CmMYB3-like negatively regulates anthocyanin biosynthesis and flower color formation during the post-flowering stage in Chrysanthemum morifolium

Color fading caused by a decrease in anthocyanin accumulation during the post-flowering stage significantly affects postharvest quality of chrysanthemum.However,the underlying mechanism by which anthocyanin accumulation decreases during the post-flowering stage still unclear,which greatly restricts design of molecular breeding in chrysanthemum.Here,a chrysanthemum SG7 R2R3 MYB transcription factor(TF),CmMYB3-like,was identified to have a function in regulating anthocyanin biosynthesis during the post-flowering stage.Quantitative real time PCR(qRT-PCR)assays showed that the expression of CmMYB3-like was gradually downregulated when anthocyanin content increased during the flowering stage and was significantly upregulated during the post-flowering stage.Genetic transformation of chrysanthemum and dual-luciferase assays in N.benthamiana leaves showed that CmMYB3-like suppressed anthocyanin accumulation by inhibiting the transcription of CmCHS and CmANS directly and that of CmF3H indirectly.However,overexpression or suppression of CmMYB3-like did not affect the biosynthesis of flavones or flavonols.Genetic transformation of chrysanthemum revealed that the overexpression of CmMYB3-like inhibited anthocyanin accumulation,but its suppression prevented the decrease in anthocyanin accumulation during the post-flowering stage.Our results revealed a crucial role of CmMYB3-like in regulating the color of petals during the post-flowering stage and provided a target gene for molecular design breeding to improve the postharvest quality of chrysanthemum.

Abiotic stress treatment reveals expansin like A gene OfEXLA1 improving salt and drought tolerance of Osmanthus fragrans by responding to abscisic acid

Sweet osmanthus(Osmanthus fragrans) is a having general approval aromatic tree in China that is widely applied to landscaping and gardening. However, the evergreen tree adaptability is limited by many environmental stresses. Currently, limited information is available regarding the genetic analysis and functional identification of expansin genes in response to abiotic stress in sweet osmanthus. In this study, a total of 29 expansin genes were identified and divided into four groups by genome-wide analysis from the sweet osmanthus genome. Transcriptome and quantitative Real-time PCR analysis showed that the cell wall-localized protein expansin-like A(OfEXLA1) gene was significantly induced by salt and drought treatment. Histochemical GUS staining of transgenic Arabidopsis lines in which GUS activity was driven with the OfEXLA1 promoter, GUS activity was significantly induced by salt, drought, and exogenous abscisic acid(ABA). In yeast, we found OfEXLA1overexpression significantly improved the population of cells compared with wild-type strains after NaCl and polyethylene glycol(PEG)treatment. Additionally, OfEXLA1 overexpression not only promoted plant growth, but also improved the salt and drought tolerance in Arabidopsis. To gain insight into the role of ABA signaling in the regulation of OfEXLA1 improving abiotic tolerance in sweet osmanthus, four differentially expressed ABA Insensitive 5(ABI5)-like genes(OfABL4, OfABL5, OfABL7, and OfABL8) were identified from transcriptome, and dualluciferase(dual-LUC) and yeast one hybrid(Y1H) assay showed that OfABL4 and OfABL5 might bind to OfEXLA1 promoter to accumulate the OfEXLA1 expression by responding to ABA signaling to improve abiotic tolerance in sweet osmanthus. These results provide the information for understanding the molecular functions of expansin-like A gene and molecular breeding of sweet osmanthus in future.

Fault Diagnosis of Power Electronic Circuits Based on Adaptive Simulated Annealing Particle Swarm Optimization

In the field of energy conversion,the increasing attention on power electronic equipment is fault detection and diagnosis.A power electronic circuit is an essential part of a power electronic system.The state of its internal components affects the performance of the system.The stability and reliability of an energy system can be improved by studying the fault diagnosis of power electronic circuits.Therefore,an algorithm based on adaptive simulated annealing particle swarm optimization(ASAPSO)was used in the present study to optimize a backpropagation(BP)neural network employed for the online fault diagnosis of a power electronic circuit.We built a circuit simulation model in MATLAB to obtain its DC output voltage.Using Fourier analysis,we extracted fault features.These were normalized as training samples and input to an unoptimized BP neural network and BP neural networks optimized by particle swarm optimization(PSO)and the ASAPSO algorithm.The accuracy of fault diagnosis was compared for the three networks.The simulation results demonstrate that a BP neural network optimized with the ASAPSO algorithm has higher fault diagnosis accuracy,better reliability,and adaptability and can more effectively diagnose and locate faults in power electronic circuits.

