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1.
Clin Radiol ; 79(9): 711-717, 2024 Sep.
Article in English | MEDLINE | ID: mdl-38960753

ABSTRACT

AIM: The challenges posed by the assessment of elderly trauma patients increase the reliance on emergency CT scanning to diagnose an injury. The COVID-19 pandemic posed challenges to image service delivery. We sought to assess the effect of the COVID-19 pandemic on the imaging of elderly trauma. MATERIALS AND METHODS: All trauma patients aged 65 and over who underwent whole-body CT scanning in the same 3-month period (April-June) in 2019 and 2022 were included in our study. Data was collected on demographics, time of scanning, clinical request details and positive report findings. Anatomical injury distribution, abbreviated injury scale (AIS) and injury severity scores (ISS) were calculated. Consensus judgment was obtained on scan justification and significance of findings. Chi-squared test of association was applied to the categorical outcomes of interest. Associations were considered significant if p<0.05. RESULTS: 79 patients were scanned in the pre-pandemic assessment period versus 217 post-pandemic, an increase of 175%, including a 248% rise in fall-from-standing requests. There was a statistically significant reduction of trauma CT requests meeting fulfilment criteria post-pandemic (95% vs 83%) (p=0.008), with significantly fewer positive findings (45.6% vs 29%) (p=0.024). There was a decrease in median ISS score in the post-pandemic group (p=0.062). CONCLUSION: Despite increased scanning, there was a reduction in both the number and severity of positive traumatic imaging findings. The pandemic has increased reliance on CT without a concomitant increase in the detection of positive findings nor clinically significant findings. This single-centre study demonstrates the need to further evaluate pan-CT trauma scanning in silver trauma patients.


Subject(s)
COVID-19 , Hospitals, Teaching , SARS-CoV-2 , Tomography, X-Ray Computed , Wounds and Injuries , Humans , COVID-19/epidemiology , COVID-19/diagnostic imaging , Aged , Female , Male , Tomography, X-Ray Computed/methods , Aged, 80 and over , Wounds and Injuries/diagnostic imaging , Pandemics , Injury Severity Score , Whole Body Imaging/methods , Retrospective Studies
2.
Ultrasound ; 30(2): 117-125, 2022 May.
Article in English | MEDLINE | ID: mdl-35509302

ABSTRACT

Introduction: The Achilles tendon is the most frequently ruptured tendon. Prompt diagnosis of this injury ensures optimal management decisions are instituted early ensuring the best outcome and patient experience, at minimal cost to the United Kingdom National Health Service. Despite this, regional and national variations to diagnosis and management exist, with anecdotal evidence of inefficiencies in the local patient pathway. To explore this further, a retrospective departmental audit of timescales from presentation to ultrasound diagnosis and definitive treatment decision was undertaken. Methods: All suspected Achilles tendon ruptures in 2018 were identified through electronic and written patient records, and information on timescales involved in the diagnosis and management of each compiled. Descriptive statistics were used to map each step of the pathway and timescales involved, with performance assessed against local departmental standards and the Swansea Morriston Achilles Rupture Treatment (SMART) protocol. Results: In total, 119 patients were identified, of which 113 received an ultrasound examination. Local departmental standards were met in the majority of cases, with 78% (n = 88) diagnosed by ultrasound within one week of the request and 83% (n = 91) given a treatment decision within two weeks of presentation. However, this was suboptimal when compared with timeframes utilised for developing the SMART protocol, with only 7% (n = 8) scanned within 48 hours of presentation. Conclusions: Key areas of the patient pathway were identified for quality service improvement and redesign, with multidisciplinary discussion resulting in the development of a revised patient pathway which expedites diagnosis and treatment for these injuries.

