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In this paper, we investigate a novel physical layer secure (PLS) potential technique which is summarized into a category of index modulation (IM) scheme, namely the spatial field digital modulation (SFDM). In an SFDM communication system, bit streams are modulated in the spatial distribution of electromagnetic (EM) field. Orbital angular momentum (OAM) mode groups can be utilized for beamforming and thus realize an OAM based SFDM (OAM-SFDM) system. This kind of IM systems that utilize the distribution of EM field to transmit information can radiate different signals to different directions and possess inherent anti-eavesdropping capability. Since an eavesdropper lacks prior knowledge, it is difficult to construct appropriate and effective estimators for signal demodulation. However, such system is vulnerable when potential eavesdroppers adopt clustering algorithm, a type of non-realtime demodulation. We propose two PLS strategies with different computational complexity, the power hopping (PH) method and the symbol variation (SV) method, to confront single-antenna eavesdroppers and multi-antenna eavesdroppers, respectively. Both approaches are key-free, and do not require any prior channel state information (CSI) about eavesdroppers. The mentioned methods could constantly disrupt the statistical properties of eavesdroppers’ channels and even their received signals. Theoretical analysis and numerical simulations have been conducted to validate the feasibility of these two schemes. Furthermore, a prototype of OAM-SFDM based PLS communication system is built in a realistic scenario. The experimental results demonstrate that both PH method and SV method can effectively resist clustering algorithm in their corresponding application scenarios.

The structured beams, which can manipulate arbitrary intensity and phase of electromagnetic rays, are significant in communication and sensing. The vortex electromagnetic wave carrying orbital angular momentum (OAM) exhibits the phase distribution of the helical wavefront, which can be viewed as a complete set of eigenmodes for electromagnetic waves. It provides a flexible beamforming method to achieve the azimuthal pattern diversity by the spatial superposition of multiple specific OAM modes. We have proposed a novel form of OAM wave with a two-dimensional structure called plane spiral OAM (PS-OAM), which is conducive to overlapping different modes. Based on this, the PS-OAM mode-group can be employed to modify the spatial beam structure and form structured electromagnetic beams. This kind of beam not only retains the inherent vorticity and orthogonality of the OAM waves but also tackles the difficulties in applications stemming from the singularity-caused dark zone and beam divergence of conventional OAM waves. In this paper, the construction and manipulation of the structured beams are investigated, and the properties are analyzed. The potential applications in multiple-input multiple-output (MIMO) communication, orthogonal multiplexing communication, and spatial field digital modulation (SFDM) communication are envisioned.

Defensins are critical components of the innate immune system and play an important role in the integration of innate and adaptive immune responses. Although information on the immunomodulatory properties of peptidoglycan from bacteria is abundant, little is known about the β-defensin induction effect of peptidoglycan from the probiotic Lactobacillus. This study investigated the effect of intact peptidoglycan from L. rhamnosusMLGA on the induction of avian β-defensin 9 in chicken immune cells and intestinal explants. Peptidoglycan from Lactobacillus rhamnosusMLGA dose dependently promoted avian β-defensin 9 mRNA expression in chicken PBMCs, splenocytes, thymocytes, hepatocytes, and chicken embryo jejunum, ileum, and cecum explants and increased the capacity of PBMC or splenocyte lysates to inhibit the growth of SalmonellaEnteritidis. In contrast to the effect of L. rhamnosusMLGA-derived peptidoglycan, peptidoglycan derived from pathogenic Staphylococcus aureusreduced avian β-defensin 9 mRNA expression in chicken PBMCs and splenocytes. The inducible effect of peptidoglycan from L. rhamnosusMLGA on avian β-defensin 9 expression in PBMCs and splenocytes was observed without activation of the expression of associated pro-inflammatory cytokines IL-1β, IL-8, and IL-12p40, whereas these cytokine expressions were suppressed by peptidoglycan hydrolysate obtained by lysozyme digestion. The results of the present study show the capability of peptidoglycan derived from L. rhamnosusMLGA to induce the antimicrobial peptide defensin while simultaneously avoiding the deleterious risks of an inflammatory response.

