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Most unsteady channel flows in nature and practical engineering appear as gradually varied ones, and in the free surface, the deformation conforms to the long wave hypothesis. One-dimensional total flow models were usually used to for the numerical simulation of long-term and long-distance reaches to describe the water movements, however, the models lack a clear relationship between the three-dimensional flow field and the total flow field. Moreover, few studies of the variations of the roughness coefficient against the time in unsteady flows were conducted. The following results are obtained through the theoretical analysis and the numerical simulations in this paper. (1) One-dimensional total flow control equations of the unsteady gradually varied flow in open channels are obtained directly from the mathematical model of the viscous fluid motion, and can both reflect the influence of the turbulence and provide an explicit expression of the energy slope term. These equations establish a direct connection between the descriptions of the three-dimensional flow fields and the one-dimensional total flows. (2) Synchronous prototype observation data and planar two-dimensional numerical simulation results are used to extract the one-dimensional total flow information and discuss the total flow characteristics. (3)The orders of magnitude for terms in the total flow motion equation are compared, and the variation of the roughness coefficient against the time is analyzed.

INTRODUCTION The aim of this study was to evaluate the efficacy and safety of azithromycin (AZI) combined with glucocorticoid (GC) in the treatment of children with refractory Mycoplasma pneumoniae. METHODS Computer search for PubMed, EMbase, Cochrane Library, China Biomedical Literature Database (CBMdisc), China Knowledge Network (CNKI), Wanfang, VIP (VIP), and a randomized controlled trial (RCT) of AZI combined with GC in the treatment of children with refractory Mycoplasma pneumoniae pneumonia test (RCT), the search time limit is built until March 20, 2019. Two researchers independently performed literature screening, data extraction, and literature risk bias, and meta-analysis was performed using RevMan 5.3 software. RESULTS A total of 12 RCTs were included, including 1130 patients. Meta-analysis showed that AZI combined with GC therapy significantly improved the total effective rate of the disease compared with the conventional treatment group (odds ratio [OR] = 6.37; 95% confidence interval [CI] 4.03, 10.07; P

As glaciers melting and sea level rising, the global warming issue is drawing more and more attention all around the world. In order to maintain climatic stability, some countries and international organizations advocate an alternative measure for the proposal of border tax adjustment(BTAs) which is carbon tariff, abating greenhouse gases emissions. This article mainly analysis the potential impact of carbon tariffs on Chinese exports. And main conclusions as followed: (1) Comparing with developed countries, developing countries suffer more negative effects.(2) In all industries, Mining industry, Metal manufacturing and Chemical industry are most heavily affected if carbon tariff were to universally impose, (3)and which might reduce the profit by over 520 million dollar if carbon price set at 40 $/t.

The first example of a β-isocupreidine (β-ICD)-catalyzed highly enantioselective [2+2] annulation of allenoates with trifluoromethyl ketones has been disclosed, allowing the synthesis of optically active 2-alkyleneoxetanes in moderate to good yields along with good to high enantioselectivities and high diastereoselectivities. Further transformations of the cycloadducts have been also disclosed to afford biologically interesting 6-trifluoromethyl-5,6-dihydropyran-2-ones and trifluoromethyl β-keto acids in good yields.

4-(N,N-dimethylamino)pyridine (DMAP) was found to be a fairly efficient catalyst for the Morita–Baylis–Hillman reactions of isatins with α-substituted allenoates to give the corresponding products in good to high yields with moderate diastereoselectivities under mild conditions.

We found that nitrogen-containing Lewis base mediated [4+2] annulation of but-3-yn-2-one with activated ketones could proceed efficiently to give the corresponding 2,3-dihydropyran-4-ones in moderate to good yields under mild conditions. The substrate scope has been carefully examined. Moreover, a plausible reaction mechanism for the [4+2] annulation of but-3-yn-2-one with activated ketones mediated by DABCO has been proposed on the basis of previous literature and our own investigations.

Asymmetric annulation of allenes with electron-deficient olefins and imines is one of the most important reactions for the synthesis of optically active carbo- and heterocycles, which are useful building blocks for the synthesis of natural products and medicinally important substances. The use of chiral phosphines as enantioselective catalysts can be envisaged for such cyclizations. This article focuses on the important developments concerning asymmetric annulations of allenes with unsaturated partners in the recent decades and on the perspectives that these new developments offer.

