Variation Of Signal Intensity Research Articles

Optimization of diffractive optical elements with millions of pixels using progressive error reduction algorithm (PERA)

Spatial light modulators (SLMs) comprising millions of micro-pixels have been applied for advanced applications requiring diffractive images of high quality (i.e., low root-mean-squared error, high signal-to-noise ratio, and low signal variation). Diffractive optical elements (DOEs) to be displayed in high-resolution SLMs are calculated using optimization algorithms to produce specific images. Current DOE optimization algorithms are incapable of providing high-quality images or else they consume too much time doing so. This paper presents two algorithms: the large error reduction algorithm (LERA) and the progressive error reduction algorithm (PERA). LERA selects image pixels (px) with the largest error for replacement with a target amplitude to improve image quality beyond what could be achieved using the iterative Fourier transform algorithm (IFTA). LERA tends to be time-consuming; however, it is able to reduce variations in signal intensity to 1.73e-8. PERA accelerates the optimization process by cascading an IFTA and several modified LERAs. Experiments were conducted on six DOEs of 1920×1080 px using a three-stage PERA equipped with three scaling factors.

A Portable Spark-Induced Breakdown Spectroscopic (SIBS) Instrument and its Analytical Performance.

A compact spark-induced plasma spectroscopic device was developed to detect elements used in a variety of applications. The system consists of a spark generator connected to tungsten electrodes, a custom-built delay generator, and two spectrometers that together cover the ultraviolet visible (UV-Vis) range (214-631 nm). The system was evaluated by qualitatively and quantitatively sampling copper standards. Prominent spectral peaks were identified using the NIST database for atomic emissions. The effectiveness of the proposed system was also tested with a lanthanide sample (gadolinium) and provided qualitative identification of the characteristic peaks. A semi-quantitative measurement for silicon and gold was performed using variable amounts of each particulate. Silica microbeads in solution were applied to paper wafers, while gold nanoparticles were sputter-coated onto silicon wafers. Results showed a positive correlation between the intensity of the signal and the concentration of each type of particulate. The variation of signal intensity was investigated to determine the repeatability, and the coefficient of variation was lowered from 60% to 25% after averaging measurements of multiple ablations per observation.

Magnetic resonance texture analysis utility in differentiating intraparenchymal neurosarcoidosis from primary central nervous system lymphoma: a preliminary analysis

Neurosarcoidosis and primary central nervous system lymphomas, although distinct disease entities, can both have overlapping neuroimaging findings. The purpose of our preliminary study was to assess if magnetic resonance texture analysis can differentiate parenchymal mass-like neurosarcoidosis granulomas from primary central nervous system lymphomas. A total of nine patients was evaluated, four with parenchymal neurosarcoidosis granulomas and five with primary central nervous system lymphomas. Magnetic resonance texture analysis was performed with commercial software using a filtration histogram technique. Texture features of different sizes and variations in signal intensity were extracted at six different spatial scale filters, followed by feature quantification using statistical and histogram parameters and 36 features were analysed for each sequence (T1-weighted, T2-weighted, fluid-attenuated inversion recovery, diffusion-weighted, apparent diffusion coefficient, T1-post contrast). The non-parametric Mann-Whitney test was used to evaluate the differences between different texture parameters. The differences in distribution of entropy on T2-weighted imaging, apparent diffusion coefficient and T1-weighted post-contrast images were statistically significant on all spatial scale filters. Magnetic resonance texture analysis using medium and coarse spatial scale filters was especially useful in discriminating neurosarcoidosis from primary central nervous system lymphomas for mean, mean positive pixels, kurtosis, and skewness on diffusion-weighted imaging ( P < 0.004-0.030). At spatial scale filter 5, entropy on T2-weighted imaging ( P = 0.001) was the most useful discriminator with a cut-off value of 6.12 ( P = 0.001, area under the curve (AUC)-1, sensitivity (Sn)-100%, specificity (Sp)-100%), followed by kurtosis and skewness on diffusion-weighted imaging with a cut-off value of -0.565 ( P = 0.011, AUC-0.97, Sn-100%, Sp-83%) and-0.365 ( P = 0.008, AUC-0.98, Sn-100%, Sp-100%) respectively. Filtration histogram-based magnetic resonance texture analysis appears to be a promising modality to distinguish parenchymal neurosarcoidosis granulomas from primary central nervous system lymphomas.

