Pairs Of Cages Research Articles

Selective Encapsulation and Chiral Induction of C60 and C70 Fullerenes by Axially Chiral Porous Aromatic Cages

AbstractChiral induction has been an important topic in chemistry, not only for its relevance in understanding the mysterious phenomenon of spontaneous symmetry breaking in nature but also due to its critical implications in medicine and the chiral industry. The induced chirality of fullerenes by host–guest interactions has been rarely reported, mainly attributed to their chiral resistance from high symmetry and challenges in their accessibility. Herein, we report two new pairs of chiral porous aromatic cages (PAC), R‐PAC‐2, S‐PAC‐2 (with Br substituents) and R‐PAC‐3, S‐PAC‐3 (with CH3 substituents) enantiomers. PAC‐2, rather than PAC‐3, achieves fullerene encapsulation and selective binding of C70 over C60 in fullerene carbon soot. More significantly, the occurrence of chiral induction between R‐PAC‐2, S‐PAC‐2 and fullerenes is confirmed by single‐crystal X‐ray diffraction and the intense CD signal within the absorption region of fullerenes. DFT calculations reveal the contribution of electrostatic effects originating from face‐to‐face arene‐fullerene interactions dominate C70 selectivity and elucidate the substituent effect on fullerene encapsulation. The disturbance from the differential interactions between fullerene and surrounding chiral cages on the intrinsic highly symmetric electronic structure of fullerene could be the primary reason accounting for the induced chirality of fullerene.

Selective Encapsulation and Chiral Induction of C60 and C70 Fullerenes by Axially Chiral Porous Aromatic Cages.

Chiral induction has been an important topic in chemistry, not only for its relevance in understanding the mysterious phenomenon of spontaneous symmetry breaking in nature but also due to its critical implications in medicine and the chiral industry. The induced chirality of fullerenes by host-guest interactions has been rarely reported, mainly attributed to their chiral resistance from high symmetry and challenges in their accessibility. Herein, we report two new pairs of chiral porous aromatic cages (PAC), R-PAC-2, S-PAC-2 (with Br substituents) and R-PAC-3, S-PAC-3 (with CH3 substituents) enantiomers. PAC-2, rather than PAC-3, achieves fullerene encapsulation and selective binding of C70 over C60 in fullerene carbon soot. More significantly, the occurrence of chiral induction between R-PAC-2, S-PAC-2 and fullerenes is confirmed by single-crystal X-ray diffraction and the intense CD signal within the absorption region of fullerenes. DFT calculations reveal the contribution of electrostatic effects originating from face-to-face arene-fullerene interactions dominate C70 selectivity and elucidate the substituent effect on fullerene encapsulation. The disturbance from the differential interactions between fullerene and surrounding chiral cages on the intrinsic highly symmetric electronic structure of fullerene could be the primary reason accounting for the induced chirality of fullerene.

Tuning the spin-crossover properties of FeII4L6 cages via the interplay of coordination motif and linker modifications.

Despite the increasing number of spin-crossover FeII-based cages, the interplay between ligand modifications (e.g. coordination motif substituents and linker) is not well-understood in these multinuclear systems, limiting rational design. Here, we report a family of FeII4L6 spin-crossover cages based on 2,2'-pyridylbenzimidazoles where subtle ligand modifications lowered the spin crossover temperature in CD3CN by up to 186 K. Comparing pairs of cages, CH3 substituents on either the coordination motif or phenylene linker lowered the spin-crossover temperature by 48 K, 91 K or 186 K, attributed to electronic effects, steric effects and a combination of both, respectively. The understanding of the interplay between ligand modifications gained from this study could be harnessed on the path towards the improved rational design of spin-crossover cages.

The Surface Area to Volume Ratio Changes the Pharmacokinetic and Pharmacodynamic Parameters in the Subcutaneous Tissue Cage Model: As Illustrated by Carprofen in Sheep.

