Real-time detection of an airborne microorganism using inertial impaction and mini-fluorescent microscopy

To achieve successful real-time detection of airborne pathogenic microorganisms, the problem must be considered in terms of their physical size and biological characteristics. We developed an airborne microorganism detection chip to realize the detection of microorganisms, ensuring compactness, sensitivity, cost-efficiency, and portability, using three key components: an inertial impaction system, a cartridge-type impaction plate, and a mini-fluorescent microscope. The inertial impaction system was used to separate microorganisms in terms of their aerodynamic particle size, and was fabricated with three impaction stages. Numerical analysis was performed to design the system; the calculated cutoff diameter at each impaction stage was 2.02 (first stage), 0.88 (second stage), and 0.54 μm (third stage). The measured cutoff diameters were 2.24, 0.91, and 0.49 μm, respectively. A cartridge-type impaction plate was used, composed of molded polydimethylsiloxane (PDMS) and an actual impaction region made of a SYBR green I dye-stained agar plate. A mini-fluorescent microscope was used to distinguish microbes from non-biological particles. Images of the microorganisms deposited at the impaction zone were obtained via mini-fluorescent microscopy, and fluorescent intensities of the images were calculated using in-house image-processing software. The results showed that the developed system successfully identified aerosolized biological particles from non-biological particles in real time

Liquefaction of H2 molecules upon exterior surfaces of carbon nanotube bundles

We have used molecular dynamics simulations to investigate interaction of H2 molecules on the exterior surfaces of carbon nanotubes (CNTs): single and bundle types. At 80 K and 10 MPa, it is found that charge transfer occurs from a low curvature region to a high curvature region of the deformed CNT bundle, which develops charge polarization only on the deformed structure. The long-range electrostatic interactions of polarized charges on the deformed CNT bundle with hydrogen molecules are observed to induce a high local-ordering of H2 gas that results in hydrogen liquefaction. Our predicted heat of hydrogen liquefaction on the CNT bundle is 97.6 kcal kg^-1. On the other hand, hydrogen liquefaction is not observed in the CNT of a single type. This is because charge polarization is not developed on the single CNT as it is symmetrically deformed under the same pressure. Consequently, the hydrogen storage capacity on the CNT bundle is much higher due to liquefaction than that on the single CNT. Additionally, our results indicate that it would also be possible to liquefy H2 gas on a more strongly polarized CNT bundle at temperatures higher than 80 K

The theoretical study on interaction of hydrogen with single-walled boron nitride nanotubes. I. The reactive force field ReaxFFHBN development

We present a new reactive force field ReaxFFHBN derived to accurately model large molecular and condensed phase systems of H, B, and N atoms. ReaxFFHBN has been tested against quantum calculation data for B–H, B–B, and B–N bond dissociations and for H–B–H, B–N–B, and N–B–N bond angle strain energies of various molecular clusters. The accuracy of the developed ReaxFFHBN for B–N–H systems is also tested for (i) H–B and H–B bond energies as a function of out of plane in H–B(NH2)3 and H–N(BH2)3, respectively, (ii) the reaction energy for the B3N3H6+H2-->B3N3H8, and (iii) crystal properties such as lattice parameters and equations of states for the hexagonal type (h-BN) with a graphite structure and for the cubic type (c-BN) with a zinc-blende structure. For all these systems, ReaxFFHBN gives reliable results consistent with those from quantum calculations as it describes well bond breaking and formation in chemical processes and physical properties. Consequently, the molecular-dynamics simulation based on ReaxFFHBN is expected to give a good description of large systems (>2000 atoms even on the one-CPU machine) with hydrogen, boron, and nitrogen atoms

Theoretical study on interaction of hydrogen with single-walled boron nitride nanotubes. II. Collision, storage, and adsorption

Collision and adsorption of hydrogen with high incident kinetic energies on a single-walled boron nitride (BN) nanotube have been investigated. Molecular-dynamics (MD) simulations indicate that at incident energies below 14 eV hydrogen bounces off the BN nanotube wall. On the other hand, at incident energies between 14 and 22 eV each hydrogen molecule is dissociated at the exterior wall to form two hydrogen atoms, but only one of them goes through the wall. However, at the incident energies between 23 and 26 eV all of the hydrogen atoms dissociated at the exterior wall are found to be capable of going inside the nanotube and then to recombine to form hydrogen molecules inside the nanotube. Consequently, it is determined that hydrogen should have the incident energy >22 eV to go inside the nanotube. On the other hand, we find that the collisions using the incident energies >26 eV could result in damaging the nanotube structures. In addition our MD simulations find that hydrogen atoms dissociated at the wall cannot bind to either boron or nitrogen atoms in the interior wall of the nanotube

Nanoscale reaction vessels: Highly ordered nanocrystal arrays inside porous anodic alumina nanowells

