Search results for: Letters
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Separate synthesis and evaluation of glucitol bis-phosphate and mannitol bis-phosphate, as competitive inhibitors of fructose bis-phosphate aldolases
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One Step Beyond: Design of Substrates Spanning Primed Positions of Zika Virus NS2B-NS3 Protease
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Combined Spectroscopic Methods of Determination of Density of Electronic States: Comparative Analysis of Diffuse Reflectance Spectroelectrochemistry and Reversed Double-Beam Photoacoustic Spectroscopy
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Naphtho[1′,2′:4,5]imidazo[1,2-a]pyridine-5,6-diones: Synthesis, enzymatic reduction and cytotoxic activity
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Symmetry-Dependent Vibrational Circular Dichroism Enhancement in Co(II) Salicylaldiminato Complexes
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Are Radicals Formed During Anion-Exchange Membrane Fuel Cell Operation?
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Use of hop cone extract obtained under supercritical CO2 conditions for producing antibacterial all-purpose cleaners
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Superconducting properties of under- and over-doped BaxK1−xBiO3 perovskite oxide
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The thermodynamic critical field and specific heat of superconducting state in phosphorene under strain
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Strong-coupling character of superconducting phase in compressed selenium hydride
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Revealing the anisotropy effects on the critical magnetic field in CaC6 superconductor
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The transition from HIF-1 to HIF-2 during prolonged hypoxia results from reactivation of PHDs and HIF1A mRNA instability
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A compact microstrip rat-race coupler constituted by nonuniform transmission lines
PublicationIn this work, a step-by-step development of a compact microstrip rat-race coupler (RRC) has been presented and discussed. A high degree of miniaturization has been obtained by substituting six quarter-wavelength uniform atomic building blocks of a RRC by their nonuniform counterparts. The miniaturization procedure has been realized in three progressive steps: (i) the first layout solution of a miniaturized RRC has been acquired...
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A robust design of a numerically demanding compact rat-race coupler
PublicationA fast and accurate design procedure of a computationally expensive microwave circuit has been presented step-by-step and experimentally validated on the basis of a compact rat-race coupler (RRC) comprising slow-wave resonant structures (SWRSs). The final compact RRC solution has been obtained by means of a sequential optimization scheme exploiting the implicit space mapping (ISM) algorithm. A well-suited surrogate optimization...
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Application of the discrete Green's function-based antenna simulations for excitation of the total-field/scattered-field interface in the FDTD method
PublicationIn this article, the discrete Green's function formulation of the finite-difference time-domain (DGF-FDTD) method is proposed for simulation of wire antennas irradiating inhomogeneous dielectric scatterers. Surface equivalence theorem in the discrete domain is used to separate the problem into an inhomogeneous domain and a wire antenna that are simulated with the use of FDTD and DGF-FDTD, respectively. Then, the excitation of the...
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Specific Binding of Cholesterol to the Amyloid Precursor Protein: Structure of the Complex and Driving Forces Characterized in Molecular Detail
PublicationC99 is the C-terminal membrane-bound fragment of the amyloid precursor protein that is cleaved by γ-secretase to release Aβ peptides, the hallmark of Alzheimer’s disease (AD). Specific interactions of C99 with cholesterol have been proposed to underlie the recognized role of cholesterol in promoting amyloidogenesis. By using molecular dynamics simulations, we studied cholesterol binding to C99 in a lipid bilayer. We determined...
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Miniaturized bandpass substrate integrated waveguide filter with frequency-dependent coupling realized using asymmetric GCPW discontinuity
PublicationAn asymmetric GCPW discontinuity is proposed to provide frequency-dependent coupling in microwave bandpass filters. Wider and narrow sections introduce, respectively, the capacitive and inductive component to the equivalent circuit representing coupling. By selecting the dimensions of the discontinuity and width of the inductive window in substrate integrated waveguide, an additional transmission zero can be introduced at prescribed...
