Here, we report the generation of MeV alpha-particles from H-11B fusion initiated by laser-accelerated boron ions. Boron ions with maximum energy of 6 MeV and fluence of 109/MeV/sr@5 MeV were generated from 60 nm-thick self-supporting boron nanofoils irradiated by 1 J femtosecond pulses at an intensity of 1019 W/cm2. By bombarding secondary hydrogenous targets with the boron ions, 3 × 105/sr alpha-particles from H-11B fusion were registered, which is consistent with the theoretical yield calculated from the measured boron energy spectra. Our results demonstrated an alternative way toward ultrashort MeV alpha-particle sources employing compact femtosecond lasers. The ion acceleration and product measurement scheme are referential for the studies on the ion stopping power and cross section of the H-11B reaction in solid or plasma.

From 24 January 2020 to 18 May 2020, Chaoshan took measures to limit the spread of coronavirus disease 2019 (COVID-19), such as restricting public gatherings, wearing masks and suspending classes. We explored the effects of these measures on the pathogen spectrum of paediatric respiratory tract infections in Chaoshan. Pharyngeal swab samples were collected from 4075 children hospitalised for respiratory tract infection before (May–December 2019) and after (January–August 2020) the COVID-19 outbreak. We used liquid chip technology to analyse 14 respiratory pathogens. The data were used to explore between-group differences, age-related differences and seasonal variations in respiratory pathogens. The number of cases in the outbreak group (1222) was 42.8% of that in the pre-outbreak group (2853). Virus-detection rates were similar in the outbreak (48.3%, 590/1222) and pre-outbreak groups (51.5%, 1468/2853; χ2 = 3.446, P = 0.065), while the bacteria-detection rate was significantly lower in the outbreak group (26.2%, 320/1222) than in the pre-outbreak group (44.1%, 1258/2853; χ2 = 115.621, P < 0.05). With increasing age, the proportions of respiratory syncytial virus (RSV) and cytomegalovirus (CMV) infections decreased, while those of Mycoplasma pneumoniae and adenovirus infections increased. Streptococcus pneumoniae, CMV and rhinovirus infections peaked in autumn and winter, while RSV infections peaked in summer and winter. We found that the proportion of virus-only detection decreased with age, while the proportion of bacteria-only detection increased with age (Table 2). Anti-COVID-19 measures significantly reduced the number of paediatric hospitalisations for respiratory tract infections, significantly altered the pathogen spectrum of such infections and decreased the overall detection rates of 14 common respiratory pathogens. The proportion of bacterial, but not viral, infections decreased.

Sugarcane brown rust, caused by Puccinia melanocephala, is one of the main diseases of sugarcane in China. The identification and discovery of new resistance genes have important theoretical and practical significance for preventing outbreaks of brown rust and ensuring the sustainable production of sugarcane. To screen for polymorphic simple-sequence repeat (SSR) molecular markers for localization of brown rust resistance genes, we used two populations that are suitable for genetic linkage map construction and mapping of new resistance genes to construct resistant and susceptible genetic pools. We then screened 449 pairs of primers to identify polymorphic SSR markers in the parental lines and the resistant/susceptible genetic pools. The results showed that 25 pairs of primers directed amplification of polymorphic DNA fragments between the parents of the cross combination ‘Yuetang 03-393’ × ‘ROC 24’, and 16 pairs of primers amplified polymorphic fragments between the parents of the cross combination ‘Liucheng 03-1137’ × ‘Dezhe 93-88’. Four pairs of primers (SMC236CG, SCESSR0928, SCESSR0636 and SCESSR2551) amplified polymorphic DNA fragments between the parental lines and the resistant/susceptible genetic pools in ‘Yuetang 03-393’ × ‘ROC 24’. The results of this study will establish a solid foundation for the mapping of new brown rust resistance genes, genetic linkage map construction and the development of closely-associated molecular markers in sugarcane.

We assessed inheritance of resistance to sugarcane brown rust (Puccinia melanocephala) in selfing F1 populations of wild sugarcane germplasm Erianthus rockii ‘Yundian 95-19’ and E. rockii ‘Yundian 95-20’. We tested parent and selfing F1 individuals for the brown rust resistance gene, Bru1, that has been shown to confer resistance to brown rust in sugarcane. The Bru1 gene was not detected in E. rockii ‘Yundian 95-19’, E. rockii ‘Yundian 95-20’ or their selfing F1 individuals, and we found there was segregation of resistance in the two selfing F1 populations (segregation ratio: 3:1). The results confirmed resistance in E. rockii ‘Yundian 95-19’ and E. rockii ‘Yundian 95-20’ to sugarcane brown rust is controlled by a novel, single dominant gene.