Using an anodic alumina template as a nanoscale reaction vessel, the authors developed a simple and unique method to prepare highly ordered arrays of nanocrystals in isolated nanowells. The highly ordered arrays of nanoscale wells were fabricated by short anodization. After the nanoscale wells were filled with a precursor solution of NaCl by dewetting, the solvent of the precursor solution was evaporated, resulting in spontaneous formation of uniformly sized NaCl nanocrystals inside the nanoscale wells. The size of crystals could be easily adjusted by varying the concentration of the precursor solution and the size of nanoscale wells. This approach is simple and cost-effective, and it can fabricate nanocrystal arrays on substrates with high throughput. It can also be readily adapted to synthesize other types of high-density nanocrystal arrays on different substrates. © 2015 The Authorsopen0

Simple and Reliable Position Sense Assessment Under Different External Torques: Toward Developing a Post-Stroke Proprioception Evaluation Device

Evaluation of position sense post-stroke is essential for rehabilitation. Position sense may be an output of a process needing position information, external torque, and the sense of effort. Even for healthy individuals, it is unclear whether external torque affects position sense. Thus, evaluation of position sense under different external torques in clinical settings is strongly needed. However, simple devices for measuring position sense under different external torques in clinical settings are lacking. Technologically advanced devices that may evaluate the elbow position sense under different torques were reported to be infeasible clinically because of device complexity and the need for technical experts when analyzing data. To address the unmet need, in this study, a simple and light elbow position sense measurement device was developed that allows clinicians to measure elbow position sense under different external torques in the form of position matching error objectively without any technical difficulties. The feasibility of the device, including intra-session intra-rater reliability and test-retest reliability over two consecutive days, was verified to be clinically applicable using tests with 25 healthy subjects. Thanks to its ease of use, high reliability, and ease of data analysis, it is expected that the device can help to evaluate the position sense post-stroke comprehensively

Spatially resolved inhomogeneous depressions of the excitons Zeeman splitting in an integrated magnetic-multiple quantum wells system

We report on the generation of a nonuniform spatial distribution of the heavy and light-hole excitons in a multiple quantum wells system integrated with a localized inhomogeneous weak magnetic field. An inhomogeneous spatially resolved depression of the Zeeman splittings of the heavy-hole excitons and the light-hole excitons with respect to their translational wave vectors is observed. A localized inverted concentration of the two types of the excitons due to the inhomogeneity of the magnetic field is also measured. A simple method to integrate permanent magnetic materials with the multiple quantum wells system is used to create an accessible degree of control for magnetically manipulating the excitonic distribution

The Significance of Lumbar Probing Combined with Continuous Irrigation and Undercutting Posterior Vertebral Body for Highly Upward Migrated Disc Herniation in ACDF: Case Reports and technical notes

The purpose of this report was to present successful cases and technical notes of the patients with up migrated cervical disc herniation to the upper level who were successfully treated using anterior cervical discectomy and fusion (ACDF), describing the evaluation of treatment outcomes and perioperative complications. The cases of two patients who had ACDF in symptomatic up migrated cervical disc herniation to the upper level in February 2021 and November 2021 were reviewed. Two patients presented with a six-week history of posterior neck pain and radiating pain. Preoperative magnetic resonance imaging (MRI) confirmed a diagnosis of up migrated cervical disc extrusion. The patients were admitted to Daegu Wooridul Spine Hospital in Daegu, Korea. ACDF was performed under general anesthesia. Treatment outcomes were examined by comparing pre and postoperative Numeric Rating Scale (NRS), and MRI. Treatment outcomes were favorable: posterior neck pain and radiating pain showed a significant reduction in NRS. Postoperative MRI showed that the up migrated discs were successfully removed in both cases. Neither patient developed perioperative complications. Anterior cervical discectomy can be feasible in patients with symptomatic up migrated cervical disc herniation to the upper level

Only Surgical Decompression Is Sufficient for Multilevel Lumbar Spinal Stenosis with Calcified Disc Protrusion and Vacuum Disc: Case Reports

This report was aimed to share our successful cases of only surgical decompression for multilevel lumbar spinal stenosis, by assessing treatment outcomes. Two patients who had only surgical decompression for multilevel lumbar spinal stenosis were investigated. They were diagnosed with the calcified disc protrusion and vacuum disc in the intervertebral space by magnetic resonance imaging (MRI) and computed tomography (CT). The chief complaints were severe low back pain and bilateral sciatica 2 or 3 months ago. The patients also reported difficulty walking due to sciatica. Unilateral laminotomy for bilateral decompression was performed and discectomy was not done on the stenosis levels. Treatment outcomes were analyzed by visual analog scale for low back pain and sciatica (Back VAS, Leg VAS), improvement in walking, and postoperative MRI. Treatment outcomes were favorable: Low back pain and bilateral sciatica showed a VAS score improvement (Back VAS =3, Leg VAS=3), the patient’s walking was improved, and on a postoperative MRI of the two patients, the thecal sac was released sufficiently. The patients developed no perioperative complications. Only surgical decompression is an effective method for multilevel lumbar spinal stenosis with calcified disc protrusion and vacuum disc in the intervertebral space