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1.
Int J Mol Sci ; 20(17)2019 Aug 26.
Artigo em Inglês | MEDLINE | ID: mdl-31454911

RESUMO

The main aim of this work is to substantiate the mechanism of 1-propanol oxidation by ozone in aqueous solution when the substrate is present in large excess. Further goals are assessment of the products, their formation yields as well as the kinetic parameters of the considered reaction. The reaction of ozone with 1-propanol in aqueous solution occurs via hydride transfer, H-abstraction and insertion. Of these three mechanisms, the largest share is for hydride transfer. This implies the extraction of an hydride ion from the activated C-H group by O3 according to reaction: (C2H5)(H)(HO)C-H + O3 → [(C2H5)(H)(HO)C+ + HO3-]cage → (C2H5)(H)(HO)C+ + HO3-. The experimentally determined products and their overall formation yields with respect to ozone are: propionaldehyde-(60 ± 3)%, propionic acid-(27.4 ± 1.0)%, acetaldehyde-(4.9 ± 0.3)%, acetic acid-(0.3 ± 0.1)%, formaldehyde-(1.0 ± 0.1)%, formic acid-(4.6 ± 0.3)%, hydrogen peroxide-(11.1 ± 0.3)% and hydroxyl radical-(9.8 ± 0.3)%. The reaction of ozone with 1-propanol in aqueous media follows a second order kinetics with a reaction rate constant of (0.64 ± 0.02) M-1·s-1 at pH = 7 and 23 °C. The dependence of the second order rate constant on temperature is described by the equation: l n   k I I = ( 27.17 ± 0.38 ) - ( 8180 ± 120 ) × T - 1 , which gives the activation energy, Ea = (68 ± 1) kJ mol-1 and pre-exponential factor, A = (6.3 ± 2.4) × 1011 M-1 s-1. The nature of products, their yields and the kinetic data can be used in water treatment. The fact that the hydride transfer is the main pathway in the 1-propanol/ozone system can probably be transferred on other systems in which the substrate is characterized by C-H active sites only.

2.
Phys Rev Lett ; 122(12): 128002, 2019 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-30978078

RESUMO

Microflows constitute an important instrument to control particle dynamics. A prominent example is the sorting of biological cells, which relies on the ability of deformable cells to move transversely to flow lines. A classic result is that soft microparticles migrate in flows through straight microchannels to an attractor at their center. Here, we show that flows through wavy channels fundamentally change the overall picture. They lead to the emergence of a second, coexisting attractor for soft particles. Its emergence and off-center location depends on the boundary modulation and the particle properties. The related cross-stream migration of soft particles is explained by analytical considerations, Stokesian dynamics simulations in unbounded flows, and Lattice-Boltzmann simulations in bounded flows. The novel off-center attractor can be used, for instance, in diagnostics, for separating cells of different size and elasticity, which is often an indicator of their health status.


Assuntos
Eritrócitos/citologia , Modelos Biológicos , Movimento Celular/fisiologia , Eritrócitos/química , Microfluídica
3.
Water Res ; 128: 171-182, 2018 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-29102696

RESUMO

This paper deals with reactions occurring in the aqueous system of 2-propanol/ozone. The considered reactions are discussed from thermodynamic and kinetic points of view. The major finding refers to the fact that 2-propanol reacts with O3 mainly via hydride transfer: (HO)(H3C)2CH + O3 â†’ [(HO)(H3C)2C+ + HO3-]cage â†’ (HO)(H3C)2C+ + HO3- â†’ (H3C)2CO + H2O + O2 Arguments supporting this proposed mechanism are: high exergonicity of reaction (ΔG = -234 kJ mol-1 for the first two steps), low HO yield - (2.4 ± 0.5)% and high acetone yield - (87.2 ± 1.5)%. Other oxidation products detected within the system are acetaldehyde - (1.4 ± 0.1)%, formaldehyde - (4.0 ± 0.1)%, acetic acid - (2.8 ± 0.2)%, formic acid - (0.6 ± 0.2)% and hydrogen peroxide - (1.5 ± 0.1)%. The temperature dependence of the second order rate constant for the reaction 2-propanol + O3 â†’ products is ln kII = 29.64-8500 × T-1. The activation energy and pre-exponential factor derived from this relationship are (71 ± 3) kJ mol-1 and (7.5 ± 6.4) × 1012 M-1 s-1, respectively. At 23 °C, the second order rate constant is kII = (2.7 ± 0.1) M-1 s-1. The low reaction rate can be explained by the transfer of one hydride ion from 2-propanol to electrophilic ozone.


