Synthesis of Calix(aza)crown and its Oligomeric Analogue for the Extraction of Selected Metal Cations and Dichromate Anions

The present study reports the synthesis of a novel ionophore, calix[4]azacrown ( 5 ) bearing two amino groups at the lower rim along with its oligomeric analogue ( 6 ). The liquid‐liquid extraction properties of these compounds towards selected metal cations and dichromate anions have been evaluated. It is observed that ( 5 ) and ( 6 ) are good extractants for the selected metal cations. However, in the case of dichromate anion, only species ( 5 ) shows remarkable extraction properties at low pH, whereas species ( 6 ) shows poor extraction behavior. The results have importance especially in wastewater treatment to obtain environmentally safe industrial effluent and they should also assist supramolecular chemists in designing and synthesizing more sophisticated host molecules for the removal of toxic pollutants.     

Deliniation of Weathering in the Çatalca Granite Quarry with the Very Low Frequency (VLF) Electromagnetic Method

Faulting and weathering can endanger quarry operations by decreasing the total reserve, quarry’s useful life and production value. We investigated weathering and faulting problems in the Çatalca granite quarry at Istanbul in Turkey, using the Very Low Frequency (VLF) method. VLF method is an electromagnetic method which is very successful in locating vertical discontinuities such as faults and fracture zones. This method measures the apparent resistivity of the rocks in the region, besides the electromagnetic parameters such as tilt angle and ellipcity. Apparent resistivity is a very sensitive parameter to water presence inside the pores and fractures of the rocks. This feature enables the VLF method to map the boundaries between the fresh and cracked granite and altered zones in the quarry. In this work we mapped the faults and weathered zones within the granite in Çatalca quarry and found a high resistivity zone at the central part of the survey area which may be suitable for production. This study also shows the efficiency of the VLF method in understanding the structural and textural features of a quarry and estimating zones with high quality rocks for production planning.     

Trend assessment of annual instantaneous maximum flows in Turkey

A comprehensive evaluation of trends in annual instantaneous maximum flows (AIMF) from 153 gauge stations located in 26 river basins in Turkey is presented. Two traditional non-parametric trend tests, the Mann-Kendall (MK) and Spearman’s rho (SR), are used to quantify the significance of trends, while Sen’s slope method is applied to determine the magnitude of trends. The traditional tests indicate that the AIMF records of 57 stations showed statistically decreasing trends, while those of six stations showed an increasing trend. Sen’s trend method, which provides more detailed assessment of the trends in different clusters (low, medium and high), was applied to the AIMF series and the results were compared with traditional tests. Sen’s trend method indicated that all flow clusters at nine stations have increasing or decreasing trends, although no significant trend was detected by the MK and SR tests.     

IRG2018: A regional geoid model in Iran using Least Squares Collocation

Studia Geophysica et Geodaetica - The aim of this study is to determine an accurate geoid model for Iran based on the Least Squares Collocation method in the framework of the Remove — Compute...     

Experimental measurements of seismic velocities on core samples and their dependence on mineralogy and stress; Witwatersrand Basin (South Africa)

Physical property measurements were integrated with mineralogical analyses to better understand the nature of the seismic reflectivity of the deepest (>3.5 km depth) gold ore body (Carbon Leader Reef). The CLR lies at depths between 3.5 km and 4.5 km below the surface. Over 50 drill-core samples were selected for geochemical analyses, density and seismic velocity measurements. Ultrasonic measurements were conducted at ambient and elevated stresses, using transducers operating at 0.5 MHz. The study reveals that P-wave velocities generally increase with increasing bulk density. The CLR conglomerate, the gold-bearing reef, has slightly higher P-wave velocity (～5070–5468 m/s) and density values (～2.78 g/cm³) amongst the quartzitic units, possibly due to its massive pyrite content. The quartzite hangingwall and footwall rocks to the CLR exhibit similar P-wave velocity (～5028–5480 and ～4777–5211 m/s, respectively) and density values (～2.68 and 2.66 g/cm³, respectively). The reflection coefficients calculated at the interface between the CLR conglomerate and its hangingwall and footwall units range between ～0.02 and 0.05 which is below the required minimum reflection coefficient value of 0.06 to produce a strong reflection between two lithological boundaries. This suggests that seismic reflection methods might not be able to directly image the CLR, as observed from its poor reflectivity in the 3D seismic data. Samples were also subjected to stresses of up to 65 MPa to simulate in situ-like conditions and to investigate the dependence of seismic velocities on applied stresses. P-wave velocities increase with progressive loading, but at different rates in shale and quartzite rocks as a result of the presence of micro-defects.     

Thermal sensation of people performing recreational activities in shadowy environment: a case study from Turkey

The objective of this study is to determine human thermal comfort conditions in the recreational areas of the city of Erzurum using an 18-year data set of the five warmest months of the year obtained from the meteorological station established in the rural area of the city at 1400 local time and discussing the applicability of a new approach that climatic or bioclimatic comfort conditions under some tree species may be comparable to those under some cloudiness categories. It was found by concluding that the effects of cloudiness and shadows of selected tree species may not be the same on thermal comfort conditions that people can experience cold stress under dense shadows especially in spring and autumn months and heat stress under weak shadows in summer months in recreational areas. It was suggested that, in order to prevent people in recreational areas from heat and cold stress, great care must be taken in the plantation of recreational areas and deciduous tree species, rather than coniferous, which can foliate late, should be used.     

