4-Acyl-2-acylamino-4,5-dihydro-1,3,4-thiadiazole durch Acylierung von Thiosemicarbazonen

4-Acyl-2-acylamino-4,5-dihydro-1,3,4-thiadiazoles by Acylation of Thiosemicarbazones Thiosemicarbazones and acid anhydrides or halides react to 4-acyl-2-acylamino-4,5-dihydro-1,3,4-thiadiazoles ( 2a – 2v ) in high yields. 3-Acyl-2-amino-4,5-dihydro-1,3,4-thiadiazoles 5 are proved as intermediates in this conversion. In special cases they can be isolated or submitted to further acylation with an other acylating agent. ¹H-n.m.r., ¹³C-n.m.r. and mass spectroscopic data of compounds 2a – 2v and 5a – 5e are given. The preparation of the compounds 2 can also be carried out starting with a carbonyl compound and thiosemicarbazide without isolation of the thiosemicarbazone.     

ortho-Spezifische Bromierung von Phenolen

Ortho-Specific Bromination of Phenols Phenol as well as 3-substituted phenols are brominated exclusively in the orthopositions by N.N-dibromomethylamine, yielding 2.6-dibrominated phenols in excellent yields. Phenols bearing an ortho-substituent need N-bromomethylamine as the brominating agent to take up one bromine atom into the free ortho-position. para-Bromination is not observed in either case. 1-Naphthol gives 2-bromo-1-naphthol, 8-hydroxyquinoline gives 7-bromo-8-hydroxyquinoline with 80% and 98% yield respectively. ortho-Specific chlorination of phenols was carried out in some cases using N-chloro-alkylamines.     

N-Aminierung von Isochinolinbasen

N-Amination of Isoquinoline Bases 3, 3-Pentamethylene oxaziridine 1 forms an N N-bond with secondary isoquinoline bases 2a – f to give the cyclohexylidene hydrazines 3a – f . In some cases nitrogen elimination yielding indane derivatives 13b, 13e competes with hydrazone formation. The cyclic Schiff'base 14 and the β-carboline derivative 16 can also be aminated.     

Neue Azoolefine und deren saure Spaltung zu Aryldiiminen

New Azoolefines and their Acidic cleavage to Aryldiimines 3-Amino-1-aryl-3′,3′-dimethyl-pyrazolin-4-spiro-2′-oxiran-5-ones ( 3a – c ) undergo ring opening with methoxide forming methyl 3-amino-3-arylazo-propenoates ( 5a – c ). 5a – c are cleaved under acidic conditions. The main products of the cleavage of 5c with methanolic hydrochloric acid are nitrogen, 2, 4, 6-trichloro-benzen ( 6 ), 2, 4, 6-trichloro-aniline ( 9 ) and 2, 4, 6-trichlorophenylhydrazine ( 10 ). Intermediates of the cleavage of 5 are aryldiimines trapped with benzaldehyde as the corresponding benzhydrazides ( 12a , b ).     

Ringöffnungs- und SubstitutionsReaktionen von 4,4-Dihalogen-pyrazolin-5-onen durch Nucleophile

Ring Opening and Substitution Reactions of 4,4-Dihalo-pyrazolin-5-ones with Nucleophiles 1-Aryl-4,4-dihalo-3-methyl-pyrazolin-5-ones ( 1a – c ) undergo ring opening with alkoxides and form alkyl 3-arylazo-2-halo-2-butenoats ( 2a – d ). Analogous reactions take place with ammonia and amines. 4-Nitro-phenoxide reacts with substitution of both halogens to the 4,4-bis(4-nitro-phenyl)-compound ( 5 ). Phenols are selectively orthobrominated by the title compounds 1a and b .     

Atomic Friction Investigations on Ordered Superstructures

We review recent friction measurements on ordered superstructures performed by atomic force microscopy. In particular, we consider ultrathin KBr films on NaCl(001) and Cu(001) surfaces, single and bilayer graphene on SiC(0001), and the herringbone reconstruction of Au(111). Atomically resolved friction images of these systems show periodic features spanning across several unit cells. Although the physical mechanisms responsible for the formation of these superstructures are quite different, the experimental results can be interpreted within the same phenomenological framework. A comparison between experiments and modeling shows that, in the cases of KBr films on NaCl(001) and of graphene films, the tip-surface interaction is well described by a potential with the periodicity of the substrate which is modulated or, respectively, superimposed with a potential with the symmetry of the superstructure.     

Associative Grammar Combination Operators for Tree-Based Grammars

Polarized unification grammar (PUG) is a linguistic formalism which uses polarities to better control the way grammar fragments interact. The grammar combination operation of PUG was conjectured to be associative. We show that PUG grammar combination is not associative, and even attaching polarities to objects does not make it order-independent. Moreover, we prove that no non-trivial polarity system exists for which grammar combination is associative. We then redefine the grammar combination operator, moving to the powerset domain, in a way that guarantees associativity. The method we propose is general and is applicable to a variety of tree-based grammar formalisms.     

Where the wind blows

The power systems in Denmark, Spain, Ireland, and New Zealand have some of the highest wind penetrations in the world (see Table 1). The management of the different power systems to date, with increasing amounts of wind energy, has been successful. There have been no incidents in which the wind has directly or indirectly been a major factor causing operational problems for the system. However, there are a number of parameters that are being monitored that indicate the need for active management in the near future (and in some cases already today). In this article, we briefly describe the situations in these four countries, giving special emphasis to the market integration of wind power, the use of wind forecasting, and curtailment experience. The final section provides an overview of the main wind forecasting methodologies and challenges.     

Parameter reference immutability: formal definition, inference tool, and comparison

Knowing which method parameters may be mutated during a method’s execution is useful for many software engineering tasks. A parameter reference is immutable if it cannot be used to modify the state of its referent object during the method’s execution. We formally define this notion, in a core object-oriented language. Having the formal definition enables determining correctness and accuracy of tools approximating this definition and unbiased comparison of analyses and tools that approximate similar definitions. We present Pidasa, a tool for classifying parameter reference immutability. Pidasa combines several lightweight, scalable analyses in stages, with each stage refining the overall result. The resulting analysis is scalable and combines the strengths of its component analyses. As one of the component analyses, we present a novel dynamic mutability analysis and show how its results can be improved by random input generation. Experimental results on programs of up to 185 kLOC show that, compared to previous approaches, Pidasa increases both run-time performance and overall accuracy of immutability inference.     

A new hypothesis to describe the mechanisms acting in a welded joint of semicrystalline thermoplastics

Since it is known that crosslinked polythylene can be worked, it is clear that the mechanics acting in the interior of a welded joint are not adequately explained yet. There are several criteria, hypotheses and models that attempt to describe what happens in a welded joint. In this paper, two new promising hypotheses, the Mixed Crystal Hypothesis and the Nexus Hypothesis, are introduced. The Mixed Crystal Hypothesis can be proven by the help of several different examination methods. Other examinations support the Nexus Hypothesis.