Linear and nonlinear optical characterization of tellurium dioxide (α-TeO2) for generation of terahertz radiation using time-domain spectroscopy.

This paper reports the linear and nonlinear optical characterization of α-T e O 2 crystal in the optical and terahertz domains for efficient terahertz (THz) generation using a difference frequency mixing technique. We have ascertained the optical properties such as refractive index, absorption coefficients, real and imaginary dielectric constants, and coherence length l c=280m m at 1.77 THz range using an indigenously developed THz spectrometer. The value of refractive index was ascertained from temporal and spectral THz profiles of the crystal and employed for calculating the Type I phase-matching angle, i.e., Î¸=21.15∘ for the generation of tunable radiation between the 0.1 and 1.9 THz range. The figure of merits in the optical and THz domains lie between the 0.02-0.015 range. The effective bandwidth of the crystal lies between the 0.1 and 3.0 THz range.

Effect of the annealing temperature on structural, morphological, and nonlinear optical properties of TeO2 thin films used for efficient THz generation.

This paper reports the effect of annealing on T e O 2 films deposited using the thermal evaporation technique. T e O 2 films of 120 nm thickness were grown on a glass substrate at room temperature (RT) and annealed at 400°C and 450°C. The structure of the film and the influence of the annealing temperature on the crystalline phase change were examined using the X-ray diffraction method. Optical properties such as transmittance, absorbance, complex refractive index, and energy bandgap were determined between ultraviolet-visible to terahertz (THz) range. These films have a direct allowed transition with the optical energy bandgap of 3.66, 3.64, and 3.54 eV at as-deposited temperatures (RTs) of 400°C and 450°C. The effect of the annealing temperature on the morphology and surface roughness of the films was investigated using atomic force microscopy. The nonlinear optical parameters, which are the refractive index and absorption coefficients, were calculated using THz time domain spectroscopy. The microstructure variation of the T e O 2 films in terms of surface orientation plays an important role in understanding the change in the nonlinear optical properties of the films. Finally, these films were subjected to 800 nm wavelength of 50 fs pulse duration obtained from a Ti:sapphire amplifier at a 1 kHz repetition rate for efficient THz generation. The power of incidence of the laser beam was tuned at a range between 75 and 105 mW; the highest power of the generated THz signal was of the order of 210 nW for 450°C annealed film with respect to the incident power of 105 mW. The conversion efficiency was found to be ∼0.22×10-5 %, which is 2.025 times more than the film annealed at 400°C.

Efficient second-harmonic and terahertz generation from single BiB3O6crystal using nanosecond and femtosecond lasers.

The paper reports the efficient UV and terahertz generation from a 1.29 mm thick and Type I, θ=28.9∘ cut BiB3O6 (bismuth triborate, BIBO) crystal using femtosecond and nanoseconds laser pulses. We have employed 800 nm wavelength pulses of 50 and 140 fs obtained from a Ti:sapphire laser amplifier and oscillators at 1 kHz and 80 MHz repetition rates, respectively. The conversion efficiency of second-harmonic generation (SHG) was ∼50% while that obtained for terahertz (THz) generations was of the order of 1.85×10-5%. In addition, LDS-698 dye laser radiation tunable between 650-700 nm was also used as a source for SHG between the 325-350 nm range. The dye laser was pumped by SHG (532 nm) radiation from an electro-optically Q-switched Nd:YAG laser having a pulse repetition rate of 10 Hz and a pulse width of 10 ns. A conversion efficiency of 4.01% was obtained for generation of UV at 343.5 nm. Finally, we have measured the transmission, refractive index, absorbance, and conductivity properties of BIBO crystal in the THz domain. We also ascertained the coherence length, relative permittivity and reflectivity of the crystal.

Linear and nonlinear temperature-dependent transmission/absorption characteristics of cadmium telluride crystal for terahertz generation.

