Investigation of pilot scale manufacturing of polysulfone (PSf) membranes by wet phase inversion method

Membranes are used as a support layer for the fabrication of thin film composite membranes. Sup- port layer properties can affect many performance parameters of TFC membranes such as flux, rejection, morphology and stability against pressure. Although studies in lab scale fabrication exist, investigation the pilot scale polysulfone membrane fabrication has not been done. In this study, opti- mization of polysulfone support membranes fabrication was conducted in pilot scale. Coagulation bath temperature; casting speed and solution content were selected as main parameters for the opti- mization. Membrane surface properties were investigated in details with SEM and pore size dis- tribution. Membrane performance were determined with permeability experiments. Differences in pilot scale and lab scale membrane manufacturing were observed and compared with literature. On the contrary to literature it was found that, coagulation bath temperature has exact opposite effect in pilot scale membrane formation compared to lab scale studies. 10°C drop (from 25°C to 15°C) in coagulation bath temperature decreased mean pore size of membranes from 27 nm to 8 nm and per- meability from 464 l/m2h to 100 l/m2h while everything else was kept constant

Geochemistry of fluid inclusions in travertines from Western and Northern Turkey: inferences on the role of active faults in fluids circulation

The understanding of the relationship between the geochemistry of fluids circulating during travertine deposition and the presence of active faults is crucial for evaluating the seismogenetic potential of an area. Here we investigate travertines from Pamukkale and Reşadiye (Turkey), sited in seismic regions and next to thermal springs. These travertines formed ~24,500–50,000 (Pamukkale) and ~240–14,600 years (Reşadiye) BP. We characterize fluid inclusions (FIs) and studied concentration of H2O, CO2, O2 + N2, and 3He, 4He, 20Ne, and 40Ar, and bulk composition (trace elements and δ13C‐δ18O). FIs from both localities are mainly primary with low salinity and homogenization temperature around 136–140 °C. H2O is the major component followed by CO2, with the highest gas content measured in Pamukkale travertines. Concentrations of Ne‐Ar together with O2 + N2 indicate that travertines from both areas precipitated from atmosphere‐derived fluids. The 3He/4He is 0.5–1.3 Ra in Pamukkale and 0.9–4.4 Ra in Reşadiye. Samples with R/Ra > 1 are modified by cosmogenic 3He addition during exposure to cosmic rays. Excluding these data, FIs of Reşadiye are mostly atmosphere‐derived. This implies a shallow formation where the circulation was dominated by meteoric waters, which is consistent with their young age. Instead, FIs of Pamukkale show mixing of mantle‐, crustal‐, and atmosphere‐derived He, indicating that these travertines formed in lithospheric fractures. Based on the δ13CCO2 and δ18O of bulk rocks, we infer that travertines formed involving crustal‐ (mechanochemical rather than organic) and mantle‐derived CO2. Trace elements of Pamukkale and Reşadiye show comparable rare earth element patterns. We conclude that travertines formed in response of seismogenetic activity.Published5473-54982T. Deformazione crostale attiva7T. Variazioni delle caratteristiche crostali e precursori sismici6A. Geochimica per l'ambiente e geologia medicaJCR Journa

20,000 years of societal vulnerability and adaptation to climate change in southwest Asia.

The Fertile Crescent, its hilly flanks and surrounding drylands has been a critical region for studying how climate has influenced societal change, and this review focuses on the region over the last 20,000 years. The complex social, economic, and environmental landscapes in the region today are not new phenomena and understanding their interactions requires a nuanced, multidisciplinary understanding of the past. This review builds on a history of collaboration between the social and natural palaeoscience disciplines. We provide a multidisciplinary, multiscalar perspective on the relevance of past climate, environmental, and archaeological research in assessing present day vulnerabilities and risks for the populations of southwest Asia. We discuss the complexity of palaeoclimatic data interpretation, particularly in relation to hydrology, and provide an overview of key time periods of palaeoclimatic interest. We discuss the critical role that vegetation plays in the human-climate-environment nexus and discuss the implications of the available palaeoclimate and archaeological data, and their interpretation, for palaeonarratives of the region, both climatically and socially. We also provide an overview of how modelling can improve our understanding of past climate impacts and associated change in risk to societies. We conclude by looking to future work, and identify themes of "scale" and "seasonality" as still requiring further focus. We suggest that by appreciating a given locale's place in the regional hydroscape, be it an archaeological site or palaeoenvironmental archive, more robust links to climate can be made where appropriate and interpretations drawn will demand the resolution of factors acting across multiple scales. This article is categorized under:Human Water > Water as Imagined and RepresentedScience of Water > Water and Environmental ChangeWater and Life > Nature of Freshwater Ecosystems

