InGaN blue resonant cavity micro-LED with RGY quantum dot layer for broad gamut, efficient displays

The technology of RGBY micro resonant cavity light emitting diodes (micro-RCLEDs) based on quantum dots (QDs) is considered one of the most promising approaches for full-color displays. In this work, we propose a novel structure combining a high color conversion efficiency (CCE) QD photoresist (QDPR) color conversion layer (CCL) with blue light micro RCLEDs, incorporating an ultra-thin yellow color filter. The additional TiO2 particles inside the QDPR CCL can scatter light and disperse QDs, thus reducing the self-aggregation phenomenon and enhancing the eventual illumination uniformity. Considering the blue light leakage, the influences of adding different color filters are investigated by illumination design software. Finally, the introduction of low-temperature atomic layer deposition (ALD) passivation protection technology at the top of the CCL can enhance the device's reliability. The introduction of RGBY four-color subpixels provides a viable path for developing low-energy consumption, high uniformity, and efficient color conversion displays.

Enhancing photoluminescence performance of perovskite quantum dots with plasmonic nanoparticles: insights into mechanisms and light-emitting applications

Perovskite quantum dots (QDs) are considered as promising materials for numerous optoelectronic applications due to their narrow emission spectra, high color purity, high photoluminescence quantum yields (PLQYs), and cost-effectiveness. Herein, we synthesized various types of perovskite QDs and incorporated Au nanoparticles (NPs) to systematically investigate the impact of plasmonic effects on the photoluminescence performance of perovskite QDs. The PLQYs of the QDs are enhanced effectively upon the inclusion of Au NPs in the solutions, with an impressive PLQY approaching 99% achieved. The PL measurements reveal that the primary mechanism behind the PL improvement is the accelerated rate of radiative recombination. Furthermore, we integrate perovskite QDs and Au NPs, which function as color conversion layers, with blue light-emitting diodes (LEDs), achieving a remarkable efficiency of 140.6 lm W-1. Additionally, we prepare photopatternable thin films of perovskite QDs using photocrosslinkable polymers as the matrix. Microscale patterning of the thin films is accomplished, indicating that the addition of plasmonic NPs does not adversely affect their photopatternable properties. Overall, our research not only elucidates the underlying mechanisms of plasmonic effects on perovskite QDs but presents a practical method for enhancing their optical performance, paving the way for next-generation optoelectronic applications, including high-definition micro-LED panels.

Investigations on the high performance of InGaN red micro-LEDs with single quantum well for visible light communication applications

In this study, we have demonstrated the potential of InGaN-based red micro-LEDs with single quantum well (SQW) structure for visible light communication applications. Our findings indicate the SQW sample has a better crystal quality, with high-purity emission, a narrower full width at half maximum, and higher internal quantum efficiency, compared to InGaN red micro-LED with a double quantum wells (DQWs) structure. The InGaN red micro-LED with SQW structure exhibits a higher maximum external quantum efficiency of 5.95% and experiences less blueshift as the current density increases when compared to the DQWs device. Furthermore, the SQW device has a superior modulation bandwidth of 424 MHz with a data transmission rate of 800 Mbit/s at an injection current density of 2000 A/cm². These results demonstrate that InGaN-based SQW red micro-LEDs hold great promise for realizing full-color micro-display and visible light communication applications.

Ameliorating Uniformity and Color Conversion Efficiency in Quantum Dot-Based Micro-LED Displays through Blue-UV Hybrid Structures

Quantum dot (QD)-based RGB micro light-emitting diode (μ-LED) technology shows immense potential for achieving full-color displays. In this study, we propose a novel structural design that combines blue and quantum well (QW)-intermixing ultraviolet (UV)-hybrid μ-LEDs to achieve high color-conversion efficiency (CCE). For the first time, the impact of various combinations of QD and TiO₂ concentrations, as well as thickness variations on photoluminescence efficiency (PLQY), has been systematically examined through simulation. High-efficiency color-conversion layer (CCL) have been successfully fabricated as a result of these simulations, leading to significant savings in time and material costs. By incorporating scattering particles of TiO₂ in the CCL, we successfully scatter light and disperse QDs, effectively reducing self-aggregation and greatly improving illumination uniformity. Additionally, this design significantly enhances light absorption within the QD films. To enhance device reliability, we introduce a passivation protection layer using low-temperature atomic layer deposition (ALD) technology on the CCL surface. Moreover, we achieve impressive CCE values of 96.25% and 92.91% for the red and green CCLs, respectively, by integrating a modified distributed Bragg reflector (DBR) to suppress light leakage. Our hybrid structure design, in combination with an optical simulation system, not only facilitates rapid acquisition of optimal parameters for highly uniform and efficient color conversion in μ-LED displays but also expands the color gamut to achieve 128.2% in the National Television Standards Committee (NTSC) space and 95.8% in the Rec. 2020 standard. In essence, this research outlines a promising avenue towards the development of bespoke, high-performance μ-LED displays.

