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1.
Nanoscale ; 12(27): 14699-14707, 2020 Jul 16.
Article in English | MEDLINE | ID: mdl-32618310

ABSTRACT

The direct reaction between Cu(CH3COO)2 and uracil-1-acetic acid in water gives rise to the formation of a hydrogel consisting of entangled nanometric ribbons of a crystalline antiferromagnetic 1D Cu(ii) coordination polymer (CP) decorated with biocompatible uracil nucleobases. This hydrogel is the precursor for the preparation of a meso/macroporous ultralight aerogel that shows a remarkable Young's modulus. As a proof-of-concept of the molecular recognition capability of the terminal uracil moieties anchored at Cu(ii) CP chains, this material has been tested as the selective stationary phase for the separation of nucleobase derivatives in HPLC columns.


Subject(s)
Nanofibers , Copper , Hydrogels , Metals , Polymers
2.
SEMERGEN, Soc. Esp. Med. Rural Gen. (Ed. Impr.) ; 46(2): 90-100, mar. 2020. tab, graf
Article in Spanish | IBECS | ID: ibc-195627

ABSTRACT

INTRODUCCIÓN: Varios estudios han identificado un peor control de los factores de riesgo cardiovascular en el sexo femenino en pacientes con diabetes tipo 2. Una de sus causas podría ser el desconocimiento sobre el perfil de riesgo cardiovascular de la mujer con diabetes tipo 2 por parte de los profesionales. OBJETIVO: Conocer la percepción y el conocimiento de los profesionales de la salud involucrados en el manejo de los pacientes con diabetes tipo 2, del impacto que las diferencias de género tienen en el control de los factores de riesgo cardiovascular en estos pacientes. MÉTODO: Se envió una encuesta de 24 preguntas relacionadas con el conocimiento y percepción (agrupadas por temas) a profesionales interesados e involucrados en el cuidado de pacientes con diabetes tipo 2. Se analizaron 998 encuestas. Construimos un modelo de ANOVA para comparar los resultados por especialidad y años de experiencia ajustados por el resto de las variables de confusión y regresión logística para estudiar los factores que podían influir en tener más de 12 respuestas adecuadas (resultado favorable). RESULTADOS: La media de respuestas correctas fue 10,3, discretamente mayor para especialistas (rango 10,7-11,8) y aumentaba con la experiencia (p = 0,001). Se encontró el género femenino y los años de experiencia como predictores de tener 12 o más respuestas correctas. CONCLUSIONES: El nivel de conocimientos sobre el tema es bajo, pero similar a los resultados de otros estudios sobre la relación del género con determinadas patologías


INTRODUCTION: Several studies have found poorer control of the cardiovascular risk factors among women with type 2 diabetes. This could be explained by the lack of awareness of their cardiovascular risk among professionals. AIMS: To determine the perception and knowledge of health care professionals involved in diabetes management on the impact of gender difference on the control of cardiovascular risk factors in patients with type 2 diabetes mellitus. METHODS: A 24-question survey related to knowledge and perceptions (grouped by topics) was sent to professionals who were interested and involved in diabetes care. A total of 998 surveys were analysed. An ANOVA model was constructed to compare the results by specialty and years of experience, as well as adjusting for the rest of the confounding factors. On having more than 12 correct answers (favourable result), a logistic regression was also performed in order to study the factors that could have an influence. RESULTS: The mean number of correct answers was 10.3, and was slightly better for specialists (range 10.7-11.8), and associated with years of experience (P=.001). Female gender and years of experience were identified as predictors of having more than 12 correct answers. CONCLUSIONS: The level of knowledge was low, but similar to the results of the other studies


Subject(s)
Humans , Male , Female , Young Adult , Adult , Middle Aged , Cardiovascular Diseases/etiology , Diabetes Mellitus, Type 2/complications , Health Knowledge, Attitudes, Practice , Health Personnel/statistics & numerical data , Risk Factors , Sex Factors , Surveys and Questionnaires
3.
Semergen ; 46(2): 90-100, 2020 Mar.
Article in Spanish | MEDLINE | ID: mdl-31831323

