Quantum dots formed in three-dimensional Dirac semimetal Cd3_3As2_2 nanowires

We demonstrate quantum dot (QD) formation in three-dimensional Dirac semimetal Cd$_{3}$As$_{2}$ nanowires using two electrostatically tuned p$-$n junctions with a gate and magnetic fields. The linear conductance measured as a function of gate voltage under high magnetic fields is strongly suppressed at the Dirac point close to zero conductance, showing strong conductance oscillations. Remarkably, in this regime, the Cd$_{3}$As$_{2}$ nanowire device exhibits Coulomb diamond features, indicating that a clean single QD forms in the Dirac semimetal nanowire. Our results show that a p$-$type QD can be formed between two n$-$type leads underneath metal contacts in the nanowire by applying gate voltages under strong magnetic fields. Analysis of the quantum confinement in the gapless band structure confirms that p$-$n junctions formed between the p$-$type QD and two neighboring n$-$type leads under high magnetic fields behave as resistive tunnel barriers due to cyclotron motion, resulting in the suppression of Klein tunneling. The p$-$type QD with magnetic field-induced confinement shows a single hole filling. Our results will open up a route to quantum devices such as QDs or quantum point contacts based on Dirac and Weyl semimetals

Separating Beads and Cells in Multi-channel Microfluidic Devices Using Dielectrophoresis and Laminar Flow

Microfluidic devices have advanced cell studies by providing a dynamic fluidic environment on the scale of the cell for studying, manipulating, sorting and counting cells. However, manipulating the cell within the fluidic domain remains a challenge and requires complicated fabrication protocols for forming valves and electrodes, or demands specialty equipment like optical tweezers. Here, we demonstrate that conventional printed circuit boards (PCB) can be used for the non-contact manipulation of cells by employing dielectrophoresis (DEP) for bead and cell manipulation in laminar flow fields for bioactuation, and for cell and bead separation in multichannel microfluidic devices. First, we present the protocol for assembling the DEP electrodes and microfluidic devices, and preparing the cells for DEP. Then, we characterize the DEP operation with polystyrene beads. Lastly, we show representative results of bead and cell separation in a multichannel microfluidic device. In summary, DEP is an effective method for manipulating particles (beads or cells) within microfluidic devices

\u27Living cantilever arrays\u27 for characterization of mass of single live cells in fluids

The size of a cell is a fundamental physiological property and is closely regulated by various environmental and genetic factors. Optical or confocal microscopy can be used to measure the dimensions of adherent cells, and Coulter counter or flow cytometry ( forward scattering light intensity) can be used to estimate the volume of single cells in a flow. Although these methods could be used to obtain the mass of single live cells, no method suitable for directly measuring the mass of single adherent cells without detaching them from the surface is currently available. We report the design, fabrication, and testing of \u27living cantilever arrays\u27, an approach to measure the mass of single adherent live cells in fluid using silicon cantilever mass sensor. HeLa cells were injected into microfluidic channels with a linear array of functionalized silicon cantilevers and the cells were subsequently captured on the cantilevers with positive dielectrophoresis. The captured cells were then cultured on the cantilevers in a microfluidic environment and the resonant frequencies of the cantilevers were measured. The mass of a single HeLa cell was extracted from the resonance frequency shift of the cantilever and was found to be close to the mass value calculated from the cell density from the literature and the cell volume obtained from confocal microscopy. This approach can provide a new method for mass measurement of a single adherent cell in its physiological condition in a non-invasive manner, as well as optical observations of the same cell. We believe this technology would be very valuable for single cell time-course studies of adherent live cells

Radiographic and computed tomographic evaluation of experimentally induced lung aspiration sites in dogs

This study was performed to radiographically examine the prevalence of aspiration sites and to evaluate their atomical correlation with the bronchial pattens. Ten healthy beagle dogs were repeatedly radiographed, at weekly intervals, in the left and right lateral, ventrodorsal (VD) and dorsoventral (DV) positions. Three mililiters of iohexol distilled with same volume of saline was infused into the tracheal inlet. Which lung lobe was aspirated was decided upon by the presence of a significant alveolar pattern due to the contrast medium. Alveolar patterns were identified at the left (100%) and right cranial lung lobes (77%) with the dogs in dependant lateral recumbency, at the right caudal lung lobe (71%) with the dogs in VD recumbency and at the right middle lung lobe (59%) with the dogs in DV recumbency, respectively. The anatomical correlation was evaluated by performing computed tomography. The right principal bronchus (165.8 ± 1.6°) was more straightly bifurcated than was the left principal bronchus (142.7 ± 1.8°, p < 0.01). In VD position, the right side lung had a greater opertunity to become aspirated. The ventrally positioned right middle lobar bronchial origin was more easily to be aspirated the other laterally positioned ones. We think that these anatomical characteristics can be one of the causes for aspiration pneumonia to occur more frequently in the right side lung