High-Reliability Perovskite Quantum Dots Using Atomic Layer Deposition Passivation for Novel Photonic Applications

In this study, we propose highly stable perovskite quantum dots (PQDs) coated with Al₂O₃ using atomic layer deposition (ALD) passivation technology. This passivation layer effectively protects the QDs from moisture infiltration and oxidation as well as from high temperatures and any changes in the material characteristics. They exhibit excellent wavelength stability and reliability in terms of current variation tests, long-term light aging tests, and temperature/humidity tests (60°/90%). A white-light system has been fabricated by integrating a micro-LED and red phosphor exhibiting a high data transmission rate of 1 Gbit/s. These results suggest that PeQDs treated with ALD passivation protection offer promising prospects in full-color micro-displays and high-speed visible-light communication (VLC) applications.

Gateway towards recent developments in quantum dot-based light-emitting diodes

Quantum dots (QDs), with their excellent photoluminescence, narrow emission linewidth, and wide color coverage, provide unrivaled advantages for advanced display technologies, enabling full-color micro-LED displays. It is indeed critical to have a fundamental understanding of how QD properties affect micro-LED display performance in order to develop the most energy-efficient display device in the near future. However, to take a more detailed look at the stability issues and passivation ways of QDs is essential for accelerating the commercialization of QD-based LED technologies. Knowing about the most recent breakthroughs in QD-based LEDs can give a good indication of how they might be used in shaping the future of displays. In this review, we discuss the characteristics of QD-based LEDs for the applications of display and lighting technologies. Various approaches for synthesis and the stability improvement of QDs are addressed in detail, along with recent advancements towards QD-based LED breakthroughs. Moreover, we summarize our latest research findings in QD-based LEDs, providing valuable information about the potential of QD-based LEDs for future display technologies.

Nanogold-Carried Graphene Oxide: Anti-Inflammation and Increased Differentiation Capacity of Mesenchymal Stem Cells

Graphene-based nanocomposites such as graphene oxide (GO) and nanoparticle-decorated graphene with demonstrated excellent physicochemical properties have worthwhile applications in biomedicine and bioengineering such as tissue engineering. In this study, we fabricated gold nanoparticle-decorated GO (GO-Au) nanocomposites and characterized their physicochemical properties using UV-Vis absorption spectra, FTIR spectra, contact angle analyses, and free radical scavenging potential. Moreover, we investigated the potent applications of GO-Au nanocomposites on directing mesenchymal stem cells (MSCs) for tissue regeneration. We compared the efficacy of as-prepared GO-derived nanocomposites including GO, GO-Au, and GO-Au (×2) on the biocompatibility of MSCs, immune cell identification, anti-inflammatory effects, differentiation capacity, as well as animal immune compatibility. Our results showed that Au-deposited GO nanocomposites, especially GO-Au (×2), significantly exhibited increased cell viability of MSCs, had good anti-oxidative ability, sponged the immune response toward monocyte-macrophage transition, as well as inhibited the activity of platelets. Moreover, we also validated the superior efficacy of Au-deposited GO nanocomposites on the enhancement of cell motility and various MSCs-derived cell types of differentiation including neuron cells, adipocytes, osteocytes, and endothelial cells. Additionally, the lower induction of fibrotic formation, reduced M1 macrophage polarization, and higher induction of M2 macrophage, as well as promotion of the endothelialization, were also found in the Au-deposited GO nanocomposites implanted animal model. These results suggest that the Au-deposited GO nanocomposites have excellent immune compatibility and anti-inflammatory effects in vivo and in vitro. Altogether, our findings indicate that Au-decorated GO nanocomposites, especially GO-Au (×2), can be a potent nanocarrier for tissue engineering and an effective clinical strategy for anti-inflammation.

Temperature-Induced Lifshitz Transition and Possible Excitonic Instability in ZrSiSe

The nodal-line semimetals have attracted immense interest due to the unique electronic structures such as the linear dispersion and the vanishing density of states as the Fermi energy approaching the nodes. Here, we report temperature-dependent transport and scanning tunneling microscopy (spectroscopy) [STM(S)] measurements on nodal-line semimetal ZrSiSe. Our experimental results and theoretical analyses consistently demonstrate that the temperature induces Lifshitz transitions at 80 and 106 K in ZrSiSe, which results in the transport anomalies at the same temperatures. More strikingly, we observe a V-shaped dip structure around Fermi energy from the STS spectrum at low temperature, which can be attributed to co-effect of the spin-orbit coupling and excitonic instability. Our observations indicate the correlation interaction may play an important role in ZrSiSe, which owns the quasi-two-dimensional electronic structures.

