Intrinsic Structural Changes Research Articles

Supranormal Left Ventricular Ejection Fraction, Concentric Remodeling, and Long-Term Survival

BackgroundSupranormal left ventricular ejection fraction (LVEF) confers a paradoxically higher mortality risk; however, whether intrinsic structural changes of left ventricle (LV) play an important role remain unclear. ObjectivesThe authors sought to investigate the prognostic implication of supranormal LVEF and its interaction with LV concentric remodeling. MethodsConsecutive participants undergoing echocardiography in a tertiary medical center with LVEF >60% were included. LV concentric remodeling was defined as LV relative wall thickness >0.42. The primary outcome was all-cause mortality. The association between LVEF and all-cause mortality was assessed using Cox models and restricted cubic splines. Subgroup analysis was performed to evaluate the association between LVEF and risk of death stratified by LV concentric remodeling. ResultsIn total, 67,108 participants (age 60.5 ± 17.2 years, men 44.6% [n = 29,924]) were included. 7,029 deaths of 67,108 (10.5%) occurred over a median of 50.3 months (Q1, Q3: 20.9, 91.3 months). In multivariable Cox models, subjects with LVEF above 70% had a significantly higher risk (vs 60%-65%) for all-cause mortality (adjusted HR: 1.15; 95% CI: 1.05-1.26; P = 0.003) after adjusting for potential confounders. A significant interaction was observed between LVEF and LV concentric remodeling (P for interaction <0.001), particularly in women, such that a higher mortality risk of supranormal LVEF could be observed mainly among those with LV concentric remodeling. ConclusionsSupranormal LVEF >70% is associated with a greater risk for all-cause mortality. The higher mortality risk could be predominantly observed among individuals presented with LV concentric remodeling, particularly in women.

Distribution recurrence plots and measures: Effective signal analysis tools for fault diagnosis of wind turbine drivetrain system

Extracting sensitive information from vibration signal has become a frequently adopted way in fault diagnosis. However, most previous methods fragmented the relationship between quantification and visualization analysis, which affects the interpretability, accuracy and comprehensiveness of the extracted information. To this end, this paper proposes distribution recurrence plots (DRP) and measures (DRM) to realize the unity of visualization and quantification analysis of the signals. Specifically, DRP is a novel feature graphical representation method following the thought of symbolic dynamics. Derived from DRP, DRM is developed containing four quantifiers for extracting comprehensive fault features that allows a multiclass support vector machine (SVM) to identify the fault types of wind turbine drivetrain system (WTDS). Specially in DRM, pattern entropy is a newly designed quantifier by considering pattern distribution to obtained more accurate quantitative representation of the signals. Using simulated data, DRP and DRM are validated to reveal the intrinsic structural changes for different dynamic systems and robustness to noise. Applications on wind turbine gearbox illustrate that the proposed method has favorable diagnosis performance and stability compared with other competitors. This approach is easy to interpret, is robust to noise, and has a low computational burden, becoming viable for WTDS fault diagnosis.

The differences between mass- and light-derived structural parameters over time for MaNGA elliptical galaxies

ABSTRACTWe apply stellar population synthesis analysis to obtain spatially resolved archaeological inferences for a large sample of ‘red and dead’ Elliptical galaxies (Classical Ellipticals, CLEs) from the MaNGA/SDSS-IV DR15 survey. From their 2D stellar light and mass maps, we explore the differences between the radial mass and light distributions in the rest-frame bands g, r, and i as functions of look-back time, tlb, or redshift, z. We characterize these differences through the ratios between the following mass- and light-derived global properties: sizes, concentrations, and effective surface densities. We find that the mass-to-light ratios of these properties change with tlb, more the more massive the galaxies are. The CLE galaxy archaeological progenitors are, on average, less compact, concentrated, and dense in light than in mass as z decreases. However, at later times, when also the evolution of the progenitors becomes passive at all radii, there is an upturn in these trends and the differences between mass and light in compactness/concentration decrease towards z ∼ 0. The trends in the ratios of mass-to-light sizes agree qualitatively with results from direct observations in galaxy surveys at different redshifts. We discuss the caveats and interpretations of our results, and speculate that the strong structural evolution found in some previous studies for early-type galaxies could be explained partially by photometric changes rather than by intrinsic structural changes.

