Aphids exhibit seasonally alternating asexual and sexual reproductive modes. Different morphs are produced throughout the life cycle. To evaluate morph-specific fitness during reproductive switching, holocyclic Sitobion avenae were induced continuously under short light conditions, and development and reproduction were compared in each morph. Seven morphs, including apterous and alate virginoparae, apterous and alate sexuparae, oviparae, males, and fundatrices, were produced during the life cycle. The greatest proportions of sexuparae, oviparae, males, and virginoparae were in the G1, G2, G3, and G4 generations, respectively. Regardless of asexual or sexual morphs, alate morphs exhibited a marked delay in age at maturity compared with that of apterous morphs. Among the alate morphs, males had the longest age at maturity, followed by sexuparae and virginoparae. Among the apterous morphs, sexuparae were older at maturity than the fundatrices, virginoparae, and oviparae. The nymphs of each morph had equal survival potentials. For the same wing morphs, apterous sexuparae and oviparae exhibited substantial delays in the pre-reproductive period and considerable reductions in fecundity, compared with those of apterous virginoparae and fundatrices, whereas alate sexuparae and alate virginoparae had similar fecundity. The seven morphs exhibited Deevey I survivorship throughout the life cycle. These results suggest that sexual production, particularly in males, has short-term development and reproduction costs. The coexistence of sexual and asexual morphs in sexuparae offspring may be regarded as an adaptive strategy for limiting the risk of low fitness in winter.

Laser-accelerated electrons are promising in producing gamma-photon beams of high peak flux for the study of nuclear photonics, obtaining copious positrons and exploring photon–photon interaction in vacuum. We report on the experimental generation of brilliant gamma-ray beams with not only high photon yield but also low divergence, based on picosecond laser-accelerated electrons. The 120 J 1 ps laser pulse drives self-modulated wakefield acceleration in a high-density gas jet and generates tens-of-MeV electrons with 26 nC and divergence as small as $1.51{}^{\circ}$ . These collimated electrons produce gamma-ray photons through bremsstrahlung radiation when transversing a high-Z solid target. We design a high-energy-resolution Compton-scattering spectrometer and find that a total photon number of $2.2\times {10}^9$ is captured within an acceptance angle of $1.1{}^{\circ}$ for photon energies up to $16\;\mathrm{MeV}$ . Comparison between the experimental results and Monte Carlo simulations illustrates that the photon beam inherits the small divergence from electrons, corresponding to a total photon number of $2.2\times {10}^{11}$ and a divergence of $7.73{}^{\circ}$ .

To uncover the chewing mechanism of Cyrtotrachelus buqueti Guer, a mathematical model was created and a kinematic analysis of its rostrum mouthparts was conducted for, to our knowledge, the first time. To reduce noise and improve the quality of scanning electron micrographs of the weevil's mouthparts, nonlocal means and integral nonlocal means algorithms were proposed. Additionally, based on a comparison and analysis of five classical edge detection algorithms, a multiscale edge detection algorithm based on the B-spline wavelet was used to obtain the boundaries of structural features. The least squares method was used to analyze the data of the mouthparts to fit the mathematical model and fitted curves were obtained using Gaussian equations. The results show that curvature and concave–convex variations of the weevil's mouthparts can highlight fluctuations in friction effects when it chews bamboo shoots, which is helpful in preventing debris from bamboo shoots or other debris from sticking to the mouthpart surfaces. Moreover, this paper highlights the utility of micro-computed tomography (microCT) for three-dimensional (3D) reconstruction and a flowchart is suggested. The reconstructed slices were 9.0 μm thick and an accurate 3D rendered model was obtained from a series of microCT slices. Finally, a real model of the rostrum mouthparts was analyzed using finite-element analysis. The results provide a biological template for the design of a novel bionic drilling mechanism.

This work focuses on the application of nanoindentation measurements and the finite element method for analyzing the mechanical properties of the rostrum of the outstanding driller Cyrtotrachelus buqueti Guer. Nanoindentation tests were carried out to measure the Young's modulus and hardness of the rostrum, with the results for the “dry” samples being 13.886 ± 0.75 and 0.368 ± 0.0445 GPa, respectively. The values for the “fresh” samples showed no clear difference from those of the “dry” ones. Moreover, field observation was conducted to determine the motion behaviors of the rostrum on the weevil. Micro-computed tomography technology was employed to obtain structural information about the rostrum, using 9 µm slices. A real three-dimensional model of the rostrum was created using the MIMICS application. Finally, the mechanical properties of the rostrum were determined by finite element analysis. It was concluded that the rostrum provides an ideal biological template for the design of biocomposite materials and lightweight tube-shaped structures. The properties determined in this study can potentially be applied in different fields, such as in the design of automotive hybrid transmission shafts, helicopter tail drive shafts, robotic arms, and other sandwich structures in aerospace engineering.