Autofluorescence in Parathyroidectomy: Signal Intensity Correlates with Serum Calcium and Parathyroid Hormone but Routine Clinical Use is Not Justified

BackgroundThe inability to identify the pathological gland at surgery results in failure to cure hyperparathyroidism in 2–5%. The poorly understood characteristic of parathyroid tissue to manifest autofluorescence (AF) under near-infrared (NIR) light has been promoted as an intraoperative adjunct in parathyroid surgery. This study sought to explore potential clinical correlates for AF and assess the clinical utility of AF in parathyroid surgery.MethodsConsecutive patients undergoing parathyroid surgery for primary and renal disease were included. NIR imaging was used intraoperatively and the degree of AF of parathyroid glands graded by the operating surgeon. Variables assessed for correlation with AF were: pre-operative serum calcium and PTH, SestaMIBI positivity, gland weight and histological composition.ResultsNinety-six patients underwent parathyroidectomy over an 8-month period: 49 bilateral explorations, 41 unilateral and 6 focussed lateral approaches: 284 potentially ‘visualisable’ glands in total. Two hundred and fifty-seven glands (90.5%) were visualised with NIR. Correlation was found between the degree of fluorescence and pre-operative serum calcium and PTH, but not between gland weight and SestaMIBI positivity. In those with renal hyperparathyroidism, a predominance of oxyphil cells correlated with increased AF.ConclusionAutofluorescence intensity correlates with serum calcium, PTH and gland composition. Further refinements would be required for this information to be of value in a clinical setting. Improvements allowing NIR to visualise the additional 9.5% of parathyroids and overcome the variation in signal intensity due to depth of access are required for the routine adoption of this technology. At present, its routine use in a clinical setting cannot be justified.

A Platform for Investigating Nuclear Organization and its Changes During Human iPSC Differentiation

The Allen Institute for Cell Science is developing a state space of stem cell structural signatures to understand the principles by which cells reorganize during the cell cycle and differentiation. We have developed a pipeline to generate high-replicate, dynamic image data on cell organization and activities using endogenous fluorescently tagged human induced pluripotent stem cells (hiPSCs) (the Allen Cell Collection at www.allencell.org). Each of the ∼25 lines express a monoallelic EGFP-tagged protein representing a cellular structure. For each structure, we take advantage of thousands of replicate high-resolution 3D images to develop quantitative image-based assays, segmentations, analyses, and computational models. We are initiating an analogous study of the nucleus, with a goal of creating a “state space of nuclear signatures.” We are endogenously tagging an initial set of eight key nuclear landmark proteins with EGFP and analyzing their sub-nuclear localization as the cells progress through the cell cycle and differentiate into cardiomyocytes. These landmarks include the nucleolus, nuclear lamina, nuclear pores, cohesin, CTCF, histones, and heterochromatin. We are also developing methods to quantify the change in localization patterns for these nuclear landmark proteins in the undifferentiated hiPSCs vs. cardiomyocytes derived from them. Preliminary image analyses, for example, reveal that H2B in cardiomyocytes displays less variation in both signal intensity and local spatial structure, generating a “smoother” protein distribution pattern within the nucleus and suggesting that our analysis approaches can detect changes in localization patterns of nuclear landmark proteins. We are also using single-cell RNAseq, FISH, and single-cell activity assays to conjoin gene expression with organization and phenotype. These cell lines and our analyses will further be integrated with genome-wide assays of chromatin architecture together with the 4D Nucleome Project and once fully characterized will be distributed publicly.

NMR as a new tool for cultural heritage application: The provenance of ancient white marbles

Identifying the origin of marble used in antiquity brings back to light details of the economic, social and political organization of classical societies, and characterizing in depth the chemistry of marble is key to discovering its provenance. Beyond X‐ray diffraction, which could reveal the presence of discriminant secondary crystalline phases and the quantification of accessory minerals combined with a multivariate analysis approach, solid‐state nuclear magnetic resonance (NMR) enables one to recognize the local structure arrangement of both crystalline and amorphous materials by looking at one or more selected atoms. In present paper targets the 13C nuclide, and thus the major component of marble, calcium carbonate. Whatever their geological origin, marbles 13C‐NMR spectra present only one resonance corresponding to the carboxyl function whose intensity and line width vary from one marble to another. If the variation of the NMR signal intensity observed is the result of great T1 variations (from 220 to 5300 s) and is linked to iron content, the line width reflects defects in the calcite crystal in which calcium has been replaced by another element such as magnesium, aluminium or strontium. The specific profile of the NMR signal has been used successfully to help determine the origin of some archaeological items.

