Crystal growth and magnetic characterization of HoIr2Si2 (I4/mmm).

Single crystals of HoIr2Si2 with the body-centered ThCr2Si2-type structure (I4/mmm) were grown by Bridgman method from indium flux. Single crystal structure determination yielded a Si-z position of 0.378(1) in the structure. We excluded the presence of the high temperature phase with the primitive CaBe2Ge2-type structure (P4/nmm) by powder x-ray diffraction. Magnetic measurements on the single crystals yield a Néel temperature of [Formula: see text] K. In the inverse magnetic susceptibility a strong anisotropy with Weiss temperatures [Formula: see text] K and [Formula: see text] K occurs above T N. The effective magnetic moment [Formula: see text] and [Formula: see text] is close to the expected value for a free Ho3+ ion, [Formula: see text]. The field dependent magnetization shows a step-like behaviour due to crystalline electric field effects. The temperature and field dependence of the magnetization hint to the ordering of the magnetic moments along the c direction below T N.

Reaction of the thermo-labile triazenide Na[tBu3SiNNNSiMe3] with CO2: formation of the imido carbonate (tBu3SiO)(Me3SiO)C[double bond, length as m-dash]N-SitBu3 and carbamine acid (tBu3SiO)CONH2.

The thermo-labile triazenide Na[tBu3SiNNNSiMe3] was prepared by the reaction of Me3SiN3 with Na(thf)2[SitBu3] in pentane at -78 °C. Treatment of Na[tBu3SiNNNSiMe3] with an excess of carbon dioxide in pentane at -78 °C yielded the imido carbonate (tBu3SiO)(Me3SiO)C[double bond, length as m-dash]N-SitBu3 and the carbamine acid (tBu3SiO)CONH2 along with other products. From the reaction solution we could isolate the imido carbonate (tBu3SiO)(Me3SiO)C[double bond, length as m-dash]N-SitBu3 and carbamine acid (tBu3SiO)CONH2. At first single crystals of the carbamine acid (tBu3SiO)CONH2 (triclinic, space group P1[combining macron]) were grown from this solution at room temperature. A second crop of crystals were obtained by concentrating the solution. The second charge consisted of the imido carbonate (tBu3SiO)(Me3SiO)C[double bond, length as m-dash]N-SitBu3 (monoclinic, space group P21/n).

Microscopic origin of the charge transfer in single crystals based on thiophene derivatives: A combined NEXAFS and density functional theory approach.

We have investigated the charge transfer mechanism in single crystals of DTBDT-TCNQ and DTBDT-F4TCNQ (where DTBDT is dithieno[2,3-d;2',3'-d'] benzo[1,2-b;4,5-b']dithiophene) using a combination of near-edge X-ray absorption spectroscopy (NEXAFS) and density functional theory calculations (DFT) including final state effects beyond the sudden state approximation. In particular, we find that a description that considers the partial screening of the electron-hole Coulomb correlation on a static level as well as the rearrangement of electronic density shows excellent agreement with experiment and allows to uncover the details of the charge transfer mechanism in DTBDT-TCNQ and DTBDT-F4 TCNQ, as well as a reinterpretation of previous NEXAFS data on pure TCNQ. Finally, we further show that almost the same quality of agreement between theoretical results and experiment is obtained by the much faster Z+1/2 approximation, where the core hole effects are simulated by replacing N or F with atomic number Z with the neighboring atom with atomic number Z+1/2.

PTF 11kx: a type Ia supernova with a symbiotic nova progenitor.

There is a consensus that type Ia supernovae (SNe Ia) arise from the thermonuclear explosion of white dwarf stars that accrete matter from a binary companion. However, direct observation of SN Ia progenitors is lacking, and the precise nature of the binary companion remains uncertain. A temporal series of high-resolution optical spectra of the SN Ia PTF 11kx reveals a complex circumstellar environment that provides an unprecedentedly detailed view of the progenitor system. Multiple shells of circumstellar material are detected, and the SN ejecta are seen to interact with circumstellar material starting 59 days after the explosion. These features are best described by a symbiotic nova progenitor, similar to RS Ophiuchi.

