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Tytuł:
Oxidative stress induced by cobalt in Jatropha curcas seedlings: response of growth and chemical changes
Autorzy:
Hu, Y.
Song, Y.
Yu, D.
Qian, W.
He, M.
Yi, L.
Gao, S.
Powiązania:
https://bibliotekanauki.pl/articles/53687502.pdf
Data publikacji:
2023
Wydawca:
Uniwersytet Warmińsko-Mazurski w Olsztynie / Polskie Towarzystwo Magnezologiczne im. Prof. Juliana Aleksandrowicza
Opis:
Experiments using in vitro embryo germination and culture have been designed to investigate the effects of cobalt levels of 0, 100, 200, 400 and 800 μM on some growth parameters and chemical changes in Jatropha curcas seedlings. The results showed that excess cobalt levels in MS media produced visual symptoms of toxicity in J. curcas seedlings after 7 d with increasing levels of cobalt ion. The fresh weights of cotyledons and radicles were significantly affected except for hypocotyls at the cobalt concentration of 100 μM. The activity of superoxide dismutase (SOD) significantly increased in the radicles when compared to the control, but decreases in the activity of the hypocotyls were found at the tested cobalt levels. Increase of guaiacol peroxidase (GPX) activity in the cotyledons and hypocotyls was observed at the tested cobalt levels, but a decrease of the activity in the radicles except for at cobalt concentration of 100 μM. Increase in the activity of catalase (CAT) of radicles with increasing cobalt concentrations, and a significant decrease in activity in the hypocotyls was also observed. Increase in phenylalanine ammonia-lyase (PAL) activity of cotyledons and radicles with increasing cobalt concentrations in the range 100-800 μM, but a decline in the activity of hypocotyls was also observed when hypocotyls at the cobalt concentrations of 400 and 800 μM. The present results indicated that SOD, GPX, CAT, and PAL may play an important role in the defensive mechanisms of Jatropha curcas seedlings exposed to excessive cobalt. These findings will help to provide useful bioassays to help in assessment of cobalt contamination in agricultural environments.
Źródło:
Journal of Elementology; 2023, 28, 4; 1037-1053
1644-2296
Pojawia się w:
Journal of Elementology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The effect of luteolin on spermatological parameters, apoptosis, oxidative stress rate in freezing rabbit semen
Autorzy:
Akarsu, S.A.
Acısu, T.C.
Güngör, İ.H.
Çakır Cihangiroğlu, A.
Koca, R.H.
Türk, G.
Sönmez, M.
Gür, S.
Fırat, F.
Esmer Duruel, H.E.
Powiązania:
https://bibliotekanauki.pl/articles/16647483.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
rabbit
semen
cryopreservation
luteolin
oxidative stress
apoptosis
Opis:
The aim of the present study was to determine the effects of Luteolin (LUT) on semen quality, oxidative stress, apoptosis, acrosomal integrity, mitochondrial membrane potential and dead sperm ratio in rabbits. Ejaculates from six New Zealand rabbits were collected, evaluated and pooled. The pooling was divided into five groups as control (no additive) LUT 25 μM, LUT 50 μM, LUT 100 μM and LUT 200 μM and LUT added. It was then filled into a falcon tube with Tris-based extender at a final concentration of approximately 35 x 106 spermatozoa. Diluated rabbit semen samples were drawn into frozen and thawed. Frozen semen straws were thawed at 37°C in 30 seconds. According to our findings, no statistical difference was found between all doses of luteolin and the control group in the CASA (computer assisted sperm analysis) analysis performed at 4°C. However, total motility, progressive motility and rapid sperm percentage were found to be higher in the frozen and thawed rabbit semen at a dose of LUT 50 μM compared to the other groups (p<0.05). While amplitude of lateral head displacement (ALH) and beat cross-frequency (BCF) values were found at the lowest dose of LUT 200 μM, a statistically significant difference was observed between the other groups. When the flow cytometry results were examined, no statistical difference was found between the rate of dead sperm, acrosomal integrity, mitochondrial membrane potential and apoptosis rate. Morever, the H2O2 percentage was found to be lower in all experimental groups compared to the control group (p<0.001). In conclusion, the addition of LUT in long-term storage of rabbit semen provided a protective effect for spermatozoa with its antioxidative properties against damage caused by cryopreservation.
