Molecular Structure Tailoring of Organic Spacers for High‑Performance Ruddlesden–Popper Perovskite Solar Cells

Layer-structured Ruddlesden–Popper(RP)perovskites(RPPs)with decent stability have captured the imagination of the photovoltaic research community and bring hope for boosting the development of perovskite solar cell(PSC)technology.However,two-dimensional(2D)or quasi-2D RP PSCs are encountered with some challenges of the large exciton binding energy,blocked charge transport and poor film quality,which restrict their photovoltaic performance.Fortunately,these issues can be readily resolved by rationally designing spacer cations of RPPs.This review mainly focuses on how to design the molecular structures of organic spacers and aims to endow RPPs with outstanding photovoltaic applications.We firstly elucidated the important roles of organic spacers in impacting crystallization kinetics,charge transporting ability and stability of RPPs.Then we brought three aspects to attention for designing organic spacers.Finally,we presented the specific molecular structure design strategies for organic spacers of RPPs aiming to improve photovoltaic performance of RP PSCs.These proposed strategies in this review will provide new avenues to develop novel organic spacers for RPPs and advance the development of RPP photovoltaic technology for future applications.

Decoding molecular mechanisms:brain aging and Alzheimer's disease

The complex morphological,anatomical,physiological,and chemical mechanisms within the aging brain have been the hot topic of research for centuries.The aging process alters the brain structure that affects functions and cognitions,but the worsening of such processes contributes to the pathogenesis of neurodegenerative disorders,such as Alzheimer's disease.Beyond these observable,mild morphological shifts,significant functional modifications in neurotransmission and neuronal activity critically influence the aging brain.Understanding these changes is important for maintaining cognitive health,especially given the increasing prevalence of age-related conditions that affect cognition.This review aims to explore the age-induced changes in brain plasticity and molecular processes,differentiating normal aging from the pathogenesis of Alzheimer's disease,thereby providing insights into predicting the risk of dementia,particularly Alzheimer's disease.

Molecular simulation study of the microstructures and properties of pyridinium ionic liquid[HPy][BF_(4)]mixed with acetonitrile

The microstructures and thermodynamic properties of mixed systems comprising pyridinium ionic liquid[HPy][BF_(4)]and acetonitrile at different mole fractions were studied using molecular dynamics simulation in this work.The following properties were determined:density,self-diffusion coefficient,excess molar volume,and radial distribution function.The results show that with an increase in the mole fraction of[HPy][BF_(4)],the self-diffusion coefficient decreases.Additionally,the excess molar volume initially decreases,reaches a minimum,and then increases.The rules of radial distribution functions(RDFs)of characteristic atoms are different.With increasing the mole fraction of[HPy][BF_(4)],the first peak of the RDFs of HA1-F decreases,while that of CT6-CT6 rises at first and then decreases.This indicates that the solvent molecules affect the polar and non-polar regions of[HPy][BF_(4)]differently.

Novel umami peptides from two Termitomyces mushrooms and molecular docking to the taste receptor T1R1/T1R3

Wild edible Termitomyces mushrooms are popular in Southwest China and umami is important flavor qualities of edible mushrooms.This study aimed to understand the umami taste of Termitomyces intermedius and Termitomyces aff.bulborhizus.Ten umami peptides from aqueous extracts were separated using a Sephadex G-15 gel filtration chromatography.The intense umami fraction was evaluated by both sensory evaluation and electronic tongue.They were identified as KLNDAQAPK,DSTDEKFLR,VGKGAHLSGEH,MLKKKKLA,SLGFGGPPGY,TVATFSSSTKPDD,AMDDDEADLLLLAM,VEDEDEKPKEK,SPEEKKEEET and PEGADKPNK.Seven peptides,except VEDEDEKPKEK,SPEEKKEEET and PEGADKPNK were selectively synthesized to verify their taste characteristics.All these 10 peptides had umami or salt taste.The 10 peptides were conducted by molecular docking to study their interaction with identified peptides and the umami taste receptor T1R1/T1R3.All these 10 peptides perfectly docked the active residues in the T1R3 subunit.Our results provide theoretical basis for the umami taste and address the umami mechanism of two wild edible Termitomyces mushrooms.