Characteristic of Fresh and Harden Properties of Polyvinyl Alcohol Fibre Reinforced Alkali Activated Composite

Fibre can enhance the mechanical properties of cement-based composites,but fibre also degrades their workability.However,the quantitative effects of fiber content and length-diameter ratio on alkali-activated materials are still unclear.Various aspect ratio,volume fraction of polyvinyl alcohol fibre(PVAF),and various water-binder ratio were employed to prepare a total of 26 groups of fibre reinforced alkali-activated composite(FRAAC).The influence of PVAF fibre factor(product of fiber volume fraction and length-diameter ratio)on flowability,compactness,strength,and crack fractal dimension of FRAAC was researched.The influence of water-binder ratio on the plastic viscosity of FRAAC was more significant than that on the yield stress.When fibre factor was lower than critical value of 150,the influence of fibres could be overlooked.The reason was that the space between fibres was distant,so the flowability of FRAAC was not impacted by PVAF.At this time,fibres were challenging to restrict the cracks in matrix and increase their mechanical properties.When fibre factor was higher than critical value 150 and lower than density packing value 450,the flexural strength,compressive strength and crack fractal dimension of FRAAC were considerably enhanced,and the FRAAC could still flow easily under dead weight.When fibre factor were above 450,noteworthy fibre balling considerably decreased the flowability,leading to poor solidity and reduced compressive strength.Hence,the ideal content of PVAF in alkali activated composite is between 150/(l/d)and 450/(l/d).

A novel transcription factor CmMYB012 inhibits flavone and anthocyanin biosynthesis in response to high temperatures in chrysanthemum

Flavones are among the major colorless pigments synthesized through branches of the flavonoid pathway in plants.However,due to the absence of a gene encoding flavone synthase(FNS)in the model plant Arabidopsis thaliana species,the regulatory mechanism of FNS-catalyzed flavone biosynthesis has rarely been studied in plants.Here,it was found that flavones play a predominant role in the elimination of excess reactive oxygen species(ROS)at high temperatures in colorless plant organs.A novel atypical subgroup 7(SG7)R2R3-MYB transcription factor,CmMYB012,was found to be induced in response to prolonged high temperatures and to inhibit flavone biosynthesis by directly regulating CmFNS.Moreover,CmMYB012 was also found to inhibit anthocyanin biosynthesis by suppressing the expression of CmCHS,CmDFR,CmANS,and CmUFGT.CmMYB012 overexpression exerted a negative in fluence on plant fitness and pink flower color formation,while CmMYB012 suppression had the opposite effect in response to high temperatures.Our findings provide new insights into the mechanisms by which high temperatures regulate the metabolism of flavones and anthocyanins to affect plant fitness and flower color formation.

Daicong solution effects on brain ultrastructure in a rat model of Alzheimer's disease

BACKGROUND： Infusion of kainic acid into the basal nuclei induces neuronal excitotoxicity, degeneration and necrosis, resulting in disturbed learning and memory functions. OBJECTIVE： To explore the effects of different doses of traditional Chinese medicine Daicong solution on brain ultrastructure in a rat model of Alzheimer＇s disease. DESIGN, TIME AND SETTING： The randomized, controlled, cellular morphology experiment was performed at the Shandong Provincial Key Laboratory of Molecular Immunology of Weifang Medical University, China from October 2006 to March 2007. MATERIALS： Fifty healthy, Sprague Dawley rats, aged 22-months, were used to establish rat models of Alzheimer＇s disease. The Morris water maze was prepared at the Pharmacometrics Key Laboratory of Weifang Medical University in Shandong Province of China. Traditional Chinese medicine Daicong solution （crude drug 1 g/mL）, composed of radix ginseng, rehmannia dried rhizome, anemarrhenae and radix astragali, was produced by the Department of Pharmacy of Hospital Affiliated to Weifang Medical University. Kainic acid was provided by Professor Xiuyan Li from Weifang Medical University. METHODS： A total of 40 model rats were equally and randomly divided into four groups： dementia model, low-dose Daicong solution （5 g/kg/d）, moderate-dose Daicong solution （10 g/kg/d）, and high-dose Daicong solution （20 g/kg/d）. An additional 10 healthy rats served as the normal control group. Rats in the dementia model and normal control groups received saline （10 mL/kg/d）. MAIN OUTCOME MEASURES： Neural cell ultrastructure was observed utilizing electron microscopy after 1 month of respective treatments. RESULTS： Compared with the normal control group, electron density and the number of ribosomes were significantly reduced in neuronal cytoplasm, and many lipofuscin grains and vacuole-like changes were observed in mitochondria in the dementia model group. In addition, nuclear chromatin presented with different sizes of plaque-shaped degenerative pathological changes. In the Alzheimer＇s disease rat model, neurons and neuroepithelial cells recovered to normal conditions following treatment with moderate- and high-dose Daicong solution. In the low-dose Daicong group, the condition was slightly improved, but the cytopathic effects were still significant. CONCLUSION： Daicong solution significantly improved neuronal and neuroepithelial pathological ultrastructure in a rat model of Alzheimer＇s disease.

