Potential Of Different Species Research Articles

Acorn (Quercus spp.) as a novel source of oleic acid and tocopherols for livestock and humans: discrimination of selected species from Mediterranean forest.

The aim of the present work was to characterization and compare acorns from selected Quercus spp. from the Mediterranean forest in Spain, namely, Portuguese oak (QF, Quercus faginea Lam.), Cork oak (QS, Quercus suber L.), Pyrenean oak (QP, Quercus pyrenaica Wild), Kermes oak (QC, Quercus coccifera L.), Holm oak (QB, Quercus ilex L. subsp. ballota [Desf.]). All physicochemical attributes varied significantly between species. Fat contents ranged from 1.30 to 4.70g 100g-1 fresh matter. The most abundant fatty acids were oleic (62.44, 56.25, 57.46, 48.02, 65.83%), followed by linoleic (16.42, 20.73, 21.30, 25.38, 14.17%) and palmitic (11.69, 14.27, 12.17, 16.22, 12.28) acids in QF, QS, QP, QC and QB species, respectively. The tocopherol content was high in the range of 31.83-45.25mgkg-1, and γ-tocopherol constituted 67-78% of total tocopherols. Only an effect of the location on γ-tocopherol content in QB was observed. The present results show the potential of different species of acorn to be used as agricultural and food resources and that geographical location plays a secondary role.

Forest mammal roadkills as related to habitat connectivity in protected areas

Fragmentation of wildlife habitat by road development is a major threat to biodiversity. Hence, conservation and enhancement of habitat connectivity in roaded landscapes are crucial for effectively maintaining long-term persistence of ecological processes, such as gene flow and migration. Using multivariate statistical techniques combined with graph theoretical methods, we investigated the influence of road-crossing habitat connectivity and road-related features on roadkill abundance of forest mammals in protected areas of South Korea. Because species have different dispersal abilities and thus connectivity would differ between them, we explored three different groups of road-killed mammals, categorized as small, intermediate, and large ones. We found that in all three mammal groups, roadkills are increased on roads that intersect high-connectivity routes. Furthermore, the effect of habitat connectivity on roadkill abundance was scale-dependent. The roadkill abundances of small, intermediate, and large mammals were related with connectivity measured at scales ranging between 100 and 300 m, between 5 and 7 km, and between 10 and 25 km, respectively. Our finding with regard to scale-dependency highlights the importance of maintaining movement and connectivity across roads at multiple scales based on the dispersal potential of different species when planning conservation strategies for forest mammalian roadkill mitigation.

СТАН ГУМОРАЛЬНОЇ ЛАНКИ ІМУННОГО СТАТУСУ У БУГАЙЦІВ НА ВІДГОДІВЛІ ЗА ВПЛИВУ ВІТАМІНІВ ГРУПИ B (B1, B2, B5, B6, B10, B12)

In realization of the genetic productivity potential of different species of farm animals, an important place is given to full feeding. Insufficient supply of farm animals with individual vitamins has negative impact on the activity of the relevant enzyme systems, hormonal status, metabolism of nutrients, the state of the natural resistance of the various organs and organ systems, the processes of adaptation and productivity level.Numerical searches have shown that farm animals need in different vitamins depends on the type, age, sex, physiological state, the season, the level of productivity and others. According to some reports ruminants have been providing with water–soluble B vitamins by their rumen microbial synthesis accordingly it was recommended to rations setting for cattle, sheep and goats, along with nutrients and minerals only by carotene and vitamins D and E .Studies have shown that the addition to the diet of calves for fattening complex of B vitamins (В1, В2, В5, В6, В10, В12) in different doses generally positive effect on bactericidal, lisocim and complement activity of blood serum, immunoglobulin cell in bull fattening.Studies have shown that the addition to the diet of bull fattening balanced in nutrients and minerals and fat–soluble vitamins A, D, E complex of B vitamins (В1, В2, В5, В6, В10, В12) in appropriate doses generally positive effect on humoral immunity state, major changes are complement activity of blood serum, depends on the dose additionally entered the diet fattening bulls B vitamins.The biggest change on humoral immunity state of calves for fattening derived from animals 3rd D (B1 – 0.040; B2 – 0.06; B5 – 1.2; B6 – 0.25, B10 – 0.0030; B12 – 0.0006 mg/kg body weight) and 4th D (B1 – 0.070; B2 – 0.10; B5 – 2.0; B6 – 0.40; B10 – 0.0050; B12 – 0.0010 mg/kg body weight) groups, and the smallest – in calves 1th D (В1 –0.015; В2 – 0,03; В5 – 0.5; В6 – 0.10; В10 – 0.0012; В12 – 0.0002 mg/kg body weight) group.