IntroductionPharmacokinetic and pharmacodynamic models can be powerful tools for predicting outcomes. Many models are based on repetitive sampling of the vascular space, due to the simplicity of obtaining samples. As many drugs do not exert their effect in the vasculature, models have been developed to sample tissues outside the bloodstream. Tissue cages are hollow devices implanted subcutaneously, or elsewhere, that are filled with fluid allowing repetitive sampling to occur. The physical dimensions of the cage, namely, the diffusible surface area to volume ratio, would be expected to change the rate of drug movement into and out of tissue cages.MethodsSeven sheep were implanted with five pairs of tissue cages, subcutaneously. Each pair of cages had a different length but a fixed diffusible surface area, so the surface area to volume ratio differed. Carrageenan was injected into half of the cages in each animal during one sampling period in a cross-over design. Samples from each cage and the bloodstream were obtained at 14-time points during two sampling periods. The concentration of carprofen was measured using LC–MS/MS and the results were modeled using nonlinear mixed-effects techniques. Prostaglandin metabolites were also measured and the change over time was analyzed using linear mixed effect modeling.ResultsThe presence of carrageenan within an animal changed the systemic pharmacokinetics of carprofen. The rate of drug movement into and out of the tissue cages varied with the surface area to volume ratio. The concentration time curve for prostaglandin metabolites changed with cage size.ConclusionThe surface area volume ratio of tissue cages will influence the calculated pharmacokinetic parameters and may affect calculated pharmacodynamics, thus, it is an important factor to consider when using tissue cage data for dosing regimes.

Contribuição de Melampus coffeus (Gastropoda, Ellobiidae) na degradação da serapilheira do médio estuário do rio Pacoti, Ceará, Brasil

A degradação da serapilheira no médio estuário do rio Pacoti foi estudada na presença e na ausência do gastrópode Melampus coffeus (Linnaeus, 1758), visando verificar a possível contribuição desse invertebrado na ciclagem da matéria orgânica dos manguezais. A densidade populacional de M. coffeus e a distribuição das folhas, em termos de biomassa úmida, biomassa seca e abundância, presentes na serapilheira do local, foram estimadas a partir de uma amostragem. Um experimento em campo foi realizado com amostras de coloração e biomassas similares de folhas de Rhizophora mangle (Rhizophoraceae) sem sinais de herbivoria, distribuídas igualmente entre 64 gaiolas. Em 32 destas foram colocados também exemplares de M. coffeus. Essas gaiolas foram distribuídas entre quatro pontos, sendo oito pares de gaiolas (controle e experimento) por ponto. Durante oito semanas, quatro pares de gaiolas foram coletados semanalmente. Após coletadas, os sinais de pastagem nas folhas causados por M. coffeus foram contados e as biomassas úmida e seca das amostras foram determinadas. Comparando controle e experimento, verificou-se que M. coffeus é capaz de contribuir na degradação da serapilheira na área estudada, porém, não foi verificada uma participação significativa desse gastrópode na degradação das folhas quando comparados experimento e controle ao longo do experimento.

Ten years of experience in the rearing of young freshwater pearl mussels (Margaritifera margaritifera)

Abstract In rearing experiments performed between 1997 and 2007, captive‐bred juvenile mussels were harvested shortly after they had dropped off their host fish, and exposed to different types of cages and holding systems. Survival of juveniles ranged from 0 to 92% in the first 4 months, but the mean annual mortality was high in all trials and with all systems. In three trials with sheet cages and sediment boxes exposed to mussel rivers from an initial number of 1440 to 1660 only one to eight mussels reached 4 years of age. With the exception of mussels kept in spring water no relationship between growth and survival was observed. Low survival rates were obtained in sheet cages exposed to very oligotrophic and highly eutrophic brook stretches. Several natural sites that were lacking recruitment in the wild nevertheless showed good results in the cages. All holding systems showed irregular variations in survival rates. Pairs of sheet cages showed no correlation between the survival of mussels in the adjacent cages. In contrast, growth rates were correlated. No relationship could be found between the growth or survival in sheet cages at different sites and brooks and the corresponding data on water chemistry. The systems tested for rearing young mussels involving a minimal time and effort in the natural habitat were not successful due to the elevated mortality rates of juveniles. The rearing success of young pearl mussels in cages in the water flow of mussel rivers gives no information about the suitability of these sites for natural reproduction. Thus, to find potential natural habitats for Margaritifera, it is imperative to survey water quality, sediments and habitat structure. Copyright © 2010 John Wiley & Sons, Ltd.

Functional identity versus species richness: herbivory resistance in plant communities.

