Improving temperature characteristics of GaN-based ultraviolet laser diodes by using InGaN/AlGaN quantum wells.

Temperature characteristics of GaN-based laser diodes are investigated. It is noted that the characteristic temperature of the threshold current (T0) decreases with decreasing lasing wavelength for GaN-based LDs. The performance deteriorates seriously for UV LDs at high temperature. It is ascribed to the increase of carriers escaping from quantum wells due to the lower potential barrier height. In this Letter, AlGaN is used as the barrier layer in UV LDs instead of GaN to improve the temperature characteristic of the threshold current and slope efficiency by increasing the potential barrier height of quantum wells. Based on this structure, a high output power of 4.6 W is obtained at the injection current of 3.8 A; its lasing wavelength is 386.8 nm.

Effects of Trichinella spiralis and its serine protease inhibitors on autophagy of host small intestinal cells.

In eukaryotes, autophagy is induced as an innate defense mechanism against pathogenic microorganisms by self-degradation. Although trichinellosis is a foodborne zoonotic disease, there are few reports on the interplay between Trichinella spiralissurvival strategies and autophagy-mediated host defense. Therefore, this study focused on the association between T. spiralis and autophagy of host small intestinal cells. In this study, the autophagy-related indexes of host small intestinal cells after T. spiralis infection were detected using transmission electron microscopy, hematoxylin and eosin staining, immunohistochemistry, quantitative real-time polymerase chain reaction, and Western blotting. The results showed that autophagosomes and autolysosomes were formed in small intestinal cells, intestinal villi appeared edema, epithelial compactness was decreased, microtubule-associated protein 1A/1B-light chain 3B (LC3B) was expressed in lamina propria stromal cells of small intestine, and the expression of autophagy-related genes and proteins was changed significantly, indicating that T. spiralis induced autophagy of host small intestinal cells. Then, the effect of T. spiralis on autophagy-related pathways was explored by Western blotting. The results showed that the expression of autophagy-related pathway proteins was changed, indicating that T. spiralis regulated autophagy by affecting autophagy-related pathways. Finally, the roles of T. spiralis serine protease inhibitors (TsSPIs), such as T. spiralis Kazal-type SPI (TsKaSPI) and T. spiralis Serpin-type SPI (TsAdSPI), were further discussed in vitro and in vivo experiments. The results revealed that TsSPIs induced autophagy by influencing autophagy-related pathways, and TsAdSPI has more advantages. Overall, our results indicated that T. spiralis induced autophagy of host small intestinal cells, and its TsSPIs play an important role in enhancing autophagy flux by affecting autophagy-related pathways. These findings lay a foundation for further exploring the pathogenesis of intestinal dysfunction of host after T. spiralis infection, and also provide some experimental and theoretical basis for the prevention and treatment of trichinellosis.

Intervention effects of Trichinella spiralis excretory-secretory antigens on allergic asthma in mice.

Allergic asthma is a chronic, heterogeneous and inflammatory respiratory disease, and there are few medicines at present. An increasing number of studies indicate that Trichinella spiralis (T. spiralis) and its excretory-secretory (ES) antigens are inflammatory modulator. Therefore, this study focused on the effects of T. spiralis ES antigens on allergic asthma. Asthma model was established by sensitizing mice with ovalbumin antigen (OVA) and aluminum hydroxide (Al[OH]3), the asthmatic mice were interfered using T. spiralis 43 kDa protein (Ts43), T. spiralis 49 kDa protein (Ts49), and T. spiralis 53 kDa protein (Ts53), the important components of ES antigens, to establish ES antigens intervention models. Then, asthma symptom changes, weight changes, and lung inflammation of mice were evaluated. The results showed that ES antigens could relieve symptoms, weight loss, and lung inflammation caused by asthma in the mice, and the effect of combined intervention of Ts43, Ts49, and Ts53 was better. Finally, the effects of ES antigens on type 1 helper T (Th1) and type 2 helper T (Th2) immune responses, and the differentiation direction of T lymphocytes in mice were discussed by detecting Th1 and Th2 cell-related factors and the ratio of CD4+/CD8+ T cells. The results suggested that the ratio of CD4+/CD8+ T cells decreased and the ratio of Th1/Th2 cells increased. In conclusion, this study indicated that T. spiralis ES antigens could mitigate allergic asthma in the mice by changing the differentiation direction of CD4+ and CD8+ T cells and regulating the imbalance of Th1/Th2 cells ratio.

