Asymmetrical Plasmon Distribution in Hybrid AuAg Hollow/Solid Coded Nanotubes

Morphological control at the nanoscale paves the way to fabricate nanostructures with desired plasmonic properties. In this study, we discuss the nanoengineering of plasmon resonances in 1D hollow nanostructures of two different AuAg nanotubes, including completely hollow nanotubes and hybrid nanotubes with solid Ag and hollow AuAg segments. Spatially resolved plasmon mapping by electron energy loss spectroscopy (EELS) revealed the presence of high order resonator-like modes and localized surface plasmon resonance (LSPR) modes in both nanotubes. The experimental findings accurately correlated with the boundary element method (BEM) simulations. Both experiments and simulations revealed that the plasmon resonances are intensely present inside the nanotubes due to plasmon hybridization. Based on the experimental and simulated results, we show that the novel hybrid AuAg nanotubes possess two significant coexisting features: (i) LSPRs are distinctively generated from the hollow and solid parts of the hybrid AuAg nanotube, which creates a way to control a broad range of plasmon resonances with one single nanostructure, and (ii) the periodicity of the high-order modes are disrupted due to the plasmon hybridization by the interaction of solid and hollow parts, resulting in an asymmetrical plasmon distribution in 1D nanostructures. The asymmetry could be modulated/engineered to control the coded plasmonic nanotubes.

Defect-Engineering-Stabilized AgSbTe2 with High Thermoelectric Performance

Thermoelectric (TE) generators enable the direct and reversible conversion between heat and electricity, providing applications in both refrigeration and power generation. In the last decade, several TE materials with relatively high figures of merit (zT) have been reported in the low- and high-temperature regimes. However, there is an urgent demand for high-performance TE materials working in the mid-temperature range (400-700 K). Herein, p-type AgSbTe₂ materials stabilized with S and Se co-doping are demonstrated to exhibit an outstanding maximum figure of merit (zT_max ) of 2.3 at 673 K and an average figure of merit (zT_ave ) of 1.59 over the wide temperature range of 300-673 K. This exceptional performance arises from an enhanced carrier density resulting from a higher concentration of silver vacancies, a vastly improved Seebeck coefficient enabled by the flattening of the valence band maximum and the inhibited formation of n-type Ag₂ Te, and ahighly improved stability beyond 673 K. The optimized material is used to fabricate a single-leg device with efficiencies up to 13.3% and a unicouple TE device reaching energy conversion efficiencies up to 12.3% at a temperature difference of 370 K. These results highlight an effective strategy to engineer high-performance TE material in the mid-temperature range.

The Importance of Surface Adsorbates in Solution-Processed Thermoelectric Materials: The Case of SnSe

Solution synthesis of particles emerges as an alternative to prepare thermoelectric materials with less demanding processing conditions than conventional solid-state synthetic methods. However, solution synthesis generally involves the presence of additional molecules or ions belonging to the precursors or added to enable solubility and/or regulate nucleation and growth. These molecules or ions can end up in the particles as surface adsorbates and interfere in the material properties. This work demonstrates that ionic adsorbates, in particular Na⁺ ions, are electrostatically adsorbed in SnSe particles synthesized in water and play a crucial role not only in directing the material nano/microstructure but also in determining the transport properties of the consolidated material. In dense pellets prepared by sintering SnSe particles, Na remains within the crystal lattice as dopant, in dislocations, precipitates, and forming grain boundary complexions. These results highlight the importance of considering all the possible unintentional impurities to establish proper structure-property relationships and control material properties in solution-processed thermoelectric materials.

Vitamin D Deficiency Is a Predictor of Mortality in Elderly with Chronic Heart Failure

Context

The prevalence of both heart failure and vitamin D deficiency increases with age and is associated with poor outcome in the elderly.

Objectives

We aimed to investigate the relationship between all-cause mortality and vitamin D deficiency in elderly patients with chronic heart failure.

Design

It is a retrospective, observational cross-sectional study. Median follow-up time was 497 days.

Subjects and Methods

302 patients aged ≥65 years heart failure patients was categorized into tertiles based on the 25-hydroxy-vitamin D levels. Clinical and laboratory parameters were evaluated according to tertiles. Hospitalization rates and overall survival were compared between tertiles. Independent predictors of all cause mortality were defined.

Results

Patients with low vitamin D tertile were mostly women (p=0.001), and had a worse NYHA functional class (p=0.005). During follow-up, deaths were more frequent in the first tertile (p = 0.001). All-cause mortality increased significantly with decreasing vitamin D tertiles (from third tertile 7.9%, to 11.9%, to 26%; log rank test p=0.003). No significant difference was observed at the composite endpoint of mortality or HF hospitalizations (P=0.451). Multivariate analysis supported that low vitamin D concentration was an independent predictor of all causes of mortality (HR 0.93; 95% CI 0.89-0.97; p=0.004).