Molybdenum and sulfur incorporation as oxyanion substitutional impurities in calcium carbonate minerals: a computational investigation

Marked increases in sulfur and molybdenum concentration in stalagmites have been proposed as possible evidence of volcanic activity in the past. Thus, speleothems have great potential to deliver long and continuous records of volcanic activity. However, little is known about the chemical nature of these impurities in the calcium carbonate (CaCO3) phases forming stalagmites, which hinders the rationalization of the incorporation mechanisms. While sulfur is known to incorporate as a sulfate anion in CaCO3 polymorphs, the nature and stability of molybdenum incorporation in these minerals has not been investigated yet. Here, we present a computer simulation study, based on density functional theory, comparing the thermodynamics of incorporation of sulfur and molybdenum as tetrahedral oxyanions [XO4]2- (X=S, Mo) in anion sites of CaCO3 polymorphs (calcite, aragonite, vaterite, monohydrocalcite and ikaite). Among the different polymorphs, vaterite incorporates [XO4]2- ions most favourably, which reflects the relatively low density of this carbonate phase. We show that molybdate anions are very unstable (more so than sulfate anions) in the bulk of all three anhydrous carbonate phases, with respect to the formation of naturally occurring competing phases. Most of the Mo impurities found in typical calcite/aragonite stalagmites is therefore likely to concentrate at surface/interface regions such as grain boundaries. Using the calcite (10.4) surface as a model, we show that the energies of substitution are indeed much lower at the surface than at the bulk. Our results suggest that factors affecting the crystallinity of CaCO3 in stalagmites, and therefore the specific surface area, will have a significant effect on the concentration of incorporated molybdenum, which should be a key consideration when interpreting data from Mo-based speleothem archives

Age and Geochemical Constraints on Formation of Fault-related Late Quaternary Carbonate Veins from Southern Turkey

Combined U-series dating and high-resolution geochemical analyses of co-seismic carbonate veins offer an invaluable opportunity to document young (<1 Ma) earthquake activity and for tracing origins of associated fluids. In this study, we analysed a total of 23 samples of fault-related carbonate veins and slickenfibered calcites collected from two separate SW– S-trending fault zones developed near Anamur and Gazipaşa areas in Southern Turkey. Microtexturally the carbonate veins mainly comprise medium- to coarse-grained, columnar calcite crystals elongated along growth direction. U-series dating indicated episodic fault-related carbonate mineralization between 132 ± 2 and 5.6 ± 0.4 ka and between 530 ± 63 and 30.0 ± 2.1 ka in Anamur and Gazipaşa areas, respectively. Carbon and oxygen isotope compositions of carbonates from both Anamur (δ13C = -12 to -6‰, δ18O = -7 to -4‰; relative to V-PDB) and Gazipaşa (δ13C = -12 to -7‰, δ18O = -7 to -3‰) areas are almost identical, whereas Anamur samples (0.7074–0.7080) have slightly lower 87Sr/86Sr ratios compared to Gazipaşa samples (0.7081–0.7096). The 87Sr/86Sr values correlate well with that of modern and Cenozoic seawater (~0.709) and Permian limestone host rocks (~0.707). PAAS-normalized rare earth element-Yttrium patterns of most samples are characterized by negative Ce and positive Y anomalies, confirming a predominantly seawater source for calcite precipitating fluids. Our acquired age and geochemical data not only has revealed young (<500 ka) seismic activity for these previously undocumented fault systems, but it also has implications for upper crustal fluid flow and palaeoclimatological conditions in the region

Mineralogic and geochemical characteristics of late quaternary veins from Anamur-Gazipaşa fault zones (S Turkey)