Partial differential equations are powerful tools for used to characterizing various physical systems. In practice, measurement errors are often present and probability models are employed to account for such uncertainties. In this paper we present a Monte Carlo scheme that yields unbiased estimators for expectations of random elliptic partial differential equations. This algorithm combines a multilevel Monte Carlo method (Giles (2008)) and a randomization scheme proposed by Rhee and Glynn (2012), (2013). Furthermore, to obtain an estimator with both finite variance and finite expected computational cost, we employ higher-order approximations.

The consequences of urbanisation for Earth's biogeochemical cycles are largely unexplored. Copper (Cu) in urban soils is being accumulated mainly due to anthropogenic activities under rapid urbanisation. The increasing Cu concentrations may contribute to altering soil nitrogen (N) cycling in urban ecosystems through modulating denitrification processes. This research aims to identify how Cu impacts urban soil denitrification functions and denitrifier abundance. An urban park soil with a background total Cu concentration of 7.9μgg–1 was incubated anaerobically with different Cu amendments (10, 20, 40, 80 and 160μg Cu g–1 soil), similar to prevalent Cu contents in urban soils. We evaluated the soil denitrification functions using the acetylene (C2H2) inhibition method and assessed the denitrifier abundance by quantitative polymerase chain reaction (qPCR) analyses of denitrifying marker genes (nirK, nirS and nosZ). At the function level, we observed that both the potential soil denitrification activity and the N2O emission rate due to denitrification were significantly (P<0.05) inhibited by Cu; even the lowest Cu addition (10μg Cu g–1 soil) drastically affected the denitrification function. Moreover, Cu significantly (P<0.05) decreased the abundance of nirK and nirS genes at the additions of 160μg Cu g–1 soil and 40μg Cu g–1 soil, respectively, whereas it had no clear impact on nosZ gene copies. Further correlation analyses revealed that the potential denitrification activity was positively correlated to the copy numbers of nirK and nirS genes, but it was not correlated to nosZ gene abundance. These findings indicate that Cu additions inhibited soil denitrification function and decreased denitrifier abundance in the investigated urban park soil. Our results suggest that Cu accumulation in urban soils, resulting from urbanisation, may generally influence denitrification in urban ecosystems.

Two sets of rectangle samples with different length/width ratios were prepared and subjected to uniaxial compression in the normal direction of rolled pure titanium. Results from Electron backscatter diffraction (EBSD) show that the produced {11 $\bar 2$ 2} twins in the two sets of samples exhibit different orientations, which is related to the variant selection of twinning behaviors with respect to the length/width ratios of the samples. The variant selection criterion is investigated in terms of the Schmid factors and contribution of the active twins to external strain, which indicates that the variants resulting in the elongation along the longer direction of the sample were unfavorable.

In this study, the precipitation behavior of the pretwinned extruded Mg–6Al–1Zn alloy was investigated. It was observed that the precipitates preferentially nucleated at the twin boundaries or within the preexistent twins. This distribution of the precipitates led to the distinguishing influences on subsequent compression and tension process, which were dominated by twinning and detwinning of the preexistent twins, respectively. The compressive yield strength after aging was a little lower than the stress when the precompression was interrupted, which meant that the impeding effect of precipitation on twin expansion was relatively smaller than that of dislocations induced by precompression. However, the tensile yield strength of aged samples was extremely higher than that of non-aged samples as the migration of the twin boundaries during detwinning was considerably hindered because of the preferential precipitation within the preexistent {10-12} twins.

Parallel tempering simulation is widely used in enhanced sampling of systems with complex energy surfaces. We hereby introduce generalized canonical ensemble (GCE) instead of the usual canonical ensemble into the parallel tempering to further improve abilities of the simulation technique. GCE utilizes an adapted weight function to obtain a unimodal energy distribution even in phase-coexisting region and then the parallel tempering on GCE yields the steady swap acceptance rates (SARs) instead of the fluctuated SARs in that on canonical ensemble. With the steady SARs, we can facilitate assign the parameters of the parallel tempering simulation to more efficiently reach equilibrium among different phases. We illustrate the parallel tempering simulation on GCE in the phase-coexisting region of 2-dimensional Potts model, a benchmark system for new simulation method developing. The result indicates that the new parallel tempering method is more efficient to estimate statistical quantities (i.e., to sample the conformational space) than the normal parallel tempering, specially in phase-coexisting regions of larger systems.

Interspecies intracytoplasmic sperm injection has been carried out to understand species-specific differences in oocyte environments and sperm components during fertilization. While sperm aster organization during cat fertilization requires a paternally derived centriole, mouse and hamster fertilization occur within the maternal centrosomal components. To address the questions of where sperm aster assembly occurs and whether complete fertilization is achieved in cat oocytes by interspecies sperm, we studied the fertilization processes of cat oocytes following the injection of cat, mouse, or hamster sperm. Male and female pronuclear formations were not different in the cat oocytes at 6 h following cat, mouse or hamster sperm injection. Microtubule asters were seen in all oocytes following intracytoplasmic injection of cat, mouse or hamster sperm. Immunocytochemical staining with a histone H3-m2K9 antibody revealed that mouse sperm chromatin is incorporated normally with cat egg chromatin, and that the cat eggs fertilized with mouse sperm enter metaphase and become normal 2-cell stage embryos. These results suggest that sperm aster formation is maternally dependent, and that fertilization processes and cleavage occur in a non-species specific manner in cat oocytes.

