Speciation, Luminescence, and Alkaline Fluorescence Quenching of 4-(2-methylbutyl)aminodipicolinic acid (H2MEBADPA)

4-(2-Methylbutyl)aminodipicolinic acid (H2MEBADPA) has been synthesized and fully characterized in terms of aqueous phase protonation constants (pKa\u27s) and photophysical measurements. The pKa\u27s were determined by spectrophotometric titrations, utilizing a fully sealed titration system. Photophysical measurements consisted of room temperature fluorescence and frozen solution phosphorescence as well as quantum yield determinations at various pH, which showed that only fully deprotonated MEBADPA2– is appreciably emissive. The fluorescence of MEBADPA2– has been determined to be quenched by hydroxide and methoxide anions, most likely through base-catalyzed excited-state tautomerism or proton transfer. This quenching phenomenon has been quantitatively explored through steady-state and time-resolved fluorescence measurements. Utilizing the determined pKas and quenching constants, the fluorescent intensity of MEBADPA2– has been successfully modeled as a function of pH

Diol esters - a family of potential plant growth regulators

Rice bran wax was found to contain 1, 3-propane diol mono- and diesters of palmitic, stearic, oleic and linolenic acids. The unsaturated esters (especially diesters) are found to be eminently active in the biological growth of rice and wheat seedlings in laboratory tests and under field conditions. They are able to induce appreciable increase in root length, fresh and dry weight, chlorophyll content and rate of photosynthesis in seedlings/plants and also yield of rice grains in the field. An extract of alfalfa revealed the presence of another family of diol esters, namely, 2-methyl 1, 4-butane diol esters of unsaturated acids which are at least as good as the 1, 3-propane diol esters in the plant growth regulating activities. Therefore, the plant growth regulating effect of alfalfa extract attributed to triacontanol could be due to the presence of diol esters as well. The natural occurrence of hitherto unreported diol esters and more importantly their plant growth regulating activities are now described

Direct detection of nucleic acid hybridization on the surface of a charge coupled device.

A method is described for the detection of DNA hybrids formed on a solid support, based upon the pairing of oligonucleotide chemistry and the technologies of electronic microdevice design. Surface matrices have been created in which oligonucleotide probes are covalently linked to a thin SiO2 film. 32P labeled target nucleic acid is then hybridized to this probe matrix under conditions of high stringency. The salient feature of the method is that to achieve the highest possible collection efficiency, the hybridization matrix is placed directly on the surface of a charge coupled device (CCD), which is used to detect 32P decay from hybridized target molecules (1, Eggers, M.D., Hogan, M.E., Reich, R.K., Lamture, J.B., Beattie, K.L., Hollis, M.A., Ehrilich, D.J., Kosicki, B.B., Shumaker, J.M., Varma, R.S., Burke, B.E., Murphy, A., and Rathman, D.D., (1993), Advances in DNA Sequencing Technology, Proc. SPIE, 1891, 13-26). Two implementations of the technology have been employed. The first involves direct attachment of the matrix to the surface of a CCD. The second involves attachment of the matrix to a disposible SiO2 coated chip, which is then placed face to face upon the CCD surface. As can be predicted from this favorable collection geometry and the known characteristics of a CCD, it is found that as measured by the time required to obtain equivalent signal to noise ratios, 32P detection speed by the direct CCD approach is at least 10 fold greater than can be obtained with a commercial gas phase array detector, and at least 100 fold greater than when X-ray film is used for 32P detection. Thus, it is shown that excellent quality hybridization signals can be obtained from a standard hybridization reaction, after only 1 second of CCD data acquisition