Enantioselective Synthesis of Axially Chiral Diaryl Ethers via NHC Catalyzed Desymmetrization and Following Resolution.

Axially chiral diaryl ethers are present in numerous natural products and bioactive molecules. However, only few catalytic enantioselective approaches have been established to access diaryl ether atropisomers. Herein, we report the N-heterocyclic carbene-catalyzed enantioselective synthesis of axially chiral diaryl ethers via desymmetrization of prochiral 2-aryloxyisophthalaldehydes with aliphatic alcohols, phenol derivatives, and heteroaromatic amines. This reaction features mild reaction conditions, good functional group tolerance, broad substrate scope and excellent enantioselectivity. The utility of this methodology is illustrated by late-stage functionalization, gram-scale synthesis, and diverse enantioretentive transformations. Control experiments and DFT calculations support the association of NHC-catalyzed desymmetrization with following kinetic resolution to enhance the enantioselectivity.

Dependences of Magnetic Properties on the Grain Size and Hard/Soft Magnetic Phase Volume Ratio for Ce2Fe14B/α-Fe and Nd2Fe14B/α-Fe Nanocomposites.

The magnetic properties of magnetic nanocomposites consisting of hard and soft magnetic phases are dependent not only on the intrinsic properties but also on the grain structure and volume ratio of the two phases. In this study, we performed a systematic micromagnetic simulation on the magnetic properties of Ce2Fe14B/α-Fe and Nd2Fe14B/α-Fe nanocomposites. The volume fractions of the hard magnetic Nd2Fe14B or Ce2Fe14B phase were varied from 80% to 40%, and the grain sizes of the hard magnetic phase and the soft magnetic α-Fe phase were changed independently from 10 nm to 40 nm. The results show that when the grain size of both hard and soft phases is 10 nm and the volume fraction of the hard phase is 70%, the highest maximum magnetic energy product can be obtained in both Ce2Fe14B/α-Fe and Nd2Fe14B/α-Fe nanocomposites. The hard magnetic properties of Ce2Fe14B/α-Fe nanocomposite decrease significantly when the volume fraction of the α-Fe phase exceeds 30%. However, for the Nd2Fe14B/α-Fe system, this situation only occurs when the α-Fe volume fraction exceeds 40%. The reason for this is not only because of the low anisotropic field and the smaller exchange coupling length between the soft and hard magnetic phases, but also because of the lower saturation magnetization of the hard phase. The grain size has greater effects on the magnetic properties compared to the volume fraction of the hard magnetic phase. The main reason is that as the grain size increases, the remanence of the nanocomposite decreases sharply, which also leads to a rapid decrease in the maximum magnetic energy product. The simulation results on the effects of phase ratio and grain size have been verified by experiments on melt-spun Ce2Fe14B/α-Fe alloys with various compositions prepared by melt-spinning followed by annealing for various lengths of time. Due to the influence of demagnetization energy, the hard magnetic phase with high saturation magnetization is preferred for the preparation of high-performance nanocomposite magnets.

Inhomogeneity of the Backward Extruded NdFeB Ring Magnet Prepared from Amorphous Powders.

Back extrusion is an important process to prepare radially oriented NdFeB ring magnets. In this work, we fabricate the ring magnets using amorphous magnetic powders as the raw material. The microstructure, magnetic properties, corrosion resistance, and mechanical properties of the backward extruded magnet at different positions along the axial direction have been investigated, and the inhomogeneity of the magnet is clarified. The results showed that the grains in the middle region of the ring magnet exhibit a strong c-axis orientation, whereas the grains at the bottom and top regions are disordered with random orientation. The microstructure variation is related to the distribution of the grain boundary phase and the degree of grain deformation. Due to the microstructure difference, the magnetic properties, temperature stability, corrosion resistance, and mechanical properties in the middle region of the magnet are higher than those in the top and bottom regions. The exchange coupling between grains also varies in different regions, which is related to the grain size and grain boundary thickness. In addition, different Co element segregations were observed in different regions, which has a crucial effect on the Curie temperature and thermal stability of the magnet. The microstructure difference also leads to the variation of corrosion resistance and mechanical properties for the samples from different regions of the magnet. This work suggests that the amorphous powder can be used to directly prepare radially oriented ring magnets, and the inhomogeneity of the magnet should be fully understood.

