Nonlinear electrical impedance spectroscopy of viruses using very high electric fields created by nanogap electrodes

Our living sphere is constantly exposed to a wide range of pathogenic viruses, which can be either known, or of novel origin. Currently, there is no methodology for continuously monitoring the environment for viruses in general, much less a methodology that allows the rapid and sensitive identification of a wide variety of viruses responsible for communicable diseases. Traditional approaches, based on PCR and immunodetection systems, only detect known or specifically targeted viruses. We here describe a simple device that can potentially detect any virus between nanogap electrodes using nonlinear impedance spectroscopy. Three test viruses, differing in shape and size, were used to demonstrate the general applicability of this approach: baculovirus，tobacco mosaic virus, and influenza virus. We show that each of the virus types responded differently in the nanogap to changes in the electric field strength, and the impedance of the virus solutions differed depending both on virus type and virus concentration. These preliminary results show that the three virus types can be distinguished and their approximate concentrations determined. Although further studies are required, the proposed nonlinear impedance spectroscopy method may achieve a sensitivity comparable to that of more traditional, but less versatile, virus detection systems

Transanal TME: new standard or fad?

Transanal total mesorectal excision (taTME) has been developed to overcome the difficulty of laparoscopic dissection and transection in the deep pelvis. TaTME has several clinical benefits over laparoscopic surgery, such as better exposure of the distal rectum and direct determination of distal resection margin. Although evidence demonstrating the true benefits of taTME over laparoscopic TME (LapTME) is still insufficient, accumulating data have revealed that, as compared with LapTME, taTME is associated with shorter operative time and a lower conversion rate without jeopardizing other short-term outcomes. However, taTME is a technically demanding procedure with specific complications such as urethral injury, and so sufficient experience of LapTME and step-by-step acquisition of the skills needed for this procedure are requisite. The role of transanal endoscopic surgery is expected to change, along with the recent progress in the treatment of rectal cancer, such as robotic surgery and the watch-and-wait strategy. Optimization of treatment will be needed in the future in terms not only of oncological but also of functional outcomes

Detection of carbon dioxide embolism by transesophageal echocardiography during transanal/perineal endoscopic surgery: a pilot study

Abstract The transanal/perineal (ta/tp) endoscopic approach has been widely used for anorectal surgery in recent years, but carbon dioxide embolism is a possible lethal complication. The frequency of this complication in this approach is not known. In this study, we investigated the frequency of intraoperative (including occult) carbon dioxide embolism using transesophageal echocardiography. Patients who underwent surgery via the ta/tp approach and consented to participate were included. Intraoperative transesophageal echocardiography was used to observe the right ventricular system in a four-chamber view. Changes in end-tidal carbon dioxide (EtCO2), oxygen saturation (SpO2), and blood pressure were taken from anesthesia records. Median maximum insufflation pressure during the ta/tp approach was 13.5 (12–18) mmHg. One patient (4.8%) was observed to have a bubble in the right atrium on intraoperative transesophageal echocardiography, with a decrease in EtCO2 from 39 to 35 mmHg but no obvious change in SpO2 or blood pressure. By lowering the insufflation pressure from 15 to 10 mmHg and controlling bleeding from the veins around the prostate, the gas rapidly disappeared and the operation could be continued. Among all patients, the range of variation in intraoperative EtCO2 was 5–22 mmHg, and an intraoperative decrease in EtCO2 of > 3 mmHg within 5 min was observed in 19 patients (median 5 mmHg in 1–10 times).Clinicians should be aware of carbon dioxide embolism as a rare but potentially lethal complication of anorectal surgery, especially when using the ta/tp approach

Electronic structure of self-doped layered Eu 3 F 4 Bi 2 S 4 material revealed by x-ray absorption spectroscopy and photoelectron spectromicroscopy

