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The lone granodiorite-hosted gold deposit at Dona sector of Jonnagiri, eastern Dharwar craton, India, contains typical shear-hosted and vein-hosted alteration zones. Pyrite is the dominant sulfide mineral in these alteration zones. Texturally three varieties of pyrites were identified in these alteration zones: (1) early pyrite-I is coarse to medium grained and subhedral shaped and contains near margin-parallel silicate inclusions, (2) main (ore)-stage pyrite-II overgrows early pyrite-I and also occurs as discrete grains invariably associated with visible gold, and (3) late-stage pyrite-III is anhedral and coarse grained and contains randomly oriented inclusions of silicates, sulfides, and native gold grains. Electron microprobe analysis, coupled with X-ray element mapping and laser ablation-inductively coupled plasma-mass spectrometry, reveals that most early pyrites (pyrite-I) have higher concentrations of As and Au in both the zones. The shear-hosted main-stage pyrite-II can be divided into Ni-rich (median 211 ppm) pyrite-IIa and Co-rich (median 274 ppm) pyrite-IIb, respectively. While invisible gold content is higher in vein-hosted late-stage pyrite (pyrite-IIIa; ≤287 ppm) when compared to shear-hosted pyrites, native visible gold is associated with only vein-hosted main- and late-stage pyrites (pyrite-II and IIIa). Arsenic, Ni, Au, Se, Mo, and Te concentrations decrease from pyrite-I to pyrite-III, reflecting remobilization of trace elements during subsequent dissolution-reprecipitation of early formed pyrites. The oscillatory zoning of As, Co, and Ni and slight increase in Bi, Te, Se, Au, and Ag in pyrite-II and pyrite-IIIa represent pressure fluctuations and repeated local fluid phase separation in the ore-forming environment. A positive correlation of Au with Pb, Sb, Bi, and Te confirms the presence of nanoinclusions of mineral phases such as nagyagite, Pb-Sb-Bi tellurides, Au-Ag tellurides, tellurosulfides, and sulfosalts within pyrites, particularly in the vein-hosted zone. Based on several lines of evidence, the following paragenetic sequence is proposed for pyrite formation at Dona, Jonnagiri. Rapid crystallization of early (porous) pyrite-I was followed by its dissolution during ~E-W–trending Sh1 shearing. Crystallization of main-stage pyrite-II and the late-stage pyrite-IIIa is the product of dissolution-reprecipitation of early pyrite during ~N-S–trending Sh2 shearing. Changing fluid compositions caused by episodic fault-valve actions and associated boiling resulted in dissolution-reprecipitation of early formed pyrites and remobilization of trace elements. This further resulted in precipitation of the bulk of gold within the inner vein-hosted zone during the later Sh2 shearing event. At the culmination of shearing, late-stage pyrite-IIIb precipitation occurs with very low concentrations of all trace elements, including gold.

We have developed a highly regio‐ and diastereoselective rhodium‐catalyzed allylic substitution of challenging alkyl‐substituted branched allylic carbonates with benzylzinc reagents, which are prepared from widely available benzyl halides. This process utilizes rhodium(III) chloride as a commercially available, high‐oxidation state and bench‐stable pre‐catalyst to provide a rare example of regio‐ and diastereoselective allylic substitution in the absence of an exogenous ligand. This reaction tolerates both electronically diverse benzylzinc nucleophiles and an array of functionalized and/or challenging aliphatic secondary allylic electrophiles. Finally, the configurational fluxionality of the rhodium‐allyl intermediate is exploited to develop a novel diastereoselective process for the construction of vicinal acyclic ternary/ternary stereogenic centers, in addition to a cyclic ternary/quaternary derivative.

A Cr2+:ZnSe crystal with quasi-continuous-wave single-mode pumping at 1.9 μm generates over 10 dB of single-pass small-signal gain at 2.3 μm. Simulations suggest 30 dB is possible. We attribute the difference to quenching and focal mismatch.