The resistance of a plant community against herbivore attack may depend on plant species richness, with monocultures often much more severely affected than mixtures of plant species. Here, we used a plant–herbivore system to study the effects of selective herbivory on consumption resistance and recovery after herbivory in 81 experimental grassland plots. Communities were established from seed in 2002 and contained 1, 2, 4, 8, 16 or 60 plant species of 1, 2, 3 or 4 functional groups. In 2004, pairs of enclosure cages (1 m tall, 0.5 m diameter) were set up on all 81 plots. One randomly selected cage of each pair was stocked with 10 male and 10 female nymphs of the meadow grasshopper, Chorthippus parallelus. The grasshoppers fed for 2 months, and the vegetation was monitored over 1 year. Consumption resistance and recovery of vegetation were calculated as proportional changes in vegetation biomass. Overall, grasshopper herbivory averaged 6.8%. Herbivory resistance and recovery were influenced by plant functional group identity, but independent of plant species richness and number of functional groups. However, herbivory induced shifts in vegetation composition that depended on plant species richness. Grasshopper herbivory led to increases in herb cover at the expense of grasses. Herb cover increased more strongly in species-rich mixtures. We conclude that selective herbivory changes the functional composition of plant communities and that compositional changes due to selective herbivory depend on plant species richness.

The preferences of laying hens for perforated Astroturf over conventional wire as a dustbathing substrate in furnished cages

AbstractFollowing the 2012 European ban (1999/74/EC) of conventional battery cages, only furnished cages will be allowed for laying hens. However, even when furnished cages provide a pecking and scratching area most dustbathing occurs on the wire floor. This study aimed to investigate whether laying hens showed a preference for dustbathing on a covered wire floor rather than a conventional wire floor. Eight groups of 10 hens were housed in pairs of adjoining furnished cages. All hens were leg-ringed for individual identification. Each pair of cages consisted of one cage containing a wire floor covered with perforated Astroturf and a second cage containing a conventional wire floor, joined by a pophole through which hens had unrestricted access. Initial scan samples were taken to investigate the general behaviour of the hens on each floor type. Dustbathing was observed more frequently on Astroturf and no other behaviours were affected by the floor type. Scans were subsequently taken at 5 min intervals between 1130h and 1600h for 10 days, identifying the number of hens, and which individual hens, were dustbathing on each floor type. Data were analysed on a per cage basis, using the binomial sign test. A strong preference was found for dustbathing on Astroturf flooring that was apparent in all cages. Furthermore, the distribution of hens indicated this was not attributable to any overall preference for either floor type but was specific to periods when hens were dustbathing. This demonstrates that there is the potential to include Astroturf in the design of furnished cages, as a dustbathing substrate, in order to improve the welfare of laying hens.

Dietary dopamine causes ovary activation in queenless Apis mellifera workers

Groups of young honey bee workers were fed a diet containing dopamine while confined in small cages at 34 °C and 80% RH in absence of a queen for 8 to 13 days. The bees in eight pairs of cages, each pair containing an equal number of workers, received a pollen-rich diet supplemented with dopamine (10 µg/g of diet) (DOP groups), or not supplemented (controls). The rate of consumption of the diet was monitored continuously during the confinement period, after which the workers were dissected to assess follicle development in the ovaries. The results showed a significantly higher proportion (P = 0.004) of workers with activated ovaries in the DOP groups than in control groups. The number of bees surviving confinement was significantly higher in the control groups than in the DOP groups (P ≤ 0.01), possibly reflecting a deleterious effect of dopamine. The surviving bees from both groups consumed equivalent amounts of diet (P = 0.687), showing that ovary activation was not due to differential diet consumption. The results suggest a role of dopamine in the chain of events mediating changes in the reproductive status of orphan honey bee workers. Apis mellifera / honeybees / dopamine / ovary activation

The potential use of metallothionein in the clam Ruditapes decussatus as a biomarker of in situ metal exposure.

