Oreganum Stalks as a New Biosorbent to Remove Textile Dyes from Aqueous Solutions

In the present study, Oreganum onites L. stalks in natural and chemically modified with HNO³ and H³PO⁴ used as adsorbent for removal of both acidic and basic dyes from waters. The adsorption was studied as a function of pH and contact time by batch method. All tested biosorbents were characterized by FT‐IR, scanning electron microscopy, and measuring the pH dependence of the zeta potential. The adsorption isotherms were fitted to Langmuir isotherm. The maximum adsorption capacity of dyes was 280.73 mg g^?1 for Basic Red 18, 147.06 mg g^?1 for methylene blue and 112.36 for Acid Red 111, which is comparable to that of other lignocellulosic materials. The modification process was considerably increased the biosorption capacity of lignocellulosic material, resulting in a 56–63% increase in the biosorption capacity of basic dyes and a 125% increase in the biosorption capacity of acidic dye. The present study illustrated that the most effective factors in the adsorption of basic dye were surface charge and acidic groups on lignocellulosic biosorbents, while non‐electrostatic forces as well as electrostatic forces were also effective in the adsorption of acidic dye. In conclusion, Oreganum stalks can be considered as a very prospective adsorbent for the removal of tested basic and acidic dyes.     

The microbial community in the layered sediments at Laguna Figueroa,Baja California,Mexico: Does it have Precambrian analogues?

In the hypersaline lagoon at Laguna Figueroa vertically stratified diverse communities of microorganisms thrive. The modern sediments of Baja California at Laguna Figueroa contain cyanobacterial communities and sedimentary structures produced by these blue greens that have already been studied by Horodyski and his colleagues. This paper provides an introduction to the complex microbial communities, primarily those that underlie the laminated Microcoleus mats. They are composed of anaerobic photosynthetic and heterotrophic bacteria.The following genera of cyanobacteria at least are components of these mat communities: Lyngbya, Microcoleus, Entophysalis, Phormidium, Pseudoanabaena, Anabaena and Schizothrix. Among the photosynthetic bacteria several species of Thiocapsa-like microbes formed major surface components of certain mats and scums; rhodospirilli, rhodopseudomonads, chromatis and others were seen.The following nonphotosynthetic bacteria were identified: Nocardia sp., three types of spirilli, two types of Spirochaeta sp., two types of Desulfovibria sp., a new strain of red Beneckea and four distinctive unidentified coccoid and filamentous bacteria. Reasons are given for believing several of the species are new to science and that the microbial diversity is far greater than the approximately twenty species reported here. Eukaryotes are extremely rare. Only one species of animal, a herpachtechoid copepod, was ever seen in the 8-km long microbial communities of the hypersaline basin. Dunaliella salina, a chlorophyte and Aspergillus sydowi, an ascomycetous fungus were the only eukaryotes that were observed to be regular components of mat communities. Ciliates, amoebae (including a chrysarchnion-like microbe) and diatom tests, mostly empty, were the only other eukaryotes observed. Attempts to enrich for eukaryotic microorganisms were not successful whereas attempts to enrich for bacteria, especially anaerobes led to such a profusion of forms that to continue detailed study of them was beyond our means. Unidentified small rods and cocci constituted the largest fraction of individuals in the subsurface community. The microbes isolated from mats are adapted for alternating dry and wet conditions as well as high concentrations of salt and low concentrations of oxygen.     

A high-resolution Fabry-Pérot spectrometer for emission line studies in planetary nebulae and other extended astronomical objects

We describe here a scanning piezo-electric Fabry-Pérot spectrometer operating in the photoncounting mode whose plate spacing and parallelism are maintained by a servo-controlled system, ensuring high accuracy, for the study of emission lines from extended astronomical objects in the spectral range 4500–7000 Å. Details of the optical set-up and the Data Acquisition System (DAS) are described. Its performance at the Cassegrain focus of the 1 m telescope at Kavalur is discussed. Some line profiles on planetary nebulae studied with the above spectrometer are also presented.     

