Type inference in stack based languages

We consider a language of operations which pass parameters by means of a stack. An algebra over the set of type signatures is introduced, which allows the type signature of a program to be obtained from the type signatures of its constituent operations.Although the theories apply in principle to any stack based language, they have been evolved with particular regard to the proposed ANSI Standard Forth language, which is currently implemented in a type free manner. We hope this work will stimulate an interest in Forth amongst those applying algebraic techniques in software engineering, and we hope to lay the theoretical foundations for implementing practical type checkers to support Forth.     

Thin Film Adhesion: Effect of Glow Discharge on Substrate

Glow discharge treatment of soda lime glass and silica substrates prior to depositing copper films in oil-free ultra high vacuum as well as in conventional vacuum has been found to increase film adhesion suggesting that gross contamination removal is not the only effect of importance in this method of improving film adhesion. There is evidence from Auger electron emission spectroscopy for sorption of gas from the discharge into the substrate surface layers. Desorption of gases from the substrate also appears to take place. A difference in electron emission from a variety of insulating surfaces following glow discharge was observed in a scanning electron microscope, the sign of the change depending on the nature of the discharge gas. No sputtered material from system components could be detected on the substrate and there was no detectable micro-roughening nor net surface electric charge.     

Second-sphere Coordination of [Pt(bipy)(NH3)2]2+ by Dibenzo-crown Ethers. Solution Spectroscopic Studies and the Crystal and Molecular Structures of [Pt(bipy)(NH3)2.dibenzo-30-crown-10] [PF6]2.0.6 H2O and [Pt(bipy)(NH3)2.dibenzo-24-crown-8] [PF6]2

In addition to hydrogen bonding and Coulombic forces, charge transfer interactions stabilise the 1:1 adducts formed between [Pt(bipy)(NH₃)₂] ²⁺ and a series of dibenzo-3n-crown-n (n = 6–12) ethers as evidenced by ¹H NMR and UV-visible spectra in solution and by X-ray crystal structures (for n = 8 and 10) in the solid state. Mutual diamagnetic (ring current) shielding by the aromatic systems of host and guest results in dramatic upfield shifts of certain aromatic proton resonances on adduct formation, especially when n = 10 or 11. A broad charge-transfer absorption band at 350 nm attains its maximum intensity at n = 11 though stability constant measurements indicate optimum binding when n = 10. X-ray diffraction studies reveal that, when n = 8, only one of the crown ether benzo-rings interacts with the bipyridyl ligand in a charge-transfer sense. However, when n = 10, the macrocycle is sufficiently large and flexible to allow both benzo-rings to enter into stabilising interactions with the bipyridyl ligand such that the platinum complex is encapsulated by the host in a U-shaped cavity.     

Cyclodextrin-based carbohydrate clusters by amide bond formation

Per-6-amino-2,3-dimethyl-ß-cyclodextrin was prepared very efficiently as its hydrochloride salt from native ß-cyclodextrin in four steps and 89% overall yield. O-Acetyl-protected ß-D-thioglucose and ß-D-thiolactose derivatives, containing short spacer arms terminated with carboxylic acid functions, were prepared by the BF₃·OEt₂-catalyzed thioglycosylation of ß-D-glucose pentaacetate and ß-lactose octaacetate with 3-mercaptopropionic acid, respectively. Utilizing amide bond formation as the key step, these thio-ß-D-glucosyl and lactosyl derivatives were coupled to per-6-amino-2,3-dimethyl-ß-cyclodextrin to afford, after deprotection, perfunctionalized ß-cyclodextrin-based clusters containing seven thio-ß-D-glucosyl and seven ß-lactosyl appendages, respectively. Molecular modeling of both these ß-cyclodextrin-based clusters revealed the glucose and lactose clusters to be approximately 23 Å and 27 Å in diameter, respectively, and approximately 19 Å in height in both cases. The association constants for the complexation of the anti-inflammatory drug naproxen by ß-cyclodextrin, per-2,3-dimethyl-ß-cyclodextrin, and the lactose cluster of ß-cyclodextrin in 0.01 M phosphate buffered saline solution (pH 7.4) were found by UV-vis spectrophotometric titration to be 374 ± 75 M⁻¹, 351 ± 70 M⁻¹, and 165 ± 33 M⁻¹, respectively.