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1.
Nano Lett ; 14(11): 6644-50, 2014 Nov 12.
Artículo en Inglés | MEDLINE | ID: mdl-25322197

RESUMEN

Conventional solar cells exhibit limited efficiencies in part due to their inability to absorb the entire solar spectrum. Sub-band-gap photons are typically lost but could be captured if a material that performs up-conversion, which shifts photon energies higher, is coupled to the device. Recently, molecular chromophores that undergo triplet-triplet annihilation (TTA) have shown promise for efficient up-conversion at low irradiance, suitable for some types of solar cells. However, the molecular systems that have shown the highest up-conversion efficiency to date are ill suited to broadband light harvesting, reducing their applicability. Here we overcome this limitation by combining an organic TTA system with highly fluorescent CdSe semiconductor nanocrystals. Because of their broadband absorption and spectrally narrow, size-tunable fluorescence, the nanocrystals absorb the radiation lost by the TTA chromophores, returning this energy to the up-converter. The resulting nanocrystal-boosted system shows a doubled light-harvesting ability, which allows a green-to-blue conversion efficiency of ∼12.5% under 0.5 suns of incoherent excitation. This record efficiency at subsolar irradiance demonstrates that boosting the TTA by light-emitting nanocrystals can potentially provide a general route for up-conversion for different photovoltaic and photocatalytic applications.

2.
Sci Total Environ ; 917: 170352, 2024 Mar 20.
Artículo en Inglés | MEDLINE | ID: mdl-38286293

RESUMEN

The contamination of indoor areas is a global health problem that can cause the dispersion of infectious diseases. In that sense, it is urgent to find new strategies applying a lower concentration of the traditional chemicals used for cleaning and disinfection. Ultraviolet radiation (UV), in particular far-UV-C (200-225 nm), has emerged as a successful, powerful, easy-to-apply, and inexpensive approach for bacterial eradication that still requires scientific assessment. This study investigated new strategies for disinfection based on far-UV-C (222 nm) combined with chlorine and mechanical cleaning, providing an innovative solution using low doses. The bactericidal activity of far-UV-C (222 nm) was tested at an intensity of irradiation from 78.4 µW/cm2 to 597.7 µW/cm2 (for 1 min) against Escherichia coli and Staphylococcus epidermidis adhered on polystyrene microtiter plates. It was further tested in combination with mechanical cleaning (ultrasounds for 1 min) and free chlorine (0.1, 0.5, and 1 mg/L for 5 min). The triple combination consisting of mechanical cleaning + free chlorine (0.5 mg/L) + far-UV-C (54 mJ/cm2) was tested against cells adhered to materials found in hospital settings and other public spaces: polyvinyl chloride (PVC), stainless steel (SS), and polyetheretherketone (PEEK). Disinfection with far-UV-C (54 mJ/cm2) and free chlorine at 0.5 mg/L for 5 min allowed a total reduction of culturable E. coli cells and a logarithmic reduction of 2.98 ± 0.03 for S. epidermidis. The triple combination of far-UV-C, free chlorine, and mechanical cleaning resulted in a total reduction of culturable cells for both adhered bacteria. Bacterial adhesion to PVC, SS, and PEEK occurred at distinct extents and influenced the bactericidal activity of the triple combination, with logarithmic reductions of up to three. The overall results highlight that, based on culturability assessment, far-UV-C (54 mJ/cm2) with chlorine (0.5 mg/L; 5 min) and mechanical cleaning (1 min) as an efficient disinfection strategy using mild conditions. The combination of culturability and viability assessment of disinfection is recommended to detect regrowth events and increase the effectiveness in microbial growth control.