Widespread vein-type carbonate (e.g., travertine) occurrences developed along active fault systems during the late Quaternary period in Turkey, a region of known active tectonism. This study presents preliminary high precision U-series and geochemical data on hypogenic fluids migrated and precipitated as carbonate veins along fractures developed in NNW-SSE trending active fault zones in S Anatolia (Ören-Anamur and Gazipaşa). U-series dates of fault-related carbonate (mainly as calcite) vein and fault plane calcite slickened fibers collected from the study areas range between >500 ka and 5.6 ka. Anamur vein samples formed between 132±2 ka and 5.6±0.4 ka, whereas ages of Gazipaşa samples vary between 530±63 ka and 30.0±2.1. Petrographic and XRD analyses revealed that the samples contain medium- to coarse-grained, equigranular, and elongated columnar calcite crystals. In some samples, calcite growth zones are identified with micrite and small groups of inclusion trails aligned perpendicular to the growth axes. According to the stable isotope analyses, the δ13C values of the fault calcite from Anamur region range between -12 and -6‰ (VPDB), and Gazipaşa samples have similar δ13C values between -12 and -7‰ (VPDB). Carbonate δ18O isotope values of Anamur and Gazipaşa regions are almost identical (Anamur: -7 – -4‰, Gazipaşa: -7 – -3‰; VPDB). Mean 87Sr/86Sr ratios of Gazipaşa samples are higher than those of both Anamur vein samples (mean=~0.708) and Permian limestone wall rock (mean=~0.707). This mean value correlates well with the mean 87Sr/86Sr ratios of modern and Cenozoic seawater (~0.709). In addition, 87Sr/86Sr values of Permian limestone wall rock samples are similar to that of Permian seawater (~0.707). A primary seawater source for calcite vein deposits is also evident in PAAS-normalized rare earth element-Yttrium diagrams, where vein samples display negative Ce and positive Y anomalies. The comparison of the project`s results with other travertine and calcite vein deposits in Turkey and the Eastern Meditarranean and the interpretation in terms of regional tectonic and climatological dynamics are still continue

Genetic investigation and comparison of Kartaldag and Madendag epithermal gold deposits in Canakkale, NW Turkey

Two epithermal gold deposits (Kartaldag and Madendag) located in NW Turkey have been characterized through the detailed examinations involving geologic, mineralogical, fluid inclusion, stable isotope, whole-rock geochemistry, and geochronology data.The Kartaldag deposit (0.01-17.65 ppm Au), hosted by Eocene dacite porphyry, is associated with four main alteration types with characteristic assemblage of: i) chlorite/smectite-illite +/- kaolinite, ii) quartz-kaolinite, iii) quartz-alunite-pyrophyllite, iv) quartz-pyrite, the last being characterized by three distinct quartz generations comprising massive/vuggy (early), fine-medium grained, vug-lining (early), and banded, colloform, comb (late) textures. Observed sulfide minerals are pyrite, covellite, and sphalerite. Oxygen and sulfur isotope analyses, performed on quartz (delta O-18((quartz)): 7.93 to 8.95 parts per thousand and calculated delta O-18((H2O)): -7.95 to 1.4 parts per thousand) and pyrite (delta S-34((pyrite)): -4.8 parts per thousand and calculated delta S-34((H2S)): -6.08 to -7.20 parts per thousand) separates, suggest a meteoric water source for water in the hydrothermal fluid, and an igneous source for the sulfur dissolved in ore-related fluids. Microthermometric analyses of primary fluid inclusion assemblages performed on quartz (late quartz generation) yield temperatures (Th) dominantly in the range of 245-285 degrees C and generally low salinity values at 0 to 1.7 wt.% NaCl eq. Based on the quartz textures and the associated base metal concentrations, along with fluid inclusion petrography, the early vug-lining quartz is considered to have been associated with the mineralization possibly through a boiling and a late mixing process at >285 degrees C.The Madendag deposit (027-20.60 ppm Au), hosted by Paleozoic mica schists, is associated with two main alteration types: sericite-illite-kaolinite, and quartz-pyrite dominated by two distinct quartz generations i) early colloform, comb and banded quartz and ii) late quartz, forming the cement in hydrothermal breccia. Whereas oxygen isotope analyses of quartz (delta O-18((quartz)): 9.55 to 18.19 parts per thousand and calculated delta O-18((H2O)): -2.97 to 5.54 parts per thousand) suggest varying proportions of meteoric and magmatic sources for the ore bearing fluid, sulfur isotope ratios (delta S-34((pyrite)): -2.2 parts per thousand and calculated delta S-34((H2S)): (-3.63) to (-3.75) parts per thousand) point to an essentially magmatic source for sulfur with or without contribution from sedimentary sources. Microthermometric analysis carried out on primary fluid inclusion populations of a brecciated sample (early quartz), give a temperature (Th) range of 235-255 degrees C and 0.0 to 0.7 wt% NaCl eq. salinity. Based on the textural relationship, base metal and high gold contents, the ore precipitation stage is associated with late stage quartz formation via a possible boiling process.The presence of alunite, pyrophyllite and kaolinite, vuggy quartz and covellite suggest a high-sulfidation type of epithermal deposit for Kartaldag. On the other hand, Madendag is identified as an adularia-sericite type owing to the presence of significant sericite, neutral pH clays (mostly illite, chlorite/smectite, and kaolinite), low temperature quartz textures (e.g., colloform, comb, and banded quartz), and limited sulfide minerals.Given the geographical proximity of Kartaldag and Madendag deposits, the similar temperature and salinity ranges obtained from their fluid inclusions, and the similar ages of igneous rocks in both deposits (Kartaldag: 40.80 +/- 036 to 42.19 +/- 0.45 Ma, Madendag: 43.34 +/- 0.85 Ma) the mineralizing systems in both deposits are considered to be genetically related. (C) 2013 Elsevier B.V. All rights reserved