Silicon nanoporous pillar array (Si-NPA) is a silicon hierarchical structure with regularly patterned surface morphology. Through a heterogeneous reaction process, zinc sulfide nanocrystallites (nc-ZnS) were grown onto Si-NPA and a unique heterostructure of ZnS/Si-NPA was obtained. The formation of wurtzite nc-ZnS was proved by x-ray diffraction, and the average grain size was evaluated to be ∼18 nm. X-ray photoelectron spectroscopy disclosed that as-grown nc-ZnS was well separated from Si-NPA by a SiO2 thin layer of ∼1.3 nm. The photoluminescence (PL) spectrum of ZnS/Si-NPA showed that in addition to the two red PL bands peaked at ∼648 and ∼705 nm observed in Si-NPA, three other PL bands peaked at ∼365, ∼418, and ∼472 nm were observed and attributed to the PL from nc-ZnS. It was also demonstrated that as-prepared ZnS/Si-NPA heterostructure could exhibit good rectification characteristic featured by a high forward current density of ∼75 mA/cm2 at 2 V and high reverse breakdown voltage of ∼10 V. Our results indicated that ZnS/Si-NPA might be a valuable heterostructure nanosystem to be further probed for achieving enhanced optical and electrical properties.

Two microsatellite markers OarHH35 and BMS2508, closely associated with high levels of reproduction in sheep, were analysed for polymorphisms in Xiangdong black goat, Nanjiang brown goat, Guizhou black goat and Boer goat. The number of alleles for OarHH35 was 11, 8, 7 and 10, respectively, in the four goat breeds. That for BMS2508 was 9, 5, 6 and 7. The polymorphic information content (PIC) values for OarHH35/BMS2508 in the above-mentioned goats were respectively 0.8294/0.8047, 0.8399/0.6894, 0.7985/0.6910 and 0.8582/0.7688. By analysing the dominant effect of the two microsatellite markers on litter size of Xiangdong black goat, it was shown that microsatellite markers BMS2508 and OarHH35 significantly influenced (P<0.05) litter size of goats. At the OarHH35 locus, the least squares means (LSM) of genotype 135/135 bp was the highest (3.67 number born/litter). Moreover, LSM of genotypes 123/135 bp and 125/125 bp also reached 3.00 kids born/litter, indicating that alleles 135 bp and 125 bp exerted a significant positive effect on the litter size in Xiangdong black goat. At the BMS2508 locus, LSM of genotypes 132/145 bp and 93/132 bp for litter size was 4.00 and 3.25 kids born/litter respectively, but that of genotype 122/122 bp for litter size was only 1.00 kid/litter, so alleles 145 bp and 93 bp had significant positive effects on the litter size of Xiangdong black goat, and the allele 122 bp had a significantly negative effect.

The mechanism of molybdenum and molybdenum oxide nanoparticles formation from molybdenum oxide microparticles by electron beam irradiation using a high-resolution transmission electron microscope on a room-temperature stage have been investigated. It is found that, the microsized molybdenum oxide particles disintegrated to form nanosized molybdenum oxide particles by electron beam irradiation with an intensity of approximately 1021e/cm2 · sec. The molybdenum nanoparticles were formed from molybdenum oxide nanoparticles upon further electron irradiation. During the electron irradiation process, the surfaces and interfaces of molybdenum oxide nanoparticles suffered damage and defects, such as vacancy arrays showing hole like spots and a moire-like fringes in the lattice image due to oxygen loss, followed by a gradual change from molybdenum oxide to molybdenum nanoparticles. The phenomenon of molybdenum metal nanoparticle formation from nanosized molybdenum oxide is considered to be due to desorption of oxygen as a result of electron stimulation and atomic displacement via the knock-on effect. It is suggested that electron irradiation is a powerful technique to create nanostructured metal, ceramic and semiconductor materials by atomic-scale control.

An investigation of the formation behavior and mechanism of onion like fullerene / metal polycrystalline film under electron beam irradiation is presented. Metallic nanoparticles of Al, Au and Pt having diameters of 1∼35 nm, were supported on an amorphous carbon film with thickness of about 20 nm. The amorphous carbon film transformed into onion-like fullerene film under electron beam irradiation, with intensity about 1020e/cm2·sec using high resolution transmission electron microscopy. The transformation mechanism and growth morphology have been investigated. It is found that the nucleation and growth process of onion-like fullerenes from amorphous carbon were divided into several steps: Firstly, a few elliptic shells of carbon were induced under Al, Au or Pt nanoparticles; secondly, a gradual reorganization took place into the structures composed of quasi-concentric spheroid or sphered graphite, i.e., onion like fullerenes, and finally, fullerenes were bonded to each other into a film.