Sedimentary Evolution and Provenance of the late Permian-middle Triassic Raggyorcaka Deposits in North Qiangtang (Tibet, Western China): Evidence for a Forearc Basin of the Longmu Co-Shuanghu Tethys Ocean

The tectonic origin of the >500‐km‐long E‐W trending Central Qiangtang metamorphic belt (CQMB), which separates the North Qiangtang block (NQB) and South Qiangtang block (SQB), remains controversial. Moreover, the coeval geological evolution of the southern NQB has been poorly investigated, particularly its tectonic relationship with the CQMB. Here we present stratigraphic, sedimentary, and provenance analyses of the late Permian‐middle Triassic depositional succession at Raggyorcaka in the southern NQB and test two radically different hypotheses for origin of the CQMB. A complete marine transgression‐regression sequence with two‐sided provenance characterizes the late Permian‐Triassic sedimentary rocks in the southern NQB. Sandstone petrological analyses reveal a prominent provenance transition to an active volcanic source beginning in the late Changhsingian. Detrital zircon U‐Pb geochronological results of the transgression subsequence show a concentrated youngest zircon group of 236–288 Ma (peak at ~248.1 Ma), with negative εHf(t) values (−25.3 to −0.2) and large Hf crustal model ages (TC DM; 1,311–2,887 Ma). These new findings show that the Raggyorcaka sequence was most likely deposited in an active continental margin. Combined with other evidence, we further infer that the Carboniferous‐Triassic successions of the southern NQB were most likely deposited in a forearc basin under the in situ suture model, that is, the northward subduction of the Longmu Co‐Shuanghu Tethys Ocean beneath the NQB. Moreover, the detrital zircon age distribution of the southern NQB suggests that the NQB probably drifted from the Gondwana supercontinent in the early Paleozoic and became adjacent to peri‐Cathaysian blocks no later than the CarboniferousOur field work was supported by the Young Scientist Fund of the National Natural Science Foundation of China (Grant 41402177). The experimental items were financially supported by the China Geological Survey (CGS): “1:50,000 regional geological surveys in the Gangmari area of Tibet” (Grant 1212011086062) and the Ministry of Education of the People's Republic of China (Grant 649199111027)

Dynamic Modeling and Nonlinear Analysis of a Spur Gear System Considering a Nonuniformly Distributed Meshing Force

In previous studies, the meshing force of a gear system is usually treated as being uniformly distributed for the convenience of analysis. In practical applications, however, it is nonuniformly distributed along the line of action due to machining errors, assembly errors, misalignment errors, etc. When a nonuniformly distributed meshing force is coupled with the shaft deformation, dynamic center distance, and time-varying meshing stiffness, the transmission performance of the gear system will be seriously degraded. Therefore, a nonuniformly distributed meshing force cannot be ignored when considering the gear systems used in complicated working conditions. In this study, the gear’s nonuniformly distributed meshing force is analyzed. Then, an 18 degrees-of-freedom bending-torsion-swing-coupled dynamic model of a pair of involute spur gears is put forward. Through this model, the coupling relationship between the nonuniformly distributed meshing force, shaft bending deformation, and dynamic center distance is accurately described. The influence of meshing frequency, stiffness excitation, damping, and error excitation on the nonlinear dynamic characteristics of the gear system was researched through bifurcation diagrams, phase diagrams, Poincaré maps, and time-domain diagrams. Various complicated nonlinear dynamic behaviors, such as quasiperiodic motion, bifurcation, chaotic motion, and chaotic banding, are revealed. Reasonable parameter ranges that guarantee the gear system is in a stable motion were extracted. By evading complicated nonlinear dynamic behavior, the transmission performance of a gear system was improved. This research will contribute to reducing the vibration and noise of gear systems

Enhancing sensitivity of SERRS nanoprobes by modifying heptamethine cyanine-based reporter molecules

Surface enhanced resonance Raman scattering (SERRS) is a physical phenomenon that occurs when the energy of incident light is close to that of electronic excitation of reporter molecules (RMs) attached on substrates. SERRS has showed great promise in healthcare applications such as tumor diagnosis, image-guided tumor surgery and real-time evaluation of therapeutic response due to its ultra-sensitivity, manipulating convenience and easy accessibility. As the most widely used organic near-infrared (NIR) fluorophore, heptamethine cyanines possess the electronic excitation energy that is close to the plasmon absorption energy of the gold nano-scaffolds, which results in the extraordinary enhancement of the SERRS signal. However, the effect of heptamethine cyanine structure and the gold nanoparticle morphology to the SERRS intensity are barely investigated. This work developed a series of SERRS nanoprobes in which two heptamethine cyanine derivatives (IR783 and IR780) were used as the RM and three gold nanoparticles (nanorod, nanosphere and nanostar) were used as the substrates. Interestingly, even though IR780 and IR783 possess very similar chemical structure, SERRS signal produced by IR780 was determined as 14 times higher than that of IR783 when the RM concentration was 6.5 × 10−6M. In contrast, less than 4.0 fold SERRS signal intensity increase was measured by changing the substrate morphologies. Above experimental results indicate that finely tuning the chemical structure of the heptamethine cyanine could be a feasible way to develop robust SERRS probes to visualize tumor or guide tumor resection with high sensitivity and target to background ratio