This paper reports on the temperature-dependent investigation of linear and nonlinear transmission/absorption characteristics of CdTe crystal in the 300-408 K range using 780-970 nm tunable wavelengths of 140 fs pulses obtained from a Ti:Sapphire laser at 80 MHz repetition rate. The same pulses were also used for terahertz generation. The linear transmission/absorption properties were measured using a specially improvised temperature-tuned spectrophotometer in the 500-1500 nm wavelength range. The linear absorption of 750 nm wavelength gradually increases with respect to a rise in the temperature, and transmission becomes zero at 408 K. Nonlinear absorption induced by femtosecond pulses shows a sudden drop of 18% in transmission above the 800 nm range, due to electron-phonon interaction, which affects the strength of the terahertz signal. It is also responsible for change in the temperature along with the linear shift in the refractive index of the crystal.

Influence of weather patterns and air quality on ecological population dynamics of ectoparasites in goats.

Ectoparasitism has a damaging impact on the economy of goat production in India, but the factors influencing its distribution and dynamics are less explored. The present study was designed to investigate the influence of environmental factors like weather and air quality parameters on the occurrence of different types of ectoparasites in goats of two agro-climatic regions of India, viz. the Upper Gangetic Plain (UGP) and the Western Himalayas (WH). The prevalence survey for ectoparasitism among goats was conducted during the four distinct climatic seasons (winter, summer, monsoon, autumn) in both regions. The season-wise data of weather parameters (maximum and minimum temperature, relative humidity in morning and evening, sunrise and sunset time, mean daily temperature and relative humidity, daily variation in temperature and relative humidity, and day length) and air quality parameters (air quality index (AQI), particulate matter 2.5 µm (PM2.5), particulate matter 10 µm (PM10)) of both regions were analyzed in relation with the ectoparasitic prevalence pattern of corresponding regions. The results depict a noticeable correlation between the studied parameters and seasonal variation in the occurrence of each type of ectoparasites. This outcome on the interaction of studied parameters and ectoparasitism is intriguing and it opens a huge scope for future studies on the biometeorological aspects of host-parasite ecological interplay and evolutionary biology. The better understanding of climatological aspects of ectoparasite occurrences helps goat farmers in formulating appropriate timely intervention strategies for the economic control of ectoparasites, which in turn tackles ectoparasiticidal drug resistance and reduces threat of vector-borne diseases.

Temperature-dependent terahertz spectroscopy and refractive index measurements of aqua-soluble and plastic explosives.

The paper reports the temperature-dependent time domain terahertz spectroscopy of premium aqua-soluble and plastic explosives such as NH4NO3, TNT, and RDX between 0.1 and 2.2 THz. Tunable terahertz radiation was generated using ZnTe crystal as a source, and a photoconductive antenna was used as a detector. The temperature-dependent study was carried out between 30°C and 200°C in a specially designed oven. The signature peaks of RDX and TNT present at 0.82 and 1.60 THz, respectively, show a strong redshift, whereas the NH4NO3 molecule shows a comparatively small shift. The high-temperature-based redshift phenomenon is just the opposite of the blueshift recorded at low temperatures. In addition, the temperature-dependent absorption coefficient data of these molecules support the change in the concentration of the NO2 molecule. We have also ascertained the temperature-dependent refractive indices of these molecules between 0.1 and 2.0 THz, which confirms the effect of temperature on the refractive indices. Finally, the signature peak of RDX with respect to the reduction in the weight concentration of RDX in the Teflon matrix was studied at 0.82 THz.

Study of thermal decomposition mechanisms and absorption cross section of nitro-rich phenyl- and bis-series 1,2,3-triazoles.

This paper reports the investigation of thermal decomposition mechanisms and evaluation of thermally released NO2 from two newly synthesized high-energy materials named 1-(4-nitrophenyl)-1H-1,2,3-triazole (S8) and 2,6-bis ((4-(nitromethyl)-1H-1,2,3-triazol-1-yl)methyl) pyridine (S9) using time-resolved pulsed photoacoustic (PA) pyrolysis technique. The PA spectra were recorded between the 30°C and 350°C range and by varying the pressure of compounds vapor using 532 nm wavelength of pulse duration 7 ns at 10 Hz repetition rate obtained from Q-switched Nd:YAG laser pulses. The PA results were cross verified with thermogravimetric-differential thermal analysis data. The quality factor "&=&Q"&=& of the PA cavity was measured to test the thermal stability of the compound. In addition, we have ascertained the molecular density, absorption cross sections of high-energy materials vapor in terms of NO2. The corresponding values are of the order of 0.1-1.2×10(20) cm-3 and 0.5-6 kilobarn, respectively. These results once again confirm the close agreement between the radiative and nonradiative transitions data and established the role of NO2 during the thermal decomposition process.

