Filtering Properties Research Articles

A Gap-Junction Mutation Reveals That Outer Hair Cell Extracellular Receptor Potentials Drive High-Frequency Cochlear Amplification.

Cochlear amplification enables the enormous dynamic range of hearing through amplifying cochlear responses to low- to moderate-level sounds and compressing them to loud sounds. Amplification is attributed to voltage-dependent electromotility of mechanosensory outer hair cells (OHCs) driven by changing voltages developed across their cell membranes. At low frequencies, these voltage changes are dominated by intracellular receptor potentials (RPs). However, OHC membranes have electrical low-pass filter properties that attenuate high-frequency RPs, which should potentially attenuate amplification of high-frequency cochlear responses and impede high-frequency hearing. We made in vivo intracellular and extracellular electrophysiological measurements from the organ of Corti of male and female mice of the CBA/J strain, with excellent high-frequency hearing, and from the CD-1 mouse strain, which has sensitive hearing below 12 kHz but loses high-frequency hearing within a few weeks postpartum. The CD-1 mouse strain was transfected with an A88V mutation of the connexin 30 gap-junction protein. By blocking the action of the GJ protein to reduce input resistance, the mutation increased the OHC extracellular RP (ERP) magnitude and rescued high-frequency hearing. However, by increasing the organ of Corti resistance, the mutation rescued high-frequency hearing through preserving the OHC extracellular RP (ERP) magnitude. We measured the voltage developed across the basolateral membranes of OHCs, which controls their electromotility, for low- to high-frequency sounds in male and female mice of the CD-1 strain that expressed the A88V mutation. We demonstrate that ERPs, not RPs, drive OHC motility and cochlear amplification at high frequencies because at high frequencies, ERPs are not frequency attenuated, exceed RPs in magnitude, and are appropriately timed to provide cochlear amplification.SIGNIFICANCE STATEMENT Cochlear amplification, which enables the enormous dynamic range of hearing, is attributed to voltage-dependent electromotility of the mechanosensory outer hair cells (OHCs) driven by sound-induced voltage changes across their membranes. OHC intracellular receptor potentials are electrically low-pass filtered, which should hinder high-frequency hearing. We measured the intracellular and extracellular voltages that control OHC electromotility in vivo in a mouse strain with impaired high-frequency hearing. A gap-junction mutation of the strain rescued high-frequency hearing, increased organ of Corti resistance, and preserved large OHC extracellular receptor potentials but reduced OHC intracellular receptor potentials and impaired low-frequency hearing. We concluded intracellular potentials drive OHC motility at low frequencies and extracellular receptor potentials drive OHC motility and cochlear amplification at high frequencies.

Innovative air purification by separation of gas-dust heterogeneous systems

The article analyzes the anomalous phenomena of nature, which are largely associated with the growing destructive, sometimes criminal in relation to nature, activity of "man" in the interests of irrepressible personal enrichment, through predatory extraction of all types of natural resources. Attention is drawn to the need to assess the activities of hundreds of thousands of facilities around the world that generate discharges into reservoirs and emissions into the atmosphere of various harmful inclusions in their production processes. Examples of recognized world leaders in the field of filtration technologies with vast experience, high scientific and technical potential of engineering staff and management are given. The design and technological features of existing modern filters are considered in detail. The requirements for the properties of filters of new generations and their cleaning capabilities are formulated. The distinctive aerodynamic properties of gases and dispersed inclusions used in FAD-G filters are considered in detail, the aerodynamics of gas media in them is considered and the results of research and testing of these models are analyzed. In conclusion, the signs and properties of new generations of FAD-G are analyzed, the world novelty of the invention and possible applications in our country are noted. Any abbreviations are prohibited. The abstract should reflect not only the relevance of the topic, but also contain a summary of the article material. Please focus on this. Use the expressions "The author is represented by...", "In the article...", etc. The abstract should be at least 200 words long

Polyimide/ZnO composite cooperatively crosslinked by Zn2+ Salt-Bondings and hydrogen bondings for ultraflexible organic solar cells