3.
Biosystems ; 196: 104186, 2020 Oct.
Article in English | MEDLINE | ID: mdl-32535178

ABSTRACT

Membrane computing is a computational paradigm inspired by the structure and behavior of a living cell. P Systems are the computing devices that are used to realize membrane computing models. Numerous theoretical studies on many variants of P Systems have shown them to be computationally universal. There is a wide range of applications of P Systems from modeling of biological processes to image processing. Among many variants of P Systems, one of the most important is Enzymatic Numerical P System (ENPS). ENPS is a class of P System in which membranes operate on numerical values. To realize the power of ENPS there are a few simulators developed. Each and every simulator has some advantages as well as some disadvantages. Here, a GPU based simulator using Python as a user interaction language is developed. This tool is a completely parallel variant, compatible with a Python based sequential simulator (PeP) which was the first Python based work for ENPS. The developed simulator uses CUDA to interact with GPU and gives the desired speed up, while processing the membranes. There are two important case studies which show the performance of the developed tool to be far better than the other serial simulators.


Subject(s)
Cell Membrane/enzymology , Computational Biology/methods , Computer Simulation , Programming Languages , Animals , Humans
4.
Biosystems ; 189: 104067, 2020 Mar.
Article in English | MEDLINE | ID: mdl-31712063

ABSTRACT

P System or Membrane Computing is an unconventional and natural computing model inspired by the functioning of a living cell. This model has an inherently parallel structure. There are several variants of P System developed, each of which has a different application. One of the variants, Enzymatic Numerical P System (ENPS), has primarily been developed to be used with numerical values (as in economics) and thus has vast applications. For realizing ENPS there are several tools available, primarily based on Java and Python, each of which has a different input format. Currently, there is no tool which allows the user to execute ENPS using both the simulators on the same platform, the issue being inter-conversion between input formats, namely, XML and PeP (specific format designed for Python based ENPS). Another major issue with existing simulators is their inability to allow multiple membrane systems to be executed and there is no facility for interconnection between two membrane systems. A tool developed here solves both problems namely, file inter-conversion and multiple membrane support by transferring dependent variable values automatically according to users' choice. The tool is developed using Python 3.0 and has only a few dependencies. The tool is tested under different scenarios and the results confirm the correctness of the tool.


Subject(s)
Algorithms , Cell Membrane/enzymology , Computer Simulation , Cell Membrane/genetics , Enzyme Assays/methods
5.
Article in English | MEDLINE | ID: mdl-26123515

ABSTRACT

Fluconazole is an efficient antifungal drug used in the treatment and prevention of superficial and systemic fungal infections. The molecular structure, fundamental vibrational wavenumber and intensity of the vibrational bands are interpreted, aided by density functional theory method. The results of the calculations were applied to simulated spectra of the title compound, which show excellent agreement with observed spectra. The vibrational analysis of the title compound has been carried out using FT-IR and FT-Raman spectra. Stability of the molecule arising from hyperconjugative interactions and charge delocalization has been analyzed using natural bond orbital analysis. The present investigation is extended to calculate the HOMO-LUMO energy gap, polarizability, Mulliken charges and thermodynamical properties of fluconazole at different temperature. The calculated HOMO-LUMO energy gap shows that the charge transfer occurs within the molecule. The frontier orbital and molecular electrostatic potential surface studies have been employed to understand the active sites of fluconazole. Nonlinear optical properties related to polarizability and hyperpolarizability are also discussed. The absorption characteristics and solvent analysis of fluconazole have been made using UV-Vis spectroscopic method.


Subject(s)
Antifungal Agents/chemistry , Fluconazole/chemistry , Models, Molecular , Molecular Conformation , Spectrophotometry, Ultraviolet , Spectroscopy, Fourier Transform Infrared , Spectrum Analysis, Raman , Static Electricity , Thermodynamics
6.
J Biosci ; 38(4): 741-7, 2013 Nov.
Article in English | MEDLINE | ID: mdl-24287654