Conclusions

Low vitamin D levels were independent predictors of all-cause mortality in the elderly population with chronic heart failure.

Exploiting the Lability of Metal Halide Perovskites for Doping Semiconductor Nanocomposites

Cesium lead halides have intrinsically unstable crystal lattices and easily transform within perovskite and nonperovskite structures. In this work, we explore the conversion of the perovskite CsPbBr₃ into Cs₄PbBr₆ in the presence of PbS at 450 °C to produce doped nanocrystal-based composites with embedded Cs₄PbBr₆ nanoprecipitates. We show that PbBr₂ is extracted from CsPbBr₃ and diffuses into the PbS lattice with a consequent increase in the concentration of free charge carriers. This new doping strategy enables the adjustment of the density of charge carriers between 10¹⁹ and 10²⁰ cm^-3, and it may serve as a general strategy for doping other nanocrystal-based semiconductors.

Synthesis, Bottom up Assembly and Thermoelectric Properties of Sb-Doped PbS Nanocrystal Building Blocks

The precise engineering of thermoelectric materials using nanocrystals as their building blocks has proven to be an excellent strategy to increase energy conversion efficiency. Here we present a synthetic route to produce Sb-doped PbS colloidal nanoparticles. These nanoparticles are then consolidated into nanocrystalline PbS:Sb using spark plasma sintering. We demonstrate that the introduction of Sb significantly influences the size, geometry, crystal lattice and especially the carrier concentration of PbS. The increase of charge carrier concentration achieved with the introduction of Sb translates into an increase of the electrical and thermal conductivities and a decrease of the Seebeck coefficient. Overall, PbS:Sb nanomaterial were characterized by two-fold higher thermoelectric figures of merit than undoped PbS.

Tuning Transport Properties in Thermoelectric Nanocomposites through Inorganic Ligands and Heterostructured Building Blocks

Methodologies that involve the use of nanoparticles as "artificial atoms" to rationally build materials in a bottom-up fashion are particularly well-suited to control the matter at the nanoscale. Colloidal synthetic routes allow for an exquisite control over such "artificial atoms" in terms of size, shape, and crystal phase as well as core and surface compositions. We present here a bottom-up approach to produce Pb-Ag-K-S-Te nanocomposites, which is a highly promising system for thermoelectric energy conversion. First, we developed a high-yield and scalable colloidal synthesis route to uniform lead sulfide (PbS) nanorods, whose tips are made of silver sulfide (Ag₂S). We then took advantage of the large surface-to-volume ratio to introduce a p-type dopant (K) by replacing native organic ligands with K₂Te. Upon thermal consolidation, K₂Te-surface modified PbS-Ag₂S nanorods yield p-type doped nanocomposites with PbTe and PbS as major phases and Ag₂S and Ag₂Te as embedded nanoinclusions. Thermoelectric characterization of such consolidated nanosolids showed a high thermoelectric figure-of-merit of 1 at 620 K.

Ligand-Mediated Band Engineering in Bottom-Up Assembled SnTe Nanocomposites for Thermoelectric Energy Conversion

The bottom-up assembly of colloidal nanocrystals is a versatile methodology to produce composite nanomaterials with precisely tuned electronic properties. Beyond the synthetic control over crystal domain size, shape, crystal phase, and composition, solution-processed nanocrystals allow exquisite surface engineering. This provides additional means to modulate the nanomaterial characteristics and particularly its electronic transport properties. For instance, inorganic surface ligands can be used to tune the type and concentration of majority carriers or to modify the electronic band structure. Herein, we report the thermoelectric properties of SnTe nanocomposites obtained from the consolidation of surface-engineered SnTe nanocrystals into macroscopic pellets. A CdSe-based ligand is selected to (i) converge the light and heavy bands through partial Cd alloying and (ii) generate CdSe nanoinclusions as a secondary phase within the SnTe matrix, thereby reducing the thermal conductivity. These SnTe-CdSe nanocomposites possess thermoelectric figures of merit of up to 1.3 at 850 K, which is, to the best of our knowledge, the highest thermoelectric figure of merit reported for solution-processed SnTe.

Polarized emission from CsPbBr3 nanowire embedded-electrospun PU fibers

Interest in all-inorganic halide perovskites has been increasing dramatically due to their high quantum yield, band gap tunability, and ease of fabrication in compositional and geometric diversity. In this study, we synthesized several hundreds of nanometer long and ∼4 nm thick CsPbBr 3 nanowires (NWs). They were then integrated into electrospun polyurethane (PU) fibers to examine the polarization behavior of the composite fiber assembly. Aligned electrospun fibers containing CsPbBr 3 NWs showed a remarkable increase in the degree of polarization from 0.17-0.30. This combination of NWs and PU fibers provides a promising composite material for various applications such as optoelectronic devices and solar cells.