Źródło:
Polish Journal of Veterinary Sciences; 2023, 26, 1; 91-98
1505-1773
Pojawia się w:
Polish Journal of Veterinary Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Oxidative stress in cows according to calving season: passive calf immunity and its relationship with colostrum quality
Autorzy:
Çolakoğlu, H.E.
Yazlık, M.O.
Çolakoğlu, E.Ç.
Kaya, U.
Bayramoğlu, R.
Kurt, S.
Vural, R.
Küplülü, Ş.
Powiązania:
https://bibliotekanauki.pl/articles/2087184.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
calf
colostrum
cow
immunoglobulin
calving season
Źródło:
Polish Journal of Veterinary Sciences; 2021, 24, 2; 225-233
1505-1773
Pojawia się w:
Polish Journal of Veterinary Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Reverse flotation of collophanite at natural pH using isooctyl polyoxyethylene ether phosphate as a collector
Autorzy:
Li, Hongqiang
Zhang, Wen
Chen, Qian
Huang, Peng
Kasomo, Richard M.
Zou, Ze
Weng, Xiaoqing
He, Dongsheng
Yang, Siyuan
Song, Shaoxian
Powiązania:
https://bibliotekanauki.pl/articles/1445877.pdf
Data publikacji:
2021
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
reverse flotation
dolomite
fluorapatite
AEP
selective adsorption
Opis:
Reverse flotation of collophanite at natural pH could significantly decrease the cost of pH regulators. In this study, isooctyl polyoxyethylene ether phosphate (AEP) was tested as a new surfactant in the reverse flotation of collophanite. Micro-flotation tests were conducted, and the adsorption mechanism of the new collector was analysed using X-ray photoelectron spectroscopy (XPS) and zeta potential analyses. The results of the flotation tests demonstrated that AEP could enable dolomite to float under natural pH (pH=7.2) and showed profound selectivity towards dolomite as opposed to fluorapatite. Based on the zeta potential and XPS results, the adsorption phenomena are mainly attributed to calcium active sites on both mineral surfaces. Dolomite possesses more magnesium active sites than fluorapatite, which tend to reinforce the interaction effect between AEP and dolomite. Furthermore, when compared to CO32- ions on the dolomite surface, PO43- ions on the fluorapatite surface tend to exhibit a stronger hindrance to the adsorption of AEP on the fluorapatite surface. This is attributed to their larger volumes and more charges on their surfaces, thereby causing a floatability difference between the two minerals.
Źródło:
Physicochemical Problems of Mineral Processing; 2021, 57, 4; 78-86
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Does increased immune response at early postpartum period have a relationship with metabolic markers and subsequent fertility?
Autorzy:
Yazlik, M.O.
Çolakoğlu, H.E.
Kaya, U.
Küplülü, Ş.
Vural, M.R.
Powiązania:
https://bibliotekanauki.pl/articles/2087342.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
cow
immunity
fertility
metabolites
Źródło:
Polish Journal of Veterinary Sciences; 2020, 23, 1; 27-35
1505-1773
Pojawia się w:
Polish Journal of Veterinary Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ephedrine production from suspension cultures of Ephedra alata L. callus
Autorzy:
Hegazi, G.A.
Ghareb, H.E.
Gabr, M.F.
