Fluorescence enhancement of the aqueous solution of terephthalate ion after bi-frequency sonication

The fluorescence enhancement of the aqueous solution of terephthalate ion (TA) under orthogonal sonication of 28 kHz and 1.7 MHz ultrasonic wave has been studied. It has been found that the fluorescence intensity of TA solution after bi-frequency ultrasonic irradiation is obviously higher than the sum of those under two individual ultrasonic irradiations.     

Atomic and molecular fluorescence as a stratospheric species monitor

The results of an extensive evaluation are presented assessing the potential of atomic and molecular fluorescence as a stratospheric monitor of the concentrations of any one of eighteen minor species. These include Cl, Cl₂, ClO, ClO₂, CO, H₂, HCHO, HCl, HNO₂, HNO₃, H₂S, NH₃, NO, NO₂, N₂O, O, OH and SO₂. All spectral regions from the vacuum u.v. through to the i.r. have been included. Where appropriate, detection limits (signal/noise ratio of unity) are presented for each species under various sample pressure conditions and are based on practical systems that could be constructed using current technology.The most promising systems, with typical detection limits indicated either as parts per million, billion or trillion by volume, are for CO(5ppb), NO₂(<1ppb), OH(0.2ppt) and O(50–200ppt). The fluorescence sensitivities for Cl(0.5–1 ppt), H₂(0.2 ppm at 10 torr sample pressure) and SO₂(1–10 ppb) are marginally insufficient at present for such a stratospheric application. Likewise HCHO(10 ppb) and NO(100 ppb) fluorescence detection may be of interest in other applications where sensitivity demands are not as severe. There are no promising analytical possibilities using direct fluorescence techniques for Cl₂, ClO₂, HCl, HNO₂, HNO₃, H₂S, NH₃ or N₂O. ClO fluorescence has not yet been characterized.It has been noted, for various reasons, that i.r. fluorescence techniques in general cannot be exploited in the development of sensitive analyzers. However, by far the most surprising outcome of this study has been the recognition of the analytical potential of vacuum u.v. fluorescence. For some species, under certain conditions, extremely high sensitivities are possible even with samples in air at atmospheric pressure.     

我国的声化学应尽快大力开展实用化工作

声化学在实验室的研究在我国正在迅速发展。面对国内外大量的、已证实有效的声化学实例,让声化学尽早尽快在化学工业、绿色化学、制药工业、食品工业、纳米材料等新技术等等方面在我国实用起来,应该是不可多得的机遇。当前急务,一方面是大力进行深入的技术准备,让声化学能在多个环节从实验室高能效地走向社会;另一方面是,利用现有的技术,现在就慎重选择部分有条件实现的实验室成果,因陋就简地推广起来,工作中再逐步提高能效。     

A parametric review of sonochemistry: Control and augmentation of sonochemical activity in aqueous solutions

In this review the phenomenon of ultrasonic cavitation and associated sonochemistry is presented through system parameters. Primary parameters are defined and considered, namely; pressure amplitude, frequency and reactor design; including transducer type, signal type, vessel-transducer ratio, liquid flow, liquid height, liquid temperature and the presence of a reflective plate. Secondary parameters are similarly characterised and involve the use of gas and liquid additives to influence the chemical and physical environments. Each of the parameters are considered in terms of their effect on bubble characteristics and subsequent impact on sonochemical activity. Evidence suggests that via parametric variation, the reaction products and efficiency may be controlled. This is hypothesised to occur through manipulation of the structural stability of the bubble.     

CdTe quantum dots as fluorescence sensor for the determination of aminophylline in aqueous solution

A novel CdTe quantum dots (QDs) based technology platform was established in aqueous solution. It can perform accurate and simple determination of aminophylline concentration in pharmaceutical samples with satisfactory results. Under optimum conditions, the relative fluorescence intensity of CdTe quantum dots is linearly proportional aminophylline concentration from 2.00 to 80.0 μg mL^?1 with a correlation coefficient of 0.9979 for aminophylline determination and a detection limit of 0.531 μg mL^?1.     

