Pure drug nanoparticles in tablets: what are the dissolution limitations?

There has been increasing interests for drug companies to incorporate drug nanoparticles into their existing formulations. However, technical knowledge in this area is still in its infancy and more study needs to be done to stimulate growth in this fledging field. There is a need to scrutinize the performance of pure drug nanoparticles in tablets, particularly relating formulation variables to their dissolution performance. Application of the pure form, synthesized without the use of surfactants or stabilizers, is often preferred to maximize drug loading and also to minimize toxicity. Cefuroxime axetil, a poorly water-soluble cephalosporin antibiotic, was used as the model drug in the formulation development. Drug release rate, tablet disintegration time, tensile strength and energy of failure were predominantly influenced by the amount of super-disintegrant, amount of surfactant, compression force and diluent species, respectively. The compression rate had minimal impact on the responses. The main hurdle confronting the effective use of pure drug nanoparticles in tablets is the difficulty in controlling aggregation in solution, which could potentially be aggravated by the tabletting process. Through the use of elevated levels of surfactants (8 w/w% sodium dodecyl sulphate), drug release from the nanoparticle preparation was enhanced from 58.0 ± 2.7% to 72.3 ± 0.7% in 10 min. Hence, it is recommended that physical formulations for pure drug nanoparticles be focused on the particle de-aggregation step in solution, if much higher rates are to be desired. In conclusion, even though pure drug nanoparticles could be easily synthesized, limitations from aggregation may need to be overcome, before successful application in tablets can be fully realized.     

Double basses on the stage floor: tuning fork-tabletop effect, or not?

The question whether or not double basses can benefit from a compliant and radiating stage floor in the low end of their tonal register, similar to the well-known tuning fork-tabletop effect, was examined through field experiments in five concert halls. The topic comprises several aspects: (1) How well the mechanical impedances of double basses and the stage floor match, (2) amount of vibration velocity transmitted to the floor through the end pin of the bass, and (3) radiation efficiency of point-excited bending waves in the stage floor far below the coincidence frequency. Each aspect represents a prerequisite for the tuning fork-tabletop effect to take place. The input impedance at the end pin was measured for three representative double basses. The stage floors of five orchestra halls were measured with respect input impedance and damping, while sound radiation to the audience area was measured for two of them. In Lindeman Hall, Oslo, all conditions for the tuning fork-tabletop effect to take place were clearly met. The contribution from the stage-floor radiation to the sound pressure level in the audience area was found to be about 5 dB between 40 and 60 Hz, and even higher between 30 and 40 Hz.     

Collisional depolarization of rotational angular momentum: what are the observables and how can they be measured?

The destruction and transfer of polarization of the rotational angular momentum of small molecules in an isotropic collisional environment is reviewed. Several recent independent treatments are drawn together, including unpublished details from the authors' own work, of the formal kinetics in terms of moments of the density matrix. The final results are shown to be equivalent and directly amenable to comparison with results of exact quantum scattering calculations. In passing, some differences in nomenclature are noted and a self-consistent version is presented that might usefully be adopted. The existing experimental approaches are surveyed, within the common theme of laser-based creation of the initial rotational anisotropy of relatively low rank, K, combined with a spectroscopic probe, also sensitive to restricted K. Those formally defined quantities that may be measured are identified, either individually or in some combination, with each method. In particular, an attempt is made to distinguish between measurements of individual tensor moments of the density matrix, or ‘bulk polarizations’, and alignment moments, which are normalized to the population. Some cases are noted where experimental procedures have compromised the results, or where the analysis has been similarly approximate or carried out on a less rigorous empirical basis.     

Nanotechnology for sustainability: what does nanotechnology offer to address complex sustainability problems?

Nanotechnology is widely associated with the promise of positively contributing to sustainability. However, this view often focuses on end-of-pipe applications, for instance, for water purification or energy efficiency, and relies on a narrow concept of sustainability. Approaching sustainability problems and solution options from a comprehensive and systemic perspective instead may yield quite different conclusions about the contribution of nanotechnology to sustainability. This study conceptualizes sustainability problems as complex constellations with several potential intervention points and amenable to different solution options. The study presents results from interdisciplinary workshops and literature reviews that appraise the contribution of the selected nanotechnologies to mitigate such problems. The study focuses exemplarily on the urban context to make the appraisals tangible and relevant. The solution potential of nanotechnology is explored not only for well-known urban sustainability problems such as water contamination and energy use but also for less obvious ones such as childhood obesity. Results indicate not only potentials but also limitations of nanotechnology??s contribution to sustainability and can inform anticipatory governance of nanotechnology in general, and in the urban context in particular.     

