Noise thermometry applied to thermoelectric measurements in InAs nanowires

We apply noise thermometry to characterize charge and thermoelectric transport in single InAs nanowires (NWs) at a bath temperature of 4.2 K. Shot noise measurements identify elastic diffusive transport in our NWs with negligible electron-phonon interaction. This enables us to set up a measurement of the diffusion thermopower. Unlike in previous approaches, we make use of a primary electronic noise thermometry to calibrate a thermal bias across the NW. In particular, this enables us to apply a contact heating scheme, which is much more efficient in creating the thermal bias as compared to conventional substrate heating. The measured thermoelectric Seebeck coefficient exhibits strong mesoscopic fluctuations in dependence on the back-gate voltage that is used to tune the NW carrier density. We analyze the transport and thermoelectric data in terms of approximate Mott's thermopower relation and to evaluate a gate-voltage to Fermi energy conversion factor

Local noise in a diffusive conductor

The control and measurement of local non-equilibrium configurations is of utmost importance in applications on energy harvesting, thermoelectrics and heat management in nano-electronics. This challenging task can be achieved with the help of various local probes, prominent examples including superconducting or quantum dot based tunnel junctions, classical and quantum resistors, and Raman thermography. Beyond time-averaged properties, valuable information can also be gained from spontaneous fluctuations of current (noise). From these perspective, however, a fundamental constraint is set by current conservation, which makes noise a characteristic of the whole conductor, rather than some part of it. Here we demonstrate how to remove this obstacle and pick up a local noise temperature of a current biased diffusive conductor with the help of a miniature noise probe. This approach is virtually noninvasive and extends primary local measurements towards strongly non-equilibrium regimes.Comment: minor revision, accepted in Scientific Report

Robotic versus laparoscopic left colectomy: a systematic review and meta-analysis

Background: This study aimed to review the new evidence to understand whether the robotic approach could find some clear indication also in left colectomy. Methods: A systematic review of studies published from 2004 to 2022 in the Web of Science, PubMed, and Scopus databases and comparing laparoscopic (LLC) and robotic left colectomy (RLC) was performed. All comparative studies evaluating robotic left colectomy (RLC) versus laparoscopic (LLC) left colectomy with at least 20 patients in the robotic arm were included. Abstract, editorials, and reviews were excluded. The Newcastle–Ottawa Scale for cohort studies was used to assess the methodological quality. The random-effect model was used to calculate pooled effect estimates. Results: Among the 139 articles identified, 11 were eligible, with a total of 52,589 patients (RLC, n = 13,506 versus LLC, n = 39,083). The rate of conversion to open surgery was lower for robotic procedures (RR 0.5, 0.5–0.6; p < 0.001). Operative time was longer for the robotic procedures in the pooled analysis (WMD 39.1, 17.3–60.9, p = 0.002). Overall complications (RR 0.9, 0.8–0.9, p < 0.001), anastomotic leaks (RR 0.7, 0.7–0.8; p < 0.001), and superficial wound infection (RR 3.1, 2.8–3.4; p < 0.001) were less common after RLC. There were no significant differences in mortality (RR 1.1; 0.8–1.6, p = 0.124). There were no differences between RLC and LLC with regards to postoperative variables in the subgroup analysis on malignancies. Conclusions: Robotic left colectomy requires less conversion to open surgery than the standard laparoscopic approach. Postoperative morbidity rates seemed to be lower during RLC, but this was not confirmed in the procedures performed for malignancies

Morphology control of single-crystal InSb nanostructures by tuning the growth parameters

Research interest in indium antimonide (InSb) has increased significantly in recent years owing to its intrinsic properties and the consequent opportunities to implement next-generation quantum devices. Hence, the precise, reproducible control over morphology and crystalline quality becomes of paramount importance for a practical quantum-device technology. Here, we investigate the growth of InSb nanostructures with different morphologies on InAs stems without pre-growth efforts (patterning). InSb nanostructures such as nanowires (1D), nanoflags (2D) and nanocubes (3D) have been realized by means of Au-assisted chemical beam epitaxy by tailoring the growth parameters like growth temperature, precursor fluxes, sample rotation and substrate orientation. Through morphological and crystallographic characterization, all the as-grown InSb 2D nanostructures are found to be single-crystalline with zinc blende structure, free from any defects such as stacking faults and twin planes. The existence of two families of 2D nanostructures, characterised by an aperture angle at the base of 145 and 160 , is observed and modelled. This study provides useful guidelines for the controlled growth of high-quality InSb nanostructures with different shape