Ketones from aldehydes via alkyl C(sp3)-H functionalization under photoredox cooperative NHC/palladium catalysis.

Direct synthesis of ketones from aldehydes features high atom- and step-economy. Yet, the coupling of aldehydes with unactivated alkyl C(sp3)-H remains challenging. Herein, we develop the synthesis of ketones from aldehydes via alkyl C(sp3)-H functionalization under photoredox cooperative NHC/Pd catalysis. The two-component reaction of iodomethylsilyl alkyl ether with aldehydes gave a variety of ß-, γ- and δ-silyloxylketones via 1,n-HAT (n = 5, 6, 7) of silylmethyl radicals to generate secondary or tertiary alkyl radicals and following coupling with ketyl radicals from aldehydes under photoredox NHC catalysis. The three-component reaction with the addition of styrenes gave the corresponding ε-hydroxylketones via the generation of benzylic radicals by the addition of alkyl radicals to styrenes and following coupling with ketyl radicals. This work demonstrates the generation of ketyl radical and alkyl radical under the photoredox cooperative NHC/Pd catalysis, and provides two and three component reactions for the synthesis of ketones from aldehydes with alkyl C(sp3)-H functionalization. The synthetic potential of this protocol was also further illustrated by the late-stage functionalization of natural products.

Magnetic properties and rare earth element diffusion behavior of hot-deformed nanocrystalline dual-main-phase Nd-Ce-Fe-B magnets.

To inhibit the magnetic dilution effect of Ce in Nd-Ce-Fe-B magnets, a dual-alloy method is employed to prepare hot-deformed dual-main-phase (DMP) magnets using mixed nanocrystalline Nd-Fe-B and Ce-Fe-B powders. A REFe2 (1 : 2, where RE is a rare earth element) phase can only be detected when the Ce-Fe-B content exceeds 30 wt%. The lattice parameters of the RE2Fe14B (2 : 14 : 1) phase exhibit non-linear variation with the increasing Ce-Fe-B content due to the mixed valence states of Ce ions. Owning to inferior intrinsic properties of Ce2Fe14B compared to Nd2Fe14B, the magnetic properties of DMP Nd-Ce-Fe-B magnets almost decrease with the increase of Ce-Fe-B addition, but interestingly, the magnet with 10 wt% Ce-Fe-B addition exhibits an abnormally increased intrinsic coercivity H cj of 1215 kA m-1, together with the higher temperature coefficients of remanence (α = -0.110%/K) and coercivity (ß = -0.544%/K) in the temperature range of 300-400 K than the single-main-phase (SMP) Nd-Fe-B magnet with H cj = 1158 kA m-1, α = -0.117%/K and ß = -0.570%/K. The reason may be partly attributed to the increase of Ce3+ ions. Different from the Nd-Fe-B powders, the Ce-Fe-B powders in the magnet are difficult to deform into a platelet-like shape because of the lack of low melting point RE-rich phase due to the precipitation of the 1 : 2 phase. The inter-diffusion behavior between the Nd-rich region and Ce-rich region in the DMP magnets has been investigated by microstructure analysis. The significant diffusion of Nd and Ce into Ce-rich and Nd-rich grain boundary phases, respectively, was demonstrated. At the same time, Ce prefers to stay in the surface layer of Nd-based 2 : 14 : 1 grains, but less Nd diffuses into Ce-based 2 : 14 : 1 grains due to the 1 : 2 phase presented in the Ce-rich region. The modification of the Ce-rich grain boundary phase by Nd diffusion and the distribution of Nd in the Ce-rich 2 : 14 : 1 phase are beneficial for magnetic properties.

Dual-response and lysosome-targeted fluorescent probe for viscosity and sulfur dioxide derivatives.

Viscosity and sulfur dioxide levels are important factors to evaluate the changes of cell micro-environment because a series of diseases usually occur when they are abnormal. At present, dual-response probes that can detect both viscosity and sulfur dioxide are rare. Therefore, we developed a novel fluorescent probe CBN for simultaneous detection of sulfur dioxide and viscosity. Besides, probe CBN could target lysosome of which normal function will be disrupted by the abnormality of viscosity. Therefore, probe CBN has the potential to be served as an effective biological tool to monitor the intracellular micro-environment.

Two-dimensional shear wave elastography with two different systems for the diagnosis of breast lesions.