The 1,4-diazabicyclic[2.2.2]octane (DABCO)-catalyzed intermolecular Rauhut-Currier reaction of maleimides with electron-deficient allenes has been investigated, affording the corresponding products in good to high yields under mild conditions. The first example of a β-isocupreidine (β-ICD)-catalyzed highly enantioselective intermolecular Rauhut-Currier reaction of maleimides with allenoates and penta-3,4-dien-2-one has been also developed, allowing the synthesis of optically active functionalized allene derivatives in good to high yields along with good to excellent enantioselectivities.

Axially chiral phosphine–oxazoline ligand L6 was found to be a fairly effective chiral ligand in silver(I)-catalyzed asymmetric Mannich reaction of N -Boc aldimines with trimethylsiloxyfuran to give the corresponding adducts in up to 97% yield, 7:1 dr and 86% ee (major diastereoisomer).

A highly regio- and enantioselective asymmetric vinylogous Mannich reaction of readily available fluorinated aldimines bearing a chiral auxiliary [(S)-1-phenylethyl group] with siloxyfurans to afford chiral fluorine-containing γ-butenolide or γ-lactone derivatives has been developed in the presence of silver acetate (10 mol%) and axially chiral phosphine-oxazoline ligand L1 (11 mol%). In most cases, the corresponding fluorinated adducts were obtained in high yields, good to excellent enantiomeric excesses and up to > 20:1 dr.

Axially chiral phosphine–oxazoline ligand L7 , prepared from ( S )-binol, was found to be a fairly effective chiral ligand in the silver(I)-catalyzed asymmetric Mannich reaction of fluorinated aldimines with trimethylsiloxyfuran to give the corresponding adducts in up to 99% yield, over 20:1 dr and 81% ee.

(E)-Alkenyloxetanes are obtained with good to high enantioselectivities by use of β-isocupreidine ICP as catalyst.

4-(N,N-dimethylamino)pyridine (DMAP) was found to be a fairly efficient catalyst for the Morita–Baylis–Hillman reactions of isatins with α-substituted allenoates to give the corresponding products in good to high yields with moderate diastereoselectivities under mild conditions.

We found that nitrogen-containing Lewis base mediated [4+2] annulation of but-3-yn-2-one with activated ketones could proceed efficiently to give the corresponding 2,3-dihydropyran-4-ones in moderate to good yields under mild conditions. The substrate scope has been carefully examined. Moreover, a plausible reaction mechanism for the [4+2] annulation of but-3-yn-2-one with activated ketones mediated by DABCO has been proposed on the basis of previous literature and our own investigations.

D-Threonine-L-tert-leucine-derived bifunctional phosphine, Cat. 11, catalyzed highly enantioselective [3+2] annulation of maleimides with allenes has been disclosed, allowing the synthesis of optically active functionalized bicyclic cyclopentenes containing two tertiary stereogenic centers in good to high yields along with good to high enantioselectivities.

Asymmetric annulation of allenes with electron-deficient olefins and imines is one of the most important reactions for the synthesis of optically active carbo- and heterocycles, which are useful building blocks for the synthesis of natural products and medicinally important substances. The use of chiral phosphines as enantioselective catalysts can be envisaged for such cyclizations. This article focuses on the important developments concerning asymmetric annulations of allenes with unsaturated partners in the recent decades and on the perspectives that these new developments offer.

In the presence of the quinidine-derived β-isocupreidine as organocatalyst, the products are obtained with good to high e.e.

D-Threonine-L-tert-leucine-derived bifunctional phosphine, Cat. 11, catalyzed highly enantioselective [3+2] annulation of maleimides with allenes has been disclosed, allowing the synthesis of optically active functionalized bicyclic cyclopentenes containing two tertiary stereogenic centers in good to high yields along with good to high enantioselectivities.

A highly regio- and enantioselective asymmetric vinylogous Mannich reaction of readily available fluorinated aldimines bearing a chiral auxiliary [(S)-1-phenylethyl group] with siloxyfurans to afford chiral fluorine-containing γ-butenolide or γ-lactone derivatives has been developed in the presence of silver acetate (10 mol%) and axially chiral phosphine-oxazoline ligand L1 (11 mol%). In most cases, the corresponding fluorinated adducts were obtained in high yields, good to excellent enantiomeric excesses and up to > 20:1 dr.