Saponin Inhibits Hepatitis C Virus Propagation by Up-regulating Suppressor of Cytokine Signaling 2

Saponins are a group of naturally occurring plant glycosides which possess a wide range of pharmacological properties, including anti-tumorigenic and antiviral activities. To investigate whether saponin has anti-hepatitis C virus (HCV) activity, we examined the effect of saponin on HCV replication. HCV replication was efficiently inhibited at a concentration of 10 µg/ml of saponin in cell culture grown HCV (HCVcc)-infected cells. Inhibitory effect of saponin on HCV replication was verified by quantitative real-time PCR, reporter assay, and immunoblot analysis. In addition, saponin potentiated IFN-α-induced anti-HCV activity. Moreover, saponin exerted antiviral activity even in IFN-α resistant mutant HCVcc-infected cells. To investigate how cellular genes were regulated by saponin, we performed microarray analysis using HCVcc-infected cells. We demonstrated that suppressor of cytokine signaling 2 (SOCS2) protein level was distinctively increased by saponin, which in turn resulted in inhibition of HCV replication. We further showed that silencing of SOCS2 resurrected HCV replication and overexpression of SOCS2 suppressed HCV replication. These data imply that saponin inhibits HCV replication via SOCS2 signaling pathway. These findings suggest that saponin may be a potent therapeutic agent for HCV patients

Value of Second Pass in Loop Electrosurgical Excisional Procedure

The aim of this study was to compare the rate of incomplete resection and treatment outcome of the second-pass technique with those of single-pass technique in loop electrosurgical excisional procedure (LEEP). From 1997 to 2002, 683 women were diagnosed as squamous dysplasia via LEEP in our institution. Age, parity, LEEP technique, grade of lesion, glandular extension, margin status, residual tumor and recurrence were obtained by reviewing medical records. Positive margin was defined as mild dysplasia or higher grade lesions at resection margin of the LEEP specimen. In women who underwent hysterectomy, residual tumor was defined as mild dysplasia or higher grade lesions in hysterectomy specimen. In women who did not underwent hysterectomy, Pap smear more than atypical squamous cells of undetermined significance or biopsy result more than mild dysplasia within two years after LEEP were regarded as cytologic or histologic recurrences, respectively. Treatment failure of LEEP was defined as residual tumor or histologic recurrence. The second-pass technique significantly reduced the endocervical margin positivity (odds ratio [OR], 0.36; 95% confidence interval [CI], 0.21-0.63). However, the second-pass technique did not reduce the treatment failure (OR, 0.62; 95% CI, 0.29-1.32). In conclusion, the second-pass technique markedly reduced the endocervical margin positivity, but did not reduce the treatment failure rate of LEEP

Detection of Recurrence by 18F-FDG PET in Patients with Endometrial Cancer Showing No Evidence of Disease

This study assessed the feasibility of F-18-fluorodeoxyglucose positron-emission tomography (18F-FDG PET) in the post-therapy surveillance for patients with endometrial cancer showing no evidence of disease (NED). From April 1997 to June 2007, 127 patients with endometrial cancer showing NED were performed 18F-FDG PET scan. The feasibility of 18F-FDG PET for the early detection of recurrence in patients with endometrial cancer was evaluated retrospectively. Of the 127 patients, 32 patients showed positive lesions on 18F-FDG PET scan. Nineteen (19/127 cases, 15%) of them were confirmed to have a recurrence clinically or histologically. The sensitivity, specificity and positive and negative predictive value of 18F-FDG PET for detecting recurrences in patients with endometrial cancer were 100%, 88%, 59% and 100%, respectively. In conclusion, 18F-FDG PET may be a useful method for the post-therapy surveillance in patients with endometrial cancer

Acceptability and Usability of HCV Self-Testing in High Risk Populations in Vietnam.