BACKGROUND: Two-dimensional (2D) - shear wave elastography (SWE) has made promising advances in the diagnostic of breast lesions. However, few studies have assessed whether the diagnostic effectiveness of different platforms employing 2D-SWE is equal or different. OBJECTIVE: To compare the diagnostic effectiveness of 2D-SWE techniques from two different systems in differentiating malignant breast lesions from benign ones. METHODS: A total of 84 breast lesions were retrospectively analyzed by experienced radiologists using 2D-SWE on two ultrasound systems, i.e. system-1 (LOGIQ E9 system, GE Healthcare, Wauwatosa, WI, USA), and system-2 (Aixplorer US system, SuperSonic Imagine, Aix-en-Provence, France). Qualitative and quantitative parameters including color sign, the maximum elasticity modulus values (E-max), the mean elasticity modulus values (E-mean) and standard deviation (E-sd) of elasticity modulus values in two 2D-SWE systems were analyzed. The diagnostic performance between system-1 and system-2 were evaluated in terms of the areas under the receiver operating characteristic curves (AUROCs). RESULTS: Among the 84 lesions in this study, 66 (78.6%) were benign and 18 (21.4%) were malignant. E-max in system-1 showed the best diagnostic performance with a cut-off value of 174.5 kPa with the associated sensitivity and specificity of 100.0% and 80.3% respectively. Meanwhile, E-sd in system-2 displayed the best diagnostic performance with a cut-off value of 12.7 kPa, with the associated sensitivity and specificity of 94.4% and 80.3% respectively. The diagnostic performance of the two 2D-SWE systems was not statistically different according to receiver operating characteristic curve (ROC) analysis of E-max, E-mean, and E-sd. CONCLUSION: For identifying breast lesions, system-1 and system-2 appear to be similar in diagnostic performance. However, different cut-off values for different parameters might be selected to obtain the best diagnostic performance for the two 2D-SWE systems.

Enantioselective Synthesis of Axially Chiral Benzothiophene/Benzofuran-Fused Biaryls by N-Heterocyclic Carbene Catalyzed Arene Formation.

Axially chiral biaryl scaffolds are prevalent in natural products, chiral ligands, and organocatalysts. However, N-heterocyclic carbene (NHC) catalyzed de novo construction of an aromatic ring with concomitant axial chirality induction for the synthesis of biaryl atropisomers is far less developed, and the efficient synthesis of axially chiral tetra-ortho-substituted biaryls remains an unsolved problem under NHC catalysis. Reported here is an NHC-catalyzed de novo synthesis of axially chiral benzothiophene/benzofuran-fused biaryls from enals and 2-benzyl-benzothiophene/benzofuran-3-carbaldehydes through a [2+4] annulation, decarboxylation, and oxidative aromatization cascade with central-to-axial chirality conversion. The developed method provides efficient and general access to novel axially chiral benzothiophene/benzofuran-fused biaryls in high enantioselectivities and works well for the synthesis of tetra-ortho-substituted biaryls.

[Effect of Ni(â ¡) on Anaerobic Ammonium Oxidation and Changes in Kinetics].

Anaerobic ammonium oxidation (ANAMMOX) is widely used for treatment of ammonium-rich wastewater because of its economic and environmental benefits. However, ANAMMOX bacteria are sensitive to environmental conditions, especially to heavy metals. The short-term and long-term effects of Ni(Ⅱ) on ANAMMOX were studied by batch and continuous flow experiments, respectively. Results showed that low concentrations of Ni(Ⅱ) had promoted nitrogen removal by ANAMMOX and high concentrations inhibited ANAMMOX performance during a short-term period. Compared with the specific anaerobic ammonium oxidation activity (SAA) without Ni(Ⅱ) addition, SAA with 1 mg·L-1 Ni(Ⅱ) addition increased by 11.14% and the SAA with 100 mg·L-1 Ni(Ⅱ) addition reduced by 49.55%. The IC50 of Ni(Ⅱ) for ANAMMOX was determined to be 83.86 mg·L-1. In contrast, long-term Ni(Ⅱ) addition significantly suppressed nitrogen removal of ANAMMOX, and the suppression threshold of Ni(Ⅱ) on ANAMMOX was 15 mg·L-1. The Monod model was applied to simulate the kinetics of ANAMMOX without Ni(Ⅱ) addition. The qmax0(TN/VSS) and KS0 values were 12.25 mg·(g·h)-1 and 405.36 mg·L-1, respectively. The modified Haldane model was suitable to describe the kinetics of ANAMMOX with 50 mg·L-1 Ni(Ⅱ) addition. The qmax(TN/VSS), KS, and Ki values were 6.78 mg·(g·h)-1, 313.2 mg·L-1, and 1.32, respectively. The inhibition of ANAMMOX by Ni(Ⅱ) is anticompetitive inhibition. In addition, the inhibition of Ni(Ⅱ) on ANAMMOX was mainly related to the content of intracellular Ni(Ⅱ). The IC50intracellular Ni(Ⅱ)(VSS) of intracellular Ni(Ⅱ) was 0.072 mg·g-1.