Molecular Mechanism and Molecular Design of Lubricating Oil Antioxidants

To overcome the limitations of traditional experimental“trial and error”methods in lubricant additive design,a new molecular design method based on molecular structure parameters is established here.The molecular mechanism of the antioxidant reaction of hindered phenol,diphenylamine,and alkyl sulfide are studied via molecular simulations.Calculation results show that the strong electron-donating ability and high hydrogen-donating activity of the antioxidant molecule and the low hydrogen-abstracting activity of free radicals formed after dehydrogenation are the internal molecular causes of the shielding of phenol and diphenylamine from scavenging peroxy free radicals,and the strong electron-donating ability is the internal molecular cause of the high activity of thioether in decomposing alkyl hydrogen peroxide.Based on this antioxidant molecular mechanism,a molecular design rule of antioxidant is proposed,namely“high EHOMO,large Q(S),low bond dissociation energy BDE(O—H)and BDE(N—H)”.Two new antioxidants,PAS-I and PAS-II,are designed and prepared by chemical bonding of hindered phenol,diphenylamine,and sulfur atoms.Experimental results show that these antioxidants both have excellent antioxidant effects in lubricating oil,and that PAS-II is the superior antioxidant,consistent with theoretical predictions.

Molecular mechanisms underlying microglial sensing and phagocytosis in synaptic pruning

Microglia are the main non-neuronal cells in the central nervous system that have important roles in brain development and functional connectivity of neural circuits.In brain physiology,highly dynamic microglial processes are facilitated to sense the surrounding environment and stimuli.Once the brain switches its functional states,microglia are recruited to specific sites to exert their immune functions,including the release of cytokines and phagocytosis of cellular debris.The crosstalk of microglia between neurons,neural stem cells,endothelial cells,oligodendrocytes,and astrocytes contributes to their functions in synapse pruning,neurogenesis,vascularization,myelination,and blood-brain barrier permeability.In this review,we highlight the neuron-derived“find-me,”“eat-me,”and“don't eat-me”molecular signals that drive microglia in response to changes in neuronal activity for synapse refinement during brain development.This review reveals the molecular mechanism of neuron-microglia interaction in synaptic pruning and presents novel ideas for the synaptic pruning of microglia in disease,thereby providing important clues for discovery of target drugs and development of nervous system disease treatment methods targeting synaptic dysfunction.

Risk stratification for radioactive iodine refractoriness using molecular alterations in distant metastatic differentiated thyroid cancer

Objective: Patients with radioactive iodine-refractory differentiated thyroid cancer(RAIR-DTC) are often diagnosed with delay and constrained to limited treatment options. The correlation between RAI refractoriness and the underlying genetic characteristics has not been extensively studied.Methods: Adult patients with distant metastatic DTC were enrolled and assigned to undergo next-generation sequencing of a customized 26-gene panel(Thyro Lead). Patients were classified into RAIR-DTC or non-RAIR groups to determine the differences in clinicopathological and molecular characteristics. Molecular risk stratification(MRS) was constructed based on the association between molecular alterations identified and RAI refractoriness, and the results were classified as high, intermediate or low MRS.Results: A total of 220 patients with distant metastases were included, 63.2% of whom were identified as RAIRDTC. Genetic alterations were identified in 90% of all the patients, with BRAF(59.7% vs. 17.3%), TERT promoter(43.9% vs. 7.4%), and TP53 mutations(11.5% vs. 3.7%) being more prevalent in the RAIR-DTC group than in the non-RAIR group, except for RET fusions(15.8% vs. 39.5%), which had the opposite pattern. BRAF and TERT promoter are independent predictors of RAIR-DTC, accounting for 67.6% of patients with RAIR-DTC. MRS was strongly associated with RAI refractoriness(P<0.001), with an odds ratio(OR) of high to low MRS of 7.52 [95%confidence interval(95% CI), 3.96-14.28;P<0.001] and an OR of intermediate to low MRS of 3.20(95% CI,1.01-10.14;P=0.041).Conclusions: Molecular alterations were associated with RAI refractoriness, with BRAF and TERT promoter mutations being the predominant contributors, followed by TP53 and DICER1 mutations. MRS might serve as a valuable tool for both prognosticating clinical outcomes and directing precision-based therapeutic interventions.

