A site-selective alkylation of dehydroalanine to access protected unnatural amino acids is described. The protocol is characterized by the wide nature of alkyl radicals employed, mild conditions, and ...functional group compatibility. This protocol is further extended to access peptides, late-stage functionalization of pharmaceuticals, and enantioenriched amino acids.
HYDRUS 2D was used to simulate chloropicrin (CP) emissions across a range of expected application and environmental conditions present within California, where CP is widely used in the pre-plant ...treatment of soils for high-value specialty crops. Simulations were developed based on field calibration work and physicochemical parameters from literature with additional consideration of application rate-dependent degradation and applicator practices including application depth, application mode, and tarp material. Model output was compared to the distribution of indirect whole-field flux estimates derived from field monitoring studies using measures of maximum 8-h, maximum 24-h, and cumulative emissions due to their relevance to public health. We observed a strong linear relationship (R2 ≥ 0.80, p < 0.001) between HYDRUS-simulated and field-based maximum flux estimates and no evidence of statistical difference depending on the estimation source for maximum 24-h flux. A linear relationship of similar strength (R2 = 0.82, p < 0.001) was observed between simulated and field-based cumulative emission estimates, although mean HYDRUS estimates were lower than field-estimated values for some high-emission application methods. Analysis of simulation output demonstrated large differences in CP emissions in response to application method and a non-linear increase in CP emissions with increasing application rate, with considerable interaction between application variables including application depth, tarp types, and field layout. The findings generally support the use of simulated CP emission estimates as a tool to address gaps in field-based flux estimates, particularly where characterization of short-term peak emissions is needed.
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Blind quantum computation allows a user to delegate a computation to an untrusted server while keeping the computation hidden. A number of recent works have sought to establish bounds on the ...communication requirements necessary to implement blind computation, and a bound based on the no-programming theorem of Nielsen and Chuang has emerged as a natural limiting factor. Here we show that this constraint only holds in limited scenarios, and show how to overcome it using a novel method of iterated gate teleportations. This technique enables drastic reductions in the communication required for distributed quantum protocols, extending beyond the blind computation setting. Applied to blind quantum computation, this technique offers significant efficiency improvements, and in some scenarios offers an exponential reduction in communication requirements.
Here, we study the problem of decoding information transmitted through unknown quantum states. We assume that Alice encodes an alphabet into a set of orthogonal quantum states, which are then ...transmitted to Bob. However, the quantum channel that mediates the transmission maps the orthogonal states into non-orthogonal states, possibly mixed. If an accurate model of the channel is unavailable, then the states received by Bob are unknown. In order to decode the transmitted information we propose to train a measurement device to achieve the smallest possible error in the discrimination process. This is achieved by supplementing the quantum channel with a classical one, which allows the transmission of information required for the training, and resorting to a noise-tolerant optimization algorithm. We demonstrate the training method in the case of minimum-error discrimination strategy and show that it achieves error probabilities very close to the optimal one. In particular, in the case of two unknown pure states, our proposal approaches the Helstrom bound. A similar result holds for a larger number of states in higher dimensions. We also show that a reduction of the search space, which is used in the training process, leads to a considerable reduction in the required resources. Finally, we apply our proposal to the case of the phase flip channel reaching an accurate value of the optimal error probability.
•Phosphorus removal from water by mussel shell was assessed in batch and column tests.•The percentage of P removed increased with initial P concentration in the solution.•Calcined mussel shell ...presented a higher retention capacity than non-calcined shell.•Direct adsorption and precipitation as calcium phosphate contribute to P removal.
Mussel shell is a carbonate-rich by-product that could be recycled in wastewater treatment. In this work, phosphorus removal from aqueous solutions was obtained in a series of batch and column experiments in the laboratory, using a calcined and a finely-ground (non-calcined) mussel shell. Phosphorus removal followed a Freundlich model at high contact times (72h) and a Langmuir model at lower time (24h). Phosphorus removal capacity increased with contact time and with P concentration in the solution, while desorption of the retained P was very low (<4%). Calcined mussel shell presented a higher retention capacity than the fine shell, which can be attributed to differences in mineralogy and composition. The process of P removal from aqueous solution showed features that are typical of chemical reactions rather than denoting adsorption; concretely, the percentage of P removed increased with initial P concentration in the solution, thus pointing at a relevant role of precipitation in P removal. The results corresponding to the fractionation of the P retained in the mussel shell after the experiments showed that both mechanisms, adsorption and precipitation, contributed to P removal.