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Synthesis and antiproliferative activity of conjugates of adenosine with muramyl dipeptide and nor-muramyl dipeptide derivatives
PublicationWe synthesized a series of MDP(D,D) and nor-MDP(D,D) derivatives conjugated with adenosine through a spacer as potential immunosuppressants. New conjugates were evaluated on two leukemia cell lines (Jurkat and L1210) and PBMC from healthy donors.
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In vitro studies of antimicrobial activity of Gly-His-Lys conjugates as potential and promising candidates for therapeutics in skin and tissue infections
PublicationWe presented in vitro studies of antimicrobial activity of Gly-His-Lys conjugates that are important point in preliminary biological evaluation of their potential application in skin and tissue therapy. The novel compounds include the conjugation of fatty acids with a modification of the amino acid sequence in the primary structure of Gly-His-Lys.
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Simulation and experiment of radiating slot in a ground-plane of microstrip junction
PublicationW pracy przedstawiono badania numeryczne oraz eksperymentalne szczeliny promieniującej umieszczonej w płaszczyźnie masy złącza mikropaskowego. Złącze mikropaskowe składa się z linii mikropaskowej oraz rozwartego na końcu sęka. Szczelina umieszczona jest równolegle do linii mikropaskowej.
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Design considerations for compact microstrip resonant cells dedicated to efficient branch-line miniaturization
PublicationA conventional compact microstrip resonant cell (CMRC)has been thoroughly investigated to enhance its slow-wave properties and subsequently ensure an efficient miniaturization of a microstrip circuit. The geometry of a classic CMRC has been improved in terms of slowwave effect in two progressive steps: (i) a single-element topology has been replaced with a double-element one and (ii) a high-impedance section has been refined by...
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IFF/SSR rectangular patch antenna with reduced transversal size
PublicationW artykule przedstawiono antenę mikropaskową dla systemów IFF/SSR, zasilaną poprzez szczelinę typu H. Zastosowanie tego typu szczeliny pozwoliło na 36-procentową redukcję wymiaru poprzcznego anteny,co jest szczególnie istotne ze względu na potencjalne zastosowanie anteny w szykach.Pomierzone parametry eektryczne anteny to: VSWR < 1.5; stosunek polaryzacji ortogonalnej do właściwej < 30 dB w obu płaszczyznach;zysk > 7 dBi.
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Novel topology of compact coplanar waveguide resonant cell low-pass filter
PublicationIn this study, a novel pseudoelliptic function low-pass filter (LPF) constituted by a compact coplanar waveguide resonant cell has been designed and manufactured. The lumped-element seven-pole prototype has been adequately realized by using complementary perturbations located both in signal line and ground plane metallization. The fabricated uniplanar LPF offers a compact size of 5.6 x 9.8 mm2, return loss better than 26 dB over...
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Doubly miniaturized rat-race hybrid coupler
PublicationTwo complementary miniaturization techniques have beenapplied to reduce the size of a rat-race hybrid coupler: (i) conventional microstrip sections have been replaced with their diminished lowimpedance counterparts as the first step of size reduction and (ii) novel fractal-shaped compact microstrip resonant cells dedicated to efficiently shorten low-impedance transmission line segments have been implemented as the second step of...
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Design of a broadband microstrip crossover for ultra-wideband applications
PublicationW pracy przedstawiono badania skrzyżowań linii mikropaskowych do zastosowań w systemach UWB. W procedurze projektowej wykorzystany został model zastępczy skrzyżowania. W celu poprawy parametrów skrzyżowań zaprojektowano dwie konfiguracje obwodów kompensujących. Wyniki numeryczne zweryfikowane zostały eksperymentalnie. Uzyskano dobrą zgodność pomiędzy rezultatami symulacji oraz pomiarów.
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Slow-wave fractal-shaped compact microstrip resonant cell
PublicationA novel fractal-shaped compact microstrip resonant cell (CMRC) featuring a strong slow-wave effect has been presented. Its vital usefulness in the process of microstrip line miniaturisation has been proved and experimentally validated on the basis of a compact 3-dB branch-line coupler illustrating the possibilities of the approach. A prototype example structure has been designed to mirror the characteristics of a conventional device,...
