Publications by authors named "Xin Min"

61 Publications

Modulation of NAD biosynthesis activates SIRT1 and resists cisplatin-induced ototoxicity.

Toxicol Lett 2021 Oct 4;349:115-123. Epub 2021 Jun 4.

Department of Otolaryngology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China; Institute of Hearing and Speech-Language Science, Sun Yat-sen University, Guangzhou, China; Department of Hearing and Speech-Language Science, Xinhua College, Guangzhou, China. Electronic address:

Cisplatin, the most widely used platinum-based anticancer drug, often causes progressive and irreversible sensorineural hearing loss in cancer patients. However, the precise mechanism underlying cisplatin-associated ototoxicity is still unclear. Nicotinamide adenine dinucleotide (NAD), a co-substrate for the sirtuin family and PARPs, has emerged as a potent therapeutic molecular target in various diseases. In our investigates, we observed that NAD level was changed in the cochlear explants of mice treated with cisplatin. Supplementation of a specific inhibitor (TES-1025) of α-amino-β-carboxymuconate-ε-semialdehyde decarboxylase (ACMSD), a rate-limiting enzyme of NADde novo synthesis pathway, promoted SIRT1 activity, increased mtDNA contents and enhanced AMPK expression, thus significantly reducing hair cells loss and deformation. The protection was blocked by EX527, a specific SIRT1 inhibitor. Meanwhile, the use of NMN, a precursor of NAD salvage synthesis pathway, had shown beneficial effect on hair cell under cisplatin administration, effectively suppressing PARP1. In vivo experiments confirmed the hair cell protection of NAD modulators in cisplatin treated mice and zebrafish. In conclusion, we demonstrated that modulation of NAD biosynthesis via the de novo synthesis pathway and the salvage synthesis pathway could both prevent ototoxicity of cisplatin. These results suggested that direct modulation of cellular NAD levels could be a promising therapeutic approach for protection of hearing from cisplatin-induced ototoxicity.
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http://dx.doi.org/10.1016/j.toxlet.2021.05.013DOI Listing
October 2021

Polydopamine Nanocluster Embedded Nanofibrous Membrane via Blow Spinning for Separation of Oil/Water Emulsions.

Molecules 2021 May 28;26(11). Epub 2021 May 28.

Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes, National Laboratory of Mineral Materials, School of Materials Science and Technology, China University of Geosciences, Beijing 100083, China.

Developing a porous separation membrane that can efficiently separate oil-water emulsions still represents a challenge. In this study, nanofiber membranes with polydopamine clusters polymerized and embedded on the surface were successfully constructed using a solution blow-spinning process. The hierarchical surface structure enhanced the selective wettability, superhydrophilicity in air (≈0°), and underwater oleophobicity (≈160.2°) of the membrane. This membrane can effectively separate oil-water emulsions, achieving an excellent permeation flux (1552 Lm h) and high separation efficiency (~99.86%) while operating only under the force of gravity. When the external driving pressure was increased to 20 kPa, the separation efficiency hardly changed (99.81%). However, the permeation flux significantly increased to 5894 Lm h. These results show that the as-prepared polydopamine nanocluster-embedded nanofiber membrane has an excellent potential for oily wastewater treatment applications.
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http://dx.doi.org/10.3390/molecules26113258DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8199142PMC
May 2021

Anti-inflammatory effects of three withanolides isolated from Physalis angulata L. in LPS-activated RAW 264.7 cells through blocking NF-κB signaling pathway.

J Ethnopharmacol 2021 Aug 4;276:114186. Epub 2021 May 4.

Key Laboratory of Molecular Pharmacology and Drug Evaluation, Ministry of Education, Collaborative Innovation Center of Advanced Drug Delivery System and Biotech Drugs in Universities of Shandong, School of Pharmacy, Yantai University, Yantai, 264005, PR China. Electronic address:

Ethnopharmacological Relevance: Physalis angulata L. is commonly used in many countries as popular medicine for the treatment of a variety of diseases such as malaria, hepatitis, dermatitis and rheumatism. But the anti-inflammatory active constituents of this medicinal plant and their molecular mechanism are still not elucidated clearly.

Aim Of The Study: The aim of the study is to isolate and identify a series of compounds from the ethanolic extract of Physalis angulata L., and to investigate the anti-inflammatory activities in vitro and the molecular mechanism of physagulin A, physagulin C, and physagulin H.

Materials And Methods: In order to further understand the anti-inflammatory mechanism of the three compounds, their potential anti-inflammatory activities were investigated in vitro in LPS-activated RAW 264.7 macrophage cells by Griess assay, ELISA, Western blot and immunofluorescence methods in the present study.

Results: Physagulin A, physagulin C, and physagulin H could not only inhibit the release of NO, PGE, IL-6 and TNF-α, but also could down-regulate the expression of iNOS and COX-2 proteins. Furthermore, physagulin A, physagulin C, and physagulin H could remarkably block the degradation of IκB-α and the nuclear translocation of NF-κB/p65 in LPS-activated RAW 264.7 cells. However, none of them could inhibit the phosphorylation of MAPKs family proteins ERK, JNK and p38. Thus, the anti-inflammatory actions of physagulin A, physagulin C, and physagulin H were mainly due to the significant inhibition of NF-κB signaling pathway rather than MAPKs signaling pathway.

Conclusions: All the results clearly showed that physagulin A, physagulin C, and physagulin H demonstrated potent anti-inflammatory activity and can be used as novel NF-κB inhibitors. They are potential to be developed as an alternative or complementary agents for inflammatory diseases.
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http://dx.doi.org/10.1016/j.jep.2021.114186DOI Listing
August 2021

[Effect of rhTPO to the Proliferation and Apoptosis of Acute Myeloid Leukemia Cell Lines].

Zhongguo Shi Yan Xue Ye Xue Za Zhi 2021 Apr;29(2):389-394

Department of Hematology, The First Medical Center, Chinese PLA General Hospital, Beijing 100853, China,E-mail:

Objective: To investigate the effects of recombinant human thrombopoietin (rhTPO) to proliferation and apoptosis of acute myeloid leukemia (AML) cell lines.

