Synchrotron-based X-ray absorption spectroscopy of Pd nanoparticles decorated on multi-walled carbon nanotubes during successive cycles of He/H2 exposure.

The MWCNTs are decorated by Pd nanoparticles via various techniques including laser ablation in liquid, chemical reduction, and simultaneously both of them. To study the hydrogen adsorption mechanism, Pd K-edge X-ray absorption spectroscopy (XAS) is carried out via heating/cooling processes under He/H2 exposure. The Fourier transform X-ray absorption fine structure (FT-EXAFS) simulation indicates the presence of the Pd-Pd and Pd-C(O) bonds. Furthermore, during the successive cycles of He/H2 exposure, bond restructuring takes place. Moreover, the heating process under He/H2 exposure induces a destructive effect on the Pd-C(O) links. Furthermore, the Pd-Pd bond distance enlarges due to the hydrogen adsorption for all samples, however, in the case of PLAL, the change in the bond distances becomes dominant. XRD and XPS are applied to support the findings.

Single-frequency gain-switched ytterbium-doped fiber laser at 1017 nm based on dynamic self-induced grating in a saturable absorber.

We report on a stable single-frequency gain-switched ytterbium-doped fiber (YDF) laser at 1017 nm based on saturable absorber (SA) properties. The laser is realized by utilizing a short-length, high-concentration phosphosilicate YDF that simultaneously acts as an SA and a gain medium in a linear cavity. Despite the fact that gain switching is achieved by modulating the pump laser, single-frequency operation is sustained due to dynamic self-induced grating. By making use of high-concentration phosphosilicate YDF and selecting a suitable spectral region, grating is strongly induced along the cavity to stabilize single-mode operation. Additionally, the residual grating property in SA assures single-mode gain-switched performance at high repetition rates. Here, the laser generates pulses with 427 ns duration at 100 kHz, yielding the mean power of 12 mW with linewidth of less than 7.5 MHz.

Effect of colliding partners on the performance of SF6 and SO2 trace measurements in photoacoustic spectroscopy.

A photoacoustic (PA) cell was designed based on the numerical simulation and then was fabricated in order to investigate the effect of various buffer gases on the acoustic signals and the resonant frequencies. The sizes of resonator and buffer chambers were suitably selected to improve signal-to-noise ratio. Atmospheric SF6 impact is high due to its significant green house effect. A series of experiments were performed to detect SF6 trace in the air and various types of rare gases. Similar experiments were carried out for the urban and industrial pollutant SO2 in the same environments. The resonant frequencies were measured at various pressures for several rare gases, namely He, Ne, Ar, Kr, and Xe. The PA spectroscopy of molecular traces in various gases gives rise to sensible spectral shift. It was shown that the use of heavier buffer gases at atmospheric pressure lead to detection of the lower concentrations. In general, the relatively intense acoustic signal is recorded for the heaviest species Xe due to its large vibrational-transitional excitation cross section. Conversely, the light elements dissipate laser energy much larger than the heavy species during the successive collisional excitations. Therefore the trace molecules in helium exhibit a notable rise in the resonant frequency accompanying a small PA signal.

Red/blue spectral shifts of laser-induced fluorescence emission due to different nanoparticle suspensions in various dye solutions.

Red/blue shifts of laser-induced fluorescence (LIF) are investigated using several guest dielectric nanoscatterers, such as TiO2, ZnO, Al2O3, and SiO2, in the host Rd6G, RdB, Coumarin 4, and Coumarin 7 ethanolic solutions. A couple of inflection points are identified varying nanoparticle (NP) density into dye solutions based on LIF spectroscopy. The inflection of the spectral shift exhibits that the suspension of NPs in dye solutions significantly involves a couple of competitive chemical and optical mechanisms during photon traveling in scattering media regarding ballistic and diffusive transport. It is shown that the low, medium, and high NP additives in fluorescent suspension induce blue, red, and blue spectral shifts, respectively.

Comparative Study between Paracervical Block and Non-Steroidal Anti Inflammatory Drug for Relief of Pain during Manual Vacuum Aspiration Procedure.

