Synthesis and Characterization,Including Cancer Cell Line Inhibition,of Group VA (Group 15)-Containing Polyesters from Reaction with Camphoric Acid

Polyesters were rapidly synthesized employing interfacial polymerization from reaction of the salt of camphoric acid with Group VA (Group 15) triphenylmetallic dihalides. Yields range from 25 to 46 percent with chain lengths about 250. Infrared spectroscopy shows the formation of two new bands one assigned to the symmetrical M–O stretching and the second assigned to the asymmetrical M–O stretching. The bridging structure about the metal atom increases as the metal atom size increases. MALDI MS and proton NMR are consistent with the formation of the polyester structure. Ion fragment clusters to four to six units are identified. The polymers show good inhibition of a group of cancer cell lines including two pancreatic human cancer cell lines. In comparison with other metal/camphoric acid polymers, the metallocene polymers exhibit low EC₅₀ to the nanogram/ml range, and CI₅₀ values greater than one thousand for the hafnocene and zirconocene products. If this trend continues, the emphasis should be on the Group IVB metallocenes with respect to efforts to create anticancer drugs.     

Horizontal Dip‐Spin Casting of aqueous alumina‐polyvinylpyrrolidone suspensions with chopped fiber

A novel ceramic processing method, called Horizontal Dip Spin Casting (HDSC), enabled fabrication of tubular ceramic parts with an aligned chopped fiber phase. HDSC was demonstrated using highly loaded aqueous alumina suspensions with >50 vol.% solids loading and ≤5 vol.% water‐soluble polymer employed as a rheological modifier. Chopped carbon fibers were added to the suspensions to attain maximum loadings of 30 vol.%. During forming, cylindrical foam molds were dipped into the suspension while being rotated radially about the long axis. Simultaneously, a doctor blade was placed at a specified distance from the foam surface to facilitate the flow of the suspension to align the fiber and control the thickness of the material that accrued on the mold. Rheological study of alumina‐PVP suspensions with and without chopped carbon fiber showed that the suspensions exhibited a yield‐pseudoplastic flow behavior. The degree of alignment of the carbon fiber phase in the green bodies was characterized for various suspension formulations, carbon fiber contents and forming speeds. Stereological characterization of green body specimens confirmed the effectiveness of HDSC to attain the desired tubular geometry with considerable fiber alignment for a suspension composition containing ≤20 vol.% chopped fibers.     

21世纪的加速老化测试

研究了老化试验科学在21世纪的状况,以及取得最新突破性成果之前的漫长征程。介绍了一个全新的突破性的ASTM测试方法的诞生。     

Characterization of Thiol‐Ene Crosslinked PEG Hydrogels

The properties of synthetic hydrogels can be tuned to address the needs of many tissue‐culture applications. This work characterizes the swelling and mechanical properties of thiol‐ene crosslinked PEG hydrogels made with varying prepolymer formulations, demonstrating that hydrogels with a compressive modulus exceeding 600 kPa can be formed. The amount of peptide incorporated into the hydrogel is shown to be proportional to the amount of peptide in the prepolymer solution. Cell attachment and spreading on the surface of the peptide‐functionalized hydrogels is demonstrated. Additionally, a method for bonding distinct layers of cured hydrogels is used to create a microfluidic channel.

     

