Primary intestinal melanoma?

The vast majority of malignant melanomas in the small intestine are metastasis of cutaneous tumors. Few cases have been published on primary melanomas in this location, some authors consider that they are always metastatic and that the primary tumor has regressed. In this letter, we present the case of a 77-year-old woman with a history of cutaneous melanoma excision 38 years ago who was diagnosed with ileal melanoma in the absence of other lesions during the study of iron deficiency anemia, and we discuss about the origin of this type of neoplasms.

Photoactive Zr and Ti Metal-Organic-Frameworks for Solid-State Solar Cells.

Solid-state photovoltaic cells based on robust metal-organic frameworks (MOFs), MIL-125(Ti), MIL-125(Ti)-NH2 , UiO-67, Ru(bpy)2 -UiO-67, (bpy 2,2'-bipyridine) as active components and spiro-MeOTAD (MeOTAD 2,2',7,7'-tetrakis[N,N-di(p-methoxyphenyl)amino]-9,9'-spirobifluorene) as hole transporting layer have been prepared., The photovoltaic response of this material increases in the presence of bathochromic -NH2 groups on the linker or Ru (II) polypyridyl complexes light harvester. These results show that the strategies typically employed in photocatalysis to enhance the photocatalytic activity of MOFs can also be applied in the field of photovoltaic devices.

Enzyme replacement therapy for the treatment of Hunter disease: A systematic review with narrative synthesis and meta-analysis.

BACKGROUND: In the last 10 years enzyme replacement therapy (ERT) has become an alternative for the treatment of patients with Hunter disease (HD). Nevertheless, the information regarding efficacy and safety is scarce and mainly based on the pivotal trials. This scarcity is especially evident for adults and severe forms of HD. METHODS: A systematic review of publications in the electronic databases PUBMED, EMBASE and Cochrane Central was undertaken. Clinical trials and observational studies were included. The data about efficacy and security were retrieved and analysed with Review Manager version 5.3. RESULTS: 677 records were found, 559 remaining after the removal of duplicates. By title and abstract review, 427 were excluded. Full reading of the rest was made (122 publications) and 42 were finally included. It was not possible to perform meta-analysis of all the endpoints due to high heterogeneity in the reporting and measuring of variables in each publication. Eight clinical trials were included, 6 with high risk of bias. The quality of the other studies was low in 12%, average in 68% and good in 21%. Main findings were: a reduction in the elimination of glycosaminoglycans (GAG) in urine in all the studies (26/26), decrease in liver and spleen size (18/18), increase of 52.59 m (95% CI, 36, 42-68.76, p < .001) in the 6-min walk test (TM6M), increase in forced vital capacity (FVC) of 9.59% (95% CI 4.77-14.51, p < .001), reduction of the left ventricular mass index of 3.57% (95% CI 1.2-5.93) and reduction in mortality (OR) of 0.44 (0.27-0.71). DISCUSSION: The data suggests a clear and consistent effect of ERT in HD reducing the accumulation of GAGs in the body, demonstrated by the reduction of its urinary excretion, as well as by the reduction of its deposits (spleen, liver and heart). Likewise, there is an improvement in physical and respiratory function. In addition, a reduction in mortality has been observed. Lack of studies, small size of the samples, and methodological deficiencies are the main limitations to establish definite conclusions. CONCLUSIONS: The data suggests that ERT is effective and safe in the treatment of HD. There is a need to evaluate patient-centred outcomes and the impact on quality of life.

Supramolecular Anchoring of Octahedral Molybdenum Clusters onto Graphene and Their Synergies in Photocatalytic Water Reduction.

Dihydrogen (H2) production from sunlight should become one of the most important energy production means in the future. To reach this goal, low-cost and efficient photocatalysts still need to be discovered. Here we show that red near-IR luminescent metal cluster anions, once combined with pyrene-containing cations, are able to photocatalytically produce molecular hydrogen from water. The pyrene moieties act simultaneously as energy transmitters and as supramolecular linkers between the cluster anions and graphene. This association results in a hybrid material combining the emission abilities of pyrene and cluster moieties with the electronic conduction efficiency of graphene. Hydrogen evolution reaction (HER) studies show that this association induces a significant increase of H2 production compared to that produced separately by clusters or graphene. Considering the versatility of the strategy described to design this photocatalytic hybrid material, transition-metal clusters are promising candidates to develop new, environmentally friendly, and low-cost photocatalysts for HER.

Gas Sensing Properties of Perovskite Decorated Graphene at Room Temperature.

