Magnetically-actuated blood filter unit attachable to pre-made biochips

We present a novel blood filter unit that is designed to separate blood plasma from whole blood by simple magnetic actuation. A non-diluted blood sample is dropped into the filter unit and magnetic attraction is applied to squeeze out only blood plasma while blood particles are filtered by membranes stacked in the filter unit. The new filter device yields good filtering performance with nearly perfect filtering efficiency (～99.999%), high plasma recovery (～30%), low blood consumption (<50 μl), and fast operation (～1 min). Because it is simple to operate and is attachable to any kind of pre-made biochip, it has commercial potential in various lab-on-a-chip applications for blood tests.     

On Worpitzky-like theorems for a two-dimensional continued fraction

Using estimates for the remainders of a two-dimensional continued fraction, the relation for the difference between two approximants of such a fraction in terms of these remainders, and the majorant method, we have proposed generalizations of the Worpitzky convergence theorem. For fractions satisfying the conditions of generalized Worpitzky theorems, we have also obtained estimates for their convergence rate.     

A practical preparation of methyl 2-methoxy-6-methylaminopyridine-3-carboxylate from 2,6-dichloro-3-trifluoromethylpyridine.

An effective and practical synthetic route to methyl 2-methoxy-6-methylaminopyridine-3-carboxylate (7), the key intermediate of 5-bromo-2-methoxy-6-methylaminopyridine-3-carboxylic acid (1), from 2,6-dichloro-3-trifluoromethylpyridine (12) was undertaken. Process improvements were highlighted by regioselectivity of 12 with a nitrogen nucleophile and conversion of the 3-trifluoromethyl group into the methoxycarbonyl group. The reaction of 12 with N-benzylmethylamine provided the 6-(N-benzyl-N-methyl)aminopyridine 26a and the regioisomer 26b in >98:<2 ratio in a quantitative yield. Treatment of 2-methoxy-6-methylamino-3-trifluoropyridine (14a) with a large excess of sodium methoxide followed by acid hydrolysis gave the pyridine-3-carboxylic ester 7 in an excellent yield. The potential application of this reaction is also described.     

Throughput Measurement of a Multilayer-Coated Schwarzschild Objective Using Synchrotron Radiation

The throughput of a Schwarzschild objective using undulator synchrotron radiation was measured. Conventionally, the throughput was estimated from the squared reflectivity of one multilayer mirror and from the obstruction ratio. However, we evaluated the transmission ratio from the input and output photon flux using a precisely calibrated monochromatic beam from an undulator light source. It was found that the objective has a maximum throughput of 8.5% at a wavelength of 13.9 nm.     

Asymptotic distribution of Wishart matrix for block-wise dispersion of population eigenvalues

This paper deals with the asymptotic distribution of Wishart matrix and its application to the estimation of the population matrix parameter when the population eigenvalues are block-wise infinitely dispersed. We show that the appropriately normalized eigenvectors and eigenvalues asymptotically generate two Wishart matrices and one normally distributed random matrix, which are mutually independent. For a family of orthogonally equivariant estimators, we calculate the asymptotic risks with respect to the entropy or the quadratic loss function and derive the asymptotically best estimator among the family. We numerically show (1) the convergence in both the distributions and the risks are quick enough for a practical use, (2) the asymptotically best estimator is robust against the deviation of the population eigenvalues from the block-wise infinite dispersion.     

Proton nuclear magnetic resonance spectra of brain tumors

Proton nuclear magnetic resonance (NMR) spectra were successfully measured in human brain tumor tissues and experimental rat brain tumors. The investigation was performed on clinical materials which consisted of tissue from one normal brain and 36 brain tumors. Normal rat brain tissue and rat glioma implanted in the brain were also analysed. NMR measurements were carried out at the resonance frequency of 99.54 MHz. The proton NMR spectrum of the normal brain consisted of one broad component and eight superimposed sharp peaks. The sharp peaks obtained from the brain tumors varied from those of the normal brain. A decrease in the signal intensity from N-acetyl aspartate was the most common finding in all tumors. Spectral patterns were similar within the same histological types, but varied among the different types. Therefore, ¹H-NMR spectra might indicate the metabolism characteristic of each tumor type which would be invaluable for clinical differential dagnosis of brain tumors.     

Scattering function for wormlike chains with finite thickness

The particle scattering function P(k) is approximately evaluated for the Kratky–Porod wormlike chain with a circular cross section to examine the effect of chain diameter d on the scattering curve of k²P(k) versus k, the magnitude of the scattering vector, for stiff chains and also the applicability of the cross‐section plot of ln[kP(k)] versus k² to them. In the evaluation, series expansions from the rod and coil limits up to the fifth‐order and third‐order deviations, respectively, are combined together. The major results or conclusions derived are as follows. First, the conventional equation, P(k) = P₀(k) exp(?k²d²/16), for straight cylinders overestimates k²P(k) at relatively large values of k, whereas its alternative, P(k) = P₀(k)[2J₁(kd/2)/(kd/2)]², is a good approximation to exact P(k) unless contour length L is shorter than 10d. Here, P₀(k) denotes the scattering function for the chain contour, and J₁(x) is the Bessel function of the first order. Second, as d is increased for a fixed value of L (relative to the Kuhn segment length), the k²P(k)–k curve lowers with a pronounced maximum, and the peak position shifts to a lower scattering angle. Third, if the chain is somewhat flexible, the cross‐section plot has an approximately linear region, with a slope fairly close to ?d²/16 expected from the aforementioned conventional equation. This plot for rods appreciably bends down, and thus the experimental observation of an approximately linear relation (over a wide k range) implies that, in contrast to the prevailing notion, the polymer examined is not completely rigid but instead is somewhat flexible. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1398–1407, 2004     

Deracemization of α-monosubstituted cyclopentanones in the presence of a TADDOL-type host molecule

Racemic α-monosubstituted cyclopentanones were converted to optically active forms by a thermodynamically controlled deracemization using TADDOL-type host molecule 1 in alkaline aqueous MeOH. The efficiency of this conversion was strongly influenced by the ratio of the solvent components (H₂O/MeOH) and the functionality and architecture of the α-side-chain on the cyclopentanones. For example, (R)-2-(2-benzyloxyethyl)cyclopentanone (9) was obtained in 89% yield with 97% ee using a 7:3 mixture of H₂O/MeOH as the solvent. X-ray analytical studies were also carried out and disclosed the nature of this chiral molecular recognition process in the solid phase.