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A femtosecond laser is a powerful tool for micromachining of silicon. In this work, large-area laser ablation of crystalline silicon is comprehensively studied using a laser source of pulse width 300 fs at two wavelengths of 343 nm and 1030 nm. We develop a unique approach to gain insight into the laser milling process by means of detailed analysis of trenches. Laser scribed trenches and milled areas are characterized using optical profilometry to extract dimensional and roughness parametersarXiv:2008.13205v1 fatcat:efyzoi224bc4nnkph3uaxo5x2q
more »... h accuracy and repeatability. In a first step, multiple measures of the trench including the average depth, the volume of recast material, the average longitudinal profile roughness, the inner trench width and the volume removal rate are studied. This allows for delineation of ablation regimes and associated characteristics allowing to determine the impact of fluence and repetition rate on laser milling. In a second step, additional factors of debris formation and material redeposition that come into play during laser milling are further elucidated. These results are utilized for processing large-area (up to few mm2) with milling depths up to 200 μm to enable the fabrication of cavities with low surface roughness at high removal rates of up to 6.9 μm3 μs-1. Finally, laser processing in combination with XeF2 etching is applied on SOI-CMOS technology in the fabrication of radio-frequency (RF) functions standing on suspended membranes. Performance is considerably improved on different functions like RF switch (23 dB improvement in 2nd harmonic), inductors (near doubling of Q-factor) and LNA (noise figure improvement of 0.1 dB) demonstrating the applicability of milling to radio-frequency applications.
early life. Unfortunately, information is currently insufficient to assess whether these NK cell responses really contribute to control infections, either vertically transmitted or acquired in infancy.doi:10.1159/000323934 pmid:21411972 fatcat:7wavayxknrhzzj2qcpmpuad26q
In biology, molecules and macromolecules such as sugars, proteins, DNA, RNA, etc., are of utmost importance. Detecting their presence as well as getting information on their actual structure is still a challenge in many cases. The vibrational states of such molecules correspond to a spectral range extending from infrared to terahertz. Spectroscopy is used for the detection and the identification of such compounds and their structure. Terahertz spectroscopy of a biosample is challenging for twodoi:10.3390/photonics5020011 fatcat:dhtkak2mfzfndl5gj2nqojlogu
more »... ain reasons: the high terahertz absorption by water molecules in the sample; and the small size of the sample-its volume is usually smaller than the cube of the terahertz wavelength, thus the light-matter interaction is extremely reduced. In this paper, we present the design, fabrication, characterization, and first typical use of a biophotonic device that aims to increase the light-matter interaction to enable terahertz spectroscopy of very small samples over a broad band (0.2-2 THz). Finally, we demonstrate the validity of our approach by time-domain spectroscopy of samples of a few µL. for spectroscopy, especially for biological systems, since the energy of the photon in the THz range is around [k B × T] at room temperature (~6 THz) and corresponds to the fundamental vibrational modes of molecules, molecular crystals or macromolecules, such as carbohydrates  , DNA, RNA, and proteins  . To summarize, while spectroscopy in the mid-infrared range of the spectrum mainly probes vibrations associated with localized atom-atom stretches in molecules, THz frequencies mainly probe collective vibrational modes in heavy and/or long molecules. However, there are still many hurdles to jump over to enable THz spectroscopy of actual biosamples. One of the major issues is that they are very small compared to the THz wavelength, which is typically between 0.1 and 1 mm. Therefore, it is mandatory to enable subwavelength confinement of the THz electromagnetic field in the sample. Such confinement has been a subject of interest in the community. To our knowledge, all the approaches exploit the relatively good response of metals in the THz range compared to the visible or near infrared ranges. There are two different approaches. The first one is to use a near-field microscopy set-up and to functionalize it for THz spectroscopy  . The second is to use a subwavelength waveguide structure. One can, for instance, use a metallic wire  around which the THz wave will propagate. In this case, the sample is placed around the wire and the light-matter interaction is not entirely enhanced because higher confinements can be achieved using full metallic boundary conditions. The most natural approach to confine the light in one direction is to use a parallel plate metallic waveguide (PPMW)  . In such a waveguide, the lower frequency mode (transverse electromagnetic: TEM) shows no frequency cut-off, relatively low losses, and, importantly, very weak dispersion linked only to the metallic material's dispersion, which is ideal for time-domain spectroscopy (TDS) [12, 13] experiments. However, a specific coupling scheme is needed to properly excite the mode of interest. The first proposed method uses silicon cylindrical lenses  with the drawbacks of introducing coupling that is highly dependent on waveguide geometry, and adding reflections due to the high refractive index of silicon. Despite this, this technique has been used inside a cryostat  . To overcome the limitations, tapered coupling antennas were used  which improved the coupling and the ease of use of the device. However, the main limitation of the PPMW is that it assumes a quasi-infinite height with the major consequence that there is no vertical confinement. There are two drawbacks of this: firstly, the light-matter interaction for small samples is smaller than in the case of 2D confinement; secondly, no vertical confinement means that during the propagation inside the waveguide, the mode will expand in the vertical direction, resulting in a strong astigmatism, probably explaining the high losses experienced in Ref.  . In this article, we present the design, technological process, characterization, and typical application of a device aiming to confine THz pulses into a 2D waveguide. The thick slot line waveguide (TSLW) does not show significant reflection or dispersion. We combined the curved tapered antenna approach (similarly to Ref.  ) to properly inject the beam into the waveguide together with the approach of Ref.  , using a fully planar geometry and subsequent 2D confinement. We modified this combination with the use of an exponential growth taper, as in Vivaldi antennas. Due to its final shape and geometry, we named our exponential tapered antenna coupled metallic waveguide "Butterfly".