ABSTRACT

INTRODUCTION: Several studies have found poorer control of the cardiovascular risk factors among women with type 2 diabetes. This could be explained by the lack of awareness of their cardiovascular risk among professionals. AIMS: To determine the perception and knowledge of health care professionals involved in diabetes management on the impact of gender difference on the control of cardiovascular risk factors in patients with type 2 diabetes mellitus. METHODS: A 24-question survey related to knowledge and perceptions (grouped by topics) was sent to professionals who were interested and involved in diabetes care. A total of 998 surveys were analysed. An ANOVA model was constructed to compare the results by specialty and years of experience, as well as adjusting for the rest of the confounding factors. On having more than 12 correct answers (favourable result), a logistic regression was also performed in order to study the factors that could have an influence. RESULTS: The mean number of correct answers was 10.3, and was slightly better for specialists (range 10.7-11.8), and associated with years of experience (P=.001). Female gender and years of experience were identified as predictors of having more than 12 correct answers. CONCLUSIONS: The level of knowledge was low, but similar to the results of the other studies.


Subject(s)
Cardiovascular Diseases/etiology , Diabetes Mellitus, Type 2/complications , Health Knowledge, Attitudes, Practice , Health Personnel/statistics & numerical data , Adult , Female , Humans , Male , Middle Aged , Risk Factors , Sex Factors , Surveys and Questionnaires , Young Adult
4.
J Med Life ; 10(4): 237-243, 2017.
Article in English | MEDLINE | ID: mdl-29362599

ABSTRACT

The objective of the study was to assess the clinical, histopathological and immunochemical changes induced by dialyzable leukocyte extract (DLE) treatment in patients with chronic cervicitis associated to HPV infection. Fifty-four female Mexican patients diagnosed with chronic cervicitis, cervical intra-epithelial neoplasia grade 1 (CIN 1) and HPV infection were divided into two groups: patients treated with placebo and patients treated with DLE. Clinical and colposcopy evaluations were performed before and after treatments. Cervix biopsies were obtained to analyze histopathological features and to determine the local immunological changes by immunohistochemistry analyses. Placebo-treated patients showed no significant changes in the evaluated parameters. Interestingly, in DLE-treated patients, clinical manifestations of cervicitis diminished and 89% of them remitted the colposcopic lesions. Histological analyses of biopsies from DLE-treated patients showed a decreasing leukocyte infiltrate. Immunochemical analyses showed an increased expression of TGF-ß, while expression of IFN-γ, PCNA, and IL-32 decreased. Our results suggest that DLE can stimulate innate immunity of cervical mucosae, diminishing chronic cervicitis in HPV-infected patients. TRIAL REGISTRATION: Register ISRCTN16429164 Abbreviations: HPV = Human Papilloma Virus; DLE = Dialyzable leukocyte extract.


Subject(s)
Papillomavirus Infections/complications , Transfer Factor/therapeutic use , Uterine Cervicitis/complications , Uterine Cervicitis/drug therapy , Adult , Aged , Biopsy , Cervix Uteri/diagnostic imaging , Cervix Uteri/pathology , Chronic Disease , Colposcopy , Female , Humans , Immunohistochemistry , Interferon-gamma/metabolism , Interleukins/metabolism , Middle Aged , Papillomavirus Infections/virology , Proliferating Cell Nuclear Antigen/metabolism , Transforming Growth Factor beta/metabolism , Uterine Cervicitis/diagnostic imaging , Uterine Cervicitis/pathology , Young Adult
5.
Inorg Chem ; 54(22): 10738-47, 2015 Nov 16.
Article in English | MEDLINE | ID: mdl-26501154