Methods: After the treatment of different concentrations of rhTPO (0, 50, 100 ng/ml) for different time (24,48,72 h),the cell proliferation rates of the AML cell lines (Kasumi-1, Skno-1, HEL, HL-60, THP-1) were determined by CCK-8 method. Apoptosis rate of each cell line cocultured with rhTPO was detected by Annexin V/PI method. The relative expression of TPO receptor c-MPL (myeloproliferative clonal antibody) mRNA in AML cell lines was detected by Q-PCR. The expression of c-MPL protein in each cell line was detected by Western blot. The expression of c-MPL antigen in HL-60 cells treated by different concentrations of rhTPO was detected by Flow cytometry.

Results: RhTPO showed no promotion to the proliferation of Kasumi-1, Skno-1, HEL, HL-60, THP-1 cell lines,however,it showed inhibitory effect to cell proliferation (72 h 0 ng/ml vs 100 ng/ml, P= 0.029) and pro-apoptotic (48 h 0 ng/ml vs 50 ng/ml, P=0.0143) in HL-60 cells. In Kasumi-1, Skno-1, HEL and THP-1 cells, there showed no statistically significant differences in apoptosis rate among each groups treated by different concentrations of rhTPO. Each AML cell line showed different levels of c-MPL gene and c-MPL protein expression, but HEL cells showed the highest expression in both of them. After HL-60 cells were treated by different concentrations of rhTPO for 48 hours, there showed no statistical difference in c-MPL antigen expression among each groups.

Conclusion: RhTPO can not promote the proliferation of Kasumi-1, Skno-1, HEL, HL-60 and THP-1 leukemia cell lines. On the contrary, rhTPO can inhibit HL-60 cell proliferation and promote its apoptosis, and this effect is not related to c-MPL gene expression or protein expression.
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http://dx.doi.org/10.19746/j.cnki.issn.1009-2137.2021.02.013DOI Listing
April 2021

[Clinical efficacy of posterior percutaneous endoscopic cervical discectomy for single level cervical spondylopathy with intraspinal ossification].

Zhongguo Gu Shang 2021 Jan;34(1):20-5

Department of Pain, Huazhong University of Science and Technology Union Shenzhen Hospital, Shenzhen 518052, Guandong, China.

Objective: To evaluate the effectiveness and security of posterior percutaneous endoscopic cervical discectomy (PPECD) in the treatment of single level cervical spondylopathy with intraspinal ossification.

Methods: Twenty three patients with single level cervical spondylopathy with intraspinal ossification were treated by posterior percutaneous endoscopic cervical discectomy between August 2017 and July 2019. There were 16 males and 7 females, aged from 29 to 74 years old with an average of (50±13) years.The disease duration were 3 to 120 months with a median of 6 months. There were 9 cases of cervical spondylotic radiculopathy, 6 cases of cervical spondylotic myelopathy, and 8 cases of mixed cervical spondylopathy. According to the characteristics of ossification, 17 cases were osteophytes on the posterior edge of the vertebral body;3 cases were protrusion ossification;3 cases were posterior longitudinal ligament ossification. According to the position of ossification in spinal canal, 14 cases were medial and lateral type, 5 cases were central type, and 4 cases were mixed type. Posterior percutaneous cervical endoscopic cervical discectomy in patients performed by the same surgeon. Japanese Orthopaedic Association (JOA) score and visual analogue scale(VAS) were compared separately before and after operation. At 3 months after operation, clinical effect was assessed according to modified Macnab standard.

Results: All operations were successful. The operative time was 30 to 155 (69.1±27.2) min. The bedridden time was 2 to 3(3.0±0.9) h, length of postoperative hospitalization was 2 to 7(4.1± 1.5) d. Three dimensional CT reconstruction of the cervical spine at 3 days after operation showed that ossified tissue of 13 cases were completely removed, and 10 cases were left after operation, and the residual was located at the posterior edge and/or center of the upper vertebral body. VAS score at discharge from hospital was significantly lower than that before operation (=9.35, <0.001), and 21 cases had a score of 0 to 3. Postoperative JOA score was significantly higher (=7.29, <0.001). At 3 months after operation, according to modified Macnab standard to evaluate clinical effect, 18 cases got exellent results, 4 good and 1 fair, with an excellent and good rate of 95.6%(22/23).

Conclusion: For an experienced surgeon, percutaneous posterior cervical endoscopic discectomy is safe and reliable in treating single level cervical spondylopathy with intraspinal ossification, and can obtain good clinical results.
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http://dx.doi.org/10.12200/j.issn.1003-0034.2021.01.005DOI Listing
January 2021

Hypoxia/reoxygenation-induced upregulation of miRNA-542-5p aggravated cardiomyocyte injury by repressing autophagy.

Hum Cell 2021 Mar 4;34(2):349-359. Epub 2021 Jan 4.

Emergency Department, Jiading District Central Hospital Affiliated Shanghai University of Medicine and Health Sciences, No.1, Chengbei Rd, Jiading District, Shanghai, 201800, China.

MicroRNAs (miRNAs) and autophagy exert an important role in hypoxia/reoxygenation (H/R)-induced cardiomyocyte injury. The current study aimed to explore the role of miRNA and autophagy in H/R-induced cardiomyocyte injury. Cardiomyocyte H9c2 was exposed to H/R to simulate H/R injury in vitro. The differentially expressed miRNAs were identified using quantitative RT-PCR (qPCR). Lactate dehydrogenase (LDH) activity was assayed to assess H/R injury. The role of miRNA and autophagy in regulating the viability and cell apoptosis was evaluated using cell counting kit-8 (CCK-8) assay, flow cytometry (FCM), and western blot. The autophagy activation was assessed through testing the number of light chain 3 (LC3) puncta and LC3-II expression using western blot and immunofluorescence analysis. In the present study, we found that the miR-542-5p expression and the autophagy activation were significantly increased in H9c2 cells after H/R injury. Functionally, forced expression of miR-542-5p further aggravated H/R injury in H9c2 cells, whereas miR-542-5p inhibition alleviated H/R injury as measured by the cell viability, LDH activity and cell apoptosis. miR-542-5p repressed autophagy activation, whereas miR-542-5p inhibition facilitated autophagy activation in H9c2 cells exposed to H/R as measured by the LC3 puncta number, LC3II, and p62 protein level. Especially, autophagy inhibition by specific inhibitor partially lessened the role of miR-542-5p inhibitor in alleviating H/R injury. Finally, the autophagy-related 7 (ATG7) was identified as a novel target gene of miR-542-5p in H9c2 cells. The current data suggest that miR-542-5p/autophagy pathway might be a potential target for the treatment of H/R-related heart diseases.
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http://dx.doi.org/10.1007/s13577-020-00466-zDOI Listing
March 2021

Synthesis of MnO derived from spent lithium-ion batteries via advanced oxidation and its application in VOCs oxidation.

