Atomic resolution interface structure and vertical current injection in highly uniform MoS2MoS_{2} heterojunctions with bulk GaN

The integration of two-dimensional $MoS_{2}$ with $GaN$ recently attracted significant interest for future electronic/optoelectronic applications. However, the reported studies have been mainly carried out using heteroepitaxial $GaN$ templates on sapphire substrates, whereas the growth of $MoS_{2}$ on low-dislocation-density bulk GaN can be strategic for the realization of truly vertical devices. In this paper, we report the growth of ultrathin $MoS_{2}$ films, mostly composed by single-layers ($1L$), onto homoepitaxial $n-GaN$ on $n^{+}$ bulk substrates by sulfurization of a pre-deposited $MoO_{x}$ film. Highly uniform and conformal coverage of the $GaN$ surface was demonstrated by atomic force microscopy, while very low tensile strain (0.05%) and a significant $p^{+}$-type doping ($4.5 \times 10^{12} cm^{-2}$) of $1L-MoS_{2}$ was evaluated by Raman mapping. Atomic resolution structural and compositional analyses by aberration-corrected electron microscopy revealed a nearly-ideal van der Waals interface between $MoS_{2}$ and the $Ga$-terminated $GaN$ crystal, where only the topmost $Ga$ atoms are affected by oxidation. Furthermore, the relevant lattice parameters of the $MoS_{2}/GaN$ heterojunction, such as the van der Waals gap, were measured with high precision. Finally, the vertical current injection across this 2D/3D heterojunction has been investigated by nanoscale current-voltage analyses performed by conductive atomic force microscopy, showing a rectifying behavior with an average turn-on voltage $V_{on}=1.7 V$ under forward bias, consistent with the expected band alignment at the interface between $p^{+}$ doped $1L-MoS_{2}$ and $n-GaN$.Comment: 21 pages, 6 figure

L’emangioma capillare dello stomaco: una rara fonte di sanguinamento. Caso clinico

Gastric haemorrhages are common clinical emergencies which often directly involve the surgeon in diagnosis and treatment; among these, rare vascular neoplasms deserve particular attention. The Authors report a rare case of benign vascular tumour of the stomach, a capillary angioma. After a literature review they highlight the importance of specific exams to reveal these small neoformations which, generally, show up clinically with acute bleeding, which may be severe, and which may not be discovered if the clinical evaluation is not very detailed. The surgical excision supported by a frozen sections is the most effective treatmen

Il trattamento endoscopico protesico delle fistole anastomotiche esofago-digiunali dopo gastrectomia totale per cancro dello stomaco: esperienza clinica

Gli Autori, alla luce della loro esperienza sull’utilizzo delle protesi autoespandibili in chirurgia addominale, riferiscono sul loro impiego in due pazienti che, operati di gastrectomia per cancro, presentavano una fistola dell’anastomosi esofago-digiunale. Alla luce dei dati più recenti della letteratura, la protesizzazione di una fistola anastomotica può a volte rappresentare una valida alternativa ad un reintervento che, oltre alla evidente difficoltà, comporta sempre un alto indice di mortalità in soggetti già in condizioni generali scadenti. In tali casi infatti, dopo l’applicazione dello stent, si ottiene un vero successo funzionale e dopo alcuni giorni il paziente può iniziare una dieta semiliquida, per passare successivamente a quella semisolida, con miglioramento della qualità di vita; inoltre, in un arco di tempo accettabile, dopo la guarigione della fistola, la protesi può essere rimossa facilmente per via endoscopic

Low-temperature atomic layer deposition of TiO2 activated by laser annealing: Applications in photocatalysis

This work reports an innovative method to obtain anatase TiO2 films on polymeric substrate. The low temperature atomic layer deposition (LT-ALD) of TiO2 on polymeric substrate was combined with the laser irradiation. TiO2 amorphous films were deposited by LT-ALD on polyethylene naphthalene (PEN) substrate at a temperature of 90 C. Successively, a KrF excimer laser was used for the annealing of the TiO2 films. The laser annealing induced the crystallization of the films in the form of anatase. A detailed morphological, structural, and chemical characterization was performed by ellipsometry, scanning electron microscopy (SEM), Raman spectroscopy, and transmission electron microscopy (TEM). The photocatalytic aptitude of the investigated films was demonstrated by the degradation of the methylene blue (MB) dye in aqueous solution under UV light irradiation. Simulations of the temperature depth profiles as a function of the time during the laser processes were performed. The results demonstrate that the matching of the extremely low temperature growth by ALD with the laser irradiation allows to synthetize anatase TiO2 films on flexible substrate that could find applications in photocatalysis, especially for wastewater remediation

Trattamento degli eventi perforativi post-colangiopancreatografia retrograda con sfinterotomia endoscopica. Esperienza personale