Sex ratio, floral traits, and genetic variation of androdioecious Osmanthus fragrans L. (Oleaceae) and the implications for maintenance of high male frequency

Several examples of androdioecy appear to have evolved from dioecy and have low male frequency(<0.5).However,the evolutionary pathway to androdioecy in Oleaceae may come from hermaphroditism.Osmanthus fragrans L.has a 1:1 sex ratio in nature populations.Significant differences are observed not only in flowering phenology but also in some floral traits between males and hermaphrodites.The protandry in the same population and the protogyny in the same plant may promote the xenogamy between genders.The majority of flower traits related with the pollen production are different between males and hermaphrodites.Males bear more flowering nodes,and more flowers per node,and larger anther in all three populations.This characteristic demonstrated that males have more male advantage than hermaphrodites.Population genetic structure of O.fragrans is genetically homogeneous at the species level,and most variations exist within a population.The percentage of variation among populations(13%)and between males and hermaphrodites(0%)is low.Moreover,genetic differentiation was very low between genders not only among populations but also in the same population.This genetic variation could be attributed to the occurrence of high levels of xenogamy between genders.Therefore,high male frequency and more male fitness advantage in males are the essential conditions for this mating system,which plays an important role during population reproduction and regeneration.The 1:1 sex ratio could be the result of integrative effects of sexual system,mating system,and reproductive success.

Discovering the ultralow thermal conductive A_(2)B_(2)O_(7)-type high-entropy oxides through the hybrid knowle dge-assiste d data-driven machine learning

Lattice engineering and distortion have been considered one kind of effective strategies for discovering advanced materials.The instinct chemical flexibility of high-entropy oxides(HEOs)motivates/accelerates to tailor the target properties through phase transformations and lattice distortion.Here,a hybrid knowledge-assisted data-driven machine learning(ML)strategy is utilized to discover the A_(2)B_(2)O_(7)-type HEOs with low thermal conductivity(κ)through 17 rare-earth(RE=Sc,Y,La-Lu)solutes optimized A-site.A designing routine integrating the ML and high throughput first principles has been proposed to predict the key physical parameter(KPPs)correlated to the targetedκof advanced HEOs.Among the smart-designed 6188(5RE_(0.2))_(2)Zr_(2)O_(7)HEOs,the best candidates are addressed and validated by the princi-ples of severe lattice distortion and local phase transformation,which effectively reduceκby the strong multi-phonon scattering and weak interatomic interactions.Particularly,(Sc_(0.2)Y_(0.2)La_(0.2)Ce_(0.2)Pr_(0.2))_(2)Zr_(2)O_(7)with predictedκbelow 1.59 Wm^(−1)K^(−1)is selected to be verified,which matches well with the ex-perimentalκ=1.69 Wm^(−1)K^(−1)at 300 K and could be further decreased to 0.14 Wm^(−1)K^(−1)at 1473 K.Moreover,the coupling effects of lattice vibrations and charges on heat transfer are revealed by the cross-validations of various models,indicating that the weak bonds with low electronegativity and few bond-ing charge density and the lattice distortion(r∗)identified by cation radius ratio(r A/r B)should be the KPPs to decreaseκefficiently.This work supports an intelligent designing strategy with limited atomic and electronic KPPs to accelerate the development of advanced multi-component HEOs with proper-ties/performance at multi-scales.

