An improvement of current hypercube pooling PCR tests for SARS-CoV-2 detection.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic can be effectively controlled by rapid and accurate identification of SARS-CoV-2-infected cases through large-scale screening. Hypercube pooling polymerase chain reaction (PCR) is frequently used as a pooling technique because of its high speed and efficiency. We attempted to implement the hypercube pooling strategy and found it had a large quantization effect. This raised two questions: is hypercube pooling with edge = 3 actually the optimal strategy? If not, what is the best edge and dimension? We used a C++ program to calculate the expected number of PCR tests per patient for different values of prevalence, edge, and dimension. The results showed that every edge had a best performance range. Then, using C++ again, we created a program to calculate the optimal edge and dimension required for pooling samples when entering prevalence into our program. Our program will be provided as freeware in the hope that it can help governments fight the SARS-CoV-2 pandemic.

Mathematical model of distal radius orientation.

Distal radius orientation is important in evaluating Colles' fracture. In most cases, the wrist was protected by a bandage, splint, or cast. Therefore, it was difficult for the radiology technician to take perfect anteroposterior and lateral view radiographs. In this study, we build a mathematical model and calculate the pronation angle needed to produce dorsal tilt, which is a volar tilt in a perfect lateral view radiograph. The formulas are all incorporated into Excel to facilitate usage.

Geometrical analysis for assessing torsional alignment of humerus.

BACKGROUND: Compared to other types of surgeries, minimally invasive surgeries (MISs) of humeral shaft fractures are associated with less radial nerve injury, less soft tissue injury and higher union rate. However, malrotation often occurs in MISs when closed reduction methods are used. This study aims to define specific palpable landmarks to help surgeons determine the correct torsional angle and reduce the incidence of malrotation. METHODS: Twenty-eight normal humeral computed tomography scans were retrieved from our image database. One line was drawn through the vertices of the intertubercular sulcus of the humeral head in the coronal view, and another line was drawn through the longest axis between the medial and lateral condyles in the coronal view. The angle between these two lines was measured at least 3 times for each scan. RESULTS: The profile of the intertubercular sulcus tangent line of the humeral head and the axis of the distal humerus was identified as the most accurate method for assessing the precision of torsion during MIS for humeral shaft fractures. The transepicondylar axis line is more internally rotated than the intertubercular sulcus tangent line. The mean angle was measured to be 41.1 degrees. CONCLUSIONS: The axis of the distal humeral condyles is internally rotated by approximately 41.1 degrees compared with the intertubercular sulcus tangent line of the humeral head. Minimally invasive surgeries can be performed by using these palpable landmarks. The torsional deformities can be reduced with the proper angle adjustment without the need for fluoroscopy. It can also be used to treat unstable comminuted humeral fractures. LEVEL OF EVIDENCE: Retrospective Study, Diagnostic study, Level III.

Surfactant-directed fabrication of supercrystals from the assembly of polyhedral Au-Pd core-shell nanocrystals and their electrical and optical properties.

Au-Pd core-shell nanocrystals with cubic, truncated cubic, cuboctahedral, truncated octahedral, and octahedral structures have been employed to form micrometer-sized polyhedral supercrystals by both the droplet evaporation method and novel surfactant diffusion methods. Observation of cross-sectional samples indicates shape preservation of interior nanocrystals within a supercrystal. Low-angle X-ray diffraction techniques and electron microscopy have been used to confirm the presence of surfactant between contacting nanocrystals. By diluting the nanocrystal concentration or increasing the solution temperature, supercrystal size can be tuned gradually to well below 1 µm using the surfactant diffusion method. Rectangular supercrystal microbars were obtained by increasing the amounts of cubic nanocrystals and surfactant used. Au-Ag core-shell cubes and PbS cubes with sizes of 30-40 nm have also been fabricated into supercrystals, showing the generality of the surfactant diffusion approach to form supercrystals with diverse composition. Electrical conductivity measurements on single Au-Pd supercrystals reveal loss of metallic conductivity due to the presence of insulating surfactant. Cubic Au-Pd supercrystals show infrared absorption at 3.2 µm due to extensive plasmon coupling. Mie-type resonances centered at 9.8 µm for the Au-Pd supercrystals disappear once the Pd shells are converted into PdH after hydrogen absorption.

Enhanced vibrational spectroscopy, intracellular refractive indexing for label-free biosensing and bioimaging by multiband plasmonic-antenna array.