Magnetic resonance imaging of the time course of hyperpolarized 129Xe gas exchange in the human lungs and heart

PurposeTo perform magnetic resonance imaging (MRI), human lung imaging, and quantification of the gas-transfer dynamics of hyperpolarized xenon-129 (HPX) from the alveoli into the blood plasma.Materials and methodsHPX MRI with iterative decomposition of water and fat with echo asymmetry and least-square estimation (IDEAL) approach were used with multi-interleaved spiral k-space sampling to obtain HPX gas and dissolved phase images. IDEAL time-series images were then obtained from ten subjects including six normal subjects and four patients with pulmonary emphysema to test the feasibility of the proposed technique for capturing xenon-129 gas-transfer dynamics (XGTD). The dynamics of xenon gas diffusion over the entire lung was also investigated by measuring the signal intensity variations between three regions of interest, including the left and right lungs and the heart using Welch’s t test.ResultsThe technique enabled the acquisition of HPX gas and dissolved phase compartment images in a single breath-hold interval of 8 s. The y-intersect of the XGTD curves were also found to be statistically lower in the patients with lung emphysema than in the healthy group (p < 0.05).ConclusionThis time-series IDEAL technique enables the visualization and quantification of inhaled xenon from the alveoli to the left ventricle with a clinical gradient strength magnet during a single breath-hold, in healthy and diseased lungs.Key Points• The proposed hyperpolarized xenon-129 gas and dissolved magnetic resonance imaging technique can provide regional and temporal measurements of xenon-129 gas-transfer dynamics.• Quantitative measurement of xenon-129 gas-transfer dynamics from the alveolar to the heart was demonstrated in normal subjects and pulmonary emphysema.• Comparison of gas-transfer dynamics in normal subjects and pulmonary emphysema showed that the proposed technique appears sensitive to changes affecting the alveoli, pulmonary interstitium, and capillaries.

Improvement ability of EIT for Thermal monitoring during Thermal Therapy by gold nanoparticles

Introduction: To prevention the healthy tissues from irreversible damages, monitoring the temperature variation of healthy tissues is critical parameter during thermal therapies. Electrical impedance tomography (EIT) is considered as a real time imaging modality for monitoring the temperature but researches show that it suffers from low temperature resolution. In this study using of gold nanoparticles(GNPs) to increase the EIT signal variation due to change in temperature of tissues was studied and improvement of its temperature resolution was surveyed. Materials and Methods: Spherical GNPs with size of 20-25 nm were synthesized with Turkevich method. Size distribution and shape of these NPs was characterized by transmission electron microscopy (TEM). EI of muscle and fat tissues at different temperatures were measured and compared to their EI at presence of GNPs. Results: EI of tissues decrease (electrical conductance increase) as their temperature increase and GNPs cause to intensify this phenomenon. Increase in specific conductance of fat and muscle tissues at 360 C were 3.80´10-3 S m and 8.59´10-2 S m, respectively. These values were 15.1% and 13.2% for fat and muscle tissues, respectively. Conclusion: Presence of GNPs could lead to increase the variation of EIT signal intensity due to change of temperature. Therefore, considering the temperature changes followed to use of GNPs in thermal treatment is recommended.

