Asymmetric Total Synthesis of (+)-Epiibogamine Enabled by Three-Component Domino Michael/Michael/Mannich Annulation of N-Sulfinyl Metallosilylenamines.

The iboga alkaloids are promising antiaddictive and neuroregeneration candidates for medical treatment. There is a lack of studies for C20-epi iboga alkaloids due to the synthetic difficulties. Herein we report the shortest total synthesis of (+)-epiibogamine in seven steps from trimethyl orthobutyrate. The novel N-sulfinyl silylenamine reagent enabled the key step, with three-component domino Michael/Michael/Mannich annulation providing the 1-amino-2,4-diester scaffold with four new chiral centers, and access to the isoquinuclidine in high yield (84%) and diastereoselectivity (>95:5 dr).

Diastereoselective Hydroxylation of N-tert-Butanesulfinyl Imines with 2-(Phenylsulfonyl)-3-phenyloxaziridine (Davis Oxaziridine).

The diastereoselective α-hydroxylation of N-tert-butanesulfinyl metallodienenamine and metalloenamines with Davis oxaziridine affords α-hydroxy N-sulfinyl imines with 50-88% yield and up to 98:2 diastereomeric ratio. Dramatic changes in diastereoselectivity and stereoselectivity were observed by choice of metal bases. The mechanistic understanding for the switch in diastereoselectivity was assisted by DFT computational modeling, which suggests the facial approach is governed by aza-enolate geometry. A one-pot protocol for the asymmetric synthesis of 1,2-amino alcohols is described.

On-chip estimation of hematocrit level for diagnosing anemic conditions by Impedimetric techniques.

An on-chip device has been fabricated on Si platform for precise estimation of the hematocrit (Hct) level of human blood with rapid turn out. Impedance/capacitance spectroscopy and current-voltage (I-V) measurements have been employed to observe the variation of electrical parameters of erythrocyte suspensions with varying Hct level. Experimentally obtained values of capacitance, impedance and conductance with Hct level suggests a linear variation. Current-time measurement has also been performed to ensure the susceptibility of red blood cells under a fixed external electric field for certain duration of time. The online real time sample analyzes have also been performed by the device connected with an embedded electronic circuit interfaced with a laptop through appropriate software. This has enabled the development of a novel Si-chip based compact point-of-care (POC) diagnosis system for Hct level estimation by measuring the dielectric/capacitive variation of an erythrocyte cell suspension. The relevant performance parameters of such a compact system including range, resolution, limit of detection and throughput have also been evaluated.

Prescription of wavelength-dependent spot size relations of a broadband laser diode in the context of uniformly maximum lens excitation of WDM signals.

We prescribe an empirical relationship between spot size and emitted wavelength for a semiconductor laser diode generating a broad spectrum of light in the near infrared range of 1.5-1.6 µm. Then, we establish uniformly maximum launch optics employing these relations in the case of hyperbolic microlens lens excitation of a step index single-mode fiber using this source. Subsequently, we explain the necessity of this source in the context of wavelength-division multiplexing (WDM) and dense WDM signal transmission with guidelines inviting its fabrication.

Light triggered uncaging of hydrogen sulfide (H2S) with real-time monitoring.

An ESIPT based light activated hydrogen sulfide (H2S) donor using a p-hydroxyphenacyl phototrigger has been developed. The unique feature of our H2S donor system is that it provides real-time monitoring of H2S release by a non-invasive fluorescence colour change approach.

FT-MIR supported Electrical Impedance Spectroscopy based study of sugar adulterated honeys from different floral origin.

This study sought to detect the presence of sucrose as an adulterant in selected honey varieties from different floral origins by employing Electrical Impedance Spectroscopy (EIS) technique which has been simultaneously supported by Fourier Transform-Mid Infrared Spectroscopy (FT-MIR) measurements to provide a rapid, robust yet simple platform for honey quality evaluation. Variation of electrical parameters such as impedance, capacitance and conductance for 10%, 20%, 30%, 40%, 50%, 60% and 70% (w/w) sucrose syrup (SS) adulterated honey samples are analyzed and their respective current-voltage (I-V) characteristics are studied. Capacitance, conductance and net current flowing through the system are observed to decrease linearly whereas system impedance has been found to increase similarly with the increase in adulterant content. Also, FT-MIR measurements in the spectral region between 1800cm-1 and 650cm-1 reveal the increment of absorbance values due to the addition of SS. Full-Width-at-Half-Maximum (FWHM) is estimated from the spectral peak 1056cm-1 for all pure and adulterated honey samples and is observed to be linearly increasing with increase in adulterant content. Finally, the coefficient of sensitivity has been extracted for all varieties of honey considered in terms of the measured conductance values.

Detailed particle-in-cell simulations on the transport of a relativistic electron beam in plasmas.

We present comprehensive two-dimensional (2D) particle-in-cell (PIC) simulations on the transport of a relativistic electron beam in a plasma in the context of fast ignition fusion. The 2D PIC simulations are performed by constructing two different simulation planes and have shown the complete stabilization and destabilization of the Weibel instability due to the beam temperature and background plasma collisions, respectively. Some three-dimensional PIC simulation results on the filamentary structures are also shown thereby further shedding light on the filamentation of the electron beam in plasmas. The linear growth rates of fastest growing mode in the beam-plasma system are compared with a theoretical model developed and are found in good agreement with each other.

Collision-driven negative-energy waves and the weibel instability of a relativistic electron beam in a quasineutral plasma.

A new model describing the Weibel instability of a relativistic electron beam propagating through a resistive plasma is developed. For finite-temperature beams, a new class of negative-energy magnetosound waves is identified, whose growth due to collisional dissipation destabilizes the beam-plasma system even for high beam temperatures. We perform 2D and 3D particle-in-cell simulations and show that in 3D geometry the Weibel instability persists even for collisionless background plasma. The anomalous plasma resistivity in 3D is caused by the two-stream instability.