J Hazard Mater 2021 Mar 2;406:124743. Epub 2020 Dec 2.

School of Environmental Science and Engineering, Shanghai Jiao Tong University, 800 Dong Chuan Road, Shanghai 200240, PR China; Shanghai Engineering Research Center of Solid Waste Treatment and Resource Recovery, Shanghai 200240, PR China. Electronic address:

In this work, manganese is selectively and efficiently recovered from spent lithium-ion batteries via advanced oxidation by using potassium permanganate and ozone, and the transition metal-doped α-MnO and β-MnO are one-step prepared for catalytic oxidation of VOCs. The recovery rate of manganese can be approximately 100% while the recovery efficiency of cobalt, nickel, and lithium is less than 15%, 2%, and 1%, respectively. Compared with pure α-MnO and β-MnO, transition metal-doped α-MnO and β-MnO exhibit better catalytic performance in toluene and formaldehyde removal attributed to their lower crystallinity, more defects, larger specific surface area, more oxygen vacancies, and better low-temperature redox ability. Besides, the introduction of the appropriate proportion of cobalt or nickel into MnO can significantly improve its catalytic activity. Furthermore, the TD/GC-MS result indicates that toluene may be oxidized in the sequence of toluene - benzyl alcohol - benzaldehyde-benzoic acid - acetic acid, 2-cyclohexen-1-one, 4-hydroxy-, cyclopent-4-ene-1,3-dione - carbon dioxide. This method provides a route for the resource utilization of spent LIBs and the synthesis of MnO.
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http://dx.doi.org/10.1016/j.jhazmat.2020.124743DOI Listing
March 2021

Recovery of cathode materials from spent lithium-ion batteries and their application in preparing multi-metal oxides for the removal of oxygenated VOCs: Effect of synthetic methods.

Environ Res 2021 02 2;193:110563. Epub 2020 Dec 2.

School of Environmental Science and Engineering, Shanghai Jiao Tong University, 800 Dong Chuan Road, Shanghai, 200240, PR China; Shanghai Institute of Pollution Control and Ecology Security, Shanghai, 200092, PR China. Electronic address:

Due to the sustainable use of wastes, cathode materials of spent lithium-ion batteries are recovered and used as transition metal precursors to prepare metal oxides catalysts for the oxidation of VOCs. In this work, a series of manganese-based and cobalt-based metal oxides are synthesized via different preparation methods. Catalytic activities of the catalysts prepared are investigated through complete oxidation of oxygenated VOCs and the physicochemical properties of optimum samples are characterized. Evaluation results indicate that MnOx (SY) (HT) sample prepared via hydrothermal method and CoOx (GS) (CP) synthesized via co-precipitation method had better performance, because they have higher specific surface area, higher concentration of active oxygen species and high-valence metal ion, as well as better low-temperature reducibility compared to the other multi-metal oxides used in the study. In addition, TD/GC-MS results imply that further oxidation of by-products requires high reaction temperature during VOCs oxidation.
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http://dx.doi.org/10.1016/j.envres.2020.110563DOI Listing
February 2021

Artificial Xylem Chip: A Three-Dimensionally Printed Vertical Digital Microfluidic Platform.

Authors:
Xin Min Woo Soo Kim

Langmuir 2020 12 29;36(48):14841-14848. Epub 2020 Nov 29.

Additive Manufacturing Laboratory, School of Mechatronic Systems Engineering, Simon Fraser University, Surrey, British Columbia V3T 0A3, Canada.

Digital microfluidics (DMF) is a promising lab-on-a-chip technology which has been applied in a wide variety of fields, including chemical sensing, biological detection, and even mechanical transportation. However, the appearance and functions of current DMF have been limited within two-dimensional planar space because of the conventional fabrication methods, such as photolithography or screen printing. In this paper, we report a DMF system which utilizes the advantage of three-dimensional (3D) printing to develop the novel form factor of electrodes and conversion of channels from planar to 3D forms. Vertical channels have been fabricated through combined 3D printing methods to facilitate stable and controlled movement of water droplets. The interfaces among liquid, gas, and solid were analyzed through Young-Lippmann law. We calculated the actuation force in a series of different configurations to enable us to optimize the system. Inspired by xylem structures in plants, the vertical movement and pumping of droplets are demonstrated by a programmable control system with a built-in boost converter for a real-time operating and portable DMF system. This work validates the promise of 3D printing to make 3D vertical DMF devices and the potential of the artificial xylem chip for micropumping applications.
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http://dx.doi.org/10.1021/acs.langmuir.0c02868DOI Listing
December 2020

Multiple Energy Transfer in Luminescence-Tunable Single-Phased Phosphor NaGdTiO: Tm, Dy, Sm.

Nanomaterials (Basel) 2020 Jun 27;10(7). Epub 2020 Jun 27.

Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes, National Laboratory of Mineral Materials, School of Materials Science and Technology, China University of Geosciences (Beijing), Beijing 100083, China.

Advances in solid-state white-light-emitting diodes (WLEDs) necessitate the urgent development of highly efficient single-phase phosphors with tunable photoluminescence properties. Herein, the Tm, Dy, and Sm ions are incorporated into the orthorhombic NaGdTiO (NGT) phosphors, resulting in phosphors that fulfill the aforementioned requirement. The emission spectrum of Tm ions overlaps well with the adsorption spectra of both Dy and Sm ions. Under the excitation at 358 nm, the single-phase NaGdTiO: Tm, Dy, Sm phosphor exhibits tunable emission peaks in the blue, yellow, and red regions simultaneously, resulting in an intense white-light emission. The coexisting energy transfer behaviors from Tm to Dy and Sm ions and the energy transfer from Dy to Sm ions are demonstrated to be responsible for this phenomenon. The phosphors with multiple energy transfers enable the development of single-phase white-light-emitting phosphors for phosphor-converted WLEDs.
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http://dx.doi.org/10.3390/nano10071249DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7407989PMC
June 2020

Promotional removal of oxygenated VOC over manganese-based multi oxides from spent lithium-ions manganate batteries: Modification with Fe, Bi and Ce dopants.

