Synthesis, growth, optical, mechanical, thermal, dielectric and third order nonlinear optical properties of cyclohexylamine derivative single crystals

The materials of Cyclohexylamine with 1,5-naphthalenedisulfonic acid and 3,5-dinitrosalicylic acid were used to synthesize the bis(cyclohexylammonium)-1,5-naphthalenedisulfonate (CA15NS) and bis(cyclohexylammonium)-3,5-dinitrosalicylate (CA35NS) compounds and single crystals of these compounds were grown successfully by low temperature solution growth technique. Crystal systems of the samples were identified for both the samples of CA15NS and CA35NS by the obtained unit cell parameters of the grown crystals which is determined by single crystal X-ray diffraction (SCXRD) analysis, the crystals of CA15NS and CA35NS are crystallized in monoclinic crystal structures. The powder X-ray diffraction (PXRD) analysis also was carried out for the title samples. The formations of the charge-transfer functional groups and the modes of vibrations of CA15NS and CA35NS have been confirmed by FT-IR and FT-Raman spectral analyses. The UV-Vis-NIR spectrum was carried out to find the optical behavior of the prepared crystals. The crystal of CA15NS has 232 nm and CA35NS has 207 nm as cut-off wavelength. The influences of mechanical and dielectric behavior in the crystals of CA15NS and CA35NS were investigated by means of Vickers microhardness test and dielectric study, respectively. By the thermo gravimetric analyses, the stability of the materials have been estimated for the title samples. Third order nonlinear optical study has also been studied by Z-scan technique.

Development of cable fed flash X-ray (FXR) system

Flash X-ray sources driven by pulsed power find applications in industrial radiography, and a portable X-ray source is ideal where the radiography needs to be taken at the test site. A compact and portable flash X-ray (FXR) system based on a Marx generator has been developed with the high voltage fed to the FXR tube via a cable feed-through arrangement. Hard bremsstrahlung X-rays of few tens of nanosecond duration are generated by impinging intense electron beams on an anode target of high Z material. An industrial X-ray source is developed with source size as low as 1 mm. The system can be operated from 150 kV to 450 kV peak voltages and a dose of 10 mR has been measured at 1 m distance from the source window. The modeling of the FXR source has been carried out using particle-in-cell and Monte Carlo simulations for the electron beam dynamics and X-ray generation, respectively. The angular dose profile of X-ray has been measured and compared with the simulation.

Development of a novel voltage divider for measurement of sub-nanosecond rise time high voltage pulses

This paper is about the development of a copper sulphate based aqueous-electrolytic voltage divider for the measurement of high voltage pulses, 100 kV, with pulse widths of 1-2 ns and rise time <1 ns. Novel features are incorporated in the design of the divider, to meet the performance requirements for the application. Analytical calculations to justify design are described. Structural simulation of the divider is carried out using field wave simulation software to verify the effectiveness. A calibration procedure has been developed to calibrate the divider. Results obtained during calibration are subjected to statistical analysis to determine the confidence of measurement. Details of design, analysis, and simulation are described in this paper.

The Outcomes of Selective Nerve Root Block for Disc Induced Lumbar Radiculopathy

Introduction : Use of Selective Nerve Root Block (SNRB) in lumbar region to relieve radicular pain along the course of a particular nerve is being practiced in the recent past. We observed and tabulated therapeutic outcomes of this procedure in management of radiculopathy induced by a prolapsed disc affecting a particular lumbar nerve root.

Methods : 40 patients with various grades of disc prolapse affecting a particular lumbar nerve root presenting with chronic radicular pain were identified irrespective of age and sex. All were injected with a combination of 40 mg of Methylprednisolone based suspension with local anaesthetic over the affected nerve root and results were analyzed.

Results : Those graded mild had 4.3 months relief and those graded moderate had 2.5 months relief. Those with severe disc prolapse had no relief except for the immediate postprocedural relief. Only 20% patients had relief up to 6 months.

Conclusion : Effect of SNRB is typically short acting in majority of patients and recurrence is expected. It creates a window period with reduced pain but of varied intervals depending on the pathology. It did not alter the prognosis in those with severe disease where surgery is well indicated.

