Science.gov

Sample records for extracting mechanical properties

  1. Antibacterial, mechanical, and barrier properties of sago starch film incorporated with Betel leaves extract.

    PubMed

    Nouri, Leila; Mohammadi Nafchi, Abdorreza

    2014-05-01

    The antimicrobial, mechanical and barrier properties and light transmission of sago starch film incorporated with different percentage of Betel leaf extract (5%, 10%, 20%, and 30%) were evaluated. With regard to mechanical properties, tensile strength decreased when the percentage of extract increased. Elongation at break (%) and seal strength (N/m) increased with increasing percentage of extract from 5% to 20%, while decreased for films containing 30% extract due to heterogeneity of films in this percentage. With regard to barrier properties, water vapour and oxygen barrier properties decreased in all samples when percentage of the extract increased. Antimicrobial activity of all the films increased against both Gram positive and Gram negative bacteria as percentage of Betel leaf extract increased, except for Psuedomonas aeruginosa, which was not susceptible at any percentage of the extract. PMID:24582935

  2. CMOS-MEMS Test-Key for Extracting Wafer-Level Mechanical Properties

    PubMed Central

    Chuang, Wan-Chun; Hu, Yuh-Chung; Chang, Pei-Zen

    2012-01-01

    This paper develops the technologies of mechanical characterization of CMOS-MEMS devices, and presents a robust algorithm for extracting mechanical properties, such as Young’s modulus, and mean stress, through the external electrical circuit behavior of the micro test-key. An approximate analytical solution for the pull-in voltage of bridge-type test-key subjected to electrostatic load and initial stress is derived based on Euler’s beam model and the minimum energy method. Then one can use the aforesaid closed form solution of the pull-in voltage to extract the Young’s modulus and mean stress of the test structures. The test cases include the test-key fabricated by a TSMC 0.18 μm standard CMOS process, and the experimental results refer to Osterberg’s work on the pull-in voltage of single crystal silicone microbridges. The extracted material properties calculated by the present algorithm are valid. Besides, this paper also analyzes the robustness of this algorithm regarding the dimension effects of test-keys. This mechanical properties extracting method is expected to be applicable to the wafer-level testing in micro-device manufacture and compatible with the wafer-level testing in IC industry since the test process is non-destructive. PMID:23235449

  3. The effect of soxhlet extraction on morphology and mechanical properties of Poly(DVB)polyHIPE

    NASA Astrophysics Data System (ADS)

    Pakeyangkoon, Pornsri; Nithitanakul, Manit

    2007-03-01

    PolyHIPE (Polymerized High Internal Phase Emulsion) is a novel porous polymer, which is microporous materials and produce by polymerization of the continuous phase of system. Poly(DVB)PolyHIPE using two different system of three-component surfactant (S20M and S80M) with various porogenic solvents including T, CB, CB/T and PE has been successfully prepared. The phase morphology, mechanical properties and surface area measurement were investigated. After polymerization of continuous phase, the porous materials with interconnected were obtained. The cell size and surface area were found to improve by using various solvent, this is due to the ability of porogenic solvent and mixture of surfactant which prevent the Ostwald ripening (coalescence) of system. Moreover, the surface area and mechanical properties of the resulting materials were found to be depended on the soxhlet time. It can be concluded that the suitable soxhlet time for extraction was 6-12 hours and at this condition, high surface area with highest mechanical properties was obtained as compare to others conditions.

  4. Antimicrobial and physical-mechanical properties of agar-based films incorporated with grapefruit seed extract.

    PubMed

    Kanmani, Paulraj; Rhim, Jong-Whan

    2014-02-15

    The use of synthetic petroleum based packaging films caused serious environmental problems due to their difficulty in recycling and poor biodegradability. Therefore, present study was aimed to develop natural biopolymer-based antimicrobial packaging films as an alternative for the synthetic packaging films. As a natural antimicrobial agent, grapefruit seed extract (GSE) has been incorporated into agar to prepare antimicrobial packaging film. The films with different concentrations of GSE were prepared by a solvent casting method and the resulting composite films were examined physically and mechanically. In addition, the films were characterized by FE-SEM, XRD, FT-IR and TGA. The incorporation of GSE caused increase in color, UV barrier, moisture content, water solubility and water vapor permeability, while decrease in surface hydrophobicity, tensile strength and elastic modulus of the films. As the concentration of GSE increased from 0.6 to 13.3 μg/mL, the physical and mechanical properties of the films were affected significantly. The addition of GSE changed film microstructure of the film, but did not influence the crystallinity of agar and thermal stability of the agar-based films. The agar/GSE films exhibited distinctive antimicrobial activity against three test food pathogens, such as Listeria monocytogenes, Bacillus cereus and Escherichia coli. These results suggest that agar/GSE films have potential to be used in an active food packaging systems for maintaining food safety and extending the shelf-life of the packaged food. PMID:24507339

  5. Extracting mechanical properties of copper coatings on oxidized silicon substrates by nanoindentation

    NASA Astrophysics Data System (ADS)

    Moharrami, N.; Oila, A.; Bull, S. J.

    2014-08-01

    The thickness of the copper coatings that are used for the manufacture of conducting tracks in microelectronic devices are being aggressively scaled down and there is a need to monitor the mechanical response of metallization at a scale comparable to the material microstructure. When using indentation tests to assess the properties of thin films, the plastic zone dimensions are of a similar scale to the grain size. For the purposes of designs based on continuum mechanics approaches it is usually required that the grain size is much smaller than the deforming volume, which is not always observed in practice. Considerable differences between predicted and observed performance can be seen depending on the material tested and its grain size; the extent of oxidation of the copper after deposition is critical, as is that of its underlying silicon substrate. Whereas it is possible to make good measurements of metallization properties on stiff substrates such as silicon there are serious issues with the reliability of Young's modulus and hardness data from coatings on device quality wafers which may have been oxidized prior to use. The effects of grain size, shape and orientation on the mechanical response of metallic thin films used for semiconductor metallization on oxidized silicon are presented in this paper. The appropriate conditions for the successful use of continuum mechanics are discussed and the importance of considering the consequences of crystallographic anisotropy and oxidation on the selection of suitable design data is presented with regards to copper coatings.

  6. Extraction of mechanical properties of articular cartilage from osmotic swelling behavior monitored using high frequency ultrasound.

    PubMed

    Wang, Q; Zheng, Y P; Niu, H J; Mak, A F T

    2007-06-01

    Articular cartilage is a biological weight-bearing tissue covering the bony ends of articulating joints. Negatively charged proteoglycan (PG) in articular cartilage is one of the main factors that govern its compressive mechanical behavior and swelling phenomenon. PG is nonuniformly distributed throughout the depth direction, and its amount or distribution may change in the degenerated articular cartilage such as osteoarthritis. In this paper, we used a 50 MHz ultrasound system to study the depth-dependent strain of articular cartilage under the osmotic loading induced by the decrease of the bathing saline concentration. The swelling-induced strains under the osmotic loading were used to determine the layered material properties of articular cartilage based on a triphasic model of the free-swelling. Fourteen cylindrical cartilage-bone samples prepared from fresh normal bovine patellae were tested in situ in this study. A layered triphasic model was proposed to describe the depth distribution of the swelling strain for the cartilage and to determine its aggregate modulus H(a) at two different layers, within which H(a) was assumed to be linearly dependent on the depth. The results showed that H(a) was 3.0+/-3.2, 7.0+/-7.4, 24.5+/-11.1 MPa at the cartilage surface, layer interface, and deep region, respectively. They are significantly different (p<0.01). The layer interface located at 70%+/-20% of the overall thickness from the uncalcified-calcified cartilage interface. Parametric analysis demonstrated that the depth-dependent distribution of the water fraction had a significant effect on the modeling results but not the fixed charge density. This study showed that high-frequency ultrasound measurement together with triphasic modeling is practical for quantifying the layered mechanical properties of articular cartilage nondestructively and has the potential for providing useful information for the detection of the early signs of osteoarthritis. PMID:17536909

  7. Nutraceutical properties of the methanolic extract of edible mushroom Cantharellus cibarius (Fries): primary mechanisms.

    PubMed

    Kozarski, Maja; Klaus, Anita; Vunduk, Jovana; Zizak, Zeljko; Niksic, Miomir; Jakovljevic, Dragica; Vrvic, Miroslav M; Van Griensven, Leo J L D

    2015-06-01

    The methanolic extract of the wild edible mushroom Cantharellus cibarius Fr. (chanterelle) was analyzed for in vitro antioxidative, cytotoxic, antihypertensive and antibacterial activities. Various primary and secondary metabolites were found. Phenols were the major antioxidant components found in the extract (49.8 mg g(-1)), followed by flavonoids, whose content was approximately 86% of the total phenol content. Antioxidant activity, measured by four different methods, was high for inhibition of lipid peroxidation (EC50 = 1.21 mg mL(-1)) and chelating ability (EC50 = 0.64 mg mL(-1)). The antioxidant activity of the C. cibarius methanol extract was achieved through chelating iron compared to hydrogen atom and/or electron transfer. The extract showed good selectivity in cytotoxicity on human cervix adenocarcinoma HeLa, breast carcinoma MDA-MB-453 and human myelogenous leukemia K562, compared to normal control human fetal lung fibroblasts MRC-5 and human lung bronchial epithelial cells BEAS-2B. The extract had inhibitory activity against angiotensin converting I enzyme (ACE) (IC50 = 0.063 mg mL(-1)). The extract revealed selective antimicrobial activity against Gram-positive bacteria with the highest potential against E. faecalis. The medicinal and health benefits, observed in wild C. cibarius mushroom, seem an additional reason for its traditional use as a popular delicacy food. PMID:25943486

  8. Impact of postharvest dehydration process of winegrapes on mechanical and acoustic properties of the seeds and their relationship with flavanol extraction during simulated maceration.

    PubMed

    Río Segade, Susana; Torchio, Fabrizio; Gerbi, Vincenzo; Quijada-Morín, Natalia; García-Estévez, Ignacio; Giacosa, Simone; Escribano-Bailón, M Teresa; Rolle, Luca

    2016-05-15

    This study represents the first time that the extraction of phenolic compounds from the seeds is assessed from instrumental texture properties for dehydrated grapes. Nebbiolo winegrapes were postharvest dehydrated at 20°C and 41% relative humidity. During the dehydration process, sampling was performed at 15%, 30%, 45% and 60% weight loss. The extractable fraction and extractability of phenolic compounds from the seeds were determined after simulated maceration. The evolution of mechanical and acoustic attributes of intact seeds was also determined during grape dehydration to evaluate how these changes affected the extraction of phenolic compounds. The extractable content and extractability of monomeric flavanols and proanthocyanidins, as well as the galloylation percentage of flavanols, might be predicted easily and quickly from the mechanical and acoustic properties of intact seeds. This would help in decision-making on the optimal dehydration level of winegrapes and the best management of winemaking of dehydrated grapes. PMID:26776049

  9. Antidiabetic properties and mechanism of action of Gynura procumbens water extract in streptozotocin-induced diabetic rats.

    PubMed

    Hassan, Zurina; Yam, Mun Fei; Ahmad, Mariam; Yusof, Ahmad Pauzi M

    2010-01-01

    Gynura procumbens (Lour.) Merr (family Compositae) is cultivated in Southeast Asia, especially Indonesia, Malaysia and Thailand, for medicinal purposes. This study evaluated the in vivo hypoglycemic properties of the water extract of G. procumbens following 14 days of treatment and in vitro in RIN-5F cells. Glucose absorption from the intestines and its glucose uptake in abdominal skeletal muscle were assessed. The antidiabetic effect of water extract of G. procumbens leaves was investigated in streptozotocin-induced diabetic rats. The intraperitoneal glucose tolerance test (IPGTT) was performed in diabetic rats treated with G. procumbens water extract for 14 days. In the IPGTT, blood was collected for insulin and blood glucose measurement. After the IPGTT, the pancreases were collected for immunohistochemical study of β-cells of the islets of Langerhans. The possible antidiabetic mechanisms of G. procumbens were assessed through in vitro RIN-5F cell study, intestinal glucose absorption and glucose uptake by muscle. The results showed that G. procumbens significantly decreased blood glucose levels after 14 days of treatment and improved outcome of the IPGTT. However, G. procumbens did not show a significant effect on insulin level either in the in vivo test or the in vitro RIN-5F cell culture study. G. procumbens also showed minimal effects on β-cells of the islets of Langerhans in the pancreas. However, G. procumbens only significantly increased glucose uptake by muscle tissues. From the findings we can conclude that G. procumbens water extract exerted its hypoglycemic effect by promoting glucose uptake by muscles. PMID:21150821

  10. Physio-mechanical properties of an active chitosan film incorporated with montmorillonite and natural antioxidants extracted from pomegranate rind.

    PubMed

    Qin, Yu-Yue; Zhang, Zhi-Hong; Li, Lin; Yuan, Ming-Long; Fan, Jian; Zhao, Tian-Rui

    2015-03-01

    An active film was prepared from chitosan incorporated with montmorillonite (MMT) and pomegranate rind powder extract (PRP). The effect of MMT (1 %, 3 %, and 5 % w/w chitosan) and PRP (1 %, 1.5 %, and 2 % w/v chitosan) on the physical, mechanical and antioxidant properties of the chitosan-based films was studied. Fourier transform infrared (FTIR) spectra revealed that good interactions occurred between functional groups of chitosan with MMT or with PRP. The results showed that the water vapor barrier property of the films was significantly improved by incorporation of MMT and PRP (p < 0.05). When compared to pure chitosan film, the WVP of M3P2 film (Chitosan/3 % MMT/2 % PRP) decreased by 25.2 %. Tensile strength of the films was affected by the addition of MMT and PRP. However, percent elongation at break was not significantly changed by addition of PRP. The film incorporated with 3 % MMT and 2 % PRP that contained the highest amount of total phenolic (15.2 mg GAE/g DW), was found to be the most active radical scavenger. These results suggest that chitosan films containing MMT and PRP can be used for development of active food packaging materials. PMID:25745215

  11. Aleurites moluccana (L.) Willd. Leaves: Mechanical Antinociceptive Properties of a Standardized Dried Extract and Its Chemical Markers

    PubMed Central

    Quintão, Nara L. M.; Meyre-Silva, Christiane; Silva, Gislaine F.; Antonialli, Carla S.; Rocha, Lilian W.; Lucinda-Silva, Ruth M.; Malheiros, Angela; Souza, Márcia M.; Cechinel Filho, Valdir; Bresolin, Tania M. B.

    2011-01-01

    Seeking to develop a new analgesic phytomedicine, a spray-dried extract (SDE) of Aleurites moluccana (L.) Willd. leaves was developed in scale up (5 kg). The SDE was standardized at 3% w/w in relation to the flavonoid 2′′-O-rhamnosylswertisin. The SDE batches were evaluated in relation to their physical, physiochemical, and pharmacological characteristics. The results demonstrated the reproducibility of the scale up SDE process which, when dosed orally, reduced carrageenan-induced mechanical hypernociception, with an ID50% of 443 mg/kg. Similar results were obtained with animals injected with complete Freund's adjuvant (CFA), in which SDE caused inhibition of 48 ± 4%. SDE was effective in preventing prostaglandin E2 (PGE2)-induced mechanical hypernociception (inhibition of 26 ± 10% and 33 ± 3%, at 250 and 500 mg/kg, respectively). Swertisin and 2′′-O-rhamnosylswertisin isolated from the own extract were effective in inhibiting the hypernociceptive response induced by carrageenan (70 ± 2% and 50 ± 5%, resp.). Furthermore, 2′′-O-rhamnosylswertisin was capable of significantly inhibiting the mechanical sensitization induced by CFA or PGE2, with inhibitions of 25 ± 3% and 94 ± 6%, respectively. These results suggest that the effects of SDE are related, at least in part, to the presence of these flavonoids. PMID:21660087

  12. A time domain technique for mechanism extraction

    NASA Technical Reports Server (NTRS)

    Dominek, Allen K.; Peters, Leon, Jr.; Burnside, Walter D.

    1987-01-01

    The properties of scattered fields from a structure can be better evaluated from the characteristics of the individual scatterers. Decomposition techniques can be classified either as a matrix or an integral formulation. With either formulation, aspect pattern of frequency information of a scattering center can be obtained. Emphasis is placed on an integral (time domain) isolation extraction technique to obtain the frequency characteristics of scattering mechanisms. This technique has its origins in the time domain interpretation of scattered fields.

  13. Mechanisms of Analgesic and Anti-Inflammatory Properties of Annona muricata Linn. (Annonaceae) Fruit Extract in Rodents

    PubMed Central

    Ishola, Ismail O.; Olusayero, Abayomi Micheal; Ochieng, Charles O.

    2014-01-01

    Abstract Unripe fruit of Annona muricata Linn. (Annonaceae) (soursop) is used in traditional African medicine for the treatment of neuralgia, rheumatism, and arthritic pain. This study sought to investigate the analgesic and anti-inflammatory effects of lyophilized fruit extract of Annona muricata (AM) in rodents. The analgesic activity was evaluated using the mouse writhing, formalin, and hot-plate tests while the anti-inflammatory action was investigated using the carrageenan-induced rat paw edema and xylene-induced ear edema tests. Pretreatment with AM (50, 100, and 200 mg/kg, p.o.) produced dose-dependent (P<.001) inhibition of writhes and formalin-induced pain in the late phase. AM and morphine produced time-course increase in pain threshold in hot-plate test. However, the analgesic effect elicited by AM was reversed (P<.05) by naloxone pretreatment. Similarly, the time-dependent increase in paw circumference induced by carrageenan was inhibited by AM treatment with peak effect (0.23±0.10 cm; P<.001, 200 mg/kg; 6 h), which was comparatively similar to that of diclofenac treated. Further, the xylene-induced ear edema was significantly reduced by AM (50 or 100 mg/kg) pretreatment; however, the anti-inflammatory effect elicited by AM was prevented by pretreatment of mice with NG-nitro-l-arginine (20 mg/kg, i.p., nitric-oxide synthase inhibitor) 15 min before AM (200 mg/kg, p.o.). The in vitro cyclooxygenase assay also showed that AM produced concentration-dependent inhibition of both cyclooxygenase (COX)-1 and COX-2 activity by 39.44%±0.05% and 55.71%±0.12%, respectively, at 100 μg/mL. In conclusion, A. muricata possesses analgesic effect through interaction with opioidergic pathway and anti-inflammatory property through inhibition of chemical mediators of inflammation. PMID:25133801

  14. Mechanisms of analgesic and anti-inflammatory properties of Annona muricata Linn. (Annonaceae) fruit extract in rodents.

    PubMed

    Ishola, Ismail O; Awodele, Olufunsho; Olusayero, Abayomi Micheal; Ochieng, Charles O

    2014-12-01

    Unripe fruit of Annona muricata Linn. (Annonaceae) (soursop) is used in traditional African medicine for the treatment of neuralgia, rheumatism, and arthritic pain. This study sought to investigate the analgesic and anti-inflammatory effects of lyophilized fruit extract of Annona muricata (AM) in rodents. The analgesic activity was evaluated using the mouse writhing, formalin, and hot-plate tests while the anti-inflammatory action was investigated using the carrageenan-induced rat paw edema and xylene-induced ear edema tests. Pretreatment with AM (50, 100, and 200 mg/kg, p.o.) produced dose-dependent (P<.001) inhibition of writhes and formalin-induced pain in the late phase. AM and morphine produced time-course increase in pain threshold in hot-plate test. However, the analgesic effect elicited by AM was reversed (P<.05) by naloxone pretreatment. Similarly, the time-dependent increase in paw circumference induced by carrageenan was inhibited by AM treatment with peak effect (0.23±0.10 cm; P<.001, 200 mg/kg; 6 h), which was comparatively similar to that of diclofenac treated. Further, the xylene-induced ear edema was significantly reduced by AM (50 or 100 mg/kg) pretreatment; however, the anti-inflammatory effect elicited by AM was prevented by pretreatment of mice with N(G)-nitro-l-arginine (20 mg/kg, i.p., nitric-oxide synthase inhibitor) 15 min before AM (200 mg/kg, p.o.). The in vitro cyclooxygenase assay also showed that AM produced concentration-dependent inhibition of both cyclooxygenase (COX)-1 and COX-2 activity by 39.44%±0.05% and 55.71%±0.12%, respectively, at 100 μg/mL. In conclusion, A. muricata possesses analgesic effect through interaction with opioidergic pathway and anti-inflammatory property through inhibition of chemical mediators of inflammation. PMID:25133801

  15. Impact of several pre-treatments on the extraction of phenolic compounds in winegrape varieties with different anthocyanin profiles and skin mechanical properties.

    PubMed

    Río Segade, Susana; Torchio, Fabrizio; Giacosa, Simone; Ricauda Aimonino, Davide; Gay, Paolo; Lambri, Milena; Dordoni, Roberta; Gerbi, Vincenzo; Rolle, Luca

    2014-08-20

    This study was performed to evaluate and compare the effects of different pre-treatments of whole grape berries (freezing with dry ice or in a cold room, steam blanching with different exposure times, and microwave heating with different exposure times and microwave power density) on total content of some phenolic compounds and the composition of individual anthocyanins released into the pulp during the treatment and those extracted during the maceration step. Two red winegrape varieties with different proportions of di- and trisubstituted anthocyanins were used (Nebbiolo and Barbera, respectively). Pulp-extracted anthocyanins were more significantly influenced by the pre-treatment. The results highlighted that freezing with dry ice, followed by freezing in a cold room and steam blanching for 5 min, have a great potential from an industrial point of view. They facilitated the extraction of anthocyanins in the must prior to maceration, when compared with the control samples, increasing their total content (+37.8-83.6%), and modifying the anthocyanin profile through the enrichment in the most stable compounds (+2.8-6.6% malvidin derivatives) to the detriment of others more prone to oxidation (-0.8-11.0% cyanidin derivatives). In Nebbiolo winegrapes, an improved extraction of low- and high-molecular weight flavanols into the pulp was also observed (+60.4-73.4%). Significant relationships between the phenolic composition of treated berries and the corresponding skin mechanical properties were also studied, but they were variety dependent. Discriminant analysis permitted a correct classification of the samples according to the variety and pre-treatment. PMID:25111462

  16. Mechanical properties of Bi2223 filaments extracted from multifilamentary tape evaluated by the single-fibre tensile test

    NASA Astrophysics Data System (ADS)

    Sugano, Michinaka; Osamura, Kozo; Hojo, Masaki

    2003-05-01

    The Young's modulus and the tensile fracture strength of Bi2223 filaments extracted from multifilamentary tape have been evaluated using the single-fibre tensile test; they are estimated to be 106 GPa and 45 MPa, respectively. The distribution of the fracture strength can be analysed using the Weibull distribution function. It was found that the observed scatter of strength is very large compared with other superconducting filaments such as NbTi and Nb3Al. The Young's modulus was nearly identical with the estimated values based on the rule of mixture from the unload/reload modulus.

  17. Mechanical Properties of Cells

    NASA Technical Reports Server (NTRS)

    Bradley, Robert; Becerril, Joseph; Jeevarajan, Anthony

    2007-01-01

    Many physiologic and pathologic processes alter the biomechanical properties of the tissue they affect, and these changes may be manifest at the single cell level. The normal and abnormal mechanical properties of a given cell type can be established with the aid of an atomic force microscope (AFM), nonetheless, consistency in the area of the tip has been a mayor limitation of using the AFM for quantitative measurements of mechanical properties. This project attempts to overcome this limitation by using materials with a known elastic modulus, which resembles the one of the cell, to create force-deformation curves to calculate the area of indentation by means of Hooke s Law (sigma = E(epsilon)), which states that stress (sigma) is proportional to the strain (epsilon) where the constant of proportionality, E, is called the Young s modulus, also referred as the elastic modulus. Hook s Law can be rearranged to find the area of indentation (Area= Force/ E(epsilon)), where the indentation force is defined by the means of the added mass spring calibration method.

  18. Mechanical Properties of Aerogels

    NASA Technical Reports Server (NTRS)

    Parmenter, Kelly E.; Milstein, Frederick

    1995-01-01

    Aerogels are extremely low density solids that are characterized by a high porosity and pore sizes on the order of nanometers. Their low thermal conductivity and sometimes transparent appearance make them desirable for applications such as insulation in cryogenic vessels and between double paned glass in solar architecture. An understanding of the mechanical properties of aerogels is necessary before aerogels can be used in load bearing applications. In the present study, the mechanical behavior of various types of fiber-reinforced silica aerogels was investigated with hardness, compression, tension and shear tests. Particular attention was paid to the effects of processing parameters, testing conditions, storage environment, and age on the aerogels' mechanical response. The results indicate that the addition of fibers to the aerogel matrix generally resulted in softer, weaker materials with smaller elastic moduli. Furthermore, the testing environment significantly affected compression results. Tests in ethanol show an appreciable amount of scatter, and are not consistent with results for tests in air. In fact, the compression specimens appeared to crack and begin to dissolve upon exposure to the ethanol solution. This is consistent with the inherent hydrophobic nature of these aerogels. In addition, the aging process affected the aerogels' mechanical behavior by increasing their compressive strength and elastic moduli while decreasing their strain at fracture. However, desiccation of the specimens did not appreciably affect the mechanical properties, even though it reduced the aerogel density by removing trapped moisture. Finally, tension and shear test results indicate that the shear strength of the aerogels exceeds the tensile strength. This is consistent with the response of brittle materials. Future work should concentrate on mechanical testing at cryogenic temperatures, and should involve more extensive tensile tests. Moreover, before the mechanical response

  19. Frequency domain mechanism extraction. [of localized scattering mechanisms from composite signature with two scattering mechanisms

    NASA Technical Reports Server (NTRS)

    Turhan-Sayan, Gonul; Dominek, Allen K.

    1990-01-01

    A time-domain analysis is applied to a frequency-domain technique which recovers the individual frequency characteristics of localized scattering mechanisms from a composite signature with two scattering mechanisms. This technique constructs a matrix which has filter characteristics with similar properties to a physically realizable filter based upon convolution concepts. This similarity is expanded to evaluate the rows of the matrix as filters, as demonstrated in the time domain to provide an alternate interpretation of the extraction process.

  20. Statistical mechanical treatment of reactive solvent extraction

    NASA Astrophysics Data System (ADS)

    Lukhezo, M.; Dunne, L. J.; Reuben, B. G.; Verrall, M. S.

    1997-07-01

    A statistical mechanical lattice model of a reactive solvent extraction process involving two phase liquid-liquid ion exchange is presented. It is applied to literature data on the extraction of alipathic carboxylic acids by quaternary ammonium salts. The Helmholtz free energy of the system is constructed and minimised subject to the constraints of mass balance and electroneutrality. The equations defining the equilibrium conditions have been solved numerically for a range of interaction parameters and hence the equilibrium concentrations of the various partitioned species are obtained. These interaction parameters are compared with experiment. The intuitive notion that the extent of partition is dominated by electrostatic solute-extractant interactions is shown to neglect various other interactions that may, in some systems, be important.

  1. Antigenotoxic properties of Terminalia arjuna bark extracts.

    PubMed

    Scassellati-Sforzolini, G; Villarini, L M; Moretti, L M; Marcarelli, L M; Pasquini, R; Fatigoni, C; Kaur, L S; Kumar, S; Grover, I S

    1999-01-01

    Compounds possessing antimutagenic properties (polyphenols, tannins, vitamins, etc.) have been identified in fruits, vegetables, spices, and medicinal plants. Terminalia arjuna (Combretaceae), a tropical woody tree occurring throughout India and known locally as Kumbuk, is a medicinal plant rich in tannins and triterpenes that is used extensively in Ayurvedic medicine as a cardiac tonic. The aim of the present collaborative work was to test six solvent extracts from the bark of Terminalia arjuna for antigenotoxic activity using in vitro short-term tests. Terminalia arjuna extracts were obtained by sequential extraction using acetone, methanol, methanol + HCl, chloroform, ethyl acetate, and ethyl ether. The antigenotoxic properties of these extracts were investigated by assessing the inhibition of genotoxicity of the directacting mutagen 4-nitroquinoline-N-oxide (4NQO) using the "comet" assay and the micronucleus (MN) test. Human peripheral blood leukocytes were incubated with different concentrations of the six extracts (from 5 to 100 microg/ mL) and with 4NQO (1 and 2 microg/mL, for the "comet" assay and MN test, respectively). Each extract/4NQO combination was tested twice; in each experiment, positive control (4NQO alone) and negative control (1% DMSO) were set. "Comet" assay results showed that acetone and methanol extracts were highly effective in reducing the DNA damage caused by 4NQO, whereas the acidic methanol, chloroform, ethyl acetate, and ethyl ether extracts showed less marked or no antigenotoxic activity. In the MN test, a decrease in 4NQO genotoxicity was observed by testing this mutagen in the presence of acetone, methanol, chloroform, and ethyl acetate extracts, even though the extent of inhibition was not always statistically significant. PMID:15281223

  2. Changes in triphasic mechanical properties of proteoglycan-depleted articular cartilage extracted from osmotic swelling behavior monitored using high-frequency ultrasound.

    PubMed

    Wang, Q; Zheng, Y P; Niu, H J

    2010-03-01

    This study aims to obtain osmosis-induced swelling strains of normal and proteoglycan (PG) depleted articular cartilage using an ultrasound system and to investigate the changes in its mechanical properties due to the PG depletion using a layered triphasic model. The swelling strains of 20 cylindrical cartilage-bone samples collected from different bovine patellae were induced by decreasing the concentration of bath saline and monitored by the ultrasound system. The samples were subsequently digested by a trypsin solution for approximately 20 min to deplete proteoglycans, and the swelling behaviors of the digested samples were measured again. The bi-layered triphasic model proposed in our previous study (Wang et al., J Biomech Eng-Trans ASME 2007; 129: 413-422) was used to predict the layered aggregate modulus Ha from the data of depth-dependent swelling strain, fixed charge density and water content. It was found that the region near the bone, for the normal specimens, had a significantly higher aggregate modulus (Ha1 = 20.6 +/- 18.2 MPa) in comparison with the middle zone and the surface layer (Ha2 = 7.8 +/- 14.5 MPa and Ha3 = 3.6 +/- 3.2 MPa, respectively) (p < 0.001). The normalized thickness of the deep layer h1 was 0.68 +/- 0.20. After the trypsin digestion, the parametric values decreased to Ha1 = 13.6 +/- 9.6 MPa, Ha2 = 6.7 +/- 11.5 MPa, Ha3 = 2.7 +/- 3.2 MPa, and h1 = 0.57 +/- 0.28. Other models were also used to analyze data and the results were compared. This study showed that high-frequency ultrasound measurement combined with the triphasic modeling was capable of nondestructively quantifying the alterations in the layered mechanical properties of the proteoglycan-depleted articular cartilage. PMID:20806723

  3. Mechanical properties of nanophase materials

    SciTech Connect

    Siegel, R.W.; Fougere, G.E.

    1993-11-01

    It has become possible in recent years to synthesize new materials under controlled conditions with constituent structures on a nanometer size scale (below 100 nm). These novel nanophase materials have grain-size dependent mechanical properties significantly different than those of their coarser-grained counterparts. For example, nanophase metals are much stronger and apparently less ductile than conventional metals, while nanophase ceramics are more ductile and more easily formed than conventional ceramics. The observed mechanical property changes are related to grain size limitations and/or the large percentage of atoms in grain boundary environments; they can also be affected by such features as flaw populations, strains and impurity levels that can result from differing synthesis and processing methods. An overview of what is presently known about the mechanical properties of nanophase materials, including both metals and ceramics, is presented. Some possible atomic mechanisms responsible for the observed behavior in these materials are considered in light of their unique structures.

  4. On the mechanism of extractive electrospray ionization.

    PubMed

    Law, Wai Siang; Wang, Rui; Hu, Bin; Berchtold, Christian; Meier, Lukas; Chen, Huanwen; Zenobi, Renato

    2010-06-01

    Extractive electrospray ionization (EESI) is a powerful ambient ionization technique that can provide comprehensive mass spectrometric (MS) information on aerosols, complex liquids, or suspensions without any sample pretreatment. An understanding of the EESI mechanism is critical for defining its range of application, the advantages, and limitations of EESI, and for improving its repeatability, sensitivity, and selectivity. However, no systematic study of EESI mechanisms has been conducted so far. In this work, fluorescence studies in the EESI plume using rhodamine 6G and H-acid sodium salt directly demonstrate that liquid-phase interactions occur between charged ESI droplets and neutral sample droplets. Moreover, the effect of the composition of the primary ESI spray and sample spray on signals of the analyte in EESI-MS was investigated systematically. The results show that the analyte signals strongly depend on its solubility in the solvents involved, indicating that selective extraction is the dominant mechanism involved in the EESI process. This mechanistic study provides valuable insights for optimizing the performance of EESI in future applications. PMID:20443546

  5. Mechanical Properties of Respiratory Muscles

    PubMed Central

    Sieck, Gary C.; Ferreira, Leonardo F.; Reid, Michael B.; Mantilla, Carlos B.

    2014-01-01

    Striated respiratory muscles are necessary for lung ventilation and to maintain the patency of the upper airway. The basic structural and functional properties of respiratory muscles are similar to those of other striated muscles (both skeletal and cardiac). The sarcomere is the fundamental organizational unit of striated muscles and sarcomeric proteins underlie the passive and active mechanical properties of muscle fibers. In this respect, the functional categorization of different fiber types provides a conceptual framework to understand the physiological properties of respiratory muscles. Within the sarcomere, the interaction between the thick and thin filaments at the level of cross-bridges provides the elementary unit of force generation and contraction. Key to an understanding of the unique functional differences across muscle fiber types are differences in cross-bridge recruitment and cycling that relate to the expression of different myosin heavy chain isoforms in the thick filament. The active mechanical properties of muscle fibers are characterized by the relationship between myoplasmic Ca2+ and cross-bridge recruitment, force generation and sarcomere length (also cross-bridge recruitment), external load and shortening velocity (cross-bridge cycling rate), and cross-bridge cycling rate and ATP consumption. Passive mechanical properties are also important reflecting viscoelastic elements within sarcomeres as well as the extracellular matrix. Conditions that affect respiratory muscle performance may have a range of underlying pathophysiological causes, but their manifestations will depend on their impact on these basic elemental structures. PMID:24265238

  6. Influence of grape pomace extract incorporation on chitosan films properties.

    PubMed

    Ferreira, Andreia S; Nunes, Cláudia; Castro, Alichandra; Ferreira, Paula; Coimbra, Manuel A

    2014-11-26

    Chitosan has been studied as a renewable polymer to form edible films allowing the incorporation of functional compounds. The aim of this work was to evaluate the effects in the chitosan films properties of the incorporation of grape pomace extracts: 0.15% of hot water extract (mainly polysaccharides), 0.15 and 0.3% of chloroform extract (wax), and 0.3 and 0.75% of n-hexane extract (oil). The evaluation of the surface morphology revealed that the films with the aqueous extract had the most homogeneous and smoother topography. The incorporation of higher proportion of wax and oil led to changes in mechanical properties of the films, namely lower resistance and stiffness. The chitosan-based films with 0.75% oil demonstrated a 75% decrease of solubility in water, due to their hydrophobicity, as confirmed by the contact angle and surface free energy measurements. The hydrophobic films showed higher antioxidant capacity in organic medium (ABTS and DPPH assays) whereas the most hydrophilic films showed an improvement in FRAP and reducing power assays. Therefore, all the chitosan-based films prepared by incorporation of these grape pomace extracts are promising for food shelf life extension. PMID:25256511

  7. Mechanical properties of nanocrystalline cobalt

    NASA Astrophysics Data System (ADS)

    Karimpoor, Amir A.; Erb, Uwe

    2006-05-01

    Due to their excellent wear and corrosion properties, nanocrystalline cobalt and several cobalt alloys made by electrodeposition are currently being developed as environmentally benign replacement coatings for hard chromium electrodeposits. The focus of this study is on the mechanical properties of nanocrystalline cobalt, which are currently not well understood. A comparison is presented for hardness, tensile properties, Charpy impact properties and fracture surface analysis of both nanocrystalline (grain size: 12 nm) and conventional polycrystalline (grain size: 4.8 m) cobalt. It is shown that the hardness and tensile strength of nanocrystalline cobalt is 2-3 times higher than for polycrystalline cobalt. However, in contrast to other nanocrystalline materials tested previously, nanocrystalline cobalt retains considerable ductility with elongation to fracture values up to 7%.

  8. Visual-adaptation-mechanism based underwater object extraction

    NASA Astrophysics Data System (ADS)

    Chen, Zhe; Wang, Huibin; Xu, Lizhong; Shen, Jie

    2014-03-01

    Due to the major obstacles originating from the strong light absorption and scattering in a dynamic underwater environment, underwater optical information acquisition and processing suffer from effects such as limited range, non-uniform lighting, low contrast, and diminished colors, causing it to become the bottleneck for marine scientific research and projects. After studying and generalizing the underwater biological visual mechanism, we explore its advantages in light adaption which helps animals to precisely sense the underwater scene and recognize their prey or enemies. Then, aiming to transform the significant advantage of the visual adaptation mechanism into underwater computer vision tasks, a novel knowledge-based information weighting fusion model is established for underwater object extraction. With this bionic model, the dynamical adaptability is given to the underwater object extraction task, making them more robust to the variability of the optical properties in different environments. The capability of the proposed method to adapt to the underwater optical environments is shown, and its outperformance for the object extraction is demonstrated by comparison experiments.

  9. Woven TPS Mechanical Property Evaluation

    NASA Technical Reports Server (NTRS)

    Gonzales, Gregory Lewis; Kao, David Jan-Woei; Stackpoole, Margaret M.

    2013-01-01

    Woven Thermal Protection Systems (WTPS) is a relatively new program funded by the Office of the Chief Technologist (OCT). The WTPS approach to producing TPS architectures uses precisely engineered 3-D weaving techniques that allow tailoring material characteristics needed to meet specific mission requirements. A series of mechanical tests were performed to evaluate performance of different weave types, and get a better understanding of failure modes expected in these three-dimensional architectures. These properties will aid in material down selection and guide selection of the appropriate WTPS for a potential mission.