Evident elevation of atmospheric monoterpenes due to degradation-induced species changes in a semi-arid grassland

Biogenic volatile organic compounds (BVOCs) emitted from plants have substantial effects on atmospheric chemistry/physics and feedbacks on ecosystem function. The on-going climate change and anthropogenic disturbance have been confirmed to cause the evident degradation of grassland with shift of plant community, and hence BVOCs emissions were suspected to be altered due to the different BOVCs emission potentials of different species. In this study, we investigated BVOCs concentration above ground surface during growing season in a degraded semi-arid grassland (41°2′ N–45°6′ N, 113°5′–117°8′) in Inner Mongolia. The observed monoterpenes' concentrations varied from 0.10 to 215.78μgm−3 (34.88±9.73μgm−3 in average) across 41 sites. Compared to non-degraded grassland, concentrations of monoterpenes were about 180 times higher at the sites dominated by subshrub — Artemisia frigida, a preponderant species under drought stress and over-grazing. The biomass of A. frigida explained 51.39% of the variation of monoterpenes' concentrations. α-pinene, β-pinene and γ-terpinene dominated in the 10 determined monoterpenes, accounting for 37.72±2.98%, 14.65±2.55% and 10.50±2.37% of the total monoterpenes concentration, respectively. Low isoprene concentrations (≤3.25μgm−3) were found and sedge biomass contributed about 51.76% to their spatial variation. α-pinene and isoprene emissions at noon were as high as 515.53±88.34μgm−2h−1 and 7606.19±1073.94μgm−2h−1 in A. frigida- and sedge-dominated areas where their biomass were 236.90gm−2 and 72.37gm−2, respectively. Our results suggested that the expansion of A. frigida and sedge caused by over-grazing and climatic stresses may increase local ambient BVOCs concentration in grassland.

Growth potential of different species and genotypes for biomass production in short rotation in Mediterranean environments

The sustainable production of lignocellulosic biomass in Short Rotation Coppice (SRC) in the context of bioeconomic development in Europe demands an ever greater understanding of the plant material. Different species and, in some cases, different genotypes (Populus deltoides ‘Baldo’, Populus x canadensis: ‘Orion’, ‘Oudenberg’, ‘Ballottino’ and ‘I-214’; Robinia pseudoacacia ‘Nyirsegi’, Salix matsudana x Salix spp. ‘Levante’ and Platanus x hispanica ‘Girona’) were tested at four contrasting Mediterranean locations to determine the biomass yield after three years. Besides production, genotypic stability is a key factor in furthering our understanding of the plant material, with important implications for the management of plantations as well as for breeding. To study this factor, several stability models were compared (additive mixed model, Shukla’s stability variance model, Finlay–Wilkinson and Eberhart–Russell models) and differences in the response capacity of the material were evaluated in the different environments. This evaluation of genotypic stability, based on the measurement of variances, was complemented by an analysis of the mean genotypic value and the variability in genotype productivity. Intrinsic water use efficiency was also evaluated as it is an important trait of plant material destined for use in Mediterranean conditions. S. matsudana x Salix spp. ‘Levante’ exhibited the highest production and showed an intermediate reactivity (stability) as well as high intrinsic water use efficiency under the conditions in which it was tested. P. x canadensis ‘Orion’ also displayed a good overall performance and was highly sensitive to improving environmental conditions. Conversely, R. pseudoacacia and P. x hispanica presented yields well below the average as well as low responsiveness to improved environmental conditions. Our findings will contribute to a better understanding of plant material, enabling improved recommendations for plantations the Mediterranean area, including more precise large scale predictions. Furthermore, the information provided will be of particular value in future breeding programs.

