Open Circulation Research Articles

A Study of Microfacies and Petrophysical Analysis of Some Subsurface Cretaceous Rocks of Abu Gharadig-34 Well, Western Desert, Egypt

The main aim of this study is to shed light on the microfacies association, petrophysical parameters, and depositional environment of different rocks such as sandstone, limestone, shale, siltstone, and dolomite of subsurface Cretaceous rock units (Abu Roash “C” member, Abu Roash “E” Member, and Bahariya Formation) from Abu Gharadig-34 well in the north western desert, Egypt. In this study, nine microfacies were identified. These microfacies include calcareous siltstone, bioclastic wackstone, ferruginous sublithic arenite, dolomitic lithic arenite, lithic arenite, fossiliferous bioclastic wackstone, glauconitic dolomitic sublithic arenite, ferroan dolomite, and ferruginous sandy siltstone. Generally, subsurface Cretaceous rock units are deposited in different depositional environments ranging from tidal flats to open circulation passes through restricted circulation shelves. Statistical analysis of the petrophysical data showed that the highest porosity was concentrated at Abu Roash “C” member, which had very good porosity and high permeability. The porosity increased when the bulk density decreased. The permeability of the studied samples was the same as the porosity, which increased when the bulk density decreased. It can be concluded that Abu Roash “C” member is a good reservoir in the Abu Gharadig-34 well.

Late Carboniferous macrofauna from Wadi Araba, Eastern Desert, Egypt, and their paleoecological implications

The Upper Carboniferous rocks at Wadi Araba are highly rich in macrofaunal content. The systematic description of these macrofauna reveals the identification of 34 species, 17 species of which are recorded for the first time from the Carboniferous rocks of Egypt, among them the trilobite Cummingella ( C.) carringtonensis carringtonensis (Etheridge). Moreover, the paleoeclogic study on some crinoid and brachiopod specimens shows predation and commensal relations with some endo and epibionts fauna. The study presents also crinoidal infestation by Oxytoma ( Palmoxytoma) cygnipes (Young and Bird) species, a relation which is recorded for the first time. Evidences of crushing or biting damages on some brachiopod shells that have been attributed to nautiloids or conchostracan arthropods are also reported. The microfacies study of the carbonate rocks in this area reveals the identification of five microfacies types indicating that the rocks were deposited in an environment ranging from restricted inner to outer shelf lagoonal environments with open circulation. The microfacies study indicates also the presence of two types of microorganisms, the filamentous microorganisms and the fossilized microbial carbonate communities, which played an important role in iron oxide precipitation and rock diagenesis.

Does the Paleoproterozoic Animikie Basin record the sulfidic ocean transition? REPLY

The Paleoproterozoic Animikie Basin in the Lake Superior region of North America is the benchmark for understanding one of the most significant changes in seawater chemistry in Earth history—the transition to a sulfidic ocean (ca. 1.84 Ga). This transition marks a dramatic increase in ocean sulfide produced by bacterial reduction of sulfate formed through the oxic chemical weathering of pyrite during the Great Oxidation Event. Such a change is thought to have caused the cessation of widespread iron formation deposition and marks the beginning of a long lull in the evolution of eukaryotes. The feasibility of using the Animikie Basin to understand this transition is re-evaluated by comparing new sulfur isotope data (δ 34 S pyrite ) from the Michigamme Formation in northern Michigan, United States, to published results from the correlative Rove Formation in Ontario, Canada. These data suggest that microbial sulfate reduction was restricted to organic-rich environments away from the influence of deltas, which delivered low-sulfate river water to the coast. Sulfur isotope data and the patchiness of sulfate reduction within the Animikie Basin suggest strong lateral and vertical gradients in seawater sulfate concentrations. When viewed in the context of the most recent tectonic and sedimentologic models, these observations are best interpreted as reflecting an evolving basin with restricted water circulation, not open circulation with the global ocean as previously postulated. Thus, the Animikie Basin does not contain an accurate record of open-ocean structure and composition during the onset of sulfidic conditions. What is clear is that marginal seas must be carefully evaluated before they are used to model the global ocean, especially given the rarity of preserved Precambrian deep-sea sediments.

