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1.
S Afr Med J ; 112(5): 328-334, 2022 04 30.
Artigo em Inglês | MEDLINE | ID: mdl-35587245

RESUMO

BACKGROUND: The paediatric HIV treatment programme in South Africa (SA) has grown since its inception in 2004. Despite this impressive scale-up of antiretroviral therapy (ART) in children, the proportion of children started on ART and retained in care remains unacceptably low, with only 47% of the 340 000 HIV-positive children in SA on ART in 2020. Johannesburg is one of the districts in SA with the largest number of children living with HIV who are not on ART, and is a priority district for paediatric case finding and retention. OBJECTIVES: To describe the dynamics of the paediatric HIV programme in Johannesburg, SA. METHODS: A secondary analysis was conducted on patient-level HIV treatment data from TIER.Net, the nationally mandated HIV/ART database. Children aged <15 years who received ART between January 2004 and June 2019 at public health facilities in Johannesburg were included. We reported the number of children on ART and the number who entered and exited the programme by age group over time, and analysed the trends of these indicators. RESULTS: By December 2018, 7 630 children aged <15 years remained in Johannesburg's paediatric ART programme: 82.5% were aged 5 - <15 years, with 54.1% of these being 10 - <15 years old. During the study period, 19 850 children were newly initiated on ART. New initiations slowed from 2013, to range from 1 172 to 1 373 yearly. In 2018, 34.2% of initiators were aged <1 year, 24.2% 1 - <5 years and 41.6% 5 - <15 years. Despite these initiations, the number of children on ART only grew by 97 in 2018, owing to programme losses. In 2018, 924  children (12.1%) aged out, 35 (0.5%) died and 983 (12.9%) were lost to follow-up (LTFU), the latter having increased from 10.7% in 2017. Of children who aged out of the paediatric ART programme, 56.3% remained in care at the same facility. CONCLUSION: Early in the SA ART roll-out, many children were found to be HIV infected and started on ART. This number started to slow in 2013, after which the growth rate of the paediatric HIV programme also began to slow. Scale-up of methods for identifying older children with HIV is needed. While ageing out of the paediatric programme is a consideration, the number of children LTFU remains unacceptably high. Further interrogation of barriers to paediatric retention is needed to help realise the Joint United Nations Programme on HIV and AIDS (UNAIDS) 90:90:90 goals for children in SA.


Assuntos
Fármacos Anti-HIV , Infecções por HIV , Adolescente , Fármacos Anti-HIV/uso terapêutico , Criança , Infecções por HIV/tratamento farmacológico , Infecções por HIV/epidemiologia , Humanos , Perda de Seguimento , Estudos Retrospectivos , África do Sul/epidemiologia , Nações Unidas
2.
Int Urol Nephrol ; 48(4): 511-5, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26790883

RESUMO

PURPOSE: To evaluate the accuracy of estimated glomerular filtration rate (eGFR) against the reference standard of isotopic GFR (iGFR) in monitoring renal function during follow-up after cystectomy and urinary diversion. METHODS: Patients who had undergone cystectomy and ileal conduit urinary diversion at two centres between August 2001 and August 2006 were identified. eGFR calculated using the MDRD formula was compared to (51)Cr EDTA measured iGFR values measured at similar time-points during follow-up. RESULTS: Six hundred and fourteen paired iGFR and eGFR results were analysed from 166 patients (18% female, median age 70 years). There was a significant difference between paired iGFR and eGFR measurements (p < 0.0001) with a mean bias of +1.8 mls/min/1.73 m(2) (SD 18.0) and a 95% limit of agreement of -33.5 to 37.2 mls/min/1.73 m(2). iGFR and eGFR values converged at a GFR of approximately 45 mls/min/1.73 m(2). 70.6% of patients experienced a loss of renal function greater than expected (>0.58 mls/min/1.73 m(2)/year). In 22.4% of these patients, a decline of greater than 10% in iGFR occurred that was undetected by eGFR measurements, which overestimated GFR. There was no significant relationship between patient height, weight or body mass index and the accuracy of eGFR measurements. CONCLUSIONS: iGFR measurement is recommended following ileal conduit urinary diversion if early signs of renal function loss are to be detected. eGFR overestimates GFR in critically relevant ranges and fails to detect loss in a clinically significant proportion of patients.


