Draft Genome Sequence of Rhodococcus erythropolis NSX2, an Actinobacterium Isolated from a Cadmium-Contaminated Environment

Rhodococcus erythropolis NSX2 is a rhizobacterium isolated from a heavy metal–contaminated environment. The 6.2-Mb annotated genome sequence shows that this strain harbors genes associated with heavy-metal resistance and xenobiotics degradation

LEAFY Controls Auxin Response Pathways in Floral Primordium Formation

The transcription factor LEAFY is a master regulator of flowering and of flower development. It acts as a component of a switch that mediates the transition from the vegetative to the reproductive phase of plant development. Auxin is a plant hormone with many different roles in plant growth, including the induction of new primordia of both leaves and flowers at the shoot apex. We report that LEAFY acts in part by controlling the auxin response pathway in new primordia. Therefore, regulation of flower development by transcriptional master regulators and hormonal control of morphogenesis appear to be interacting processes. We found that hormone perception not only controls but is also controlled by the transcriptional signals that create plant form

Carbon-assisted growth and high visible-light optical reflectivity of amorphous silicon oxynitride nanowires

Large amounts of amorphous silicon oxynitride nanowires have been synthesized on silicon wafer through carbon-assisted vapor-solid growth avoiding the contamination from metallic catalysts. These nanowires have the length of up to 100 μm, with a diameter ranging from 50 to 150 nm. Around 3-nm-sized nanostructures are observed to be homogeneously distributed within a nanowire cross-section matrix. The unique configuration might determine the growth of ternary amorphous structure and its special splitting behavior. Optical properties of the nanowires have also been investigated. The obtained nanowires were attractive for their exceptional whiteness, perceived brightness, and optical brilliance. These nanowires display greatly enhanced reflection over the whole visible wavelength, with more than 80% of light reflected on most of the wavelength ranging from 400 to 700 nm and the lowest reflectivity exceeding 70%, exhibiting performance superior to that of the reported white beetle. Intense visible photoluminescence is also observed over a broad spectrum ranging from 320 to 500 nm with two shoulders centered at around 444 and 468 nm, respectively

Effects of Charge Transport Materials on Blue Fluorescent Organic Light-Emitting Diodes with a Host-Dopant System

High efficiency blue fluorescent organic light-emitting diodes (OLEDs), based on 1,3-bis(carbazol-9-yl)benzene (mCP) doped with 4,4’-bis(9-ethyl-3-carbazovinylene)-1,1’-biphenyl (BCzVBi), were fabricated using four different hole transport layers (HTLs) and two different electron transport layers (ETLs). Fixing the electron transport material TPBi, four hole transport materials, including 1,1-Bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC), N,N’-Di(1-naphthyl)-N,N’-diphenyl-(1,1’-biphenyl)-4’-diamine(NPB), 4,4’-Bis(N-carbazolyl)-1,1,-biphenyl (CBP) and molybdenum trioxide (MoO3), were selected to be HTLs, and the blue OLED with TAPC HTL exhibited a maximum luminance of 2955 cd/m2 and current efficiency (CE) of 5.75 cd/A at 50 mA/cm2, which are 68% and 62% higher, respectively, than those of the minimum values found in the device with MoO3 HTL. Fixing the hole transport material TAPC, the replacement of TPBi ETL with Bphen ETL can further improve the performance of the device, in which the maximum luminance can reach 3640 cd/m2 at 50 mA/cm2, which is 23% higher than that of the TPBi device. Furthermore, the lifetime of the device is also optimized by the change of ETL. These results indicate that the carrier mobility of transport materials and energy level alignment of different functional layers play important roles in the performance of the blue OLEDs. The findings suggest that selecting well-matched electron and hole transport materials is essential and beneficial for the device engineering of high-efficiency blue OLEDs

Improved Efficiency of Perovskite Light-Emitting Diodes Using a Three-Step Spin-Coated CH3NH3PbBr3 Emitter and a PEDOT:PSS/MoO3-Ammonia Composite Hole Transport Layer

High efficiency perovskite light-emitting diodes (PeLEDs) using PEDOT:PSS/MoO3-ammonia composite hole transport layers (HTLs) with different MoO3-ammonia ratios were prepared and characterized. For PeLEDs with one-step spin-coated CH3NH3PbBr3 emitter, an optimal MoO3-ammonia volume ratio (0.02) in PEDOT:PSS/MoO3-ammonia composite HTL presented a maximum luminance of 1082 cd/m2 and maximum current efficiency of 0.7 cd/A, which are 82% and 94% higher than those of the control device using pure PEDOT:PSS HTL respectively. It can be explained by that the optimized amount of MoO3-ammonia in the composite HTLs cannot only facilitate hole injection into CH3NH3PbBr3 through reducing the contact barrier, but also suppress the exciton quenching at the HTL/CH3NH3PbBr3 interface. Three-step spin coating method was further used to obtain uniform and dense CH3NH3PbBr3 films, which lead to a maximum luminance of 5044 cd/m2 and maximum current efficiency of 3.12 cd/A, showing enhancement of 750% and 767% compared with the control device respectively. The significantly improved efficiency of PeLEDs using three-step spin-coated CH3NH3PbBr3 film and an optimum PEDOT:PSS/MoO3-ammonia composite HTL can be explained by the enhanced carrier recombination through better hole injection and film morphology optimization, as well as the reduced exciton quenching at HTL/CH3NH3PbBr3 interface. These results present a promising strategy for the device engineering of high efficiency PeLEDs

Plant growth-promoting rhizobacteria enhance the growth and Cd uptake of Sedum plumbizincicola in a Cd-contaminated soil

This study aimed to isolate plant growth-promoting rhizobacteria (PGPR) that exhibit heavy metal resistance to examine their influence on Cd uptake and soil microbial community structure during phytoremediation. Heavy metal-tolerant PGPR were isolated from the roots of possible hyperaccumulators using plates with 1-aminocyclopropane-1-carboxylate (ACC) as sole nitrogen source. Minimal inhibitory concentrations (MICs) of each isolate were determined by the plate dilution method. The impacts of isolated PGPR on the growth and Cd accumulation of Sedium plumbizincicola were conducted in a pot experiment. In addition, the effect of PGPR inoculation on the microbial community during phytoextraction by S. plumbizincicola was studied by 454 pyrosequencing. A total of nine Cd-resistant strains were isolated from the roots of Cd accumulators, and their plant growth-promoting activities were characterized. Isolates were able to produce indole-3-acetic acid (IAA) (28-133 mg L-1) and solubilize phosphate (65-148 mg L-1). In a pot experiment, the inoculation of isolates NSX2 and LCR1 significantly enhanced the growth of and uptake of Cd by the Cd hyperaccumulator S. plumbizincicola. 454 pyrosequencing revealed that the inoculation of the PGPR lead to a decrease in microbial community diversity in the rhizopshere during phytoextraction. Specifically, indigenous heavy metal-tolerant PGPR such as Actinospica, Bradyrhizobium, Rhizobium, Mesorhizobium, and Mycobacterium were selectively enriched in the treatments in which PGPR were added. It is suggested that a unique constitution of microbial communities in inoculated treatments plays a key role in enhancing Cd phytoremediation. Inoculation of strains Rhodococcus erythropolis NSX2 and Cedecea davisae LCR1 could promote S. plumbizincicola growth and enhance the remediation efficiency. The introduced PGPR could also affect the indigenous microbial community structure and the diversity in Cd-contaminated soil during phytoremediation.This study aimed to isolate plant growth-promoting rhizobacteria (PGPR) that exhibit heavy metal resistance to examine their influence on Cd uptake and soil microbial community structure during phytoremediation