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491.
A kinetic study of anaerobic digestion of olive mill wastewater at mesophilic and thermophilic temperatures 总被引:3,自引:0,他引:3
Borja R Martín A Banks CJ Alonso V Chica A 《Environmental pollution (Barking, Essex : 1987)》1995,88(1):13-18
The kinetics of the anaerobic digestion of olive mill wastewater (OMW) was studied in the mesophilic and thermophilic ranges of temperature. Two completely mixed continuous flow bioreactors operating at 35 degrees C and 55 degrees C and with an average biomass concentration of 5.45 g VSS litre(-1) were used. The thermophilic reactor worked satisfactorily between hydraulic retention times (HRT) of 10 to 40 days, removing between 94.6 and 84.4% of the initial chemical oxygen demand (COD). In contrast, the mesophilic reactor showed a marked decrease in substrate utilization and methane production at a HRT of 10 days. TVFA levels and the TVFA/alkalinity ratio were higher and close to the suggested limits for digester failure. The yield coefficient for methane production (1 CH(4) STP g(-1) COD(added)) was 28% higher in the thermophilic process than in the mesophilic one. Macroenergetic parameters, calculated using Guiot's kinetic model, gave yield coefficients for the biomass (Y) of 0.18 (mesophilic) and 0.06 g VSS g(-1) COD (thermophilic) and specific rates of substrate uptake for cell maintenance (m) of 0.12 (mesophilic) and 0.27 g COD g(-1) VSS.day(-1) (thermophilic). The experimental results showed the rate of substrate uptake (R(s); g COD g(-1) VSS.day(-1)), correlated with the concentration of biodegradable substrate (S(b); g COD litre(-1)), through an equation of the Michaelis-Menten type for the two temperatures used. 相似文献
492.
Rosas I Velasco A Belmont R Báez A Martínez A 《Environmental pollution (Barking, Essex : 1987)》1993,80(3):255-264
An evaluation of water quality and phytoplankton composition position was carried out in order to determine the trophic conditions of Lake Patzcuaro (2035 m above sea level), a high altitude tropical lake. Temperatures ranged from 15 to 23 degrees C. Total phosphorus and inorganic nitrogen showed a seasonal variation; highest values coincided with the rainy season (0.48 and 2.1 mg litre(-1), respectively). Dissolved oxygen ranged from 2 to 7.9 mg litre(-1) at the surface and from 0.6 to 7.3 mg litre(-1) on the bottom, the lowest values being found in shallow zones. Average transparency varied from 0.62 to 1.4 m Secchi depth. Rainfall was a primary factor in seasonal variability as it influenced both physical and biological conditions by contributing to the transport and deposition of silt, which mixed with sinking algal cells. The composition of the surface phytoplankton segregated along five major divisions comprising a total of 49 species. General seasonal patterns of dominance alternated in a sequence beginning with Bacillariophyta, through Chlorophyta to Cyanophyta. Diatoms, the dominant group from February to early June, included Melosira granulata, Stephanodiscus sp., Synedra sp. and Fragilaria sp. During the rainy season (late June to September), Microcystis aeruginosa, Oscillatoria sp., Anabaena sp., Merismopedia sp., Crucigenia cuadrata, Oocystis lacustris, Selenastrum gracile, Mallomonas sp. and Tetraediella sp. were important. Melosira granulata was present throughout the period of study. Spatial and temporal variability in both physical and biological conditions make it difficult to assign a specific trophic state to Lake Patzcuaro. Nevertheless, analysis of the algal community indicates a generally mesotrophic condition. 相似文献
493.