Assuntos
Cistectomia/métodos , Taxa de Filtração Glomerular/fisiologia , Rim/fisiopatologia , Neoplasias da Bexiga Urinária/cirurgia , Derivação Urinária/métodos , Adulto , Idoso , Idoso de 80 Anos ou mais , Creatinina/sangue , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Período Pós-Operatório , Prognóstico , Estudos Retrospectivos , Fatores de Tempo , Neoplasias da Bexiga Urinária/sangue , Neoplasias da Bexiga Urinária/fisiopatologia
3.
Eur J Surg Oncol ; 39(10): 1157-63, 2013 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-23886896

RESUMO

BACKGROUND AND OBJECTIVES: A relatively unknown associations exists between the detection, progression and rate of interventions in small renal masses in the context of socioeconomic status. The study explored the impact of socioeconomic status on the detection, progression and intervention rate in SRMs. PARTICIPANTS AND METHODS: A population-based cohort of patients with SRMs was identified using various hospital databases in well-defined geographical area between January 2007 and December 2011. A list of patients with unique 10-digits Community Health Index (CHI) number and their follow-up was recorded on a pre-designed electronic database sheet. Correlation between the socioeconomic status and detection, progression and pattern of interventions of small renal masses was the primary outcome. The postcode of each patient was identified and linked to the Scottish Index of Multiple Deprivation (SIMD) scoring system, and a deprivation category number assigned to each patient, allowing potential links to become apparent between small renal masses and deprivation. RESULTS: Two hundred and seventeen patients were diagnosed with small renal masses in 150,820 abdominal imaging carried out in a population of 117,600. The detection of SRMs in relation to SIMD status showed no statistically significant differences across different categories. Similarly, interventions, type of surgery and progression remained unaffected by socioeconomic status. The group on active surveillance showed slow or no-growth at a mean follow-up of more than 2 years. CONCLUSIONS: The detection of small renal masses is very small compared with the amount of imaging investigations of abdomen in 5 years in this cohort. Detection, progression and rate of intervention did not differ in different socioeconomic strata of the cohort. The majority of small renal masses on active surveillance did not change or grew in size very slowly when observed over time.


Assuntos
Neoplasias Renais/diagnóstico , Neoplasias Renais/terapia , Idoso , Estudos de Coortes , Diagnóstico por Imagem , Progressão da Doença , Feminino , Humanos , Incidência , Neoplasias Renais/epidemiologia , Masculino , Vigilância da População , Fatores de Risco , Escócia/epidemiologia , Fatores Socioeconômicos
4.
Scott Med J ; 58(2): 64-8, 2013 May.
Artigo em Inglês | MEDLINE | ID: mdl-23728749

RESUMO

INTRODUCTION: Prostate cancer is the commonest cancer in men and a major health issue worldwide. Screening for early disease has been available for many years, but there is still no national screening programme established in the United Kingdom. OBJECTIVE: To assess the latest evidence regarding prostate cancer screening and whether it meets the necessary requirements to be established as a national programme for all men. METHODS: Electronic databases and library catalogues were searched electronically and manual retrieval was performed. Only primary research results were used for the analysis. RESULTS: In recent years, several important randomised controlled trials have produced varied outcomes. In Europe the largest study thus far concluded that screening reduced prostate cancer mortality by 20%. On the contrary, a large American trial found no reduction in mortality after 7-10 years follow-up. Most studies comment on the adverse effects of screening - principally those of overdiagnosis and subsequent overtreatment. DISCUSSION: Further information about the natural history of prostate cancer and accuracy of screening is needed before a screening programme can be truly justified. In the interim, doctors and patients should discuss the risks, benefits and sequelae of taking part in voluntary screening for prostate cancer.