Demonstrating the steady performance of iron oxide composites over 2000 cycles at fast charge-rates for Li-ion batteries

The feasibility of using iron oxides as negative electrode materials for safe high-power Li-ion batteries is demonstrated by the carbon-coated FeOx/CNT composite synthesized by controlled pyrolysis of ferrocene, which delivered a specific capacity retention of 84% (445 mA h g(-1)) after 2000 cycles at 2000 mA g(-1) (4C).

Investigation of genotoxic effects of doripenem using cytogenetic and molecular methods

The main aim of this study was to investigate the genotoxic effects of doripenem (DRP) using both cytogenetic and molecular test systems. Although there have been some studies reporting the effects of DRP, none of them has shown the genotoxic effects of DRP. In order to achieve the main aim of the study, the human peripheral lymphocytes were treated with 100 μg/ml, 200 μg/ml, and 400 μg/ml concentrations of DRP for 24 and 48 hours, and the chromosome aberration (CA) and micronucleus (MN) methods were used as the cytogenetic tests and RAPD-PCR method was used as the molecular test to determine the genotoxic effects of DRP. DRP did not induce the chromosome aberrations and micronucleus frequencies at all concentrations and at all treatment periods. So, it was concluded that DRP did not show any cytotoxic effect. However, DRP increased the number of polymorphic bands and decreased the ratio of genomic template stability, especially at the 48-hour treatment period. In this study, according to the obtained results, it was determined that DRP failed to show any genotoxic risk at the therapeutic doses. This result also indicates that DRP could be a reliable antibiotics according to its rapid metabolism.

Polybenzoxazine-Derived N-doped Carbon as Matrix for Powder-Based Electrocatalysts

In addition to catalytic activity, intrinsic stability, tight immobilization on a suitable electrode surface, and sufficient electronic conductivity are fundamental prerequisites for the long-term operation of particle- and especially powder-based electrocatalysts. We present a novel approach to concurrently address these challenges by using the unique properties of polybenzoxazine (pBO) polymers, namely near-zero shrinkage and high residual-char yield even after pyrolysis at high temperatures. Pyrolysis of a nanocubic prussian blue analogue precursor (K_m Mn_x [Co(CN)₆ ]_y ⋅n H₂ O) embedded in a bisphenol A and aniline-based pBO led to the formation of a N-doped carbon matrix modified with Mn_x Co_y O_z nanocubes. The obtained electrocatalyst exhibits high efficiency toward the oxygen evolution reaction (OER) and more importantly a stable performance for at least 65 h.

The analysis of lncRNA HOTAIR rs12826786 C>T polymorphism and gastric cancer susceptibility in a Turkish population: lack of any association in a hospital-based case-control study

BACKGROUND

The HOX transcript antisense intergenic RNA (HOTAIR), a well-known long noncoding RNA (lncRNA), has been widely identified to participate in pathogenesis of multiple cancers. An aberrant up-regulation and biological functions have been observed in gastric cancer (GC). A common single nucleotide polymorphism (SNP) (rs12826786 C>T) at the HOTAIR has been reported to influence HOTAIR expression, but its association with GC has yet to be investigated in Turkish population.

AIM

The aim of the present study was to investigate whether HOTAIR rs12826786 C>T polymorphism could be involved in the risk of GC susceptibility in Turkish population.

METHODS

We genotyped HOTAIR rs12826786 C>T polymorphism in 312 Turkish individuals including 105 GC patients and 207 healthy controls matched on age and gender by a Real-Time Polymerase Chain Reaction (PCR) with the TaqMan assay.

RESULTS

No statistically significant differences were found in the allele or genotype distributions of the HOTAIR rs12826786 C>T polymorphism among GC and healthy control subjects (P > 0.05).

CONCLUSIONS

Our results demonstrate that the HOTAIR rs12826786 C>T polymorphism has not been in any major role in genetic susceptibility to gastric carcinogenesis, at least in the population studied here. Independent studies are needed to validate our findings in a larger series, as well as in patients of different ethnic origins.

Inorganic Photocatalytic Enhancement: Activated RhB Photodegradation by Surface Modification of SnO2 Nanocrystals with V2O5-like species

SnO₂ nanocrystals were prepared by precipitation in dodecylamine at 100 °C, then they were reacted with vanadium chloromethoxide in oleic acid at 250 °C. The resulting materials were heat-treated at various temperatures up to 650 °C for thermal stabilization, chemical purification and for studying the overall structural transformations. From the crossed use of various characterization techniques, it emerged that the as-prepared materials were constituted by cassiterite SnO₂ nanocrystals with a surface modified by isolated V(IV) oxide species. After heat-treatment at 400 °C, the SnO₂ nanocrystals were wrapped by layers composed of vanadium oxide (IV-V mixed oxidation state) and carbon residuals. After heating at 500 °C, only SnO₂ cassiterite nanocrystals were obtained, with a mean size of 2.8 nm and wrapped by only V₂O₅-like species. The samples heat-treated at 500 °C were tested as RhB photodegradation catalysts. At 10^-7 M concentration, all RhB was degraded within 1 h of reaction, at a much faster rate than all pure SnO₂ materials reported until now.