Three-dimensional finite element analysis on cochlear implantation electrode insertion.

Studying the insertion process of cochlear implant (CI) electrode array (EA) is important to ensure successful, sufficient, and safe implantation. A three-dimensional finite element (FE) model was developed to simulate the insertion process. The cochlear structures were reconstructed from an average statistical shape model (SSM) of human cochlea. The electrode is simplified as a long and tapered beam of homogeneous elastic materials, contacting and interacting with the stiff cochlear structures. A quasi-static insertion simulation was conducted, the insertion force and the contact pressure between the electrode and the cochlear wall, were calculated to evaluate the smoothness of insertion and the risk of potential cochlear trauma. Based on this model, different EA designs were analyzed, including the Young's modulus, the straight or bended shape, the normal or a more tapped section size. The influence of the insertion angle was also discussed. Our simulations indicate that reducing the EA Young's modulus, tapering and pre-bending are effective ways to ensure safe and successful EA implantation. This model is beneficial for optimizing EA designs and is potentially useful for designing patient-specific CI surgery.

Social Rank or Social Bonds: Which one Facilitates Coalition Formation in Male Tibetan Macaques?

Previous studies have shown that fierce competition could promote male coalitions. There are two ways for males to choose their allies in the conflict. The first is that supporters choose high-ranking individuals, and the second is that supporters choose affiliated individuals. It is necessary to clarify the factors for forming a coalition and the process of cooperation in primates with complex relationships and strict hierarchies. Thus, we conducted a study on a group of free-ranging Tibetan macaques (Macaca thibetana) in Anhui, China, and recorded the whole process of male macaques forming coalitions once agonistic support occurred. The results showed that a higher intensity of the social bond between males was associated with more frequent coalitions. Dominance rank also significantly influenced male coalitions, showing that high-ranking individuals allied more frequently. Moreover, males with longer residence times formed more stable coalitions. We suggest that male Tibetan macaques form a stable social relationship, where social bond and social rank both promote the formation of a coalition. This study provided some insights into the mechanism by which social cooperation develops in multi-male and multi-female groups.

Individual Variation in the Use of Acoustic Signals to Coordinate Group Movements among Tibetan Macaques (Macaca thibetana).

To maintain group cohesion, social animals need to coordinate their actions during group movements. Several species use vocalizations to communicate with each other during coordination. However, the process of vocal communication and its influence in collective decision making is not clear. We studied a group of free-range Tibetan macaques (Macaca thibetana) at Huangshan, China, and recorded acoustic signals during their group movements. It was found that three kinds of sounds were used in their movements. Group movements with vocalizations recruited more participants than the movements without sound. Moreover, during group departures, individuals in the front emitted a higher frequency of vocalization than individuals in the rear. Sex and social centrality both had a significant influence on vocalizations. Social centrality indicates the degree of proximity relations between two individuals in a social network. Females and individuals with high social centrality emitted more sound in group movements. However, social rank and the number of relatives did not affect the emission of sound. These results suggest that the function of calls in collective movements relates to coordinating group movements. This study provides an insight into the association of acoustic communication with collective decision making.

"Emotional Proximity" and "Spatial Proximity": Higher Relationship Quality and Nearer Distance Both Strengthen Scratch Contagion in Tibetan Macaques.

Behavioral contagion has been defined as a phenomenon in which an unlearned behavior automatically triggers a similar behavior in others. Previous studies showed that a behavioral contagion might have the function of strengthening social relationships, promoting group coordination and maintaining social cohesion. However, so far, there are few studies investigating the correlation between contagious scratching and social bonding. Tibetan macaques (Macaca thibetana) live in multi-male and multi-female cohesive matrilineal groups, and scratching is usually observed in their affiliated interactions. We investigated the process of scratch contagion in one group of free-ranging Tibetan macaques and explored whether behavioral contagion could consolidate social relationships and maintain social stability. Results showed that the scratching was contagious and correlated with relationship quality and spatial distance. In dyads with a higher Dyadic Composite Sociality Index (DSI), the contagion was strong. In addition, contagions occurred more frequently and faster among individuals nearer to each other. In terms of social groups, members with higher social centrality participated in more behavioral contagion, whether as expressers or observers. Our findings provide new perspectives for studying behavioral contagions in humans and animals.