Flexible Organometal-Halide Perovskite Lasers for Speckle Reduction in Imaging Projection

Disorder is emerging as a strategy for fabricating random laser sources with very promising materials, such as perovskites, for which standard laser cavities are not effective or too expensive. We need, however, different fabrication protocols and technologies for reducing the laser threshold and controlling its emission. Here, we demonstrate an effectively solvent-engineered method for high-quality perovskite thin films on a flexible polyimide substrate. The fractal perovskite thin films exhibit excellent optical properties at room temperature and easily achieve lasing action without any laser cavity above room temperature with a low pumping threshold. The lasing action is also observed in curved perovskite thin films on flexible substrates. The lasing threshold can be further reduced by increasing the local curvature, which modifies the scattering strengths of the bent thin film. We also show that the curved perovskite lasers are extremely robust with respect to repeated deformations. Because of the low spatial coherence, these curved random laser devices are efficient and durable speckle-free light sources for applications in spectroscopy, bioimaging, and illumination.

Bidentate chelating ligands as effective passivating materials for perovskite light-emitting diodes

Aromatic chelating ligands are used as surface passivating agents to fix the defects of the perovskite layers in light-emitting diodes.

New iridium-containing conjugated polymers for polymer solar cell applications

The highest value of power conversion efficiency is 1.74% for the P3 based polymer.

[Effects and mechanism of allogeneic platelet rich plasma on collagen synthesis in wound healing]

Objective: To investigate the effects and mechanism of allogeneic platelet rich plasma (PRP) on collagen in wound surface at different time. Methods: A total of 50 clean 7-week rats were selected for this study, including 10 rats for platelet-rich blood plasma preparation, 20 rats for PRP group and 20 rats for control group, 0.1 ml allogenic PRP and 0.1 ml saline were smeared respectively on wound surfaces of PRP and control group, wound regeneration and healing were examined. Cellular and histological morphology alteration was observed via Masson staining, type Ⅰ and type Ⅲ collagen protein and mRNA expression level were detected by Western blot and real-time PCR. T test was applied for comparison between two samples and one-way ANOVA was utilized for comparison between two groups. Results: The wound healing rate of PRP group was higher than that of control group on 3(rd,) 6(th,) 10(th) and 15(th) day (30.33±3.35 vs.18.35±2.04, 55.51±2.74 vs.36.83±2.34, 79.64±1.40 vs.56.92±1.44, 86.88±2.12 vs.65.80±1.76) after wound surface formation, there were statistic differences (t=13.66-50.48, all P<0.05). The wound collagen of PRP group form faster and coarser, and the fibers arrayed more densely in Masson staining. The protein expression of type Ⅰ collagen(1.92±0.09 vs.1.18±0.11) and type Ⅲ collagen(1.16±0.05 vs.0.74±0.11) of PRP group were higher than that of control group (t=22.99, P<0.01; t=17.62, P<0.05); the mRNA expression of type Ⅰ collagen(5.17±0.11 vs.1.79±0.18, 6.97±0.09 vs.1.96±0.08, 6.00±0.26 vs.2.10±0.05, 4.95±0.11 vs.3.58±0.09)and type Ⅲ collagen(2.35±0.08 vs.1.44±0.05, 3.08±0.05 vs.1.84±0.06, 3.48±0.07 vs.2.36±0.09, 4.42±0.07 vs.2.77±0.10) were higher than that of control group on 3(rd,) 6(th,) 10(th) and 15(th) day after wound surface formation, there were significant differences (t=43.37-188.37, all P<0.05). Conclusion: The allogeneic platelet rich plasma may promote fibroblasts secreted collagen by activated and releasing all kinds of growth factors, especially type Ⅰ and type Ⅲ collagen to accelerate the wound healing.

Photoexfoliation of two-dimensional materials through continuous UV irradiation

This paper describes the preparation of fluorinated graphene nanosheets (FGNs) through photoexfoliation of fluorinated graphite (FG) in the liquid phase. We discovered that UV irradiation of FG dispersions in N-methyl-2-pyrolidone facilitated exfoliation to give FGNs. Transmission electron microscopy and atomic force microscopy revealed that the average thickness of the FGNs was approximately 3 nm; they were considerably thinner than the nanosheets prepared using a conventional sonication approach. Furthermore, when the FGNs were deposited uniformly onto substrates (through spin coating), they formed effective cathode interlayers for polymer solar cells (PSCs), the efficiency of which was 60% greater than that of PSCs containing FGNs prepared through ultrasonication.

