Search

The Nanpanjiang basin hosts the world's second-largest concentration of Carlin-type gold deposits. To decipher the origin and evolution of hydrothermal fluid, this study conducted Sm–Nd dating, in-situ trace element, and C-O-Sr isotopic analyses on three types of calcite samples from the giant Lannigou gold deposit in the Nanpanjiang basin, SW China. The type-I calcite, intergrown with Au-bearing arsenian pyrite, has an Sm–Nd isochron age of 213 ± 7 Ma (MSWD = 0.81), indicating that gold mineralization occurred in Late Triassic. The type-II calcite, which coexists with high-maturity bitumens and cut through the main-stage gold orebodies, yields an Sm–Nd age of 188 ± 14 Ma (MSWD = 0.34), representing a post-ore hydrocarbon accumulation event. The type-I and type-II calcite samples have low REE contents (5.28–51.6 ppm) and exhibit MREE-enriched and LREE-/HREE-depleted patterns. Combined with their identical C-O-Sr isotopes, we suggest that hydrothermal fluids responsible for the precipitation of type-I and type-II calcite samples were derived from a mixed metamorphic fluid and meteoric water source. In contrast, the type-III calcite samples, associated with realgar and orpiment, have distinct Mn, Sr, and As contents, REE patterns, and C-O-Sr isotopic composition from the type-I and II calcites, suggestive of different fluid sources. Based on our and previously published data, we propose that the fluid evolution, gold mineralization, and hydrocarbon accumulation in the Nanpanjiang basin are closely related to the Indosinian and Yanshanian orogenies in South China. [ABSTRACT FROM AUTHOR]

Recently, the second coordination sphere effect has been successfully exploited to modulate the catalytic behavior of late-transition metal catalysts in olefin insertion polymerization. In this study, four bulky iminopyridyl Ni(II) and Pd(II) complexes that contain naphthalene or benzothiophene groups were firstly prepared and their applications in olefin oligomerization were also investigated. The as-prepared nickel and palladium complexes generally displayed good catalytic activity in ethylene oligomerization, providing hyperbranched oligomers with various microstructures. Notably, the molecular weights of the ethylene oligomers generated by the benzothiophene-based Ni(II)/Pd(II) complexes were significantly lower than those generated by the naphthalene-based complexes. In addition, these palladium complexes could catalyze the co-oligomerization of ethylene and MA, yielding hyperbranched co-oligomers with tunable incorporation ratios of MA. Moreover, for ethylene oligomerization catalyzed by nickel complexes, toluene-end-functionalized branched ethylene oligomers were formed via Friedel–Crafts addition of the resulting unsaturated ethylene oligomers to the toluene solvent. In this work, we found that the second coordination sphere effect of benzothiophene could facilitate chain transfer in iminopyridyl Ni(II)/Pd(II)-catalyzed ethylene (co)oligomerization, in contrast to the phenomenon observed in the corresponding α-diimine system. [ABSTRACT FROM AUTHOR]

In this study, a series of partially chain-straightened propylene oligomers and functional propylene–methyl acrylate (P-MA) co-oligomers were synthesized with 8-alkyl-iminopyridyl Pd(II) catalysts. The molecular weight and polar monomer incorporation ratio could be tuned by using Pd(II) catalysts with various 8-alkyl-naphthyl substituents (8-alkyl: H, Me, and n-Bu). In propylene oligomerization, all the 8-alkyl-iminopyridyl Pd(II) catalysts convert propylene to partially chain-straightened (119–136/1000 C) oligomers with low molecular weights (0.3–1.5 kg/mol). Among the catalysts, Pd1 with non-substituent (H) on the ligand showed the highest activity of 5.4 × 104 g/((mol of Pd) h), generating oligomers with the lowest molecular weight (Mn: 0.3 kg/mol). Moreover, polar-functionalized propylene-MA co-oligomers with very high incorporation ratios (22.8–36.5 mol %) could be obtained in the copolymerization using these 8-alkyl-iminopyridyl Pd(II) catalysts. Additionally, Pd1 exhibited the best performance in propylene-MA copolymerization as it displayed the highest MA incorporation ratio of up to 36.5 mol%. All the three catalysts are capable of generating partially chain-straightened P-MA co-oligomers and the activities decrease gradually while the molecular weight increases with the increasing steric hindrance of the alkyl substituent (H < Me < n-Bu). Compared to Pd4 with the rigid 8-aryl substituent, the flexible 8-alkyl-iminopyridyl Pd(II) catalysts (Pd1-3) not only showed much higher activities in the propylene oligomerization, but also yielded P-MA co-oligomers with significantly higher incorporation ratios in the propylene co-oligomerization. [ABSTRACT FROM AUTHOR]