Assuntos
2-Propanol/química , Ozônio/química , Acetona/química , Formiatos/química , Peróxido de Hidrogênio/química , Cinética , Oxirredução , Temperatura Ambiente , Termodinâmica , Água
4.
Water Res ; 102: 582-593, 2016 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-27448509

RESUMO

Pyridine, pyridazine, pyrimidine and pyrazine were investigated in their reaction with ozone. These compounds are archetypes for heterocyclic aromatic amines, a structural unit that is often present in pharmaceuticals, pesticides and dyestuffs (e.g., enoxacin, pyrazineamide or pyrimethamine). The investigated target compounds react with ozone with rate constants ranging from 0.37 to 57 M(-1) s(-1), hampering their degradation during ozonation. In OH radical scavenged systems the reaction of ozone with pyridine and pyridazine is characterized by high transformation (per ozone consumed) of 55 and 54%, respectively. In non scavenged system the transformation drops to 52 and 12%, respectively. However, in the reaction of pyrimidine and pyrazine with ozone this is reversed. Here, in an OH radical scavenged system the compound transformation is much lower (2.1 and 14%, respectively) than in non scavenged one (22 and 25%, respectively). This is confirmed by corresponding high N-oxide formation in the ozonation of pyridine and pyridazine, but probably low formation in the reaction of pyrimidine and pyrazine with ozone. With respect to reaction mechanisms, it is suggested that ozone adduct formation at nitrogen is the primary step in the ozonation of pyridine and pyridazine. On the contrary, ozone adduct formation to the aromatic ring seems to occur especially in the ozonation of pyrimidine as inferred from hydrogen peroxide yield. However, also OH radical reactions are supposed processes in the case of pyrimidine and in particular for pyrazine, albeit negligible OH radical yields are obtained. The low compound transformation in OH radical scavenged system can prove this. As a result of negligible OH radical yields in all cases (less than 6%) electron transfer as primary reaction pathway plays a subordinate role.


Assuntos
Ozônio/química , Piridinas , Peróxido de Hidrogênio/química , Cinética , Poluentes Químicos da Água/química
5.
Water Res ; 98: 147-59, 2016 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-27088249

RESUMO

Anilines as archetypes for aromatic amines, which play an important role in the production of, e.g., dyestuffs, plastics, pesticides or pharmaceuticals were investigated in their reaction with ozone. Due to their high reactivity towards ozone (1.2 × 10(5)-2.4 × 10(6) M(-1) s(-1)) the investigated aniline bearing different substituents are readily degraded in ozonation. However, around 4 to 5 molecules of ozone are needed to yield a successful transformation of aniline, most likely due to a chain reaction that decomposes ozone without compound degradation. This is inferred from OH radical scavenging experiments, in which compound transformation per ozone consumed is increased. Mechanistic considerations based on product formation indicate that addition to the aromatic ring is the preferential reaction in the case of aniline, p-chloroaniline and p-nitroaniline (high amounts of o-hydroxyaniline, p-hydroxyaniline, chloride, nitrite and nitrate, respectively were found). For aniline an addition to the nitrogen happens but to a small extent, since nitroso- and nitrobenzene were observed as well. In the case of N-methylaniline and N,N-dimethylaniline, an electron transfer reaction from nitrogen to ozone was proven due to the formation of formaldehyde. In contrast, for p-methylaniline and p-methoxyaniline the formation of formaldehyde may result from an electron transfer reaction at the aromatic ring. Additional oxidation pathways for all of the anilines under study are reactions of hydroxyl radicals formed in the electron transfer of ozone with the anilines (OH radical yields = 34-59%). These reactions may form aminyl radicals which in the case of aniline can terminate in bimolecular reactions with other compounds such as the determined o-hydroxyaniline by yielding the detected 2-amino-5-anilino-benzochinon-anil.