High power conversion efficiency (PCE), operational stability and low cost are essential for the commercial application of ultraflexible organic solar cells (OSCs), but it is still challenging to realize these purposes simultaneously. Here, a high-performance polyimide (PI)/ZnO composite (PI-ZnO) was prepared via introducing ZnO nanocrystals to an elaborately designed PI with both hydrogen bondings and abundant carboxyl groups (PI-COOH), where the fabrication cost of the PI-COOH was reduced by using common solvent under air atmosphere. With the UV absorption of ZnO nanocrystals, Zn2+ salt-bondings (formed via carboxyl ligand exchanges) and strong hydrogen bondings integrated in the single material, the PI-ZnO showed outstanding solvent-resistant, mechanical, thermal, and UV filtering properties. An untraflexible OSC with an optimal PCE of 13.55 % (average of 13.42 %) was constructed based on the AgNWs semi-embedded ultrathin flexible transparent composite electrode (FTCE, ∼ 6 μm). The ultraflexible OSC showed outstanding mechanical stability (PCE decreased by less than 5 % after 4000 bending cycles at a small bending radius of 1 mm) and superior UV light stability (PCE decreased by only ∼3 % after UV light irradiation for 6 h). This work would provide a new approach for fabricating high-performance, stable and low-cost ultraflexible OSCs.

Detection of the angle-of-arrival of an optical beam by means of interference optical filters for free-space optical communication.

We propose a method for estimating the angle-of-arrival of an optical beam, which is based on angle-dependent properties of interference optical filters. One-filter and two-filter configurations for beam angle detection in one plane were investigated experimentally. By using off-the-shelf interference filters and a laser beam with a 4 nm broad spectrum at a 1030 nm center wavelength, an angle detection range of 1.6°-2.3° was achieved with an angle detection uncertainty standard deviation of <0.2% of the total beam angle detection range. The performance of the proposed beam angle detection method was compared with that of the segmented detector method under conditions of air turbulence. It was found that the proposed method is more resistant to turbulence-caused beam distortions and allows determination of the beam angle with higher precision.

Mechanically and Ultraviolet Light Stable Ultrathin Organic Solar Cell via Semi-Embedding Silver Nanowires in a Hydrogen Bonds-Based Polyimide.

Ultrathin organic solar cells (OSCs) with both high power conversion efficiency (PCE) and operational stability are of great significance for the industrial applications but still challenging. Here, a polyimide (PI) substrate for high-performance and stable ultrathin OSCs, which is physically crosslinked via strong hydrogen bonds (denoted as HB-PI) to enhance the mechanical, thermal, solvent-resistant, and UV filtering properties (with a cut-off wavelength of 376nm), is synthesized. An ultrathin flexible transparent composite electrode (FTCE, ≈7µm) is fabricated via semi-embedding AgNWs in the HB-PI substrate. The FTCE possesses excellent optoelectronic property, smooth surface, and high mechanical stability simultaneously. Based on this FTCE, an ultrathin OSC is constructed with a PCE of 13.52% (average of 13.22%). Moreover, the ultrathin OSC shows outstanding mechanical stability (PCE decreased by less than 4% after 1000 bending cycles at a small bending radius of 0.5mm) and superior UV light stability (no evident PCE degradation after irradiation under UV light for 10h). This work will provide a new avenue for fabricating high-performance and stable ultrathin OSCs.

Plasma-based GHz tunable bandstop filter

Tunability is an important feature for the filter. As a special electromagnetic medium, the plasma has its permittivity being altered in a wideband range. In this work, based on the surface plasmon polaritons of plasma–dielectric–plasma waveguides, we propose a double-stubs structure submerged in a gaseous discharge plasma medium to realize tunable filtering properties in the giga-hertz (GHz) regime. The finite element method is applied to numerically compute filtering properties. The coupled mode theory and orthogonal design method are introduced to verify simulation results and estimate the effect of simulation parameters on the filtering properties. It is shown that the height of two stubs has the most important influence on filtering performance. Although once the filter is fabricated, its size cannot be modified, one can, nevertheless, vary the plasma frequency to effectively adjust the plasma frequency for the best filtering. Thus, such a plasma-modified filter provides a feasible scheme to dynamically adjust the filtering frequency.

The properties of a tunable terahertz filter based on a photonic crystal with a magnetized plasma defect layer

Tunable terahertz (THz) filtering properties of a single channel filter are investigated. The filter structure is based on a defective photonic crystal. The defect layer is assumed as a magnetized plasma medium. The photonic crystal has the structure of (Dielectric–Dielectric)L Plasma (Dielectric–Dielectric)L, where L is the number of unit cells on both sides of the plasma layer. The tunability of the defect mode is studied for various magnetic fields, plasma densities, and thicknesses of the plasma layer. We found that as the applied magnetic field increases, the defect modes shift to a higher frequency. Moreover, the defect modes shift to a shorter frequency as the plasma density or the plasma layer thickness increases. This article provides the theoretical basis for designing a tunable filter or a sensor depending on the parameters used at the THz range.