Assuntos
Detecção Precoce de Câncer , Neoplasias da Próstata/diagnóstico , Exame Retal Digital , Medicina Baseada em Evidências , Humanos , Masculino , Antígeno Prostático Específico/sangue , Reino Unido
5.
Inorg Chem ; 52(7): 3547-55, 2013 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-23485079

RESUMO

Hexavalent neptunium can be solubilized in 0.5-3.5 M aqueous MOH (M = Li(+), Na(+), NMe4(+) = TMA(+)) solutions. Single crystals were obtained from cooling of a dilute solution of Co(NH3)6Cl3 and NpO2(2+) in 3.5 M [N(Me)4]OH to 5 °C. A single-crystal X-ray diffraction study revealed the molecular formula of [Co(NH3)6]2[NpO2(OH)4]3·H2O, isostructural with the uranium analogue. The asymmetric unit contains three distinct NpO2(OH)4(2-) ions, each with pseudooctahedral coordination geometry with trans-oxo ligands. The average Np═O and Np-OH distances were determined to be 1.80(1) and 2.24(1) Å, respectively. EXAFS data and fits at the Np L(III)-edge on solid [Co(NH3)6]2[NpO2(OH)4]3·H2O and aqueous solutions of NpO2(2+) in 2.5 and 3.5 M (TMA)OH revealed bond lengths nearly identical with those determined by X-ray diffraction but with an increase in the number of equatorial ligands with increasing (TMA)OH concentration. Raman spectra of single crystals of [Co(NH3)6]2[NpO2(OH)4]3·H2O reveal a ν1(O═Np═O) symmetric stretch at 741 cm(-1). Raman spectra of NpO2(2+) recorded in a 0.6-2.2 M LiOH solution reveal a single ν1 frequency of 769 cm(-1). Facile exchange of the neptunyl oxo ligands with the water solvent was also observed with Raman spectroscopy performed with (16)O- and (18)O-enriched water solvent. The combination of EXAFS and Raman data suggests that NpO2(OH)4(2-) is the dominant solution species under the conditions of study and that a small amount of a second species, NpO2(OH)5(3-), may also be present at higher alkalinity. Crystal data for [Co(NH3)6]2[NpO2(OH)4]3·H2O: monoclinic, space group C2/c, a = 17.344(4) Å, b = 12.177(3) Å, c = 15.273 Å, ß = 120.17(2)°, Z = 4, R1 = 0.0359, wR2 = 0.0729.

6.
Am J Physiol Lung Cell Mol Physiol ; 299(4): L455-71, 2010 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-20622121

RESUMO

Lung development requires coordinated signaling between airway and vascular growth, but the link between these processes remains unclear. Mammalian target of rapamycin complex-1 (mTORC1) can amplify hypoxia-inducible factor-1α (HIF-1α) vasculogenic activity through an NH(2)-terminal mTOR binding (TOS) motif. We hypothesized that this mechanism coordinates vasculogenesis with the fibroblast growth factor (FGF)-10/FGF-receptor2b/Spry2 regulator of airway branching. First, we tested if the HIF-1α TOS motif participated in epithelial-mesenchymal vascular signaling. mTORC1 activation by insulin significantly amplified HIF-1α activity at fetal Po(2) (23 mmHg) in human bronchial epithelium (16HBE14o-) and induced vascular traits (Flk1, sprouting) in cocultured human embryonic lung mesenchyme (HEL-12469). This enhanced activation of HIF-1α by mTORC1 was abolished on expression of a HIF-1α (F99A) TOS-mutant and also suppressed vascular differentiation of HEL-12469 cocultures. Next, we determined if vasculogenesis in fetal lung involved regulation of mTORC1 by the FGF-10/FGFR2b/Spry2 pathway. Fetal airway epithelium displayed distinct mTORC1 activity in situ, and its hyperactivation by TSC1(-/-) knockout induced widespread VEGF expression and disaggregation of Tie2-positive vascular bundles. FGF-10-coated beads grafted into fetal lung explants from Tie2-LacZ transgenic mice induced localized vascular differentiation in the peripheral mesenchyme. In rat fetal distal lung epithelial (FDLE) cells cultured at fetal Po(2), FGF-10 induced mTORC1 and amplified HIF-1α activity and VEGF secretion without induction of ERK1/2. This was accompanied by the formation of a complex between Spry2, the cCBL ubiquitin ligase, and the mTOR repressor, TSC2, which abolished GTPase activity directed against Rheb, the G protein inducer of mTORC1. Thus, mTORC1 links HIF-1α-driven vasculogenesis with the FGF-10/FGFR2b/Spry2 airway branching periodicity regulator.