Longitudinal clival fractures: A report of three cases

Genellikle şiddetli kafa travmasına eşlik ettiği bildirilen klivus kırığı vertebrobaziler sistem, beyin sapı ve alt kraniyal sinir yaralanmalarına bağlı olarak yüksek mortaliteye sahiptir. Klivus kırığının tanısı erken dönemde yüksek mortalite oranı ve acil radyolojik tekniklerin yetersiz olmasından dolayı nadiren konur. Ancak, yüksek çözünürlükte kemik pencere bilgisayarlı tomografi görüntüleme ile günümüzde tanı kolaylaşmı ştır. Bu yazıda, hafif (bir olgu) ve şiddetli (iki olgu) kafa travması sonrası longitüdinal klivus kırığı saptanan üç hastadaki radyolojik ve klinik özellikler sunularak eşlik eden patolojiler ve prognoz açısından önemi, literatürdeki az sayıda bildirilen olgulardan da yararlanılarak tartışıldı.Fractures of the clivus are often associated with severe head trauma and have high mortality rates due to coexisting injury of the adjacent vessels, brain stem and lower cranial nerves. An early diagnosis is often not possible because of adherent problems, high mortality rate and inadequacy of emergency imaging. Diagnosis has recently become easier with high resolution bone window computed tomography studies. In this study, radiological and clinical findings of three patients with longitudinal clival fractures and severe head trauma have been presented and associated injuries and prognostic issues are discussed with reference to the limited number of similar cases in the English literature

Tethered cord syndrome in the adult

Çocukluk çağında daha çok görülen gergin omurilik sendromu erişkin yaş grubunda da görülmektedir. İstanbul Tıp Fakültesi Nöroşirurji Kliniğinde 1971-1996 yıllan arasında ameliyat edilen 128 gergin omurilik sendromlu olgudan 21 yaş ve üstü onaltısı rekrospektif olarak değerlendirildi. Olguların dokuzu erkek, yedisi kadın ve yaş ortalaması 41.7(yaş aralığı:21-82) idi. Nedenler arasında en sık kısa-kalın fılum terminale ve intradural lipom saptandı. Bel ve bacak ağrısı en sık rastlanan başvuru yakınması idi. Cerrahi olarak gerginliğin sonlandırıldığı olgularda klinik remisyon sağlandı. Olguların yedisinde üç ay sonra yapılan kontrol manyetik rezonans görüntüleme tetkiklerinde konuş medullaris'in seviye olarak ameliyat öncesi durumunun değişmediği ancak gerginliğin kaybolduğu görüldü. Bel, bacak ağnsı ve yürüme mesafesinde kısalma yakınmaları ile başvuran olguların ayırıcı tanısında gergin omurilik sendromu da düşünülmelidir.Tethered cord syndrome in the adult. Tethered cord syndrome can be seen in adults although it is more common in childhood. Of the 128 tethered cord syndrome cases which were surgically treated between 1971-1996 in our institution, 16 of them, 21 years of age and above were evaluated. Nine of the cases were male, seven of then were female and average age was 41.7(ranging from 21-82). Thick-short filum terminale and intradural lipoma were the most common etiologi-cal factors. Back and leg pain was the most common complaint for admittance. Terminating the tethering surgically; resulted in clinical remission. After three months, it was seen in seven of the cases on the magnetic resonance scanning, the position of level has not changed but tethering was disappeared. The patients who admit with back and leg pain and shorting of walking distance complaints, tethered cord syndrome must be considered at further investigating