Assuntos
Compostos de Anilina , Ozônio , Radical Hidroxila , Cinética , Oxirredução
6.
Water Res ; 88: 960-971, 2016 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-26624229

RESUMO

Piperidine, piperazine and morpholine as archetypes for secondary heterocyclic amines, a structural unit that is often present in pharmaceuticals (e.g., ritalin, cetirizine, timolol, ciprofloxacin) were investigated in their reaction with ozone. In principle the investigated compounds can be degraded with ozone in a reasonable time, based on their high reaction rate constants with respect to ozone (1.9 × 10(4)-2.4 × 10(5) M(-1) s(-1)). However, transformation is insufficient (13-16%), most likely due to a chain reaction, which decomposes ozone. This conclusion is based on OH scavenging experiments, leading to increased compound transformation (18-27%). The investigated target compounds are similar in their kinetic and stoichiometric characteristics. However, the mechanistic considerations based on product formation indicate various reaction pathways. Piperidine reacts with ozone via a nonradical addition reaction to N-hydroxypiperidine (yield: 92% with and 94% without scavenging, with respect to compound transformation). However, piperazine degradation with ozone does not lead to N-hydroxypiperazine. In the morpholine/ozone reaction, N-hydroxymorpholine was identified. Additional oxidation pathways in all cases involved the formation of OH with high yields. One important pathway of piperazine and morpholine by ozonation could be the formation of C-centered radicals after ozone or OH radical attack. Subsequently, O2 addition forms unstable peroxyl radicals, which in one pathway loose superoxide radicals by generating a carbon-centered cation. Subsequent hydrolysis of the carbon-centered cation leads to formaldehyde, whereby ozonation of the N-hydroxy products can proceed in the same way and in addition give rise to hydroxylamine. A second pathway of the short-lived peroxyl radicals could be a dimerization to form short-lived tetraoxides, which cleave by forming hydrogen peroxide. All three products have been found.


Assuntos
Morfolinas/química , Ozônio/química , Preparações Farmacêuticas/química , Piperazinas/química , Piperidinas/química , Poluentes Químicos da Água/química , Cinética , Piperazina , Eliminação de Resíduos Líquidos
8.
Cytogenet Genome Res ; 142(4): 239-44, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24853086

RESUMO

We report on our experience of studying amniotic fluid cells by cytogenetic analysis (CA) of the first 2 clones. We investigated the incidence and types of chromosome aberrations detected by CA of 196 amniocenteses performed on pregnant women at high risk. Of these cases, 178 were analysed by QF-PCR (risk group A). The results were compared with the data obtained by CA of 1,263 amniocenteses carried out in patients with other indications. QF-PCR was used to investigate 1,030 of these cases (risk group B). The combined average turnaround time for a CA result of the first 2 clones in both risk groups was within 9 ± 2 days. The final CA results (≥6 clones) were obtained within 12 ± 4 days. In risk group A, CA was not possible in 2 cases due to cell culture failure. The foetal karyotype was abnormal in 13.8% of the cases by CA of ≥6 clones and in 13.5% of the cases by QF-PCR. Together, CA of ≥6 clones and QF-PCR detected chromosome aberrations in 14.8% of the cases. With the exception of 2 cases of in vitro culture failure and 1 case with low gonosomal mosaicism, CA of the first 2 clones detected all cases with chromosome aberrations. Five cases with clinically significant chromosome aberrations were not detected by QF-PCR. In risk group B, the foetal karyotype was found to be abnormal in 2.2% of the cases by CA of ≥6 clones and in 1.0% of the cases by QF-PCR. Together, CA of ≥6 clones and QF-PCR revealed chromosome aberrations in 2.2% of the cases. With the exception of 1 case with low gonosomal mosaicism, CA of the first 2 clones detected all other cases with chromosome aberrations. The majority of these cases were inherited chromosome aberrations. Eighteen cases with chromosome aberrations were not detected by QF-PCR. Based on our results, CA of ≥6 clones, together with QF-PCR as a first test, should be performed in all prenatal cases with abnormal ultrasound findings. In pregnancies with other indications, CA of the first 2 clones alone is sufficient to identify all clinically significant (and inherited) chromosome aberrations.