Leaching kinetics of ionic rare-earth in ammonia-nitrogen wastewater system added with impurity inhibitors

Ammonia-nitrogen wastewater is produced during the dressing and smelting process of rare-earth ores. Such wastewater includes a very high concentration of NH4 +, as well as other ions (e.g., NH4 +, RE3+, Al3+, Fe3+, Ca2+, Cl-, and SiO3 2-) with a pH of 5.4-5.6. Its direct discharge will pollute, yet it can be recycled and used as a leaching reagent for ionic rare-earth ores. In this study, leaching kinetics studies of both rare earth ions and impurity ion Al3+ were conducted in the ammonia-nitrogen wastewater system with the aid of impurity inhibitors. Results showed that the leaching process of rare-earth followed the internal diffusion kinetic model. When the temperature was 298 K and the concentration of NH4 + was 0.3 mol/L, the leaching reaction rate constant of ionic rare-earth was 1.72 and the apparent activation energy was 9.619 kJ/mol. The leaching rate was higher than that of conventional leaching system with ammonium sulfate, which indicated that ammonia-nitrogen wastewater system and the addition of impurity inhibitors could promote ionic rare-earth leaching. The leaching kinetic process of impurity Al3+ did not follow either internal diffusion kinetic model or chemical reaction control, but the hybrid control model which was affected by a number of process factors. Thus, during the industrial production the leaching of impurity ions could be reduced by increasing the concentration of impurity inhibitors, reducing the leaching temperature to a proper range, accelerating the seepage velocity of leaching solution, or increasing the leaching rate of rare earths

Detection of Abrin by Electrochemiluminescence Biosensor Based on Screen Printed Electrode

For the convenience of fast measurement in the outdoor environment, a portable electrochemiluminescence biosensor with the screen-printed electrode as the reaction center was developed, which possesses the characteristics of high sensitivity, small scale, simplified operation and so on, and has been used for in situ detection of abrin. First, combining with magnetic separation technique, the “biotin-avidin” method was used to immobilize the polyclonal antibody (pcAb) on the magnetic microspheres surface as the capture probe. Secondly, the Ru(bpy)32+-labeled monoclonal antibody (mcAb) was used as the specific electrochemiluminescence signal probe. Then, the “mcAb-toxin-pcAb” sandwich model was built to actualize the quantitative detection of abrin on the surface of the screen-printed electrode. The linear detection range was 0.5–1000 ng/mL; the regression equation was Y = 89.251lgX + 104.978 (R = 0.9989, n = 7, p < 0.0001); and the limit of detection (LOD) was 0.1 ng/mL. The sensing system showed high sensitivity, excellent specificity and good anti-interference ability, and could be used for the analysis of trace abrin in various environmental samples with good recovery and reproducibility. Compared with the traditional electrochemiluminescence sensing device, its miniaturization and portability gives it potential to satisfy the requirement of in situ detection

Metabolizable Photosensitizer with Aggregation-Induced Emission for Photodynamic Therapy

10.1021/acs.chemmater.1c01173CHEMISTRY OF MATERIALS33155974-598

Living Bacteria-Based Immuno-Photodynamic Therapy: Metabolic Labeling of <i>Clostridium butyricum</i> for Eradicating Malignant Melanoma

10.1002/advs.202105807ADVANCED SCIENCE91

Carrier-Free Hybrid DNA Nanoparticles for Light-Induced Self-Delivery of Functional Nucleic Acid Enzymes

10.1021/acsnano.0c10045ACS NANO1511841-184

Living Bacteria-Based Immuno-Photodynamic Therapy: Metabolic Labeling of Clostridium butyricum for Eradicating Malignant Melanoma.

Due to the complexity, aggressiveness, and heterogeneity of malignant melanoma, it is difficult to eradicate the whole tumor through conventional treatment. Herein, a strategy of metabolic engineering labeled anaerobic oncolytic bacteria (Clostridium butyricum) is demonstrated to achieve the ablation of melanoma. In this system, the metabolic substrate of C. butyricum d-alanine (d-Ala) is first conjugated with a photosensitizer (TPApy) showing aggregation-induced emission (AIE). The yielded metabolic substrate of d-Ala-TPAPy can be metabolically incorporated into bacterial peptidoglycan to form engineered C. Butyricum. Once the engineered C. butyricum is injected into melanoma, the bacteria can only proliferate in an anaerobic zone, stimulate the tumor immune microenvironment, and ablate the tumor hypoxia region. Following that, the relatively rich oxygen content in the peripheral area can induce the death of C. butyricum. The photosensitizer (PS) on the bacteria can subsequently exert a photodynamic effect in the oxygen-rich region and further remove the melanoma residue under light irradiation. Prominent in vivo melanoma ablation results revealed that the engineering oncolytic bacteria can provide a promising regime for solid tumor eradication