Structural and Functional Brain Changes in Hemodialysis Patients with End-Stage Renal Disease: DTI Analysis Results and ALFF Analysis Results.

IntroductionThe current study aimed to depict intrinsic structural changes and the spontaneous brain activity patterns in voxel level in patients with end-stage renal disease (ESRD) undergoing hemodialysis (HD) by using diffusion-tensor imaging and resting-state functional magnetic resonance (MR) imaging with an amplitude of low-frequency fluctuations (ALFF) algorithm and their clinical relevance.Materials and MethodsIn the study, the diffusion-tensor imaging and resting-state functional MR imaging were performed in forty-two hemodialysis patients with ESRD and 42 healthy control subjects. Neuropsychological and laboratory tests were performed in all subjects. ALFF, fraction anisotropy (FA), and mean diffusivity (MD) values were compared between the two groups. Correlations between ALFF, FA or MD values, and clinical markers were analyzed.ResultsWe found that ESRD patients exhibited significantly lower ALFF values in multiple areas, including medial frontal gyrus, limbic lobe, superior frontal gyrus, bilateral lingual gyri, occipital lobe, parahippocampal gyrus, precuneus, while increased ALFF values in medial frontal gyrus than healthy controls. FA values were decreased in medial frontal gyrus, parietal lobe, and left precuneus regions in the ESRD group compared with controls. Importantly, FA for the frontal and parietal lobes was negatively associated with the dialysis duration of ESRD patients, ALFF z-scores for the medial prefrontal cortex (MPFC) were positively correlated with the dialysis duration of ESRD patients and Serum calcium of ESRD patients negatively correlated with FA values in the frontal and parietal lobes (p<0.05).ConclusionOur study revealed that both impaired brain structure and function in ESRD patients with routine hemodialysis distributed mainly in the parietal, temporal, and frontal lobes. ESRD patients have cognitive impairment and declined memory ability. Serum calcium and dialysis duration might be associated with the impairment of brain structure and function in patients with ESRD.

Multi-Scale Structural Assessment of Cellulose Fibres Cement Boards Subjected to High Temperature Treatment.

The methodology of multi-scale structural assessment of the different cellulose fibre cement boards subjected to high temperature treatment was proposed. Two specimens were investigated: Board A (air-dry reference specimen) and Board B (exposed to a temperature of 230 °C for 3 h). At macroscale all considered samples were subjected to the three-point bending test. Next, two methodologically different microscopic techniques were used to identify evolution (caused by temperature treatment) of geometrical and mechanical morphology of boards. For that purpose, SEM imaging with EDS analysis and nanoindentation tests were utilized. High temperature was found to have a degrading effect on the fibres contained in the boards. Most of the fibres in the board were burnt-out, or melted into the matrix, leaving cavities and grooves which were visible in all of the tested boards. Nanoindentation tests revealed significant changes of mechanical properties caused by high temperature treatment: “global” decrease of the stiffness (characterized by nanoindentation modulus) and “local” decrease of hardness. The results observed at microscale are in a very good agreement with macroscale behaviour of considered composite. It was shown that it is not sufficient to determine the degree of degradation of fibre-cement boards solely on the basis of bending strength; advanced, microscale laboratory techniques can reveal intrinsic structural changes.

Physicochemical investigations, biological studies of the Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Hg(II) and UO2(VI) complexes of picolinic acid hydrazide derivative: A combined experimental and computational approach

Assessment of the intrinsic structural changes inflicted by metal coordination in the molecular geometries of (E)-2-(2-picolinoyhydrazono) propanoic (H2PAP) is of fundamental importance for proper characterization and understanding of the structure–activity relationships. Efforts are being made here to investigate the coordination properties of (H2PAP) as a potential metal-binding entity involving a combined solid state synthetic and computational approach. The metal complexes of (H2PAP) with the divalent cations of manganese, cobalt, nickel, copper, zinc and cadmium also trivalvent chromium and iron in addition to hexavalent uranium are characterized by elemental analyses, TG/DTA, infrared, nuclear magnetic resonance (1H-, 13C-), electronic absorption, as well as magnetic studies. Analysis of the geometrical parameters suggests significant changes in the molecular structure of (H2PAP) coordination with metallic centers. Hg complex is found to have antifungal activity against C. albicans showing 71.4% of the activity clotrimazole. Hg(II) and Cd(II) chelates have highly activity against Gram-negative E.coli with 75% and 62.5% whereas Hg(II) and Cd(II) complexes showed moderate activity against the Gram-positive S. aureus with 54.5 and 27.3%, respectively compared to ampicillin. H2PAP and its metal complexes indicate that Fe(III) and Mn(II) complexes exhibit the potent antioxidative activity for quenching phenazin methosulphate radicals at 99.2% and 84.5% inhibition respectively. It was found that Mn (II), Cu (II), Cd (II), Co (II) and Ni (II) complexes were the most active compound exhibiting a DPPH radical scavenging activity, 77.7, 70.4, 69.3, 67.8 and 67.2% inhibition, respectively.