Serum ferritin predicts early mortality in patients with decompensated cirrhosis.

BACKGROUND & AIMS: Serum ferritin is a known marker of hepatic necro-inflammation and has been studied to predict 1 year mortality and post-transplant survival in decompensated cirrhotics. However, there are no studies evaluating ferritin as a predictor of early mortality. We investigated whether serum ferritin levels could predict 15 day and 30 day mortality in patients with decompensated cirrhosis. METHODS: 318 patients with decompensated cirrhosis were included. RESULTS: Patients of decompensated cirrhosis [257 males, mean age of 51 [±13]years, were followed for a median of 31 days. Serum ferritin levels were significantly different between survivors and non-survivors [p<0.001] and showed significant correlation with MELD score [p<0.001], CTP score [p<0.001], leucocyte counts [TLC] [p<0.001], serum sodium [p<0.001], ACLF grades [p=0.005], spontaneous bacterial peritonitis [SBP] [p=0.02], hepatic encephalopathy [HE] [p<0.001] and hepatorenal syndrome [HRS] [p=0.012]. Serum ferritin, etiology, MELD, HE, CTP score, sodium, TLC, and ACLF grades were significant predictors of mortality on univariate analysis. Ferritin [p=0.04, HR 1.66 95% CI (1.02-2.73)] was a significant predictor of early mortality on multivariate analysis along with HE [p=0.006, HR 3.47 95% CI (2.13-8.41)] (Model 1), TLC [p=0.02, HR 1.81 95% CI (1.06-3.07)] (Model 2), ACLF grades [p=0.018, HR 2.013,95% CI (1.126-3.60)], and CTP score [p<0.0001, HR 1.36 95% CI (1.17-1.59)] (Model 3). CONCLUSION: Serum ferritin levels correlate with severity of hepatic decompensation and are associated with early liver related death independent of the MELD score in hospitalized patients with decompensated cirrhosis. This could also have a potential therapeutic implication.

Molecular analyses of novel ASAH1 mutations causing Farber lipogranulomatosis: analyses of exonic splicing enhancer inactivating mutation.

Farber lipogranulomatosis is a rare autosomal recessive lysosomal storage disorder caused by mutations in the ASAH1 gene. In the largest ever study, we identified and characterized ASAH1 mutations from 11 independent Farber disease (FD) families. A total of 13 different mutations were identified including 1 splice, 1 polypyrimidine tract (PPT) deletion and 11 missense mutations. Eleven mutations were exclusive to the Indian population. The IVS6+4A>G splice and IVS5-16delTTTTC PPT deletion mutations resulted in skipping of exon 6 precluding thereby the region responsible for cleavage of enzyme precursor. A missense mutation (p.V198A) resulted in skipping of exon 8 due to inactivation of an exonic splicing enhancer (ESE) element. This is the first report of mutations affecting PPT and ESE in the ASAH1 gene resulting in FD.

Terahertz-based optoelectronic properties of ZnS quantum dot-polymer composites: For device applications.

Terahertz (THz) technology integration with nanomaterials is receiving excellent attention for next-generation applications, including enhanced imaging and communication. The excellent optical properties in THz domain can lead to preparation of low-cost CMOS camera which can convert THz radiation into optical signal in very efficient manner. In the present study, we have studied the properties of Zinc Sulfide quantum dots (ZnS QDs) embedded with Polyvinyl Alcohol (PVA) composites films using THz Signal at room temperature. The optical characterizations such as refractive index, absorption coefficients and dielectric constants of these samples were measured in the 0.1-2.0 THz range. Additionally, optical impedance, surface roughness, and reflection coefficient in TE and TM mode between 0.1 and 2.0 THz range were determined for these samples based on surface roughness-based reflection and scattering properties. The surface roughness factor was used to measure the optical impedance of the ZnS QDs based polymer films. The measured values of the absorption coefficient at 266 nm are compared with THz radiation, and the refractive indices of these samples range from 1.75 to 2.0. Finally, these samples were subjected to UV light excitation (λexe = 266 nm) of 0.15 ns duration and 400 nm for the fluorescence and corresponding life time measurements. We observed two numbers of fluorescence lines in nanosecond based excited domain whereas 400 nm excitation-based fluorescence life time lies between 13.8-11.39 ns range along with shift in fluorescence lines between 538.7 to 560.7 nm, respectively.

