Amending coherence-breaking channels via unitary operations

The coherence-breaking channels play a significant role in quantum information theory. We study the coherence-breaking channels and give a method to amend the coherence-breaking channels by applying unitary operations. For given incoherent channel $\Phi$, we give necessary and sufficient conditions for the channel to be a coherence-breaking channel and amend it via unitary operations. For qubit incoherent channels $\Phi$ that are not coherence-breaking ones, we consider the mapping $\Phi\circ\Phi$ and present the conditions for coherence-breaking and channel amendment as well.Comment: 8 page

Accelerated Computation of Free Energy Profile at ab Initio Quantum Mechanical/Molecular Mechanics Accuracy via a Semi-Empirical Reference Potential. I. Weighted Thermodynamics Perturbation

Free energy profile (FE Profile) is an essential quantity for the estimation of reaction rate and the validation of reaction mechanism. For chemical reactions in condensed phase or enzymatic reactions, the computation of FE profile at ab initio (ai) quantum mechanical/molecular mechanics (QM/MM) level is still far too expensive. Semiempirical (SE) method can be hundreds or thousands of times faster than the ai methods. However, the accuracy of SE methods is often unsatisfactory, due to the approximations that have been adopted in these methods. In this work, we proposed a new method termed MBAR+wTP, in which the ai QM/MM free energy profile is computed by a weighted thermodynamic perturbation (TP) correction to the SE profile generated by the multistate Bennett acceptance ratio (MBAR) analysis of the trajectories from umbrella samplings (US). The weight factors used in the TP calculations are a byproduct of the MBAR analysis in the post-processing of the US trajectories, which are often discarded after the free energy calculations. The results show that this approach can enhance the efficiency of ai FE profile calculations by several orders of magnitude

RAR-PINN algorithm for the data-driven vector-soliton solutions and parameter discovery of coupled nonlinear equations

This work aims to provide an effective deep learning framework to predict the vector-soliton solutions of the coupled nonlinear equations and their interactions. The method we propose here is a physics-informed neural network (PINN) combining with the residual-based adaptive refinement (RAR-PINN) algorithm. Different from the traditional PINN algorithm which takes points randomly, the RAR-PINN algorithm uses an adaptive point-fetching approach to improve the training efficiency for the solutions with steep gradients. A series of experiment comparisons between the RAR-PINN and traditional PINN algorithms are implemented to a coupled generalized nonlinear Schr\"{o}dinger (CGNLS) equation as an example. The results indicate that the RAR-PINN algorithm has faster convergence rate and better approximation ability, especially in modeling the shape-changing vector-soliton interactions in the coupled systems. Finally, the RAR-PINN method is applied to perform the data-driven discovery of the CGNLS equation, which shows the dispersion and nonlinear coefficients can be well approximated

Comparison study of U+L and Y+L working face ventilation patterns on gas control in a highly gassy mine

A mine ventilation system is an important component of an underground mining system. We all know that the ventilation system design plays an important role in highly gassy mines, and the ventilation pattern is the primary factor in gob gas control in fully mechanized working faces. Because the gas emission rate is notably large in highly gassy fully mechanized working faces and the U ventilation pattern seriously restricts normal production, a new ventilation pattern is required. This paper uses a gas flow distribution numerical simulation method to analyze the gas controlling effect of U+L and Y+L patterns. The results indicate that the gas concentration of the U+L ventilation pattern is lower than that of Y+L pattern in a fully mechanized working face and its upper corner. Furthermore, the main ventilation factors that affect the gas drainage of U+L ventilation pattern are optimized through the orthogonal test and fuzzy evaluation method; it effectively reduces the gas concentration of the upper corner and the return airway. After the implementation of the optimal solution of the U+L ventilation pattern in No. 32212(1) working face of Rujigou coal mine of Ningxia Hui Autonomous Region in China, the gas concentration of the upper corner was reduced to 0,6 %, which can ensure the normal production of the coal mine

Methyl 3-hydr­oxy-4-(3-methyl­but-2-en­yloxy)benzoate

The title compound, C13H16O4, was isolated from culture extracts of the endophytic fungus Cephalosporium sp. The ester and ether substituents are twisted only slightly out of the benzene ring plane, making dihedral angles of 2.16 (2) and 3.63 (5)°, respectively. The non-H atoms of all three substituents are almost coplanar with the benzene ring, with an r.m.s. deviation of 0.0284 Å from the mean plane through all non-H atoms in the structure. A weak intra­molecular O—H⋯O hydrogen bond contributes to this conformation. In the crystal structure, mol­ecules are linked into a one-dimensional chain by inter­molecular O—H⋯O hydrogen bonds. Weak non-classical C—H⋯π contacts are also observed in the structure

Clinical observation of macular grid photocoagulation before cataract surgery for diabetes patients with diffuse macular edema

AIM: To explore the effects and reliability of macular grid photocoagulation before cataract surgery for diabetes patients with diffuse macular edema.<p>METHODS: A total of 30 patients(40 eyes)were enrolled in the study. All the patients were randomly divided into two groups: group A: 20 eyes were treated with macular grid photocoagulation before cataract surgery; group B: 20 eyes were treated with cataract surgery only. <p>RESULTS: The patients treated with macular grid photocoagulation before cataract surgery. Postoperative visual acuity was improved, the edema of macular decreased. The patients treated with cataract surgery only, visual acuity showed no evident change and macular edema remained stable or creased. <p>CONCLUSION: Macular grid photocoagulation before cataract surgery for diabetes patients can improve the outcome and vision of the patients

1,3-Bis(chloro­meth­yl)-2-methyl-5-nitro­benzene

The title compound, C9H9Cl2NO2, is a natural product isolated from the endophytic fungus No. B77 of the mangrove tree from the South China Sea coast. In the crystal structure, the mol­ecules lie on twofold axes and form offset stacks through face-to-face π–π inter­actions. Adjacent mol­ecules in each stack are related by a centre of inversion and have an inter­planar separation of 3.53 (1) Å, with a centroid–centroid distance of 3.76 (1) Å. Between stacks, there are C—H⋯O inter­actions to the nitro groups and Cl⋯Cl contacts of 3.462 (1) Å

2,2′-(p-Phenyl­ene)bis­(4,5-dihydro-1H-imidazol-3-ium) bis­(3-nitro­benzoate)

In the title compound, C12H16N4 +·2C7H4NO4 −, the complete 2,2′-(p-phenyl­ene)bis­(4,5-dihydro-1H-imidazol-3-ium) (bib) dication is generated by crystallographic inversion symmetry. The bib cations reside on crystallographic inversion centers, which coincide with the centroids of the respective benzene rings. In the cation, the imidazole ring adopts an envelop conformation with the flap atom displaced by 0.082 (3) Å from the plane through the other ring atoms. In the crystal, the cations and anions are linked through inter­molecular N—H⋯O hydrogen bonds, forming chains running along the a axis. C—H⋯O inter­actions also occur. Weak π–π contacts between the imidazole rings of bib and between the benzene rings of NB [centroid–centroid distances = 3.501 (1) and 3.281 (2) Å, respectively] may further stabilize the structure