Study on Magnetic Shielding for Performance Improvement of Axial-Field Dual-Rotor Segmented Switched Reluctance Machine

A category of permanent-magnet-shield(PM-shield)axial-field dual-rotor segmented switched reluctance machines(ADS-SRMs)are presented in this paper.These topologies are featured by using the magnetic material to shield the flux leakage in the stator and rotor parts.Besides,the deployed magnets weaken the magnetic saturation in the iron core,thus increasing the main flux.Hence,the torque-production capability can be increased effectively.All the PM-shield topologies are proposed and designed based on the magnetic equivalent circuit(MEC)model of ADS-SRM,which is the original design deploying no magnet.The features of all the PM-shield topologies are compared with the original design in terms of the magnetic field distributions,flux linkages,phase inductances,torque components,and followed by their motion-coupled analyses on the torque-production capabilities,copper losses,and efficiencies.Considering the cost reduction and the stable ferrite-magnet supply,an alternative proposal using the ferrite magnets is applied to the magnetic shielding.The magnet demagnetization analysis incorporated with the thermal behavior is performed for further verification of the motor performance.

Design and Optimization of Dual-Winding Fault-Tolerant Permanent Magnet Motor

To improve the performance of the traditional fault-tolerant permanent magnet(PM)motor,the design and optimal schemes of dual-winding fault-tolerant permanent magnet motor(DWFT-PMM)are proposed and investigated.In order to obtain small cogging torque ripple and inhibiting the short-circuit current,the air gap surface shape of the PM and the anti short-circuits reactance parameters are designed and optimized.According to the actual design requirements of an aircraft electrical actuation system,the parameters,finite element analysis and experimental verification of the DWFT-PMM after optimal design are presented.The research results show that the optimized DWFT-PMM owns the merits of strong magnetic isolation,physics isolation,inhibiting the short circuit current,small cogging torque ripple and high fault tolerance.

Advances in emission control of diesel vehicles in China

Diesel vehicles have caused serious environmental problems in China.Hence,the Chinese government has launched serious actions against air pollution and imposed more stringent regulations on diesel vehicle emissions in the latest China VI standard.To fulfill this stringent legislation,two major technical routes,including the exhaust gas recirculation(EGR)and high-efficiency selective catalytic reduction(SCR)routes,have been developed for diesel engines.Moreover,complicated aftertreatment technologies have also been developed,including use of a diesel oxidation catalyst(DOC)for controlling carbon monoxide(CO)and hydrocarbon(HC)emissions,diesel particulate filter(DPF)for particle mass(PM)emission control,SCR for the control of NOx emission,and an ammonia slip catalyst(ASC)for the control of unreacted NH3.Due to the stringent requirements of the China VI standard,the aftertreatment system needs to be more deeply integrated with the engine system.In the future,aftertreatment technologies will need further upgrades to fulfill the requirements of the near-zero emission target for diesel vehicles.

FeS@LAB-35@Ti_(3)C_(2)as a high-efficiency nanozyme for near infrared light induced photothermal enhanced chemodynamic antibacterial activity and wound healing

The abuse of antibiotics leads to a significant increase in bacterial resistance,which makes it difficult to treat bacterial infections.Therefore,it is urgent to develop new strategies for efficient antibacterial and wound healing.Recently,nanozymes based antibacterial agents have attracted increasing attention for their multifunction and high efficiency.In this study,we report a FeS@lauramidopropyl betaine(LAB-35)@Ti_(3)C_(2)nanozyme as a high-efficiency antibacterial agent for near infrared(NIR)light induced photothermal enhanced chemodynamic antibacteria and wound healing.The FeS@LAB-35@Ti_(3)C_(2)nanozyme possesses peroxidase-like catalysis activity,which can promote the generation of hydroxyl radicals(·OH)through catalyzing the decomposition of H_(2)O_(2).FeS@LAB-35@Ti_(3)C_(2)has photothermal conversion efficiency(η=65.1%),and it exhibits enhanced catalytic activity under NIR light irradiation.The in vitro antibacterial experiments demonstrate the excellent antibacterial activity of FeS@LAB-35@Ti_(3)C_(2)against representative Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus.The animal experiments indicate that FeS@LAB-35@Ti_(3)C_(2)nanozyme can effectively inhibit wound ulceration and promote wound healing.Overall,this study proposes FeS@LAB-35@Ti_(3)C_(2)nanozyme that integrates chemodynamic and photothermal therapy,which provides an efficient strategy for bacterial inhibition and wound healing.