Polymer-Enhanced Stability of Inorganic Perovskite Nanocrystals and Their Application in Color Conversion LEDs

Cesium lead halide (CsPbX3, X = Cl, Br, I) nanocrystals (NCs) offer exceptional optical properties for several potential applications but their implementation is hindered by a low chemical and structural stability and limited processability. In the present work, we developed a new method to efficiently coat CsPbX3 NCs, which resulted in their increased chemical and optical stability as well as processability. The method is based on the incorporation of poly(maleic anhydride-alt-1-octadecene) (PMA) into the synthesis of the perovskite NCs. The presence of PMA in the ligand shell stabilizes the NCs by tightening the ligand binding, limiting in this way the NC surface interaction with the surrounding media. We further show that these NCs can be embedded in self-standing silicone/glass plates as down-conversion filters for the fabrication of monochromatic green and white light emitting diodes (LEDs) with narrow bandwidths and appealing color characteristics.

Mn3O4@CoMn2O4-CoxOy Nanoparticles: Partial Cation Exchange Synthesis and Electrocatalytic Properties toward the Oxygen Reduction and Evolution Reactions

Mn3O4@CoMn2O4 nanoparticles (NPs) were produced at low temperature and ambient atmosphere using a one-pot two-step synthesis protocol involving the cation exchange of Mn by Co in preformed Mn3O4 NPs. Selecting the proper cobalt precursor, the nucleation of CoxOy crystallites at the Mn3O4@CoMn2O4 surface could be simultaneously promoted to form Mn3O4@CoMn2O4-CoxOy NPs. Such heterostructured NPs were investigated for oxygen reduction and evolution reactions (ORR, OER) in alkaline solution. Mn3O4@CoMn2O4-CoxOy NPs with [Co]/[Mn] = 1 showed low overpotentials of 0.31 V at -3 mA·cm(-2) and a small Tafel slope of 52 mV·dec(-1) for ORR, and overpotentials of 0.31 V at 10 mA·cm(-2) and a Tafel slope of 81 mV·dec(-1) for OER, thus outperforming commercial Pt-, IrO2-based and previously reported transition metal oxides. This cation-exchange-based synthesis protocol opens up a new approach to design novel heterostructured NPs as efficient nonprecious metal bifunctional oxygen catalysts.

Co-Cu Nanoparticles: Synthesis by Galvanic Replacement and Phase Rearrangement during Catalytic Activation

The control of the phase distribution in multicomponent nanomaterials is critical to optimize their catalytic performance. In this direction, while impressive advances have been achieved in the past decade in the synthesis of multicomponent nanoparticles and nanocomposites, element rearrangement during catalyst activation has been frequently overseen. Here, we present a facile galvanic replacement-based procedure to synthesize Co@Cu nanoparticles with narrow size and composition distributions. We further characterize their phase arrangement before and after catalytic activation. When oxidized at 350 °C in air to remove organics, Co@Cu core-shell nanostructures oxidize to polycrystalline CuO-Co3O4 nanoparticles with randomly distributed CuO and Co3O4 crystallites. During a posterior reduction treatment in H2 atmosphere, Cu precipitates in a metallic core and Co migrates to the nanoparticle surface to form Cu@Co core-shell nanostructures. The catalytic behavior of such Cu@Co nanoparticles supported on mesoporous silica was further analyzed toward CO2 hydrogenation in real working conditions.

High-performance thermoelectric nanocomposites from nanocrystal building blocks

The efficient conversion between thermal and electrical energy by means of durable, silent and scalable solid-state thermoelectric devices has been a long standing goal. While nanocrystalline materials have already led to substantially higher thermoelectric efficiencies, further improvements are expected to arise from precise chemical engineering of nanoscale building blocks and interfaces. Here we present a simple and versatile bottom–up strategy based on the assembly of colloidal nanocrystals to produce consolidated yet nanostructured thermoelectric materials. In the case study on the PbS–Ag system, Ag nanodomains not only contribute to block phonon propagation, but also provide electrons to the PbS host semiconductor and reduce the PbS intergrain energy barriers for charge transport. Thus, PbS–Ag nanocomposites exhibit reduced thermal conductivities and higher charge carrier concentrations and mobilities than PbS nanomaterial. Such improvements of the material transport properties provide thermoelectric figures of merit up to 1.7 at 850 K.

Nanomaterials provide a route to efficient solid-state conversion between thermal and electrical energy. Here, the authors demonstrate that a combination of metal and semiconductor colloidal nanocrystals can produce thermoelectric nanocomposites with high performance.

