Centrifuge Force Research Articles

Wavelet-based damage detection method for a beam-type structure carrying moving mass

In this research, the wavelet transform is used to analyze time response of a cracked beam carrying moving mass for damage detection. In this respect, a new damage detection method based on the combined use of continuous and discrete wavelet transforms is proposed. It is shown that this method is more capable in making damage signature evident than the traditional two approaches based on direct investigation of the wavelet coefficients of structural response. By the proposed method, it is concluded that strain data outperforms displacement data at the same point in revealing damage signature. In addition, influence of moving mass-induced terms such as gravitational, Coriolis, centrifuge forces, and pure inertia force along the deflection direction to damage detection is investigated on a sample case. From this analysis it is concluded that centrifuge force has the most influence on making both displacement and strain data damage-sensitive. The Coriolis effect is the second to improve the damage-sensitivity of data. However, its impact is considerably less than the former. The rest, on the other hand, are observed to be insufficient alone.

Effects of Ultraviolet-A and Riboflavin on the Interaction of Collagen and Proteoglycans during Corneal Cross-linking

Corneal cross-linking using riboflavin and ultraviolet-A (RFUVA) is a clinical treatment targeting the stroma in progressive keratoconus. The stroma contains keratocan, lumican, mimecan, and decorin, core proteins of major proteoglycans (PGs) that bind collagen fibrils, playing important roles in stromal transparency. Here, a model reaction system using purified, non-glycosylated PG core proteins in solution in vitro has been compared with reactions inside an intact cornea, ex vivo, revealing effects of RFUVA on interactions between PGs and collagen cross-linking. Irradiation with UVA and riboflavin cross-links collagen α and β chains into larger polymers. In addition, RFUVA cross-links PG core proteins, forming higher molecular weight polymers. When collagen type I is mixed with individual purified, non-glycosylated PG core proteins in solution in vitro and subjected to RFUVA, both keratocan and lumican strongly inhibit collagen cross-linking. However, mimecan and decorin do not inhibit but instead form cross-links with collagen, forming new high molecular weight polymers. In contrast, corneal glycosaminoglycans, keratan sulfate and chondroitin sulfate, in isolation from their core proteins, are not cross-linked by RFUVA and do not form cross-links with collagen. Significantly, when RFUVA is conducted on intact corneas ex vivo, both keratocan and lumican, in their natively glycosylated form, do form cross-links with collagen. Thus, RFUVA causes cross-linking of collagen molecules among themselves and PG core proteins among themselves, together with limited linkages between collagen and keratocan, lumican, mimecan, and decorin. RFUVA as a diagnostic tool reveals that keratocan and lumican core proteins interact with collagen very differently than do mimecan and decorin.

Citations

Citations

Massively Parallel Single-Molecule Manipulation Using Centrifugal Force

Precise manipulation of single molecules has already led to remarkable insights in physics, chemistry, biology, and medicine. However, widespread adoption of single-molecule techniques has been impeded by equipment cost and the laborious nature of making measurements one molecule at a time. We have solved these issues by developing an approach that enables massively parallel single-molecule force measurements using centrifugal force. This approach is realized in an instrument that we call the centrifuge force microscope in which objects in an orbiting sample are subjected to a calibration-free, macroscopically uniform force-field while their micro-to-nanoscopic motions are observed. We demonstrate high-throughput single-molecule force spectroscopy with this technique by performing thousands of rupture experiments in parallel, characterizing force-dependent unbinding kinetics of an antibody-antigen pair in minutes rather than days. Additionally, we verify the force accuracy of the instrument by measuring the well-established DNA overstretching transition at 66 ± 3 pN. With significant benefits in efficiency, cost, simplicity, and versatility, single-molecule centrifugation has the potential to expand single-molecule experimentation to a wider range of researchers and experimental systems.