New D-A1-D-A2-Type Regular Terpolymers Containing Benzothiadiazole and Benzotrithiophene Acceptor Units for Photovoltaic Application

Two novel regular terpolymers that are of D-A1-D-A2 type and contain benzothiadiazole and 2,5-dibromo-8-dodecanoylbenzo[1,2-b:3,4-b':5,6-d″]trithiophene (P1) or 2,8-dibromo-5-dodecanoylbenzene[1,2-b:3,4-b':5,6-d″]trithiophene (P2) acceptor units with the same thiophene donor were synthesized through Stille coupling, and their optical and electrochemical properties were investigated. The highest occupied molecular orbital (HOMO) and lowest unoccupied (LUMO) molecular orbital energy levels of these terpolymers indicate that there is sufficient LUMO offset with PCBM for efficient exciton dissociation, and their deeper HOMO levels ensure the high open-circuit voltage for the resultant bulk heterojunction solar cells. Measurements on the solar cell devices also confirm that compared to those based on P2 the devices based on P1 possess a higher short-circuit photocurrent (J_sc) as well as a higher fill factor (FF), which is attributed to the lower bandgap and higher hole mobility for P1, whereas the V_oc is higher for the devices that are based on P2, which may be a result of P2 having a lower HOMO energy level than P1. The optimized polymer solar cells fabricated using P1:PC₇₁BM (DIO/CF) and P2:PC₇₁BM (CF/DIO) for the active layers showed a PCE of 7.19% and 6.34%, respectively. Atomic force microscopy (AFM) images of P1:PC₇₁BM blend films show that they exhibit more suitable morphology with favorable interpenetrating networks, which favors high J_sc and FF. Moreover, P1 exhibits a more crystalline nature than P2 that also favors the charge transport. This may be a result of better molecular packing, more distinct phase separation of the blended films, as well as a reduction of charge recombination.

Controllable lasing performance in solution-processed organic-inorganic hybrid perovskites

Solution-processed organic-inorganic perovskites are fascinating due to their remarkable photo-conversion efficiency and great potential in the cost-effective, versatile and large-scale manufacturing of optoelectronic devices. In this paper, we demonstrate that the perovskite nanocrystal sizes can be simply controlled by manipulating the precursor solution concentrations in a two-step sequential deposition process, thus achieving the feasible tunability of excitonic properties and lasing performance in hybrid metal-halide perovskites. The lasing threshold is at around 230 μJ cm^-2 in this solution-processed organic-inorganic lead-halide material, which is comparable to the colloidal quantum dot lasers. The efficient stimulated emission originates from the multiple random scattering provided by the micro-meter scale rugged morphology and polycrystalline grain boundaries. Thus the excitonic properties in perovskites exhibit high correlation with the formed morphology of the perovskite nanocrystals. Compared to the conventional lasers normally serving as a coherent light source, the perovskite random lasers are promising in making low-cost thin-film lasing devices for flexible and speckle-free imaging applications.

Cross-Linkable Hole-Transport Materials Improve the Device Performance of Perovskite Light-Emitting Diodes

Hybrid organic/inorganic perovskites are promising candidate materials for use in photovoltaic applications. More recently, they have also become highly attractive as active materials for other optoelectronic devices, including lasers, light-emitting diodes, and photodetectors. Nevertheless, difficulties in forming continuous and uniform films and the existence of a charge-injection barrier between the perovskite layer and the electrodes have hindered the development of high-performance perovskite light-emitting diodes (PeLEDs). In this study, a cross-linked hole-transport layer (HTL) is introduced to improve the hole-injection efficiency of PeLEDs. Furthermore, this layer simultaneously facilitates the formation of smooth perovskite layers, presumably because of the different surface energies. More interestingly, the HTL also exhibits strong solvent effects on the device performance. When the processing solvent for fabricating the HTLs is changed from chlorobenzene to N,N-dimethylformamide (DMF), the perovskite layer becomes more uniform and continuous, leading to better surface coverage and higher device efficiency, presumably because DMF has strong affinity toward the perovskite precursors. The approach presented herein could become a general method for decreasing the hole-injection barrier of PeLEDs and, eventually, lead to higher device performance.

Localized surface plasmon for enhanced lasing performance in solution-processed perovskites

A promising method to promote the lasing performance of solution-processed organic-inorganic lead-halide perovskites has been demonstrated. With the adding Ag and PMMA thin films, the threshold excitation power for low-temperature lasing action in perovskites can be greatly reduced by over two orders of magnitude than that acquired in bare perovskite layers, ascribing to the strong exciton-plasmon coupling between the Ag and perovskite films. Also, the PMMA layer can be exploited to prevent the perovskite degradation from the hydrolysis in ambient environment, achieving long-lasting light-emitting performance. The advantages exhibited by the hybrid perovskite configuration would be very promising in making practical laser devices.