  10. Mechanical Properties of Niobium Cavities

    SciTech Connect

    Ciovati, Gianluigi; Dhakal, Pashupati; Matalevich, Joseph R.; Myneni, Ganapati Rao

    2015-09-01

    The mechanical stability of bulk Nb cavity is an important aspect to be considered in relation to cavity material, geometry and treatments. Mechanical properties of Nb are typically obtained from uniaxial tensile tests of small samples. In this contribution we report the results of measurements of the resonant frequency and local strain along the contour of single-cell cavities made of ingot and fine-grain Nb of different purity subjected to increasing uniform differential pressure, up to 6 atm. Measurements have been done on cavities subjected to different heat treatments. Good agreement between finite element analysis simulations and experimental data in the elastic regime was obtained with a single set of values of Young’s modulus and Poisson’s ratio. The experimental results indicate that the yield strength of medium-purity ingot Nb cavities is higher than that of fine-grain, high-purity Nb.

  11. Functional properties of spice extracts obtained via supercritical fluid extraction.

    PubMed

    Leal, Patrícia F; Braga, Mara E M; Sato, Daisy N; Carvalho, João E; Marques, Marcia O M; Meireles, M Angela A

    2003-04-23

    In the present study the antioxidant, anticancer, and antimycobacterial activities of extracts from ginger (Zingiber officinale Roscoe), rosemary (Rosmarinus officinalis L.), and turmeric (Curcuma longa L.) were evaluated. The extracts were obtained using supercritical CO(2) with and without ethanol and/or isopropyl alcohol as cosolvent. The extracts' antioxidant power was assessed using the reaction between beta-carotene and linolenic acid, the antimycobacterial activity against M. tuberculosis was measured by the MABA test, and their anticancer action was tested against nine human cancer ancestries: lung, breast, breast resistant, melanoma, colon, prostate, leukemia, and kidney. The rosemary extracts exhibited the strongest antioxidant and the lowest antimycobacterial activities. Turmeric extracts showed the greatest antimycobacterial activity. Ginger and turmeric extracts showed selective anticancer activities. PMID:12696930

  12. Mechanical properties of metal dihydrides

    DOE PAGESBeta

    Schultz, Peter A.; Snow, Clark S.

    2016-02-04

    First-principles calculations are used to characterize the bulk elastic properties of cubic and tetragonal phase metal dihydrides,more » $$\\text{M}{{\\text{H}}_{2}}$$ {$$\\text{M}$$ = Sc, Y, Ti, Zr, Hf, lanthanides} to gain insight into the mechanical properties that govern the aging behavior of rare-earth di-tritides as the constituent 3H, tritium, decays into 3He. As tritium decays, helium is inserted in the lattice, the helium migrates and collects into bubbles, that then can ultimately create sufficient internal pressure to rupture the material. The elastic properties of the materials are needed to construct effective mesoscale models of the process of bubble growth and fracture. Dihydrides of the scandium column and most of the rare-earths crystalize into a cubic phase, while dihydrides from the next column, Ti, Zr, and Hf, distort instead into the tetragonal phase, indicating incipient instabilities in the phase and potentially significant changes in elastic properties. We report the computed elastic properties of these dihydrides, and also investigate the off-stoichiometric phases as He or vacancies accumulate. As helium builds up in the cubic phase, the shear moduli greatly soften, converting to the tetragonal phase. Conversely, the tetragonal phases convert very quickly to cubic with the removal of H from the lattice, while the cubic phases show little change with removal of H. Finally, the source and magnitude of the numerical and physical uncertainties in the modeling are analyzed and quantified to establish the level of confidence that can be placed in the computational results, and this quantified confidence is used to justify using the results to augment and even supplant experimental measurements.« less

  13. Mechanical properties of metal dihydrides

    NASA Astrophysics Data System (ADS)

    Schultz, Peter A.; Snow, Clark S.

    2016-03-01

    First-principles calculations are used to characterize the bulk elastic properties of cubic and tetragonal phase metal dihydrides, \\text{M}{{\\text{H}}2} {\\text{M}   =  Sc, Y, Ti, Zr, Hf, lanthanides} to gain insight into the mechanical properties that govern the aging behavior of rare-earth di-tritides as the constituent 3H, tritium, decays into 3He. As tritium decays, helium is inserted in the lattice, the helium migrates and collects into bubbles, that then can ultimately create sufficient internal pressure to rupture the material. The elastic properties of the materials are needed to construct effective mesoscale models of the process of bubble growth and fracture. Dihydrides of the scandium column and most of the rare-earths crystalize into a cubic phase, while dihydrides from the next column, Ti, Zr, and Hf, distort instead into the tetragonal phase, indicating incipient instabilities in the phase and potentially significant changes in elastic properties. We report the computed elastic properties of these dihydrides, and also investigate the off-stoichiometric phases as He or vacancies accumulate. As helium builds up in the cubic phase, the shear moduli greatly soften, converting to the tetragonal phase. Conversely, the tetragonal phases convert very quickly to cubic with the removal of H from the lattice, while the cubic phases show little change with removal of H. The source and magnitude of the numerical and physical uncertainties in the modeling are analyzed and quantified to establish the level of confidence that can be placed in the computational results, and this quantified confidence is used to justify using the results to augment and even supplant experimental measurements.

  14. Evaluation of Antioxidant and Antiangiogenic Properties of Caesalpinia Echinata Extracts

    PubMed Central

    da Silva Gomes, Elisangela Christhianne Barbosa; Jimenez, George Chaves; da Silva, Luis Claudio Nascimento; de Sá, Fabrício Bezerra; de Souza, Karen Pena Cavalcanti; Paiva, Gerson S.; de Souza, Ivone Antônia

    2014-01-01

    Natural products contain important combinations of ingredients, which may to some extent help to modulate the effects produced by oxidation substrates in biological systems. It is known that substances capable of modulating the action of these oxidants on tissue may be important allies in the control of neovascularization in pathological processes. The aim of this study was to evaluate the antioxidant and antiangiogenic properties of an ethanol extract of Caesalpinia echinata. The evaluation of antioxidant properties was tested using two methods (DPPH inhibition and sequestration of nitric oxide). The antiangiogenic properties were evaluated using the inflammatory angiogenesis model in the corneas of rats. The extract of C. echinata demonstrated a high capacity to inhibit free radicals, with IC50 equal to 42.404 µg/mL for the DPPH test and 234.2 µg/mL for nitric oxide. Moreover, it showed itself capable of inhibiting the inflammatory angiogenic response by 77.49%. These data suggest that biochemical components belonging to the extract of C. echinata interfere in mechanisms that control the angiogenic process, mediated by substrates belonging to the arachidonic acid cascade, although the data described above also suggest that the NO buffer may contribute to some extent to the reduction in the angiogenic response. PMID:24563668

  15. Mechanical Properties of Nanocrystal Supercrystals

    SciTech Connect

    Tam, Enrico; Podsiadlo, Paul; Shevchenko, Elena; Ogletree, D. Frank; Delplancke-Ogletree, Marie-Paule; Ashby, Paul D.

    2009-12-30

    Colloidal nanocrystals attract significant interest due to their potential applications in electronic, magnetic, and optical devices. Nanocrystal supercrystals (NCSCs) are particularly appealing for their well ordered structure and homogeneity. The interactions between organic ligands that passivate the inorganic nanocrystal cores critically influence their self-organization into supercrystals, By investigating the mechanical properties of supercrystals, we can directly characterize the particle-particle interactions in a well-defined geometry, and gain insight into both the self-assembly process and the potential applications of nanocrystal supercrystals. Here we report nanoindentation studies of well ordered lead-sulfide (Pbs) nanocrystal supercrystals. Their modulus and hardness were found to be similar to soft polymers at 1.7 GPa and 70 MPa respectively and the fractures toughness was 39 KPa/m1/2, revealing the extremely brittle nature of these materials.

  16. Mechanical properties of titanium connectors.

    PubMed

    Neo, T K; Chai, J; Gilbert, J L; Wozniak, W T; Engelman, M J

    1996-01-01

    The tensile mechanical properties of welded titanium joints were studied, and intact titanium was used as controls. Welded joints were fabricated with either a stereographic laser-welding technique or a gas tungsten arc welding technique. The effect of heat treatment following a simulated porcelain application was also investigated. Heat-treated laser welds had significantly lower ultimate tensile strengths. Heat treatment had no effect on the modulus of elasticity or elongation, but generally significantly decreased the yield strength of the titanium specimens. The gas tungsten are welding specimens had significantly higher yield strengths and elastic moduli than the other two groups. The elongation of the control specimens was significantly greater than the elongation of the gas tungsten arc welding specimens, which was in turn significantly higher than that of the laser-welded specimens. PMID:8957877

  17. Mechanical algal disruption for efficient biodiesel extraction

    NASA Astrophysics Data System (ADS)

    Krehbiel, Joel David

    Biodiesel from algae provides several benefits over current biodiesel feedstocks, but the energy requirements of processing algae into a useable fuel are currently so high as to be prohibitive. One route to improving this is via disruption of the cells prior to lipid extraction, which can significantly increase energy recovery. Unfortunately, several obvious disruption techniques require more energy than can be gained. This dissertation examines the use of microbubbles to improve mechanical disruption of algal cells using experimental, theoretical, and computational methods. New laboratory experiments show that effective ultrasonic disruption of algae is achieved by adding microbubbles to an algal solution. The configuration studied flows the solution through a tube and insonifies a small section with a high-pressure ultrasound wave. Previous biomedical research has shown effective cell membrane damage on animal cells with similar methods, but the present research is the first to extend such study to algal cells. Results indicate that disruption increases with peak negative pressure between 1.90 and 3.07 MPa and with microbubble concentration up to 12.5 x 107 bubbles/ml. Energy estimates of this process suggest that it requires only one-fourth the currently most-efficient laboratory-scale disruption process. Estimates of the radius near each bubble that causes disruption (i.e. the disruption radius) suggest that it increases with peak negative pressure and is near 9--20 microm for all cases tested. It is anticipated that these procedures can be designed for better efficiency and efficacy, which will be facilitated by identifying the root mechanisms of the bubble-induced disruption. We therefore examine whether bubble expansion alone creates sufficient cell deformation for cell rupture. The spherically-symmetric Marmottant model for bubble dynamics allows estimation of the flow regime under experimental conditions. Bubble expansion is modeled as a point source of

  18. Mechanical Properties of Primary Cilia

    NASA Astrophysics Data System (ADS)

    Battle, Christopher; Schmidt, Christoph F.

    2013-03-01

    Recent studies have shown that the primary cilium, long thought to be a vestigial cellular appendage with no function, is involved in a multitude of sensory functions. One example, interesting from both a biophysical and medical standpoint, is the primary cilium of kidney epithelial cells, which acts as a mechanosensitive flow sensor. Genetic defects in ciliary function can cause, e.g., polycystic kidney disease (PKD). The material properties of these non-motile, microtubule-based 9 +0 cilia, and the way they are anchored to the cell cytoskeleton, are important to know if one wants to understand the mechano-electrochemical response of these cells, which is mediated by their cilia. We have probed the mechanical properties, boundary conditions, and dynamics of the cilia of MDCK cells using optical traps and DIC/fluorescence microscopy. We found evidence for both elastic relaxation of the cilia themselves after bending and for compliance in the intracellular anchoring structures. Angular and positional fluctuations of the cilia reflect both thermal excitations and cellular driving forces.

  19. Mechanical algal disruption for efficient biodiesel extraction

    NASA Astrophysics Data System (ADS)

    Krehbiel, Joel David

    Biodiesel from algae provides several benefits over current biodiesel feedstocks, but the energy requirements of processing algae into a useable fuel are currently so high as to be prohibitive. One route to improving this is via disruption of the cells prior to lipid extraction, which can significantly increase energy recovery. Unfortunately, several obvious disruption techniques require more energy than can be gained. This dissertation examines the use of microbubbles to improve mechanical disruption of algal cells using experimental, theoretical, and computational methods. New laboratory experiments show that effective ultrasonic disruption of algae is achieved by adding microbubbles to an algal solution. The configuration studied flows the solution through a tube and insonifies a small section with a high-pressure ultrasound wave. Previous biomedical research has shown effective cell membrane damage on animal cells with similar methods, but the present research is the first to extend such study to algal cells. Results indicate that disruption increases with peak negative pressure between 1.90 and 3.07 MPa and with microbubble concentration up to 12.5 x 107 bubbles/ml. Energy estimates of this process suggest that it requires only one-fourth the currently most-efficient laboratory-scale disruption process. Estimates of the radius near each bubble that causes disruption (i.e. the disruption radius) suggest that it increases with peak negative pressure and is near 9--20 microm for all cases tested. It is anticipated that these procedures can be designed for better efficiency and efficacy, which will be facilitated by identifying the root mechanisms of the bubble-induced disruption. We therefore examine whether bubble expansion alone creates sufficient cell deformation for cell rupture. The spherically-symmetric Marmottant model for bubble dynamics allows estimation of the flow regime under experimental conditions. Bubble expansion is modeled as a point source of

  20. Extraction kinetics and properties of proanthocyanidins from pomegranate peel

    Technology Transfer Automated Retrieval System (TEKTRAN)

    With an objective of developing a safe and efficient method to extract proanthocyanidins products from pomegranate peel for use in nutraceuticals or as food additives, the effects of extraction parameters on the production efficiency, product properties, and extraction kinetics were systematically s...

  1. Antimicrobial Properties of Teas and Their Extracts in vitro.

    PubMed

    Siddiqui, Md Wasim; Sharangi, A B; Singh, J P; Thakur, Pran K; Ayala-Zavala, J F; Singh, Archana; Dhua, R S

    2016-07-01

    Tea has recently received the attention of pharmaceutical and scientific communities due to the plethora of natural therapeutic compounds. As a result, numerous researches have been published in a bid to validate their biological activity. Moreover, major attention has been drawn to antimicrobial activities of tea. Being rich in phenolic compounds, tea has the preventive potential for colon, esophageal, and lung cancers, as well as urinary infections and dental caries, among others. The venture of this review was to illustrate the emerging findings on the antimicrobial properties of different teas and tea extracts, which have been obtained from several in vitro studies investigating the effects of these extracts against different microorganisms. Resistance to antimicrobial agents has become an increasingly important and urgent global problem. The extracts of tea origin as antimicrobial agents with new mechanisms of resistance would serve an alternative way of antimicrobial chemotherapy targeting the inhibition of microbial growth and the spread of antibiotic resistance with potential use in pharmaceutical, cosmetic, and food industries. PMID:25675116

  2. Anti-Fatigue Properties of Tartary Buckwheat Extracts in Mice

    PubMed Central

    Jin, Hong-Mei; Wei, Ping

    2011-01-01

    Anti-fatigue properties of tartary buckwheat extracts (TBE) was investigated in male Kunming mice. The animals were divided into four groups. The first group, designated as the control group (control), was administered with distilled water by gavage every day for 28 days. The other three groups, designated as TBE treatment groups, were administered with TBE of 60, 120 and 240 mg/kg body weight, respectively, by gavage every day for 28 days. Exhaustive swimming time, blood lactic acid (BLA), blood urea nitrogen (BUN), tissue glycogen, glutathione peroxidase (GPx) and superoxide dismutase (SOD) of mice after swimming were determined. The results showed that tartary buckwheat extracts had anti-fatigue properties, which extended the exhaustive swimming time of mice, effectively inhibiting the increase of BLA, decreasing the level of BUN, increasing the tissue glycogen content and the activities of SOD and GPx of mice. However, further study is needed to elucidate the exact mechanism of the effect of TBE on fatigue. PMID:21954324

  3. Enhancement of mechanical properties of 123 superconductors

    DOEpatents

    Balachandran, Uthamalingam

    1995-01-01

    A composition and method of preparing YBa.sub.2 Cu.sub.3 O.sub.7-x superconductor. Addition of tin oxide containing compounds to YBCO superconductors results in substantial improvement of fracture toughness and other mechanical properties without affect on T.sub.c. About 5-20% additions give rise to substantially improved mechanical properties.

  4. Enhancement of mechanical properties of 123 superconductors

    DOEpatents

    Balachandran, U.

    1995-04-25

    A composition and method are disclosed of preparing YBa{sub 2}Cu{sub 3}O{sub 7{minus}x} superconductor. Addition of tin oxide containing compounds to YBCO superconductors results in substantial improvement of fracture toughness and other mechanical properties without affect on T{sub c}. About 5-20% additions give rise to substantially improved mechanical properties.

  5. The Antinociceptive Properties of the Corydalis yanhusuo Extract.

    PubMed

    Wang, Lien; Zhang, Yan; Wang, Zhiwei; Gong, Nian; Kweon, Tae Dong; Vo, Benjamin; Wang, Chaoran; Zhang, Xiuli; Chung, Jae Yoon; Alachkar, Amal; Liang, Xinmiao; Luo, David Z; Civelli, Olivier

    2016-01-01

    Corydalis yanhusuo. W.T. extracts (YHS) are widely used for the treatment of pain and inflammation. There are a few studies that assessed the effects of YHS in pain assays; however, none of these studies has systematically compared its activities in the different pain animal modes namely: acute, inflammatory and chronic pain. Furthermore, little is known about the mechanism of YHS activity in these assays. The aim of this study was to systematically evaluate the antinociceptive properties of YHS by testing it in four standardized pain assays and to investigate its mechanism. YHS antinociceptive properties were analyzed in the tail flick, the formalin paw licking, the von Frey filament and the hot box assays after spinal nerve ligation, which monitors acute nociceptive, persistent inflammatory and chronic neuropathic pain, respectively. YHS pharmacological profile was determined by screening it against a battery of G-protein coupled receptors and its mechanism of action was studied using knock-out mice. Our study shows that YHS, at a non-sedative dose, increases the tail flick latency in the tail flick assay without resulting in development of tolerance. YHS also decreases paw licking time in the formalin assay. Further, YHS increases paw withdraw threshold and latency in the von Frey filament and the hot box assays, respectively. In vitro, YHS exhibits prominent dopamine receptor antagonistic properties. In dopamine D2 receptor knockout mice, its antinociceptive effects are attenuated in acute and neuropathic pain but not inflammatory pain assays. Our results therefore indicate that YHS effectively attenuates acute, inflammatory and neuropathic pain, without causing tolerance. The effects on acute and neuropathic pain, but not inflammatory pain, are at least partially mediated through dopamine D2 receptor antagonism. Since YHS is a dietary supplement commercially available in the United States, our data suggest that it might be a candidate for alternative pain

  6. Bioactive phytochemicals in wheat: Extraction, analysis, processing, and functional properties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Whole wheat provides a rich source of bioactive phytochemicals namely, phenolic acids, carotenoids, tocopherols, alkylresorcinols, arabinoxylans, benzoxazinoids, phytosterols, and lignans. This review provides information on the distribution, extractability, analysis, and nutraceutical properties of...

  7. Mechanical property characterization of polymeric composites reinforced by continuous microfibers

    NASA Astrophysics Data System (ADS)

    Zubayar, Ali

    Innumerable experimental works have been conducted to study the effect of polymerization on the potential properties of the composites. Experimental techniques are employed to understand the effects of various fibers, their volume fractions and matrix properties in polymer composites. However, these experiments require fabrication of various composites which are time consuming and cost prohibitive. Advances in computational micromechanics allow us to study the various polymer based composites by using finite element simulations. The mechanical properties of continuous fiber composite strands are directional. In traditional continuous fiber laminated composites, all fibers lie in the same plane. This provides very desirable increases in the in-plane mechanical properties, but little in the transverse mechanical properties. The effect of different fiber/matrix combinations with various orientations is also available. Overall mechanical properties of different micro continuous fiber reinforced composites with orthogonal geometry are still unavailable in the contemporary research field. In this research, the mechanical properties of advanced polymeric composite reinforced by continuous micro fiber will be characterized based on analytical investigation and FE computational modeling. Initially, we have chosen IM7/PEEK, Carbon Fiber/Nylon 6, and Carbon Fiber/Epoxy as three different case study materials for analysis. To obtain the equivalent properties of the micro-hetero structures, a concept of micro-scale representative volume elements (RVEs) is introduced. Five types of micro scale RVEs (3 square and 2 hexagonal) containing a continuous micro fiber in the polymer matrix were designed. Uniaxial tensile, lateral expansion and transverse shear tests on each RVE were designed and conducted by the finite element computer modeling software ANSYS. The formulae based on elasticity theory were derived for extracting the equivalent mechanical properties (Young's moduli, shear

  8. Microstructure and mechanical properties of sheep horn.

    PubMed

    Zhu, Bing; Zhang, Ming; Zhao, Jian

    2016-07-01

    The sheep horn presents outstanding mechanical properties of impact resistance and energy absorption, which suits the need of the vehicle bumper design, but the mechanism behind this phenomenon is less investigated. The microstructure and mechanical properties of the sheep horn of Small Tailed Han Sheep (Ovis aries) living in northeast China were investigated in this article. The effect of sampling position and orientation of the sheep horn sheath on mechanical properties were researched by tensile and compression tests. Meanwhile, the surface morphology and microstructure of the sheep horn were observed using scanning electron microscopy (SEM). The formation mechanism of the mechanical properties of the sheep horn was investigated by biological coupling analysis. The analytical results indicated that the outstanding mechanical properties of the sheep horn are determined by configuration, structure, surface morphology and material coupling elements. These biological coupling elements make the sheep horn possess super characteristics of crashworthiness and energy absorption through the internal coupling mechanism. We suppose that these findings would make a difference in vehicle bumper design. Microsc. Res. Tech. 79:664-674, 2016. © 2016 Wiley Periodicals, Inc. PMID:27184115

  9. Extract from Ceratonia siliqua Exhibits Depigmentation Properties.

    PubMed

    Lall, Namrita; Kishore, Navneet; Momtaz, Saeideh; Hussein, Ahmed; Naidoo, Sanushka; Nqephe, Mabatho; Crampton, Bridget

    2015-11-01

    Skin hyper-pigmentation is a condition initiated by the overproduction of melanin existing in the melanocytes. Melanin pigment is responsible for the colour of skin in humans. It is formed through a series of oxidative reactions involving the amino acid tyrosine in the presence of the key enzyme tyrosinase. In continuation with our efforts to identify tyrosinase inhibitors from plants sources, the methanol extract from leaf, bark and fruit of Ceratonia siliqua were screened for tyrosinase inhibition and diphenolase activity. The bark extract exhibited significant inhibition on mushroom tyrosinase using L-tyrosine as a substrate and showed diphenolase activity. The extract further significantly lowered tyrosinase mRNA levels in B16-F10 mouse melanocytes. Bioassay-guided fractionation led to the isolation of six compounds. Compounds (-)-epicatechin-3-O-gallate, 1,2,3,6-tetra-O-galloyl-ß-D-glucose and gallocatechin-3-O-gallate showed tyrosinase inhibitions with the IC50 values of 27.52, 83.30 and 28.30 µg/mL, respectively. These compounds also exhibited L-DOPA activities with IC50 values of >200, 150 and 200 µg/mL, respectively. A clinical study was conducted using 20 volunteers in a patch testing trial for irritancy potential and skin depigmentation. The clinical results showed the sample to be non-irritant with irritancy potential of -34.21 and depigmentation trial showed an improvement in the even skin tone of UV induced pigmentation at 3% after 28 days of application. PMID:26201055

  10. Mechanical property characterization of intraply hybrid composites

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.; Lark, R. F.; Sinclair, J. H.

    1979-01-01

    An investigation of the mechanical properties of intraply hybrids made from graphite fiber/epoxy matrix hybridized with secondary S-glass or Kevlar 49 fiber composites is presented. The specimen stress-strain behavior was determined, showing that mechanical properties of intraply hybrid composites can be measured with available methods such as the ten-degree off-axis test for intralaminar shear, and conventional tests for tensile, flexure, and Izod impact properties. The results also showed that combinations of high modulus graphite/S-glass/epoxy matrix composites exist which yield intraply hybrid laminates with the best 'balanced' properties, and that the translation efficiency of mechanical properties from the constituent composites to intraply hybrids may be assessed with a simple equation.

  11. Mechanical Behavior of Agave Americana L. Fibres: Correlation Between Fine Structure and Mechanical Properties

    NASA Astrophysics Data System (ADS)

    Msahli, S.; Chaabouni, Y.; Sakli, F.; Drean, J. Y.

    In this study, results of a mechanical behavior study of fibres extracted from the agave Americana L. plant, the most abundant variety in Tunisia, are presented. These results deal with the principal and mechanical characteristics of these fibres which are the elongation at break, the elasticity modulus and the rupture facture. These results permitted to situate these fibres, compared to the other textile fibres, as materials that can be used in technical applications such as reinforcing composites or geotextile. In order to understand the mechanical properties of these fibres, a correlation study between the properties already cited and the fine structure was done. The obtained results showed that the mechanical properties of agave Americana L. fibres are closely related to the individual fibers deformations and to the natural matrix (lignin and gums) that links these elementary fibres.

  12. Mechanical properties of low tantalum alloys

    NASA Technical Reports Server (NTRS)

    Kortovich, C. S.

    1982-01-01

    The mechanical property behavior of equiaxed cast B-1900 + Hf alloy as a function of tantalum content was studied. Tensile and stress rupture characterization was conducted on cast to size test bars containing tantalum at the 4.3% (standard level), 2.2% and 0% levels. Casting parameters were selected to duplicate conditions used to prepare test specimens for master metal heat qualification. The mechanical property results as well as results of microstructural/phase analysis of failed test bars are presented.

  13. Electron extraction mechanisms of a micro-ECR neutralizer

    NASA Astrophysics Data System (ADS)

    Takao, Yoshinori; Hiramoto, Kenta; Nakagawa, Yuichi; Kasagi, Yusuke; Koizumi, Hiroyuki; Komurasaki, Kimiya

    2016-07-01

    Three-dimensional particle simulations have been conducted to analyze the mechanisms of electron extraction through the orifices of a 4.2 GHz microwave discharge microneutralizer, using a xenon electron cyclotron resonance plasma. The dimensions of the neutralizer are 20 × 20 × 4 mm3, and a ring-shaped microwave antenna and permanent magnets are employed for its discharges. The numerical model is composed of a particle-in-cell simulation with a Monte Carlo collision algorithm for charged particle motions, a finite-difference time-domain method for microwaves, and a finite element analysis for magnetostatic fields. The simulation results have shown that the electrostatic field inside the plasma source has a dominant effect on electron extraction. The extracted electrons move along the magnetic field line to the orifice entrances and the E × B drift at the orifice edge induces electron extraction.

  14. Thigmomorphogenesis: on the mechanical properties of mechanically perturbed bean plants.

    PubMed

    Jaffe, M J; Telewski, F W; Cooke, P W

    1984-01-01

    The mechanical properties of control and mechanically perturbed (MP) bean stems (Phaseolus vulgaris L., cv. Cherokee wax) were compared. The rubbed plants were greatly hardened against mechanical rupture by previous MP. This hardening was due to a dramatic increase in the flexibility of the stems, but not in their stiffness. The MP-plants were able to bend more than 90 degree without breaking, whereas the control plants broke after just slight bending. A comparison with other work reveals that different species utilize different tactics for achieving similar resistance to rupture due to mechanical stress. PMID:11540788

  15. Mechanical properties of mesoporous ceria nanoarchitectures.

    PubMed

    Sayle, Thi X T; Inkson, Beverley J; Möbus, Günter; Parker, Stephen C; Seal, Sudipta; Sayle, Dean C

    2014-12-01

    Architectural constructs are engineered to impart desirable mechanical properties facilitating bridges spanning a thousand meters and buildings nearly 1 km in height. However, do the same 'engineering-rules' translate to the nanoscale, where the architectural features are less than 0.0001 mm in size? Here, we calculate the mechanical properties of a porous ceramic functional material, ceria, as a function of its nanoarchitecture using molecular dynamics simulation and predict its yield strength to be almost two orders of magnitude higher than the parent bulk material. In particular, we generate models of nanoporous ceria with either a hexagonal or cubic array of one-dimensional pores and simulate their responses to mechanical load. We find that the mechanical properties are critically dependent upon the orientation between the crystal structure (symmetry, direction) and the pore structure (symmetry, direction). PMID:25322448

  16. Evaluation of Skin Colouring Properties of Curcuma Longa Extract

    PubMed Central

    Arct, J.; Ratz-Łyko, Anna; Mieloch, M.; Witulska, M.

    2014-01-01

    The aim of this study was to evaluate the skin colouring properties of curcuma extract in cosmetic formulations. Objective measurements of the skin colour changes were done by Chromameter using the CIE L*a*b* colour space parameters. These measurements were correlated with the results of the sensory analysis. The observations showed permanent, visible and statistically significant changing of b* component after one application of emulsions containing 12% and 25% of turmeric extract. The change of skin color remained also after removing the emulsion. Sensory analysis indicated that the tested emulsions with curcuma extract have a significant impact on skin smoothness, spreadability, cosmetic absorption and pillow effect. PMID:25284937

  17. Silk Fibroin Degradation Related to Rheological and Mechanical Properties.

    PubMed

    Partlow, Benjamin P; Tabatabai, A Pasha; Leisk, Gary G; Cebe, Peggy; Blair, Daniel L; Kaplan, David L

    2016-05-01

    Regenerated silk fibroin has been proposed as a material substrate for biomedical, optical, and electronic applications. Preparation of the silk fibroin solution requires extraction (degumming) to remove contaminants, but results in the degradation of the fibroin protein. Here, a mechanism of fibroin degradation is proposed and the molecular weight and polydispersity is characterized as a function of extraction time. Rheological analysis reveals significant changes in the viscosity of samples while mechanical characterization of cast and drawn films shows increased moduli, extensibility, and strength upon drawing. Fifteen minutes extraction time results in degraded fibroin that generates the strongest films. Structural analysis by wide angle X-ray scattering (WAXS) and Fourier transform infrared spectroscopy (FTIR) indicates molecular alignment in the drawn films and shows that the drawing process converts amorphous films into the crystalline, β-sheet, secondary structure. Most interesting, by using selected extraction times, films with near-native crystallinity, alignment, and molecular weight can be achieved; yet maximal mechanical properties for the films from regenerated silk fibroin solutions are found with solutions subjected to some degree of degradation. These results suggest that the regenerated solutions and the film casting and drawing processes introduce more complexity than native spinning processes. PMID:26756449

  18. Antibacterial mechanism and activities of black pepper chloroform extract.

    PubMed

    Zou, Lan; Hu, Yue-Ying; Chen, Wen-Xue

    2015-12-01

    Black pepper extracts reportedly inhibit food spoilage and food pathogenic bacteria. This study explored the antimicrobial activity of black pepper chloroform extract (BPCE) against Escherichia coli and Staphylococcus aureus. The antibacterial mechanism of BPCE was elucidated by analyzing the cell morphology, respiratory metabolism, pyruvic acid content, and ATP levels of the target bacteria. Scanning electron micrographs showed that the bacterial cells were destroyed and that plasmolysis was induced. BPCE inhibited the tricarboxylic acid pathway of the bacteria. The extract significantly increased pyruvic acid concentration in bacterial solutions and reduced ATP level in bacterial cells. BPCE destroyed the permeability of the cell membrane, which consequently caused metabolic dysfunction, inhibited energy synthesis, and triggered cell death. PMID:26604394

  19. Mechanical properties of the brain-skull interface.

    PubMed

    Mazumder, Mohammad Mynuddin Gani; Miller, Karol; Bunt, Stuart; Mostayed, Ahmed; Joldes, Grand; Day, Robert; Hart, Robin; Wittek, Adam

    2013-01-01

    Knowledge of the mechanical properties of the brain-skull interface is important for surgery simulation and injury biomechanics. These properties are known only to a limited extent. In this study we conducted in situ indentation of the sheep brain, and proposed to derive the macroscopic mechanical properties of the brain-skull interface from the results of these experiments. To the best of our knowledge, this is the first ever analysis of this kind. When conducting in situ indentation of the brain, the reaction force on the indentor was measured. After the indentation, a cylindrical sample of the brain tissue was extracted and subjected to uniaxial compression test. A model of the brain indentation experiment was built in the Finite Element (FE) solver ABAQUS™. In the model, the mechanical properties of the brain tissue were assigned as obtained from the uniaxial compression test and the brain-skull interface was modeled as linear springs. The interface stiffness (defined as sum of stiffnesses of the springs divided by the interface area) was varied to obtain good agreement between the calculated and experimentally measured indentor force-displacement relationship. Such agreement was found to occur for the brain-skull interface stiffness of 11.45 Nmm⁻¹/mm². This allowed identification of the overall mechanical properties of the brain-skull interface. PMID:23951996

  20. The mechanical properties of FeAl

    SciTech Connect

    Baker, I.; George, E.P.

    1996-12-31

    Only in the last few years has progress been made in obtaining reproducible mechanical properties data for FeAl. Two sets of observations are the foundation of this progress. The first is that the large vacancy concentrations that exist in FeAl at high temperature are easily retained at low temperature and that these strongly affect the low-temperature mechanical properties. The second is that RT ductility is adversely affected by water vapor. Purpose of this paper is not to present a comprehensive overview of the mechanical properties of FeAl but rather to highlight our understanding of key phenomena and to show how an understanding of the factors which control the yield strength and fracture behavior has followed the discovery of the above two effects. 87 refs, 9 figs.

  1. Yellow Mealworm Protein for Food Purposes - Extraction and Functional Properties.

    PubMed

    Zhao, Xue; Vázquez-Gutiérrez, José Luis; Johansson, Daniel P; Landberg, Rikard; Langton, Maud

    2016-01-01

    A protocol for extraction of yellow mealworm larvae proteins was established, conditions were evaluated and the resulting protein extract was characterised. The freeze-dried yellow mealworm larvae contained around 33% fat, 51% crude protein and 43% true protein on a dry matter basis. The true protein content of the protein extract was about 75%, with an extraction rate of 70% under optimised extraction conditions using 0.25 M NaOH, a NaOH solution:ethanol defatted worm ratio of 15:1 mL/g, 40°C for 1 h and extraction twice. The protein extract was a good source of essential amino acids. The lowest protein solubility in distilled water solution was found between pH 4 and 5, and increased with either increasing or decreasing pH. Lower solubility was observed in 0.5 M NaCl solution compared with distilled water. The rheological tests indicated that temperature, sample concentration, addition of salt and enzyme, incubation time and pH alterations influenced the elastic modulus of yellow mealworm protein extract (YMPE). These results demonstrate that the functional properties of YMPE can be modified for different food applications. PMID:26840533

  2. Yellow Mealworm Protein for Food Purposes - Extraction and Functional Properties

    PubMed Central

    Zhao, Xue; Vázquez-Gutiérrez, José Luis; Johansson, Daniel P.; Landberg, Rikard; Langton, Maud

    2016-01-01

    A protocol for extraction of yellow mealworm larvae proteins was established, conditions were evaluated and the resulting protein extract was characterised. The freeze-dried yellow mealworm larvae contained around 33% fat, 51% crude protein and 43% true protein on a dry matter basis. The true protein content of the protein extract was about 75%, with an extraction rate of 70% under optimised extraction conditions using 0.25 M NaOH, a NaOH solution:ethanol defatted worm ratio of 15:1 mL/g, 40°C for 1 h and extraction twice. The protein extract was a good source of essential amino acids. The lowest protein solubility in distilled water solution was found between pH 4 and 5, and increased with either increasing or decreasing pH. Lower solubility was observed in 0.5 M NaCl solution compared with distilled water. The rheological tests indicated that temperature, sample concentration, addition of salt and enzyme, incubation time and pH alterations influenced the elastic modulus of yellow mealworm protein extract (YMPE). These results demonstrate that the functional properties of YMPE can be modified for different food applications. PMID:26840533

  3. Mechanism and analyses for extracting photosynthetic electrons using exogenous quinones - what makes a good extraction pathway?

    PubMed

    Longatte, G; Rappaport, F; Wollman, F-A; Guille-Collignon, M; Lemaître, F

    2016-08-01

    Plants or algae take many benefits from oxygenic photosynthesis by converting solar energy into chemical energy through the synthesis of carbohydrates from carbon dioxide and water. However, the overall yield of this process is rather low (about 4% of the total energy available from sunlight is converted into chemical energy). This is the principal reason why recently many studies have been devoted to extraction of photosynthetic electrons in order to produce a sustainable electric current. Practically, the electron transfer occurs between the photosynthetic organism and an electrode and can be assisted by an exogenous mediator, mainly a quinone. In this regard, we recently reported on a method involving fluorescence measurements to estimate the ability of different quinones to extract photosynthetic electrons from a mutant of Chlamydomonas reinhardtii. In the present work, we used the same kind of methodology to establish a zone diagram for predicting the most suitable experimental conditions to extract photoelectrons from intact algae (quinone concentration and light intensity) as a function of the purpose of the study. This will provide further insights into the extraction mechanism of photosynthetic electrons using exogenous quinones. Indeed fluorescence measurements allowed us to model the capacity of photosynthetic algae to donate electrons to an exogenous quinone by considering a numerical parameter called "open center ratio" which is related to the Photosystem II acceptor redox state. Then, using it as a proxy for investigating the extraction of photosynthetic electrons by means of an exogenous quinone, 2,6-DCBQ, we suggested an extraction mechanism that was globally found consistent with the experimentally extracted parameters. PMID:27411477

  4. Extensive screening for herbal extracts with potent antioxidant properties

    PubMed Central

    Niwano, Yoshimi; Saito, Keita; Yoshizaki, Fumihiko; Kohno, Masahiro; Ozawa, Toshihiko

    2011-01-01

    This paper summarizes our research for herbal extracts with potent antioxidant activity obtained from a large scale screening based on superoxide radical (O2•−) scavenging activity followed by characterization of antioxidant properties. Firstly, scavenging activity against O2•− was extensively screened from ethanol extracts of approximately 1000 kinds of herbs by applying an electron spin resonance (ESR)-spin trapping method, and we chose four edible herbal extracts with prominently potent ability to scavenge O2•−. They are the extracts from Punica granatum (Peel), Syzygium aromaticum (Bud), Mangifera indica (Kernel), and Phyllanthus emblica (Fruit). These extracts were further examined to determine if they also scavenge hydroxyl radical (•OH), by applying the ESR spin-trapping method, and if they have heat resistance as a desirable characteristic feature. Experiments with the Fenton reaction and photolysis of H2O2 induced by UV irradiation demonstrated that all four extracts have potent ability to directly scavenge •OH. Furthermore, the scavenging activities against O2•− and •OH of the extracts of P. granatum (peel), M. indica (kernel) and P. emblica (fruit) proved to be heat-resistant. The results of the review might give useful information when choosing a potent antioxidant as a foodstuff. For instance, the four herbal extracts chosen from extensive screening possess desirable antioxidant properties. In particular, the extracts of the aforementioned three herbs are expected to be suitable for food processing in which thermal devices are used, because of their heat resistance. PMID:21297917

  5. Stainless Steel Microstructure and Mechanical Properties Evaluation

    SciTech Connect

    Switzner, Nathan T

    2010-06-01

    A nitrogen strengthened 21-6-9 stainless steel plate was spinformed into hemispherical test shapes. A battery of laboratory tests was used to characterize the hemispheres. The laboratory tests show that near the pole (axis) of a spinformed hemisphere the yield strength is the lowest because this area endures the least “cold-work” strengthening, i.e., the least deformation. The characterization indicated that stress-relief annealing spinformed stainless steel hemispheres does not degrade mechanical properties. Stress-relief annealing reduces residual stresses while maintaining relatively high mechanical properties. Full annealing completely eliminates residual stresses, but reduces yield strength by about 30%.