ABSTRACT

Casuarina equisetifolia Forst. is a tree crop that provides fuel wood, land reclamation, dune stabilization, and scaffolding for construction, shelter belts, and pulp and paper production. C. equisetifolia fixes atmospheric nitrogen through a symbiotic relationship with Frankia, a soil bacterium of the actinobacteria group. The roots of C. equisetifolia produce root nodules where the bacteria fix atmospheric nitrogen, which is an essential nutrient for all plant metabolic activities. However, rooted stem cuttings of elite clones of C. equisetifolia by vegetative propagation is being planted by the farmers of Pondicherry as costeffective method. As the vegetative propagation method uses inert material (vermiculite) for rooting there is no chance for Frankia association. Therefore after planting of these stocks the farmers are applying 150 kg of di-ammonium phosphate (DAP)/acre/year. To overcome this fertilizer usage, the Frankia-inoculated rooted stem cuttings were propagated under nursery conditions and transplanted in the nutrient-deficient soils of Karaikal, Pondicherry (India), in this study. Under nursery experiments the growth and biomass of C. equisetifolia rooted stem cuttings inoculated with Frankia showed 3 times higher growth and biomass than uninoculated control. These stocks were transplanted and monitored for their growth and survival for 1 year in the nutrient-deficient farm land. The results showed that the rooted stem cuttings of C. equisetifolia significantly improved growth in height (8.8 m), stem girth (9.6 cm) and tissue nitrogen content (3.3 mg g-1) than uninoculated controls. The soil nutrient status was also improved due to inoculation of Frankia.


Subject(s)
Fagaceae/growth & development , Frankia/physiology , Plant Stems/growth & development , Root Nodules, Plant/microbiology , Soil Microbiology , Fagaceae/microbiology , Nitrogen/metabolism , Nitrogen Fixation/physiology , Plant Stems/microbiology , Root Nodules, Plant/growth & development , Soil/chemistry , Symbiosis
7.
Ir J Med Sci ; 182(4): 697-701, 2013 Dec.
Article in English | MEDLINE | ID: mdl-23645548

ABSTRACT

AIMS: To study the nature of the tumours managed in the Irish population. METHODS: This audit research was completed via a retrospective medical review on 200 patients with CNS tumours managed in a tertiary care centre between 2008 and 2009. RESULTS: The mean age was 53 years. The male:female ratio was 2:1. The majority were glioblastomas and astrocytomas. Grade IV tumours were predominant (65.5 %). Headaches (37 %), motor weakness (32 %) and seizures (25.5 %) were the highest presentations. The commonest sites affected were the left parietal and left temporal lobes. There were 17.5 % operative morbidities with motor weakness (22.9 %), seizure (14.3 %) and thrombo-embolism (14.3 %) dominating and significant association to surgical radicality (p = 0.041). 3.5 % operative mortalities were reported. 52.5 and 62.5 % of patients received adjuvant chemotherapy and radiotherapy, respectively. CONCLUSIONS: Patients with CNS tumours typically had multiple presentations. More extensive surgical resection was associated with higher postoperative morbidities (p = 0.041). The 30-day postoperative morbidity (17.5 %) and mortality (3.5 %) were concordant with the currently available literature.


Subject(s)
Astrocytoma/surgery , Central Nervous System Neoplasms/surgery , Glioblastoma/surgery , Neurosurgical Procedures , Adolescent , Adult , Aged , Aged, 80 and over , Astrocytoma/complications , Astrocytoma/mortality , Central Nervous System Neoplasms/complications , Central Nervous System Neoplasms/mortality , Chemotherapy, Adjuvant , Child , Child, Preschool , Female , Glioblastoma/complications , Glioblastoma/mortality , Headache/etiology , Humans , Infant , Ireland , Male , Medical Audit , Middle Aged , Motor Neuron Disease/etiology , Neoplasm Grading , Neurosurgical Procedures/adverse effects , Neurosurgical Procedures/mortality , Radiotherapy, Adjuvant , Retrospective Studies , Seizures/etiology , Tertiary Care Centers , Thromboembolism/etiology , Treatment Outcome , Young Adult
8.
Indian Pediatr ; 48(4): 333-4, 2011 Apr.
Article in English | MEDLINE | ID: mdl-21532108

ABSTRACT

After one year of antiretroviral treatment in 49 HIV infected children compared to 53 children without, weight for age improved significantly and was highly correlated with baseline immune status and CD4% increase but height for age did not change. Stunting is a common feature of pediatric HIV, both on and off HAART.


