene Nppc between lbab/lbab and +/+ mice. One-step reverse transcriptase polymerase chain reaction was performed to validate the difference of Nppc in different types of mice at the mRNA level. The mutation of Nppc was unique in lbab/lbab mice among multiple mouse inbred strains. The mutation of Nppc is co-segregated with lbab disease in 200 progenies produced from heterozygous lbab/+ parents. CONCLUSION: A single nucleotide mutation of Nppc is associated with dwarfism in lbab/lbab mice. Current genome information and technology allow us to efficiently identify single nucleotide mutations from roughly mapped disease loci. The lbab mouse is a useful model for hereditary human achondroplasia

Individually addressable AlInGaN micro-LED arrays with CMOS control and subnanosecond output pulses

We report the fabrication and characterization of an ultraviolet (370 nm) emitting AlInGaN-based micro-light- emitting diode (micro-LED) array integrated with complementary metal-oxide-semiconductor control electronics. This configuration allows an 8 × 8 array of micro-LED pixels, each of 72-mum diameter, to be individually addressed. The micro-LED pixels can be driven in direct current (dc), square wave, or pulsed operation, with linear feedback shift registers (LFSRs) allowing the output of the micro-LED pixels to mimic that of an optical data transmitter. We present the optical output power versus drive current characteristics of an individual pixel, which show a micro-LED output power of up to 570 muW in dc operation. Representative optical pulse trains demonstrating the micro-LEDs driven in square wave and LFSR modes, and controlled optical pulsewidths from 300 ps to 40 ns are also presented

Digital Silicon Photomultipliers with OR/XOR Pulse Combining Techniques

A recently proposed XOR-based digital silicon photomultiplier (dSiPM) is compared against the OR-based counterpart. We show experimental data from a set of single-photon avalanche diode (SPAD) pixel arrays in 130-nm CMOS process with selectable OR tree and XOR tree for direct comparison. We demonstrate how XOR-based dSiPMs solve the limitation caused by monostable circuits and reach higher maximum count rates compared with optimized OR-based dSiPMs. The increased throughput of the SPAD array allows higher sampling rates for the digitization of the light signal enhancing dynamic range and linearity

A SPAD-Based QVGA Image Sensor for Single-Photon Counting and Quanta Imaging

A CMOS single-photon avalanche diode (SPAD)-based quarter video graphics array image sensor with 8-μm pixel pitch and 26.8% fill factor (FF) is presented. The combination of analog pixel electronics and scalable shared-well SPAD devices facilitates high-resolution, high-FF SPAD imaging arrays exhibiting photon shot-noise-limited statistics. The SPAD has 47 counts/s dark count rate at 1.5 V excess bias (EB), 39.5% photon detection probability (PDP) at 480 nm, and a minimum of 1.1 ns dead time at 1 V EB. Analog single-photon counting imaging is demonstrated with maximum 14.2-mV/SPAD event sensitivity and 0.06e- minimum equivalent read noise. Binary quanta image sensor (QIS) 16-kframes/s real-time oversampling is shown, verifying single-photon QIS theory with 4.6× overexposure latitude and 0.168e- read noise