Assuntos
Relógios Biológicos , Fator 10 de Crescimento de Fibroblastos/metabolismo , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Pulmão/metabolismo , Neovascularização Fisiológica , Proteínas do Tecido Nervoso/metabolismo , Receptor Tipo 2 de Fator de Crescimento de Fibroblastos/metabolismo , Fatores de Transcrição/metabolismo , Animais , Western Blotting , Brônquios/citologia , Brônquios/metabolismo , Células Cultivadas , Ritmo Circadiano , Embrião de Mamíferos/citologia , Embrião de Mamíferos/metabolismo , Ensaio de Imunoadsorção Enzimática , Células Epiteliais/metabolismo , Feto/citologia , Feto/metabolismo , Fator 10 de Crescimento de Fibroblastos/genética , Fibroblastos/citologia , Fibroblastos/metabolismo , Humanos , Subunidade alfa do Fator 1 Induzível por Hipóxia/genética , Técnicas Imunoenzimáticas , Imunoprecipitação , Pulmão/citologia , Mesoderma/citologia , Mesoderma/metabolismo , Camundongos , Proteínas do Tecido Nervoso/genética , RNA Mensageiro/genética , Ratos , Ratos Sprague-Dawley , Receptor Tipo 2 de Fator de Crescimento de Fibroblastos/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Fatores de Transcrição/genética , Proteína 1 do Complexo Esclerose Tuberosa , Proteínas Supressoras de Tumor/fisiologia
7.
Haemophilia ; 16(1): 80-9, 2010 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-19780845

RESUMO

In patients with severe haemophilia and inhibitors, regular factor VIII inhibitor bypassing activity (FEIBA) prophylaxis has been shown to reduce the frequency of bleeding by up to 85% and to improve patient quality of life. FEIBA is well tolerated; the incidence of thrombotic events and of allergic reactions is extremely low. The concept of prophylaxis in haemophilia patients with inhibitors is relatively new and some clinicians may be unsure of how to use FEIBA in this context. These treatment recommendations, based on published evidence plus the collective experience of a group of haematologists (with practical knowledge of managing inhibitor patients with FEIBA prophylaxis), are intended to provide guidance to clinicians considering initiating and maintaining patients on FEIBA prophylaxis with specific focus on practical aspects of patient selection, dosing, monitoring and stop criteria.


Assuntos
Fatores de Coagulação Sanguínea/uso terapêutico , Hemofilia A/tratamento farmacológico , Hemofilia B/tratamento farmacológico , Hemorragia/prevenção & controle , Adolescente , Adulto , Inibidores dos Fatores de Coagulação Sanguínea/sangue , Fatores de Coagulação Sanguínea/efeitos adversos , Criança , Pré-Escolar , Hemofilia A/complicações , Hemofilia B/complicações , Humanos , Tolerância Imunológica , Lactente , Pessoa de Meia-Idade , Guias de Prática Clínica como Assunto , Adulto Jovem
9.
Br Dent J ; 198(9): 533-41, 2005 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-15895045

RESUMO

With a plethora of post systems available, it is often difficult to decide which one to use. This is made more difficult by the fact that new posts are introduced before existing ones are fully evaluated in laboratory and clinical studies. This paper therefore describes the different post types and the main advantages and disadvantages of each. In addition, the choice of post system will influence whether further tooth preparation is required and will dictate which luting cement and core material are most appropriate. Whilst the choice of post will, for many dentists, be driven by personal preference and a history of clinical success, there are certain pit falls to avoid and these are outlined.