Simulation of operating characteristics of the silica gel–water adsorption chiller powered by solar energy

Abstract A lumped parameter model of a silica gel–water adsorption chiller driven by solar energy was introduced for the operating characteristics investigation. Matlab–Simulink, as a high-performance computing and programming tool, was used to simulate the operating characteristics of the chiller. Effects of the hot water tank capacity, the cycle time and the initial hot water temperature on the performance of the chiller were analyzed when the chiller was driven by a stable heat source and solar energy respectively. The simulation results indicated that when the chiller was driven by solar energy, the open circulation of the hot water with a short cycle time and the closed circulation of hot water with a longer cycle time were better. A proposal was also provided for the chiller driven by solar energy to work under the optimum working conditions, such as hot water circulation mode, cycle time and initial temperature.

Cyclic sedimentation in the Eocene Allenby Formation of south-central British Columbia and the origin of the Princeton Chert fossil beds

Extensive deposits of Eocene conglomerate, sandstone, shale, and sub-bituminous coal occur within a half-graben at Princeton, British Columbia. These strata comprise ∼2000 m of fluvial sediment interbedded with tephra and volcanic flows. Near the southeast margin of the basin, ∼200 m of rhythmically bedded strata are exposed along the Similkameen River. Cyclic deposition resulted from repeated episodes of hydrologic and topographic change related to seismic activity along the Boundary Fault on the east flank of the Princeton Basin, where Allenby Formation sediments are juxtaposed against metamorphic and metavolcanic rocks of the Upper Triassic Nicola Group. Interbedded carbonaceous shale and tuffaceous sandstone record influxes of distal lahar deposits into a lowland swamp. Coal–breccia transitions originated when debris flows along the scarp carried volcanic debris into adjacent wetlands. Coal–chert rhythmites are inferred to be evidence of hydrologic changes associated with floodplain tilt events that caused lowland to repeatedly alternate between a stagnant pond (“fen”) and a stream-fed lake. During fen stages, peat was silicified in situ from percolation of groundwater carrying silica dissolved from underlying tuffaceous beds. Episodic influxes of stream flow reduced dissolved silica concentrations and caused increases in dissolved oxygen levels. These geochemical changes caused organic matter that accumulated during these conditions of open water circulation to remain unsilicified and susceptible to partial maceration. Diagenesis eventually converted these deposits to alternating beds of sub-bituminous coal intercalated with chert horizons.

International Convergence of Corporate Governance: Concepts and Reality

This paper sheds light on some critical questions about international convergence of corporate governance: what are the different governance models prevailing in the different countries around the world and why? Is there any “best” corporate governance mode? If so, how the countries with different models are moving towards developing the optimum model and is there any convergence? What are the major factors enhances the convergence in corporate governance? This study finds that convergence in corporate governance is taking place due to the reasons related to the globalization of financial and product markets, an increasing harmonization and propinquity of legal and institutional norms and a more open circulation of and attitude towards foreign ideas.

Investigation of tropical eel spawning area in the South-Western Indian Ocean: Influence of the oceanic circulation

In the South-Western Indian Ocean (SWIO), four eel species of the genus Anguilla (i.e. Anguilla bicolor bicolor, Anguilla nebulosa labiata, Anguilla marmorata and Anguilla mossambica) were identified, while their respective oceanic spawning area remained unknown. Based on collected larvae, glass eel captures and hydrodynamical conditions, previous studies raised the hypothesis that the eel spawning area might be common to all of those freshwater eel species, and located East of Madagascar. An original modeling approach, based on backward simulations, is developed to assess how the ocean circulation in the SWIO determines the location of the spawning areas and whether a common spawning area for each recruitment site where glass eels were found is possible. We use a hydrodynamical model, which reproduces realistically the 3D open ocean circulation in the region, associated with a Lagrangian model that calculates the possible migration pathways of larvae, represented by passive particles. Some biological parameters, provided by previous otolith microstructures analysis, are taken into account to constrain our simulations. Results suggest the existence of a common spawning area located between 13°S and 19°S and westwards of 60.5°E, although these boundaries vary on the interannual timescale. Salinity fronts were reported beside the boundaries, reinforcing this assumption. We explore the impact of hydrodynamic conditions on recruitment and migration durations from three specific regions within the common spawning area. They all allow migration to each recruitment sites consistent with duration estimated from otolith microstructure analyses. Nevertheless, there is substantial variability on intra-seasonal to interannual timescale in simulated migration durations and arrival success, with specific amplitude to each recruitment site and spawning location.