The role of stem cells in anti-aging medicine

Aging is the result of two overlapping processes, “intrinsic” and “extrinsic.” Intrinsic structural changes occur as a consequence of physiologic aging and are genetically determined; extrinsic relates to exposure to harmful events and habits, like smoking, bad diet, alcohol consumption, lack of sleep, stress, sun exposure, environmental pollution, etc. Aging may be decelerated by improving bad habits or treating signs of aging with various esthetic methods, food supplements, and antioxidants. It is believed that we cannot stop aging entirely due to the intrinsic part, which leads to irreversible cell damage, as well as tissue and organ damage due to their limited ability to regenerate. Stem cells and their ability to exhibit telomerase activity, to self-renew, and to differentiate into all three embryonic tissues challenges aging as a process, which is not inevitable and can even possibly be reversed. Stem cells can promote regeneration of aged tissues and organs by replacing apoptotic and necrotic cells with healthy ones. In addition, they can have antiinflammatory and antiapoptotic properties by paracrine-secreting growth factors and cytokines on the site of administration. Autologous adipose-derived stem cells are the most promising because they can be easily harvested in huge numbers with minimally invasive liposuction and, as such, represent a powerful tool in anti-aging and regenerative medicine. In this contribution, the author discusses their properties and application in clinical practice.

S-Edge-rich MoxSy arrays vertically grown on carbon aerogels as superior bifunctional HER/OER electrocatalysts.

Molybdenum disulfide (MoS2) is a potential earth-abundant electrocatalyst for the hydrogen evolution reaction (HER), but the lack of in-depth understanding of its intrinsic activity still impedes the further optimization and design of MoS2-based electrocatalysts. Herein, we report a facile in situ hydrothermal synthetic method to prepare vertical MoxSy arrays grown on guar gum-derived carbon aerogels (GCA), termed MoxSy@GCA. The obtained well-assembled MoxSy@GCA architectures consist of uniform, few-layered and S-edge-rich MoxSy nanoflakes with a length of approximately 100 nm, which effectively prevent the inherent stacking among MoxSy layers and connect the charge transfer path between interlayers, thus endowing MoxSy@GCA with a huge number of active sites and high conductivity. Benefitting from all these advantages, the optimal Mo4S16@GCA exhibited extraordinary HER/OER performances, including a low onset potential for both the HER (24.28 mV) and OER (1.53 V), and a low overpotential at 10 mA cm-2 for the HER (54.13 mV) and OER (370 mV), which are both extremely close to that of the noble Pt/C. Furthermore, a series of operando Raman spectroscopy measurements on Mo4S16@GCA were conducted to identify the intrinsic HER/OER-active sites during the HER and OER process. The results show that the S-H bond is generated simultaneously as HER/OER excitation, indicating the rich S-edge may be the intrinsic active site, which will accelerate the HER/OER kinetic process. Density functional theory (DFT) calculations revealed that the observed superb HER/OER activity can be attributed to the synergistic effect of rich S-edge of MoxSy and confinement effect of GCA, which collaboratively promote the proton adsorption and electrocatalytic kinetics. Reasonably, this study will have profound guiding value for the rational tailoring of the microstructure and size of transition metal electrocatalysts via hierarchical porous carbon aerogels.

Stability of Perovskites at the Surface Analytic Level.

Organic-inorganic halide perovskites have attracted considerable attention in the past few years because of their remarkable performance in optoelectronic devices. However, long-term stability of the materials and devices remains the biggest challenge for realistic implementation of perovskite solar cells. Although significant efforts have been carried out on the causes of degradation at the device level, few measurements have been made at the surface analytic level to reveal the degradation mechanisms. In this Perspective, we review the effects of environmental factors, such as O2, water, and light, on the perovskite layer by monitoring the intrinsic electronic structure and compositional changes in different exposure tests. This work contributes in developing better understanding of the degradation mechanisms and improving the overall stability of perovskite solar cells.

