Theoretical Screening of Transition Metal Doped Defective MoS2 as Efficient Electrocatalyst for CO Conversion to CH4

CO is a key intermediate during electrochemical CO₂ conversion. The deep reduction of CO to value-added chemical products is a crucial strategy for effective carbon utilization. Single transition metal atoms supported by two-dimensional material present a novel paragon for various catalytic reactions. Herein, we employ first principle theory to study a series of single 3d-transition metal atoms supported by monolayered MoS₂ with S vacancy as efficient electrocatalyst for CO electroreduction to CH₄. The screening result indicates that Cr doped defective MoS₂ (labeled as Cr/S_v-MoS₂) is beneficial to electroreduction of CO to CH₄, with even less negative limiting potential (−0.32 V) than Cu that has been widely studied as the most promising electrocatalyst in experiment. The outstanding activity is derived from the regulation of the d-band-center of doped Cr and Mo atoms exposed on the surface. This discovery provides a theoretical basis for the preparation of future electrocatalysts for CORR.     

Established Beta Amyloid Pathology Is Unaffected by TREM2 Elevation in Reactive Microglia in an Alzheimer’s Disease Mouse Model

Several genetic studies have identified a rare variant of triggering receptor expressed on myeloid cells 2 (TREM2) as a risk factor for Alzheimer’s disease (AD). However, findings on the effects of TREM2 on Aβ deposition are quite inconsistent in animal studies, requiring further investigation. In this study, we investigated whether elevation of TREM2 mitigates Aβ pathology in TgCRND8 mice. We found that peripheral nerve injury resulted in a robust elevation of TREM2 exclusively in reactive microglia in the ipsilateral spinal cord of aged TgCRND8 mice at the age of 20 months. TREM2 expression appeared on day 1 post-injury and the upregulation was maintained for at least 28 days. Compared to the contralateral side, neither amyloid beta plaque load nor soluble Aβ40 and Aβ42 levels were attenuated upon TREM2 induction. We further showed direct evidence that TREM2 elevation in reactive microglia did not affect amyloid-β pathology in plaque-bearing TgCRND8 mice by applying anti-TREM2 neutralizing antibody to selectively block TREM2. Our results question the ability of TREM2 to ameliorate established Aβ pathology, discouraging future development of disease-modifying pharmacological treatments targeting TREM2 in the late stage of AD.     

具有伸展链构象聚苯胺/蒙脱土混杂纳米复合物的合成与表征

报道了具有聚苯胺伸展链构象的聚苯胺／ 粘土（ Ｐ Ａｎ／ Ｍ Ｍ Ｔ） 混杂纳米复合物的合成与表征．用插层聚合的方法将聚苯胺分子链嵌入层状蒙脱土的片层之中,从而得到一种高电导率的聚苯胺／ 层状硅酸盐混杂纳米复合物．通过 Ｘ 射线衍射（ Ｘ Ｒ Ｄ） ,付立叶红外（ Ｆ Ｔ Ｉ Ｒ） ,四探针电导率测量以及定性和定量的电子光谱分析等手段对产物进行了表征,结果表明,９０ ％ 以上的聚苯胺的分子链被插入蒙脱土的片层中间．由于聚苯胺分子链在受限的纳米空间生成,聚苯胺以伸展的单分子链构象存在．该构象在苯胺的通常聚合中不可能生成．通过对聚合过程进行吸收光谱监测,发现该聚合是扩散控制过程．     

人血清吸收光谱的研究

用吸收光谱的方法测试正常人血清和癌症病人的血清,发现它们的吸光度有差异。另外,在人血清中加入一定数目的癌细胞后测其吸光度,得到一些有意义的结果。     

Different Bonding Defects on Dual-Metal Single-Atom Electrocatalyst CoZnN6(OH) for Oxygen Reduction Reaction

Since dual-metal single-atom catalyst (CoZnN/C) has been experimentally synthesized by atomically arching CoZn on N-doped carbon nanofibers and exhibited potential electrocatalysis activity towards oxygen reduction reaction (ORR), we perform first-principles calculations to identify the highly active sites at different defects by comparing the four-step ORR processes on the constructed four CoZnN₆ models on graphene. The corresponding N-edge effect, dopant effect, and C-edge ring-closing effect are evaluated with the ORR evolution on different bonding environments, including pristine CoZnN₆(OH), nanoribbon (NR) along zigzag direction, substitution of carbon/oxygen (C/O substitution), and C-edge ring-closing configurations. OH-ligand is shown to significantly improve the ORR activities for all the considered structures. Especially, C-substituted CoZnN₆(OH), NR-CoZnN₅O(OH) and CoZnN₆(OH) with C-edge-effect exhibit obviously reduced overpotentials (η_lim=0.28, 0.48 and 0.41 V) of rate-determining steps among all the considered nine candidates. By plotting the relationship between the limiting potentials (U_lim) and free energies of intermediate *OH (ΔG_OH*), two prior catalysts of pristine-CoZnN₅C(OH) and defect-CoZnN₆CH(OH) are located near the top of the volcano curve with higher U_lim=0.95 and 0.82 V than Pt(111) (U_lim=0.80 V), implying that C-substitution could facilitate ORR performance in pristine- and defect-CoZnN₆(OH) bonding situation.     