Geochemistry of mafic microgranular enclaves in the Tamdere Quartz Monzonite, south of Dereli/Giresun, Eastern Pontides, Turkey

Rocks of the Late Cretaceous Tamdere Quartz Monzonite, constituting a part of the Eastern Pontide plutonism, include mafic microgranular enclaves (MMEs) ranging from spheroidal to ellipsoidal in shape, and from a few centimeters to decimeters in size. The MMEs are composed of diorite, monzodiorite and quartz diorite, whereas the felsic host rocks comprise mainly quartz monzonite, granodiorite and rarely monzogranite on the basis of both mineralogical and chemical compositions. The common texture of felsic host rocks is equigranular. MMEs are characterized by a microgranular texture and also reveal some special types of microscopic textures, e.g. antirapakivi, poikilitic K-feldspar, small lath-shaped plagioclase in large plagioclase, blade-shaped biotite, acicular apatite, spike zones in plagioclase and spongy-cellular plagioclase textures.

The distribution of major, trace and RE elements apparently reflect exchange between the MMEs and the felsic host rocks mainly due to thermal, mechanical and chemical interactions between coeval felsic host magma and mafic magma. The most evident major element transfer from felsic host magma to mafic magma blob is that of alkalis such as Na and K. LILEs such as Rb, Sr, Ba and some HFSEs such as Nb, Y, Zr and Th have been migrated from felsic host magma to MMEs. Apart from these major and trace elements, the other element transfer from felsic host magma to mafic one concerns REE contents. Such a transfer of REEs has evidently increased the LREE contents of MMEs. Enrichments in alkalis, LILEs, HFSEs and REEs could have been achieved by diffusional processes during the solidification of magma sources. The felsic and mafic magma sources behave as Newtonian and visco-plastic materials. In such an interaction, small MMEs behave as a closed system due to immediate rapid cooling, whereas the bigger MMEs suffer greater diffusion from the Newtonian felsic host magma due to slow cooling.     

Neotectonics of East Anatolian Plateau (Turkey) and Lesser Caucasus: implication for transition from thrusting to strike-slip faulting

Abstract

The east Anatolian plateau and the Lesser Caucasus are characterised and shaped by three major structures: (1) NW- and NE-trending dextral to sinistral active strike-slip faults, (2) N-S to NNW-trending fissures and /or Plio-Quatemary volcanoes, and (3) a 5-km thick, undeformed Plio-Quatemary continental volcanosedimentary sequence accumulated in various strike-slip basins. In contrast to the situation in the east Anatolian plateau and the Lesser Caucasus, the Transcaucasus and the Great Caucasus are characterised by WNW-trending active thrust to reverse faults, folds, and 6-km thick, undeformed (except for the fault-bounded basin margins) continuous Oligocene-Quaternary molassic sequence accumulated in actively developing ramp basins. Hence, the neotectonic regime in the Great Caucasus and the Transcaucasus is compressional-contractional, and Oligocene-Quaternary in age; whereas it is compressional-extensional, and Plio-Quatemary in age in the east Anatolian plateau and the Lesser Caucasus.

Middle and Upper Miocene volcano-sedimentary sequences are folded and thrust-to-reverse-faulted as a result of compressional- contractional tectonic regime accompanied by mostly calc-alkaline volcanic activity, whereas Middle Pliocene-Quaternary sequences, which rest with angular unconformity on the pre-Middle Pliocene rocks, are nearly flat-lying and dominated by strike-slip faulting accompanied by mostly alkali volcanic activity implying an inversion in tectonic regime. The strike-slip faults cut and displace dykes, reverse to thrust faults and fold axes of Late Miocene age up to maximum 7 km: hence these faults are younger than Late Miocene, i.e., these formed after Late Miocene. Therefore, the time period between late Serravalian (~ 12 Ma) continent-continent collision of Arabian and Eurasian plates and the late Early Pliocene inversion in both the tectonic regime, basin type and deformation pattern (from folding and thrusting to strike-slip faulting) is here termed as the Transitional period.

Orientation patterns of various neotectonic structures and focal mechanism solutions of recent earthquakes that occurred in the east Anatolian plateau and the Caucasus fit well with the N-S directed intracontinental convergence between the Arabian plate in the south and the Eurasian plate in the north lasting since Late Miocene or Early Pliocene in places. © 2001 Éditions scientifiques et médicales Elsevier SAS     

Novel Calix[4]arene‐based Amberlite XAD‐4 Modified Resin for As(III) Removal from Water

The present article describes As(III) sorption behavior of novel calix[4]arene appended TS‐4 resin. The sorption ability of TS‐4 resin has been evaluated at wide range of pH, i.e., pH 2–14. The maximum As(III) sorption efficiency (95%) was achieved at pH 2, which shows that the TS‐4 resin possesses greater affinity for As(III) at this pH. Column sorption mechanism was evaluated through various operating parameters, i.e., change in concentration, flow rate, bed heights, and pH. The experimental data were also tested against bed depth service time model and from the results; it has been observed that the data is in close agreement with the theoretically calculated values. Thus, from the data it has been revealed that TS‐4 resin has maximum column efficiency of 0.13 mmol g^?1. Application of TS‐4 to real samples indicates a slight decrease (2–3%) in extraction efficiency of TS‐4 because of high concentration of total dissolved salts. Thermal behavior was tested by differential scanning calorimetry and it has been observed that TS‐4 resin is stable up to 160°C. TS‐4 resin was found to be regenerable and best regeneration was achieved by using 4% solution of NaOH. It can be deduced from the study that the resin will find its applicability in small as well as industrial scale water purification plants.