Cretaceous anoxic–oxic changes in the Moldavids (Carpathians, Romania)

This study focused on the Cretaceous black shale successions, followed by red shales that crop out at the outer regions of the Romanian Carpathians, in the Moldavids. The oldest parts of the black shale units deposited in an abyssal plain during Late Valanginian–Late Barremian time; they are mainly characterized by hemipelagic and pelagic muddy siliciclastic rocks and carbonates, commonly intercalated with fine-grained turbidites. During the sedimentation of the middle part of the black shale units in the Late Barremian–Early Albian interval, the depth of the basin increased, as the carbonate hemipelagic sedimentation was replaced by a mainly siliceous one. Only a few thin turbidite intercalations are present. The youngest part (Albian pro parte) of the black shale units is characterized by a turbiditic sedimentation, with mainly sandy sequences of middle and lower deep-water fans. We may assume that the depth of the basin continuously decreased. The presence of authigenic glauconite in the Albian sandstones suggests a palaeoenvironmental change, linked to the occurrence of oxygenated turbidity current circulation. A significant shift in the sedimentation regime in the Eastern Carpathian Moldavids took place in the Late Albian, when Cretaceous Oceanic Red Beds (CORB) occurred. This type of sedimentation lasted up to the Coniacian. The lower part of the CORBs that contains radiolarites intercalated with variegated shales, pyroclastic tuffs and thin sandstones is interpreted as a hemipelagic and pelagic sedimentation in the abyssal plain environment, where rarely turbidites occurred. Upwards, there are mainly burrowed variegated red and green shales. The youngest parts of CORBs are characterized by increased thickness and frequency of the turbidites. While the main part of the CORB is carbonate free or has very low carbonate content, the upper part of these strata becomes rich in marl and mudstone strata, indicating a decrease of the basin-depth. The accumulation of black shales in the Eastern Carpathians during the Late Valanginian–Late Albian interval is linked to the existence of a small, silled basin of the Moldavian Trough, in which restricted circulation led to the density stratification of the water column, resulting in the deposition of anoxic Lower Cretaceous sediments (i.e., the black shales). Because of the tectonic deformation that took place within the Lower–Upper Cretaceous boundary interval, the restricted circulation had changed to an open circulation regime in the Moldavian Trough. Hence, the anoxic regime was progressively replaced by an oxic one, across the Albian–Cenomanian boundary interval. The beginning and the end of the CORBs in the Moldavid units depend thus on various palaeogeographic and palaeoenvironmental settings, and it was controlled by the regional tectonic activity.

Thyroid Function and Insulin Sensitivity Before and After Bilio-pancreatic Diversion

Bilio-pancreatic diversion (BPD) induces permanent weight loss in previously severe obese patients through a malabsorptive mechanism. The aim of the study was to evaluate the modifications of circulating thyroid hormones after BPD, a surgical procedure which interferes with the entero-hepatic circulation of biliary metabolites. Forty-five patients were studied before and 2 years after BPD. Thyroid-stimulating hormone (TSH), free triiodothyronine (fT3), free thyroxine (fT4), anti-thyroid antibodies, iodine urinary excretion, lipid profile, insulin and glucose plasma levels were assessed. The insulin-resistance HOMA IR index was calculated, and colour Doppler ultrasonography of the neck was performed. The subjects (23%) had subclinical hypothyroidism prior to BPD (TSH levels above the normal range with normal fT3 and fT4 levels). After 2 years 40.42% of the population showed subclinical hypothyroidism, while 6.3% became frankly hypothyroid, all of them with no evidence of auto-immune thyroiditis. Most of the patients, who became sub-clinically hypothyroid only following BPD, had already thyroid alterations at the sonogram (multi-nodular euthyroid goiter and thyroidal cysts) prior to surgery. BPD increases the prevalence of subclinical or even frank hypothyroidism, without causing a defect in thyroid function itself, through several integrated mechanisms. (1) It induces iodine malabsorption, which is partially compensated by iodine excretion contraction. (2) The entero-hepatic open circulation determines fT3 loss, which induces subclinical or frank hypothyroidism in patients with pre-existing thyroid alterations, interfering also with the weight loss progress. Iodine supplementation should be recommended in those patients reporting thyroid alterations at the sonogram prior to BPD, LT4 therapy should be strictly monitored in patients suffering of subclinical hypopthiroidism and T3 therapy should eventually be considered for patients diagnosed with frank hypothyroidism prior to BPD.