One-step aqueous synthesis of CdS nanoparticles as a novel fluorescence probe for the ultrasensitive detection of DNA

One-step aqueous synthesis of CdS nanoparticles as a novel fluorescence probe for sensitive and selective determination of DNA with synchronous fluorescence spectrometric method has been developed. Different from the traditional organometallic route, in which toxic precursors or solvents might be used, the wet chemical approach demonstrated in this paper is superior in terms of simplicity, using of nontoxic materials, mild synthetic condition and good reproducibility. When Δλ=255 nm, maximum synchronous fluorescence is produced at 264 nm, the synchronous fluorescence intensity of the composite nanoparticles is significantly decreased in the presence of trace DNA at PH 0.91. Under optimal conditions, the linear ranges of the calibration curves are 0.08-30.0 μg mL⁻¹ for ctDNA and 0.05-35.0 μg mL⁻¹ for hsDNA, respectively. The detection limits are 1.5 ng mL⁻¹ for ctDNA and 2.2 ng mL⁻¹ for hsDNA, respectively. Furthermore, the method is successfully applied to the quantification of DNA in synthetic samples. The results show that this proposed method is stable, sensitive and practical for the determination of trace DNA.     

Single-bubble sonoluminescence of aqueous solutions of lanthanide chlorides and models of the sonochemistry of nonvolatile metal salts

The single-bubble sonoluminescence of d-f (Ce³⁺, Pr³⁺) and f-f (Tb³⁺) ions is detected in aqueous solutions of LnCl₃. It has been shown that the luminescence of these ions is sonophotoluminescence, i.e., the reemission of the absorbed short-wavelength part of the radiation spectrum of a blackbody, which appears in a bubble levitating in the field of a standing ultrasonic wave, in the bulk of the solution. In view of the revealed inefficiency of reemission in GdCl₃, the single-bubble sonoluminescence of Gd³⁺ has not been observed. The results indicate the low probability of the penetration of nonvolatile metal ions into the bubble in the hot shell model, which would be valid in single-bubble sonolysis and thereby confirm the validity of the injected droplet model, which explains the penetration to the bubble, electronic excitation, and luminescence of f-f ions Gd³⁺ and Tb³⁺ in multibubble sonolysis with an intensity much higher than the yield of their sonophotoluminescence.     

A study on effect of sonochemistry in a reverberation field

In this paper,an ultrasound with frequency of 815 kHz was used to re-search the sonochemical yield in a small-size reverberation field by the methodof fluorescent spectrum analysis.There are two characteristics on the effect ofsonochemistry in the reverberation field:First,the cavitation threshold wasabout 0.3W/cm~2(it was 0.7W/cm~2 in travelling field);Second,when thesound intensity was larger than the threshold,the sonochemical yield increasedas the intensity increased and increased rapidly after the intensity was at1.69-2.13W/cm~2,so that there was a upturned point in the curve of the result(which would tend to saturation in the travelling field).The theoretical analysisshows that the reason of the threshold decrease is that the sound energy densitybecomes high in the reverberation field,and the upturned point results from thedisturbance of the radiation pressure on the liquid surface.Therefore,by exper-iment and theory this paper shows that a reverberation field has to be built forthe higher sonoche     

Relevance of sonochemistry or ultrasound (US) as a proficient means for the synthesis of fused heterocycles

Medicinal chemistry has been benefited by combinatorial chemistry and high throughput parallel synthesis. The use of sonochemistry under controlled conditions has been proved beneficial for medicinal chemistry and drug discovery process since it dramatically reduces reaction times, from days or hours to minutes. In addition, sonochemistry synthesis provides higher yields, lower cost, easy workups and greater purity as compared to lower yields, tedious workups, longer reaction times, lesser purity and termination of many by-products in the conventional thermal methods.     

ESR Induced in CR-39 Plastic as a means of Gamma Ray Dosimetry

The gamma-induced ESR in CR-39 plastic has been studied and the possibility of using it as a gamma-ray dosimeter was investigated. The induced ESR was found to vary linearly with the dose up to 700 krad. The fading of the induced ESR signal at room temperature has been also investigated. The results suggest the possible use of CR-39 plastic for gamma dosimetry in the range 0 … 700 krad.

Es wurde die γ-induzierte ESR-Technik am CR-39 Plast untersucht und ihre Eignung als Gammastrahlen-Dosimeter geprüft. Die induzierte ESR variierte linear bis zu einer Dosis von 700 krad. Das Fading des induzierten ESR-Signals bei Zimmertemperatur wurde ebenfalls untersucht. Die Ergebnisse zeigten, daβ cine Verwendung des CR-39 Plast als Dosimeter für Gammastrahlen im Bereich von 0 … 700 krad möglich ist.     

Comments on the evolving field of sonochemistry by a cavitation physicist

Sonochemistry is an evolving field that has shown recent rapid growth and increasing interest. Although this field concentrates on chemistry and uses acoustics principally as a tool, the basic mechanism that gives rise to sonochemistry — acoustic cavitation — is often ignored or given little attention. This paper addresses some of the relevant aspects of cavitation and physical acoustics that apply to sonochemistry.     