The incidence of first trimester pregnancy loss is around 10.0-20.0% of registered pregnancies. Manual vacuum aspiration is a safe, effective and acceptable option of treatment for patients diagnosed with first trimester pregnancy loss. Main disadvantage of MVA is the pain caused by manipulation of the cervix, the uterine suction and the cervical dilatation. This study showed the way how the pain and discomfort might be reduced. This was a cross-sectional comparative study was conducted at the obstetrics and Gynecological Department of Sadar hospital, Manikganj, Bangladesh from January 2017 to December 2017. All the consecutive women admitted and diagnosed as incomplete abortion, missed abortion and anembryonic pregnancy (blighted ovum) were included in this study. Sampling technique was purposive sampling. The objective of this study was to compare the effectiveness of paracervical block anesthesia with non-steroidal anti inflammatory drug (NSAID) for relief of pain during the manual vacuum aspiration procedure for the treatment of first trimester pregnancy loss. Total 120 cases were included in this study. Assigned study population were divided into two groups like Group A and Group B. 60 of the study population were included in Group A who were given paracervical block anesthesia 3 minutes before the procedure. Another 60 study population was included in Group B who was given diclofenac 75mg intramuscular injection, 30 minutes before the procedure. Both intraoperative and postoperative pain level was evaluated by using visual analog scale ranged from (0-10 points) 30 minutes after the procedure. At the same time the satisfaction level of the study population were measured by 5 points lickert scale. Regarding clinical profile of the study population it showed no significant difference in case of mean age, mean gestational age and mean duration of the procedure between two groups. The mean intraoperative pain score in Group A was 4.0±1.3, in Group B it was 5.4±1.5 (p=0.001) which was significant. So it showed that paracervical block anesthesia significantly reduced the pain in relation to diclofenac 75mg intramuscular injection. Mean postoperative pain level 30 minutes after procedure in Group A was 2.2±0.4 and in Group B was 2.4±0.4 (p=0.343), where post-operative pain is lower in Group A than Group B. Though this difference is not statistically significant (p=0.343). In Group A 73.0% (n=44) and in Group B 43.0% (n=26) study population were agreed that the procedure was easy. Most common adverse effect was epigastric pain which was 1.7% (n=1) in Group A and 10.0% (n=7) in Group B. Paracervical block significantly reduces intraoperative pain during Manual Vacuum Aspiration (MVA) procedure in the treatment of first trimester pregnancy loss in comparison to intramuscular injection of diclofenac. In conclusion it might be mentioned that regarding paracervical block anesthesia, efficacy is higher and side effects are less. Moreover paracervical block anesthesia is cost effective.

Discrimination of normal and cancerous human skin tissues based on laser-induced spectral shift fluorescence microscopy.

A homemade spectral shift fluorescence microscope (SSFM) is coupled with a spectrometer to record the spectral images of specimens based on the emission wavelength. Here a reliable diagnosis of neoplasia is achieved according to the spectral fluorescence properties of ex-vivo skin tissues after rhodamine6G (Rd6G) staining. It is shown that certain spectral shifts occur for nonmelanoma/melanoma lesions against normal/benign nevus, leading to spectral micrographs. In fact, there is a strong correlation between the emission wavelength and the sort of skin lesions, mainly due to the Rd6G interaction with the mitochondria of cancerous cells. The normal tissues generally enjoy a significant red shift regarding the laser line (37 nm). Conversely, plenty of fluorophores are conjugated to unhealthy cells giving rise to a relative blue shift i.e., typically SCC (6 nm), BCC (14 nm), and melanoma (19 nm) against healthy tissues. In other words, the redshift takes place with respect to the excitation wavelength i.e., melanoma (18 nm), BCC (23 nm), and SCC (31 nm) with respect to the laser line. Consequently, three data sets are available in the form of micrographs, addressing pixel-by-pixel signal intensity, emission wavelength, and fluorophore concentration of specimens for prompt diagnosis.

Fluorescence emission quenching of RdB fluorophores in attendance of various blood type RBCs based on Stern-Volmer formalism.

In this work, the optical properties of Rhodamine B (RdB) are investigated in the attendance of various red blood cells (RBCs). RdB fluorophores, as biological markers, is excited using SHG-CW Nd:YAG laser at 532 nm. In fact, the addition of biomolecules of interest to the reference fluorophore notably changes the fluorescence properties of the suspension. Here, laser induced fluorescence (LIF) spectrophotometry based on Stern-Volmer quenching formalism and field emission scanning electron microscope (FESEM) are employed here. According to the given fluorescence spectra, the spectral shift of emissions as well as quenching coefficients are assessed subsequently. The Stern-Volmer formalism is used to determine the quenching coefficients. In fact, RdB + RBCs suspensions contain a plenty of bioconjugates leading to the signal reduction and notable red shift in RdB fluorescence emissions. Furthermore, it is demonstrated that the positive blood type RBCs exhibit the higher quenching coefficients and the larger red shifts against those of negative blood types. This mainly arises from the nature of specific sugar antigens available on the RBC membranes as to N-acetylgalactosamine and galactose attached to the O-antigen terminal would enhance further quenching of the species. Moreover, a significant correlation appears between Stern-Volmer coefficients and the corresponding RBCs. In fact, distinct discrepancy takes place in quenching coefficients in terms various positive/negative blood types to envisage a facile method of blood typing.

