Adsorption of divalent copper, zinc, cadmium and lead ions from aqueous solution by waste tea and coffee adsorbents.

The adsorption of the divalent cations of Cu, Zn, Cd and Pb by tea leaves and coffee grounds from aqueous solutions is described. Both adsorbents exhibited strong affinity for these ions which could be described by a simple single-site equilibrium model. For coffee, the order of increasing adsorption equilibrium constant K was Cu < Pb < Zn < Cd, while for tea the opposite order was observed indicating that the adsorption sites on each adsorbent have a different chemical nature. Adsorption decreased at low pH < 4 through competition with H+ for adsorption sites, and for all metals except Cu, at high pH > 10, probably because of anion formation in the case of Zn2+ and also increased leaching of metal-binding soluble materials. The effect of metal ion concentration on the adsorptive equilibria indicated a threshold concentration above which overall adsorption became limited by saturation of the adsorption sites. Competition between two metal ions for the same sites was not observed with Cu(II) and Pb(II), however Zn(II) reacted competitively with Cd(II) binding sites on both tea and coffee. If fresh coffee or tea adsorbents were used, the fraction of metal ion taken up by the adsorbent was diminished by the competitive effects of soluble metal-binding ligands released by the tea or coffee. Experiments with coffee showed that roasting temperature controls the formation of metal ion adsorption sites for this adsorbent.

Automated electrochemical analysis with combinatorial electrode arrays.

Two combinatorial approaches for rapid automated screening of electrochemical activity of modified electrode surfaces are described. One approach enables simultaneous comparison of electrochemical current by fluorescence associated with pH changes that accompany consumption or production of protons at the electrode surface during a redox process. However, this method cannot distinguish small differences in current at differently modified electrodes. A second approach relies on computer-automated, serial measurement of electrochemical current at each electrode of a 64-electrode array immersed in a single electrochemical cell. Unlike the fluorescent screen, the second method is capable of distinguishing small differences in current at differently modified electrodes, as demonstrated here for gold electrode surfaces covered with organosulfur monolayers of different chain lengths. The improved precision of the computer-automated direct electrochemical method enables examination of active zones that have been first identified by less precise parallel fluorescent screening methods. The direct electrochemical measurement method can easily be extended to a variety of electrode materials, including fuel cell electrocatalysts and redox storage materials. A complete description of the methodology, hardware and computer program for automated measurement is provided.

Suspension and protoplast culture of U.S. rice cultivars.

Efficient protoplast culture and plant regeneration of five U.S. rice cultivars (Oryza sativa L.) - Mercury, Lacassine, Maybelle, Cypress, and Lemont - were obtained from suspension cells maintained in modified General Medium. Embryogenic suspension cells were developed from calli grown on the original callus induction medium for 10-20 weeks without subculture. Weekly subculture of the suspensions for five to eight weeks yielded cells suitable for protoplast isolation. After 2 weeks, rate of colony formation from protoplasts varied among the cultivars and ranged from 2.5 to 6.8%. Improvement of plating efficiencies to as high as 13.7% was obtained by conducting a second cycle of protoplast culture. A total of 525 plants were regenerated from the cultivars studied.

Plasma lipid peroxides in coronary heart disease.

The relation between plasma lipid peroxide and coronary heart disease was investigated at Harapan Hospital in Kita Jakarta. Ninety-eight patients (83 males and 15 females), below 75 years old were included in the study. The samples consisted of 47 cases with angina and 22 cases with myocardial infarction which were proven to suffer from coronary atherosclerosis by the presence of clinical symptoms, ECG abnormalities, angiography and myocardial enzyme measurement. Controls were patients who did not show any abnormalities in the parameters used. Controls and patients were classified into several groups based on the presence or absence of risk factors (smoking, hypertension, diabetes mellitus, hyperlipidemia, obesity, family history). The results of the study showed that plasma lipid peroxide in patients with angina and myocardial infarction which were 3.26 +/- 1.07 mumol and 3.20 +/- 0.82 mumol/l, respectively, were significantly higher (p less than 0.05) than controls 2.50 +/- 0.45 mumol/l. There was no differences in total cholesterol, LDL and triglyceride contents between control and patients with coronary heart disease; whereas HDL cholesterol level was significantly higher in the patients with angina, 38.7 +/- 10.5 mg/dl vs 31.5 +/- 6.76 mg/dl in patients with myocardial infarction. Univariate analysis of various risk factors revealed a strong correlation between plasma lipid peroxide and the chance in developing coronary heart disease. The present study showed that plasma lipid peroxide was increased in coronary heart disease and that it might be used as a determinant in the assessment of the severity of the disease. An investigation on the effects of antioxidants in these patients is planned.