Strong backaction on a mechanical resonator by a few photons

Cavity electromechanical systems, consisting of a mechanical resonator coupled to an electromagnetic mode, are extensively used for sensing of various forces and controlling the vibrations of a mechanical mode down to their quantum limit. In the microwave domain, such devices based on magnetic-flux coupling have emerged as a promising platform with the potential to reach a single-photon strong coupling regime. Here, we demonstrate a flux-coupled electromechanical device using a frequency tunable superconducting transmon qubit, and a microwave cavity. By tuning the qubit in resonance with the cavity, the hybridized state (dressed mode) of the qubit and the cavity mode is used to achieve a magnetic field-dependent electromechanical coupling. It is established by performing an electromagnetically-induced transparency (EIT)-like experiment. At the largest applied field, we estimate the single-photon coupling rate of 60 kHz. Further, in the presence of the pump signal, we observe backaction, showing both cooling and heating of the mechanical mode. With a stronger pump, the dressed mode shows the signature of "super-splitting", and a strong backaction on the mechanical resonator, reflected in the broadening of the mechanical linewidth by a factor of 42 while using less than 1 photon in the dressed mode.Comment: Total 9 figures; 13 page

ANALYTICAL METHOD DEVELOPMENT, VALIDATION AND STABILITY STUDIES BY RP-HPLC METHOD FOR SIMULTANEOUS ESTIMATION OF ANDROGRAPHOLIDE AND CURCUMIN IN CO-ENCAPSULATED NANOSTRUCTURED LIPID CARRIER DRUG DELIVERY SYSTEM

Objective: The current study aims to boost the bioavailability criteria of two natural bioactive compounds, andrographolide and curcumin by their combination in nanostructured lipid carrier (NLC) and also to develop a straightforward reverse-phase high-performance liquid chromatography (RP-HPLC) method to validate, quantify of andrographolide and curcumin simultaneously in novel NLC formulation. Methods: The reliable chromatographic separation was executed by using a column of Phenomenex octadecylsilane (C18) at 35 °C column oven temperature using a mobile phase of 0.02 M potassium dihydrogen orthophosphate (KH2PO4) salt solution of pH 3.0 as a buffer and acetonitrile in 50: 50 v/v fixed ratio and 1.5 ml/min flow rate of with 20 μl injection load. The detection was carried out at 240 nm isosbestic wavelength employing a photodiode array (PDA) detector. Results: Andrographolide and curcumin were eluted at 2.4 and 4.9 min, respectively. Quantification and linearity were achieved for both drugs at the 10-140 μg/ml range. The method is specified as the presence of excipients utilized in the formulation failed to interfere with the estimation of andrographolide and curcumin. The developed method was successfully utilized to work out the drug loading efficiency and in vitro drug release study of those drugs in NLC formulation and also for the estimation of those drugs from rat plasma. Conclusion: The developed high-performance liquid chromatography (HPLC) method may be utilized in the future estimation of andrographolide and curcumin simultaneously in NLC and other nanoformulations both in vitro and in vivo

PREPARATION AND CHARACTERIZATION OF ANDROGRAPHOLIDE NANOPARTICLES FOR VISCERAL LEISHMANIASIS CHEMOTHERAPY: IN VITRO AND IN VIVO EVALUATIONS

Objective: To overcome low physiological solubility, poor bioavailability, the short plasma half-life of andrographolide (AG), a delivery system based on poly (D, L-lactide-co-glycolide) (PLGA) nanoparticles (NPs) were developed to increase the efficiency of AG against visceral leishmaniasis (VL). Methods: Andrographolide-PLGA nanoparticles (AGnp) were prepared with Pgp efflux inhibitor vitamin E TPGS (D-α-tocopheryl polyethylene glycol 1000 succinate) by emulsion solvent evaporation method and characterized. Antileishmanial activity was evaluated using in vitro and in vivo VL infection model. Results: The particle size of AGnp was found to be171.4±11.5 nm with an encapsulation efficiency of 81%. The AGnp reduced AG cellular toxicity, retained it's in vitro antileishmanial activity and lead to a reduction (99.9%) of parasite burden in the Leishmania donovani infected spleen and liver. AGnp was more active in infected mice liver at low dose than in spleen. Therapeutic indexes (TI) were 6.9-fold greater in AG and 68-fold in AGnp compared to amphotericin B (AmB) when evaluated in L. donovani infected spleen. Conclusion: Incorporation of AG in PLGA nanoparticles, provided controlled and improved in vivo performance against V