Organic Photovoltaics and Bioelectrodes Providing Electrical Stimulation for PC12 Cell Differentiation and Neurite Outgrowth

Current bioelectronic medicines for neurological therapies generally involve treatment with a bioelectronic system comprising a power supply unit and a bioelectrode device. Further integration of wireless and self-powered units is of practical importance for implantable bioelectronics. In this study, we developed biocompatible organic photovoltaics (OPVs) for serving as wireless electrical power supply units that can be operated under illumination with near-infrared (NIR) light, and organic bioelectronic interface (OBEI) electrode devices as neural stimulation electrodes. The OPV/OBEI integrated system is capable to provide electrical stimulation (ES) as a means of enhancing neuron-like PC12 cell differentiation and neurite outgrowth. For the OPV design, we prepared devices incorporating two photoactive material systems--β-carotene/N,N'-dioctyl-3,4,9,10-perylenedicarboximide (β-carotene/PTCDI-C8) and poly(3-hexylthiophene)/phenyl-C61-butyric acid methyl ester (P3HT/PCBM)--that exhibited open circuit voltages of 0.11 and 0.49 V, respectively, under NIR light LED (NLED) illumination. Then, we connected OBEI devices with different electrode gaps, incorporating biocompatible poly(hydroxymethylated-3,4-ethylenedioxythiophene), to OPVs to precisely tailor the direct current electric field conditions during the culturing of PC12 cells. This NIR light-driven OPV/OBEI system could be engineered to provide tunable control over the electric field (from 220 to 980 mV mm(-1)) to promote 64% enhancement in the neurite length, direct the neurite orientation on chips, or both. The OPV/OBEI integrated systems under NIR illumination appear to function as effective power delivery platforms that should meet the requirements for wirelessly offering medical ES to a portion of the nervous system; they might also be a key technology for the development of next-generation implantable bioelectronics.

Metal Nanoparticle-Decorated Two-Dimensional Molybdenum Sulfide for Plasmonic-Enhanced Polymer Photovoltaic Devices

Atomically thin two-dimensional (2D) transition metal dichalcogenides have also attracted immense interest because they exhibit appealing electronic, optical and mechanical properties. In this work, we prepared gold nanoparticle-decorated molybdenum sulfide (AuNP@MoS₂) through a simple spontaneous redox reaction. Transmission electron microscopy, UV-Vis spectroscopy, and Raman spectroscopy were used to characterize the properties of the AuNP@MoS₂ nanomaterials. Then we employed such nanocomposites as the cathode buffer layers of organic photovoltaic devices (OPVs) to trigger surface plasmonic resonance, leading to noticeable enhancements in overall device efficiencies. We attribute the primary origin of the improvement in device performance to local field enhancement induced by the effects of localized surface plasmonic resonance. Our results suggest that the metal nanoparticle-decorated two-dimensional materials appear to have great potential for use in high-performance OPVs.

Establishment of a prediction model for the miRNA-based heading date characteristics of rice in the booting stage

Rice (Oryza sativa L.) is one of the most important food crops in the world. In Taiwan, due to the warm climate, there are two harvests annually. However, the yield and quality of rice can vary between each crop season in any given year. Previous reports have shown that microRNAs (miRNAs) play a crucial role in many developmental and physiological processes in plants. In this study, the heading date characteristics of 167 rice cultivars from the second crop season were recorded, and 27 rice cultivars were selected for preliminary microarray analysis. A total of 14 miRNAs from different heading date characteristics in 21 cultivars were selected based on significant differences in their expression profiles. Using a correlation analysis between the heading date and selected miRNA expression obtained from real-time polymerase chain reaction (PCR) assays, we developed a heading date prediction model. The model includes nine miRNA genes with corresponding R2 values of 0.8. To confirm the model, a real-time PCR analysis was performed on an additional 27 rice cultivars and we found the model predicted the heading date with accuracy. Therefore, the developed prediction may be useful in further studies aimed at confirming the reliability of the use of miRNA in molecular breeding and to increase the selection efficiency of rice cultivars and breeding.

Synergistic plasmonic effects of metal nanoparticle-decorated PEGylated graphene oxides in polymer solar cells

Metal nanostructures that trigger plasmonic near-field effects are often incorporated in organic photovoltaic devices (OPVs) to improve their light-harvesting ability. These nanostructures usually can be positioned in two different locations in a device: (i) within the photon absorption layers and (ii) at the interfaces between the active layer and the metal electrodes. In this study, we developed amphiphilic gold nanoparticles (Au NPs) for use in dual plasmonic nanostructures within OPVs. We employed graphene oxide as the template to anchor the Au NPs, thereby avoiding their aggregation. Furthermore, we added poly(ethylene glycol) (PEG) bis(amine) to the synthesis medium to improve the solubility of the nanocomposites, such that they could be dispersed well in water and in several organic solvents. Accordingly, we could incorporate the PEGylated Au NP/graphene oxides readily into both the buffer layer and photoactive layer of OPVs, which, as a result, exhibited obvious enhancements in their photocurrents and overall device efficiencies. Moreover, we observed different spectral enhancement regions when we positioned the nanocomposites at different locations, reflecting the different dielectric environments surrounding the NPs; this unexpected behavior should assist in enhancing the broadband absorption of solar irradiation.