The synthesis of hyper‐branched ethene oligomers through catalytic insertion reactions with late transition metal catalysts is unique in its synthetic and practical scope. In this study, a series of iminopyridyl Ni(II) and Pd(II) complexes with electron‐rich distal aryl motifs were synthesized and characterized. These complexes were very efficient in ethene oligomerization and co‐oligomerization with methyl acrylate (MA). Hyperbranched ethene oligomers with different microstructures were generated using different metal species in ethene oligomerization. More importantly, hyperbranched ethene‐MA co‐oligomers with varying incorporation ratios were generated via ethene and MA co‐oligomerization using the Pd(II) complexes. Most notably, weak neighboring group interactions of distal aryl motifs in the nickel system are more effective in influencing the microstructure of ethene oligomers than the corresponding palladium system. [ABSTRACT FROM AUTHOR]

Low accuracy is the main challenge that plagues the application of engine modeling technology at present. In this paper, correlation analysis technology is used to analyze the main influencing factors of engine torque and NOx (nitrogen oxides) raw emission performance from a statistical point of view, and on this basis, the regression algorithm is used to construct the engine torque and NOx emission prediction model. The prediction RMSE between engine torque prediction value and true value reaches 4.6186, and the torque prediction R2 reaches 1.00. Prediction RMSE between NOx emission prediction value and true value reaches 67.599, and NOx emission prediction R2 reaches 0.99. When using the new WHTC data for model prediction verification, the RMSE between the engine torque predicted value and true value reaches 4.9208, and the prediction accuracy reaches 99.60%, the RMSE between NOx emission prediction value and true value reaches 72.38, and the prediction accuracy reaches 99.2%, indicating that the model is relatively accurate. The evaluation result of the ambient temperature impact on torque shows that ambient temperature is positively correlated with engine torque. [ABSTRACT FROM AUTHOR]

A twisted ∂¯f-Neumann problem associated to a singularity (On,f) is established. By relating it to the Koszul complex for Toeplitz n-tuples (f1,…,fn), where fi=∂f∂zi, on Bergman space B0(D), this ∂¯f-Neumann problem is solved. Moreover, the cohomology of the L2-holomorphic Koszul complex (B∗(D),∂f∧) can be computed explicitly. [ABSTRACT FROM AUTHOR]

The authors prove that the total descendant potential functions of the theory of Fan-Jarvis-Ruan-Witten for D with symmetry group 〈 J〉 and for D with symmetry group G, respectively, are both tau-functions of the D Kac-Wakimoto/Drinfeld-Sokolov hierarchy. This completes the proof, begun in the article by Fan-Jarvis-Ruan (2013), of the Witten Integrable Hierarchies Conjecture for all simple (ADE) singularities. [ABSTRACT FROM AUTHOR]

Low-molecular-weight (MW) ethylene oligomers with hyperbranched microstructures are often difficult to be synthesized by traditional catalytic processes. In this study, a series of N -terphenyl iminopyridyl ligands and the corresponding Pd(II) and Ni(II) complexes bearing remote conjugated substituents with different electronic effects (H, Me, F, Cl, and t Bu) were synthesized in a simple and efficient way. These Pd(II) and Ni(II) complexes were highly effective in the ethylene oligomerization and co-oligomerization with methyl acrylate (MA). Low-MW ethylene oligomers with hyperbranched microstructures were generated using the iminopyridyl Pd(II) and Ni(II) complexes in ethylene oligomerization. More importantly, polar functionalized ethylene-MA co-oligomers with low MWs and varying incorporation ratios were generated via ethylene and MA co-oligomerization using the Pd(II) complexes. Most notably, these ethylene oligomers obtained by different metal species showed a significant difference in microscopic chain architectures. The remote conjugated electron effect showed little effect on the polymerization parameters of the iminopyridyl system, which is very different from those of the salicylaldiminato system., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)

Thermus thermophilus DNA ligase ( Tth DNA ligase) is widely employed for cloning, enzymatic synthesis, and molecular diagnostics at high temperatures (e.g., 65 °C). It has been long believed that the complementary ends must be very long (e.g., >30 bp) to place two DNA fragments nearby for the ligation. In the current study, the length of the complementary portion was systematically varied, and the ligation efficiency was evaluated using the high resolution melting (HRM) method. Unexpectedly, very short oligonucleotides (7-10 nt) were successfully ligated on the complementary overhang attached to a dsDNA at 70 °C. Furthermore, sticky ends with the overhang of only 4 nt long, available after scission with many restriction enzymes, were also efficiently ligated at 45-70 °C. The ligation yield for the 6-nt-long sticky ends was as high as 80%. It was concluded that Tth DNA ligase can be used as a unique tool for DNA manipulation that cannot be otherwise easily accomplished.