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Effect of ground plane size on radiation pattern in IFF/SSR microstrip antenna on thick substrate fed by H type slot
PublicationW pracy pokazano numeryczne i eksperymentalne wyniki badania wpływu rozmiarówmasy na charakterystyki promieniowania anteny dla zastosowań IFF/SSR, zrealizowanej na grubym podłożu i zasilanej przez szczelinę typu H. Pokazane wyniki dla anteny oryginalnej porównano z wynikami uzyskanymi po zmniejszeniu wymiarów masy (w każdym z kierunków). Pokazano jak dalece można zminimalizować wymiary anteny, przy założonym poziomie listków bocznych.
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Determinants of Directionality and Efficiency of the ATP Synthase Fo Motor at Atomic Resolution
PublicationFo subcomplex of ATP synthase is a membrane-embedded rotary motor that converts proton motive force into mechanical energy. Despite a rapid increase in the number of high-resolution structures, the mechanism of tight coupling between proton transport and motion of the rotary c-ring remains elusive. Here, using extensive all-atom free energy simulations, we show how the motor’s directionality naturally arises from the interplay...
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Guanosine Dianions Hydrated by One to Four Water Molecules
PublicationIntermolecular interactions such as those present in molecule···water complexes may profoundly influence the physicochemical properties of molecules. Here, we carried out an experimental–computational study on doubly deprotonated guanosine monophosphate···water clusters, [dGMP – 2H]2–·nH2O (n = 1–4), using a combination of negative anion photoelectron spectroscopy (NIPES) with molecular dynamics (MD) and quantum chemical (QM) calculations....
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Miniaturized dual‐band branch‐line coupler with enhanced bandwidth
PublicationIn this letter, a miniaturized hybrid dual-band branch-line coupler (BLC) with enhanced fractional bandwidths is proposed. Compact size and bandwidth enhancement are obtained using meandered transmission line sections with broken symmetry between cross-coupling branches. The circuit is designed at a low numerical cost using surrogate-assisted techniques. The optimized design features small size of only 0.25λg×0.19λg(28% miniaturization...
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Novel structure and design of enhanced-bandwidth hybrid quadrature patch coupler
PublicationA novel structure and design optimization procedure of an enhanced-bandwidth hybrid quadrature patch coupler is proposed. Improved performance of the circuit has been obtained by parameterizing the coupler sections using splines, which introduces additional degrees of freedom. Due to computational complexity of the parameter adjustment problem, a sequential design procedure is applied. In each iteration, a selected number of spline...
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On the plastic buckling of curved carbon nanotubes
PublicationThis research, for the first time, predicts theoretically static stability response of a curved carbon nanotube (CCNT) under an elastoplastic behavior with several boundary conditions. The CCNT is exposed to axial compressive loads. The equilibrium equations are extracted regarding the Euler–Bernoulli displacement field by means of the principle of minimizing total potential energy. The elastoplastic stress-strain is concerned...
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Ab initio chemical kinetics of Isopropyl acetate oxidation with OH radicals
PublicationGlobal reactivity descriptors of isopropyl acetate (IPA) and thermo-kinetic aspects of its oxidation via OH radicals have been studied. Transition state theory (TST) was utilized to estimate the bimolecular rate constants. Ten oxidation pathways have been investigated, and all of them are exothermic. The potential energy diagram has been sketched using different pre- and post-reactive complexes for all reaction pathways. Rate coefficient...
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Dissociative Electron Attachment to 5-Iodo-4-thio-2′-deoxyuridine: A Potential Radiosensitizer of Hypoxic Cells
PublicationIn the search for effective radiosensitizers for tumor cells, halogenated uracils have attracted more attention due to their large cross section for dissociation upon the attachment of low-energy electrons. In this study, we investigated dissociative electron attachment (DEA) to 5-iodo-4-thio-2'-deoxyuridine, a potential radiosensitizer using a crossed electron-molecule beam experiment coupled with quadrupole mass spectrometry....