Enhanced-Stopband Dual-Polarized Filtenna Without Extra Circuit for Tile Array Applications

In this communication, a dual polarized (DP) stacked patch filtenna (filtering antenna) with a wide stopband is developed for tile array applications. The bandpass filtering property is realized by improving the feeding network and patch without adding extra bandpass circuit or size. An elaborate feeding structure with complementary pair of a short-circuited stub and an open-circuited stub (CSSOS) is developed, which generates two transmission nulls effectively enhancing the selectivity and suppressing the harmonic. Moreover, CSSOS has a small size and broadens the impedance bandwidth apparently by introducing an in-band resonance. By properly etching four U-shaped slots on the driven patch, a radiation null in the upper stopband is also generated. The nulls generated by the two approaches can be adjusted independently in wide ranges. For further harmonic suppression, bandstop striplines (BSSs) with ultralow insertion loss are developed. Measured results show that the filtenna performs a wide operating band (3.10–3.95 GHz) and a wide stopband up to 8 GHz with a rejection level higher than 16 dB. Besides, a 32-element tile phased array employing the filtennas is also fabricated and measured. A compact configuration, high selectivity, and good beam steering capacity are exhibited.

Filtering the NMR Spectra of Mixtures by Coordination to Paramagnetic Cu2.

The paramagnetic spin relaxation (PSR) filter allows the selective NMR signal suppression of components in mixtures according to their complexation ability to a paramagnetic ion. It relies on the faster relaxation of nuclei in paramagnetic environments and thus is complementary to classical diffusion and relaxation filters. So far, the PSR filter has established Gd3+ as the sole PSR agent, restricting the paramagnetic filtering repertoire. Herein, we present Cu2+ as a robust PSR agent with characteristic filtering properties. While Gd3+ depends on unspecific ion-pair interactions with anionic components, Cu2+ stands out for filtering species via ordered coordination complexes. An evaluation of the paramagnetic effect of Cu2+ over more than 50 small molecules and polymers has unveiled different sensitivities to Cu2+ (especially high for pyridines, diamines, polyamines, and amino alcohols) and precise filtering conditions for mixtures (1H, COSY, and HMQC) that were challenged with a test bed of commercial drugs. The advantage of integrating Cu2+ and Gd3+ for the stepwise PSR filtering of complex mixtures is also shown.

Enhancement of pozzolanic clay ceramic membrane properties by niobium pentoxide and titanium dioxide addition: Characterization and application in oil-in-water emulsion microfiltration

Pozzolanic clay was mixed with niobium pentoxide (Nb2O5) and titanium dioxide (TiO2) to improve the filtering properties of disk-type ceramic membranes, in 0.1 g L−1 oil-in-water emulsion. The effect of sintering temperatures of 1000 °C, 1100 °C and 1150 °C was evaluated. The newly formed hydrophilic membranes were fully characterized in terms of porosity, mechanical strength, X-ray fluorescence (XRF), X-ray diffraction (XRD), thermogravimetric analysis (TGA), water contact angle, scanning electron microscopy (SEM), atomic force microscopy (AFM), and hydraulic permeability. The applicability of the developed membranes was evaluated using crossflow microfiltration (MF) of an oil-in-water emulsion. The results demonstrated that the membranes could offer higher permeate fluxes with low permeate TOC contents that were compliant with that reported in the literature. The niobium pentoxide increased the hydraulic permeability and initial permeate flux by up to 118% and 72%, respectively, compared with the pure clay membranes. The pore blocking models were adjusted to the MF data of the membranes sintered at 1100 °C, revealing that the intermediate pore blocking was the major fouling mechanism for pure clay and niobium pentoxide enriched membranes, while complete pore blocking was best fitted to the titanium dioxide containing membrane. Overall, the results demonstrated that the mixing of pozzolanic clay and niobium pentoxide has great potential.

Excellent long-wavelength-pass filters of CsPbBr3 and CsPb(Cl/Br)3 quantum dot glasses by a Cu2+ quenching strategy