Abstract 5580: Nanolytic Approach to Prompt Revascularization in Acute Ischemic Stroke

Background: Vascular-constrained fibrin-specific nanolytic agents could permit early revascularization in the setting of acute ischemic stroke. Development of fibrin-targeted nanolytics requires optimized surface co-presentation of homing ligands and fibrinolytic enzymes on nanoparticles without compromising bioactivity. Objective : The study optimized human urokinase coupling and anti-fibrin homing ligand density for targeted thrombolytic efficacy and demonstrated the concept in vivo. Methods and Results: Minimal thiolation (N-succinimidyl-S-acetylthioacetate, SATA) of urokinase (i.e., 1 to 3 SATA/molecule) diminished human clot dissolution time relative to the native molecule; greater degrees of thiolation (3 to 6 SATA/molecule) severely decreased activity. For dog clots, which digested slower than human clots, 1 to 3 SATA/urokinase did not further impair fibrinolysis rate. Concomitant coupling of thiolated urokinase and anti-fibrin antibody (50:5, 100:10, 200:20, and 400:40 ratio, respectively) to perfluorocarbon nanoparticles resulted in optimal clot dissolution for the 100:10 and 200:20 formulations. Increasing the surface urokinase-to-antibody ratio from 0:10 to 50:10, 100:10, 200:10, and 400:10 increased particle size from 273 nm (0:10) to 340 nm at the 50:10 and 100:10 enzyme levels, and to more than 400 nm with 200 urokinase molecules per particle. Acoustic microscopy (25MHz) was used to quantify binding of the fibrin-targeted PFC nanoparticles to acoustically transparent human clots. Fibrin targeting with 10 antibodies per particle provided minimal acoustic enhancement in comparison with the relatively increased (p<0.05) but equivalent signals obtained with 20 or 40 antibodies per particle. Dissolution of canine femoral clots, created by electrical injury, was monitored with low MI ultrasound under open circulation conditions following in situ targeting with the nanolytic system. Substantial subjective clot dissolution and fragmentation was observed in three animals over 60 minutes, demonstrating the nanolytic concept. Conclusion: Nanolytic agents can target fibrinolytic enzymes to lyse nascent thrombus, which may permit early revascularization in acute ischemic stroke with minimal hemorrhagic risk.

Seasonal and interannual variability of the surface circulation in the eastern Gulf of Cadiz (SW Iberia)

An 11‐year (1996–2007) time series of current meter observations representative of the open sea circulation; a 4‐year (2001–2005) time series of current meter records over the continental shelf and in situ data during different seasons have been compared in order to study the seasonal and interannual variability of the surface circulation in the eastern Gulf of Cadiz. The open sea velocity observations indicate southeastward flow along the northern continental slope of the Gulf of Cadiz, compatible with anticyclonic circulation, during most of the year and more intense during summer months. Flow reversals (northwestward circulation) at seasonal time scales in late autumn and early winter (preferably December and January) are a rather recurrent feature with variable intensity depending on the year. Anticyclonic circulation is associated with westerlies, whereas flow reversals usually take place under easterly episodes, suggesting wind‐driven circulation. Negative North Atlantic Oscillation indices (indicative of southward displacement of the Azores high) are also linked to the reversals. Changes in this mainly wind‐driven large‐scale surface circulation are echoed by the shelf circulation: the coastal countercurrent that closes the mesoscale cyclonic cell over the eastern shelf in spring‐summer (upwelling season) is replaced by and eastward current in autumn and winter.

Foraminifera and palaeoenvironment of elevated Late Pleistocene sands, White Rock Point, southeastern Tasmania

A well-preserved foraminiferal fauna similar to that living in nearby Ralphs Bay in southeastern Tasmania is documented from raised shallow-water sediment of 130-119 Ka age (Late Pleistocene; Marine Isotope Stage 5e) at about 24 m above modern sea level on White Rock Point. Foraminifera and sediment characteristics indicate that deposition occurred in very shallow, highly oxygenated, high-energy marine conditions in an area of open circulation. There is very little infauna. The locality is the only known site for such a fauna from before human habitation of the Derwent Estuary region, and allows comparison with modern faunas.

