How Doping Affects the Activity of the Aluminum Oxide Support

The performance of heteronuclear clusters [AlXO₃]⁺ (X=Al, AlO₄, AlMg₂O₂, AlZnO, AlAu₂, Mg, Y, VO, NbO, TaO) in activating methane has been explored by a combination of high–level quantum calculations with reported and supplementary gas-phase experiments. With different dopants in [AlXO₃]⁺, the mechanism, reactivity and selectivity towards methane activation varies accordingly. The classic HAT competes with PCET, depending on the composition of intramolecular interactions. Although the existence of terminal oxygen radical is beneficial for classic HAT, the Al_t−C interaction in the [AlXO₃]⁺ clusters as enhanced by the strongly electronegative doping groups (X=Al, AlZnO, Mg, Zn, VO, NbO, TaO) favors the PCET process, facilitating C−H bond breaking. In addition, with different dopants, the destiny of the split methyl group varies accordingly. While strong interaction between Al_t and CH₃ results in the formation of the Al_t−C bond, dopants with variable valance may promote the formation of deep-oxidation products like formaldehyde. It has been discussed in detail how to regulate the activity and selectivity of the active center of the catalyst via rational doping.     

Accurate Geometry and Non-Covalent Interactions in 1-Phenylethanol and its Monohydrate: A Rotational Study

The pure rotational spectra of 1-phenylethanol and its monohydrate were measured by using a pulsed jet Fourier transform microwave spectrometer. One conformer of the 1-phenylethanol monomer with the trans form was observed in the pulsed jet. The experimental values of rotational constants of ten isotopologues, including eight mono-substituted ¹³C and one D isotopologues, allow an accurate structure determination of the skeleton of 1-phenylethanol. For its monohydrate, only one isomer has been observed, of which 1-phenylethanol adopts the trans form and binds with water through an O−H⋅⋅⋅O_w and an O_w−H⋅⋅⋅π hydrogen bond. Each rotational transition displays a doublet with a relative intensity ratio of 1 : 3, due to a hindered internal rotation of water around its C₂ axis. This study provides the information on accurate geometry of 1-phenylethanol (PE) and large amplitude motion of water in the PE monohydrate.     

Influence of Changing the Remote Substituents on Charge Transfer Properties of Cyanide-Bridged Trinuclear Fe−Ru−Fe Complexes

To investigate the effect of ligand remote (>10 Å) substituents on the bridging metal center on the metal-to-metal charge transfer (MMCT) properties in cyanidometa-bridged complexes, a series of new cyanidometal-bridged complexes and their one-electron and two-electron oxidation products have been synthesized and well characterized (namely, trans-[Cp(dppe)Fe−NC−(L)Ru(PPh₃)−CN−Fe(dppe)Cp][PF₆]_n (n=2, 3, 4) (L=dmptpy, 1[PF₆]_n ; L=meoptpy, 2[PF₆]_n ; L=t-Buptpy, 3[PF₆]_n ) (Cp=1,3-cyclopentadiene, dppe=1,2-bis(diphenylphosphino)ethane, PPh₃=triphenylphosphine, dmptpy=4′-(4-dimethylaminophenyl)-2,2′,6′,2′′-terpyridine, meoptpy=4′-(4-methoxyphenyl)-2,2′,6′,2′′-terpyridine, t-Buptpy=4′-(4-tertbutylphenyl)-2,2′,6′,2′′-terpyridine)). The investigations suggest that the cyanido-stretching (ν_CN) vibration energy for the complexes is unsensitive to the electron-donating ability change of the remote substituents of the cyanidometal bridging auxiliary ligand from tertbutyl, methoxy to dimethylamino group. However, the MMCT energies of the one- and two-electron oxidation complexes are still sensitive to the remote substituents of the ligand on the bridging metal center, and decreases with the increase of the electron-donating ability of the remote substituents from tertbutyl, methoxy to dimethylamino group. All one-electron and two-electron oxidation products belong to Class II mixed valence compounds according to the classification of Robin and Day.     