Asunto(s)
Benzofenonas , Escherichia coli , Polímeros , Rayos Ultravioleta , Staphylococcus epidermidis , Cloro/farmacología , Cloro/química , Desinfección/métodos , Cloruros
3.
Braz J Biol ; 84: e281457, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38896729

RESUMEN

Cowpea is a leguminous plant belonging to the fabaceae family cultivated in the North and Northeast regions of Brazil, with productive potential. Among the abiotic factors, water deficiency is one of the main environmental limitations that influence agricultural production in the world. The objective of this work was to study the relative water content and osmoregulators of cowpea plants subjected to water stress. The experiment was carried out in a greenhouse at the Universidade Federal Rural da Amazônia (UFRA, Belém, PA), cowpea plants BR-17 Gurguéia Vigna unguiculata (L.) Walp were used. The experimental design was completely randomized (DIC) in a 2 × 2 factorial scheme, two water conditions (control and water deficit) and two times of stress (four and six days of water suspension), with 7 replications, totaling 28 experimental units. The water deficit affected plants, causing a reduction in relative water content (69.98%), starch (12.84% in leaves and 23.48% in roots) and carbohydrates (84.34%), and an increase in glycine-betaine, sucrose (114.11% in leaves and 18.71% in roots) and proline (358.86%) at time 2. The relative water content was negatively affected by water conditions, with a decrease in relation to the interaction of the aerial part and the root system. Therefore, greater metabolic responses were noted in plants that were subjected to stress treatment at time 2 (6 days).


Asunto(s)
Vigna , Agua , Deshidratación , Osmorregulación/fisiología , Betaína/análisis
4.
Hum Reprod ; 25(8): 2101-6, 2010 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-20576636

RESUMEN

BACKGROUND: Changes in the endometrium are not regulated exclusively by ovarian hormones; the immune system has also been implicated in normal endometrial function, similar to processes taking place during inflammatory and reparative path. Many cytokines are crucially important for reproductive processes, and the role of cytokines in the female reproductive system function has been broadly investigated during controlled ovarian stimulation (COS) for IVF attempts. The aim of this study was to evaluate the levels of serum cytokines and hormones, and the clinical outcomes of women who underwent COS and ICSI procedures. METHODS: The study prospectively included 96 patients (aged 22-43 years, unexplained or male infertility, n = 61; female infertility factors, n = 35) who underwent ICSI cycles. Serum levels of interleukin (IL-8, IL-6, IL-1beta, IL-10, IL-12), tumour necrosis factor and leukaemia-inhibitory factor (LIF) and the hormones FSH, estradiol, progesterone, anti-Mullerian hormone and Inhibin-B were measured on the day of oocyte retrieval. RESULTS: The ongoing pregnancy rate was 25.3%. The presence of serum IL-1beta positively affected the implantation rate (P = 0.004) and increased the chance of becoming pregnant by 15 fold. Furthermore, the percentage of patients with detectable serum IL-1beta levels who conceived (62.5%) was higher than those who failed to conceive (37.5%; P = 0.019). The LIF was undetectable in all serum samples, and no other factors influenced the clinical outcomes of patients undergoing ICSI cycles. CONCLUSIONS: Our findings revealed that detectable serum levels of IL-1beta on the day of oocyte retrieval in patients undergoing COS and ICSI are predictive of successful implantation and ongoing pregnancy.


Asunto(s)
Citocinas/sangre , Hormonas Gonadales/sangre , Interleucina-1beta/sangre , Inducción de la Ovulación , Adulto , Implantación del Embrión , Femenino , Humanos , Recuperación del Oocito , Embarazo , Resultado del Embarazo , Índice de Embarazo
5.
Andrology ; 7(2): 213-219, 2019 03.
Artículo en Inglés | MEDLINE | ID: mdl-30570220

