The pandemic coronavirus SARS-CoV-2 in the world has caused a large infected population suffering from COVID-19. To curb the spreading of the virus, WHO urgently demanded an extension of screening and testing; thus, a rapid and simple diagnostic method is needed. We applied a reverse transcription-loop-mediated isothermal amplification (RT-LAMP) to achieve the detection of SARS-CoV-2 in 30 min. We designed four sets of LAMP primers (6 primers in each set), targeting the viral RNA of SARS-CoV-2 in the regions of orf1ab, S gene and N gene. A colorimetric change was used to report the results, which enables the outcome of viral RNA amplification to be read by the naked eye without the need of expensive or dedicated instrument. The sensitivity can be 80 copies of viral RNA per ml in a sample. We validated the RT-LAMP method in a hospital in China, employing 16 clinic samples with 8 positives and 8 negatives. The testing results are consistent with the conventional RT-qPCR. In addition, we also show that one-step process without RNA extraction is feasible to achieve RNA amplification directly from a sample. This rapid, simple and sensitive RT-LAMP method paves a way for a large screening at public domain and hospitals, particularly regional hospitals and medical centres in rural areas.

A simple and efficient optical interference method for fabricating high quality two- and three-dimensional (2D and 3D) periodic structures is demonstrated. Employing multi-exposure of two-beam interference technique, different types of periodic structures are created depending on the number of exposure and the rotation angle of the sample for each exposure. Square and hexagonal 2D structures are fabricated by a multi-exposure of two-beam interference pattern with a rotation angle of 90 masculine and 60 masculine between two different exposures, respectively. Three-exposure, in particular, results in different kinds of 3D structures, with close lattice constants in transverse and longitudinal directions, which is difficult to be obtained by the commonly used multi-beam interference technique. The experimental results obtained with SU-8 photoresist are well in agreement with the theoretical predictions. Multi-exposure of two-beam interference technique should be very useful for fabrication of photonic crystals.

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Second-order nonlinear optical devices can be constructed by arranging the organic chromophores as pendants into a supramolecular backbone. [1][2][3][4] Enhancement of such nonlinearity has been observed when chromophores are organized in a fixed noncentrosymmetric arrangement as side groups of helical polyisocyanide and polypeptide. 1 However, no enhancement on the first hyperpolarizability β 0 values was observed for chromophores incorporated into a polymer with a flexible backbone. 4 The use of more rigid polymers such as polynorbornenes (PNB) derived from the ring-opening metathesis polymerization (ROMP) of norbornene derivatives in optoelectronic applications has been briefly explored. [5][6][7] The versatility of this methodology was demonstrated by synthesizing liquid crystalline polymers, 5 electroluminescent polymers, 6 and multiblock copolymers bearing various aryl chromophores to study their steady-state emission. 7 We wish to report the first examples of using dipolar conjugated moieties as pendants on a PNB backbone for the second-order nonlinear optical investigations.Four different monomers 1 were synthesized (Scheme 1, Supporting Information). 8 Grubb's ruthenium catalyst (RuCl 2 -(PCy 3 ) 2 (dCHPh) was employed to prepare the corresponding polymers 2. 8,9 The M n and polydispersity (PDI) of 2 as well as the absorption maxima in CHCl 3 solution of both 1 and 2 are summarized in Table 1. The profiles of the absorption spectra of 1 and 2 are similar, although the absorption maxima for 2 are somewhat blue-shifted in comparison to those of the corresponding 1. 10 Only 1d and 2d exhibited fluorescence emission at 497 and 492 nm, respectively, no excimer formation being detected. Thermogravimetrical analyses showed that polymers 2a and 2d were stable at 220 °C, whereas 2b and 2c remained intact below 180 °C.The hyper-Rayleigh scattering (HRS) method was employed to measure the β 0 values for 1 and 2 in CHCl 3 which are also tabulated in Table 1. 11,12 It is interesting to note that the β 0 values are significantly enhanced in 2 in comparison with those of the corresponding monomers 1. A plot of the β 0 (2)/β 0 (1) having the same pendant chromophore versus the average number of repetitive monomeric units, n, in 2 gave a linear relationship with

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By embedding NaYF 4 :Yb 3+ ,Tm 3+ nanocrystals into the top cladding layer of a resonant waveguide grating structure, we demonstrate that the upconversion fluorescence of Tm 3+ ions can be greatly enhanced, by a factor of up to 10 4 . The resonant waveguide grating structure consists of an SU8 bottom layer with sinusoidal grating morphology coated with a thin TiO 2 waveguide layer and then covered with a poly(methyl methacrylate) cladding layer doped with NaYF 4 :Yb 3+ ,Tm 3+ nanocrystals. The giant enhancement of the upconversion fluorescence is achieved first by coupling the excitation light with a guided mode of the resonant waveguide grating structure and then the fluorescent light with a second guided mode. Our numerical simulation results obtained by rigorous coupled-wave analysis indicate that the electric field of the incident light is strongly enhanced near the interface of the TiO 2 layer and the poly(methyl methacrylate) layer at guided mode resonance, and this is the major effect of the observed enhancement of the upconversion fluorescence of the nanocrystals. The resonance between the fluorescent emission and the waveguide structure further enhances the intensities of the fluorescent signal. We also find that the lifetime of upconversion fluorescence at 480 nm wavelength from the rare-earth nanocrystals is reduced about 1.34-fold when both excitation and extraction resonance occurs in the waveguide structure.

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BackgroundThe effectiveness of arthroscopic treatment for osteoarthritic knee is a controversy. This study presents the technique of a novel concept of arthroscopic procedure and investigates its clinical outcome.MethodAn arthroscopic procedure targeted on elimination of focal abrasion phenomenon and regaining soft tissue balance around patello-femoral joint was applied to treat osteoarthritis knees. Five hundred and seventy-one knees of 367 patients with osteoarthritis received this procedure. There were 70 (19%) male and 297 (81%) female and the mean age was 60 years (SD 10). The Knee Society score (KSS) and the knee injury and osteoarthritis outcome score (KOOS) were used for subjective outcome study. The roentgenographic changes of femoral-tibial angle and joint space width were evaluated for objective outcomes. The mean follow-up period was 38 months (SD 3).ResultsThere were 505 knees in 326 patients available with more than 3 years follow-up and the mean follow-up period was 38 months (SD 3). The subjective satisfactory rate for the whole series was 85.5%. For 134 knees with comprehensive follow-up evaluation, the KSS and all subscales of the KOOS improved statistically. The femoral-tibial angle improved from 1.57 degrees (SD 3.92) to 1.93 degrees (SD 4.12) (mean difference: 0.35, SD 0.17). The joint space width increased from 2.02 millimeters (SD 1.24) to 2.17 millimeters (SD 1.17) (mean difference: 0.13, SD 0.05). The degeneration process of the medial compartment was found being reversed in 82.1% of these knees by radiographic evaluation.ConclusionsBased on these observations arthroscopic cartilage regeneration facilitating procedure is an effective treatment for osteoarthritis of the knee joint and can be expected to satisfy the majority of patients and reverse the degenerative process of their knees.