ABSTRACT

The properties recently reported on the Cu(I)-iodide pyrimidine nonporous 1D-coordination polymer [CuI(ANP)]n (ANP = 2-amino-5-nitropyridine) showing reversible physically and chemically driven electrical response have prompted us to carry a comparative study with the series of [CuX(ANP)]n (X = Cl (1), X = Br (2), X = CN (4), and X = SCN (5)) in order to understand the potential influence of the halide and pseudohalide bridging ligands on the physical properties and their electrical response to vapors of these materials. The structural characterization of the series shows a common feature, the presence of -X-Cu(ANP)-X- (X = Cl, Br, I, SCN) double chain structure. Complex [Cu(ANP)(CN)]n (4) presents a helical single chain. Additionally, the chains show supramolecular interlinked interactions via hydrogen bonding giving rise to the formation of extended networks. Their luminescent and electrical properties have been studied. The results obtained have been correlated with structural changes. Furthermore, the experimental and theoretical results have been compared using the density functional theory (DFT). The electrical response of the materials has been evaluated in the presence of vapors of diethyl ether, dimethyl methylphosphonate (DMMP), CH2Cl2, HAcO, MeOH, and EtOH, to build up simple prototype devices for gas detectors. Selectivity toward gases consisting of molecules with H-bonding donor or acceptor groups is clearly observed. This selective molecular recognition is likely due to the 2-amino-5-nitropyridine terminal ligand.

6.
Chem Commun (Camb) ; 51(76): 14306-9, 2015 Oct 01.
Article in English | MEDLINE | ID: mdl-26264525

ABSTRACT

We present a structurally flexible copper-iodide-pyridine-based coordination polymer showing drastic variations in its electrical conductivity driven by temperature and sorption of acetic acid molecules. The dramatic effect on the electrical conductivity enables the fabrication of a simple and robust device for gas detection. X-ray diffraction studies and DFT calculations allow the rationalisation of these observations.

7.
Dalton Trans ; 43(29): 11371-5, 2014 Aug 07.
Article in English | MEDLINE | ID: mdl-24926964

ABSTRACT

The first nickel(ii) complex with the heteroscorpionate-like bridging ligand DIMMAL (2-di1H-2-imidazolylmethylmalonate), [Ni(DIMMAL)(H2O)3]n·3nH2O (1), is a one-dimensional coordination polymer whose structure shows regular Ni(ii) chains with H-bonding inter-chain interactions and a rare example of a Quadruple Imidazolyl Embrace (QIE). The Ni(ii) chain shows a weak antiferromagnetic interaction that can be modelled with a regular S = 1 chain model including a zero field splitting with g = 2.270, J = -1.5 cm(-1) and D = -2.26 cm(-1).

8.
Allergol. immunopatol ; 40(6): 379-384, nov.-dic. 2012. tab, graf
Article in English | IBECS | ID: ibc-107720

ABSTRACT

Background: Allergic diseases are very common, with the estimated cumulative prevalence in Colombia for asthma and allergic rhinitis being 22.7% and 31.3% respectively, and with a clear upward trend. A major social as well as economic impact associated with allergic disease has been described. Because in Colombia there are no studies that assess the Health-Related Quality of Life (HRQOL) in allergic respiratory diseases, our aim is to describe the HRQOL in subjects with respiratory allergy and its association with clinical control variables. Methods: A prospective descriptive study was conducted among 76 Colombian subjects with rhinitis and asthma/allergic rhinitis. In order to evaluate the HRQOL, the instruments Kidscreen-27 and SF-36 were applied. The scores obtained in the HRQOL fields were correlated with the following clinical variables: peak expiratory flow (PEF) and peak nasal inspiratory flow (PNIF). Results: In children, the better HRQL domain is present in the school environment (55.9) and the worst in psychological well-being (39.9). For adults the worst HRQL was found in the emotional function domain (55.6) while the physical function (81.7) had the best. There were no statistical differences between groups of asthma/allergic rhinitis and allergic rhinitis. Subjects with allergic asthma showed a strong correlation between the mental health domain and PEF values (r=−0717, p=0.046). Conclusion: Mental health is more affected than physical health in Colombian subjects with respiratory allergy. There was a strong correlation between the mental health domain and the values of PEF in patients with asthma/allergic rhinitis(AU)


Subject(s)
Humans , Male , Female , Child , Asthma/epidemiology , Rhinitis/epidemiology , Quality of Life , Colombia/epidemiology , Child Health/statistics & numerical data , Prospective Studies
9.
Nutr. hosp ; 27(6): 1940-1944, nov.-dic. 2012. ilus
Article in Spanish | IBECS | ID: ibc-112177