Powiązania:
https://bibliotekanauki.pl/articles/2096962.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
shake-flask culture
in vitro
alkaloid
biotic elicitor
Aspergillus niger
yeast extract
Opis:
Ephedra alata is an important Egyptian medicinal plant with enormous applications in pharmaceutical industry. Shake-flask suspension cultures of E. alata were established from internodal segment-derived callus. The suspension cultures were treated with two biotic elicitors, namely Aspergillus niger and yeast extract, to enhance the synthesis of ephedrine – the bioactive constituent of E. alata. Ephedrine was quantified using the high performance liquid chromatography technique. Ephedrine concentration was not directly related to biomass production. Aspergillus niger and yeast extract enhanced the production of ephedrine by 2.5- to 7-fold after different durations of incubation as compared to ephedrine content in the mother plant. Treatment with the fungal elicitor A. niger extract induced the maximum accumulation of ephedrine at the concentration of 1.67%; it also increased ephedrine biosynthesis by 7-fold in 24-day-old culture as compared to the ephedrine content in the mother plant and caused higher ephedrine biosynthesis than that in the control treatment without elicitors. The present protocol could be applicable for the large-scale production of ephedrine from E. alata.
Źródło:
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology; 2020, 101, 1; 25-33
0860-7796
Pojawia się w:
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Genome-wide association study of terpenoids in resin reveals candidate genes for resin yield in Pinus massoniana
Autorzy:
Bai, Q.
Zhang, Q.
Cai, Y.
Lian, H.
Liu, W.
Luo, M.
Zeng, L.
He, B.
Powiązania:
https://bibliotekanauki.pl/articles/2078149.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Instytut Dendrologii PAN
Tematy:
Pinus massoniana
GC-MS
terpenoid
GWAS
candidate gene
Opis:
Masson pine (Pinus massoniana) is an important species for resin tapping in China. Molecular assisted selection (MAS) has been gradually introduced in to the selection and breeding of masson pine. Until now, the lack of connection between genome information and phenotypic data has hindered the breeding and selection of important chemical compounds of xylem resin. In this study, gas chromatography mass spectrometer (GC-MS) was employed for qualitative and quantitative analysis of chemical compounds of resin collected from 69 masson pine germplasm resources. Then, genome-wide association study (GWAS) was conducted for the terpenoids with higher heritability. A total of 15 primary compounds, including six diterpenes and nine monoterpenes/sesquiterpenes, were detected from xylem resin. By using five GWAS methods, 42 associated SNPs were identified from these masson pines. The P. taeda genome database was used for detecting candidate genes related to the associated SNPs. By using transcriptome data, several members of PKc_like super family, Cytochrome P450, AP2-ERF, F-box, and ABC transporter were found to be highly expressed in the masson pines with higher resin-yielding capacity. The terpenoids associated SNPs can be directly used for MAS. These candidate genes, especially the two F-box members, will contribute to the study of terpenoid biosynthesis mechanisms in the future.
Źródło:
Dendrobiology; 2020, 84; 109-121
1641-1307
Pojawia się w:
Dendrobiology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Abiotic mechanisms for biochar effects on soil N2O emission
Autorzy:
He, C.
Manevski, K.
Andersen, M.N.
Hu, C.
Dong, W.
Li, J.
Powiązania:
https://bibliotekanauki.pl/articles/2082642.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Instytut Agrofizyki PAN
Tematy:
gas diffusion
mitigation
nitrous oxide
water
filled pore space
Opis:
In this research, sterile soil columns with different contents of biochar made from apple-tree residues (0, 1 and 5% w/w) at three levels of water filled pore space (40, 60, and 80%) were set up in the laboratory to study nitrous oxide diffusion and binding processes. The results indicated that nitrous oxide emission can be effectively mitigated at 5% biochar regardless of soil water content. However, 1% biochar stimulated nitrous oxide diffusion compared to the other biochar treatments, which was opposite to expectations due to the stronger aeration than adsorption effect, while 0% had a suppression effect between 1 and 5%. Nitrous oxide emissions increased with increasing water filled pore space due to concomitantly decreasing biochar tortuousity at high water content. The increase of nitrogen from 1.11 to 1.50% on the biochar surface in the 5% treatment, and from 1.11 to 1.46% in the 100% biochar treatment, suggested that the main abiotic mechanisms for mitigation of nitrous oxide emission is adsorption and subsequent reactions with C = C bonds on appletree biochar surfaces since C = O and C-O bonds both increased and C=C/C-C/C-H declined.
