The influence of diet on the distribution of nitrogen isotopes in animals was investigated by analyzing animals grown in the laboratory on diets of constant nitrogen isotopic composition. 
The isotopic composition of the nitrogen in an animal reflects the nitrogen isotopic composition of its diet. The δ^(15)N values of the whole bodies of animals are usually more positive than those of their diets. Different individuals of a species raised on the same diet can have significantly different δ^(15)N values. The variability of the relationship between the δ^(15)N values of animals and their diets is greater for different species raised on the same diet than for the same species raised on different diets. Different tissues of mice are also enriched in ^(15)N relative to the diet, with the difference between the δ^(15)N values of a tissue and the diet depending on both the kind of tissue and the diet involved. The δ^(15)N values of collagen and chitin, biochemical components that are often preserved in fossil animal remains, are also related to the δ^(15)N value of the diet. 
The dependence of the δ^(15)N values of whole animals and their tissues and biochemical components on the δ^(15)N value of diet indicates that the isotopic composition of animal nitrogen can be used to obtain information about an animal's diet if its potential food sources had different δ^(15)N values. The nitrogen isotopic method of dietary analysis probably can be used to estimate the relative use of legumes vs non-legumes or of aquatic vs terrestrial organisms as food sources for extant and fossil animals. However, the method probably will not be applicable in those modern ecosystems in which the use of chemical fertilizers has influenced the distribution of nitrogen isotopes in food sources. 
The isotopic method of dietary analysis was used to reconstruct changes in the diet of the human population that occupied the Tehuacan Valley of Mexico over a 7000 yr span. Variations in the δ^(15)C and δ^(15)N values of bone collagen suggest that C_4 and/or CAM plants (presumably mostly corn) and legumes (presumably mostly beans) were introduced into the diet much earlier than suggested by conventional archaeological analysis.

Influence of Diet On the Distribtion of Nitrogen Isotopes in Animals

Optimisation of the anaerobic digestion of agricultural resources.

Selective adsorption of chromium(VI) in industrial wastewater using low-cost abundantly available adsorbents

The antitumor activity of the organometallic ruthenium(II)−arene complexes, RuCl2(η6-arene)(PTA), (arene = p-cymene, toluene, benzene, benzo-15-crown-5, 1-ethylbenzene-2,3-dimethylimidazolium tetrafluoroborate, ethyl benzoate, hexamethylbenzene; PTA = 1,3,5-triaza-7-phosphaadamantane), abbreviated RAPTA, has been evaluated. In vitro biological experiments demonstrate that these compounds are active toward the TS/A mouse adenocarcinoma cancer cell line whereas cytotoxicity on the HBL-100 human mammary (nontumor) cell line was not observed at concentrations up to 0.3 mM, which indicates selectivity of these ruthenium(II)−arene complexes to cancer cells. Analogues of the RAPTA compounds, in which the PTA ligand is methylated, have also been prepared, and these prove to be cytotoxic toward both cell lines. RAPTA-C and the benzene analogue RAPTA-B were selected for in vivo experiments to evaluate their anticancer and antimetastatic activity. The results show that these complexes can reduce the growth of lung m...

In Vitro and in Vivo Evaluation of Ruthenium(II)−Arene PTA Complexes

A technique is described for the measurement of fluid temperatures in microfluidic systems based on temperature-dependent fluorescence. The technique is easy to implement with a standard fluorescence microscope and CCD camera. In addition, the method can be used to measure fluid temperatures with micrometer spatial resolution and millisecond time resolution. The efficacy of the method is demonstrated by measuring temperature distributions resulting from Joule heating in a variety of microfluidic circuits that are electrokinetically pumped. With the equipment used for these measurements, fluid temperatures ranging from room temperature to 90 °C were measured with a precision ranging from 0.03 to 3.5 °Cdependent on the amount of signal averaging done. The spatial and temporal resolutions achieved were 1 μm and 33 ms, respectively.

Temperature measurement in microfluidic systems using a temperature-dependent fluorescent dye.

A process monitoring/controlling system for the treatment of wastewater containing chromium(VI)

Determination of chemical oxygen demand by a flow-injection method using cerium(IV) sulphate as oxidizing agent

The determination of chemical oxygen demand in waste-waters with dichromate by flow injection analysis

A novel computer-controlled micropump is developed for various flow analyses and offers a number of improvements to the limitations of conventional pumping systems. With flow patterns which are easily programmed, the pump allows precise microliter delivery and complete in-line mixing to be conveniently achieved. This instrument is particurlarly suitable for both heterogeneous flow analysis and flow analysis based on slow reaction because it provides a large interface between immiscible phases or miscible streams just after merging and hence promotes mass transfer in radial directions

Computer-controlled micropump suitable for precise microliter delivery and complete in-line mixing

A method is described for the continuous, rapid determination of chemical oxygen demand (COD). The method is based on flow injection analysis (FIA) and uses acidic potassium permanganate solution as both an oxidant and a spectrophotometric reagent, and glucose as a standard. COD values for aqueous environmental samples, such as industrial wastewaters, are compared with those obtained using the Japanese Industrial Standard (JIS) method and are found to be within an error range of ±30%. The method is comparable to other manual and automatic methods and has several advantages. A sampling rate of 20 samples per hour can be achieved, and the detection limit and precision are 5 mg l–1 as COD and 0.6%, respectively. Chloride ion up to levels of 6000 mg l–1 does not interfere, even in the absence of silver salts.

Takashi Korenaga

Papers

A process monitoring/controlling system for the treatment of wastewater containing chromium(VI)

Determination of chemical oxygen demand by a flow-injection method using cerium(IV) sulphate as oxidizing agent

The determination of chemical oxygen demand in waste-waters with dichromate by flow injection analysis

Computer-controlled micropump suitable for precise microliter delivery and complete in-line mixing

Continuous-flow injection analysis of aqueous environmental samples for chemical oxygen demand