Subject(s)
Antiretroviral Therapy, Highly Active/adverse effects , Growth Disorders/chemically induced , Growth Disorders/virology , HIV Infections/complications , HIV Infections/drug therapy , Anti-HIV Agents/adverse effects , Anti-HIV Agents/therapeutic use , Body Height , Body Mass Index , Body Weight , Child , Child, Preschool , Cohort Studies , Humans , India/epidemiology
9.
Talanta ; 81(1-2): 462-72, 2010 Apr 15.
Article in English | MEDLINE | ID: mdl-20188947

ABSTRACT

A simple and efficient method for the determination of ultra-trace amounts of inorganic mercury (iHg) and methylmercury (MeHg) in waters and fish tissues was developed using a micro-column filled with polyaniline (PANI) coupled online to flow injection-chemical vapour generation-inductively coupled plasma mass spectrometry (FI-CVG-ICPMS) system. Preliminary studies indicated that inorganic and methyl mercury species could be separated on PANI column in two different speciation approaches. At pH <3, only iHg could be sorbed and almost no adsorption of MeHg was found (speciation procedure 1). If the sample solution pH is approximately 7, both MeHg and iHg species could be sorbed on the PANI column. Subsequently both the Hg species were selectively eluted with 2% HCl and a mixture of 2% HCl and 0.02% thiourea respectively (speciation procedure 2). The adsorption percentage of iHg on the PANI column was unchanged even with acidity of the sample solution increased to 6 mol L(-1). Therefore, an acidic solution (5 mol L(-1) HCl), used for ultra-sound assisted extraction of the mercury species from biological samples, was used directly to separate MeHg from iHg in the fish tissues (tuna fish ERM-CE 463, ERM-CE 464 and IAEA-350) by PANI column using speciation procedure 1. The determined values were in good agreement with certified values. Under optimal conditions, the limits of detection (LODs) were 2.52 pg and 3.24 pg for iHg and MeHg (as Hg) respectively. The developed method was applied successfully to the direct determination of iHg and MeHg in various waters (tap water, lake water, ground water and sea-water) and the recoveries for the spiked samples were in the range of 96-102% for both the Hg species.


Subject(s)
Aniline Compounds/chemistry , Fishes , Mass Spectrometry , Methylmercury Compounds/analysis , Methylmercury Compounds/chemistry , Online Systems , Water/chemistry , Analytic Sample Preparation Methods , Animals , Buffers , Chemical Fractionation , Flow Injection Analysis , Hydrochloric Acid/chemistry , Hydrogen-Ion Concentration , Indicators and Reagents/chemistry , Mercury/analysis , Mercury/chemistry , Mercury/isolation & purification , Methylmercury Compounds/isolation & purification , Tuna , Ultrasonics , Volatilization
10.
Int J Pediatr ; 2009: 837627, 2009.
Article in English | MEDLINE | ID: mdl-20041007

ABSTRACT

Background. Growth failure is a common feature of children with human immunodeficiency virus (HIV) infection. Malnutrition increases mortality and may impair the response to antiretroviral treatment. Objective. Our objective was to describe the prevalence of stunting, underweight, and wasting in HIV-infected children in south India and to assess the utility of these parameters in predicting immune status. Methodology. In this cross-sectional study, anthropometric measurements and CD4 counts were performed on 231 HIV-infected children. Z scores for height for age, weight for age, and weight for height were correlated with CD4 cell counts and receiver operating characteristic curves plotted. Results. Prevalence of underweight was 63%, stunting 58%, and wasting 16%, respectively. 33-45% of children were moderately or severely malnourished even at CD4 >25%; sensitivity and specificity of stunting or underweight to predict HIV disease severity was low. Conclusions. Undernutrition and stunting are common among HIV-infected children at all stages of the disease in India. Early and aggressive nutritional intervention is required, if long-term outcomes are to be improved.