Assuntos
Líquido Amniótico/citologia , Aberrações Cromossômicas , Transtornos Cromossômicos/diagnóstico , Análise Citogenética/métodos , Diagnóstico Pré-Natal/métodos , Amniocentese , Células Cultivadas , Feminino , Humanos , Cariótipo , Cariotipagem , Gravidez , Reação em Cadeia da Polimerase em Tempo Real
9.
Neuropediatrics ; 43(5): 275-8, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-22976442

RESUMO

Glucose transporter 1 (GLUT1) deficiency syndrome (DS) results from impaired glucose transport into brain. We describe the case of an 8-year-old girl with early-onset myoclonic epilepsy unresponsive to eight anticonvulsants. Oral steroid treatment achieved dramatic seizure control at the expense of Cushing syndrome and progressive fatty liver disease. Steroid withdrawal resulted in severe seizure exacerbation but was eventually enforced for lumbar puncture. GLUT1DS was diagnosed by hypoglycorrhachia and a heterozygous SLC2A1 mutation (Arg400His). A ketogenic diet resulted in effective seizure control. Steroids in GLUT1DS are unusual and unreported. Here a remarkable immediate and effective seizure control and a dose-independent unsuccessful steroid withdrawal indicated a potential GLUT1 sensitivity to steroids. We review the literature on GLUT1/steroid interactions and propose that unusual steroid sensitivity in intractable childhood epilepsy might be indicative for GLUT1DS.


Assuntos
Anticonvulsivantes/uso terapêutico , Erros Inatos do Metabolismo dos Carboidratos/complicações , Epilepsia/tratamento farmacológico , Epilepsia/genética , Esteroides/uso terapêutico , Criança , Eletroencefalografia , Feminino , Transportador de Glucose Tipo 1/química , Transportador de Glucose Tipo 1/genética , Humanos , Modelos Moleculares , Proteínas de Transporte de Monossacarídeos/deficiência , Mutação/genética
10.
Intern Med ; 51(15): 2007-9, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22864127

RESUMO

Birt-Hogg-Dubé syndrome is a rare autosomal dominant condition caused by a germline mutation in the folliculin gene, which is characterized by skin fibrofolliculomas, multiple lung cysts and renal cancer. The clinical expression of the syndrome is highly variable, with recurrent pneumothoraces due to ruptured lung cysts in many cases. We report a patient with pneumomediastinum and cervico-facial emphysema after severe coughing without pneumothorax, skin lesions or renal tumour, but a striking family history of lung abnormalities.


Assuntos
Síndrome de Birt-Hogg-Dubé/complicações , Síndrome de Birt-Hogg-Dubé/genética , Enfisema Mediastínico/complicações , Enfisema Mediastínico/genética , Síndrome de Birt-Hogg-Dubé/diagnóstico por imagem , Tosse/complicações , Mutação da Fase de Leitura , Humanos , Masculino , Enfisema Mediastínico/diagnóstico por imagem , Linhagem , Fenótipo , Proteínas Proto-Oncogênicas/genética , Tomografia Computadorizada por Raios X , Proteínas Supressoras de Tumor/genética , Adulto Jovem
11.
J Hazard Mater ; 207-208: 97-102, 2012 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-21543156

RESUMO

Single Cr(VI) reduction and coupled reduction/stabilization (R/S) processes were evaluated at pilot scale to determine their effectiveness to treat chromite ore processing residue (COPR). Sodium sulfide was used as the reducing agent and cement, gypsum and lime were tested as the stabilizing agents. The pilot experiments were performed in a helical ribbon blender mixer with batches of 250 kg of COPR and mixing time up to 30 min. Na2S/Cr(VI) mass ratios of 4.6, 5.7 and 6.8 were evaluated in the single reduction process to treat COPR with Cr(VI) concentration of ≈4.2 g/kg. The R/S process was tested with a Na2S/Cr(VI) mass ratio of 5.7 and including stabilizing agents not exceeding 5% (w/w(COPR)), to treat COPR with a Cr(VI) content of ≈5.1g/kg. The single reduction process with a ratio of 6.8, reached Cr(VI) reduction efficiencies up to 97.6% in the first days, however these values decreased to around 93% after 380 days of storage. At this point the total Cr level was around 12.5 mg/L. Cr(VI) removal efficiencies exceeding 96.5% were reached and maintained during 380 days when the coupled R/S process was evaluated. Total Cr levels lower than 5 mg/l were attained at the initials days in all R/S batch tested, however after 380 days, concentrations below the regulatory limit were only found with gypsum (2%) as single agent and with a blend of cement (4%) and lime (1%). These results indicated that the coupled R/S process is an excellent alternative to stabilize COPR.