What are the bounds on space-time non-commutativity?

In this article we consider the bounds on the non-commutative nature of space-time. We argue that these bounds are extremely model dependent. In the only phenomenologically viable framework, i.e. when the fields are taken to be in the enveloping algebra, the constraints are fairly loose and only of the order of a few TeV. We concentrate on the most stringent bounds that come from clock comparison experiments. In the framework where fields are taken in the enveloping algebra, they are model independent since these bounds are independent on choices involved with the Seiberg-Witten maps.Received: 6 July 2004, Revised: 20 December 2004, Published online: 21 April 2005     

Inductive and mesomeric effects on the π orbitals of halobenzenes

Ionization potentials for the π bands of a wide range of fluoro-, chloro-, and bromobenzenes have been measured by the technique of photoelectron spectroscopy. An empirical model incorporating inductive and mesomeric terms is discussed and its validity tested with the observed energies. Satisfactory agreement is obtained with dipole moment data. The theory accurately predicts ionization energies only for molecules having no ortho halogen atoms. Deviations from linearity are adequately explained in terms of an ortho effect which is proportional to the number of halogens situated in ortho positions. An analogous effect has previously been observed in the electronic spectra of substituted benzenes. Application of the model to 1a _2u band shifts in the fluorobenzenes leads to the conclusion that the energy of this band in benzene lies in the region of 11·5 eV.     

Pressure and temperature effects on the Γ, N and L-phonons in zirconium

Abstract

The effective potentials for the E_2g,-phonon at the T point of the Brillouin zone of hep Zr, the transverse N- and longitudinal L-phonons of bcc Zr are calculated for different pressures by the “frozen phonon” method. The temperature and pressure dependences of the phonon frequencies are studied within the framework of a modified pseudo-harmonic approximation. The results obtained are in good agreement with the experimental ones. The stability of the hep, bec and ω phases of zirconium at different temperatures and pressures is discussed.     

Comparison between the effects of ultrasound and γ-rays on the inactivation of Saccharomyces cerevisiae: Analyses of cell membrane permeability and DNA or RNA synthesis by flow cytometry

The effects of 200 kHz ultrasonic irradiation on DNA or RNA formation and membrane permeability of yeast cells were investigated by flow cytometry and compared with those of ⁶⁰Co γ-ray radiation. Colony counting analyses were also performed for comparison. It was observed that the colony-forming activity of yeast cells was not affected by small doses of ultrasonic irradiation, but was closely related to the amounts of sonolytically formed hydrogen peroxide at concentrations of more than 80 μM. On the other hand, γ-rays directly retarded colony-forming ability in addition to the effects of radiolytically formed hydrogen peroxide. The results obtained by flow cytometry also indicated that the amounts of DNA or RNA formed decreased with an increase in ultrasonic irradiation time without any threshold. These results indicated that flow cytometry can show early growth activities, but that colony counting analyses are insufficient to evaluate continuous and quantitative changes in these activities. In addition, by analyzing the amounts of DNA or RNA formed in the presence of the same amount of hydrogen peroxide, it was found that DNA or RNA formation behavior in the presence of hydrogen peroxide with no irradiation was similar to that following ultrasonic irradiation. These results suggested that similar chemical effects due to the formation of hydrogen peroxide were produced during ultrasonic irradiation. In addition, physical effects of ultrasound, such as shock wave, hardly contributed to cell inactivation and cell membrane damage, because relatively high frequency ultrasound was used here. In the case of γ-ray radiation, direct physical effects on the cells were clearly observed.     

Critical review on lithium-ion batteries: are they safe? Sustainable?

The goal of this critical review is to explain why the safety problem raised by the lithium batteries must be considered. The performance of the batteries with different chemistries is compared and analyzed, with emphasis on the safety aspects, in addition to the electrochemical properties of the cells. Problems encountered with cathode materials (layered compounds, spinel and olivine), anode materials (graphite and lithium titanate), electrolytes, lithium salts, and separators are pointed out. In this critical review, we also discuss the place of the lithium batteries in the context of sustainable energies (electric vehicles, smart grid).     

Asymmetry and speed-dependent effects on the 748.8 nm self-broadened neon line

Using an interferometric method, detailed analysis of the self-broadened 748.8 nm Ne line shapes emitted from the glow discharge of neon was performed, where departures from the ordinary Voigt profile were observed. These departures are shown to be consistent with fits of the speed-dependent asymmetric Voigt profile to experimental profiles. It was shown that neglecting the correlation between Doppler and collisional broadening may cause errors in determined line shape parameter values. Coefficients of the pressure broadening, shift and collision-time asymmetry are determined and compared with those calculated in the adiabatic approximation for the van der Waals and Lennard-Jones potentials.     