11.
Talanta ; 79(5): 1454-63, 2009 Oct 15.
Article in English | MEDLINE | ID: mdl-19635384

ABSTRACT

The applicability of polyaniline (PANI) for the on-line preconcentration and recovery of palladium from various water samples has been investigated. Batch experiments were performed to optimize conditions such as pH and contact time to achieve quantitative separation of Pd spiked at high (microg ml(-1)) and low levels (ng ml(-1)). During all the steps of the removal process, it was found that Pd was selectively removed by PANI even in the presence of various ions. Quantitative removal of Pd occured in the entire studied pH range (1-12) and the K(d) value was found to be >10(6). Kinetic studies show that a contact time of <4 min was adequate to reach equilibrium. The retained Pd was subsequently eluted with a mixture of HCl and thiourea, optimized using a factorial experimental design approach. ICP-OES was used for the micro-level determinations of Pd whereas ICP-MS was used for the determination of Pd at sub-ppb levels. Breakthrough curve using column experiments demonstrated that PANI has an excellent ability to accumulate up to approximately 120 mg g(-1) of Pd from synthetic sample solutions. A preconcentration factor of about 125 was achieved for Pd when 250 ml of water was passed. PANI columns prepared were used up to 10 times in consecutive retention-elution cycles without appreciable deterioration in their performance. The proposed on-line method also has the ability to remove interfering elements Cu and Y for the determination of Pd in waters by ICP-MS. The reported method has been applied successfully for the determination of Pd in ground water, lake water sea-water and waste water samples. The recoveries were found to be >95% in all cases. These studies indicate that PANI has an excellent ability to preconcentrate Pd from various waters making the method very promising for the determination of Pd.


Subject(s)
Aniline Compounds/isolation & purification , Palladium/isolation & purification , Water Pollutants, Chemical/isolation & purification , Hydrogen-Ion Concentration , Mass Spectrometry/instrumentation , Mass Spectrometry/methods , Mass Spectrometry/standards
12.
Am J Transplant ; 9(1): 132-9, 2009 Jan.
Article in English | MEDLINE | ID: mdl-19067662

ABSTRACT

The aim of this study was to assess the patterns, predictors and outcomes of left ventricular remodeling after heart transplantation (HTX). Routine echocardiographic studies were performed and analyzed at 1 week, 1 year and 3-5 years after HTX in 134 recipients. At each study point the total cohort was divided into three subgroups based on determination of left ventricle mass and relative wall thickness: (1) NG-normal geometry (2) CR-concentric remodeling and (3) CH-concentric hypertrophy. Abnormal left ventricular geometry was found as early as 1 week after HTX in 85% of patients. Explosive mode of donor brain death was the most significant determinant of CH (OR 2.9, p = 0.01) at 1 week. CH at 1 week (OR 2.72, p = 0.01), increased body mass index (OR 1.1, p = 0.01) and cytomegalovirus viremia (OR - 4.06, p = 0.02) were predictors of CH at 1 year. CH of the cardiac allograft at 1 year was associated with increased mortality as compared to NG (RR 1.87, p = 0.03). CR (RR 1.73, p = 0.027) and CH (RR 2.04, p = 0.008) of the cardiac allograft at 1 year is associated with increased subsequent graft arteriosclerosis as compared to NG.


