Physical properties of new ordered bimetallic phases M0.25Cd0.75PS3 (M = ZnII, NiII, CoII, MnII).

Four bimetallic phases of the thiophosphate family have been synthesized by the cationic exchange reaction using a freshly prepared K0.5Cd0.75PS3 precursor phase and methanolic solutions of nitrates of the divalent cations ZnII, NiII, CoII, and MnII. All the materials were characterized by FTIR, PXRD, SEM-EDXS and (in the case of the diamagnetic compounds) by solid state NMR. For the K0.5Cd0.75PS3 precursor, the X-ray powder diffraction data suggest a modification of the structure, while solid state NMR results confirm that this phase possesses an ordered arrangement of Cd vacancies. The cationic exchange reaction achieves a complete removal of potassium ions (no potassium detected by SEM-EDXS) and re-occupation of the vacancies by divalent cations. Therefore, the obtained compounds have an average composition of M0.25Cd0.75PS3 (M = ZnII, NiII, CoII, MnII) and possess an ordered distribution of the substituent cations. Even with the paramagnetic substitution level of 25%, antiferromagnetic behaviour is present in the phases with MnII, CoII and NiII, as evidenced by dc susceptibility and in the case of the MnII substituted phase by EPR. The cooperative magnetic interactions confirm the conclusion that the paramagnetic ions adopt an ordered arrangement. The analysis by broad band impedance spectroscopy allows to attribute the conductivity in these materials to charge movements in the layers due to the difference in electronegativity of the metal ions. Zn0.25Cd0.75PS3 is the phase that shows the highest conductivity values. Finally, the band gap energies of the bimetallic phases tend to be lower than those of the single-metal phases, probably due to an overlap of the band structures.

Ab initio molecular dynamics study of small alkali metal clusters.

In this work, the dynamics of the clusters of the type M3 with M a metal alkaline atom from Li to Cs have been studied. Other heteroatomic mixed clusters like LiNaK and one bigger cluster, Na7, have also been studied. It was found that the dynamics present interesting phenomena like pseudorotations and crossovers which could explain the differences between experimental and theoretical values of some electrical properties, like the electric dipole moment of alkali metal clusters.

On the principle of spin potential equalization.

In analogy with Sanderson's electronegativity equalization principle, it is possible to postulate a principle of spin potential equalization in the E[N(alpha), N(beta)] representation of the spin polarized density functional theory, where N(alpha) and N(beta) refer to the number of electrons with spins alpha and beta, respectively. The principle provides simple expressions to evaluate the energy changes DeltaE between two interacting molecules, A and B, together with the electron transfer, DeltaN(alpha) and DeltaN(beta). The model is illustrated for a series of addition reactions of electrophilic, nucleophilic, and ambiphilic carbenes to alkenes in their singlet and triplet multiplicities. The results are in a consistent qualitative agreement with the experimental reactivity established for these systems.

Theoretical ro-vibrational spectrum of CF(+).

We determined the energies for ro-vibrational transitions of fluoromethylidynium (CF(+)) using a numerical variational approach and a Potential Energy Function calculated with the internally contracted multireference configuration interaction method including also the Davidson correction (MRCI+Q). For this purpose, all the CSFs built the full valence space have been selected as multireferential space and all the valence electrons have been correlated for the ground state X(1) summation operator(+) of CF(+). The rotational transitions observed experimentally toward the Orion Bar have been calculated to be 101.2 (102.6)GHz, 202.9 (205.2) GHz and 304.0 (307.7)GHz (experimental values in parentheses) respectively for the J=1-->0, J=2-->1 and J=3-->2 transitions. From the manifold of transitions data, it is shown how to calculate the spectroscopic parameters as well as the coefficients for the Dunham expansion.

Heterometallic CuII/LnIII polymers active in the catalytic aerobic oxidation of cycloalkenes under solvent-free conditions.

Heterometallic 3d-4f inorganic polymers were prepared using 3,5 pyridinedicarboxylic acid (H2PDC), {[CuLn2(PDC)2(SO4)2(H2O)6]·H2O}n (Ln: SmIII, CuSmPDC, EuIII, CuEuPDC, GdIII, and CuGdPDC). These catalysts are active in the aerobic oxidation of cycloalkenes under solvent-free conditions, with a conversion for the oxidation of cyclohexene of 71% after one hour of the reaction, and a TOF value of 1438 h-1 for CuSmPDC. On the other hand, the oxidation of cycloheptene and cyclooctene exhibited slightly lower conversions of 52% and 47%, and TOF values of 1053 and 159 h-1 after 1 and 6 hours of the reaction, respectively. The radical mechanism for the oxidation reaction of cyclohexene was assessed by Raman and EPR spectroscopy. The first evidenced the formation of Cu-O2 adducts and the second permitted is to observe the presence of the oxygen centered radical species, which act as initiators of the reaction chain to generate the products. An increase in the temperature of the reaction correlates with the adduct formation, and with the enhancement of the oxidation reaction.