High-entropy(La_(0.2)Nd_(0.2)Sm_(0.2)Gd_(0.2)Yb_(0.2))_(2)(Zr_(0.75)Ce_(0.25))_(2)O_(7)thermal barrier coating material with significantly enhanced fracture toughness

Poor fracture toughness leads to premature failure of La_(2)(Zr_(0.75)Ce_(0.25))_(2)O_(7)(LCZ)ther-mal barrier coatings in an elevated temperature service environment.A novel coating material,namely(La_(0.2)Nd_(0.2)Sm_(0.2)Gd_(0.2)Yb_(0.2))_(2)(Zr_(0.75)Ce_(0.25))_(2)O_(7)(LNSGY)based on the high-entropy con-cept,was successfully fabricated by solid-state sintering.The microstructure of LCZ and LNSGY was investigated by X-Ray Diffraction(XRD),Raman Spectrometer(RS),Transmission Electronic Microscopy(TEM)and Scanning Electron Microscopy(SEM).The fracture toughness of the LCZ and LNSGY ceramics was evaluated.The LNSGY has excellent high-temperature phase stability,and the grain size of LNSGY ceramic is smaller than that of LCZ ceramic at an elevated temper-ature due to the sluggish diffusion effect.Compared with LCZ(fracture toughness is(1.4±0.1)MPa·m^(1/2)),the fracture toughness of LNSGY is significantly enhanced(fracture toughness is(2.0±0.3)MPa·m^(1/2)).Therefore,the LNSGY can be a promising advanced thermal barrier coat-ing material in the future.

Lightweight quasi-layered elastic fibrous porous ceramics with high compressive stress and low thermal conductivity

Fibrous porous ceramics are attractive for use as thermal insulation materials.However,the intrinsic brit-tleness of rigid materials has remained challenging and severely restricts their applications.Here,we demonstrated a facile method for fabricating elastic fibrous porous ceramics(EFPCs)with high com-pressive strength and low thermal conductivity through ordinary press filtration and subsequent heat treatment.The quasi-layered structure and the well-bonded bridging fibers between layers are the key points for the elasticity of EFPCs.The advanced EFPCs exhibited low density(∼0.126 g cm^(−3)),high com-pressive stress(∼0.356 MPa),and low thermal conductivity(∼0.026 W m^(−1) K^(−1)).Compared with rigid porous fibrous materials,the EFPCs had deformability and excellent shape recovery.In contrast to flexible materials,the EFPCs possessed high compressive stress,thus endowing them with good resistance to de-formation.The emergence of this fascinating material may provide new insights for candidate materials in thermal insulation and other fields.

High-entropy ceramics:Present status,challenges,and a look forward

High-entropy ceramics (HECs) are solid solutions of inorganic compounds with one or more Wyckoff sites shared by equal or near-equal atomic ratios of multi-principal elements.Although in the infant stage,the emerging of this new family of materials has brought new opportunities for material design and property tailoring.Distinct from metals,the diversity in crystal structure and electronic structure of ceramics provides huge space for properties tuning through band structure engineering and phonon engineering.Aside from strengthening,hardening,and low thermal conductivity that have already been found in high-entropy alloys,new properties like colossal dielectric constant,super ionic conductivity,severe anisotropic thermal expansion coefficient,strong electromagnetic wave absorption,etc.,have been discovered in HECs.As a response to the rapid development in this nascent field,this article gives a comprehensive review on the structure features,theoretical methods for stability and property prediction,processing routes,novel properties,and prospective applications of HECs.The challenges on processing,characterization,and property predictions are also emphasized.Finally,future directions for new material exploration,novel processing,fundamental understanding,in-depth characterization,and database assessments are given.

Recent progress in drug delivery

Drug delivery systems(DDS)are defined as methods by which drugs are delivered to desired tissues,organs,cells and subcellular organs for drug release and absorption through a variety of drug carriers.Its usual purpose to improve the pharmacological activities of therapeutic drugs and to overcome problems such as limited solubility,drug aggregation,low bioavailability,poor biodistribution,lack of selectivity,or to reduce the side effects of therapeutic drugs.During 2015-2018,significant progress in the research on drug delivery systems has been achieved along with advances in related fields,such as pharmaceutical sciences,material sciences and biomedical sciences.This review provides a conciseoverview of current progress in this research area through its focus on the delivery strategies,construction techniques and specific examples.It is a valuable reference for pharmaceutical scientists who want to learn more about the design of drug delivery systems.