Analysis of CH_(4) and H_(2) Adsorption on Heterogeneous Shale Surfaces Using aMolecular Dynamics Approach

Determining the adsorption of shale gas on complex surfaces remains a challenge in molecular simulation studies.Difficulties essentially stem from the need to create a realistic shale structure model in terms of mineral heterogeneityand multiplicity.Moreover,precise characterization of the competitive adsorption of hydrogen andmethane in shale generally requires the experimental determination of the related adsorptive capacity.In thisstudy,the adsorption of adsorbates,methane(CH_(4)),and hydrogen(H_(2))on heterogeneous shale surface modelsof Kaolinite,Orthoclase,Muscovite,Mica,C_(60),and Butane has been simulated in the frame of a moleculardynamic’s numerical technique.The results show that these behaviors are influenced by pressure and potentialenergy.On increasing the pressure from 500 to 2000 psi,the sorption effect for CH_(4)significantly increasesbut shows a decline at a certain stage(if compared to H_(2)).The research findings also indicate that raw shalehas a higher capacity to adsorb CH_(4)compared to hydrogen.However,in shale,this difference is negligible.

Facile synthesis of Cu-doped manganese oxide octahedral molecular sieve for the efficient degradation of sulfamethoxazole via peroxymonosulfate activation

Advanced processes for peroxymonosulfate(PMS)-based oxidation are efficient in eliminating toxic and refractory organic pol-lutants from sewage.The activation of electron-withdrawing HSO_(5)^(-)releases reactive species,including sulfate radical(·SO_(4)^(-)),hydroxyl radical(·OH),superoxide radical(·O_(2)^(-)),and singlet oxygen(1O_(2)),which can induce the degradation of organic contaminants.In this work,we synthesized a variety of M-OMS-2 nanorods(M=Co,Ni,Cu,Fe)by doping Co^(2+),Ni^(2+),Cu^(2+),or Fe^(3+)into manganese oxide oc-tahedral molecular sieve(OMS-2)to efficiently remove sulfamethoxazole(SMX)via PMS activation.The catalytic performance of M-OMS-2 in SMX elimination via PMS activation was assessed.The nanorods obtained in decreasing order of SMX removal rate were Cu-OMS-2(96.40%),Co-OMS-2(88.00%),Ni-OMS-2(87.20%),Fe-OMS-2(35.00%),and OMS-2(33.50%).Then,the kinetics and struc-ture-activity relationship of the M-OMS-2 nanorods during the elimination of SMX were investigated.The feasible mechanism underly-ing SMX degradation by the Cu-OMS-2/PMS system was further investigated with a quenching experiment,high-resolution mass spec-troscopy,and electron paramagnetic resonance.Results showed that SMX degradation efficiency was enhanced in seawater and tap water,demonstrating the potential application of Cu-OMS-2/PMS system in sewage treatment.