Exploring bioenergy potentials of built-up areas based on NEG-EROEI indicators

The production of bioenergy is dependent on the supply of biomass. Biomass production for bioenergy may cause large land use conversions, impact agricultural production, food prices, forest conservation, etc. The best solution is to use biomass that does not have agricultural or ecological value. Some of such unconventional sources of biomass are found within urban spaces. We employed Geographic Information System (GIS) and quantitative Life Cycle Assessment (LCA) methodologies to identify and estimate bioenergy potential of green roofs and other bioenergy options within urban areas. Net Energy Gain (NEG) and Energy Return on Energy Invested (EROEI) were used as indicators to assess the bioenergy potential of urban spaces within the Overijssel province of the Netherlands as a case study. Data regarding suitable areas were geometrically extracted from available GIS datasets, and used to estimate the biomass/bioenergy potential of different species with different yields per hectare, growing under different environmental conditions. We found that potential net-energy gain from built-up areas can meet 0.6–7.7% of the 2030 renewable energy targets of the province without conflicting with socio-ecological concerns, while also improving human habitat.

Influence of agro-climatic conditions on antioxidant potential of Mentha species

BackgroundMentha species are known to be important sources of antioxidants. The antioxidant potential of different species may be affected when grown in different agro-climatic conditions. So the effect of location on the antioxidant potential of two Mentha species has been studied. MethodsMentha species (Mentha longifolia and Mentha spicata) were raised at two different locations i.e. in Lovely Professional University (Punjab) and in Kashmir University (Srinagar). The first and second generation leaves of these Mentha species were plucked at after one month interval from the plants and extracted with different solvents. The extracts were analyzed for total phenols, flavonoids and antioxidant potential using various in vitro models. ResultsM. spicata had a relatively higher total phenols, flavonoids and antioxidant properties than those of M. longifolia raised at either of the locations. M. spicata and M. longifolia raised at higher altitude had much higher content of total phenols and flavonoids as well as antioxidant potential than the respective species raised in plains of Punjab during same period. Moreover, the leaves of second generation had higher content of total phenols and flavonoids but had lower antioxidant potential than that of first generation leaves. ConclusionAntioxidant potential of Mentha species raised at higher altitude was far better than the corresponding species raised in plains. Moreover, first generation leaves had better antioxidant potential. No direct correlation between total phenols, flavonoid content and antioxidant potential of these species could be established.

Forestry activity is one mechanism of invasion by arboreal plants

For a long time, forestry primarily had industrial goals. Volume of wood production was the main criterion of forestry efficacy, and thus rapid-growing arboreal species were cultivated in natural forests. More recently, nature protection has become one of forestry’s goals. Unfortunately, some introduced, rapid-growing species became aggressive components of natural ecological systems during the interim. In this paper, we first describe a method that we developed to categorize aggressiveness of invasive arboreal plants in natural forest ecosystems of Kazakhstan. We then apply this new scheme to monitoring data of invasive arboreal plants to provide an insight into the invasion potential of different species in the fruit forests of Southeast Kazakhstan.