C-Aryl Glycosylation via Interrupted Pummerer Rearrangement

C-aryl glycosides are an important kind of carbohydrate derivatives for drug discovery,due to their distinctive attributes of resistance to hydrolysis from enzymes.Herein,C-aryl glycosylation was established for the synthesis of 2-sulfur C-aryl glycals and 1,2-dihydrobenzofuran-fused C-aryl glycosides via interrupted Pummerer process,featured with sulfonium-tethered[3,3]-sigmatropic rearrangement between sulfoxide glycals and phenols.This protocol offers a broad substrate scope with diverse glycosyl and phenols.Dapagliflozin,Empagliflozin,and Ipragliflozin analogs were straightforward achieved,respectively.

Research strategies in click chemistry: Measuring its cognitive contents and knowledge flow

The issue about how outstanding scientists obtained innovative findings has drawn the interest of researchers in science, policy and scientometrics. Here, we attempt to address this question by using computational methods to measure the cognitive content and concepts of K. Barry Sharpless’ research and estimate the knowledge flow of his click chemistry to other fields. First, we traced Sharpless’ conceptual journey over time through topic modeling approach, mapping and clustering of the epistemic network from distant reading his publications. We find that connectivity and functions, the core features of click chemistry, are embodied in his constant search for simplicity. What makes simplicity possible is his continuous work with collaborators on reactivity and reaction mechanisms. Moreover, citation and link analysis show that click chemistry had a much richer impact on other research fields than what is generally acknowledged, and drew solutions to significant and practical questions back to chemistry from biology.Together with these findings, we propose that the click chemistry philosophy follows the way that values nature’s principle. Chemistry has a clear-cut epistemic domain in modeling Nature. Thus, click chemistry as a concept on doing science beyond a connective technology goes across the boundaries between disciplines and impacts many other fields.

N-Acetylenethio phthalimides: Sequential linkage for compositional click reaction

Click chemistry has become a useful tool for diverse molecular linkage and modification, and the development of new click strategy that enable reversibility and multifunctionality is of high demand for the multifunction and drug release. Herein, compositionally clicking combined regioselective iridium-catalyzed azide-alkynthio cycloaddition(Ir-AAC) and disulfuration has been developed for the sequential linkage from N-acetylenethio phthalimides, naturally occurring thiols and readily available azides. This method has been successfully applied to the construction of drug hybrids, peptide modification and glycosylation. Furthermore, by the design of diacetylenethio phthalimide as a platform molecule, trifunctional conjugants were sequentially linked through independent Ir-AAC, disulfuration and Cu-AAC reaction for hydrophobic tagging ternary PROTACs.

A whispering-gallery scanning microprobe for Raman spectroscopy and imaging

Optical whispering-gallery-mode microsensors are a promising platform for many applications,such as biomedical monitoring,magnetic sensing,and vibration detection.However,like many other micro/nanosensors,they cannot simultaneously have two critical properties–ultrahigh sensitivity and large detection area,which are desired for most sensing applications.Here,we report a novel scanning whispering-gallery-mode microprobe optimized for both features and demonstrate enhanced Raman spectroscopy,providing high-specificity information on molecular fingerprints that are important for numerous sensing applications.Combining the superiorities of whispering-gallery modes and nanoplasmonics,the microprobe exhibits a two-orders-of-magnitude sensitivity improvement over traditional plasmonics-only enhancement;this leads to molecular detection demonstrated with stronger target signals but less optical power required than surface-enhanced-Raman-spectroscopy substrates.Furthermore,the scanning microprobe greatly expands the effective detection area and realizes two-dimensional micron-resolution Raman imaging of molecular distribution.The versatile and ultrasensitive scanning microprobe configuration will thus benefit material characterization,chemical imaging,and quantum-enhanced sensing.

Total Synthesis of Trabectedin,Lurbinectedin,and Renieramycin T

Trabectedin and lurbinectedin are therapeutic antitumor pharmaceuticals approved by the Food and Drug Administration for treating soft tissue sarcomas and metastatic small cell lung cancer and have been facing synthesis challenges over the past three decades.In this report,the total synthesis of trabectedin,lurbinectedin,and renieramycin T were accomplished in 22-27 steps.The synthetic strategy features stereocontrolled Pictet-Spengler(PS)reaction leading to the multisubstituted tetrahydroisoquinoline fragment(DE ring),aldol condensation for C4-C10 bond formation,and a second PS cyclization with asymmetric oxomalonate for the fully substituted B ring,in which palladium complex-induced stereoselectivity is achieved via decarboxylative protonation anchoring the C1 stereocenter.The pentacyclic skeleton(A-E)was efficiently effectuated at a gramscale,displaying superior potential for further drug development.