Reacciones medicamentosas severas en piel / Severe skin drug reactions

Las drogas son sustancias químicas que pueden interferir con el sistema inmune y a veces conducen a reacciones inusuales y severas. Éstas pueden amenazar la vida, requerir hospitalizaciones prolongadas o dejar secuelas significativas. Cerca del 2 por ciento de las reacciones cutáneas inducidas por fármacos se consideran graves. Estas son el angioedema, el shock anafiláctico, el síndrome de Stevens-Johnson (SSJ), la necrolisis epidérmica tóxica (NET), y el síndrome de hipersensibilidad (DRESS), entre otros. Requieren atención especial ya que los síntomas clínicos son heterogéneos y pueden imitar diferentes enfermedades, lo que lleva a retardar el diagnóstico correcto.

Drugs are chemicals that can interfere with the immune system and may sometimes lead to unusual and severe reactions. These can be life threatening, requiring prolonged hospitalization or have significant sequelae. About 2 per cent of drug-induced skin reactions are considered serious. They are angioedema, anaphylactic shock, the Steven-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), and hypersensitivity syndrome (DRESS), among others. They require special attention because clinical symptoms are heterogeneous and can mimic different diseases, leading to a delay in the correct diagnosis.

Electrochemical and crystal structural analysis of alpha- and dehydro-alpha-lapachones.

Lapachones are pharmaceutically active compounds generating reactive oxygen species. The crystal structure and redox behaviour of the title lapachones, derivates of quinones, were determined by X-ray diffraction and cyclovoltametric measurements. The observed results were compared with beta-lapachone.

Lisencefalia y epilepsia en pediatría / Lissencephaly and epilepsy in paediatrics

Background: Lissencephaly is a brain malformation caused by defective neuronal migration and characterized by epilepsy and severe psychomotor retardation, with high mortality. Objective: Describe the clinical presentation, neuroradiologic characteristics and evolution of 9 children with lissencephaly. Results: 9 children (4 males) were controlled between 1999 and 2007. The diagnosis was made during the neonatal period in 4 patients; 3 cases presented seizures and microcephaly, while 1 newborn had a prenatal ultrasonography showing cerebral malformation. The diagnosis was made during the first year of life in 5 patients; 4 cases had epilepsy, severe psychomotor retardation and microcephaly, while 1 child had macrocephaly. During follow-up period, 8/9 children had catastrophic epilepsy and severe psychomotor retardation. Conclusions: Lissencephaly is a pathology with bad prognosis, usually diagnosed during the first year of life. Symptoms include refractory epilepsy and severe psychomotor delay. It is important to complete the evaluation with genetic studies and high - resolution neuroimaging, in order to perform an early diagnosis, predict evolution and offer genetic counsil.

Introducción: Lisencefalias son malformaciones cerebrales causadas por una alteración de la migración neuronal, que se manifiestan como síndromes epilépticos y trastornos motores graves con alta mortalidad. Objetivo: Describir la presentación clínica, características neuroradiológicas y seguimiento de 9 niños con lisencefalia. Pacientes y Método: Se incluyeron 9 pacientes (4 varones) controlados durante los años 1999-2007. Resultados: Se diagnosticaron 4 pacientes en período neonatal, 3 de los cuales presentaron convulsiones y microcefalia, y 1 presentó ecografia prenatal con alteración cerebral. En el período de lactante se diagnosticaron 5 pacientes, 4 durante el estudio de epilepsia y retraso grave del desarrollo psicomotor asociada a microcefalia y 1 paciente durante el estudio de macrocefalia. En el seguimiento 8/9 evolucionaron con síndromes epilépticos catastróficos y retraso grave del desarrollo psicomotor. Conclusión: Las lisencefalias son patologías de mal pronóstico, que se manifiestan en el primer año de vida. En la mayoría de los pacientes causa epilepsia refractaria y retraso grave del desarrollo psicomotor. Es importante el estudio genético y con neuroimágenes de alta resolución para realizar un diagnóstico precoz, predecir evolución y ofrecer consejo genético.