This paper explores the gas sensing properties of graphene nanolayers decorated with lead halide perovskite (CH3NH3PbBr3) nanocrystals to detect toxic gases such as ammonia (NH3) and nitrogen dioxide (NO2). A chemical-sensitive semiconductor film based on graphene has been achieved, being decorated with CH3NH3PbBr3 perovskite (MAPbBr3) nanocrystals (NCs) synthesized, and characterized by several techniques, such as field emission scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. Reversible responses were obtained towards NO2 and NH3 at room temperature, demonstrating an enhanced sensitivity when the graphene is decorated by MAPbBr3 NCs. Furthermore, the effect of ambient moisture was extensively studied, showing that the use of perovskite NCs in gas sensors can become a promising alternative to other gas sensitive materials, due to the protective character of graphene, resulting from its high hydrophobicity. Besides, a gas sensing mechanism is proposed to understand the effects of MAPbBr3 sensing properties.

Synthesis, characterization and photoinduced charge separation of carbon nanohorn-oligothienylenevinylene hybrids.

The covalent coupling between oligo(thienylenevinylenes) (nTVs) and carbon nanohorns (CNHs) has been investigated. The resulting nanohybrids have been characterized by a combination of several techniques, including thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HR-TEM) and Raman spectroscopy. The photophysical properties of the new hybrids were investigated by steady-state and time-resolved spectroscopic techniques. A transient signal characterized by two kinetic regimes, one short decay within 0.5 µs corresponding to around 80% of the total signal and another much longer-lived decay of 10 µs, has been detected. The transient absorption spectra are characterized by a continuous absorption that increases in intensity towards shorter wavelengths, with a maximum at 430 nm. These transient signals have been assigned to the charge-separated state delocalized on CNHs based on the quenching behavior and by comparison with the photophysical properties of nTV in the absence and presence of quenchers. The photophysical behavior of covalent nTV-CNH conjugates with microsecond transients due to electrons and holes on CNHs contrasts with the absence of any transient for analogous nTV-C60 conjugates, for which charge separation was not observed at timescales longer than nanoseconds. The photochemical behavior of CNHs is believed to derive from the amphoteric (electron donor and acceptor) properties of CNHs and from the larger number of carbon atoms (efficient delocalization) in CNHs compared with C60.

p-n Heterojunction of doped graphene films obtained by pyrolysis of biomass precursors.

Nitrogen-doped graphene [(N)G] obtained by pyrolysis at 900 °C of nanometric chitosan films exhibits a Hall effect characteristic of n-type semiconductors. In contrast, boron-doped graphene [(B)G] obtained by pyrolysis of borate ester of alginate behaves as a p-type semiconductor based also on the Hall effect. A p-n heterojunction of (B)G-(N)G films is built by stepwise coating of a quartz plate using a mask. The heterojunction is created by the partial overlapping of the (B)G-(N)G films. Upon irradiation with a xenon lamp of aqueous solutions of H(2) PtCl(6) and MnCl(2) in contact with the heterojunction, preferential electron migration from (B)G to (N)G with preferential location of positive holes on (B)G is established by observation in scanning electron microscopy of the formation of Pt nanoparticles (NP) on (N)G and MnO(2) NP on (B)G. The benefits of the heterojunction with respect to the devices having one individual component as a consequence of the electron migration through the p-n heterojunction are illustrated by measuring the photocurrent in the (B)G-(N)G heterojunction (180% current enhancement with respect to the dark current) and compared it to the photocurrent of the individual (B)G (15% enhancement) and (N)G (55% enhancement) components.

Visible-light photoresponse of gold nanoparticles supported on TiO2 : a combined photocatalytic, photoelectrochemical, and transient spectroscopy study.

In the context of gaining understanding on the origin of the visible-light photoresponse of TiO2 containing gold nanoparticles, the photocurrent spectra and photocatalytic H2 evolution of titania (P25) and Au-P25 were compared. Whereas no photocurrent was detected upon visible-light irradiation for either of the two photocatalysts, Au-P25 exhibited photocatalytic H2 evolution for wavelengths between 400 and 575 nm. This contradictory behavior under visible-light irradiation of Au-P25 was rationalized by transient absorption spectroscopy. It was suggested that photocatalytic H2 generation results from methanol quenching of the charge-separation state in each semiconductor nanoparticle, but the lack of photocurrent is due to the short lifetime of the charge separation, which makes interparticle charge migration for micrometric distances unlikely.

Efficiency Records in Mesoscopic Dye-Sensitized Solar Cells.