  6. Mechanical Properties of Ingot Nb Cavities

    SciTech Connect

    Ciovati, Gianluigi; Dhakal, Pashupati; Kneisel, Peter; Mammosser, John; Matalevich, Joseph; Rao Myneni, Ganapati

    2014-07-01

    This contribution presents the results of measurements of the resonant frequency and of strain along the contour of a single-cell cavity made of ingot Nb subjected to increasing uniform differential pressure, up to 6 atm. The data were used to infer mechanical properties of this material after cavity fabrication, by comparison with the results from simulation calculations done with ANSYS. The objective is to provide useful information about the mechanical properties of ingot Nb cavities which can be used in the design phase of SRF cavities intended to be built with this material.

  7. Mechanical properties of Silicon Carbide Nanowires

    NASA Astrophysics Data System (ADS)

    Alkhateeb, Abdullah; Zhang, Daqing; McIlroy, David; Aston, David Eric

    2004-05-01

    Silicon carbide nanowires could be potentially useful for high strength materials which lead to the interest in understanding their mechanical properties. In this report we use the digital pulse force microscopy to analyze the mechanical properties of SiC nanowires .Stiffness and adhesion images of SiC nanowires on silicon grating were obtained and calibrated force-distance curves were plotted along the wire which spans on a 1.5 micron trench. Moreover, spring constant and Young's modules have been calculated from the linear part of the force-distance curves.

  8. Chemical properties and oxidative stability of perilla oils obtained from roasted perilla seeds as affected by extraction methods.

    PubMed

    Jung, Dong Min; Yoon, Suk Hoo; Jung, Mun Yhung

    2012-12-01

    The chemical properties and oxidative stability of perilla oils obtained from roasted perilla seeds as affected by extraction methods (supercritical carbon dioxide [SC-CO(2)], mechanical press, and solvent extraction) were studied. The SC-CO(2) extraction at 420 bar and 50 °C and hexane extraction showed significantly higher oil yield than mechanical press extraction (P < 0.05). The fatty acid compositions in the oils were virtually identical regardless of the extraction methods. The contents of tocopherol, sterol, policosanol, and phosphorus in the perilla oils greatly varied with the extraction methods. The SC-CO(2) -extracted perilla oils contained significantly higher contents of tocopherols, sterols, and policosanols than the mechanical press-extracted and hexane-extracted oils (P < 0.05). The SC-CO(2) -extracted oil showed the greatly lower oxidative stability than press-extracted and hexane-extracted oils during the storage in the oven under dark at 60 °C. However, the photooxidative stabilities of the oils were not considerably different with extraction methods. PMID:23106331

  9. Mechanical Properties Of Large Sodium Iodide Crystals

    NASA Technical Reports Server (NTRS)

    Lee, Henry M.

    1988-01-01

    Report presents data on mechanical properties of large crystals of thallium-doped sodium iodide. Five specimens in shape of circular flat plates subjected to mechanical tests. Presents test results for each specimen as plots of differential pressure versus center displacement and differential pressure versus stress at center. Also tabulates raw data. Test program also developed procedure for screening candidate crystals for gamma-ray sensor. Procedure eliminates potentially weak crystals before installed and ensures material yielding kept to minimum.

  10. Mechanical properties of polygonal carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Huang, Ling; Cao, Dapeng

    2012-08-01

    A group of polygonal carbon nanotubes (P-CNTs) have been designed and their mechanical behavior was investigated by classical molecular dynamics simulations. The research aimed at exploring the effects of structure, temperature, and strain rate on the mechanical properties. The results indicate that the Young's modulus of P-CNTs is lower than those of circumcircle carbon nanotubes (C-CNT). Moreover, with an increase in the number of sides to the polygons, the Young's modulus increases and is much closer to that of C-CNT. The effects of temperature and strain rate on the mechanical properties of P-CNTs show that the higher temperature and slower strain rate result in a lower critical strain and weaker tensile strength. In addition, it was found that the critical strains of P-CNTs are dependent on the tube size. Finally, we used the transition-state theory model to predict the critical strain of P-CNTs at given experimental conditions. It is expected that this work could provide feasible means to manipulate the mechanical properties of novel P-CNTs and facilitate the mechanical application of nanostructures as potential electronic devices.A group of polygonal carbon nanotubes (P-CNTs) have been designed and their mechanical behavior was investigated by classical molecular dynamics simulations. The research aimed at exploring the effects of structure, temperature, and strain rate on the mechanical properties. The results indicate that the Young's modulus of P-CNTs is lower than those of circumcircle carbon nanotubes (C-CNT). Moreover, with an increase in the number of sides to the polygons, the Young's modulus increases and is much closer to that of C-CNT. The effects of temperature and strain rate on the mechanical properties of P-CNTs show that the higher temperature and slower strain rate result in a lower critical strain and weaker tensile strength. In addition, it was found that the critical strains of P-CNTs are dependent on the tube size. Finally, we used the

  11. Laminar Tendon Composites with Enhanced Mechanical Properties

    PubMed Central

    Alberti, Kyle A.; Sun, Jeong-Yun; Illeperuma, Widusha R.; Suo, Zhigang; Xu, Qiaobing

    2015-01-01

    Purpose A strong isotropic material that is both biocompatible and biodegradable is desired for many biomedical applications, including rotator cuff repair, tendon and ligament repair, vascular grafting, among others. Recently, we developed a technique, called “bioskiving” to create novel 2D and 3D constructs from decellularized tendon, using a combination of mechanical sectioning, and layered stacking and rolling. The unidirectionally aligned collagen nanofibers (derived from sections of decellularized tendon) offer good mechanical properties to the constructs compared with those fabricated from reconstituted collagen. Methods In this paper, we studied the effect that several variables have on the mechanical properties of structures fabricated from tendon slices, including crosslinking density and the orientation in which the fibers are stacked. Results We observed that following stacking and crosslinking, the strength of the constructs is significantly improved, with crosslinked sections having an ultimate tens ile strength over 20 times greater than non-crosslinked samples, and a modulus nearly 50 times higher. The mechanism of the mechanical failure mode of the tendon constructs with or without crosslinking was also investigated. Conclusions The strength and fiber organization, combined with the ability to introduce transversely isotropic mechanical properties makes the laminar tendon composites a biocompatiable material that may find future use in a number of biomedical and tissue engineering applications. PMID:25691802

  12. Synergism in a HDEHP/TOPO Liquid-Liquid Extraction System: An Intrinsic Ligands Property?

    PubMed

    Pecheur, O; Dourdain, S; Guillaumont, D; Rey, J; Guilbaud, P; Berthon, L; Charbonnel, M C; Pellet-Rostaing, S; Testard, F

    2016-03-17

    Among the proposed mechanisms to predict and understand synergism in solvent extraction, the possibility of a preorganization of the mixture of extractant molecules has never been considered. Whether involving synergistic aggregation as for solubilization enhancement with reverse micelles or favored molecular interaction between the extractant molecules, evaluation of this hypothesis requires characterization of the aggregates formed by the extractant molecules at different scales. We investigate here the HDEHP/TOPO couple of extractant with methods ranging from vibrational spectroscopy and ESI-MS spectrometry to vapor pressure osmometry and neutron and X-ray scattering to cover both molecular and supramolecular scales. These experimental methods are subjected to DFT calculations and molecular dynamics calculations, allowing a rationalization of the results through the different scales. Performed in the absence of any cation, this original study allows a decorrelation of the mechanisms at the origin of synergy: it appears that no clear preorganization of the extractants can explain the synergy and therefore that the synergistic aggregation observed in the presence of cations is rather due to the chelation mechanisms than to intrinsic properties of the extractant molecules. PMID:26900882

  13. Surface mechanical properties - effects of ion implantation

    NASA Astrophysics Data System (ADS)

    Herman, Herbert

    1981-05-01

    Ion implantation has been used to modify the mechanical properties of a wide range of metals and alloys. The affected properties which have been studied include friction and wear, erosion and fatigue. Both BCC and FCC systems have been examined, with the major effort being directed at the former, due to the strong influence of interstitial implantants on mechanical properties of BCC and because of the industrial utility of these alloys. In seeking the microstructural origins of these sometimes dramatic effects, researchers have employed numerous surface analysis techniques, including backscattering and electron spectroscopy, TEM, SEM, X-ray and Mössbauer analysis and internal friction measurements. The interactions of surface dislocation structures with implantation-induced imperfections, surface alloying, and precipitation phenomena are discussed. A review is given of the current status of activities as represented by a number of research groups.

  14. Mechanical Properties and Failure Mechanisms in Polycrystalline Graphene

    NASA Astrophysics Data System (ADS)

    Gonzalez, Joseph; Perriot, Romain; Oleynik, Ivan

    Large-scale growth of graphene using chemical vapor deposition produces polycrystalline material containing grain boundaries. Recent experiments demonstrate that polycrystalline graphene is nearly as strong as pristine. In this work, the mechanical properties of bi-crystal and polycrystalline graphene samples are investigated by simulating nano-indentation of a circular membrane using classical molecular dynamics and a novel Screened Environment Dependent Reactive Bond Order (SED-REBO) potential. The failure mechanisms and crack propagation in graphene samples containing grain boundaries are also discussed.

  15. Isotropic microscale mechanical properties of coral skeletons

    PubMed Central

    Pasquini, Luca; Molinari, Alan; Fantazzini, Paola; Dauphen, Yannicke; Cuif, Jean-Pierre; Levy, Oren; Dubinsky, Zvy; Caroselli, Erik; Prada, Fiorella; Goffredo, Stefano; Di Giosia, Matteo; Reggi, Michela; Falini, Giuseppe

    2015-01-01

    Scleractinian corals are a major source of biogenic calcium carbonate, yet the relationship between their skeletal microstructure and mechanical properties has been scarcely studied. In this work, the skeletons of two coral species: solitary Balanophyllia europaea and colonial Stylophora pistillata, were investigated by nanoindentation. The hardness HIT and Young's modulus EIT were determined from the analysis of several load–depth data on two perpendicular sections of the skeletons: longitudinal (parallel to the main growth axis) and transverse. Within the experimental and statistical uncertainty, the average values of the mechanical parameters are independent on the section's orientation. The hydration state of the skeletons did not affect the mechanical properties. The measured values, EIT in the 76–77 GPa range, and HIT in the 4.9–5.1 GPa range, are close to the ones expected for polycrystalline pure aragonite. Notably, a small difference in HIT is observed between the species. Different from corals, single-crystal aragonite and the nacreous layer of the seashell Atrina rigida exhibit clearly orientation-dependent mechanical properties. The homogeneous and isotropic mechanical behaviour of the coral skeletons at the microscale is correlated with the microstructure, observed by electron microscopy and atomic force microscopy, and with the X-ray diffraction patterns of the longitudinal and transverse sections. PMID:25977958

  16. Improvement of mechanical properties of glass substrates

    NASA Astrophysics Data System (ADS)

    Karbay, Ismail Hakki Cengizhan; Budakoglu, Refika; Zayim, Esra Ozkan

    2015-12-01

    This paper aims to enhance the mechanical and optical properties of glass substrates with thin films by the sol-gel method. TiO2-SiO2 binary system and Ta2O5 were deposited on glass substrates with high transparency. Ring-on-ring flexure and scratch tests were the main mechanical characterization tests. Herein, we report that the thin films can be used to enhance the mechanical properties of the glass substrates efficiently and effectively. TiO2-SiO2 binary system shows more than two times and Ta2O5 thin films show nearly three times better ultimate strength in the ring-on-ring flexure test. Besides, Ta2O5 thin film samples show superior scratch resistance. Additionally, the finite element method was also used to check the conformity in the application of mechanical properties of composite materials. It is also worth noting that, the finite element method can be used to accurately analyze the mechanical stability of composite materials. The use of the finite element method can reduce the total number of experimental trials without losing reliability.

  17. Mechanical properties of additively manufactured octagonal honeycombs.

    PubMed

    Hedayati, R; Sadighi, M; Mohammadi-Aghdam, M; Zadpoor, A A

    2016-12-01

    Honeycomb structures have found numerous applications as structural and biomedical materials due to their favourable properties such as low weight, high stiffness, and porosity. Application of additive manufacturing and 3D printing techniques allows for manufacturing of honeycombs with arbitrary shape and wall thickness, opening the way for optimizing the mechanical and physical properties for specific applications. In this study, the mechanical properties of honeycomb structures with a new geometry, called octagonal honeycomb, were investigated using analytical, numerical, and experimental approaches. An additive manufacturing technique, namely fused deposition modelling, was used to fabricate the honeycomb from polylactic acid (PLA). The honeycombs structures were then mechanically tested under compression and the mechanical properties of the structures were determined. In addition, the Euler-Bernoulli and Timoshenko beam theories were used for deriving analytical relationships for elastic modulus, yield stress, Poisson's ratio, and buckling stress of this new design of honeycomb structures. Finite element models were also created to analyse the mechanical behaviour of the honeycombs computationally. The analytical solutions obtained using Timoshenko beam theory were close to computational results in terms of elastic modulus, Poisson's ratio and yield stress, especially for relative densities smaller than 25%. The analytical solutions based on the Timoshenko analytical solution and the computational results were in good agreement with experimental observations. Finally, the elastic properties of the proposed honeycomb structure were compared to those of other honeycomb structures such as square, triangular, hexagonal, mixed, diamond, and Kagome. The octagonal honeycomb showed yield stress and elastic modulus values very close to those of regular hexagonal honeycombs and lower than the other considered honeycombs. PMID:27612831

  18. Mechanical Properties of Polymer Nano-composites

    NASA Astrophysics Data System (ADS)

    Srivastava, Iti

    Thermoset polymer composites are increasingly important in high-performance engineering industries due to their light-weight and high specific strength, finding cutting-edge applications such as aircraft fuselage material and automobile parts. Epoxy is the most widely employed thermoset polymer, but is brittle due to extensive cross-linking and notch sensitivity, necessitating mechanical property studies especially fracture toughness and fatigue resistance, to ameliorate the low crack resistance. Towards this end, various nano and micro fillers have been used with epoxy to form composite materials. Particularly for nano-fillers, the 1-100 nm scale dimensions lead to fascinating mechanical properties, oftentimes proving superior to the epoxy matrix. The chemical nature, topology, mechanical properties and geometry of the nano-fillers have a profound influence on nano-composite behavior and hence are studied in the context of enhancing properties and understanding reinforcement mechanisms in polymer matrix nano-composites. Using carbon nanotubes (CNTs) as polymer filler, uniquely results in both increased stiffness as well as toughness, leading to extensive research on their applications. Though CNTs-polymer nano-composites offer better mechanical properties, at high stress amplitude their fatigue resistance is lost. In this work covalent functionalization of CNTs has been found to have a profound impact on mechanical properties of the CNT-epoxy nano-composite. Amine treated CNTs were found to give rise to effective fatigue resistance throughout the whole range of stress intensity factor, in addition to significantly enhancing fracture toughness, ductility, Young's modulus and average hardness of the nano-composite by factors of 57%, 60%, 30% and 45% respectively over the matrix as a result of diminished localized cross-linking. Graphene, a one-atom-thick sheet of atoms is a carbon allotrope, which has garnered significant attention of the scientific community and is

  19. Food mechanical properties and dietary ecology.

    PubMed

    Berthaume, Michael A

    2016-01-01

    Interdisciplinary research has benefitted the fields of anthropology and engineering for decades: a classic example being the application of material science to the field of feeding biomechanics. However, after decades of research, discordances have developed in how mechanical properties are defined, measured, calculated, and used due to disharmonies between and within fields. This is highlighted by "toughness," or energy release rate, the comparison of incomparable tests (i.e., the scissors and wedge tests), and the comparison of incomparable metrics (i.e., the stress and displacement-limited indices). Furthermore, while material scientists report on a myriad of mechanical properties, it is common for feeding biomechanics studies to report on just one (energy release rate) or two (energy release rate and Young's modulus), which may or may not be the most appropriate for understanding feeding mechanics. Here, I review portions of materials science important to feeding biomechanists, discussing some of the basic assumptions, tests, and measurements. Next, I provide an overview of what is mechanically important during feeding, and discuss the application of mechanical property tests to feeding biomechanics. I also explain how 1) toughness measures gathered with the scissors, wedge, razor, and/or punch and die tests on non-linearly elastic brittle materials are not mechanical properties, 2) scissors and wedge tests are not comparable and 3) the stress and displacement-limited indices are not comparable. Finally, I discuss what data gathered thus far can be best used for, and discuss the future of the field, urging researchers to challenge underlying assumptions in currently used methods to gain a better understanding between primate masticatory morphology and diet. PMID:26808100

  20. In vitro antioxidant properties of mangosteen peel extract.

    PubMed

    Suttirak, Weerayuth; Manurakchinakorn, Supranee

    2014-12-01

    The growing interest in the replacement of synthetic food antioxidants by natural ones has fostered research on the screening of plant-derived raw materials for identifying new antioxidants. The special attention of research today is focused on inexpensive or residual sources from agricultural industries. Fruit peels as sources of powerful natural antioxidants are often the waste parts of various fruits from consumption and food industry. Among the fruit peels, mangosteen peel is an important source of natural phenolic antioxidants. The mangosteen peel contains various bioactive substances, i.e., phenolic acids and flavonoids, which possess biological and medicinal properties, especially antioxidant properties. The aim of this review, after presenting analytical techniques for determining in vitro antioxidant activity of mangosteen peel extract, is to summarize available data on the factors affecting antioxidant activity of mangosteen peel extract. In addition, the potential antioxidant activity of mangosteen peel extract, the bioactive compounds identified from mangosteen peel extract and their antioxidant activity are presented. Potential applications of the mangosteen peel extract in food, pharmaceutical and cosmetic products are also discussed. PMID:25477623

  1. Microstructure and Mechanical Properties of Porous Mullite

    NASA Astrophysics Data System (ADS)

    Hsiung, Chwan-Hai Harold

    Mullite (3 Al2O3 : 2 SiO2) is a technologically important ceramic due to its thermal stability, corrosion resistance, and mechanical robustness. One variant, porous acicular mullite (ACM), has a unique needle-like microstructure and is the material platform for The Dow Chemical Company's diesel particulate filter AERIFY(TM). The investigation described herein focuses on the microstructure-mechanical property relationships in acicular mullites as well as those with traditional porous microstructures with the goal of illuminating the critical factors in determining their modulus, strength, and toughness. Mullites with traditional pore morphologies were made to serve as references via slipcasting of a kaolinite-alumina-starch slurry. The starch was burned out to leave behind a pore network, and the calcined body was then reaction-sintered at 1600C to form mullite. The samples had porosities of approximately 60%. Pore size and shape were altered by using different starch templates, and pore size was found to influence the stiffness and toughness. The ACM microstructure was varied along three parameters: total porosity, pore size, and needle size. Total porosity was found to dominate the mechanical behavior of ACM, while increases in needle and pore size increased the toughness at lower porosities. ACM was found to have much improved (˜130%) mechanical properties relative to its non-acicular counterpart at the same porosity. A second set of investigations studied the role of the intergranular glassy phase which wets the needle intersections of ACM. Removal of the glassy phase via an HF etch reduced the mechanical properties by ˜30%, highlighting the intergranular phase's importance to the enhanced mechanical properties of ACM. The composition of the glassy phase was altered by doping the ACM precursor with magnesium and neodymium. Magnesium doping resulted in ACM with greatly reduced fracture strength and toughness. Studies showed that the mechanical properties of the

  2. Investigation of antioxidant properties of Nasturtium officinale (watercress) leaf extracts.

    PubMed

    Ozen, Tevfik

    2009-01-01

    The objective of this study was to examine the in vitro and in vivo antioxidative properties of aqueous and ethanolic extracts of the leaf of Nasturtium officinale R. Br. (watercress). Extracts were evaluated for total antioxidant activity by ferric thiocyanate method, total reducing power by potassium ferricyanide reduction method, 1,1-diphenyl-2-picrylhydrazyl (DPPH*) radical scavenging activities, superoxide anion radical scavenging activities in vitro and lipid peroxidation in vivo. Those various antioxidant activities were compared to standards such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and alpha-tocopherol. The ethanolic extract was found as the most active in total antioxidant activity, reducing power, DPPH* radicals and superoxide anion radicals scavenging activities. Administration of the ethanol extract to rats decreased lipid peroxidation in liver, brain and kidney. These results lead to the conclusion that N. officinale extracts show relevant antioxidant activity by means of reducing cellular lipid peroxidation and increasing antioxidant activity, reducing power, free radiacal and superoxide anion radical scavenging activities. In addition, total phenolic compounds in the aqueous and ethanolic extract of N. officinale were determined as pyrocatechol. PMID:19719054

  3. Extracellular polymeric substances (EPS) from aerobic granular sludges: extraction, fractionation, and anionic properties.

    PubMed

    Caudan, Cédric; Filali, Ahlem; Lefebvre, Dominique; Spérandio, Mathieu; Girbal-Neuhauser, Elisabeth

    2012-04-01

    A multi-method protocol previously proposed for the extraction of extracellular polymeric substances (EPS) from flocculated sludges was investigated on dense aerobic granules. The protocol combines mechanical disruption by sonication and chemical extraction using the Tween detergent and the cation chelator, EDTA. Polysaccharides were mainly recovered during the first sonication step while proteins were recovered all along the extractive procedure with a high prevalence in the EDTA step. These data confirmed the interest of the multi-method protocol for harvesting a diversified pool of EPS from dense granules and for fractionation of the polymers according to their physicochemical properties. In addition, the high extractability of proteins with EDTA confers a specific behavior of the aerobic granules towards the multi-method extraction protocol, supporting the idea that proteins are associated in the granule matrix through ionic interactions involving divalent cations. Analysis of the extracted EPS by anionic exchange chromatography confirmed the presence of highly anionic proteins that were specifically detected in the extracts obtained from granules. One important question is now to investigate whether these highly anionic proteins are involved in the aggregation and densification process and if their presence is related to the cohesive properties of these particles. PMID:22415780

  4. Mechanical Properties of Fe-Ni Meteorites

    NASA Astrophysics Data System (ADS)

    Roberta, Mulford; El Dasher, B.

    2010-10-01

    Iron-nickel meteorites exhibit a unique lamellar microstructure, Widmanstatten patterns, consisting of small regions with steep-iron-nickel composition gradients.1,2 The microstructure arises as a result of extremely slow cooling in a planetary core or other large mass. Mechanical properties of these structures have been investigated using microindentation, x-ray fluorescence, and EBSD. Observation of local mechanical properties in these highly structured materials supplements bulk measurements, which can exhibit large variation in dynamic properties, even within a single sample. 3 Accurate mechanical properties for meteorites may enable better modeling of planetary cores, the likely origin of these objects. Appropriate values for strength are important in impact and crater modeling and in understanding the consequences of observed impacts on planetary crusts. Previous studies of the mechanical properties of a typical iron-nickel meteorite, a Diablo Canyon specimen, indicated that the strength of the composite was higher by almost an order of magnitude than values obtained from laboratory-prepared specimens.4 This was ascribed to the extreme work-hardening evident in the EBSD measurements. This particular specimen exhibited only residual Widmanstatten structures, and may have been heated and deformed during its traverse of the atmosphere. Additional specimens from the Canyon Diablo fall (type IAB, coarse octahedrite) and examples from the Muonionalusta meteorite and Gibeon fall ( both IVA, fine octahedrite), have been examined to establish a range of error on the previously measured yield, to determine the extent to which deformation upon re-entry contributes to yield, and to establish the degree to which the strength varies as a function of microstructure. 1. A. Christiansen, et.al., Physica Scripta, 29 94-96 (1984.) 2. Goldstein and Ogilvie, Geochim Cosmochim Acta, 29 893-925 (1965.) 3. M. D. Furnish, M.B. Boslough, G.T. Gray II, and J.L. Remo, Int. J. Impact Eng

  5. Evaluation of the Hypoglycemic Properties of Anacardium humile Aqueous Extract

    PubMed Central

    Urzêda, Márcio A.; Marcussi, Silvana; Silva Pereira, Luciana L.; França, Suzelei C.; Pereira, Ana Maria S.; Pereira, Paulo S.; da Silva, Saulo L.; Guimarães, César L. S.; Calderon, Leonardo A.; Stábeli, Rodrigo G.; Soares, Andreimar M.; Couto, Lucélio B.

    2013-01-01

    The antihyperglycemic effects of several plant extracts and herbal formulations which are used as antidiabetic formulations have been described and confirmed to date. The main objective of this work was to evaluate the hypoglycemic activity of the aqueous extract of Anacardium humile. Although the treatment of diabetic animals with A. humile did not alter body weight significantly, a reduction of the other evaluated parameters was observed. Animals treated with A. humile did not show variation of insulin levels, possibly triggered by a mechanism of blood glucose reduction. Levels of ALT (alanine aminotransferase) decreased in treated animals, suggesting a protective effect on liver. Levels of cholesterol were also reduced, indicating the efficacy of the extract in reestablishing the balance of nutrients. Moreover, a kidney protection may have been achieved due to the partial reestablishment of blood glucose homeostasis, while no nephrotoxicity could be detected for A. humile. The obtained results demonstrate the effectiveness of A. humile extracts in the treatment of alloxan-induced diabetic rats. Therefore, A. humile aqueous extract, popularly known and used by diabetic patients, induced an improvement in the biochemical parameters evaluated during and following treatment of diabetic rats. Thus, a better characterization of the medicinal potential of this plant will be able to provide a better understanding of its mechanisms of action in these pathological processes. PMID:23737820

  6. Mechanical properties of crosslinked polymer coatings

    NASA Technical Reports Server (NTRS)

    Csernica, Jeffrey

    1994-01-01

    The objectives of this experiment are to: fabricate and test thin films to explore relations between a polymer's structure and its mechanical properties; expose students to testing methods for hardness and impact energy that are simple to perform and which have results that are easy to comprehend; show importance of polymer properties in materials that students frequently encounter; illustrate a system which displays a tradeoff between strength and impact resistance, the combination of which would need to be optimized for a particular application; and to expose students to coatings technology and testing.

  7. [Immunostimulatory properties of mistletoe extracts and their application in oncology].

    PubMed

    Wrotek, Sylwia; Skawiński, Robert; Kozak, Wiesław

    2014-01-01

    For a long time cancer immunotherapy was overshadowed by chemotherapy and radiotherapy. Recently, "Science", one of the world's top scientific journals, named the stimulation of the body's own immune system to fight cancer cells as the "breakthrough of the year". In Germany, Switzerland and Austria, extracts derived from mistletoe (Viscum album L.) such as Iscador, Abnobaviscum, Helixor, Iscar, Iscucin and Isorel have been used in oncology for many years. These extracts have immunomodulating and immunostimulating properties, as demonstrated by experimental studies as well as in clinical trials. The aim of our paper is to present immunological disorders associated with cancer, which can be counteracted by treatment with extracts derived from mistletoe. Although these drugs cannot replace conventional cancer treatment, they may improve the patient's quality and length of life. PMID:25380204

  8. In vitro release properties of encapsulated blueberry (Vaccinium ashei) extracts.

    PubMed

    Flores, Floirendo P; Singh, Rakesh K; Kerr, William L; Phillips, Dennis R; Kong, Fanbin

    2015-02-01

    We aimed to determine the effect of encapsulation on the release properties of blueberry extracts during simulated gastrointestinal digestion. An ethanolic pomace extract was microencapsulated with whey protein isolate via spray drying. The in vitro release of monomeric anthocyanins, phenolics and ferric reducing antioxidant activity of the microcapsules (W) were evaluated for the microcapsules and two non-encapsulated systems: ethanolic pomace extract (P) and freeze-dried juice (F). Concentrations of anthocyanin and phenolics were normalised prior to digestion. Results showed that antioxidant activity was in the order of: F>W>P. Regardless of encapsulation, more phenolics were released from W and P than F. Anthocyanin concentration decreased after intestinal digestion for W, but remained constant for P and F. MALDI-MS showed similar spectra for P and F but not for W. The spray-dried product has comparable release characteristics to freeze-dried juice, and may be investigated for food applications. PMID:25172704

  9. Mechanical properties of intra-ocular lenses

    NASA Astrophysics Data System (ADS)

    Ehrmann, Klaus; Kim, Eon; Parel, Jean-Marie

    2008-02-01

    Cataract surgery usually involves the replacement of the natural crystalline lens with a rigid or foldable intraocular lens to restore clear vision for the patient. While great efforts have been placed on optimising the shape and optical characteristics of IOLs, little is know about the mechanical properties of these devices and how they interact with the capsular bag once implanted. Mechanical properties measurements were performed on 8 of the most commonly implanted IOLs using a custom build micro tensometer. Measurement data will be presented for the stiffness of the haptic elements, the buckling resistance of foldable IOLs, the dynamic behaviour of the different lens materials and the axial compressibility. The biggest difference between the lens types was found between one-piece and 3-piece lenses with respect to the flexibility of the haptic elements

  10. Rhenium Mechanical Properties and Joining Technology

    NASA Technical Reports Server (NTRS)

    Reed, Brian D.; Biaglow, James A.

    1996-01-01

    Iridium-coated rhenium (Ir/Re) provides thermal margin for high performance and long life radiation cooled rockets. Two issues that have arisen in the development of flight Ir/Re engines are the sparsity of rhenium (Re) mechanical property data (particularly at high temperatures) required for engineering design, and the inability to directly electron beam weld Re chambers to C103 nozzle skirts. To address these issues, a Re mechanical property database is being established and techniques for creating Re/C103 transition joints are being investigated. This paper discusses the tensile testing results of powder metallurgy Re samples at temperatures from 1370 to 2090 C. Also discussed is the evaluation of Re/C103 transition pieces joined by both, explosive and diffusion bonding. Finally, the evaluation of full size Re transition pieces, joined by inertia welding, as well as explosive and diffusion bonding, is detailed.

  11. Electron Extraction Mechanisms of a Micro ECR Neutralizer

    NASA Astrophysics Data System (ADS)

    Takao, Yoshinori; Hiramoto, Kenta; Nakagawa, Yuichi; Kasagi, Yusuke; Koizumi, Hiroyuki; Komurasaki, Kimiya

    2015-09-01

    A neutralizer is one of the indispensable components for ion propulsion systems. To design a better performance neutralizer the mechanisms of electron extraction from its plasma source through orifices should be elucidated. In the present study, three-dimensional particle simulations have been carried out for a 4.2-GHz microwave discharge neutralizer, where the size of the discharge chamber is 20 × 20 × 4 mm3 and a xenon electron cyclotron resonance plasma is employed. The numerical model is composed of a particle-in-cell simulation with a Monte Carlo collision algorithm for the kinetics of charged particles, a finite-difference time-domain method for the electromagnetic fields of microwaves, and a finite element analysis for the magnetostatic fields of permanent magnets. The calculations were conducted at the gas pressure of 1 mTorr and the absorbed power of 0.3 W. The simulation results have indicated that the electrostatic field of the plasma has a dominant influence on the electron extraction, where electrons are not extracted unless the effect of the electrostatic field is taken into account in the calculations. This work was supported in part by JSPS KAKENHI Grant No. 25289304. Part of the simulations was performed on the KDK computer system at RISH, Kyoto University.

  12. [Properties of commercial licorice extracts used as a food additive].

    PubMed

    Iida, Kenji; Uematsu, Yoko; Suzuki, Kumi; Yasuno, Tetsuko; Hirata, Keiko; Ito, Kouichi

    2007-08-01

    Properties of eight commercial licorice extracts used as a food additive (sweetener, listed in the List of Existing Food Additives in the Japanese Food Sanitation Law) were surveyed. Residue on ignition ranged from 0.3 to 12.4%, and pH ranged from 4.1 to 6.8, amount of glycyrrhizin, which is the major component in licorice extract, ranged from 10.9 to 77.4%, sodium ranged from 0.1 to 1.2%, potassium ranged from 0.3 to 5.0%, and ammonium nitrogen ranged from 0.03 to 2.5%. These results indicated that various products were distributed on the market. Differences in the manufacturing process may contribute to the variations of product properties. PMID:17892005

  13. Determinants of the mechanical properties of bones

    NASA Technical Reports Server (NTRS)

    Martin, R. B.

    1991-01-01

    The mechanical properties of bones are governed by the same principles as those of man-made load-bearing structures, but the organism is able to adapt its bone structure to changes in skeletal loading. In this overview of the determinants of the strength and stiffness of bone, a continuum approach has been taken, in which the behavior of a macroscopic structure depends on its shape and size, and on the mechanical properties of the material within. The latter are assumed to depend on the composition (porosity and mineralization) and organization (trabecular or cortical bone architecture, collagen fiber orientation, fatigue damage) of the bone. The effects of each of these factors are reviewed. Also, the possible means of non-invasively estimating the strength or other mechanical properties of a bone are reviewed, including quantitative computed tomography, photon absorptiometry, and ultrasonic measurements. The best estimates of strength have been obtained with photon absorptiometry and computed tomography, which at best are capable of accounting for 90% of the strength variability in a simple in vitro test, but results from different laboratories have been highly variable.

  14. Antioxidative and Cardioprotective Properties of Anthocyanins from Defatted Dabai Extracts

    PubMed Central

    Khoo, Hock Eng; Azlan, Azrina; Nurulhuda, M. Halid; Ismail, Amin; Abas, Faridah; Hamid, Muhajir; Roowi, Suri

    2013-01-01

    This study aimed to determine anthocyanins and their antioxidative and cardioprotective properties in defatted dabai parts. Anthocyanins in crude extracts and extract fractions of defatted dabai peel and pericarp were quantified using UHPLC, while their antioxidant capacity and oxidative stress inhibition ability were evaluated by using DPPH and CUPRAC assays as well as linoleic acid oxidation system, hemoglobin oxidation, and PARP-1 inhibition ELISA. Cardioprotective effect of the defatted dabai peel extract was evaluated using hypercholesterolemic-induced New Zealand white rabbits. Six anthocyanins were detected in the defatted dabai peel, with the highest antioxidant capacities and oxidative stress inhibition effect compared to the other part. The defatted dabai peel extract has also inhibited lipid peroxidation (plasma MDA) and elevated cellular antioxidant enzymes (SOD and GPx) in the tested animal model. Major anthocyanin (cyanidin-3-glucoside) and other anthocyanins (pelargonidin-3-glucoside, malvidin-3-glucoside, cyanidin-3-galactoside, cyanidin-3-arabinoside, and peonidin-3-glucoside) detected in the defatted dabai peel are potential future nutraceuticals with promising medicinal properties. PMID:24368926

  15. Tensile mechanical properties of human forearm tendons.

    PubMed

    Weber, J F; Agur, A M R; Fattah, A Y; Gordon, K D; Oliver, M L

    2015-09-01

    Previous studies of the mechanical properties of tendons in the upper limb have used embalmed specimens or sub-optimal methods of measurement. The aim of this study was to determine the biomechanical properties of all tendons from five fresh frozen cadaveric forearms using updated methodology. The cross-sectional area of tendons was accurately measured using a laser reflectance system. Tensile testing was done in a precision servo-hydraulic device with cryo-clamp fixation. We determined that the cross-sectional area of some tendons is variable and directly influences the calculated material properties; visual estimation of this is unreliable. Data trends illustrate that digital extensor tendons possess the greatest tensile strength and a higher Young's modulus than other tendon types. PMID:25940499

  16. Obtaining railpad properties via dynamic mechanical analysis

    NASA Astrophysics Data System (ADS)

    Oregui, M.; de Man, A.; Woldekidan, M. F.; Li, Z.; Dollevoet, R.

    2016-02-01

    In this paper, we propose combining dynamic mechanical analysis (DMA) and the time-temperature superposition principle to determine various railpad dynamic properties. Having accurate information regarding the dynamic properties of a railpad is a fundamental requirement for designing tracks and understanding track deterioration. By testing three different railpad types, we demonstrate that the dynamic behavior of railpads over a wide frequency range can be successfully obtained under different preloads and temperatures if time-temperature superposition can be applied. To investigate railpad aging, worn railpads taken from a mainline in the Netherlands are tested. In this case, worn railpads are softer and possess a lower damping capacity than new railpads. In addition to performing these measurements, a Prony series material model is proposed to reproduce the dynamic behavior of railpads. The Prony series model is in good agreement with the measurements. Measured railpad dynamic properties and the corresponding Prony series numerical model provide valuable information for track design and modeling.

  17. Antioxidant properties of xanthones extracted from the pericarp of Garcinia mangostana (Mangosteen): A theoretical study

    NASA Astrophysics Data System (ADS)

    Thong, Nguyen Minh; Quang, Duong Tuan; Bui, Ngoc Hoa Thi; Dao, Duy Quang; Nam, Pham Cam

    2015-04-01

    A theoretical study on antioxidant properties of fourteen xanthones extracted from the pericarp of G. Mangostana has been performed. Three main reaction mechanisms are investigated: hydrogen atom transfer (HAT), single electron transfer-proton transfer (SETPT) and sequential proton loss electron transfer (SPLET). The Osbnd H bond dissociation enthalpy (BDE), ionization energy (IE), proton affinity (PA) and electron transfer energy (ETE) parameters were computed in gas phase and water. The results show that HAT would be the most favorable mechanism for explaining antioxidant activity of xanthones in gas phase, whereas the SPLET mechanism is thermodynamically favored in water.

  18. Database of Mechanical Properties of Textile Composites

    NASA Technical Reports Server (NTRS)

    Delbrey, Jerry

    1996-01-01

    This report describes the approach followed to develop a database for mechanical properties of textile composites. The data in this database is assembled from NASA Advanced Composites Technology (ACT) programs and from data in the public domain. This database meets the data documentation requirements of MIL-HDBK-17, Section 8.1.2, which describes in detail the type and amount of information needed to completely document composite material properties. The database focuses on mechanical properties of textile composite. Properties are available for a range of parameters such as direction, fiber architecture, materials, environmental condition, and failure mode. The composite materials in the database contain innovative textile architectures such as the braided, woven, and knitted materials evaluated under the NASA ACT programs. In summary, the database contains results for approximately 3500 coupon level tests, for ten different fiber/resin combinations, and seven different textile architectures. It also includes a limited amount of prepreg tape composites data from ACT programs where side-by-side comparisons were made.