Exploring the taste presentation and receptor perception mechanism of salty peptides from Stropharia rugosoannulata based on molecular dynamics and thermodynamics simulation

The taste presentation and receptor perception mechanism of the salty peptide of Stropharia rugosoannulata were predicted and verified using peptide omics and molecular interaction techniques.The combination of aspartic acid(D)and glutamic acid(E),or peptide fragments composed of arginine(R),constitute the characteristic taste structural basis of salty peptides of S.rugosoannulata.The taste intensity of the salty peptide positively correlates with its concentration within a specific concentration range(0.25–1.0 mg/mL).The receptor more easily recognizes the first amino acid residue at the N-terminal of salty peptides and the aspartic acid residue in the peptides.GLU513,ASP707,and VAL508 are the critical amino acid residues for the receptor to recognize salty peptides.TRPV1 is specifically the receptor for recognizing salty peptides.Hydrogen bonds and electrostatic interactions are the main driving forces for the interactions between salty peptides and TRPV1 receptors.KSWDDFFTR has the most potent binding capacity with the receptor and has tremendous potential for application in sodium salt substitution.This study confirmed the taste receptor that specifically recognizes salty peptides,analyzed the receptor-peptide binding interaction,and provided a new idea for understanding the taste receptor perception of salty peptides.

Development of in situ characterization techniques in molecular beam epitaxy

Ex situ characterization techniques in molecular beam epitaxy(MBE)have inherent limitations,such as being prone to sample contamination and unstable surfaces during sample transfer from the MBE chamber.In recent years,the need for improved accuracy and reliability in measurement has driven the increasing adoption of in situ characterization techniques.These techniques,such as reflection high-energy electron diffraction,scanning tunneling microscopy,and X-ray photoelectron spectroscopy,allow direct observation of film growth processes in real time without exposing the sample to air,hence offering insights into the growth mechanisms of epitaxial films with controlled properties.By combining multiple in situ characterization techniques with MBE,researchers can better understand film growth processes,realizing novel materials with customized properties and extensive applications.This review aims to overview the benefits and achievements of in situ characterization techniques in MBE and their applications for material science research.In addition,through further analysis of these techniques regarding their challenges and potential solutions,particularly highlighting the assistance of machine learning to correlate in situ characterization with other material information,we hope to provide a guideline for future efforts in the development of novel monitoring and control schemes for MBE growth processes with improved material properties.

High adsorption selectivity of activated carbon and carbon molecular sieve boosting CO_(2)/N_(2) and CH_(4)/N_(2) separation

Flue gas and coal bed methane are two important sources of greenhouse gases.Pressure swing adsorption process has a wide range of application in the field of gas separation,and the selection of adsorbent is crucial.In this regard,in order to assess the better adsorbent for separating CO_(2) from flue gas and CH_(4) from coal bed methane,adsorption isotherms of CO_(2),CH_(4) and N_(2) on activated carbon and carbon molecular sieve are measured at 303.15,318.15 and 333.15 K,and up to 250 kPa.The experimental data fit better with Langmuir 2 compared to Langmuir 3 and Langmuir-Freundlich models,and Clausius-Clapeyron equation was used to calculate the isosteric heat.Both the order of the adsorbed amount and the adsorption heat on the two adsorbents are CO_(2)>CH_(4)>N_(2).The adsorption kinetics are calculated by the pseudo-first kinetic model,and the order of adsorption rates on activated carbon is N_(2)-CH_(4)>CO_(2),while on carbon molecular sieve,it is CO_(2)-N_(2)>CH_(4).It is shown that relative molecular mass and adsorption heat are the primary effect on kinetics for activated carbon,while kinetic diameter is the main resistance factor for carbon molecular sieve.Moreover,the adsorption selectivity of CH_(4)/N_(2) and CO_(2)/N_(2) were estimated with the ideal adsorption solution theory,and carbon molecular sieve performed best at 318.15 K for both CO_(2) and CH_(4) separation.The study suggested that activated carbon is a better choice for separating flue gas and carbon molecular sieve can be a strong candidate for separating coal bed methane.

Assessment of molecular markers and marker-assisted selection for drought tolerance in barley(Hordeum vulgare L.)