The aim of the present review article is to show the progress achieved in the efficiency of dye-sensitized solar cells (DSSCs) by evolution in the structure and composition of the dye. After an initial brief description of DSSCs and the operating mechanism the major part of the present article is organized according to the type of dye, trying to show the logic in the variation of the dye structure in order to achieve strong binding on the surface of the layer of nanoparticulate TiO2 , efficient interfacial electron injection between the excited dye and the semiconductor, and minimization of the unwanted dark current processes. Besides metal complexes, including polypyridyls and nitrogenated macro rings, organic dyes and inorganic light harvesters such as quantum dots and perovskites have also been included in the review. The last section summarizes the current state of the art and provides an overview on future developments in the field.

Double-wall carbon nanotube-porphyrin supramolecular hybrid: synthesis and photophysical studies.

Double-wall carbon nanotubes (DWCNTs) with pyridyl units covalently attached to the external wall through isoxazolino linkers and carboxylic groups that have been esterified by pentyl chains are synthesized. The properties of these modified DWCNTs are then compared with an analogous sample based on single-wall carbon nanotubes (SWCNTs). Raman spectroscopy shows the presence of characteristic radial breathing mode vibrations, confirming that the samples partly retain the integrity of the nanotubes in the case of DWCNTs, including the internal and external nanotubes. Quantification of the pyridyl content for both samples (DWCNT and SWCNT derivatives) is based on X-ray photoelectron spectroscopy and thermogravimetric profiles, showing very similar substituent load. Both pyridyl-containing nanotubes (DWCNTs and SWCNTs) form a complex with zinc porphyrin (ZnP), as evidenced by the presence of two isosbestic points in the absorption spectra of the porphyrin upon addition of the pyridyl-functionalized nanotubes. Supramolecular complexes based on pyridyl-substituted DWCNTs and SWCNTs quench the emission and the triplet excited state identically, through an energy-transfer mechanism based on pre-assembly of the ground state. Thus, the presence of the intact inner wall in DWCNTs does not influence the quenching behavior, with respect to SWCNTs, for energy-transfer quenching with excited ZnP. These results sharply contrast with previous ones referring to electron-transfer quenching, in which the double-wall morphology of the nanotubes has been shown to considerably reduce the lifetime of charge separation, owing to faster electron mobility in DWCNTs compared to SWCNTs.

Delayed electron-hole pair recombination in iron(III)-oxo metal-organic frameworks.

The photodynamic properties of a series of Fe(III)-MOFs have been examined via redox reactions with N,N,N',N'-tetramethyl-p-phenylenediamine as an electron donor and methyl viologen as an electron acceptor. Furthermore, photogeneration of long-lived species in MIL-88B(Fe) has been proven via transient absorption spectroscopy.

Enhanced CO2 Sensing by Oxygen Plasma-Treated Perovskite-Graphene Nanocomposites.

Carbon dioxide (CO2) is a major greenhouse gas responsible for global warming and climate change. The development of sensitive CO2 sensors is crucial for environmental and industrial applications. This paper presents a novel CO2 sensor based on perovskite nanocrystals immobilized on graphene and functionalized with oxygen plasma treatment. The impact of this post-treatment method was thoroughly investigated using various characterization techniques, including Raman spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The detection of CO2 at parts per million (ppm) levels demonstrated that the hybrids subjected to 5 min of oxygen plasma treatment exhibited a 3-fold improvement in sensing performance compared to untreated layers. Consequently, the CO2 sensing capability of the oxygen-treated samples showed a limit of detection and limit of quantification of 6.9 and 22.9 ppm, respectively. Furthermore, the influence of ambient moisture on the CO2 sensing performance was also evaluated, revealing a significant effect of oxygen plasma treatment.

Regioselectivity in Pyrene-Templated Polymerization Using MOFs as 1D Porous Scaffolds.

Physicochemical properties of polymers strongly depend on the arrangement and distribution of attached monomers. Templated polymerization using porous crystalline materials appears as a promising route to gain control on the process. Thus, we demonstrate here the potential of metal-organic frameworks as scaffolds with a versatile and very regular porosity, well adapted for the regioselective oxidative polymerization of pyrene. This photoresponsive monomer was first encapsulated within the one-dimensional (1D) microporosity of the robust zirconium(IV) carboxylate metal-organic framework (MOF) (MIL-140D) to, later, undergo in situ oxidative polymerization, enabling the growth of a highly selective polypyrene (PPyr) regioisomer over other potential polymer configurations. To confirm the polymerization and the geometry control of pyrene, the resulting composites were exhaustively characterized by powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), N2 sorption measurements, scanning transmission electron microscopy coupled with energy-dispersive X-ray (STEM-EDX) spectroscopy, and fluorescence spectroscopy. Among others, photoluminescence quenching and emission shift in the solid state demonstrated the presence of PPyr inside the MOF porosity. Furthermore, an in-depth joint analysis combining solid-state, magic-angle spinning (MAS) 1H and 13C NMR spectroscopy, Fourier transform infrared (FTIR) spectroscopy, matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy (MALDI-TOF MS), and molecular simulations (grand canonical Monte Carlo (GCMC) and density functional theory (DFT)) allowed the elucidation of the spatial, host-guest interactions driving the polymerization reaction.

