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161.
Acoustic absorbers that can have applications in a desired frequency band are a challenge often encountered in underwater acoustic absorber panel design. Polyurethane-based sound absorbing composite panels were designed with the help of finite element method (FEM) modeling using COMSOL for material formulations that can give optimum performance of echo reduction (ER) with minimum thickness. Polyurethanes of different compositions were evaluated for their acoustic performance using FEM modeling and experimental validation of the modeling results was done. The frequency-dependent modulus and damping properties were generated using dynamic mechanical analyzer and time–temperature superposition were performed to generate the material properties in the high frequency range (up to 25 kHz), which are significant for underwater acoustic detection applications and these data were used as inputs for modeling studies. Acoustic properties of the samples were experimentally evaluated using a water-filled pulse tube in 2–15 kHz frequency range as well as in an acoustic tank test facility for bigger dimension panels. These are nonresonant type absorbers capable to overcome limitations arising from environmental factors such as high hydrostatic pressures and also they are effective over a broad range of frequency (500 Hz–15 kHz) with ER > 15 dB. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47165. 相似文献
162.
Georg Lutter Thomas Puehler Lukas Cyganek Jette Seiler Anita Rogler Tanja Herberth Philipp Knueppel Stanislav N. Gorb Janarthanan Sathananthan Stephanie Sellers Oliver J. Müller Derk Frank Irma Haben 《International journal of molecular sciences》2022,23(1)
Clinically used heart valve prostheses, despite their progress, are still associated with limitations. Biodegradable poly-ε-caprolactone (PCL) nanofiber scaffolds, as a matrix, were seeded with human endothelial colony-forming cells (ECFCs) and human induced-pluripotent stem cells-derived MSCs (iMSCs) for the generation of tissue-engineered heart valves. Cell adhesion, proliferation, and distribution, as well as the effects of coating PCL nanofibers, were analyzed by fluorescence microscopy and SEM. Mechanical properties of seeded PCL scaffolds were investigated under uniaxial loading. iPSCs were used to differentiate into iMSCs via mesoderm. The obtained iMSCs exhibited a comparable phenotype and surface marker expression to adult human MSCs and were capable of multilineage differentiation. EFCFs and MSCs showed good adhesion and distribution on PCL fibers, forming a closed cell cover. Coating of the fibers resulted in an increased cell number only at an early time point; from day 7 of colonization, there was no difference between cell numbers on coated and uncoated PCL fibers. The mechanical properties of PCL scaffolds under uniaxial loading were compared with native porcine pulmonary valve leaflets. The Young’s modulus and mean elongation at Fmax of unseeded PCL scaffolds were comparable to those of native leaflets (p = ns.). Colonization of PCL scaffolds with human ECFCs or iMSCs did not alter these properties (p = ns.). However, the native heart valves exhibited a maximum tensile stress at a force of 1.2 ± 0.5 N, whereas it was lower in the unseeded PCL scaffolds (0.6 ± 0.0 N, p < 0.05). A closed cell layer on PCL tissues did not change the values of Fmax (ECFCs: 0.6 ± 0.1 N; iMSCs: 0.7 ± 0.1 N). Here, a successful two-phase protocol, based on the timed use of differentiation factors for efficient differentiation of human iPSCs into iMSCs, was developed. Furthermore, we demonstrated the successful colonization of a biodegradable PCL nanofiber matrix with human ECFCs and iMSCs suitable for the generation of tissue-engineered heart valves. A closed cell cover was already evident after 14 days for ECFCs and 21 days for MSCs. The PCL tissue did not show major mechanical differences compared to native heart valves, which was not altered by short-term surface colonization with human cells in the absence of an extracellular matrix. 相似文献
163.
164.
