•Dy3+ ions doped ZnNaPbB were synthesized by melt quenching technique.•Emission spectra consist of three peaks in the visible region under 350 nm excitation.•Calculated CIE coordinates for all ...glasses are close to the standard white point.•ZnNaPbBDy0.5 glass is optimized glass and more efficient for luminescence applications.
In this report, we present a comprehensive explanation of the luminescent features of Dy3+-ions doped Zinc Sodium Lead Borate (ZnNaPbB) glasses through various characterizations like UV–Vis-NIR, absorption and emission spectroscopy. The absorption spectra were used to determine the optical bandgap (Eopt) and Urbach energy (ΔE). The emission spectra are dominated by three peaks (strong yellow, blue and weak red) in the visible range at 481 nm, 575 nm and 664 nm. The CIE coordinates lie in the pure white region of the chromaticity diagram indicating that the as-prepared glasses have possible applications for optoelectronic devices.
Local motifs in GeS2–Ga2S3 glasses Pethes, I.; Nazabal, V.; Chahal, R. ...
Journal of alloys and compounds,
07/2016, Letnik:
673
Journal Article
Recenzirano
Odprti dostop
The structure of (GeS2)0.75(Ga2S3)0.25 and (GeS2)0.83(Ga2S3)0.17 glasses was investigated by Raman scattering, high energy X-ray diffraction and extended X-ray absorption fine structure (EXAFS) ...measurements at the Ga and Ge K-edges. The reverse Monte Carlo simulation technique (RMC) was used to obtain structural models compatible with diffraction and EXAFS datasets. It was found that the coordination number of Ga is close to four. While Ge atoms have only S neighbors, Ga binds to S as well as to Ga atoms showing a violation of chemical ordering in GeS2–Ga2S3 glasses. Analysis of the corner- and edge-sharing between GeS4/2 units revealed that about 30% of germanium atoms participate in the edge-shared tetrahedra.
•Structural models of GeS2–Ga2S3 glasses consistent with XRD + EXAFS data are created.•Chemical order is respected but Ga–Ga bonds are present caused by S-deficiency.•The coordination number of Ga is 3.7 ± 0.3.•The frequency and geometry of corner/edge-sharing GeS4/2 units were determined.
The structure of Ge22Ga3Sb10S65 and Ge15Ga10Sb10S65 glasses was investigated by neutron diffraction (ND), X-ray diffraction (XRD), and extended X-ray absorption fine structure (EXAFS) measurements at ...the Ge, Ga and Sb K-edges. Experimental data sets were fitted simultaneously in the framework of the reverse Monte Carlo (RMC) simulation technique. Short range order parameters were determined from the obtained large-scale configurations. It was found that the coordination numbers of Ge, Sb and S are around the values predicted by the Mott-rule (4, 3 and 2, respectively). The Ga atoms have on average 4 nearest neighbors. The structure of these stoichiometric glasses can be described by the chemically ordered network model: Ge-S, Ga-S and Sb-S bonds are the most important. Long Sb-S distances (0.3–0.4 Å higher than the usual covalent bond lengths) are observed, suggesting that Sb atoms can be found in various local environments.
•Structure of Ge22Ga3Sb10S65 and Ge15Ga10Sb10S65 glasses was investigated.•Structural models consistent with diffraction (ND, XRD) and EXAFS data was created.•The coordination numbers of Ge, Ga, Sb and S atoms are 4, 4, 3 and 2, respectively.•Structure of these glasses can be described by the chemically ordered network model.
Chemical order in Ge-Ga-Sb-Se glasses Pethes, I.; Chahal, R.; Nazabal, V. ...
Journal of non-crystalline solids,
03/2018, Letnik:
484
Journal Article
Recenzirano
Odprti dostop
The short range order in Ge30Ga5Sb10Se55 and Ge21Ga5Sb10Se64 glasses was investigated by X-ray (XRD) and neutron diffraction (ND) as well as extended X-ray absorption fine structure (EXAFS) ...measurements at the Ge, Ga, Sb and Se K-edges. Large scale structural models were obtained by fitting simultaneously the experimental data sets by reverse Monte Carlo (RMC) simulation technique. It was found that Ge, Sb and Se atoms follow the Mott-rule and have 4, 3 and 2 nearest neighbors, respectively. The average coordination number of the Ga atoms was around 4. The structure of these glasses can be described by the chemically ordered network model: the Ge–Se, Ga–Se and Sb–Se bonds are the most prominent while Ge–Ge and Ge–Sb bonds are formed only in Se-poor compositions. Models generated by RMC contained some long distances (0.3–0.4 Å higher than the usual covalent bond lengths) between Ge–Se and/or Ge–Ge pairs. Dedicated simulation runs confirm the existence of these bonds.
•Structural models of GeGaSbSe glasses consistent with multiple datasets are created.•These glasses can be described by the chemically ordered network model.•Ge, Sb, Se and Ga atoms have 4, 3, 2 and 4 nearest neighbors, respectively.•Ge-Ge (or Ge–Ga) bonds can be found in both Se deficient glasses.•In Ge30Ga5Sb10Se55 glass Ge–Sb bonds also exist.