Last Patents on Bubble Electrospinning.

Due to their unique properties, nanofibers have been widely used in various areas, for example, information industry, pharmaceutical application, environmental industry, textile and clothing, etc. Bubble electrospinning is one of the most important non-needle electrospinning methods for nanofiber fabrication. It usually uses polymer bubbles for the production of nanomaterials by using electrostatic force, flowing air or mechanical force to overcome the surface tension of bubbles. Bubble electrospinning mainly includes bubble electrospinning and blown bubble electrospinning. History of the development of bubble electrospinning is briefly introduced in this article, and the most promising patents on the technology are elucidated. The methods of bubble electrospinning are single bubble electrospinning, porous bubble electrospinning, blown bubble electrospinning, electrostatic-fieldassisted blown bubble spinning and others. These different bubble electrospinning methods are also discussed in this paper.

NBE-Controlled Palladium-Catalyzed Interannular Selective C-H Silylation: Access to Divergent Silicon-Containing 1,1'-Biaryl-2-Acetamides.

A novel palladium-catalyzed interannular selective C-H silylation of 1,1'-biaryl-2-acetamides is described. The combination of palladium catalyst with copper oxidant enables meta- or ortho-selective C-H silylation by employing hexamethyldisilane as a trimethylsilyl source, which relies on the control of NBE derivatives as a switch, thus providing straightforward access to divergent silicon-containing 1,1'-biaryl-2-acetamides.

Three-dimensional shear wave elastography for differentiation of breast lesions: An initial study with quantitative analysis using three orthogonal planes.

OBJECTIVES: To prospectively evaluate the diagnostic performance of three-dimensional (3D) shear wave elastography (SWE) for breast lesions with quantitative stiffness information from transverse, sagittal and coronal planes. METHODS: Conventional ultrasound (US), two-dimensional (2D)-SWE and 3D-SWE were performed for 122 consecutive patients with 122 breast lesions before biopsy or surgical excision. Maximum elasticity values of Young's modulus (Emax) were recorded on 2D-SWE and three planes of 3D-SWE. Area under the receiver operating characteristic curve (AUC), sensitivity and specificity of US, 2D-SWE and 3D-SWE were evaluated. Two combined sets (i.e., BI-RADS and 2D-SWE; BI-RADS and 3D-SWE) were compared in AUC. Observer consistency was also evaluated. RESULTS: On 3D-SWE, the AUC and sensitivity of sagittal plane were significantly higher than those of transverse and coronal planes (both P < 0.05). Compared with BI-RADS alone, both combined sets had significantly (P < 0.05) higher AUCs and specificities, whereas, the two combined sets showed no significant difference in AUC (P > 0.05). However, the combined set of BI-RADS and sagittal plane of 3D-SWE had significantly higher sensitivity than the combined set of BI-RADS and 2D-SWE. CONCLUSIONS: The sagittal plane shows the best diagnostic performance among 3D-SWE. The combination of BI-RADS and 3D-SWE is a useful tool for predicting breast malignant lesions in comparison with BI-RADS alone.

A radical cyclization cascade of 2-alkynylbenzonitriles with sodium arylsulfinates.

A convenient radical cyclization cascade procedure for the construction of sulfonated indenones from 2-alkynylbenzonitriles and sodium arylsulfinates has been explored under mild reaction conditions. The present methodology offers a low-cost and operationally straightforward approach to synthesizing various sulfonated indenones in moderate to good yields by simple use of cheap sodium persulfate as an oxidant and environmentally benign water as a co-solvent.

Palladium-Catalyzed Synthesis of Triphenylenes via Sequential C-H Activation and Decarboxylation.