RESUMEN

BACKGROUND: Regulatory bodies recommend inconsistent ejaculatory abstinence lengths before semen analysis. The literature exploring the effect of ejaculatory abstinence length on the outcomes of intracytoplasmic sperm injection is scarce. OBJECTIVE: To study the influence of ejaculatory abstinence length on semen quality and intracytoplasmic sperm injection outcomes. MATERIALS AND METHODS: This prospective cohort study included 818 patients undergoing conventional semen analysis from October 2015 to October 2016, in a private university-affiliated IVF centre. Generalized linear models adjusted for potential confounders were used to investigate the associations between ejaculatory abstinence length and seminal parameters and intracytoplasmic sperm injection outcomes. RESULTS: Increasing ejaculatory abstinence length was positively correlated with semen volume, sperm concentration, total sperm count, total motile sperm count and sperm DNA fragmentation index. Significant inverse correlations were observed between ejaculatory abstinence length and fertilization rate, blastocyst formation rate, implantation rate and pregnancy rate. A discriminant analysis showed a mean ejaculatory abstinence length in the positive pregnancy group of 3.14 ± 1.64 days and 4.83 ± 3.66 days in the negative pregnancy group. A cut-off point was established halfway between ejaculatory abstinence length averages, at 4 days. The ejaculatory abstinence ≤4 days group showed significant lower semen volume, sperm concentration, total sperm count and total motile sperm count compared to ejaculatory abstinence > 4 days group. The ejaculatory abstinence ≤ 4 days group showed significant lower sperm DNA fragmentation index, and higher rates of fertilization, high-quality embryos on day 3, blastocyst development, implantation and pregnancy compared to ejaculatory abstinence > 4 days group. The implantation rate was significantly higher and the pregnancy rate tended to be higher with one day of ejaculatory abstinence, compared to 2-4 days of ejaculatory abstinence. CONCLUSIONS: Ejaculatory abstinence periods of >4 days have a detrimental effect on sperm DNA and intracytoplasmic sperm injection outcomes. One day of ejaculatory abstinence significantly improves implantation rate and tends to increase pregnancy rate, compared to 2, 3 and 4 days of ejaculatory abstinence.


Asunto(s)
Eyaculación , Análisis de Semen/métodos , Abstinencia Sexual , Inyecciones de Esperma Intracitoplasmáticas/métodos , Estudios de Cohortes , Humanos , Masculino , Estudios Prospectivos
6.
Hum Fertil (Camb) ; 11(4): 254-8, 2008 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-19085262

RESUMEN

OBJECTIVE: Professionals involved in assisted reproductive technologies (ART) have in-depth awareness and knowledge of the risks of multiple pregnancies at the conclusion of in vitro fertilization (IVF) treatment. The aim of the study was to investigate ART professionals' attitudes towards the awareness of the risk of infertility, as well as the decision-making process in IVF issues. METHODS: Seventy ART professionals answered a questionnaire covering demographic data, infertility awareness and attitudes towards IVF. RESULTS: Approximately half (50.8%) of the participants thought that they were not at risk of infertility. However, if they received a diagnosis of infertility, none would accept childlessness and almost all would undergo IVF. In an IVF cycle, the number of high-quality embryos transferred would be around three, but if treatment was extended to a third cycle, a higher percentage of participants would elect to transfer four or more embryos. All participants would prefer to undergo IVF and accept the risk of multiple pregnancy than remaining childless. It was found that less than a third of ART professionals considered triplets to be an unacceptable complication of IVF. CONCLUSIONS: Diagnosis of infertility affects all participants psychosocially, supporting the idea that the emotional aspects of wanting a biological child, and decision making about whether to undertake ART, outweigh the medical position regarding the risks and benefits of IVF.


Asunto(s)
Actitud , Concienciación , Fertilización In Vitro/psicología , Niño , Estudios Transversales , Femenino , Encuestas Epidemiológicas , Humanos , Infertilidad Femenina/epidemiología , Infertilidad Femenina/psicología , Infertilidad Masculina/epidemiología , Infertilidad Masculina/psicología , Masculino , Médicos/psicología , Conducta Reproductiva/psicología , Encuestas y Cuestionarios
7.
Andrology ; 2018 Feb 18.
Artículo en Inglés | MEDLINE | ID: mdl-29457367