Adherencia a las inmunizaciones en niños con necesidades de cuidado médico especial / Adherence to immunization among children with special health care needs

Los niños con necesidades de cuidado médico especial (NECMES) son una población creciente en pediatría y su riesgo de complicaciones asociadas a enfermedades infecciosas es alto. Objetivo. En niños con NECMES, describir la adherencia al Programa Nacional de Inmunizaciones (PNI) y al uso de vacunas adicionales recomendadas. Pacientes y Métodos. En forma retrospectiva se registró en niños con NECMES, hospitalizados: vacunas PNI administradas, retrasos y causas de éstos, prescripción y administración de vacunas adicionales. Resultados. Se analizaron 70 niños: 30 presentaron al menos un atraso en las vacunas PNI, 40,0 por ciento por hospitalizaciones previas, 26,7 por ciento por morbilidad menor y 20 por ciento por otras causas no justificadas. Se prescribió vacunas adicionales al PNI a 49 niños (70 por ciento) pero sólo 25 las recibieron. Conclusiones. Esta población presentó baja adherencia al esquema de vacunación PNI y extra PNI. Cualquier contacto con el personal de salud, incluyendo la hospitalización, debe constituir una oportunidad para actualizar las inmunizaciones.

The proportion of children with special health care needs (CSHCN) due to chronic illness is increasing. They have a high risk of complications due to infectious diseases. Objective. To describe adherence to the Expanded Program of Immunization (EPI) and administration of other expert recommended vaccines in CSHCN. Patients and methods. In a retrospective manner information on chronic disease, EPI vaccines administration, reasons for delays, prescription and administration of additionally recommended vaccines was registered in a cohort of hospitalized CSHCN. Results. Seventy children were analyzed. Thirty (42.9 percent) had at least one delay in EPI immunization schedule; 40 percent due to previous hospitalizations, 26.7 percent due to minor morbidity and 20 percent due to other unjustified reasons. Forty-nine (70.0 percent) received prescriptions for additional vaccines, but only 25 actually received them. Conclusions. CSHCN showed low adherence to EPI and received few additionally recommended vaccines. Every contact with these patients, including hospitalization should be used to update immunizations.

Síndrome de PHACES / PHACES syndrome

El hemangioma es el tumor vascular benigno más frecuente de la infancia y su asociación con otras malformaciones es rara. Se ha descrito recientemente asociado al síndrome de PHACES, que corresponde a una alteración del desarrollo en la gestación precoz. Este síndrome se caracteriza por la presencia de un gran Hemangioma facial (H) asociado a otras anomalías como: malformaciones cerebrales de la fosa Posterior (P), alteraciones de las arterias cervicocraneales y Coartación de la aorta (C), defectos oculares (E) y esternón hendido y/o rafe supraumbilical (S). Afecta de preferencia al sexo femenino y la mayoría tiene sólo una manifestación extracutánea.

The hemangioma is the most common benign vascular tumor in childhood and is rarely related to other systemic malformations. It has been recently described in association with PHACES syndrome, which is an alteration in gestational development. This syndrome presents a large facial Hemangioma (H), with other anomalies like: Posterior fossa brain malformation (P), cervicocraneal arterial anomalies and coarctation of the aorta (C), ophthalmologic disorders (E), and midline abdominal and sternal defects (S). Females are more frequently affected and there is usually only one extracutaneous manifestation.

Self-trapping of magnetic oscillation modes in Landau flux-closure structures.