Martínez-de la Puente J Merino S Tomás G Moreno J Morales J Lobato E Martínez J 《Die Naturwissenschaften》2011,98(2):99-106
Parasites are undoubtedly a biotic factor that produces stress. Heat shock proteins (HSPs) are important molecules buffering cellular damage under adverse conditions. During the breeding season, blue tit Cyanistes caeruleus (L.) adults are affected by blood parasites, nest-dwelling parasites and biting flies, potentially affecting their HSP-mediated responses. Here, we treated females with primaquine to reduce blood parasites and fumigated nests with permethrin to reduce nest-dwelling parasites to test whether these treatments affect HSP60 level during the breeding season. Medicated females, but not controls, had a significant reduction of the intensity of infection by Haemoproteus spp. blood parasites. However, final intensity of infection did not differ significantly between groups, and we did not find an effect of medication on change in HSP60 level. Fumigation reduced the abundance of nest-dwelling parasites (mites, fleas and blowfly larvae) and engorged biting midges in nests. Females breeding in non-fumigated nests increased HSP60 levels during the season more than those breeding in fumigated nests. Furthermore, the change in HSP60 level was positively correlated with the abundance of biting midges. These results show how infections by nest ectoparasites during the breeding period can increase the level of HSPs and suggest that biting midges impose physiological costs on breeding female blue tits. Although plausible, the alternative that biting midges prefer to feed on more stressed birds is poorly supported by previous studies. 相似文献
494.
The mechanisms that confer honesty to multiple sexual signals of vertebrates remain less known. We suggest that vitamin E
in the scent (femoral secretions) and carotenoids in coloration of Lacerta lepida lizards might advertise quality because they are relevant in metabolism as major antioxidants and have a dietary origin.
Results showed that there may be similar trade-offs between immunity and both chemical and visual signaling, as males with
more vitamin E in secretions and those with more greenish, darker, and saturated carotenoid-dependent colorations had a higher
immune response. This suggests that only high-quality males can divert from metabolism and allocate enough vitamin E to secretions
and enough carotenoids to coloration. Therefore, information provided by visual and chemical signals is congruent. The use
of multiple sensory channels may allow signaling a male quality under different circumstances or reinforce the reliability
of the signal when both signals are perceived simultaneously. However, we also found that characteristics of carotenoid-dependent
coloration mirror the amounts of vitamin E in secretions. This might support that carotenoids, which are not true antioxidants
in the organism, would just reflect and “inform” on the actual contents of metabolic antioxidant vitamin E, which is part
of the true system that prevent oxidation. We suggest that the metabolic roles of vitamins might be the actual basis of honesty
of many sexual displays, and that carotenoid-based signals might be just the visible part of the whole system. 相似文献
495.
Ana Martín-González Jacek Wierzchos Juan C. Gutiérrez Jesús Alonso Carmen Ascaso 《Die Naturwissenschaften》2009,96(5):551-564
Microorganisms are the most ancient cells on this planet and they include key phyla for understanding cell evolution and Earth
history, but, unfortunately, their microbial records are scarce. Here, we present a critical review of fossilized prokaryotic
and eukaryotic microorganisms entrapped in Cretaceous ambers (but not exclusively from this geological period) obtained from
deposits worldwide. Microbiota in ambers are rather diverse and include bacteria, fungi, and protists. We comment on the most
important microbial records from the last 25 years, although it is not an exhaustive bibliographic compilation. The most frequently
reported eukaryotic microfossils are shells of amoebae and protists with a cell wall or a complex cortex. Likewise, diverse
dormant stages (palmeloid forms, resting cysts, spores, etc.) are abundant in ambers. Besides, viral and protist pathogens
have been identified inside insects entrapped in amber. The situation regarding filamentous bacteria and fungi is quite confusing
because in some cases, the same record was identified consecutively as a member of these phylogenetically distant groups.
To avoid these identification errors in the future, we propose to apply a more resolute microscopic and analytical method
in amber studies. Also, we discuss the most recent findings about ancient DNA repair and bacterial survival in remote substrates,
which support the real possibility of ancient DNA amplification and bacterial resuscitation from Cretaceous resins. 相似文献
496.
Many animals use chemical signals in sexual selection, but it is not clear how these sexual traits might have evolved to signal honestly male condition. It is possible that there is a trade-off between maintaining the immune system and the elaboration of ornaments. We experimentally challenged the immune system of male Iberian wall lizards, Podarcis hispanica, with a bacterial antigen (lipopolysaccharide), without pathogenic effects, to explore whether the immune activation affected chemical ornaments. Immune activation resulted in decreased proportions of a major chemical in femoral secretions (cholesta-5,7-dien-3-ol = provitamin D(3)) known to be selected in scent of males by females and which active form (vitamin D) has a variety of important effects on immune system function. This result suggests the existence of a potential trade-off between physiological regulation of the immune system and the allocation of essential nutrients (vitamins) to sexual chemical ornaments in male lizards. 相似文献
497.