This work aimed to validate the relationship between metallothioneins (MTs) and metals (Cd, Cu and Zn) in field conditions. Specimens of the marine bivalve Ruditapes decussatus (Linné, 1758) from Gargour were transferred in two sites: Gargour and Sidi Mansour, both situated along the south-eastern coast of Tunisia. The bivalves were removed from pairs of cages at day 0 (date of transplantation), day 62 and day 132. Metals (Cd, Cu and Zn) and MTs were determined in the subcellular fractions of the digestive gland. In Gargour, metal and MT levels increased significantly after 62 days of transplantation. However, they showed modest and non-significant variations in Sidi Mansour. Zn was mainly associated with the insoluble fraction, whereas Cd and Cu percentages in the soluble and the insoluble fractions were equivalent. Simple correlation analysis showed a positive and significant relationship between MTs and each metal. If all metals were taken together, multiple correlations showed that MTs were significantly correlated with Cd and Zn, with an important coefficient for Cd, but no significant relationship was observed for Cu. Gel filtration chromatography showed that in the heat stable fraction, the only cytosolic SH rich compounds have an apparent low molecular mass (about 15 kDa), which could correspond to metallothioneins. In the digestive gland of R. decussatus MTs responded to moderate increases of metal contamination, without interference with other factors, and could be a promising biochemical indicator of metal exposure.

Synchronization of behavior among laying hens in battery cages

An investigation was carried out to assess synchronization of behavior among hens in battery cages. Two genetic stocks of pullets were raised in battery cages and housed as pairs in laying cages at 21 weeks of age (96 cages per stock). Hens of the same genetic stock occupied adjacent pairs of cages. The laying phase was divided into 28-day periods, and in Periods 1, 3, 5, 7, 9 and 11, time-lapse videorecordings were made of four pairs of cages per day over a sequence of 4 days. Each pair of cages was viewed by one camera, allowing simultaneous recording of the behavior of the hens in each cage. For each tape, 60 records of the behavior of each hen were obtained at equal intervals over 8 h. Behavioral dyads were defined as the concurrent behavioral states of a pair of hens at each point of observation. The frequency of occurrence of each dyad was compared with that expected given random manifestation of the behavior of hens relative to other hens. Cagemates showed a decided tendency to synchronize behavior. Six of eleven possible dyads of the same behavior occurred more than expected, many of them with a very high degree of statistical significance. Behavioral dyad differences from expected occurrence (DFEs) were consistently greater within cages than between cages for dyads of the same behavior, suggesting that social factors promoted synchronization of behavior in cages. Nonetheless, some degree of behavioral synchronization was apparent between cages as well. The potential effects of a desire to synchronize behavior are considered with regard to egg production and well-being in a battery cage environment.

Fossilization potential of the mud crab, Panopeus (brachyura: Xanthidae) and temporal variability in crustacean taphonomy

Studies of crustacean taphonomy in modern marine environments have suggested that disturbance (e.g., scavenging) of the decaying organisms and dissolution of their mineralized exoskeletons are major causes for failure of preservation. In order to test these ideas, a series of short term (< 3 weeks) and longer term (10 months) burial and recovery experiments of mud crabs, Panopeus sp., were carried out in Bermuda Freshly killed crabs were buried in pairs of cages that were designed to either exclude or admit large infaunal bioturbators and scavengers. The cages were exhumed and checked at intervals ranging from 1 day to 10 months. Of 22 crabs accessible to disturbance, all but 4 were completely or partly recovered. In addition, there was relatively little evidence of dissolution of exoskeletons. The good preservation observed during the course of these experiments may be attributed to low organic content and resulting low density of infauna, and to high pH of the carbonate burial environment which buffers the effects of acids produced by soft-tissue decay. These factors act to reduce infaunal scavenging and predation and to slow rates of dissolution. Organic matter content of sediment is one of many taphonomic parameters and processes that vary over a wide range of time scales. Preservation potential of crustacean exoskeleton also varies with the molt cycle, overall growth, physical and biological sediment disturbance, changes in sediment composition and organic content, and the evolution of scavengers and of the cuticle itself. Taphonomic processes are not invariant “filters”, but dynamic phenomena that change over ontogenetic, ecologic, and evolutionary time scales.