Necrotizing fasciitis after spinal anesthesia.

Regional anesthesia is the preferred technique for Cesarean delivery. Strict aseptic precautions should be taken; otherwise, infectious complications including abscess formation, meningitis and necrotizing fasciitis may result. We report a case of a 26-year-old post-partum female who presented with necrosis of the skin of back following spinal anesthesia, which was administered for Cesarean delivery 5 days prior at a private nursing home. On presentation, she was drowsy, appeared dehydrated and febrile. Examination of her back revealed necrosis of skin extending from just below the scapula to the gluteal region. Debridement of skin over the back was performed, and intravenous antibiotics started. After three debridements following which skin grafting was performed, she made complete recovery. Infectious complications following regional anesthesia are rare, and most of the literature focuses on colonization of epidural catheters or epidural abscess. There is no report of necrotizing fasciitis following spinal anesthesia so far. Sources of infection that are suspected in our case include: local anesthetic solution used for subcutaneous infiltration, nonadherence to aseptic precautions, skin flora of patient, endogenous source and nasopharyngeal flora of anesthesiologist. We considered each possibility, and the most likely cause in our case appears to be infection from an already-used vial of a local anesthetic agent. Local anesthetics have bacteriostatic properties, but infection may still be transmitted through contaminated solutions. The present case highlights the importance of maintaining strict aseptic precautions, avoiding reusing multidose vials and early recognition of this complication as timely intervention can be lifesaving.

Low level detection of acetone vapor by improvised design of high "Q" tunable frequency Helmholtz photoacoustic cell using UV, mid- IR and THz sources.

The paper reports the designing and fabrication aspects of a high "Q = 492.3" Helmholtz photoacoustic (PA) cell employed for the trace level detection of acetone, a biomarker by using 266 nm- UV, Mid-IR (5.4-10.6 micron) and 0.11 Terahertz (THz) sources. The designed Helmholtz PA cell is made of Aluminum and possesses a natural frequency tunable between 1.4 to 4.4 kHz range using a movable piston arrangement of the microphone sensor. Numerous types of disorders, including diabetes, asthma, lung cancer, etc., can be diagnosed using the acetone concentration obtained through breath analysis. The comparative study is related to the response of different types of excitation mechanisms contributed by electronics, vibrational and rotational modes of acetone. The low-level detection (LoD) limit for acetone is of the order of 5.06 & 7.92 ppbV, and 15.3 pptV, respectively, in UV, Mid-IR, and THz region. This study contributes to the development of a highly sensitive, non-invasive acetone detection and quantification modality.

A founder ectodysplasin A receptor (EDAR) mutation results in a high frequency of the autosomal recessive form of hypohidrotic ectodermal dysplasia in India.