Perovskite C s P b B r 3 quantum dot (QD) glasses doping C u 2 + are reported for excellent long-wavelength-pass filters. Transmittance, optical density (OD), photoluminescence (PL), PL excitation, and PL decay are used to investigate filter properties and the quenching mechanism. At low C u 2 + molar concentrations of 0%, 0.0025%, 0.005%, and 0.01%, the filters exhibit good properties in transmittance and OD. Transition wavelengths are 518, 513, 513, and 512 nm, respectively. The shape and position of transmittance and OD are almost not changed. As C u 2 + concentration increases, PL intensity is monotonously quenched. PL decay is obviously faster. The quenching mechanism is dynamic quenching, which is electron transfer from QDs to C u 2 + . In comparison with the initial intensity, the intensity decreases by factors of 7.6, 12.8, and 18.8. Oxidation and reduction atmospheres are introduced, and the dynamic quenching mechanism is further confirmed. At high C u 2 + concentrations of 0.013%–0.02%, the quenching mechanism is static quenching. Double-anion C s P b ( C l / B r ) 3 QD glasses of different C u 2 + concentrations extend the operation wavelength to the blue light region. For C u 2 + concentrations of 0%, 0.005%, and 0.01%, the transition wavelengths are 470, 472, and 473 nm for C s P b ( C l / B r ) 3 (NaCl as Cl source) QD glasses, and 430, 426, and 445 nm for C s P b ( C l / B r ) 3 ( P b C l 2 as Cl source) QD glasses, respectively.

Study of the aerosol particle filtration efficiency of fabrics used to manufacture non-medical face masks in Lithuania

The global spread of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) proved to be a challenge for public health. The high demand of medical masks worldwide during the pandemic has led to a critical situation for decision-makers regarding high-quality mask supply. For this period, the World Health Organization has suggested the use of non-medical face masks (also known as ‘community’ masks) in public places to reduce the airborne spread of SARS-CoV-2. In this study, the filtration efficiency of various fabrics widely used in community masks was determined based on two main mask filtering properties: filtration efficiency (FE) and pressure drop (ΔP) according to the recommendations of the CEN Workshop Agreement (CWA) 17553:2020. The combination of FE and ΔP parameters must be considered in order to select suitable materials for public masks. The filtration efficiencies for various fabrics ranged from 6 to 100%. It was found that the composite materials have the highest FE equivalent to the requirements of a medical mask (FE &gt; 95%), that is confirmed by high-quality parameters 16–30 kPa–1. The study found that fabrics of natural fibres (100% cotton) have a higher FE with Ag coating (18–40% before and 29–40% after coating) in the 0.54–1.50 μm particle size range.

Focal shifts in thin film filters for MUX/DEMUXs.

Optical properties of thin film filters (TFFs) are investigated for the design of multiplexer/demultiplexers (MUX/DEMUXs) in a zigzag configuration. Focal shifts are observed in reflection and transmission of the TFFs, and the focal shifts in reflection can be explained by reflection and refraction effects of the curved surfaces of the TFFs, while the focal shifts in transmission are significantly larger than those by the refraction effects of the curved surfaces. The focal lengths are calculated using a transmission model of TFFs, and it is confirmed that they are equal to the focal lengths obtained from the transmission loss trends.

Sparse DDK: A Data-Driven Decorrelation Filter for GRACE Level-2 Products

High-frequency and correlated noise filtering is one of the important preprocessing steps for GRACE level-2 products before calculating mass anomaly. Decorrelation and denoising kernel (DDK) filters are usually considered as such optimal filters to solve this problem. In this work, a sparse DDK filter is proposed. This is achieved by replacing Tikhonov regularization in traditional DDK filters with weighted L1 norm regularization. The proposed sparse DDK filter adopts a time-varying error covariance matrix, while the equivalent signal covariance matrix is adaptively determined by the Gravity Recovery and Climate Experiment (GRACE) monthly solution. The covariance matrix of the sparse DDK filtered solution is also developed from the Bayesian and error-propagation perspectives, respectively. Furthermore, we also compare and discuss the properties of different filters. The proposed sparse DDK has all the advantages of traditional filters, such as time-varying, location inhomogeneity, and anisotropy, etc. In addition, the filtered solution is sparse; that is, some high-degree and high-order terms are strictly zeros. This sparsity is beneficial in the following sense: high-degree and high-order sparsity mean that the dominating noise in high-degree and high-order terms is completely suppressed, at a slight cost that the tiny signals of these terms are also discarded. The Center for Space Research (CSR) GRACE monthly solutions and their error covariance matrices, from January 2004 to December 2010, are used to test the performance of the proposed sparse DDK filter. The results show that the sparse DDK can effectively decorrelate and denoise these data.

A Wideband Coplanar L-Probe-Fed Slot-Loaded Rectangular Filtering Microstrip Patch Antenna With High Selectivity

A coplanar L-probe slot-loaded wideband filtering microstrip antenna is proposed in this letter. The filtering properties are realized by the introduction of four slots and a coplanar L-probe. A standard TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">20</sub> mode is excited to attain the radiation null at the lower band. Moreover, a standard TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</sub> mode and the L-probe contribute to the two radiation nulls at the upper band. The slots also excite new resonant modes to enhance the bandwidth of the antenna. The analysis reveals that a traditional TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01</sub> mode and a reshaped TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</sub> mode are excited and couple with each other to realize a wide bandwidth. The measurements reveal that the proposed antenna has a 10 dB impedance bandwidth of 14% from 2.32 to 2.63 GHz with a peak gain of 9.24 dBi at 2.48 GHz. The gain variation is less than 1 dB within the passband. The advantages of simple structure, coplanar, easy fabrication make the proposed antenna suitable for various wireless communication systems.

