Short-term comparison of the 660 and 830 nm laser in the treatment of temporomandibular dysfunction – a randomized clinical trial

Introduction. The objective of this study was to compare the effects of low-level laser therapy (LLLT), 660nm laser with 830nm, in temporomandibular dysfunction (TMD). Aim. To compare the effect of LLLT 660 nm and 830 nm in treatment of TMD. Material and methods. This is a randomized clinical study, composed of 30 volunteers with TMDs selected and divided into three groups: LLLT 660nm, LLLT 830nm and Sham. After the intervention, the results were reevaluated with the Fonseca anamnestic questionnaire (FAQ), American Academy of Orofacial Pain Questionnaire (AAOPQ), McGill Pain Questionnaire and Visual Analog Scale. Results. Analysis of the results showed that, although all groups had reduced values in the FAQ, only the laser groups presented alterations in the level of classification; for AAOPQ, only the treatment groups had a reduction in the positive responses, variables, the reduction was similar for all groups. Conclusion. LLLT produced a reduction in severity of symptoms but was like the sham for pain.

Pressure-Induced Dimerization of C60 at Room Temperature as Revealed by an In Situ Spectroscopy Study Using an Infrared Laser

Using in situ high-pressure Raman spectroscopy and X-ray diffraction, the polymerization and structure evaluation of C60 were studied up to 16 GPa at room temperature. The use of an 830 nm laser successfully eliminated the photo-polymerization of C60, which has interfered with the pressure effect in previous studies when a laser with a shorter wavelength was used as excitation. It was found that face-centered cubic (fcc) structured C60 transformed into simple cubic (sc) C60 due to the hint of free rotation for the C60 at 0.3 GPa. The pressure-induced dimerization of C60 was found to occur at about 3.2 GPa at room temperature. Our results suggest the benefit and importance of the choice of the infrared laser as the excitation laser.

Design Considerations for a Portable Raman Probe Spectrometer for Field Forensics

Raman spectroscopy has been shown to be a viable method for explosives detection. Currently most forensic Raman systems are either large, powerful instruments for laboratory experiments or handheld instruments for in situ point detection. We have chosen to examine the performance of certain benchtop Raman probe systems with the goal of developing an inexpensive, portable system that could be used to operate in a field forensics laboratory to examine explosives-related residues or samples. To this end, a rugged, low distortion line imaging dispersive Raman spectrograph was configured to work at 830 nm laser excitation and was used to determine whether the composition of thin films of plastic explosives or small (e.g., ≤10 μm) particles of RDX or other explosives or oxidizers can be detected, identified, and quantified in the field. With 300 mW excitation energy, concentrations of RDX and PETN can be detected and reconstructed in the case of thin Semtex smears, but further work is needed to push detection limits of areal dosages to the ~1 μg/cm2 level. We describe the performance of several probe/spectrograph combinations and show preliminary data for particle detection, calibration and detection linearity for mixed compounds, and so forth.

Resonance Raman Enhancement of the ν4 Band in Fe (TMPP)Cl at NIR Laser Excitation Attributed to Supramolecular Interaction

The strong enhancement when applying near-infrared excitation wavelengths, of totally symmetric modes of heme derivatives including β-hematin (malaria pigment), was hypothesized to be due to supramolecular interaction. Specifically, the intensity of the electron density or oxidation state marker band, ν4, is in part strongly affected by CH(((X hydrogen bonding interactions when X is an electron-donating entity. Chlorotetra (p-methoxyphenyl) porphyrinatoiron (III), Fe (TMPP)Cl, is a model compound that supports this hypothesis. The single crystal X-ray structure of Fe (TMPP)Cl, recrystallized by vapor diffusion of diethyl ether into dichloromethane solution, was determined. There are πpor···πpor interactions and numerous additional supramolecular interactions in the form of CH···Cl and CH···O, and CH···π hydrogen bond interactions. The corresponding resonance Raman intensity of Fe (TMPP)Cl exhibited great enhancement of the ν4 band when using 780 and 830 nm laser sources supporting the correlation of the strong CH(((X hydrogen bonding interaction and the strong resonance Raman enhancement of totally symmetric modes, especially ν4, observed in malaria pigment supramolecular arrays when applying near-infrared wavelengths.

Growth and High Pressure Investigation of (C60)n@SWNT

The (C60)n@SWNT (peapod) samples were prepared by vapor diffusion method. We performed the high pressure Raman measurements on the peapod samples by using a Mao-Bell type diamond anvil cell (DAC). In the In situ high pressure experiments, the peapod samples were exposed under UV laser line irradiation. The polymerization of C60 molecules in SWNT cave under both laser irradiation and pressure effects has been studied. The Raman spectra of the released samples from high pressure indicated that C60s form one-dimensional orthorhombic polymer. For the Raman measurements, two different excitation wavelengths were used, 325 nm laser and 830 nm laser.