An objective, comprehensive and scientific evaluation of emergency medical rescue capability (EMRC) is of great realistic significance in assisting the health administrative department to grasp the overall response capability of all emergency medical rescue teams, enabling each team to have a full understanding of its own strengths and weakness and improve itself accordingly. At present, the research on the evaluation of EMRC in Hazardous Chemicals Accidents (HCA) is not systematic and in-depth, and the existing research results also have some shortcomings, such as, the lack of strong theoretical support for the evaluation index system, the relatively single function of evaluation methods, and so on. The objective of this article is to research the evaluation index system and a new evaluation method of EMRC in HCA to overcome the above shortcomings. It establishes an emergency medical rescue capability model by employing the competency model and then constructs the evaluation index system on the basis of the analysis of all the factors of emergency medical rescue capability in hazardous chemical accidents and sets up an evaluation model based on the theory of connection numbers and partial connection numbers. It determines the competence ranking of several emergency medical rescue teams and the competence state of an individual emergency medical rescue team by calculating the connection principal value, and it also predicts how the emergency medical rescue capability will develop based on the values of partial connection numbers. The example shows that the calculation process of this model is relatively simple, and its assessment results are objective and authentic, and moreover, its multi-functions can make up for the deficiency of the simplified function of other evaluation models. This method is scientific and rational to some extent and can provide reference for evaluation problems of the same kind.

Background: An objective, comprehensive and scientific evaluation of emergency medical rescue capability (EMRC) is of great realistic significance in assisting the health administrative department to grasp the overall response capability of all emergency medical rescue teams, enabling each team to have a full understanding of its own strengths and weakness and improve itself accordingly. At present, the research on the evaluation of EMRC in Hazardous Chemicals Accidents (HCA) is not systematic and in-depth, and the existing research results also have some shortcomings, such as, the lack of strong theoretical support for the evaluation index system, the relatively single function of evaluation methods, and so on.Objectives: The objective of this article is to research the evaluation index system and a new evaluation method of EMRC in HCA to overcome the above shortcomings.Methods: It establishes an emergency medical rescue capability model by employing the competency model and then constructs the evaluation index system on the basis of the analysis of all the factors of emergency medical rescue capability in hazardous chemical accidents and sets up an evaluation model based on the theory of connection numbers and partial connection numbers. It determines the competence ranking of several emergency medical rescue teams and the competence state of an individual emergency medical rescue team by calculating the connection principal value, and it also predicts how the emergency medical rescue capability will develop based on the values of partial connection numbers.Results: The example shows that the calculation process of this model is relatively simple, and its assessment results are objective and authentic, and moreover, its multi-functions can make up for the deficiency of the simplified function of other evaluation models.Conclusion: This method is scientific and rational to some extent and can provide reference for evaluation problems of the same kind.

In this study, a new xylanase gene (RuXyn) was obtained from a rumen metagenome and heterologously expressed in Escherichia colito produce xylo-oligosaccharides (XOS) as a prebiotic. RuXyn, which belongs to the glycosyl hydrolase 10 (GH10) family, exhibited maximum activity at pH 6.0 and 50 °C, with excellent temperature resistance at 30–50 °C. RuXyn showed preferential hydrolysis of xylan, especially rice straw xylan. RuXyn activity was significantly increased in the presence of 5 mM dithiothreitol, 0.5% Tween-20, and 0.5% Triton X-100 (31%, 37%, and 43%, respectively). Reaction time (10, 15, 30, and 45 min) and dosage (0.15, 0.31, and 0.62 U) of RuXyn affected XOS yield and composition, with a maximum yield at 0.62 U and 30 min. The primary degradation products of wheat straw xylan, resulting from RuXyn activity, were xylotetraose, xylotriose, and xylopentose, which accounted for 33.4%, 33.0%, and 26.4% of the total sugar yield, respectively. The prebiotic effects of XOS were evaluated by in vitrofermentation of XOS using known probiotic Bifidobacterium bifidumand Levilactobacillus brevisstrains. Results showed that regardless of incubation time and XOS concentration, XOS stimulated the growth and xylanolytic enzyme secretion of the two probiotics compared to the controls. Supplementation with XOS significantly enhanced lactate production in B. bifidumand L. brevis. Thus, these results indicate that RuXyn is capable of hydrolyzing wheat xylan to produce XOS with a degree of polymerization 3 and 5 and to subsequently promote the growth of probiotics.

