Oxidation of MBE-Grown ZnTe and ZnTe/Zn Nanowires and Their Structural Properties

Results of comparative structural characterization of bare and Zn-covered ZnTe nanowires (NWs) before and after thermal oxidation at 300 °C are presented. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, high-resolution transmission electron microscopy, and Raman scattering not only unambiguously confirm the conversion of the outer layer of the NWs into ZnO, but also demonstrate the influence of the oxidation process on the structure of the inner part of the NWs. Our study shows that the morphology of the resulting ZnO can be improved by the deposition of thin Zn shells on the bare ZnTe NWs prior to the oxidation. The oxidation of bare ZnTe NWs results in the formation of separated ZnO nanocrystals which decorate crystalline Te cores of the NWs. In the case of Zn-covered NWs, uniform ZnO shells are formed, however they are of a fine-crystalline structure or partially amorphous. Our study provides an important insight into the details of the oxidation processes of ZnTe nanostructures, which could be of importance for the preparation and performance of ZnTe based nano-devices operating under normal atmospheric conditions and at elevated temperatures.     

A Scalable Route to Highly Functionalized Multi‐Walled Carbon Nanotubes on a Large Scale

A scalable and solvent‐free chemical process to obtain highly functionalized and dispersible multi‐walled carbon nanotubes is reported. Highly functionalized multi‐walled carbon nanotubes have been prepared using in situ generated aryl diazonium salts in the presence of ammonium persulfate and 2,2′‐azoisobutyronitrile by solvent‐free techniques. In the Raman spectra of the resulting materials, characteristic peaks, the D‐ and G‐bands, are shifted by about 10 cm^?1 to lower frequencies. At the same time, the relative intensity ratios between the D‐ and G‐bands increase in comparison to that in the spectrum of the purified product. Fourier‐transform infrared spectroscopy reveals the presence of the functional groups on the surface. Transmission electron microscopy images directly confirm the significant build‐up of sidewall organic moieties on the treated materials. The weight loss of various functional moieties determined by thermogravimetry–differential scanning calorimetry analysis is about 18–33%. The dispersibility of the functionalized materials in solvents, such as chloroform, tetrahydrofuran, and water, is obviously improved.

     

Pharmacological Characterization and Raman Spectroscopy Evaluation of Oral and Maxillofacial Surgery-Related Carnoy´S Solution Modified by Different Viscosity Agents

Background: There are several lesions of odontogenic and non-odontogenic origin in the oral cavity, such as odontogenic keratocyst, as well as many treatment options for such lesions. In order to reduce recurrence due to conservative treatments and less aesthetic and functional impairment of the patient (radical therapies), Carnoy’s solution has been used as an adjuvant to surgery, showing satisfactory results. Its application is not standardized, presenting risks to adjacent tissues. Thus, we characterized the Carnoy’s solution with different viscosity agents to enhance its applicability. Material and Methods: All solutions prepared (Carnoy with and without chloroform) were added with viscosity agent: ethyl cellulose, propylene glycol, and glycerol totaling eight solutions. The pharmacological characterization of the solutions was performed by determining the mass density and relative density (using a clean and dry pycnometer), pH (using pH meter), and concentration of Fe3+ (using ultraviolet/visible spectroscopy). The analyses of the inorganic components were determined by Raman micro spectrometry. Data were analyzed with statistical program BIOESTAT 5.3. Results: Solutions with ethyl cellulose were discarded due to precipitate formation and suspension of the viscosity agent. In the other solutions, viscosity increase (propylene glycol solutions) and acidic pH were observed mainly in the glycerol group. The ferric chloride characterized as a hemostatic agent had its concentration increased with the use of thickening agents, theoretically favoring its action. Conclusion: The similarity of the propylene glycol and glycerol molecules justifies the Raman spectra of these substances to be similar and the difficulty in obtaining a “fingerprint”.     