SELF-ADHESION HYSTERESIS IN POLYDIMETHYLSILOXANE ELASTOMERS

The interphase between a polyimide and a metal substrate was modeled by depositing phthalic anhydride (PA) onto a silver substrate pretreated with meta-aminothiophenol (m-ATP) and then curing in a mixture of acetic anhydride and pyridine or triethylamine. Surface-enhanced Raman scattering (SERS) and reflection-absorption infrared spectroscopy (RAIR) were used to determine the molecular structure of the interphase. It was found that m-ATP was adsorbed dissociatively onto silver substrates through the thiol groups. The tilt angle for m-ATP molecules adsorbed on silver substrates was determined using RAIR to be approximately 39°. However, there was no preferred rotational angle of the adsorbed APDS molecules about the molecular axes. When PA was deposited onto m-ATP pretreated silver substrates, anhydride groups of PA reacted with amino groups of m-ATP to form amic acids. When PA/m-ATP/Ag samples were chemically cured in acetic anhydride and pyridine or triethylamine, isoimide was the predominant product regardless of the use of pyridine or triethylamine as catalyst. These results were different from those obtained from PA/APDS/Au systems in which imide was the major product in the presence of triethylamine. These differences in the relative composition of cured products between two model systems were explained by the effect of substituents attached to APDS and m-ATP benzene rings.     

GRAPHICAL TECHNIQUE FOR MODELING INTEGRATING (Non–SELF-REGULATING) PROCESSES WITHOUT STEADY-STATE PROCESS DATA

Model-fitting techniques for controller tuning that require the process to be initially at steady state cannot generally be used with integrating (non–self-regulating) processes. To address this issue, a graphical model-fitting technique is detailed and demonstrated for determination of first order plus dead time integrating model parameters from integrating process response plots. The resulting model parameters can be used directly in a range of tuning correlations designed specifically for integrating processes. The advantage of this technique is that it requires only two periods of constant manipulated and disturbance variables sustained just long enough for the process variable to respond and establish a clear slope. This is an important benefit because integrating processes generally cannot be maintained at an initial steady state as required when using techniques published for self-regulating processes. The result is an industry-friendly method. The method is demonstrated for level control in a pumped tank, a classical challenge in industrial practice. Both a simulation and a bench-scale experimental system are used in the demonstration studies.     

An ESR and Time-Resolved CIDEP Study of the Light-Induced Yellowing Processes of Tmp Paper

Integral ESR and time-resolved CIDEP techniques applied to the study of the light-induced yellowing of bleached and unbleached TMP samples provide some further insights into the nature and the mechanisms of the processes. The identity of the phenoxy and ketyl free radical intermediates involved in mese processes is established and the primary triplet photochemical mechanisms of their formation are characterized. The radical scavenging mechanisms responsible for the inhibition of light-induced yellowing in the TMP system by ascorbic acid and triphenylmethyl thiol are formulated.     

A Thermal Desorption Chemical Ionization Ion Trap Mass Spectrometer for the Chemical Characterization of Ultrafine Aerosol Particles

The development of a thermal desorption chemical ionization ion trap mass spectrometer for the chemical characterization of ultrafine aerosol particles is reported and first experimental results are presented. Atmospheric particles are size-classified and collected using a unipolar charger, a radial differential mobility analyzer and an electrostatic precipitator, and analyzed after thermal desorption and chemical ionization using an ion trap mass spectrometer. Integration of an ion trap mass spectrometer allows for fast scans of the entire mass spectrum every 0.5 s and bears the potential to identify unknown particulate compounds by tandem mass spectrometry. Particle collection efficiencies range from 90–100% for 25 nm particles to about 50% for 40 nm particles. In the current configuration, the absolute sensitivity of the instrument with regard to ammonium is in the range of 10–100 pg NH ⁺ ₄ . In ambient samples collected in the Colorado Front Range, NH ⁺ ₄ was the major signal peak in the positive ion spectrum, and additional minor signals and peak patterns of organic compounds including methylamine were found.     

Optimization of Open-end Rotor Spinning Frame Parameter and Estimation of Relevant Quality Characteristics

The high-cleaning Lyocell fibers are used to spin the Ne 32 yarns for an open-end rotor spinning frame. The optimal processing parameters were obtained in demonstrating output speed, stretching roller speed, feed speed and rotor revolution. The quality characteristics, such as yarn count, strength, elongation and Um (%), are far beyond the rating standard of the combed yarn. No yarn breaking for continuous spinning during the experimental confirmation. The result presents lower yarn breaking rate and maintains stabilized output status of spinning conditions. The back propagation neural network was employed for learning, forecast and verification of the processing parameters.