The effect of female proximity and social interaction on the menstrual cycle of crab-eating monkeys (Macaca fascicularis)

Twelve adult female crab-eating monkeys (Macaca fascicularis) were placed in six pairs of adjacent cages, allowing physical contact between members of these experimental pairs. Twelve additional females remained singly caged (no physical contact allowed) and served as six control “pairs.” In both experimental and control pairs, one member had a history of regular menstrual cycles, whereas the other tended to have cycles that were unusually long and/or irregular. Over a six-month period, menses and amount of vaginal secretion were recorded daily for all subjects, and the behavior of experimental pairs was sampled three times per week. During the course of the study, the irregular experimental subjects began to exhibit menstrual cycles of near normal length although there was no apparent trend to synchronize cycles. Irregular controls continued to show cycles that were abnormally long. Vaginal secretions tended to increase in all regularly cycling animals during days 9–15 (peak day 11) or reverse days 21–16 of the cycle, consistent with the estimated time of ovulation. Analysis of behavior indicated that irregularly cycling subjects inspected the genitalia of their regularly cycling cagemates at a significantly higher frequency than the converse (F=12.61,p<.005), particularly during the follicular phase (F=3.39,p<.07). These results suggest that close physical contact may serve to transmit chemical and/or hormonal cues that can normalize the menstrual cycle of crab-eating monkeys.

Influence of Detritus upon Colonization of Stream Invertebrates

The effect of introduced detritus on the colonization of cages by benthic invertebrates within the substrate of two stony streams was examined. Pairs of substrate-filled screen cages were buried to a depth of 10–20 cm within the substrate of Otter Creek, Sauk County, Wisconsin, and the East River, Gunnison County, Colorado. Variously conditioned coarse particular detritus was added to experimental cages, and no detritus to control cages. Total macroinvertebrates and total detritivores did not preferentially colonize cages enriched with detritus. Shredders showed higher colonization of experimental cages during fall trials using leaves conditioned by inoculation with microbial flora from Otter Creek. This observation reflects habitat choice by availability of high-quality food for shredders during the season of their greatest abundance. Shredders preferentially colonized detritus-enriched cages during combined summer trials in the East River and during summer trials when leaves were not microbially conditioned before use. Shredders in this high-altitude stream showed opportunistic colonization of introduced large-particle detritus where natural allochthonous matter was less readily available.Key words: detritus, streams, macrobenthos colonization, leaf conditioning, shredders, experimental manipulation

Inundative Releases ofAphidius smithiAgainstAcyrthosiphon pisum

In 1965, 1966, 1967, and 1969, field tests were conducted in the Walla Walla, Washington, area with an estimated 100–300 million cage-reared Aphidius smithi Sharma & Subba Rao (inundative releases) in an effort to control populations of the pea aphid, Acyrthosiphon pisum (Harris) on alfalfa. The objective was to prevent migration of the aphids from their overwintering site in the alfalfa to about 100,000 acres of peas grown for processing. Parasites from 14 pairs of cages effectively controlled pea aphids on 2500 acres of seed alfalfa in 1967, until the area was sprayed for Lygus spp. When parasitic, natural, and chemical control systems were compared in 1967, averages of 13, 56, and 82 aphids/100 sweeps, respectively, were obtained. The population in the field exposed to chemical control oscillated wildly, but the population in the field exposed to parasitic control remained uniformly low. Use of aphid parasites in this manner appears impractical at present because of production and distribution requirements.

A test of sexual isolation in Drosophila.

1. A test is described for the development of sexual isolation between a wild and a derived population of D. melanogaster adapted to a new diet, containing EDTA. Other experiments had shown that adaptation to the new diet involved genetic changes in all chromosomes. Also fitness was reversed on the alternative diets under crowded competitive conditions.2. In three replicated trials flies from each population were used to establish paired cage populations, supplied with the medium to which each was adapted, and the pairs of cages were joined to allow restricted immigration between them. The experiment was run for about twenty-five generations.3. After fifteen and twenty-five generations, flies were collected from each cage to provide eggs which were cultured on the alternative diets to determine how far the members of pairs of populations differed from each other and from the foundation population. There were striking differences between the sub-populations and the parent populations, attributable to immigration between the former. Judged by the differences in performance between the sub-populations, genetic differences persisted but these were minor compared with the differences between the parent populations.4. Tests of preferential mating on the part of flies from paired sub-populations were entirely negative.5. Fourteen generations of selection for positive assortative mating failed to provide evidence of sexual isolation between the two basic populations, adapted to different diets.6. From these and other experiments it is inferred that sympatric divergence is improbable in a species like D. melanogaster.