We report on the mid-wave infrared (MWIR) and long-wave infrared (LWIR) emissions of a 1000 ppm Dy3+ doped Ga5Ge20Sb10Se65 chalcogenide fiber. Following a short-wave infrared (SWIR) optical pumping ...at 0.92, 1.12 and 1.32 μm using commercial laser diodes, LWIR luminescence around 7.3 μm (6H7/2 → 6H9/2 transition) was recorded for the first time to the best of our knowledge along with MWIR emissions around 4.3 μm and 5.4 μm with a Dy3+ doped Ga5Ge20Sb10Se65 fiber. Frequency dependent spectroscopic investigation clearly shows that this LWIR luminescence originates from the 6H7/2 manifold. Spectroscopic properties of this Dy3+ doped material and the comparison with its equivalent sulfide Dy3+:Ga5Ge20Sb10S65 glass are presented.
•Dy3+ doped chalcogenide glasses.•Infrared spectroscopy.•Rare-earth LWIR luminescence in selenide based glasses.•Comparative study with respect to the equivalent sulfide glass.
The 3-15 μm range is a key region for a large number of applications in diverse areas such as biology and medicine, molecular spectroscopy, ground based and space borne environmental monitoring but ...also an important issue of instrumentation for astronomy and astrophysics to achieve complex but very reliable instruments. Going to the mid IR region is crucial for the observation of warm objects around 300 K and the characterization of their spectral features, considered as signatures for biological activity (e.g. Water, ozone, carbon dioxide). Most infrared signatures or "fingerprints" (fundamental transitions) of organic species and bio molecules are essentially located in this spectral window. Thus, infrared spectroscopy is a powerful tool for detecting and determining the composition of complex samples, it is simple, reliable, fast, cost-efficient and non-destructive method. Then, it is crucial to be able to work at the extension toward thermal IR waveguides, where chalcogenide glasses provide promising properties, specifically their extended optical transmission window from the visible to the far infrared (up to 20 μm).
Acute painless bilateral foot drop without bowel/bladder involvement is a very rare presentation of lumbar degenerative disorders. Only a few cases have been published on it in the literature. An ...early intervention could prove to be very helpful for the neurological recovery.
We present three cases where patients developed acute onset bilateral foot drop without radiculopathy and without bowel/bladder involvement. The first case was due to acute lumbar disc herniation, the second was caused by acute disc prolapse in a pre-existing asymptomatic lumbar canal stenosis, and the third one precipitated in a progressive degenerative severe lumbar spinal stenosis. Two cases (case reports 1 and 3) underwent minimal invasive decompression while the other case (case report 2) underwent instrumentation+ decompression + fusion. Case 1 and 2 with a short duration of symptoms showed good neurological recovery, whileereas Case 3 with longer duration of complaints did not improve.
Patients presenting with painless bilateral foot drop without cauda equine syndrome should be evaluated for spinal causes besides central nervous systemCNS, peripheral nerve, metabolic and autoimmune causes. Any finding in support of lumbar degenerative disease as the cause after excluding other causes should prompt for surgical decompression of the spine as an early intervention might help patient recover back to a normal and active lifestyle.
Background:
Intraoperative anteropulsion of a transforaminal lumbar interbody fusion (TLIF) cage is infrequent but may have disastrous complications. Here, we present an 80-year-old female whose ...L5-S1 TLIF cage extruded anteriorly and later migrated into the pouch of Douglas (i.e. an anterior peritoneal reflection between the uterus and the rectum) posing potential significant risks/complications, particularly of a major vessel injury. Notably, this 80-year-old patient with degenerative lumbosacral scoliosis should have only undergone a lumbar decompression alone.
Case Description:
An 80-year-old female underwent a two-level L4-L5 and L5-S1 TLIF to address lumbosacral canal stenosis with degenerative scoliosis. During the L5-S1 TLIF, intraoperative fluoroscopy showed the anterior displacement of the cage ventral to the sacrum. As she remained hemodynamically stable, the cage was left in place. The postoperative CT scan confirmed that the cage was located in the retroperitoneum but did not jeopardize the major vascular structures. Three months later, however, the cage migrated inferiorly into the pouch of Douglas. Although asymptomatic, general surgery and gynecology advised laparoscopic removal of the cage to avoid the potential for a major vessel/bowel perforation. However, the patient refused further surgery, and 3 years later remained asymptomatic.
Conclusion:
Anterior cage migration following TLIF has been rarely reported. In this case, an L5-S1 TLIF cage extruded anteriorly in an 80-year-old severely osteoporotic female and migrated 3 months later into the pouch of Douglas, posing the risk of a major vessel/bowel injury. Although surgical removal was recommended, the patient refused further surgery but remained asymptomatic 3 years later. Notably, the authors, in retrospect, recognized that choosing to perform a 2-level TLIF in an 80-year-old female reflected poor judgment.
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