RNA methyltransferases (MTases) catalyse the transfer of a methyl group to their RNA substrates using most-often S-adenosyl-L-methionine (SAM) as cofactor. Only few RNA-bound MTases structures are currently available due to the difficulties in crystallising RNA:protein complexes. The lack of complex structures results in poorly understood RNA recognition patterns and methylation reaction mechanisms. On the contrary, many cofactor-bound MTase structures are available, resulting indoi:10.6084/m9.figshare.7855421.v1 fatcat:qlw6oggav5clzkjkel76ti4dym
more »... protein:cofactor recognition, that can guide the design of bisubstrate analogues that mimic the state at which both the substrate and the cofactor is bound. Such bisubstrate analogues were recently synthesized for proteins monomethylating the N6-atom of adenine (m6A). These proteins include, amongst others, RlmJ in E. coli and METLL3:METT14 and METTL16 in human. As a proof-of-concept, we here test the ability of the bisubstrate analogues to mimic the substrate:cofactor bound state during catalysis by studying their binding to RlmJ using differential scanning fluorimetry, isothermal titration calorimetry and X-ray crystallography. We find that the methylated adenine base binds in the correct pocket, and thus these analogues could potentially be used broadly to study the RNA recognition and catalytic mechanism of m6A MTases. Two bisubstrate analogues bind RlmJ with micro-molar affinity, and could serve as starting scaffolds for inhibitor design against m6A RNA MTases. The same analogues cause changes in the melting temperature of the m1A RNA MTase, TrmK, indicating non-selective protein:compound complex formation. Thus, optimization of these molecular scaffolds for m6A RNA MTase inhibition should aim to increase selectivity, as well as affinity.
High Q-factor inductors are critical in designing high performance RF/microwave circuits on SOI technology. Substrate losses is a key limiting factor when designing inductors with high Q-factors. In this context, we report a substrate engineering method that enables improvement of quality factors of already fabricated inductors on SOI. A novel femtosecond laser milling process is utilized for the fabrication of locally suspended membranes of inductors with handler silicon completely etched.arXiv:2008.09030v1 fatcat:ou5cbodgpvdztlllgvrojar4pq
more »... flexible membranes suspended freely on the BOX show up to 92 % improvement in Q factor for single turn inductor. The improvement in Q-factor is reported on large sized inductors due to reduced parallel capacitance which allows enhanced operation of inductors at high frequencies. A compact model extraction methodology has been developed to model inductor membranes. These membranes have been utilized for the improvement of noise performance of LNA working in the 4.9,5.9 GHz range. A 0.1 dB improvement in noise figure has been reported by taking an existing design and suspending the input side inductors of the LNA circuit. The substrate engineering method reported in this work is not only applicable to inductors but also to active circuits, making it a powerful tool for enhancement of RF devices.