Let $Q$ be an infinite subset of $\mathbb{N}$. For any ${\it\tau}>2$, denote $W_{{\it\tau}}(Q)$ (respectively $W_{{\it\tau}}$) to be the set of ${\it\tau}$ well-approximable points by rationals with denominators in $Q$ (respectively in $\mathbb{N}$). We consider the Hausdorff dimension of the liminf set $W_{{\it\tau}}\setminus W_{{\it\tau}}(Q)$ after Adiceam. By using the tools of continued fractions, it is shown that if $Q$ is a so-called $\mathbb{N}\setminus Q$-free set, the Hausdorff dimension of $W_{{\it\tau}}\setminus W_{{\it\tau}}(Q)$ is the same as that of $W_{{\it\tau}}$, i.e. $2/{\it\tau}$.

Let α∈(0,1) be an irrational, and [0;a1,a2,…] the continued fraction expansion of α. Let Hα,V be the one-dimensional Schrödinger operator with Sturmian potential of frequency α. Suppose the potential strength V >20 and the sequence (ai)i≥1 is bounded. We proceed by developing some new ideas on dimensional theory of Cookie-cutter sets. We prove that the spectral generating bands satisfy the principles of bounded variation and bounded covariation, and then we show that there exists a Gibbs-like measure on the spectrum σ(Hα,V). As an application, we prove that where s* and s* are the lower and upper pre-dimensions. Moreover, if (an)n≥1 is ultimately periodic, then s* =s*.

The population doubling number (70–80 times) of human fetal bone marrow mesenchymal stem cells (BMMSCs) is about two times higher than that (30–40 times) of adult BMMSCs, and their differentiation capacity is superior to that of their adult counterparts. In this study, BMMSCs were isolated from long bones of 2- to 3-month-old human abortuses by rinsing and selectively culturing whole marrow cells. Basic medium and serum concentration were optimized and growth curves plotted, both by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-di-phenyltetrazolium bromide] reduction assay. Isolated cells were identified by flow cytometry and immunocytochemistry for their antigen markers. The biosafety of isolated cells was evaluated by karyotype analysis and a tumour-forming experiment. The results indicated that lengthwise scissoring of fetal long bones and rinsing of their marrow cells was practical and useful for recovery of BMMSCs from the investigated human abortuses. In this experiment, α-MEM (minimum essential medium, alpha medium)+20% FCS (fetal calf serum) was the best for in vitro culture of BMMSCs. The third-passage BMMSCs expressed Oct4, SSEA3 and SSEA4 besides the surface markers of their adult counterparts. The population doubling time of the BMMSCs of passage 6, 12 and 24 were 34, 36 and 40 h, respectively. Cells in all passages showed a diploid karyotype and formed no tumours in nude mice. The BMMSCs used in this study proved to be biologically safe and ideal seed cells for research on human tissue engineering and regeneration medicine.

In this paper, we characterize the substitutions over a three-letter alphabet which generate a ultimately periodic sequence.

Multitype Moran sets are introduced in this paper. They appear naturally in the study of the structure of the quasi-crystal spectrum, and they generalize some known fractal structures such as self-similar sets, graph-direct sets and Moran sets. It is known that for any Moran set E with a bounded condition on contracting ratios, one has \[\dim_H E=s_*\le s^*=\dim_P E=\dimB E,\] where $s_*$ and $s^*$ are the lower and upper pre-dimension according to the natural coverings. For any multitype Moran set E with a bounded condition on contracting ratios, we prove $\dimB E{=}s^*$. With an additional assumption of primitivity, we prove that for multitype Moran sets, the above formula still holds. We also give some examples to show that if the condition of primitivity is not fulfilled, then it may happen that $\dim_H E<s_*$ or $\dim_P E<s^*$.

Let K be a compact subset of ℝn, 0[les ]s[les ]n. Let Ps0, [Pscr ]s denote s-dimensional packing premeasure and measure, respectively. We discuss in this paper the relation between Ps0 and [Pscr ]s. We prove: if Ps0(K)<∞, then [Pscr ]s(K) = Ps0(K); and if Ps0(K) = ∞, then for any ε>0, there exists a compact subset F of K such that [Pscr ]s(F) = Ps0(F) and [Pscr ]s(F)[ges ] [Pscr ]s(K)−ε.