Magnetic behaviour of bimetallic layered phases M'0.2Mn0.8PS3·0.25 H2O (M' = ZnII, CuII, NiII, CoII).

In this work the magnetic properties of bimetallic phases M'0.2Mn0.8PS3·0.25H2O (M' = CoII, NiII, CuII or ZnII) have been explored and compared with those of the pristine phase MnPS3. Magnetic susceptibility, high field magnetization and electron paramagnetic resonance (EPR) studies reveal that the transition temperature between the antiferromagnetic and paramagnetic order for the pristine phase is shifted to lower values in the bimetallic phases. From magnetization measurements the critical field of the spin-flop transition is found to be dependent on the nature of the added secondary transition metal ion. EPR spectra of all compounds in the temperature range of 8-300 K present a single resonance line shape. Temperature dependence of the EPR parameters, like line width, g values and double integrated area (IDIN), are obtained from the spectra and present a scenario compatible with the magnetization results. The temperature dependence of the first derivative of the product (IDINT) shows two maxima for all samples, with exception of the CoII phase, indicating two critical temperatures, while these critical temperatures could not be clearly determined by dc susceptibility.

DNA ploidy pattern and tumor suppressor gene p53 expression in gallbladder carcinoma.

The relationship between p53 gene expression and DNA content in advanced gallbladder carcinoma was studied. Fifty-three cases of advanced gallbladder carcinoma (45 primary tumors and 8 metastases) were analyzed, p53 protein expression was determined by immunohistochemistry, DNA content was measured by cytophotometric techniques. Study subjects included 45 (85%) female and 8 male patients, with an overall mean age of 58.6 years. Positive staining for p53 protein was observed in 27 (51%) cases. In subserosal tumors, the expression was significantly less than that in tumors that reached the serosa (P = 0.01). Twenty-nine (55%) cases were diploid and 24 were aneuploid. Sixty-seven % of primary tumors were diploid, whereas 87% of metastases showed an aneuploid DNA content. Both diploid and aneuploid tumors were positive for the p53 protein in the same proportion, and p53 was also expressed equally in both primary and secondary tumors. In advanced gallbladder carcinoma, the expression of the p53 gene was earlier than the accumulation of abnormal quantities of chromosomal DNA in the tumor cells. The determination of these events as markers in preneoplastic lesions is warranted in gallbladder carcinogenesis.

Anatomical substrate for separate processing of ascending and descending visceral information in the nucleus of the solitary tract of the rat.

We examined the possible existence of divergent visceral pathways arising from the nucleus of the solitary tract, by co-injecting axonal tracers into the parabrachial nucleus and into the ventrolateral medulla. We found that around 5% of NTS neurons projected to both sites, and that neurons projecting to VLM were larger. This parallel organization allows a differential control of the ascending versus descending visceral pathways at an early stage of processing.

Resinas infiltrantes: Un tratamiento eficaz y mínimamente invasivo para el tratamiento de lesiones blancas no cavitadas. Revisión narrativa / Resin infiltration: An effective and minimally invasive treatment for the treatment of non-cavitated white lesions. Narrative review

Introducción: La caries es un proceso en el que la ganancia de minerales del tejido dentario es menor que la pérdida de ellos, lo que conlleva a la formación inicial de una lesión opaca y blanca, que en un comienzo será no cavitada y si el proceso continua se cavitará. Existen variados tratamientos para tratar estas lesiones blancas no cavitadas entre los que existen las resinas infiltrantes. Con nombre comercial ICON este tratamiento está indicado para lesiones D1 o R3 según criterio de detección radiográfico (radiolucidez hasta el tercio externo de la dentina) y lesiones de mancha blanca en superficies libres vestibulares. Existe variada evidencia científica que respalda su uso, tanto en tratamiento interproximal como para tratamiento de superficies libres. Conclusiones: El uso de la terapia con resinas infiltrantes tanto para detención de lesiones incipientes interproximales como para tratamiento de lesiones libres vestibulares (post tratamiento de ortodoncia) está respaldada por la evidencia científica. Los estudios revelaron que el uso de RI para detener la progresión de lesiones de caries no cavitadas es alentador. Esto sugiere que RI es una prometedora técnica no invasiva. La evidencia científica disponible nos muestra también que la infiltración de resina mejora significativamente la apariencia clínica de LBNC vestibulares y reduce su tamaño. Sin embargo, ensayos clínicos de alta calidad y a largo plazo, son necesarios para confirmar la eficacia de RI en la detención de lesiones no cavitadas tanto en dientes temporales como permanentes. En particular, con el fin de determinar los beneficios a largo plazo (AU)

