Bacteria-based AND logic gate: a decision-making and self-powered biosensor

We developed a bacteria-based AND logic gate using a Pseudomonas aeruginosa lasI/rhlI double mutant with two quorum-sensing signaling molecules as the input signals. We showed a distinct electrical output signal, despite the complexity and continuous regulation of metabolic reactions of living cells.     

Applying the Pfaffianization Procedure to the Two-Dimensional Leznov Lattice

We derive Wronskian and Grammian determinant solutions for the two-dimensional Leznov lattice and provide a Pfaffianized version of this Leznov lattice using Hirota and Ohta’s Pfaffianization procedure. We give the Gramm-type Pfaffian solution for the Pfaffianized system explicitly.__________Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 144, No. 3, pp. 484–491, September, 2005.     

Bounded harmonic maps on a class of manifolds

Without imposing any curvature assumptions, we show that bounded harmonic maps with image contained in a regular geodesic ball share similar behaviour at infinity with the bounded harmonic functions on the domain manifold.

     

Size-selected Ni catalyst islands for single-walled carbon nanotube arrays

Many properties of single-walled carbon nanotube (SWCNT) arrays are determined by the size and surface coverage of the metal catalyst islands from which they are nucleated. Methods using thermal fragmentation of continuous metal films frequently fail to produce size-uniform islands. Hybrid numerical simulations are used to propose a new approach to controlled self-assembly of Ni islands of the required size and surface coverage using tailored gas-phase generated nanocluster fluxes and adjusted surface temperatures. It is shown that a maximum surface coverage of 0.359 by 0.96–1.02 nm Ni catalyst islands can be achieved at a low surface temperature of 500 K. Optimized growth of Ni catalyst islands can lead to fabrication of size-uniform SWCNT arrays, suitable for numerous nanoelectronic applications. This approach is deterministic and is applicable to a range of nanoassemblies where high surface coverage and island size uniformity are required.

     

On the semiring of cone preserving maps

If K is a proper cone in Rⁿ, then the cone of all linear operators that preserve K, denoted by π(K), forms a semiring under usual operator addition and multiplication. Recently J.G. Horne examined the ideals of this semiring. He proved that if K₁, K₂ are polyhedral cones such that π(K₁) and π(K₂) are isomorphic as semirings, then K₁ and K₂ are linearly isomorphic. The study of this semiring is continued in this paper. In Sec. 3 ideals of π(K) which are also faces are characterized. In Sec. 4 it is shown that π(K) has a unique minimal two-sided ideal, namely, the dual cone of π(K¹), where K¹ is the dual cone of K. Extending Horne's result, it is also proved that the cone K is characterized by this unique minimal two-sided ideal of π(K). The set of all faces of π(K) inherits a quotient semiring structure from π(K). Properties of this face-semiring are given in Sec. 5. In particular, it is proved that this face-semiring admits no nontrivial congruence relation iff the duality operator of π(K) is injective. In Sec. 6 the maximal one-sided and two-sided ideals of π(K) are identified. In Sec. 8 it is shown that π(K) never satisfies the ascending-chain condition on principal one-sided ideals. Some partial results on the question of topological closedness of principal one-sided ideals of π(K) are also given.     

On indecomposable subcones

Let K₁,K₂ be cones. We say that K₁ is a subcone of K₂ if ExtK₁?ExtK₂. Furthermore, if K₁≠K₂, K₁ is called a proper subcone; if dimK₁=dimK₂, K₁ is called a non-degenerate subcone. We first prove that every n-dimensional indecomposable cone, n?3, contains a non-degenerate indecomposable subcone which has no more than 2n-2 extremals. Then we construct for each n?3 an n-dimensional indecomposable cone with exactly 2n-2 extremals such that each of its proper non-degenerate subcones is decomposable.     

Improved deprotection in solid phase peptide synthesis: quantitative reduction of methionine sulfoxide to methionine during HF cleavage

The reduction of methionine sulfoxide residues in peptides was found to be quantitative by treatment with a low concentration of HF in dimethylsulfide (HF:dimethylsulfide, 1:3, v/v). The reduction was dependent on the acidity function of HF and was optimal with an HF concentration between 25% and 40%. The low HF concentration cleavage reagent also deprotected most of the benzyl alcohol-derived protecting groups.     

Reaction of Isocyanates and Isothiocyanates with Butyraldazine; Formation of 1-Substituted 2-Pyrazolines

Phenyl isothiocyanate reacts with butyraldazine in presence of acidic catalysts to form a 2-pyrazoline (IV) whereas phenyl or benzyl isocyanates under similar conditions yield a mixture of the two isomeric 2-pyrazolines XIa and XII. On reaction with Ac₂O, IV gave the 1-acetyl derivative V. Reduction with LiAlH₄ led to the corresponding pyrazolidines. Reexamination of Kost's three step preparation of a 1-phenylthiocarbamoyl 2-pyrazoline [19] such as X via formic acid cyclization [18] of butyraldazine revealed that his first step product was apparently a mixture of two stereoisomeric 1-formyl-2-pyrazolines VIIIa and VIIIb. A mechanism for the formation of these pyrazolines is proposed.