Sci Total Environ 2020 Oct 11;740:139951. Epub 2020 Jun 11.

School of Environmental Science and Engineering, Shanghai Jiao Tong University, 800 Dong Chuan Road, Shanghai 200240, PR China; Shanghai Engineering Research Center of Solid Waste Treatment and Resource Recovery, Shanghai 200240, PR China. Electronic address:

In this work, cathode materials of spent lithium-ions manganate batteries are recovered as the precursor of manganese-based oxides catalysts and furthermore, different amount of Fe, Bi, Ce are introduced to modify their properties. A series of MnOx(MS)-X Fe, MnOx(MS)-X Bi and MnOx(MS)-X Ce samples with crystal phase of MnO are synthesized using combustion method and then the catalytic behavior and physicochemical properties of prepared catalysts are investigated. Compared to binary MnOx-5% Fe, MnOx-15% Bi and MnOx-10% Ce samples, multi MnOx(MS)-5% Fe, MnOx(MS)-15 Bi and MnOx(MS)-10% Ce catalysts display enhanced catalytic performance significantly in the removal of oxygenated VOC, which could be attributed to larger specific surface area, higher concentration of surface active oxygen species and Mn ions and better reducibility at low temperature. In-situ DRIFTS results imply that main oxygen-containing functional groups such as carbonyl (-C=O), carboxyl (-COO), hydroxyl (-OH) can be observed during VOC oxidation and by comparison, it can be found that gas-phase O plays a crucial role in facilitating the further oxidation of by-products into CO. In addition, TD/GC-MS results point out that the main by-products are formaldehyde; 2-propanol, 1-methoxy-; ethanol, 2-methoxy-, acetate; 2-ethoxyethyl acetate; acetic acid during VOC oxidation.
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http://dx.doi.org/10.1016/j.scitotenv.2020.139951DOI Listing
October 2020

Enhanced catalytic activity of oxygenated VOC deep oxidation on highly active in-situ generated GdMnO/GdMnO catalysts.

J Colloid Interface Sci 2020 Oct 2;578:229-241. Epub 2020 Jun 2.

School of Environmental Science and Engineering, Shanghai Jiao Tong University, 800 Dong Chuan Road, Shanghai 200240, PR China; Shanghai Engineering Research Center of Solid Waste Treatment and Resource Recovery, Shanghai 200240, PR China. Electronic address:

In this work, GdMnO material is successfully prepared using sol-gel method and GdMnO/GdMnO materials are in-situ generated by acid treatment. These materials are investigated and applied as catalysts for oxygenated VOC complete oxidation. The evaluation results show that GdMnO/GdMnO-1.00 exhibits a remarkable increase in catalytic activity (T = 198 °C and T = 225 °C) of 2-ethoxyethanol oxidation when compared with the initial sample GdMnO (T = 223 °C and T = none). Characterization analyses show that acid treatment can result in the significant improvement of specific surface area from 20.502 m·g to 67.952 m·g, abundant surface Mn content and active oxygen, excellent reducibility at low temperature in GdMnO/GdMnO-1.00 sample. In-situ DRIFTS results point out that the main functional groups such as ν(OCO), ν(COO), ν(CO) are formed in the process of 2-ethoxyethanol oxidation over GdMnO/GdMnO-1.00 sample and some by-products including ethanol, 2-ethoxyethyl acetate, acetic acid, carbonic acid, 2-ethoxyethyl 2-methoxyethyl ester, ethane and 1,1'-oxybis[2-methoxy-] can be produced at a reaction temperature of 200 °C. Additionally, in-situ DRIFTS studies indicate the presence of gas-phase O plays a vital role in facilitating 2-ethoxyethanol deep oxidation to final products.
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http://dx.doi.org/10.1016/j.jcis.2020.05.095DOI Listing
October 2020

ZBTB20-mediated titanium particle-induced peri-implant osteolysis by promoting macrophage inflammatory responses.

Biomater Sci 2020 Jun 4;8(11):3147-3163. Epub 2020 May 4.

Department of Orthopaedic Surgery, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China.

Aseptic loosening (AL) caused by wear particles released from implant surfaces is one of the main causes for the failure of artificial joints, which is initiated by macrophage inflammatory responses. Emerging evidence suggests that the member of a broad-complex, tramtrack, bric-a-brac/poxvirus and zinc finger (BTB/POZ) family as well as zinc finger and BTB domain-containing protein 20 (ZBTB20) can inhibit IκBα gene transcription, promote NF-κB activation, and initiate innate immune responses. The molecular mechanism(s) by which ZBTB20 contributes to titanium particle (TiP)-induced macrophage inflammatory responses and osteolysis has not been fully elucidated. Here, we showed that ZBTB20 increased either in the AL group's synovial membranes or in TiP-stimulated bone-marrow-derived macrophages (BMDMs) as compared to that in the control groups. Moreover, the knockdown of ZBTB20 led to the inhibition of proinflammatory factors induced by TiPs in BMDMs, such as tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and interferon-β (IFN-β). Here, we also reported that the knockdown of ZBTB20 suppressed TiP-induced NF-κB activation and M1 polarization as well as stabilized the trans Golgi network (TGN) in BMDMs. The dual-luciferase reporter assay identified the binding between the IκBα promoter and ZBTB20, and IκBα knockdown could rescue the antiinflammatory effects induced by the ZBTB20 knockdown in BMDMs. Finally, we found that sh-ZBTB20 lentivirus injection could reduce TiP-induced osteolysis in mouse calvaria, inhibiting TiP-induced proinflammatory factors and loss of bone volume/total volume (BV/TV) as well as bone mineral density (BMD). These results suggest that ZBTB20 positively regulated NF-κB activation and M1 polarization as well as the production of TGN-derived tubular carriers in BMDMs, playing a positive role in macrophage activation and mouse cranial osteolysis induced by TiPs. It may be a potential therapeutic target for the prevention of aseptic loosening of prostheses.
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http://dx.doi.org/10.1039/d0bm00147cDOI Listing
June 2020

Metal-Based Nanocatalysts via a Universal Design on Cellular Structure.