Fluorescence quenching effects of carbon nano-structures (Graphene Oxide and Nano Diamond) coupled with Methylene Blue.

Here, the effect of Graphene Oxide (GO) and Nano Diamond (ND) carriers on the spectral properties of the fluorescence emissions of MB suspensions in the form of (MB + GO) and (MB + ND) biomaterials are investigated. The strong affinity of MB fluorophores with GO/ND nanostructures lead to the chemical bonding formation that affects the quenching coefficient and spectral shift. According to Stern-Volmer linearity despite, the excited (MB + GO) is strongly quenched due to its privileged bonding affinity, however the (MB + ND) does not. Furthermore, the corresponding quenching coefficients are measured. In fact, GO additives in the MB suspension gives rise to a sensible blue shift due to its surface functionality while no spectral shift takes place in the case of (MB + ND). We have shown that the complex formation such as (MB + GO) is strongly correlated to the GO quenching coefficient due to the hydrogen bonding and π - π staking, whereas there is a loose dependence with the blue shift phenomena. Furthermore, we have compared the quenching coefficients of Rd6G and DOX with MB fluorophore to attest the quenching coefficient is strongly correlated to the molecular structure and its active sites. The findings could be helpful in the course of simultaneous PDT and fluorescence imaging.

Synergistic performance of triggered drug release and photothermal therapy of MCF7 cells based on laser activated PEGylated GO + DOX.

Graphene oxide is used as a singular 2D nano-carrier in cancer therapy. Here, graphene oxide is used as a hybrid chemo-drug graphene oxide (GO) + doxorubicin (DOX), mainly due to its unique chemical and optical properties. The laser triggers GO + DOX for selective drug delivery to optimize the drug release. The characterization of GO is investigated in terms of laser properties at 808 nm. Furthermore, the laser activates GO + DOX compounds to treat MCF7 cancerous cells. The drug release strongly depends on the temperature rise that mainly effects on the viability of the cancerous cells of interest. DOX simultaneously acts as a chemo-drug and as an optical fluorescent agent, whereas GO performs as an efficient photothermal nano-carrier. In fact, the GO-DOX hybrid drug demonstrates multifunctional during malignant cell treatment. We have shown that the laser heating of GO enhances the release percentage up to a treatment yield of 90%. This arises from the synergistic nature of DOX and GO compounds in simultaneous chemo/photo thermal therapy. Furthermore, the fluorescence property of DOX is used to assess the GO uptake using confocal microscope imaging.

Fluorescence properties of Phycocyanin and Phycocyanin-human serum albumin complex.

In this work, the fluorescence properties of Phycocyanin (PC) and the corresponding quenching effects are investigated in attendance of human serum albumin (HSA). At first, PC is excited at 532 nm using CW SHG Nd:YAG laser, then the emission wavelength, Stokes shift, quantum yield, extinction constant and self-quenching coefficient are obtained based on the modified Beer-Lambert equation. It is shown that a notable red shift appears in terms of PC concentration. According to the fluorescence spectra, the addition of HSA in PC solution leads to a significant reduction in the fluorescence signal via quenching events, however a lucid blue shift takes place in the same time. Stern-Volmer formalism is used to determine the quenching constant (KS), the number of binding sites (n) between PC and HSA as well as the association constant Ka for the purpose of facile transportation to the target in the context of drug delivery. Eventually, temperature dependent coefficients and corresponding spectral shifts are investigated over a wide range of temperatures at a couple of distinct PC concentrations to attest the dominant static quenching takes place. The rate of conjugate formations elevates at low temperatures leading to a certain blue shift. Furthermore, large KS is measured in the course of signal reduction, particularly at low PC populations. In fact, PC conjugation to HSA is essential interaction to enhance chemo drug transportation. Here, at the body temperature, the quenching coefficient decreases to facilitate the drug release. Moreover, the spectral shift of fluorescence emission can be useful for simultaneous monitoring and drug delivery treatment.

Dual-laser-beam-induced breakdown spectroscopy of copper using simultaneous continuous wave CO(2) and Q-switched Nd:YAG lasers.

In this work, we investigate the enhancement of Cu emission lines of a micro-plasma induced by a Nd:YAG laser due to the thermal effect of simultaneous irradiation by a continuous wave (CW) CO(2) laser. The enhancement of the emission lines was achieved at a higher temperature with minimal distortion of the target when the focal point of the Nd:YAG laser was located approximately 1 mm away from the sample surface.