Domain-functional analyses of PIWIL1 and PABPC1 indicate their synergistic roles in protein translation via 3'-UTRs of meiotic mRNAs.

Translational regulation plays a central role during post-meiotic development of male germ cells. Previous studies suggested that P-element induced wimpy testis like 1 (PIWIL1), a PIWI-interacting RNA (piRNA) binding protein that is critical for sperm development, participates in the maintenance and translational regulation of post-meiotic mRNAs in haploid spermatids. However, how PIWIL1 regulates protein translation remains largely unclear. Using biochemical assays, we show here that PIWIL1 utilizes different domains to interact with post-meiotic mRNAs and Poly-A binding protein cytoplasmic 1 (PABPC1), a general protein translation regulator. PIWIL1 binds 3'-untranslated regions (3'-UTRs) of several spermiogenic mRNAs via its N-terminal domain, whereas its interactions with PABPC1 are mediated through its N- and C-terminal domains in an RNA-dependent manner. Using a heterologous cell system, we analyzed its effects on protein translation via luciferase reporter assay and sucrose gradient sedimentation. It was found that PIWIL1 augments protein translation with PABPC1 in the presence of 3'-UTRs of post-meiotic mRNAs. While both the N-terminal RNA recognition motif (RRM) domain and the central linker region of PABPC1 stimulate translation, only the PIWI Argonaute and Zwille (PAZ) domain of PIWIL1 positively affects translation of reporter mRNAs. Interestingly, the PAZ domain was found absent from polysomal fractions, in contrast to the N- and C-terminal domains of PIWIL1. Taken together, the results suggest that PIWIL1 interacts with various partners using different domains and participates in translational regulation partly through 3'-UTRs. It will be of interest to further explore how PIWIL1 elicit its versatile functions, including translational regulation of post-meiotic mRNAs through intrinsic structural changes and extrinsic signals during mouse spermiogenesis under more physiological settings.

Electrochemical characterizations of darbufelone, a di-tert-butylphenol derivative, by voltammetric techniques and density functional theory calculations

Darbufelone is a dual cyclooxygenase/lypoxygenase inhibitor that is emerging as a novel option for the treatment of inflammatory diseases. Akin to the synthetic antioxidants, butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA), the electroactive di-tert-butylphenol moiety is also present in the darbufelone structure thus conferring reducing properties. The antioxidant properties of darbufelone BHT and BHA can be studied by means of voltammetric techniques while the influence of intrinsic molecular structural changes can be correlated to molecular electrostatic potential (MEP) and HOMO/LUMO energy profiles. In this report, the overall electronic structure of the darbufelone BHT and BHA for lowest energy enantiomorphs were computed. A comparison between the experimental and computational theoretical results was drawn. The charge distributions for the lowest energy enantiomorphs were evaluated for reduced and oxidized species in order to bring new insights about their redox properties. The electrochemical oxidation of BHT and BHA occurs in one-step, at peak potentials below 0.5 V. The redox behavior of darbufelone is characterized by two anodic peaks at Ep1a ∼0.2 V and Ep2a ∼0.5 V, and a less intense cathodic peak at Ep1c ∼0.2 V. Square wave voltammetric measurements were performed to confirm the reversibility and/or irreversibility of redox processes. From the HOMO energies calculated for BHT, BHA and darbufelone isomers, it was possible to infer that both anodic processes of darbufelone are related to the difference in the electronic structure of the diastereosiomers, which are further separated due to the passivation of the electrode surface by the isomers oxidized in the Ep1a ∼0.2 V anodic peak.