Assuntos
Cromo/química , Sulfetos/química , Cromo/isolamento & purificação , Concentração de Íons de Hidrogênio , Oxirredução , Projetos Piloto
12.
Eur J Pediatr ; 169(7): 789-93, 2010 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-19957191

RESUMO

INTRODUCTION: Low level of trisomy 13 mosaicism is a rare condition. In the present report, we describe a case of a 19-month-old boy with poor feeding, poor weight gain, mild dysmorphic features, mild muscular hypotonia, and speech delay. DISCUSSION: Cytogenetic analysis on metaphases of lymphocytes revealed an 8% mosaic Robertsonian translocation trisomy 13 in the boy and a balanced Robertsonian translocation, 45,XX,der(13;14)(q10;q10), in his normal mother. Fluorescence in situ hybridization (FISH) on patient lymphocytes disclosed 4% of metaphases with a trisomy 13. The trisomy 13 mosaicism in metaphases could not be identified by interphase FISH. The percentage of three signals (4%) was within the standard deviation in diploid controls. Follow-up of the patient was performed at the age of 7 1/12 years, and in cells from buccal smear of the patient, trisomy 13 was detected in 11% of interphases analyzed that is a higher frequency. Uniparental disomy of chromosomes 13 and 14 were excluded in the boy, and therefore, his phenotypic abnormalities most likely were caused by the low level of trisomy 13 mosaicism. CONCLUSION: The detailed report of this patient described the infrequent occurrence of a low mosaic Robertsonian translocation trisomy 13. We suggest to study cases of low trisomy mosaicism preferentially using metaphase analyses rather than interphase FISH. Our case is helpful in further defining the phenotype of these patients.


Assuntos
Anormalidades Múltiplas/genética , Cromossomos Humanos Par 13 , Deficiências do Desenvolvimento/genética , Face/anormalidades , Mosaicismo , Translocação Genética , Trissomia/genética , Adulto , Feminino , Alemanha , Humanos , Lactente , Masculino
13.
Environ Sci Technol ; 37(9): 1941-8, 2003 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-12775069

RESUMO

The ozone decomposition quantum yield (phi) in millimolar and higher-concentration aqueous tertiary butanol solution is 0.64 +/- 0.05 (observed over a wavelength range from 250 to 280 nm) and rises toward lower tertiary butanol concentrations (phi approximately 1.5 at 10(-5) M at pH 2) on account of the onset of the well-known *OH-radical-induced chain reaction. The destruction of the organic is initiated by hydrogen-atom abstraction through OH radicals which are produced via the reaction of the photolytically generated O(1D) with the solvent water at a quantum yield of phi(*OH) of about 0.1. There is no decomposition of ozone in the dark on the time scale of the photolysis experiment. The efficiency of tertiary butanol destruction with respect to ozone consumption ([O3]0 = 3 x 10(-4) M), defined by the ratio delta[t-BuOH]/delta[O3], termed eta(t-BuOH), is 0.26 at millimolar tertiary butanol concentrations, determined at the stage of essentially complete ozone consumption. It diminishes toward lower tertiary butanol concentrations (delta[t-BuOH]/delta[O3] approximately 0.17 at [t-BuOH]0 = 1 x 10(-4) M). Part of the effect of the ozone, apart from being a source of *OH radicals, rests on the intervention of HO2*/O2*- which is produced in the course of the peroxyl-radical chemistry of the tertiary butanol in this dioxygen-saturated environment and converted into further *OH radical by reaction with ozone. Moreover in this system, organic free radicals and peroxyl radicals react with the ozone. On the basis of the experimental and mechanistic-simulation data, the quantum yield of direct (by hv) ozone cleavage in aqueous solution is estimated at about 0.5.


Assuntos
Modelos Teóricos , Oxidantes Fotoquímicos/química , Ozônio/química , terc-Butil Álcool/química , Radical Hidroxila/química , Oxidantes/química , Fotólise
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