Room temperature continuous-wave operated 2.0-W GaN-based ultraviolet laser diodes.

Temperature characteristics of near-UV laser diodes (LDs) with a lasing wavelength of 384 nm are investigated. The characteristic temperature of threshold current (T0) of the UV LDs is low. Thus, the performance of the UV LDs under continuous wave (CW) operation is not as good as under pulsed operation especially at a high injection current. In addition, it is found that self-heating is a key factor for CW characteristics of the UV LDs, where suppression of the self-heating by using thick waveguide layers can increase the critical current of thermal rollover of the UV LD's operation. A high CW output power of 2.0 W is achieved for an InGaN near-UV LD with the n-side down on a sub-mount, whose threshold current density is 1.27 kA/cm2 and the highest wall plug efficiency (WPE) is approximately 15.9% at an injection current of 1.2 A.

Characteristics of immune function of full-term infants with different feeding patterns at the age of 3 months: a prospective cohort study. / ä¸åŒå–‚å »æ–¹å¼çš„è¶³æœˆå„¿3æœˆé¾„æ—¶å ç–«åŠŸèƒ½ç‰¹ç‚¹åˆ†æžçš„å‰çž»æ€§é˜Ÿåˆ—ç ”ç©¶.

OBJECTIVES: To explore the characteristics of immune function of healthy full-term infants at the age of 3 months, and to analyze the relationship of immune function with feeding pattern and sex. METHODS: A total of 84 healthy full-term infants born in four hospitals in Beijing and Hohhot, China were prospectively recruited. Their feeding patterns remained unchanged within 4 months after birth. They were divided into a breast-feeding group and a milk powder feeding group according to their feeding patterns. At the age of 3 months after birth, peripheral venous blood samples of the two groups were collected to evaluate cellular immunity and humoral immunity and perform routine blood test. The laboratory indices were compared between infants with different feeding patterns and sexes. RESULTS: Compared with the milk powder feeding group, the breast-feeding group had significantly lower proportion of T cell second signal receptor CD28, immunoglobulin M, and proportion and absolute count of neutrophils (P<0.05) and significantly higher expression and proportion of HLA-DR, a surface activation marker of CD8+ T cells, and proportion of lymphocytes (P<0.05). The male infants had a significantly lower white blood cell count and a significantly higher proportion of eosinophils compared with the female infants (P<0.05). CONCLUSIONS: Sex has no significant effect on the proportion of lymphocyte subsets in 3-month-old full-term infants, but feeding patterns are associated with the proportion of CD28+ T cells (lymphocyte functional subset) and HLA-DR+ T cells (lymphocyte activation subset), suggesting that feeding patterns have a certain effect on the development of immune function in 3-month-old full-term infants.

Relative mobility of screw versus edge dislocations controls the ductile-to-brittle transition in metals.

Body-centered cubic metals including steels and refractory metals suffer from an abrupt ductile-to-brittle transition (DBT) at a critical temperature, hampering their performance and applications. Temperature-dependent dislocation mobility and dislocation nucleation have been proposed as the potential factors responsible for the DBT. However, the origin of this sudden switch from toughness to brittleness still remains a mystery. Here, we discover that the ratio of screw dislocation velocity to edge dislocation velocity is a controlling factor responsible for the DBT. A physical model was conceived to correlate the efficiency of Frank-Read dislocation source with the relative mobility of screw versus edge dislocations. A sufficiently high relative mobility is a prerequisite for the coordinated movement of screw and edge segments to sustain dislocation multiplication. Nanoindentation experiments found that DBT in chromium requires a critical mobility ratio of 0.7, above which the dislocation sources transition from disposable to regeneratable ones. The proposed model is also supported by the experimental results of iron, tungsten, and aluminum.

[Efficacy and safety of less invasive surfactant administration in the treatment of neonatal respiratory distress syndrome: a Meta analysis].

