MgBr2 · OEt2: A Lewis Acid Catalyst for the O- and N-Boc Protection of Phenols and Amines

MgBr₂ · OEt₂ efficiently catalyzes the O- and N-tert-butoxycarbonylation of functionalized phenols and amines. The presented procedure is operationally simple and done under solvent-free conditions.     

Mechanisms of electrochemical nitrogen gas reduction to ammonia under ambient conditions: a focused review

Journal of Solid State Electrochemistry - Electrocatalytic nitrogen reduction reaction (E-NRR) to ammonia is becoming a major topic of interest in the field of large-scale energy storage from...     

Application of synchronous fluorescence to parchment characterization

A nondestructive method for quantitative parchment characterization and sensitive indication of its deterioration stage was developed. Synchronous fluorescence (SF) measurements were applied for the first time to parchment samples. The method provides detailed spectral features, which are useful for parchment characterization. The discrimination of parchment samples into groups (modern, historical, and artificially aged) was successfully performed. The SF spectra could be resolved into specific fluorophores, which were related to the parchment condition. The spectral data indicate a continuous change in the collagen-to-gelatin ratio during the aging process. Depth-resolved synchronous fluorescence spectra were also measured. The data indicate that parchments possess a layered structure, and the dominant fluorophore in the upper layer is different from those in the lower layers. Layer-resolved profiling allows for quantifying the contribution of each fluorophore in each given layer. This way, significant differences between modern, artificially aged, and historical samples can be observed.     

Polyhedral functions and multiparametric linear programming

In a linear programming problem with a vector parameter appearing on the right-hand side, the minimum value of the objective is a polyhedral function of this parameter. We show how different characterizations of a polyhedral function correspond to different ways of solving the right-hand side multiparameteric linear programming problem.     

A further note on a diffusion problem with chemical reaction

Summary The problem of chemical reaction in an isothermal liminar-flow tubular reactor has been studied by Lauwerier for a first order irreversible reaction. The analysis of Lauwerier is extented in this work to include the case of consecutive irreversible first order reactions. Also the important numerical parameters have been calculated and are tabulated in this paper.     

The Fucik spectrum and critical groups

We compute critical groups of zero for variational functionals arising from semilinear elliptic boundary value problems with jumping nonlinearities when the asymptotic limits of the nonlinearity fall in certain parts of Type (II) regions between curves of the Fucik spectrum.

     

Dynamical stereochemistry of the hydrogen exchange reaction: A computational study

The barrier for the hydrogen exchange reaction increases with the bend angle of H₃. The implications for the dynamics of the reaction are explored on two levels. The static one uses the concept of a relaxed potential. This provides for a convenient, yet realistic representation. Itallows for the response of the molecule to the approaching atom. Among features made very evident by the relaxed potential is the possibility that hotH atoms can react by insertion. It also shows the widening of the cone of acceptance upon reagent vibrational excitation. On the dynamical level, classical trajectory computations are used to illustrate the dependence of the reactivity on the angle of attack and on the translational and vibrational excitation of the reagents. Detailed product distributions are generally not sensitive to the attack angle. An exception is the HD/H₂ branching ratio in H + HD reactive collisions.     

Resonance Problems Which Intersect Many Eigenvalues

We study semilinear problems in which the nonlinear part is linear at infinity but behaves like a function intersecting many of the eigenvalues of the linear operator. The asymptotic linear operator can have a null space of any finite dimension.     

On Functionals Bounded Below

In this paper, we prove that the infimum of a functional with a lower bound is a critical value. The novelty is that we do not need the Palais–Smale type condition.     

Landesman–Lazer resonance problems and saddle point methods

We show how saddle point techniques can be used to obtain new results for general resonance problems of the type considered by Landesman and Lazer.