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Electromagnetic wave scattering by a set of axially symmetric omega-medium cylinder
PublicationZaprezentowano analizę rozproszenia fali elektromagnetycznej od układu obiektów cylindrycznych zbudowanych z materiałów pseudochiralnych, umieszczonych w złączach falowodowych lub wolnej przestrzeni. Analiza bazuje na iteracyjnej procedurze rozproszenia i metodzie dopasowania rodzajów.
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Radiation phenomena from pseudochiral cylinders at plane wave incidence
PublicationPrzedstawiono wpływ materiałów pseudochiralnych na charakterystyki rozproszenia fali elektromagnetycznej od obiektów cylindrycznych. W celu zbadania zjawisk rozproszenia zastosowano kombinacje iteracyjnej procedury rozproszenia i metodę dopasowania rodzajów. Wpływ zastosowania materiałów pseudochiralych w konfiguracjach obiektów cylindrycznych zaprezentowano na charakterystykach pola rozproszonego w strefie dalekiej oraz na charakterystykach...
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Endothelial dysfunction due to eNOS uncoupling: molecular mechanisms as potential therapeutic targets
PublicationNitric oxide (NO) is one of the most important molecules released by endothelial cells, and its antiatherogenic properties support cardiovascular homeostasis. Diminished NO bioavailability is a common hallmark of endothelial dysfunction underlying the patho‑ genesis of the cardiovascular disease. Vascular NO is synthesized by endothelial nitric oxide synthase (eNOS) from the substrate L‑arginine (L‑Arg), with tetrahydrobiopterin...
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Why Are Left-Handed G-Quadruplexes Scarce?
PublicationG-quadruplexes (G4s) are nucleic acid structures crucial for the regulation of gene expression and genome maintenance. While they hold promise as nanodevice components, achieving desired G4 folds requires understanding the interplay between stability and structural properties, like helicity. Although right-handed G4 structures dominate the experimental data, the molecular basis for this preference over left-handed helicity is unclear....
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The immunoregulatory effects of edeine analogues in mice
PublicationZbadano właściwości immunoregulatorowe kilku, otrzymanych na drodze syntezy, uproszczonych analogów peptydowego antybiotyku edeiny w testach in vivo i in vitro z wykorzystaniem modelu mysiego. Jako związek referencyjny zastosowano edeinę B. Otrzymane peptydy wykazywały efekt stymulacyny na proliferację splenocytów z użyciem konkawaliny, podczas gdy zastosowanie mitogenu powodowało hamowanie proliferacji splenocytów. Peptydy hamowały...
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A novel compact broadband 5-35GHz
PublicationW artykule przedstawiono zasadę pracy oraz procedurę projektowania zintegrowanego planarnego baluna (symetryzatora). Układ zaprojektowano wykorzystując połączenie linii paskowych i szczelinowych oraz struktury rezonatorów w formie wielogałęziowych sęków szczelinowych. Wykonany wielowarstwowy symetryzator pracuje poprawnie w zakresie 5-35GHz.
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Compact-planar monopole loop antennas for 802.11b/g WLAN systems
PublicationZaproponowano planarne anteny monopolowe dla systemów komunikacji bezprzewodowej WLAN pracujących w pasmach 2.45GHz i 5.25GHz. W strukturze radiatorów zasilanych poprzez linię mikropaskową wykorzystano krzywe fraktalne: pętlę Kocha oraz pętlę Minkowskiego. W obu przypadkach uzyskano dwuzakresową pracę anten dzięki wprowadzeniu nowej konfiguracji zminiaturyzowanych transformatorów impedancji w układzie zasilania.
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Investigations of the circulation effects in the structure using ferrite coupled slot-line section
PublicationW artykule przedstawiono badania cyrkulatora zrealizowanego w oparciu o magnesowaną wzdłużnie sekcję ferrytowych szczelinowych linii sprzężonych. Zaproponowane rozwiązanie pozwala na minimalizację rozmiarów układu cyrkulatora oraz na uzyskanie parametrów porównywalnych z dotychczas publikowanymi. W treści artykułu opisano kolejne etapy projektu. Wyniki numeryczne zweryfikowano eksperymentalnie. Pomierzony układ charakteryzował...