Level of Evidence – Level 4

Influence of calcination temperature on the luminescent properties of Eu³⁺ doped CaAl₄O₇ phosphor prepared by Pechini method

Motivated by the need for new phosphor for white light emitting diode (WLED) applications, CaAl₄O₇ phosphors activated by Eu(3+) rare earth ion was synthesized using the Pechini method at different calcination temperatures. The crystal structure and luminescent properties were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), UV-Vis diffuse reflectance spectroscopy (DRS), and photoluminescence spectroscopy (PL). The XRD and SEM patterns confirm the presence of a single grossite monoclinic phase (311) and the particles exhibit good crystallinity and the particle size varies with calcination temperature. Absorption peak of FT-IR shows the decomposition of citrate ethylene glycol complex and the formation of CaAl₄O₇:Eu(3+) phosphor. Diffuse reflectance spectra indicate an absorption in the UV-region. The photoluminescence excitation spectrum exhibited a broad band covering from 340 to 420 nm with a sharp band at 395 nm. CaAl₄O₇:Eu(3+) phosphor excited by near UV (395 nm) light showed a strong red emission at 611 nm. The emission band is due to f-f transitions within the 4f(6) configuration of Eu(3+) ions, respectively. The photoluminescence properties were found to be strongly dependent on the calcination temperature and the PL properties are superior for sample calcined at 950 °C.

Bulk crystal growth and nonlinear optical characterization of a stilbazolium derivative crystal: 4-[2-(3,4-dimethoxyphenyl)ethenyl]-l methylpyridinium tetraphenylborate (DSTPB) for NLO device fabrication

The search for organic crystals with highly efficient nonlinear optical (NLO) properties with a high surface laser damage threshold (LDT) has become more of a demand in the frontier areas of optical switching and communications applications.

Growth and characterization of an organic single crystal: 2-[2-(4-diethylamino-phenyl)-vinyl]-1-methyl-pyridinium iodide

Optically transparent crystal of the organic salt DEASI (2-[2-(4-Diethylamino-phenyl)-vinyl]-1-methyl-pyridinium iodide) has been synthesized by using knoevenagel condensation reaction method. The synthesized material has been purified by successfully recrystallization process. Single crystals of DEASI have been grown by slow evaporation technique at room temperature. The solubility of the title material has been determined at different temperature in acetonitrile/methanol mixture. The cell parameters and crystallinity of the title crystal were determined by single crystal XRD. The powder diffraction was carried out to study the reflection plane of the grown crystal and diffraction peaks were indexed. The presence of different functional groups in the crystal was confirmed by Fourier transform infrared (FTIR) analysis. (1)H NMR spectrum was recorded to confirm the presence of hydrogen nuclei in the synthesized material. The optical property of the title crystal was studied by UV-Vis-NIR spectroscopic analysis. The melting point and thermal property of DEASI were studied using TGA/DSC technique. The Vicker's hardness (Hv) was carried out to know the category. The dielectric constant and dielectric loss of the compound decreases with an increase in frequencies. Chemical etching studies showed that the DEASI grows in the two dimensional growth mechanisms. The Kurtz-Perry powder second harmonic generation (SHG) test has done for title crystal.

Synthesis, growth, crystal structure, spectral, thermal, mechanical and optical studies of stilbazolium derivative single crystal: 2-[2-(4-Diethylamino-phenyl)-vinyl]-1-methyl-pyridinium naphthalene-2-sulfonate (DESNS)

Single crystals of organic optical material, 2-[2-(4-Diethylamino-phenyl)-vinyl]-1-methyl-pyridinium naphthalene-2-sulfonate (DESNS) (15×10×9 mm(3)) were grown by a slow evaporation technique at room temperature using methanol-acetonitrile (1:1) mixed solvent. The molecular structure of the grown crystal was confirmed by single crystal X-ray diffraction studies, and it belongs to orthorhombic system with space group Pbca and the unit cell dimentions are a=11.5148(3) Å, b=15.4352(4) Å, c=27.2187(7) Å, Z=8. The crystallinity of the title crystals was confirmed from the powder XRD pattern. The presence of functional groups of the title crystal was confirmed from the FTIR spectral studies. The transparent range and cut off wavelength of the grown crystal was studied by the UV-Vis-NIR spectroscopic analysis. The mechanical properties and thermal behavior of the grown crystals were studied from Vickers microhardness test and TG/DTA.

Effect of additives on the large-size growth of 4-N,N-dimethylamino-4-N-methyl stilbazolium naphthalene-2-sulfonate (DSNS) single crystal: an efficient stilbazolium derivative NLO crystal with potential terahertz wave properties

We explored the growth of the highly nonlinear optical stilbazolium salt 4-N,N-dimethylamino-4-N-methyl stilbazolium naphthalene-2-sulfonate (DSNS) by a slow evaporation method.