ABSTRACT

El contacto precoz piel a piel provee beneficios para la madre y para el bebé, además de tener un papel importante en el establecimiento de la lactancia materna. Objetivo: El objetivo de este estudio fue informar a las madres de bebés pretérmino sobre la importancia del contacto piel con piel para la implantación de la lactancia materna y para un mejor vínculo entre ellos (cuidados centrados en el desarrollo CCD). Material y método: Se realizó un estudio de cohorte, prospectivo, en varios Hospitales de Cisjordania en Palestina, en el período de tiempo comprendido entre 2008 y 2011. El universo lo constituyó una estimación de un promedio de 2.500 partos anuales en cada hospital. Se determinó una población muestral de n = 252. Todos los recién nacidos tenían una edad gestacional inferior a 37 semanas y un peso inferior a 2.500 gramos y, por problemas de salud, fueron ingresados en unidades de encamación neonatal. Resultados: Este estudio ha puesto de manifiesto que en Palestina las mujeres jóvenes practican el contacto piel con piel y la lactancia materna con mayor frecuencia que las mujeres mayores; una vez informada de sus ventajas, muestran mayor interés en aprender los cuidados de sus bebés en las propias unidades de encamación neonatal. Conclusiones: La aplicación del contacto piel a piel (CCD) y la lactancia en bebés pretérmino ha sido posible mediante información e instrucción a las madres. Este estudio ha tenido una gran repercusión y ha sido muy bien aceptado por la población femenina. No existían estudios similares en ningún hospital de Palestina (AU)


In addition to its important role in the initiation of breastfeeding, early skin-to-skin contact benefits both mothers and their babies. Objective: To inform all mothers of premature babies about the importance of skin-to-skin contact and breast-feeding in order to foment a closer bond between mother and child (development-centered care). Materials and method: A prospective cohort study was conducted in various hospitals on the West Bank in Palestine during 2008-2011. The universe was made up of an estimated average of 2,500 childbirths per year in each hospital. All of the subjects in the sample population of n = 252 babies had a gestational age of less than 37 GWs, and had weighed less than 2,500 grams at birth. For health reasons, they were hospitalized in neonatal care units. Results: The results obtained showed that in Palestine, young women tend to breastfeed their babies and have skin-to-skin contact with them more often than older mothers. Once the new mothers were informed of the advantages of these practices, they showed greater interest in learning how to care for their babies in the neonatal care units. Conclusions: Breastfeeding premature babies as well as having skin-to-skin contact with them was made possible by informing and teaching new mothers about the advantages of this type of infant care. This research has had widespread impact and has been very well received by the female population in the country. This is the first study of its kind to be carried out in Palestine (AU)


Subject(s)
Humans , Male , Female , Infant, Newborn , Infant , Breast Feeding/statistics & numerical data , Infant, Premature/growth & development , Kangaroo-Mother Care Method , Arabs , Mother-Child Relations , Health Promotion , Health Education
10.
Curr Microbiol ; 65(4): 361-8, 2012 Oct.
Article in English | MEDLINE | ID: mdl-22711331

ABSTRACT

Acute gastroenteritis (AGE) is a major cause of childhood morbidity and mortality worldwide; the etiology of AGE includes viruses, bacteria, and parasites. A multiplex PCR assay to simultaneously identify human Astrovirus (HAstV), Calicivirus (HuCVs), Entamoeba histolytica (E. histolytica), and enteroinvasive Escherichia coli (EIEC) in stool samples is described. A total of 103 samples were individually analyzed by ELISA (enzyme-linked immunosorbent assays) and RT-PCR/PCR. HAstV and HuCVs were detected in four out of 103 samples (3.8 %) by RT-PCR, but ELISAs found only one sample as positive for HuCVs (2.5 %). E. histolytica was identified in two out of 19 samples (10.5 %) and EIEC in 13 out of 20 samples (70 %) by PCR, and all PCR products were sequenced to verify their identities. Our multiplex PCR results demonstrate the simultaneous amplification of different pathogens such as HAstV, EIEC, and E. histolytica in the same reaction, though the HuCVs signal was weak in every replicate. Regardless, this multiplex PCR protocol represents a novel tool for the identification of distinct pathogens and may provide support for the diagnosis of AGE in children.


