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A theoretical–experimental approach is proposed to convert the photoluminescence spectra of colloidal perovskite quantum dot ensembles into accurate estimates for their intrinsic particle size distribution functions. Two main problems were addressed and properly correlated: the size dependence of the first excitonic transition in a single cube-shaped quantum dot and the inhomogeneous broadening of the fluorescence line shape due to the size nonuniformity of the chemically prepared quantum dot suspension in addition to the single-dot homogeneous broadening. By applying the reported methodology to CsPbBr3 quantum dot samples belonging to the strong and intermediate confinement regimes, the calculated size distributions exhibited close agreement with those obtained from transmission electron microscopy, with precise estimates for the average particle size and standard deviation. Specifically for strongly confined ultrasmall CsPbBr3 quantum dots, the presented spectroscopic model for size distribution computation is based on a new analytical expression for the size-dependent bandgap, which was developed within the framework of the finite-depth square-well effective mass approximation accounting for band nonparabolicity effects. Such a quantum mechanical approach correctly predicts the expected transition to the intermediate confinement regime in sufficiently large quantum dots, which are traditionally described by the well-known bandgap equation in the infinite potential barrier limit with a spatially correlated electron–hole wavefunction and nonparabolic carrier effective masses. The proposed calculation scheme originates from general theoretical considerations so that it can be readily adapted to semiconductor quantum dots of many other systems, from all inorganic metal halides to hybrid perovskite materials, regardless of the adopted chemical synthesis route. [ABSTRACT FROM AUTHOR]

Fusarium ear rot (FER) is a disease that causes a decrease in grain quality in several popcorn fields in tropical regions. To contribute to the development of popcorn cultivars resistant to FER and superior in the main agronomic traits, the study aimed to compare gains in popping expansion (PE), grain yield (GY), and FER resistance through direct and indirect selection strategies by proposing a new super trait. The study was conducted in Campos dos Goytacazes, RJ. The traits were evaluated in 41 inbred lines from four environments using a randomized block design with four replicates. Six selection strategies and four selection intensities were tested. Direct selection on GY resulted in losses in PE and small gains in FER in the majority of the environments. Positive selection on PE resulted in FER reduction in scenarios of lower selection intensity. Selection by popping volume showed a satisfactory increase in GY and PE but was not effective in FER reduction. Selection by multi‐trait genotype–ideotype distance index resulted in GY increase only in some environments, PE increase in all environments, and FER reduction in all environments under higher selection intensities. The newly developed super trait popping volume without Fusarium (PVwF) showed the possibility of increasing GY (32.90% at 88.8%) and PE (5.10% at 10.20%) while simultaneously reducing FER in all environments and selection intensities (−6.30% at −6.70%). PVwF is an easily executable methodology to help popcorn breeders optimize gains in their programs. The lines L214, L217, L292, and L328 are more suitable for use in mating blocks aimed to develop superior popcorn hybrids. Core Ideas: Ear rot reduces the popping expansion in popcorn.The popping volume without Fusarium enabled simultaneous gains in yield, popping expansion, and reduction of ear rot in all environments.Higher selection intensities hinder the achievement of simultaneous gains in several environments. [ABSTRACT FROM AUTHOR]

The application of nonlinear optical effects in optoelectronic devices is still scarce because the irradiance threshold necessary to induce a specific effect is very high. In this context, knowing the frequency-resolved first order molecular hyperpolarizability (β) is essential to identifying regions where this response is intense enough to allow for applications in commercial devices. Thus, herein, we have determined the β spectral dependence of five new push–pull cinnamylidene acetophenone derivatives using femtosecond laser-induced Hyper-Rayleigh Scattering (HRS). A considerable increase in β values was observed in molecules. We found remarkable β values in regions near the two-photon resonance, which are mediated by electron withdrawing and donating groups. This effect was mapped using wavelength-tunable femtosecond Z-scan technique. Furthermore, it was modeled in light of the sum-over-states approach for the second- and third-order nonlinearities. Finally, our outcomes suggest a strategy to obtain large β values mediated by the 2PA transition. [ABSTRACT FROM AUTHOR]