Antimelanoma and radioprotective activity of alcoholic aqueous extract of different species of Ocimum in C57BL mice

Context: Various Ocimum species (Labiateae) are commonly used for the treatment of inflammation, stress, diarrhea, and as an antioxidant drug in the Indian ethnic system of medicine.Objective: The present study was carried out to investigate the antimelanoma and radioprotective activity of different species of Ocimum in C57BL and Swiss albino mice.Materials and methods: The antimelanoma activity of 50% alcoholic aqueous leaf extract of five species of Ocimum [Ocimum sanctum (SE), Ocimum gratissimum (GE), Ocimum basilicum (BE), Ocimum canum (CE), and Ocimum kilimandscharicum (KE)] alone or in combination with radiotherapy was determined on the basis of tumor volume, body weight, and survival rate of animals. The radioprotective potential of different species of Ocimum was determined by chromosomal aberration assay. The effect of the alcoholic aqueous extract of different species of Ocimum was also evaluated for the estimation of glutathione level and glutathione S-transferase activity in Swiss albino mice.Results: The 50% alcoholic aqueous extract of different species of Ocimum administered orally (200 mg/kg, p.o.) resulted in significant reduction in tumor volume, increase in average body weight, and survival rate of mice. The various extracts showed modulatory influence against lethal irradiation doses of gamma radiation in terms of radiation-induced chromosomal damage, while at the same time induced an increase in reduced glutathione level and GST activity.Discussion and conclusion: These findings demonstrate that Ocimum species have antimelanoma and radioprotective activity against B16F10 metastatic melanoma cell line-induced metastasis and could be exploited as one of the potential sources for plant-based pharmaceutical products.

Desafios técnicos e barreiras sociais,econômicas e regulatórias na fitorremediação de solos contaminados

A fitorremediação - uso de plantas e comunidades microbianas associadas à rizosfera para degradar, isolar ou imobilizar contaminantes do solo e água - é uma técnica de custo relativamente baixo, vantagens estéticas e que não gera impactos adicionais. A maioria dos estudos com plantas na recuperação de áreas contaminadas tem sido desenvolvida em países de clima temperado, onde o potencial da fitorremediação é limitado por fatores climáticos. No Brasil, o conhecimento acerca do potencial fitorremediador das várias espécies de plantas e comunidades microbianas em solos tropicais é ainda muito escasso, o que, associado à falta de instrumentos de aferição e de apoio à decisão, dificulta a recomendação por parte das agências ambientais e empresas. A presente revisão descreve brevemente os mecanismos de fitorremediação e discute aspectos sociais, econômicos e reguladores que representam entraves ao amplo desenvolvimento da técnica, em comparação com técnicas convencionais, mais conhecidas e aceitas pelas agências e empresas. Finalmente, o mercado brasileiro presente e futuro é discutido, sendo sugerida a criação de protocolos experimentais e instrumentos de apoio à decisão que estimulem a aplicação da fitorremediação nos casos em que ela se apresente como a opção mais adequada.

Comparative studies on the nutritive and anti-nutritive properties of fruits in selected Berberis species of West Himalaya, India

Nutritional and anti-nutritional factors of five Berberis species, widely known for their wild edible fruits and medicinal properties, were investigated in the Indian west Himalaya. These fruits contained high content of fiber (pulp 7.0–8.1%; seeds 4.4–5.3%), protein (pulp 4.7–7.2%; seeds 5.9–8.5%) and fat (pulp 2.6–4.0%; seeds 4.6–5.3%) as compared to most of the known wild edibles in the region. They, however, contained reasonably lower food energy, largely due to low carbohydrate content. All the five species emerged as good source of minerals, especially Ca and K. The values of various nutrient and mineral elements varied significantly among species, which implies potential of different species can be harnessed for diverse attributes. The fruits, however, possessed anti-nutritional factors like tannins and phytic acid, which need to be tackled appropriately while considering these fruits for value addition as health food.