Parallel photoreactor development with enhanced photon efficiency and reproducibility based on laws of optics

A lab-scale parallel photoreactor model has been developed for broad applications in organic chemistry.Position,angle,and distance in the reactor are systematically optimized for achieving high reproducibility under the guidance of the Inverse Square Law and Lambert’s Cosine Law,which were first applied in the design of the photoreactor.Improvement of photon efficiency is realized via 3-point irradiation and broad-band light reflector of aluminum.Photon flux is measured with an optical power meter with its display and adjustment suggested being integrated into the photoreactor for the first time.

Pd-Catalyzed C-S Cyclization via C-H Functionalization Strategy： Access to Sulfur-containing Benzoheterocyclics

A C-H sulfurated cyclization protocol starting from thioacetates is developed for straightforward construction of sulfur-containing benzo- heterocyclics. The diversiform functional dihydrobenzothiophenes and thiochromans were comprehensively achieved through the Pd-catalyzed carbon- sulfur cyclization. Mechanistic studies indicated that C-H bond cleavage was involved in the rate-determining step. [1]Benzothieno-[3,2-b]- [1]benzothiophene （BTBT） and benzo[b]thieno[2,3-d]thiophene （BTT） were efficiently established as the well-known organic field-effect transistor （OFET） material molecules through this methodology.

Optothermal dynamics in whispering-gallery microresonators

Optical whispering-gallery-mode microresonators with ultrahigh quality factors and small mode volumes have played an important role in modern physics.They have been demonstrated as a diverse platform for a wide range of applications in photonics,such as nonlinear optics,optomechanics,quantum optics,and information processing.Thermal behaviors induced by power build-up in the resonators or environmental perturbations are ubiquitous in high-quality-factor whispering-gallery-mode resonators and have played an important role in their operation for various applications.In this review,we discuss the mechanisms of laser-field-induced thermal nonlinear effects,including thermal bistability and thermal oscillation.With the help of the thermal bistability effect,optothermal spectroscopy and optical nonreciprocity have been demonstrated.By tuning the temperature of the environment,the resonant mode frequency will shift,which can also be used for thermal sensing/tuning applications.The thermal locking technique and thermal imaging mechanisms are discussed briefly.Finally,we review some techniques employed to achieve thermal stability in a high-quality-factor resonator system.

Visible light-promoted, iodine-catalyzed selenoalkoxylation of olefins with diselenides and alcohols in the presence of hydrogen peroxide/air oxidant: an efficient access to α-alkoxyl selenides

Under iodine-catalyzed and visible light-irradiated aerobic conditions, selenoalkoxylation of olefins with diselenides and alcohols can be efficiently achieved to afford the useful α-alkoxyl selenides in the presence of only 0.5 equiv. of H_2O_2. Controlling the sub-stoichiometric H_2O_2 amount is crucial to avoid the non-selective over-oxidation of the diselenides that leads to the ineffective hyper-valent selenium compounds. Meanwhile, under visible light irradiation, the green, safe, and low-cost air can work as a supplemental mild oxidant in the reaction to ensure selective oxidation of the diselenides, full conversion of the reactants, and ultimately good yield of the products.

Surface-enhanced Raman scattering on dielectric microspheres with whispering gallery mode resonance

Conventionally, metallic nanostructures are used for surface-enhanced Raman spectroscopy(SERS), but recently there has been increasing interest in the enhancement of Raman scattering from dielectric substrates due to their improved stability and biocompatibility compared with metallic substrates. Here, we report the observation of enhanced Raman scattering from rhodamine 6 G molecules coated on silica microspheres. We excite the whispering gallery modes(WGMs) supported in the microspheres with a tapered fiber coupler for efficient WGM excitation, and the Raman enhancement can be attributed to the WGM mechanism. Strong resonance enhancement in pump laser intensity and modified Raman emission from the Purcell effect in the microsphere resonator are observed from the experiment and compared with theoretical results. A total Raman enhancement factor of 1.4 × 10~4 is observed, with contribution mostly from the enhancement in pump laser intensity. Our results show that, with an efficient pumping scheme, dielectric microspheres are a viable alternative to metallic SERS substrates.