Evaluation of faba beans ( Vicia faba L. var. minuta) as a replacement for soybean meal in practical diets of juvenile Nile tilapia Oreochromis niloticus

We have studied the possible use of faba bean meal (FBM) in juvenile Nile tilapia-practical diets by progressively increasing its inclusion level at the expense of dehulled soybean meal (DSBM) in isonitrogenous (27.5%) and isoenergetic formulated (15.20 kJ g − 1 ) diets. DSBM was replaced by 12, 24 and 36% of FBM (diets 1, 2 and 3, respectively). A diet without FBM served as the control. Each diet was fed for 75 days to three replicate groups of 30 fish (17.64 ± 0.04 g; mean ± SE), arranged in a completely randomized design in an open circulation system. Survival did not differ among treatments ( p > 0.05). The growth and feed conversion ratio (FCR) did not differ significantly ( p < 0.05) between fish fed diets1, 2 and the control diet. By contrast fish fed diet 3 showed poorer growth and feed conversion ratio than the other groups. Apparent dry matter digestibility (ADMD) showed a progressive reduction with increasing FBM levels. Apparent protein digestibility (APD) decreases significantly in fish fed diet 3. No significant difference in carcass protein content was found among the treatments, but fish fed diet 3 had higher moisture and lower lipid content in carcass than fish fed in the other diets. Results showed that FBM could be incorporated up to 24% in diets of juvenile Nile tilapia which corresponds to a reduction of 20% DSBM in the control diet without compromising growth or feed conversion ratio.

Postglacial depositional environments and sedimentation rates in the Norwegian Channel off southern Norway

Based on seismic profiles, multibeam bathymetry and sediment cores, an improved understanding of the deglaciation/postglacial history of the southern part of the Norwegian Channel has been obtained. The Norwegian Channel Ice Stream started to recede from the shelf edge ca. 15.5 ka BP ( 14C ages are used throughout). Approximately 500–1000 years later the ice margin was located east of the deep Skagerrak trough. At that time, the Norwegian Channel off southern Norway had become a large fjord-like embayment, surrounded by the grounded ice sheet along the northern slope and possibly stagnant ice remnants at the southern flank. The Norwegian Channel off southern Norway has been the main sediment trap of the North Sea, and south of Egersund more than 200 m of sediments have been deposited since the start of the deglaciation. Five seismic units are mapped. The oldest unit E occurs in some of the deepest troughs, and was deposited immediately after the ice became buoyant. Unit D is acoustically massive and comprises mass-movement deposits in eastern Skagerrak and south of Egersund. Unit C (in the channel southwest of Lista/Egersund) is interpreted to comprise mainly bottom current deposits derived from palaeo-rivers, e.g. Elben. During deposition of unit C (ca. 14.5–13 ka BP), there was limited inflow of Atlantic water. A change in depositional environment at ca. 13 ka BP is related to an increased inflow of saline water and more open hydrographic circulation. Widely distributed, acoustically stratified clays of unit B were deposited ca. 13–10 ka BP. The Holocene Unit A shows a depositional pattern broadly similar to that of unit B.

Upper Cretaceous facies development and depositional environments, Gebel Somar area, north central Sinai, Egypt

Facies analysis of the exposed Upper Cretaceous sequence at Gebel Somar area revealed that the Cenomanian — Turonian carbonates are related either to platform — epicontinental sea or to deeper shelf- margin carbonates. Their microfacies types are equivalent to the Standard Microfacies (SMF) types, namely the bioclastic wackestone or bioclastic micrite (SMF-9) of shallow open marine platform facies (FZ. 7), rudstone with reef debris (SMF-6) accumulated in fore-reef slope (FZ. 4) and hemipelagic wackestone (SMF-3) deposited under deep shelf marginal conditions (FZ. 3). The Coniacian-Santonian rocks show rapid facies change and manifest oscillating depositional environments from restricted marine shoals to shelf facies with open circulation. The SMF types of bioclastic wackestone (SMF-9), grainstone with coated bioclasts (SMF-11), grainstone with ooids (SMF-15), grainstone with pellets (SMF-16), grainstone or pelsparite with aggregate grains (SMF-17) and pelleted lime mudstone-wackestone (SMF-19) are discernible in the Coniacian-Santonian carbonates. These SMF types are platform facies belts either winnowed (FZ. 6), open (FZ. 7) or restricted (FZ. 8) platforms. The rapid facies change of the Coniacian-Santonian may reflect mild tectonic instability other than sea-level fluctuations. This tectonic instability may be the first imprint of Syrian are deformation, evidenced at the studied area by complete absence of Campanian strata. The Maastrichtian rocks are formed of pelagic sediments deposited under deep shelf margin conditions (SMF-3) in a wide basin or depocenter generated as a result of the Syrian arching system.