Assuntos
Coroas , Técnica para Retentor Intrarradicular , Cimentação , Resinas Compostas , Cimentos Dentários , Planejamento de Prótese Dentária , Humanos , Quartzo , Preparo do Dente
10.
Br Dent J ; 198(10): 609-17, 2005 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-15920585

RESUMO

This paper highlights the fact that many anterior teeth requiring restoration are severely weakened having wide, flared canal spaces, and thin dentinal walls that are prone to fracture. Traditionally these teeth have been restored using metal posts and are often unsuccessful because of lack of retention or root fracture. This paper describes how mineral trioxide aggregate (MTA) can be used to form an immediate apical seal rather than waiting months for apexification. Weakened roots can be reinforced using dentine bonding agents and composite resin and if insufficient coronal tooth structure is present a quartz-fibre post can be placed to retain a composite core.


Assuntos
Compostos de Alumínio , Compostos de Cálcio , Combinação de Medicamentos , Óxidos , Técnica para Retentor Intrarradicular , Materiais Restauradores do Canal Radicular , Obturação do Canal Radicular/métodos , Silicatos , Ápice Dentário/fisiologia , Raiz Dentária/patologia , Resinas Compostas , Colagem Dentária , Adesivos Dentinários , Humanos , Incisivo , Maxila , Quartzo
11.
Br Dent J ; 198(7): 395-404, 2005 Apr 09.
Artigo em Inglês | MEDLINE | ID: mdl-15870790

RESUMO

This is the first in a series of four papers related to the management of root canal treated teeth. When teeth compromised by extensive restorations become non-vital, suggestions have been given as to how root canal treatment can be carried out with the greatest chance of success. Once root canal treated, either by a previous dentist or by the current dentist, a review of the assessment process that should be carried out prior to placing costly indirect definitive restorations is given. It will be clear that post-retained restorations are mainly reserved for anterior or single-rooted teeth, posterior teeth rarely requiring a post for core retention. The second paper in this series describes the basic tooth preparation that should be carried out prior to placing a post. Depending on the type of post system used, further modifications to tooth preparation may be required and the cementation techniques may also have to be modified. The third paper therefore discusses the various post types, when and how they should be used for optimum results. The final paper addresses reinforcement and restoration of compromised root canals, such as those with immature, open apices, or those that have been over-prepared for previous post-retained restorations.


Assuntos
Dente não Vital/terapia , Restauração Dentária Permanente/métodos , Humanos , Incisivo , Dente Molar , Avaliação das Necessidades , Percussão , Técnica para Retentor Intrarradicular , Prognóstico , Radiografia , Fraturas dos Dentes/diagnóstico , Mobilidade Dentária/diagnóstico , Raiz Dentária/lesões , Dente não Vital/diagnóstico por imagem
12.
Br Dent J ; 198(8): 463-71, 2005 Apr 23.
Artigo em Inglês | MEDLINE | ID: mdl-15849574

RESUMO

Failure of root canal treatment and/or post crowns can be avoided in many cases if appropriate tooth preparation is carried out. This paper discusses the rationale for the timing of post placement following root canal treatment and appropriate methods for removal of gutta-percha prior to post space preparation. The basic principles of post space preparation are described, which should reduce the risk of weakening the root unnecessarily, causing damage to the periodontium and post perforation.


