Preparation of composite monoliths of quaternized chitosan and diatom earth for protein separation

In this study, composite monoliths with porous structures were prepared using quaternized chitosan and diatom earth for protein separation. Quaternized chitosan (N-[(2-hydroxy-3-trimethylammonium)propyl] chitosan chloride) dissolved in water was mixed with diatom earth and crosslinked with glutaraldehyde under low-temperature conditions to form a cryogel. Interconnected porous monoliths were obtained after removing ice crystals from the cryogel. The monoliths adsorbed bovine serum albumin selectively from the solution mixture of bovine serum albumin and bovine ɤ-globulin, and bovine ɤ-globulin was recovered in the flow-through fraction. The adsorption selectivity was enhanced by changing the solution pH from 6.8 to 5.5. The adsorption of bovine serum albumin by the monolith was replicated at least five times following its washing with a buffer containing 400 mM NaCl and subsequent regeneration with a 10 mM acetate buffer. The composited monolith is a promising adsorbent for the removal of acidic proteins, such as serum albumin contamination in neutral proteins, for example, ɤ-globulins, in bioproduction processes.     

A study on the synthesis of calix[4 and 6]arenes using alternately arranged phloroglucinols and p-tert-butylphenols

A method for the synthesis of calix[4 and 6]arenes with two or three alternately arranged phloroglucinols and p-tert-butylphenols was studied using "3+1" and "5+1" approaches, compared to a simple one-pot synthesis based on a "1+1" approach. By using Yb(OTf)3 as a catalyst, each calix[4 and 6]arenes was afforded, in an overall yield of 20.7% and 11.8% in the "3+1" and "5+1" approaches, respectively, and 24.6% and 19.9% using a "1+1" approach with chlorobenzene and toluene as refluxing solvents, respectively.     

Relative rotational motion between alpha-Cyclodextrin Derivatives and a stiff axle molecule

Novel [2]rotaxanes bearing alpha-cyclodextrin (alpha-CD) derivatives and a diphenylacetylene axis molecule with trinitrobenzene as a bulky stopper have been prepared to investigate the relative rotary movement of a ring relative to an axis molecule and that of an axis molecule in a ring by NMR techniques. [2]Rotaxanes 2 and 3 were composed of alpha-CD derivatives (2: 6-phenyl-amide-alpha-CD; 3: 6-stilbene-amide-alpha-CD). The protons of alpha-CDs in rotaxanes were thoroughly assigned by the two-dimensional NMR techniques (TOCSY, COSY, ROESY, HMQC, and HMBC). The protons of alpha-CD in rotaxane 1 did not show splitting, whereas the resonance peak shifts and splitting for the corresponding protons of alpha-CD derivatives in rotaxanes 2 and 3 were observed by the shielding and deshielding effects from a diphenylacetylene axis molecule. The splitting of resonance peaks was closely related to the rotary movements of alpha-CDs and an axis molecule. We supposed that alpha-CD in rotaxane 1 rotates freely around a diphenylacetylene axis molecule, and vice versa, whereas the rotary movement of alpha-CD derivatives and the axis molecules of rotaxanes 2 and 3 were restricted by the steric repulsion between the substituent group of alpha-CD and the stopper group of an axis molecule. To estimate the relative rotary movement of CDs and an axis molecule in rotaxanes, the rotational correlation time (tauc) of rotaxanes was measured by 13C NMR. The results indicate that the corresponding rotary movement of the modified alpha-CD and the axis molecules in rotaxanes 2 and 3 depends on the size of the substituent group.     

Halichonadins K and L, new dimeric sesquiterpenoids from a sponge Halichondria sp

Two new structurally unique dimeric sesquiterpenoids, halichonadins K (1) and L (2), were isolated from an Okinawan marine sponge Halichondria sp. The structures of 1 and 2 were elucidated on the basis of spectroscopic analysis including a single crystal X-ray diffraction analysis and chemical conversion. Halichonadins K (1) and L (2) are homodimers of the eudesmane sesquiterpene linked with a piperidine ring through amide bonds. Halichonadin K (1) showed moderate cytotoxicity against KB cells.     

The Effects of Cyclodextrins on Autoinducer Activities of Quorum Sensing in Pseudomonas aeruginosa

Inclusion complex formation between cyclodextrin and autoinducer of gram negative bacteria in aqueous solution was investigated by 1D ¹H-NMR and ROESY spectra. An inhibitioneffect was observed on autoinducer activities of quorum sensing in Pseudomonas aeruginosa by adding cyclodextrins to the bacterial culture medium.     

Catalytic Reduction of Dinitrogen into Ammonia and Hydrazine by Using Chromium Complexes Bearing PCP-Type Pincer Ligands**

A series of chromium-halide, -nitride, and -dinitrogen complexes bearing carbene- and phosphine-based PCP-type pincer ligands has been newly prepared, and some of them are found to work as effective catalysts to reduce dinitrogen under atmospheric pressure, whereby up to 11.60 equiv. of ammonia and 2.52 equiv. of hydrazine (16.6 equiv. of fixed N atom) are produced based on the chromium atom. To the best of our knowledge, this is the first successful example of chromium-catalyzed conversion of dinitrogen to ammonia and hydrazine under mild reaction conditions.     

Fabrication of Ge-channel MOSFETs by using replacement gate process and selective epitaxial growth

We fabricated Ge-channel metal-oxide-semiconductor field-effect transistors (MOSFETs) by using replacement gate process and selective epitaxial growth. In our method, thin Ge layers were selectively grown on the channel region of MOSFETs after the removal of a sacrificial gate stack structure and the etching of the channel region. Ge layers with a smooth surface and a good morphology could be obtained by using the thin Si_0.5Ge_0.5 buffer layer. Dislocations were observed in the epitaxial layers and near the interface between the epitaxial layer and the substrates. We consider that these dislocations degrade the device performance. Although the electrical characteristics of the obtained MOSFETs need further improvement, our method is one of the promising candidates for the practical fabrication process of Ge-channel MOSFETs.     

Stable monopole and dyon solutions in the einstein-yang-mills theory in asymptotically anti-de sitter space

A continuum of new monopole and dyon solutions in the Einstein-Yang-Mills theory in asymptotically anti-de Sitter space are found. They are regular everywhere and specified by their mass and their non-Abelian electric and magnetic charges. A class of monopole solutions which have no node in non-Abelian magnetic fields is shown to be stable against spherically symmetric linear perturbations.     

Generic initial ideals of some monomial complete intersections in four variables

Let R = K[x ₁, x ₂, x ₃, x ₄] be the polynomial ring over a field of characteristic zero. For the ideal (x₁^a, x₂^b, x₃^c, x₄^d) ì R{(x_1^a, x_2^b, x_3^c, x_4^d) \subset R}, where at least one of a, b, c and d is equal to two, we prove that its generic initial ideal with respect to the reverse lexicographic order is the almost revlex ideal corresponding to the same Hilbert function.