Adv Sci (Weinh) 2020 Feb 26;7(3):1902051. Epub 2019 Nov 26.

Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes National Laboratory of Mineral Materials School of Materials Science and Technology China University of Geosciences (Beijing) Beijing 100083 P. R. China.

Metal-based nanocatalysts supported on carbon have significant prospect for industry. However, a straightforward method for efficient and stable nanocatalysts still remains extremely challenging. Inspired by the structure and comptosition of cell walls and membranes, an ion chemical bond anchoring, an in situ carbonization coreduction process, is designed to obtain composite catalysts on N-doped 2D carbon (C-N) loaded with various noble and non-noble metals (for example, Pt, Ru, Rh, Pd, Ag, Ir, Au, Co, and Ni) nanocatalysts. These 2 nm particles uniformly and stably bond with the C-N support since the agglomeration and growth are suppressed by anchoring the metal ions on the cell wall and membrane during the carbonization and reduction reactions. The [email protected] exhibits excellent catalytic activity and long-term stability for the hydrogen evolution reaction, and the relative overpotential at 100 mA cm is only 77 mV, which is much lower than that of commercial Pt/C and Pt single-atom catalysts reported recently.
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http://dx.doi.org/10.1002/advs.201902051DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7001642PMC
February 2020

Yellow Emission Obtained by Combination of Broadband Emission and Multi-Peak Emission in Garnet Structure NaYMgVO: Dy Phosphor.

Molecules 2020 Jan 27;25(3). Epub 2020 Jan 27.

Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes, National Laboratory of Mineral Materials, School of Materials Science and Technology, China University of Geosciences, Beijing 100083, China.

The fabrication and luminescent performance of novel phosphors NaYMgVO:Dy were investigated by a conventional solid-state reaction method. Under near-UV light, the NaYMgVO host self-activated and released a broad emission band (400-700 nm, with a peak at 524 nm) ascribable to charge transfer in the (VO) groups. Meanwhile, the NaYMgVO:Dy phosphors emitted bright yellow light within both the broad emission band of the (VO) groups and the sharp peaks of the Dy ions at 490, 582, and 663 nm at a quenching concentration of 0.03 mol. The emission of the as-prepared NaYMgVO:Dy phosphors remained stable at high temperatures. The obtained phosphors, commercial YO:Eu red phosphors, and BaMgAlO:Eu blue phosphors were packed into a white light-emitting diode (WLED) device with a near-UV chip. The designed WLED emitted bright white light with good chromaticity coordinates (0.331, 0.361), satisfactory color rendering index (80.2), and proper correlation to a color temperature (7364 K). These results indicate the potential utility of NaYMgVO:Dy phosphor as a yellow-emitting phosphor in solid-state illumination.
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http://dx.doi.org/10.3390/molecules25030542DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7038123PMC
January 2020

Efficient Adsorption of the Cd(II) and As(V) Using Novel Adsorbent Ferrihydrite/Manganese Dioxide Composites.

ACS Omega 2019 Nov 28;4(20):18627-18636. Epub 2019 Oct 28.

Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes, National Laboratory of Mineral Materials, School of Materials Science and Technology, China University of Geosciences, Beijing 100083, China.

Ferrihydrite/manganese dioxide composites (FH-M) were synthesized from ferrihydrite (FH) and manganese compounds by ex situ synthesis and characterized using X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy in the present work. The influences of experimental parameters such as the solution pH value and initial concentration of adsorbate on the adsorption uptake of Cd(II)/As(V) was systematically investigated. The adsorption kinetics was analyzed by fitting quasi-first-order and quasi-second-order kinetic equations. The results showed that with increase in the pH value, the adsorption rate of Cd(II) is increased, while that of As(V) is increased first and then decreased. For the kinetic adsorption process, the adsorption performance of FH-M to As(V) was better than that to Cd(II). The quasi-second-order kinetic equation and Freundlich equation were more suitable to describe the adsorption of Cd(II)/As(V). The ligand exchange of Cd(II)/As(V) with the -OH in the composites was confirmed by analyzing the characterization results of X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The high adsorption ability of the FH-M makes it a potentially attractive adsorbent for the removal to Cd(II) and As(V) with a good application prospect.
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http://dx.doi.org/10.1021/acsomega.9b02431DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6854822PMC
November 2019

New Efficient Visible-Light-Driven Photocatalyst of Chitin-Modified Titanium Dioxide/Carbon Fiber Composites for Wastewater.

Sci Rep 2019 Nov 8;9(1):16321. Epub 2019 Nov 8.

Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes, National Laboratory of Mineral Materials, School of Materials Science and Technology, China University of Geosciences (Beijing), 29 Xueyuan Road, Beijing, 100083, China.

To improve the catalyst properties of TiO under visible light irradiation, chitin-modified TiO was synthesized via a hydrothermal method on the surface of carbon fibers. The microstructure and interface properties of the so-prepared photocatalyst were investigated via X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and UV-visible diffuse reflectance spectroscopy. Our results indicated that the synergetic effect of the crystal phase of TiO, carbon fiber, and chitin is the main reason leading to the improvement of the photocatalytic activity of the composite catalyst. The modified TiO sample with chitin content of 0.6 wt% exhibited the highest photocatalytic activity under visible light irradiation when RhB was chosen as the target degradation product. Compared to the pure TiO/carbon fiber, the sample of TiO/carbon fiber with 0.6 wt% of chitin exhibits enhanced visible light activity with an apparent rate of degradation about 2.25 times. The enhancement of the photocatalytic performance of the sample with chitin can be attributed to the relatively high adsorption capacity of the particular network structure and photosensitivity of chitin, which can effectively separate the photoelectron-hole pair recombination. Furthermore, the new composite photocatalyst shows excellent catalytic stability after multiple degradation cycles, indicating that it is a promising photocatalytic material for degrading organic pollutants in wastewater.
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http://dx.doi.org/10.1038/s41598-019-52833-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6841960PMC
November 2019

Smart Composite Hydrogels with pH-Responsiveness and Electrical Conductivity for Flexible Sensors and Logic Gates.