Yulan Gong Rajeswari Nagarathinam Maria F. Arisi Lorenzo Gerratana Jennifer S. Winn Michael Slifker Jianming Pei Kathy Q. Cai Zachary Hasse Elias Obeid Julio Noriega Christopher Sebastiano Eric Ross Katherine Alpaugh Massimo Cristofanilli Sandra V. Fernandez 《International journal of molecular sciences》2021,22(16)
To better understand the etiology of inflammatory breast cancer (IBC) and identify potential therapies, we studied genomic alterations in IBC patients. Targeted, next-generation sequencing (NGS) was performed on cell-free DNA (cfDNA) (n = 33) and paired DNA from tumor tissues (n = 29) from 32 IBC patients. We confirmed complementarity between cfDNA and tumor tissue genetic profiles. We found a high incidence of germline variants in IBC patients that could be associated with an increased risk of developing the disease. Furthermore, 31% of IBC patients showed deficiencies in the homologous recombination repair (HRR) pathway (BRCA1, BRCA2, PALB2, RAD51C, ATM, BARD1) making them sensitive to poly (ADP-ribose) polymerase (PARP) inhibitors. We also characterized the tumor-infiltrating lymphocytes (TILs) in tumor tissue biopsies by studying several markers (CD4, CD8, FoxP3, CD20, PD-1, and PD-L1) through immunohistochemistry (IHC) staining. In 7 of 24 (29%) patients, tumor biopsies were positive for PD-L1 and PD-1 expression on TILs, making them sensitive to PD-1/PD-L1 blocking therapies. Our results provide a rationale for considering PARP inhibitors and PD-1/PDL1 blocking immunotherapy in qualifying IBC patients. 相似文献
165.
Bhukya Gandhi Johny Juliya Veeragoni Dileep Batchu Uma Rajeswari Sunil Misra Shiva Shanker Kaki 《European Journal of Lipid Science and Technology》2021,123(9):2100055
Novel structured monoacylglycerol (MAG)-based phenolic lipids are synthesized from11-bromoundecanoic acid, phenolic acids, and solketal. Selected phenolic acids namely 4-hydroxy benzoic, vanillic, syringic, cinnamic, p-coumaric, sinapic, 4-fluorocinnamic, 4-hydroxyphenyl acetic acid, 3-(4-hydroxyphenyl) propanoic and dihydrocaffeic acids are employed for the synthesis of ten novel MAG-based phenolic lipids. The synthesized phenolic lipids are characterized by FT-IR, NMR, and mass spectra analysis. All the compounds are evaluated for antioxidant, antimicrobial, and cytotoxic activities. MAG derivative 8g of sinapic acid exhibits excellent antioxidant activity in both DPPH assay and inhibition of lipid oxidation assay. MAG derivative 8f bearing p-coumaric acid shows good antimicrobial activity against both Gram-positive and Gram-negative bacterial strains with a minimum inhibitory concentration (MIC) value of 6.25 µm mL−1. All the synthesized compounds are found to exhibit cytotoxicity against B16, DU145, and CHO cell lines, while sinapic and p-coumaric acid derivatives exhibit better activities compared to other derivatives. 相似文献
166.
167.
N. Rajeswari S. Selvasekarapandian C. Sanjeeviraja J. Kawamura S. Asath Bahadur 《Polymer Bulletin》2014,71(5):1061-1080
Proton-conducting polymer blend electrolytes based on PVA–PVP–NH4NO3 were prepared for different compositions by solution cast technique. The prepared films are investigated by different techniques. The XRD study reveals the amorphous nature of the polymer electrolyte. The FTIR and laser Raman studies confirm the complex formation between the polymer and salt. DSC measurements show decrease in T g with increasing salt concentration. The ionic conductivity of the prepared polymer electrolyte was found by ac impedance spectroscopy analysis. The maximum ionic conductivity was found to be 1.41 × 10?3 S cm?1 at ambient temperature for the composition of 50PVA:50PVP:30 wt% NH4NO3 with low-activation energy 0.29 eV. The conductivity temperature plots are found to follow an Arrhenius nature. The dielectric behavior was analyzed using dielectric permittivity (ε*) and the relaxation frequency (τ) was calculated from the loss tangent spectra (tan δ). Using this maximum ionic conducting polymer blend electrolyte, the primary proton battery with configuration Zn + ZnSO4·7H2O/50PVA:50PVP:30 wt% NH4NO3/PbO2 + V2O5 was fabricated and their discharge characteristics studied. 相似文献
168.
Efficient aggregation in wireless sensor nodes helps reduce network traffic and reduce energy consumption. The objective of this work Localization Based Evolutionary Routing (LOBER) is to achieve global optimization for aggregation and WMSN lifetime. Improved localization is achieved by a novel Centroid Based Octant Localization (CBOL) technique considering an arbitrary hexagonal region. Geometric principles of hexagon are used to locate the unknown nodes in the centroid positions of partitioned regions. Flower pollination algorithm, a meta heuristic evolutionary algorithm that is extensively applied in solving real life, complex and nonlinear optimization problems in engineering and industry is modified as Enhanced Flower Pollination Algorithm (EFPA) to fit into WMSN and enhance routing mechanism and ensure efficiency in data aggregation. The system is simulated using MATLAB and found to have a considerable improvement in the optimization process. 相似文献