Dharwar Craton in southern India hosts several gold bearing greenstone belts including the well-known Kolar and Hutti. Among them, the Gadag greenstone belt in the western part of Dharwar Craton contains many potential gold mines. It has three different lode systems named western, central and eastern lodes. These lodes are spatially distributed as linear groups along the shear zone with distinct lithological assemblages. Tourmaline is one of the most common hydrothermal minerals present in the alteration zones apart from chlorite, muscovite and sericite. These tourmalines show two textural association (i) occur as isolated, euhedral grains along the mylonitic foliation defined by chlorite, muscovite, sericite, quartz and carbonates (ii) occurrences of anhedral bizarre shaped tourmaline grains along with carbonate and quartz. Though texturally different, compositionally both the tourmalines are similar. They are dravite in nature with high Altot (6.02 to 6.56 apfu), low Na (0.42 to 0.88 apfu) and medium X-vacancies (0.08 to 0.57 apfu). The predominance of Fe2+ (high Fe2+/Fe3+) and low Na in the tourmaline crystal structure indicates low saline, reduced ore fluid of metamorphic origin that is responsible for gold mineralization in Gadag.Microthermometric study of aqueous, carbonic and aqueous-carbonic inclusions from the auriferous lodes at Gadag reveal low to medium saline (0.04 to 9.59 NaCl equiv.) H2O-NaCl-CO2±CH4 ore forming fluid. Presence of trace amount of methane content within the carbonic inclusion indicates mineralization occurred at reducing environment. Thus, fluid inclusion results consistent with the tourmaline chemistry and strongly supports the metamorphic origin of ore fluids that responsible for gold mineralization at Gadag.

We demonstrate experimentally that random phase modulation of an erbium-doped fiber ring-laser by an intra-cavity electro-optic phase modulator did not inhibit ultrashort-pulse operation. Stable and self-starting ultrashort-pulse operation with a single pulse circulating in the cavity was achieved even when the phase modulator was driven with random sequences sufficiently fast and strong to render the laser cavity modeless, in the sense that heterodyning of the laser output did not show any spectral lines corresponding to a mode spectrum. No significant change in measured pulse characteristics was observed, compared to conventional mode-locking in the unmodulated cavity. The insensitivity to the random phase modulation is expected, given the lack of phase-sensitive elements in the cavity., Manuscript submitted to Journal of Lightwave Technology. Accept

The influence of the parameters of Q-switched thulium fiber laser at 1.94 μm on human calcium oxalate monohydrate (COM) urinary stone and soft tissues has been investigated to determine its efficiency on stone fragmentation and tissue ablation along with surrounding thermal injury. The designed Q-switched thulium fiber laser can be operated with peak powers varying from 93 to 493 W, pulse duration from 350 to 750 ns, and repetition rates from 55 to 135 kHz at 9.5 W average power. Comparative effects on COM stone fragmentation rate and soft tissue ablation by using Q-switched and continuous wave (CW) thulium fiber laser have been studied. The stable pulse from the Q-switched thulium fiber laser at high repetition rate is effective for COM stone fragmentation with very fine particle size, average in the range of 47.85 μm, called dusting, at the fragmentation rate of 12.75 mg/min. Soft tissue ablation employing the Q-switched thulium fiber laser is reasonably clean, leaving minimum residual carbonization of 170 μm and heat-affected zone of 0.76 mm. The Q-switched thulium fiber laser produces two times narrower adjacent tissue damage zone along with four times lower charring region compared to the equivalent CW thulium fiber laser exposure in soft tissue.

The topography of active mountain belts is shaped by long-term crustal deformation and strain from tectonic plates. To test this hypothesis, we correlated mean topography, topographic slope and GPS derived strain rates along the active orogenic belts of South America (Ecuador and northern Peru segments), where relatively rapid convergence occurs between the Nazca and South America plates. Our results show that the Ecuador and northern Peru segments follow well-defined power-law relation with distinct exponents that are consistent with the nonlinear deformation associated with dislocation-creep occurring at depth. We propose that the depth of dislocation-creep and distinct power-law exponents have first order control over mean topography, and that the topographic slope can be used as proxy for inter-plate coupling.