Michelle P. Martín-Raugh Harrison J. Kell Jason G. Randall Cristina Anguiano-Carrasco Justin T. Banfi 《组织行为杂志》2023,44(1):132-156
What candidates say in an interview is important—but so is how they say it. We draw on dual-process theory to explain why interviewers rely on individuals' dynamic and static nonverbal cues to evaluate performance with quick, implicit inferences (System 1 processing). Yet, it remains unclear which cues most influence interviewers' judgments and whether moderators affecting interviewers' reliance on System 1 thinking (e.g., interview structure, modality, duration, and interviewee gender) impact the relationship between nonverbal cues and interview ratings. We performed the first meta-analysis to address these questions, integrating findings across 63 studies (N = 4868). The nonverbal cues demonstrating the strongest association with interview performance were professional appearance (ρ = .62), eye contact (ρ = .45), and head movement (ρ = .43). Moderator analyses highlight the persistent power of nonverbal cues, as the results were largely unaffected by interview structure, modality, or duration. Experimental design did play a role, as did interviewees' gender, with stronger effects for certain nonverbal cues (e.g., facial expressions and professional appearance) for women than men, conveying interviewers' reliance on gender-based stereotypes when judging their performance. Overall, these results suggest nonverbal cues and characteristics are an important influence on job applicants' success in employment interviews. 相似文献
498.
Hernan Mauricio Pérez Katherina B. Brokordt Gloria Martínez Helga Guderley 《Marine Biology》2009,156(8):1585-1593
The energetic cost of spawning and the endogenous factors that modulate spawning could modify escape response performance,
leading to a conflict between the requirements of two fundamental components of fitness: reproduction and survival. We examined
whether spawning changed force production during escape responses by the functionally hermaphroditic scallop, Argopecten purpuratus, and whether the response of smooth (tonic) and striated (phasic) muscles differed. Force production during escape responses
by mature scallops was compared before induction of spawning, during spawning and after completion of spawning. Maximum tonic
force and the area under the force curve (total force recorded) were diminished during gamete release, whereas phasic force
production (maximum and mean force) increased after spawning was completed. The number and frequency of phasic contractions
did not change during the spawning process, suggesting that spawning did not limit fuel availability for phasic contractions.
The decrease in tonic force during spawning and the increased phasic force production after spawning may reflect changes in
monoamine levels during gamete release. Whereas the spawning process modified force production during escape responses, the
changes would, if anything, enhance escape performance during an initial encounter between a scallop and a predatory sea star. 相似文献
499.
Sánchez-Peinado Mª del Mar González-López Jesús Martínez-Toledo Mª Victoria Pozo Clementina Rodelas Belén 《Environmental science and pollution research international》2010,17(3):779-790
Background, aim, and scope
Linear alkylbenzene sulfonate (LAS) is the most used anionic surfactant in a worldwide scale and is considered a high-priority pollutant. LAS is regarded as a readily biodegradable product under aerobic conditions in aqueous media and is mostly removed in wastewater treatment plants, but an important fraction (20–25%) is immobilized in sewage sludge and persists under anoxic conditions. Due to the application of the sludge as a fertilizer, LAS reaches agricultural soil, and therefore, microbial toxicity tests have been widely used to evaluate the influence of LAS on soil microbial ecology. However, molecular-based community-level analyses have been seldom applied in studies regarding the effects of LAS on natural or engineered systems, and, to our knowledge, there are no reports of their use for such appraisals in agricultural soil. In this study, a microcosm system is used to evaluate the effects of a commercial mixture of LAS on the community structure of Alphaproteobacteria, Actinobacteria, and Acidobacteria in an agricultural soil. 相似文献500.
María Pilar Martín Porrero Maria Paz Gallego-Iniesta García Jose Luis Espinosa Ruiz Araceli Tapia Valle Beatriz Cabañas Galán Maria Sagrario Salgado Muñoz 《Environmental science and pollution research international》2010,17(3):539-546