Higher-order topological phases in crystalline and non-crystalline systems: a review.

In recent years, higher-order topological phases have attracted great interest in various fields of physics. These phases have protected boundary states at lower-dimensional boundaries than the conventional first-order topological phases due to the higher-order bulk-boundary correspondence. In this review, we summarize current research progress on higher-order topological phases in both crystalline and non-crystalline systems. We firstly introduce prototypical models of higher-order topological phases in crystals and their topological characterizations. We then discuss effects of quenched disorder on higher-order topology and demonstrate disorder-induced higher-order topological insulators. We also review the theoretical studies on higher-order topological insulators in amorphous systems without any crystalline symmetry and higher-order topological phases in non-periodic lattices including quasicrystals, hyperbolic lattices, and fractals, which have no crystalline counterparts. We conclude the review by a summary of experimental realizations of higher-order topological phases and discussions on potential directions for future study.

Experimental study of unconventional modified filling energy absorption and control mechanism in high energy storage rock masses.

Aiming at the problems that it is difficult to predict rock burst accurately in engineering practice and the implementation parameters of rock burst prevention measures depend on some empirical formulas, in order to study the advantages and disadvantages of different in-situ modification mechanisms deeply, determine the applicable conditions of unusual in-situ modification measures, and provide a theoretical basis for forming adaptive in-situ modification control schemes. Two kinds of modified control methods using the same foundation involve engineering scale and indoor scale. With the help of scale transformation, the whole failure process analysis test of bearing rock samples was carried out. The results show that various modification measures can effectively control the properties, and realize "hard-rock softening or soft-rock hardening" by changing the physical and mechanical parameters of the target rock sample. Compared with the control group, the automatic parameters of rocks deteriorated significantly under different modification measures. The evolution law of carrying energy is similar. However, there are obvious diversity between various modification measures in plastic stage and post-peaking phase stage, which provides favorable conditions for rock burst prevention. Based on this, an adaptive modification control system was constructed. At the same time, filling materials is considered to increase the energy of post-peaking phase (non newtonian fluid: energy-absorbing materials), and further slow down the intensity of released energy within post-peaking phase stage. Because rock burst is characterized by rapid release of energy, non newtonian fluid has a good absorption effect on high-speed impact force. Therefore, in the design test, the effect of non newtonian fluid is realized by applying a high loading rate, and the evaluation of energy absorption effect of bearing rock samples filled with non newtonian fluid in borehole is considered.

Isolation and identification of beneficial orchid mycorrhizal fungi in Paphiopedilum barbigerum (Orchidaceae).

Seed germination and seedling development in nearly all orchid species rely on a symbiotic relationship with mycorrhizal fungi; however, this is not the case with all mycorrhizal fungi. This study aims to provide an understanding about the important role of mycorrhiza in seed germination and growth of Paphiopedilum barbigerum. Therefore, we isolated and identified endophytic fungi from the roots of wild P. barbigerum. The beneficial mycorrhizal fungi Epulorhiza sp. FQXY019 and Tulasnella calospora FQXY017 were screened by seed symbiotic germination tests and found to promote seed germination. However, only the seeds inoculated with FQXY019 progressed from the seed germination to rooting stage. This shows that mycorrhizal fungi and P. barbigerum have a specific relation at different growth phases. In addition, we selected FQXY019 and inoculated it into MS medium, B5 medium, OMA medium, and PDA medium. The results showed that FQXY019 co-cultured on PDA significantly promoted the increase in seedling fresh weight, leaf length, and root length (p < .01). Furthermore, it significantly promoted the root number and leaf number of seedlings compared with those co-cultured on MS, B5, and OMA media and control (p < .05). Thus, this study demonstrated the promoting effect of Epulorhiza sp. FQXY019 on seed germination and seedling development, making it an alternative method for the artificial propagation of P. barbigerum.

Structural-Disorder-Induced Second-Order Topological Insulators in Three Dimensions.

Higher-order topological insulators are established as topological crystalline insulators protected by crystalline symmetries. One celebrated example is the second-order topological insulator in three dimensions that hosts chiral hinge modes protected by crystalline symmetries. Since amorphous solids are ubiquitous, it is important to ask whether such a second-order topological insulator can exist in an amorphous system without any spatial order. Here, we predict the existence of a second-order topological insulating phase in an amorphous system without any crystalline symmetry. Such a topological phase manifests in the winding number of the quadrupole moment, the quantized longitudinal conductance, and the hinge states. Furthermore, in stark contrast to the viewpoint that structural disorder should be detrimental to the higher-order topological phase, we remarkably find that structural disorder can induce a second-order topological insulator from a topologically trivial phase in a regular geometry. We finally demonstrate the existence of a second-order topological phase in amorphous systems with time-reversal symmetry.

Atomic Oxygen-Resistant Polyimide Composite Films Containing Nanocaged Polyhedral Oligomeric Silsesquioxane Components in Matrix and Fillers.