100 - Comparison of sample tubes for the X-band EPR measurement of an aqueous sample: effects on reproducibility of signal intensities

Reproducibility of the X-band EPR measurement of an aqueous solution sample was compared using three different types of sample tubes, and accuracy of quantitative performance was assessed. A PTFE tubing, a glass capillary and a quartz flat cuvette were compared to get a suitable condition for quantitative measurement. An accurate 0.1 mM water solution of TEMPOL was used as a standard sample. The TEMPOL solution was loaded into one of sample tube, and the sample tube was set in the TE-mode cavity of X-band EPR spectrometer. Two procedures below were tested for reproducibility of repeated measurements. 1) The sample tube in the cavity was washed or renewed every measurement, and measurements were repeated several times with fixed EPR parameters. 2) The sample tubes in the cavity were stayed and repeatedly measured several times. Next, EPR parameters such as sweep speed, time constant, modulation width, and/or microwave power were varied to seek optimum signal intensity. The PTFE tubing showed the best reproducibility when the measurements were repeated with staying the sample tube (the ratio of standard deviation to the averaged signal intensity; SD/AV = 0.0058). When the sample and sample tube was renewed every measurement, variation of signal intensity became larger (SD/AV = 0.0333). The glass capillary had the best reproducibility in both procedures 1 and 2 (SD/AV = 0.0104 and 0.0036, respectively). The signal reproducibility of the flat cuvette was relatively low (SD/AV = 0.0400 and 0.0690 for procedures 1 and 2, respectively). However, the flat cuvette gave the largest signal intensity when the loaded volume of the sample was the identical. In conclusion, the best quantitative performance of the X-band EPR spectroscopy for a liquid sample was obtained when the measurements are carried out with the capillary.

Magneto-plasmonic biosensing platform for detection of glucose concentration

A magneto-optical sensor consisting of [Glass/Au/Co/Au/GS] has been simulated for detection of glucose concentration using a combination of surface plasmon resonance and magneto optical Kerr effect. In this optical sensor, plasmon excitation occurs in the Au thin film and Co plays the role of a magnetic layer. Under optimal conditions of Au and Co thicknesses and incident angle, the magneto-optical transverse Kerr signal is amplified, resulting in an increase in optical sensor sensitivity. In fact, the SPR based sensor evaluates changes in refractive index (RI) of GS. The sensor performance is designed based on two approaches: I) angle shift in the minimum of reflection curve and maximum of transverse Kerr signal in the variable incident angle; II) variation of transverse Kerr signal intensity in a fixed incident angle. Our simulations show that the second approach provides a higher sensitivity, being more applicable due to the performance at a fixed incident angle. This simulated sensor has resolution of 0.003 in the RI value which is equivalent to 0.02 g/ml of glucose concentration. These findings can convey a new pathway to integration of surface plasmon excitation and transverse Kerr effect for sensing applications.

Pre-treatment of soil X-ray powder diffraction data for cluster analysis

X-ray powder diffraction (XRPD) is widely applied for the qualitative and quantitative analysis of soil mineralogy. In recent years, high-throughput XRPD has resulted in soil XRPD datasets containing thousands of samples. The efforts required for conventional approaches of soil XRPD data analysis are currently restrictive for such large data sets, resulting in a need for computational methods that can aid in defining soil property – soil mineralogy relationships. Cluster analysis of soil XRPD data represents a rapid method for grouping data into discrete classes based on mineralogical similarities, and thus allows for sets of mineralogically distinct soils to be defined and investigated in greater detail. Effective cluster analysis requires minimisation of sample-independent variation and maximisation of sample-dependent variation, which entails pre-treatment of XRPD data in order to correct for common aberrations associated with data collection.A 24 factorial design was used to investigate the most effective data pre-treatment protocol for the cluster analysis of XRPD data from 12 African soils, each analysed once by five different personnel. Sample-independent effects of displacement error, noise and signal intensity variation were pre-treated using peak alignment, binning and scaling, respectively. The sample-dependent effect of strongly diffracting minerals overwhelming the signal of weakly diffracting minerals was pre-treated using a square-root transformation. Without pre-treatment, the 60 XRPD measurements failed to provide informative clusters. Pre-treatment via peak alignment, square-root transformation, and scaling each resulted in significantly improved partitioning of the groups (p < 0.05). Data pre-treatment via binning reduced the computational demands of cluster analysis, but did not significantly affect the partitioning (p > 0.1). Applying all four pre-treatments proved to be the most suitable protocol for both non-hierarchical and hierarchical cluster analysis. Deducing such a protocol is considered a prerequisite to the wider application of cluster analysis in exploring soil property – soil mineralogy relationships in larger datasets.

High field magnetic resonance imaging is comparable with gross anatomy for description of the normal appearance of soft tissues in the equine stifle.

