Study on the Adsorption of Cr3+ by Peanut Shell: Adsorption Kinetics,Thermodynamics, and Isotherm Properties

The pollution of heavy metals in soil to the environment is becoming more and more serious, resulting in the reduction of crop production and the occurrence of medical accidents. In order to remove heavy metal ions from soil and reduce the harm of heavy metals to the environment, modified peanut shell was used to adsorb Cr³⁺ in this article. The effects of different adsorption conditions on the adsorption rate and adsorption capacity of Cr³⁺ on ZnCl₂ modified peanut shell were studied, the best adsorption conditions were explored, and the relationship of kinetics, thermodynamics and adsorption isotherm properties of adsorption process were explored. The results showed that the optimum adsorption pH value, dosage, initial concentration, adsorption temperature and contact time of ZnCl₂ modified peanut shell were 2.5, 2.5 g/L, 75 μg/mL, 25 °C and 40 min, respectively. The prepared materials were characterized and analyzed by scanning electron microscope (SEM) and X-ray diffraction (XRD) analyzer. It was concluded that the modified peanut shell had a good adsorption capacity to Cr³⁺. The kinetic study showed that the adsorption process of Cr³⁺ on peanut shell modified by zinc chloride was in accordance with the quasi-second-order kinetic model. The adsorption process belonged to exothermic reaction and belonged to spontaneous reaction process. In summary, it is proved that zinc chloride modified peanut shell can efficiently adsorb Cr³⁺, which can be used for the treatment of heavy metal wastes in industry, which is beneficial to environmental protection and avoid heavy metal pollution.     

A New Method for Finding Small Vertebrate Fossils: Ultraviolet Light At Night

Vertebrate fossils from many different formations fluoresce when exposed to ultraviolet (UV) light. In this paper field observations and controlled experiments in the Chadron Formation (White River Group, late Eocene) of Wyoming are used to assess the utility of searching for fossils at night using ultraviolet light. The results indicate that, especially for very small teeth and egg-shell fragments, searching with ultraviolet light at night can result in significantly more specimens than searching during daylight hours. This method has the potential to increase sample sizes for small vertebrate specimens that are often overlooked when using standard collecting techniques.     

Chemico-structure of the organophosphatic shells of siphonotretide brachiopods

The organophosphatic shell of siphonotretide brachiopods is stratiform with orthodoxly secreted primary and secondary layers. The dominant apatitic constituents of the secondary layer are prismatic laths and rods arranged in monolayers (occasionally in cross-bladed successions), normally recrystallized as platy laminae. Sporadically distributed, interlaminar, lenticular chambers, containing apatitic meshes of laths and aggregates of plates and spherulites, probably represent degraded, localized exudations of glycosaminoglycans (GAGs) with dispersed apatite.
The shells of Helmersenia and Gorchakovia are perforated by canals with external depressions (antechambers) that possibly contained chitinous tubercles in vivo . The immature shell of Siphonotreta and most other siphonotretids is similarly perforated and pitted; but the mature part bears recumbent, rheomorphic, hollow spines that grew forward out of pits. Internally, spines pierce the shell as independent structures to terminate as pillars in GAGs chambers. Spines and pillars were probably secreted by collectives of specialized cells (acanthoblasts) within the mantle.
The shell of the oldest siphonotretide, Schizambon , is imperforate but the ventral valve has a pedicle foramen that lies forward of the posterior margin of the juvenile valve. This relationship characterizes all siphonotretides, suggesting that the pedicle, in vivo , originated within the ventral outer epithelium and not from the posterior body wall as in lingulides.     

The cap-shaped Cambrian fossil Maikhanella and the relationship between coeloscleritophorans and molluscs

The recent discovery of large shells. growing by accretion, in the scleritome of the coeloscleritophoran Ha lkieria Poulsen, 1967, prompts the reconsideration of a number of cap-shaped shells in the Lower Cambrian. The scaly shells of Maikhanella Zhegallo, 1982. from Mongolia provide a good starting point, mce they occur together with spicules of siphogonuchitid type and appear to be composed of merged spicules. The shells are phosphatired and consist of two main elements: spicules, typically filled with phosphate. and an intermediate matrix. The associated loose spicules belong to forms that have served as the basis for erection of the genera Siphogonuchites Qian. 1977, and Lopochites Qian, 1977. Maikhanella is prohdbly a junior synonym of one or both of the latter two genera, but taxonomic revision is suspended until the type material of these siphogonuchitid genera has been restudied. and all three genera are left as sciotaxa. Various cap-shaped shells and plates in the Chinese Meishucunian are reinterpreted as shells belonging to coeloscleritophornn scleritoines. Maikhanella shells were formed through the embedding of spicules in secondary calcareous shell zubstance. The skeletogenesis has several similarities with that of molluscs, and together with the polyplacophoran-like features of the Halkieria scleritome this forces a reconsideration of the phylogenetic relationships between coeloscleritophorans and molluscs     