Assuntos
Retenção em Prótese Dentária/métodos , Técnica para Retentor Intrarradicular , Preparo do Dente/métodos , Materiais Biocompatíveis , Aumento da Coroa Clínica/métodos , Coroas , Guta-Percha , Humanos , Obturação do Canal Radicular/métodos , Tratamento do Canal Radicular/métodos , Técnicas de Movimentação Dentária/métodos
13.
J Am Chem Soc ; 126(41): 13443-58, 2004 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-15479101

RESUMO

Pu L(3) X-ray absorption fine structure spectra from 24 samples of PuO(2+x) (and two related Pu-substituted oxides), prepared by a variety of methods, demonstrate that (1) although the Pu sublattice remains the ordered part of the Pu distribution, the nearest-neighbor O atoms even at x = 0 are found in a multisite distribution with Pu-O distances consistent with the stable incorporation of OH(-) (and possibly H(2)O and H(+)) into the PuO(2) lattice; (2) the excess O from oxidation is found at Pu-O distances <1.9 A, consistent with the multiply bound "oxo"-type ligands found in molecular complexes of Pu(V) and Pu(VI); (3) the Pu associated with these oxo groups is most likely Pu(V), so that the excess O probably occurs as PuO(2)(+) moieties that are aperiodically distributed through the lattice; and (4) the collective interactions between these defect sites most likely cause them to cluster so as give nanoscale heterogeneity in the form of domains that may have unusual reactivity, observed as sequential oxidation by H(2)O at ambient conditions. The most accurate description of PuO(2) is therefore actually PuO(2+x-y)(OH)(2)(y).zH(2)O, with pure, ordered, homogeneous PuO(2) attained only when H(2)O is rigorously excluded and the O activity is relatively low.

14.
J Am Chem Soc ; 126(20): 6387-401, 2004 May 26.
Artigo em Inglês | MEDLINE | ID: mdl-15149236

RESUMO

Reaction of 3 equiv of 2,6-diisopropylaniline with La[N(SiMe(3))(2)](3) produces the dimeric species La(2)(NHAr)(6) (1). X-ray crystallography reveals a centrosymmetric structure, where the dimeric unit is bridged by intermolecular eta(6)-arene interactions of a unique arylamide ligand attached to an adjacent metal center. Exposure of 1 to THF results in formation of the monomeric tris-THF adduct La(NHAr)(3)(THF)(3) (2), which was shown by X-ray crystallography to maintain a fac-octahedral structure in the solid state. (1)H NMR spectroscopy illustrates that the binding of THF to 1 to form 2 is reversible and removal of THF under vacuum regenerates dimeric 1. Addition of pyridine to 1 yields the monomeric bis-pyridine adduct La(NHAr)(3)(py)(2) (3), which exhibits a distorted trigonal-bipyramidal La metal center. Solution (1)H NMR, IR, and Raman spectroscopy indicate that the pi-arene-bridged dimeric structure of 1 is maintained in solution. Variable-temperature (1)H NMR spectroscopic investigations of 1 are consistent with a monomer-dimer equilibrium at elevated temperature. In contrast, variable-temperature (1)H NMR spectroscopic investigations of the aryloxide analogue La(2)(OAr)(6) (4) show that the bridging and terminal aryloxide groups exchange by a mechanism in which the dimeric nature of the compound is retained. Density functional theory (DFT) calculations were carried out on model compounds La(2)(OC(6)H(5))(6), La(2)(NHC(6)H(5))(6), and (C(6)H(5)R)La(XC(6)H(5))(3), where X = O or NH and R = H, OH, or NH(2). The formation of eta(6)-arene interactions is energetically favored over monomeric LaX(3) (X = OPh or NHPh) with the aryloxide pi-arene interaction being stronger than the arylamide pi-arene interaction. Calculation of vibrational frequencies reveals the origin of the observed IR spectral behavior of both La(2)(OC(6)H(5))(6) and La(2)(NHC(6)H(5))(6), with the higher energy nu(C=C) stretch due to terminal ligands and the lower energy stretch associated with the bridging ligands.

15.
Inorg Chem ; 43(1): 116-31, 2004 Jan 12.
Artigo em Inglês | MEDLINE | ID: mdl-14704059

RESUMO

Pu L(3) X-ray near edge absorption spectra for Pu(0-VII) are reported for more than 60 chalcogenides, chlorides, hydrates, hydroxides, nitrates, carbonates, oxy-hydroxides, and other compounds both as solids and in solution, and substituted in zirconolite, perovskite, and borosilicate glass. This large database extends the known correlations between the energy and shape of these spectra from the usual association of the XANES with valence and site symmetry to higher order chemical effects. Because of the large number of compounds of these different types, a number of novel and unexpected behaviors are observed, such as effects resulting from the medium and disorder that can be as large as those from valence.