Subject(s)
Coronary Vessels/physiopathology , Heart Transplantation , Survival Rate , Ventricular Remodeling , Adult , Cohort Studies , Electrocardiography , Female , Humans , Male , Middle Aged , Transplantation, Homologous
13.
J Cardiovasc Electrophysiol ; 19(4): 362-6, 2008 Apr.
Article in English | MEDLINE | ID: mdl-18284509

ABSTRACT

BACKGROUND: Catheter ablation for atrial fibrillation (AF) can increase risk of left atrial (LA) thrombi and stroke. Optimal periprocedural anticoagulation has not been determined. OBJECTIVE: We report the role of administering warfarin and aspirin without low molecular weight heparin in patients undergoing AF ablation. METHODS: A total of 207 patients underwent ablation for AF. Transesophageal echocardiography (TEE) guided transseptal puncture and ruled out clot in the LA. After first puncture, the sheath was flushed with heparin (5,000 Units/mL). After second puncture, a bolus of 80 units/kg of heparin was given, followed by an infusion to maintain activated clotting time (ACT) around 300-350 seconds. Warfarin was stopped and aspirin was started (325 mg/day) 3 days preprocedure. Warfarin was restarted on the day of the procedure. Both medications were continued for 6 weeks postablation. Warfarin was continued for 6 months in patients with prior history of persistent or recurrent AF. Thirty-seven patients who showed smoke in the LA on TEE were given low molecular weight heparin postprocedure until international normalized ratio (INR) was therapeutic. RESULTS: Thirty-two patients had persistent and 175 had paroxysmal AF; 87 were cardioverted during ablation. Two patients had transient ischemic attack (TIA) on the sixth and eighth days, respectively, following ablation, with complete recovery. Both had subtherapeutic INRs. CONCLUSION: In patients without demonstrable clot or smoke in the LA, starting aspirin 3 days prior and warfarin immediately post-radiofrequency ablation, without low molecular weight heparin, with meticulous anticoagulation during the procedure, appears to be a safe mode of anticoagulation.


Subject(s)
Anticoagulants/administration & dosage , Atrial Fibrillation/epidemiology , Atrial Fibrillation/surgery , Catheter Ablation/statistics & numerical data , Premedication/statistics & numerical data , Risk Assessment/methods , Thrombosis/epidemiology , Thrombosis/prevention & control , Comorbidity , Female , Heart Diseases/epidemiology , Heart Diseases/prevention & control , Humans , Intraoperative Care/statistics & numerical data , Male , Middle Aged , Postoperative Complications/epidemiology , Risk Factors , Wisconsin/epidemiology
14.
Indian J Med Res ; 123(6): 788-98, 2006 Jun.
Article in English | MEDLINE | ID: mdl-16885601

ABSTRACT

BACKGROUND & OBJECTIVES: Data on infectious diseases like tuberculosis (TB) have been analyzed in the past without giving adequate attention to spatial variations. Earlier studies also attempted to display disease status of sub regions, usually census tracts, by categorizing them into quartiles, that helps the authorities to identify high- or low-risk areas. This approach is based mainly on binomial and Poisson models for disease data, and the recent attempts focus on using mixture models of Poisson distribution. We carried out this study to find wards of Madurai Corporation having high risks for TB disease, to develop a model of mixture of Poisson distributions for the number of cases and to classify each ward to one of many risk groups for TB disease, and to represent spatial distribution of TB incidence in Madurai city. METHODS: produced the observed counts of TB patients in 72 wards of Madurai Corporation. The number of risk groups and the Poisson parameters of each group were found by maximum likelihood approach using the computer package C.A.MAN (Computer Assisted Mixture ANalysis). Bayesian methods were used to associate each ward to a particular risk group. The results were geographically presented in maps by using ArcView mapping software. RESULTS: Using binomial model, 26 wards were categorized as high risk wards, and with mixture model approach 15 wards showed standardized morbility ratio (SMR) >1. The wards along river Vaigai and densely populated wards had high risk. INTERPRETATION & CONCLUSION: Our findings demonstrate the usefulness of the mixture models for disease data with geographical variations.


