819 research outputs found

    Microfabricated high-finesse optical cavity with open access and small volume

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    We present a microfabricated optical cavity, which combines a very small mode volume with high finesse. In contrast to other micro-resonators, such as microspheres, the structure we have built gives atoms and molecules direct access to the high-intensity part of the field mode, enabling them to interact strongly with photons in the cavity for the purposes of detection and quantum-coherent manipulation. Light couples directly in and out of the resonator through an optical fiber, avoiding the need for sensitive coupling optics. This renders the cavity particularly attractive as a component of a lab-on-a-chip, and as a node in a quantum network

    An antibody raised against a pathogenic serpin variant induces mutant-like behaviour in the wild-type protein

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    A monoclonal antibody (mAb) that binds to a transient intermediate may act as a catalyst for the corresponding reaction; here we show this principle can extend on a macro molecular scale to the induction of mutant-like oligomerization in a wild-type protein. Using the common pathogenic E342K (Z) variant of α1-antitrypsin as antigen-whose native state is susceptible to the formation of a proto-oligomeric intermediate-we have produced a mAb (5E3) that increases the rate of oligomerization of the wild-type (M) variant. Employing ELISA, gel shift, thermal stability and FRET time-course experiments, we show that mAb5E3 does not bind to the native state of α1-antitrypsin, but recognizes a cryptic epitope in the vicinity of the post-helix A loop and strand 4C that is revealed upon transition to the polymerization intermediate, and which persists in the ensuing oligomer. This epitope is not shared by loop-inserted monomeric conformations. We show the increased amenity to polymerization by either the pathogenic E342K mutation or the binding of mAb5E3 occurs without affecting the energetic barrier to polymerization. As mAb5E3 also does not alter the relative stability of the monomer to intermediate, it acts in a manner similar to the E342K mutant, by facilitating the conformational interchange between these two states

    Laser beam steering device

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    Agile beam steering is a critical requirement for airborne and space based LIDAR and optical communication systems. Design and test results are presented for a compact beam steering device with low inertia which functions by dithering two complementary (positive and negative) binary optic microlens arrays relative to each other in directions orthogonal to the direction of light propagation. The miniaturized system has been demonstrated at scan frequencies as high as 300 Hz, generating a 13 x 13 spot array with a total field of view of 2.4 degrees. The design is readily extendable to a 9.5 degree field of view and a 52 x 52 scan pattern. The system is compact - less than 2 in. on a side. Further size reductions are anticipated

    Floating aortic thrombus with celiac artery embolus presenting with chronic epigastric and right upper quadrant pain: A case report

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    Arterial occlusion may be the cause of chronic pain, and vascular diagnostic procedures should be a part of the workup in patients with unexplained chronic visceral pain. © 2021 The Authors. Clinical Case Reports published by John Wiley & Sons Ltd

    Comparison of antibacterial activity of essential oils of Foeniculum vulgare Mill, Mentha arvensis and Mentha piperita against Streptococcus mutans

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    Background and aims: Tooth decay is one of the most common chronic diseases around the world and this problem is the result of variety of different bacteria. Streptococcus mutants is one of the most important bacteria which is related to this disease. Finding new effective antibacterial agents is an important area in bioscience for fighting and controlling bacterial infections. Essential oils are most important natural sources of antibacterial agents, particularly against drug-resistant bacteria. Methods: The aim of this study was to evaluate and compare the antibacterial activity of three essential oils Mentha arvensis, Mentha piperita and Foeniculum vulgare Mill against Streptococcus mutants. Disk diffusion method was carried out and the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were measured. Results: The results showed that all three essential oils have antibacterial activity against S. mutants. With a constant concentration of 100 µg/µl, the efficiency of Mentha piperita and then Foeniculum vulgare Mill was higher than the efficiency of Mentha arvensis at all 3 given time points (24, 48 and 72 hours). The most effective MIC and MBC were related to Streptococcus mutants using Foeniculum vulgare essential oil which were equal to 8.4 and 14.9 µg/ml, respectively. MIC and MBC for Mentha piperita essential oil were measured 10.5 and 16.3 µg/ml, respectively. Conclusion: The Essential oils used in present study with different components showed antibacterial activity and therefore they can be used as new antibacterial substances

    Titration of the Iranian white spot virus isolate, on crayfish Astacus leptodactylus and Penaeus semisulcatus

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    White Spot Virus (WSV) is currently the most serious viral pathogen of shrimp worldwide; it causes mortality up to 100% within 7-10 days in commercial shrimp farms. Infected Indian white shrimp Fenneropenaeus indicus samples were collected from Guatr shrimp site in Sistan and Baluchestan province in south of Iran and WSV infection was confirmed by Nested PCR. WSV was isolated from infected shrimp samples by centrifugation and filtration and multiplied in crayfish by intramuscular inoculation, the isolated virus was called WSV/IRN/1/2010. In order to determine the dilution resulting in 90-100% mortality in Penaeus semiculcatus, diluted virus stock in steps from 10^0 till 10^5 times in sterile PBS was injected intramuscularly to 14 shrimps in each group. Also the virus stock was diluted in steps from 1/2 till 1/32 times in sterile PBS and injected intramuscularly in Astacus leptodactylus crayfish. Therefore the LD50 of live virus stock in Astacus leptodactylus and Penaeus semiculcatus crayfish were calculated by the Karber method 10^3.29 /ml and 10^5.35 /ml, respectively
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