A
bstract
We show that the recently reported excess in resonant diboson production can be explained in the context of non-custodial composite Higgs models. Dibosons are generated via the s-channel ...exchange of massive vector bosons present in these models. We discuss the compatibility of the signal excess with other diboson experimental searches. We also discuss the tension between diboson production and other experimental tests of the model that include electroweak precision data, dilepton, dijet and top pair production and show that there is a region of parameter space in which they are all compatible with the excess.
As the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) pandemic continues to expand, healthcare resources globally have been spread thin. Now, the disease is rapidly spreading across ...South America, with deadly consequences in areas with already weakened public health systems. The Amazon region is particularly susceptible to the widespread devastation from Coronavirus disease 2019 (COVID-19) because of its immunologically fragile native Amerindian inhabitants and epidemiologic vulnerabilities. Herein, we discuss the current situation and potential impact of COVID-19 in the Amazon region and how further spread of the epidemic wave could prove devastating for many Amerindian people living in the Amazon rainforest.
ABSTRACT
We present the analysis of physical conditions, chemical composition, and kinematic properties of two bow shocks – HH 529 II and HH 529 III – of the fully photoionized Herbig–Haro object ...HH 529 in the Orion Nebula. The data were obtained with the Ultraviolet and Visual Echelle Spectrograph at the 8.2m Very Large Telescope and 20 yr of Hubble Space Telescope imaging. We separate the emission of the high-velocity components of HH 529 II and III from the nebular one, determining ne and Te in all components through multiple diagnostics, including some based on recombination lines (RLs). We derive ionic abundances of several ions, based on collisionally excited lines and RLs. We find a good agreement between the predictions of the temperature fluctuation paradigm (t2) and the abundance discrepancy factor (ADF) in the main emission of the Orion Nebula. However, t2 cannot account for the higher ADF found in HH 529 II and III. We estimate 6 per cent of Fe in the gas phase of the Orion Nebula, while this value increases to 14 per cent in HH 529 II and between 10 and 25 per cent in HH 529 III. We find that such increase is probably due to the destruction of dust grains in the bow shocks. We find an overabundance of C, O, Ne, S, Cl, and Ar of about 0.1 dex in HH 529 II and III that might be related to the inclusion of H-deficient material from the source of the HH 529 flow. We determine the proper motions of HH 529 finding multiple discrete features. We estimate a flow angle with respect to the sky plane of 58° ± 4° for HH 529.
The study of non-equilibrium properties in topological systems is of practical and fundamental importance. Here, we analyze the stationary properties of a two-dimensional bosonic Hofstadter lattice ...coupled to two thermal baths in the quantum open-system formalism. Novel phenomena appear like chiral edge heat currents that are the out-of-equilibrium counterparts of the zero-temperature edge currents. They support a new concept of dissipative symmetry-protection, where a set of discrete symmetries protects topological heat currents, differing from the symmetry-protection devised in closed systems and zero-temperature. Remarkably, one of these currents flows opposite to the decreasing external temperature gradient. As the starting point, we consider the case of a single external reservoir already showing prominent results like thermal erasure effects and topological thermal currents. Our results are experimentally accessible with platforms like photonics systems and optical lattices.
Fracton models provide examples of novel gapped quantum phases of matter that host intrinsically immobile excitations and therefore lie beyond the conventional notion of topological order. Here, we ...calculate optimal error thresholds for quantum error correcting codes based on fracton models. By mapping the error-correction process for bit-flip and phase-flip noises into novel statistical models with Ising variables and random multibody couplings, we obtain models that exhibit an unconventional subsystem symmetry instead of a more usual global symmetry. We perform large-scale parallel tempering Monte Carlo simulations to obtain disorder-temperature phase diagrams, which are then used to predict optimal error thresholds for the corresponding fracton code. Remarkably, we found that the X-cube fracton code displays a minimum error threshold (7.5%) that is much higher than 3D topological codes such as the toric code (3.3%), or the color code (1.9%). This result, together with the predicted absence of glass order at the Nishimori line, shows great potential for fracton phases to be used as quantum memory platforms.
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