RESUMEN

Human sperm morphology has been described as an essential parameter for the diagnosis of male infertility and a prognostic indicator of natural or assisted pregnancies. Nevertheless, standard morphological assessment remains a subjective analysis and its impact on intracytoplasmic sperm injection (ICSI) is also of limited value. The objective of this prospective cohort study was to investigate whether motile sperm organelle morphology examination (MSOME) can improve semen analysis by better defining male infertility and providing a better prognosis for ICSI up to a year later. Data were obtained from 483 patients undergoing conventional semen analysis from June 2015 to June 2017 in a private university-affiliated in vitro fertilization (IVF) center. The correlation of MSOME with seminal parameters was evaluated. One hundred and thirty patients underwent ICSI up to a year later, and the correlation between MSOME and ICSI outcomes was established. Except for volume, all seminal parameters were positively correlated with MSOME I+II. MSOME was also distinct between World Health Organization (WHO) classification groups, with normozoospermic and oligoasthenoteratozoospermic presenting the higher and the lower proportion of MSOME I+II, respectively. MSOME I+II was prognostic for fertilization rate, high-quality cleavage-stage embryos rate, and blastocyst rate. The normality cutoff value based on blastocyst rate was MSOME I+II≥ 5.5%. MSOME could be a useful tool for the diagnosis of infertility severity as it is correlated with sperm morphology, motility, and concentration. Men who had higher MSOME I+II had better ICSI outcomes. The future use of MSOME as a routine method for semen analysis may be a reliable form of assessing male infertility.

8.
Exp Biol Med (Maywood) ; 242(14): 1462-1470, 2017 08.
Artículo en Inglés | MEDLINE | ID: mdl-28661205

RESUMEN

Hemorrhagic shock is a leading cause of morbidity and mortality worldwide. Significant blood loss may lead to decreased blood pressure and inadequate tissue perfusion with resultant organ failure and death, even after replacement of lost blood volume. One reason for this high acuity is that the fundamental mechanisms of shock are poorly understood. Proteomic and metabolomic approaches have been used to investigate the molecular events occurring in hemorrhagic shock but, to our knowledge, a systematic analysis of the transcriptomic profile is missing. Therefore, a pilot analysis using paired-end RNA sequencing was used to identify changes that occur in the blood transcriptome of rats subjected to hemorrhagic shock after blood reinfusion. Hemorrhagic shock was induced using a Wigger's shock model. The transcriptome of whole blood from shocked animals shows modulation of genes related to inflammation and immune response (Tlr13, Il1b, Ccl6, Lgals3), antioxidant functions (Mt2A, Mt1), tissue injury and repair pathways (Gpnmb, Trim72) and lipid mediators (Alox5ap, Ltb4r, Ptger2) compared with control animals. These findings are congruent with results obtained in hemorrhagic shock analysis by other authors using metabolomics and proteomics. The analysis of blood transcriptome may be a valuable tool to understand the biological changes occurring in hemorrhagic shock and a promising approach for the identification of novel biomarkers and therapeutic targets. Impact statement This study provides the first pilot analysis of the changes occurring in transcriptome expression of whole blood in hemorrhagic shock (HS) rats. We showed that the analysis of blood transcriptome is a useful approach to investigate pathways and functional alterations in this disease condition. This pilot study encourages the possible application of transcriptome analysis in the clinical setting, for the molecular profiling of whole blood in HS patients.


Asunto(s)
Células Sanguíneas/patología , Perfilación de la Expresión Génica , Choque Hemorrágico/patología , Animales , Modelos Animales de Enfermedad , Masculino , Ratas Wistar , Análisis de Secuencia de ARN
9.
Chem Commun (Camb) ; 52(79): 11815-11818, 2016 Sep 27.
Artículo en Inglés | MEDLINE | ID: mdl-27722256

RESUMEN

Alloying isomorphous crystals of barbituric acid (BA) and thiobarbituric acid (TBA) yields solid solutions of general formula BAxTBA1-x (x < 0.8); for x = 0.5 the stable co-crystal BA0.5TBA0.5, isomorphous with the parent keto forms, is observed, which melts at 265 °C, i.e. ca. 10 and 20 °C higher than the melting points of BA and TBA, respectively. While the BAxTBA1-x solid solutions with x > 0.5 are stable, those with x < 0.5 convert, with time or temperature, to the BA0.5TBA0.5 co-crystal.

