The chemical oceanographic consequences of environmental restoration projects in the Golden Horn estuary (Marmara Sea, Turkey).

The input of industrial and domestic waste to the horizontal circulation in the Golden Horn Estuary of Marmara Sea has resulted in one of the most polluted estuaries in the past. Consequently, the dissolved oxygen concentrations in both the surface and bottom waters decreased toward to the estuary head during 1998-2005. In contrast, the total suspended solids content of the surface water decreased toward to the estuary mouth. However, construction of the operational collector system surrounding the estuary during the process of rehabilitation projects, combined with the opening of the middle pontoons of the Valide Sultan Bridge, resulted in gradually improved water quality of the estuary with a concomitant decrease in pollution. However, phytoplankton blooms and eutrophication persist especially in the innermost part of the Golden Horn in 2005. The region from the estuary mouth up to Camialti has a dynamic structure, and sufficient circulation seemingly occurs in this part of the Golden Horn.

Active manganese oxide: a novel adsorbent for treatment of wastewater containing azo dye.

A new variety of active manganese oxide was prepared, characterized, and tested for its potential of adsorbing Congo Red, a dis-azo dye, from aqueous solutions. Both equilibrium and kinetics were investigated over different values of process parameters such as temperature (25-45 degrees C), adsorbent loading (0.4-0.6%), initial dye concentration (50-500 mg/L), presence of salts (sodium sulphate, 500 mg/L) and the oxygen content (MnO(x), x=1.2, 1.33 and 2) of the adsorbent. The equilibrium adsorption data were fitted to Langmuir and Freundlich isotherms. Langmuir adsorption capacity of the sorbent (x=1.33) for Congo Red was 38.6 mg/g at room temperature which is substantially higher than those for commercial manganese dioxide, red mud, coir pith, activated carbon, and fly ash. The kinetic data were best interpreted using a pseudo-second order model. The results show that the active manganese oxide used in this work removes the dye by reversible adsorption and has the potential for practical use for remediation of textile industry effluents.

Spectrophotometric determination of cyclotrimethylenetrinitramine (RDX) in explosive mixtures and residues with the Berthelot reaction.

On-site colorimetric methods are a valuable, cost-effective tool to assess the nature and extent of contamination in remediated sites and to enable on-site screening for police criminology laboratories. The existing colorimetric method for cyclotrimethylenetrinitramine (RDX) based on a Griess reaction suffers from the non-quantitative reduction to nitrite and from the unstable character of HNO2 in acidic medium. Thus we propose a novel spectrophotometric RDX assay in explosive mixtures and residues, based on (Zn+HCl) reduction of RDX in a microwave oven, followed by neutralization of the reduction products to ammonia and low molecular-weight amines, and Berthelot reaction of these amine-compounds with phenol and hypochlorite in alkaline medium to give an intensely blue indophenol dye absorbing at 631nm. The molar absorptivity and limit of detection (LOD) for RDX were (1.08+/-0.04)x10(4) L mol(-1) cm(-1) and 0.18 mg L(-1), respectively. Application of the method to synthetic mixture solutions of RDX and trinitrotoluene (TNT) at varying proportions showed that there was minimal interference from TNT (which could be compensated for by dicyclohexylamine colorimetry), since the Berthelot reaction was essentially non-responsive to m-substituted anilines derived from TNT upon (Zn+HCl) reduction. The proposed method was successfully applied to military-purpose explosive mixtures of (RDX+inert matter) such as Comp A5, Comp C4, and Hexal P30, and to (RDX+TNT) mixtures such as Comp B. The molar absorptivity of RDX was much higher than that of either ammonium or nitrate; RDX could be effectively separated from ammonium and nitrate in soil mixtures, based on solubility differences. The Berthelot method for RDX was statistically validated using Comp B mixtures against standard HPLC equipped with a Hypersil C-18 column with (40% MeOH-60% H2O) mobile phase, and against gas chromatography-thermal energy analysis (GC-TEA) system.

Spectrophotometric determination of 4,6-dinitro-o-cresol (DNOC) in soil and lemon juice.