Sexual genetic and simple sequence repeat (SSR) analysis for molecular marker development on the all hermaphrodite papaya

The papaya (Carica papaya L.) is one of the most important economic tropical fruits in the world, and the hermaphrodite is the preferred type in field cultures. We analyzed the sexual ratio of offspring from the cultivar 'Taiwan Seed Station No. 7' (T7) by a self-cross and its cross with Taichung Sunrise (TS). Female progeny from the T7 self-crossing were not observed. This finding may be caused by a lethal gene that is linked to females. In this study, we selected 192 simple sequence repeats (SSRs) to analyze the polymorphism between T7 and TS. A total of 37 SSRs were identified for T7 and TS. In addition, 14 SSRs served as the molecular makers for identification of T7, TS and their hybrid offsprings. Thus, the results show that the genetic similarity between T7 and TS is rather high. This suggests that T7 may be a mutant of TS. Phylogenetic analysis from the SSR polymorphisms of the above parent strains and 15 F1 offspring revealed the genetic distance of the F1 offspring located between T7 and TS. The results of this study may provide an opportunity for elucidating the genetic characteristics of all hermaphrodites via identification of molecular makers.

Synthesis and characterization of π-conjugated copolymers with thieno-imidazole units in the main chain: application for bulk heterojunction polymer solar cells

In this paper the three new narrow bandgap D–A conjugated copolymers P1, P2 and P3 based on different weak donor fused thiophene-imidazole containing derivatives and the same benzothiadiazole acceptor unit were synthesized by Stille cross-coupling polymerization and characterized by 1H NMR, elemental analysis, GPC, TGA, DSC. These copolymers exhibit intensive absorbance in the range 350–900 nm and the optical bandgap lies in the range of 1.50–1.61 eV, which corresponds to the maximum photon flux of the solar spectrum. The electrochemical bandgap derived from cyclic voltammetry varies within the limits 1.47–1.65 eV and is approximately very close to the optical bandgap. The highest occupied molecular orbital (HOMO) energy level of all copolymers is deep lying (−5.24 eV and −5.37 eV and −5.25 eV for P1, P2 and P2, respectively) which shows that copolymers have good stability in the air and assured a higher open circuit voltage (Voc) for polymer BHJ solar cells. These copolymers were used as donors along with PC71BM and the BHJ polymer solar cells based on P1:PC71BM, P2:PC71BM and P3:PC71BM processed from chloroform (CF) solvent with 3 v% DIO as an additive showed an overall PCE of 4.55%, 6.76% and 5.16%, respectively.

Variations in cognitive demand affect heart rate in typically developing children and children at risk for developmental coordination disorder

BACKGROUND

Developmental coordination disorder (DCD) is a diagnosis for children who present with movement difficulties, but are of normal intelligence without neurological deficits. Previous studies have demonstrated that children with DCD exhibit perceptual deficits and lower cognition performance. To date, their autonomic nervous system (ANS) responses during tasks requiring cognitive and perceptual effort have not been compared to typically developing children (TDC).

OBJECTIVE

The present study investigated heart rate variability (HRV) as a marker for ANS response differences between DCD and TDC, and the impact of different levels of task difficulty.

METHODS

Participants were 60 individuals (9-10 years); 30 children at risk for DCD, and 30 TDC. Each participant performed two tasks each of which demanded enhanced cognitive effort: a visual signal detection task and a digit memory task-each task had two levels of difficulty, low (LD) and high (HD). Heart rate responses were continuously recorded during performance of each task. Frequency domain analysis and heart rate sample entropy (SampEn) were computed to determine ANS responses in each of the tasks.

RESULTS

HRV differences were detected between the two levels of task difficulty, LD and HD, for the visual signal detection task, but not for the digit memory task. HRV differences between LD and HD conditions were greater for TDC children than DCD when engaged in visual signal detection task, compare to the memory task.

INTERPRETATION

The results suggest that children at risk for DCD may show decreased HRV as a marker for altered ANS responses and potential deficits in the linkage between their perceptions and actions.