10.
Andrology ; 4(5): 880-6, 2016 09.
Artículo en Inglés | MEDLINE | ID: mdl-27152971

RESUMEN

The objective of this study was to compare (i) the intracytoplasmic sperm injection outcomes among groups with different total motile sperm count ranges, (ii) the intracytoplasmic sperm injection outcomes between groups with normal and abnormal total motile sperm count, and (iii) the predictive values of WHO 2010 cut-off values and pre-wash total motile sperm count for the intracytoplasmic sperm injection outcomes, in couples with male infertility. This study included data from 518 patients undergoing their first intracytoplasmic sperm injection cycle as a result of male infertility. Couples were divided into five groups according to their total motile sperm count: Group I, total motile sperm count <1 × 10(6) ; group II, total motile sperm count 1-5 × 10(6) ; group III, total motile sperm count 5-10 × 10(6) ; group IV, total motile sperm count 10-20 × 10(6) ; and group V, total motile sperm count >20 × 10(6) (which was considered a normal total motile sperm count value). Then, couples were grouped into an abnormal and normal total motile sperm count group. The groups were compared regarding intracytoplasmic sperm injection outcomes. The predictive values of WHO 2010 cut-off values and total motile sperm count for the intracytoplasmic sperm injection outcomes were also investigated. The fertilization rate was lower in total motile sperm count group I compared to total motile sperm count group V (72.5 ± 17.6 vs. 84.9 ± 14.4, p = 0.011). The normal total motile sperm count group had a higher fertilization rate (84.9 ± 14.4 vs. 81.1 ± 15.8, p = 0.016) and lower miscarriage rate (17.9% vs. 29.5%, p = 0.041) compared to the abnormal total motile sperm count group. The total motile sperm count was the only parameter that demonstrated a predictive value for the formation of high-quality embryos on D2 (OR: 1.18, p = 0.013), formation of high-quality embryos on D3 (OR: 1.12, p = 0.037), formation of blastocysts on D5 (OR: 1.16, p = 0.011), blastocyst expansion grade on D5 (OR: 1.27, p = 0.042), and the odds of miscarriage (OR: 0.52, p < 0.045). The total motile sperm count has a greater predictive value than the WHO 2010 cut-off values for laboratory results and pregnancy outcomes in couples undergoing intracytoplasmic sperm injection as a result of male infertility.


Asunto(s)
Fertilización/fisiología , Infertilidad Masculina/terapia , Inyecciones de Esperma Intracitoplasmáticas , Motilidad Espermática , Espermatozoides/citología , Adulto , Transferencia de Embrión , Femenino , Humanos , Masculino , Embarazo , Resultado del Embarazo , Índice de Embarazo , Recuento de Espermatozoides
11.
Dalton Trans ; 45(44): 17939-17947, 2016 Nov 28.
Artículo en Inglés | MEDLINE | ID: mdl-27781225

RESUMEN

Three copper(i) complexes have been obtained by the reaction of CuI with 3-picolylamine in acetonitrile solution and characterized by X-ray powder diffraction, both from synchrotron and laboratory radiation. Photophysical investigations in the solid state revealed highly efficient thermally-activated delayed fluorescence (TADF) with photoluminescence quantum yields (PLQYs) up to 18%. Notably, the complex [Cu2I2(3pica)]∞ displays a strong luminescence thermochromism due to the presence of both 1,3(X + M)LCT excited states and a lower-lying cluster-centered (3CC) one, leading to multiple emission at room temperature; as a result, a white luminescence is achieved with a PLQY of 4.5%.

12.
Genetics ; 150(4): 1663-82, 1998 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-9832541

RESUMEN

The complex polyploid genomes of three Saccharum species have been aligned with the compact diploid genome of Sorghum (2n = 2x = 20). A set of 428 DNA probes from different Poaceae (grasses) detected 2460 loci in F1 progeny of the crosses Saccharum officinarum Green German x S. spontaneum IND 81-146, and S. spontaneum PIN 84-1 x S. officinarum Muntok Java. Thirty-one DNA probes detected 226 loci in S. officinarum LA Purple x S. robustum Molokai 5829. Genetic maps of the six Saccharum genotypes, including up to 72 linkage groups, were assembled into "homologous groups" based on parallel arrangements of duplicated loci. About 84% of the loci mapped by 242 common probes were homologous between Saccharum and Sorghum. Only one interchromosomal and two intrachromosomal rearrangements differentiated both S. officinarum and S. spontaneum from Sorghum, but 11 additional cases of chromosome structural polymorphism were found within Saccharum. Diploidization was advanced in S. robustum, incipient in S. officinarum, and absent in S. spontaneum, consistent with biogeographic data suggesting that S. robustum is the ancestor of S. officinarum, but raising new questions about the antiquity of S. spontaneum. The densely mapped Sorghum genome will be a valuable tool in ongoing molecular analysis of the complex Saccharum genome.