Potential of different species for use in removal of DDT from the contaminated soils

Dichlorodiphenyltrichloroethane (DDT) and its main metabolites, p, p′-DDD and p, p′-DDE (DDTs in this study included DDT, DDD and DDE), are frequently detected in agricultural soils even though its usage in agriculture was banned in 1980s or earlier. In this study, eleven plants including eight maize ( Zea mays) cultivars and three forage species (alfalfa, ryegrass and teosinte) widely cultivated in China were grown in the soils spiked with DDTs to investigate their potential for removal of DDT from the contaminated soils. The plants varied largely in their ability to accumulate and translocate DDTs, with the bioconcentration factor (BCF; DDT concentration ratio of the plant tissues to the soils) ranging from 0.014 to 0.25 and the translocation factor (TF; DDT concentration ratio of the shoots to the roots) varying from 0.35 ( Zea mays cv Chaotian-23) to 0.76 ( Zea mays spp. mexicana). The amount of DDT phytoextraction ranged from 3.89 μg (ryegrass) to 27.0 μg (teosinte) and accounted for <0.1% of the total initial DDTs spiked in the soils. After 70 d, the removal rates reached 47.1–70.3% of the total initial DDTs spiked in the soils with plants while that was only 15.4% in the soils without plant. Moreover, the higher removal rates of DDTs occurred at the first 20 d of experiment, and then the removal rate decreased with time. The highest amount of DDTs phytoextracted was observed in teosinte, followed by Zea mays spp. mexicana, but the highest removal rate of DDTs was found in maize ( Zea mays cv Jinhai-6). Even though phytoextraction is not the main removal process for DDTs, the plant species especially Zea mays cv Jinhai-6 showed high potential for removing DDTs from the contaminated soils.

Potential contribution of the forestry sector in Bangladesh to carbon sequestration

The Kyoto Protocol provides for the involvement of developing countries in an atmospheric greenhouse gas reduction regime under its Clean Development Mechanism (CDM). Carbon credits are gained from reforestation and afforestation activities in developing countries. Bangladesh, a densely populated tropical country in South Asia, has a huge degraded forestland which can be reforested by CDM projects. To realize the potential of the forestry sector in developing countries for full-scale emission mitigation, the carbon sequestration potential of different species in different types of plantations should be integrated with the carbon trading system under the CDM of the Kyoto Protocol. This paper discusses the prospects and problems of carbon trading in Bangladesh, in relation to the CDM, in the context of global warming and the potential associated consequences. The paper analyzes the effects of reforestation projects on carbon sequestration in Bangladesh, in general, and in the hilly Chittagong region, in particular, and concludes by demonstrating the carbon trading opportunities. Results showed that tree tissue in the forests of Bangladesh stored 92 tons of carbon per hectare (tC/ha), on average. The results also revealed a gross stock of 190 tC/ha in the plantations of 13 tree species, ranging in age from 6 to 23 years. The paper confirms the huge atmospheric CO 2 offset by the forests if the degraded forestlands are reforested by CDM projects, indicating the potential of Bangladesh to participate in carbon trading for both its economic and environmental benefit. Within the forestry sector itself, some constraints are identified; nevertheless, the results of the study can expedite policy decisions regarding Bangladesh's participation in carbon trading through the CDM.

EVOLUTION OF THE ALLERGENIC POTENTIAL IN PEACH AND NECTARINE FRUITS DURING RIPENING

According to recent epidemiological studies, in many countries food allergies increased strongly during recent decades. Allergies to fruits represent also an emerging problem and studies should be addressed to identify allergens, evaluate the allergenic potential of different species and varieties and, possibly, produce hypoallergenic fruits. In peach, the major allergen has been identified as a Lipid Transfer Protein (LTP) and in the present research the evolution of the allergenic potential of different peach and nectarine varieties has been monitored throughout ripening and in relation to postharvest treatments. Fruits of peach cv. 'Royal Gemm', 'Zorzi', of nectarine cv. 'Rita Star', 'Early Giant' and 'Maria Dorata', and of flat type (Platicarpa) were harvested in correspondence of commercial ripeness and allowed to ripen at room temperature or stored at 4°C for 3 weeks. Northern blot analyses were carried out on total RNA extracted from epicarp and mesocarp to study Pp-LTP1 gene expression. Immunological studies were performed by means of a polyclonal antibody raised against the purified protein. Expression analysis showed that Pp-LTP1 transcripts accumulated only in the epicarp. With the exception of cv. 'Rita Star' the strongest accumulations have been detected in epicarp of all varieties at harvest. With the exception of Platicarpa, a decreasing trend of expression was observed in fruits kept in air and at 4°C. Western blots revealed the presence of LTP only in epicarp of all studied varieties, but not in 'Rita Star', and showed that the protein markedly increased in full ripe fruits maintained in air. This might indicate the presence of a lag between gene transcription and accumulation of secreted functional LTP. According to these results, cv. 'Rita Star' appears to be a variety with a reduced allergenic potential.

