The recognition in the 1990s that light beams with a helical phase front have orbital angular momentum has benefited applications ranging from optical manipulation to quantum information processing. ...Recently, attention has been directed towards the opportunities for harnessing such beams in communications. Here, we demonstrate that four light beams with different values of orbital angular momentum and encoded with 42.8 × 4 Gbit s-1 quadrature amplitude modulation (16-QAM) signals can be multiplexed and demultiplexed, allowing a 1.37 Tbit s-1 aggregated rate and 25.6 bit s-1 Hz-1 spectral efficiency when combined with polarization multiplexing. Moreover, we show scalability in the spatial domain using two groups of concentric rings of eight polarization-multiplexed 20 × 4 Gbit s-1 16-QAM-carrying orbital angular momentum beams, achieving a capacity of 2.56 Tbit s-1 and spectral efficiency of 95.7 bit s-1 Hz-1 . We also report data exchange between orbital angular momentum beams encoded with 100 Gbit s-1 differential quadrature phase-shift keying signals. These demonstrations suggest that orbital angular momentum could be a useful degree of freedom for increasing the capacity of free-space communications.
Artemisinin is highly effective against drug-resistant malarial parasites, which affects nearly half of the global population and kills 〉500 000 people each year. The primary cost of artemisinin is ...the very expensive process used to extract and purify the drug from Artemisia annua. Elimination of this apparently unnecessary step will make this potent antimalarial drug affordable to the global population living in endemic regions. Here we reported the oral delivery of a non-protein drug artemisinin biosynthesized （~0.8 mg/g dry weight） at clinically meaningful levels in tobacco by engineering two metabolic pathways targeted to three different cellular compartments （chloroplast, nucleus, and mitochondria）. The doubly transgenic lines showed a three-fold enhancement of isopentenyl pyrophosphate, and targeting AACPR, DBR2, and CYP71AV1 to chloroplasts resulted in higher expression and an efficient photo-oxidation of di- hydroartemisinic acid to artemisinin. Partially purified extracts from the leaves of transgenic tobacco plants inhibited in vitro growth progression of Plasmodium falciparum-infected red blood cells. Oral feeding of whole intact plant cells bioencapsulating the artemisinin reduced the parasitemia levels in challenged mice in comparison with commercial drug. Such novel synergistic approaches should facilitate low-cost production and delivery of artemisinin and other drugs through metabolic engineering of edible plants.
Linear and nonlinear propagation characteristics of multidimensional drift ion-acoustic (IA) solitons are studied in an inhomogeneous partially degenerate electron-ion magnetoplasma. A modified ...Zakharov-Kuznetsov (mZK) equation is deduced, accounting for the longitudinal as well as the transverse dispersions. It is shown that the mZK equation admits a distinct solution, revealing excitation of a pulse-shaped soliton when the phase speed exceeds by the wave dispersion. For the instability condition of the waves, a novel growth rate (γ) is derived by modifying the standard small-k expansion scheme. The instability criterion, given for long-wavelength IA waves, has not been described elsewhere. Numerical analysis show that solitary pulses gain energy from the ion drift, involving into instability: it saturates with amplification of the unstable potentials. Similarly trapped electrons lead to unstable growth of the solitary waves by enhancing γ. This study is relevant to compact stars and to high-density facilities where density inhomogeneity ensues the unstable drift modes. The instability analysis is important in understanding anomalous diffusion, which reduces the lifespan (τ=γ^{-1}) of magnetically confined plasma.
This study evaluated the reduction of CO2 to methanol in the presence of effective and stable MWCNTs impregnated with Cu2O. A preliminary DFT study shows that the incorporation of Cu2O in MWCNTs ...improves the electronic properties of the electrocatalyst. The surface morphology and structural interaction between Cu2O and MWCNTs at different Cu2O loadings (10–50wt%) were characterized by SEM, TEM, EDX, XRD, BET, TGA, and Raman spectroscopy. Characterization results show that the Cu2O particles are incorporated at defect sites in the MWCNT matrix. However, higher lodgings (40 and 50wt%) result in the agglomeration of Cu2O particles and crystallite size growth. Electrochemical evaluation of the catalyst for CO2 reduction was conducted in a two-component polycarbonate electrochemical cell. Linear sweep voltammetry results show that the 30% Cu2O-MWCNTs catalyst gives the highest current density in the entire potential range, and a faradaic efficiency of 38% was achieved at −0.8V for the reduction of CO2 to methanol. The study shows that the impregnation of Cu2O on MWCNTs affects the structural and electronic properties of the electrode, which in turn improves both the activity and stability of the catalyst as confirmed by chronoamperometry.
•Synthesis of a Cu2O catalyst supported on MWCNTs functionalized with carboxyl groups.•Characterizing the electrocatalyst and optimizing the Cu2O loading on MWCNTs.•Evaluation of the electrocatalyst in a two-component polycarbonate electrochemical cell.•A Faradic efficiency of 38% in the reduction of CO2 to methanol.•Supporting Cu2O on MWCNTs increased the active surface area and electronic properties.