Subject(s)
Caliciviridae/isolation & purification , Entamoeba histolytica/isolation & purification , Escherichia coli/isolation & purification , Gastroenteritis/diagnosis , Mamastrovirus/isolation & purification , Molecular Diagnostic Techniques/methods , Multiplex Polymerase Chain Reaction/methods , Child , Feces/microbiology , Feces/parasitology , Feces/virology , Gastroenteritis/microbiology , Gastroenteritis/parasitology , Gastroenteritis/virology , Humans , Mexico
11.
Allergol Immunopathol (Madr) ; 40(6): 379-84, 2012.
Article in English | MEDLINE | ID: mdl-22316550

ABSTRACT

BACKGROUND: Allergic diseases are very common, with the estimated cumulative prevalence in Colombia for asthma and allergic rhinitis being 22.7% and 31.3% respectively, and with a clear upward trend. A major social as well as economic impact associated with allergic disease has been described. Because in Colombia there are no studies that assess the Health-Related Quality of Life (HRQOL) in allergic respiratory diseases, our aim is to describe the HRQOL in subjects with respiratory allergy and its association with clinical control variables. METHODS: A prospective descriptive study was conducted among 76 Colombian subjects with rhinitis and asthma/allergic rhinitis. In order to evaluate the HRQOL, the instruments Kidscreen-27 and SF-36 were applied. The scores obtained in the HRQOL fields were correlated with the following clinical variables: peak expiratory flow (PEF) and peak nasal inspiratory flow (PNIF). RESULTS: In children, the better HRQL domain is present in the school environment (55.9) and the worst in psychological well-being (39.9). For adults the worst HRQL was found in the emotional function domain (55.6) while the physical function (81.7) had the best. There were no statistical differences between groups of asthma/allergic rhinitis and allergic rhinitis. Subjects with allergic asthma showed a strong correlation between the mental health domain and PEF values (r=-0717, p=0.046). CONCLUSION: Mental health is more affected than physical health in Colombian subjects with respiratory allergy. There was a strong correlation between the mental health domain and the values of PEF in patients with asthma/allergic rhinitis.


Subject(s)
Asthma/epidemiology , Quality of Life , Rhinitis, Allergic, Perennial/epidemiology , Rhinitis, Allergic, Seasonal/epidemiology , Stress, Psychological/epidemiology , Adolescent , Adult , Asthma/diagnosis , Child , Colombia/epidemiology , Female , Humans , Male , Mental Health/statistics & numerical data , Peak Expiratory Flow Rate , Prospective Studies , Rhinitis, Allergic, Perennial/diagnosis , Rhinitis, Allergic, Seasonal/diagnosis , Stress, Psychological/diagnosis , Surveys and Questionnaires , Young Adult
12.
Nutr Hosp ; 27(6): 1940-4, 2012.
Article in Spanish | MEDLINE | ID: mdl-23588442

ABSTRACT

UNLABELLED: In addition to its important role in the initiation of breastfeeding, early skin-to-skin contact benefits both mothers and their babies. OBJECTIVE: To inform all mothers of premature babies about the importance of skin-to-skin contact and breast-feeding in order to foment a closer bond between mother and child (development-centered care). MATERIALS AND METHOD: A prospective cohort study was conducted in various hospitals on the West Bank in Palestine during 2008-2011. The universe was made up of an estimated average of 2,500 childbirths per year in each hospital. All of the subjects in the sample population of n = 252 babies had a gestational age of less than 37 GWs, and had weighed less than 2,500 grams at birth. For health reasons, they were hospitalized in neonatal care units. RESULTS: The results obtained showed that in Palestine, young women tend to breastfeed their babies and have skin-to-skin contact with them more often than older mothers. Once the new mothers were informed of the advantages of these practices, they showed greater interest in learning how to care for their babies in the neonatal care units. CONCLUSIONS: Breastfeeding premature babies as well as having skin-to-skin contact with them was made possible by informing and teaching new mothers about the advantages of this type of infant care. This research has had widespread impact and has been very well received by the female population in the country. This is the first study of its kind to be carried out in Palestine.


