Analysis of elastic waves from two-point strain measurement

Provided that the one-dimensional wave equation applies, strain measurement at two sections of a linearly elastic cylindrical rod makes it possible to determine a number of important quantities at an arbitrary section of the rod; for example, strain, particle velocity and power transmission. The equations needed are derived, and the design of an analogue real-time analyzer is presented. The influence of some principal sources of error is analyzed and it is shown that it should be possible to perform accurate evaluation (errors less than a few percent) during a time interval which is not very long compared to the travelling time for a wave between the two gage positions. Comparisons are made between direct measurement and digital evaluation of strain, and between digital and analogue evaluation of particle velocity and power transmission. The discrepancies are typically less than ten percent during a time interval of 20 travelling times between gages. Although these results do not represent what is achievable, the accuracy is sufficient in several applications and demonstrates the feasibility of the method used.     

Determination of natural radiative lifetimes for S and D states in rubidium and cesium using a pulsed dye laser

Using delayed-coincidence techniques we have measured the natural radiative lifetimes of several S and D states in Rb and Cs. The states were excited by a pulsed dye laser from the first P state, populated using an rf discharge lamp.     

An efficient method for measuring atomic and molecular lifetimes using a modulated or deflected CW dye laser beam

By pulse modulating or deflecting a CW dye laser beam, cascade-free lifetime determinations at high spectral resolution can be performed with the decayed-coincidence technique using measuring times of about 1 minute. The method is illustrated by lifetime measurements for the $\text{7}{}^2\text{P}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext><mtext>1</mtext><mtext>2</mtext>}}$ levels of cesium.     

Measurement of the hyperfine structure splitting for the 4 and 52 P 1/2 states of sodium using radio-frequency spectroscopy

The hyperfine-structure splitting for the 4 and 5² P ^1/2 states of sodium was measured using step-wise laser excitation combined with rf-resonance techniques. The magnetic dipole interaction constants were found to be a(4² P _1/2)=30.4(5) MHz and a(5₂ P _1/2) =13.3(2) MHz. The results are compared with a theoretical calculation, taking polarization effects into account.     

Dalitz plot analysis of the decay D(+)-->K(-)pi(+)pi(+) and indication of a low-mass scalar Kpi resonance

We study the Dalitz plot of the decay D(+)-->K(-)pi(+)pi(+) with a sample of 15090 events from Fermilab experiment E791. Modeling the decay amplitude as the coherent sum of known Kpi resonances and a uniform nonresonant term, we do not obtain an acceptable fit. If we allow the mass and width of the K(*)(0)(1430) to float, we obtain values consistent with those from PDG but the chi(2) per degree of freedom of the fit is still unsatisfactory. A good fit is found when we allow for the presence of an additional scalar resonance, with mass 797+/-19+/-43 MeV/c(2) and width 410+/-43+/-87 MeV/c(2). The mass and width of the K(*)(0)(1430) become 1459+/-7+/-5 MeV/c(2) and 175+/-12+/-12 MeV/c(2), respectively. Our results provide new information on the scalar sector in hadron spectroscopy.     

Hyperbranched copolymer micelles as delivery vehicles of doxorubicin in breast cancer cells

Four types of drug nanoparticles (NPs) based on amphiphilic hyperbranched block copolymers were developed for the delivery of the chemotherapeutic doxorubicin (DOX) to breast cancer cells. These carriers have their hydrophobic interior layer composed of the hyperbranched aliphatic polyester, Boltorn^® H30 or Boltorn^® H40, that are polymers of poly 2,2‐bis (methylol) propionic acid (bis‐MPA), while the outer hydrophilic shell was composed of about 5 poly(ethylene glycol) (PEG) segments of 5 or 10 kDa molecular weight. A chemotherapeutic drug DOX, was further encapsulated in the interior of these polymer micelles and was shown to exhibit a controlled release profile. Dynamic light scattering and transmission electron microscopy analysis confirmed that the NPs were uniformly sized with a mean hydrodynamic diameter around 110 nm. DOX‐loaded H30‐PEG10k NPs exhibited controlled release over longer periods of time and greater cytotoxicity compared with the other materials developed against our tested breast cancer cell lines. Additionally, flow cytometry and confocal scanning laser microscopy studies indicated that the cancer cells could internalize the DOX‐loaded H30‐PEG10k NPs, which contributed to the sustained drug release, and induced more apoptosis than free DOX did. These findings indicate that the H30‐PEG10k NPs may offer a very promising approach for delivering drugs to cancer cells. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012