  19. Antioxidant Properties of Artemisia annua Extracts in Model Food Emulsions

    PubMed Central

    Skowyra, Monika; Gallego, Maria Gabriela; Segovia, Francisco; Almajano, Maria Pilar

    2014-01-01

    Artemisia annua is currently the only commercial source of the sesquiterpene lactone artemisinin. Although artemisinin is a major bioactive component present in this Chinese herb, leaf flavonoids have shown a variety of biological activities. The polyphenolic profile of extract from leaves of A. annua was assessed as a source of natural antioxidants. Total phenolic content and total flavonoid content were established and three assays were used to measure the antioxidant capacity of the plant extract. The measurement of scavenging capacity against the 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS) radical cation, the oxygen radical absorbance capacity (ORAC) and the ferric reducing antioxidant power (FRAP) were 314.99 µM Trolox equivalents (TE)/g DW, 736.26 µM TE/g DW and 212.18 µM TE/g DW, respectively. A. annua extracts also showed good antioxidant properties in 10% sunflower oil-in-water emulsions during prolonged storage (45 days) at 32 °C. Artemisia extract at 2 g/L was as effective as butylated hydroxyanisole (BHA) at 0.02 g/L in slowing down the formation of hydroperoxides as measured by peroxide value and thiobarbituric acid reactive substances. The results of this study indicate that extract of A. annua may be suitable for use in the food matrix as substitutes for synthetic antioxidants. PMID:26784667

  20. Reversible work extraction in a hybrid opto-mechanical system

    NASA Astrophysics Data System (ADS)

    Elouard, Cyril; Richard, Maxime; Auffèves, Alexia

    2015-05-01

    With the progress of nano-technology, thermodynamics also has to be scaled down, calling for specific protocols to extract and measure work. Usually, such protocols involve the action of an external, classical field (the battery) of infinite energy, that controls the energy levels of a small quantum system (the calorific fluid). Here we suggest a realistic device to reversibly extract work in a battery of finite energy : a hybrid optomechanical system. Such devices consist of an optically active two-level quantum system interacting strongly with a nano-mechanical oscillator that provides and stores mechanical work, playing the role of the battery. We identify protocols where the battery exchanges large, measurable amounts of work with the quantum emitter without getting entangled with it. When the quantum emitter is coupled to a thermal bath, we show that thermodynamic reversibility is attainable with state-of-the-art devices, paving the road towards the realization of a full cycle of information-to-energy conversion at the single bit level.

  1. Mechanisms involved in the chemoprotective effects of rosemary extract studied in human liver and bronchial cells.

    PubMed

    Offord, E A; Macé, K; Avanti, O; Pfeifer, A M

    1997-03-19

    Natural polyphenols found in rosemary have not only potent antioxidant activities but also anticarcinogenic properties. We have studied some of the molecular mechanisms involved in their chemopreventive action using in vitro human liver and bronchial cell models. Rosemary extract, or its active components, carnosol or carnosic acid are potent inhibitors of DNA adduct formation induced by benzo(a)pyrene or aflatoxin B1. At least two mechanisms are involved in the anticarcinogenic action of rosemary extract: (i) inhibition of the metabolic activation of procarcinogens catalysed by the phase I cytochrome P450 enzymes; (ii) induction of the detoxification pathway catalysed by the phase II enzymes such as glutathione S-transferase. PMID:9103309

  2. Different mechanical properties in Seldinger guide wires

    PubMed Central

    Schummer, Wolfram

    2015-01-01

    Background and Aims: Most central venous catheters are placed using Seldinger guide wires. EN ISO 11070 is the guideline for testing guide wire flexing performance and tensile strength, and we can safely assume that guide wires in use meet these requirements. Unfortunately, EN ISO 11070 guidelines do not reflect the clinical requirements and we continue to see mechanical failures and their associated complications. Material and Methods: This in vitro study was performed in an accredited laboratory. With regard to flexing, we: (1) Established the minimum flexing performance needed to meet clinical requirements, (2) developed flexing performance tests which mimic clinical requirement, and (3) evaluated the mechanical properties of various guide wires relative to these requirements. With regard to tensile strength, we used the testing method prescribed in ISO 11070, but did not end the test at 5 Newton (N). We continued until the guide wire was damaged, or we reached maximum tractive force. We then did a wire-to-wire comparison. We examined two basic wire constructions, monofil and core and coil. Results: Tensile strength: All wires tested, except one, met EN ISO 11070 requirements for 5 N tensile strength. The mean of the wire types tested ranged from 15.06 N to 257.76 N. Flexing performance: None of the wires kinked. The monofil had no evidence of bending. Two core/coil wires displayed minor bending (angle 1.5°). All other wires displayed bending angles between 22.5° and 43.0°. Conclusion: We recommend that: (1) Clinicians use guide wires with high-end mechanical properties, (2) EN ISO 11070 incorporate our flexing test into their testing method, raise the flexing requirement to kink-proof, (3) and raise the tensile strength requirement to a minimum of 30 N, and (3) all manufacturers and suppliers be required to display mechanical properties of all guide wire, and guide wire kits sold. PMID:26702209

  3. Machining as a mechanical property test revisited

    NASA Astrophysics Data System (ADS)

    Smith, David L.

    There is much need for data on mechanical behavior of metals at high strains and strain rates. This need is dictated by modeling of processes like forming and machining, wherein the material in the deformation zone is subjected to severe deformation conditions atypical of conventional material property tests such as tension and torsion. Accurate flow stress data is an essential input for robust prediction of process outputs. Similar requirements arise from applications in high speed ballistic penetration and design of materials for armor. Since the deformation zone in cutting of metals is characterized by unique and extreme combinations of strain, strain rate and temperature, an opportunity exists for using plane-strain cutting as a mechanical property test for measuring flow properties of metals. The feasibility of using plane-strain cutting to measure flow properties of metals is revisited in the light of recent data showing controllability of the deformation conditions in chip formation by systematic variation of process input parameters. A method is outlined as to how the deformation conditions can be varied by changing the process parameters. The method is applied to cutting of commercially pure copper (FCC), iron (BCC) and zinc (HCP). Forces and chip geometries are measured, in conjunction with particle image velocimetry characterization of the deformation using high speed image sequences. The flow stresses are estimated from these measurements. The measured flow stress and its dependence on strain are shown to agree well with prior measurements of these parameters using conventional tests, and flow stress inferred from hardness characterization. The method is also demonstrated to be able to measure properties of metals that recrystallize at room temperature (zinc), wherein quasi-static tests predict much lower strength. Sources of variability and uncertainty in the application of this measurement technique are discussed. Future work in the context of further

  4. Different Neurophysiological Mechanisms Underlying Word and Rule Extraction from Speech

    PubMed Central

    De Diego Balaguer, Ruth; Toro, Juan Manuel; Rodriguez-Fornells, Antoni; Bachoud-Lévi, Anne-Catherine

    2007-01-01

    The initial process of identifying words from spoken language and the detection of more subtle regularities underlying their structure are mandatory processes for language acquisition. Little is known about the cognitive mechanisms that allow us to extract these two types of information and their specific time-course of acquisition following initial contact with a new language. We report time-related electrophysiological changes that occurred while participants learned an artificial language. These changes strongly correlated with the discovery of the structural rules embedded in the words. These changes were clearly different from those related to word learning and occurred during the first minutes of exposition. There is a functional distinction in the nature of the electrophysiological signals during acquisition: an increase in negativity (N400) in the central electrodes is related to word-learning and development of a frontal positivity (P2) is related to rule-learning. In addition, the results of an online implicit and a post-learning test indicate that, once the rules of the language have been acquired, new words following the rule are processed as words of the language. By contrast, new words violating the rule induce syntax-related electrophysiological responses when inserted online in the stream (an early frontal negativity followed by a late posterior positivity) and clear lexical effects when presented in isolation (N400 modulation). The present study provides direct evidence suggesting that the mechanisms to extract words and structural dependencies from continuous speech are functionally segregated. When these mechanisms are engaged, the electrophysiological marker associated with rule-learning appears very quickly, during the earliest phases of exposition to a new language. PMID:18000546

  5. Mechanical properties of stapedial annular ligament.

    PubMed

    Gan, Rong Z; Yang, Fan; Zhang, Xiangming; Nakmali, Don

    2011-04-01

    Stapedial annular ligament (SAL) provides a sealed but mobile boundary between the stapes footplate and oval window bony wall. Mechanical properties of the SAL affect the transmission of ossicular movement into the cochlea in sound conduction. However, the mechanical properties of this tissue have never been investigated due to its complexity. In this paper, we report measurement of the viscoelastic properties of SAL on human cadaver temporal bones using a micro-material testing system with digital image correlation analysis. The measured load-deformation relations of SAL samples were converted into shear stress-shear strain relationship, stress relaxation function, and ultimate shear stress and shear strain of the SAL. The hyperelastic Ogden model was used to describe constitutive behavior of the SAL and a 3D finite element model of the experimental setup with SAL was created for assessing the effects of loading variation and measurement errors on results. The study demonstrates that the human SAL is a typical viscoelastic material with hysteresis, nonlinear stress-strain relationship and stress relaxation function. The shear modulus changes from 3.6 to 220 kPa when the shear stress increases from 2 to 140 kPa. These results provide useful information on quasi-static behavior of the SAL. PMID:21112232

  6. Aggregate of nanoparticles: rheological and mechanical properties

    NASA Astrophysics Data System (ADS)

    Wang, Yu; Wu, Xiaojun; Yang, Wei; Zhai, Yuanming; Xie, Banghu; Yang, Mingbo

    2011-12-01

    The understanding of the rheological and mechanical properties of nanoparticle aggregates is important for the application of nanofillers in nanocompoistes. In this work, we report a rheological study on the rheological and mechanical properties of nano-silica agglomerates in the form of gel network mainly constructed by hydrogen bonds. The elastic model for rubber is modified to analyze the elastic behavior of the agglomerates. By this modified elastic model, the size of the network mesh can be estimated by the elastic modulus of the network which can be easily obtained by rheology. The stress to destroy the aggregates, i.e., the yield stress ( σ y ), and the elastic modulus ( G') of the network are found to be depended on the concentration of nano-silica ( ϕ, wt.%) with the power of 4.02 and 3.83, respectively. Via this concentration dependent behavior, we can extrapolate two important mechanical parameters for the agglomerates in a dense packing state ( ϕ = 1): the shear modulus and the yield stress. Under large deformation (continuous shear flow), the network structure of the aggregates will experience destruction and reconstruction, which gives rise to fluctuations in the viscosity and a shear-thinning behavior.

  7. Method for improving the extraction properties of a tributyl phosphate solution

    DOEpatents

    Martin, Earl C.; Bruns, Lester E.

    1976-01-01

    A method for improving the extraction properties of a tributyl phosphate extractant used for reprocessing irradiated nuclear reactor fuel (Purex Process) containing degradation products of tributyl phosphate by contacting the extractant with diazomethane in a suitable solvent whereby the degradation products are esterified to triester phosphates which have extraction properties similar to those of tributyl phosphate.

  8. Quantifying tissue mechanical properties using photoplethysmography

    PubMed Central

    Akl, Tony J.; Wilson, Mark A.; Ericson, M. Nance; Coté, Gerard L.

    2014-01-01

    Photoplethysmography (PPG) is a non-invasive optical method that can be used to detect blood volume changes in the microvascular bed of tissue. The PPG signal comprises two components; a pulsatile waveform (AC) attributed to changes in the interrogated blood volume with each heartbeat, and a slowly varying baseline (DC) combining low frequency fluctuations mainly due to respiration and sympathetic nervous system activity. In this report, we investigate the AC pulsatile waveform of the PPG pulse for ultimate use in extracting information regarding the biomechanical properties of tissue and vasculature. By analyzing the rise time of the pulse in the diastole period, we show that PPG is capable of measuring changes in the Young’s Modulus of tissue mimicking phantoms with a resolution of 4 KPa in the range of 12 to 61 KPa. In addition, the shape of the pulse can potentially be used to diagnose vascular complications by differentiating upstream from downstream complications. A Windkessel model was used to model changes in the biomechanical properties of the circulation and to test the proposed concept. The modeling data confirmed the response seen in vitro and showed the same trends in the PPG rise and fall times with changes in compliance and vascular resistance. PMID:25071970

  9. Quantifying tissue mechanical properties using photoplethysmography

    SciTech Connect

    Akl, Tony; Wilson, Mark A.; Ericson, Milton Nance; Cote, Gerard L.

    2014-01-01

    Photoplethysmography (PPG) is a non-invasive optical method that can be used to detect blood volume changes in the microvascular bed of tissue. The PPG signal comprises two components; a pulsatile waveform (AC) attributed to changes in the interrogated blood volume with each heartbeat, and a slowly varying baseline (DC) combining low frequency fluctuations mainly due to respiration and sympathetic nervous system activity. In this report, we investigate the AC pulsatile waveform of the PPG pulse for ultimate use in extracting information regarding the biomechanical properties of tissue and vasculature. By analyzing the rise time of the pulse in the diastole period, we show that PPG is capable of measuring changes in the Young s Modulus of tissue mimicking phantoms with a resolution of 4 KPa in the range of 12 to 61 KPa. In addition, the shape of the pulse can potentially be used to diagnose vascular complications by differentiating upstream from downstream complications. A Windkessel model was used to model changes in the biomechanical properties of the circulation and to test the proposed concept. The modeling data confirmed the response seen in vitro and showed the same trends in the PPG rise and fall times with changes in compliance and vascular resistance.

  10. Quantifying tissue mechanical properties using photoplethysmography.

    PubMed

    Akl, Tony J; Wilson, Mark A; Ericson, M Nance; Coté, Gerard L

    2014-07-01

    Photoplethysmography (PPG) is a non-invasive optical method that can be used to detect blood volume changes in the microvascular bed of tissue. The PPG signal comprises two components; a pulsatile waveform (AC) attributed to changes in the interrogated blood volume with each heartbeat, and a slowly varying baseline (DC) combining low frequency fluctuations mainly due to respiration and sympathetic nervous system activity. In this report, we investigate the AC pulsatile waveform of the PPG pulse for ultimate use in extracting information regarding the biomechanical properties of tissue and vasculature. By analyzing the rise time of the pulse in the diastole period, we show that PPG is capable of measuring changes in the Young's Modulus of tissue mimicking phantoms with a resolution of 4 KPa in the range of 12 to 61 KPa. In addition, the shape of the pulse can potentially be used to diagnose vascular complications by differentiating upstream from downstream complications. A Windkessel model was used to model changes in the biomechanical properties of the circulation and to test the proposed concept. The modeling data confirmed the response seen in vitro and showed the same trends in the PPG rise and fall times with changes in compliance and vascular resistance. PMID:25071970

  11. Polymer nanocomposites: permeability, chain dynamics, mechanical properties

    NASA Astrophysics Data System (ADS)

    Sahu, Laxmi

    2005-03-01

    Polymer nanocomposites based on dispersion of surfactant treated expandable smectite clays such as montmorillonite layered silicates (MLS) have shown promise as organic-inorganic hybrids with the potential to improve barrier properties. Separately, flexible displays based on plastic substrates have reduced lifetimes tied to the low barrier properties. While there has been a general attribution of improved barrier properties to the tortuous path, this does not consider the influence the introduction of a secondary filler has on the morphology of the host polymer. Here we examine the influence of MLS nanoplatelets on the barrier properties and chain dynamics of polymers. We investigate the potential for host polymer modification by comparing two crystallizable polymers nylon and PET and resulting well dispersed nanocomposites. We study mechanical, cyclic fatigue and permeability of films. Permeability of the biaxially stretched film and when the film undergoes fatigue of 50 and 10000 cycles are also measured. Chain dynamics were modeled based on the Burger model fit to creep-recovery data. A systematic approach to predict the permeability considering amorphous, crystalline and MLS content and comparison with experimental values were done. We also conducted water absorption measurements to highlight the water absorption differences in the two polymers. Dimensional stability of PET was studied by measuring coefficient of thermal expansion of thin film on Si substrate by ellipsometry method.

  12. PICA Variants with Improved Mechanical Properties

    NASA Technical Reports Server (NTRS)

    Thornton, Jeremy; Ghandehari, Ehson M.; Fan, Wenhong; Stackpoole, Margaret; Chavez-Garcia, Jose

    2011-01-01

    Phenolic Impregnated Carbon Ablator (PICA) is a member of the family of Lightweight Ceramic Ablators (LCAs) and was developed at NASA Ames Research Center as a thermal protection system (TPS) material for the Stardust mission probe that entered the Earth s atmosphere faster than any other probe or vehicle to date. PICA, carbon fiberform base and phenolic polymer, shows excellent thermal insulative properties at heating rates from about 250 W/sq cm to 1000 W/sq cm. The density of standard PICA - 0.26 g/cu cm to 0.28 g/cu cm - can be changed by changing the concentration of the phenolic resin. By adding polymers to the phenolic resin before curing it is possible to significantly improve the mechanical properties of PICA without significantly increasing the density.

  13. Electrical and Mechanical Properties of Graphene

    NASA Astrophysics Data System (ADS)

    Bao, Wenzhong

    Graphene is an exciting new atomically-thin two-dimensional (2D) system of carbon atoms organized in a hexagonal lattice structure. This "wonder material" has been extensively studied in the last few years since it's first isolation in 2004. Its rapid rise to popularity in scientific and technological communities can be attributed to a number of its exceptional properties. In this thesis I will present several topics including fabrication of graphene devices, electrical and mechanical properties of graphene. I will start with a brief introduction of electronic transport in nanosclae system including quantum Hall effect, followed by a discussion of fundamental electrical and mechanical properties of graphene. Next I will describe how graphene devices are produced: from the famous "mechnical exfoliation" to our innovative "scratching exfoliation" method, together with the traditional lithography fabrication for graphene devices. We also developed a lithography-free technique for making electrical contacts to suspended graphene devices. Most of the suspended devices presented in this thesis are fabricated by this technique. Graphene has remarkable electrical properties thanks to its crystal and band structures. In Chapter 3, I will first focus on proximity-induced superconductivity in graphene Josephson transistors. In this section we investigate electronic transport in single layer graphene coupled to superconducting electrodes. We observe significant suppression in the critical current I c and large variation in the product IcR n in comparison to theoretic prediction; both phenomena can be satisfactorily accounted for by premature switching in underdamped Josephson junctions. Another focus of our studies is quantum Hall effect and many body physics in graphene in suspended bilayer and trilayer graphene. We demonstrate that symmetry breaking of the first 3 Landau levels and fractional quantum Hall states are observed in both bilayer and trilayer suspended graphene

  14. Volatile profile and sensory property of Gardenia jasminoides aroma extracts.

    PubMed

    Kanlayavattanakul, Mayuree; Lourith, Nattaya

    2015-01-01

    The volatile profiles of aroma extracts prepared from the flower of Gardenia jasminoides by different methods were investigated using gas chromatography-mass spectrometry. The enfleurage extraction using spermaceti wax and palm oil afforded the best aroma extract with a preference that was significantly (p < 0.05) better than those from solvent extractions, as sensorially evaluated in 43 volunteers. The odor quality of the absolute de enfleurage was similar to the floral scent of fresh gardenia, as confirmed in 152 volunteers. Although female volunteers were insignificantly (p > 0.05) better sensed than male volunteers, age was significant (p < 0.05). The nuance gardenia floral scent was contributed by farnesene, Z-3-hexenyl tiglate, Z-3-hexenyl benzoate, and indole. The relaxing and refreshing sensations of the gardenia odor suggest its applications in body care, cleansing products, and perfume. This study addresses the increasing interest in floral fragrances. The aroma profile and sensory property of this sweet and elegant scent flower will strengthen and expand the applications of gardenia from traditional medicine to those of perfumery and the field of phytochemistry. PMID:27125012

  15. Anticonvulsant properties of the methanolic extract of Cyperus articulatus (Cyperaceae).

    PubMed

    Bum, E N; Schmutz, M; Meyer, C; Rakotonirina, A; Bopelet, M; Portet, C; Jeker, A; Rakotonirina, S V; Olpe, H R; Herrling, P

    2001-07-01

    The methanolic extract of rhizomes of Cyperus articulatus, a plant used in traditional medicine in Africa and Latin America for many diseases, possesses anticonvulsant activity in mice. This extract protected mice against maximal electroshock (MES)- and pentylenetetrazol (PTZ)-induced seizures. It also delayed the onset of seizures induced by isonicotinic acid hydrazide and strongly antagonized N-methyl-D-aspartate-induced turning behavior. The ED(50) for protection against seizures was 306 (154-541) mg/kg intraperitoneally (i.p.) for the PTZ test and 1005 (797-1200) mg/kg i.p. for the MES test. The ED(50) of methanolic extract against N-methyl-D-aspartate-induced turning behavior was 875 (623-1123) mg/kg i.p. C. articulatus L. methanolic extract protected 54% of mice from seizures induced by strychnine at the dose of 1000 mg/kg i.p. but had no or a moderate effect only against picrotoxin- or bicuculline-induced seizures. With these effects, the rhizome of C. articulatus L. possesses anticonvulsant properties in animals that might explain its use as a traditional medicine for epilepsy in Africa. PMID:11390127

  16. Mechanical Properties from PBX 9501 Pressing Study

    NASA Astrophysics Data System (ADS)

    Graff Thompson, Darla; Wright, Walter J.

    2004-07-01

    A PBX 9501 pressing study was conducted by researchers in ESA-WMM, LANL, to identify the hydrostatic pressing parameters most important in fabricating high-density parts with uniform density. In this study, 31 charges were pressed using a full permutation of six pressing parameters. Five charges from the set of 31 were selected for an evaluation of their mechanical properties, specifically uniaxial compression and tension. Charges were selected to 1) span the density range of the study, and 2) allow two direct comparisons of pressing parameters independent of bulk density (density has a well-established affect on some material properties). Three PBX 9501 charges pressed isostatically at Pantex Plant in Amarillo, TX were also included in the study. The tensile properties of the 8 charges varied significantly. Careful evaluation of the results suggests that an increase in pressing temperature may correlate with an increase in tensile stress (strength) and a decrease in strain (ductility). Trends in compression exist but are less pronounced. In an effort to explore the relationship between pressing temperature and tensile strength, four sheets of Estane polymer (a component of the PBX 9501 binder) were compression molded at 70, 90, 110 and 130°C. The tensile strength of Estane was observed to increase by a factor of nearly 20 when the molding temperature was increased from 70 to 90°C (strength increase was negligible beyond 90°C). We present an outline of ongoing work that will irrefutably quantify the mechanical property affects of both pressing temperature and dwell time on PBX 9501.(LA-UR 03-4842).

  17. Mechanical properties of low dimensional materials

    NASA Astrophysics Data System (ADS)

    Saini, Deepika

    Recent advances in low dimensional materials (LDMs) have paved the way for unprecedented technological advancements. The drive to reduce the dimensions of electronics has compelled researchers to devise newer techniques to not only synthesize novel materials, but also tailor their properties. Although micro and nanomaterials have shown phenomenal electronic properties, their mechanical robustness and a thorough understanding of their structure-property relationship are critical for their use in practical applications. However, the challenges in probing these mechanical properties dramatically increase as their dimensions shrink, rendering the commonly used techniques inadequate. This dissertation focuses on developing techniques for accurate determination of elastic modulus of LDMs and their mechanical responses under tensile and shear stresses. Fibers with micron-sized diameters continuously undergo tensile and shear deformations through many phases of their processing and applications. Significant attention has been given to their tensile response and their structure-tensile properties relations are well understood, but the same cannot be said about their shear responses or the structure-shear properties. This is partly due to the lack of appropriate instruments that are capable of performing direct shear measurements. In an attempt to fill this void, this dissertation describes the design of an inexpensive tabletop instrument, referred to as the twister, which can measure the shear modulus (G) and other longitudinal shear properties of micron-sized individual fibers. An automated system applies a pre-determined twist to the fiber sample and measures the resulting torque using a sensitive optical detector. The accuracy of the instrument was verified by measuring G for high purity copper and tungsten fibers. Two industrially important fibers, IM7 carbon fiber and KevlarRTM 119, were found to have G = 17 and 2.4 GPa, respectively. In addition to measuring the shear

  18. Mechanical properties of phosphorene nanoribbons and oxides

    SciTech Connect

    Hao, Feng; Chen, Xi

    2015-12-21

    Mechanical properties of phosphorene nanoribbons and oxides are investigated by using density functional theory. It is found that the ideal strength of nanoribbon decreases in comparison with that of 2D phosphorene. The Young's modulus of armchair nanoribbon has a remarkable size effect because of the edge relaxations. The analysis of the stress-strain relation indicates that, owing to chemisorbed oxygen atoms, the ideal strength and Young's modulus of 2D phosphorene oxide are greatly reduced along the zigzag direction, especially upon high oxidation ratios. In addition, strain and oxidation have significant impacts on phonon dispersion.

  19. Linking properties to microstructure through multiresolution mechanics

    NASA Astrophysics Data System (ADS)

    McVeigh, Cahal James

    The macroscale mechanical and physical properties of materials are inherently linked to the underlying microstructure. Traditional continuum mechanics theories have focused on approximating the heterogeneous microstructure as a continuum, which is conducive to a partial differential equation mathematical description. Although this makes large scale simulation of material much more efficient than modeling the detailed microstructure, the relationship between microstructure and macroscale properties becomes unclear. In order to perform computational materials design, material models must clearly relate the key underlying microstructural parameters (cause) to macroscale properties (effect). In this thesis, microstructure evolution and instability events are related to macroscale mechanical properties through a new multiresolution continuum analysis approach. The multiresolution nature of this theory allows prediction of the evolving magnitude and scale of deformation as a direct function of the changing microstructure. This is achieved via a two-pronged approach: (a) Constitutive models which track evolving microstructure are developed and calibrated to direct numerical simulations (DNS) of the microstructure. (b) The conventional homogenized continuum equations of motion are extended via a virtual power approach to include extra coupled microscale stresses and stress couples which are active at each characteristic length scale within the microstructure. The multiresolution approach is applied to model the fracture toughness of a cemented carbide, failure of a steel alloy under quasi-static loading conditions and the initiation and velocity of adiabatic shear bands under high speed dynamic loading. In each case the multiresolution analysis predicts the important scale effects which control the macroscale material response. The strain fields predicted in the multiresolution continuum analyses compare well to those observed in direct numerical simulations of the

  20. HTML Extraction Algorithm Based on Property and Data Cell

    NASA Astrophysics Data System (ADS)

    Purnamasari, Detty; Wayan Simri Wicaksana, I.; Harmanto, Suryadi; Yuniar Banowosari, Lintang

    2013-06-01

    The data available on the Internet is in various models and formats. One form of data representation is a table. Tables extraction is used in process more than one table on the Internet from different sources. Currently the effort is done by using copy-paste that is not automatic process. This article presents an approach to prepare the area, so tables in HTML format can be extracted and converted into a database that make easier to combine the data from many resources. This article was tested on the algorithm 1 used to determine the actual number of columns and rows of the table, as well as algorithm 2 are used to determine the boundary line of the property. Tests conducted at 100 tabular HTML format, and the test results provide the accuracy of the algorithm 1 is 99.9% and the accuracy of the algorithm 2 is 84%.

  1. Paullinia pinnata extracts rich in polyphenols promote vascular relaxation via endothelium-dependent mechanisms.

    PubMed

    Zamble, Alexis; Carpentier, Marie; Kandoussi, Abdelmejid; Sahpaz, Sevser; Petrault, Olivier; Ouk, Tawarak; Hennuyer, Nathalie; Fruchart, Jean-Charles; Staels, Bart; Bordet, Régis; Duriez, Patrick; Bailleul, François; Martin-Nizard, Françoise

    2006-04-01

    Paullinia pinnata L. (Sapindaceae) is an African tropical plant whose roots and leaves are used in traditional medicine for many purposes, especially for erectile dysfunction, but its action mechanism is unknown. P. pinnata root and leaf methanolic extracts are rich in phenolic compounds. This study shows that both extracts are highly antioxidative and induce a slight transcriptional activity of peroxisome proliferator activated receptor-alpha. They also increased and decreased endothelial nitric oxide synthase and endothelin-1 mRNA levels in bovine aortic endothelial cells, respectively. In this study P. pinnata methanolic extracts in cumulative doses elicited in a dose-dependent manner the relaxation of phenylephrine precontracted isolated rat aortic rings. N-nitro-L-arginine methyl ester significantly attenuated the capacity of both extracts to induce arterial relaxation, indicating that this arterial relaxation was mediated by endothelial nitric oxide release. It could be suggested that the arterial relaxation induced by both extracts could be mainly linked to their capacities to inhibit nitric oxide oxidation through their antioxidant properties. PMID:16680075

  2. Mechanical Properties of Nanoceramic Silicon Carbide

    NASA Astrophysics Data System (ADS)

    Ojo, Ipidapo; Abunaemeh, Malek; Smith, Cydale; Muntele, Claudiu; Ila, Daryush

    2009-03-01

    Generation IV nuclear reactors will use the TRISO fuels, a type of micro fuel particle. It consists of a fuel kernel coated with four layers of isotropic material. One of the materials considered for these layers is silicon carbide ceramic. This lightweight material can maintain chemical and dimensional stability in adverse environments at very high temperatures up to 3000 C, and it is chemically inert. It is widely used as a semiconductor material in electronics because of its high thermo conductivity, high electric field break down strength, and high maximum current density, which makes it more desirable than silicon. Silicon carbide has a very low coefficient of thermal expansion and has no phase transition that would discontinue its thermal expansion. At the Center for Irradiation of Materials (C.I.M.) we are developing a new fabrication process for nanopowdered silicon carbide for TRISO fuel coating purposes. We also study the mechanical properties of the material produced. Among the different test being performed are particle induced X-ray emission (PIXE) an Rutherford backscattering spectroscopy (RBS). The mechanical properties of interest are hardness (measured by Vickers Hardness machine), toughness (measured by the Anstis equation, KIC= 1.6 x 10-2(E/H)^1/2(P/C0^3/2, where P=load, C0=crack length, E=Young's modulus and H=Vickers Hardness), tensile strength and flexural strength (measured by a three point bend test). Results will be presented during the meeting.

  3. Inhibitory mechanisms of two Uncaria tomentosa extracts affecting the Wnt-signaling pathway.

    PubMed

    Gurrola-Díaz, Carmen Magdalena; García-López, Pedro Macedonio; Gulewicz, Krzysztof; Pilarski, Radoslaw; Dihlmann, Susanne

    2011-06-15

    Uncaria tomentosa ("uña de gato"; "cat's claw"), a woody vine native to the Amazon rainforest, is commonly used in South American traditional medicine to treat a broad spectrum of diseases. Although recent studies have reported anti-inflammatory and anti-proliferative properties of different alkaloids extracted from this plant, the underlying molecular mechanisms of these effects have not been elucidated yet. Our study investigates the inhibitory mechanisms of Uncaria tomentosa extracts on the Wnt-signaling pathway, a central regulator of development and tissue homoeostasis. A modified cell-based luciferase assay for screening inhibitors of the Wnt-pathway was used for analysis. Three cancer cell lines displaying different levels of aberrant Wnt-signaling activity were transfected with Wnt-signaling responsive Tcf-reporter plasmids and treated with increasing concentrations of two Uncaria tomentosa bark extracts. Wnt-signaling activity was assessed by luciferase activity and by expression of Wnt-responsive target genes. We show that both, an aqueous and an alkaloid-enriched extract specifically inhibit Wnt-signaling activity in HeLa, HCT116 and SW480 cancer cells resulting in reduced expression of the Wnt-target gene: c-Myc. The alkaloid-enriched extract (B/S(rt)) was found to be more effective than the aqueous extract (B/W(37)). The strongest effect was observed in SW480 cells, displaying the highest endogenous Wnt-signaling activity. Downregulation of Wnt-signaling by a dominant negative-TCF-4 variant in non-cancer cells rendered the cells insensitive towards treatment with B/S(rt). B/Srt was less toxic in non-cancer cells than in cancer cells. Our data suggest that the broad spectrum of pharmacological action of Uncaria tomentosa involves inhibition of the Wnt-signaling pathway, downstream of beta-Catenin activity. PMID:21156346

  4. Mechanical properties of 3D ceramic nanolattices

    NASA Astrophysics Data System (ADS)

    Meza, Lucas

    Developments in advanced nanoscale fabrication techniques have allowed for the creation of 3-dimensional hierarchical structural meta-materials that can be designed with arbitrary geometry. These structures can be made on length scales spanning multiple orders of magnitude, from tens of nanometers to hundreds of microns. The smallest features are controllable on length scales where materials have been shown to exhibit size effects in their mechanical properties. Combining novel nanoscale mechanical properties with a 3-dimensional architecture enables the creation of new classes of materials with tunable and unprecedented mechanical properties. We present the fabrication and mechanical deformation of hollow tube alumina nanolattices that were fabricated using two-photon lithography direct laser writing (DLW), atomic layer deposition (ALD), and oxygen plasma etching. Nanolattices were designed in a number of different geometries including octet-truss, octahedron, and 3D Kagome. Additionally, a number of structural parameters were varied including tube wall thickness (t) , tube major axis (a) , and unit cell size (L) . The resulting nanolattices had a range of densities from ρ = 4 to 250 mg/cm3. Uniaxial compression and cyclic loading tests were performed on the nanolattices to obtain the yield strength and modulus. In these tests, a marked change in the deformation response was observed when the wall thickness was reduced below 20nm; thick-walled nanolattices (t>20nm) underwent catastrophic, brittle failure, which transitioned to a gradual, ductile-like deformation as wall thickness was reduced. Thick-walled nanolattices also exhibited no recovery after compression, while thin-walled structures demonstrated notable recovery, with some recovering by 98% after compression to 50% strain and by 80% when compressed to 90% strain. Across all geometries, unit cell sizes, and wall thicknesses, we found a consistent power law relation between strength and modulus with

  5. Potential Properties of Plant Sprout Extracts on Amyloid β

    PubMed Central

    Okada, Mizue; Okada, Yoshinori

    2016-01-01

    The aim of this study is to examine the amyloid β (Aβ) inhibition mechanism of plant sprouts' aqueous extracts (PSAE). In this study, we screened the effects of five plant sprouts' extracts on Aβ (1–42) structure modification using gel electrophoresis. In PSAE, no band of Aβ monomer was recognized in Japanese butterbur. Similarly, the Aβ monomer band became light in buckwheat, red cabbage, broccoli, and brussels. The neuroprotective effects of PSAE were evaluated by measuring levels of Aβ in mixtures (Aβ  and PSAE) with Aβ ELISA assay. The treatment with PSAE decreased Aβ levels. The results indicated that the levels of red cabbage, Japanese butterbur, and broccoli were 9.6, 28.0, and 44.0%, respectively. The lowest value was observed with buckwheat. Furthermore, we carried out a Congo Red (CR) and Aβ binding experiment of PSAE to confirm the modification mechanism of PSAE. The correlation coefficient for the absorption spectrum peak of CR was found to be bigger than 0.8 (r = 0.882) which proved that the Aβ levels could be attributed to the peak of CR. In conclusion, we demonstrated that treatment with PSAE effectively decreases Aβ concentration. Thus, the mechanism that decreased the Aβ levels may be modification by PSAE. PMID:27429807

  6. Potential Properties of Plant Sprout Extracts on Amyloid β.

    PubMed

    Okada, Mizue; Okada, Yoshinori

    2016-01-01

    The aim of this study is to examine the amyloid β (Aβ) inhibition mechanism of plant sprouts' aqueous extracts (PSAE). In this study, we screened the effects of five plant sprouts' extracts on Aβ (1-42) structure modification using gel electrophoresis. In PSAE, no band of Aβ monomer was recognized in Japanese butterbur. Similarly, the Aβ monomer band became light in buckwheat, red cabbage, broccoli, and brussels. The neuroprotective effects of PSAE were evaluated by measuring levels of Aβ in mixtures (Aβ  and PSAE) with Aβ ELISA assay. The treatment with PSAE decreased Aβ levels. The results indicated that the levels of red cabbage, Japanese butterbur, and broccoli were 9.6, 28.0, and 44.0%, respectively. The lowest value was observed with buckwheat. Furthermore, we carried out a Congo Red (CR) and Aβ binding experiment of PSAE to confirm the modification mechanism of PSAE. The correlation coefficient for the absorption spectrum peak of CR was found to be bigger than 0.8 (r = 0.882) which proved that the Aβ levels could be attributed to the peak of CR. In conclusion, we demonstrated that treatment with PSAE effectively decreases Aβ concentration. Thus, the mechanism that decreased the Aβ levels may be modification by PSAE. PMID:27429807

  7. Mechanical properties of monolayer graphene oxide.

    PubMed

    Suk, Ji Won; Piner, Richard D; An, Jinho; Ruoff, Rodney S

    2010-11-23

    Mechanical properties of ultrathin membranes consisting of one layer, two overlapped layers, and three overlapped layers of graphene oxide platelets were investigated by atomic force microscopy (AFM) imaging in contact mode. In order to evaluate both the elastic modulus and prestress of thin membranes, the AFM measurement was combined with the finite element method (FEM) in a new approach for evaluating the mechanics of ultrathin membranes. Monolayer graphene oxide was found to have a lower effective Young's modulus (207.6 ± 23.4 GPa when a thickness of 0.7 nm is used) as compared to the value reported for "pristine" graphene. The prestress (39.7-76.8 MPa) of the graphene oxide membranes obtained by solution-based deposition was found to be 1 order of magnitude lower than that obtained by others for mechanically cleaved graphene. The novel AFM imaging and FEM-based mapping methods presented here are of general utility for obtaining the elastic modulus and prestress of thin membranes. PMID:20942443

  8. Extraction of petroleum hydrocarbons from soil by mechanical shaking

    SciTech Connect

    Schwab, A.P.; Su, J.; Wetzel, S.; Pekarek, S.; Banks, M.K.