High field magnetic resonance imaging (MRI) is increasingly used for horses with suspected stifle disease, however there is limited available information on normal imaging anatomy and potential incidental findings. The aim of this prospective, anatomic study was to develop an optimized high field MRI protocol for evaluation of the equine stifle and provide detailed descriptions of the normal MRI appearance of the stifle soft tissues, using ultrasound and gross pathological examination as comparison tests. Nine cadaver limbs were acquired from clinically normal horses. Stifles were evaluated ultrasonographically and then by an extensive 1.5T MRI protocol. Subsequently, all stifles were evaluated for gross pathologic change. Findings were compared between gross evaluation and MRI imaging and described. No soft tissue structure abnormalities were identified on any evaluation. Specific descriptive findings of the meniscotibial, meniscofemoral, collateral, patellar and cruciate ligaments, and the menisci were reported. The high field MRI protocol described in this study provided high spatial and contrast resolution of the soft tissue structures, and this in turn allowed visualization of detailed structural characteristics, such as striations and variations in signal intensity. Findings supported the use of high field MRI as a modality for the evaluation of the soft tissues of the equine stifle. As clinical availability of this modality increases in the future, authors anticipate that new stifle diseases will be detected that have not previously been identified with other imaging modalities.

Influence of k-space trajectory corrections on proton density mapping with ultrashort echo time imaging: Application for imaging of short T2 components in white matter

PurposeTo evaluate the impact of MR gradient system imperfections and limitations for the quantitative mapping of short T2* signals performed by ultrashort echo time (UTE) acquisition approach. Materials and methodsThe measurement of short T2* signals from a phantom and a healthy volunteer study (8 subjects of average age 28 ± 4 years) were performed on a 3T scanner. The characteristics of the gradient system were obtained using calibration method performed directly on the measured subject or phantom. This information was used to calculate the actual sampling trajectory with the help of a parametric eddy current model. The actual sample positions were used to reconstruct corrected images and compared with uncorrected data. ResultsComparison of both approaches, i.e., without and with correction of k-space sampling trajectories revealed substantial improvement when correction was applied. The phantom experiments demonstrate substantial in-plane signal intensity variations for uncorrected sampling trajectories. In the case of the volunteer study, this led to significant differences in relative proton density (RPD) estimation between the uncorrected and corrected data (P = 0.0117 by Wilcoxon matched-pairs test) and provides for about ~15% higher values for short T2* components of white matter (WM) in the case of uncorrected images. ConclusionThe imperfection of the applied gradients could induce errors in k-space data sampling which further propagates into the fidelity of the UTE images and jeopardizes precision of quantification. However, the study proved that measurement of gradient errors together with correction of sample positions can contribute to increased accuracy and unbiased characterization of short T2* signals.

Considerations for Western Blot Normalization Techniques

Western blotting is a well‐established method to specifically measure the relative quantities of individual proteins in complex biological samples. However, data quality may be affected by technical and biological variation. The application of data normalization strategies is strongly recommended to compensate for these non‐sample related variations in signal intensity. Here, we compare the power of two different data normalization strategies, namely housekeeping protein (HKP) and total protein (TP) normalization based on Stain‐free technology to offer an orientation in selecting the appropriate data normalization tool. In brief, HeLa cell lysates were separated with SDS‐PAGE Stain‐free gels and blotted onto a PVDF membrane. Stain‐free imaging after activation with UV was applied to obtain a total protein blot signal. The blot was then treated to the appropriate immuno‐probing steps and the intensity of the target protein ATG7 was recorded by chemiluminescence. In order to illustrate the differences of the two techniques, the membrane was subsequently immuno‐probed for GAPDH as a typical example for housekeeping protein data normalization. Both data sets were used for data normalization of the target protein ATG7. Our results revealed that total protein staining through Stain‐free technology shows less technical variation than HKP recording as represented by GADPH. Additionally, the use of housekeeping proteins as data normalization tool is restricted in its general applicability and may not be compatible with the strict publishing journal guidelines.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Determination of Arsenic by Hydride Generation—Laser-Induced Breakdown Spectroscopy: Characterization of Interelement Interferences