Impact of Implementing an Antimicrobial Stewardship Program for Optimizing Antibiotic Treatment in Gram-negative Bacilli Bacteremia.

BACKGROUND: Antibiotic Stewardship Programs (ASP) have improved empirical and directed antibiotic treatment in Gram-negative bloodstream infections. A decrease in mortality, readmission, and length of hospitalization has been reported. MATERIALS AND METHODS: A pre-post-quasi-experimental study was conducted between November and April 2015-2016 (pre-intervention period), 2016-2017, 2017-2018, and 2018-2019 (post-intervention periods), to analyse the impact of ASP on empirical, directed, and entire treatment optimization, as well as mortality, readmission, and length of hospitalization, in hospitalized patients with Gram-negative bacilli (GNB) bloodstream infections. RESULTS: One hundred seventy-four patients were included (41 in the pre-intervention group, 38 in the first-year post-intervention group, 50 in the second-year post-intervention group, and 45 in the third-year post-intervention group). There was a significant improvement in directed treatment optimization (43.9% in the pre-intervention group, 68.4% in the first-year post-intervention group, 74% in the second-year post-intervention group, and 88.9% in the third-year post-intervention group, P <0.001), as well as in entire treatment optimization (19.5%, 34.2%, 40.0%, and 46.7%, respectively, P=0.013), with increased optimal directed (adjusted odds ratio [aOR], 3.71; 95% confidence interval [CI], 1.60-8.58) and entire treatment (aOR, 3.31; 95% CI, 1.27-8.58). Although a tendency toward improvement was observed in empirical treatment after ASP implementation, it did not reach statistical significance (41.5% vs. 57.9%, P=0.065). No changes in mortality, readmission, or length of hospitalization were detected. CONCLUSION: ASP implementation improved both directed and entire treatment optimization in patients with GNB bloodstream infections over time. Nevertheless, no improvement was found in clinical outcomes such as mortality, readmission, or length of hospitalization.

Formation and properties of a hybrid organosilica with a p-phenylene vinylene polymer partially grafted to the walls.

The present manuscript reports a mesoporous organosilica (mpSiO(2)) containing a p-phenylene vinylene (PPV) co-polymer partially grafted to the walls of the hybrid material (PPV⊂mpSiO(2)). This material was obtained by using a bis-silylated 2,5-bis(chloromethylphenylene) as the silicon precursor in combination with tetraethyl orthosilicate (TEOS) and cetyltrimethylammonium bromide (CTABr) as the surfactant. The final polymer was formed by adding appropriate amounts of 2,2'-{[2,5-bis(chloromethyl)-1,4-phenylene]bis(oxy)}diethanol as the co-monomer and KtBuO as the base. The resulting PPV⊂mpSiO(2) was characterized by XRD, SEM, TEM, FTIR spectroscopy, and magic angle spinning (29) Si NMR spectroscopy; all spectroscopic data were in agreement with the presence of a conducting polymer. The resulting PPV⊂mpSiO(2) material exhibits electrical conductivity, particularly after I(2) doping, an electrochemical response, and electroluminescence. Laser flash photolysis studies of PPV⊂mpSiO(2) indicate that this material can form PPV(·+) polarons that could be responsible for the electrochemical and electroluminescent response.

Preparation of graphene quantum dots from pyrolyzed alginate.

Pyrolysis at 900 °C under an inert atmosphere of alginate, a natural widely available biopolymer, renders a graphitic carbon that upon ablation by exposure to a pulsed 532 nm laser (7 ns, 50 mJ pulse(-1)) in acetonitrile, water, and other solvents leads to the formation of multilayer graphitic quantum dots. The dimensions and the number of layers of these graphitic nanoparticles decrease along the number of laser pulses from 100 to 10 nm average and from multiple layers to few layers graphene (1-1.5 nm thickness), respectively, leading to graphene quantum dots (GQDs). Accordingly, the emission intensity of these GQDs increases appearing at about 500 nm in the visible region along the reduction of the particle size. Transient absorption spectroscopy has allowed detection of a transient signal decaying in the microsecond time scale that has been attributed to the charge separation state.