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A simple way of increasing estimation accuracy of generalized adaptive notch filters
PublicationGeneralized adaptive notch filters are used for identification/tracking of quasi-periodically varying dynamic systems and can be considered an extension, to the system case, of classical adaptive notch filters. It is shown that frequency biases, which arisein generalized adaptive notch filtering algorithms, can be significantly reduced by incorporating in the adaptive loop an appropriately chosen decision delay. The resulting performance...
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Microstrip line with short-circuited edge as a high-pass filter operating up to millimeter-wave frequencies
PublicationPrzedstawiono prosty planarny filtr górnoprzepustowy wykorzystujący linię mikropaskową ze zwartym brzegiem. Układy zaprojektowano w taki sposób, aby pasmo przepustowe rozpoczynało się w zakresie K lub Ka. Wykonano dwa prototypy: na podłożu w postaci warstwy dielektrycznej wykonanej z ceramiki alundowej oraz na podłożu organicznym o niskiej przenikalności elektrycznej. Wykazano dużą zgodność teoretycznych i pomierzonych charakterystyk...
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Low-Barrier Hydrogen Bond Determines Target-Binding Affinity and Specificity of the Antitubercular Drug Bedaquiline
PublicationThe role of short strong hydrogen bonds (SSHB) in ligand-target binding remains largely unexplored, thereby hin- dering a potentially important avenue in the rational drug de- sign. Here, we investigate the interaction between bedaquiline (Bq), a potent anti-tuberculosis drug, and the mycobacterial ATP synthase, to unravel the role of a specific hydrogen bond to a conserved acidic residue in the target affinity and specificity....
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Comments on “Closed Form Variable Fractional Time Delay Using FFT”
PublicationIn this letter drawbacks of the aforementioned paper are pointed out. The proposed approach is improved with minor modifications of the discrete frequency response. This allows for design of fractional delay filters which are close to optimal and can be efficiently implemented in the frequency domain using the sliding DFT based structure. Alternatively, the derived equivalent closed form formulae for offset windows can be used...
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A new 1-nitro-9-aminoacridine derivative targeting yeast topoisomerase II able to overcome fluconazole-resistance
PublicationFungal resistance remains a significant threat and a leading cause of death worldwide. Thus, overcoming microbial infections have again become a serious clinical problem. Although acridine derivatives are widely analyzed as anticancer agents, only a few reports have demonstrated their antifungal activity. In an effort to develop biologically active antifungals, twelve novel C-857 (9-(2′ -hydroxyethylamino)-1-nitroacridine) and...
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Triazoloacridone C-1305 impairs XBP1 splicing by acting as a potential IRE1α endoribonuclease inhibitor
PublicationInositol requiring enzyme 1 alpha (IRE1α) is one of three signaling sensors in the unfolding protein response (UPR) that alleviates endoplasmic reticulum (ER) stress in cells and functions to promote cell survival. During conditions of irrevocable stress, proapoptotic gene expression is induced to promote cell death. One of the three signaling stressors, IRE1α is an serine/threonine-protein kinase/endoribonuclease (RNase) that...
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Using Evidence-based Arguments to Support Dependability Assurance - Experiences and Challenges
PublicationThe presentation introduces to the problem of evidence-based arguments and their applications. Then, based on the experiences collected during development and commercial deployment of a concrete solution to this problem (system NOR-STA) we overview selected challenges and the ways of addressing them.
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Design of Microstrip UWB Balun Using Quasi-TEM Approach Aided by the Artificial Neural Network
PublicationThe design procedure for UWB balun realized in the microstrip technology is proposed in the paper. The procedure applies Artificial Neural Network which corrects the dimensions of the approximate design found by appropriate scaling of the dimensions of the prototype. The scale coefficients for longitudinal and transverse dimensions of microstrip lines are determined from electromagnetic modeling based on transmission line equations....