OBJECTIVE: To evaluate the efficacy and safety of less invasive surfactant administration (LISA) in the treatment of neonatal respiratory distress syndrome (NRDS). METHODS: PubMed, Cochrane Library, Embase, China Biology Medicine disc, China Scientific Journal Database, CNKI Database, and Wanfang Database were searched for randomized controlled trials (RCTs) on the use of LISA strategy in the treatment of NRDS. Literature screening and quality assessment were performed according to inclusion and exclusion criteria. Review Manager 5.3 software was used to perform the Meta analysis. RESULTS: A total of 9 RCTs were included, with a total of 1 212 children with NRDS. There were 611 children in the experimental group (treated with LISA strategy) and 601 children in the control group [treated with intubation-surfactant-extubation (INSURE) strategy]. The Meta analysis showed that the use of LISA strategy reduced the rate of mechanical ventilation within 72 hours after birth (OR=0.39, 95%CI: 0.29-0.51, P<0.001) and the incidence rates of bronchopulmonary dysplasia (OR=0.53, 95%CI: 0.38-0.72, P<0.001) and pneumothorax (OR=0.56, 95%CI: 0.33-0.93, P=0.02). There were no significant differences in the mortality rate and incidence rates of other neonatal diseases between the two groups (P>0.05). There was no significant difference in the rate of repeated use of pulmonary surfactant (PS) between the two groups (P>0.05), but there was a higher incidence rate of PS reflux observed by LISA strategy (OR=2.60, 95%CI: 1.64-4.12, P<0.001). CONCLUSIONS: Compared with INSURE strategy, LISA strategy has advantages in reducing the need for mechanical ventilation and the incidence rates of bronchopulmonary dysplasia and pneumothorax in children with NRDS.

Puerarin protects against high-fat high-sucrose diet-induced non-alcoholic fatty liver disease by modulating PARP-1/PI3K/AKT signaling pathway and facilitating mitochondrial homeostasis.

As yet, there was no effective pharmacological therapy approved for non-alcoholic fatty liver disease (NAFLD). Here, we aimed to evaluate the therapeutic potential of puerarin against NAFLD and explored the underlying mechanisms. C57BL/6J mice were fed with a high-fat high-sucrose (HFHS) diet with or without puerarin coadministration intragastrically. The levels of hepatocellular injury, steatosis, fibrosis, and mitochondrial and metabolism alteration were detected. First, puerarin ameliorated histopathologic abnormalities due to HFHS. We observed a marked increase in hepatic lipid content, inflammation, and fibrosis level, which were attenuated by puerarin. Possible mechanisms were related to puerarin-mediated activation of PI3K/AKT pathway and further improvement in fatty acid metabolism. Puerarin restored the NAD+ content and beneficially affected the hepatic mitochondrial function, which attenuated HFHS-induced steatosis and metabolic disturbances. Finally, hepatic PARP-1 was activated due to excessive fat intake. Puerarin attenuated the PARP-1 expression in HFHS-fed mice, and PJ34, the PARP inhibitor, could mimic these protections of puerarin. However, pharmacological inhibition of PI3K disabled the protection of puerarin or PJ34 toward NAD+ refilling and mitochondrial homeostasis. In conclusion, our findings indicated that puerarin could be a promising and practical therapeutic strategy in NAFLD through modulating PARP-1/PI3K/AKT signaling pathway and further facilitating mitochondrial function.

[Relationship between R236C site in exon 7 of SP-B gene and respiratory distress syndrome in Han newborns in western Inner Mongolia].

OBJECTIVE: To detect and analyze the genetic variation in exon 7 of lung surfactant protein B (SP-B), and to investigate the relationship between the genetic variation and the incidence of neonatal respiratory distress syndrome (NRDS) in Han populations in western Inner Mongolia. METHODS: In the case-control study, 47 Han infants with NRDS were assigned to case group. All the 47 patients had the last three generations of their ancestors reside in western Inner Mongolia. Forty-seven Han newborns without NRDS were assigned to control group. PCR-based gene analysis was used to determine the mutation in exon 7 of SP-B gene and genotype and allele frequencies of the R236C site in exon 7 of SP-B gene. RESULTS: In Han newborns in western Inner Mongolia, there was no mutation in exon 7 of SP-B gene; two genotypes, CC and CT, were identified in the R236C site in exon 7 of SP-B gene. No TT genotype was found in the two groups. There were no significant differences in the genotype frequency of CC or CT as well as the allele frequency of C or T between the case and control groups (CC: 72% vs 85%, P>0.05; CT: 28% vs 15%, P>0.05; C: 85% vs 93%, P>0.05; T: 15% vs 7%, P>0.05). CONCLUSIONS: There is no mutation in exon 7 of SP-B gene in Han infants with NRDS in western Inner Mongolia. There is no significant association between the gene polymorphism of the R236C site in exon 7 of SP-B gene and the incidence of NRDS in Han populations in that region.