纳米雄黄酸水飞品X射线衍射及拉曼光谱分析

目的:分析纳米雄黄酸水飞品(Realgar nanoparticles processed,NRPP)X射线衍射(XRD)图谱和拉曼光谱的图谱特征,并比较雄黄炮制前后晶形结构的异同。方法:采用X射线衍射法和拉曼光谱法对6批雄黄生品,6批雄黄水飞品,6批纳米雄黄酸水飞品进行测定,确定各样品的物相组成及晶形结构成键情况。结果:XRD分析表明雄黄生品和雄黄水飞品均为β-As_4S_4,纳米雄黄酸水飞品中NRPP1,NRPP5及NRPP6批次为β-As_4S_4,NRPP2,NRPP3及NRPP4批次为β-As_4S_4和α-As S的混合体。拉曼光谱分析表明雄黄生品、雄黄水飞品和纳米雄黄酸水飞品均在360~362,342~344,185~187,164~166 cm~(-1)等波数位置出现了特征性较强的拉曼振动峰。结论:X射线衍射技术与拉曼光谱法相结合,能较好地反映出纳米雄黄酸水飞品的特征吸收峰,可用于纳米雄黄酸水飞品的鉴定与分析。雄黄经常规的水飞法炮制未造成晶型结构的变化,而经纳米化并酸水飞后晶形结构则发生改变。     

Raman spectroscopic evidence for nuclear disulfide in isolated lenses of hyperbaric oxygen-treated guinea pigs

Our laboratory treats guinea pigs with hyperbaric oxygen (HBO) as a model for investigating the formation of nuclear cataract. Previous analyses of lens supernatants using this model have shown an increase in disulfide (-SS-) and loss of sulfhydryl (-SH) in the lens nucleus of O(2)-treated animals. In this paper, we have used the non-invasive technique of Raman spectroscopy to confirm these findings in intact, freshly-excised lenses. Guinea pigs were treated 3 times per week with HBO for a total of 50 (4 months of treatment) or 85 (7 months of treatment) times to induce an increased level of lens nuclear light scattering. Intact lenses were analyzed by Raman spectroscopy using a 514.5 nm laser and collecting the scattered light in a 90 degrees geometry. The laser beam was focused either in the lens nucleus or equatorial cortex. Changes in the levels of -SS- (503 cm(-1)) and -SH (2577 cm(-1)) vibrations were measured. Raman spectra were analyzed by fitting Lorentzian profiles to the observed data in the -SS- and -SH regions. -SS- levels in the O(2)-treated nucleus were found to have increased by a factor of 2.1 (p=0.0001) and 2.5 (p=0.001) after 50 and 85 HBO treatments, respectively, compared to age-matched controls. Based on previous biochemical analyses, the -SS- increase was due mainly to the formation of protein disulfide (PSSP) with contribution also from protein/thiol mixed disulfides, but not from oxidized glutathione. -SH levels in the O(2)-treated nucleus decreased by 13% (p=0.007) and 35% (p=0.001) after 50 and 85 HBO treatments, respectively, compared to age-matched controls. No significant increase in -SS- or loss of -SH was observed in the lens cortex of the O(2)-treated guinea pigs. The Raman spectroscopy results rule out the possibility that artifactual production of -SS- and loss of -SH occurred during homogenization of lenses in previous studies. The data provide additional evidence to support a link between O(2), disulfide-crosslinking of lens crystallins in the nucleus, and nuclear cataract.     

Raman spectroscopy of parathyroid tissue pathology

Primary hyperparathyroidism (HPT) in 80% of patients is due to a solitary parathyroid adenoma, while in 20% multigland pathology exists, usually hyperplasia [Scott-Coombes, Surgery, 21(12):309–312, 2003]. Despite recent advances in minimally invasive parathyroidectomy, better preoperative localisation techniques and intraoperative parathyroid hormone (PTH) monitoring, a 4% failure rate [Grant CS, Thompson G, Farley D, Arch Surg, 140:47–479, 2005] persists making accurate differentiation between adenomas and hyperplasia of prime importance. We investigated the ability of Raman spectroscopy to accurately differentiate between parathyroid adenomas and hyperplasia. Raman spectra were measured at defined points on the parathyroid tissue sections using a bench-top microscopy system. Multivariate analysis of the spectra was carried out to construct a diagnostic algorithm correlating spectral results with the histopathological diagnosis. A total of 698 spectra were analysed. Principal-component (PCA)-fed linear discriminant analysis (LDA) used to construct a diagnostic algorithm. Detection sensitivity for parathyroid adenomas was 95% and hyperplasia was 93%. These preliminary results indicate that Raman spectroscopy is potentially an excellent tool to differentiate between parathyroid adenomas and hyperplasia.     

