In-die evaluation of capping tendency of pharmaceutical tablets using force-displacement curve and stress relaxation parameter

A novel in-die evaluation method of tablet capping tendency was proposed based on a force-displacement curve and stress relaxation parameter in a tableting process. In our previous study (Chem. Pharm. Bull., 59, 2011, Nakamura et al.), the phase diagram consisting of elastic recovery energy (E(e)) and plastic deformation energy (E(p)) of compressed powder, named as the E(e)-E(p) diagram, was proposed. However, it was found that capping tendency of tablets prepared by double-compression with multi-component powder formulations cannot be discriminated using the E(e)-E(p) diagram. To improve the capping discrimination ability, we here proposed a novel corrected phase diagram consisting of the E(e) and an interparticle bonding parameter E(b)(t), named as the E(e)-E(b)(t) diagram. The E(b)(t) was proposed as a new parameter expressing strength of the interparticle bonding formed by the stress relaxation inside compressed powder. The E(b)(t) was defined as a product of the E(p) and the stress relaxation parameter Y(t), estimated from the force-displacement curve and the stress relaxation test. The capping discrimination ability of the diagrams was evaluated using a hierarchical-clustering analysis. The results exhibited that the capping tendency could be clearly discriminated using the proposed E(e)-E(b)(t) diagram at the double-compression and the multi-component powder formulations, as compared to the E(e)-E(p) diagram. This proposed diagram can be used for screening of the powder formulations to avoid the capping.     

Desorption/ionization efficiency of peptides containing disulfide bonds in matrix-assisted laser desorption/ionization mass spectrometry

In order to elucidate the role of desorption/ionization efficiency of peptides in MALDI-MS, we focused on peptides with disulfide bonds, which form a rigid tertiary structure. We synthesized seven sets of peptides with one disulfide bond (oxytocin, somatostatin, [Arg(8)]-vasopressin, [Arg(8)]-vasotocin, cortistatin, melanin-concentrating hormone, urotensin II-related peptide) and five sets of peptides with two disulfide bonds (tertiapin, α-conotoxin GI, α-conotoxin ImI, α-conotoxin MI and α-conotoxin SI). Each peptide set consisted of three peptides: the oxidized form (S-S type), the reduced form (SH type), and an internal standard peptide in which all cysteine residues were substituted with alanine residues. In the case of urotensin II-related peptide, tertiapin, α-conotoxin ImI and α-conotoxin MI, the reduced form showed higher desorption/ionization efficiency than the oxidized form. In contrast, the other peptides revealed higher desorption/ionization efficiency in the oxidized form relative to the reduced form. These results imply that a rigid structure of peptides formed by disulfide bonds does not correlate with desorption/ionization efficiency in MALDI-MS.     

Rapid synthesis of gold nanorods by the combination of chemical reduction and photoirradiation processes; morphological changes depending on the growing processes

Combination of chemical reduction of tetrachloroaurate by ascorbic acid and subsequent ultraviolet photoirradiation resulted in the quick generation of gold nanorods quantitatively, with appreciable shape changes as the reaction proceeds.     

Hinge sugar as a movable component of an excimer fluorescence sensor

[reaction: see text] The ring flip of a carbohydrate is employed for the tongs-like movable component of a metal ion sensor. A pair of separated pyrene groups attached to the carbohydrate component are placed side by side when it recognizes metal ions, affording excimer fluorescence. This novel molecular sensor is selective for Zn(2+) and Cd(2+).     

Selective detection of minor prototropic tautomers in low-symmetry tetraazaporphyrin derivatives by the combined use of electronic absorption, MCD, and CI calculations

A series of low-symmetry metal-free tetraazaporphyrin (TAP) derivatives, i.e. monobenzo-substituted (1H2), adjacently dibenzo-substituted (2AdH2), oppositely dibenzo-substituted (2OpH2), and tribenzo-substituted (3H2) TAP derivatives, has been investigated by the combined use of electronic absorption, MCD, and CI calculations, proving the existence of two prototropic tautomers in 1H2 and 3H2.     

Temperature-induced sedimentation to dispersion of ionic vesicles

We present a temperature-induced sedimentation/dispersion transition of ionic vesicles in the system of alkyldimethylamine oxide hemihydrochloride (CnDMAO.1/2HCl) with a hydrocarbon chain length of 12-16 (n = 12, 14, and 16) and sodium 2-naphthalenesulfonate (NaNphS). The temperature-sensitive sedimentation/dispersion of ionic vesicles took place around a temperature of 50 degrees C, which was weakly dependent on the alkyl chain length. The combined effect of the thermally induced dissociation of the counterions from the vesicle and a hydrogen bonding between the nonionic and the cationic head groups is likely to be responsible for this unique behavior.     