Introduction: Caries is a process in which the mineral gain of the dental tissue is less than the loss of them, which leads to the initial formation of an opaque and white lesion, which in the beginning will not cavitate and if the process Will continue to cavitate. There are several treatments to treat these non-cavitated white lesions among which there are infiltrating resins. ICON trade name is indicated for D1 or R3 lesions according to radiographic detection criteria (radiolucency up to the external third of the dentin) and white spot lesions on free vestibular surfaces. There is a variety of scientific evidence that supports its use, both in interproximal treatment and in the treatment of free surfaces. Conclusions: The use of infiltrating resin therapy for the management of interproximal incipient lesions as well as treatment of free vestibular lesions (post orthodontic treatment) is supported by scientific evidence. Studies have shown that the use of RI to stop the progression of non cavitated carious lesions is encouraging. This suggests that IR is a promising non invasive technique. Available scientific evidence also shows that resin infiltration significantly improves the clinical appearance of vestibular LBNCs and reduces their size. However, high-quality, long-term clinical trials are needed to confirm the efficacy of IR in arresting non-cavitated lesions in both temporal and permanent teeth. In particular, in order to determine the long-term benefits (AU)

Osteoporosis: Parte I - Generalidades / Osteoporosis: Part I - Basic concepts

This review corresponds to a general analysis of osteoporosis, with emphasis in calcium metabolism, the role of Vitamin D, as well as osteoporosis physiopathology, diagnosis and treatment. The second part (Osteoporosis. Part II) will describe the importance of osteoporosis in several digestive diseases (liver and gastrointestinal tract).

En esta revisión abordamos el tema osteoporosis en forma general, desarrollando principalmente el metabolismo del calcio, el rol de la vitamina D; así como la fisiopatología, el diagnóstico y tratamiento de la osteoporosis. En la segunda parte (Osteoporosis. Parte II ) se describirá la importancia de la osteoporosis en diversas enfermedades digestivas (hepáticas y del tubo digestivo).

Osteoporosis: parte II: en enfermedades hepáticas y del tubo digestivo / Osteoporosis: part II: in liver and digestive tract diseases

The present review addresses liver and gastrointestinal diseases that are more frequently associated to osteopenia and osteoporosis. For each disease, we describe the prevalence and physiopathology of these bone metabolism conditions. The purpose is to create awareness of this scenario and prompt early analysis if these patients, and in other cases, to provide prophylaxis and treatment of these disorders.

En esta revisión se abordan las enfermedades hepáticas y del tubo digestivo que con mayor frecuencia se asocian a osteopenia y osteoporosis. En cada patología describimos la prevalencia y fisiopatología de estas afecciones del metabolismo óseo. El objetivo es dar a conocer esta realidad e inducir a que estos pacientes sean estudiados precozmente, en otros casos aplicar la profilaxis y tratar estos desórdenes.

Síndrome antifosfolípido catastrófico: caso clínico / Catastrophic antiphospholipid syndrome: clinical case

El síndrome antifosfolípido (SAF) fue descrito y caracterizado durante la segunda mi-tad del siglo XX inicialmente como un fenómeno protrombótico secundario en con-texto de otras enfermedades del tejido conectivo, principalmente lupus. Sin embargo, el estudio de pacientes con enfermedad primaria impulsó a distintos consensos, tan-to clínicos como de laboratorio para su correcta identificación. Entre los pacientes con SAF destaca la forma de presentación catastrófica, de baja prevalencia, pero impor-tante por su mal pronóstico, caracterizada por el compromiso de múltiples sistemas en corto tiempo. Presentamos el caso de una paciente del Hospital Clínico San Borja-Arriarán con diag-nóstico de SAF primario, que presentó en su evolución la forma catastrófica. Este caso sirve de base para una revisión del proceso diagnóstico del SAF en relación a otras patologías reumatológicas y las características propias del SAF catastrófico.

