A multiple injection method for exerting kinetic control in the synthesis of CdSe nanorods

The thermolysis reaction of a dual precursor system, comprising one that promotes a controlled nucleation event to produce a rod-shaped nanocrystal template, and the other introduced through a subsequent series of injections that maintain the reaction under kinetic drive, is shown to provide a means of controlling growth of CdSe nanorods with a pre-determined aspect ratio.     

Proofs of the Parisi and Coppersmith‐Sorkin random assignment conjectures

Suppose that there are n jobs and n machines and it costs c_ij to execute job i on machine j. The assignment problem concerns the determination of a one‐to‐one assignment of jobs onto machines so as to minimize the cost of executing all the jobs. When the c_ij are independent and identically distributed exponentials of mean 1, Parisi [Technical Report cond‐mat/9801176, xxx LANL Archive, 1998] made the beautiful conjecture that the expected cost of the minimum assignment equals . Coppersmith and Sorkin [Random Structures Algorithms 15 ( 6 ), 113–144] generalized Parisi's conjecture to the average value of the smallest k‐assignment when there are n jobs and m machines. Building on the previous work of Sharma and Prabhakar [Proc 40th Annu Allerton Conf Communication Control and Computing, 20 , 657–666] and Nair [Proc 40th Annu Allerton Conf Communication Control and Computing, 17 , 667–673], we resolve the Parisi and Coppersmith‐Sorkin conjectures. In the process we obtain a number of combinatorial results which may be of general interest.© 2005 Wiley Periodicals, Inc. Random Struct. Alg. 2005     

A finite dimensional realization of the mollifier method for compact operator equations

We introduce and analyze a stable procedure for the approximation of where is the least residual norm solution of the minimal norm of the ill-posed equation , with compact operator between Hilbert spaces, and has some smoothness assumption. Our method is based on a finite number of singular values of and some finite rank operators. Our results are in a more general setting than the one considered by Rieder and Schuster (2000) and Nair and Lal (2003) with special reference to the mollifier method, and it is also applicable under fewer smoothness assumptions on .

     

Optical absorption and photoluminescence spectroscopy of the growth of silver nanoparticles

Results obtained from the optical absorption and photoluminescence (PL) spectroscopy experiments have shown the formation of excitons in the silver-exchanged glass samples. These findings are reported here for the first time. Further, we investigate the dramatic changes in the photoemission properties of the silver-exchanged glass samples as a function of postannealing temperature. Observed changes are thought to be due to the structural rearrangements of silver and oxygen bonding during the heat treatments of the glass matrix. In fact, photoelectron spectroscopy does reveal these chemical transformations of silver-exchanged soda glass samples caused by the thermal effects of annealing in a high vacuum atmosphere. An important correlation between temperature-induced changes of the PL intensity and thermal growth of the silver nanoparticles has been established in this Letter through precise spectroscopic studies.     

Benzannulation of 3-substituted pyrroles to indoles

In a new general indole synthesis, the anion derived from benzotriazolyl derivative 5b underwent regioselective 1,4-addition to various alpha,beta-unsaturated ketones; subsequent acid-catalyzed cyclization formed the corresponding indoles 1a-f.     

Unprecedented reactivity of N-heterocyclic carbenes toward DMAD and aldehydes leading to novel multicomponent reactions

A facile synthesis of highly functionalized 2-oxymaleate and furanone derivatives by the multicomponent reaction of 1,3-dimesityl imidazolin-2-ylidene/imidazol-2-ylidene, DMAD, and aldehydes is described.     

Novel synthesis of 2-arylbenzothiazoles mediated by ceric ammonium nitrate (CAN): a rebuttal

[reaction: see text] The reported synthesis of 2-arylbenzothiazoles mediated by ceric ammonium nitrate (CAN) is irreproducible; the only products formed in this reaction are bis-(p-tolyl) disulfide and p-tolyl p-toluenethiosulfonate.     

A comparison between Lanczos and moment methods

A simple procedure is suggested for generating the 2n - 1 Lanczos tridiagonal elements from the 2n - 1 moments of any hamiltonian with regard to a given starting vector. The numerical feasibility is studied in the quartic oscillator example.     

On non-Abelian Thomas-Fermi screening

The Thomas-Fermi screening of non-Abelian gauge fields by fermions or screening of gluon fields in quark matter is discussed. It is described by an effective mass term which is, as with hard thermal loops, related to the eikonal for a Chern-Simons theory and the Wess-Zumino-Witten action.     

Some comments on quark masses and baryon magnetic moments

The suggestion made by Lipkin regarding the quark masses and magnetic moments of baryons is examined in the context of the variable pressure bag model. We find that the exact agreement obtained by Lipkin between theory and experiment in the case ofμ(Λ) cannot be considered accidental, contrary to the scepticism expressed by Minami.