The role of water mass dynamics in controlling bacterial abundance and production in the middle Adriatic Sea

Month-to-month fluctuations in the abundance of bacteria and heterotrophic nanoflagellates (HNF) and bacterial production, as well as various chemical (nutrients, oxygen) and physical (salinity, temperature) parameters were analysed at a station located in the open middle Adriatic Sea during one decade (1997-2006). Being influenced by both coastal waters and open Adriatic circulation in the surface layer, and by the deep Adriatic water masses in the deep layers (100 m), this station is quite suitable for detecting the environmental changes occurring in the open Adriatic Sea with respect to the circulation of its water masses and their long-term changes and anomalies. Multivariate methods were used to identify seasonal and inter-annual changes of the investigated parameters, associating observed changes to the changes in Adriatic water masses and circulation regimes. The analyses showed that bacterial abundance and production were controlled by different water mass dynamics during 1997-2001 compared to 2002-2006 period, particularly noticeable in different seasonal patterns of biological parameters. The interplay between North Adriatic Dense Water (NAdDW) and Levantine Intermediate Water (LIW) resulted in a change in the available nutrients (NAdDW is poor in orthophosphates), and as a consequence different bacterial abundance and production. A few periods were examined in detail, such as 2004, when LIW inflow was particularly strong and was accompanied by an increase of bacterial and HNF abundances, as well as of bacterial production.

Growth of Nile tilapia (Oreochromis niloticus L.) fed with diets containing graded levels of green algae ulva meal (Ulva rigida) reared in geothermal waters of southern Tunisia

Summary The use of green algae ulva meal (UM) (Ulva rigida) was evaluated as a replacement for soybean meal in a practical diet formulated to contain 28% crude protein, 7.50% lipid and 15 kJ gross energy g−1. Soybean meal was replaced by 0%, 10%, 20% and 30% of UM (diets U0, U1, U2 and U3, respectively). The feeding experiment was carried out in an open circulation system. Each diet treatment was applied to triplicate groups of 30 fish (21.37 ± 0.193 g average wet weight) per tank (400 L) arranged in a completely randomized design. The fish were hand fed to satiation four times daily between 07.00 and 18.00 hours for 75 days. There were no significant differences (P > 0.05) in growth performance among fish fed with diets U0, U1 and U2. However, fish fed diet U3 had significantly lower growth (P < 0.05) than those fed diets U0, U1 and U2. Fish fed the control diet (U0) and diets including 10% and 20% UM had significantly (P < 0.05) better daily weight gain, relative growth weight, specific growth weight and protein efficiencies ratio than those fed with diet U3. Feed conversion ratio increased with increasing UM content, but only the value found in fish fed with diet U3 differed significantly (P < 0.05) from all other treatments. Survival rates ranged between 91.11% and 93.33%. No feed-related mortality was observed during the entire experimental period. Apparent protein digestibility (APD) of diets ranged from 87.06 to 69.91% and was lowest for fish fed with diet U3. In general, APD values decreased with increasing inclusion levels of UM, explained by the increase of anti-nutritional factors and high non-digestible fibre content. Compared to the control diet (U0), fish fed diets containing high levels of UM had lower levels of carcass lipid and higher levels of carcass moisture. Results show that this product can be included by up to 20% in practical male Nile tilapia diets with no detrimental effects.

Phenotypic differences between red pulp capillary and sinusoidal endothelia help localizing the open splenic circulation in humans

The distribution of capillaries, sinuses and larger vessels was investigated by immunohistology in paraffin sections of 12 adult human spleens using a panel of antibodies. Double staining for CD34 and CD141 (thrombomodulin) revealed that capillary endothelia in the cords of the splenic red pulp and at the surface of follicles were CD34(+)CD141(-), while red pulp sinus endothelia had the phenotype CD34(-)CD141(+). Only in the direct vicinity of splenic follicles did sinus endothelial cells exhibit both antigens. Thus, splenic sinuses do not replace conventional capillaries, but exist in addition to such vessels. The endothelium in arterioles, venules and larger arteries and veins was uniformly CD34(+)CD141(+). Anti-CD34 and anti-CD141 both additionally reacted with different types of splenic stromal cells. Differential staining of capillaries and sinuses may permit a three-dimensional reconstruction of serial sections to unequivocally delineate the "open" and "closed" splenic circulation in humans.