Subject(s)
Breast Feeding , Infant, Premature , Adult , Age Factors , Cohort Studies , Female , Health Promotion , Humans , Infant, Newborn , Maternal Behavior , Middle East , Mother-Child Relations , Mothers , Prospective Studies , Young Adult
13.
Nutr Hosp ; 27(6): 2102-8, 2012.
Article in Spanish | MEDLINE | ID: mdl-23588463

ABSTRACT

UNLABELLED: During pregnancy, the prolonged stress and worry felt by mothers can alter the development and function of the right brain hemisphere. For this reason, importance is given to prenatal stimulation programs for pregnant women. OBJECTIVES: To determine the perinatal results in the moment of childbirth in mothers who had participated in prenatal stimulation programs. MATERIAL: An experimental study was conducted in five health districts in the town of Cienfuegos (Cuba) with a view to identifying the perinatal results at the moment of childbirth in women that had participated in prenatal stimulation programs. METHODOLOGY: The study consisted of an intentional sampling of all of the subjects (n = 200 women who were 20-28 weeks pregnant). The variables studied were the following: duration of labor, baby's birth weight, Apgar score at birth, type of childbirth, and opinion of the subjects about the prenatal stimulation program. RESULTS: Of the population sample, 36% of the subjects gave birth in less than six hours; 67.5% had babies weighing 2,500-3,000 grams; and 96.5% had babies whose Apgar scores were between 8 and 9. Finally, 68.5% of the subjects had natural childbirths and 96% were satisfied with the prenatal stimulation program. CONCLUSIONS: The results obtained showed that these new prenatal stimulation programs were well received by the subjects in this study.


Subject(s)
Prenatal Care/methods , Acoustic Stimulation , Adult , Affect , Apgar Score , Birth Weight/physiology , Cuba , Female , Humans , Infant , Infant, Newborn , Patient Satisfaction , Photic Stimulation , Physical Stimulation , Pregnancy , Pregnancy Outcome
14.
J Phys Condens Matter ; 22(17): 175701, 2010 May 05.
Article in English | MEDLINE | ID: mdl-21393674

ABSTRACT

Scanning tunnelling spectroscopy (STS) and microscopy (STM) were performed on the paramagnetic molecular superconductor ß''-ET(4)[(H(3)O)Fe(C(2)O(4))(3)]·C(6)H(5)Br. Under ambient pressure, this compound is located near the boundary separating superconducting and insulating phases of the phase diagram. In spite of a strongly reduced critical temperature T(c) (T(c) = 4.0 K at the onset, zero resistance at T(c) = 0.5 K), the low temperature STS spectra taken in the superconducting regions show strong similarities with the higher T(c) ET κ-derivatives series. We exploited different models for the density of states (DOS), with conventional and unconventional order parameters to take into account the role played by possible magnetic and non-magnetic disorder in the superconducting order parameter. The values of the superconducting order parameter obtained by the fitting procedure are close to the ones obtained on more metallic and higher T(c) organic crystals and far above the BCS values, suggesting an intrinsic role of disorder in the superconductivity of organic superconductors and a further confirmation of the non-conventional superconductivity in such compounds.