One-pot polyol synthesis of highly monodisperse short green silver nanorods

High yield production of green silver nanorods of a low aspect ratio via an optimized one-pot polyol method using tannic acid at substoichiometric concentrations.

Cu₂ZnSnS₄-Ag₂S Nanoscale p-n Heterostructures as Sensitizers for Photoelectrochemical Water Splitting

A cation exchange-based route was used to produce Cu2ZnSnS4 (CZTS)-Ag2S nanoparticles with controlled composition. We report a detailed study of the formation of such CZTS-Ag2S nanoheterostructures and of their photocatalytic properties. When compared to pure CZTS, the use of nanoscale p-n heterostructures as light absorbers for photocatalytic water splitting provides superior photocurrents. We associate this experimental fact to a higher separation efficiency of the photogenerated electron-hole pairs. We believe this and other type-II nanoheterostructures will open the door to the use of CZTS, with excellent light absorption properties and made of abundant and environmental friendly elements, to the field of photocatalysis.

High-yield synthesis and optical properties of g-C3N4

Graphitic carbon nitride (g-C3N4), a metal-free semiconductor with a band gap of 2.7 eV, has received considerable attention owing to its fascinating photocatalytic performances under visible-light. g-C3N4 exhibits high thermal and chemical stability and non-toxicity such that it has been considered as the most promising photocatalyst for environmental improvement and energy conservation. Hence, it is of great importance to obtain high-quality g-C3N4 and gain a clear understanding of its optical properties. Herein, we report a high-yield synthesis of g-C3N4 products via heating of high vacuum-sealed melamine powder in an ampoule at temperatures between 450 and 650 °C. Using transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), electron energy loss spectroscopy (EELS), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), the chemical composition and crystallization of the as-produced g-C3N4 are demonstrated. A systematic optical study of g-C3N4 is carried out with several approaches. The optical phonon behavior of g-C3N4 is revealed by infrared and Raman spectroscopy, and the emission properties of g-C3N4 are investigated using photoluminescence (PL) spectroscopy, while the photocatalytic properties are explored by the photodegradation experiment.

Size and aspect ratio control of Pd₂Sn nanorods and their water denitration properties

Monodisperse Pd2Sn nanorods with tuned size and aspect ratio were prepared by co-reduction of metal salts in the presence of trioctylphosphine, amine, and chloride ions. Asymmetric Pd2Sn nanostructures were achieved by the selective desorption of a surfactant mediated by chlorine ions. A preliminary evaluation of the geometry influence on catalytic properties evidenced Pd2Sn nanorods to have improved catalytic performance. In view of these results, Pd2Sn nanorods were also evaluated for water denitration.

Surface modification of TiO₂ nanocrystals by WO(x) coating or wrapping: solvothermal synthesis and enhanced surface chemistry

TiO2 anatase nanocrystals were prepared by solvothermal processing of Ti chloroalkoxide in oleic acid, in the presence of W chloroalkoxide, with W/Ti nominal atomic concentration (R(w)) ranging from 0.16 to 0.64. The as-prepared materials were heat-treated up to 500 °C for thermal stabilization and sensing device processing. For R(0.16), the as-prepared materials were constituted by an anatase core surface-modified by WO(x) monolayers. This structure persisted up to 500 °C, without any WO3 phase segregation. For R(w) up to R(0.64), the anatase core was initially wrapped by an amorphous WO(x) gel. Upon heat treatment, the WO(x) phase underwent structural reorganization, remaining amorphous up to 400 °C and forming tiny WO3 nanocrystals dispersed into the TiO2 host after heating at 500 °C, when part of tungsten also migrated into the TiO2 structure, resulting in structural and electrical modification of the anatase host. The ethanol sensing properties of the various materials were tested and compared with pure TiO2 and WO3 analogously prepared. They showed that even the simple surface modification of the TiO2 host resulted in a 3 orders of magnitude response improvement with respect to pure TiO2.

In situ template synthesis of gold nanoparticles using a bis-imidazolium amphiphile-based hydrogel

HYPOTHESIS

Gemini-type bis-imidazolium amphiphiles are able to stabilize gold nanoparticles (GNPs) and also form hydrogels. It should be possible to obtain GNPs synthesized within these hydrogels and stabilized by the bis-imidazolium molecules.

EXPERIMENTS

Hydrogels containing a gold salt were formed using 1,3-bis[(3-octadecyl-1-imidazolio)methyl]benzene dibromide. After aging of the gel, upon addition of the reducing agent in a solvent the formation of GNPs was assessed. The gel was characterised and the GNPs were observed using High Resolution Transmission Electron Microscopy (HRTEM).

FINDINGS

Monodisperse GNPs with an average size of ca. 5 nm and well defined icosahedral geometry were formed in situ using the bis-imidazolium amphiphile-based hydrogel as template. Furthermore the gelator is also the stabilizing ligand of the GNPs, allowing the recovery of the GNP by disassembling the gel without aggregation of the inorganic colloid.