Rhodium-catalyzed ortho-C-H functionalization is well known in the literature. Described herein is the Xphos-supported rhodium catalysis of meta-C-H olefination of benzylsulfonic acid and phenyl acetic acid frameworks with the assistance of a para-methoxy-substituted cyano phenol as the directing group. Complete mono-selectivity is observed for both scaffolds. A wide range of olefins and functional groups attached to arene are tolerated in this protocol.

A diode-pumped, air-cooled, all-fiber, quasi-continuous-wave thulium laser at an operating wavelength of 1.94 μm has been designed to study the performance of the laser parameter on the rate of fragmentation and its dependence on stone composition, fragmented particle size, as well as the retropulsion effect. The optimized laser cavity with an active fiber core/cladding diameter of 10/130 μm under a counter-propagating pump provides a stable laser power of 30 W at a slope efficiency of 50% and wall plug efficiency of 17%. The rate of fragmentation along with the retropulsion effect has been studied with human calcium oxalate monohydrate (COM) urinary stones (N=36) of different composition by using the designed laser and 200-μm-core low OH silica delivery fiber. The thulium fiber laser setting of 2.7 J pulse energy at the pulse rate of 10 Hz, pulse width of 90 ms, and peak power of 30 W is successful in breaking human COM stones in a controlled manner at a fragmentation rate of 0.8±0.4 mg/s, with almost uniform fragments of particle size less than 1.6 mm. During the stone fragmentation, the stone displacement (retropulsion effect) is less than 15 mm, even for the fragmented stone mass of 15±5 mg.

α,β-Alkenyl carboxylic acids undergo CuII -mediated decarboxylative annulation reactions with aliphatic cyclic ketones to provide synthetically valuable di-heterocycles. The annulation process tolerates a variety of aliphatic ketones and heterocyclic alkenyl carboxylic acids, producing substituted fused furan derivatives with complete regioselectivity. The current protocol offers a synthetically applicable pathway to construct a variety of oligo-heterocycles through Cu-mediated single-electron transfer and decarboxylation. Notably, synthesis of relatively inaccessible di-heterocycles has been achieved successfully using this protocol.

Single-mode thulium fiber laser (TFL) at 1.94 μm with optimal energy and pulse settings has potential benefits for lithotripsy over the presently used Ho:YAG laser. A fiber Bragg grating-based, all-fiber, continuous-wave and modulated TFL at 1.94 μm is configured to deliver up to 30 W of laser power with efficiency of 50%. The TFL operating in the range of repetition rate 10 Hz-1 kHz and corresponding pulse energy 2 J-1.05 mJ is irradiated on urinary stone for in-vitro evaluation of fragmented particle size and retropulsion. TFL irradiation at higher repetition rate fragments the stones into smaller particle size (average size of few hundreds microns) resulting reduced retropulsion.

The Nidar Ophiolite Complex (NOC) in the Ladakh Himalaya region of northern India is well-preserved and exposed along the Indus Yarlung–Zangbo suture zone. This sequence has been thrusted onto the Indus Formation to the north and to the Zildat ophiolitic melange in the south. Chromitite mineralization in the NOC occurs as massive, semi-massive, and disseminated ore bodies hosted by dunite. The chromite in these ore bodies contains inclusions of isolated silicates, base metal sulfides, and platinum-group minerals. Little variation in the [Cr/(Cr + Al)] (i.e., Cr#) (0.78–0.86) is observed, in contrast to Mg# ([Mg/(Mg + Fe2+)]), which is more variable (0.56–0.73). The NOC chromitites are high in Cr (Cr# > 0.78), suggesting a possible boninitic parent magma. The calculated (Al2O3)melt and (FeO/MgO)melt range from 9.29 to 11.50 and 0.49–0.10, respectively. The trace element compositions of these chromitites (Ga: 14–27 ppm; Ni: 440–1301 ppm; V: 612–802 ppm; Sc: 2–6 ppm; Co: 207–542 ppm) are comparable to those hosted in the mantle sections of other ophiolite complexes. The overall chemical composition, deduced from the Al2O3 content and FeO/MgO ratio of the primitive parent magma of high-Cr chromitites, is consistent with island arc tholeiitic melts of boninitic affinity. This parent magma would have been in equilibrium with podiform chromitites and associated ultramafic rocks. Further, the distributions of minor and trace elements in NOC chromites also indicate a boninitic magma source. The field relations, petrographic observations, and major and trace element compositions of the studied chromitites suggest that they have undergone melt–rock and melt–melt interactions, which led to the precipitation of high-Cr chromitites from Cr-rich and Al- and Ti-poor boninitic melts. The occurrence of high-Cr chromitites and the boninitic nature of the parent magma indicate that the chromitite layers of the NOC likely formed in an island arc supra-subduction zone.