Laser induced fluorescence spectroscopy of various carbon nanostructures (GO, G and nanodiamond) in Rd6G solution.

The effect of carbon nanostructures such as graphene (G), graphene oxide (GO) and nanodiamond (ND) on the spectral properties of Rhodamine 6G (Rd6G) emission due to the laser induced fluorescence (LIF) was investigated. It is shown that the addition of carbon nano- structures lead to sensible Red/Blue shifts which depend on the optical properties and surface functionality of nanoparticles. The current theories such as resonance energy transfer (RET), fluorescence quenching and photon propagation in scattering media support the experimental findings. Stern-Volmer curves for dynamic and static quenching of Rd6G molecules embedded with G, GO and nanodiamond are correlated with spectral shifts. Furthermore, time evolution of the spectral shift contributes to determine loading/release rates of fluorescent species with large S-parameter on the given nano-carriers.

Spectral Lines of the Atomic-Fluorine Laser from 2 psi (absolute) to 5.5 atm.

Various lines of atomic fluorine laser have been studied over a wide pressure range for determination of the relative intensity of each pressure-dependent line. In this investigation, the most probable laser pumping mechanisms have been verified.

Measurement of the small-signal gain and saturation intensity of a XeF discharge laser.

An optical oscillator-amplifier series driven by a Blumlein discharge has been fabricated and optimized for measuring the small-signal gain and saturation intensity of a XeF (B ? X) laser at 352 nm. Pressure dependence of the gain and the saturation property of the laser have been investigated.

The effects of errors in lipid measurement and assessment.

Accurate cholesterol and lipoprotein measurements have provided dependable and powerful basic risk factors for cardiovascular disease. A battery of total cholesterol (TC), high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol, and triglycerides (TG) is recommended in the initial evaluation for classification of patients (based on lipids) into highly desirable, desirable, borderline, high, and very high lipid risk factor for cardiovascular disease. Treatment is based largely on the LDL cholesterol measurement result of the patient. The risk factor score of a patient greatly increases when other risk factors for cardiovascular disease exist, along with increased lipid risk factors. Attainment of the needed acceptable accurate lipid and lipoprotein measurements depends upon prevention or control of multiple sources of errors or variation that can exist in preanalytic, analytic, and postanalytic stages of determination of the reported result. Highly important is to control nonfasting, posture, diet, and alcohol intake in the preanalytic part, elimination of matrix effects and use of accurate calibrators in the analytic part, and check for transcription errors in preparation of reports in the postanalytic part of the measurement of lipids.

Performance of four homogeneous direct methods for LDL-cholesterol.

BACKGROUND: Homogeneous LDL-cholesterol methods from Genzyme, Reference Diagnostics, Roche, and Sigma were evaluated for precision, accuracy, and specificity for LDL in the presence of abnormal lipoproteins. METHODS: Each homogeneous method was performed by a Roche/Hitachi 911 according to the vendors' instructions, and the results were compared with the beta-quantification reference method. We measured precision over 20 days using quality-control and frozen serum specimens. Sera from 100 study participants, including 60 with hyperlipidemias, were assayed by each method. Accuracy was evaluated from regression and total error analysis. Specificity was evaluated from the bias (as a percentage) vs concentration of triglycerides. RESULTS: The total CV was <2% for all methods. Regression slope and intercept (with 95% confidence intervals) were as follows: Genzyme, 0.955 (0.92 to 0.99) and 30.3 (-12 to 73) mg/L; Reference Diagnostics, 0.975 (0.93 to 1.02) and -8 (-63 to 47) mg/L; Roche, 1.067 (1.02 to 1.11) and -101 (-161 to -42) mg/L; and Sigma, 0.964 (0.91 to 1.02) and 164 (89 to 239) mg/L. The percentages of individual results with >12% bias were as follows: Genzyme, 8.0%; Reference Diagnostics, 11.0%; Roche, 10.0%; and Sigma, 30.0%. Total error calculated from mean systematic bias and all-sources random bias was as follows: Genzyme, 12.6%; Reference Diagnostics, 16.5%; Roche, 41.6%; and Sigma, 38.3%. Slopes of bias (as a percentage) vs triglycerides were P <0.001 for all methods except the Roche method, which was P = 0.094. CONCLUSIONS: The evaluated methods show nonspecificity toward abnormal lipoproteins, thus compromising their ability to satisfy the National Cholesterol Education Program goal for a total error of <12%. These homogeneous LDL-cholesterol results do not improve on the performance of LDL-cholesterol calculated by the Friedewald equation at triglyceride concentrations <4000 mg/L.