On higher dimensional Poissonian pair correlation

In this article we study the pair correlation statistic for higher dimensional sequences. We show that for any $d\geq 2$, strictly increasing sequences $(a_n^{(1)}),\ldots, (a_n^{(d)})$ of natural numbers have metric Poissonian pair correlation with respect to sup-norm if their joint additive energy is $O(N^{3-\delta})$ for any $\delta>0$. Further, in two dimension, we establish an analogous result with respect to $2$-norm. As a consequence, it follows that $(\{n\alpha\}, \{n^2\beta\})$ and $(\{n\alpha\}, \{[n\log^An]\beta\})$ ($A \in [1,2]$) have Poissonian pair correlation for almost all $(\alpha,\beta)\in \mathbb{R}^2$ with respect to sup-norm and $2$-norm. This gives a negative answer to the question raised by Hofer and Kaltenb\"ock [15]. The proof uses estimates for 'Generalized' GCD-sums.Comment: Added references and corrected typos. To appear in Journal of Mathematical Analysis and Application

VALIDATION, STABILITY STUDIES, AND SIMULTANEOUS ESTIMATION OF CO-ENCAPSULATED CURCUMIN, EPIGALLOCATECHIN GALLATE NANOFORMULATION BY RP-HPLC METHOD

Objective: A new reverse-phase high-performance liquid chromatography (RP-HPLC) method was developed to simultaneously determine curcumin and epigallocatechin gallate (EGCG) in novel nanoformulation. Methods: The high-performance liquid chromatography (HPLC) method was achieved by using a Thermo Scientific Hypersil Base Deactivated Silica (BDS) C18 column (25 cm X 4.6 mm, 5 µm) at 35 °C column oven temperature. The chromatographic procedure was performed with a mobile phase of acetonitrile and 0.025 M (pH 4.0) potassium dihydrogen phosphate (KH2PO4) buffer by gradient mode of elution. The injection volume was 20 µl, and the flow rate was 1.5 ml/min, with ultraviolet (UV) detection using a diode array detector (DAD) at a 268 nm isosbestic wavelength. Results: Drug entrapment efficiency studies were performed with co-encapsulated EGCG and curcumin nanoformulation, which were found to be 94.35 % and 95.12 %, respectively. This shows that the developed method is highly effective. EGCG and curcumin were eluted at 3.9 min and 10.7 min, respectively. The linearity range was 25-175 µg/ml for EGCG and 12.5-100 µg/ml for curcumin. The correlation coefficient was 0.991 for EGCG and 0.999 for curcumin from the linearity curve, which indicates that the method can produce good sensitivity. Forced degradation studies were conducted in acidic, basic, oxidative, thermal, photolytic, and UV stress conditions, where all the degradation peaks were monitored. Conclusion: The developed method was linear, simple, rapid, robust, and precise. It could be used to quantify EGCG and curcumin simultaneously in various nanoformulations for in vivo and in vitro applications

Steady-state Quantum Thermodynamics with Synthetic Negative Temperatures

A bath with a negative temperature is a subject of intense debate in recent times. It raises fundamental questions not only on our understanding of negative temperature of a bath in connection with thermodynamics but also on the possibilities of constructing devices using such baths. In this work, we study steady-state quantum thermodynamics involving baths with negative temperatures. A bath with a negative temperature is created synthetically using two baths of positive temperatures and weakly coupling these with a qutrit system. These baths are then coupled to each other via a working system. At steady-state, the laws of thermodynamics are analyzed. We find that whenever the temperatures of these synthetic baths are identical, there is no heat flow, which reaffirms the zeroth law. There is always a spontaneous heat flow for different temperatures. In particular, heat flows from a bath with a negative temperature to a bath with a positive temperature which, in turn, implies that a bath with a negative temperature is `hotter' than a bath with a positive temperature. This warrants an amendment in the Kelvin-Planck statement of the second law, as suggested in earlier studies. In all these processes, the overall entropy production is positive, as required by the Clausius statement of the second law. We construct continuous heat engines operating between positive and negative temperature baths. These engines yield maximum possible heat-to-work conversion efficiency, that is, unity. We also study the thermodynamic nature of heat from a bath with a negative temperature and find that it is thermodynamic work but with negative entropy.Comment: 7+2 pages, comments welcom

Instabilities near ultrastrong coupling in microwave optomechanical cavity

With artificially engineered systems, it is now possible to realize the coherent interaction rate, which can become comparable to the mode frequencies, a regime known as ultrastrong coupling (USC). We experimentally realize a cavity-electromechanical device using a superconducting waveguide cavity and a mechanical resonator. In the presence of a strong pump, the mechanical-polaritons splitting can nearly reach 81% of the mechanical frequency, overwhelming all the dissipation rates. Approaching the USC limit, the steady-state response becomes unstable. We systematically measure the boundary of the unstable response while varying the pump parameters. The unstable dynamics display rich phases, such as self-induced oscillations, period-doubling bifurcation, period-tripling oscillations, and ultimately leading to the chaotic behavior. The experimental results and their theoretical modeling suggest the importance of residual nonlinear interaction terms in the weak-dissipative regime.Comment: 7 pages, 4 figures, and supplemental materia