Subject(s)
Demography , Models, Statistical , Risk Assessment/methods , Tuberculosis, Pulmonary/epidemiology , Bayes Theorem , Cities/epidemiology , Geography , Humans , Incidence , India/epidemiology , Likelihood Functions , Poisson Distribution
15.
Circulation ; 111(5): 546-54, 2005 Feb 08.
Article in English | MEDLINE | ID: mdl-15699274

ABSTRACT

BACKGROUND: Although segmental or circumferential ablation is effective in eliminating pulmonary vein (PV)-mediated atrial fibrillation (AF), this procedure may be complicated by the occurrence of PV stenosis. METHODS AND RESULTS: To establish the clinical presentation, diagnostic manifestations, and interventional management of PV stenosis, 23 patients with stenosis of 34 veins complicating ablation of AF were evaluated. Each patient became symptomatic 103+/-100 days after undergoing ablation. In 8 veins, the ablation producing the PV stenosis was a repeated procedure for continued AF. Nineteen patients presented with dyspnea on exertion, 7 with dyspnea at rest, 9 with cough, and 6 with chest pain. On multirow spiral computed tomography examination, the narrowest lumen of the affected PVs measured 3+/-2 mm compared with 13+/-3 mm at baseline (P< or =0.001). The relative perfusion of affected lung segments on isotope scans was reduced to 4+/-3% of total perfusion compared with 22+/-10% in unaffected segments. At percutaneous intervention, these veins showed 80+/-13% stenosis, with a mean gradient of 12+/-5 mm Hg. This was significantly reduced to a residual stenosis of 9+/-8% (P< or =0.001) and a residual gradient of 3+/-4 mm Hg (P< or =0.001). Twenty veins were treated with balloon dilatation alone, whereas 14 veins were stented with standard 10-mm-diameter bare-metal stents. Although the symptomatic response was nearly immediate and impressive, 14 patients developed in-stent or in-segment restenosis, requiring repeated interventions in 13. CONCLUSIONS: Percutaneous intervention produces rapid and dramatic symptom relief in patients with highly symptomatic PV stenosis after radiofrequency ablation for AF. Nevertheless, alternative treatment methods will be required to decrease recurrent in-stent or in-segment restenosis.


Subject(s)
Atrial Fibrillation/surgery , Catheter Ablation , Pulmonary Veins/surgery , Pulmonary Veno-Occlusive Disease/diagnosis , Pulmonary Veno-Occlusive Disease/therapy , Adult , Atrial Fibrillation/complications , Constriction, Pathologic/diagnosis , Constriction, Pathologic/etiology , Constriction, Pathologic/therapy , Echocardiography, Transesophageal , Female , Follow-Up Studies , Humans , Male , Middle Aged , Pulmonary Veins/diagnostic imaging , Pulmonary Veno-Occlusive Disease/etiology , Tomography, X-Ray Computed
16.
Talanta ; 65(1): 135-43, 2005 Jan 15.
Article in English | MEDLINE | ID: mdl-18969775

ABSTRACT

The possibility of using moss (Funaria hygrometrica), immobilized in a polysilicate matrix as substrate for speciation of Cr(III) and Cr(VI) in various water samples has been investigated. Experiments were performed to optimize conditions such as pH, amount of sorbent and flow rate, to achieve the quantitative separation of Cr(III) and Cr(VI). During all the steps of the separation process, Cr(III) was selectively sorbed on the column of immobilized moss in the pH range of 4-8 while, Cr(VI) was found to remain in solution. The retained Cr(III) was subsequently eluted with 10ml of 2moll(-1) HNO(3). A pre-concentration factor of about 20 was achieved for Cr(III) when, 200ml of water was passed. The immobilized moss was packed in a home made mini-column and incorporated in flow injection system for obtaining calibration plots for both Cr(III) and Cr(VI) at low ppb levels that were compared with the plots obtained without column. After separation, the chromium (Cr) species were determined by inductively coupled plasma mass spectrometry (ICP-MS) and flame atomic absorption spectrometry (FAAS). The sorption capacity of the immobilized moss was found to be approximately 11.5mgg(-1) for Cr(III). The effect of various interfering ions has also been studied. The proposed method was applied successfully for the determination of Cr(III) and Cr(VI) in spiked and real wastewater samples and recoveries were found to be >95%.