Solvothermal, chloroalkoxide-based synthesis of monoclinic WO(3) quantum dots and gas-sensing enhancement by surface oxygen vacancies

We report for the first time the synthesis of monoclinic WO3 quantum dots. A solvothermal processing at 250 °C in oleic acid of W chloroalkoxide solutions was employed. It was shown that the bulk monoclinic crystallographic phase is the stable one even for the nanosized regime (mean size 4 nm). The nanocrystals were characterized by X-ray diffraction, High resolution transmission electron microscopy, X-ray photoelectron spectroscopy, UV-vis, Fourier transform infrared and Raman spectroscopy. It was concluded that they were constituted by a core of monoclinic WO3, surface covered by unstable W(V) species, slowly oxidized upon standing in room conditions. The WO3 nanocrystals could be easily processed to prepare gas-sensing devices, without any phase transition up to at least 500 °C. The devices displayed remarkable response to both oxidizing (nitrogen dioxide) and reducing (ethanol) gases in concentrations ranging from 1 to 5 ppm and from 100 to 500 ppm, at low operating temperatures of 100 and 200 °C, respectively. The analysis of the electrical data showed that the nanocrystals were characterized by reduced surfaces, which enhanced both nitrogen dioxide adsorption and oxygen ionosorption, the latter resulting in enhanced ethanol decomposition kinetics.

A multidisciplinary approach to the management of individuals with fragile X syndrome

BACKGROUND

Fragile X syndrome (FXS) is the most common inherited form of intellectual disability. Since the identification of the responsible gene (FMR1) and its protein (FMRP), there has been enormous progress in both clinical and pathogenetic research on the neurobehavioural aspects of the condition. However, studies regarding other medical problems anticipated in individuals with FXS are limited. A multidisciplinary study evaluating various causes of morbidity in the same group has not been published yet.

METHODS

Twenty-four boys with FXS full mutation were recruited out of a larger group of 103 diagnosed in one centre over the past 10 years. Ear nose and throat, eye and cardiac examinations were performed in addition to routine cognitive, behavioural, neurological and speech and language assessments.

RESULTS

The average IQ score was 49.8 +/- 20 (range 25-90). There were four patients (18%) with IQ above 70. Using DSM-IV, attention deficit hyperactivity disorder was diagnosed in five boys out of 22 examined (23%), while 32% were diagnosed with pervasive developmental disorder. The seizure frequency was 17%. A psychiatric disorder was diagnosed in six out of eight boys with electroencephalogram abnormalities (75%). Minimal conductive hearing loss was found in five (5/22) patients. There was significant delay in both expressive and receptive language skills. Ocular findings were refractive errors (13%) and strabismus (4.4%). Mitral valve prolapsus (MVP) was observed in 3/22 (13.7%) patients and aortic annulus dilatation was present in 2/22 (9%) patients.

CONCLUSIONS

Frequency of psychiatric diagnoses made with DSM-IV were in parallel to those reported in the literature. Comorbidity of seizures and psychiatric disorders was noteworthy. The percentage of 'high-functioning' full mutation males supports the previous observations. Ear nose and throat and eye examination revealed remarkably lower prevalence of abnormal findings than reported. MVP was slightly less frequent compared with the single study in the literature. Age at the time of examination had an effect on the outcome of cardiac evaluation. These findings will guide us in future management of the group of patients followed in our institution. The protocol applied provides an applicable outline for multidisciplinary institutional settings dealing with individuals with FXS.

Testis fixation in prepubertal rats: fibrin glue versus transparenchymal sutures reduces testicular damage

Experimental studies have shown that different suture materials used in testis fixation cause some degree of inflammation in the testis. This study was planned to compare the histological changes that were caused by fibrin glue which is a tissue sealant and by silk and polypropylene for transparenchymal testis fixation. 28 prepubertal rats were divided into 4 groups. Testis was fixed to the tunica vaginalis by fibrin glue in group 1, by silk in group 2 and by polypropylene in group 3. Group 4 was planned as a control. Testicular inflammation and seminiferous tubular diameter were evaluated for histological changes. The least inflammation was observed in the fibrin glue group, while the most inflammation occurred in the silk group. Seminiferous tubular diameter was 241.55 +/- 45.90 in the fibrin glue group, 151.90 +/- 8.34 in the silk group and 161.36 +/- 9.96 in the polypropylene group. In conclusion, fibrin glue, when used for testis fixation, causes less inflammation and less destruction of seminiferous tubular diameter compared with silk and polypropylene.