    1999-06-01

    A shaking extraction method for petroleum hydrocarbons in soil was developed and compared to Soxhlet extraction. Soxhlet extraction is an EPA-approved method for volatile and semivolatile organic contaminants from solid materials, but it has many disadvantages including long extraction periods and potential loss of volatile compounds. When field-moist soils are used, variability in subsamples is higher, and the extraction of hydrocarbons with a nonpolar solvent may be less efficient. A shaking method was designed to fill the need for simpler and more efficient extraction of petroleum hydrocarbons from soil. A systematic study of extraction conditions was performed for various soil types, soil weights, solvents, extraction times, and extraction cycles. The results were compared to those for Soxhlet extraction. Shaking 1 g of soil with a sequence of three 10-mL aliquots of dichloromethane or acetone was found to be equivalent to Soxhlet extraction for total petroleum hydrocarbons and polycyclic aromatic hydrocarbons. Shaking with acetone was more consistent than all other methods for the extraction of specific compounds from aged, contaminated soil. The shaking method appears to be applicable to a wide range of soil types and petroleum contaminants but should be compared to Soxhlet extraction for new conditions.

  9. Photosensitizing properties of water-extractable organic matter from soils.

    PubMed

    Nkhili, Ezzhora; Boguta, Patrycja; Bejger, Romualda; Guyot, Ghislain; Sokołowska, Zofia; Richard, Claire

    2014-01-01

    Water-extractable organic matter (WEOM) was extracted using pure water from two black soils and from the Elliott reference soil of the International Humic Substances Society (IHSS). WEOMs were characterized by chemical and spectroscopic methods. The apparent quantum yields of singlet oxygen, triplet excited states and hydroxyl radicals formation upon irradiation within the wavelength range 290-450 nm were determined using chemical probes and compared to those of standard Elliott humic substances. In general, the aromatic content, as measured by the SUVA value, was close in WEOMs and humic substances, while the E2/E3 was higher and the humification index lower in the former. Quantum yield values measured for WEOMs fell within the range of those found for basic medium extracted humic substances or were even higher in one case. Thus, water soluble aromatic moiety of the soil organic matter, especially those with low humification degree, is important for the photosensitizing properties. We also found that WEOMs sensitized the bisphenol A phototransformation with rates of the same order of magnitude for all the samples. PMID:24083904

  10. Morphology, orientation, and mechanical properties of gelatin films

    SciTech Connect

    Blanton, T.N.; Tsou, A.H.

    1996-12-31

    Gelatin is a polypeptide derived from degradation and disorganization of collagen fibers and is the primary binder in photographic emulsions. Gelatin provides the mechanical integrity and strength to the photographic emulsion allowing for packaging, handling, and photofinishing operations. Gelatin films generated from aqueous-solution casting can exist in a semicrystalline or an amorphous state. When a gelatin solution is cooled below its helix-coil transition temperature, partial renaturation of gelatin to form triple helices can occur. The degree of renaturation in a coated film is dependent upon the drying temperature and the drying rate. During the drying process, gelatin crystals can be formed by lateral association of the triple helices through a mechanism of nucleation and growth of a fringed micelle structure. X-ray scattering techniques have been utilized to examine the morphology and orientation of gelatin films. Based on X-ray diffraction data, it is observed that aggregates of triple-helix rods lie parallel to the film plane but are symmetrically distributed within the film plane. Since a material`s physical and mechanical properties are related to its structure, it is necessary to understand and to characterize the morphological development in gelatin film formation. In this study, an X-ray diffractometer and pole figure goniometer were utilized to examine the structural development and orientation anisotropy in solid-state gelatin films. Also, in this study, the in-plane mechanical properties of a gelatin film were determined from a uniaxial tensile test, and the gelatin film properties in the thickness direction were extracted from an indentation test based on the finite element analysis of the indentation results using a viscoelastic material model.

  11. Possible antiosteoporotic mechanism of Cicer arietinum extract in ovariectomized rats

    PubMed Central

    Fahmy, Sohair R; Soliman, Amel M; Sayed, Amany A; Marzouk, Mohamed

    2015-01-01

    Objective: The present study aimed to throw the light on the anti-osteoprotic mechanism of Cicer arietinum extract (CAE) seeds against ovariectomized (OVX) rats. Methods: Seventy female rats were divided into two groups. The first group (14 rats/group) represented normal rats (Sham operated) while the second group (56 rats/group) underwent bilateral ovariectomy (OVX). After one week of recovery from ovariectomy surgery, the second group was randomly subdivided into 4 subgroups (14 rats/ each subgroup). The rats administered orally; distilled water (vehicle) (1st subgroup), Cicer arietinum extract (CAE) (500 or 1000 mg/kg body weight/day) (2nd and 3rd subgroups), alendronate (6.5 mg/kg mg/kg body weight) as a positive control one time/week (4rh subgroup), daily for 10 weeks. Results: The present study demonstrated that ovariectomy caused significant decrease in bone mineral; density (BMD) and content (BMC), Bone-specific alkaline phosphatase (BALP), calcium (Ca), phosphorus (P), parathyroid hormone (PTH) and calcitonin levels. Furthermore, ovariectomy induced significant elevation of tartrate-resistant acid phosphatase 5b (TRAP 5b) and receptor activator of nuclear factor (NF-kappa β) ligand (RANKL) concentration. Conversely, osteoprotegerin (OPG) and OPG/RANKL ratio were decreased following ovariectomy. The present work suggests that CAE has antiosteoporotic action against ovariectomy effects and its activity may results from its phytochemical and/or phytoestrogen contents. Conclusion: The ongoing study speculates that the CAE exerts its action through regulation of RANK/RANKL/OPG system. As, CAE not only promotes osteoblast differentiation, but also up-regulates OPG and downregulates RANKL secretion in osteoblasts, subsequently prevents bone loss and osteoporosis. PMID:26097532

  12. Environmental properties set cell mechanics and morphology

    NASA Astrophysics Data System (ADS)

    Janmey, Paul

    2012-02-01

    Many cell types are sensitive to mechanical signals that are produced either by application of exogenous force to their surfaces, or by the resistance that their surroundings place on forces generated by the cells themselves. Cell morphology, motility, proliferation, and protein expression all change in response to substrate stiffness. Changing the elastic moduli of substrates alters the formation of focal adhesions, the assembly of actin filaments into bundles, and the stability of intermediate filaments. The range of stiffness over which different primary cell types respond can vary over a wide range and generally reflects the elastic modulus of the tissue from which these cells were isolated. Mechanosensing depends on the type of adhesion receptor by which the cell binds, and therefore on both the molecular composition of the extracellular matrix and the nature of its link to the cytoskeleton. Many cell types can alter their own stiffness to match that of the substrate to which they adhere. The maximal elastic modulus that cells such as fibroblasts can attain is similar to that of crosslinked actin networks at the concentrations in the cell cortex. The precise mechanisms of mechanosensing are not well defined, but they presumably require an elastic connection between cell and substrate, mediated by transmembrane proteins. The viscoelastic properties of different extracellular matrices and cytoskeletal elements strongly influence the response of cells to mechanical signals, and the unusual non-linear elasticity of many biopolymer gels, characterized by strain-stiffening, leads to novel mechanisms by which cells alter their stiffness by engagement of molecular motors that produce internal stresses. Cell cortical elasticity is dominated by cytoskeletal polymer networks and can be modulated by internal tension. Simultaneous control of substrate stiffness and adhesive patterns suggests that stiffness sensing occurs on a length scale much larger than single molecular

  13. Studies on the mechanism of efficient extraction of tea components by aqueous ethanol.

    PubMed

    Hu, Ci-Jie; Gao, Ying; Liu, Yang; Zheng, Xin-Qiang; Ye, Jian-Hui; Liang, Yue-Rong; Lu, Jian-Liang

    2016-03-01

    Effect of solvent on the extraction yield and its relevant mechanism have been studied in this paper. Compared with extraction by water, catechins and caffeine could be easily extracted from green tea by aqueous ethanol, but hardly at all by absolute ethanol. Results of the vacuum-assisted extraction, solubility determination of EGCG and caffeine, as well as swelling ratio analysis of the infused leaves, indicated that an excellent leaf-matrix-swelling effect and high solubility of tea components might be the key mechanisms for high extraction efficiency by the aqueous ethanol. These mechanisms were further confirmed by the pre-swelling extraction. This is a first report on the mechanism of efficient extraction by aqueous organic solvent. Application of pre-swelling extraction is also discussed. PMID:26471560

  14. Enhanced mechanical energy extraction from transverse galloping using a dual mass system

    NASA Astrophysics Data System (ADS)

    Vicente-Ludlam, D.; Barrero-Gil, A.; Velazquez, A.

    2015-03-01

    This paper offers a theoretical study of energy extraction through transverse galloping using a dual-mass system. To this end, a two-degree-of-freedom model is developed where fluid forces on the galloping body are described resorting to quasi-steady hypothesis; the model is solved approximately by using the Harmonic Balance Method. Three possible configurations of the dual-mass system have been analyzed. Two of them show an improvement in the efficiency of energy extraction with respect to that of the single mass configuration when the mechanical properties of the dual-mass system are appropriately chosen. In addition, the dual-mass system promotes a broadening of the values of the incident flow velocities at which the efficiency is kept high.

  15. Evaluation of mechanical properties of esthetic brackets

    PubMed Central

    Umezaki, Eisaku; Komazawa, Daigo; Otsuka, Yuichiro; Suda, Naoto

    2015-01-01

    Plastic brackets, as well as ceramic brackets, are used in various cases since they have excellent esthetics. However, their mechanical properties remain uncertain. The purpose of this study was to determine how deformation and stress distribution in esthetic brackets differ among materials under the same wire load. Using the digital image correlation method, we discovered the following: (1) the strain of the wings of plastic brackets is within 0.2% and that of ceramic and metal brackets is negligible, (2) polycarbonate brackets having a stainless steel slot show significantly smaller displacement than other plastic brackets, and (3) there is a significant difference between plastic brackets and ceramic and stainless steel brackets in terms of the displacement of the bracket wing. PMID:25755677

  16. Mechanical properties of icosahedral virus capsids

    NASA Astrophysics Data System (ADS)

    Vliegenthart, G. A.; Gompper, G.

    2007-12-01

    Virus capsids are self-assembled protein shells in the size range of 10 to 100 nanometers. The shells of DNA-viruses have to sustain large internal pressures while encapsulating and protecting the viral DNA. We employ computer simulations to study the mechanical properties of crystalline shells with icosahedral symmetry that serve as a model for virus capsids. The shells are positioned on a substrate and deformed by a uni-axial force excerted by a small bead. We predict the elastic response for small deformations, and the buckling transitions at large deformations. Both are found to depend strongly on the number N of elementary building blocks (capsomers), and the Föppl-von Kármán number γ which characterizes the relative importance of shear and bending elasticity.

  17. Tension-induced mechanical properties of stanene

    NASA Astrophysics Data System (ADS)

    Tao, Lele; Yang, Chuanghua; Wu, Liyuan; Han, Lihong; Song, Yuxin; Wang, Shumin; Lu, Pengfei

    2016-05-01

    In this paper, elastic properties of stanene under equiaxial or uniaxial tensions along armchair and zigzag directions are investigated by first-principles calculations. The stress-strain relation is calculated and the relaxation of the internal atom positions is analyzed. The high-order elastic constants are calculated by fitting the polynomial expressions. The Young’s modulus and Poisson ratio of the stanene is calculated to be 24.14 N/m and 0.39 N/m, respectively. The stanene exhibits lower Young’s modulus than those of the proceeding group IV elements, which is attributed to the smaller sp2-sp3 bond energy in stanene than those of silicene and germanene. Calculated values of ultimate stresses and strains, second-order elastic constants (SOCEs) and the in-plane Young’s modulus are all positive. It proves that stanene is mechanically stable.

  18. Mechanical Properties of Silicon Carbonitride Thin Films

    NASA Astrophysics Data System (ADS)

    Peng, Xiaofeng; Hu, Xingfang; Wang, Wei; Song, Lixin

    2003-02-01

    Silicon carbonitride thin films were synthesized by reactive rf sputtering a silicon carbide target in nitrogen and argon atmosphere, or sputtering a silicon nitride target in methane and argon atmosphere, respectively. The Nanoindentation technique (Nanoindenter XP system with a continuous stiffness measurement technique) was employed to measure the hardness and elastic modulus of thin films. The effects of sputtering power on the mechanical properties are different for the two SiCN thin films. With increasing sputtering power, the hardness and the elastic modulus decrease for the former but increase for the latter. The tendency is similar to the evolution trend of Si-C bonds in SiCN materials. This reflects that Si-C bonds provide greater hardness for SiCN thin films than Si-N and C-N bonds.

  19. In vivo penetration mechanics and mechanical properties of mouse brain tissue at micrometer scales.

    PubMed

    Sharp, Andrew A; Ortega, Alicia M; Restrepo, Diego; Curran-Everett, Douglas; Gall, Ken

    2009-01-01

    Substantial advancement in the understanding of the neuronal basis of behavior and the treatment of neurological disorders has been achieved via the implantation of various devices into the brain. To design and optimize the next generation of neuronal implants while striving to minimize tissue damage, it is necessary to understand the mechanics of probe insertion at relevant length scales. Unfortunately, a broad-based understanding of brain-implant interactions at the necessary micrometer scales is largely missing. This paper presents a generalizable description of the micrometer-scale penetration mechanics and material properties of mouse brain tissue in vivo. Cylindrical stainless steel probes were inserted into the cerebral cortex and olfactory bulb of mice. The effects of probe size, probe geometry, insertion rate, insertion location, animal age, and the presence of the dura and pia on the resulting forces were measured continuously throughout probe insertion and removal. Material properties (modulus, cutting force, and frictional force) were extracted using mechanical analysis. The use of rigid, incompressible, cylindrical probes allows for a general understanding of how probe design and insertion methods influence the penetration mechanics of brain tissue in vivo that can be applied to the quantitative design of most future implantable devices. PMID:19224718

  20. Rationally designing the mechanical properties of protein hydrogels

    NASA Astrophysics Data System (ADS)

    Cao, Yi

    Naturally occurring biomaterials possess diverse mechanical properties, which are critical to their unique biological functions. However, it remains challenging to rationally control the mechanical properties of synthetic biomaterials. Here we provide a bottom-up approach to rationally design the mechanical properties of protein-based hydrogels. We first use atomic fore microscope (AFM) based single-molecule force spectroscopy to characterize the mechanical stability of individual protein building blocks. We then rationally design the mechanical properties of hydrogels by selecting different combination of protein building blocks of known mechanical properties. As a proof-of-principle, we demonstrate the engineering of hydrogels of distinct extensibility and toughness. This simple combinatorial approach allows direct translation of the mechanical properties of proteins from the single molecule level to the macroscopic level and represents an important step towards rationally designing the mechanical properties of biomaterials.

  1. Mechanical and biological properties of keratose biomaterials.

    PubMed

    de Guzman, Roche C; Merrill, Michelle R; Richter, Jillian R; Hamzi, Rawad I; Greengauz-Roberts, Olga K; Van Dyke, Mark E

    2011-11-01

    The oxidized form of extractable human hair keratin proteins, commonly referred to as keratose, is gaining interest as a biomaterial for multiple tissue engineering studies including those directed toward peripheral nerve, spinal cord, skin, and bone regeneration. Unlike its disulfide cross-linked counterpart, kerateine, keratose does not possess a covalently cross-linked network structure and consequently displays substantially different characteristics. In order to understand its mode(s) of action and potential for clinical translatability, detailed characterization of the composition, physical properties, and biological responses of keratose biomaterials are needed. Keratose was obtained from end-cut human hair fibers by peracetic acid treatment, followed by base extraction, and subsequent dialysis. Analysis of lyophilized keratose powder determined that it contains 99% proteins by mass with amino acid content similar to human hair cortex. Metallic elements were also found in minute quantities. Protein oxidation led to disulfide bond cleavage and drastic reduction of free thiols due to conversion of sulfhydryl to sulfonic acid, chain fragmentation, and amino acid modifications. Mass spectrometry identified the major protein constituents as a heterogeneous mixture of 15 hair keratins (type I: K31-35 and K37-39, and type II: K81-86) with small amounts of epithelial keratins which exist in monomeric, dimeric, multimeric, and even degraded forms. Re-hydration with PBS enabled molecular assembly into an elastic solid-like hydrogel. Highly-porous scaffolds formed by lyophilization of the gel had the compression behavior of a cellular foam material and reverted back to gel upon wetting. Cytotoxicity assays showed that the EC50 for various cell lines were attained at 8-10 mg/mL keratose, indicating the non-toxic nature of the material. Implantation in mouse subcutaneous tissue pockets demonstrated that keratose resorption follows a rectangular hyperbolic regression

  2. Biodegradable compounds: Rheological, mechanical and thermal properties

    NASA Astrophysics Data System (ADS)

    Nobile, Maria Rossella; Lucia, G.; Santella, M.; Malinconico, M.; Cerruti, P.; Pantani, R.

    2015-12-01

    Recently great attention from industry has been focused on biodegradable polyesters derived from renewable resources. In particular, PLA has attracted great interest due to its high strength and high modulus and a good biocompatibility, however its brittleness and low heat distortion temperature (HDT) restrict its wide application. On the other hand, Poly(butylene succinate) (PBS) is a biodegradable polymer with a low tensile modulus but characterized by a high flexibility, excellent impact strength, good thermal and chemical resistance. In this work the two aliphatic biodegradable polyesters PBS and PLA were selected with the aim to obtain a biodegradable material for the industry of plastic cups and plates. PBS was also blended with a thermoplastic starch. Talc was also added to the compounds because of its low cost and its effectiveness in increasing the modulus and the HDT of polymers. The compounds were obtained by melt compounding in a single screw extruder and the rheological, mechanical and thermal properties were investigated. The properties of the two compounds were compared and it was found that the values of the tensile modulus and elongation at break measured for the PBS/PLA/Talc compound make it interesting for the production of disposable plates and cups. In terms of thermal resistance the compounds have HDTs high enough to contain hot food or beverages. The PLA/PBS/Talc compound can be, then, considered as biodegradable substitute for polystyrene for the production of disposable plates and cups for hot food and beverages.

  3. Hemostatic and Wound Healing Properties of Chromolaena odorata Leaf Extract

    PubMed Central

    Pandith, Hataichanok; Liggett, Jason; Min, Kyung-Won; Gritsanapan, Wandee; Baek, Seung Joon

    2013-01-01

    Chromolaena odorata (L.) King and Robinson (Siam weed) extract has been used to stop bleeding and in wound healing in many tropical countries. However, its detailed mechanisms have not been elucidated. In this study, we examined the molecular mechanisms by which Siam weed extract (SWE) affected hemostatic and wound healing activities. SWE promoted Balb/c 3T3 fibroblast cell migration and proliferation. Subsequently, we found that heme oxygenase-1 (HO-1), the accelerating wound healing enzyme, was increased at the transcriptional and translational levels by SWE treatments. The HO-1 promoter analyzed with luciferase assay was also increased by treatment of SWE in a dose-dependent manner. This induction may be mediated by several kinase pathways including MEK, p38MAPK, AKT, and JNK. Quantitative real-time PCR using undifferentiated promonocytic cell lines revealed that thromboxane synthase (TXS), a potent vasoconstrictor and platelet aggregator, was increased and MMP-9, an anti platelet aggregator, was decreased in the presence of SWE. Our studies presented that SWE accelerated hemostatic and wound healing activities by altering the expression of genes, including HO-1, TXS, and MMP-9. PMID:23984087

  4. Hemostatic and Wound Healing Properties of Chromolaena odorata Leaf Extract.

    PubMed

    Pandith, Hataichanok; Zhang, Xiaobo; Liggett, Jason; Min, Kyung-Won; Gritsanapan, Wandee; Baek, Seung Joon

    2013-01-01

    Chromolaena odorata (L.) King and Robinson (Siam weed) extract has been used to stop bleeding and in wound healing in many tropical countries. However, its detailed mechanisms have not been elucidated. In this study, we examined the molecular mechanisms by which Siam weed extract (SWE) affected hemostatic and wound healing activities. SWE promoted Balb/c 3T3 fibroblast cell migration and proliferation. Subsequently, we found that heme oxygenase-1 (HO-1), the accelerating wound healing enzyme, was increased at the transcriptional and translational levels by SWE treatments. The HO-1 promoter analyzed with luciferase assay was also increased by treatment of SWE in a dose-dependent manner. This induction may be mediated by several kinase pathways including MEK, p38MAPK, AKT, and JNK. Quantitative real-time PCR using undifferentiated promonocytic cell lines revealed that thromboxane synthase (TXS), a potent vasoconstrictor and platelet aggregator, was increased and MMP-9, an anti platelet aggregator, was decreased in the presence of SWE. Our studies presented that SWE accelerated hemostatic and wound healing activities by altering the expression of genes, including HO-1, TXS, and MMP-9. PMID:23984087

  5. Photopatterning the mechanical properties of polydimethylsiloxane films

    NASA Astrophysics Data System (ADS)

    Cotton, D. P. J.; Popel, A.; Graz, I. M.; Lacour, S. P.

    2011-03-01

    Silicone rubber films with graded and localized mechanical properties are prepared using two-part polydimethylsiloxane (PDMS) elastomer, photoinhibitor compounds and conventional photolithography. First the un-cross-linked PDMS is mixed with benzophenone. The resulting positive photosensitive material is then exposed through a mask to UV light from a conventional mask aligner. Cross-linking of the UV exposed elastomer is inhibited, leading to softer regions than the surrounding unexposed matrix. By empirically fitting the nonlinear, hyperelastic Mooney-Rivlin model to experimentally measured stress-strain curves we determine the equivalent tensile modulus (E) of the rubber film. We show the PDMS tensile modulus can then be adjusted in the 0.65-2.9 MPa range by decreasing the UV exposure dose (from 24 000 to 0 mJ cm-2). Further, using a patterned UV mask, we can locally define differential regions of tensile modulus within a single PDMS rubber film. We demonstrate that "hard islands" (E ≈ 2.9 MPa) of 100 μm minimum diameter can be patterned within a 100-μm-thick, single "soft" PDMS rubber membrane (E ≈ 0.65 MPa) cured at 150 °C for 24 h. Thin gold film conductors patterned directly onto the photopatterned PDMS are stretchable and withstand uniaxial cycling to tens of percent strain. The mechanically "pixellated" PDMS rubber film provides an improved substrate with built-in strain relief for stretchable electronics.

  6. Mechanical Properties of a Single Cancellous Bone Trabeculae Taken from Bovine Femur

    NASA Astrophysics Data System (ADS)

    Enoki, Shinichi; Sato, Mitsuhiro; Tanaka, Kazuto; Katayama, Tsutao

    The increase of patients with osteoporosis is becoming a social problem, thus it is an urgent issue to find its prevention and treatment methods. Since cancellous bone is metabolically more active than cortical bone, cancellous bone is often used for diagnosis of osteoporosis and has received much attention within the study of bone. Bone is a hierarchically structured material and its mechanical properties vary at different structural levels, therefore it is important to break down the mechanical testing of bone according to the various levels within bone material. Mechanical properties of cancellous bone is said to be depended on quantities and orientation of trabecular bone. It is supposed that mechanical properties of trabecular bone are constant without depending on any structural arrangement and parts. However, such assumption has not been established in studies of trabecular bone. Furthermore test results have a large margin of error caused by insufficient shape assessment. In this study, three point bending tests of single cancellous bone trabeculae extracted from bovine femur were conducted to evaluate the effects of directions to the femur major axis direction on the mechanical properties. X-ray μCT was used to obtain shape of trabecular bone specimens. Furthermore compression tests of cancellous bone specimens, which were extracted in 10mm cubic geometry, were conducted for evaluation of directional properties.There were small difference in the elastic modulus of the trabecular bones which were extracted in parallel and in perpendicular to the major axis of femur. Considering from the results that the cancellous bone specimens, which were extracted in 10mm cubic geometry, have different elastic properties depending on the tested directions; the bone structure has larger influence than bone material property on the mechanical properties of cancellous bone.

  7. Trabecular Bone Mechanical Properties and Fractal Dimension

    NASA Technical Reports Server (NTRS)

    Hogan, Harry A.

    1996-01-01

    Countermeasures for reducing bone loss and muscle atrophy due to extended exposure to the microgravity environment of space are continuing to be developed and improved. An important component of this effort is finite element modeling of the lower extremity and spinal column. These models will permit analysis and evaluation specific to each individual and thereby provide more efficient and effective exercise protocols. Inflight countermeasures and post-flight rehabilitation can then be customized and targeted on a case-by-case basis. Recent Summer Faculty Fellowship participants have focused upon finite element mesh generation, muscle force estimation, and fractal calculations of trabecular bone microstructure. Methods have been developed for generating the three-dimensional geometry of the femur from serial section magnetic resonance images (MRI). The use of MRI as an imaging modality avoids excessive exposure to radiation associated with X-ray based methods. These images can also detect trabecular bone microstructure and architecture. The goal of the current research is to determine the degree to which the fractal dimension of trabecular architecture can be used to predict the mechanical properties of trabecular bone tissue. The elastic modulus and the ultimate strength (or strain) can then be estimated from non-invasive, non-radiating imaging and incorporated into the finite element models to more accurately represent the bone tissue of each individual of interest. Trabecular bone specimens from the proximal tibia are being studied in this first phase of the work. Detailed protocols and procedures have been developed for carrying test specimens through all of the steps of a multi-faceted test program. The test program begins with MRI and X-ray imaging of the whole bones before excising a smaller workpiece from the proximal tibia region. High resolution MRI scans are then made and the piece further cut into slabs (roughly 1 cm thick). The slabs are X-rayed again

  8. Flexible Mechanical Conveyors for Regolith Extraction and Transport

    NASA Technical Reports Server (NTRS)

    Walton, Otis R.; Vollmer, Hubert J.

    2013-01-01

    A report describes flexible mechanical conveying systems for transporting fine cohesive regolith under microgravity and vacuum conditions. They are totally enclosed, virtually dust-free, and can include enough flexibility in the conveying path to enable an expanded range of extraction and transport scenarios, including nonlinear drill-holes and excavation of enlarged subsurface openings without large entry holes. The design of the conveyors is a modification of conventional screw conveyors such that the central screw-shaft and the outer housing or conveyingtube have a degree of bending flexibility, allowing the conveyors to become nonlinear conveying systems that can convey around gentle bends. The central flexible shaft is similar to those used in common tools like a weed whacker, consisting of multiple layers of tightly wound wires around a central wire core. Utilization of compliant components (screw blade or outer wall) increases the robustness of the conveying, allowing an occasional oversized particle to pass hough the conveyor without causing a jam or stoppage

  9. Physicochemical properties of modified citrus pectins extracted from orange pomace.

    PubMed

    Venzon, Simoni Spohr; Canteri, Maria Helene Giovanetti; Granato, Daniel; Junior, Bogdan Demczuk; Maciel, Giselle Maria; Stafussa, Ana Paula; Haminiuk, Charles Windson Isidoro

    2015-07-01

    Modified pectin is a polysaccharide rich in galacturonic acid altered by pH adjustment and thermal treatment used especially as an anti-cancer agent. The aim of this work was to study the physical and chemical properties of modified pectins extracted from orange pomace with citric and nitric acids. The galacturonic acid content, degree of esterification, Fourier Transform Infrared Spectroscopy profile, molecular weight, intrinsic viscosity, rheological properties and antioxidant activity of the pectins were evaluated. The modification process caused the de-esterification of pectins and a decrease of molecular weight due to removal of neutral sugars, maintaining the linear chain of galacturonic acid. Such changes also caused a significant increase in the in vitro antioxidant activity (p ≤ 0.05) and influenced the rheological properties of pectin, reducing its viscosity. This work showed that the modification of pectin from orange pomace with citric and nitric acids altered its structural and physical characteristics as well as its biological activity toward a free-radical. PMID:26139875

  10. On the mechanical properties of tooth enamel under spherical indentation.

    PubMed

    Chai, Herzl

    2014-11-01

    The mechanical properties of tooth enamel generally exhibit large variations, which reflect its structural and material complexity. Some key properties were evaluated under localized contact, simulating actual functioning conditions. Prominent cusps of extracted human molar teeth were polished down ~0.7 mm below the cusp tip and indented by tungsten carbide balls. The internal damage was assessed after unloading from longitudinal or transverse sections. The ultimate tensile stress (UTS) was determined using a novel bilayer specimen. The damage is characterized by penny-like radial cracks driven by hoop stresses and cylindrical cracks driven along protein-rich interrod materials by shear stresses. Shallow cone cracks typical of homogeneous materials which may cause rapid tooth wear under repeat contact are thus avoided. The mean stress vs. indentation strain curve is highly nonlinear, attributable to plastic shearing of protein between and within enamel rods. This curve is also affected by damage, especially radial cracks, the onset of which depends on ball radius. Several material properties were extracted from the tests, including shear strain at the onset of ring cracks γ(F) (=0.14), UTS (=119 MPa), toughness K(C) (=0.94 MPa m(1/2)), a crack propagation law and a constitutive response determined by trial and error with the aid of a finite-element analysis. These quantities, which are only slightly sensitive to anatomical location within the enamel region tested, facilitate a quantitative assessment of crown failure. Causes for variations in published UTS and K(C) values are discussed. PMID:25034644

  11. Mechanical Extraction of Power From Ocean Currents and Tides

    NASA Technical Reports Server (NTRS)

    Jones, Jack; Chao, Yi

    2010-01-01

    A proposed scheme for generating electric power from rivers and from ocean currents, tides, and waves is intended to offer economic and environmental advantages over prior such schemes, some of which are at various stages of implementation, others of which have not yet advanced beyond the concept stage. This scheme would be less environmentally objectionable than are prior schemes that involve the use of dams to block rivers and tidal flows. This scheme would also not entail the high maintenance costs of other proposed schemes that call for submerged electric generators and cables, which would be subject to degradation by marine growth and corrosion. A basic power-generation system according to the scheme now proposed would not include any submerged electrical equipment. The submerged portion of the system would include an all-mechanical turbine/pump unit that would superficially resemble a large land-based wind turbine (see figure). The turbine axis would turn slowly as it captured energy from the local river flow, ocean current, tidal flow, or flow from an ocean-wave device. The turbine axis would drive a pump through a gearbox to generate an enclosed flow of water, hydraulic fluid, or other suitable fluid at a relatively high pressure [typically approx.500 psi (approx.3.4 MPa)]. The pressurized fluid could be piped to an onshore or offshore facility, above the ocean surface, where it would be used to drive a turbine that, in turn, would drive an electric generator. The fluid could be recirculated between the submerged unit and the power-generation facility in a closed flow system; alternatively, if the fluid were seawater, it could be taken in from the ocean at the submerged turbine/pump unit and discharged back into the ocean from the power-generation facility. Another alternative would be to use the pressurized flow to charge an elevated reservoir or other pumped-storage facility, from whence fluid could later be released to drive a turbine/generator unit at a

  12. Immunomodulatory properties of cacao extracts - potential consequences for medical applications.

    PubMed

    Becker, Kathrin; Geisler, Simon; Ueberall, Florian; Fuchs, Dietmar; Gostner, Johanna M

    2013-01-01

    Anti-inflammatory properties of cacao, fruits of Theobroma cacao L. (Sterculiaceae), are well documented, and therapeutic applications are described for gastrointestinal, nervous, and cardiovascular abnormalities. Most, if not all of these disease conditions involve inflammation or immune activation processes. The pro-inflammatory cytokine interferon-γ (IFN-γ) and related biochemical pathways like tryptophan breakdown by indoleamine 2,3-dioxygenase (IDO) and neopterin formation are deeply involved in their pathogenesis. Neopterin concentrations and the kynurenine to tryptophan ratio (Kyn/Trp, an estimate of IDO activity) are elevated in a significant proportion of patients with virus infections, cancer, autoimmune syndrome, neurodegeneration, and coronary artery disease. Moreover, higher neopterin and Kyn/Trp concentrations are indicative for poor prognosis. When investigating the effect of aqueous or ethanolic extracts of cacao on IFN-γ, neopterin and Kyn/Trp concentrations in mitogen-stimulated human peripheral blood mononuclear cells, breakdown of tryptophan by IDO, and formation of neopterin and IFN-γ were dose-dependently suppressed. The effects observed in the cell-based assays are associated with the antioxidant activity of the cacao extracts as determined by the cell-free oxygen radical absorption capacity assay. The influence of cacao extracts on IDO activity could be of particular relevance for some of the beneficial health effects ascribed to cacao: tryptophan breakdown by IDO is strongly involved in immunoregulation, and the diminished availability of tryptophan limits the biosynthesis of neurotransmitter serotonin. The inhibition of tryptophan breakdown by cacao constituents could thus be relevant not only for immune system restoration in patients, but also contribute to mood elevation and thereby improve quality of life. However, the available data thus far are merely in vitro only and future studies need to investigate the influence of cacao on

  13. Are extracted materials truly representative of original samples? Impact of C18 extraction on CDOM optical and chemical properties

    NASA Astrophysics Data System (ADS)

    Andrew, Andrea; Del Vecchio, Rossana; Zhang, Yi; Subramaniam, Ajit; Blough, Neil

    2016-02-01

    Some properties of dissolved organic matter (DOM) and chromophoric dissolved organic matter (CDOM) can be easily measured directly on whole waters, while others require sample concentration and removal of natural salts. To increase CDOM content and eliminate salts, solid phase extraction is often employed. Biases following extraction and elution are inevitable, thus raising the question of how truly representative the extracted material is of the original. In this context, we investigated the wavelength dependence of extraction efficiency for C18 cartridges with respect to CDOM optical properties using samples obtained from the Middle Atlantic Bight (MAB) and the Equatorial Atlantic Ocean (EAO). Further, we compared the optical changes of C18 extracts and the corresponding whole water following chemical reduction with sodium borohydride (NaBH4). C18 cartridges preferentially extracted long-wavelength absorbing/emitting material for samples impacted by riverine input. Extraction efficiency overall decreased with offshore distance away from riverine input. Spectral slopes of C18-OM samples were also almost always lower than those of their corresponding CDOM samples supporting the preferential extraction of higher molecular weight absorbing material. The wavelength dependence of the optical properties (absorption, fluorescence emission and quantum yield) of the original water samples and their corresponding extracted material were very similar. C18 extracts and corresponding water samples further exhibited comparable optical changes following NaBH4 reduction, thus suggesting a similarity in nature (structure) of the optically active extracted material, independent of geographical locale. Altogether, these data suggested a strong similarity between C18 extracts and corresponding whole waters, thus indicating that extracts are representative of the CDOM content of original waters.

  14. Are Extracted Materials Truly Representative of Original Samples? Impact of C18 Extraction on CDOM Optical and Chemical Properties

    PubMed Central

    Andrew, Andrea A.; Del Vecchio, Rossana; Zhang, Yi; Subramaniam, Ajit; Blough, Neil V.

    2016-01-01

    Some properties of dissolved organic matter (DOM) and chromophoric dissolved organic matter (CDOM) can be easily measured directly on whole waters, while others require sample concentration and removal of natural salts. To increase CDOM content and eliminate salts, solid phase extraction (SPE) is often employed. Biases following extraction and elution are inevitable, thus raising the question of how truly representative the extracted material is of the original. In this context, we investigated the wavelength dependence of extraction efficiency for C18 cartridges with respect to CDOM optical properties using samples obtained from the Middle Atlantic Bight (MAB) and the Equatorial Atlantic Ocean (EAO). Further, we compared the optical changes of C18 extracts and the corresponding whole water following chemical reduction with sodium borohydride (NaBH4). C18 cartridges preferentially extracted long-wavelength absorbing/emitting material for samples impacted by riverine input. Extraction efficiency overall decreased with offshore distance away from riverine input. Spectral slopes of C18-OM samples were also almost always lower than those of their corresponding CDOM samples supporting the preferential extraction of higher molecular weight absorbing material. The wavelength dependence of the optical properties (absorption, fluorescence emission, and quantum yield) of the original water samples and their corresponding extracted material were very similar. C18 extracts and corresponding water samples further exhibited comparable optical changes following NaBH4 reduction, thus suggesting a similarity in nature (structure) of the optically active extracted material, independent of geographical locale. Altogether, these data suggested a strong similarity between C18 extracts and corresponding whole waters, thus indicating that extracts are representative of the CDOM content of original waters. PMID:26904536

  15. Are Extracted Materials Truly Representative of Original Samples? Impact of C18 Extraction on CDOM Optical and Chemical Properties.

    PubMed

    Andrew, Andrea A; Del Vecchio, Rossana; Zhang, Yi; Subramaniam, Ajit; Blough, Neil V

    2016-01-01

    Some properties of dissolved organic matter (DOM) and chromophoric dissolved organic matter (CDOM) can be easily measured directly on whole waters, while others require sample concentration and removal of natural salts. To increase CDOM content and eliminate salts, solid phase extraction (SPE) is often employed. Biases following extraction and elution are inevitable, thus raising the question of how truly representative the extracted material is of the original. In this context, we investigated the wavelength dependence of extraction efficiency for C18 cartridges with respect to CDOM optical properties using samples obtained from the Middle Atlantic Bight (MAB) and the Equatorial Atlantic Ocean (EAO). Further, we compared the optical changes of C18 extracts and the corresponding whole water following chemical reduction with sodium borohydride (NaBH4). C18 cartridges preferentially extracted long-wavelength absorbing/emitting material for samples impacted by riverine input. Extraction efficiency overall decreased with offshore distance away from riverine input. Spectral slopes of C18-OM samples were also almost always lower than those of their corresponding CDOM samples supporting the preferential extraction of higher molecular weight absorbing material. The wavelength dependence of the optical properties (absorption, fluorescence emission, and quantum yield) of the original water samples and their corresponding extracted material were very similar. C18 extracts and corresponding water samples further exhibited comparable optical changes following NaBH4 reduction, thus suggesting a similarity in nature (structure) of the optically active extracted material, independent of geographical locale. Altogether, these data suggested a strong similarity between C18 extracts and corresponding whole waters, thus indicating that extracts are representative of the CDOM content of original waters. PMID:26904536

  16. Characterisation, quantity and sorptive properties of microplastics extracted from cosmetics.

    PubMed

    Napper, Imogen E; Bakir, Adil; Rowland, Steven J; Thompson, Richard C

    2015-10-15

    Cosmetic products, such as facial scrubs, have been identified as potentially important primary sources of microplastics to the marine environment. This study characterises, quantifies and then investigates the sorptive properties of plastic microbeads that are used as exfoliants in cosmetics. Polyethylene microbeads were extracted from several products, and shown to have a wide size range (mean diameters between 164 and 327 μm). We estimated that between 4594 and 94,500 microbeads could be released in a single use. To examine the potential for microbeads to accumulate and transport chemicals they were exposed to a binary mixture of (3)H-phenanthrene and (14)C-DDT in seawater. The potential for transport of sorbed chemicals by microbeads was broadly similar to that of polythene (PE) particles used in previous sorption studies. In conclusion, cosmetic exfoliants are a potentially important, yet preventable source of microplastic contamination in the marine environment. PMID:26234612

  17. Mechanical properties of thermal protection system materials.

    SciTech Connect

    Hardy, Robert Douglas; Bronowski, David R.; Lee, Moo Yul; Hofer, John H.