Characterization and expression analysis of somatic embryogenesis receptor-like kinase genes from Phalaenopsis

Somatic embryogenesis receptor-like kinase (SERK) genes have been found to be involved in the somatic embryogenesis of several plant species. We identified and characterized 5 PhSERK genes in the Phalaenopsis orchid. The amino acid sequences of PhSERKs and other SERK proteins are highly conserved, with the highest homology observed in the leucine-rich repeat-receptor-like kinase domain. All 5 PhSERKs were expressed in all Phalaenopsis organs examined (root, leaf, shoot apical meristem, and flower), with the strongest expression, particularly for PhSERK1 and 3, in the shoot apical meristem of mature plants. Expression of all PhSERKs was downregulated during early floral bud development and was upregulated gradually until the semi-open flower stage was reached. All 5 PhSERKs were expressed during both seed germination and protocorm-like-body (PLB) development. In germinated seeds, quantitative real-time PCR revealed upregulation of all PhSERKs except PhSERK4 at 1 week and downregulation after 4 weeks. The 5 PhSERKs were differentially expressed in the early stage of PLB development and maintained substantial levels during PLB formation, with PhSERK1 and 5 upregulated 1 week after culture and PhSERK2, 3, and 4 downregulated over this period. Because physical wounding of PLB stimulates secondary PLB formation, the PhSERK5 expression peak at week 3 coincided with visible and fully developed secondary PLBs. PhSERK5 may be important in PLB induction and subsequent development. Our PhSERK expression analysis revealed that these genes have a broad role during orchid plant development.

Plasmonic nanostructures for light trapping in organic photovoltaic devices

Over the past decade, we have witnessed rapid advances in the development of organic photovoltaic devices (OPVs). At present, the highest level of efficiency has surpassed 10%, suggesting that OPVs have great potential to become competitive with other thin-film solar technologies. Because plasmonic nanostructures are likely to further improve the efficiency of OPVs, this Article reviews recent progress in the development of metal nanostructures for triggering plasmonic effects in OPVs. First, we briefly describe the physical fundamentals of surface plasmons (SPs). Then, we discuss recent approaches toward increasing the light trapping efficiency of OPVs through the incorporation of plasmonic structures. Finally, we provide a brief outlook into the future use of SPs in highly efficient OPVs.

Analysis of sequence diversity through internal transcribed spacers and simple sequence repeats to identify Dendrobium species

The Orchidaceae is one of the largest and most diverse families of flowering plants. The Dendrobium genus has high economic potential as ornamental plants and for medicinal purposes. In addition, the species of this genus are able to produce large crops. However, many Dendrobium varieties are very similar in outward appearance, making it difficult to distinguish one species from another. This study demonstrated that the 12 Dendrobium species used in this study may be divided into 2 groups by internal transcribed spacer (ITS) sequence analysis. Red and yellow flowers may also be used to separate these species into 2 main groups. In particular, the deciduous characteristic is associated with the ITS genetic diversity of the A group. Of 53 designed simple sequence repeat (SSR) primer pairs, 7 pairs were polymorphic for polymerase chain reaction products that were amplified from a specific band. The results of this study demonstrate that these 7 SSR primer pairs may potentially be used to identify Dendrobium species and their progeny in future studies.

Reduced optical loss in mechanically stacked multi-junction organic solar cells exhibiting complementary absorptions

This paper describes a promising approach toward preparing effective electrical and optical interconnections for tandem organic photovoltaic devices (OPVs). The first subcell featured a semi-transparent electrode, which allowed a portion of the solar irradiation to pass through and to enter the second subcell exhibiting complementary absorption behavior. The resulting multi-junction OPV had multiple contacts such that the subcells could be easily connected either in series or in parallel. More importantly, we used UV-curable epoxy to "mechanically" stack the two subcells and to eliminate the air gap between them, thereby reducing the optical loss induced by mismatches of refractive indices. Therefore, an improved power conversion efficiency of approximately 6.5% has been achieved.

Gold nanoparticle-decorated graphene oxides for plasmonic-enhanced polymer photovoltaic devices

In this work, gold nanoparticle/graphene oxide (AuNP/GO) nanocomposites are synthesized and used as anodic buffer layers in organic photovoltaic devices (OPVs). The application of thiol-terminated polyethylene glycol as a capping agent prevents the aggregation of AuNPs on the GO surface and further improves the solubility and stability of these nanomaterials in solutions. When AuNP/GO nanomaterials served as the buffer layers, they introduced localized surface plasmon resonance (LSPR) in the OPVs, leading to noticeable enhancements in the photocurrent and the efficiencies of the OPVs. We attribute the primary origin of the improvement in device performance to local field enhancement induced by the LSPR. We anticipate that this study might open up new avenues for constructing plasmon-enhancing layers on the nanoscale to improve the performance of solar cells.