What are the differences between Hantzsch ester and H2 as two‐hydrogen‐atom donors in acetonitrile on the thermodynamics of elementary steps?

Thermodynamic driving forces of eight possible elementary steps for Hantzsch ester and six possible elementary steps for H₂ to release two hydrogen atoms (2H^?) or ions (H^? and H⁺) in acetonitrile were examined using experimental method or the available related thermodynamic data for the first time, which can facilitate chemists to choose a suitable reducing agent between Hantzsch ester and H₂ to reduce a given organic unsaturated compound in acetonitrile and make a rational diagnosis on the detailed reaction mechanisms. The focus of this paper is to compare the differences between Hantzsch ester and H₂ to release two hydrogen atoms (or ions) on the thermodynamics of elementary steps in acetonitrile. Copyright © 2016 John Wiley & Sons, Ltd.     

Sonication effects on non-radical reactions. A sonochemistry beyond the cavitation?

The kinetics of pH-independent hydrolysis of 4-methoxyphenyl dichloroacetate were investigated under ultrasonic irradiation with an application of 10% of the maximum power of the equipment and without sonication in acetonitrile–water binary mixtures with a content of acetonitrile ranging from 0.008 to 35 wt.%. Similar kinetic investigations were performed at intensities corresponding to 10%, 20%, 30%, 40%, and 50% of the input energy in solvent mixtures containing 10 wt.% and 25 wt.% acetonitrile. In parallel, the responses of KI and terephthalic acid dosimeters at applied irradiation levels were registered under the same experimental conditions. Significant kinetic sonication effects were found at sound intensities presumably not inducing cavitation in the solution. This result provides an experimental evidence of kinetic effects of ultrasound in the absence of cavitation. A disturbing impact of cavitation on the ultrasonic acceleration of the reaction was found. The implications of these findings were discussed.     

Numerical analysis of the effects of radiation heat transfer and ionization energy loss on the cavitation Bubble?s dynamics

A numerical scheme for simulating the acoustic and hydrodynamic cavitation was developed. Bubble instantaneous radius was obtained using Gilmore equation which considered the compressibility of the liquid. A uniform temperature was assumed for the inside gas during the collapse. Radiation heat transfer inside the bubble and the heat conduction to the bubble was considered. The numerical code was validated with the experimental data and a good correspondence was observed. The dynamics of hydrofoil cavitation bubble were also investigated. It was concluded that the thermal radiation heat transfer rate strongly depended on the cavitation number, initial bubble radius and hydrofoil angle of attack.     

Nanotechnology,voluntary oversight,and corporate social performance: does company size matter?

In this article, we examine voluntary oversight programs for nanotechnology in the context of corporate social performance (CSP) in order to better understand the drivers, barriers, and forms of company participation in such programs. At the theoretical level, we use the management framework of CSP to understand the voluntary behavior of companies. At the empirical level, we investigate nanotech industry participation in the Environmental Protection Agency’s Nanoscale Materials Stewardship Program (NMSP) as an example of CSP, in order to examine the effects of company characteristics on CSP outcomes. The analysis demonstrates that, on the average, older and larger companies for which nanotech is one of the many business activities demonstrate greater CSP as judged by company actions, declarations, and self-evaluations. Such companies tended to submit more of the requested information to the NMSP, including specific information about health and safety, and to claim fewer of the submitted items as confidential business information. They were also more likely to have on-line statements of generic and nano-specific corporate social responsibility principles, policies, and achievements. The article suggests a need to encourage smaller and younger companies to participate in voluntary oversight programs for nanotechnology and presents options for better design of these programs.     

Perturbation theory and nonperturbative effects: A happy marriage ?

Perturbation expansions in renormalized quantum field theories are reformulated in a way that permits a straightforward handling of situations when in the conventional approach, i.e. in fixed renormalization scheme, these expansions are factorially divergent and even of asymptotically constant sign. The result takes the form of convergent (under certain circumstances) expansions in a set of functionsZ _k(a,) of the couplant and the free parameter which specifies the procedure involved. The value of is shown to be correlated to the basic properties of nonperturbative effects as embodied in power corrections. Close connection of this procedure to Borel summation technique is demonstrated and its relation to conventional perturbation theory in fixed renormalization schemes elucidated.