BACKGROUND: Hypohidrotic/anhidrotic ectodermal dysplasia (HED) is a rare Mendelian disorder affecting ectodermal tissues. The disease is primarily caused by inactivation of any one of three genes, namely ectodysplasin A1 (EDA-A1), which encodes a ligand belonging to the tumour necrosis factor (TNF) superfamily; ectodysplasin A receptor (EDAR), encoding the EDA-A1 receptor and ectodysplasin A receptor-associated death domain (EDARADD), encoding an adaptor protein. X-linked recessive (EDA-A1), the predominant form of HED, as well as autosomal recessive and dominant (EDAR and EDARADD) inheritance patterns have been identified in affected families. OBJECTIVES: To determine the common genes causing HED in India. METHODS: We performed mutation analysis on 26 HED families from India (including 30 patients). In addition, we carried out sequence and structural analysis of missense/nonsense and insertion/deletion mutations. RESULTS: Among the 26 families analysed, disease-causing EDAR mutations were identified in 12 (46%) while EDA-A1 mutations were detected in 11 (42%). Four novel mutations in EDAR and five in EDA-A1 were identified. More importantly, a possible founder EDAR mutation, namely c.1144G>A, was identified in five independent families, thus accounting for about one-fifth of affected families in whom mutation was detected. A majority of EDA-A1 mutations localized to the TNF-like domain while the location of EDAR mutations was more widespread. CONCLUSIONS: This is the first report of a founder EDAR mutation and of a significantly high frequency of autosomal recessive HED.

Study of photo induced charge transfer mechanism of PEDOT with nitro groups of RDX, HMX and TNT explosives using anti-stokes and stokes Raman lines ratios.

The paper reports the charge transfer mechanism between poly (3,4-ethylenedioxythiophene) (PEDOT) and high energy materials such as RDX, HMX and TNT, respectively in terms of ratios of anti-stokes (AS) and stokes(S) Raman lines of NO2 bands. Generally it works as an effective sensing medium for the detection of explosives when mixed in an equal proportion and are subjected to 532 nm wavelength without any chemical treatment [1]. The pristine PEDOT is less sensitive to 532 nm wavelength (2.33 eV) but influences the Raman S and AS lines of explosives in the mixture. The study also reveals that a small quantity (one milligram) of PEDOT is sufficient to initiate the positive charge transfer mechanism between its oxidized state to the lone pairs of electrons on the oxygen atoms of the nitro group of the explosive molecules. Consequently, the intensity of the Raman spectra of RDX, HMX and TNT is dropped by an order of 22.5, 11.45 and 17.2 times, respectively along with the shift of the NO2 vibrational modes. It is also attributed to Photon-electron-phonon interaction. Finally, we have estimated the reduced mass of the functional group to ascertain the force constant and the intensity ratios of AS /S lines to confirm the charge transfer mechanism. The effect of charge transfer mechanism is also reflected in drastic change in transmission /absorption characteristics of FTIR spectra of same PEDOT and explosive mixtures.

Study of charge transfer mechanism of PEDOT polymer for detection of solid TEX and CL-20 explosives using pulsed photoacoustic technique.

We report the use of PEDOT polymer (poly (2, 3-dihydrothieno [3,4-b] dioxane-5,7-diyl) as a sensing medium for the detection of solid secondary explosives like TEX and CL-20 in solid form using pulsed photoacoustic (PA) technique under visible 532 nm wavelength. The PEDOT polymer (poly (2, 3-dihydrothieno [3,4-b] dioxane-5,7-diyl) plays the role of an optode or an effective sensing medium for the detection of explosives when mixed in equal proportion and subjected to 532 nm wavelength obtained from Q-switched Nd: YAG laser without any chemical treatment. The study reveals that one milligram of PEDOT is sufficient to initiate the charge transfer mechanism between the positive charge on the oxidized PEDOT and the lone pairs of electrons on the oxygen atoms of the nitro group of the explosives. The strength of the enhanced PA signal for TEX and CL-20 was of the order of 65.38 and 1.77 times, respectively. However, the same experiment was repeated with non-explosive samples such as NaNO2 and NaNO3, separately mixed with PEDOT. The obtained peaks of PA spectra were very weak, broaden and distorted in nature and occupies less than 3 kHz frequency rage and 3.5 times less than the PA signal of pure PEDOT. The estimated minimum detection limit of the solid explosives, CL-20 and TEX were of the order of 0.33 ng and 1.03 ng, respectively.

Expression of the matrix metalloproteinases MMP-2 and MMP-9 and their inhibitors TIMP-1 and TIMP-2 in systemic lupus erythematosus patients.