Predicting pork water-holding capacity with NIR spectroscopy in relation to different reference methods

The objective of the study was to evaluate the ability of near infrared (NIR) spectroscopy to predict pork water-holding capacity (WHC) in relation to different methods of WHC determination. The study comprised 228 longissimus dorsi muscle samples (147 for calibration, 81 for external validation). Calibration models were developed using WinISI II on visible ( λ = 400–1100 nm), NIR ( λ = 1100–2500 nm) or the whole spectral range ( λ = 400–2500 nm). Models’ quality was assessed by means of the coefficient of determination of cross-validation ( R cv 2 ) or prediction ( R p 2 ) and the error of cross-validation ( se cv ) or prediction ( se p ) . The R cv 2 ranged from 0.28 to 0.62, while se cv was estimated between 1.0% and 1.4% for EZ drip loss (meat juice container procedure), 2.3% and 2.5% for cooking loss, 1.9% and 2.3% for centrifuge force and 0.9% and 1.0% for tray drip loss, and was similar to the repeatability ( s r ) of the method (1.1%, 1.8%, 2.0%, 0.4%, respectively). The results of the external validation confirmed those obtained by cross-validation ( R p 2 = 0.22 – 0.44 ; se p = 1.2 – 1.3 % , 2.2–2.4%, 2.1–2.3% and 1.1% for EZ drip loss, cooking loss, centrifuge force and tray drip loss, respectively). The best calibration results were obtained for EZ drip loss ( R cv 2 = 0.62 , se cv = 1.0 % ) and tray drip loss ( R cv 2 = 0.49 , se cv = 0.9 % ) on visible spectral range. NIR spectroscopy offers great advantages for the on-line application, however, its prediction ability is limited by the reference methods and this should be taken into account.

J1102-4-2 移動支援機器Tread-Walk 1における搭乗者の位置を考慮した旋回アルゴリズムの開発([1102-4]ライフサポート(4))

J1102-4-2 移動支援機器Tread-Walk 1における搭乗者の位置を考慮した旋回アルゴリズムの開発([1102-4]ライフサポート(4))

Interplay between lipoproteins and bee venom phospholipase A2 in relation to their anti-plasmodium toxicity

We previously showed that the in vitro intraerythrocytic development of the malarial agent Plasmodium falciparum is strongly inhibited by secreted phospholipases A(2) (sPLA(2)s) from animal venoms. Inhibition is dependent on enzymatic activity and requires the presence of serum lipoproteins in the parasite culture medium. To evaluate the potential involvement of host lipoproteins and sPLA(2)s in malaria, we investigated the interactions between bee venom phospholipase A(2) (bvPLA(2)), human triglyceride-rich lipoproteins, and infected erythrocytes. Even at high enzyme concentration (100x IC(50)), bvPLA(2) binding to Plasmodium-infected or normal erythrocytes was not detected. On the contrary, tight association with lipoproteins was observed through the formation of buoyant bvPLA(2)/lipoprotein complexes. Direct involvement of the hydrolysis lipid products in toxicity was demonstrated. Arachidonic acid (C20:4), linoleic acid (C18:2), and, to a lesser extent, docosahexaenoic acid (C22:6) appeared as the main actors in toxicity. Minimal oxidation of lipoproteins enhanced toxicity of the lipolyzed particles and induced their interaction with infected or normal erythrocytes. Fresh or oxidized lipolyzed lipoproteins induced the parasite degeneration without host cell membrane disruption, ruling out a possible membranolytic action of fatty acids or peroxidation products in the death process. In conclusion, our data enlighten on the capability of secreted PLA(2)s to exert cytotoxicity via the extracellular generation of toxic lipids, and raise the question of whether such mechanisms could be at play in pathophysiological situations such as malaria.

Recuperação de proteínas do soro de leite por meio de coacervação com polissacarídeo

O objetivo deste trabalho foi recuperar e fracionar as proteínas do soro de leite por meio da técnica de coacervação, utilizando o polissacarídeo carboximetilcelulose sódica (CMC). O soro de leite foi obtido da fabricação industrial do queijo tipo frescal. Foram estudados concentrações do polímero (0,1% a 0,9% CMC p/v) e valores de pH, a fim de se obter uma precipitação seletiva das proteínas do soro de leite, sendo as condições otimizadas para produção em piloto. Mediante ajuste gradual, foi possível obter, no pH 3, uma precipitação das proteínas totais (PT/CMC); no pH 4, da beta-lactoglobulina (beta-Lg/CMC) e, no pH 3,2, a maior proporção de alfa-lactoalbumina (alfa-La/CMC). Os coacervados foram separados, por aplicação de força centrífuga, e caracterizados em relação à composição centesimal e perfil eletroforético. O maior rendimento foi verificado no fracionamento da beta-lactoglobulina, com 86% de recuperação dessa classe de proteínas do soro desnatado. O coacervado beta-lactoglobulina-CMC (beta-Lg/CMC) apresenta maior conteúdo protéico, provavelmente em conseqüência da proporção estabelecida entre os hidrocolóides coacervados. O coacervado composto pela alfa-La/CMC apresentou menor conteúdo protéico e porcentagem de recuperação dessas proteínas presentes no soro.