15.
Inorg Chem ; 43(6): 2049-56, 2004 Mar 22.
Article in English | MEDLINE | ID: mdl-15018528

ABSTRACT

We report the synthesis, structure, and physical properties of (BEDT-TTF)[Ni(tdas)2] [BEDT-TTF, or ET, is bis(ethylenedithio)tetrathiafulvalene; tdas is 1,2,5-thiadiazole-3,4-dithiolate], which is the first example of a salt containing monomeric [Ni(tdas)2]- monoanions. This salt, which crystallizes in the monoclinic space group P2(1)/c with a = 17.2324(6) A, b = 13.2740(5) A, c = 10.9467(4) A, beta = 96.974(2) degrees, and V = 2485.5(2) A(3), forms a layered structure. One layer contains dimerized BEDT-TTF electron donor molecules and isolated [Ni(tdas)2]- monoanions, while the second layer contains chains of [Ni(tdas)2]- monoanions. Conductivity measurements show that (BEDT-TTF)[Ni(tdas)2] has a semiconductor-to-semiconductor transition near 200 K, while magnetic measurements indicate that it is an S = 1/2 paramagnet with weak antiferromagnetic coupling. Reflectance spectra reveal bands in the near-infrared region (6.6 x 10(3) and 10.6 x 10(3) cm(-1)) which are typical of (BEDT-TTF)2(2+) dimers. From these data, we can conclude that the unpaired electron lies on the [Ni(tdas)2]- anions. Tight-binding band structure calculations were used to analyze the electronic structure of this salt.

16.
Phys Rev Lett ; 90(14): 146401, 2003 Apr 11.
Article in English | MEDLINE | ID: mdl-12731933

ABSTRACT

We report on the very peculiar magnetic properties of an ensemble of very weakly coupled lithium-doped MoS2 nanotubes. The magnetic susceptibility chi of the system is nearly 3 orders of magnitude greater than in typical Pauli metals, yet there is no evidence for any instability which would alleviate this highly frustrated state. Instead, the material exhibits peculiar paramagnetic stability down to very low temperatures, with no evidence of a quantum critical point as T-->0 in spite of clear evidence for strongly correlated electron behavior. The exceptionally weak intertube interactions appear to lead to a realization of a near-ideal one-dimensional state in which fluctuations prevent the system from reordering magnetically or structurally.

18.
Inorg Chem ; 40(20): 5127-32, 2001 Sep 24.
Article in English | MEDLINE | ID: mdl-11559070

ABSTRACT

Electrochemical combination of the magnetic dinuclear anion [MM'(C2O4)(NCS)8](4-) (MM' = Cr(III)Cr(III), Cr(III)Fe(III)) with the ET organic pi-donor (ET = BEDT-TTF = bis(ethylenedithio)tetrathiafulvalene) gives rise to two new isostructural molecular hybrid salts ET5[MM'(C2O4)(NCS)8], with MM' = CrCr (1), CrFe (2). The molecular structure of compound 1 has been determined by single crystal X-ray diffraction. The particular arrangement of the organic units consists of an unprecedented two-dimensional organic sublattice nearly similar to that observed in kappa-phase structures. For both compounds, the magnetic susceptibility measurements indicate (i) the ET radicals do not contribute to the magnetic moment probably due to the presence of strong antiferromagnetic interaction between them, and (ii) in the anion, the magnetic coupling is antiferromagnetic for 1 (J = -3.65 cm(-1)) and ferromagnetic for 2 (J = 1.14 cm(-1), J being the parameter of the exchange Hamiltonian H = -2JS1S2). The field dependence of the magnetization of compound 2 at 2.0 K gives further evidence of the S = 4 ground-state arising from the interaction between S = 3/2 Cr(III) and S = 5/2 Fe(III). EPR measurements confirm the nature of the magnetic interactions and the absence of any contribution from the organic part, as observed from the static magnetic measurement. Conductivity measurements and electronic band structure calculations show that both salts are semiconductors with low activation energies.