Southern corn leaf blight (SCLB), caused by Bipolaris maydis, is an important leaf disease of popcorn. The use of resistant genotypes is the most suitable control option for this disease, but there are few sources of resistance described in popcorn germplasm for use in breeding programmes. This research aimed to identify new sources of resistance in a panel of popcorn inbred lines. A total of 184 lines were evaluated in the field twice a year for the incidence and severity of SCLB symptoms. A set of candidate lines for sources of resistance (CLSR) was selected and evaluated in a greenhouse under artificial inoculation based on joint analysis of variance and grouping of means. Data from the area under the disease progress curve (AUDPC), based on three symptom severity assessments, allowed the analysis of variance followed by the grouping of means. The lines presented high phenotypic variability for the incidence and severity of SCLB under field conditions, enabling the selection of lines with higher potential for resistance. The test of means for AUDPC in the greenhouse allowed the formation of five groups, with the highest resistance comprising 23 lines. This group gathered lines with resistance to SCLB, the potential for grain yield and expansion capacity, in addition to lines that stood out with satisfactory performance as parents in previous research. Twelve percent (23 lines) out of the total evaluated lines were indicated as a source of resistance to SCLB. [ABSTRACT FROM AUTHOR]

Abstract The aim of the current study was to investigate the pathogenicity of Bipolaris species associated with southern corn leaf blight (SCLB) in Brazil. Fungi were isolated from leaves presenting SCLB symptoms. Morphological features were described when the cultures were grown in Potato dextrose agar (PDA) medium. The ITS and GAPDH regions were used for phylogenetic analyses. The pathogenicity of B. maydis isolates was assessed in four popcorn lines under controlled conditions. Two Bipolaris species among the collected isolates were capable of infecting corn, namely, B. maydis and B. gossypina. Previous studies reporting the infection of corn by B. gossypina were not found; therefore, the present study appears to be the first to report it. Pathological differences between isolates were observed, and there was a significant isolate x line interaction. Line L692 was susceptible in all tests, while Line L623 was resistant to three B. maydis isolates. The isolate CF/UENF 482 of B. gossypina did not generate symptoms in the tested popcorn lines. The B. maydis isolates CF/UENF 477 and CF/UENF 501 were the most virulent. [ABSTRACT FROM AUTHOR]

Silver nanoparticles (AgNPs) exhibit very interesting properties that have been employed in several kinds of applications spanning from antibacterial activity to plasmon–polaritons generation. Nanoparticle size strongly influences these applications. However, the characterization of ultrasmall AgNPs (particle diameter < 10 nm) encompassing different aspects such as average size, polydispersion, shape (anisotropy), concentration, and density remains a challenging task. To address these challenges, we combined TEM measurements with a computational framework based on Mie–Gans theory. This allowed us to describe the aforementioned AgNP features accurately. The synthesis of AgNPs in an aqueous medium involved the use of silver nitrate as a chemical precursor and sodium borohydride as a reducing agent, with polyvinylpyrrolidone acting as a stabilizing agent. Our outcomes showed that increasing the concentration of the precursor and reducing agent with a fixed 1 : 2 molar ratio tends to yield ultrasmall AgNPs with low to moderate polydispersion, a nearly spherical shape (low anisotropy), concentration in the nanomolar range and density close to silver bulk. Also, we established an analytical expression that correlates the extinction molar absorptivity to AgNP size considering the nanoparticle shape. Notably, the computational framework proved to be highly effective in extracting crucial information about the AgNPs from UV-vis spectroscopy data. In conclusion, our study sheds light on the unique properties of ultrasmall AgNPs and presents a comprehensive approach for properly characterizing these nanoparticles, paving the way for further advancements in their applications. [ABSTRACT FROM AUTHOR]