Alteration of biomacromolecule in corn by steam flaking in relation to biodegradation kinetics in ruminant, revealed with vibrational molecular spectroscopy

Large scale of steam flaked corn has been used in dairy ration to maintain high milk production level. This study aimed to determine effects of steam flaking on processing-induced intrinsic molecular structure changes that were associated with rumen degradation kinetics and nutrients supply. The advanced vibrational molecular spectroscopy was applied to reveal the processing-induced intrinsic structure changes on a molecular basis. The rumen degradation kinetics and nutrient supply were determined using in situ approach in ruminant livestock system. Raw corn grain (RC) and steam flaked corn grain (SFC) were obtained from two different processing plants. The results showed that (1) Compared to RC, SFC had greater truly digestible non-fiber carbohydrate [tdNFC: 86.8 versus 78.0% dry matter (DM)], but lower truly digestible crude protein [tdCP: 7.7 versus 9.0% DM]. (2) The steam flaking increased (P<0.01) rumen degradable DM (RDDM) and starch (RDSt), but decreased (P<0.01) rumen degradable protein (RDP). (3) Molecular absorbance intensities of most carbohydrate biopolymers were greater in SFC (P<0.01), but protein amides associated molecular spectral intensities were lower (P<0.01) in SFC. (4). The molecular structure and nutrient interactive study showed that carbohydrate spectral intensities were positively (P<0.10) associated with RDDM and RDSt and protein amide spectral intensities were positively (P<0.10) associated with RDP. This results indicated that the steam flaking induced molecular structure changes had an interactive relationship with rumen degradation kinetics.

Influence of cerebrovascular disease on brain networks in prodromal and clinical Alzheimer's disease.

Network-sensitive neuroimaging methods have been used to characterize large-scale brain network degeneration in Alzheimer's disease and its prodrome. However, few studies have investigated the combined effect of Alzheimer's disease and cerebrovascular disease on brain network degeneration. Our study sought to examine the intrinsic functional connectivity and structural covariance network changes in 235 prodromal and clinical Alzheimer's disease patients with and without cerebrovascular disease. We focused particularly on two higher-order cognitive networks-the default mode network and the executive control network. We found divergent functional connectivity and structural covariance patterns in Alzheimer's disease patients with and without cerebrovascular disease. Alzheimer's disease patients without cerebrovascular disease, but not Alzheimer's disease patients with cerebrovascular disease, showed reductions in posterior default mode network functional connectivity. By comparison, while both groups exhibited parietal reductions in executive control network functional connectivity, only Alzheimer's disease patients with cerebrovascular disease showed increases in frontal executive control network connectivity. Importantly, these distinct executive control network changes were recapitulated in prodromal Alzheimer's disease patients with and without cerebrovascular disease. Across Alzheimer's disease patients with and without cerebrovascular disease, higher default mode network functional connectivity z-scores correlated with greater hippocampal volumes while higher executive control network functional connectivity z-scores correlated with greater white matter changes. In parallel, only Alzheimer's disease patients without cerebrovascular disease showed increased default mode network structural covariance, while only Alzheimer's disease patients with cerebrovascular disease showed increased executive control network structural covariance compared to controls. Our findings demonstrate the differential neural network structural and functional changes in Alzheimer's disease with and without cerebrovascular disease, suggesting that the underlying pathology of Alzheimer's disease patients with cerebrovascular disease might differ from those without cerebrovascular disease and reflect a combination of more severe cerebrovascular disease and less severe Alzheimer's disease network degeneration phenotype.

Voltage Dependence of Conformational Dynamics and Subconducting States of VDAC-1

The voltage-dependent anion channel 1 (VDAC-1) is an important protein of the outer mitochondrial membrane that transports energy metabolites and is involved in apoptosis. The available structures of VDAC proteins show a wide β-stranded barrel pore, with its N-terminal α-helix (N-α) bound to its interior. Electrophysiology experiments revealed that voltage, its polarity, and membrane composition modulate VDAC currents. Experiments with VDAC-1 mutants identified amino acids that regulate the gating process. However, the mechanisms for how these factors regulate VDAC-1, and which changes they trigger in the channel, are still unknown. In this study, molecular dynamics simulations and single-channel experiments of VDAC-1 show agreement for the current-voltage relationships of an “open” channel and they also show several subconducting transient states that are more cation selective in the simulations. We observed voltage-dependent asymmetric distortions of the VDAC-1 barrel and the displacement of particular charged amino acids. We constructed conformational models of the protein voltage response and the pore changes that consistently explain the protein conformations observed at opposite voltage polarities, either in phosphatidylethanolamine or phosphatidylcholine membranes. The submicrosecond VDAC-1 voltage response shows intrinsic structural changes that explain the role of key gating amino acids and support some of the current gating hypotheses. These voltage-dependent protein changes include asymmetric barrel distortion, its interaction with the membrane, and significant displacement of N-α amino acids.