Analysis of meatal location in 300 boys

The high incidence of anterior hypospadias and the consideration of some of the parents that this location is a normal variation and the resistance to the surgical treatment led us to investigate the normal meatal location in boys. The location of external meatus was analyzed in 300 boys. The meatal location was classified as type A (anterior third/tip of the glans) type B (middle third) and type C (posterior third/glandular hypospadias). Of the 300 boys taken into study, in 282 (94%) meatus was located at the tip of the glans in 14 patients (4.6%) on the middle third, 'type B' and in 2 patients (0.6%) on the posterior third, 'type C'. The present study clearly demonstrated that the true location of urethral meatus should be at the tip of the glans. Type B is an acceptable location, which requires no operation and is seen in a very small percentage. Type C is a true glandular hypospadias and should certainly be corrected by glanuloplasty and meatal advancement. We are of the opinion that after surgery for anterior hypospadias meatal position presenting elsewhere than at the tip of the glans should not be considered a successful intervention.

Histopathological evaluation of the urethra after the Snodgrass operation: an experimental study in rabbits

OBJECTIVE

To investigate the histopathological outcome of the incised urethral plate after tubularized incised-plate urethroplasty (the Snodgrass procedure to repair hypospadias) in a hypospadiac rabbit model, as it can produce meatal and neourethral strictures, and healing with scarring.

MATERIALS AND METHODS

The study comprised 10 male New Zealand White rabbits (2.2-2.4 kg); under general anaesthesia the ventral urethra was completely excised 1 cm from the meatus proximally and a model of hypospadias formed. A full-thickness incision was then made in the distal dorsal urethra and the two sides of the incision marked by Indian ink tattooing. After placing a feeding tube (5 F) as a urethral catheter, both urethral wings were sutured ventrally by a 7/0 polydioxanone running suture, and the penile skin approximated by 5/0 chromic catgut. At 21 days and 3 months after surgery the penises were harvested, assessed histopathologically, and compared with those from control untreated rabbits of the same age and weight.

RESULTS

In the study group the incised area of the dorsal urethra was re-epithelialized; the regional tissue and vascularity were normal.

CONCLUSION

In this rabbit model the dorsal urethral incisions healed with no scar tissue; only the ventral suture lines had minimal fibrosis and inflammatory reaction.

Phe 84 deletion of the PMP22 gene associated with hereditary motor and sensory neuropathy HMSN III with multiple cranial neuropathy: clinical, neurophysiological and magnetic resonance imaging findings

Hereditary motor and sensory neuropathy (HMSN) is a heterogeneous group of peripheral neuropathies which are diagnosed on the basis of clinical, electrophysiological and neuropathological findings. Among the hypertrophic demyelinating neuropathies, HMSN III is the most severe. It is often associated with de novo mutations in the genes encoding for peripheral myelin proteins. While peripheral nerve hypertrophy is an expected finding in HMSN III, cranial nerve hypertrophy is exceptional. Here we describe a mutation in the PMP22 gene in a 19-year-old man with infantile onset of sensory motor polyneuropathy without family history and multiple cranial nerve hypertrophy shown by cranial magnetic resonance imaging.

Thermal and optical properties of Tm3+ doped tellurite glasses

Ultraviolet, visible (UV/VIS) and differential thermal analysis (DTA) measurements were carried out in order to investigate the optical and thermal properties of various 0.5 mol.% Tm2O3 containing (1 - x)TeO2 + xLiCl glasses in molar ratio. The samples were prepared by fusing the mixture of their respective reagent grade powders in a platinum cricuble at 750 degrees C for 30 min. DTA curves taken in the 23-600 degrees C temperature range with a heating rate of 10 degrees C/min reveal a change in the value of the glass transition temperature, Tg, while melting was not observed for the glasses containing LiCl content less than 50 mol.%. These glasses were found to be moisture-resistant. However, the glasses with LiCl content higher than 50 mol.%, in which a melting peak was observed at Tc = 401 degrees C, were moisture-sensitive. Absorption measurements in the UV/VIS region of the glasses without Tm2O3 content show that the Urbach cutoff occurs at about 320 nm and, is relatively independent of the LiCl content. Six absorption bands were observed in the Tm2O3 doped glasses corresponding to the absorption of the 1G4, 3F2, 3F3 and 3F4, 3H5 and 3H4 levels from the 3H6 ground level of Tm3+ ions. The spectra also show that the integrated absorption cross-section of each band depends on the glass composition. Judd-Ofelt theory was used to determine the Judd-Ofelt parameters as well as the radiative transition probabilities for the metastable levels of Tm3+ ions in (0.3)LiCl + (0.7) TeO2: 0.01 Tm2O3 glass which is moisture-resistant.

Long-term follow-up and evaluation of autoaugmentation cystoplasty (detrusorotomy) in an animal model

OBJECTIVE

To evaluate long-term follow-up of an autoaugmentation (detrusorotomy) technique, in puppies.

PATIENTS AND METHODS

In 10 mongrel puppies, bladder capacities were reduced to nearly half their original volume by 10 per cent formalin instillations. In 7 puppies, the muscular coat of the bladder was split open widely down to the mucosal layer, from the bladder neck anteriorly, to the trigone posteriorly while the mucosa was kept exposed and intact. Three puppies were kept as controls.

