体内無給電型人工心臓駆動用磁気式アクチュエータの性能向上

研究種目:科学研究費補助金基盤研究(C)報告年度:2001年度研究課題番号:11650280研究概要:本研究は,平成11年度から3カ年に亘って遂行したものであり,平成13年度は,以下の研究業績を得た。1.アクチュエータ出力向上を目的とした磁石ヨークの検討本アクチュエータの機構上,金属磁石に隣接させるヨークの磁化特性がアクチュエータの磁気力を左右させ,その結果としてこれがアクチュエータ出力を決定する要因の一つとなっており,珪素鋼鈑を含む複数のヨークに対して,最もアクチュエータ出力が得られるヨークを決定した。ヨーク厚としては,1.6mmから6mmまでを検討した。また,ヨークの体積軽減を図り,アクチュエータの軽量化実現のため,金属磁石ヨークを空洞化して,その内径について検討した。シミュレーションにより金属磁石間に働く磁力を計算し,シリンダ行程を最大限取れるヨーク厚およびヨーク内径を求めた。2.アクチュエータ出力向上を目的とした構造設計法の確立アクチュエータによって駆動されるポンプのシリンダ行程およびシリンダへの電磁力仕様から,金属磁石の内径寸法を決定するアルゴリズムを構築した。本アクチュエータを人工心臓駆動用ポンプへ適用する場合を想定し,ヒトの循環器系の最高血圧からポンプの最大圧力出力を仕様として定め,一方,シリンダ行程の最大状態からポンプ動作が可能な磁石間距離を求めてこれもポンプ設計上の仕様と定めた。これらの仕様および金属磁石の磁化特性からポンプ出力を最大とするシリンダ行程および磁石間距離を定めるアルゴリズムを構築した

Detection of matrilysin (MMP-7) activity using polypeptide functionalized reduced graphene oxide field-effect transistor sensor.

A novel approach for rapid and sensitive detection of matrilysin (MMP-7, a biomarker involved in the degradation of vari-ous macromolecules) based on polypeptide (JR2EC) functionalized reduced graphene oxide (rGO) field effect transistor (FET) is reported. MMP-7 specifically digests negatively charged JR2EC immobilized on rGO, thereby modulating the con-ductance of rGO-FET. The proposed assay enabled detection of MMP-7 at clinically relevant concentrations with a limit of detection (LOD) of 10 ng/mL (400 pM), attributed to the significant reduction of the net charge of JR2EC upon digestion by MMP-7. Quantitative detection of MMP-7 in human plasma was further demonstrated with a LOD of 40 ng/mL, illustrating the potential for the proposed methodology for tumor detection and carcinoma diagnostic (e.g. lung cancer and salivary gland cancer). Additionally, excellent specificity of the proposed assay was demonstrated using matrix metallopeptidase 1 (MMP-1), a protease of the same family. With appropriate selection and modification of polypeptides, the proposed assay could be extended for detections of other enzymes with polypeptide digestion capability

INFLUENCE OF SOCCER ON THE PHYSICAL PERFORMANCE OF UNIVERSITY STUDENTS

ABSTRACT Introduction Football is a sport with good acceptance among contemporary university students; it integrates competition, entertainment, and physical fitness. However, few studies demonstrate the concrete advantages found in college players. Objective Explore the impact of football on the physical performance of university students. Methods 100 university volunteers in elementary class 1-3 soccer practitioners, aged 19.2±2.1 years, were evaluated by a battery of tests in body composition, body function, and physical fitness. The results were compared with the literary data, and the experiment went through a mathematical, statistical method to separate the soccer intervention and conduct empirical research on physical health. Results After the 18-week elective course intervention, the 50m and 1000m sprint results changed significantly, especially the 1000m sprint performance greatly improved; the difference was significant (P</div

Backbone Modification of β-Hairpin-Forming Tetrapeptides in Asymmetric Acyl Transfer Reactions