Źródło:
International Agrophysics; 2019, 33, 4; 537-546
0236-8722
Pojawia się w:
International Agrophysics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Reducing the salinity impact on soilless culture of tomatoes using supplemental Ca and foliar micronutrients
Autorzy:
Saleh, S.
Liu, G.
Liu, M.
Liu, W.
Gruda, N.
He, H.
Powiązania:
https://bibliotekanauki.pl/articles/12688394.pdf
Data publikacji:
2019
Wydawca:
Uniwersytet Przyrodniczy w Lublinie. Wydawnictwo Uniwersytetu Przyrodniczego w Lublinie
Tematy:
plant cultivation
tomato
Solanum lycopersicum
soilless culture
vegetative growth
fruit quality
yield
calcium supplementation
foliar application
foliar nutrition
micronutrient
salinity impact
salt stress
physiological parameter
Opis:
Salt stress is known as one of the most severe abiotic factors limiting the plant production all over the world. In this study, three additives: (i) supplemental Ca (5 mmol L–1) to nutrient solution, (ii) foliar application of micronutrients (Fe, Mn and Zn at 60, 160 and 110 mg L–1, respectively), and (iii) combination of both of them were evaluated aiming to reduce the negative impact of salt stress on tomato plants cultivated in a soilless culture and improve the internal quality of fruits. The obtained results show that salinity reduced vegetative growth and physiological parameters, fruit yield and its components, and even more lowered fruit market classification of tomatoes. Salinity treatment reduced most of essential macro- and micronutrients in tomato fruit, whilst Na content was increased. Tomato productivity and fruit quality were ameliorated under saline conditions by increasing Ca into nutrient solution and applying a foliar application of micronutrients. A combination of both additives ranked the first to alleviate the adverse effects of salinity on tomatoes, followed by solo supplemental Ca into saline nutrient solution. On the other hand, the internal fruit quality of antioxidant compounds, such as vitamin C, lycopene, α-carotene, β-carotene and lutein as well as acidity, total soluble solid and dry matter percent, were increased under saline conditions.
Źródło:
Acta Scientiarum Polonorum. Hortorum Cultus; 2019, 18, 3; 187-200
1644-0692
Pojawia się w:
Acta Scientiarum Polonorum. Hortorum Cultus
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ship route planning using historical trajectories derived from AIS Data
Autorzy:
He, Y. K.
Zhang, D.
Zhang, J. F.
Zhang, M. Y.
Li, T. W.
Powiązania:
https://bibliotekanauki.pl/articles/116536.pdf
Data publikacji:
2019
Wydawca:
Uniwersytet Morski w Gdyni. Wydział Nawigacyjny
Tematy:
AIS Data
Automatic Identification System (AIS)
route planning
historical trajectories
AIS messages
marine traffic
Dijkstra algorithm
ant colony algorithm
Opis:
Ship route planning is one of the key issues in enhancing traffic safety and efficiency. Many route planning methods have been developed, but most of them are based on the information from charts. This paper proposes a method to generate shipping routes based on historical ship tracks. The ship's historical route information was obtained by processing the AIS data. From which the ship turning point was extracted and clustered as nodes. The ant colony algorithm was used to generate the optimize route. The ship AIS data of the Three Gorges dam area was selected as a case study. The ships’ optimized route was generated, and further compared with the actual ship's navigation trajectory. The results indicate that there is space of improvement for some of the trajectories, especially near the turning areas.
Źródło:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation; 2019, 13, 1; 69-76
2083-6473
2083-6481
Pojawia się w:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Combined Influence of Silicon Content and Oxygen Concentration on the Oxidation Process of Silicon-Containing Steels
Autorzy:
Yuan, Q.
Xu, G.
Zhou, M.
He, B.
Hu, H.