P-points, MAD families and Cardinal Invariants

P-points, MAD families and Cardinal Invariants

Multiplication and Accumulation Co-Optimization for Low Complexity FIR Filter Implementation

In multiplierless finite impulse response (FIR) filters, the product accumulation block (PAB) could be the major contributor to hardware complexity, especially for high-order filters. In this paper, an optimization scheme where the constant multiplication block and the PAB are jointly optimized at the bit-level is proposed to minimize the hardware complexity. In the proposed joint optimization, the multiple constant multiplications (MCM) block is rearranged into several MCM sub-blocks. The products are summed locally before accumulation to reduce the word-length of the structural adders. It is shown that the symmetric property of linear phase FIR filters can be utilized in some cases to further reduce the complexity of the constant multiplications. Quantitative analyses are also presented to study the relationship between the optimum group size and the coefficient values as well as the filter orders. It is shown that there is no fixed optimum structure for filters with different coefficient word-lengths and filter orders, and each filter needs to be optimized specifically to achieve the minimum hardware complexity. Implementation results are presented to validate the effectiveness of the proposed method.

Cortical adaptation to sound reverberation.

In almost every natural environment, sounds are reflected by nearby objects, producing many delayed and distorted copies of the original sound, known as reverberation. Our brains usually cope well with reverberation, allowing us to recognize sound sources regardless of their environments. In contrast, reverberation can cause severe difficulties for speech recognition algorithms and hearing-impaired people. The present study examines how the auditory system copes with reverberation. We trained a linear model to recover a rich set of natural, anechoic sounds from their simulated reverberant counterparts. The model neurons achieved this by extending the inhibitory component of their receptive filters for more reverberant spaces, and did so in a frequency-dependent manner. These predicted effects were observed in the responses of auditory cortical neurons of ferrets in the same simulated reverberant environments. Together, these results suggest that auditory cortical neurons adapt to reverberation by adjusting their filtering properties in a manner consistent with dereverberation.

Obtaining modified sorbents based on natural raw materials of Kazakhstan and research of their properties

With the huge explored reserves of potash salts in Kazakhstan, there is still no production of potash fertilizers, the demand for which is constantly growing. In this regard, research of processing of the largest Chelkar deposit ore into potash fertilizers and salts is an urgent problem. The article presents the research results of washed potash ore decomposition with nitric acid and nitric acid suspension filtration. The filtering properties and granulometric composition of the insoluble residue were studied, on what basis the decomposition mode with precipitate double washing was determined. To ensure good suspension filterability, washed, uncalcined ore should be used. Tests of a by-product, gypsum, as a gypsum binder were carried out, which confirmed its compliance with the normally hardening gypsum binder of the G-2 B grade. Advantage of the obtained gypsum is its environmental friendliness. Salts, which are chlorine-free water-soluble potassium-magnesium fertilizers have been obtained by crystallization from nitric acid solution. On the basis of results of experimental-and-laboratory tests, a basic flow scheme has been developed for obtaining potash and complex potassium-nitrogen-magnesium fertilizers from the Chelkar deposit ore.

Design and analysis of 1D photonic crystal doped with magnetized cold plasma defect for application of single/multi-channel tunable narrowband filter

The present research demonstrates the tunable filtering properties of a single/multi-channel filter based on 1D photonic crystal (PhC), which is designed with dielectric materials (A, B) and magnetized cold plasma (P). The proposed filter has a configuration of Transmission spectra of the structure is investigated for both right-hand polarization and left-hand polarization configurations of the plasma material by employing the well-known transfer matrix method. It is found that number of periods of the plasma layer (N) decides the single-channel and multi-channel operations of the filter. It is revealed that the external magnetic field can be manipulated to tune the frequency of the filter. Also, it is found that the geometrical parameters such as thickness of the plasma layer, plasma density, and incident angle play a significant role in tuning the defect mode frequency. Moreover, the color map plot is studied to provide a clear insight of shifting nature of the defect mode frequency. Quality factor of the filter is evaluated vis-à-vis different geometrical parameters. Our considered structure can be the mainstay for filtering applications in microwave regions, and can find suitable applications in dense wavelength division multiplexing and high speed signal processing.