Study of precipitation chemistry over an industrial city

The growing trend of industrialization has marked impact on the atmospheric chemistry around the globe. Such impacts are also predicted for developing countries like India. Acid precipitation due to secondary pollutants is one of them. The present investigation was conducted with an aim of studying the precipitation chemistry over Asansol city, India during the monsoon season. The rain water samples, collected on event basis during the period of June to September 2006, were analyzed for HCO₃ ^?, Cl^?, SO₄ ^2?, NO₃ ^?, NH₄ ⁺, K⁺, Na⁺, Mg²⁺, Ca²⁺ and pH using standard procedures. The study revealed that the precipitation was alkaline in nature with mean pH value of 6.08. Dominant anion in rain water samples was HCO₃ ^? (36 %), whereas Ca²⁺ was highest among the cations (53 %). The observed acidic events, based on pH value, were only 17 %, indicating the alkaline components effectively neutralize rain water over the area. This was also supported by the total alkaline to acid ion ration of 1.05. The ratio of (NO₃-^?+Cl^?) and SO₄ ^2? was >1, indicating that acidic properties were influenced by HNO₃ and HCl. In the ratio between (Ca²++NH₄ ⁺) and (NO₃ ^?+SO₄ ^2?), values >1 were obtained, indicating significant alkaline influence, which effectively prevented acid depositions in the area.     

Mineral chemistry of Carlsberg Ridge basalts at 3°35′–3°41′N

Mineral chemical analyses of transitional basalts from the Carlsberg Ridge show plagioclase (An ~ 87 mole %), phenocrysts, and microphenocrysts have a K₂O depletion as compared to the laths (An ~ 79 mole %). Olivine (Fo ~ 91 mole %) are few and rarely zoned. The composition of plagioclase and olivine indicate low pressure equilibrium crystallization. The basalts were probably derived through fractional crystallization at shallow depths under low partial melting conditions. Morphology of plagioclase phenocrysts and bulk rock chemistry suggest magma mixing and fractional crystallization for the origin of these basalts. (Detailed chemical analyses can be obtained from the authors.)     

Bayesian dynamic modeling for large space-time datasets using Gaussian predictive processes

In this paper, we extend the applicability of a previously proposed class of dynamic space-time models by enabling them to accommodate large datasets. We focus on the common setting where space is viewed as continuous but time is taken to be discrete. Scalability is achieved by using a low-rank predictive process to reduce the dimensionality of the data and ease the computational burden of estimating the spatio-temporal process of interest. The proposed models are illustrated using weather station data collected over the northeastern United States between 2000 and 2005. Here our interest is to use readily available predictors, association among measurements at a given station, as well as dependence across space and time to improve prediction for incomplete station records and locations where station data does not exist.     

A preliminary magnetic study of soil samples from west-central Minnesota

Various rock magnetic techniques were applied to characterize magnetically the samples of a soil profile taken from west-central Minnesota. There is a marked change in magnetic properties as a function of depth in the core. X-ray analysis and Curie temperature measurements carried out on the magnetic fractions indicate that magnetite is the dominant iron oxide in both the top soil and the subsoil. The intensity of anhysteretic remanent magnetization (ARM) decreases sharply as the depth increases. In contrast, the stability of ARM was found to be higher for the subsoil. The surface soil sample was capable of acquiring a significant amount of viscous remanent magnetization (VRM). The VRM acquisition coefficient (S_a) of the subsoil (S_{a= 3.18 × 10^?6emu g^?1, 3.18 × 10^?6A m² kg^?1}) was about ten times weaker than that of the top soil sample (S_a = 3.868 × 10^{?7emu g?1, 3.868 × 10?7A m2 kg?1}). The magnetic domain state indicator, the ratio of coercivity of remanence to coercive force, H_cr/H_c, was 1.5 and 3.85 for the top soil and subsoil, respectively. It appears that the observed variations in magnetic properties down the present soil core is due only to a difference in grain size. We conclude that the magnetic grains in surface soil samples were more single-domain (SD) like whereas the magnetite grains in the subsoil samples were more likely in pseudo-single-domain (PSD) or small multidomain (MD) range. The observed lower stability for the surface soil samples is attributed to the presence of superparamagnetic grains whose presence was confirmed by transmission electron micrographs.     

A study on the Wilkins and Forchheimer equations used in coarse granular media flow

Complexity of the pore geometry and the random nature of flow velocity make it difficult to predict and represent post laminar flow through porous media. Present study experimentally investigates the applicability of Forchheimer and Wilkins equations for post laminar flow where Darcy’s law is invalid due to predominant inertial effect. It is observed that both porosity and media size have significant influence over the coefficients of the Forchheimer coefficients. To incorporate the effect of porosity and media size, behaviour of Forchheimer coefficients are investigated with hydraulic radius as characteristic length. An inversely proportional variation trend is found for all the present and earlier reported data. A new empirical relation between Forchheimer coefficients and hydraulic radius is obtained which can be universally applicable for all media size and porosity. Coefficients of the Wilkins equation are found to be non-deviating for different hydraulic radius in the present study and in the reported literature validating its applicability in predicting the non laminar flow through porous media. Further the Wilkins equation is modified after incorporating the correction factors for better applicability on the field.