    2005-06-01

    An experimental study was conducted to measure the mechanical properties of the Thermal Protection System (TPS) materials used for the Space Shuttle. Three types of TPS materials (LI-900, LI-2200, and FRCI-12) were tested in 'in-plane' and 'out-of-plane' orientations. Four types of quasi-static mechanical tests (uniaxial tension, uniaxial compression, uniaxial strain, and shear) were performed under low (10{sup -4} to 10{sup -3}/s) and intermediate (1 to 10/s) strain rate conditions. In addition, split Hopkinson pressure bar tests were conducted to obtain the strength of the materials under a relatively higher strain rate ({approx}10{sup 2} to 10{sup 3}/s) condition. In general, TPS materials have higher strength and higher Young's modulus when tested in 'in-plane' than in 'through-the-thickness' orientation under compressive (unconfined and confined) and tensile stress conditions. In both stress conditions, the strength of the material increases as the strain rate increases. The rate of increase in LI-900 is relatively small compared to those for the other two TPS materials tested in this study. But, the Young's modulus appears to be insensitive to the different strain rates applied. The FRCI-12 material, designed to replace the heavier LI-2200, showed higher strengths under tensile and shear stress conditions. But, under a compressive stress condition, LI-2200 showed higher strength than FRCI-12. As far as the modulus is concerned, LI-2200 has higher Young's modulus both in compression and in tension. The shear modulus of FRCI-12 and LI-2200 fell in the same range.

  18. Anticholinesterase and Antioxidative Properties of Aqueous Extract of Cola acuminata Seed In Vitro

    PubMed Central

    Akinyemi, Ayodele J.; Omojokun, Olasunkanmi S.; Oyeleye, Idowu S.

    2014-01-01

    Background. Cola acuminata seed, a commonly used stimulant in Nigeria, has been reportedly used for the management of neurodegenerative diseases in folklore without scientific basis. This study sought to investigate the anticholinesterase and antioxidant properties of aqueous extracts from C. acuminata seed in vitro. Methodology. The aqueous extract of C. acuminata seed was prepared (w/v) and its effect on acetylcholinesterase (AChE) and butyrylcholinesterase activities, as well as some prooxidant (FeSO4, sodium nitroprusside (SNP), and quinolinic acid (QA)) induced lipid peroxidation in rat brain in vitro, was investigated. Results. The results revealed that C. acuminata seed extract inhibited AChE (IC50 = 14.6 μg/mL) and BChE (IC50 = 96.2 μg/mL) activities in a dose-dependent manner. Furthermore, incubation of rat's brain homogenates with some prooxidants caused a significant increase P < 0.05 in the brain malondialdehyde (MDA) content and inhibited MDA production dose-dependently and also exhibited further antioxidant properties as typified by their high radicals scavenging and Fe2+ chelating abilities. Conclusion. Inhibition of AChE and BChE activities has been the primary treatment method for mild Alzheimer's disease (AD). Therefore, one possible mechanism through which the seed exerts its neuroprotective properties is by inhibiting cholinesterase activities as well as preventing oxidative-stress-induced neurodegeneration. However, this is a preliminary study with possible physiological implications. PMID:25506036

  19. Mechanical Properties of Nb-1Zr Weldments

    NASA Astrophysics Data System (ADS)

    Santella, Michael; McNabb, Jeffery; Frederick, Alan

    2005-02-01

    The objective of this work was to measure the mechanical properties of Nb-1Zr weldments, and, more specifically, to evaluate whether Charpy V-notch impact testing may be a more meaningful indication of weld deposit ductility than the slow bend testing. Manual gas-tungsten-arc welds were made in Mb-1Zr plates using 4 beads of filler wire from the same heat. The cold-rolled plates were recrystallized by heat treatment at 1773 K for 1 hour prior to welding. Welded plates were made in a stainless steel welding glove box backfilled with either argon or helium. Two plates were made with each gas, with one plate post-weld heat treated at 1373 K. Weld metal from each of the four welded plates was subjected to chemical analysis, tensile testing at room temperature, and Charpy V-notch testing at 93-473 K. Also, microhardness testing was used to evaluate property gradients in the weldments. Impurity concentrations in the weld deposits compared well with the base metal concentrations and were within the limits of the relevant ASTM specification, B393 Type 3. All specimens with one minor exception had yield strengths, tensile strengths, and ductilities that exceeded the ASTM specified minimums. The Charpy V-notch specimens from the as-welded He weld deposit, and from both post-weld-heat-treated weld deposits showed similar behavior with upper shelf energies of 9.7-10 J and ductile-brittle transition temperatures of 85-100 K. These Charpy V-notch properties were comparable to those of the unwelded plate. The as-welded Ar weld deposit had a slightly higher ductile-brittle transition temperature near 150 K. Microhardness testing indicated that in the as-welded conditions the average hardness of the weld deposit made in Ar was higher than that made in He. Post-weld heat treatment reduced the average hardnesses of base metal and weld metal. The range of hardnesses in the weld deposits was increased by the post weld heat treatment.

  20. Mechanical properties of the porcine growth plate vary with developmental stage.

    PubMed

    Wosu, Roxanne; Sergerie, Kim; Lévesque, Martin; Villemure, Isabelle

    2012-03-01

    The objectives of this study were to extract the intrinsic mechanical properties of the growth plate at four different stages of growth and to compare two different methods of extracting these properties. Porcine distal ulnar growth plate samples were obtained from newborn, 4-, 8-, and 18-week (W) pigs and were tested using stress relaxation tests under unconfined compression. A four-parameter curve fitting procedure was developed to extract mechanical properties using the Transversely Isotropic Biphasic Elastic model(TIBPE) (Cohen et al. in J Biomech Eng Trans Asme 120(4):491-496, 1998) and the Differential Evolution (DE) optimization algorithm (Price et al. Natural computing series, Springer, Germany 2005). Optimization was done on all experimental curves for the first method and on one average experimental curve per developmental stage in the second. The 4-week stage was studied in two subgroups (a) and (b) due to distinct differences in mechanical properties. Intrinsic mechanical properties of the growth plate varied nonlinearly with developmental stage. Both methods showed that transverse and out-of-plane Young's moduli (E (1), E (3)) decrease with developmental stage, whereas transverse permeability (k (1)) increases. The exception is a sharp increase in stiffness and reduction in permeability at the 4W(a) stage, which may be associated with rapid porcine developmental changes at the 3-4 week period. The second method provides a more reliable representation of the average mechanical behavior, whereas the first method allows statistical comparison of optimized mechanical properties. This study characterizes, for the first time, the variation in growth plate mechanical properties for the same animal (porcine) and bone (ulna) model with developmental stage and provides new insight into the progression of musculoskeletal diseases during growth spurts in response to mechanical loading. PMID:21559968

  1. Mechanical Properties of Nuclear Fuel Surrogates using Picosecond Laser Ultrasonics

    SciTech Connect

    David Hurley; Marat Khafizov; Farhad Farzbod; Eric Burgett

    2013-05-01

    Detailed understanding between microstructure evolution and mechanical properties is important for designing new high burnup nuclear fuels. In this presentation we discuss the use of picosecond ultrasonics to measure localize changes in mechanical properties of fuel surrogates. We develop measurement techniques that can be applied to investigate heterogeneous elastic properties caused by localize changes in chemistry, grain microstructure caused by recrystallization, and mechanical properties of small samples prepared using focused ion beam sample preparation. Emphasis is placed on understanding the relationship between microstructure and mechanical properties

  2. Tuning the mechanical properties of silica microcapsules.

    PubMed

    Zhang, Lijuan; D'Acunzi, Maria; Kappl, Michael; Imhof, Arnout; van Blaaderen, Alfons; Butt, Hans-Jürgen; Graf, Robert; Vollmer, Doris

    2010-12-21

    Heat treatment is a standard method to increase the hardness of silica in various applications. Here, we tested the effect of high temperature annealing on the mechanical properties of silica microcapsules by force spectroscopy under point loads applied to the particle shell. The Young's modulus of the shells moderately increases after annealing at temperatures above 500 °C. Temperatures over 850 °C result in a much stronger increase and the Young's modulus is close to that of fused silica after annealing at 1100 °C. NMR analysis revealed that in untreated microcapsules synthesized by seeded growth using the Stöber method only 55% of the silicon atoms form siloxane bonds with four neighbors, whereas the remaining ones only form three or less siloxane bonds each and, thus, a large number of ethoxy and silanol groups still exist. During annealing at 500 °C, these are successively transformed into siloxane bonds through condensation reactions. This process correlates with only a moderate increase in Young's modulus. The strong increase at temperatures above 850 °C was associated with a densification which was associated by a decrease in capsule size and shell thickness while the shells remained homogenous and of spherical shape. The main strengthening of the shells is thus mainly due to compaction by sintering at length scales significantly larger than that of local siloxane bonds. PMID:20963236

  3. Nonlinear NDE of Concrete Mechanical Properties

    NASA Astrophysics Data System (ADS)

    Shkolnik, Iosif E.

    2006-05-01

    Obtained theoretical relationship shows that the strength of concrete increases if the nonlinear parameter decreases. Experimental data proved that modulus of elasticity, ultrasound pulse velocity and nonlinear parameter are independent characteristics of concrete. Two nondestructive patent methods based on the measurement of resonant frequency shift and phase shift are described. These nonlinear nondestructive methods can be used when conventional acoustic methods are not applicable for evaluating strength of concrete. The relationship between static and dynamic modulus is obtained from the thermofluctuation theory and nonlinear equation of state of concrete. Corresponding relationship shows that the ratio of the static to the dynamic modulus of elasticity depends on the strength of concrete, its temperature, ratio and rate of loading, and that dynamic modulus is greater than static modulus of elasticity. Comparative study illustrates substantial agreement between obtained relationships and existing experimental results as well as general equations given in standards. Presented data illustrate the potential of the nonlinear approach, and indicate a new direction for nonlinear nondestructive methods of evaluating mechanical properties of concrete.

  4. Mechanical properties of lattice grid composites

    NASA Astrophysics Data System (ADS)

    Fan, Hualin; Fang, Daining; Jin, Fengnian

    2008-08-01

    An equivalent continuum method only considering the stretching deformation of struts was used to study the in-plane stiffness and strength of planar lattice grid composite materials. The initial yield equations of lattices were deduced. Initial yield surfaces were depicted separately in different 3D and 2D stress spaces. The failure envelope is a polyhedron in 3D spaces and a polygon in 2D spaces. Each plane or line of the failure envelope is corresponding to the yield or buckling of a typical bar row. For lattices with more than three bar rows, subsequent yield of the other bar row after initial yield made the lattice achieve greater limit strength. The importance of the buckling strength of the grids was strengthened while the grids were relative sparse. The integration model of the method was used to study the nonlinear mechanical properties of strain hardening grids. It was shown that the integration equation could accurately model the complete stress-strain curves of the grids within small deformations.

  5. Fluid Mechanical Properties of Silkworm Fibroin Solutions

    NASA Astrophysics Data System (ADS)

    Matsumoto, Akira

    2005-11-01

    The aqueous solution behavior of silk fibroin is of interest due to the assembly and processing of this protein related to the spinning of protein fibers that exhibit remarkable mechanical properties. To gain insight into the origins of this functional feature, it is desired to determine how the protein behaves under a range of solution conditions. Pure fibroin at different concentrations in water was studied for surface tension, as a measure of surfactancy. In addition, shear induced changes on these solutions in terms of structure and morphology was also determined. Fibroin solutions exhibited shear rate-sensitive viscosity changes and precipitated at a critical shear rate where a dramatic increase of 75-150% of the initial value was observed along with a decrease in viscosity. In surface tension measurements, critical micelle concentrations were in the range of 3-4% w/v. The influence of additional factors, such as sericin protein, divalent and monovalent cations, and pH on the solution behavior in relation to structural and morphological features will also be described.

  6. Mechanical properties of hybrid polymer nanotube systems

    NASA Astrophysics Data System (ADS)

    Coleman, Jonathan N.; Cadek, Martin; Dalton, Alan B.; Munoz, Edgar; Razal, Joselito; Baughman, Ray H.; Blau, Werner J.

    2003-04-01

    In this work, mechanical properties of hybrid materials fabricated from nanotubes and commercially available polymers were investigated. It was found that, by adding various concentrations of arc discharge multiwall nanotubes, both Young"s modulus and hardness increased by factors of 1.8 and 1.6 at 1wt% in PVA and 2.8 and 2.0 at 8wt% in PVK, in reasonable agreement with the Halpin-Tsai theory. Furthermore, the presence of the nanotubes was found to nucleate crystallization of the PVA. This crystal growth is thought to enhance matrix-nanotube stress transfer. In addition, microscopy studies suggest extremely strong interfacial bonding in the PVA-based composite. This is manifested by the fracture of the polymer rather that the polymer-nanotube interface. The dependence of the polymer nanotube interfacial interaction on host polymer was studied by intercalating various polymers (PVA, PVP and PS) into single wall nanotube buckypaper. Even for short soak times, significant polymer intercalation into existing free volume was observed. Depending on the polymer and the level of intercalation tensile tests on intercalated sheets showed that the Young"s modulus, strength and toughness increased by factors of 3, 9 and 28, respectively. This indicates that the intercalated polymer enhances load transmission between nanotubes due the significant stress transfer. The level of stress transfer was observed to scale with polymer hydrophobicity as expected.

  7. Mechanical Properties of the Upper Airway

    PubMed Central

    Strohl, Kingman P.; Butler, James P.; Malhotra, Atul

    2013-01-01

    The importance of the upper airway (nose, pharynx, and larynx) in health and in the pathogenesis of sleep apnea, asthma, and other airway diseases, discussed elsewhere in the Comprehensive Physiology series, prompts this review of the biomechanical properties and functional aspects of the upper airway. There is a literature based on anatomic or structural descriptions in static circumstances, albeit studied in limited numbers of individuals in both health and disease. As for dynamic features, the literature is limited to studies of pressure and flow through all or parts of the upper airway and to the effects of muscle activation on such features; however, the links between structure and function through airway size, shape, and compliance remain a topic that is completely open for investigation, particularly through analyses using concepts of fluid and structural mechanics. Throughout are included both historically seminal references, as well as those serving as signposts or updated reviews. This article should be considered a resource for concepts needed for the application of biomechanical models of upper airway physiology, applicable to understanding the pathophysiology of disease and anticipated results of treatment interventions. PMID:23723026

  8. Information processing tools for extracting the electrical properties of nanoparticles

    NASA Astrophysics Data System (ADS)

    Bakewell, David J.; Bailey, Joe; Holmes, David

    2015-02-01

    Newly developed information processing tools are described that enable easy-to-use, fast extraction of the electrical properties of nanoparticles. Positive dielectrophoretic (pDEP) collection rate analysis enables the dielectric properties of very small samples of nanoparticles to be accurately quantified. We report the latest advances of semi-automated image quantification methods that are applied to pDEP collection experiments using dual-cycle pulsed pDEP [1]. Compared to traditional methods that require information about the geometry of the electrode array to be entered for semi-automated quantification [2], the new statistic-based approach described does not require a priori knowledge of device geometry. Consequently, the statistical method is supervisor-free, fast and suitable for laboratory application. The statistical method gives estimates for the nanoparticle conductivity and surface conductance that agree closely to those obtained using more complex geometric methods. The efficacy of the method is demonstrated using 200 nm diameter latex nanospheres yielding a nanoparticle conductivity value of 25.8 mS/m and surface conductance value of 1.29 nS. These values agree closely with values using traditional measurements.

  9. Cell Mechanosensitivity: Mechanical Properties and Interaction with Gravitational Field

    PubMed Central

    Ogneva, I. V.

    2013-01-01

    This paper addressed the possible mechanisms of primary reception of a mechanical stimulus by different cells. Data concerning the stiffness of muscle and nonmuscle cells as measured by atomic force microscopy are provided. The changes in the mechanical properties of cells that occur under changed external mechanical tension are presented, and the initial stages of mechanical signal transduction are considered. The possible mechanism of perception of different external mechanical signals by cells is suggested. PMID:23509748

  10. Rectangular waveguide material characterization: anisotropic property extraction and measurement validation

    NASA Astrophysics Data System (ADS)

    Crowgey, Benjamin Reid

    for characterization of a sample filling the cross-section of a waveguide. Due to the rectangular nature of the waveguide, typically three different samples are manufactured from the same material in order to characterize the six complex material parameters. The second technique for measuring the electromagnetic properties of a biaxially anisotropic material sample uses a reduced-aperture waveguide sample holder designed to accommodate a cubical sample. All the tensor material parameters can then be determined by measuring the reflection and transmission coefficients of a single sample placed into several orientations. The parameters are obtained using a root-searching algorithm by comparing theoretically computed and measured reflection and transmission coefficients. The theoretical coefficients are determined using a mode matching technique. The first technique for characterizing the electromagnetic properties of gyromagnetic materials considers requires filling the cross-section of a waveguide. The material parameters are extracted from the measured reflection and transmission coefficients. Since the cross-sectional dimensions of waveguides become prohibitively large at low frequencies, and it is at these frequencies that the gyromagnetic properties are most pronounced, sufficiently large samples may not be available. Therefore, the second technique uses a reduced-aperture sample holder that does not require the sample to fill the entire cross section of the guide. The theoretical reflection and transmission coefficients for both methods are determined using a mode matching technique. A nonlinear least squares method is employed to extract the gyromagnetic material parameters. Finally, this dissertation introduces a waveguide standard that acts as a surrogate material with both electric and magnetic properties and is useful for verifying systems designed to characterize engineered materials using the NRW technique. A genetic algorithm is used to optimize the all

  11. Auxetic oesophageal stents: structure and mechanical properties.

    PubMed

    Ali, Murtaza Najabat; Busfield, James J C; Rehman, Ihtesham U

    2014-02-01

    Oesophageal cancer is the ninth leading cause of malignant cancer death and its prognosis remains poor, ranking as the sixth most frequent cause of death in the world. This research work aims to adopt an Auxetic (rotating-squares) geometry device, that had previously been examined theoretically and analysed by Grima and Evans (J Mater Sci Lett 19(17):1563-1565, 2000), to produce a novel Auxetic oesophageal stent and stent-grafts relevant to the palliative treatment of oesophageal cancer and also for the prevention of dysphagia. This paper discusses the manufacture of a small diameter Auxetic oesophageal stent and stent-graft. The oral deployment of such an Auxetic stent would be simplest if a commercial balloon dilatational catheter was used as this obviates the need for an expensive dedicated delivery system. A novel manufacturing route was employed in this research to develop both Auxetic films and Auxetic oesophageal stents, which ranged from conventional subtractive techniques to a new additive manufacturing method. Polyurethane was selected as a material for the fabrication of Auxetic films and Auxetic oesophageal stents because of its good biocompatibility and non-toxicological properties. The Auxetic films were later used for the fabrication of seamed Auxetic oesophageal stents. The flexible polyurethane tubular grafts were also attached to the inner luminal side of the seamless Auxetic oesophageal stents, in order to prevent tumour in-growth. Scanning electron microscopy was used to conduct surface morphology study by using different Auxetic specimens developed from different conventional and new additive manufacturing techniques. Tensile testing of the Auxetic films was performed to characterise their mechanical properties. The stent expansion tests of the Auxetic stents were done to analyse the longitudinal extension and radial expansion of the Auxetic stent at a range of radial pressures applied by the balloon catheter, and to also identify the pressure

  12. Ultrasonic nondestructive evaluation, microstructure, and mechanical property interrelations

    NASA Technical Reports Server (NTRS)

    Vary, A.

    1984-01-01

    Ultrasonic techniques for mechanical property characterizations are reviewed and conceptual models are advanced for explaining and interpreting the empirically based results. At present, the technology is generally empirically based and is emerging from the research laboratory. Advancement of the technology will require establishment of theoretical foundations for the experimentally observed interrelations among ultrasonic measurements, mechanical properties, and microstructure. Conceptual models are applied to ultrasonic assessment of fracture toughness to illustrate an approach for predicting correlations found among ultrasonic measurements, microstructure, and mechanical properties.

  13. Extracting material response from simple mechanical tests on hardening-softening-hardening viscoplastic solids

    NASA Astrophysics Data System (ADS)

    Mohan, Nisha

    Compliant foams are usually characterized by a wide range of desirable mechanical properties. These properties include viscoelasticity at different temperatures, energy absorption, recoverability under cyclic loading, impact resistance, and thermal, electrical, acoustic and radiation-resistance. Some foams contain nano-sized features and are used in small-scale devices. This implies that the characteristic dimensions of foams span multiple length scales, rendering modeling their mechanical properties difficult. Continuum mechanics-based models capture some salient experimental features like the linear elastic regime, followed by non-linear plateau stress regime. However, they lack mesostructural physical details. This makes them incapable of accurately predicting local peaks in stress and strain distributions, which significantly affect the deformation paths. Atomistic methods are capable of capturing the physical origins of deformation at smaller scales, but suffer from impractical computational intensity. Capturing deformation at the so-called meso-scale, which is capable of describing the phenomenon at a continuum level, but with some physical insights, requires developing new theoretical approaches. A fundamental question that motivates the modeling of foams is `how to extract the intrinsic material response from simple mechanical test data, such as stress vs. strain response?' A 3D model was developed to simulate the mechanical response of foam-type materials. The novelty of this model includes unique features such as the hardening-softening-hardening material response, strain rate-dependence, and plastically compressible solids with plastic non-normality. Suggestive links from atomistic simulations of foams were borrowed to formulate a physically informed hardening material input function. Motivated by a model that qualitatively captured the response of foam-type vertically aligned carbon nanotube (VACNT) pillars under uniaxial compression [2011,"Analysis of

  14. Microstructure, mechanical properties, bio-corrosion properties and antibacterial properties of Ti-Ag sintered alloys.

    PubMed

    Chen, Mian; Zhang, Erlin; Zhang, Lan

    2016-05-01

    In this research, Ag element was selected as an antibacterial agent to develop an antibacterial Ti-Ag alloy by a powder metallurgy. The microstructure, phase constitution, mechanical properties, corrosion resistance and antibacterial properties of the Ti-Ag sintered alloys have been systematically studied by X-ray diffraction (XRD), scanning electron microscope (SEM), compressive test, electrochemical measurements and antibacterial test. The effects of the Ag powder size and the Ag content on the antibacterial property and mechanical property as well as the anticorrosion property have been investigated. The microstructure results have shown that Ti-Ag phase, residual pure Ag and Ti were the mainly phases in Ti-Ag(S75) sintered alloy while Ti2Ag was synthesized in Ti-Ag(S10) sintered alloy. The mechanical test indicated that Ti-Ag sintered alloy showed a much higher hardness and the compressive yield strength than cp-Ti but the mechanical properties were slightly reduced with the increase of Ag content. Electrochemical results showed that Ag powder size had a significant effect on the corrosion resistance of Ti-Ag sintered alloy. Ag content increased the corrosion resistance in a dose dependent way under a homogeneous microstructure. Antibacterial tests have demonstrated that antibacterial Ti-Ag alloy was successfully prepared. It was also shown that the Ag powder particle size and the Ag content influenced the antibacterial activity seriously. The reduction in the Ag powder size was benefit to the improvement in the antibacterial property and the Ag content has to be at least 3wt.% in order to obtain a strong and stable antibacterial activity against Staphylococcus aureus bacteria. The bacterial mechanism was thought to be related to the Ti2Ag and its distribution. PMID:26952433

  15. Understanding nanoscale mechanical properties of materials using ultrafast EUV photoacoustics

    NASA Astrophysics Data System (ADS)

    Hoogeboom-Pot, K.; Turgut, E.; Shaw, J.; Hernandez-Charpak, J.; Murnane, M.; Kapteyn, H.; Nardi, D.

    2014-03-01

    How do the elastic properties of materials evolve as a nanostructure builds up layer by layer? A host of questions in nanoscience, nanotechnology, quantum dot systems and more rely on an answer to this issue; but our ability to probe mechanical properties is severely constrained at dimensions below 100 nm. With tabletop high harmonic generation (HHG), we overcome these limitations by extending non-destructive visible photoacoustics to extreme ultraviolet (EUV) wavelengths. The short wavelength of EUV light, combined with the coherence and ultrashort pulses of HHG creates a unique and powerful probe of nanostructured materials on their intrinsic length and time scales. We study a series of ultrathin bilayer (10-nm Ni/0-6-nm Ta) nanostructures on SiO2 substrates. A femtosecond infrared pulse excites longitudinal acoustic waves (LAWs) within the nanostructures and surface acoustic waves (SAWs) in the substrate. Diffraction of a time-delayed EUV probe pulse monitors the dynamics. LAW resonances are directly related to the bilayer thickness and effective speed of sound; their dependence on Ta-layer thickness reveals that the LAW velocities of both Ni and Ta differ from bulk values. The changing mass of Ta also affects the SAW frequency, allowing us to extract nanoscale densities. This work was supported by the SRC Contract 2012-OJ-2304, by NSF Award No.: DGE 1144083, and used facilities provided by the NSF Engineering Research Center in EUV Science and Technology.

  16. Antioxidant properties of extracts from Ginkgo biloba leaves in meatballs.

    PubMed

    Kobus-Cisowska, Joanna; Flaczyk, Ewa; Rudzińska, Magdalena; Kmiecik, Dominik

    2014-06-01

    The aim was to determine the effect of Ginkgo leaf extracts on the stability of lipids and cholesterol in pork meatballs over 21days of refrigerated storage. The antioxidants used were characterized by their antioxidant activity towards lipids and cholesterol. Extracts were prepared from green and yellow leaves from Ginkgo biloba L. trees. Water, acetone and ethanol were used as extractants. The extracts showed stabilizing effects on both lipid and cholesterol oxidation processes. The lipid oxidation process of pork meatballs was mostly inhibited by the aqueous and ethanolic extracts of the yellow leaves. Their antioxidant activity was higher than that of BHT. All the extracts had a stabilizing effect on cholesterol and most of them inhibited the formation of oxidized derivatives. The acetone and ethanol extracts of green leaves and the ethanol extract of yellow leaves inhibited the formation of cholesterol oxidation products formation most effectively. PMID:24583325

  17. Bioactive glass/hydroxyapatite composites: mechanical properties and biological evaluation.

    PubMed

    Bellucci, Devis; Sola, Antonella; Anesi, Alexandre; Salvatori, Roberta; Chiarini, Luigi; Cannillo, Valeria

    2015-06-01

    Bioactive glass/hydroxyapatite composites for bone tissue repair and regeneration have been produced and discussed. The use of a recently developed glass, namely BG_Ca/Mix, with its low tendency to crystallize, allowed one to sinter the samples at a relatively low temperature thus avoiding several adverse effects usually reported in the literature, such as extensive crystallization of the glassy phase, hydroxyapatite (HA) decomposition and reaction between HA and glass. The mechanical properties of the composites with 80wt.% BG_Ca/Mix and 20wt.% HA are sensibly higher than those of Bioglass® 45S5 reference samples due to the presence of HA (mechanically stronger than the 45S5 glass) and to the thermal behaviour of the BG_Ca/Mix, which is able to favour the sintering process of the composites. Biocompatibility tests, performed with murine fibroblasts BALB/3T3 and osteocites MLO-Y4 throughout a multi-parametrical approach, allow one to look with optimism to the produced composites, since both the samples themselves and their extracts do not induce negative effects in cell viability and do not cause inhibition in cell growth. PMID:25842126

  18. Investigation of Phytochemical and Antioxidant Properties of Methanol Extract and Fractions of Ballota limbata (Lamiaceae).

    PubMed

    Waheed, I; Ahmad, M; Syed, N-H; Ashraf, Romeeza

    2014-05-01

    Ballota limbata (Lamiaceae) has been used for its antispasmodic, antiulcer, diuretic, vermifuge and sedative effects in folk medicine. However, little is known about how does it work to produce these therapeutic actions. Present research investigated phytochemical components and antioxidant properties of methanol extract and different fractions of Ballota limbata. In this study, phytochemical investigation was done by performing different chemical tests. Here, antioxidant property of the extract and fractions was investigated by using 1,1-diphenyl-2-picryl hydrazyl radical scavenging activity, total antioxidant activity by the phosphomolybdenum method, linoleic acid peroxidation, ferric thiocyanate analysis and ferric-reducing antioxidant power. Methanol extract and fractions showed presence of numerous chemical principles including alkaloids, cardiac glycosides, tannins and flavonoids. The ethyl acetate fraction exhibited higher scavenging activity compared to the other fractions under investigation. This fraction displayed 84.16±1.02% 1,1-diphenyl-2-picryl hydrazyl radical inhibition at a dose of 60 μg/ml. IC50 for 1,1-diphenyl-2-picryl hydrazylradical-scavenging activity was 13.53±0.22 μg/ml, relative to the standard, butylatedhydroxytoluene, having IC50 of 12.33±0.88 μg/ml. Thus, Ballota limbata showed significant antioxidant activity, which may contribute in the mechanism of above pharmacological actions. PMID:25035539

  19. Mechanical properties of materials at micro/nano scales

    NASA Astrophysics Data System (ADS)

    Xu, Wei-Hua

    Mechanical properties of materials in small dimensions, including the depth-dependent hardness at the nano/micrometer scales, and the mechanical characterization of thin films and nanotubes, are reported. The surface effect on the depth-dependent nano/microhardness was studied and an apparent surface stress was introduced to represent the energy dissipated per unit area of a solid surface. A plastic bearing ratio model was proposed for the nanoindentation of rough surfaces. The energy dissipation occurring at the indented surface is among the factors that cause the Indentation Size Effect (ISE) at the micro/nanometer scales. Furthermore, an elastic-plastic bearing ratio model was developed for nanoindentation of rough surfaces with a flat indenter tip. The theoretical predictions agree with the experimental results and finite element simulations, from which the elastic constant and the surface hardness were extracted. The surface hardness exhibits an inverse ISE due to the interaction of asperities. The nanoindentation tests on Highly Oriented Pyrolytic Graphite (HOPG) may lead to the formation of carbon tubes, which are rolled up by the delaminated graphite layers. The nanoindentation loading-unloading curves reveal single pop-in and multiple pop-in phenomena, which is induced by fracture of the graphite layers and/or by delamination between the layers. From the load at pop-in, the fracture strength of the layers and/or the bonding strength between the layers can be estimated by the elastic field model for Hertzian contact including sliding friction for transverse isotropy. Two novel methods were developed to estimate the mechanical properties of films, including the Raman spectra method for the estimation of residual stresses in thin ferroelectric films and the microbridge testing method for the mechanical characterization of trilayer thin films. Mechanical characterization was also carried out on Tobacco Mosaic Virus (TMV) nanotubes with each being comprised of

  20. Determination of antioxidant properties of aroma extracts from various beans.

    PubMed

    Lee, K G; Mitchell, A E; Shibamoto, T

    2000-10-01

    Aroma extracts from fresh soybeans, mung beans, kidney beans, and azuki beans were prepared using simultaneous steam distillation and solvent extraction (SDE) under mild conditions (55 degrees C and 95 mmHg). Extracts were examined for antioxidative activities in two different assays. The aroma extracts isolated from all beans inhibited the oxidation of hexanal for nearly one month at a level of 250 microL/mL. Mung bean and soybean extracts inhibited malonaldehyde (MA) formation from cod-liver oil by 86% and 88%, respectively, at the 250 microL/mL level. Azuki and kidney bean extracts inhibited MA formation from cod-liver oil by 76% and 53%, respectively, at the 250 microL/mL level. The antioxidative activities of mung bean and soybean extracts were comparable with that of the natural antioxidant, alpha-tocopherol (vitamin E). PMID:11052738

  1. Probing mechanical properties of fully hydrated gels and biological tissues.

    PubMed

    Constantinides, Georgios; Kalcioglu, Z Ilke; McFarland, Meredith; Smith, James F; Van Vliet, Krystyn J

    2008-11-14

    A longstanding challenge in accurate mechanical characterization of engineered and biological tissues is maintenance of both stable sample hydration and high instrument signal resolution. Here, we describe the modification of an instrumented indenter to accommodate nanomechanical characterization of biological and synthetic tissues in liquid media, and demonstrate accurate acquisition of force-displacement data that can be used to extract viscoelastoplastic properties of hydrated gels and tissues. We demonstrate the validity of this approach via elastoplastic analysis of relatively stiff, water-insensitive materials of elastic moduli E>1000 kPa (borosilicate glass and polypropylene), and then consider the viscoelastic response and representative mechanical properties of compliant, synthetic polymer hydrogels (polyacrylamide-based hydrogels of varying mol%-bis crosslinker) and biological tissues (porcine skin and liver) of E<500 kPa. Indentation responses obtained via loading/unloading hystereses and contact creep loading were highly repeatable, and the inferred E were in good agreement with available macroscopic data for all samples. As expected, increased chemical crosslinking of polyacrylamide increased stiffness (E40 kPa) and decreased creep compliance. E of porcine liver (760 kPa) and skin (222 kPa) were also within the range of macroscopic measurements reported for a limited subset of species and disease states. These data show that instrumented indentation of fully immersed samples can be reliably applied for materials spanning several orders of magnitude in stiffness (E=kPa-GPa). These capabilities are particularly important to materials design and characterization of macromolecules, cells, explanted tissues, and synthetic extracellular matrices as a function of spatial position, degree of hydration, or hydrolytic/enzymatic/corrosion reaction times. PMID:18922534

  2. Extracting accurate strain measurements in bone mechanics: A critical review of current methods.

    PubMed

    Grassi, Lorenzo; Isaksson, Hanna

    2015-10-01

    Osteoporosis related fractures are a social burden that advocates for more accurate fracture prediction methods. Mechanistic methods, e.g. finite element models, have been proposed as a tool to better predict bone mechanical behaviour and strength. However, there is little consensus about the optimal constitutive law to describe bone as a material. Extracting reliable and relevant strain data from experimental tests is of fundamental importance to better understand bone mechanical properties, and to validate numerical models. Several techniques have been used to measure strain in experimental mechanics, with substantial differences in terms of accuracy, precision, time- and length-scale. Each technique presents upsides and downsides that must be carefully evaluated when designing the experiment. Moreover, additional complexities are often encountered when applying such strain measurement techniques to bone, due to its complex composite structure. This review of literature examined the four most commonly adopted methods for strain measurements (strain gauges, fibre Bragg grating sensors, digital image correlation, and digital volume correlation), with a focus on studies with bone as a substrate material, at the organ and tissue level. For each of them the working principles, a summary of the main applications to bone mechanics at the organ- and tissue-level, and a list of pros and cons are provided. PMID:26099201

  3. Antioxidant properties of a North American ginseng extract.

    PubMed

    Kitts, D D; Wijewickreme, A N; Hu, C

    2000-01-01

    A North American ginseng extract (NAGE) containing known principle ginsenosides for Panax quinquefolius was assayed for metal chelation, affinity to scavenge DPPH-stable free radical, and peroxyl (LOO*) and hydroxyl (*OH) free radicals for the purpose of characterizing mechanisms of antioxidant activity. Dissociation constants (Kd) for NAGE to bind transition metals were in the order of Fe2+ > Cu2+ > Fe3+ and corresponded to the affinity to inhibit metal induced lipid peroxidation. In a metal-free linoleic acid emulsion, NAGE exhibited a significant (p < or = 0.05) concentration (0.01-10 mg/mL) dependent mitigation of lipid oxidation as assessed by the ammonium thiocyanate method. Similar results were obtained when NAGE was incubated in a methyl linoleate emulsion containing haemoglobin catalyst and assessed by an oxygen electrode. NAGE also showed strong DPPH radical scavenging activity up to a concentration of 1.6 mg/mL (r2 = 0.996). Similar results were obtained for scavenging of both site-specific and non site-specific *OH, using the deoxyribose assay method. Moreover, NAGE effectively inhibited the non site-specific DNA strand breakage caused by Fenton agents, and suppressed the Fenton induced oxidation of a 66 Kd soluble protein obtained from mouse brain over a concentration range of 2-40 mg/mL. These results indicate that NAGE exhibits effective antioxidant activity in both lipid and aqueous mediums by both chelation of metal ions and scavenging of free radicals. PMID:10724326

  4. Wave-Mechanical Properties of Stationary States.

    ERIC Educational Resources Information Center

    Holden, Alan

    This monograph is a review of the quantum mechanical concepts presented in two other monographs, "The Nature of Atoms" and "Bonds Between Atoms," by the same author. It is assumed the reader is familiar with these ideas. The monograph sketches only those aspects of quantum mechanics that are of most direct use in picturing and calculating the…

  5. In-vivo mechanical tissue property measurement for improved simulations

    NASA Astrophysics Data System (ADS)

    Ottensmeyer, Mark P.; Salisbury, J. Kenneth, Jr.