International audienceWe have studied the electronic structure of Eu 3 F 4 Bi 2 S 4 using a combination of Eu L 3-edge x-ray absorption spectroscopy (XAS) and space-resolved angle-resolved photoemission spectroscopy (ARPES). From the Eu L 3-edge XAS, we have found that the Eu in this system is in mixed valence state with coexistence of Eu 2+ /Eu 3+. The bulk charge doping was estimated to be ∼0.3 per Bi site in Eu 3 F 4 Bi 2 S 4 , which corresponds to the nominal x in a typical REO 1−x F x BiS 2 system (RE: rare-earth elements). From the space-resolved ARPES, we have ruled out the possibility of any microscale phase separation of Eu valence in the system. Using a microfocused beam we have observed the band structure as well as the Fermi surface that appeared similar to other compounds of this family with disconnected rectangular electronlike pockets around the X point. The Luttinger volume analysis gives the effective carrier to be 0.23 electrons per Bi site in Eu 3 F 4 Bi 2 S 4 , indicating that the system is likely to be in the underdoped region of its superconducting phase diagram. The BiS 2-based superconductors are composed of a layered structure with active BiS 2 bilayers intercalated by insulating spacer layers [1]. The typical BiS 2-based system REOBiS 2 (RE: rare-earth elements) is usually a band insulator, and the band filling can be controlled by electron doping; by substituting O by F [2] or tetravalent ions by trivalent La at RE site [3]. As the doping level increases, superconductivity develops within the BiS 2 layers with the maximum T c of 10.5 K found in LaO 0.5 F 0.5 BiS 2 [4]. The conduction bands are composed of Bi 6p x/y orbitals giving rise to rectangular electron pockets around the X point of the Brillouin zone [5,6]. With the same crystal structure, EuFBiS 2 shows super-conductivity without any doping. It is thought to be caused by the self-doped electrons coming from Eu that is in a mixed valence state with coexisting Eu 2+ and Eu 3+ [7]. A similar situation seems to occur in a new class of the BiS 2-based family Eu 3 F 4 Bi 2 S 4 system that is found to show bulk superconductivity with T c = 1.5 K induced by self-doping [8]. The structure is rather complex with an additional EuF 2 layer intercalated into the EuFBiS 2 structure as shown in Fig. 1(a). In this work we have studied the electronic structure of Eu 3 F 4 Bi 2 S 4 by means of Eu L 3-edge x-ray absorption spectroscopy (XAS) and space-resolved angle-resolved pho-toemission spectroscopy (ARPES); the Eu L 3-edge XAS is a bulk sensitive probe on the valence state while the space-resolved ARPES can reveal the space-dependent electronic structure, which is especially important on the present system with a mixed valence of Eu and highly disordered local symmetry [9-11]. High-quality single crystals of Eu 3 F 4 Bi 2 S 4 were grown by the CsCl-flux method with powders of EuS, Bi 2 S 3 , and BiF 3. The excess CsCl flux was removed using H 2 O. The crystals were well characterized for their crystal structures and transport properties prior to the spectroscopy measurements [12]. The Eu L 3-edge XAS measurements have been performed at BM30B beamline of the European Synchrotron Radiation Facility. At the BM30B, the synchrotron radiation was monochromatized by a double crystal Si(220) monochromator, and the energy resolution is close to the intrinsic resolution of the Si crystals, i.e., around 0.35 eV at the Eu L 3 edge [13]. Two Si mirrors covered by a Rh layer allow us to avoid high energy photons (harmonics). The Eu 3 F 4 Bi 2 S 4 crystals were mounted in a continuous flow He cryostat and XAS measurements were carried out in a partial fluorescence yield mode at a temperature of 21 K. The experimental geometry in sketched in the inset of Fig. 1(b) with the linearly polarized light falling at an angle of 33 • with respect to the normal direction of the sample. This angle avoids the polarization effects and provides the angle-independent bulk spectrum. The Eu L 3-edge absorption spectrum was collected by detecting the Eu L α1 fluorescence photons over a large solid angle using a multielement Ge detector. The obtained XAS spectrum was corrected for the self-absorption using the FLUO algorithm embedded in Athena software [14]. Space-resolved ARPES measurements have been performed at the Spectromicroscopy beamline, Elettra synchrotron facility, Trieste [15]. Incident photons of 74 eV were focused using a Schwarzschild optics down to a 500 × 500 nm 2 beam spot. For the present measurements the total energy resolution is about ∼100 meV while the angular resolution is 0.5 •. The single crystals of Eu 3 F 4 Bi 2 S 4 were cleaved and oriented in situ at 40 K under ultrahigh vacuum condition (<10 −10 mbar). All the measurements were carried 2469-9950/2017/95(3)/035152(5) 035152-