This review updates the present status of the field of molecular markers and marker-assisted selection(MAS),using the example of drought tolerance in barley.The accuracy of selected quantitative trait loci(QTLs),candidate genes and suggested markers was assessed in the barley genome cv.Morex.Six common strategies are described for molecular marker development,candidate gene identification and verification,and their possible applications in MAS to improve the grain yield and yield components in barley under drought stress.These strategies are based on the following five principles:(1)Molecular markers are designated as genomic‘tags’,and their‘prediction’is strongly dependent on their distance from a candidate gene on genetic or physical maps;(2)plants react differently under favourable and stressful conditions or depending on their stage of development;(3)each candidate gene must be verified by confirming its expression in the relevant conditions,e.g.,drought;(4)the molecular marker identified must be validated for MAS for tolerance to drought stress and improved grain yield;and(5)the small number of molecular markers realized for MAS in breeding,from among the many studies targeting candidate genes,can be explained by the complex nature of drought stress,and multiple stress-responsive genes in each barley genotype that are expressed differentially depending on many other factors.

Insight of Natural Compounds Halimane Diterpenoids against Mycobacterium tuberculosis: Virtual Screening, DFT, Drug-Likeness, and Molecular Dynamics Approach

In the purpose to design novel antituberculosis (anti-TB) drugs agents against Mycobacterium tuberculosis (Mtb), we have built a molecular library around 42 Halimane Diterpenoids isolated from natural sources. Two Mtb enzymes drug targets (Mtb Mycothiol S-transferase and Mtb Homoserine transacetylase) have been adopted. The pharmacological potential was investigated through molecular docking, molecular dynamics simulation, density functional theory (gas phase and water) and ADMET analysis. Our results indicate that (2R,5R,6S)-1,2,3,4,5,6,7,8-octahydro-5-((E)-5-hydroxy-3-methylpent-3-enyl)-1,1,5,6-tetramethylnaphtha-lene-2-ol (compound 20) has displays higher docking score with each of the selected drug targets. In addition, this molecule exhibits a satisfactory drug potential activity and a good chemical reactivity. Its improved kinetic stability in the Mtb Mycothiol S-transferase enzyme reflects its suitability as a novel inhibitor of Mtb growth. This molecule has displayed a good absorption potential. Our results also show that its passive passage of the intestinal permeability barrier is more effective than that of first-line treatments (ethambutol, isoniazid). In the same way, this anti-TB druglikeness has shown to be able to cross the blood brain barrier.

Molecular Identification of Mycobacterium Strains Responsible of Bovine Tuberculosis Cases in Bobo-Dioulasso Slaughterhouse, Burkina Faso

Bovine tuberculosis (bTB) is an endemic zoonosis significantly affects animal health in Burkina Faso. The primary causative agent is Mycobacterium tuberculosis (M. tuberculosis) complex, mainly M. bovis. Cattle are considered as natural reservoir of M. bovis. However, in Burkina Faso, the circulation of these strains remains poorly understood and documented. This study aimed to identify and characterize Mycobacterium strains from suspected carcasses during routine meat inspection at Bobo-Dioulasso refrigerated slaughterhouse. A prospective cross-sectional study was conducted from January 2021 to December 2022 on cases of seizures linked to suspected bovine tuberculosis. Microbiological and molecular analyzes were used for mycobacterial strain isolation and characterization. Out of 50 samples, 24% tested positive by microscopy and 12% by culture. Molecular analysis identified 6 strains of Mycobacteria, exclusively Mycobacterium bovis specifically the subspecies bovis (Mycobacterium bovis subsp bovis). In conclusion, M. bovis subsp bovis is the primary agent responsible for bovine tuberculosis in Bobo-Dioulasso. Continuous monitoring of mycobacterial strains is therefore necessary for the effective control of this pathology in the local cattle population.