A comparative study of hydrocarbon degradation byMarinobactersp.,Rhodococcussp. andCorynebacteriumsp. isolated from different mat systems

Abstract This comparative study of the hydrocarbon degrading potential of different species and genera of oil degrading bacteria shows that whilst Marinobacter spp. were frequently isolated hydrocarbon degrading organisms from all the sites sampled they had the lowest mineralization rates. In contrast, Rhodococcus isolate O1-NR-LI and Corynebacterium isolate T2W rapidly degraded hexadecane when present either as sole carbon source or in binary and tertiary hydrocarbon model mixtures. Octadecane was metabolized more rapidly in binary and tertiary hydrocarbon mixtures due to solubilisation in hexadecane which increased bio-availability. Mineralisation of the branch-chained alkane, pristane was always slower in hydrocarbon mixtures than for straight chain saturated hydrocarbons. None of the isolates could degrade benzothiophene and when present in model hydrocarbon mixtures it inhibited mineralization until the concentration decreased below the inhibitory threshold.

Bayesian analysis of systems with random chemical composition: renormalization-group approach to Dirichlet distributions and the statistical theory of dilution.

We investigate the statistical properties of systems with random chemical composition and try to obtain a theoretical derivation of the self-similar Dirichlet distribution, which is used empirically in molecular biology, environmental chemistry, and geochemistry. We consider a system made up of many chemical species and assume that the statistical distribution of the abundance of each chemical species in the system is the result of a succession of a variable number of random dilution events, which can be described by using the renormalization-group theory. A Bayesian approach is used for evaluating the probability density of the chemical composition of the system in terms of the probability densities of the abundances of the different chemical species. We show that for large cascades of dilution events, the probability density of the composition vector of the system is given by a self-similar probability density of the Dirichlet type. We also give an alternative formal derivation for the Dirichlet law based on the maximum entropy approach, by assuming that the average values of the chemical potentials of different species, expressed in terms of molar fractions, are constant. Although the maximum entropy approach leads formally to the Dirichlet distribution, it does not clarify the physical origin of the Dirichlet statistics and has serious limitations. The random theory of dilution provides a physical picture for the emergence of Dirichlet statistics and makes it possible to investigate its validity range. We discuss the implications of our theory in molecular biology, geochemistry, and environmental science.

Interspecific Variation in Climbing by Gastropods: Implications for Transmission of Parelaphostrongylus tenuis

-Most studies of the gastropod intermediate hosts of the nematode parasite Parelaphostrongylus tenuis used cardboard placed on the ground to collect host specimens. We examined interspecific variation in climbing behavior of seven gastropod species from Algonquin Park, Ontario, to evaluate the potential for sampling bias and its implications (1) for inferences regarding which gastropods may be important in parasite transmission and (2) for estimating parasite prevalence in gastropods. Gastropods were highly variable in the degree to which they climbed and when they did so. Zonitoides arboreus, Anguispira alternata and Deroceras laeve climbed relatively infrequently; Stenotremafraternum and Mesodon sp. were most arboreal. Discus cronkhitei and Succinea ovalis were intermediate; they spent about as much time on the ground as they did climbing. Thus, the latter species are potentially most important as intermediate hosts because they frequent the ground where they can become infected with the parasite, but also climb to where they may be more vulnerable to ingestion by foraging deer and moose. A comparison of gastropod collections was made between studies that used cardboard to sample gastropods and studies where hand-searching was used. It revealed that species from the families Zonitidae and Limacidae comprised the largest fractions of collections using cardboard, consistent with the idea that cardboard samples are biased to terrestrial species. If collections are biased, prevalence levels detected for gastropod hosts of P tenuis may underestimate true levels. Therefore, the degree of arboreality among gastropod intermediate hosts could be important to consider when evaluating the potential for different species to serve as important vectors of transmission of P tenuis.