Investigation of synthesis, crystal structure and third-order NLO properties of a new stilbazolium derivative crystal: a promising material for nonlinear optical devices

A new organic stilbazolium derivative crystal 2-[2-(3-hydroxy-4-methoxy-phenyl)-vinyl]-1-methyl-pyridinium naphthalene-2-sulfonate dehydrate (C₂₅H₂₃NO₅S·2H₂O) (VSNS) was synthesized successfully.

2-[(E)-2-(4-Methoxyphenyl)ethenyl]-1-methylpyridinium iodide

In the title mol­ecular salt, C₁₆H₁₀NO⁺·I⁻, the dihedral angle between the pyridinium and benzene rings is 6.61 (8)°. In the crystal, the cation is linked to the anion by a C—H⋯I inter­action arising from the activated aromatic C atom adjacent to the N⁺ cation.

Comparative study of percutaneous dilatational tracheostomy and conventional tracheostomy in the intensive care unit

OBJECTIVE

Tracheostomy is a one of the earliest described surgical procedure dating back to 2000 B.C. Percutaneous tracheostomy is becoming increasingly popular as an alternative method for conventional tracheostomy in the intensive care unit. In this study we compare the results of the use of these 2 techniques in 32 patients who underwent elective tracheostomy in the intensive care unit.

STUDY DESIGN

Prospective randomized comparative study.

SETTING

Tertiary care hospital.

PATIENTS

Adult intubated patients selected randomly in the intensive care unit with normal cervical soft tissue, laryngeal framework, palpable cricoid cartilage and normal coagulation parameters.

RESULTS

17 patients underwent conventional tracheostomy and 15 patients underwent percutaneous dilatational tracheostomy. Demographic data and duration of intubation comparable between two groups. The mean operative time, blood loss and complications were lower in percutaneous than in conventional tracheostomy.

CONCLUSIONS

PDT is quicker to perform and has lower blood loss and complication rates compared to conventional tracheostomy. However percutaneous tracheostomy is not indicated in emergencies and in children. The cost of the percutaneous kit and use of bronchoscopy adds to the cost. It is a good alternative to conventional tracheostomy in properly selected patients.

High voltage pulse shaping of e-beam diode using perveance variation

This paper presents a new high voltage pulse shaping methodology for pulsed power applications. The aim is to generate high voltage square pulse across anode cathode gap of e-beam diodes. The non-linear time varying perveance characteristics of e-beam diodes are used for shaping of output voltage pulse across it, generated directly from Marx generator. Analytically, it has been shown in the paper that under certain conditions, if achieved, Marx generator feeding an e-beam diode can produce a square-like pulse at the output, without any extra pulse shaping arrangements. Experimental results to support the analysis are also presented in the paper.

Prepulse minimization in KALI-5000

A pulse power system (1 MV, 50 kA, and 100 ns) based on Marx generator and Blumlein pulse forming line has been built for generating high power microwaves. The Blumlein configuration poses a prepulse problem and hence the diode gap had to be increased to match the diode impedance to the Blumlein impedance during the main pulse. A simple method to eliminate prepulse voltage using a vacuum sparkgap and a resistor is given. Another fundamental approach of increasing the inductance of Marx generator to minimize the prepulse voltage is also presented. Experimental results for both of these configurations are given.

Intestinal myiasis caused by Muscina stabulans

Intestinal maggots were isolated from a patient, who had reported to the Department of General Medicine of Sri Manakula Vinayagar Medical College, Puducherry, in southern India with complaints of abdominal distress, bloating of abdomen and intestinal hurry following a meal. He was diagnosed as a case of intestinal myiasis. Maggots obtained from his stool were identified to be Muscina stabulans based on characteristic patterns of posterior spiracles. He was treated with purgatives and albendazole. This intestinal myiasis case caused by M. stabulans is reported here because of its rare occurrence and the need to establish a correct diagnosis.

A design approach for systems based on magnetic pulse compression

A design approach giving the optimum number of stages in a magnetic pulse compression circuit and gain per stage is given. The limitation on the maximum gain per stage is discussed. The total system volume minimization is done by considering the energy storage capacitor volume and magnetic core volume at each stage. At the end of this paper, the design of a magnetic pulse compression based linear induction accelerator of 200 kV, 5 kA, and 100 ns with a repetition rate of 100 Hz is discussed with its experimental results.

Characterization and analysis of a pulse power system based on Marx generator and Blumlein

A pulse power system (1 MV, 50 kA, and 100 ns) based on Marx generator and Blumlein pulse forming line has been studied for characterization of a general system. Total erected Marx inductance and series resistance are calculated from modular testing of Marx generator and testing of Marx generator with Blumlein. The complete pulse power system has been tested with the termination of a liquid resistor load for finding the Blumlein characteristic impedance. Equivalent electrical circuits during the charging and discharging of the Blumlein are constructed from the characterized parameters of the system. These equivalent circuits can be used in the analysis of prepulse voltage and droop in the flat top of the main pulse in the pulse power systems based on Marx generator and Blumlein.