The development and implementation of pathological parameters and molecular testing impact prognosis of colorectal adenocarcinoma

Objective:This study aims to analyze how changes in pathological diagnosis practice and molecular detection technology have affected clinical outcomes for colorectal cancer(CRC)patients in Fudan University Shanghai Cancer Center(FUSCC).Methods:This retrospective cohort study analyzed 21,141 pathologically confirmed CRC cases diagnosed at FUSCC from 2008 to 2020.Patients were divided into five groups for different analytical purposes:(1)the before vs.since 2014 groups to analyze the influence of the changes in the classification criteria of pT3 and pT4 staging on the survival of patients;(2)the partial vs.total mesorectal excision(TME)groups to analyze whether evaluation of completeness of the mesorectum have impact on the survival of patients;(3)the tumor deposit(TD)(+)N0 vs.TD(+)N1c groups to analyze the influence of the changes in the pN staging on the survival of patients with positive TD and negative regional lymph node metastasis(LNM);(4)the before vs.since 2013 groups to analyze the influence of the changes in the testing process of deficient mismatch repair on the survival of patients;and(5)the groups with vs.without RAS/BRAF gene mutation testing to analyze the influence of these testing on the survival of patients.Patients’clinicopathological parameters,including age at diagnosis,sex,tumor size,location,differentiation,mucinous subtype,TD,lymphovascular invasion,perineural invasion,tumor depth,LNM and distant metastasis,and tumor-node-metastasis(TNM)stage,were compared between groups.Kaplan-Meier analysis with log rank method was performed for patients’overall survival(OS)and disease-free survival(DFS)analyses.Results:In pathological reports,there were three parameter changes that impacted patient outcomes.Firstly,changes in the pT staging criteria led to a shift of the ratio of patients with stage pT3 to stage pT4 from 1:110.9 to 1:0.26.In comparison to patients admitted before 2014(n=4,754),a significant difference in prognosis between pT3 and pT4 stages was observed since 2014(n=9,965).Secondly,we began to evaluate the completeness of the mesorectum since 2016.As a result,91.0%of patients with low rectal cancer underwent TME(n=4,111)surgery,and patients with TME had significantly better OS compared with partial mesorectal excision(PME,n=409).Thirdly,we began to stage TD(+)LNM(-)as N1c since 2017.The results showed that N1c(n=127)but not N0(n=39)can improve the prognosis of patients without LNM and distal metastasis.In molecular testing,there have been three and five iterations of updates regarding mismatch repair(MMR)/microsatellite instability(MSI)status and RAS/BRAF gene mutation detection,respectively.The standardization of MMR status testing has sharply decreased the proportion of deficient MMR(dMMR)patients(from 32.5%to 7.4%)since 2013.The prognosis of patients underwent MMR status testing since 2013(n=867)were significantly better than patients before 2013(n=1,313).In addition,detection of RAS/BRAF gene mutation status(n=5,041)resulted in better DFS but not OS,for patients with stage I-III disease(n=16,557).Conclusion:Over the past few decades,updates in elements in pathological reports,as well as the development of standardized tests for MMR/MSI status and RAS/BRAF gene mutations have significantly improved patient outcomes.

Molecular phylogeny and taxonomy of Phlomoides(Lamiaceae subfamily Lamioideae)in China:Insights from molecular and morphological data