ABSTRACTIn this study, interelement interferences were evaluated for the determination of arsenic in aqueous samples through laser-induced breakdown spectroscopy (LIBS) hyphenated with a hydride generation sample introduction system. Optimum instrumental and chemical parameters were selected and variation in LIBS signal intensity was recorded for As solution in the presence of comparable concentrations of interfering elements. No significant change in the signal intensity of As(I) 228.8 nm line was observed in the presence of alkali/alkali earth metals; however, the presence of hydride-forming elements has shown a noticeable decrease in the line emission strength of arsenic. The least variation in arsenic signal was observed in the presence of Ge, the most volatile of all. However, the signal has decreased to a greater extent in the presence of Sn, Sb, and Pb. The presence of interfering elements on electron temperature and electron number density of arsenic plasma has also been studied. Plasma temperatures calculated using both As and Ar emission lines in the Boltzmann equation were similar, being around 5000 K. The McWhirter criterion for stationary and homogenous plasmas was utilized for the establishment of the local thermodynamic equilibrium under the plasma conditions studied. Applicability of the technique for multielemental analysis of water samples was tested through spiking experiments. Arsenic signal showed 26% decrease in the multielemental mixture solution. LIBS is among a few atomic spectroscopic techniques that facilitate rapid and simultaneous multielemental analysis without extensive sample preparation steps. However, the analytical performance of the technique still requires more serious efforts to compete with other conventional techniques for routine analysis of environmental samples.

Single-grain dating of potassium-rich feldspar grains: Towards a global standardised growth curve for the post-IR IRSL signal

Abstract Potassium-rich feldspar (K-feldspar) grains were extracted from 28 sediment samples from sites in Asia, Europe and Africa and the dose response curves — or growth curves — were constructed from the post-infrared infrared stimulated luminescence (pIRIR) signals emitted by individual grains. The samples exhibit large between-grain variation in both pIRIR signal intensity and the shape of the corresponding growth curves; the latter can be largely explained as a result of measurement uncertainties, including counting statistics and instrumental irreproducibility. This between-grain variation can be reduced by applying a least-squares normalisation (LS-normalisation) procedure, which allows a common growth curve — or global standardised growth curve (gSGC) — to be established for individual K-feldspar grains from the range of samples investigated. Equivalent dose (De) values for single grains can be estimated using the fitting parameters of the gSGC, together with measurements of the natural signal (Ln), one regenerative-dose signal (Lx) and their corresponding test-dose signals (Tn, Tx). The De values obtained using the gSGC approach are consistent at 2σ with those obtained from the individual growth curves constructed for each of the grains. The establishment of a gSGC greatly reduces the time required to measure a large number of grains for old samples, and it also overcomes the problem of De underestimation that can occur using a full single-aliquot (or single-grain) regenerative-dose (SAR) procedure when a large number of grains are rejected due to issues of ‘saturation’. The construction of a gSGC may, therefore, potentially extend the dating range of pIRIR signals beyond the reliable limit of De estimation using the standard SAR method.

Combination of nano-material enrichment and dead-end filtration for uniform and rapid sample preparation in matrix-assisted laser desorption/ionization mass spectrometry

Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is a fast analysis tool for the detection of a wide range of analytes. However, heterogeneous distribution of matrix/analyte cocrystal, variation in signal intensity and poor experimental reproducibility at different locations of the same spot means difficulty in quantitative analysis. In this work, carbon nanotubes (CNTs) were employed as adsorbent for analyte cum matrix on a conductive porous membrane as a novel mass target plate. The sample pretreatment step was achieved by enrichment and dead-end filtration and dried by a solid-liquid separation. This approach enables the homogeneous distribution of analyte in the matrix, good shot-to-shot reproducibility in signals and quantitative detection of peptide and protein at different concentrations with correlation coefficient (R2) of 0.9920 and 0.9909, respectively. The simple preparation of sample in a short time, uniform distribution of analyte, easy quantitative detection, and high reproducibility makes this technique useful and may diversify the application of MALDI-MS for quantitative detection of a variety of proteins.

Characterization of Melanin Radicals in Paraffin-embedded Malignant Melanoma and Nevus Pigmentosus Using X-band EPR and EPR Imaging.