In this study, we report a multiband plasmonic-antenna array that bridges optical biosensing and intracellular bioimaging without requiring a labeling process or coupler. First, a compact plasmonic-antenna array is designed exhibiting a bandwidth of several octaves for use in both multi-band plasmonic resonance-enhanced vibrational spectroscopy and refractive index probing. Second, a single-element plasmonic antenna can be used as a multifunctional sensing pixel that enables mapping the distribution of targets in thin films and biological specimens by enhancing the signals of vibrational signatures and sensing the refractive index contrast. Finally, using the fabricated plasmonic-antenna array yielded reliable intracellular observation was demonstrated from the vibrational signatures and intracellular refractive index contrast requiring neither labeling nor a coupler. These unique features enable the plasmonic-antenna array to function in a label-free manner, facilitating bio-sensing and imaging development.

Inducing transparency with large magnetic response and group indices by hybrid dielectric metamaterials.

We present metamaterial-induced transparency (MIT) phenomena with enhanced magnetic fields in hybrid dielectric metamaterials. Using two hybrid structures of identical-dielectric-constant resonators (IDRs) and distinct-dielectric-constant resonators (DDRs), we demonstrate a larger group index (ng~354), better bandwidth-delay product (BDP~0.9) than metallic-type metamaterials. The keys to enable these properties are to excite either the trapped mode or the suppressed mode resonances, which can be managed by controlling the contrast of dielectric constants between the dielectric resonators in the hybrid metamaterials.

Low-loss and high-symmetry negative refractive index media by hybrid dielectric resonators.

Based on Maxwell's equations and Mie theory, strong sub-wavelength artificial magnetic and electric dipole resonances can be excited within dielectric resonators, and their resonant frequencies can be tailored simply by scaling the size of the dielectric resonators. Therefore, in this work we hybridize commercially available zirconia and alumina structures to harvest their individual artificial magnetic and electric response simultaneously, presenting a negative refractive index medium (NRIM). Comparing with the conventional NRIM constructed by metallic structures, the demonstrated all-dielectric NRIM possesses low-loss and high-symmetry advantages, thus benefiting practical applications in communication components, perfect lenses, invisible cloaking and other novel electromagnetic devices.

A multi-functional plasmonic biosensor.

We present a coupler-free, multi-mode refractive index sensor based on nanostructured split ring resonators (SRRs). The fabricated SRR structures exhibit multiple reflectance peaks, whose spectral positions are sensitive to local dielectric environment and can be quantitatively described by our standing-wave plasmonic resonance model, providing a design rule for this multi-mode refractive-index (MMRI) sensor. We further manifest that the lower-order modes possess greater sensitivity associated with stronger localized electromagnetic field leading to shorter detection lengths within five hundreds nanometers, while the higher-order modes present mediate sensitivity with micron-scale detection lengths to allow intracellular bio-events detection. These unique merits enable the SRR-based sensor a multi-functional biosensor and a potential label-free imaging device.

Creating negative refractive identity via single-dielectric resonators.

From a periodic array of commercially available zirconia cubes, we demonstrate artificial magnetic and electric dipoles due to the combination of displacement currents and Mie resonance. By scaling the size and periodicity of these dielectric resonators, the corresponding magnetic and electric responses are shifted to the desired frequencies. To further overlap the magnetic and electric resonances in the same frequency, we create a negative refractive index medium (NRIM) from single-dielectric resonators. Comparing with the conventional NRIM comprised of metallic or two-dielectric resonators, these single-dielectric structures present the low-loss and isotropic characteristics, and possess a further advantage to facilitate practical applications.

Coexposure of lead- and lipopolysaccharide-induced liver injury in rats: involvement of nitric oxide-initiated oxidative stress and TNF-alpha.

In this study, we investigated the interaction between lipopolysaccharide (LPS) and lead (Pb) and the involvement of tumor necrosis factor-alpha (TNF-alpha) and oxidative stress in Pb-plus-LPS (Pb/LPS)-induced liver damage in rats. Serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), TNF-alpha, nitric oxide (NO), and lipid peroxidation (LPO) were determined in rats treated with Pb and/or LPS. Pb ranging from 0 to 15 mg/kg dose dependently increased AST, ALT, NO, or LPO in LPS-treated rats. Pretreatment with iNOS inhibitor 1400W reduced NO, LPO, TNF-alpha, AST, and ALT in Pb/LPS-treated rats. Thus, Pb increased LPS-induced liver damage, which might be associated with increased NO-initiated oxidative stress and TNF-alpha in rats.