Structural and Functional Changes of the Invariant NKT Clonal Repertoire in Early Rheumatoid Arthritis.

Invariant NKT cells (iNKT) are potent immunoregulatory T cells that recognize CD1d via a semi-invariant TCR (iNKT-TCR). Despite the knowledge of a defective iNKT pool in several autoimmune conditions, including rheumatoid arthritis (RA), a clear understanding of the intrinsic mechanisms, including qualitative and structural changes of the human iNKT repertoire at the earlier stages of autoimmune disease, is lacking. In this study, we compared the structure and function of the iNKT repertoire in early RA patients with age- and gender-matched controls. We analyzed the phenotype and function of the ex vivo iNKT repertoire as well as CD1d Ag presentation, combined with analyses of a large panel of ex vivo sorted iNKT clones. We show that circulating iNKTs were reduced in early RA, and their frequency was inversely correlated to disease activity score 28. Proliferative iNKT responses were defective in early RA, independent of CD1d function. Functional iNKT alterations were associated with a skewed iNKT-TCR repertoire with a selective reduction of high-affinity iNKT clones in early RA. Furthermore, high-affinity iNKTs in early RA exhibited an altered functional Th profile with Th1- or Th2-like phenotype, in treatment-naive and treated patients, respectively, compared with Th0-like Th profiles exhibited by high-affinity iNKTs in controls. To our knowledge, this is the first study to provide a mechanism for the intrinsic qualitative defects of the circulating iNKT clonal repertoire in early RA, demonstrating defects of iNKTs bearing high-affinity TCRs. These defects may contribute to immune dysregulation, and our findings could be exploited for future therapeutic intervention.

Reversible Piezofluorochromic Property and Intrinsic Structure Changes of Tetra(4-methoxyphenyl)ethylene under High Pressure.

During the past decade, luminescent mechanochromism has received much attention. Despite the garnered attention, only a few studies have reported the effect of internal molecular structure change on the performance of mechanochromic fluorescence. Here, we chose tetra(4-methoxyphenyl)ethylene (TMOE) as a model molecule to study the correlation between structure and fluorescence property under a hydrostatic pressure produced by a diamond anvil cell (DAC). TMOE is a methoxy-substituted tetraphenylethylene (TPE) derivative and has a nearly centrosymmetric structure and a natural propeller shape. Ultraviolet-visible absorption and fluorescence spectra of TMOE and TPE in solution proved that the presence of methoxy groups in TMOE is responsible for the difference in fluorescence emissions of TMOE and TPE. Under a hydrostatic pressure, the in situ fluorescence spectra of TMOE at different concentrations show that the fluorescence intensity gradually weakens, accompanied by an obvious redshift. The Raman peak intensities decrease gradually, and the peaks disappear eventually with the pressure increasing. These spectral changes are attributed to the changes in the intramolecular conformation, that is, the strengthening of the weak C-H···O hydrogen bonds in TMOE molecules, which is caused by the twisted dihedral angle between the benzene ring and the carbon rigid plane of ethylene. Density functional theory simulation further confirms that the decreased dihedral angle could weaken Raman peak intensity, which is consistent with our experimental results.

Mg-O-Si Chemical Bond Formation in Light Burned Magnesia and Fumed Silica Mixture During Mechanical Activation

Mg-O-Si chemical bond formation in a light burned magnesia (MgO) and fumed silica (SiO2) mixture during mechanical activation was investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), magic angle spinning nuclear magnetic resonance (MAS-NMR), and X-ray photoelectron spectroscopy (XPS). Crystallinity and intrinsic structure changes of the starting mixture during high-energy milling were examined by XRD. The formation of new Mg-O-Si chemical bonds of the ground mixture was illustrated by the incorporation of Mg2+ in Si-O-Si linkages, the appearance of new resonance in the 29Si NMR spectrum and the decrease of the Si 2p binding energy. The formation of Mg-O-Si chemical bonds created during grinding partly contributed to the lowered temperature of complete forsterite formation from 1400 to 1100°C.

First observation of the temperature-dependent light-induced response of Ge(25)As(10)Se(65) thin films.