Scanning Photocurrent Microscopy in Single Crystal Multidimensional Hybrid Lead Bromide Perovskites.

We investigated solution-grown single crystals of multidimensional 2D-3D hybrid lead bromide perovskites using spatially resolved photocurrent and photoluminescence. Scanning photocurrent microscopy (SPCM) measurements where the electrodes consisted of a dip probe contact and a back contact. The crystals revealed significant differences between 3D and multidimensional 2D-3D perovskites under biased detection, not only in terms of photocarrier decay length values but also in the spatial dynamics across the crystal. In general, the photocurrent maps indicate that the closer the border proximity, the shorter the effective decay length, thus suggesting a determinant role of the border recombination centers in monocrystalline samples. In this case, multidimensional 2D-3D perovskites exhibited a simple fitting model consisting of a single exponential, while 3D perovskites demonstrated two distinct charge carrier migration dynamics within the crystal: fast and slow. Although the first one matches that of the 2D-3D perovskite, the long decay of the 3D sample exhibits a value two orders of magnitude larger. This difference could be attributed to the presence of interlayer screening and a larger exciton binding energy of the multidimensional 2D-3D perovskites with respect to their 3D counterparts.

Optoelectronic properties of octahedral molybdenum cluster-based materials at a single crystal level.

Octahedral molybdenum (Mo6) clusters constitute suitable building blocks for the design of promising single crystal materials in the field of optoelectronics. Here, we prepared single crystals composed of hydroxo Mo6X8 (X = Br, Cl) cluster complexes interconnected by H-bonding interactions with water molecules and protons. The optoelectronic responses and the absorption and emission spectra of these cluster-based single crystals were acquired upon light irradiation, and they show dependency on the nature of the halogens, with the brominated cluster being the most conductive. A fast photoelectrical response was recorded and it showed remarkable stability after multiple illumination on/off cycles. The results obtained provide relevant information for the development of photonic and optoelectronic devices, sensors and photocatalysts.

Photochemical evidence of electronic interwall communication in double-wall carbon nanotubes.

Single- and double-wall carbon nanotubes (CNTs) having dimethylanilino (DMA) units covalently attached to the external graphene wall have been prepared by the reaction of the dimethylaminophenylnitronium ion with the corresponding CNT. The samples have been characterized by Raman and XPS spectroscopies, thermogravimetry, and high-resolution transmission electron microscopy in which the integrity of the single or double wall of the CNT and the percentage of substitution (one dimethylanilino group every 45 carbons of the wall for the single- and double-wall samples) has been determined. Nanosecond laser flash photolysis has shown the generation of transients that has been derived from the charge transfer between the dimethylanilino (as the electron donor) to the CNT graphene wall (as the electron acceptor). Importantly, the lifetime of the double-wall CNT is much shorter than that monitored for the single-wall CNT. Shorter-lived transients were also observed for the pentyl-esterified functionalized double-wall CNT with respect to the single-wall analogue in the presence of hole (CH(3)OH) and electron quenchers (O(2), N(2)O), which has led to the conclusion that the inner, intact graphene wall that is present in double-wall CNT increases the charge mobility significantly, favoring charge recombination processes. Considering the importance that charge mobility has in microelectronics, our finding suggests that double-wall CNT or two-layer graphene may be more appropriate to develop devices needing fast charge mobility.

Unraveling the Gas-Sensing Mechanisms of Lead-Free Perovskites Supported on Graphene.

Lead halide perovskites have been attracting great attention due to their outstanding properties and have been utilized for a wide variety of applications. However, the high toxicity of lead promotes an urgent and necessary search for alternative nanomaterials. In this perspective, the emerging lead-free perovskites are an environmentally friendly and harmless option. The present work reports for the first time gas sensors based on lead-free perovskite nanocrystals supported on graphene, which acts as a transducing element owing to its high and efficient carrier transport properties. The use of nanocrystals enables achieving excellent sensitivity toward gas compounds and presents better properties than those of bulky perovskite thin films, owing to their quantum confinement effect and exciton binding energy. Specifically, an industrially scalable, facile, and inexpensive synthesis is proposed to support two different perovskites (Cs3CuBr5 and Cs2AgBiBr6) on graphene for effectively detecting a variety of harmful pollutants below the threshold limit values. H2 and H2S gases were detected for the first time by utilizing lead-free perovskites, and ultrasensitive detection of NO2 was also achieved at room temperature. In addition, the band-gap type, defect tolerance, and electronic surface traps at the nanocrystals were studied in detail for understanding the differences in the sensing performance observed. Finally, a comprehensive sensing mechanism is proposed.