Identification of chemical compositions of skin calcified deposit by vibrational microspectroscopies

Calcinosis cutis is characterized by the deposition of calcium salts in the subcutaneous tissues. Both Fourier transform infrared (FTIR) and Raman microspectroscopic analysis have been applied to easily get the chemical compositions of the skin calcified deposit (SCD), which was surgically excised from a female patient. This SCD was cut into two parts for histopathological (H&E stain) examination and vibrational microspectroscopic study. The result indicates that the whole SCD in the skin lesion was found to be a well-developed, mature and hard mass. Several FTIR absorption bands at 873, 961 and 1,031 cm⁻¹ [the stretching modes of carbonate and phosphate of hydroxyapatite (HA)], 1,547 and 1,658 cm⁻¹ (the amide I and II bands of collagen) were detected in the IR spectrum of SCD. The Raman spectral bands at 1,665 and 1,450 cm⁻¹ (collagen); 1,519 and 1,156 cm⁻¹ (β-carotene); and 1,072 and 958 cm⁻¹ (HA) were also obtained. To our knowledge, this is the first report using FTIR and Raman microspectroscopies to quickly identify and quantify three predominant components, collagen, β-carotene and type B carbonated HA, in the SCD of a patient.     

Raman spectroscopy for optical diagnosis in the larynx: preliminary findings

BACKGROUND AND OBJECTIVES: Raman spectroscopy (RS) provides information about molecular structure and is a potential tool for non-invasive tissue diagnosis. To determine if Raman spectra could be obtained rapidly from laryngeal tissue in vitro, and compare Raman spectra from normal, benign, and cancerous laryngeal tissue. STUDY DESIGN/MATERIALS AND METHODS: Forty-seven laryngeal specimens were studied using RS with signal acquisition times (SAT) between 1 and 30 second(s). Multivariate analysis was used to determine the diagnostic ability of RS compared to standard histology (n = 18, 13, and 16 respectively for normal tissue, carcinoma, and squamous papilloma). RESULTS: Good quality spectra were obtained with 5-second SAT. Spectral peak analysis showed prediction sensitivities of 89%, 69%, and 88%, and specificities of 86%, 94%, and 94% for normal tissue, carcinoma, and papilloma. CONCLUSIONS: In the larynx, spectral differences appear to exist between normal tissue, carcinoma, and papilloma. The ability to obtain spectra rapidly supports potential for future in vivo studies.     

Autofluorescence and Raman microspectroscopy of tissue sections of oral lesions

Autofluorescence spectroscopy and Raman spectroscopy have been suggested for lesion diagnostics. We investigate the information contained in autofluorescence and Raman spectra recorded from oral tissue slices of various lesion types. Thirty-seven human oral mucosa lesions were biopsied and freeze-dried. Complete autofluorescence images and spectra were recorded from 20 m sections. Raman spectra were acquired from the same positions for 12 of the sections. Cluster analysis was applied to find any relationship between spectral shape and lesion type or cell layer. Autofluorescence images showed high intensities for keratin layers and connective tissue, but hardly any for the epithelium. Autofluorescence spectra were centered around 520 nm and did not show specific spectral features. No clustering with regard to lesion type or cell layer was observed. Raman spectra allowed for reliable classification into cell layers, but differences between lesion types were not significant in this study. Autofluorescence spectra of freeze-dried oral mucosa sections did not contain useful information. A more comprehensive study is required for Raman spectra.