Shell-banding polymorphism of the land snail Xeropicta vestalis along the coastal plain of Israel

Along the coastal plain of Israel, shell darkness of the polymorphic land snail Xeropicta vestalis is positively related to the extent of perennial vegetation. It is not related to rain, temperature, geographic position or darkness of the ground.
White shells reflect more radiation than dark ones do, and therefore in Israel's coastal plain, where solar radiation is very strong, they are favoured. Perennial vegetation, where it occurs, shields the snails from the sun by absorbing radiation, so that snails amongst them can afford to be darker, and thus more cryptic. Hence, the more perennial vegetation in the habitat, the darker the shells.
Also during the Pleistocene, when temperatures were 5–10°C lower than today, the shells of the coastal plain were as pale as recent ones are. The distribution of a snail-predator, Gerbillus allenbyi , which is restricted to sandy biotopes where perennial bushes occur, and which was absent from Israel during the Pleistocene, could perhaps explain the distribution of X. vestalis morphs, both today and in the past.     

Effets à long terme de 4 détersifs chez le pulmoné d'eau douce Lymnaea stagnalis L.: Intoxication des adultes

Detergents added to the rearing water of the molluscLymnaea induce a sharp mortality of all the animals of each experimental group after a variable delay, depending upon the nature of the detergent and its concentration.No important perturbation of the shell growth is noted with the cationic detergent; conversely a light decrease is observed with the anionic detergents and a very severe effect is induced by a commercial washing mixture.The fecundity is always reduced by the detergents: the number of egg-masses per snail and the number of eggs per mass are diversely changed according to the products.In many cases the egg fertility is decreased and the duration of embryogenesis is increased. For each detergent the reduction of the biological yield ofLymnaea is calculated and the curves drawn allow to classify these detergents according to their chemical nature: among the anionic detergents, A has a low toxicity, B and P are characterized by higher toxicities and the cationic detergent is strongly toxic.

     

Ascaris sp.: water loss during desiccation of embryonating eggs

The ability of embryonating eggs of Ascaris lumbricoides to avoid desiccation by reducing the loss of water through the egg shell was investigated. When exposed to desiccation the eggs lost water at a rate dependent upon the relative humidity and ambient temperature, eventually resulting in the collapse of the eggs and the death of the enclosed embryo. The eggs are small with a large surface to volume ratio. A low permeability to gaseous exchange thus restricts water loss while still ensuring an adequate supply of oxygen for embryonic development. Relative humidity did not appear to affect the rate of development. In eggs exposed to desiccation at various constant temperatures, the rate of water loss increased as an exponential function of increasing temperature. When eggs were exposed to various temperatures before exposure to desiccation at 22 C, the rate of water loss increased as a function of increasing pretreatment temperature. After exposure to 63–65 C, the ability of the egg shell to slow down the loss of water was destroyed. These phenomena suggest that there is not a simple “critical” or “transition” temperature, but a gradual melting of the complex mixture of components forming the lipid layer.     

Curcumin-loaded cockle shell-derived calcium carbonate nanoparticles: A novel strategy for the treatment of lead-induced hepato-renal toxicity in rats

Lead (Pb) toxicity affects the hepatic and renal systems resulting to homeostasis imbalance. Curcumin is a strong antioxidant but has restrained clinical applications due to its poor bioavailability. Nanomedicine showed promising potentials in drug delivery and has brought forth the use of cockle shell-derived aragonite calcium carbonate nanoparticles (CSCaCO₃NP) to enhance the effectiveness and targeted delivery of curcumin (Cur). Thus, this study aimed at evaluating the therapeutic effect of curcumin-loaded CSCaCO₃NP (Cur- CSCaCO₃NP) on lead-induced hepato-renal toxicity in rats. Thirty-six male adults Sprague-Dawley rats were randomly assigned into five groups. All groups contained six rats each except for group A, which contained 12 rats. All rats apart from the rats in group A (control) were orally administered a flat dose of 50 mg/kg of lead for four weeks. Six rats from group A and B were euthanized after four weeks of lead induction. Oral administration of curcumin (100 mg/kg) for group C and Cur-CSCaCO₃NP (50 and 100 mg/kg) for groups D and E respectively, commenced immediately after 4 weeks of lead induction which lasted for 4 weeks. All rats were euthanized at the 8th week of the experiment. Further, biochemical, histological and hematological analysis were performed. The findings revealed a biochemical, hematological and histological changes in lead-induced rats. However, treatments with the Cur-CSCaCO₃NP and free curcumin reversed the aforementioned changes. Although, Cur-CSCaCO₃NP presented better therapeutic effects on lead-induced toxicity in rats when compared to free curcumin as there was significant improvements in hematological, biochemical and histological changes which is parallel with attenuation of oxidative stress. The findings of the current study hold great prospects for Cur-CSCaCO₃NP as a novel approach for effective oral treatment of lead-induced hepato-renal impairments.