BACKGROUND: The study aimed to look at alterations in expression of matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) and their potential use as biomarkers in the pathogensis of SLE. METHODS: SLE patients (n = 41) and healthy controls (n = 50) were recruited. Quantitative RT-PCR/ELISA assays were performed for expression of MMP and TIMP mRNA in whole blood and PBMC; and corresponding serum protein levels. Intracellular levels of MMP-2 and MMP-9 proteins were analysed by flow cytometry. RESULTS: Based on SLEDAI scores patients were grouped into active (SLEDAI ≥ 10) and inactive cases (SLEDAI < 10). In active cases, MMP-2 expression significantly increased and TIMP-2 expression was decreased (p < 0.0001) both at serum secretion (p = 0.0003) and mRNA (p < 0.0001) levels as compared to inactive cases. MMP-9 and TIMP-1 showed significantly reduced serum secretion and mRNA expression (p < 0.0001) in active cases as compared to inactive cases. Intracellular concentration of MMP-9 was reported to be higher in neutrophils, while MMP-2 was mainly found in lymphocytes of SLE patients as compared to controls. MMP/TIMP ratio profile was altered as SLE disease progresses. INTERPRETATION & CONCLUSIONS: Findings suggest disturbed MMP and TIMP levels have a role in the pathogenesis of SLE.

Detection of endogenous malondialdehyde-deoxyguanosine adducts in human liver.

Endogenous DNA adducts may contribute to the etiology of human genetic disease and cancer. One potential source of endogenous DNA adducts is lipid peroxidation, which generates mutagenic carbonyl compounds such as malondialdehyde. A sensitive mass spectrometric method permitted detection and quantitation of the major malondialdehyde-DNA adduct, a pyrimidopurinone derived from deoxyguanosine. DNA from disease-free human liver was found to contain 5400 adducts per cell, a frequency comparable to that of adducts formed by exogenous carcinogens.

A comparative study of thermal stability of TNT, RDX, CL20 and ANTA explosives using UV 266 nm-time resolved photoacoustic pyrolysis technique.

The paper reports the potential use of UV based pulsed photoacoustic spectroscopy to study the thermal stability of some well-known premier explosives such as TNT, RDX, CL20, and ANTA between 30 and 350 °C range. The thermal PA spectra of samples were recorded using fourth harmonic wavelength i.e. 266 nm of pulse duration 7 ns and repetition rate 10 Hz obtained from Q-switched Nd: YAG laser system. Under the influence of UV radiation, the explosive molecules in vapor phase follow the photodissociation process and converted into their byproducts such as NO, NO2 and N2O etc. due to π* ← n transitions, which are responsible for the generation resultant PA signal at 266 nm wavelength. The results obtained from PA spectra as a function of temperature are cross verified with Thermo gravimetric-differential thermal analysis (TG-DTA) to ascertain the thermal stability of these samples. The comparative PA spectra of samples were analyzed and shown the behavior of acoustic modes with respect to incident laser energy, and data acquisition time. Finally, the thermal quality factor "Q" is measured to test the stability of reported explosives.

Temperature dependent time resolved mid-IR photoacoustic spectroscopy of a nerve gas simulant DMMP.

The paper reports the temperature dependent pulsed photoacoustic spectroscopy of Dimethyl methylphosphonate (DMMP) a nerve gas simulant between 50 and 180 °C temperature range. The time domain PA spectra are recorded using two mid-IR wavelengths i.e. 3374 nm, 3495 nm of pulse duration 1.5 ns at 1 kHz repetition rate obtained from optical parametric oscillator. Two anti-symmetric stretching vibrational modes of (CH3P) and (CH3O) groups of DMMP molecules have very strong vibrational peaks at 2861.2 cm-1 (3495 nm) and 2963.8 cm-1 (3374 nm), respectively. In addition, we have also recorded the PA spectra of acetone at the vibrational frequency 3115.2 cm-1 (3210 nm), which is the strong vibrational mode of CH band. The comparison of two PA spectra of DMMP and acetone recorded using similar PA cavity help us to understand the effect of other functional groups with respect to different excitation wavelengths. The presence of additional acoustic modes in the PA spectra of DMMP (3374 nm) above the boiling point confirms the slow process of thermal decomposition. Finally, the low level detection limit of DMMP in air is of the of the order of 0.91 ppbV.