Relationship between susceptibility to protein oxidation, aging, and maximum life span potential of different species.

The main objective of this study was to determine whether antioxidative potential of the tissues plays a role in the aging process. Antioxidative potential was ascertained as the susceptibility of tissues to undergo protein oxidation, manifested as protein carbonyls, in response to acute oxidative stress, induced by exposure to x-rays. Brain homogenates from 22-month-old rats were more susceptible to oxidative stress than those from three-month-old rats. Brain was more susceptible to oxidative damage than the heart. A comparison of the susceptibility of brain and heart homogenates in five different species (mouse, rat, rabbit, pig, and pigeon) indicated that maximum life span potential of the species was inversely related to their susceptibility to acute oxidative stress.

Mitochondrial superoxide and hydrogen peroxide generation, protein oxidative damage, and longevity in different species of flies

The objective of this study was to further elucidate the role of oxidative stress in the aging process by determining whether or not the rates of mitochondrial superoxide anion radical and hydrogen peroxide (H 2O 2) production, the activity of cytochrome c oxidase, and the concentration of protein carbonyls are correlated with the life span potential of different species. A comparison was made among five different species of dipteran flies, namely, Drosophila melanogaster (fruit fly), Musca domestica (house fly), Sarcophaga bullata (flesh fly), Calliphora vicina (blow fly) and Phaenecia sericata (a species of blow flies), which range more than 2-fold in their life span potentials. The average life span potential of these species was found to be inversely correlated with the rates of mitochondrial superoxide and H 2O 2 production and with the level of protein carbonyls, and to be directly related to the activity of cytochrome c oxidase. The significance of these findings in context of the validity of the oxidative stress hypothesis of aging is discussed. It is inferred that longer life span potential in these insect species is associated with relatively low levels of oxidant generation and oxidative molecular damage. These results accord with our previous findings on different mammalian species.

High-concentration point-defect chemistry: Statistical-thermodynamic approach applied to nonstoichiometric cerium dioxides.

Many properties of crystalline solids are controlled by the presence of point defects. Traditionally the concentrations of these defects are calculated using mass action laws that describe the reactions among the defects and with the environment. This formulation, however, is not applicable in the high-defect-concentration regime because it is based on assumptions that are valid only at the limit of dilute defect concentration. In the present work a statistical thermodynamic approach is used to develop a defect chemistry formulation that has general applicability at all levels of defect concentrations. This is accomplished by deriving an expression for the virtual chemical potential of point defects from the Gibbs free energy that includes contributions from short-range and long-range Coulombic interactions, and from a configurational entropy that incorporates generalized exclusion effects. By balancing the chemical potentials of different species and the environment as required under thermodynamic equilibrium conditions, one can derive equations that govern the concentrations of defects. At the limit of low defect concentration, the current approach is shown to be equivalent to that of the traditional theory. This formulation is demonstrated by working out an example in detail using undoped ${\mathrm{CeO}}_{2\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\delta}}}$ as a model system. The concentrations of different species are calculated as functions of T and ${\mathit{P}}_{\mathrm{O}2}$ using a numerical routine based on the conjugate gradient algorithm. The oxygen deficiency \ensuremath{\delta} is obtained as the net concentrations of all oxygen vacancy containing species, and is found to be in good agreement with literature data. The effects of defect interactions and exclusions are discussed, and the thermodynamic activities of different species are calculated as functions of environmental parameters.