RESUMEN
Precise photon flux measurement of single photon sources (SPSs) is essential to the successful application of SPSs. In this work, a novel method, to our knowledge, was proposed for direct measurement of the absolute photon flux of single photon sources with a femtosecond laser multiphoton microscope. A secondary 2-mm-diameter aperture was installed under the microscope objective to define the numerical aperture (NA) of the microscope. The defined NA was precisely measured to be 0.447. An LED-based miniaturized integrating sphere light source (LED-ISLS) was used as a standard radiance source to calibrate the photon flux responsivity of the multiphoton microscope, with the defined NA. The combined standard uncertainty of the measured photon flux responsivity was 1.97%. Absolute photon flux from a quantum-dot based emitter was measured by the multiphoton microscope. The uncertainty of the photon flux was evaluated to be 2.1%. This work offers a new, to our knowledge, radiometric method for fast calibration of photon flux responsivity of microscopes, and absolute photon flux calibration of single photon sources.
RESUMEN
Time-of-flight method was adopted to measure the distance between two parallel precision apertures utilized in a vacuum chamber for cryogenic radiometry. The diameters of the apertures are 9â mm and 8â mm, respectively. A 1550-nm femtosecond pulse laser, a 70-GHz photodetector, and a 30-GHz oscilloscope were used to measure the round-trip flight time difference between the flat front surfaces of the two precision apertures. The distance between the apertures was analyzed to be 0.36423 m with a relative standard uncertainty of 0.004%. The non-contact distance measurement method is useful for applications such as low background infrared radiance measurement system based on an absolute cryogenic radiometer.
RESUMEN
LED-based integrating sphere light sources (LED-ISLSs) in the size of typical microscope slides were developed to calibrate the radiance responsivity of optical imaging microscopes. Each LED-ISLS consists of a miniaturized integrating sphere with a diameter of 4â mm, an LED chip integrated on a printed circuit board, and a thin circular aperture with a diameter of 1â mm as the exit port. The non-uniformity of the radiant exitance of the LED-ISLSs was evaluated to be 0.8%. The normal radiance of the LED-ISLSs in the range of (5â¼69) W m-2 sr-1 was measured with a standard uncertainty of 1.3% using two precision apertures and a standard silicon photodetector whose spectral responsivity is traceable to an absolute cryogenic radiometer. The LED-ISLSs were applied to calibrate the radiance responsivity of a home-built optical imaging microscope with a standard uncertainty of 2.6â¼2.9%. The LED-ISLSs offer a practical way to calibrate the radiance responsivity of various optical imaging microscopes for results comparison and information exchange.
RESUMEN
Ultrathin metamaterials provide new possibilities for the realization of cloaking devices because of their ability to control electromagnetic waves. However, applications of metamaterials in cloaking devices have been limited primarily to reflection-type carpet cloaks. Hence, a transmissive free-space cloak was developed using a multilayer frame structure, wherein highly transparent metamaterials were used to guide incident waves into propagating around an object. The cloaking effect was quantitatively verified using near-field and far-field distributions. Metamaterials allow for the cloaking shells of transmissive cloaks to be developed without spatially varying extreme parameters. Moreover, a transmissive invisible cloak with metamaterial-based mirrors was designed. The design principle of this cloak with a frame structure consists of four metamaterial-based mirrors and two metal mirrors. After covered with the designed metamaterials-based mirrors cloak, the outgoing electromagnetic wave is restored greatly as if the wave passes directly through the obstacle without distortion. This cloak used the metamaterials mirrors to adjust the reflected angle, so that the outgoing electromagnetic wave does not change direction, thereby achieving the cloaking effect.