Synthesis of bisubstrate and donor analogues of sialyltransferase and their inhibitory activities

[reaction: see text] Sialyltransferases (STs) are involved in the biosynthesis of glycoconjugates with important biological activities. Most STs utilize cytidine-5'-monophospho-N-acetylneuraminic acid (CMP-Neu5Ac) as a common donor substrate. A bisubstrate analogue containing the donor substrate (CMP-Neu5Ac mimic) and the acceptor substrate (galactose) was synthesized. Four donor analogues having the partial structure of the bisubstrate analogue were also synthesized to support study of the structure-activity relationship. Each analogue contains an ethylene group in place of the exocyclic anomeric oxygen of CMP-Neu5Ac. The bisubstrate analogue exhibited only weak inhibitory activity to rat recombinant alpha-2,3- and alpha-2,6-ST (IC(50) = 1.3, 2.4 mM). Conversion of the C-1 carboxylate of the Neu5Ac moiety to carboxyamide, hydroxymethyl, or methylene phosphate each resulted in a reduction in inhibitory activity. Among the synthesized analogues, cytidin-5'-yl sialylethylphosphonate (4) was the most potent inhibitor against rat recombinant alpha-2,3- and alpha-2,6-ST (IC(50) = 0.047, 0.34 mM).     

Numerical simulation of a nonequilibrium plasma jet in an applied magnetic field using three-fluid model

A three fluid model is applied for the numerical simulation of the axisymmetric flow and temperature fields in a nonequilibrium argon plasma jet which can be controlled by applying art electromagnetic field. The effects of the magnetic field on the characteristics of each plasma species, i.e., electrons, positive ions, and neutral particles, should be accurately clamed. The three-fluid model applied here can clarify the behavior of each plasma species. Equations of conservation for each plasma species coupled witli the generalized Ohm's law, Maxwell's equations, and the equation of state are simultaneously solved taking variable transport properties into account. It is shown that the electron temperature is the highest and the electron velocity is strongly influenced by the magnetic field. Furthermore, the momentum and energy exchanges through electrons can be varied even by a small magnetic flux.Nomenclature B magnetic flux density (T) - c mathematical mean thermal velocity (m/s) - C _p specific heat at constant pressure (J/(kg · K)) d ₀ nozzle diameter (m) - e electron charge (C) - E electric field (V/m) - E effective electric field (V/m) - Ex ^* energy transfer by collision - g relative velocity (m/s) - G partition function - h enthalpy (J/kg) - h _Planck Planck's constant (J · s) - H diffusion enthalpy (J/kg) - j ^* current density (j/en ₀ u ₀ - k Boltzmann constant (J/K) - l mean free path length (m) - L ₀ length of calculation domain along stream (m) - m mass (kg) - M ^* momentum transfer by collision - n number density (m^–3) - production rate of species [/(m³ · 3)] - p pressure (Pa) - collision cross section (m²) - q heat flux (W/m²) - r radial coordinate (m) - r _in inner radius of round tube (m) - R gas constant (J/(kg · K)) - R _in magnetic Reynolds number (=u ₀ d ₀₀µ₀) - s ion slip coefficient [=( _n /gr ₂)² _{e i} ] - S ₁ cross section parameter (m²/J) - T temperature (K) - u axial component of velocity (m/s) - U axial component of diffusion velocity (m/s) - radial component of velocity (m/s) - V radial component of diffusion velocity (m/s) - w peripheral component of velocity (m/s) - W peripheral component of diffusion velocity (m/s) - z axial coordinate (m) - degree of ionization [=n _e /)n _e +n _i +n _n )] - Hall parameter (= ) - ₀ permittivity in vacuum (F/m) - ge ₁ first excitation energy (J) - _ion ionization energy (J) - viscosity (Pa · s) - peripheral coordinate - thermal conductivity [W/(m · K)] - µ₀ permeability in vacuum (H/m) - density (kg/m³) - electrical conductivity (S/m) - mean collision time (s) - cyclotron frequency (Hz) Suffix 0 nozzle exit - e electron - i ion - n neutral particle - r radial component - s plasma species ofs kinds - z axial component - gq peripheral component Originally published inTrans. of the Japan Society of Mechanical Engineers, Ser.B,60, No. 577, 3072–3079 (1994) (in Japanese).