Powiązania:
https://bibliotekanauki.pl/articles/352126.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
silicone content
oxygen concentration
mass gain
isothermal holding time
Opis:
The combined influence of silicon content and oxygen concentration on silicon-containing steels was investigated, via a heating route similar to that applied in the industrial reheating process, using a Simultaneous Thermal Analyzer (STA). Four different oxygen concentrations and three different isothermal holding times were designed. The results show that the effect of silicon on the mass gain depends on the oxygen concentration and the oxidation time. The mass gain of low-silicon steel is greater than that of high-silicon steel at 1260°C in the oxygen concentrations of 1.0 vol.% and 2.0 vol.%, even when the isothermal holding time is 90 minutes. However, there is a critical time point for mass gain in oxygen concentrations ≥3.0 vol.%. The mass gain of lowsilicon steel is greater before and smaller after this critical point. The critical time is deferred with decreasing oxygen concentration.
Źródło:
Archives of Metallurgy and Materials; 2018, 63, 1; 445-450
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Different Ignition Responses of Powdery and Bulky 1,3,5-Triamino-2,4,6-trinitrobenzene (TATB) Based Polymer-bonded Explosives under Ultra-high Voltage Electrostatic Discharge
Autorzy:
Lyu, Z.
Long, X.
Li, Z.
Dai, X.
Deng, C.
He, S.
Li, M.
Yao, K.
Wen, Y.
Powiązania:
https://bibliotekanauki.pl/articles/358240.pdf
Data publikacji:
2018
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Tematy:
electrostatic spark sensitivity
ultra-high voltage electrostatic discharge
thermal effect
electric field effect
Opis:
The electric spark induced ignition mechanism for explosives needs further study. The ignition of powdery and bulky TATB by electrostatic discharge (ESD) was investigated. Up to 200 kV ultra-high voltage ESD was applied to powdery and bulky explosives of two TATB-based polymer-bonded explosives (named PBX-1 and PBX-2). The results showed that the spark sensitivities of powdery and bulky explosives are extremely different for the same formulation. The 50% ignition voltages of powdery PBX-1 and PBX-2 were 10.8 kV and 8.5 kV, respectively, while the values for the bulky samples (tablets) were not less than 200 kV. Both heat and the electric field can be transmitted into the powdery samples, on the other hand only the electric field can be transmitted into the bulk samples. The electric field has a smaller contribution while the heat has a larger contribution to the ignition during an ESD, i.e., the thermal effect plays a main role in the ignition process. Our experimental results are in good agreement with recent results calculated by density functional theory.
Źródło:
Central European Journal of Energetic Materials; 2018, 15, 2; 283-298
1733-7178
Pojawia się w:
Central European Journal of Energetic Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Differential responses of aquatic and aerobic forms of Echinochloa crus-galli (L.) Beauv. and E. colona (L.) Link. by morpho-physiological and molecular analysis
Autorzy:
Khedr, A.-H.A.
Serag, M.M.
Shaaban, H.E.
Abogadallah, G.M.
Powiązania:
https://bibliotekanauki.pl/articles/9989.pdf
Data publikacji:
2017
Wydawca:
Fundacja na Rzecz Młodych Naukowców
Tematy:
alcohol dehydrogenase
ADH zob.alcohol dehydrogenase
aquatic form
aerobic form
Echinochloa crus-galli
Echinochloa colona
habitat alteration
morphophysiological analysis
molecular analysis
phosphoenolopyruvate carboxylase
Rubisco
Opis:
Echinochloa crus-galli and E. colona are serious weeds around the world. Morphological and biochemical features of aquatic and aerobic forms of both species were investigated experimentally by transplanting the seedlings reciprocally between water-saturated and aerobic soils (70% field capacity). When the plants were grown in water-saturated soil, a significant decrease in tiller height was observed in E. crus-galli, but not in E. colona. Upon growing the plants in aerobic soil, internode length and spike dry weight increased significantly in E. crus-galli, but decreased significantly in E. colona. Growth under aerobic condition caused a significant increase in PEPC/Rubisco ratio, but a significant decrease was observed under water-saturated conditions. When E. crus-galli was transplanted in aerobic soil, several forms of peroxidase were upregulated. Contrarily, in E. colona peroxidase isoforms did not respond to habitat change. Gene expression of ADH in E. colona was constitutive at a fairly high level under native habitats then enhanced with reversing habitat that caused anoxic and mild drought conditions. Both species tend to grow faster under aerobic conditions by modifying the photosynthetic machinery and capacity of scavenging of reactive oxygen species. Furthermore, ADH appears to play a role in supporting growth under water-saturated conditions.