19.
Inorg Chem ; 40(14): 3526-33, 2001 Jul 02.
Article in English | MEDLINE | ID: mdl-11421701

ABSTRACT

The synthesis, structure, and physical characterization of two new radical salts formed with the organic donor bis(ethylenethia)tetrathiafulvalene (BET-TTF) and the octahedral anions hexacyanoferrate(III), [Fe(CN)(6)](3-), and nitroprusside, [Fe(CN)(5)NO](2-), are reported. These salts are (BET-TTF)(4)(NEt(4))(2)[Fe(CN)(6)] (1) (monoclinic space group C2/c with a = 38.867(7) A, b = 8.438(8) A, c = 11.239(6) A, beta = 90.994(9) degrees, V = 3685(4) A(3), Z = 4) and (BET-TTF)(2)[Fe(CN)(5)NO].CH(2)Cl(2) (2) (monoclinic space group C2/c with a = 16.237(6) A, b = 18.097(8) A, c = 12.663(7) A, beta = 106.016(9) degrees, V = 3576(3) A(3), Z = 4). In salt 1 the organic BET-TTF molecules are packed in orthogonal dimers, forming the first kappa phase observed for this donor. The analysis of the bond distances and the electronic and IR spectra suggests a degree of ionicity of 1/4 per BET-TTF molecule, in agreement with the stoichiometry of the salt. The electrical properties show that 1 is a semiconductor with a high room-temperature conductivity (11.6 S cm(-1)) and a low activation energy (45 meV), in agreement with the band structure calculations. The magnetic susceptibility of 1 shows, besides the paramagnetic contribution from the anion, a temperature-independent paramagnetism (TIP) of the Pauli type due to the electronic delocalization observed at high temperatures in the organic sublattice. This Pauli type paramagnetism is confirmed by the ESR spectra that also show a Dysonian line when the magnetic field is parallel to the conducting plane, typical of metallic and highly conducting systems. Salt 2 presents an unprecedented packing of the organic molecules that form zigzag tunnels where the anions and the solvent molecules are located. The stoichiometry indicates that all the BET-TTF molecules bear a charge of +1, and accordingly, 2 behaves as a semiconductor with a very low room-temperature conductivity. The magnetic properties of this salt indicate that the unpaired electrons on the organic molecules are strongly antiferromagnetically coupled, giving rise to a diamagnetic behavior of 2, as the nitroprusside anion is also diamagnetic.

20.
Rev. esp. pediatr. (Ed. impr.) ; 57(2): 185-190, mar. 2001.
Article in Es | IBECS | ID: ibc-464

ABSTRACT

Objetivos: valorar la utilidad de dos modelos de termómetro timpánico para el diagnóstico de la fiebre en la infancia. Diseño: estudio prospectivo transversal. Material y Métodos: se estudiaron 1.406 niños hospitalizados a los que se realizaron 3 determinaciones de temperatura: la primera axilar con termómetro de mercurio (TAXI), la segunda con termómetro timpánico Termo Scan Pro1 (TOTIC) y la tercera con termómetro timpánico Termo Scan Pro 3000 (TOTIC2). Se estudiaron la sensibilidad (SE), especificidad (Es), Valor Predictivo Positivo (VPP) y Valor Predictivo Negativo (VPN) y estudio de curvas ROC para TOTIC y TOTIC2 y valores de TAXI > 37° C, 37,2° C y 37,9° C. Resultados: 234 niños (16,64 por ciento) presentaron TAXI > 37° C, 190 niños (13,51 por ciento) TAXI > 37,2° C y 108 niños (7,68 por ciento) TAXI > 37,9° C. La Se fue > 85 por ciento, la Es > 91 por ciento, el VPP > 83 por ciento y el VPN > 95 por ciento, para TOTIC y TOTIC2, y los 3 valores de TAXI. Los mejores valores se encontraron para TOTIC2 y TAXI > 37,9° C (Se 100 por ciento, Es 95 por ciento, VPP 89,81 por ciento y VPN 98,37 por ciento). El área bajo la curva en el estudio de las curvas ROC fue > 0,953 con un máximo de 0,993 para TOTIC2 y TAXI > 37,9° C. Aunque las áreas bajo la curva fueron superiores para TOTIC2 respecto a TOTIC, las diferencias no fueron estadísticamente significativas. Conclusiones: de nuestro estudio parece deducirse que la termometría timpánica es un método cómodo, rápido y eficaz para la detección de la fiebre en la infancia, pero hay que tener en cuenta que se precisa el establecimiento de valores normales de acuerdo con el modelo de termómetro empleado (AU)


Subject(s)
Child , Humans , Thermometers , Fever/diagnosis , Prospective Studies , Cross-Sectional Studies
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