A nano-second mode-locked Er: Yb fiber laser has been employed to generate gain-switched pulses of sub-100 ns duration from a thulium fiber laser cavity with a wavelength near water absorption peak. Potential application in tissue ablation surgery is under study.

A universal simulation model for rare earth doped cw fibre lasers is presented. The model is based on generic rate and gain equations and therefore is very compact. It can be used for any fibre doped with one or several rare earth ions. The model allows for spectral simulations as well as radial discretization of the fibre. An algorithm was developed which optimizes the longitudinal fibre segmentation of the model. Spectroscopic parameters for Thulium doped fibre lasers are taken from the literature or derived from calculations. Calculated multiphonon up-conversion rates take the thermalisation of closely spaced states into account. The simulation is compared with measurement results of a coupled wavelength shift observed in a tunable fibre ring laser. The simulation allows to investigate possible explanations and it indicates that the phenomenon is a measurement artefact.

A focused laser beam at wavelength of strong water absorption at 1.94 μm can be a good scalpel for precision soft tissue surgery. A fiber Bragg grating-based, all-fiber, continuous-wave as well as modulated, cladding pumped, thulium-doped fiber laser at 1.94 μm has been configured to deliver up to 10 W of laser power under pumping at 793 nm having an efficiency of 32 %. The laser was exposed to freshly sacrificed chicken breast at different power level and exposure time. The formalin-fixed samples were examined by microscopy to identify the ablation region, carbonization and necrosis region for laser parameter optimization.