Solution-processed nanocomposites containing molybdenum oxide and gold nanoparticles as anode buffer layers in plasmonic-enhanced organic photovoltaic devices

Solution-processed nanocomposites containing molybdenum oxide (MoO3) and gold nanoparticles (Au NPs) have been used as anode buffer layers in organic photovoltaic devices (OPVs). The resulting devices exhibit a remarkable enhancement in power conversion efficiency after Au NPs were incorporated into the device. Such enhancements can be attributed to the localized surface plasmon resonance induced by the metallic nanostructures. We have also found that the rate of exciton generation and the probability of exciton dissociation were increased. Furthermore, the devices made of the MoO3 buffer layer containing Au NPs exhibited superior stability. This work opens up the possibility of fabricating OPVs with both high efficiency and a prolonged lifetime.

High-performance flexible waveguiding photovoltaics

The use of flat-plane solar concentrators is an effective approach toward collecting sunlight economically and without sun trackers. The optical concentrators are, however, usually made of rigid glass or plastics having limited flexibility, potentially restricting their applicability. In this communication, we describe flexible waveguiding photovoltaics (FWPVs) that exhibit high optical efficiencies and great mechanical flexibility. We constructed these FWPVs by integrating poly-Si solar cells, a soft polydimethylsiloxane (PDMS) waveguide, and a TiO₂-doped backside reflector. Optical microstructures that increase the light harvesting ability of the FWPVs can be fabricated readily, through soft lithography, on the top surface of the PDMS waveguide. Our optimized structure displayed an optical efficiency of greater than 42% and a certified power conversion efficiency (PCE) of 5.57%, with a projected PCE as high as approximately 18%. This approach might open new avenues for the harvesting of solar energy at low cost with efficient, mechanically flexible photovoltaics.

Postural responses to a suprapostural visual task among children with and without developmental coordination disorder

We sought to determine the effects of varying the perceptual demands of a suprapostural visual task on the postural activity of children with developmental coordination disorder (DCD), and typically developing children (TDC). Sixty-four (32 per group) children aged between 9 and 10 years participated. In a within-participants design, each child performed a signal detection task at two levels of difficulty, low (LD) and high difficulty (HD). During performance of the signal detection tasks we recorded positional variability of the head and torso using a magnetic tracking system. We found that task difficulty had a greater effect on task performance among the TDC group than among children with DCD. Overall positional variability was greater the DCD group than in the TDC group. In the TDC group, positional variability was reduced during performance of the HD task, relative to sway during performance of the LD task. In the DCD group, positional variability was greater during performance of the HD task than during performance of the LD task. In children, DCD may reduce the strength of functional integration of postural activity with the demands of suprapostural visual tasks.

Surface plasmonic effects of metallic nanoparticles on the performance of polymer bulk heterojunction solar cells

We have systematically explored how plasmonic effects influence the characteristics of polymer photovoltaic devices (OPVs) incorporating a blend of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C(61)-butyric acid methyl ester (PCBM). We blended gold nanoparticles (Au NPs) into the anodic buffer layer to trigger localized surface plasmon resonance (LSPR), which enhanced the performance of the OPVs without dramatically sacrificing their electrical properties. Steady state photoluminescence (PL) measurements revealed a significant increase in fluorescence intensity, which we attribute to the increased light absorption in P3HT induced by the LSPR. As a result, the rate of generation of excitons was enhanced significantly. Furthermore, dynamic PL measurements revealed that the LSPR notably reduced the lifetime of photogenerated excitons in the active blend, suggesting that interplay between the surface plasmons and excitons facilitated the charge transfer process. This phenomenon reduced the recombination level of geminate excitons and, thereby, increased the probability of exciton dissociation. Accordingly, both the photocurrents and fill factors of the OPV devices were enhanced significantly. The primary origin of this improved performance was local enhancement of the electromagnetic field surrounding the Au NPs. The power conversion efficiency of the OPV device incorporating the Au NPs improved to 4.24% from a value of 3.57% for the device fabricated without Au NPs.

Incidental primary hyperparathyroidism in a hypercalcaemic woman with tuberculous peritonitis

We report on a 51-year-old woman with initial hypercalcaemia and unknown ascites. In spite of unyielding laparoscopy, laparotomy showed findings compatible with tuberculous peritonitis (TBP). Unexpectedly, a series of examinations eventually revealed the concurrence of hyperparathyroidism due to a parathyroid adenoma. Anti-tuberculous regimen was given and was uneventful. However, hypercalcaemia was not decreased but sustained at a high level even after anti-tuberculous therapy for 3 months. Parathyroidectomy was performed with subsequent normalisation of hypercalcaemia. The aetiology of hypercalcaemia in a patient with an explored disease able to cause this electrolyte abnormality such as TBP may be a coexistent occult parathyroid adenoma.