Antiphospholipid syndrome (APS) was described and characterized during the second half of the 20th century initially as a secondary prothrombotic phenome-non in the context of other connective tissue diseases, mainly lupus. However, the study of patients with primary disease prompted different consensus, both clin-ical and laboratory for their correct identification. Among patients with APS, the catastrophic presentation is of low prevalence, but important because of its poor prognosis, characterized by the commitment of multiple systems in a short time. We present the case of a patient from the San Borja-Arriaran Clinic Hospital with di-agnosis of primary APS, which presented the catastrophic form in its evolution. This case serves as a basis for a review of the diagnostic process of APS in relation to other rheumatologic pathologies and the characteristics of catastrophic APS.

Estudio de una masa abdominal en pediatría: revisión de la literatura / Study of an abdominal mass in pediatrics: review of the literature

Alrededor del 20 por ciento de los tumores diagnosticados en pediatría corresponden a masas intraabdominales y de ellos, el 20 por ciento son tumores malignos, por lo que un alto índice de sospecha asociado a un diagnóstico precoz pueden incidir positivamente en el pronóstico de los pacientes. El objetivo de este trabajo fue realizar una revisión actualizada de la literatura disponible sobre el estudio de una masa abdominal en pediatría, enfocado principalmente en la epidemiología y orientación diagnóstica que debería seguir el médico al enfrentarse a un paciente con este hallazgo. La forma de presentación clínica de una masa abdominal es variable. En un número importante de pacientes será de forma asintomática, lo que dificulta el diagnóstico precoz, por lo que es necesario mantener un alto índice de sospecha frente esta patología. Como herramientas para la evaluación de una masa abdominal contamos cada vez más con exámenes radiológicos, marcadores tumorales e histología, sin embargo, los exámenes deben realizarse orientados a comprobar la sospecha diagnóstica que obtengamos de una completa anamnesis y examen físico.

About 20 percent of the tumors diagnosed in pediatric patients correspond to intraabdominal masses. These can correspond to both benign and malignant pathology. Moreover, 20 percent of solid malignant tumors are located in the abdomen, so a high index of suspicion associated with an early diagnosis can positively affect the prognosis of these patients. The clinical presentation of an abdominal mass is variable. A significant number of patients will be asymptomatic, which makes early diagnosis difficult. This is why it is necessary to maintain a high index of suspicion in this pathology. As tools for the evaluation of an abdominal mass, we are increasingly counting on radiological examinations, tumor markers and histology. However, the examinations must be carried out in order to verify the diagnostic suspicion that we obtain from a complete anamnesis and physical examination. The objective of this work was to perform an updated review of the available literature on the study of abdominal mass in pediatrics, focused mainly on the epidemiology and diagnostic orientation that should be followed by the physician when confronting a patient with this finding.

On the Gas-Phase Electronic Chemical Potential of Anions.

In the process of evaluating intrinsic electronic chemical potentials and related properties of anions in the gas phase, positive values for this quantity often arise. We herein examine in detail this result in terms of computational grounds. At a low level of theory, this result is often obtained, but its origin is mainly traced to the fact that the LUMO energy level is not really converged. Therefore, this outcome may be an artifact of the calculation. We establish the minimum basis set analysis that is to be performed before the electronic chemical potential of charged electron donors, in the absence of medium (solvent) effects, may be safely calculated to yield physically meaningful results. The implications that this result may have on the phenomenological chemical reactivity theory are discussed in detail, mainly those related to the definition of the electron-donating (nucleophilicity) ability of anions in the gas phase. The arguments given are illustrated for a large number of atomic and molecular systems at different levels of theory.

Fracturas vertebrales: ¿Son inocuas? / Vertebral fractures: are harmless?

La masa ósea disminuye y el riesgo de fracturas aumenta con la edad, especialmente en la posmenopausia. Las fracturas vertebrales son las fracturas osteoporóticas más frecuentes, y se asocian a deformidad de columna, reducción de estatura, dolor de espalda, dificultad respiratoria, morbilidad y mortalidad aumentadas; y pueden predecir futuras fracturas vertebrales y de cadera.

Bone mass declines and the risk of fractures increases as people age, specially in postmenopausal women. Vertebral fractures are the most frequent osteoporotic fractures and associated to spine deformity, height loss, back pain, impaired breathing, increased morbidity and mortality; and predict future spine and hip fractures.

Comparison among four different ways to condense the Fukui function.