The true incidence of sudden cardiac death (SCD) in US athletes is unknown. Current estimates are based largely on case identification through public media reports and estimated participation rates. ...The purpose of this study was to more precisely estimate the incidence of SCD in National Collegiate Athletic Association (NCAA) student-athletes and assess the accuracy of traditional methods for collecting data on SCD.
From January 2004 through December 2008, all cases of sudden death in NCAA student-athletes were identified by use of an NCAA database, weekly systematic search of public media reports, and catastrophic insurance claims. During the 5-year period, there were 273 deaths and a total of 1 969 663 athlete participant-years. Of these 273 deaths, 187 (68%) were due to nonmedical or traumatic causes, 80 (29%) to medical causes, and 6 (2%) to unknown causes. Cardiovascular-related sudden death was the leading cause of death in 45 (56%) of 80 medical cases, and represented 75% of sudden deaths during exertion. The incidence of SCD was 1:43 770 participants per year. Among NCAA Division I male basketball players, the rate of SCD was 1:3100 per year. Thirty-nine (87%) of the 45 cardiac cases were identified in the NCAA database, only 25 (56%) by use of public media reports, and 9 (20%) from catastrophic claims data.
SCD is the leading medical cause of death and death during exercise in NCAA student-athletes. Current methods of data collection underestimate the risk of SCD. Accurate assessment of SCD incidence is necessary to shape appropriate health policy decisions and develop effective strategies for prevention.
The aim of this work was to study the pyrolysis kinetics of the thermal transformation of kaolin to metakaolin with the aid of models and model free isoconversional methods. Thermal treatment in the ...range of 600–850°C is used to convert kaolin into an amorphous and highly reactive metakaolin (MK). In this study, the thermal transformation of kaolin to metakaolin was investigated using thermokinetics and instrumental analysis. Kaolin was subjected to thermogravimetric analysis (TGA) at heating rates of 10, 20 and 40°C/min, in the temperature range of 50–800°C. Approximately, 14.2% of mass loss was recorded during the TG analysis. 95% of the degree of dehydroxylation was attained at 635°C, representing the minimum temperature for this process. The TGA and its related data were analyzed using model free (based on DTG, DTA and TG) and model based kinetics methods. Both DTG and DTA peak temperatures were employed for the thermokinetics of kaolin using Ozawa, Kissinger and Starink methods; giving an Ea in the range of 246.6–252.5kJ·mol−1. A slight higher average Ea (266–267kJ·mol−1 vs 246.6–252.5kJ·mol−1) was observed when TGA based integral methods (KAS, FWO and Starink) were used. The mechanism of the thermokinetics was investigated using the Redfern model and the best fitting was given by 3rd order chemical reaction (F3) function. Both model-free and model based thermokinetics methods could be used to validate the thermal transformation of kaolinite to metakaolinite.
•Thermokinetics methods produced Ea in the range of 246.6-281KJ/mol and the lnA in the range of 31-39min-1.•Starink method was successfully applied to DTG, DTA and TG data.•The Redfern model showed that a third order chemical reaction (F3) was followed by thermal transformation of kaolin.•The 95% dehydroxylation can be achieved at temperature higher than 635°C.
Demonstration of an ac Josephson junction laser Cassidy, M. C.; Bruno, A.; Rubbert, S. ...
Science (American Association for the Advancement of Science),
03/2017, Letnik:
355, Številka:
6328
Journal Article
Recenzirano
Odprti dostop
Superconducting electronic devices have reemerged as contenders for both classical and quantum computing due to their fast operation speeds, low dissipation, and long coherence times. An ultimate ...demonstration of coherence is lasing. We use one of the fundamental aspects of superconductivity, the ac Josephson effect, to demonstrate a laser made from a Josephson junction strongly coupled to a multimode superconducting cavity. A dc voltage bias applied across the junction provides a source of microwave photons, and the circuit’s nonlinearity allows for efficient down-conversion of higher-order Josephson frequencies to the cavity’s fundamental mode. The simple fabrication and operation allows for easy integration with a range of quantum devices, allowing for efficient on-chip generation of coherent microwave photons at low temperatures.
A modern progress in fluid dynamics has been emphasizes on nanofluids which maintain remarkable thermal conductivity properties and intensify the transport of heat in fluids. Here, the present-day ...endeavor progresses a Maxwell nanofluid towards stretched cylinder heated convectively. The addition properties, i.e., MHD, stagnation point, thermal radiation, heat sink/source and chemical reactions are elaborated. The homotopic algorithm has been exploited for solutions of ODEs. Here, it is noted that the temperature field enhances for Biot number and radiation parameter. Additionally, Brownian movement and thermophoretic influences have conflicting performance for nanomaterial concentration. The mass transport rate for constructive–destructive chemical reaction is opposite in nature in response to the thermal Biot number. The ratification of our findings is also addressed via tables and attained noteworthy results.
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