doi:10.3201/eid2212.150983 pmid:27869605 pmcid:PMC5189124 fatcat:4h5qkns6bfgw7oupyrjoiiw4pq
RNA methyltransferases (MTases) catalyse the transfer of a methyl group to their RNA substrates using mostoften S-adenosyl-L-methionine (SAM) as cofactor. Only few RNA-bound MTases structures are currently available due to the difficulties in crystallising RNA:protein complexes. The lack of complex structures results in poorly understood RNA recognition patterns and methylation reaction mechanisms. On the contrary, many cofactor-bound MTase structures are available, resulting in well-understooddoi:10.1080/15476286.2019.1589360 fatcat:w3t54pqsl5hb3cks72sic7vsom
more »... protein:cofactor recognition, that can guide the design of bisubstrate analogues that mimic the state at which both the substrate and the cofactor is bound. Such bisubstrate analogues were recently synthesized for proteins monomethylating the N6-atom of adenine (m 6 A). These proteins include, amongst others, RlmJ in E. coli and METLL3:METT14 and METTL16 in human. As a proof-of-concept, we here test the ability of the bisubstrate analogues to mimic the substrate:cofactor bound state during catalysis by studying their binding to RlmJ using differential scanning fluorimetry, isothermal titration calorimetry and X-ray crystallography. We find that the methylated adenine base binds in the correct pocket, and thus these analogues could potentially be used broadly to study the RNA recognition and catalytic mechanism of m 6 A MTases. Two bisubstrate analogues bind RlmJ with micro-molar affinity, and could serve as starting scaffolds for inhibitor design against m 6 A RNA MTases. The same analogues cause changes in the melting temperature of the m 1 A RNA MTase, TrmK, indicating non-selective protein:compound complex formation. Thus, optimization of these molecular scaffolds for m 6 A RNA MTase inhibition should aim to increase selectivity, as well as affinity. ARTICLE HISTORY
Flora Ngadjeua, Emmanuelle Braud, Saidbakhrom Saidjalolov, Laura Iannazzo, Dirk Schnappinger, Sabine Ehrt, Jean-Emmanuel Hugonnet, Dominique Mengin-Lecreulx, Delphine Patin, Mélanie Ethève-Quelquejeu, ... Flora Ngadjeua # , Emmanuelle Braud # , Saidbakhrom Saidjalolov, Laura Iannazzo, Dirk Schnappinger, Sabine Ehrt, Jean- Emmanuel Hugonnet, Dominique Mengin- Lecreulx, Delphine Patin, Mélanie Ethève- Quelquejeu ...doi:10.1002/chem.201706082 pmid:29389045 fatcat:nqpv3prpyfdorht3plnj7tggp4
A set of new heteroquinone derivatives bearing two methoxycarbonylmethylthio groups on the benzoquinone ring were synthesized and evaluated for CDC25B phosphatase inhibitory activity. All compounds inhibited the enzyme with IC50 values in the micromolar range regardless of the size and heteroatoms constituting the heterocycle fused to the quinone ring. Moreover, these quinonoid-based compounds showed moderate antiproliferative activity toward two cancer cell lines (HeLa and MiaPaca-2). Thesedoi:10.5155/eurjchem.2.4.433-440.400 fatcat:w3kwchpr75d67e3iij7i2gftwq
more »... ults provide additional data for CDC25 inhibition by quinone-type derivatives and highlight the importance of substituents on the quinonic moiety. Heterocyclic quinones CDC25B inhibitors Enzymatic activity Phosphatase Cancer Cell cycle
.; Braud, E.; Ethève-Quelquejeu, M.; Tisné, C. Bisubstrate analogues as structural tools to investigate m 6 A methyltransferase active sites. RNA Biol. 2019, 16, 798-808. ...doi:10.3390/molecules25143241 pmid:32708658 fatcat:5yw5ubp22bepppqbneydcjsr3i
We studied the phenotype and activity of cord blood natural killer (NK) cells in newborns congenitally infected with Trypanosoma cruzi. We found that the proportion of CD56 bright NK cells was significantly decreased in cord blood from these newborns, suggesting they may have been recruited to secondary lymphoid organs. The remaining CD56 bright NK cells exhibited a defective ability in the production of interferon (IFN)-␥ following in vitro activation with interleukin (IL)-12 ϩ IL-2 or IL-12 ϩdoi:10.1203/01.pdr.0000220335.05588.ea pmid:16690951 fatcat:aw7e3xtexngndln5hz3jd5obay
more »... IL-15 cytokines, as compared with NK cells from uninfected newborns. In addition, cord blood NK cells from congenitally infected newborns stimulated with cytokines have a decreased release of granzyme B (GrB) when incubated with K562 target cells. This defect in cytotoxic effector function is associated with a reduced surface expression of activating NK receptors (NKp30, NKp46, and NKG2D) on CD56 dim NK cells compared with uninfected newborns. These alterations of fetal NK cells from congenitally infected newborns may reflect a down-regulation of the NK cell response after an initial peak of activation and could also be the result of T. cruzi modulating the immune response. (Pediatr Res 60: 38-43, 2006)
2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz)
Sergey Mitryukovskiy 1 , Mélanie Lavancier 1 , Flavie Braud 1 , Théo Hannotte 1 , Emmanuel Dubois 1 , Jean-François Lampin 1 , and Romain Peretti 1 1 IEMN, CNRS, Université de Lille, Villeneuve d'Ascq ...doi:10.1109/irmmw-thz.2019.8874026 fatcat:2ft7pjv3fnb6zk4vltehdrje24
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