AbstractIn the present study, the effect of niacin supplementation on the growth performance and nutrient utilisation in Chinese Jinjiang cattle was investigated. A total of 48 finishing male Jinjiang cattle aged 24–30 months, with body weights of 200 ± 15 kg, were randomly divided into four groups. The cattle were fed a finishing diet (concentrate to forage ratio of 80:20). The diets for the control, NA320, NA480and NA640groups were supplemented with 0, 320, 480 or 640 mg/kg of niacin, respectively. The body weight and feed consumption of the 48 cattle were recorded on days 1, 28, and 56 of the experiment. Assessment of feed digestibility was conducted from days 52 to 56 of the study. Blood samples were collected from each animal on day 56. From days 1 to 56 of the study, the results indicated a significant increase in the average daily weight gains (p < .05) and lower feed to gain ratios (p < .05) for the NA480and NA640groups than for the control group. Furthermore, supplementation with 640 mg/kg niacin increased the apparent digestibility of all nutrients (p < .05), whereas supplementation with 480 mg/kg niacin enhanced the apparent digestibility of crude protein (p < .05). Moreover, supplementation with 480 and 640 mg/kg niacin increased the content of serum nonesterified fatty acids (p < .05). Therefore, it was concluded that supplementation with 640 mg/kg niacin in a high-concentrate diet may be beneficial to growth and nutrient utilisation in Chinese Jinjiang cattle.

To understand the effects of niacin on the ruminal microbial ecology of cattle under high-concentrate diet condition, Illumina MiSeq sequencing technology was used. Three cattle with rumen cannula were used in a 3 × 3 Latin-square design trial. Three diets were fed to these cattle during 3 periods for 3 days, respectively: high-forage diet (HF; forage-to-concentrate ratio = 80:20), high-concentrate diet (HC; forage-to-concentrate ratio = 20:80), and HC supplemented with 800 mg/kg niacin (HCN). Ruminal pH was measured before feeding and every 2 h after initiating feeding. Ruminal fluid was sampled at the end of each period for microbial DNA extraction. Overall, our findings revealed that subacute ruminal acidosis (SARA) was induced and the α-diversity of ruminal bacterial community decreased in the cattle of HC group. Adding niacin in HC could relieve the symptoms of SARA in the cattle but the ruminal pH value and the Shannon index of ruminal bacterial community of HCN group were still lower than those of HF group. Whatever the diet was, the ruminal bacterial community of cattle was dominated by Bacteroidetes, Firmicutesand Proteobacteria. High-concentrate diet significantly increased the abundance of Prevotella, and decreased the abundance of Paraprevotella, Sporobacter, Ruminococcusand Treponemathan HF. Compared with HC, HCN had a trend to decrease the percentage of Prevotella, and to increase the abundance of Succiniclasticum, Acetivibrioand Treponema. Increasing concentrate ratio could decrease ruminal pH value, and change the ruminal microbial composition. Adding niacin in HC could increase the ruminal pH value, alter the ruminal microbial composition.

Algebraic immunity (AI) is a new cryptographic criterion proposed against algebraic attacks. Extended algebraic immunity (EAI) extends the concept of algebraic immunity, whose point is that a Boolean function fmay be replaced by another Boolean function fccalled the algebraic complement of fIn this paper, we investigate EAI of Boolean functions. Firstly, we present a sufficient and necessary condition to judge AI of a Boolean function equals to its EAI. Secondly, we prove that two classes of Boolean functions with maximum AI also have optimal EAI. Finally, we analyze that the structure of the annihilators of Boolean functions with the algebraic complement.