There are many Neoarchaean orogenic gold hosting greenstone belts in the Dharwar Craton (DC), India; among them the southern extension of the Kolar greenstone belt (SKGB) contain promising gold deposits such as Chigargunta and Bisanatham. Auriferous laminated quartz-calcite veins are hosted mainly within the sheared and altered Champion gneiss and amphibolite in Chigargunta and Bisanatham respectively. The hydrothermal alteration mineral assemblages show three main alteration zones at Chigargunta. However, only two alteration zones were identified at Bisanatham. The hydrothermal mineral assemblage at Chigargunta and Bisanatham indicate a similar mineralogy that consists of tourmaline, muscovite, biotite, chlorite, epidote, sericite, calcite and quartz along with sulfide and gold. Sulfides associated with ore are predominantly pyrrhotite, pyrite, arsenopyrite, chalcopyrite, ±molybdenite in both the places. Native gold is mainly associated with pyrrhotite in the inner and proximal zone of both the deposits. Fluid inclusion petrography and microthermometry from quartz-calcite veins within the mineralized zone at Chigargunta reveal a low to medium salinity (0.5 to 13.3 wt% NaCl equiv.) H2O-NaCl-CO2-CH4 ± N2 bearing fluid. However, at Bisanatham only H2O-NaCl fluid with low salinity (1.56 to 6.44 wt% NaCl equiv.) was observed. P-T conditions of the gold mineralization at the Chigargunta and Bisanatham deposits range between 1.7 and 3.5 kbar pressure/285 °C to 378 °C temperature and 0.8 to 1.2 kbar pressure/365 °C to 405 °C temperature respectively. Alteration mineralogy, ore mineral assemblages, fluid compositions and P-T conditions from the SKGB confirm that the near neutral to slightly alkaline mineralizing fluid transported gold as Au(HS)2− complexes with low ƒO2 conditions. The observed drastic pressure and temperature fluctuation suggests that fault-valve mechanism/pressure cycling occurred at the time of gold precipitation. Carbon (δ13CCO2) isotopic composition of ore fluid deduced from calcite varies from −2.4 to +3.3‰ (average: −0.3‰) and −2.1 to +1.4‰ (average: −0. 8‰) for Chigargunta and Bisanatham respectively. Oxygen isotopic (δ18OH2O) values for both the deposits vary from +7.2 to +14.6‰ (average: +9.3) and +7.3 to +8.9‰ (average: +8.3‰) respectively. Ore-forming fluid could have possibly been derived from the decarbonation of marine carbonates during the metamorphic devolatilization of greenstones. The slight intra-deposit variation of the carbon isotopic value implies the Rayleigh fractionation with progressive consumption of the CO2 as a result of interaction between hydrothermal fluid and wall rock as well as immiscibility of CH4 and CO2 fluid. Ore fluid sulfur (δ34SH2S) isotopic composition, derived from δ34S values of sulfides, varies from −0.42 to +2.43‰ and +0.25 to +2.34‰ for Chigargunta and Bisanatham respectively. Both the sulfur and carbon isotopic values, from these deposits are comparable with other orogenic gold deposits in the DC and elsewhere in the world. Although carbon isotopic values possibly indicate the metamorphic fluid source, the sulfur isotopes signify average crustal sulfur composition that is from crustally derived/modified fluid. Based on the field-geological, mineralogical, fluid, and isotopic compositions, the possible fluid source could be from the metamorphic devolatilization process of the thick greenstone sequence in the SKGB. However, a magmatic source could be further tested with geochronological studies on intrusives in the area.

A continuous-wave (CW) as well as quasi-continuous wave (QCW) thulium-doped all-fiber laser at 1.94 μm has been designed for targeting applications in urology. The thulium-doped active fiber with an octagonal-shaped inner cladding is pumped at 793 nm to achieve stable CW laser power of 10 W with 32% lasing efficiency (against launched pump power). The linear variation of laser power with pump offers a scope of further power scaling. A QCW operation with variation of duty cycle from 0.5% to 90%, repetition rate from 0.1 Hz to 1 kHz, and pulse width from 40 μs to 2 s has been presented. Laser power of 9.5 W in CW mode of operation and average power of 5.2 W with energy range of 10.4-104 mJ in QCW mode of operation has been employed to fragment calcium oxalate monohydrate kidney stones (size of 1.5-4 cm) having different colors and composition. Dependence of ablation threshold, ablation rate, and average fragmented particle size on the average power and energy has been studied. One minute of laser exposure results in fragmentation of a stone surface with ablation rate of 8 mg/min having minimum particle size of 6.54 μm with an average size of 20-100 μm ensuring the natural removal of fragmented parts through the urethra.

A layout decomposition in Double Patterning Lithography (DPL) is considered to be potential for processing nodes at or below 32 nm. In this method, two features are assigned different colors corresponding to different exposures if the spacing between them is less than a minimum value defined by design-specific rules. In general, there are cases where such different colors assignment may not be possible even though the inter-feature spacing is less than the specified minimum. This condition is often known as color conflict of adjacent features. Color conflicts are traditionally resolved by splitting the features. This problem is often modeled as a graph-theoretic problem, with color conflicts identified as odd-cycle detection, and the duplication of vertices of the graph arising out of splitting of features of a layout. However, for a given layout, the splitting of features may not always be desirable or even feasible. In this paper, we propose a merge-only technique with conservative application of de-compaction so that the overall area of the layout is minimally affected. We consider layouts having rectilinear features present in the layout and apply the proposed algorithm to obtain a DPL-compliant layout with selective use of stitches keeping the overall layout area fixed. Experimental results with some standard layouts demonstrate the effectiveness of the proposed algorithm.