A novel tandem intermolecular decarboxylative coupling reaction of o-bromobenzoic acids and aryl iodides has been developed. The method affords a range of unsymmetrically triphenylenes and displays unique regioselectivity and broad substrate scope. Mechanistically, palladium/norbornene-catalyzed C-H activation and subsequent double decarboxylative coupling reactions were involved. Moreover, the triphenylenes can also be synthesized from 2-iodobiphenyls and o-bromobenzoic acids under norbornene-free conditions.

Two-dimensional shear wave elastography for differential diagnosis between mastitis and breast malignancy.

OBJECTIVE: To determine the diagnostic performance of conventional ultrasound (US) and two-dimensional shear wave elastography (2D SWE) in the differential diagnosis between mastitis and breast malignancy. METHODS: Between January 2016 and March 2017, 105 patients with 105 pathologically proven breast lesions were enrolled. All the lesions were subject to conventional US and 2D SWE examinations. In 2D SWE, the qualitative parameter of stiff rim sign and quantitative parameter of maximal shear wave velocity (SWV) were obtained. The diagnosis performances of US and combination of US and 2D SWE were evaluated, including sensitivity, specificity and the area under the receiver operating characteristic curve (AUROC). The AUROC of US and the combined method were also evaluated in subgroups with different diameters. RESULTS: Pathologically, 26 breast lesions were confirmed to be mastitis and 79 were malignant. The cut-off value for maximal SWV was 6.75 m/sec. The AUROC of stiff rim sign and maximal SWV were 0.701 (95% CI: 0.587-0.815) and 0.753 (95% CI: 0.659-0.832) respectively. Compared with US, the specificity and AUROC of the combined method increased significantly (specificity: 11.5% vs. 96.1%, AUROC: 0.520 vs. 0.752; both P < 0.05). CONCLUSIONS: The combination of US and 2D SWE improved the diagnostic performance in the differential diagnosis between mastitis and breast malignancy in comparison with the conventional US alone.

Value of shear wave arrival time contour display in shear wave elastography for breast masses diagnosis.

To evaluate the diagnostic performance of shear wave arrival time contour (SWATC) display for the diagnosis of breast lesions and to identify factors associated with the quality of shear wave propagation (QSWP) in breast lesions. This study included 277 pathologically confirmed breast lesions. Conventional B-mode ultrasound characteristics and shear wave elastography parameters were computed. Using the SWATC display, the QSWP of each lesion was assigned to a two-point scale: score 1 (low quality) and score 2 (high quality). Binary logistic regression analysis was performed to identify factors associated with QSWP. The area under the receiver operating characteristic curve (AUROC) for QSWP to differentiate benign from malignant lesions was 0.913, with a sensitivity of 91.9%, a specificity of 90.7%, a positive predictive value (PPV) of 74.0%, and a negative predictive value (NPV) of 97.5%. Compared with using the standard deviation of shear wave speed (SWSSD) alone, SWSSD combined with QSWP increased the sensitivity from 75.8% to 93.5%, but decreased the specificity from 95.8% to 89.3% (P < 0.05). SWSSD was identified to be the strongest factor associated with the QSWP, followed by tumor malignancy and the depth of the lesion. In conclusion, SWATC display may be useful for characterization of breast lesions.

Replication of a pathogenic non-coding RNA increases DNA methylation in plants associated with a bromodomain-containing viroid-binding protein.

Viroids are plant-pathogenic molecules made up of single-stranded circular non-coding RNAs. How replicating viroids interfere with host silencing remains largely unknown. In this study, we investigated the effects of a nuclear-replicating Potato spindle tuber viroid (PSTVd) on interference with plant RNA silencing. Using transient induction of silencing in GFP transgenic Nicotiana benthamiana plants (line 16c), we found that PSTVd replication accelerated GFP silencing and increased Virp1 mRNA, which encodes bromodomain-containing viroid-binding protein 1 and is required for PSTVd replication. DNA methylation was increased in the GFP transgene promoter of PSTVd-replicating plants, indicating involvement of transcriptional gene silencing. Consistently, accelerated GFP silencing and increased DNA methylation in the of GFP transgene promoter were detected in plants transiently expressing Virp1. Virp1 mRNA was also increased upon PSTVd infection in natural host potato plants. Reduced transcript levels of certain endogenous genes were also consistent with increases in DNA methylation in related gene promoters in PSTVd-infected potato plants. Together, our data demonstrate that PSTVd replication interferes with the nuclear silencing pathway in that host plant, and this is at least partially attributable to Virp1. This study provides new insights into the plant-viroid interaction on viroid pathogenicity by subverting the plant cell silencing machinery.