BACKGROUND Physical tests are usually preferred to assess rotator-cuff syndrome but are insufficient to predict the morphology and size of the rotator-cuff. The objective of the study was to rate the ultrasound findings for patients with sudden shoulder pain and to determine potential predictors of the same. MATERIAL AND METHODS A total of 112 patients with sudden shoulder pain with rotator-cuff syndrome, suspected by orthopedic doctors, were subjected to ultrasonography. Real-time ultrasonography was done for the acromioclavicular joint, biceps, infraspinatus, posterior labrum, subscapularis, supraspinatus, teres minor tendon, and the sub-acromial-subdeltoid bursa. Each tendon was assessed via scanning planes in orientation as per longer and shorter axis, and from their myotendinous junction shoulder to bony insertions. Linear and logistic regression analysis were performed to predict the associations of medical history with rotator-cuff injury. RESULTS Ultrasonography identified that 82% of the enrolled patients had at least one particular cause of the rotator-cuff disorder. Among the rotator-cuff disorders, calcific tendonitis (54%) was observed more frequently followed by tendinopathy (32%), subacromial-subdeltoid bursitis (22%), and partial thickness tear (21%). Also, 46 patients (41%) had multiple findings. Older age (older than 40 years) was a strong predicting factor of rotator-cuff disorder (r²=0.36, P=0.0004). CONCLUSIONS Ultrasonography is a vital diagnostic procedure used by orthopedic surgeons for diagnosis of the rotator-cuff disorder(s) in patients with sudden shoulder pain.

Doxorubicin (DOX) resistance in breast cancer largely results from the breast cancer stem cell like cells (BCSCs) which could be targetted to improve the efficacy of chemotherapy. Cell permeabilization using microbubbles (MBs) and ultrasound (US) have the potential for delivering molecules into the cytoplasm. We aim to evaluate a new methodology of US on BCSCs. First, our findings indicated that ALDHA1 + spheres which were derived from fresh primary breast cancer samples displayed stem cell like features and were resistant to DOX. In patient cohort, we revealed the presence of a variable fraction of ALDHA1 + cells in nine out of ten. We, for the first time, showed a new US-MB treatment condition which could be used on ALDHA1 + BCSCs by fluorescence measurement and calcein assay. Next, we demonstrated the efficacy of combined treatment on human BCSCs in vitro and in vivo using DOX and US-MB: the combined treatment with much reduced drug dosage significantly suppressed the stem cell like features of BCSCs and induced BCSCs apoptosis. Furthermore, we suggested that decreased ABCG2 level might be one of the mechanisms by which US-MB medicated DOX treatment. In conclusion, this new US-MB treatment condition has clinical potential in breast cancer therapy by targetting BCSCs; thereby holding benefits for breast cancer patients., (© 2017 The Author(s).)

Purpose: To study the effects of Complex Tropicamide (0.5% Tropicamide and 0.5% phenylephrine HCI) and Saline solution on corneal thickness in adult myopic patients with the Orbscan II system., Setting: Department of Ophthalmology, Yantai Yuhuangding Hospital., Design: Prospective, nonrandomized, clinical trial., Methods: The thinnest pachymetry of the cornea was obtained before and 1.5 hours after administration of three drops of Complex Tropicamide to the left eyes of 58 patients (58 eyes) and Saline solution to their 31 right eyes, respectively. The corneal thickness of the other 27 right eyes before and 1.5 hours after eyelid closure without exposure to eye drops was used as the control group., Results: The thinnest pachymetry of the cornea was significantly higher after exposure to eye drops in the Tropicamide group (23.36 +/- 15.01 microm; t = -11.855, P < 0.001). Similar findings were also noted in the Saline group (7.13 +/- 8.11 microm, t = -4.894, P < 0.001). The difference between the two groups was also significant (t = 6.737, P < 0.001). There were no statistically changes in corneal thickness in control group. The drops tested have no effect on the location of the thinnest corneal site and its distance form the visual axis., Conclusion: Eye drops including Saline solutions may have significant effects on the corneal thickness in myopia, and this may have implications for corneal refractive surgery.