Polymers (Basel) 2019 Sep 26;11(10). Epub 2019 Sep 26.

The Key Laboratory of Space Applied Physics and Chemistry, Ministry of Education and Shaanxi Key Laboratory of Macromolecular Science and Technology, School of Science, Northwestern Polytechnical University, Xi'an 710072, China.

Stimuli-responsive conductive hydrogels have a wide range of applications due to their intelligent sensing of external environmental changes, which are important for smart switches, soft robotics, and flexible sensors. However, designing stimuli-responsive conductive hydrogels with logical operation, such as smart switches, remains a challenge. In this study, we synthesized pH-responsive conductive hydrogels, based on the copolymer network of acrylic acid and hydroxyethyl acrylate doped with graphene oxide. Using the good flexibility and conductivity of these hydrogels, we prepared a flexible sensor that can realize the intelligent analysis of human body motion signals. Moreover, the pH-responsive conductive hydrogels were integrated with temperature-responsive conductive hydrogels to develop logic gates with sensing, analysis, and driving functions, which realized the intellectualization of conductive hydrogels.
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http://dx.doi.org/10.3390/polym11101564DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6836247PMC
September 2019

VPModel: High-Fidelity Product Simulation in a Virtual-Physical Environment.

IEEE Trans Vis Comput Graph 2019 11 12;25(11):3083-3093. Epub 2019 Aug 12.

In the development of a new product, the design team must describe the expected effects of the final products to potential users and stakeholders. However, existing prototyping tools can only present a product imperfectly, due to limitations at different levels. Specifically, the physical product model, which may be the product of 3D printing, could lack a visual interface; the presentation of the product through modeling software such as Rhinoceros 3D does not provide good realistic tactile perception; or the interface platforms, such as Axure RP, used to display the interactive effects differ from those to be used in the actual operation. Thus, we present the VPModel, a high-fidelity prototyping tool, able to integrate multiple prototyping methods simultaneously. It combines a touchable 3D-printed product model (3DPM) and a corresponding visualized virtual model, and the interactive interfaces are rendered synchronously in a mixed-reality device. Through the tangible, visual, and interactive demonstration, designers and normal users can each obtain a similar experience to the experience of the finished product. Furthermore, the VPModel also enhances design practices by enabling comparisons between modular models. However, the implementation of this system is a challenging task, which subsumes several fundamental problems as sub-tasks: object detection, real-time matching, hand-gesture detection and action recognition. To achieve the expected goals of the VPModel, this system uses physical hardware (a Microsoft MR HoloLens headset, a Leap Motion Controller, and a 3D printer) and existing machine learning algorithms. To evaluate our VPModel, we report the user experience of 16 participants, evaluated using a closed-ended questionnaire survey, a quantitative analysis of task performance, and a qualitative analysis of open-ended interviews. The results show a significant improvement in realism and enjoyment using the VPModel over the two traditional camera prototype approaches. In summary, the VPModel can be used to support design strategy and to convey design concepts fully and efficiently, which indicates a potential use for the VPModel in shortening product development cycles and reducing communication costs.
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http://dx.doi.org/10.1109/TVCG.2019.2932276DOI Listing
November 2019

A novel synthetic strategy for styrene-butadiene-styrene tri-block copolymer with high -1,4 units via changing catalytic active centres.

R Soc Open Sci 2019 Jun 19;6(6):190536. Epub 2019 Jun 19.

Ministry of Education and Shaanxi Key Laboratory of Macromolecular Science and Technology, School of Science, Northwestern Polytechnical University, Xi'an, Shaanxi 710129, People's Republic of China.

A styrene-butadiene-styrene tri-block copolymer (SBS) with a high -1,4 unit content (greater than 97%) was synthesized by a novel synthetic strategy based on changing the catalytic active centres using -butyllithium and a nickel-based catalyst. Firstly, styrene was polymerized via anionic polymerization using butyllithium as the initiator (Li, activity centre Li) at 50°C. The obtained alkylated macroinitiator (PSLi) was aged with nickel naphthenate (Ni) and boron trifluoride etherate (B) to prepare a second reactive centre (Ni-F), which was used to initiate the polymerization of butadiene (Bd). Finally, triphenyl phosphine (PPh) was added to adjust the electron density of the third active centre (P-Ni-F), and styrene monomer was added again to synthesize the second polystyrene block to obtain SBS. The polymerization technique presented here is simple and has an efficient initiation effect due to the high initiation activities for the different monomers. It also exhibits excellent control over the stereo-structure of the butadiene segments in the prepared copolymers, and the SBS polymers with high -1,4 unit content were easily achieved.
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http://dx.doi.org/10.1098/rsos.190536DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6599772PMC
June 2019

Toxicities of chemoradiotherapy and radiotherapy in nasopharyngeal carcinoma: an updated meta-analysis.

J Int Med Res 2019 Jul 5;47(7):2832-2847. Epub 2019 Jul 5.

1 Oncology Department, Jiading District Central Hospital Affiliated Shanghai University of Medicine & Health Sciences, Shanghai, China.

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http://dx.doi.org/10.1177/0300060519858031DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6683919PMC
July 2019

A New Strategy to Synthesize α,ω-Dihydroxy Multiblock Copolymers via [CpRu(CH CN) ]PF /Quinaldic Acid Catalyst.

Macromol Rapid Commun 2019 Sep 8;40(17):e1900135. Epub 2019 May 8.

Ministry of Education and Shaanxi Key Laboratory of Macromolecular Science and Technology, The Key Laboratory of Space Applied Physics and Chemistry, School of Science, Northwestern Polytechnical University, Xi'an, 710072, P. R. China.

In this study, a new strategy to synthesize random and alternating multiblock copolymers (MBCs) by the polycondensation of macromonomers' terminal hydroxyl groups with [CpRu(CH CN) ]PF /quinaldic acid as the catalyst is reported, which is often used for the preparation of a variety of biological small molecules via the reaction of allyl ethers. The degrees of hydroxyl functionality (F ) of the MBCs are assessed by titration, and the presence of hydroxyl on both the ends of MBCs is also confirmed by a chain-extension experiment of the ring-opening polymerization of D,L-lactide.
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http://dx.doi.org/10.1002/marc.201900135DOI Listing
September 2019

Synthesis and Luminescence Properties of a Novel Green-Yellow-Emitting Phosphor BiOCl:Pr for Blue-Light-Based w-LEDs.