Correlation between Interfacial Structures and Device Performance: The Double-Edged Sword Effect of Lead Iodide in Perovskite Solar Cells

The interfacial electronic structure of perovskite layers and transport layers is critical for the performance and stability of perovskite solar cells (PSCs). The device performance of PSCs can generally be improved by adding a slight excess of lead iodide (PbI₂) to the precursor solution. However, its underlying working mechanism is controversial. Here, we performed a comprehensive study of the electronic structures at the interface between CH₃NH₃PbI₃ and C₆₀ with and without the modification of PbI₂ using in situ photoemission spectroscopy measurements. The correlation between the interfacial structures and the device performance was explored based on performance and stability tests. We found that there is an interfacial dipole reversal, and the downward band bending is larger at the CH₃NH₃PbI₃/C₆₀ interface with the modification of PbI₂ as compared to that without PbI₂. Therefore, PSCs with PbI₂ modification exhibit faster charge carrier transport and slower carrier recombination. Nevertheless, the modification of PbI₂ undermines the device stability due to aggravated iodide migration. Our findings provide a fundamental understanding of the CH₃NH₃PbI₃/C₆₀ interfacial structure from the perspective of the atomic layer and insight into the double-edged sword effect of PbI₂ as an additive.     

Rapid separation and binding configuration prediction of the components in Danshen decoction to endothelin A receptor using affinity chromatography and molecular dynamics simulation

As a famous traditional Chinese formula, Danshen Decoction has the potential to relieve the pain of pulmonary arterial hypertension patients, however, the functional components remain unknown. Herein, we reported a method to screen the functional components in Danshen Decoction targeting endothelin receptor A, an accepted target for the treatment of the disease. The receptor was functionalized on the macroporous silica gel through an epidermal growth factor receptor fusion tag and its covalent inhibitor. Using the affinity gel as the stationary phase, the bioactive compound was identified as salvianolic acid B by mass spectrometry. The binding kinetic parameter (dissociation rate constants k_d) of salvianolic acid B with the receptor was determined via peak profiling. Using the specific ligands of the receptor as probes, the binding configuration prediction of salvianolic acid B with the receptor was performed by molecular dynamics simulation. Our results indicated that salvianolic acid B is a potential bioactive compound in Danshen Decoction targeting the receptor. This work showed that receptor chromatography in combination with molecular dynamics simulation is applicable to predicting the binding kinetics and configuration of a ligand to a receptor, providing crucial insight for the rational design of drugs that recognize functional proteins.     

An integrated strategy for the geographical origin traceability of Goji berries by antioxidants characteristic fingerprint based online ultra-performance liquid chromatography-2,2-diphenyl-1-picrylhydrazyl- photodiode array detector-mass spectrometry combined with multivariate statistics analysis

Goji berries are now becoming increasingly popular in the human diet due to their potential health benefits. Unscrupulous traders deliberately mislabel with certain origins to gain illegal profits, which seriously affected the consumers’ benefits. In this study, an online ultra-performance liquid chromatography-2,2-diphenyl-1 -picrylhydrazyl-photodiode array detector-electrospray ionization-quadrupole time of flight mass was developed for rapid screening and identification of the antioxidants from Goji berry; then, the antioxidants characteristic fingerprint was established and explored in the origins discrimination of Goji berries from China combined with multivariate statistics analysis. As a result, twenty-eight compounds were screened from Goji berry extract, 19 of which were identified by accurate molecular and ultraviolet information according to references. Principal components analysis and partial least squares discrimination analysis achieved the accurate classification from the four regions, eight compounds were selected as origin-related antioxidant markers with variable importance in projection >1 and one-way analysis of variance (P<0.05), including rutin, rutin di-hexose, P-coumaric acid tri-hexose, dicaffeoylquinic acid isomer, Quercetin-rhamno-di-hexoside, peak14, peak16, and peak27. This study provides a feasible strategy for the geographical origins discrimination of Goji berries based on antioxidant ingredients difference and will be helpful for improving the quality control level of Goji berries.     

Flash Nanoprecipitation Fabrication of PEI@Amorphous Calcium Carbonate Hybrid Nanoparticles for siRNA Delivery

RNA interference (RNAi) is a promising approach for disease treatments. But the development of safe and effective delivery carriers remains a major challenge. Organic–inorganic hybrid nanoparticles (NPs), with the integration of functions from distinct materials, show great potential in small interfering RNA (siRNA) delivery. Herein, pH responsive amorphous calcium carbonate NPs (ACC NPs) are prepared using flash nanoprecipitation and hybrid NPs are constructed by coating ACC NPs with polyethyleneimine (PEI) for efficient siRNA delivery. PEI/ACC NPs show robust pH responsiveness and stability as well as effective siRNA loading and protection. Furthermore, siRNA-loaded PEI/ACC NPs demonstrate enhanced cellular uptake and efficient endosomal escape, mediating improved siRNA delivery compared to pure PEI. These findings suggest that PEI/ACC NPs may have great potential in siRNA delivery for RNAi-based therapy.     

