An unprecedented synthesis of N‐heteroaromatics from biaryl aldehydes and NH3 through reagent‐free C−H/N−H cross‐coupling has been developed. The electrosynthesis uses NH3 as an inexpensive and ...atom‐economic nitrogen donor, requires no oxidizing agents, and allows efficient and regioselective access to a wide range of phenanthridines and structurally related polycyclic N‐heteroaromatic products.
It's electricfying: An unprecedented synthesis of N‐heteroaromatics from biaryl aldehydes and NH3 through reagent‐free C−H/N‐H cross‐coupling has been developed. The electrosynthesis uses NH3 as an inexpensive and atom‐economic nitrogen donor, requires no oxidizing agents, and allows efficient and regioselective access to a wide range of phenanthridines and structurally related polycyclic N‐heteroaromatic products. HFIP=1,1,1,3,3,3‐hexafluoro‐2‐propanol
Estimation of ore grade is very important for the value evaluation of ore deposits, and it directly affects the development of mineral resources. To improve the accuracy of the inverse distance ...weighting (IDW) method in ore grade estimation and reduce the smoothing effect of the IDW method in grade estimation, the weight calculation method involved in the IDW method was improved. The length parameter of the ore sample was used to calculate the weight of the IDW method. The length of the ore samples was used as a new factor of the weighting calculation. A new method of IDW integrated with sample length weighting (IDWW) was proposed. The grade estimation of Li, Al, and Fe in porcelain clay ore was used as a case study. A comparative protocol for grade estimation via the IDWW method was designed and implemented. The number of samples involved in the estimation, sample combination, sample grade distribution, and other factors affecting the grade estimation were considered in the experimental scheme. The grade estimation results of the IDWW and the IDW methods were used for comparative analysis of grades of the original and combined samples. The estimated results of the IDWW method were also compared with those of the IDW method. The deviation analysis of the estimated grade mainly included the minimum, maximum, mean, and coefficient of variation of the ore grade. The estimation effect of IDWW method was verified. The minimum deviations of the estimated grade of Li, Al, and Fe were between 9.129% and 59.554%. The maximum deviations were between 4.210 and 22.375%. The mean deviations were between - 1.068 and 7.187%. The deviations in the coefficient of variation were between 3.076 and 36.186%. The deviations in the maximum, minimum, mean, and coefficients of variation of the IDWW were consistent with those of the IDW, demonstrating the accuracy and stability of the IDWW method. The more the samples involved in the estimation, the greater the estimation deviations of IDW and IDWW methods. The estimated deviations of Li, Al, and Fe were affected by the shape of the grade distribution, when the same estimation parameters were used. The grade distribution pattern of the samples significantly influenced the grade estimation results. The IDWW method offers significant theoretical advantages and addresses the adverse effects of uneven sample lengths on the estimates. The IDWW method can effectively reduce the smoothing effect and improves the utilization efficiency of the original samples.
We report herein an atom‐economical and sustainable approach to access amidinyl radical intermediates through the anodic cleavage of N−H bonds. The resulting nitrogen‐centered radicals undergo ...cyclizations with (hetero)arenes, followed by rearomatization, to afford functionalized tetracyclic benzimidazoles in a highly straightforward and efficient manner. This metal‐ and reagent‐free C−H/N−H cross‐coupling reaction exhibits a broad substrate scope and proceeds with high chemoselectivity.
Power trip: A conceptually new method for the generation of amidinyl radicals through the anodic cleavage of N−H bonds was developed and applied to the development of aromatic C−H functionalization reactions to give benzimidazoles and pyridoimidazoles. This metal‐ and reagent‐free transformation exhibits a broad scope and proceeds with high chemoselectivity.
Resolving the low mass puzzle of Λc(2940) Luo, Si-Qiang; Chen, Bing; Liu, Zhan-Wei ...
European physical journal. C, Particles and fields,
04/2020, Letnik:
80, Številka:
4
Journal Article
Recenzirano
Odprti dostop
For the long standing low mass puzzle of
Λ
c
(
2940
)
+
, we propose an unquenched picture. Our calculation explicitly shows that the mass of the
Λ
c
(
2
P
,
3
/
2
-
)
state can be lowered down to be ...consistent with the experimental data of
Λ
c
(
2940
)
+
by introducing the
D
∗
N
channel contribution. It means that the low mass puzzle of
Λ
c
(
2940
)
+
can be solved. What is more important is that we predict a mass inversion relation for the 2
P
Λ
c
+
states, i.e., the
Λ
c
(
2
P
,
1
/
2
-
)
state is higher than the
Λ
c
(
2
P
,
3
/
2
-
)
, which is totally different from the result of conventional quenched quark model. It provides a criterion to test such an unquenched scenario for
Λ
c
(
2940
)
+
. We expect the future experimental progress from the LHCb and Belle II.
Very recently, the LHCb Collaboration at the Large Hadron Collider at CERN observed new resonance
X
(4630). The
X
(4630) is decoded as a charmoniumlike molecule with hidden-strange quantum number ...well in the one-boson-exchange mechanism. Especially, the study of its hidden-charmed decays explicitly shows the dominant role of
J
/
ψ
ϕ
among all allowed hidden-charmed decays of the
X
(4630), which enforces the conclusion of
X
(4630) as a charmoniumlike molecule. The discovery of the
X
(4630) is a crucial step of constructing charmoniumlike molecule zoo.
Inflammatory bowel disease(IBD)includes Crohn’s disease and ulcerative colitis.The exact etiology and pathology of IBD remain unknown.Available evidence suggests that an abnormal immune response ...against the microorganisms in the intestine is responsible for the disease in genetically susceptible individuals.Dysregulation of immune response in the intestine plays a critical role in the pathogenesis of IBD,involving a wide range of molecules including cytokines.On the other hand,besides T helper(Th)1 and Th2 cell immune responses,other subsets of T cells,namely Th17 and regulatory T cells,are likely associated with disease progression.Studying the interactions between various constituents of the innate and adaptive immune systems will certainly open new horizons of the knowledge about the immunologic mechanisms in IBD.
The cobalt‐catalyzed alkoxylation of C(sp2)H bonds in aromatic and olefinic carboxamides has been developed. The reaction proceeded under mild conditions in the presence of Co(OAc)2⋅4H2O as the ...catalyst and tolerates a wide range of both alcohols and benzamide substrates, including even olefinic carboxamides. In addition, this reaction is the first example of the direct alkoxylation of alkenes through CH bond activation.
Alcohols in action: A wide range of alcohols and benzamide substrates functionalized with electron‐rich or electron‐poor substituents are tolerated in the title reaction. This practical reaction occurs under mild conditions.
PDF