RESULTS

Mean post-instillation bladder capacity was 15.40 ml. One week after detrusorotomy the bladder capacity averaged up to 20.00 ml; 3 weeks later up to 20.43 ml; and 3 months later up to 34.28 ml and were well up to 3 months. However, at the termination of an additional 9-month period, the bladders of 4 of the remaining five dogs were seen to decrease in volume except the one with an accidental omental adherence to the exposed mucosa which kept the detrusorotomy intact.

CONCLUSION

Post-detrusorotomy volume could be retained if a graft, e.g. omentum, gut segment, amniotic membrane or lyophilized dura is inserted at the time of intervention, in-between the split musculature to line the exposed mucosa externally and to prevent re-adhesion of the muscular edges.

Management of pneumothorax in children

BACKGROUND

The efficacy of tube thoracostomies inserted at the sixth intercostal space at midaxillary line was evaluated retrospectively in children.

METHODS

Ninety-seven children with pneumothorax, treated by tube thoracostomy were taken into the study. There were 67 male and 30 female patients with a mean age of 6.5 years (range 1 days to 15 years)

RESULTS

Pneumothorax was located at the right side in 50 (51.5%), and at the left in 38 (39.1%) of the cases. Bilateral pneumothorax was found in 9 additional patients (9.2%). All patients were treated with tube thoracostomy placed in the pleural cavity at the sixth intercostal space at the mid-axillary line. Postoperative course was uneventful and no complication was encountered at any of the patients.

CONCLUSIONS

On the basis of these data we suggest that all thoracostomy tubes should be inserted on the sixth intercostal space where both air and the accumulating fluid can be reached. The insertion of the thoracostomy tube at the second intercostal space must be avoided since it carries a high risk of subclavian vein injury in small children, and also a secondary tube is frequently required to drain the accompanying intrapleural fluid.

Askin tumors in children: a report of four cases

Primary malignant tumors of the chest are rare in the pediatric age group. Askin tumor belongs to the peripheral primitive neuroectodermal tumor family, and typically involves the periosteum, soft tissue and extrapulmonary tissue of the thoracic wall. We report our ten years experience with four cases of this rare tumor.

Dermatomal and mixed nerve somatosensory evoked potentials in the diagnosis of neurogenic thoracic outlet syndrome

To evaluate the diagnostic utility of dermatomal and mixed nerve somatosensory evoked potentials (SEPs) in patients with thoracic outlet syndrome (TOS) and to compare their value with routine electrodiagnostic methods, we studied a group of 44 patients with neurogenic TOS and 30 healthy controls. In addition to bilateral median and ulnar SEPs, evoked potentials were recorded after stimulation of C6 and C8 dermatomes from the first and fifth digits, respectively. The patients were classified into 3 groups according to the nature of their clinical condition. The abnormality rate for both ulnar and C8 dermatomal SEPs was 100% in a small group of patients with severe neurological signs like atrophy. In groups of patients with lesser degrees of neurogenic damage, abnormality rates for ulnar and C8 dermatomal SEPs on affected limb(s) were 67 and 50%, respectively. Same abnormality rates were 25 and 18% in patients with only subjective symptoms. In patients with objective neurological signs, the major increase in sensitivity was with electromyography (EMG). Abnormalities of routine nerve conduction studies and F-wave latency were observed in patients with severe neurogenic damage. We concluded that the most useful tests in the diagnosis of neurogenic TOS are needle EMG and ulnar SEPs.

Gastroesophageal reflux: a determinant in the outcome of caustic esophageal burns

Deep circumferencial burns of the esophagus always result in stricture formation and obstruction of the lumen. The usual treatment of caustic esophageal strictures is long-term esophageal dilatations. A new method of treatment, long-term stenting of the strictured esophagus gave superior results when compared with the classic dilatation therapy (healing rates, 68% v 33%; P < .01). Although success in the stent group was very satisfactory, the 32% failure rate requires explanation. In the years between 1991 and 1993, 53 stent-treated patients were screened for gastroesophageal reflux (GER). All patients were investigated with 24-hour ambulatory distal esophageal pHmetry. In 18 patients reflux index (RI) was found to be below 4. In 14 patients RI was between 4.1 and 19. In the final group of 21 patients RI was over 20 (minimum, 21.8; maximum, 72.8). When these data were compared with the healing rates of the patients, it was found that none of the 21 patients with RI over 20 responded to the described therapy. We conclude that the esophagus, after a serious caustic insult, not only narrows but also shortens thus altering the lower esophageal sphincter function leading to serious GER. Therefore all caustic esophageal burn patients should be screened for GER periodically during the dilatation or stent therapy programs, and GER should be controlled before RI approaches 20.