[Effects of simvastatin on the proliferation of HepG2 cells].

OBJECTIVE: To investigate the effects of simvastatin on the proliferation, cell cycle and expression of cyclin-dependent kinase inhibitor p21 protein in human hepatocellular carcinoma (HepG2) cells in vitro. METHODS: HepG2 cells were administrated with simvastatin. Proliferation of the cells was detected by MTT assay, cell cycle was measured by flowcytometry and the cyclin-dependent kinase inhibitor p21 protein expression was detected by immunocytochemistry. The results were evaluated by factorial design and one-way analysis of variance. RESULTS: Simvastatin inhibited HepG2 cells growth in vitro (F(concentration) = 1264, P value less than 0.001; F(time) = 17.466, P value less than 0.001; F(concentration*time) = 35.053, P value less than 0.001) and could arrest HepG2 cells in G0/G1 phase of cell cycle. However, apoptosis of HepG2 cells was not obvious. Simvastatin could also increase cyclin-dependent kinase inhibitor p21 protein expression (F = 512.133, P value less than 0.001). CONCLUSION: Simvastatin can inhibit the growth of HepG2 cells in vitro, which may be explained by its effects of enhancing cyclin-dependent kinase inhibitor p21 protein expression and arresting HepG2 cells at G0/G1 phase of cell cycle.

Stabilization of cobalt oxyhydrate superconductor.

Stabilization of cobalt oxyhydrate superconductor was realized by post-treatment of the as-prepared superconductor in concentrated NaOH solution; this finding is expected to promote future experimental research on the intriguing material.

[Establishment and melting of charge ordering in La0.3Ca0.7Mn(1-x)W(x)O3 system].

Polycrystalline samples of La0.3Ca0.7Mn(1-x)W(x)O3 (0.00 < or = x < or = 0.15) were prepared by conventional solid-state reaction method. The influence of W doping at Mn site on the magnetic transition of La0.3Ca0.7Mn(1-x)W(x)O3 system was studied by the measurements of magnetization-temperature (MT) curves, magnetization-magnetic intensity (MH) curves, and ESR spectra. The results show that, with the increase in W doping amount, the magnetic transition of the system exhibits a complicated charge process, when the doping amount is 0.00 < or = x < or = 0.08, the charge-ordering (CO) phase exists in the system, AFM/CO states coexist below the transition temperature, and the charge-ordering temperature (Tco) goes up with the increase in W doping content; when x > or = 0.12, the charge ordering (CO) state of the system weakens and melts, and paramagnetism-ferromagnetism (PM-FM) transition exists at extremely low temperature.

[Magnetic properties and transport behaviors in double doped La(0.67+1.33x)Sr(0.33-1.33x)Mn(1-x)Mg(x)O3 system].

The M-T curves, M-H curves, ESR curves, infrared spectrum, Raman spectrum, rho-T curves and MR-T curves of La(0.67+1.33x)Sr(0.33-1.33x)Mn(1-x)Mg(x)O3 (0.00 < or = x < or = 0.25) were studied. The experiment pointed out that all samples exhibit a paramagnetic-ferromagnetic (PM-FM) transition associated with metallic-insulating (MI) transition in the low doping region, which does not occur in the heavy doping zone. The authors suggest that this behavior is attributed to the difference between the Jahn-Teller distortion of the Mn3+ ion neighboring Mg2+ and that of the Mn3+ ion non-neighboring Mg2+, which is confirmed by the IR and Raman spectra. The anomalous transport behavior is dominated by the differerent Jahn-Teller distortion.

[Phase separation and transport behaviors in La(0.7 - x)Dy(x)Sr0.3MnO3 system].

The influence of Dy doping (0.00 < or = x < or = 0.30) on magnetic and electric properties of La0.7Sr0.3MnO3 was studied by measuring M-T curves, M-H curves, ESR curves, rho-T curves and MR-T curves of the samples. The experimental results indicate that all samples undergo the transition from paramagnetism to ferromagnetism at T(C). When T < T(C), the doped samples enter the cluster-spin glass state, and the antiferromagnetism is exhibited at lower temperature. For the samples x = 0.2, the phase separation occurs at the temperature far above T(C), the variation in magnetic structure caused by Dy doping leads to colossal magnetoresistance.