    2000-08-01

    Surgical training today, beyond what can be learned in didactic form or practice on animal or other models, is subject to the availability of appropriate training cases from which students can learn. This is especially true for battlefield surgery, as civilian hospitals may not expose doctors to frequent examples of relevant injuries. To provide a more uniform training experience, covering a standard suite of typical operations without relying on the misfortune of patients requiring surgery, many groups are developing computer-based surgical simulation systems. One of the current areas of development is the implementation of force and tactile (haptic) feedback in simulations. To create a model with realistic haptic feedback, knowledge of the material properties of the tissues in question is essential. While there is much data from tissue samples in vitro, the properties of living tissue in situ are mostly unknown. From the data that is available, it is clear that living tissue and tissue in vitro can have radically different mechanical properties. For this reason, our group is developing surgical tools that will be able to measure the force-displacement characteristics of a variety of tissues in living organisms. Taking these data over the range of frequencies relevant to haptic simulation provides information to extract stiffness and material damping parameters of different kinds of tissue. The tools are being designed for use during minimally invasive surgery, but will permit data to be acquired either during MIS or open procedures. Animal tests are expected to commence in early 2000, but the tools are being designed with safety considerations in mind for eventual use in humans. Data will be taken both for solid organs and for selected elements of the vasculature. These data will be used in simulation systems under development at the Center for Innovative Minimally Invasive Therapy at Massachusetts General Hospital and the Laboratory for Human and Machine Haptics

  6. Atomic Force Microscopy Measurements of the Mechanical Properties of Cell Walls on Living Bacterial Cells

    NASA Astrophysics Data System (ADS)

    Bailey, Richard; Mullin, Nic; Turner, Robert; Foster, Simon; Hobbs, Jamie

    2014-03-01

    Staphylococcus aureus is a major cause of infection in humans, including the Methicillin resistant strain, MRSA. However, very little is known about the mechanical properties of these cells. Our investigations use AFM to examine live S. aureus cells to quantify mechanical properties. These were explored using force spectroscopy with different trigger forces, allowing the properties to be extracted at different indentation depths. A value for the cell wall stiffness has been extracted, along with a second, higher value which is found upon indenting at higher forces. This higher value drops as the cells are exposed to high salt, sugar and detergent concentrations, implying that this measurement contains a contribution from the internal turgor pressure. We have monitored these properties as the cells progress through the cell cycle. Force maps were taken over the cells at different stages of the growth process to identify changes in the mechanics throughout the progression of growth and division. The effect of Oxacillin has also been studied, to better understand its mechanism of action. Finally mutant strains of S. aureus and a second species Bacillus subtilis have been used to link the mechanical properties of the cell walls with the chain lengths and substructures involved.

  7. Investigation of mechanical properties of pavement through electromagnetic techniques

    NASA Astrophysics Data System (ADS)

    Benedetto, Andrea; Tosti, Fabio; D'Amico, Fabrizio

    2014-05-01

    Ground-penetrating radar (GPR) is considered as one of the most flexible geophysical tools that can be effectively and efficiently used in many different applications. In the field of pavement engineering, GPR can cover a wide range of uses, spanning from physical to geometrical inspections of pavements. Traditionally, such inferred information are integrated with mechanical measurements from other traditional (e.g. plate bearing test) or non-destructive (e.g. falling weight deflectometer) techniques, thereby resulting, respectively, in time-consuming and low-significant measurements, or in a high use of technological resources. In this regard, the new challenge of retrieving mechanical properties of road pavements and materials from electromagnetic measurements could represent a further step towards a greater saving of economic resources. As far as concerns unpaved and bound layers it is well-known that strength and deformation properties are mostly affected, respectively, by inter-particle friction and cohesion of soil particles and aggregates, and by bitumen adhesion, whose variability is expressed by the Young modulus of elasticity. In that respect, by assuming a relationship between electromagnetic response (e.g. signal amplitudes) and bulk density of materials, a reasonable correlation between mechanical and electric properties of substructure is therefore expected. In such framework, a pulse GPR system with ground-coupled antennae, 600 MHz and 1600 MHz centre frequencies was used over a 4-m×30-m test site composed by a flexible pavement structure. The horizontal sampling resolution amounted to 2.4×10-2 m. A square regular grid mesh of 836 nodes with a 0.40-m spacing between the GPR acquisition tracks was surveyed. Accordingly, a light falling weight deflectometer (LFWD) was used for measuring the elastic modulus of pavement at each node. The setup of such instrument consisted of a 10-kg falling mass and a 100-mm loading plate so that the influence domain

  8. Mechanical Properties of Degraded PMR-15 Resin

    NASA Technical Reports Server (NTRS)

    Tsuji, Luis C.; McManus, Hugh L.; Bowles, Kenneth J.

    1998-01-01

    Thermo-oxidative aging produces a non-uniform degradation state in PMR-15 resin. A surface layer, usually attributed to oxidative degradation, forms. This surface layer has different properties from the inner material. A set of material tests was designed to separate the properties of the oxidized surface layer from the properties of interior material. Test specimens were aged at 316 C in either air or nitrogen, for durations of up to 800 hours. The thickness of the oxidized surface layer in air aged specimens, and the shrinkage and Coefficient of Thermal Expansion (CTE) of nitrogen aged specimens were measured directly. Four-point-bend tests were performed to determine modulus of both the oxidized surface layer and the interior material. Bimaterial strip specimens consisting of oxidized surface material and unoxidized interior material were constructed and used to determine surface layer shrinkage and CTE. Results confirm that the surface layer and core materials have substantially different properties.

  9. Local mechanical properties of the head articulation cuticle in the beetle Pachnoda marginata (Coleoptera, Scarabaeidae).

    PubMed

    Barbakadze, N; Enders, S; Gorb, S; Arzt, E

    2006-02-01

    Insect exoskeleton (cuticle) has a broad range of mechanical properties depending on the function of a particular structure of the skeleton. Structure and mechanical properties of the specialised cuticle of insect joints remain largely unknown to date. We used scanning (SEM) and transmission electron microscopy (TEM) to obtain information about the material structure of the gula plate, the head part of the head-to-neck articulation system in the beetle Pachnoda marginata. The surface of this cuticle appears rather smooth in SEM. The fibers of the exocuticle are partly oriented almost perpendicular to the surface, which is rather unusual for arthropod cuticle. Nanoindentation experiments were performed to determine the local mechanical properties (hardness and elastic modulus) of the gula material. To understand the effect of desiccation and the influence of an outer wax layer on the mechanical behavior of the material, the samples were tested in fresh, dry and chemically treated (lipid extraction in organic solvents) conditions. Nanoindentation results were found to be strongly influenced by desiccation but only slightly by lipid extraction. Decreasing water content ( approximately 15-20% of the cuticle mass) led to an increase in hardness (from 0.1 to 0.49 GPa) and elastic modulus (from 1.5 to 7.5 GPa). The lipid extraction caused a slight further hardening (to 0.52 GPa) as well as stiffening (to 7.7 GPa) of the material. The results are discussed in relation to the mechanical function of the gula plate. PMID:16449566

  10. In vitro antioxidant properties and anthocyanin compositions of elderberry extracts.

    PubMed

    Duymuş, Hale Gamze; Göger, Fatih; Başer, K Hüsnü Can

    2014-07-15

    In this study, dried elderberry fruits growing wild in Turkey were macerated using different solvents and an infusion was prepared according to traditional methods. All extracts were investigated for their total phenolic content, total monomeric anthocyanins, qualitative-quantitative determination of cyanidin-3-glucoside (by HPLC-UV analysis), anthocyanin compositions (by LC/MS-MS), free radical scavenging activity (DPPH and ABTS) and inhibition of β-carotene/linoleic acid co-oxidation. An extract with 70% ethanol was found to be richer in cyanidin-3-glucoside when compared to the other extracts. The infusion was found to be as rich as the 70% ethanol extract. Ethanol and acetone extracts (both 70%) were found to be more active in the free radical activity and β-carotene bleaching assays. Water extract showed good ABTS radical scavenging activity when compared with ascorbic acid. PMID:24594162

  11. Mechanical properties of UV irradiated rat tail tendon (RTT) collagen.

    PubMed

    Sionkowska, Alina; Wess, Tim

    2004-04-01

    The mechanical properties of RTT collagen tendon before and after UV irradiation have been investigated by mechanical testing (Instron). Air-dried tendon were submitted to treatment with UV irradiation (wavelength 254 nm) for different time intervals. The changes in such mechanical properties as breaking strength and percentage elongation have been investigated. The results have shown, that the mechanical properties of the tendon were greatly affected by time of UV irradiation. Ultimate tensile strength and ultimate percentage elongation decreased after UV irradiation of the tendon. Increasing UV irradiation leads to a decrease in Young's modulus of the tendon. PMID:15178003

  12. Mechanical and physical properties of plasma-sprayed stabilized zirconia

    NASA Technical Reports Server (NTRS)

    Siemers, P. A.; Mehan, R. L.

    1983-01-01

    Physical and mechanical properties were determined for plasma-sprayed MgO- or Y2O3-stabilized ZrO2 thermal barrier coatings. Properties were determined for the ceramic coating in both the freestanding condition and as-bonded to a metal substrate. The properties of the NiCrAlY bond coating were also investigated.

  13. Evaluation of a sequential extraction process used for determining mercury binding mechanisms to coal combustion byproducts

    SciTech Connect

    James D. Noel; Pratim Biswas; Daniel E. Giammar

    2007-07-15

    This study evaluated the selectivity and effectiveness of a sequential extraction process used to determine mercury binding mechanisms to various materials that are present in coal combustion byproducts. A six-step sequential extraction process was applied to laboratory-synthesized materials with known mercury concentrations and binding mechanisms. These materials were calcite, hematite, goethite, and titanium dioxide. Fly ash from a full-scale coal-fired power plant was also investigated. The concentrations of mercury were measured using inductively coupled plasma (ICP) mass spectrometry, whereas the major elements were measured by ICP atomic emission spectrometry. The materials were characterized by X-ray powder diffraction and scanning electron microscopy with energy dispersive spectroscopy. The sequential extraction procedure provided information about the solid phases with which mercury was associated in the solid sample. The procedure effectively extracted mercury from the target phases. The procedure was generally selective in extracting mercury. However, some steps in the procedure extracted mercury from nontarget phases, and others resulted in mercury redistribution. Iron from hematite and goethite was only leached in the reducible and residual extraction steps. Some mercury associated with goethite was extracted in the ion exchangeable step, whereas mercury associated with hematite was extracted almost entirely in the residual step. Calcium in calcite and mercury associated with calcite were primarily removed in the acidsoluble extraction step. Titanium in titanium dioxide and mercury adsorbed onto titanium dioxide were extracted almost entirely in the residual step. 42 refs., 13 figs., 2 tabs.

  14. Phonon spectrum, mechanical and thermophysical properties of thorium carbide

    NASA Astrophysics Data System (ADS)

    Pérez Daroca, D.; Jaroszewicz, S.; Llois, A. M.; Mosca, H. O.

    2013-06-01

    In this work, we study, by means of density functional perturbation theory and the pseudopotential method, mechanical and thermophysical properties of thorium carbide. These properties are derived from the lattice dynamics in the quasi-harmonic approximation. The phonon spectrum of ThC presented in this article, to the best authors' knowledge, have not been studied, neither experimentally, nor theoretically. We compare mechanical properties, volume thermal expansion and molar specific capacities with previous results and find a very good agreement.

  15. Mechanical Properties of Degraded PMR-15 Resin

    NASA Technical Reports Server (NTRS)

    Tsuji, Luis C.

    2000-01-01

    Thermo-oxidative aging produces a nonuniform degradation state in PMR-15 resin. A surface layer, usually attributed to oxidative degradation, forms. This surface layer has different properties from the inner material. A set of material tests was designed to separate the properties of the oxidized surface layer from the properties of interior material. Test specimens were aged at 316 C in either air or nitrogen, for durations of up to 800 hr. The thickness of the oxidized surface layer in air aged specimens, and the shrinkage and coefficient of thermal expansion (CTE) of nitrogen aged specimens were measured directly. The nitrogen-aged specimens were assumed to have the same properties as the interior material in the air-aged specimens. Four-point-bend tests were performed to determine modulus of both the oxidized surface layer and the interior material. Bimaterial strip specimens consisting of oxidized surface material and unoxidized interior material were constructed and used to determine surface layer shrinkage and CTE. Results confirm that the surface layer and core materials have substantially different properties.

  16. A preliminary study of the mechanism of hypoglycaemic activity of Nauclea latifolia leaf ethanolic extract.

    PubMed

    Gidado, Abubakar; Ameh, Danladi A; Atawodi, Sunday E; Ibrahim, Sani

    2012-01-01

    The aim of this study was to determine the possible underlying mechanism of the hypoglycaemic activity of the ethanolic extract of Nauclea latifolia leaves in rats. The extract, glibenclamide or water was administered orally in a glucose, sucrose and maltose tolerance tests. In addition, the effect of the extract on α-glucosidase enzymes was also studied. The ethanolic extract at 200mg/kg body weight inhibited the increase in glucose level after both oral and intraperitoneal glucose loads as did glibenclamide. The extract also dose dependently inhibited both maltase and sucrase activities in vitro but not in vivo. The hypoglycaemic effect of N. latifolia leaf ethanolic extract thus appears to be most probably exerted through a mechanism similar to that of glibenclamide which is related to increased insulin release from pancreatic β-cells. PMID:22944715

  17. Lunar soil properties and soil mechanics

    NASA Technical Reports Server (NTRS)

    Mitchell, J. K.; Houston, W. N.

    1974-01-01

    The long-range objectives were to develop methods of experimentation and analysis for the determination of the physical properties and engineering behavior of lunar surface materials under in situ environmental conditions. Data for this purpose were obtained from on-site manned investigations, orbiting and softlanded spacecraft, and terrestrial simulation studies. Knowledge of lunar surface material properties are reported for the development of models for several types of lunar studies and for the investigation of lunar processes. The results have direct engineering application for manned missions to the moon.

  18. Evaluation of a sequential extraction process used for determining mercury binding mechanisms to coal combustion byproducts.

    PubMed

    Noel, James D; Biswas, Pratim; Giammar, Daniel E

    2007-07-01

    Leaching of mercury from coal combustion byproducts is a concern because of the toxicity of mercury. Leachability of mercury can be assessed by using sequential extraction procedures. Sequential extraction procedures are commonly used to determine the speciation and mobility of trace metals in solid samples and are designed to differentiate among metals bound by different mechanisms and to different solid phases. This study evaluated the selectivity and effectiveness of a sequential extraction process used to determine mercury binding mechanisms to various materials. A six-step sequential extraction process was applied to laboratory-synthesized materials with known mercury concentrations and binding mechanisms. These materials were calcite, hematite, goethite, and titanium dioxide. Fly ash from a full-scale power plant was also investigated. The concentrations of mercury were measured using inductively coupled plasma (ICP) mass spectrometry, whereas the major elements were measured by ICP atomic emission spectrometry. The materials were characterized by X-ray powder diffraction and scanning electron microscopy with energy dispersive spectroscopy. The sequential extraction procedure provided information about the solid phases with which mercury was associated in the solid sample. The procedure effectively extracted mercury from the target phases. The procedure was generally selective in extracting mercury. However, some steps in the procedure extracted mercury from nontarget phases, and others resulted in mercury redistribution. Iron from hematite and goethite was only leached in the reducible and residual extraction steps. Some mercury associated with goethite was extracted in the ion exchangeable step, whereas mercury associated with hematite was extracted almost entirely in the residual step. Calcium in calcite and mercury associated with calcite were primarily removed in the acid-soluble extraction step. Titanium in titanium dioxide and mercury adsorbed onto

  19. Fructus Ligustri Lucidi (FLL) ethanol extract increases bone mineral density and improves bone properties in growing female rats.

    PubMed

    Lyu, Ying; Feng, Xin; Zhao, Pengling; Wu, Zhenghao; Xu, Hao; Fang, Yuehui; Hou, Yangfeng; Denney, Liya; Xu, Yajun; Feng, Haotian

    2014-11-01

    Osteoporosis is a chronic disease affecting millions of people worldwide. It is generally accepted that acquisition of a high peak bone mass (PBM) early in life can reduce the risk of osteoporosis later in life. The aims of this study were to investigate the effects of Fructus Ligustri Lucidi (FLL) ethanol extract on bone mineral density and its mechanical properties in growing female rats and to explore the underlying mechanisms. The rats were given different doses of FLL extract mixed with AIN-93G formula (0.40, 0.65 and 0.90 %), and a group given AIN-93G diet treatment only was used as control. The intervention lasted for 16 weeks until the animals were about 5 months old, the time when the animals almost reach their PBM. Our results showed that FLL treatment increased bone mineral density and improved bone mechanical properties in the growing female rats in a dose-dependent manner. In addition, FLL treatment significantly decreased the serum bone-resorbing marker, CTX-I, while significantly increasing serum 25(OH)D3 and thereby increasing Ca absorption and Ca retention. Intriguingly, both in vivo and in vitro results demonstrated that FLL treatment could reduce the RANKL/OPG ratio. In conclusion, FLL ethanol extract exerted beneficial effects on peak bone mass acquisition and the improvement of bone mechanical properties by favoring Ca metabolism and decreasing the RANKL/OPG ratio. PMID:24362453

  20. Physical and mechanical properties of icebergs

    SciTech Connect

    Gammon, P.H.; Bobby, W.; Gagnon, R.E.; Russell, W.E.

    1983-05-01

    Physical and mechanical characteristics of iceberg ice were studied from samples collected near the shores of eastern Newfoundland. Although the physical characteristics show considerable diversity, iceberg ice has some common features and is generally porous, lacks significant concentrations of dissolved materials, contains internal cracks and has an irregular interlocking grain structure. A review of mechanical testing of ice was carried out and an experimental setup was devised to reduce effects of improper contact between specimen and loading apparatus. Uniaxial compressive strength for iceberg ice was determined and compared with that for lake ice. The strength of iceberg ice was higher than that of lake ice but Young's Modulus for lake ice was higher.

  1. Mechanism of electrodialytic ion transport through solvent extraction membranes

    SciTech Connect

    Moskvin, L.N.; Shmatko, A.G.; Krasnoperov, V.M.

    1987-02-01

    The authors construct a mathematical model for electrodialysis and solvent extraction via an ion-selective ion exchange membrane and accounts for the electrochemical, ion exchange, and diffusional behavior of the processes including their dependence on component concentration and current and voltage. The model is tested against experimental data for the electrodialytic transport of anionic platinum complexes of chlorides from hydrochloric acid solution through tributylphosphate membranes. The platinum concentration in the aqueous solution was determined by gamma spectroscopy obtained via platinum 191 as a radiotracer.

  2. Supramolecular Polymer Nanocomposites - Improvement of Mechanical Properties

    NASA Astrophysics Data System (ADS)

    Hinricher, Jesse; Neikirk, Colin; Priestley, Rodney

    2015-03-01

    Supramolecular polymers differ from traditional polymers in that their repeat units are connected by hydrogen bonds that can reversibly break and form under various stimuli. They can be more easily recycled than conventional materials, and their highly temperature dependent viscosities result in reduced energy consumption and processing costs. Furthermore, judicious selection of supramolecular polymer architecture and functionality allows the design of advanced materials including shape memory and self-healing materials. Supramolecular polymers have yet to see widespread use because they can't support much weight due to their inherent mechanical weakness. In order to address this issue, the mechanical strength of supramolecular polymer nanocomposites based on ureidopyrmidinone (UPy) telechelic poly(caprolactone) doped with surface activated silica nanoparticles was investigated by tensile testing and dynamic mechanical analysis. The effects of varying amounts and types of nanofiller surface functionality were investigated to glean insight into the contributions of filler-filler and filler-matrix interactions to mechanical reinforcement in supramolecular polymer nanocomposites. MRSEC NSF DMR 0819860 (PI: Prof. N. Phuan Ong) REU Site Grant: NSF DMR-1156422 (PI: Prof. Mikko Haataja)

  3. Metal binding properties of extracellular polymeric substances extracted from anaerobic granular sludges.

    PubMed

    d'Abzac, Paul; Bordas, François; Joussein, Emmanuel; van Hullebusch, Eric D; Lens, Piet N L; Guibaud, Gilles

    2013-07-01

    Extracellular polymeric substances (EPS) were extracted from four anaerobic granular sludges with different procedures to study their involvement in biosorption of metallic elements. EPS extracts are composed of closely associated organic and mineral fractions. The EPS macromolecules (proteins, polysaccharides, humic-like substances, nucleic, and uronic acids) have functional groups potentially available for the binding of metallic elements. The acidic constants of these ionizable groups are: pKa1 (4-5) corresponding to the carboxyl groups; pKa2 (6-7) corresponding to the phosphoric groups; pKa3 (8-10) and pKa4 (≈10) corresponding to the phenolic, hydroxyl, and amino groups. The polarographic study confirms the higher affinity of the EPS to bind to lead than to cadmium. Moreover, the binding of these metallic compounds with the EPS is a mix of several sorption mechanisms including surface complexation, ion exchange, and flocculation. Inorganic elements were found as ions linked to organic molecules or as solid particles. The mineral fraction affects the binding properties of the EPS, as the presence of salts decreases the EPS binding ability. Calcite and apatite particles observed on SEM images of EPS extracts can also sorb metallic elements through ion exchange or surface complexation. PMID:23250729

  4. Composite propellant technology research: Mechanical property characterization

    NASA Technical Reports Server (NTRS)

    Bower, Mark V.

    1991-01-01

    Proof for the existence of a single Poisson's ratio function in isotropic linear viscoelastic materials is presented. An in-depth discussion is given of three dimensional viscoelastic material properties and their relationships to linear isotropic and orthotropic viscoelastic materials. A discussion of the alternate invariant definition as used by Abaqus and how it relates to the form used by Dr. S. Peng is presented.

  5. Pectin from Abelmoschus esculentus: optimization of extraction and rheological properties.

    PubMed

    Chen, Yi; Zhang, Jian-Guo; Sun, Han-Ju; Wei, Zhao-Jun

    2014-09-01

    Response surface methodology (RSM) was applied to optimize the parameters of pectin extraction from okra pods. The extracted okra pectin was then investigated by steady-shear and oscillatory rheological measurements. Statistical analysis showed that the linear term of the liquid-solid ratio, the quadratic term of the pH, and the linear term of the extraction time showed highly significant effects on pectin yield. The optimal extraction conditions that maximized the pectin yield within the experimental range of the variables researched were a pH of 3.9, an extraction time of 64 min, an extraction temperature of 60°C, and a liquid-solid ratio of 42:1. Under these conditions, the pectin yield was predicted to be 2.71%. At a liquid-solid ratio less than 2.5% w/w in aqueous solution, the pectin extracted from okra presented non-Newtonian shear-thinning behavior and could be well described by the Cross model. The okra pectin showed predominantly viscous responses (G'

  6. Toxicity and properties of the extract from Sarcocystis cruzi cysts.

    PubMed

    Saito, M; Taguchi, K; Shibata, Y; Kobayashi, T; Shimura, K; Itagaki, H

    1995-12-01

    The extract from Sarcocystis cruzi cysts in bovine muscle was subcutaneously injected to mice, guinea pigs, chickens, and rabbits to detect its toxicity. Only rabbits showed reactions after administration of the extract at a dose of 25 micrograms. The main clinical signs of the rabbits were depression, reduction in body temperature and intermittent diarrhea and the hematological findings observed were elevation in WBC, RBC, PCV, TP, BUN, AST, AUT and creatinine values and reduction in glucose, K+ and pH of blood. The extract, crude toxin, was a water soluble, acid-alkali stable and thermolabile protein and estimated to be a molecular mass of 15-16 kd. PMID:8720045

  7. Mechanical properties of different types of space maintainers

    NASA Astrophysics Data System (ADS)

    Beldiman, M.-A.; Mârţu, I.; Leiţoiu, B.; Luchian, I.; Lupescu, O.; Bârcă, E. S.

    2015-11-01

    Currently, inside the oral cavity, the dental space maintainers are subjected to forces exerted on them when performing various functions; therefore, it is important to know how each of these mechanisms behave and respond to forces that are applied directly to them. The mechanical properties of the materials used in dentistry are defined by a set of characteristics representing the behaviour of their particular working conditions and it is qualitatively expressed by a number of parameters.The study aimed to determine the pressing force that can be taken by four 4 types of space maintainers frequently used in practice - fixed and removable, applied on four samples realized with human teeth extracted for orthodontic purposes. Static tests were carried out on a machine type short WDW-5 EC with a maximum force of 5 kN and a loading speed of 5 mm/min by a special testing machine, with an innovative appliance; data recording was automatically performed, using a computer with a special program that present the specific diagrams. Experimental determinations included the following aspects: to determine the maximum force that can be supported by each sample, and to observe the deformations. The values obtained indicate that the best option in terms of behavior under the conditions specified is the removable appliance, and the less functional version is the fixed space maintainer using brackets. According to tests conducted, the fracture strength was found to be more important for fixed space maintainers (band and loop, for example) so, in practice is using more frequent these types of space maintainers.

  8. Probing the mechanical properties of dental porcelain through nanoindentation

    NASA Astrophysics Data System (ADS)

    Manda, Marianthi; Moschakis, Nikolaos; Konstantinidis, Avraam; Christophilos, Demetrios; Papadopoulou, Lambrini; Koidis, Petros; Aifantis, Elias

    2012-11-01

    The purpose of this short communication is to report on some micro/nanoscale aspects of the mechanical behavior of dental porcelain. Specimens were characterized by micro-Raman spectroscopy and scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS). Massive nanoindentation experiments on the surface of the specimens were performed, and typical load-displacement or load-depth (P-h) curves were obtained, which in turn were used to determine the Young modulus (E) and nanoindentation hardness (n-H), based on the Oliver-Pharr method [1]. Statistical analyses were carried out to determine the Spearman’s rank correlation coefficient (Spearman’s ρ), along with non-parametric linear regression analysis by employing Kolmogorov-Smirnov and Two-Step Cluster tests. Densification due to grain boundary diffusion and open-pore elimination was revealed by SEM. EDS analysis indicated a leucite-dispersed silicate glass matrix, as well as its contamination by traces of other minerals. Raman spectroscopy supported the EDS assignments. The P-h curves suggested that inelastic deformation and material flow increases at larger depths. Spearman’s ρ value showed strong dependence of E and n-H on h, indicating the occurrence of a size effect. The logarithmic data of E and n-H as functions of h were fitted by using linear regression analysis. The data did not obey a normal distribution (as the Kolmogorov-Smirnov test showed) due to the chemical heterogeneity involved. The Two-Step Cluster analysis indicated clustering in four groups associated with the chemical heterogeneity of the surface. Similar works using nanoindentation to determine the mechanical properties of dental materials can be found, for example, in [2, 3]. Corresponding methods for extracting the values of E and n-H from P-h experimental curves can be found, for example, in [4-6].

  9. [Estimations of mechanical properties of bones using nanoindentation].

    PubMed

    Sakamoto, Makoto

    2016-01-01

    Nanoindentation has been applied in recent years to measure the mechanical properties of bone tissues at a microscopic scale, overcoming the limitations of traditional mechanical testing techniques for small samples. This method is precise and accurate and appears well suited for measuring mechanical properties in bone. Dynamic nanoindentation is also a promising method of measuring the viscoelastic properties of bone tissues at smaller length and load scales than allowed by other testing methods, thus allowing individual constituents and local regions of inhomogeneous tissues to be characterized individually. This article describes our nanoindentation studies of bone tissues with recent studies. PMID:26728534

  10. Mechanical properties of intermediate filament proteins

    PubMed Central

    Charrier, Elisabeth E.; Janmey, Paul A.

    2016-01-01

    Purified intermediate filament proteins can be reassembled in vitro to produce polymers closely resembling those found in cells, and these filament form viscoelastic gels. The crosslinks holding IFs together in the network include specific bonds between polypeptides extending from the filament surface and ionic interactions mediated by divalent cations. IF networks exhibit striking non-linear elasticity with stiffness, as quantified by shear modulus, increasing an order of magnitude as the networks are deformed to large stains resembling those that soft tissues undergo in vivo. Individual Ifs can be stretched to more than 2 or 3 times their resting length without breaking. At least ten different rheometric methods have been used to quantify the viscoelasticity of IF networks over a wide range of timescales and strain magnitudes. The mechanical roles of different classes of IF on mesenchymal and epithelial cells in culture have also been studied by an even wider range of microrheological methods. These studies have documented the effects on cell mechanics when IFs are genetically or pharmacologically disrupted or when normal or mutant IF proteins are exogenously expressed in cells. Consistent with in vitro rheology, the mechanical role of IFs is more apparent as cells are subjected to larger and more frequent deformations. PMID:26795466

  11. Mechanical Properties of Intermediate Filament Proteins.

    PubMed

    Charrier, Elisabeth E; Janmey, Paul A

    2016-01-01

    Purified intermediate filament (IF) proteins can be reassembled in vitro to produce polymers closely resembling those found in cells, and these filaments form viscoelastic gels. The cross-links holding IFs together in the network include specific bonds between polypeptides extending from the filament surface and ionic interactions mediated by divalent cations. IF networks exhibit striking nonlinear elasticity with stiffness, as quantified by shear modulus, increasing an order of magnitude as the networks are deformed to large strains resembling those that soft tissues undergo in vivo. Individual IFs can be stretched to more than two or three times their resting length without breaking. At least 10 different rheometric methods have been used to quantify the viscoelasticity of IF networks over a wide range of timescales and strain magnitudes. The mechanical roles of different classes of cytoplasmic IFs on mesenchymal and epithelial cells in culture have also been studied by an even wider range of microrheological methods. These studies have documented the effects on cell mechanics when IFs are genetically or pharmacologically disrupted or when normal or mutant IF proteins are exogenously expressed in cells. Consistent with in vitro rheology, the mechanical role of IFs is more apparent as cells are subjected to larger and more frequent deformations. PMID:26795466

  12. Mechanical properties and morphology of polymer gels

    NASA Astrophysics Data System (ADS)

    Sliozberg, Yelena; Sirk, Timothy; Brennan, John; Andzelm, Jan; Mrozek, Randy; Lenhart, Joseph

    2012-02-01

    Understanding morphology and mechanical response of polymeric gels is of particular importance to design materials with required energy dissipation characteristics. We will present our latest results for polymer gels based on 1) self-assembled block copolymers and 2) chemically cross-linked polymers. The dissipative particle dynamics (DPD) was used to predict morphology in good agreement with atomic force microscopy. We have performed DPD non-equilibrium oscillatory shear calculations predicting elastic modulus of unentangled gels that correlates well with experimental rheology data. However, this methodology fails to predict mechanics of entangled polymer networks due to unphysical chain crossing brought by the soft potentials used in DPD simulations. Recently, we have introduced an improved segmental repulsion potential that removes the bond crossing allowing for reptation dynamics. The improved DPD method was used in simulations for entangled gels to explore impact of branched architecture of solvent on the mechanical response to the tensile deformation. Novel architectures of solvent resulting in a dramatic increase of the elastic modulus were identified. The topological analysis was applied to understand contributions of chemical cross-links and entanglements to the stress.

  13. Mechanical properties of alumina porcelain during heating

    NASA Astrophysics Data System (ADS)

    Šín, Peter; Podoba, Rudolf; ŠtubÅa, Igor; Trník, Anton

    2014-11-01

    The mechanical strength and Young's modulus of green alumina porcelain (50 wt. % of kaolin, 25 wt. % of Al2O3, and 25 wt. % of feldspar) were measured during heating up to 900 °C and 1100 °C, respectively. To this end, we used the three point-bending method and modulated force thermomechanical analysis (mf-TMA). The loss liberation - of the physically bound water (20 - 250 °C) strengthens the sample and Young's modulus increases its values significantly. The dehydroxylation that takes place in the range of 400 - 650 °C causes a slight decrease in Young's modulus. On the other hand, the mechanical strength slightly increases in this temperature range, although it has a sudden drop at 420 °C. Beyond the dehydroxylation range, above 650 °C, both Young's modulus and mechanical strength increase. Above 950 °C, a sharp increase of Young's modulus is caused by the solid-state sintering and the new structure created by the high-temperature reactions in metakaolinite.

  14. Properties of herbal extracts against Propionibacterium acnes for biomedical application

    NASA Astrophysics Data System (ADS)

    Lim, Youn-Mook; Kim, Sung Eun; Kim, Yong Soo; Shin, Young Min; Jeong, Sung In; Jo, Sun-Young; Gwon, Hui-Jeong; Park, Jong-seok; Nho, Young-Chang; Kim, Jong-Cheol; Kim, Seong-Jang; Shin, HeungSoo

    2012-10-01

    Propionibacterium acnes (P. acnes), one of the anaerobic bacterium, causes inflammatory acne. To find a novel medication for treating the inflammation caused by P. acnes, we investigated the anti-bacterial and anti-inflammatory activities of several herbal extracts against P. acnes. The aqueous extracts from five dried herbs, Phellodendron amurense Rupr., Paeonia lactiflora Pallas., Houttuynia cordata Thunb., Agrimonia pilosa Ledeb. and Glycyrrhiza uralensis Fisch., were prepared and mixed. In this experiment, 1 mg/ml of the herbal extract mixture caused a decrease in the growth of P. acnes and reduced the production of pro-inflammatory cytokines, TNF-α, IL-8, IL-1β and IL-6, in human monocytic THP-1 cells treated with heat-killed P. acnes. Therefore, this herbal extract mixture may possess both anti-bacterial and anti-inflammatory activities against P. acnes and can be a novel therapeutic agent for treating inflammatory acne.

  15. Mechanical Properties of the Frog Sarcolemma

    PubMed Central

    Fields, R. Wayne

    1970-01-01

    The elastic properties of cylindrical segments of sarcolemma were studied in single striated fibers of the frog semitendinosus muscle. All measurements were made on membranes of retraction zones, cell segments from which the sarcoplasm had retracted. Quantitative morphological studies indicated that three deforming forces interact with the intrinsic elastic properties of the sarcolemma to determine membrane configuration in retraction zone segments. The three deforming forces, namely intrazone pressure, axial fiber loads, and radial stresses introduced by retracted cell contents, could all be experimentally removed, permitting determination of the “undeformed” configuration of the sarcolemma. Analysis of these results indicated that membrane of intact fibers at rest length is about four times as wide and two-thirds as long as undeformed membrane. Membrane geometry was also studied as a function of internal hydrostatic pressure and axial loading to permit calculation of the circumferential and longitudinal tension-strain (T-S) diagrams. The sarcolemma exhibited nonlinear T-S properties concave to the tension axis in both directions. Circumferential T-S slopes (measures of membrane stiffness) ranged from 1500 to greater than 50,000 dynes/cm over the range of deformations investigated, while longitudinal T-S slopes varied from 23,000 to 225,000 dynes/cm. Thus, the membrane is anisotropic, being much stiffer in the longitudinal direction. Certain ramifications of the present results are discussed in relation to previous biomechanical studies of the sarcolemma and of other tissues. ImagesFigure 2Figure 3Figure 4 PMID:5439320

  16. The mechanical and strength properties of diamond

    NASA Astrophysics Data System (ADS)

    Field, J. E.

    2012-12-01

    Diamond is an exciting material with many outstanding properties; see, for example Field J E (ed) 1979 The Properties of Diamond (London: Academic) and Field J E (ed) 1992 The Properties of Natural and Synthetic Diamond (London: Academic). It is pre-eminent as a gemstone, an industrial tool and as a material for solid state research. Since natural diamonds grew deep below the Earth's surface before their ejection to mineable levels, they also contain valuable information for geologists. The key to many of diamond's properties is the rigidity of its structure which explains, for example, its exceptional hardness and its high thermal conductivity. Since 1953, it has been possible to grow synthetic diamond. Before then, it was effectively only possible to have natural diamond, with a small number of these found in the vicinity of meteorite impacts. Techniques are now available to grow gem quality synthetic diamonds greater than 1 carat (0.2 g) using high temperatures and pressures (HTHP) similar to those found in nature. However, the costs are high, and the largest commercially available industrial diamonds are about 0.01 carat in weight or about 1 mm in linear dimension. The bulk of synthetic diamonds used industrially are 600 µm or less. Over 75% of diamond used for industrial purposes today is synthetic material. In recent years, there have been two significant developments. The first is the production of composites based on diamond; these materials have a significantly greater toughness than diamond while still maintaining very high hardness and reasonable thermal conductivity. The second is the production at low pressures by metastable growth using chemical vapour deposition techniques. Deposition onto non-diamond substrates was first demonstrated by Spitsyn et al 1981 J. Cryst. Growth 52 219-26 and confirmed by Matsumoto et al 1982 Japan J. Appl. Phys. 21 L183-5. These developments have added further to the versatility of diamond. Two other groups of materials

  17. The mechanical and strength properties of diamond.

    PubMed

    Field, J E

    2012-12-01

    Diamond is an exciting material with many outstanding properties; see, for example Field J E (ed) 1979 The Properties of Diamond (London: Academic) and Field J E (ed) 1992 The Properties of Natural and Synthetic Diamond (London: Academic). It is pre-eminent as a gemstone, an industrial tool and as a material for solid state research. Since natural diamonds grew deep below the Earth's surface before their ejection to mineable levels, they also contain valuable information for geologists. The key to many of diamond's properties is the rigidity of its structure which explains, for example, its exceptional hardness and its high thermal conductivity. Since 1953, it has been possible to grow synthetic diamond. Before then, it was effectively only possible to have natural diamond, with a small number of these found in the vicinity of meteorite impacts. Techniques are now available to grow gem quality synthetic diamonds greater than 1 carat (0.2 g) using high temperatures and pressures (HTHP) similar to those found in nature. However, the costs are high, and the largest commercially available industrial diamonds are about 0.01 carat in weight or about 1 mm in linear dimension. The bulk of synthetic diamonds used industrially are 600 µm or less. Over 75% of diamond used for industrial purposes today is synthetic material. In recent years, there have been two significant developments. The first is the production of composites based on diamond; these materials have a significantly greater toughness than diamond while still maintaining very high hardness and reasonable thermal conductivity. The second is the production at low pressures by metastable growth using chemical vapour deposition techniques. Deposition onto non-diamond substrates was first demonstrated by Spitsyn et al 1981 J. Cryst. Growth 52 219-26 and confirmed by Matsumoto et al 1982 Japan J. Appl. Phys. 21 L183-5. These developments have added further to the versatility of diamond. Two other groups of

  18. [Plant extracts with cytostatic properties growing in Cuba. II].

    PubMed

    Lopez Abraham, A M; Rojas Hernandez, N M; Jimenez Misas, C A

    1979-01-01

    The study of the cytostatic activity of aqueous, alcoholic and ketonic extracts from 18 parts of 9 species of superior plants of the families Araceae, Borraginacease, Burseraceae, Cesalpinaceae, Meliaceae, Compositae, Rebiaceae, Cruciferaceae and Verbenaceae using the microbiologic method of described by Kubas in 1972 is pursued. The best results were obtained from Hamelia patens. Lippia alba, Lepidium virginicum, Cassia ligustrina, Bursera simaruba and Heliotropium campechianum extracts. PMID:161406

  19. Analysis on the Physicochemical Properties of Ginkgo biloba Leaves after Enzymolysis Based Ultrasound Extraction and Soxhlet Extraction.