Perfluorinated acids as novel chemical tracers of global circulation of ocean waters

Perfluorinated acids (PFAs) such as perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) are global environmental contaminants. The physicochemical properties of PFAs are unique in that they have high water solubilities despite the low reactivity of carbon-fluorine bond, which also imparts high stability in the environment. Because of the high water solubilities, the open-ocean water column is suggested to be the final sink for PFOS and PFOA. However, little is known on the distribution of PFAs in the oceans around the world. Here we describe the horizontal (spatial) and vertical distribution of PFAs in ocean waters worldwide. PFOS and PFOA concentrations in the North Atlantic Ocean ranged from 8.6 to 36 pg l −1 and from 52 to 338 pg l −1, respectively, whereas the corresponding concentrations in the Mid Atlantic Ocean were 13–73 pg l −1 and 67–439 pg l −1. These were completely different from the surface waters of the South Pacific Ocean and the Indian Ocean (overall range of <5–11 pg l −1 for PFOS and PFOA). Vertical profiles of PFAs in the marine water column were associated with the global ocean circulation theory. Vertical profiles of PFAs in water columns from the Labrador Sea reflected the influx of the North Atlantic Current in surface waters, the Labrador Current in subsurface waters, and the Denmark Strait Overflow Water in deep layers below 2000 m. Striking differences in the vertical and spatial distribution of PFAs, depending on the oceans, suggest that these persistent acids can serve as useful chemical tracers to allow us to study oceanic transportation by major water currents. The results provide evidence that PFA concentrations and profiles in the oceans adhere to a pattern consistent with the global “Broecker’s Conveyor Belt” theory of open ocean water circulation.

Depositional framework and sequence stratigraphic aspects of the Coniacian–Santonian mixed siliciclastic/carbonate Matulla sediments in Nezzazat and Ekma blocks, Gulf of Suez, Egypt

Superb outcrops of mixed siliciclastic/carbonate rocks mark the Coniacian–Santonian Matulla Formation exposed in Nezzazat and Ekma blocks, west central Sinai. They are built up of various lithofacies that reflect minor fluctuations in relative sea-level from lower intertidal to slightly deep subtidal settings. Relying on the facies characteristics and stratal geometries, the siliciclastic rocks are divided into seven depositional facies, including beach foreshore laminated sands, upper shoreface cross-bedded sandstone, lower shoreface massive bioturbated and wave-rippled sandstones, shallow subtidal siltstone and deep subtidal shale/claystone. The carbonate rocks comprise lower intertidal lime-mudstone, floatstone and dolostone, shallow subtidal skeletal shoal of oyster rudstone/bioclastic grainstone, and shoal margin packstone. Oolitic grain-ironstone and ferribands are partially intervened the facies types. Deposition has taken place under varied conditions of restricted, partly open marine circulation, low to high wave energy and normal to raised salinity during alternating periods of abundant and ceased clastic supply. The facies types are arranged into asymmetric upward-shallowing cycles that record multiple small-scale transgressive–regressive events. Lime-mudstone and sandstone normally terminate the regressive events. Four sequence boundaries marking regional relative sea-level falls divide the Matulla Formation into three stratigraphic units. These boundaries are Turonian/Coniacian, intra-Coniacian, Coniacian/Santonian and Santonian/Campanian. They do not fit with those sequence boundaries proposed in Haq et al.’s global eustatic curves (1988) except for the sea-level fall associated with the intra-Coniacian boundary. Other sequence boundaries have resulted from regional tectonic impact of the Syrian Arc Fold System that has been initiated in north Egypt during the Latest Turonian–Coniacian. These boundaries enclose three well-defined 3rd order depositional sequences; their enclosing shallowing-upward cycles (i.e. parasequences) record the 4th order relative sea-level fluctuations. 34 and 20 parasequence sets, in the order of a few meters to tens of meters thick, mark the Matulla sequences in Nezzazat and Ekma blocks respectively. Each sequence shows an initial phase of rapid sea-level rise with retrogradational sets, followed by lowering sea-level and progradation/aggradation of the parasequence sets. The transgressive deposits display predominance of deep subtidal lagoonal facies, while highstand deposits show an increase in siliciclastic and carbonate facies with the progressive decrease of lagoonal facies. The sedimentary patterns and environments suggest that the regional, partly eustatic sea-level (i.e. intra-Coniacian) changes controlled the overall architecture of the sequence distribution, whereas changes in the clastic input controlled the variations in facies associations within each depositional sequence.