Molecules 2019 Apr 3;24(7). Epub 2019 Apr 3.

Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes, National Laboratory of Mineral Materials, School of Materials Science and Technology, China University of Geosciences, Beijing 100083, China.

The development of white-light-emitting diodes (w-LEDs) makes it meaningful to develop novel high-performance phosphors excited by blue light. Herein, BiOCl:Pr green-yellow phosphors were prepared via a high-temperature solid-state reaction method. The crystal structure, luminescent properties, lifetime, thermal quenching behavior, and quantum yield were studied in detail. The BiOCl:Pr phosphors presented several emission peaks located in green and red regions, under excitation at 453 nm. The CIE coordinates could be tuned along with the changed doping concentration with fair luminescence efficiency. The results also indicated that the optimized doping concentration of Pr ions was at x = 0.0075 because of the concentration quenching behavior resulting from an intense exchange effect. When the temperature reached 150 °C, the intensity of the emission peak at 495 nm could remain at 78% of that at room temperature. The activation energy of 0.20 eV also confirmed that the BiOCl:Pr phosphor exhibited good thermal stability. All these results indicate that the prepared products have potential to be used as a high-performance green-yellow-light-emitting phosphor for blue-light-based w-LEDs.
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http://dx.doi.org/10.3390/molecules24071296DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6480924PMC
April 2019

A New Strategy for the Synthesis of Hydroxyl Terminated Polystyrene--Polybutadiene--Polystyrene Triblock Copolymer with High Cis-1, 4 Content.

Polymers (Basel) 2019 Apr 2;11(4). Epub 2019 Apr 2.

Department of Applied Chemistry, School of Nature and Applied Sciences, Northwestern Polytechnical University, Dongxiang Road 1, Xi'an 710072, China.

This work reports the preparation of a hydroxyl terminated polystyrene--polybutadiene--polystyrene triblock copolymer (SBS) with high cis-1, 4 content via a novel nickel catalyst, [η³-Ni(CH₂CHCHCH₂OOCH₃)][BPh₄]. FT-IR, ¹H-NMR, and C NMR indicated that the polybutadiene segment of the copolymer contains greater than 90% cis-1, 4 structure, indicating achievement of the objective. Toward the functionalization goal, a hydroxyl group was successfully introduced at the end of the triblock copolymer (HO⁻SBS⁻OH). The results of gel permeation chromatography (GPC) revealed that the polymer is indeed a triblock copolymer, with no traces of homopolymer. Differential scanning calorimetry (DSC) showed that HO⁻SBS⁻OH synthesized using the novel catalyst had a lower glass transition temperature () than HO⁻SBS⁻OH synthesized with an alkyl lithium catalyst. Therefore, the polymer synthesized via the novel catalyst contains high cis-1,4 content and displays excellent low-temperature mechanical properties.
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http://dx.doi.org/10.3390/polym11040598DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6523885PMC
April 2019

Synthesis and Properties of Side-Chain Functionalized Polytetrahydrofuran Derivatives via the Blue-Light Photocatalytic Thiol-Ene Reaction.

Polymers (Basel) 2019 Apr 1;11(4). Epub 2019 Apr 1.

The Key Laboratory of Space Applied Physics and Chemistry, Ministry of Education and Shaanxi Key Laboratory of Macromolecular Science and Technology, School of Science, Northwestern Polytechnical University, Xi'an 710072, China.

A series of side-chain functionalized polytetrahydrofuran (PTHF) derivatives were synthesized via the blue-light photocatalytic thiol-ene "click" reaction. Firstly, unsaturated polytetrahydrofuran (UPTHF) as a new unsaturated polyether was synthesized via condensation polymerization of cis-2-butene-1,4-diol and trans-1,4-dibromo-2-butene using potassium hydroxide (KOH) as a catalyst. Then, double bonds in the backbone of UPTHF were modified into different pendant functionality side groups by blue-light photocatalytic thiol-ene "click" reaction using Ru(bpy)₃Cl₂ as a photoredox catalyst, obtaining different side-chain functionalized PTHF derivatives. The structure and the morphology of the side-chain functionalized PTHF derivatives was characterized via Fourier-transform infrared spectra (FTIR), nuclear magnetic resonance (NMR), size exclusion chromatography/multi-angle laser light scattering (SEC/MALLS), and differential scanning calorimeter (DSC). The results showed that the blue-light photocatalytic thiol-ene reaction exhibited high efficiency, and all the unsaturated bonds were modified. Different branch units bestowed different performance of PTHF derivatives; we systematically investigated the thermal properties, pH-triggered and temperature-triggered, self-assembly behaviors of different PTHF derivatives.
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http://dx.doi.org/10.3390/polym11040583DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6523133PMC
April 2019

A New Synthesis Strategy on Styrene-Butadiene Di-Block Copolymer Containing High -1,4 Unit Via Transfer of Anionic to Coordination Polymerization.

Polymers (Basel) 2019 Jan 23;11(2). Epub 2019 Jan 23.

Ministry of Education and Shaanxi Key Laboratory of Macromolecular Science and Technology, School of Science, Northwestern Polytechnical University, Xi'an 710072, China.

A novel synthesis strategy on styrene-butadiene di-block copolymer (PS--PB) with high -1,4 unit content was developed, based on a transfer technique from anionic to coordination polymerization. Firstly, the styrene monomer was initiated by -butyllithium (Li) utilizing anionic polymerization at 50 °C, which resulted in a macromolecular alkylating initiator (PSLi). Secondly, PSLi was aged with nickel naphthenate (Ni) and boron trifluoride etherate (B) for obtaining a complex catalyst system (Ni/PSLi/B). Then, Ni/PSLi/B was applied to initiate the butadiene (Bd) polymerization. Following this new strategy, a series of PS--PBs were successfully synthesized. The experimental results indicated that under the molar ratio combination of [Li]/[Ni] = 5 and [B]/[Li] = 1, styrene-butadiene di-block copolymers could be easily achieved with high -1,4 unit content (>97%) and controlled molecular weight as well as narrow molecular weight distribution (M/M < 1.5). Furthermore, the copolymer's block ratio could also be effectively controlled by controlling the two components' monomer feed ratio.
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http://dx.doi.org/10.3390/polym11020195DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6418940PMC
January 2019

Additively Manufactured Digital Microfluidic Platforms for Ion-Selective Sensing.