High-entropy rare-earth zirconate ceramics with low thermal conductivity for advanced thermal-barrier coatings

The high-entropy rare-earth zirconate((La_(0.2)Nd_(0.2)Sm_(0.2)Gd_(0.2)Yb_(0.2))_(2)Zr_(2)O_(7),5RE_(2)Zr_(2)O_(7)HEREZs)ceramics were successfully prepared by a new high-speed positive grinding strategy combined with solid-state reaction method.The microstructure,crystal structure,phase composition,and thermophysical and mechanical properties of the samples were systematically investigated through various methods.Results indicate that the samples have a single-phase defect fluorite-type crystal structure with excellent high-temperature thermal stability.The as-prepared samples also demonstrate low thermal conductivity(0.9–1.72 W·m^(−1)·K^(−1)at 273–1273 K)and high coefficient of thermal expansion(CTE,10.9×10^(−6)K^(−1)at 1273 K),as well as outstanding mechanical properties including large Young’s modulus(E=186–257 GPa)and high fracture toughness(KIC).Furthermore,the formation possibility of the as-prepared samples was verified through the first-principles calculations,which suggested the feasibility to form the 5RE_(2)Zr_(2)O_(7)HE-REZs in the thermodynamic direction.Therefore,in view of the excellent multifunctional properties exhibited by the as-prepared 5RE_(2)Zr_(2)O_(7)HE-REZs,they have great potential applications in next-generation thermal-barrier coatings(TBCs).

Ablation of C/SiC-HfC composite prepared by precursor infiltration and pyrolysis in plasma wind tunnel

Carbon fiber reinforced silicon carbide-hafnium carbide(C/SiC-HfC)composite was prepared by precursor infiltration and pyrolysis process.Then,ablation behavior of C/SiC-HfC was evaluated in plasma wind tunnel.It was found that oxide layer formed during ablation significantly influenced the surface temperature.Formation of dense HfO2 SiO2 layer under low heat flux led to stable surface temperature.Silica(SiO2)on the surface was gradually consumed when heat flux increased,resulting in conversion of HfO2-SiO2 on the surface to HfO2.Converted HfO2 with high catalytic cofficient absorbed more energy,causing gradual increase in the surface temperature.Formed oxide layer was destroyed at high heat flux and high stagnation point pressure.After carbon fiber lost the protection of HfO2-SiO2 layer,it burned immediately,leading to surface temperature jump.

Thermal Expansion of Al Matrix Composites Reinforced with Hybrid Micro-/nano-sized Al_2O_3 Particles

The thermal expansion behavior of aluminum matrix composites reinforced with hybrid （nanometer and micrometer） Al2O3 particles was measured between 100 and 600℃ and compared to theoretical models. The results revealed that the nanoparticle concentration had significant effect on the thermal expansion behavior of the composites. For the composites with lower nanoparticle concentration, their coefficient of thermal expansion （CTE） is determined by a stress relaxation process. While for the composites with higher nanoparticle concentration, their CTE is determined by a percolation process.

利用CRISPR-Cas9系统构建新型异戊酰螺旋霉素Ⅰ产生菌

异戊酰螺旋霉素(Isovalerylspiramycin,ISP)Ⅰ是必特螺旋霉素(Bitespiramycin,BT)的一种主组分,其抗菌活性与BT相似,而且作为单一组分在质控和剂型上更具优势,目前正在进行临床前研究。原有的 ISPⅠ工程菌株经过3次基因改造,已经具有2种抗性基因,很难再进行遗传操作。前期研究利用经典同源重组的方法无法构建无抗性的ISPⅠ产生菌,文中利用CRISPR-Cas9基因编辑系统在螺旋霉素(Spiramycin,SP)产生菌中成功将3位酰基化酶的基因bsm4替换为组成型强启动子ermEp~*控制下的异戊酰基转移酶基因(Isovaleryltansferase gene,ist)。删除bsm4后突变株只能产生SPⅠ组分,外源基因ist的表达产物催化SPⅠ在其4″位进行异戊酰化修饰形成ISPⅠ。经过HPLC和质谱鉴定,阳性菌株ΔEI的发酵产物中只有ISPⅠ一种ISP组分,证实新的ISPⅠ工程菌株构建成功。ΔEI菌株不带有抗性基因,可重复利用CRISPR-Cas9系统进行基因操作来获得新的改良菌株。