    PubMed

    Zhang, Chang-Wei; Wang, Cheng-Zhang; Tao, Ran

    2016-01-01

    In this study, high performance liquid chromatography (HPLC), ultraviolet (UV), thermagravimetric analyzer (TGA), pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS), and scanning electron microscope (SEM) were used as measurement techniques, contents of chemical composition, pyrolytic products, thermal stability, morphological characterization of Ginkgo biloba leaves (GBL) acted as the index, and physicochemical properties of GBL after enzymolysis based ultrasound extraction (EBUE) and Soxhlet extraction were studied. The detection results of chemical composition revealed that contents of general flavone, soluble protein, soluble total sugar and protein in the GBL declined significantly after EBUE, and contents of polyprenols and crude fat obviously reduced as well after Soxhlet extraction. Py-GC-MS results indicated that total GC contents of micromolecules with carbon less than 12 from 54.0% before EBUE decline to 8.34% after EBUE. Total GC contents of long-chain fatty acids with carbon less than 20 from 43.0% before EBUE reduced to 27.0% after Soxhlet extraction. Thermal stability results showed that GBL after Soxhlet extraction was easier to decompose than GBL before EBUE. SEM results illustrated that surface structure of GBL was damaged severely after EBUE, compared with GBL before EBUE, while organic solvent extraction had little influence on the morphological characterization of GBL after Soxhlet extraction compared with GBL after EBUE. PMID:26784159

  20. Antioxidant properties of Berberis aetnensis C. Presl (Berberidaceae) roots extract and protective effects on astroglial cell cultures.

    PubMed

    Campisi, Agata; Acquaviva, Rosaria; Bonfanti, Roberta; Raciti, Giuseppina; Amodeo, Andrea; Mastrojeni, Silvana; Ragusa, Salvatore; Iauk, Liliana

    2014-01-01

    Berberis aetnensis C. Presl (Berberidaceae) is a bushy-spiny shrub common on Mount Etna (Sicily). We demonstrated that the alkaloid extract of roots of B. aetnensis C. Presl contains prevalently berberine and berbamine, possesses antimicrobial properties, and was able to counteract the upregulation evoked by glutamate of tissue transglutaminase in primary rat astroglial cell cultures. Until now, there are no reports regarding antioxidant properties of B. aetnensis C. Presl collected in Sicily. Air-dried, powdered roots of B. aetnensis C. Presl were extracted, identified, and quantified by HPLC. We assessed in cellular free system its effect on superoxide anion, radicals scavenging activity of antioxidants against free radicals like the 1,1-diphenyl-2-picrylhydrazyl radical, and the inhibition of xanthine oxidase activity. In primary rat astroglial cell cultures, exposed to glutamate, we evaluated the effect of the extract on glutathione levels and on intracellular production of reactive oxygen species generated by glutamate. The alkaloid extract of B. aetnensis C. Presl inhibited superoxide anion, restored to control values, the decrease of GSH levels, and the production of reactive oxygen species. Potent antioxidant activities of the alkaloid extract of roots of B. aetnensis C. Presl may be one of the mechanisms by which the extract is effective against health disorders associated to oxidative stress. PMID:25177720

  1. Mechanical Properties of Austenitic Stainless Steel Made by Additive Manufacturing

    PubMed Central

    Luecke, William E; Slotwinski, John A

    2014-01-01

    Using uniaxial tensile and hardness testing, we evaluated the variability and anisotropy of the mechanical properties of an austenitic stainless steel, UNS S17400, manufactured by an additive process, selective laser melting. Like wrought materials, the mechanical properties depend on the orientation introduced by the processing. The recommended stress-relief heat treatment increases the tensile strength, reduces the yield strength, and decreases the extent of the discontinuous yielding. The mechanical properties, assessed by hardness, are very uniform across the build plate, but the stress-relief heat treatment introduced a small non-uniformity that had no correlation to position on the build plate. Analysis of the mechanical property behavior resulted in four conclusions. (1) The within-build and build-to-build tensile properties of the UNS S17400 stainless steel are less repeatable than mature engineering structural alloys, but similar to other structural alloys made by additive manufacturing. (2) The anisotropy of the mechanical properties of the UNS S17400 material of this study is larger than that of mature structural alloys, but is similar to other structural alloys made by additive manufacturing. (3) The tensile mechanical properties of the UNS S17400 material fabricated by selective laser melting are very different from those of wrought, heat-treated 17-4PH stainless steel. (4) The large discontinuous yielding strain in all tests resulted from the formation and propagation of Lüders bands. PMID:26601037

  2. Mechanical Properties of Austenitic Stainless Steel Made by Additive Manufacturing.

    PubMed

    Luecke, William E; Slotwinski, John A

    2014-01-01

    Using uniaxial tensile and hardness testing, we evaluated the variability and anisotropy of the mechanical properties of an austenitic stainless steel, UNS S17400, manufactured by an additive process, selective laser melting. Like wrought materials, the mechanical properties depend on the orientation introduced by the processing. The recommended stress-relief heat treatment increases the tensile strength, reduces the yield strength, and decreases the extent of the discontinuous yielding. The mechanical properties, assessed by hardness, are very uniform across the build plate, but the stress-relief heat treatment introduced a small non-uniformity that had no correlation to position on the build plate. Analysis of the mechanical property behavior resulted in four conclusions. (1) The within-build and build-to-build tensile properties of the UNS S17400 stainless steel are less repeatable than mature engineering structural alloys, but similar to other structural alloys made by additive manufacturing. (2) The anisotropy of the mechanical properties of the UNS S17400 material of this study is larger than that of mature structural alloys, but is similar to other structural alloys made by additive manufacturing. (3) The tensile mechanical properties of the UNS S17400 material fabricated by selective laser melting are very different from those of wrought, heat-treated 17-4PH stainless steel. (4) The large discontinuous yielding strain in all tests resulted from the formation and propagation of Lüders bands. PMID:26601037

  3. Porosity and mechanical properties of zirconium ceramics

    SciTech Connect

    Kalatur, Ekaterina Narikovich, Anton; Buyakova, Svetlana E-mail: kulkov@ispms.tsc.ru; Kulkov, Sergey E-mail: kulkov@ispms.tsc.ru

    2014-11-14

    The article studies the porous ceramics consisting of ultra-fine ZrO{sub 2} powders. The porosity of ceramic samples varied from 15% to 80%. The structure of the ceramic materials had a cellular configuration. The distinctive feature of all experimentally obtained strain diagrams is their nonlinearity at low deformations characterized by the parabolic law. It was shown that the observed nonlinear elasticity for low deformations shown in strain diagrams is due to the mechanical instability of cellular elements of the ceramic framework.

  4. Interfaces with Tunable Mechanical and Radiosensitizing Properties.

    PubMed

    Berg, Nora G; Pearce, Brady L; Snyder, Patrick J; Rohrbaugh, Nathaniel; Nolan, Michael W; Adhikari, Prajesh; Khan, Saad A; Ivanisevic, Albena

    2016-08-31

    We report the fabrication of a composite containing nanostructured GaOOH and Matrigel with tunable radiosensitizing and stiffness properties. Composite characterization was done with microscopy and rheology. The utility of the interface was tested in vitro using fibroblasts. Cell viability and reactive oxygen species assays quantified the effects of radiation dosages and GaOOH concentrations. Fibroblasts' viability decreased with increasing concentration of GaOOH and composite stiffness. During ionizing radiation experiments the presence of the scintillating GaOOH triggered a different cellular response. Reactive oxygen species data demonstrated that one can reduce the amount of radiation needed to modulate the behavior of cells on interfaces with different stiffness containing a radiosensitizing material. PMID:26882455

  5. Characterising Mechanical Properties of Braided and Woven Textile Composite Beams

    NASA Astrophysics Data System (ADS)

    Dauda, Benjamin; Oyadiji, S. Olutunde; Potluri, Prasad

    2009-02-01

    The focus of this paper is on the manufacture of textile composite beams and on the determination of their mechanical properties. This includes investigating the effects of fibre orientation on the mechanical properties of braided and woven textile composites. Composites were manufactured from nominally identical constituents and identical consolidation processes, leaving as the only variables, variations caused by the different fibre architecture of the preform. The repeatability and, hence, reliability of this approach is demonstrated. Results obtained show that fibre architecture affects composite strength and extensibility. Composites with woven preforms are practically linear up to catastrophic failure while composites with braided preforms exhibit non-linearity prior to failure. Also the mechanical properties of the textile composite beams were determined. Results show that by tailoring the braid angle and pick density of braided and woven composite performs, the mechanical properties of the composite beams can be controlled to suit end-use requirement.

  6. Tailoring of mechanical properties of hydroformed aluminum tubes

    SciTech Connect

    Hong, Sung-tae; Lavender, Curt A.

    2007-07-06

    Tailoring of the mechanical properties of hydroformed aluminum 6063-T4 tubes to those of aluminum 6063-T6 was performed by heat treatment. Quasi-static tensile tests and a SEM analysis were conducted to evaluate the change of the mechanical properties. The experimental results of the hydroformed tubes in T4 condition (before the heat treatment) show significant variations of the mechanical properties along the length due to the different extents of work hardening by hydroforming. The experimental results of the hydroformed tubes in T6 condition (after the heat treatment) show that the precipitation hardening successfully removed the effects of the non-uniform work hardening and resulted in the uniform mechanical properties in the tube.

  7. Study of the effect of gamma irradiation on a commercial polycyclooctene I. Thermal and mechanical properties

    NASA Astrophysics Data System (ADS)

    García-Huete, N.; Laza, J. M.; Cuevas, J. M.; Vilas, J. L.; Bilbao, E.; León, L. M.

    2014-09-01

    A gamma radiation process for modification of commercial polymers is a widely applied technique to promote new physical, chemical and mechanical properties. Gamma irradiation originates free radicals able to induce chain scission or recombination of radicals, which induces annihilation, branching or crosslinking processes. The aim of this work is to research the structural, thermal and mechanical changes induced on a commercial polycyclooctene (PCO) when it is irradiated with a gamma source of 60Co at different doses (25-200 kGy). After gamma irradiation, gel content was determined by Soxhlet extraction in cyclohexane. Furthermore, thermal properties were evaluated before and after Soxhlet extraction by means of Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC), as well as mechanical properties were measured by Dynamic Mechanical Thermal Analysis (DMTA). The results showed the variations of the properties depending on the irradiation dose. Finally, a first approach to evaluate qualitatively the shape memory behaviour of all irradiated PCO samples was performed by a visually monitoring shape recovery process.

  8. Processing effects on the mechanical properties of tungsten heavy alloys

    NASA Technical Reports Server (NTRS)

    Kishi, Toshihito; German, R. M.

    1990-01-01

    Tungsten heavy alloys exhibit significant mechanical property sensitivities to the fabrication variables. These sensitivities are illustrated in this examination of vacuum sintering and the effects of composition, sintering temperature, and sintering time on the mechanical properties of tungsten heavy alloys. Measurements were conducted to assess the density, strength, hardness, and elongation dependencies. A detrimental aspect of vacuum sintering is matrix phase evaporation, although vacuum sintering does eliminate the need for postsintering heat treatments.

  9. Primate dietary ecology in the context of food mechanical properties.

    PubMed

    Coiner-Collier, Susan; Scott, Robert S; Chalk-Wilayto, Janine; Cheyne, Susan M; Constantino, Paul; Dominy, Nathaniel J; Elgart, Alison A; Glowacka, Halszka; Loyola, Laura C; Ossi-Lupo, Kerry; Raguet-Schofield, Melissa; Talebi, Mauricio G; Sala, Enrico A; Sieradzy, Pawel; Taylor, Andrea B; Vinyard, Christopher J; Wright, Barth W; Yamashita, Nayuta; Lucas, Peter W; Vogel, Erin R

    2016-09-01

    Substantial variation exists in the mechanical properties of foods consumed by primate species. This variation is known to influence food selection and ingestion among non-human primates, yet no large-scale comparative study has examined the relationships between food mechanical properties and feeding strategies. Here, we present comparative data on the Young's modulus and fracture toughness of natural foods in the diets of 31 primate species. We use these data to examine the relationships between food mechanical properties and dietary quality, body mass, and feeding time. We also examine the relationship between food mechanical properties and categorical concepts of diet that are often used to infer food mechanical properties. We found that traditional dietary categories, such as folivory and frugivory, did not faithfully track food mechanical properties. Additionally, our estimate of dietary quality was not significantly correlated with either toughness or Young's modulus. We found a complex relationship among food mechanical properties, body mass, and feeding time, with a potential interaction between median toughness and body mass. The relationship between mean toughness and feeding time is straightforward: feeding time increases as toughness increases. However, when considering median toughness, the relationship with feeding time may depend upon body mass, such that smaller primates increase their feeding time in response to an increase in median dietary toughness, whereas larger primates may feed for shorter periods of time as toughness increases. Our results emphasize the need for additional studies quantifying the mechanical and chemical properties of primate diets so that they may be meaningfully compared to research on feeding behavior and jaw morphology. PMID:27542555

  10. Structure, mechanical properties, and fracture of 20GL cast steel

    NASA Astrophysics Data System (ADS)

    Schastlivtsev, V. M.; Tabatchikova, T. I.; Yakovleva, I. L.; Klyueva, S. Yu.

    2014-04-01

    The structure and mechanical properties of 20GL steel are studied. It is shown that a significant decrease in the ductility and impact toughness of the steel is caused by intercrystalline fracture, which is induced by a weakening of the intercrystallite bonds due to the existence of coarse lamellar pearlite and nonmetallic inclusions, namely, film inclusions and eutectic-type oxysulfides, at the boundaries of primary crystals. Annealing from a temperature in the intercritical range is found to improve the mechanical properties.

  11. Mechanical properties of hydroxyapatite/mica composite.

    PubMed

    Nordström, E G; Herø, H; Jørgensen, R B

    1994-01-01

    Bend specimens of the inorganic synthetic materials hydroxyapatite (HA) and a composite of hydroxyapatite/muscovite mica have been prepared and tested mechanically. Sintering followed by hot isostatic pressing (HIP) without encapsulation gave an increased strength for HA alone, but no significant increase in strength compared with sintering alone for HA/mica composites. The bend strength of the HA/mica composite was inferior to that of HA alone, the reason being inadequate bonding between HA and mica. HIP in glass capsules and an increased cold compaction pressure tended to improve the bend strength of the composite. Corrosion in tris for 7 d did not affect the bend strength of the investigated materials significantly. PMID:7950878

  12. The Antioxidant Mechanisms Underlying the Aged Garlic Extract- and S-Allylcysteine-Induced Protection

    PubMed Central

    Colín-González, Ana L.; Santana, Ricardo A.; Silva-Islas, Carlos A.; Chánez-Cárdenas, Maria E.; Santamaría, Abel; Maldonado, Perla D.

    2012-01-01

    Aged garlic extract (AGE) is an odorless garlic preparation containing S-allylcysteine (SAC) as its most abundant compound. A large number of studies have demonstrated the antioxidant activity of AGE and SAC in both in vivo—in diverse experimental animal models associated to oxidative stress—and in vitro conditions—using several methods to scavenge reactive oxygen species or to induce oxidative damage. Derived from these experiments, the protective effects of AGE and SAC have been associated with the prevention or amelioration of oxidative stress. In this work, we reviewed different antioxidant mechanisms (scavenging of free radicals and prooxidant species, induction of antioxidant enzymes, activation of Nrf2 factor, inhibition of prooxidant enzymes, and chelating effects) involved in the protective actions of AGE and SAC, thereby emphasizing their potential use as therapeutic agents. In addition, we highlight the ability of SAC to activate Nrf2 factor—a master regulator of the cellular redox state. Here, we include original data showing the ability of SAC to activate Nrf2 factor in cerebral cortex. Therefore, we conclude that the therapeutic properties of these molecules comprise cellular and molecular mechanisms at different levels. PMID:22685624

  13. Efficient Extraction Method of the Change of Buildings for Fixed Property Investigation

    NASA Astrophysics Data System (ADS)

    Tanauchi, Y.; Chikatsu, H.

    2012-07-01

    In order to appraise fixed property, local governments in Japan annually investigate taxable buildings on January 1, but the efficiency of the investigation is an issue. With this context, change extraction methods of buildings have been studied using various data. However, labor and time optimization for change extraction methods remains an issue. With this in mind, the authors have concentrated on developing a change extraction method for buildings that uses only photomaps of two separate times. This paper describes the extraction method using color and texture, which can be obtained from photomaps. In order to evaluate effectiveness, the proposed method was investigated using photomaps of two separate times on various locations. It was confirmed that the proposed method extracted the changed buildings. It was also verified that the change of buildings cannot be extracted by color information only; rather, the change extraction of buildings was accomplished by using both color and texture. It should be noted that all changed buildings include extracted regions so that the change extraction of buildings is effectively performed without oversights. The proposed method could extract all changed buildings. In conclusion, the proposed method can reduce over-extraction of changed buildings by intensively visually checking extracted regions that have changes in color or texture rather than by visually checking all regions of photomaps. It is concluded that the proposed method has the ability to effectively extract changed buildings by using only photomaps.

  14. In Vitro Tissue Differentiation using Dynamics of Tissue Mechanical Properties

    NASA Astrophysics Data System (ADS)

    Lin, Wei-Chiang; Phillips, Paul J.

    2002-03-01

    Dynamics of tissue mechanical properties of various human tissue types were studied at macroscopic as well as microscopic level in vitro. This study was conducted to enable the development of a feedback system based on dynamics of tissue mechanical properties for intraoperative guidance for tumor treatment (e.g., RF ablation of liver tumor) and noninvasive tumor localization. Human liver tissues, including normal, cancerous, and cirrhotic tissues, were obtained from patients receiving liver transplant or tumor resection at Vanderbilt University Medical Center with the approval of the Vanderbilt Institutional Review Board. Tissue samples, once resected from the patients, were snap-frozen using liquid nitrogen and stored at -70 oC. Measurements of the mechanical properties of these tissue samples were conducted at the University of Tennessee at Knoxville. Dynamics of tissue mechanical properties were measured from both native and thermally coagulated tissue samples at macroscopic and microscopic level. Preliminary results suggest the dynamics of mechanical properties of normal liver tissues are very different from those of cancerous liver tissues. The correlation between the dynamics of mechanical properties at macroscopic level and those at microscopic level is currently under investigation.

  15. Alterations in mechanical properties are associated with prostate cancer progression.

    PubMed

    Wang, Xuejian; Wang, Jianbo; Liu, Yingxi; Zong, Huafeng; Che, Xiangyu; Zheng, Wei; Chen, Feng; Zhu, Zheng; Yang, Deyong; Song, Xishuang

    2014-03-01

    Cancer progression and metastasis have been shown to be accompanied by alterations in the mechanical properties of tissues, but the relationship between the mechanical properties and malignant behavior in prostate cancer (Pca) is less clear. The aims of this study were to detect the mechanical properties of benign prostatic hyperplasia (BPH) and Pca tissues on both the macro- and micro-scales, to explore the relationships between mechanical properties and malignant behavior and, finally, to identify the important molecules in the mechanotransduction signaling pathway. We demonstrated that the strain index of Pca tissue was significantly higher than that of BPH tissue on the macro-scale but the Young's modulus of the Pca tissues, especially in advanced Pca, was lower than that of BPH tissues on the micro-scale. These two seemingly contradictory results can be explained by the excessive proliferation of tumor cells (Ki-67) and the degradation of scaffold proteins (collagens). These data indicate that alterations of the macro- and micro-mechanical properties of Pca tissues with malignant behavior are contradictory. The mechanical properties of tissues might be useful as a new risk factor for malignancy and metastasis in Pca. Furthermore, collagens, matrix metalloproteinase, fibronectin, and integrins might be the important molecules in the mechanotransduction signaling pathway. PMID:24504844

  16. Understanding and Tailoring the Mechanical Properties of LIGA Fabricated Materials

    SciTech Connect

    Buchheit, T.E.; Christenson, T.R.; Lavan, D.A.; Schmale, D.T.

    1999-01-25

    LIGA fabricated materials and components exhibit several processing issues affecting their metallurgical and mechanical properties, potentially limiting their usefulness for MEMS applications. For example, LIGA processing by metal electrodeposition is very sensitive to deposition conditions which causes significant processing lot variations of mechanical and metallurgical properties. Furthermore, the process produces a material with a highly textured lenticular rnicrostructural morphology suggesting an anisotropic material response. Understanding and controlling out-of-plane anisotropy is desirable for LIGA components designed for out-of-plane flexures. Previous work by the current authors focused on results from a miniature servo-hydraulic mechanical test frame constructed for characterizing LIGA materials. Those results demonstrated microstructural and mechanical properties dependencies with plating bath current density in LIGA fabricated nickel (LIGA Ni). This presentation builds on that work and fosters a methodology for controlling the properties of LIGA fabricated materials through processing. New results include measurement of mechanical properties of LIGA fabricated copper (LIGA Cu), out-of-plane and localized mechanical property measurements using compression testing and nanoindentation of LIGA Ni and LIGA Cu.

  17. Mechanical and microstructural properties of "wet" alginate and composite films containing various carbohydrates.

    PubMed

    Harper, B Allison; Barbut, Shai; Smith, Alexandra; Marcone, Massimo F

    2015-01-01

    Composite "wet" alginate films were manufactured from alginate-carbohydrate solutions containing 5% alginate and 0.25% pectin, carrageenan (kappa or iota), potato starch (modified or unmodified), gellan gum, or cellulose (extracted or commercial). The "wet" alginate films were used as a model to understand co-extruded alginate sausage casings that are currently being used by several sausage manufacturers. The mechanical, optical, and microstructural properties of the calcium cross-linked composite films were explored. In addition, the water holding capacity and textural profile analysis properties of the alginate-carbohydrate gels were studied. The results indicate that the mechanical properties of "wet" alginate films/casings can be modified by adding various carbohydrates to them. Alginate films with pectin, carrageenan, and modified potato starch had significantly (P < 0.05) greater elongation values than pure alginate films. The alginate-pectin films also had greater (P < 0.05) tensile strengths than the pure alginate films. Alginate films with extracted cellulose, commercial cellulose, and modified potato starch had lower (P < 0.05) puncture force, distance, and work values than the alginate control films. Transmission electron microscopy images showed a very uniform alginate network in the control films. Several large cellulose fibers were visible in the films with extracted cellulose, while the cellulose fibers in the films with commercial cellulose were difficult to distinguish. Despite these apparent differences in cellulose fiber length, the 2 cellulose films had similar puncture and tensile properties. PMID:25471730

  18. Evaluation of antioxidant and antiradical properties of Pomegranate (Punica granatum L.) seed and defatted seed extracts.

    PubMed

    Basiri, Shadi

    2015-02-01

    Pomegranate seeds are byproducts of the Pomegranate juice industries that contains functional compounds such as phenols. This study was aimed to evaluate the effect of solvents on extraction from Pomegranate seed and Pomegranate defatted seed and to measure the yield extract and phenolic content and antioxidant properties. For this purpose, the seeds and defatted seeds were directly isolated from fruits and seeds by cold pressing respectively, then were crushed and extracted with different solvents, including water, Methanol, Acetone, Ethyl acetate and Hexane and finally the extracts of them were evaluted. Phenolic compounds, ferric reducing-antioxidant power and radicals scavenging property of extracts were measured. The results showed the highest extraction efficiencies were for Hexane and Acetone solvents in extraction of seed and defatted seed respectively. The highest phenolic content was obtained from Methanol seed extract. Reducing activity test proved that the Methanol extracts of Pomegranate seed and Pomegranate defatted seed had the highest reducing strength. Results of radical scavenging activity were similar to reducing activity results. The order of antioxidant capacity of Pomegranate seed and Pomegranate defatted seed were found to be Methanol > Water > Acetone > Butanol > Ethyl acetate > Hexane. It can be concluded Pomegranate seed, which possesses high levels of polyphenols, can be one of the sources of the natural antioxidants. The Methanol extract had a higher antioxidant efficiency than seed and defatted seed extracts. PMID:25694727

  19. Anti-inflammatory and neuroactive properties of selected fruit extracts.

    PubMed

    Heim, Kelly C; Angers, Paul; Léonhart, Sebastien; Ritz, Barry W

    2012-09-01

    Epidemiological evidence supports inverse associations between fruit and vegetable intake and incidence of cardiovascular disease and neurodegeneration. Dietary botanicals with salient health benefits include berries and leafy vegetables. Molecular pharmacology research has ascribed these benefits primarily to phenolic constituents and antioxidant activity. The current investigation sought to eluicidate pharmacologic activity of two novel preparations of berry and spinach extracts in vitro. Blueberry and cranberry exhibited the greatest antioxidant activity. In a dose-dependent manner, a proprietary mixture of cranberry and blueberry extracts inhibited inhibitor of κB kinase β, a central node in inflammatory signal transduction. A proprietary mixture of blueberry, strawberry, and spinach extracts inhibited prolyl endopeptidase, a regulator of central neuropeptide stability and an emerging therapeutic target in neurology and psychiatry. These results indicate specific molecular targets of blended dietary plants with potential relevance to inflammation and neurological health. PMID:22871089

  20. Mechanical properties of branched actin filaments

    NASA Astrophysics Data System (ADS)

    Razbin, Mohammadhosein; Falcke, Martin; Benetatos, Panayotis; Zippelius, Annette

    2015-07-01

    Cells moving on a two dimensional substrate generate motion by polymerizing actin filament networks inside a flat membrane protrusion. New filaments are generated by branching off existing ones, giving rise to branched network structures. We investigate the force-extension relation of branched filaments, grafted on an elastic structure at one end and pushing with the free ends against the leading edge cell membrane. Single filaments are modeled as worm-like chains, whose thermal bending fluctuations are restricted by the leading edge cell membrane, resulting in an effective force. Branching can increase the stiffness considerably; however the effect depends on branch point position and filament orientation, being most pronounced for intermediate tilt angles and intermediate branch point positions. We describe filament networks without cross-linkers to focus on the effect of branching. We use randomly positioned branch points, as generated in the process of treadmilling, and orientation distributions as measured in lamellipodia. These networks reproduce both the weak and strong force response of lamellipodia as measured in force-velocity experiments. We compare properties of branched and unbranched networks. The ratio of the network average of the force per branched filament to the average force per unbranched filament depends on the orientation distribution of the filaments. The ratio exhibits compression dependence and may go up to about 4.5 in networks with a narrow orientation distribution. With orientation distributions measured in lamellipodia, it is about two and essentially independent from network compression, graft elasticity and filament persistence length.

  1. Mechanical properties of iron-aluminum alloys

    SciTech Connect

    Alexander, D.J.; Sikka, V.K.

    1993-07-01

    Tensile and impact tests have been conducted on specimens for a series of five heats of iron-aluminum alloys. These results have been compared to data for the iron aluminide alloy FA-129. The first of the new alloys was a simple ternary alloy with iron, aluminum, and chromium contents that matched the FA-129 composition. The second was similar but with additions of zirconium and carbon. Three heats were produced with reduced aluminum contents so that a disordered body-centered cubic structure would be present. Additions of titanium or yttrium were included. The ductile-to brittle transition temperatures of all of the Fe{sub 3}Al alloys were similar, but the simple ternary alloy had a much higher upper-shelf energy levels than the Fe{sub 3}Al type alloys. The reduced aluminum alloy with the yttrium addition showed excellent tensile properties, with a room temperature total elongation of over 40%, and a very high upper-shelf energy level. Despite the high tensile ductility at room temperature, the transition temperature of the yttrium-containing alloy was still about 150{degrees}C, compared to approximately 300{degrees}C for FA-129.

  2. Mechanical properties of porcine intralobar pulmonary arteries.

    PubMed

    Ohtaka, H; Hogg, J C; Moreno, R H; Paré, P D; Schellenberg, R R

    1988-04-01

    The isobaric and isovolumetric properties of intrapulmonary arteries were evaluated by placing a highly compliant balloon inside arterial segments. The passive pressure-volume (P-V) curve was obtained by changing volume (0.004 ml/s) and measuring pressure. The isobaric active volume change (delta V) or isovolumetric active pressure change (delta P) generated by submaximal histamine was measured at four different transmural pressures (Ptm's) reached by balloon inflation. The maximal delta P = 11.2 +/- 0.6 cmH2O (mean +/- SE) was achieved at 30.8 +/- 1.2 cmH2O Ptm and maximal delta V = 0.20 +/- 0.02 ml at 16.7 +/- 1.7 cmH2O Ptm. The P-V relationships were similar when volume was increased after either isobaric or isovolumetric contraction. The calculated length-tension (L-T) relationship showed that the active tension curve was relatively flat and that the passive tension at the optimal length was 149 +/- 11% of maximal active tension. These data show that 1) a large elastic component operates in parallel with the smooth muscle in intralobar pulmonary arteries, and 2) the change in resistance associated with vascular expansion of the proximal arteries is independent of the type of contraction that occurs in the more distal arterial segments. PMID:3378988

  3. Mechanical properties of branched actin filaments.

    PubMed

    Razbin, Mohammadhosein; Falcke, Martin; Benetatos, Panayotis; Zippelius, Annette

    2015-07-01

    Cells moving on a two dimensional substrate generate motion by polymerizing actin filament networks inside a flat membrane protrusion. New filaments are generated by branching off existing ones, giving rise to branched network structures. We investigate the force-extension relation of branched filaments, grafted on an elastic structure at one end and pushing with the free ends against the leading edge cell membrane. Single filaments are modeled as worm-like chains, whose thermal bending fluctuations are restricted by the leading edge cell membrane, resulting in an effective force. Branching can increase the stiffness considerably; however the effect depends on branch point position and filament orientation, being most pronounced for intermediate tilt angles and intermediate branch point positions. We describe filament networks without cross-linkers to focus on the effect of branching. We use randomly positioned branch points, as generated in the process of treadmilling, and orientation distributions as measured in lamellipodia. These networks reproduce both the weak and strong force response of lamellipodia as measured in force-velocity experiments. We compare properties of branched and unbranched networks. The ratio of the network average of the force per branched filament to the average force per unbranched filament depends on the orientation distribution of the filaments. The ratio exhibits compression dependence and may go up to about 4.5 in networks with a narrow orientation distribution. With orientation distributions measured in lamellipodia, it is about two and essentially independent from network compression, graft elasticity and filament persistence length. PMID:26040560

  4. STARCH FILLED TERNARY POLYMER COMPOSITES I: DYNAMIC MECHANICAL PROPERTIES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    It has been shown that the dynamic mechanical properties of starch filled blends of polyethylene (PE) and poly (hydroxy ester ether) (PHEE) are strongly dependent on the properties and distribution of the minor component of the blend (PHEE). The effect of this minor component on the viscoelastic pr...

  5. Porosity and mechanical properties of zirconium ceramics

    NASA Astrophysics Data System (ADS)

    Buyakova, S.; Sablina, T.; Kulkov, S.

    2015-11-01

    Has been studied a porous ceramics obtained from ultra-fine powders. Porous ceramic ZrO2(MgO), ZrO2(Y2O3) powder was prepared by pressing and subsequent sintering of compacts homologous temperatures ranging from 0.63 to 0.56 during the isothermal holding duration of 1 to 5 hours. The porosity of ceramic samples was from 15 to 80%. The structure of the ceramic materials produced from plasma-sprayed ZrO2 powder was represented as a system of cell and rod structure elements. Cellular structure formed by stacking hollow powder particles can be easily seen at the images of fracture surfaces of obtained ceramics. There were three types of pores in ceramics: large cellular hollow spaces, small interparticle pores which are not filled with powder particles and the smallest pores in the shells of cells. The cells generally did not have regular shapes. The size of the interior of the cells many times exceeded the thickness of the walls which was a single-layer packing of ZrO2 grains. A distinctive feature of all deformation diagrams obtained in the experiment was their nonlinearity at low deformations which was described by the parabolic law. It was shown that the observed nonlinear elasticity for low deformation on deformation diagrams is due to mechanical instability of the cellular elements in the ceramic carcass.

  6. Porosity and mechanical properties of zirconium ceramics

    SciTech Connect

    Buyakova, S. Kulkov, S.; Sablina, T.

    2015-11-17

    Has been studied a porous ceramics obtained from ultra-fine powders. Porous ceramic ZrO{sub 2}(MgO), ZrO{sub 2}(Y{sub 2}O{sub 3}) powder was prepared by pressing and subsequent sintering of compacts homologous temperatures ranging from 0.63 to 0.56 during the isothermal holding duration of 1 to 5 hours. The porosity of ceramic samples was from 15 to 80%. The structure of the ceramic materials produced from plasma-sprayed ZrO{sub 2} powder was represented as a system of cell and rod structure elements. Cellular structure formed by stacking hollow powder particles can be easily seen at the images of fracture surfaces of obtained ceramics. There were three types of pores in ceramics: large cellular hollow spaces, small interparticle pores which are not filled with powder particles and the smallest pores in the shells of cells. The cells generally did not have regular shapes. The size of the interior of the cells many times exceeded the thickness of the walls which was a single-layer packing of ZrO{sub 2} grains. A distinctive feature of all deformation diagrams obtained in the experiment was their nonlinearity at low deformations which was described by the parabolic law. It was shown that the observed nonlinear elasticity for low deformation on deformation diagrams is due to mechanical instability of the cellular elements in the ceramic carcass.

  7. Mechanical properties of lanthanum and yttrium chromites

    SciTech Connect

    Paulik, S.W.; Armstrong, T.R.

    1996-12-31

    In an operating high-temperature (1000{degrees}C) solid oxide fuel cell (SOFC), the interconnect separates the fuel (P(O{sub 2}){approx}10{sup -16} atm) and the oxidant (P(O2){approx}10{sup 0.2} atm), while being electrically conductive and connecting the cells in series. Such severe atmospheric and thermal demands greatly reduce the number of viable candidate materials. Only two materials, acceptor substituted lanthanum chromite and yttrium chromite, meet these severe requirements. In acceptor substituted chromites (Sr{sup 2+} or Ca{sup 2+} for La{sup 3+}), charge compensation is primarily electronic in oxidizing conditions (through the formation of Cr{sup 4+}). Under reducing conditions, ionic charge compensation becomes significant as the lattice becomes oxygen deficient. The formation of oxygen vacancies is accompanied by the reduction of Cr{sup 4+} ions to Cr{sup 3+} and a resultant lattice expansion. The lattice expansion observed in large chemical potential gradients is not desirable and has been found to result in greatly reduced mechanical strength.

  8. Mechanical and Thermophysical Properties of Cerium Monopnictides

    NASA Astrophysics Data System (ADS)

    Bhalla, Vyoma; Singh, Devraj; Jain, S. K.

    2016-03-01

    The ultrasonic attenuation due to phonon-phonon interaction, thermoelastic relaxation and dislocation damping mechanisms has been investigated in cerium monopnictides CeX (X: N, P, As, Sb and Bi) for longitudinal and shear waves along {< }100{rangle }, {< }110{rangle } and {< }111{rangle } directions. The second- and third-order elastic constants of CeX have also been computed in the temperature range 0 K to 500 K using Coulomb and Born-Mayer potential upto second nearest neighbours. The computed values of these elastic constants have been applied to find out Young's moduli, bulk moduli, Breazeale's non-linearity parameters, Zener anisotropy, ultrasonic velocity, ultrasonic Grüneisen parameter, thermal relaxation time, acoustic coupling constants and ultrasonic attenuation. The fracture/toughness ratio is less than 1.75, which shows that the chosen materials are brittle in nature as found for other monopnictides. The drag coefficient acting on the motion of screw and edge dislocations due to shear and compressional phonon viscosities of the lattice have also been evaluated for both the longitudinal and shear waves. The thermoelastic loss and dislocation damping loss are negligible in comparison to loss due to Akhieser damping (phonon-phonon interaction). The obtained results for CeX are in qualitative agreement with other semi-metallic monopnictides.

  9. Measuring the mechanical properties of molecular conformers

    PubMed Central

    Jarvis, S. P.; Taylor, S.; Baran, J. D.; Champness, N. R.; Larsson, J. A.; Moriarty, P.

    2015-01-01

    Scanning probe-actuated single molecule manipulation has proven to be an exceptionally powerful tool for the systematic atomic-scale interrogation of molecular adsorbates. To date, however, the extent to which molecular conformation affects the force required to push or pull a single molecule has not been explored. Here we probe the mechanochemical response of two tetra(4-bromophenyl)porphyrin conformers using non-contact atomic force microscopy where we find a large difference between the lateral forces required for manipulation. Remarkably, despite sharing very similar adsorption characteristics, variations in the potential energy surface are capable of prohibiting probe-induced positioning of one conformer, while simultaneously permitting manipulation of the alternative conformational form. Our results are interpreted in the context of dispersion-corrected density functional theory calculations which reveal significant differences in the diffusion barriers for each conformer. These results demonstrate that conformational variation significantly modifies the mechanical response of even simple porpyhrins, potentially affecting many other flexible molecules. PMID:26388232

  10. Crude extract of maggots: Antibacterial effects against Escherichia coli, underlying mechanisms, separation and purification

    PubMed Central

    Ge, Quan-Sheng; Zhang, Hui-Min; Liu, Xia; Wang, Shou-Yu; Lv, De-Cheng; Li, Xu-Dong

    2015-01-01

    AIM: To investigate the antibacterial effects of a crude extract of maggots against Escherichia coli (E. coli) and the underlying mechanisms, and to separate and purify the crude extract of maggots to assess the antibacterial effects of the active ingredients in the crude extract. METHODS: Different concentrations of the crude extract of maggots were incubated with E. coli (O157:H7) and cultured. The optical density (OD) was measured at different time points to plot the OD-T curve. The effects of different concentrations of the crude extract on bacterial membrane permeability were determined by fluorescence probe technique. The effects of different concentrations of the crude extract on plasmid DNA replication were determined by agarose gel electrophoresis. DEAE-Sepharose ion exchange chromatography and Sephacryls-200HR gel filtration chromatography were used to separate and purify the crude extract of maggots. The molecular weight of proteins in the purified crude extract was determined by SDS-PAGD electrophoresis, and its antibacterial effects were determined by turbidimetric method. RESULTS: The antibacterial effects of the crude extract of maggots at concentrations > 0.5 mg/mL were significant. The antibacterial effects of the crude extract at concentrations of 1.0, 1.5 and 2.0 mg/mL did not differ significantly. Fluorescence probe analysis showed that the rate of membrane permeability change was 1223.1% in bacteria incubated with 2 mg/mL of the crude extract, and 1300.0% in those incubated with 80 mg/mL of the crude extract. Plasmid DNA was undetectable in E. coli incubated with 2 and 80 mg/mL of the crude extract. A low molecular weight protein band (about 15 kDa) was detected in the crude extract of maggots and eluent, but not in eluant, from DEAE-Sepharose ion exchange chromatography. The antibacterial effects of the crude extract of maggots and eluent were superior to those of eluant, with the antibacterial effects of eluents being better than those of the