A Honeycomb-Like Bulk Superstructure of Carbon Nanosheets for Electrocatalysis and Energy Storage

Superstructures have attracted extensive attention because of their potential applications in materials science and biology. Herein, we fabricate the first centimeter-sized porous superstructure of carbon nanosheets (SCNS) by using metal–organic framework nanoparticles as a template and polyvinylpyrrolidone as an additional carbon source. The SCNS shows a honeycomb-like morphology with wall-sharing carbon cages, in each cavity of which a porous carbon sphere is encapsulated. A single piece of SCNS is directly used as the electrode for a two-electrode symmetrical supercapacitor cell without any binders and supports, benefiting from its advantage in ultra-large geometric size, and the Fe-immobilized SCNS exhibits excellent catalytic performances for oxygen reduction reaction and in a Zn–air battery. This synthetic strategy presents a facile approach for preparing functional SCNS at centimetric scale with controllable morphologies and compositions favoring the fabrication of energy devices.     

2,4,6-三硝基-1,3,5-三羟基苯的一种新制备方法

为降低2,4,6-三硝基-1,3,5-三羟基苯（TNPG）在生产过程中对环境造成的危害并探究其高效且低污染的规模化生产工艺，本文以3,5-二甲氧基氟苯为原料，通过硝酸钾-浓硫酸组成的硝化体系进行硝化。在冰水淬灭硝化反应时氟原子被水解，得到中间体3,5-二甲氧基-2,4,6-三硝基苯酚（2），用冰乙酸溶解中间体2，再用氢溴酸脱甲基得到目标化合物TNPG，总收率96.13%。对该反应进行公斤级规模放大，发现重现性较好。采用核磁共振（NMR）、X-射线单晶衍射分析（XRD）和元素分析（EA）等方法对TNPG进行结构表征；利用差示扫描量热（DSC）和热重（TG）方法研究TNPG的热分解过程，结果发现：TNPG在157.11 ℃出现吸热峰，在171.60 ℃和191.63 ℃处出现放热峰。该合成方法简洁且收率较高。在温度为-173.15 ℃时，6TNPG·4H2O单晶密度为1.939 g/cm³，属trigonal晶系，P-3c1空间群。     

A Visibly Observable,Programmable Supramolecular Logic Platform and Its Application in Smart Thiols Sensing

Molecular computation is increasingly attractive as a tool for medical and biological research because of its programmability and controllability. Herein, a novel visibly observable supramolecular system that can execute multi-level logic functions on a uniform platform was constructed. By employing some programming factors, we succeeded in not only constructing a whole set of contrary logic pairs, but also building up a logic network that can implement advanced functions. Further, the platform is applied to sense thiols in specific environments. The developed method can efficiently filter signals of thiols in intracellular conditions and measure cysteine levels quantitatively in serum conditions. The visual readout makes the method particularly suitable for point-of-care testing. The supramolecule-based platform illustrates not only an incremental advance for the construction of programmable molecular logic systems, but also viable applications in intelligent thiol analysis.     

Recognizing Hybrid/Mixed G-quadruplex in Human Telomeres by Using a Cyanine Dye Supramolecule with Confocal Laser Scanning Microscopy

Single‐stranded telomeric DNA tends to form a four‐base‐paired planar structure termed G‐quadruplex. Although kinds of G‐quadruplex structures in vitro have been documented in the presence of potassium or sodium, recognition of these DNA motifs (both in vitro and in vivo) is still an important issue in understanding the biological function of the G‐quadruplex structures in telomeres as well as developing anticancer agents. Herein we address this important question through the distinctive properties of a supramolecular system of cyanine dye 3,3′‐di(3‐sulfopropyl)‐4,5,4′,5′‐dibenzo‐9‐methyl‐thiacarbocyanine triethylammonium salt (MTC) upon binding to different DNA motifs. Interaction of MTC with hybrid/mixed G‐quadruplex results in a set of unique spectrophotometric signatures which are completely different from those arising from binding to other DNA motifs. Furthermore, such feature could be extended to map the locations of DNAs on interface. Linear duplex and mixed G‐quadruplex in human telomeres assembled on Au film and stained by MTC were directly recognized by confocal laser scanning microscopy (CLSM). All results suggested that MTC supramolecular system may be a good probe of specific G‐quadruplex structure.     

Formation of Human Telomeric G-quadruplex Structures Induced by the Quaternary Benzophenanthridine Alkaloids:Sanguinarine,Nitidine,and Chelerythrine

The ligands which can facilitate the formation and stabilize G‐quadruplex structures have attracted enormous attention due to their potential ability of inhibiting the telomerase activity and halting tumor cell proliferation. It is noteworthy that the abilities of the quaternary benzophenanthridine alkaloids (QBAs), the very important G‐quadruplex binders, in inducing the formation of human telomeric DNA G‐quadruplex structures, have not been reported. Herein, the interaction between single‐strand human telomeric DNA and three QBAs: Sanguinarine (San), Nitidine (Nit) and Chelerythrine (Che), has been investigated. Although these molecules are very similar in structure, they exhibit significantly different abilities in inducing oligonucleotide d(TTAGGG)₄ (HT4) to specific G‐quadruplex structures. Our experimental results indicated that the best ligand San could convert HT4 into antiparallel G‐quadruplex structure completely, followed by Nit, which could transform to mixed‐type or hybrid G‐quadruplex structure partially, whereas Che could only transform to antiparallel G‐quadruplex structure in small quantities. The relative QBAs' inducing abilities as indicated by the CD data are in the order of San>Nit>Che. Further investigation revealed that the G‐quadruplex structures from HT4 induced by QBAs are of intramolecular motif. And only sequences with certain length could be induced by QBAs because of their positive charges which could not attract short chain DNA molecules to close to each other and form intermolecular G‐quadruplex. In addition, the factors that affect the interaction between HT4 and QBAs were discussed. It is proposed that the thickness of the molecular frame and the steric hindrance are the primary reasons why the subtle differences in QBAs' structure lead to their remarkable differences in inducing the formation of the G‐quadruplex structures.