Synthetic oligopeptides as mimics of enzymes have been increasingly exploited as catalysts for asymmetric reactions, but highly effective oligopeptide catalysts with relatively low molecular weight are still in great demand. In this paper, we showed the conformational engineering of the β-hairpin-forming tetrapeptide 4 which was first reported by Miller’s group as the catalyst for the asymmetric acyl transfer reaction of trans-2-(N-acetylamino)cyclohexan-1-ol (krel = 28). Through our backbone modification strategy, thioamide and sulfonamide as the isosteres of amide were introduced in the β-hairpin secondary structure. The thioxo peptides also adopt β-hairpin conformations as the oxopeptide supported by the combined use of NMR, IR, and X-ray techniques. Thioxo tetrapeptide 14 formed a more constrained β-hairpin conformation and therefore delivered much higher enantioselectivity (krel = 109) in the same reaction. Moreover, the examination of the conformational changes of tetrapeptide 8 upon the protonation of the Nπ-methylhistidine moiety provided evidence to explain the variation of its catalytic efficiency in the asymmetric acyl-transfer reaction

Curvature of the Localized Surface Plasmon Resonance Peak

Localized surface plasmon resonance (LSPR) occurring in noble metal nanoparticles (e.g., Au) is a widely used phenomenon to report molecular interactions. Traditional LSPR sensors typically monitor shifts in the peak position or extinction in response to local refractive index changes in the close vicinity of the nanoparticle surface. The ability to resolve minute shifts/extinction changes is to a large extent limited by instrumental noise. A new strategy to evaluate LSPR responses utilizing changes in the shape of the extinction spectrum (the curvature) is proposed. The response of curvature to refractive index changes is investigated theoretically using Mie theory and an analytical expression relating the curvature to the refractive index is presented. The experimentally derived curvatures for 13 nm spherical gold nanoparticles (AuNPs) exposed to solvents with different bulk refractive indices confirm the theoretical predictions. Moreover, both the calculated and experimental findings suggest that the curvature is approximately a linear function of refractive index in regimes relevant to bio and chemical sensing. We demonstrate that curvature is superior over peak shift and extinction both in terms of signal-to-noise (S/N) ratio and reliability of LSPR sensors. With a curvature, one could readily monitor submonolayer adsorption of a low molecular weight thiol molecule (<i>M</i>_w = 458.6) onto 13 nm AuNPs. It is also worthwhile mentioning that curvature is virtually insensitive to instrumental instabilities and artifacts occurring during measurement. Instabilities such as baseline tilt and shift, shift in peak position as well as sharp spikes/steps in the extinction spectra do not induce artifacts in the sensorgrams of curvature

Backbone Modification of β-Hairpin-Forming Tetrapeptides in Asymmetric Acyl Transfer Reactions

Synthetic oligopeptides as mimics of enzymes have been increasingly exploited as catalysts for asymmetric reactions, but highly effective oligopeptide catalysts with relatively low molecular weight are still in great demand. In this paper, we showed the conformational engineering of the β-hairpin-forming tetrapeptide 4 which was first reported by Miller’s group as the catalyst for the asymmetric acyl transfer reaction of trans-2-(N-acetylamino)cyclohexan-1-ol (krel = 28). Through our backbone modification strategy, thioamide and sulfonamide as the isosteres of amide were introduced in the β-hairpin secondary structure. The thioxo peptides also adopt β-hairpin conformations as the oxopeptide supported by the combined use of NMR, IR, and X-ray techniques. Thioxo tetrapeptide 14 formed a more constrained β-hairpin conformation and therefore delivered much higher enantioselectivity (krel = 109) in the same reaction. Moreover, the examination of the conformational changes of tetrapeptide 8 upon the protonation of the Nπ-methylhistidine moiety provided evidence to explain the variation of its catalytic efficiency in the asymmetric acyl-transfer reaction