Continuous wave electron paramagnetic resonance (CW EPR) and X-band (9 GHz) EPR imaging (EPRI) were used to nondestructively investigate the possible differentiation between malignant melanoma (MM) and nevus pigmentosus (NP) melanin radicals in paraffin-embedded specimens. The EPR spectra of both samples were analyzed using linewidth, spectral pattern, and X-band EPRI. The CW-EPR spectra of the MM showed an additional signal overlap. Eumelanin- and pheomelanin-related radicals were observed in the MM specimens. The EPR results revealed that the peak-to-peak linewidths (ΔHpp) of paraffin-embedded MM and NP samples were 0.65 ± 0.01 and 0.69 ± 0.01 mT, respectively. The g-value was 2.005 for both samples. Moreover, the two-dimensional (2D) EPRI of the MM showed different signal intensities at the different tumor stages, unlike the NP, which displayed fewer variations in signal intensity. Thus, the present results suggest that EPR and 2D EPRI can be useful for characterization of the two melanin radicals in the MM and for determination of their size and concentration.

Regional Heterogeneity of Lobar Ventilation in Asthma Using Hyperpolarized Helium-3 MRI

To determine lobar ventilation patterns in asthmatic lungs with hyperpolarized 3He magnetic resonance imaging (HP 3He MRI). Eighty-two subjects (14 normal, 48 mild-to-moderate asthma, and 20 severe asthma) underwent HP 3He MRI, computed tomography (CT), and pulmonary function testing. After registering proton to 3He images, we segmented the lungs from proton MRI and further segmented the five lung lobes (right upper lobe [RUL], right middle lobe [RML], and right lower lobe [RLL]; left upper lobe and left lower lobe [LLL]) by referring to the lobar segmentation from CT. We classified the gas volume into four signal intensity levels as follows: ventilation defect percent (VDP), low ventilation percent, medium ventilation percent, and high ventilation percent. The local signal intensity variations in the ventilated volume were estimated using heterogeneity score (Hs). We compared each ventilation level and Hs measured in the whole lung and lobar regions across the three subject groups. In mild-to-moderate asthma, the RML and RUL showed significantly greater VDP than the two lower lobes (RLL and LLL) (P ≤ .047). In severe asthma, the pattern was more variable with the VDP in the RUL significantly greater than in the RLL (P = .026). In both asthma groups, the lower lobes (RLL and LLL) showed significantly higher high ventilation percent and Hs compared to the three upper lobes (all P ≤ .015). In asthma, the RML and RUL showed greater ventilation abnormalities, and the RLL and LLL were more highly ventilated with greater local heterogeneity. These findings may facilitate guided bronchoscopic sampling and localized airway treatment in future studies.

Structural, thermal and optical properties of $${\hbox {Cu}}^{2+}$$ Cu 2 + doped methacrylic acid–ethyl acrylate (MAA:EA) copolymer films

Pure and \({\hbox {Cu}}^{2+}\) doped methacrylic acid–ethyl acrylate (MAA:EA) copolymer films were prepared using the solution cast technique. The amorphous feature of the copolymer was depicted using X-ray diffraction scans and degree of crystallinity was found to vary with increasing doping content. UV–Vis absorption spectra in the wavelength region 200–900 nm were used to evaluate the optical properties like direct band gap, indirect band gap and absorption edge. The optical band gap decreased with the increase of mol% of \(\hbox {Cu}^{2+}\) ions. Fourier transform infrared spectral studies on pure MAA:EA and \(\hbox {Cu}^{2+}\) ions-doped films revealed the vibrational changes that occurred due to the effect of dopant salt in the copolymer. Thermal properties of these films were investigated by employing differential scanning calorimetry and thermogravimetric analysis. The variation in film morphology was examined by scanning electron microscopy. Electron paramagnetic resonance (EPR) spectra of all the doped samples exhibited signals due to \(\hbox {Cu}^{2+}\) ions with the effective g-values \(g_{\Vert } = 2.177\) and \(g_{\bot }= 2.058\). The observed variation in the EPR signal intensity is due to the isolated and aggregated copper ions. The photoluminescence spectra of \(\hbox {Cu}^{2+}\) ions-doped MAA:EA copolymer exhibited four emission peaks at 480 (blue), 579 (yellow), 604 (red) and 671 nm (red).