Asunto(s)
ADN de Plantas , Diploidia , Plantas Comestibles/genética , Poliploidía , Grano Comestible/genética , Duplicación de Gen , Reordenamiento Génico , Genoma de Planta , Polimorfismo Genético , Recombinación Genética
14.
Dalton Trans ; 44(29): 13003-6, 2015 Aug 07.
Artículo en Inglés | MEDLINE | ID: mdl-26145149

RESUMEN

Solid [CuI(piperazine)0.5]∞, characterized by a structure with an infinite double chain of CuI, presents an unexpected dual luminescence. The short copper-copper distances allow the existence of both cluster-centered and 1-D delocalized electronic transitions, as emerged from theoretical calculations. Beyond the more common cluster-centered emission a higher energy band, which differs in lifetime and in temperature dependence, is observed.

15.
Andrology ; 3(4): 723-8, 2015 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-26122368

RESUMEN

The present case-control study aimed to identify the effect of sperm cryopreservation on the quality of the embryo and on the probability of blastocyst formation when oocytes free of dimorphisms are injected and when at least one dymorphism is present. The study included 22 186 zygotes, obtained from 2802 patients undergoing intracytoplasmic sperm injection cycles, in a private assisted reproduction center, using either fresh or cryopreserved sperm. The effect of sperm cryopreservation on the embryo quality on cleavage stage and blastocyst formation chance were evaluated when oocytes free of dimorphisms are injected and when at least one dymorphism is present. The quality of the embryo on cleavage stage as well as the chance for blastocyst formation was not influenced by the origin of the spermatozoa when the quality of the oocyte was not considered. When at least one oocyte defect was present, a negative influence of sperm cryopreservation on cleavage stage embryo quality and the chance for blastocyst formation was noted. In oocytes with extra-cytoplasmic dimorphisms, the injection of cryopreserved sperm did not affect the quality of the embryo during the cleavage stage, but did affect the chance for blastocyst formation. Conversely, in oocytes with intracytoplasmic defects, the quality of the embryos on cleavage stage and the chance of blastocyst formation were negatively influenced by the injection of cryopreserved sperm. The results suggest an oocyte quality-dependent negative effect of sperm cryopreservation on embryo quality and on the probability of blastocyst formation.


Asunto(s)
Criopreservación/estadística & datos numéricos , Desarrollo Embrionario , Oocitos/citología , Inyecciones de Esperma Intracitoplasmáticas/estadística & datos numéricos , Espermatozoides , Adulto , Estudios de Casos y Controles , Femenino , Humanos , Masculino , Embarazo
16.
Stud Health Technol Inform ; 216: 1104, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-26262403

RESUMEN

This article describes the process of building an ontology to assist medical students and professionals specialized in Oncology. The ontology allows the user to obtain knowledge more quickly and thus assist professionals in their decision-making.


Asunto(s)
Ontologías Biológicas , Neoplasias de la Mama/clasificación , Minería de Datos/métodos , Internet/organización & administración , Oncología Médica/organización & administración , Procesamiento de Lenguaje Natural , Femenino , Humanos
17.
Immunol Lett ; 49(1-2): 27-30, 1996 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-8964605

RESUMEN

The CD40 ligand (CD40L) is a molecule expressed by activated T cells which plays a critical role in the regulation of B-cell responses, including differentiation into Ig-producing cells. Using the specific monoclonal antibody TRAP1 we have evaluated the ontogeny of CD40L expression in 97 normal individuals between birth and 50 years of age. The expression of CD40L is a function of age; it is severely reduced at birth, progressively increases during the first months of life, and reaches a plateau in the second decade. This progressive attainment of the ability to express CD40L is due to a process of maturation of the CD4 + subset, being significantly correlated with the expression of the CD45RO antigen.