The application of sulfur-containing peptides in drug discovery

In recent decades, peptides as potential drugs were more and more explored with the development of non-oral medicine. There into, sulfur-containing peptide is one of the most popular aspects in peptide drugs due to the introduction of sulfur atoms leading unique properties.The purpose of the present review is to focus on the discovery of various sulfur-containing peptides with particular emphasis on their pharmacological mechanisms. This review is organized according to the structures of the sulfurcontaining peptides.

Straightforward Sulfonamidation via Metabisulfite-Mediated CrossCoupling of Nitroarenes and Boronic Acids under Transition-Metal-Free Conditionst

of main observation and conclusion A straightforward multicomponent sufonamidation of nitroarenes,sodium metabisulfite and boronicacids was established under transition-mnetal-free conditions to access diverse sulfonamides from readily avilable and low-cost materials modularv.Inorganic salt sodium metabisulfite not only served as a sulfur dioxide source,but also played a key role for both activator and reductant duringsulfonamidation.Notably,naturlly occuring biomolecules and pharmaceuticals with multiple heteroatorms and sensitive functional groups were intensivly investigated in this transformtion providing versatile sulionamides collectively,further mechanistic studies demonstrated that nitrosoarene is thekey intermediate,and the activation of boronic acid is the rate-determining step in the transformation.

A strong robustness open-circuit fault diagnosis strategy for novel fault-tolerant electric drive system based on d-q-axis current signal

To diagnose the Open-Circuit(OC)fault in the novel fault-tolerant electric drive system,based on d-q-axis current signal,a strong robustness diagnosis strategy is proposed and investigated.Fewer independent power supplies and converters are required in the novel fault-tolerant electric drive system based on Dual-Winding Permanent Magnet Motor(DWPMM),and the system’s reliability,usage ratio and power density have been improved compared to the conventional fault-tolerant motor drive system.However,the novel fault-tolerant electric drive system has the OC fault diagnostic false alarms issue when load changes suddenly or under light-load condition.And it lacks the research on the diagnostic method when the system encounters intermittent OC fault in power switches.By theory derivation,simulation and experimental verification,it can be concluded that the proposed strong robustness OC fault diagnosis strategy based on d-q-axis current signal can overcome the OC fault diagnostic false alarms issue when load changes suddenly or under light-load condition.And it can detect and locate the OC fault of single-phase winding in real time,and diagnose the intermittent OC fault of power switches.

Synergistic Catalysis of Se and Cu for the Activation of α-H of Methyl Ketones with Molecular Oxygen/Alcohol to Produce α-Keto Acetals

Summary of main observation and conclusion Selenium and copper synergistically catalyzed the oxidation/alkoxylation of methyl ketones to synthesize a-keto acetals directly.Using 02 as oxidant and alcohol as solvent and alkoxylation reagent,the reaction is practical from industrial viewpoint.Mechanistic studies revealed that copper promoted the oxidation of organoselenium intermediates with O2 to allow the key rearrangement and selenoxide syn-elim-ination regenerating the catalytically active organoselenium species.

Full-Spectrum Fluoromethyl Sulfonation via Modularized Multicomponent Coupling

Modular free-assembly construction of mono-,di-,and tri-fluoromethyl sulfones was comprehensively achieved by a combination of halides,a sulfur dioxide surrogate,and halofluorocarbons.The industrial raw material thiourea dioxide served as the sulfur dioxide source,combined with readily available fluorocarbon sources such as 2-bromo-2-fluoroacetate and chlorodifluoromethane(ClCF_(2)H,Freon)employed as fluoromethyl reagents.Notably,four methyl sulfone-containing pharmaceuticals were modified into three types of fluoromethyl sulfones,displaying their great potential for drug discovery via the current strategy.Mechanistic studies further demonstrated that C-F…H-N interactions between thiourea dioxide and halofluorocarbons play a key role in stabilizing monofluoromethyl electrophiles and difluorocarbene species.

Transition-Metal-Free Reductive Cross-Coupling Employing Metabisulfite as a Connector:General Construction of Alkyl–Alkyl Sulfones

A multicomponent reductive cross-coupling of unactivated alkyl halides and alkyl tosylates connected via sodium metabisulfite was established for the general construction of alkyl-alkyl sulfones.Neither a metal catalyst nor a metal reductant is required in this“green”reductive cross-coupling.Inorganic sodium metabisulfite served as both the sulfur dioxide source and the robust connector.