Phlomoides,with 150-170 species,is the second largest and perhaps most taxonomically challenging genus within the subfamily Lamioideae(Lamiaceae).With about 60 species,China is one of three major biodiversity centers of Phlomoides.Although some Phlomoides species from China have been included in previous molecular phylogenetic studies,a robust and broad phylogeny of this lineage has yet to be completed.Moreover,given the myriad new additions to the genus,the existing infrageneric classification needs to be evaluated and revised.Here,we combine molecular and morphological data to investigate relationships within Phlomoides,with a focus on Chinese species.We observed that plastid DNA sequences can resolve relationships within Phlomoides better than nuclear ribosomal internal and external transcribed spacer regions(nrITS and nrETS).Molecular phylogenetic analyses confirm the monophyly of Phlomoides,but most previously defined infrageneric groups are not monophyletic.In addition,morphological analysis demonstrates the significant taxonomic value of eight characters to the genus.Based on our molecular phylogenetic analyses and morphological data,we establish a novel section Notochaete within Phlomoides,and propose three new combinations as well as three new synonyms.This study presents the first molecular phylogenetic analyses of Phlomoides in which taxa representative of the entire genus are included,and highlights the phylogenetic and taxonomic value of several morphological characters from species of Phlomoides from China.Our study suggests that a taxonomic revision and reclassification for the entire genus is necessary in the future.

Distinct molecular targets of ProEGCG from EGCG and superior inhibition of angiogenesis signaling pathways for treatment of endometriosis

Endometriosis is a common chronic gynecological disease with endometrial cell implantation outside the uterus.Angiogenesis is a major pathophysiology in endometriosis.Our previous studies have demonstrated that the prodrug of epigallocatechin gallate(ProEGCG)exhibits superior anti-endometriotic and anti-angiogenic effects compared to epigallocatechin gallate(EGCG).However,their direct binding targets and underlying mechanisms for the differential effects remain unknown.In this study,we demonstrated that oral ProEGCG can be effective in preventing and treating endometriosis.Additionally,1D and 2D Proteome Integral Solubility Alteration assay-based chemical proteomics identified metadherin(MTDH)and PX domain containing serine/threonine kinase-like(PXK)as novel binding targets of EGCG and ProEGCG,respectively.Computational simulation and BioLayer interferometry were used to confirm their binding affinity.Our results showed that MTDH-EGCG inhibited protein kinase B(Akt)-mediated angiogenesis,while PXK-ProEGCG inhibited epidermal growth factor(EGF)-mediated angiogenesis via the EGF/hypoxia-inducible factor(HIF-1a)/vascular endothelial growth factor(VEGF)pathway.In vitro and in vivo knockdown assays and microvascular network imaging further confirmed the involvement of these signaling pathways.Moreover,our study demonstrated that ProEGCG has superior therapeutic effects than EGCG by targeting distinct signal transduction pathways and may act as a novel antiangiogenic therapy for endometriosis.

Theoretical Design of Molecular Diode Based on Thiol-and Amino-Terminated Molecules

Utilizing density functional theory(DFT)and non-equilibrium Green's function,we systematically studied the electrical transport and rectification properties of thiol-and amino-terminated molecules embedded in graphene nanoribbons.We firstly found the thiol-terminated moleculesshowbetterelectron transport properties compared to the amino-terminated,which can be attributed to the strong electronwithdrawing ability and favorable coupling effects.Secondly,the symmetrical molecules show almost symmetrical current-voltage(-V)curves and exhibit negligible rectification effects.On the other hand,the asymmetrical molecules exhibit asymmetrical I-V curves and better rectification performance.The rectification effect is closely related to molecular asymmetry degrees.For example,the rectification ratio of asymmetric N6((E)-N1-(3-aminopropyl)-but-2-ene-1,4-diamine)molecule is much smaller than the N4(5-phenylthiazole-2,4-diamine)and N5(2,6-diaminohexane-1,1,5-triol)molecules.Furthermore,we found the rectification ratio of the asymmetrical amino-terminated molecules can reach 400,while the biggest rectification ratio of the thiol-terminated molecule can only reach 45.These findings offer crucial insights for future graphene molecular electronic device design.

Molecular Dynamics for Spin Systems

We present a microscopic simulation of particles with time-dependent spins,where different interaction and density are considered.Ferromagnetism has been observed for the attractive spin-spin interaction,while antiferromagnetism and paramagnetism have been observed in different density region for the repulsive spin-spin interaction.The method developed here should be extended to include spin-color interaction into“color molecular dynamics”.