Although the use of once widely applied selective herbicide, 4,6-dinitro-o-cresol (DNOC), was cancelled by US-EPA in 1987, it is still found in soil and water due to its slow degradation in the environment. Since solid phase extraction-spectrophotometry combinations are much simpler and cheaper than chromatography/MS based methods and most routine laboratories lack such sophisticated instrumentation, it is desirable to establish novel sensitive, well-established, and field-applicable spectrophotometric methods for the rapid assay of DNOC in water and soil. For this purpose, two distinct spectrophotometric methods utilizing the periodate and copper(II)-neocuproine (Nc) reagents have been developed following Zn/HCl reduction of the pesticide in a microwave oven for 15s, and validated for DNOC determination at mg L(-1) level. The LOD values were 1.6 and 0.2 mg L(-1) for periodate and Cu(II)-Nc methods, respectively. Statistical comparison of the developed methods was made with the aid of high performance liquid chromatography (HPLC) equipped with a C18 (5 microm), 250 mm x 4.6 mm ID reversed phase column in conjunction with a UV (264 nm) detector, and a methanol (HPLC grade) +0.1% glacial acetic acid mixture mobile phase. Both spectrophotometric methods were directly applicable to soil since they were not interfered with common soil cations and anions, together with some pesticides. These methods were applied to real samples such as synthetically contaminated montmorillonite and lemon juice, and overall recovery efficiencies at the order of 95% or greater were achieved in the devised adsorption/elution procedures. An 8-hydroxyquinoline (oxine)-impregnated XAD copolymer resin stabilized with Fe(III) salt was used to preconcentrate DNOC at a concentration factor of 20 from lemon juice contaminated with 1 mg L(-1) DNOC, and the analyte retained at pH 2.5 was eluted with 0.025 M methanolic NaOH. Both the devised spectrophotometric methods and the proposed preconcentration column with optimized sorption and desorption conditions are novel for DNOC assay in the natural environment.

Transient intrauterine hypotension: effect on newborn rat brain.

Intrauterine perfusion failure can cause cerebral malformations. We investigated the effect of transient maternal hypotension on newborn rat brain by inducing hypovolemic hypotension for 2.5 h during early embryonic day 7 (E7) or late (E15) gestation in pregnant rats. We found an increase in the number of TUNEL-positive cells within the periventricular germinative matrix in pups subjected to early gestational hypotension and within the cerebral cortex in those subjected to late gestational hypotension in comparison to sham control animals. These results suggest that episodic maternal hypovolemic hypotension may affect the fetal brain, and apoptotic mechanisms may mediate this effect.

Modeling of Copper(II), Cadmium(II), and Lead(II) Adsorption on Red Mud from Metal-EDTA Mixture Solutions.

The adsorption of toxic heavy metal cations, i.e., Cu(II), Cd(II), and Pb(II), from metal-EDTA mixture solutions on a composite adsorbent having a heterogeneous surface, i.e., bauxite waste red mud, has been investigated and modeled with the aid of a modified surface complexation approach in respect to pH and complexant dependency of heavy metal adsorption. EDTA was selected as the modeling ligand in view of its wide usage as an anthropogenic chelating agent and abundance in natural waters. The adsorption experiments were conducted for metal salts (nitrates), metal-EDTA complexes alone, or in mixtures containing (metal+metal-EDTA). The adsorption equilibrium constants for the metal ions and metal-EDTA complexes were calculated. For all studied cases, the solid adsorbent phase concentrations of the adsorbed metal and metal-EDTA complexes were found by using the derived model equations with excellent compatibility of experimental and theoretically generated adsorption isotherms. The model was useful for metal and metal-EDTA mixture solutions either at their natural pH of equilibration with the sorbent, or after pH elevation with NaOH titration up to a certain pH. Thus adsorption of every single species (M(2+) or MY(2-)) or of possible mixtures (M(2+)+MY(2-)) at natural pH or after NaOH titration could be calculated by the use of simple quadratic model equations, once the initial concentrations of the corresponding species, i.e., [M(2+)](0) or [MY(2-)](0), were known. The compatibility of theoretical and experimental data pairs of adsorbed species concentrations was verified by means of nonlinear regression analysis. The findings of this study can be further developed so as to serve environmental risk assessment concerning the expansion of a heavy metal contaminant plume with groundwater move ment in soil consisting of hydrated-oxide type minerals. Copyright 2000 Academic Press.

Modeling the kinetics of UV/hydrogen peroxide oxidation of some mono-, di-, and trichlorophenols.