HIV self-testing has emerged as a safe and effective approach to increase the access to and uptake of HIV testing and treatment, especially for key populations. Applying self-testing to hepatitis C virus (HCV) may also offer an additional way to address low coverage of HCV testing and to accelerate elimination efforts. To understand the potential for HCV self-testing (HCVST), an observational study was conducted to assess the acceptability and usability of the OraQuick® HCV Self-Test (prototype) among people who inject drugs (PWID) and men who have sex with men (MSM) in Thai Nguyen, a province in northern Vietnam. A total of 105 PWID and 104 MSM were eligible and agreed to participate in the study. Acceptability, defined as the proportion of participants among eligible subjects who agreed to participate in the study, was 92.9% in PWID and 98.6% in MSM. Compared to MSM, PWID were older (median age: 45 vs. 22 years; p < 0.0001) and had a lower education level (high school and college: 38.1% vs. 100%; p < 0.0001). HCVST usability was high among MSM with fewer observed mistakes, difficulties, or participants requiring assistance (33.7%, 28.8%, and 17.3%, respectively) compared to PWID (62.9%, 53.3%, and 66.7%, respectively; all p < 0.0001)). Inter-reader and inter-operator agreement were good in both groups (Kappa coefficient range: 0.61-0.99). However, the concordance between HCVST and study staff -read or performed HCV testing was lower among PWID than MSM (inter-reader concordance 88.6% vs. 99.0% and inter-operator concordance 81.9% vs. 99%). Overall, HCVST was highly acceptable with moderate to high usability among PWID and MSM in Thai Nguyen. Efforts to provide support and assistance may be needed to optimize performance, particularly for PWID populations and for those who are older and with lower literacy or education levels

Integrating maternal, newborn, child health and non-communicable disease care in the sustainable development goal era

Noncommunicable diseases (NCDs) and maternal newborn and child health (MNCH) are two deeply intertwined health areas that have been artificially separated by global health policies, resource allocations and programming. Optimal MNCH care can provide a unique opportunity to screen for, prevent and manage early signs of NCDs developing in both the woman and the neonate. This paper considers how NCDs, NCD modifiable risk factors, and NCD metabolic risk factors impact MNCH. We argue that integrated management is essential, but this faces challenges that manifest across all levels of domestic health systems. Progress toward Sustainable Development targets requires joined-up action

Micromachined electromechanical devices for analysis and characterization of a biological entity on a single cell level

With the advent of the MEMS technology, various new possibilities have arisen in the analysis of biological entities. One of the new possibilities is the ability to analyze the heterogeneity of the target entities due to the ability to do measurements at the level of single entities. Typically, the target entities are usually processed and analyzed in large number especially in the field of microbiology, ignoring the heterogeneity of the sample population. MEMS technology can provide versatile tools for manipulating, processing and analyzing a few or single particles, enabling detailed analysis on the physiology and the metabolism of individual entities. The new approach based on MEMS technology can lead us into numerous valuable findings on the physiology and the metabolism of the target entities. In this work, various techniques and devices aimed for a few or single cell analysis of the biological entities were developed, which could be potentially integrated in a single Lab on Chip (LOC) system. A dielectrophoresis (DEP)-based capture and reagentless electrical lysis was implemented on a nano-probe array, which could capture a small number of particles in a fluid with DEP induced by a nano-scale sharp probe and then lyse the particles with a strong electric field generated by the same probe. The DEP-based capture and the electrical lysis of vaccinia virus were demonstrated. For extending the principle of DEP particle manipulation into a real application, a DEP particle manipulation apparatus was developed based on a custom-made printed circuit board without any cleanroom processes. This apparatus can provide a low cost mass-producible platform to implement a DEP particle manipulation in a lab-on-chip system. Finally, and most importantly, for the analysis of a single live cell in fluid, a MEMS-based resonant mass sensor was developed. In one version of this device, the cells were captured in fluid with DEP on a cantilever array and the resonant frequency shift of a cantilever with a single cell was measured to calculate the mass of the cell attached to each cantilever. In a second and significantly improved version of this device, a novel resonant mass sensor with a uniform mass sensitivity was designed and fabricated to overcome the non-uniformity of mass sensitivity of traditional rectangular shaped cantilever-based resonant mass sensors. A new resonant frequency measurement technique with electromagnetic actuation was developed for more precision mass measurement and the mass of HeLa cells was measured using these mass sensors