Trattamento degli eventi perforativi post-colangio­pancreatografia retrograda con sfinterotomia endoscopica. Esperienza personale. L.G. Angiò, G. Sfuncia, P. Viggiani, G. Faro, A. Bonsignore, M. Licursi, M. Soliera, M. Galati, A. Putortì Introduzione. La colangiopancreatografia retrograda endoscopica (CPRE) ha apportato reali progressi nella gestione delle patologie bilio-pancreatiche, in virtù della sua ambivalenza diagnostica e terapeutica. Le sue complicanze perforative insorgono in meno dell’1% dei pazienti, ma sono associate a una mortalità del 16%-18%. Casistica personale. Caso 1- F, 89 anni con ittero ostruttivo da calcolosi della via biliare principale (VBP) sottoposta a CPRE con sfinterotomia endoscopica (SE), nel corso della quale si verifica lesione tipo II per cui, vista la parziale bonifica della VBP ottenuta, si opta per un trattamento conservativo, con risoluzione in XII giornata post-CPRE. Caso 2- F, 53 anni con colangiti recidivanti e stenosi post-colecistectomia della VBP già trattata mediante stenting; per il verificarsi di lesione tipo I in corso di CPRE, si sottopone la paziente a intervento chirurgico in urgenza/emergenza con guarigione in XXIII giornata. Caso 3- M, 84 anni con colecistite litiasica, ittero ostruttivo, enfisema polmonare e cardiopatia ischemica; eseguita colecistostomia percutanea in urgenza, si procede successivamente a tentativo di CPRE con evidenza di lesione tipo I e, a causa delle comorbilità, si opta per un trattamento conservativo, non risolutivo, per poi procedere all’intervento chirurgico con exitus per complicanze cardio-respiratorie. Caso 4- M, 89 anni con ittero ostruttivo di ndd; interrotta la CPRE per complicanze respiratorie, si procede a colangiografia transeptica per cutanea (CTP) nel corso della quale si evidenzia una lesione tipo IV, che è trattata conservativamente con dimissione in XII giornata. Caso 5- F, 68 anni con colecistite litiasica e coledocolitiasi; in corso di CPRE con SE si verifica lesione tipo II con segni ingravescenti di addome acuto e, in considerazione del quadro clinico e dell’impossibilità di effettuare bonifica endoscopica della VBP, si dispone l’intervento chirurgico in urgenza/emergenza con exitus per complicanze respiratorie. Discussione. Nella diatriba esistente su quale debba essere il trattamento degli eventi perforativi post-CPRE con SE (intervento chirurgico immediato ovvero terapia conservativa), non possiamo non auspicare un atteggiamento eclettico sulla base delle peculiarità anatomo-cliniche del singolo caso

Site-specific halloysite functionalization by polydopamine: A new synthetic route for potential near infrared-activated delivery system

Halloysite nanotubes (HNTs) represent a versatile core structure for the design of functional nanosystems of biomedical interest. However, the development of selective methodologies for the site-controlled functionalization of the nanotubes at specific sites is not an easy task. This study aims to accomplish a procedure for the site-selective/specific, “pin-point”, functionalization of HNTs with polydopamine (HNTs@PDA). This goal was achieved, at pH 6.5, by exploiting the basicity of ZnO nanoparticles anchored on the HNTs external surface (HNTs@ZnO) to induce a punctual polydopamine polymerization and coating. The morphology and the chemical composition of the nanomaterial was demonstrated by several techniques. Turbidimetric analysis showed that PDA coating affected the aqueous stability of HNTs@PDA compared to both HNTs@ZnO and HNTs. Notably, hyperthermia studies revealed that the nanomaterial induced a local thermic rise, up to 50 °C, under near-infrared (NIR) irradiation. Furthermore, secondary functionalization of HNTs@PDA by selective grafting of biotin onto the PDA coating followed by avidin binding was also accomplished

Atomic resolution interface structure and vertical current injection in highly uniform MoS2 heterojunctions with bulk GaN

The integration of two-dimensional MoS2 with GaN recently attracted significant interest for future electronic/optoelectronic applications. However, the reported studies have been mainly carried out using heteroepitaxial GaN templates on sapphire substrates, whereas the growth of MoS2 on low-dislocation-density bulk GaN can be strategic for the realization of “truly” vertical devices. In this paper, we report the growth of ultrathin MoS2 films, mostly composed by single-layers (1L), onto homoepitaxial n−-GaN on n+ bulk substrates by sulfurization of a pre-deposited MoOx film. Highly uniform and conformal coverage of the GaN surface was demonstrated by atomic force microscopy, while very low tensile strain (∼0.05%) and a significant p+-type doping (∼4.5 × 1012 cm−2) of 1L-MoS2 was evaluated by Raman mapping. Atomic resolution structural and compositional analyses by aberration-corrected electron microscopy revealed a nearly-ideal van der Waals interface between MoS2 and the Ga-terminated GaN crystal, where only the topmost Ga atoms are affected by oxidation. Furthermore, the relevant lattice parameters of the MoS2/GaN heterojunction, such as the van der Waals gap, were measured with high precision. Finally, the vertical current injection across this 2D/3D heterojunction has been investigated by nanoscale current-voltage analyses performed by conductive atomic force microscopy, showing a rectifying behavior with an average turn-on voltage Von = 1.7 V under forward bias, consistent with the expected band alignment at the interface between p+ doped 1L-MoS2 and n-GaN

Tuning the Composition of Alloy Nanoparticles Through Laser Mixing: The Role of Surface Plasmon Resonance

In this work we report a technique for the preparation of Au<i>_x</i>Ni_1–<i>_x</i> alloy nanoparticles based on pulsed laser irradiation in liquid of Au and Ni@NiO colloidal mixtures. The structural and compositional characterization of the obtained materials, performed through X-ray diffraction and transmission electron microscopy coupled with energy dispersive X-ray spectroscopy, has shown a correlation between the final alloy composition and the different Au to Ni@NiO ratio in the irradiated mixture. With the support of theoretical calculations, we propose as possible mechanism for the formation of the alloy structures a temperature increase, enhanced by the strong absorption of gold surface plasmon resonance at resonant wavelength, and a subsequent melting of the structures. Optical characterization through UV–vis spectroscopy and magnetic characterization through SQUID magnetometry confirm a coexistence of the plasmonic and magnetic behaviors in the hybrid systems. In view of such results, Au_<i>x</i>Ni_1–<i>x</i> alloy nanoparticles could be a promising base material for devices requiring both plasmonic and magnetic properties