Pyrolysed pitch-polysilane blends for use as anode materials in lithium ion batteries II: the effect of oxygen

As previously reported, blends of pitch and polysilanes, (Me₂Si)_x(PhMeSi)_y, with various pitch/polysilane ratios were pyrolysed at 1000 °C [W. Xing, A.M. Wilson, G. Zank, J.R. Dahn, Solid State Ionics 93 (1997) 239]. Some of the pyrolysed mixtures demonstrated large reversible capacities for lithium insertion (600 mA h g⁻¹), small irreversible capacities (150–200 mA h g⁻¹) and small hysteresis between charge and discharge cycles. Here, we investigate the role of the oxygen in these materials. The magnitude of the irreversible capacity and hysteresis are correlated to the oxygen content. This suggests that these materials are disordered carbons containing nanodispersed silicon oxycarbide clusters and not nanodispersed silicon, as was previously suggested. This does not change our opinion that pyrolysed pitch-polysilane blends are good alternatives to carbons for anode materials in lithium ion batteries.     

Investigating the possible use of a tetra (hydroxyphenyl) porphyrin as a fluorescence probe for the supramolecular detection of phospholipids

The present work explores the interest of using the 5,10,15,20-tetrakis(3-hydroxyphenyl)-21H,23H-porphine (m-THPP), a commercially available porphyrin, as a polarity probe for the detection of phospholipids. Feasibility of the process was first tested by direct fluorimetry and it was established that emission enhancement in the presence of lipids was maximum for a methanol content of 15% (v/v), a neutral pH (6-8) and a probe concentration of 2×10⁻⁷ M in the working solution. Detection with m-THPP in these conditions presents higher response factor but shorter linear range than diphenylhexatriene (DPH), the reference dye for the supramolecular detection of lipids. Insights on the mechanism of m-THPP-lipid association demonstrated that, at high lipid concentrations, porphyrin is associated to lipid assemblies in monomer form and located in the interior of bilayer; in low lipid content, porphyrin aggregates coexist with the monomer. Finally it was assessed that the method can be successfully coupled with micro-bore liquid chromatography.     

Thermoluminescence induced in Plastics above Room Temperature as a Means of Gamma Ray Dosimetry

The gamma-induced thermoluminescence (TL) in five types of plastics has been studied. The plastics used are Lexan, Makrofol, CA 80-15, LR 115 and CR-39. The result showed that the TL response for Makrofol and Lexan is linear in the range 5 …700 krad, 5 … 3000 krad, respectively. This suggests the possible use of these plastics for gamma dosimetry in the dose range 5 … 3000 krad.

Die gammastrahlen-induzierte Thermolumineszenz wurde an fünf Plastmaterialien untersucht, und zwar an Lexan, Makrofol, CA 80-15, LR 115 und CR-39. Die Ergebnisse zeigten, daβ die Thermolumineszenz-Reaktion für Makrofol und Lexan in Bereich 5 … 700 krad bzw. 5 … 3000 krad war. Das ermöglicht die Verwendung dieser Plastematerialien zur Gamma-Dosimetrie im Dosisbereich von 5 … 3000 krad.     

Industrial applications of sonochemistry in the syntheses of vitamin-building blocks

In this article, the application of ultrasound in syntheses of vitamins and fine chemicals is presented. Based on selected examples, the use of ultrasound in dehydration, isomerisation, and decarboxylation reactions is described.     

Influence of dissolved gases on sonochemistry and sonoluminescence in a flow reactor

In the present work, the influence of gas addition is investigated on both sonoluminescence (SL) and radical formation at 47 and 248 kHz. The frequencies chosen in this study generate two distinct bubble types, allowing to generalize the conclusions for other ultrasonic reactors. In this case, 47 kHz provides transient bubbles, while stable ones dominate at 248 kHz. For both bubble types, the hydroxyl radical and SL yield under gas addition followed the sequence: Ar > Air > N₂ >> CO₂. A comprehensive interpretation is given for these results, based on a combination of thermal gas properties, chemical reactions occurring within the cavitation bubble, and the amount of bubbles. Furthermore, in the cases where argon, air and nitrogen were bubbled, a reasonable correlation existed between the OH-radical yield and the SL signal, being most pronounced under stable cavitation at 248 kHz. Presuming that SL and OH originate from different bubble populations, the results indicate that both populations respond similarly to a change in acoustic power and dissolved gas. Consequently, in the presence of non-volatile pollutants that do not quench SL, sonoluminescence can be used as an online tool to qualitatively monitor radical formation.