For the development of spacecraft with long-servicing life in low earth orbit (LEO), high-temperature resistant polymer films with long-term atomic oxygen (AO) resistant features are highly desired. The relatively poor AO resistance of standard polyimide (PI) films greatly limited their applications in LEO spacecraft. In this work, we successfully prepared a series of novel AO resistant PI composite films containing nanocaged polyhedral oligomeric silsesquioxane (POSS) components in both the PI matrix and the fillers. The POSS-containing PI matrix film was prepared from a POSS-substituted aromatic diamine, N-[(heptaisobutyl-POSS)propyl]-3,5-diaminobenzamide (DABA-POSS) and a common aromatic diamine, 4,4'-oxydianline (ODA) and the aromatic dianhydride, pyromellitic dianhydride (PMDA) by a two-step thermal imidization procedure. The POSS-containing filler, trisilanolphenyl POSS (TSP-POSS) was added with the fixed proportion of 20 wt% in the final films. Incorporation of TSP-POSS additive apparently improved the thermal stability, but decreased the high-temperature dimensional stable nature of the PI composite films. The 5% weight loss temperature (T5%) of POSS-PI-20 with 20 wt% of DABA-POSS is 564 °C, and its coefficient of linear thermal expansion (CTE) is 81.0 × 10-6/K. The former is 16 °C lower and the latter was 20.0 × 10-6/K higher than those of the POSS-PI-10 film (T5% = 580 °C, CTE = 61.0 × 10-6/K), respectively. POSS components endowed the PI composite films excellent AO resistance and self-healing characteristics in AO environments. POSS-PI-30 exhibits the lowest AO erosion yield (Es) of 1.64 × 10-26 cm3/atom under AO exposure with a flux of 2.51 × 1021 atoms/cm2, which is more than two orders of magnitude lower than the referenced PI (PMDA-ODA) film. Inert silica or silicate passivation layers were detected on the surface of the PI composite films exposed to AO.

Symmetry-Protected Topological Phases in a Rydberg Glass.

Recent theoretical studies predict that structural disorder, serving as a bridge connecting a crystalline material to an amorphous material, can induce a topological insulator from a trivial phase. However, to experimentally observe such a topological phase transition is very challenging due to the difficulty in controlling structural disorder in a quantum material. Given experimental realization of randomly positioned Rydberg atoms, such a system is naturally suited to studying structural disorder induced topological phase transitions and topological amorphous phases. Motivated by the development, we study topological phases in an experimentally accessible one-dimensional amorphous Rydberg atom chain with random atom configurations. In the single-particle level, we find symmetry-protected topological amorphous insulators and a structural disorder induced topological phase transition, indicating that Rydberg atoms provide an ideal platform to experimentally observe the phenomenon using state-of-the-art technologies. Furthermore, we predict the existence of a gapless symmetry-protected topological phase of interacting bosons in the experimentally accessible system. The resultant many-body topological amorphous phase is characterized by a Z_{2} invariant.

Vof-16 knockout improves the recovery from hypoxic-ischemic brain damage of neonatal rats.

Hypoxic-ischemic encephalopathy (HIE) results in high neonatal mortality and severe neurological impairments, and its underlying molecular mechanism underwent extensive investigations. Long non-coding RNA (lncRNA) is considered to be an important regulator on brain development and many neurological diseases. Currently, little is known about the role of Vof-16 (lncRNA) in HIE. We detected the relative expression level of Vof-16 in the cortex and hippocampus of hypoxic-ischemic (HI) models whose successful establishment was verified by TTC staining. Then, Vof-16 knockout rats were generated using the CRISPR/Cas engineering technology to search the specific function of the Vof-16 through a series of behavioral evaluations including Neurological severity scores (NSS), Y-maze test, Morris water maze (MWW) test, open field test, and Rotarod test. The results demonstrated the expression of Vof-16 was substantially up-regulated in the cortex and hippocampus of rats with HI injury. Importantly, Vof-16 knockout facilitated the recovery from long-term HI induced nerve damage and neurobehavioral dysfunctions. In conclusion, this study suggests Vof-16 knockout is a promising treatment target for neonatal HIE.

Topological Amorphous Metals.

We study amorphous systems with completely random sites and find that, through constructing and exploring a concrete model Hamiltonian, such a system can host an exotic phase of topological amorphous metal in three dimensions. In contrast to the traditional Weyl semimetals, topological amorphous metals break translational symmetry, and thus they cannot be characterized by the first Chern number defined based on the momentum space band structures. Instead, their topological properties will manifest in the Bott index and the Hall conductivity as well as the surface states. By studying the energy band and quantum transport properties, we find that topological amorphous metals exhibit a diffusive metal behavior. We further introduce a practical experimental proposal with electric circuits where the predicted phenomena can be observed using state-of-the-art technologies. Our results open the door to exploring topological gapless phenomena in amorphous systems.

Five new species of Eimeria Schneider, 1875 from the endangered Tibetan antelope Pantholops hodgsonii (Abel) (Artiodactyla: Bovidae: Caprinae) in the Hoh Xil Nature Reserve Area of Qinghai Province, China.