We investigated the magnetodynamics in rectangular Permalloy platelets by means of time-resolved x-ray photoemission microscopy. 10 nm thick platelets of size 16 x 32 microm were excited by an oscillatory field along the short side of the sample with a fundamental frequency of 500 MHz and considerable contributions of higher harmonics. Under the influence of the oscillatory field, the Néel wall in the initial classical Landau pattern shifts away from the center, corresponding to an induced magnetic moment perpendicular to the exciting field. This phenomenon is explained by a self-trapping effect of the dominating spin-wave mode when the system is excited just below the resonance frequency. The basic driving mechanism is the maximization of entropy.

Disqueratosis congénita ligada al cromosoma X / X-linked congenital dyskeratosis

La disqueratosis congénita es una genodermatosis muy poco frecuente, existiendo aproximadamente 180 casos reportados. Objetivo: Presentar el caso de un paciente de sexo masculino en quien se sospechó el diagnóstico basado en la presentación clínica, confirmado posteriormente mediante estudio molecular. Caso clínico: Escolar de sexo masculino con antecedentes de anemia refractaria a tratamiento e infecciones bacterianas severas, que se presentó clínicamente con hiperpigmentación cutánea reticular, distrofia ungueal, leucoplaquia y falla medular. En el estudio molecular se detectó una mutación del gen DKC1 que determina una sustitución aminoacídica en la posición 353 de Alanina por Valina. Discusión: La disqueratosis congénita es un desorden genético multisistémico, muy poco frecuente. Clínicamente se caracteriza por la presencia de hiperpigmentación cutánea de tipo reticular, distrofia ungueal, leucoplaquia de la mucosa oral y pancitopenia progresiva. La mutación detectada en este caso es una causa importante de Disqueratosis congénita en el mundo.

Dyskeratosis congenita is a rare genetic disorder with approximately 180 cases reported in the literature. Objective: To present the case of a boy, in whom the diagnosis was clinically suspected and later confirmed by molecular analysis of the Dyskerin gene. Clinical Case: A school age boy with a history of anemia resistant to treatment, and severe bacterial infections, who presented with reticulated pigmentation of the skin, nail dystrophy, oral leukoplakia and progressive pancitopenia. Molecular analysis revealed a mutation in the DKC1 gene, that results in an aminoacid change from alanine to valine. Conclusion: Dyskeratosis congenita is a rare inherited disease characterised by cutaneous reticulated hyperpigmentation, nail dystrophy, oral leukoplakia and progressive pancytopenia. The mutation detected in this patient is an important cause of dyskeratosis congenita worldwide.

Degradation of 4-chlorophenol mediated by Fe(III)-NTA in homogeneous and heterogeneous systems.

In this work, the comparison of 4-chlorophenol (4-CP) degradation by two different AOT processes has been performed: a) a homogeneous system with Fe(III)-NTA (1:1 complex), b) a TiO2/Fe(III)-NTA heterogeneous system. In both cases, NTA appears to play a positive role in the photochemical reaction. In the homogeneous system, the iron salt is the only absorbing species and is proved to be able to photoinduce 4-CP degradation ([4-CP] = 0.1-0.2 mM, [FeNTA] = 0.3-0.9 mM, pH 4, lambda = 365 nm). The progress of the reaction was positively affected by the FeNTA concentration, and the reaction kept going even after the total disappearance of FeNTA. However, 4-CP complete degradation requires the presence of oxygen, otherwise the reaction stops. In the heterogeneous system ([4-CP] = 2.0 mM, [FeNTA] = 1.0-2.0 mM, [TiO2] = 0.1 and 1.0 g L(-1), pH 3, lambda = 300-400 nm), an important effect of the complex on the degradation extent and on the initial reaction rate can be seen, which overcomes the effect of non-complexed Fe(III). This behaviour is more important at the highest TiO2 concentration.

Homogeneous (Fe(III)) and heterogeneous (TiO2) photocatalytic systems for pollutant removal from the aquatic compartment: comparison and complementarity.