ACS Sens 2019 04 20;4(4):918-923. Epub 2019 Mar 20.

Additive Manufacturing Laboratory, School of Mechatronic Systems Engineering , Simon Fraser University , Surrey , British Columbia V3T 0A3 , Canada.

Digital microfluidic (DMF) sensors integrated with circuit systems have been applied to a broad range of applications including biology, medicine, and chemistry. Compared with the conventional microfluidic devices that require extra liquid as a carrier and a complex pumping system to operate, DMF is an ideal platform for ion-selective sensing as it enables the droplet operation in a discrete, accurate, and automatic way. However, it is quite rare that DMF platform is utilized for the ion-selective detection. In this paper, we report an integrated DMF system which combines DMF and ion-selective sensing for facile blending of multiple ions, and detection of targeted primary ion. The platform is fabricated through an additive manufacturing method, together with the real-time droplet's motion monitoring feedback system. Thus, the fabricated system demonstrates controlled droplet manipulation ability including droplet actuation, mixing, and speed control. Targeted primary ion is selectively detected under concentration range from 10 to 1 M. The interference study with blended ions has been investigated through on-chip ion selective membranes.
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http://dx.doi.org/10.1021/acssensors.8b01689DOI Listing
April 2019

Formononetin and metformin act synergistically to inhibit growth of MCF-7 breast cancer cells in vitro.

Biomed Pharmacother 2019 Jan 26;109:2084-2089. Epub 2018 Nov 26.

Department of Physiology, Guilin Medical University, Guilin 541004, PR China. Electronic address:

Many breast cancer patients suffer from obvious side effects induced by chemotherapy. Formononetin (FM), one kind ingredient of Chinese herbal medicine, has been suggested to inhibit MCF-7 breast cancer cells. And recently metformin (MET) has gained more attention as a potential anti-cancer drug. The aim of this study was to investigate the synergistic effects of FM and MET on the proliferation of MCF-7 cells and to clarify the possible molecular mechanism involved. MCF-7 cells were treated with various concentrations of FM (40 and 80 μM) or FM (40 and 80 μM) combined with MET (150 μM) for 48 h. Cell proliferation was tested by an methyl tetrazolium (MTT) (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide) assay. The percentage of apoptotic cells was measured by flow cytometry. The expression level of b-cell lymphoma/leukemia-2 (bcl-2) mRNA was examined by RT-PCR, while the expression levels of phosphorylated extracellular signal-regulated kinases (p-ERK1/2) and bcl-2 protein were detected by Western blotting. Compared with untreated cells, 40 μM and 80 μM FM efficiently inhibited proliferation and increased apoptosis in MCF-7 cells. Additionally, 40 μM and 80 μM FM greatly downregulated bcl-2 mRNA expression when compared with untreated cells. Furthermore, the protein expression of bcl-2 and p-ERK1/2 was significantly reduced by 40 μM and 80 μM FM. The cytotoxic effect of FM was more remarkable when 150 μM MET was added. Taken together, the combinational use of FM and MET enhanced cell growth inhibition, and the induction of apoptosis in MCF-7 cells mediated by the ERK1/2 signaling pathway.
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http://dx.doi.org/10.1016/j.biopha.2018.09.033DOI Listing
January 2019

Ni-Catalyzed Dimerization and Hydroperfluoroarylation of 1,3-Dienes.

J Org Chem 2018 08 21;83(16):9267-9277. Epub 2018 Jun 21.

Department of Applied Chemistry, Graduate School of Engineering , Osaka University , Suita , Osaka 565-0871 , Japan.

A nickel-catalyzed three-component coupling reaction between perfluoroarenes and two molecules of a 1,3-diene in the presence of an alkyl Grignard reagent, which acted as a hydride source, provided 3-perfluoroarylated-1,7-octadienes via 1,3-diene dimerization and subsequent perfluoroarylation upon C-F bond cleavage. The reaction proceeded smoothly in a regioselective manner by simply combining NiCl and PPh as a catalyst and tolerated various functional groups on the perfluoroarenes. When substituted perfluoroarenes were employed, the reaction selectively occurred at the para-position. Mechanistic studies revealed that an anionic Ni complex, generated upon the reaction of Ni(0) with two molecules of a 1,3-diene and an alkyl Grignard reagent, played an important role in the C-C bond forming step with perfluoroarenes. The C-F bond cleavage was found to be a relatively fast step in the catalytic cycle.
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http://dx.doi.org/10.1021/acs.joc.8b01266DOI Listing
August 2018

Utilization of steric hindrance of alkyl lithium-based initiator to synthesize high 1,4 unit-containing hydroxyl- terminated polybutadiene.

R Soc Open Sci 2018 May 30;5(5):180156. Epub 2018 May 30.

Northwestern Polytechnical University, Xi'An, Shannxi 710000, People's Republic of China.

A novel alkyl lithium-based initiator with relatively large steric hindrance, -butyldimethylsiloxydimethylpropyl lithium (TBDMSODPrLi), was designed and synthesized. By using TBDMSODPrLi, hydroxyl-terminated polybutadiene (HTPB) was prepared via anionic polymerization. The macromolecular structure of HTPB was characterized and verified by FTIR and H-NMR. It was found that 1,4 unit content in HTPB initiated by TBDMSODPrLi was significantly higher (over 90%) compared to a HTPB (1,4 unit content of 70%) initiated with another initiator possessing smaller steric hindrance. The possible mechanism, which was based on initiator steric hindrance affecting monomer chain addition behaviour, was deduced. It was that the initiator's larger steric hindrance blocked lithium's intermolecular association during anionic polymerization; as a result, it could effectively increase the 1,4 unit content in HTPB. To further study how to obtain higher and stable 1,4 unit content, the optimal anionic polymerization technique for HTPB was explored including polymerization temperature, time and the amount of initiator used. The study concluded that utilization of an initiator with larger steric hindrance and reducing the polymerization temperature were two important factors to raise the 1,4 unit content in HTPB.
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http://dx.doi.org/10.1098/rsos.180156DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5990791PMC
May 2018
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