Long-term stability of glass electrodes in aqueous media

The stability of the potential of glass electrodes has been studied. The potential changes only slightly during the hydration of freshly etched electrodes. With glass electrodes previously used in alkaline solutions, structural transformations within the gel-layer give rise to large potential drifts in neutral or acidic test solutions. In alkaline solutions all glass electrodes are attacked, especially the low-temperature type, and the potential changes with time. Drying hydrated electrodes affects the stability only slightly. Alternating transfers between acidic and basic solutions decrease the stability. Recommendations for precise measurements with glass electrodes are given.     

The vibrational force field of halogenated aromatic molecules: V. The CH stretching field in fluoroaromatics

It is shown that the average CH stretching frequencies in the fluoroaromatic series C₆H_6?nF_n depend on the fluorine substitution patterns, being given by v? = v?_B + _noX_o + _nmX_m + n_pX_p. Two variants on the general quadratic force field, which are taken to be transferable between members of the series, have been fitted to the experimental data. Each ortho fluorine substituent increases the diagonal CH stretching force constant by 1.0%. The dependence on meta and para substituents is not as obvious as with the average stretching frequency due to the rather large variance. A comparison with existing correlations between average stretching frequencies and bond length data indicates that an ortho fluorine atom leads to a CH bond shortening of 0.0017 A. Such information could prove of value in microwave structural investigations.     

A new kind of iron-nitric oxide complex: the radical Fe(No)3CO

Photolysis of Fe(CO)₅ in non-polar solvents containing dissolved NO results in the generation of an EPR spectrum which is assigned to the free radical Fe(NO)₃CO.     

The structure of crotofolin E,A novel tricyclic diterpene from Croton corylifolius

A novel and highly functionalized crotofolane diterpene, crotofolin E ($\text{4}$), has been isolated from Croton corylifolius L. (Euphorbiaceae) and its stereostructure determined from spectral and X-ray crystall crystallographic analyses.     

Characterization of plasma polymer films of phenylsilane by X-ray photoelectron spectroscopy

Carbon 1s and silicon 2p X-ray photoelectron spectra of phenylsilane plasma polymer films prepared at substrate temperatures,T_s, between 50 and 450°C were recorded. The binding energies, lineshapes, and shake-up satellite intensities are in accordance with a structure consisting of a silicon network with pendant phenyl groups, and the minor dependence on T_s is consistent with the main effect of increasing preparation temperature being the loss of hydrogen and some pendant phenyl, with a concurrent increase in the interconnectivity of the network. The observed C 1s binding energy and linewidth specifically rule out the presence of any significant amount of carbon in silicon carbide form. A simultaneous shift of about 0.6 eV in the binding energies of both the C 1s and Si 2p lines is tentatively interpreted as a shift in the Fermi level with respect to the valence band edge.     

Therapeutic systems and controlled drug delivery

Therapeutic systems can provide pre-programmed, unattended delivery of a drug at a rate, and for a time period, established to meet a specific therapeutic need. The system can be designed to minimize the patient's intervention and to optimize compliance with the prescribed regimen. The ocular therapeutic system described here for the control of intraocular pressure in glaucoma delivers pilocarpine at 20 or 40 μg/h for one week, and fits comfortably into the cul-de-sac of the eye. The intrauterine progesterone contraceptive system described here represents a new approach to steroidal contraception that localizes the effect of the hormone progesterone to the uterus, delivering the hormone at a rate of 65 μg/day for one year. Both of these systems are designed to deliver drug into their immediate locale, and are thus topical dosage forms. The transdermal therapeutic system described here has been designed to deliver scopolamine across intact skin and into systemic blood to achieve an antinausea effect. The pharmacokinetics of scopolamine are such that, to minimize the time required for the onset of drug action, drug should be presented at an initially high rate, i.e. as a priming dose, to attain the therapeutically effective drug level, and then at a constant rate, so as to maintain the therapeutically effective level. This system functions according to the priming dose/maintenance rate design requirement.     

公共广播系统的应备功能

介绍了公共广播国家标准《公共广播系统工程技术规范》中关于公共广播系统应备功能的有关规定，并对这些规定进行了适当的讨论。