Vibro-acoustic propagation of gear dynamics in a gear-bearing-housing system

This work developed a computational process to predict noise radiation from gearboxes. It developed a system-level vibro-acoustic model of an actual gearbox, including gears, bearings, shafts, and housing structure, and compared the results to experiments. The meshing action of gear teeth causes vibrations to propagate through shafts and bearings to the housing radiating noise. The vibration excitation from the gear mesh and the system response were predicted using finite element and lumped-parameter models. From these results, the radiated noise was calculated using a boundary element model of the housing. Experimental vibration and noise measurements from the gearbox confirmed the computational predictions. The developed tool was used to investigate the influence of standard rolling element and modified journal bearings on gearbox radiated noise.     

A Three-Color Fluorescent Supramolecular Nanoassembly of Phototherapeutics Activable by Two-Photon Excitation with Near-Infrared Light

A supramolecular nanoassembly, of about 30 nm in diameter, that consists of a green-fluorescent, β-cyclodextrin-based, branched polymer co-encapsulating a red-emitting singlet oxygen (¹O₂) photosensitizer and a nitric oxide (NO) photoreleaser, which comprises a blue fluorescent reporter, is here reported. The system exhibits “five-in-one” photofunctionalities. All components can be simultaneously excited in the phototherapeutic window with two-photons by using near-infrared light at 740 nm and despite their close proximity, behave as independent units. This allows for their in vitro visualization in carcinoma cancer cells, due to their distinct green, red, and blue fluorescence, and for the production of both cytotoxic ¹O₂ and biofunctional NO.     

Infrared spectroscopic study of O2 interaction with carbon nanotubes

Infrared reflection-absorption spectroscopic measurements have been performed on single-wall carbon nanotubes (SWNTs), cleaned by heating to approximately 500 degrees C in vacuo, during exposure to pure 16O2 or 18O2 at room temperature and at pressures of up to approximately 630 Torr. No vibrational signature of any form of adsorbed O is detected. However, structure is seen which is very similar to that observed for the adsorption of atomic H or D and which indicates changes in the SWNT vibrational spectrum. The close similarity between the spectra for atomic H and D, on one hand, and O2 on the other is an unexpected result. Changes are also noted in the broad background extending throughout the mid-IR which arises from the Drude contribution to the reflectance. All these effects increase with O2 exposure and are essentially irreversible upon evacuation of the gas. The results are consistent with other data indicating that O2 interacts only weakly with, and does not chemisorb on, pristine regions of the SWNT under these conditions. The small and irreversible effects seen upon O2 exposure are interpreted in terms of enhanced chemisorption, at or near defective regions of the SWNT wall, which saturates at a low O coverage.     

Proton-neutron correlations and the longitudinal nuclear response

We study the influence of the proton-neutron correlations, in particular of the tensor ones, on the longitudinal nuclear response. They generate a high-energy tail that we evaluate. We show that this tail produces an apparent quenching of the Coulomb sum rule. The amount of quenching found is significant, although insufficient to explain the totality of the missing strength.     

The chemical synthesis and antiviral properties of an acyclovir-phospholipid conjugate

The synthesis of acyclovir-phospholipid conjugate (2) is reported through an unambiguous one-step preparation of L-alpha-dimyristoyl phosphatidic acid triethylammonium salt (5). The biological activity of 2 as an antiviral drug has also been investigated.     

Nuclear critical opalescence,a precursor to pion condensation

It is shown that pion condensation in nuclei, a long-range phenomenon, has a precursor in the disordered phase, the local ordering of spins which becomes of infinite range at the critical point. A new physical effect arising from this short-range order is predicted, namely the enhancement of the static nuclear pion field near the critical momentum. This phenomenon is strongly reminiscent of the critical opalescence observed in the scattering of neutrons by antiferromagnetic substances.     

The electromagnetic polarizability and the swelling of nucleons in the nucleus

We discuss the modifications of the e.m. polarizability and of the charge radius of a nucleon embedded in the nuclear medium. For a free nucleon these structure constants are influenced by the pion cloud. The distortion of this cloud by the nuclear environment produces an appreciable enhancement of the two constants. The implications for the deep inelasticee′ experiments is discussed.     

High-performance liquid chromatographic quantitation of trimethoprim, sulfamethoxazole, and N4-acetylsulfamethoxazole in body fluids

We describe a rapid, precise and simple procedure for the quantitative determination of trimethoprim, sulfamethoxazole, and N4-acetylsulfamethoxazole in body fluids by reversed-phase high-performance liquid chromatography. This method utilizes antipyrine as an internal standard with the compounds detected by dual-wavelength monitoring at 225 nm and 254 nm after a single-step extraction. Precision, sensitivity, and accuracy of this assay are within the range of clinical utility; the coefficient of variation is less than or equal to 3%, sensitivity less than 0.5 micrograms/ml for all compounds, and recovery greater than 97%. The short time for performance and small sample size makes the assay ideal for clinical drug monitoring and pharmacokinetic studies.     

Pion bound states in nuclei

Bound π-nuclear states can appear under certain realistic conditions in finite nuclei. The best prospects are certain medium-weight nuclei with dense central regions and large neutron excess. Numerical illustrations are given for ¹⁶O, ²⁸Si, ³²Na and ²⁰⁸Pb with realistic parameters for the interaction. Further, we show that the usual low-energy π nuclear potential develops pathological features like an infinity of bound states beyond a certain critical strength. The natural remedies are indicated.     

How accurately can the deuteron radius be determined?

The theoretical uncertainty in the correction term due to nucleon finite size is found to be of the order of 1–2% (i.e., ± 0.1% inr _d). It must be considered in the experimental analysis.