The decomposition of a number of chlorophenols (CPs), namely 2-CP, 2, 4-dichlorophenol and 2,4,6-trichlorophenol, has been studied in aqueous solution by UV-catalyzed oxidation with H(2)O(2) under UV radiation emitted by a 125-W medium pressure Hg lamp in an immersion well-type quartz photoreactor, and the organic-bound chlorine has been converted into the environmentally harmless inorganic chloride. For oxidant/CP mole ratios between 1:1 and 16:1, the reaction kinetics were modeled and the corresponding rate constants found by periodically measuring the remaining CP, hydrogen peroxide and converted chloride in solution. A theoretical model for the degradation pathway is proposed expressing the rate as a linear function of the concentrations of CP and oxidant. The rate constants for the pseudo-first order approximation of the CP degradation were compared. H(2)O(2), when combined with UV, is an effective photoactivated oxidant. The photodegradation order in terms of the initial rate of CPs destruction was: Cl(3).Ph>/=Cl(2).Ph>Cl.Ph.

A case of leukoencephalopathy with vanishing white matter.

A 6-year old Turkish boy with a recently defined entity: "leukoencephalopathy with vanishing white matter" is described. He was born to consanguinous parents. His psychomotor development was normal till he first presented with fever and generalized tonic-clonic seizures at the age of 2.5, followed by rapid motor and mental deterioration. Decerebrate posture and marked spasticity subsequently developed. The initial MRI examination showed diffuse involvement of white matter, including subcortical U-fibers, with signal intensity parallel to CSF on all sequences. The white matter appeared swollen. The ventricles were slightly enlarged and there was cavum septi pellucidi et vergae. The posterior crus of the internal capsule, external and extreme capsules were affected. Cerebellar hemispheres and vermis showed atrophy. The involvement pattern of brainstem was noteworthy in that pontine tegmentum and cruri cerebri were affected. Follow-up MRI obtained after three years did not show any interval change. Brain biopsy showed thinned cortex with relatively preserved cortical layering and neuronal structure. There was rarefaction of the white matter with cystic degeneration. Fibrillary gliosis and increased number of oligodendroglial cells were observed within the cerebral white matter.

A case of late infantile neuronal ceroid lipofuscinosis associated with precocious puberty.

Neuronal ceroid lipofuscinosis is one of the hereoffegenerative diseases for which clinical and neuropathologic findings are well documented. We present a patient with late infantile neuronal ceroid lipofuscinosis with true precocious puberty; to our knowledge, this association has not been reported before. The association could be due to an underlying disturbance of hypothalamic-pituitary gonadal function, or to coincidence.

Leigh syndrome in a 3-year-old boy with unusual brain MR imaging and pathologic findings.

We report unusual MR serial imaging and electron microscopy findings in a 3-year-old boy who had Leigh syndrome with cytochrome-c oxidase (cox) deficiency. The MR imaging findings included periventricular white matter involvement, posteroanterior progression, and extension through the corpus callosum and internal capsule; however, no basal ganglia or brain stem abnormality was found, which was suggestive of leukodystrophy. The most noteworthy findings were the cystic foci with contrast enhancement in the affected white matter.

Simultaneous derivative spectrophotometric determination of cobalt(II) and nickel(II) by dithizone without extraction.

Dithizone (Dz), a common extractive-photometric ligand for Co(II) and Ni(II), has been dissolved in the water-miscible solvent tetrahydrofurane (THF) so as to constitute a reagent for both metals in aqueous phase without extraction. Complex formation was complete for both metals at pH 12.0 (adjusted by aqueous NH(3)) within 30 min, and the complexes were stable for at least 2 h. First-derivative spectra of the metal dithizonates (singly or as binary mixtures) were preferred to ordinary spectra, because working wavelength determination was more precise and spectral overlap was less. Two wavelengths at which the spectral overlap was minimum were selected as analytical wavelengths, i.e. 620 nm for Co and 740 nm for Ni, and the calibration curves drawn with zero-to-peak values as a function of concentration were linear for these wavelengths. Thus, the total (1)D values at 620 and 740 nm of the mixtures were used to determine Co and Ni concentrations. The relative standard deviation (R.S.D.) for the analysis of Co (3.0 mg l(-1)) individually was 3.5%, and for its admixture with Ni (3.5 mg l(-1)) was 2.5%. The R.S.D. for the analysis of Ni (5.9 mg l(-1)) individually and for its admixture with Co (1.8 mg l(-1)) were 5.5 and 5.8%, respectively. The linear range in (1)D evaluation was between 5.0x10(-6) and 1.0x10(-4) M for Co and 2.0x10(-5)-2.0x10(-4) M for Ni. Interference analysis was performed for individual metal (Co or Ni) determinations. Finally, the method has been applied to a Ni-Cr-based dental alloy (Wiron 99) successfully.