17.
J Chromatogr A ; 1050(2): 223-7, 2004 Oct 01.
Article in English | MEDLINE | ID: mdl-15508316

ABSTRACT

In situ matrix evaporation of high-purity acids based on isothermal distillation was achieved in a high-density polyethylene (HDPE) container on a water bath, to avoid contamination from the laboratory environment. The solubility of water and acid vapours in glycerol due to co-association was utilized to achieve complete evaporation. All major sources which contribute to the process blank were taken care of in a simple and effective way. A 50-fold preconcentration with >99.9% matrix removal was achieved for the analysis of low-boiling acids, HCl, HF, HNO3 and H2O2. The non-volatile ions NH4+, Li+, Na+, K+, Mg2+, Ca2+, SO4(2-) and PO4(3-) were determined by ion chromatograph with conductivity detection. The detection limits were 6-130 ng/l with recoveries of 85-110% for all ions studied.


Subject(s)
Indicators and Reagents/chemistry , Chromatography, Ion Exchange , Polyethylenes , Reproducibility of Results , Thermodynamics
18.
J Chromatogr A ; 1036(2): 223-7, 2004 May 21.
Article in English | MEDLINE | ID: mdl-15146925

ABSTRACT

Trace levels of phosphorus in purified quartz are determined by ion chromatography. In situ reagent purification, matrix digestion and oxidation of phosphorus to orthophosphate ion are carried out simultaneously in a vapour phase digestion (VPD) assembly using a mixture of HF, HNO3 and H2O2. A drastic reduction (475 times) in phosphate blank from reagents (HF/H2O2) was achieved in the VPD through in situ purification of the reagent. The residues remaining after volatilisation (solvent/matrix), mostly consisting of insoluble phosphate/fluoride salts of divalent and trivalent cations, were solubilised by ion-exchange dissolution. Phosphate was analysed on the IonPac AS17 column with suppressed conductivity detection. The results of the ion chromatography (IC) method were compared with a spectrophotometric method. Accuracy was evaluated by analysing a certified reference material (silicon, NIST 57a). The method detection limit was 0.05 microg g(-1).


Subject(s)
Chromatography, Liquid/methods , Phosphorus/analysis , Quartz/chemistry , Indicators and Reagents , Reference Standards
20.
J Chromatogr A ; 1022(1-2): 25-31, 2004 Jan 02.
Article in English | MEDLINE | ID: mdl-14753768

ABSTRACT

A method has been developed for the determination of relevant trace impurities (alkali, alkaline and transition metals) in high purity quartz by ion-chromatography. In situ reagent (HF) purification and simultaneous sample dissolution was achieved in a multichannel vapour phase digestion assembly. Twenty-one samples can be digested at a time in this vapour phase system. Significant decrease in the process blank levels for all the analytes was observed. Drastic reduction (250 times) of NH4+ blank was achieved in the described vapour phase digestion, which enables the determination of trace concentration of sodium in high purity quartz. After volatilisation of the matrix and unreacted HF, the clear water leached solutions were injected into an ion-chromatograph equipped with conductivity detector for the determination of alkali and alkaline earth metals. In the case of transition metals, the trace residues were leached with 10 mM HCl and after separation on a mixed bed analytical column (IonPac CS5) were detected by spectrophotometry after post column derivatisation using 4-(2-pyridylazo)resorcinol (PAR). The accuracy of the result was checked by their comparison with those obtained by independent methods like inductively coupled plasma (ICP) MS and ICP atomic emission spectrometry. The achievable detection limits are between 0.4 ng/g (Li) and 22 ng/g (Mn). The application of the method to the determination of the above trace metals in two high-purity-grade quartz samples is demonstrated.


Subject(s)
Chromatography, Liquid/methods , Metals/analysis , Quartz/chemistry , Trace Elements/analysis , Reproducibility of Results , Sensitivity and Specificity
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