Kinetics of the oxidative photodegradation of monuron (3-(4-chlorophenyl)-1-1-dimethylurea) in both homogeneous solution of Fe(ClO4)3 and heterogeneous suspension of TiO2, were investigated and compared. In the homogeneous system (Fe(II)), the speciation of Fe(III) aquacomplexes was shown to play an essential role in the rate of photodegradation. For high concentrations of TiO2 (> 500 mg L(-1)), the photodegradation rate was similar to the reaction rate obtained with a freshly prepared solution of Fe(II) (3 x 10(-4) mol L(-1)). In the combined system (TiO2 + Fe(III)), a synergy effect accelerating the monuron photodegradation was observed. Actually, in the presence of Fe(III) (in concentration compatible with a safe environment), a similar reaction rate for monuron photodegradation was obtained with a TiO2 concentration lower by a factor of 20.

[Precurarization of succinylcholine with cisatracurium: the influence of the precurarization interval]. / Präkurarisierung von Succinylcholin mit Cisatracurium Der Einfluss des Präkurarisierungsintervalls.

PURPOSE: To determine the influence of two different pretreatment intervals, i.e. 3 and 6 min, on the efficacy of 0.01 mg/kg cisatracurium in preventing succinylcholine-induced fasciculations and myalgia. METHODS: A total of 60 adult patients were randomized and received either 0.01 mg/kg cisatracurium (0.2*ED(95)) i.v. (Cis 3 group: pretreatment interval 3 min, Cis 6 group: pretreatment interval 6 min) or normal saline i.v. (placebo group) prior to injection of succinylcholine. The incidence and severity of fasciculations and myalgia and side-effects of precurarization were assessed. RESULTS: The incidence of muscle fasciculations was only reduced in the Cis 6 group (45%) compared with the Placebo group (85%), p<0.05. Cisatracurium was associated with a higher incidence of paralytic symptoms in both pretreatment groups (Cis 3: 75%, Cis 6: 80%) compared with the Placebo group (30%), p<0.05. CONCLUSION: Cisatracurium is only effective in preventing succinylcholine-induced fasciculations when a longer pretreatment interval, i.e. 6 min instead of 3 min, is chosen. Precurarization led to signs of paralysis in both pretreatment groups in the majority (75-80%) of patients without reducing the incidence or severity of postoperative myalgia.

Feeding lambs high-oleate or high-linoleate safflower seeds differentially influences carcass fatty acid composition.

Our objective was to determine effects of dietary high-oleate (Oleate; 76% 18:1) or high-linoleate (Linoleate; 78% 18:2) safflower seeds on fatty acids in muscle and adipose tissue of feedlot lambs. White-faced ewe lambs (n = 36) were fed a beet pulp, oat hay, and soybean meal basal diet (Control), blocked by BW, and allotted randomly to dietary treatments. Cracked safflower seeds were used in isocaloric and isonitrogenous replacement of beet pulp, oat hay, and soybean meal so that Oleate and Linoleate diets contained 5.0% additional fat. Fatty acids were determined in semitendinosus, longissimus dorsi (longissimus), and adipose tissue from the tail head (tailhead adipose tissue), adjacent to the 12th rib (s.c. adipose tissue), and kidney and pelvic fat (KPH adipose tissue) depots. Fatty acid data were analyzed within muscle and adipose tissue as a split-block design. Single degree of freedom orthogonal contrasts were used to compare treatment effects. Average daily gain, feed efficiency, and carcass characteristics did not differ (P = 0.15 to 0.96) across dietary treatments. Adipose tissue saturated fatty acids were greater (P = 0.04) for Controls but were not different (P = 0.36) in muscle. Trans-vaccenic acid (18:1(trans-11)) increased (P < 0.0001) with safflower supplementation and was greater (P < 0.0001) in Linoleate than in Oleate for both tissue types. Linoleate lamb had greater (P < 0.0001) PUFA than Oleate lamb in muscle and adipose tissue. Conjugated linoleic acids (CLA; cis-9, trans-11 and trans-10, cis-12) were greater (P < 0.0001) in muscle and adipose tissue of lambs fed safflower seeds. Lambs fed Linoleate had greater (P < 0.0001) CLA in adipose tissue and muscle than lambs fed Oleate. Saturated fatty acids were greater (P < 0.0001) in s.c. adipose tissue than in tailhead adipose tissue. Mono- and polyunsaturated fatty acids were greater (P < 0.0001) in tailhead adipose tissue than in s.c. adipose tissue. Weight percentages of 18:1(trans-11) ranked tailhead adipose tissue = KPH adipose tissue > s.c. adipose tissue and semitendinosus > longissimus, whereas CLA ranked tailhead adipose tissue > s.c. adipose tissue > KPH adipose tissue and semitendinosus > longissimus. Feeding mono- and polyunsaturated fatty acids increased tissue 18:1(trans-11) and CLA, which is a favorable change in regard to current human dietary guidelines.