Simultaneous spectrophotometric determination of cyanide and thiocyanate after separation on a melamine-formaldehyde resin.

A simple indirect spectrophotometric method for the determination of cyanide, based on the oxidation of the cyanide with chlorine (Cl(2)) is described. The residual chlorine is determined by the color reaction with o-tolidine (3,3'-dimethylbenzidine). The maximum absorbance for Cl(2) is at 437 nm. A linear calibration graph (0-4.0x10(-5) M CN(-)) is obtained under optimal reaction conditions at room temperature and pH 11-12. The stoichiometric mole ratio of chlorine to cyanide is 1:1. The effective molar absorptivity for cyanide is 5.87x10(4) l mol(-1) cm(-1) at pH 1.6. The limit of quantification (LOQ) is 3.6x10(-7) M or 9.4 ppb. Effects of pH, excess reagent, sensitivity, reaction time and tolerance limits of interferent ions are reported. The method was applied to the determination of cyanide in a real sample. The basic interferent usually accompanying CN(-), i.e. thiocyanate, is separated from cyanide by sorption on a melamine-formaldehyde resin at pH 9 while cyanide is not retained. Thiocyanate is eluted with 0.4 M NaOH from the column and determined spectrophotometrically using the acidic FeCl(3) reagent. The initial column effluent containing cyanide was analyzed by both the developed chlorine-o-tolidine method and the conventional barbituric acid-pyridine (Spectroquant 14800) procedure, and the results were statistically compared. The developed method is relatively inexpensive and less laborious than the standard (Spectroquant) procedure, and insensitive to the common interferent, cyanate (CNO(-)).

A case of paroxysmal tonic upgaze of childhood with ataxia.

Paroxysmal tonic upgaze of childhood is a rare, distinctive, childhood syndrome that may be associated with ataxia and sometimes strabismus or amblyopia. Neurological examination as well as metabolic studies, electroencephalogram and neuroradiological investigations are normal in these patients. Although it has been considered as an age-related, dopa-sensitive dystonia, the exact pathogenetic mechanism is still unknown. Aggravation of attacks by fatigue, intercurrent infection or vaccination, and possible corticomesencephalic dysmaturation may underlie this abnormality. We report on a sporadic case of paroxysmal tonic upgaze with ataxia in which there was prompt aggravation of symptoms with sleep without response to levodopa treatment. This case suggests a different underlying pathogenetic mechanism from dopaminergic pathways for this syndrome.

A case of relapsing acute disseminated encephalomyelitis with high dose corticosteroid treatment.

We report a 16-month-old boy with acute disseminated encephalomyelitis (ADEM) who had an early relapse despite prompt treatment with high dose methylprednisolone. The second episode responded to intravenous immunoglobulin (IVIg). This case illustrates the probability of relapses or treatment failures in ADEM after steroid treatment, and the use of alternative drugs.

Photocatalytic decomposition of 4-chlorophenol over oxide catalysts.

4-Chlorophenol in the presence of catalysts was decomposed in aqueous solution by a 125 W medium pressure mercury lamp in a thermostated quartz batch photoreactor, and the organic bound chlorine was catalytically converted into the environmentally less harmful inorganic chloride. Differences in the concentration of 4-chlorophenol and of the intermediates, such as hydroquinone and quinone, are followed by HPLC. The best catalyst among a homolog series for the photo-decomposition of 4-chlorophenol was selected as finely dispersed platinum oxide on a TiO2 semiconductor support, and kinetic parameters of the Langmuir-Hinshelwood type decomposition reaction were reported for the selected catalyst. A simple mechanism of substrate degradation in accord with the chosen kinetic model was postulated. The developed process may serve photooxidative removal of chlorophenols in wastewater without using costly oxidants.

Acute disseminated encephalomyelitis in childhood: report of 10 cases.

