Stamp collapse in soft lithography

We have studied the so-called roof collapse in soft lithography. Roof collapse is due to the adhesion between the PDMS stamp and substrate, and it may affect the quality of soft lithography. Our analysis accounts for the interactions of multiple punches and the effect of elastic mismatch between the PDMS stamp and substrate. A scaling law among the stamp modulus, punch height and spacing, and work of adhesion between the stamp and substrate is established. Such a scaling law leads to a simple criterion against the unwanted roof collapse. The present study agrees well with the experimental data.     

Mechanism of sorption of phenols from aqueous solutions onto surfactant-modified montmorillonite

Equilibrium and kinetic studies on the sorption of phenol, m-nitrophenol (m-NP), and o-cresol from water onto montmorillonite modified with cetyltrimethylammounium bromide (CTAB) were conducted. Experiments were carried out as a function of solution pH, sorbate concentration, and temperature (25-55 degrees C). It was shown that the sorption capacity decreased in the order phenol>o-cresol>m-NP. The Langmuir, dual-mode sorption, and Redlich-Peterson models were tested to fit the sorption isotherms of single-solute systems, whereas the Langmuir competitive model was used to describe bisolute sorption equilibria. Thermodynamic parameters (DeltaH degrees and DeltaS degrees ) and the mean free energy (E) for the sorption of phenols were determined from the temperature dependence of the distribution constant and the Dubinin-Radushkevick equation, respectively. A simplified kinetic model was proposed to confirm the sorption mechanism.     

Primitive Representations by Spinor Genera of Ternary Quadratic Forms

Let a be primitively represented by the genus of a ternary quadraticlattice L defined over the ring of integers of an algebraicnumber field F. Criteria to determine whether a is primitivelyrepresented by every spinor genus in the genus of L involvecertain subgroups *(L_p, a) of the multiplicative groups of thelocalizations F_p of F with respect to the various nonarchimedeanprime spots p on F. In this paper these groups *(L_p, a) aredetermined explicitly for nondyadic and 2-adic prime spots.Examples are given which show how this information can, in someinstances, be used in combination with known results, to determineall integers primitively represented by a particular positivedefinite ternary quadratic form.     

A comprehensive survey of the INAA of reference materials

The nature of summary reports now being prepared for issuance, summarizing the results of detailed INAA Advance Prediction Computer Program (APCP) calculations for many widely used reference materials, is discussed and illustrated. For each material, the best photopeak % _rel value (where it is10%) is shown for each of the 12 condition sets (t_i/t_d/t_c) calculated from the input elemental composition. These summary reports will be very useful to groups that use various reference materials as multi-element standards.     

A new penalty parameter for linearly constrained 0–1 quadratic programming problems

The equivalence between the linearly constrained 0–1 quadratic programming problem and the continuous quadratic programming problem is studied in this note. Specifically, we show that the existing penalty parameter from the literature can be further improved.     

Conformation and Hydrolytic Stability of Polysaccharide from Xanthomonas campestris

Xanthomonas campestris polysaccharide in the solid state is stable to 225°C in air and 250°C in inert atmosphere. In solution, even at moderate temperatures, the polymer undergoes hydrolytic degradation via the glycosidic linkages, and occurrence of main-chain scission results in lower solution viscosity. In solution, the polymer can exist in ordered and disordered conformations. In distilled water at temperatures ≤ 50°C, the polymer exists in the disordered conformation. In the presence of salt, acid, or base the polymer exists in the ordered conformation. In the ordered conformation the polymer exhibits a far greater hydrolytic stability. The higher stability of the ordered conformation is especially demonstrated when the polymer is aged in acid or base solutions. Contrary to the expected lower stability of the glycosidic linkages in acid or base than in water, Xanthomonas campestris polysaccharide shows higher stability in these media.     

The MTE continuum relation with application to an argon arc at atmospheric pressure

The continuum emission coefficient relation for a plasma in Multithermal Equilibrium (MTE) is derived using the partial-MTE ionization equation. The results are presented in a form using the nonhydrogenic free-bound Gaunt factors of Schlüter. Measurements on a 200 A, 1 atm, constricted argon arc indicate that electron densities calculated from the MTE continuum relation and Schlüter's ξ_fb values exceed electron densities from the Stark broadening of H_β by 15–30%. Experimental values of ξ_fb are up to 3 times larger than Schlüter's values, but are in agreement with the values of Morris and Krey at 5 atm, which is probably one of the few similar experiments actually in or near complete LTE. In the present experiment at the arc axis: N_e(H_β) = 1.00 × 10¹⁷cm^-3 (±8%); T_e = 34,000 K (±20%); T_exa = 12,000 K (±3%); T_exβ = 9000 K (±5%); and T_a = T_i = 10,000 K (±68%). The probable errors reflect the need for more accurate transition probabilities which had an uncertainty of 25%.     

Downstream Conditions in a Constricted ARC with Radial Injection

The thermal, flow and electrical conditions are presented for the downstream portion of an argon arc with local fluid constriction. The arc is initially wall-stabilized in a 10 mm diameter water-cooled constrictor and at some point after flow becomes fully developed the arc is constricted by a radial inward jet. The redevelopment of the flow downstream of the injection slot is investigated by measurements of the pressure drop, wall heat flux and electric field. It is observed that redevelopment proceeds roughly as predicted by classical theory. Measurements of the electric field indicate that the region of maximum constriction is limited in extent.