Filters,Antichains and Towers in Topological Spaces and the Axiom of Choice

We find some characterizations of the Axiom of Choice (AC) in terms of certain families of open sets in T₁ spaces.     

Intermolecular ‘oxidative’ aromatic substitution reactions of the imidazol-5-yl radical mediated by the ‘reductant’ Bu3SnH

The reactivity of the imidazol-5-yl in comparison to the imidazol-2-yl and phenyl radical under the reductive conditions of Bu₃SnH, in intermolecular substitution reactions onto various aromatic substrates is reported. The directing effect of the hetero atom or methyl substituent in aromatic substrates was found to be more important than the polarity of the attacking σ-radical in determining the major product isomer.     

A correspondence between a class of monoids and self-similar group actions I

We describe a correspondence between a class of left cancellative monoids and self-similar group actions in the sense of Nekrashevych et al. This correspondence originated in Perrot’s 1972 thesis, and developed the ideas to be found in Rees’ 1948 paper.     

New Liquid Metal Experimental Loop

In this paper we report the rebuilding of liquid metal experimental loop （LMEL） to avoid loop danger in running. In the new loop, We have eliminated the hidden trouble of the inherent safety in the former loop, obtained more stable magnetic field region, upgraded the reliability of the data acquisition and processing. New LMEL can provide the more extensive experiments on MHD effects and their thermal-hydraulics on the liquid metal divertor and the liquid metal blanket.     

Electrogenerated Nickel(I) complexes as catalysts for the intramolecular radical cyclisation of unsaturated α-bromoesters

The indirect electroreduction of unsaturated α-bromoesters using Ni(II) complexes as electron-transfer mediators is achieved in N,N′-dimethylformamide by constant current electrolysis between a cathode and a sacrificial anode in a diaphragmless cell. Cyclic compounds are obtained in moderate to good yields in conditions that avoid the usual preparation using organotin reagents.     

Benzodiazepine Alkaloids from Marine‐Derived Endophytic Fungus Aspergillus ochraceus

A new fungus‐derived benzodiazepine analogue, 2‐hydroxycircumdatin C ( 1 ), and a compound which has been isolated from a natural resource for the first time, but has been previously synthesized, namely (11aS)‐2,3‐dihydro‐7‐methoxy‐1H‐pyrrolo[2,1‐c][1,4]benzodiazepine‐5,11(10H,11aH)‐dione ( 2 ), along with five structurally related known alkaloids ( 3 – 7 ), were isolated from Aspergillus ochraceus, an endophytic fungus derived from the marine brown alga Sargassum kjellmanianum. Their structures were established on the basis of spectroscopic methods. The absolute configuration of 1 was determined through CD evidence. Compound 1 displayed significant DPPH radical‐scavenging activity with an IC₅₀ value of 9.9 μM , which is 8.9‐fold more potent than that of butylated hydroxytoluene (BHT), a well‐known synthetic positive control.     

Finite subgroups of ∨-semilatticed inverse semigroups

In this paper we describe the ∨-semilatticed inverse semigroups generated by a finite group G. We do this by first constructing the free ∨-semilatticed inverse semigroup ?(G) on the group G. Each ∨-semilatticed inverse semigroup generated by G is a quotient of ?(G) by a ∨-congruence. We then describe these congruences and their corresponding quotients explicitly in terms of families of subgroups of G.     

Enantiopure alkaloid analogues and iminosugars from proline derivatives: stereocontrol in sequential processes

An alternative to the use of expensive auxiliaries or catalysts in the synthesis of chiral 2-substituted pyrrolidines is described. Thus, commercial, cheap 4-(S)-hydroxyproline was readily transformed into optically pure pyrrolidines, using a one-pot decarboxylation-alkylation reaction as the key step. In this reaction, an acyliminium intermediate was generated, which was trapped by carbon nucleophiles. As postulated by Woerpel, the addition of the nucleophiles to the five-membered ring iminium ions took place stereoselectively, affording 2,4-cis-disubstituted pyrrolidines in high de. The hydroxy group at C-4 can then be removed, or alternatively, it can be used to create new functionalities in the molecule. In this way, optically pure alkaloid analogues and iminosugars were prepared.     

An orthogonal mapping technique for the computation of a viscous free-surface flow

In this paper we describe finite element computations of the free-surface flow of a viscous fluid down an undulating inclined plane. The technique developed here employs an orthogonal mapping that is computed along with the velocity and pressure. This is allied to a technique to compute symbolically the Jacobian and other derivatives required for numerical continuation methods. The solutions obtained are compared with laboratory experiments and finite element computations reported by Pritchard and co-workers. The finite element computational method used by these authors employs spines to represent the free surface. An excellent agreement is shown to exist between the new computations and the laboratory experiments, and with the numerical solutions of Pritchard and co-workers.     

New strategies in the synthesis of regioselectively trifluoromethyl- and trifluoromethoxy-substituted arenes as building blocks for biologically active molecules

Regioisomerically pure trifluoromethyl- and trifluoromethoxy-substituted aromatic and heteroaromatic aldehydes and carboxylic acids are valuable building blocks for the synthesis of biologically active molecules. They have been prepared by employing modern organometallic methods. On this basis, a novel access to 2,3-dihydro-5-(trifluoromethoxy)indole was developed which represents an intriguing example of how organometallic and radical chemistry can fecundate each other.