Two stereoisomeric 3(I),2(II)-anhydro-alpha-cyclodextrins: a molecular dynamics and crystallographic study.

Regioselective epoxide ring opening of 2(I),3(I)-(2(I)S)-anhydro-alpha-cyclodextrin (1) through intramolecular attack of hydroxyl groups of neighboring glucose rings occurs in diequatorial fashion to yield 3(I),2(II)-anhydro-alpha-cyclodextrin (3) with a rigid glucopyranose-dioxane-glucopyranose tricyclic ring system, the usual diaxial opening and the gluco/altro-configured stereoisomer 2 cannot be detected. Molecular dynamic simulations in water were used to analyze the conformations of 1-3 and the stereochemical implications of this reaction. Due to the contracted 2,3-OH side of the torus, 3 features an inverted conicity compared to the parent alpha-cyclodextrin. A crystallographic study on the bis-3.3 n-PrOH nonahydrate not only displays little variations between the solid-state and solution geometries of 3, but also provides a molecular picture of a unique inclusion complex in which three n-propanol molecules are distributed in the cavity of a dimeric unit of 3 (monoclinic, space group P2(1), a=14.257(1), b=22.623(2), c=16.644(1) A, beta=104.82(1) degrees, all 19,278 reflections with I>2 sigma(I) yield R(F)=0.1017).

Dawn simulation and bright light in the treatment of SAD: a controlled study.

BACKGROUND: Some small controlled studies have found that dawn simulation is effective in treating seasonal affective disorder (SAD). With a larger sample size and a longer duration of treatment, we compared dawn simulation with bright light therapy and a placebo condition in patients with SAD. METHOD: Medication-free patients with SAD were randomly assigned to one of three conditions: bright light therapy (10,000 lux for 30 min, from 6:00 AM to 6:30 AM), dawn simulation (1.5 hour dawn signal from 4:30 AM to 6:00 AM peaking at 250 lux), and a placebo condition, a dim red light (1.5 hour dawn signal from 4:30 am to 6:00 AM peaking at 0.5 lux.) Over the subsequent 6 weeks, the subjects were blindly rated by a psychiatrist using the Structured Interview Guide for the Hamilton Depression Rating-Seasonal Affective Disorder Version (SIGH-SAD). We modeled the profiles of the remissions (SIGH-SAD < or = 8) and response (> or =50% decrease in SIGH-SAD) to treatment over time using Cox proportional hazards models. RESULTS: The sample consisted of 95 subjects who were randomized to the three conditions: bright light (n = 33), dawn simulation (n = 31) and placebo (n = 31). Dawn simulation was associated with greater remission (p <.05) and response (p <.001) rates compared to the placebo. Bright light did not differ significantly from the placebo. Dawn simulation was associated with greater remission (p <.01) and response (p <.001) rates compared to the bright light therapy. The mean daily hours of sunshine during the week before each visit were associated with a significant increase in likelihood of both remission (p <.001) and response (p <.001). CONCLUSIONS: Dawn simulation was associated with greater remission and response rates compared to the placebo and compared to bright light therapy. The hours of sunshine during the week before each assessment were associated with a positive clinical response.