Źródło:
Environment, Earth and Ecology; 2017, 1, 1
2543-9774
2451-4225
Pojawia się w:
Environment, Earth and Ecology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Enhancing SO2 removal efficiency by lime modified with sewage sludge in a novel integrated desulfurization process
Autorzy:
Qin, L.
Han, J.
Chen, W.
Liu, Z.
He, M.
Xing, F.
Powiązania:
https://bibliotekanauki.pl/articles/950037.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
sewage sludge
steel industry
sintering process
osad ściekowy
przemysł hutniczy
proces spiekania
Opis:
In China, the sintering process annually emitted around 1.5 million t SO2, representing 70% of SO2 produced from the iron and steel industry. Lime based sorbent was modified with municipal sewage sludge (MSS) and the influence of the modification on the desulfurization efficiency was investigated in a laboratory-scale novel integrated desulfurization (NID) reactor. The properties of modified sorbent were characterized by the Brunauer–Emmett–Teller (BET) analyzer and X-ray fluorescence (XRD) analyzer. BET surface area was increased from 17.48 to 46.68 m2g–1. when the MSS/lime ratio increased from 0 to 0.08. Ca4Al8Si8O32, Ca1.5SiO3.5, Na2Si2O5 and CaSiO3 found in the modified lime benefited for the increase of the BET surface area and pore volume. The effects of sewage sludge/CaO weight ratio, calcination temperature and hydration time on the desulfurization efficiency were also studied. SO2 removal efficiency was increased from 88.7% to 97.3% after using the lime modified with sewage sludge.
Źródło:
Environment Protection Engineering; 2017, 43, 4; 17-27
0324-8828
Pojawia się w:
Environment Protection Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the Interaction of Resonance And Bragg Scattering Effects for the Locally Resonant Phononic Crystal with Alternating Elastic and Fluid Matrices
Autorzy:
Yuan, B.
Chen, Y.
Jiang, M.
Tang, S.
He, M.
Tu, M.
Powiązania:
https://bibliotekanauki.pl/articles/177103.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
locally resonant phononic crystals
effective speed of sound
coupling band gaps
underwater acoustic materials
Opis:
Three-dimensional (3D) locally resonant phononic crystals (LRPCs) are studied with the aim of optimising the sub-wavelength band gaps of such composites. By analysing their effective acoustic properties, it has been found that the effective acoustic speed of the composite will drop to zero when local resonance arise, and will increase monotonically when Bragg scattering effects occur. Moreover, if the matrix is a low-shear-speed medium, local resonators can significantly reduce the effective acoustic speed of the composite and, therefore, lower the frequency where Bragg scattering effects occur. Hence, a specific LRPC with alternating elastic and fluid matrices is proposed, whose resonance and Bragg gaps are already close in frequency. The fluid matrix behaves as a wave filter, which prevents the shear waves from propagating in the composite. By using the layer-multiple-scattering theory, the coupling behaviour of local resonance and Bragg scattering band gaps has been investigated. Both gaps are enhanced when they move closer to each other. Finally, a gap-coupled case is obtained that displays a broad sub-wavelength band gap. Such proposal excels at the application of underwater acoustic materials since the arrangement of structure can be handily adjusted for tuning the frequency of coupled gap.
Źródło:
Archives of Acoustics; 2017, 42, 4; 725-733
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł

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