16.
Inorg Chem ; 42(12): 3715-7, 2003 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-12793805

RESUMO

Pu L(3) XAFS measurements show that the excess oxygen in single phase PuO(2+)(x)() occurs as oxo groups with Pu-O distances of 1.83-1.91 A. This distance and the energy of the edge (via comparison with a large number of related compounds) are more consistent with a Pu(IV/V) than a Pu(IV/VI) mixture. Analogous to Pu(IV) colloids, although the Pu-Pu pair distribution remains single site even when it shows substantial disorder, the Pu-O distribution can display a number of additional shells at specific distances up to 3.4 A even in high fired materials when no oxo groups are present, implying intrinsic H(+)/OH(-)(/H(2)O). The number of oxo atoms increases when samples are equilibrated with humid air at ambient temperature, indicating that the Pu reactivity in this solid system differs notably from that of isolated complexes and demonstrating the importance of nanoscale cooperative phenomena and total free energy in determining its chemical properties.

17.
Environ Sci Technol ; 36(14): 3114-7, 2002 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-12141492

RESUMO

X-ray absorption spectroscopy was used to determine the local structure of U(VI) within synthetic fluorapatite at a concentration of 2.3 wt %. Extended X-ray absorption fine structure indicates that U(VI) substitutes into the Ca1 site. To accommodate this substitution the apatite structure significantly distorts such that the Ca1 site approximates octahedral coordination, with six uniform U-0 distances of 2.06A. An X-ray adsorption edge structure, with two inflection points, and optical emission spectra are consistent with 6d orbital crystal field splitting. These results indicate that significant amounts of U(VI) can be accommodated in the apatite structure but with an unexpected coordination, which may bear on the ultimate development of apatite-hosted nuclear-waste forms.


Assuntos
Apatitas/química , Urânio/química , Monitoramento Ambiental , Estrutura Molecular , Resíduos Radioativos , Análise Espectral/métodos
18.
J Am Chem Soc ; 124(7): 1327-33, 2002 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-11841302

RESUMO

The first quaternary plutonium metal thiophosphates have been synthesized by the reactive flux method and characterized by single-crystal X-ray diffraction: K(3)Pu(PS(4))(2) (I), KPuP(2)S(7) (II), RbPuP(2)S(7) (III), and CsPuP(2)S(7) (IV). All four compounds crystallize in the monoclinic space group P2(1)/c with Z = 4. Compound I has cell parameters of a = 9.157(1) A, b = 16.866(2) A, c = 9.538(1), and beta = 90.610(3)degrees. Compound II has cell parameters of a = 9.641(1) A, b = 12.255(1) A, c = 9.015(1) A, and beta = 90.218(1)degrees. Compound III has cell parameters of a = 9.8011(6) A, b = 12.3977(7) A, c = 9.0263(5) A, and beta = 90.564(1)degrees. Compound IV has cell parameters of a = 10.1034(7) A, b = 12.5412(9) A, c = 9.0306(6) A, and beta = 91.007(1)degrees. Compound I is isostructural to a family of rare-earth metal thiophosphates and comprises bicapped trigonal prismatic PuS(8) polyhedra linked in chains through edge-sharing interactions and through thiophosphate tetrahedra. Compounds II-IV crystallize in a known structure type not related to any previously observed actinide thiophosphates and contain the (P(2)S(7))(4-) corner-shared bitetrahedral ligand as a structural building block. A summary of important bond distances and angles for these new plutonium thiophosphate materials is compared to the limited literature on plutonium solid-state compounds. Diffuse reflectance spectra confirm the Pu(III) oxidation state and Raman spectroscopy confirms the tetrahedral PS(4)(3-) building block in all structures.