Ge-rich ternary chalcogenide glasses (ChGs) exhibit photobleaching (PB) when illuminated with bandgap light. This effect originates from the combined effects of intrinsic structural changes and photo-oxidation. In a sharp contradiction to previous observations, in this Letter, we demonstrate, for the first time, that Ge-rich Ge(25)As(10)Se(65) ChG thin films exhibit photodarkening (PD) at 20 K and PB at 300 and 420 K after having been continuously illuminated for ∼3 hours. The temporal evolution of PD/PB shows distinct characteristics at the temperature of illumination, and provides valuable information on the light-induced structural changes. Furthermore, structure-specific far-infrared (FIR) absorption measurements give direct evidence of different structural units involved in PD/PB at the contrasting temperatures. By comparing the light-induced effects in vacuum and air, we conclude that intrinsic structural changes dominate over photo-oxidation in the observed PB in Ge(25)As(10)Se(65) ChG thin films.

P12.10 * 5-ALA GUIDED REMOVAL AND COMBINED TREATMENT IN MALIGNANT GLIOMA

INTRODUCTION: Malignant gliomas are the most unfavourable brain tumours. Recent evidence suggests that extensive tumour removal is associated with better survival. The current treatment is complete as possible resection of the contrast-enhancing tumour tissue, followed by adjuvant treatment with radiotherapy and chemotherapy. As it appears difficult to distinguish between infiltration tumour and normal tissue, specially in recurrent tumours, the radical removal becomes harmful. Techniques to visualize the borderline tumour intraoperatively are helpful. More recently, fluorescence guidance has taken advantage of intrinsic metabolic and structural changes that occur within malignant glioma by exploiting the eme biosynthetic pathway and a natural biochemical in that pathway, 5-aminolevulinic acid (5-ALA). METHODS: Since the end of 2009, in our Institute 54 patients were operated on using fluorescence guided tumour resection. Preoperatively, all enrolled patients had MRI showing contrast enhancing lesions. MRI within 72 hours after surgery and thereafter at 3-month interval was performed. 32 patients were newly diagnosed tumour, 22 were recurrent malignant glioma. An oral dose of 20 mg 5-ALA /kg body weight was administered to each patient. By a NC4 OPMI Pentero operating microscope (Zeiss), enabled switching from xenon light to violet-blue light for visualizing fluorescence, the surgical resection was performed. Histology was in 48 glioblastoma (1 gliosarcoma), in 4 anaplastic oligodendroglioma, in 1 oligodendroglioma I WHO and in 1 pleomorphic xanthoastrocytoma. All the patients, as first line treatment, were submitted to radiotherapy and chemotherapy; in recurrent tumours second and in some cases third line treatments were administered. The follow-up ranged from 2 years to 8 months. RESULTS: In all cases the yellow fluorescence due to 5-ALA in cortical vessels was seen. In 47 glioblastoma, 4 anaplastic oligodendroglioma and 1 xanthoastrocytoma the tumour tissue showed intraoperative red fluorescence. Specially in recurrent tumours, the fluorescence-guided surgery was helpful to identify, inside the gliotic tissue, some areas with active tumour from perilesional “healthy” brain. Furthermore, after surgery no relevant neurological deficit caused by 5-ALA guided resection were observed. Early postoperative MRI confirmed gross total resection without contrast enhancment in 80 % of patients. At the follow-up 24 patients are still alive. CONCLUSIONS: The 5-ALA was helpful to localize the tumour on the cortex and extended resection of infiltrating tumour, specially in recurrence. Patients affected by glioblastoma are elctive for this technique. Extended resections by 5-ALA fluorescence guide does not impair neurological functions and can impact on the overall survival of patients affected by malignant glioma.

In‐Situ Raman Spectroscopy Study of Photoinduced Structural Changes in Ge‐rich Chalcogenide Films

Very few studies have been directed at the compositional dependence of the intrinsic photostability of the GexSe1−x binary ChG films especially for the Ge‐rich films with the mean coordination number (MCN) larger than 2.67. Here, by measuring the in‐situ transmission changes, it shows that the photosensitivity (e.g., photobleaching, PB) of the Ge‐rich films (as compared to the GeSe2 film) is attenuated, in fact almost completely eliminated in the film with the largest MCN. A straightforward technique, in‐situ Raman spectroscopy, is used to record the time‐resolved intrinsic structural changes during the irradiation of the films. The result indicates a transition from PB towards photostability occurs at the critical composition of GeSe2 corresponding to the structural phase transition. The stressed rigid structures of the Ge‐rich films inhibit any significant photo‐structural changes.