A gain-switched all-fiber thulium laser at 2 μm with high repetition rate has been demonstrated under a hybrid pumping scheme combined of a pulsed pump at 1.56 μm and CW pump at 793 nm. The in-band pulsed pump at 1.56 μm triggers the gain-switching pulses while the CW pump at 793 nm facilitates the energy storage. Therefore, the seed cavity delivers high energy pulses allowing the elimination of multistage amplification. Such hybrid pump configuration is effective for generating gain-switched pulses of high average power with better slope efficiency and pulse width of a few hundreds of a nanosecond. The optimized cavity under such hybrid pump configuration provides output power of 5.92 W from the gain-switched oscillator with slope efficiency of 60% and pulse width of 300 ns at a repetition rate of 344 kHz. Maximum pulse energy of 17.2 μJ and peak power of 53.9 W has been achieved at this repetition rate. Stable gain-switched pulses at reduced pump pulse energy have been achieved by the use of a CW pump at 793 nm. This novel pump configuration facilitates gain switch at higher repetition rates where enough pump pulse energy may not be available. The gain-switched laser also operates at 520 kHz and 1.3 MHz repetition rate by changing the 1.56 μm pulsed pump and cavity length.

All-fiber Holmium laser at 2.1 µm is designed by using in-house fabricated Ho-doped fiber under pumping at 1.95 µm. Laser output power of 7 W has been obtained with slope efficiency of 74.25%.

Strong water absorption at 2 μm generated recent interest in lasers at this wavelength for soft tissue surgery. A fiber Bragg grating-based, all-fiber, continuous-wave, cladding pumped, thulium-doped fiber laser at 1.95 μm is configured. The thulium-doped active fiber with octagonal-shaped inner cladding is pumped at 808 nm (total power of 17 W) with six laser diodes through a combiner. The laser power of 3.3 W (after elimination of unabsorbed pump power through a passive fiber) with slope efficiency of 23% (against launched pump power) is achieved. The linear variation of laser power with pump offers scope of further power scaling.

Fiber laser below 2000 nm is required for effective urological applications because of strong water absorption. Design of all-fiber thulium laser at this wavelength under pumping at 793 nm, utilizing cross relaxation mechanism, demands rigorous optimization of parameters as highly concentrated thulium doped silica has maximum gain at around 2010 nm. Length of the active fiber and the reflectivity of the output coupler have been optimized for maximum slope efficiency and output power. Counter propagating pumping scheme has been considered for better thermal management and good lasing efficiency. Spectral property and time domain response of the laser have been studied at different levels of output power. Lasing characteristics at 1910 nm, 1950 nm, 2000 nm and 2100 nm have also been investigated. The continuous wave lasing at 1950 nm with output power of 16.1 W having slope efficiency of 65.6% has been demonstrated. In quasi-continuous wave mode of operation, pulse energy in the range of 400 µJ to 5 mJ has been measured for the peak power of 16 W. The designed laser has been used successfully in human kidney stone breaking.

This work presents a comprehensive computer simulation study for the hydrolytic polymerization of e-caprolactam without water removal in a continuous tubular reactor. It incorporates a laminar (Hagen-Poiseuille) or plug flow velocity profile, as well as radial thermal diffusion. The solution of the balance equations is carried out using two types of finite-difference techniques coupled with Gear's method for solving the ordinary differential equations so generated. Simulation results are obtained for various operating conditions. A comparison is made of the different methods used and their limitations are discussed. These results will form the basis for a comparison of the numerical results that could be generated using far more powerful computational tools like orthogonal collocation or finite-element techniques.

Presenting fabrication process and characteristics of large core Yb–doped optical fibers with pedestal design using vapor phase doping technique. Preforms have uniform step–index profiles. Fibers exhibit good optical properties, suitable for high power laser applications.