Identification and validation of AIB1 and EIF5A2 for noninvasive detection of bladder cancer in urine samples.

We previously demonstrated that amplified in breast cancer 1 (AIB1) and eukaryotic initiation factor 2 (EIF5A2) overexpression was an independent predictor of poor clinical outcomes for patients with bladder cancer (BCa). In this study, we evaluated the usefulness of AIB1 and EIF5A2 alone and in combination with nuclear matrix protein 22 (NMP22) as noninvasive diagnostic tests for BCa. Using urine samples from 135 patients (training set, controls [n = 50] and BCa [n = 85]), we detected the AIB1, EIF5A2, and NMP22 concentrations using enzyme-linked immunosorbent assay. We applied multivariate logistic regression analysis to build a model based on the three biomarkers for BCa diagnosis. The diagnostic accuracy of the three biomarkers and the model were assessed and compared by the area under the curve (AUC) of the receiver operating characteristic. We validated the diagnostic accuracy of these biomarkers and the model in an independent validation cohort of 210 patients. In the training set, urinary concentrations of AIB1, EIF5A2, and NMP22 were significantly elevated in BCa. The AUCs of AIB1, EIF5A2, NMP22, and the model were 0.846, 0.761, 0.794, and 0.919, respectively. The model had the highest diagnostic accuracy when compared with AIB1, EIF5A2, or NMP22 (p < 0.05 for all). The model had 92% sensitivity and 92% specificity. We obtained similar results in the independent validation cohort. AIB1 and EIF5A2 show promise for the noninvasive detection of BCa. The model based on AIB1, EIF5A2, and NMP22 outperformed each of the three individual biomarkers for detecting BCa.

Does chromophobe renal cell carcinoma have better survival than clear cell renal cell carcinoma? A clinical-based cohort study and meta-analysis.

BACKGROUND: It is controversial whether chromophobe renal cell carcinoma (chRCC) or clear cell renal cell carcinoma (ccRCC) is associated with better survival. We conducted a clinical-based cohort study and meta-analysis to evaluate the prognostic role of histology between chRCC and ccRCC. METHODS: A cohort of 1540 patients (166 with chRCC and 1374 with ccRCC) were selected from Sun Yat-sen University and The Cancer Genome Atlas databases. The clinicopathological parameters and overall survival (OS) were compared between patients with chRCC and those with ccRCC. For the meta-analysis, we searched the PubMed, Cochrane Library, and Ovid databases for studies comparing OS or cancer-specific survival (CSS) between chRCC and ccRCC. RESULTS: The cohort study revealed that patients with chRCC were younger (median 52 vs. 55 years, P < 0.001), were more commonly female (47.0 vs. 33.0%, P < 0.001), and had a larger tumor size (mean 7.1 vs. 5.9 cm, P < 0.001), and they had a lower stage compared with those with ccRCC. Five-year OS rates for chRCC and ccRCC were 90.3 and 75.3%, respectively (P < 0.001). We found significantly better survival for chRCC in stratification analysis by age, sex, tumor size, and stage. Similar results were observed on both univariate [hazard ratio (HR), 0.30; 95% confidence interval (CI) 0.16-0.55, P < 0.001] and multivariate analyses (HR 0.42; 95% CI 0.23-0.79, P = 0.006). Ten studies were included in our meta-analysis. Eight of them provided data on univariate analysis. The pooled HR was statistically significant for OS (pooled HR 0.49; 95% CI 0.30-0.79, P = 0.004) and CSS (pooled HR 0.49; 95% CI 0.37-0.64, P < 0.001). Seven studies reported the HR on multivariate analysis. The pooled HR was also statistically significant for OS (pooled HR 0.63; 95% CI 0.51-0.77, P < 0.001) and CSS (pooled HR 0.72; 95 % CI 0.57-0.90, P = 0.003). These data indicate that patients with chRCC had better outcomes than those with ccRCC. CONCLUSIONS: Our large cohort study and meta-analysis confirmed that chRCC had better survival than ccRCC.