A heterotrimeric G protein, G alpha i-3, on Golgi membranes regulates the secretion of a heparan sulfate proteoglycan in LLC-PK1 epithelial cells

A heterotrimeric G-alpha-i subunit, alpha-i-3, is localized on Golgi membranes in LLC-PK1 and NRK epithelial cells where it colocalizes with mannosidase II by immunofluorescence. The alpha-i-3 was found to be localized on the cytoplasmic face of Golgi cisternae and it was distributed across the whole Golgi stack. The alpha-i-3 subunit is found on isolated rat liver Golgi membranes by Western blotting and G-alpha-i-3 on the Golgi apparatus is ADP ribosylated by pertussis toxin. LLC-PK1 cells were stably transfected with G-alpha-i-3 on an MT-1, inducible promoter in order to overexpress alpha-i-3 on Golgi membranes. The intracellular processing and constitutive secretion of the basement membrane heparan sulfate proteoglycan (HSPG) was measured in LLC-PK1 cells. Overexpression of alpha-i-3 on Golgi membranes in transfected cells retarded the secretion of HSPG and accumulated precursors in the medial-trans-Golgi. This effect was reversed by treatment of cells with pertussis toxin which results in ADP-ribosylation and functional uncoupling of G-alpha-i-3 on Golgi membranes. These results provide evidence for a novel role for the pertussis toxin sensitive G-alpha-i-3 protein in Golgi trafficking of a constitutively secreted protein in epithelial cells

Near-Field microscopy with phase sensitive coherent detection employing quantum cascade lasers

We demonstrate a novel architecture for a THz near-field probe, which enables coherent imaging with subwavelength spatial resolution using THz quantum cascade lasers. An InAs nanowire acting as a THz detector based on the field effect transistor concept is integrated inside a subwavelength input aperture of the near-field probe to detect intensity of the THz field and its phase. To determine the phase locally, the THz field is superimposed on the reference THz field incident on the aperture of the probe from the back side. In this configuration, the THz detector exhibits coherent gain and sensitivity to the relative phase between the local and the reference THz fields

InAs/InP/InSb Nanowires as Low Capacitance n-n Heterojunction Diodes

Nanowire diodes have been realized by employing an axial heterojunction between InAs and InSb semiconductor materials. The broken-gap band alignment (type III) leads to a strong rectification effect when the current-voltage (I-V) characteristic is inspected at room temperature. The additional insertion of a narrow InP barrier reduces the thermionic contribution, which results in a net decrease of leakage current in the reverse bias with a corresponding enhanced rectification in terms of asymmetry in the I-V characteristics. The investigated diodes compare favorably with the ones realized with p-n heterostructured nanowires, making InAs/InP/InSb devices appealing candidates to be used as building blocks for nanowire-based ultrafast electronics and for the realization of photodetectors in the THz spectral range

Conversion Surgery in Gastric Cancer Carcinomatosis

Background: After the REGATTA trial, patients with stage IV gastric cancer could only benefit from chemotherapy (CHT). However, some of these patients may respond extraordinarily to palliative chemotherapy, converting their disease to a radically operable stage. We present a single centre experience in treating peritoneal carcinomatosis from gastric cancer. Methods: All patients with stage IV gastric cancer with peritoneal metastases as a single metastatic site operated at a single centre between 2005 and 2020 were included. Cases were grouped according to the treatment received. Results: A total of 118 patients were considered, 46 were submitted to palliative gastrectomy (11 were considered M1 because of an unsuspected positive peritoneal cytology), and 20 were submitted to Hyperthermic Intraperitoneal Chemotherapy (HIPEC) because of a <6 Peritoneal Cancer Index (PCI). The median overall survival (OS) after surgery plus HIPEC was 46.7 (95% CI 15.8–64.0). Surgery (without HIPEC) after CHT presented a median OS 14.4 (8.2–26.8) and after upfront surgery 14.7 (10.9–21.1). Patients treated with upfront surgery and considered M1 only because of a positive cytology, had a median OS of 29.2 (25.2–29.2). The OS of patients treated with surgery plus HIPEC were 60.4 months (9.2–60.4) in completely regressed cancer after chemotherapy and 31.2 (15.8–64.0) in those partially regressed (p = 0.742). Conclusions: Conversion surgery for peritoneal carcinomatosis from gastric cancer was associated with long survival and it should always be taken into consideration in this group of patients