Asunto(s)
Linfocitos T CD4-Positivos/metabolismo , Activación de Linfocitos , Glicoproteínas de Membrana/biosíntesis , Adolescente , Adulto , Factores de Edad , Anticuerpos Monoclonales/inmunología , Ligando de CD40 , Niño , Preescolar , Humanos , Lactante , Recién Nacido , Antígenos Comunes de Leucocito/biosíntesis , Glicoproteínas de Membrana/inmunología , Persona de Mediana Edad
18.
Chemistry ; 6(8): 1310-7, 2000 Apr 14.
Artículo en Inglés | MEDLINE | ID: mdl-10840952

RESUMEN

Depending on the stoichiometric ratio, squaric acid (3,4-dihydroxy-3-cyclobutene-1,2-dione, H2SQA) reacts with [(eta6-C6H6)2Cr] in THF to form the crystalline material [(eta6-C6H6)2Cr][HSQA] (1) and in water to yield [[(eta6-C6H6)2Cr]2][SQA] x 6H2O (3); it also reacts with [(eta5-C5H5)2Co][OH] in water to form [[(eta5-C5H5)2Co]2][SQA] x 6H2O (4). Compound 1 is almost isostructural with the previously reported salt [(eta5-C5H5)2Co][HSQA] (2); its structure is based on pi-pi stacks between the benzene ligands and the hydrogen squarate anionic chains (pi-pi distance 3.375 A). Compounds 3 and 4 are isomorphous and have a structure in which layers of organometallic cations intercalate with layers of water molecules hydrogen bonded to squarate dianions. All crystals contain charge-assisted C-Hdelta+...Odelta- hydrogen bonds between the organometallic and the organic components, while negative O-H(-)...O(-) and O-H...O(2-) interactions are present in the pairs 1/3 and 2/4, respectively. In constrast to most organic salts of [(eta6-C6H6)2Cr]+ and [(eta5-C5H5)2Co]+ which are yellow, crystals of compounds 1-4 are orange. Reflectance spectra measured on the crystalline material 1 show the presence of an intense tail that can be assigned to a charge-transfer transition through the [(eta6-C6H6)2Cr]+/[HSQA]- pi-stacking interactions, while the pi stacking in 2 causes only a broadening of the band. The magnetic behaviour of 1 and 3 has been investigated by SQUID magnetometry. Both compounds are characterised by a weak antiferromagnetic interaction between the S=1/2 Cr centres of the [(eta6-C6H6)2Cr]+ cations, which is significantly stronger in 1 due to the pi-stacking with the HSQA- anions.

19.
Chem Commun (Camb) ; (21): 2272-3, 2001 Nov 07.
Artículo en Inglés | MEDLINE | ID: mdl-12240146

RESUMEN

Exposure of the solid zwitterion [CoIII(eta 5-C5H4CO2H)(eta 5-C5H4CO2)] to hydrated vapours of volatile acids (HCl, CF3CO2H, HBF4) or bases (NH3, NMe3, NH2Me) quantitatively produces the corresponding salts; the heterogeneous reactions are fully reversible, as the acid or base molecules can be removed by thermal treatment, regenerating the starting material.

20.
Cutis ; 53(2): 92-4, 1994 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-7851130

RESUMEN

A single case of trichorhinophalangeal syndrome, type I, is reported. The patient manifested the complete triad of the syndrome: thin, sparse, slow-growing scalp hairs; a pear-shaped nose; and cone-shaped epiphysis in some interphalangeal articulations of both hands. In addition, tooth decay, pectus carinatum, lumbar scoliosis, and polycystic ovary were observed. This multisystemic disorder is apparently rare, but its prevalence is probably underestimated in the dermatologic literature.


Asunto(s)
Dedos/anomalías , Cabello/anomalías , Nariz/anomalías , Anomalías Múltiples , Adulto , Epífisis/anomalías , Femenino , Articulaciones de los Dedos/anomalías , Humanos , Síndrome del Ovario Poliquístico/patología , Escoliosis/patología , Esternón/anomalías , Síndrome
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