RESUMEN
Ultrathin metasurface provides a completely new path to realize cloaking devices on account of their fascinating ability to control electromagnetic wave. However, the conventional cloaking devices are limited by their narrow bandwidth. To overcome this challenge, we present the realization of ultrabroadband and wide angle metasurface cloaking through high refractive index dielectric layer and antireflective "moth-eye-like" microstructure in this work. Two options are proposed and demonstrated numerically in terahertz region. By using local phase compensation, the proposed carpet cloaks can suppress significantly the unexpected scattering and reconstruct wavefront. The cloaking effects of the proposed design are verified from 0.65THz to 0.9THz with a wide range of angles. Moreover, the proposed metasurface cloaking is probable to extend to the optical and microwave domains and can be applied in stealth, illusion optic, radar and antenna systems.
RESUMEN
Low permeability reservoirs are characterized by low permeability, small pore throat, strong heterogeneity, and poor injection-production ability. High shale content of the reservoir, strong pressure sensitivity, micropore undersaturation, and significant water-lock effect in water injection development lead to increased fluid seepage resistance. There is an urgent need to adopt physical and chemical methods to supplement energy and improve infiltration efficiency, thereby forming effective methods for increasing the production and efficiency. Aiming at the characteristics of ultralow permeability reservoirs, in this paper, a green and environmental friendly biobased profile control and displacement agent (Bio Nano30) has been developed using noncovalent supramolecular interaction. Physical simulation experiments illustrate the profile control and displacement mechanism of Bio-Nano30. Laboratory experiments and field applications show that good results have been achieved in oil well plugging removal, water well pressure reduction and injection increase, and well group profile control and oil displacement. This research has good application prospects in low permeability heterogeneous reservoirs.
RESUMEN
Phospho-specific primary antibodies are used in immunohistochemistry (IHC) to detect phosphorylated sequences in proteins, in some cases they may also cross-react with non- or de-phosphorylated sequences. To rule out nonspecific staining, and to determine that the staining pattern is specific it is necessary to employ a so-called absorption control: phospho-specific primary antibodies are first incubated with phospho-peptide immunogen to block antibody binding sites, and this mixture is applied to tissue sections. If the antibody pre-blocked with cognate immunogen does not produce tissue staining, then the antibody is considered specific. However, if the staining does occur, it indicates that the antibody is nonspecific. The drawback of doing absorption by mixing the peptide with the antibody is that in solution such peptide-antibody complexes can dissociate unblocking the antibody which becomes capable of binding to cell and tissue targets, producing unwanted staining. To overcome this problem, we have developed a simple absorption control technique allowing for efficient blocking of phospho-specific antibodies with phospho-peptides immobilized on magnetic beads. This technique allows for sequestration of peptide-antibody complex from the incubation mixture eliminating the risk of un-blocking primary antibodies via their dissociation from the blocking peptide.
Asunto(s)
Técnica del Anticuerpo Fluorescente , Inmunohistoquímica/métodos , Técnicas de Inmunoadsorción , Fosfopéptidos/metabolismo , Animales , Anticuerpos Fosfo-Específicos/inmunología , Ratones , Microscopía Confocal , Células 3T3 NIH , Fosfopéptidos/inmunologíaRESUMEN
Although phospho-specific primary antibodies used in immunohistochemistry (IHC) are expected to detect phosphorylated proteins, in some cases these antibodies may also cross-react with nonphosphorylated proteins. Therefore, it is of ultimate importance to employ a control to determine that the staining pattern is specific. One of the frequently used controls in IHC is a so-called absorption control: phospho-specific primary antibodies are first incubated with a phospho-peptide immunogen to block antibody-binding sites, and this mixture is subsequently applied to tissue sections. If the antibody blocked with cognate immunogen does not produce tissue staining, then the antibody is considered specific, but if staining is obtained, the antibody is considered nonspecific. Unfortunately, bound peptide can dissociate from the antibody allowing unblocked antibody to bind to tissue targets, producing unwanted staining. We have developed a simple absorption-control protocol allowing for the efficient neutralization of phospho-specific antibodies with phospho-peptides immobilized on magnetic beads. This technique allows for sequestration of antibody-peptide complex from the incubation solution, minimizing the risk of formation of unblocked antibodies capable of producing tissue staining.