Four different ways to condense the Fukui function are compared. Three of them perform a numerical integration over different basins to define the condensed Fukui function, and the other one is the most traditional Fukui function using Mulliken population analysis. The basins are chosen to be the basins of the electron density (AIM), the basins of the electron localization function (ELF), and the basins of the Fukui function itself. The use of the last two basins is new and presented for the first time here. It is found that the last three methods yield results which are stable against a change in the basis set. The condensed Fukui function using the basins of the ELF is not able to give information on the reactivity of an acceptor molecule. In general, the condensed Fukui function using the basins of the density or the basins of the Fukui function describe the reactivity trends well. The latter is preferred, because it only contains information about the Fukui function itself and it gives the right information for donor as well as acceptor centers.

Pseudopotential and electron propagator methods for the calculation of the photoelectron spectra of anionic silicon clusters: predictions on Si10-.

Photoelectron spectra of anionic clusters of silicon require reliable theoretical calculations for their assignment and interpretation. Electron propagator calculations in the outer valence Green's-function approximation with two well-characterized, all-electron basis sets on vertical electron detachment energies (VEDEs) of anions are compared to similar calculations that employ Stuttgart pseudopotentials. Tests on Si(n) (-) clusters with n=3-7 exhibit an encouraging agreement between the all-electron and pseudopotentials results and between electron propagator predictions and experiments and values obtained from coupled-cluster calculations. To illustrate the capabilities of the new approach based on a Si pseudopotential and electron propagator methods, VEDE calculations on Si(10) (-) are presented.

Electron probability distribution in AIM and ELF basins.

The probabilities of finding a certain number of electrons enclosed in a given volume is calculated and discussed for a series of molecules. Two different methodologies to do the partition of the molecular space in separate volumes are investigated: the Atoms in the Molecules, AIM, topologic analysis of the density, and the topologic analysis of the Electron Localization Function (ELF). The formulas to calculate the probability distribution are reviewed and the way to implement them shortly explained. For a series of molecules, we present how the probability distribution complement the chemical information about the localization of the electrons in certain regions of the space. The calculations show that the probability of finding Z electrons in the AIM atomic basin associated to an atom of atomic number Z is, in general, low, even when the average number of electrons is close to Z. The probability distribution on the ELF basins associated to bonds yields new insight about the nature of the respective bond.

Selective amplification of neocortical neuronal output by fast prepotentials in vivo.

Neocortical cells integrate inputs from thousands of presynaptic neurons distributed along their dendritic arbors. Propagation of postsynaptic potentials to the soma is crucial in determining neuronal output. Using intracellular recordings in anesthetized and non-anesthetized, naturally awake and sleeping cats, we found evidence for generation of fast, all-or-none events recorded at the soma in about 20% of regular-spiking and intrinsically-bursting neurons. These events, termed fast prepotentials (FPPs), were suppressed by hyperpolarizing the neurons or by inhibiting synaptic transmission with perfusion of Ca2+-free artificial cerebrospinal fluid. FPPs could be evoked by activation of specific cortical inputs and allowed neurons to fire at more hyperpolarized levels of membrane potentials. Thus, FPPs represent a powerful mechanism to boost the output of neocortical neurons in response to given inputs. We further found evidence for modulation of FPPs generation across the waking-sleep cycle, indicating important changes in the integrative properties of neocortical neurons in different states of vigilance. We suggest that FPPs represent attenuated spikes generated in hot spots of the dendritic arbor and constitute a powerful mechanism to reinforce the functional connections between specific elements of the cortical networks.

[Determination of DNA content in salivary gland tumors]. / Determinación del contenido de ADN en tumores de glándulas salivales.

BACKGROUND: DNA content determination is a useful tool in the characterization of different malignant tumors. AIM: To measure DNA content in cells of salivary gland tumors as adjunct to histological diagnosis, correlating morphologic and biological features of these tumors. MATERIAL AND METHODS: From the archives of the Pathology service of a general hospital, 21 salivary gland tumors, 15 pleomorphic adenomas, 3 mucoepidermoid carcinomas and 3 cystic adenoid carcinomas were selected. DNA content was determined in the histological samples using a flow cytometric DNA analysis. RESULTS: All pleomorphic adenomas had a normal or diploid DNA content. Fifty percent of malignant tumors had an aneuploid DNA content (1 mucoepidermoid carcinoma and 2 cystic adenoid carcinomas). CONCLUSIONS: DNA determination may help in the histological diagnosis of salivary gland tumors. The presence of aneuploidy suggests malignity.