Smart drug delivery systems for precise cancer therapy

Nano-drug delivery strategies have been highlighted in cancer treatment, and much effort has been made in the optimization of bioavailability, biocompatibility, pharmacokinetics profiles, and in vivo distributions of anticancer nano-drug delivery systems. However, problems still exist in the delicate balance between improved anticancer efficacy and reduced toxicity to normal tissues, and opportunities arise along with the development of smart stimuli-responsive delivery strategies. By on-demand responsiveness towards exogenous or endogenous stimulus, these smart delivery systems hold promise for advanced tumor-specificity as well as controllable release behavior in a spatial-temporal manner. Meanwhile, the blossom of nanotechnology, material sciences, and biomedical sciences has shed light on the diverse modern drug delivery systems with smart characteristics, versatile functions, and modification possibilities. This review summarizes the current progress in various strategies for smart drug delivery systems against malignancies and introduces the representative endogenous and exogenous stimuli-responsive smart delivery systems. It may provide references for researchers in the fields of drug delivery, biomaterials, and nanotechnology.

Interaction of multicomponent disilicate(Yb_(0.2)Y_(0.2)Lu_(0.2)Sc_(0.2)Gd_(0.2))_(2)Si_(2)O_(7)with molten calcia-magnesia-aluminosilicate

Environmental barrier coating(EBC)materials that are resistant against molten calcia-magnesia-aluminosilicate(CMAS)corrosion are urgently required.Elerein,multicomponent rare-earth(RE)disilicate((Yb_(0.2)Y_(0.2)Lu_(0.2)Sc_(0.2)Gd_(0.2))_(2)Si_(2)O_(7),(5RE)_(2)Si_(2)O_(7))was investigated with regard to its CMAS interaction behavior at 1400°C.Compared with the individual RE disilicates,the(5RE)2Si2C>7 material exhibited improved resistance against CMAS attack.The dominant process involved in the interaction of(5RE)_(2)Si_(2)O_(7)with CMAS was reaction-recrystallization.A dense and continuous reaction layer protected the substrate from rapid corrosion at high temperatures.The results demonstrated that multicomponent strategy of RE species in disilicate can provide a new perspective in the development of promising EBC materials with improved corrosion resistance.

Oxidation behaviors of(Hf_(0.25)Zr_(0.25)Ta_(0.25)Nb_(0.25))C and(Hf_(0.25)Zr_(0.25)Ta_(0.25)Nb_(0.25))C-SiC at 1300-1500℃

In this work,high-entropy ceramics(Hf_(0.25) Zr_(0.25)Ta_(0.25)Nb_(0.25))C(HZTNC) and HZTNC doped with 20 vol%SiC(HZTNC-SiC) were fabricated by spark plasma sintering.Their oxidation behavior was investigated over the temperature range of 1300-1500℃ for up to 60 min.Both HZTNC and HZTNC-SiC exhibited good oxidation resistance,and their weight change as a function of oxidation time obeyed a parabolic law.Through XRD,microstructure observation,and elemental mapping analysis of the oxide layers,it was found that the formation of Nb_(2) Zr_(6) O_(17),Hf_(6) Ta_(2) O_(17),and(Ta,Nb)_(2) O_(5) mixed-oxide layers effectively protected the matrix from further oxidation.Microcracks began to appear on the oxide layer of HZTNC at high temperatures after 60 min of oxidation.However,the addition of SiC in HZTNC suppressed these microcracks at high temperatures due to the active oxidation of SiC.Compared with the oxides formed on HZTNC,the additional formation of Hf(Zr)SiO_(4) on HZTNC-SiC could further improve its oxidation resistance over HZTNC ceramics.

Experimental verification of performance improvement for a gigabit wavelength division multiplexing visible light communication system utilizing asymmetrically clipped optical orthogonal frequency division multiplexing

Asymmetrically clipped optical orthogonal frequency division multiplexing(ACO-OFDM)has been a promising candidate in visible light communications(VLC)due to its improvement in power efficiency and reduction of nonlinearity based on previous simulation analysis.In this paper,for the first time as far as we know,we experimentally verify that ACO-OFDM would be an efficient scheme to improve the performance of a gigabit wavelength division multiplexing VLC system.Our theoretical investigations reveal that the advantages of ACO-OFDM can be attributed to the reduction of inter-carrier interference caused by signal–signal beating noise.An aggregate data rate of 1.05 Gb∕s is successfully achieved over 30 cm transmission below the 7%forwarderror-correction threshold of 3.8×10−3.The experimental results show that ACO-OFDM can outperform DC-biased optical OFDM by BER performance of 1.5 dB at the same data rate and 4 dB at the same bandwidth,which clearly demonstrates the benefit and feasibility of ACO-OFDM.