A General Strategy to Convert the MerR Family Proteins into Highly Sensitive and Selective Fluorescent Biosensors for Metal Ions

The MerR family metal-regulatory proteins are converted into fluorescent biosensors that can detect different metal ions with high sensitivity and selectivity

Additional file 1 of Drug-target interaction prediction based on spatial consistency constraint and graph convolutional autoencoder

Additional file 1. Novel DTIs predicted by SDGAE.xlsx: it contains 30 candidate targets for all drugs in the dataset. The candidate targets for each drug are sorted in descending order according to their prediction scores

Oxygen Activation by the Noncoupled Binuclear Copper Site in Peptidylglycine α-Hydroxylating Monooxygenase. Reaction Mechanism and Role of the Noncoupled Nature of the Active Site

Reaction thermodynamics and potential energy surfaces are calculated using density functional methods to investigate possible reactive Cu/O2 species for H-atom abstraction in peptidylglycine α-hydroxylating monooxygenase (PHM), which has a noncoupled binuclear Cu active site. Two possible mononuclear Cu/O2 species have been evaluated, the 2-electron reduced CuIIM−OOH intermediate and the 1-electron reduced side-on CuIIM−superoxo intermediate, which could form with comparable thermodynamics at the catalytic CuM site. The substrate H-atom abstraction reaction by the CuIIM−OOH intermediate is found to be thermodynamically accessible due to the contribution of the methionine ligand, but with a high activation barrier (∼37 kcal/mol, at a 3.0-Å active site/substrate distance), arguing against the CuIIM−OOH species as the reactive Cu/O2 intermediate in PHM. In contrast, H-atom abstraction from substrate by the side-on CuIIM−superoxo intermediate is a nearly isoenergetic process with a low reaction barrier at a comparable active site/substrate distance (∼14 kcal/mol), suggesting that side-on CuIIM−superoxo is the reactive species in PHM. The differential reactivities of the CuIIM−OOH and CuIIM−superoxo species correlate to their different frontier molecular orbitals involved in the H-atom abstraction reaction. After the H-atom abstraction, a reasonable pathway for substrate hydroxylation involves a “water-assisted” direct OH transfer to the substrate radical, which generates a high-energy CuIIM−oxyl species. This provides the necessary driving force for intramolecular electron transfer from the CuH site to complete the reaction in PHM. The differential reactivity pattern between the CuIIM−OOH and CuIIM−superoxo intermediates provides insight into the role of the noncoupled nature of PHM and dopamine β-monooxygenase active sites, as compared to the coupled binuclear Cu active sites in hemocyanin, tyrosinase, and catechol oxidase, in O2 activation

Data_Sheet_1_On the Hysteresis Mechanism of Magnetorheological Fluids.docx

In this paper, hysteresis of magnetorheological (MR) fluids is identified from experimental tests following the mechanism of rate-independence and further studied to explore the hysteresis mechanism. The theoretical analysis based on the dipole model is provided to reveal the hysteresis mechanism of MR fluids. Specifically, the performance tests of a self-developed double-rod MR damper under different excitations show that instead of the typical force-velocity plot, the relationship between the force and displacement meets the requirements of rate-independence of the hysteresis well. A critical concept of “yield displacement” is defined and analyzed in the force-displacement plot to illustrate the hysteresis characteristics. In addition, the relationship of the normalized restoring force vs. strain is derived for a single chain from the dipole model. Then a stress-strain curve is developed for the multi-chain structure with an assumption of the dynamic equilibrium between the rupture and reconstruction of the chains. Sequentially, the hysteresis mechanism is established based on the force-displacement characteristics under reciprocating excitations. The consistency between the yield displacement in experiment and yield strain in theory verifies the effectiveness of the hypothetical hysteresis mechanism. The analysis results provide a guideline for the structural design of MR devices to enhance/reduce the hysteresis effect. The hysteresis mechanism-based further extension for the stress-strain properties of MR elastomers and the response time of MR fluids are provided as well.</p