Use of Centrifuge Force to Fabricate Reticulated Porous Ceramics Results in Uniform Structure

Use of Centrifuge Force to Fabricate Reticulated Porous Ceramics Results in Uniform Structure

On styrene–butadiene–styrene–barium ferrite nanocomposites

Magnetic investigations on a nanocomposite material obtained by spinning solutions of styrene–butadiene–styrene block copolymer containing barium ferrite nanoparticles onto Si wafers are reported. The effect of the spinning frequency on the magnetic features is discussed. It is observed that the magnetization at saturation is decreased as the spinning frequency is increased as the centrifuge force removes the magnetic nanoparticles from the solution. This is supported by the derivative of the hysteresis loops, which show two components, one with a high coercive field and another with a small coercive field. Increasing the spinning frequency increases the weight of the low coercive field component. The anisotropy in the distribution of magnetic nanoparticles, triggered eventually by the self-assembly capabilities of the matrix, is revealed by the difference between the coercive field in parallel and perpendicular configuration. It is noticed that increasing the spinning frequency enhances this difference. The effect of annealing the nanocomposite films is discussed.

Effect of centrifuge conditions on water and total dissolved phosphorus extraction from soil

Centrifugation of soils to extract soil water is widely used to investigate the chemical properties of soil water. However, no single set of standard operating conditions in terms of centrifuge time and speed have been defined. This study investigated centrifuge conditions on the effect of volume of soil water and phosphorus concentrations extracted to determine a set of standard operating conditions that could be used for soil water extraction in the future.Two contrasting soils that had been dried and rewet, a Ferrosol and a Dermosol, were used to investigate centrifuge speed (1000–3000 r.p.m.) and centrifuge time (5–30 min) on the extraction of soil water. Centrifuge speeds of 1000, 2000, and 3000 r.p.m. were trialed in this study giving relative centrifugal forces of 220, 881, and 1982g respectively. Increasing centrifuge time significantly increased (P < 0.001) the volume of soil water extracted. Almost twice as much soil water was extracted when the centrifuge time was increased from 5 to 30 min. Centrifuge speed was also a highly significant factor (P < 0.001) in increasing the volume of soil water extracted. The amount of soil water extracted increased by up to 15% when the centrifuge speed was increased from 1000 to 3000 r.p.m.The concentration of total dissolved phosphorus (TDP) did not change significantly with either centrifuge speed or time. The most important factor in determining the concentration of TDP was the soil type.The conditions that gave an adequate volume of soil water for analyses from field-moist soils in the shortest amount of time were a centrifuge force of 1982g and a time of 10 min.

Numerical analysis on the action of centrifuge force in magnetic fluid rotating shaft seals

The magnetic fluid seal is suitable for high-speed rotating shaft seal applications. Centrifuge force will have evident influence on magnetic fluid rotating shaft seals. The seal capacity of the rotating shaft seal can be improved or increased by some measures. Through hydrodynamic analysis the moving status of the magnetic fluid is worked out. By numerical method, the magnetic field and the isobars in the magnetic fluid of a seal device are computed. Then the influence of the centrifuge force on the magnetic fluid seal is calculated quantitatively.

Laminar flow effects in the coil planet centrifuge

The coil planet centrifuge designedby Ito employs flow of a single liquid pphase, through a rotating coiled tube in a centrifuge force field, to provide a separation of particles based on sedidmentation rates. Mathematical soltuions are derived for the linear differential equations governing particle behavior in the coil planet centrifuge device. These solutions are then applied as the basis of a model for optimizing particle separations.

An Evaluation of Zonal Centrifugation as a Research Tool in Soil Science: II. Characterization of Soil Clays

AbstractData revealed little resolution in banding is gained in centrifuging for 40 compared to 17 hours in a conventional centrifuge (force field less than 623 × g). On the other hand, the resolution obtained by centrifuging in an ultracentrifuge is considerably better than that obtained in a conventional refrigerated centrifuge. The clay fraction from a Dodge silt loam banded into nine fractions after centrifuging at 15,000 rpm (38,500 × g) for 17 hours. Characterization of each band allowed a much more extensive evaluation as to the quantities of each specific clay mineral present than the conventional estimates presently being made by examining X‐ray diffractograms of the total clay fractions.