Microinjection Molded Biopolymeric Airway Stent with Antibacterial and Anti-Hyperplastic Properties

Central airway stenosis is a condition that the diameter of the trachea or main bronchus shrinkage is caused by external compression or internal tissue hyperplasia, which can cause difficulty breathing, asphyxia, and even death. Airway stenting is an easy way to restore the patency of the central airway, but airway stents commonly used in clinical practice can lead to complications such as mucus plugging, bacterial infection, and granulation tissue hyperplasia. Moreover, the non-degradable characteristic makes it requires a second operation to remove, which has the potential to cause tissue damage. In this study, a biodegradable airway stent is fabricated by microinjection molding using the bioelastomer of poly (L-lactide-co-ε-caprolactone) as the matrix material. The airway stent has excellent mechanical properties and an appropriate degradation rate. The hydrophilic surface of the airway stent can inhibit mucus plugging. The loading of silver nanoparticles and cisplatin endows the stent with antibacterial and anti-hyperplastic functions. In vitro and in vivo experiments demonstrate that this study provides an antibacterial and anti-hyperplastic biodegradable airway stent with elastic properties to avoid secondary removal operation and reduce complications associated with mucus plugging, bacterial infection, and granulation tissue hyperplasia.     

交互模式-电感耦合等离子体质谱(ICP-MS)法测定生态地球化学植物样品中7种金属元素

植物样品中各元素的含量,是评价土壤质量及健康的重要指标。为满足测定大批量生态地球化学植物样品中多金属元素分析要求,建立了交互模式-ICP-MS法测定植物样品中7种痕量金属元素的定量分析方法。讨论了ICP-MS的STD、KED（He）、交互模式3种方法测定植物样品中7种金属元素结果。实验结果表明：利用工作曲线法配制Hg标准溶液,更改82Se在线校正方程系数为1.83,在ICP-MS的交互模式下测定植物样品中82Se,63Cu,60Ni,66Zn,111Cd,75As、202Hg可以得到准确可靠的结果,克服了植物样品中Se和Hg元素测定的难题。基于所建方法各元素校准曲线系数＞0.999;方法检出限为0.0004~0.08mg/kg;加标回收率在96.2%-107%之间;测定GBW10010a（大米）、GBW10012（玉米）、GBW10021（豆角）3种标准物质,结果均在参考值范围内,相对标准偏差RSD＜10%。该方法前处理简单、灵敏度高、准确度高、分析速度快,适用于生态地球化学评价植物样品多金属元素同时测定。为地球化学调查工作中分析测试植物样品中金属多元素的快速测定提供了新思路。     

酸溶-电感耦合等离子体发射光谱法测定白云石和菱镁石中主次元素

利用电感耦合等离子体原子发射光谱仪( ICP-AES)建立白云石和菱镁石中铝、钙、铁、镁、锰、磷、硅、锶的测定方法。研究了酸体系、温度及消解方式对试样消解的影响,结果表明,使用5 mL盐酸和硝酸混合酸(1：3)-0.75 mL氢氟酸-5 mL水以密闭消解的方式在150 ℃下消解白云石和菱镁石30min,并以2mL饱和硼酸络合多余的氢氟酸,可以得到澄清消解液。通过白云石和菱镁石中铝、钙、铁、镁、锰、磷、硅、锶的谱线干扰情况,选择Al 308.215 nm、Ca 318.127 nm、Fe 261.187 nm、Mg 277.983 nm、Mn 257.61 nm、P 213.618 nm、Si 251.611 nm、Sr 421.552 nm作为分析线,各元素的校准曲线在线性范围内线性关系良好,相关系数均不小于0.999。按照实验方法测定白云石和菱镁石标准物质,各元素结果的相对标准偏差 (RSD, n=6)为0.89~3.19%,测定值与认定值无显著性差异。本方法有效解决了白云石和菱镁石快速有效溶解及准确测定问题。