Inflammatory pseudotumours of the paranasal sinuses

Inflammatory pseudotumors are clinocopathologically distinctive but biologically controversial entities. They have been described in the lungs, abdomen, retroperitoneum and extremities, but rarely affect the head and neck region. This report is of 2 cases of pseudo tumor of the paranasal sinuses with varied clinical presentation and successful outcome following treatment.

Disseminated Intravascular Coagulation syndrome - ENT surgeon's perspective

ENT surgeon is seldom confronted with a systemic disease severe enough to progress to Disseminated Intravascular Coagulation syndrome (DIC), where he has to undertake a definitive surgical procedure for malignancy or perform an emergency tracheostomy. This calls for a judicious calculation of the pros and cons with an element of risk that needs to be accepted. We report two such patients who have been treated in such a scenario where the outcome varied depending on the severity and time of onset of the underlying coagulation disorder.

Laparoscopic Repair of Ureterovaginal Fistula: Successful Outcome by Laparoscopic Ureteral Reimplantation

We describe our technique of laparoscopic repair of ureterovaginal fistula in a 34-year-old woman who developed a vaginal leak of urine 15 days after laparoscopic hysterectomy. Laparoscopy and extravesical ureteral reimplantation with a stent was carried out. Cystoscopy and stent removal was done after 6 weeks. The patient was dry. To our knowledge, laparoscopy for the repair of ureterovaginal fistula has not been described. This distressing condition can be corrected laparoscopically with obvious benefit to the patient.

Otological manifestations in head injury and their management - a case report

32 year old male presented with right facial palsy following head injury. Clinical evaluation showed hemotympanum on right with moderately severe conductive hearing loss, grade III LMN facial palsy and BPPV. HRCT of temporal bone demonstrated fracture base of skull involving the roof of mastoid with no evidence of bony injury to fallopian canal. Conservative management of head trauma resulted in satisfactory outcome except for conductive hearing loss and faciel palsy. Facial palsy was managed conservatively [physiotherapy and oral steroids] with full recovery of function after 4 weeks. Conductive hearing loss was managed by combined approach tympanaplasty. Preoperutively incudostapedial joint dislocation and fracture anterior crus of stapes were noted. Type II tympanoplasty with horizontal incus repositioning was carried out.PTA after 6 weeks showed 15-20 dB air-bone gap compared to 50-55dB air-bone gap preoperatively. BPPV recovered spontaneously. This case is reported to highlight:Importance of imaging of temporal bone.Spontaneous recovery of facial nerve function in neuropraxtc injury.Timely and appropriate surgical intervention of ossicular damage following head injury resulting in satisfatctory outcome.

Hypericin photosensitization in aqueous model systems

Photosensitization of lysozyme, liposomes, ghosts and intact red blood cells (RBC) was investigated for aqueous hypericin. The effects of azide ion, 1,4-diazabicyclo(2.2.2)octane, and superoxide dismutase on photosensitized inactivation of lysozyme in 0.5% Triton X-100 indicate that singlet oxygen is the major inactivating intermediate with a contribution from superoxide. The singlet oxygen quantum yield (phi delta) scaled to methylene blue is 0.49 +/- 0.06 at monochromatic wavelengths from 514 to 600 nm. Relative values of phi delta based on lysozyme inactivation for different vehicles are: 0.5% Triton X-100 (1.13), human serum albumin (0.65), Cremophor-EL (0.76), Cremophor-RH40 (0.98), egg phosphatidylcholine (EPC) liposomes (0.04), hydrogenated soy phosphatidylcholine (HSPC) liposomes (< 0.01). Hypericin photosensitized lipid peroxidation of EPC liposomes and RBC ghosts. Extensive cross-linking of ghost membrane proteins occurred during the initial stages of lipid peroxidation. Prompt photohemolysis was used as the assay of RBC membrane damage. The photohemolysis curves are modeled with multihit target theory based on the "hit number" (n) and the target cross section (v). The values of v and the conventional "1/t50" parameter are equivalent determinants of the photohemolysis rate. The photohemolysis curves are in good agreement with n = 15 for incubation in phosphate-buffered saline at different hypericin concentrations and with additives. The measurements for other vehicles led to n = 19 for Cremophor-EL and n = 3 for EPC and HSPC liposomes, indicating that the kinetics of photohemolysis depend on the conditions of incubation.