We report 10 children with the diagnosis of acute disseminated encephalomyelitis. Diagnosis was based on clinical and radiologic findings, and after acute encephalitis was excluded by negative culture and antibody results. The most common presenting symptom was ataxia, followed by optic neuropathy, cranial nerve palsy, convulsions, motor dysfunction, and loss of consciousness. Brain magnetic resonance imaging showing bilateral symmetrical hyper-intense lesions of the same age in brain stem, subcortical white matter, thalamus, basal ganglia, or cerebellum was the mainstay of the diagnosis. The presence of a preceding event (either an infection or vaccination) was present in 8 of 10 patients. Brain computed tomographic scans were abnormal in 3 of 10, and electroencephalogram was normal in all patients. High-dose corticosteroids were given to six patients, one received low-dose steroids, and the other three had symptomatic follow-up. Those who relapsed were mainly from the symptomatic follow-up group. Only one patient (the youngest) receiving high-dose methylprednisolone relapsed. Therefore, early high-dose steroid treatment seems to be the most effective treatment in acute disseminated encephalomyelitis and can prevent relapses.

Correlation between the Limiting pH of Metal Ion Solubility and Total Metal Concentration.

As an alternative to species distribution diagrams (pM vs pH curves in aqueous solution) drawn for a fixed total metal concentration, this work has developed simple linear models for correlating the limiting pH of metal ion solubility-in equilibrium with the least soluble amorphous metal hydroxide solid phase-to the total metal concentration. Thus adsorptive metal removal processes in complex systems can be better designed once the limiting pH of heavy metal solubility (i.e., pH*) in such a complex environment can be envisaged by simple linear equations. pH* vs pMt (Mt = total metal concentration that can exist in aqueous solution in equilibrium with M(OH)2(s)) linear curves for uranyl-hydroxide, uranyl-carbonate-hydroxide, and mercuric-chloride-hydroxide simple and mixed-ligand systems and cupric-carbonate-hydroxide complexes in equilibrium with mixed hydroxide solid phases may enable the experimental chemist to distinguish true adsorption (e.g., onto hydrous oxide sorbents) from bulk precipitation removal of the metal and to interpret some anomalous metal fixation data-usually attributed to pure adsorption in the literature-with precipitation if the pMt at the studied pH is lower than that tolerated by pH* vs pMt curves. This easily predictable pH* corresponding to a given pMt may aid the design of desorptive mobilization experiments for certain metals as well as their adsorptive removal with the purpose of simulating metal adsorption and desorption cycles in real complex environments with changing groundwater pH. Copyright 1999 Academic Press.

Cardiac dysrhythmia that simulates seizure disorder in two children.

Cardiac dysrhythmia can present signs and symptoms of a seizure disorder and sometimes they are clinically indistinguishable. We present two children with a presumed seizure disorder but also with an underlying and associated cardiac problem. Therefore, we suggest that both conditions must be considered concomitantly, and that each patient with a newly diagnosed seizure disorder requires both neurological and cardiological evaluation.

Hepatitis as the presenting symptom of childhood systemic lupus erythematosus.

We report in this article a girl with an initial diagnosis of autoimmune hepatitis who developed full-blown systemic lupus erythematosus (SLE) at her two-years follow-up. She was formerly considered as HBV-related chronic active hepatitis but due to the persistence of elevated liver enzymes, the reversal of the albumin and globulin ratio and abnormal HBV serology, she was later diagnosed as autoimmune hepatitis. With the clinical findings of arthritis, arthralgia and malar rash and supported by results of laboratory tests, she was diagnosed as a case of unusual SLE presenting with autoimmune hepatitis. We conclude, therefore, that each patient with a diagnosis of autoimmune hepatitis in childhood who exhibits abnormal HBV serology must be evaluated for a possible diagnosis of SLE.

Preoperative use of octreotide in a newborn with persistent hyperinsulinemic hypoglycemia of infancy.

In this paper, we describe a newborn diagnosed with persistent hyperinsulinemic hypoglycemia of infancy (PHHI) at two days of age. She presented with severe asymptomatic hypoglycemia and required both a high rate of glucose infusion and diazoxide treatment. On the 9th hospital day, due to persistent and intractable hypoglycemia, subcutaneous octreotide treatment was initiated. This treatment reduced the rate and concentration of glucose needed to be infused but the hypoglycemia did not subside totally. On the 18th hospital day near-total pancreatectomy was performed. Tachyphylaxis resulting from continuous use of octreotide limited its effect but enabled us to keep the patient euglycemic preoperatively.