19.
Geochem Trans ; 3: 31, 2002.
Artigo em Inglês | MEDLINE | ID: mdl-35412759

RESUMO

The Raman spectra of thioarsenite and arsenite species in aqueous solution were obtained at room temperature. Solutions at constant ΣAs + ΣS of 0.1 and 0.5 mol kg-1 were prepared with various ΣS/ΣAs ratios (0.1-9.0) and pH values (~7-13.2). Our data suggest that the speciation of As under the conditions investigated is more complicated than previously thought. The Raman measurements offer evidence for at least six separate S-bearing As species whose principal bands are centered near 365, 385, 390, 400, 415 and 420 cm-1. The data suggest that at least two different species may give rise to bands at 385 cm-1, bringing the probable minimum number of species to seven. Several additional species are possible but could not be resolved definitively. In general, the relative proportions of these species are dependent on total As concentration, ΣS/ΣAs ratio and pH. At very low ΣS/ΣAs ratios we also observe Raman bands attributable to the dissociation products of H3AsO3(aq). Although we were unable to assign precise stoichiometries for the various thioarsenite species, we were able to map out general pH and ΣS/ΣAs conditions under which the various thioarsenite and arsenite species are predominant. This study provides a basis for more detailed Raman spectroscopic and other types of investigations of the nature of thioarsenite species.

20.
N Z Med J ; 114(1140): 423-5, 2001 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-11700750

RESUMO

AIM: To review the current epidemiology of patients with deliberate self-poisoning presenting to Christchurch Emergency Department, and to compare this with 1996, 1992, and 1989 data. METHODS: A retrospective analysis of computer and case records over the twelve-month period of 1999 was conducted and compared with published data from 1996,1992 and 1989. RESULTS: There were 561 presentations of deliberate self-poisoning to Christchurch Hospital, representing 0.87% of total presentations (compared with 1.1% in 1996, 1.2% in 1992, and 1.0% in 1989). The female to male ratio was 2.2:1.0 (compared with 1.9:1.0, 1.5:1.0, and 2.1:1.0). The principal drugs ingested were antidepressants 30.8% (compared with 20.1%, 24.4%,15.7%), paracetamol 23.5% (compared with 16.7%, 16.9%, 10.6%), benzodiazepines 23.0% (compared with 11.1%, 23.6% 22.8%) and antipsychotics 17.8% (compared with 10.7%, 16.1%, not reported). Gastrointestinal decontamination was performed in only 14.4% of patients (compared with 61%, 73%, 61%). Activated charcoal was given alone in 13.2% (compared with 54%, 46%, 0.4%), activated charcoal and gastric lavage in 0.7% (7%, 26%, 53%), a whole bowel irrigation in 0.5% (not recorded in previous papers). 70.4% were admitted (compared with 69%, 59%, 64%), 7% to intensive care (10.2%, 10.6%, 18%). There were two deaths (compared with 6, 2 and 2). CONCLUSIONS: Over the time periods studied the drugs ingested and admission rates remain similar, although a large proportion are now being observed in the emergency short stay ward, reducing admission rates to the ward and intensive care. Trends in gastrointestinal decontamination have changed dramatically over the four time periods, but there has been no worsening in the outcome of patients with deliberate self-poisoning.


Assuntos
Lavagem Gástrica/métodos , Intoxicação/epidemiologia , Intoxicação/terapia , Tentativa de Suicídio/estatística & dados numéricos , Acetaminofen/intoxicação , Adolescente , Adulto , Distribuição por Idade , Idoso , Idoso de 80 Anos ou mais , Antidepressivos/intoxicação , Benzodiazepinas/intoxicação , Distribuição de Qui-Quadrado , Descontaminação , Feminino , Seguimentos , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Nova Zelândia/epidemiologia , Probabilidade , Estudos Retrospectivos , Fatores de Risco , Distribuição por Sexo , Taxa de Sobrevida , Resultado do Tratamento
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