We examined faeces of 76 endangered Tibetan antelopes Pantholops hodgsonii (Abel) in May 2017, from the Hoh Xil Nature Reserve, Qinghai Province, China, and found 62/76 (82%) discharging oöcysts representing five new species of Eimeria Schneider, 1875. Oöcysts of Eimeria pantholopensis n. sp., found in 54/76 (71%) chiru, are subspheroidal/ellipsoidal, 15-22 × 12-19 (18.6 × 16.1) µm, with a length/width (L/W) ratio of 1.0-1.3 (1.2); micropyle cap and 1-3 polar granules are present, but oöcyst residuum is absent. Sporocysts are ovoidal, 7-11 × 4-6 (9.2 × 5.3) µm, with a L/W ratio of 1.6-2.0 (1.7); Stieda body and sporocyst residuum of small, scattered granules are present; each sporozoite contains 2 refractile bodies. Oöcysts of Eimeria wudaoliangensis n. sp. found in 52/76 (68%) chiru, are pyriform, 21-29 × 17-21 (24.9 × 19.0) µm, with a L/W ratio of 1.1-1.5 (1.3); micropyle, micropyle cap and 1-4 polar granules are present, but oöcyst residuum is absent. Sporocysts are ovoidal, 9-13 × 5-8 (11.7 × 6.7) µm, with a L/W ratio of 1.4-2.7 (1.7); Stieda body and sporocyst residuum of disbursed granules are present; sporozoites have a single large refractile body. Oöcysts of Eimeria hodgsonii n. sp. found in 20/76 (26%) chiru, are elongate-ellipsoidal, 25-32 × 18-21 (28.9 × 19.8) µm, with a L/W ratio of 1.2-1.7 (1.5); micropyle, micropyle cap and 1-3 polar granules are present, but oöcyst residuum is absent. Sporocysts are ovoidal, 11-14 × 6-7 (12.3 × 6.8) µm, with a L/W ratio of 1.7-2.1 (1.8); Stieda body and sporocyst residuum as group of large granules lying along the interface between intertwined sporozoites are present; sporozoites have 2 refractile bodies. Oöcysts of Eimeria schalleri n. sp. found in 49/76 (64.5%) chiru, are ellipsoidal, 26-36 × 19-25 (30.4 × 23.2) µm, with a L/W ratio of 1.2-1.5 (1.3); micropyle with micropyle cap and polar granules appearing as many diffuse tiny bodies are present, but oöcyst residuum is absent. Sporocysts are ovoidal, 12-16 × 7-9 (14.2 × 7.8) µm, with a L/W ratio of 1.6-2.1 (1.8); Stieda body and sporocyst residuum are present, the latter as a group of small dispersed granules between intertwined sporozoites; sporozoites with 2 refractile bodies. Oöcysts of Eimeria sui n. sp. found in 4/76 (5%) chiru, are ovoidal, 32-38 × 26-30 (36.6 × 28.6) µm, with a L/W ratio of 1.0-1.4 (1.3); micropyle and micropyle cap and 1-3 polar granules are present, but oöcyst residuum is absent. Sporocysts are ovoidal, 15-18 × 8-10 (16.7 × 8.9) µm, with a L/W ratio of 1.7-2.1 (1.9); Stieda body and sporocyst residuum are present, the latter as a group of dispersed small granules; sporozoites with 2 refractile bodies. Five of 62 faecal samples in which oöcysts were detected (8%) had a single species infection, 13 of 62 (21%) had two species, 28 of 62 (45%) had three species and 16 of 62 (26%) had four species.

[Effects of assisted-electroacupuncture on recovery of fast tracking anesthesia in mPCNL].

OBJECTIVE: To compare the effects on anesthesia recovery between assisted-electroacupuncture fast tracking anesthesia and simple fast tracking anesthesia in patients with minim ally invasive percutaneous nephrolithotomy (mPCNL). METHODS: Eighty cases of mPCNL were selected and randomly divided into a treatment group and a control group. Fentanyl (1-2 microg/kg), sevoflurane (8%) and rocuronium (0.5 mg/kg) were applied to perform anesthesia induction in both groups, and endotracheal inhalation of sevoflurane and intravenous pump injection of remifentanil were adopted to main anesthesia status during the operation. 20 min before anesthesia induction, bilateral Neiguan (PC 6), Neimadian, Hegu (LI 4), Yangxi (LI 5), Zhongji (CV 3), Qichong (ST 30), Zuwuli (LR 10) were selected and punctured in the treatment group, and elecctroacupuncture was given after arrival of qi until 30 min after the wake-up from anesthesia and withdrawal of endotracheal tube. The dosage for anesthesia maintenance, recovery time of awareness, extubation time, incidences of nausea, vomiting and chill and irritation of urethral catheters were observed and recorded. RESULTS: (1) The dosages of remifentanil and sevoflurane in the treatment group during the operation were obviously less than those in the control group [remifentanil: (5. 27 +/-1.23) micro g/kg h vs (7.35+/-1.70) micro g/kg . h; sevoflurane: (1.12+/-0.43) vol% vs (2.35+/-0.87) vol% , both P<0. 001]. (2) The recovery time of awareness and extubation time in the treatment group were significantly earlier than those in the control group [recovery time of awareness: (5.65 +/- 2.34) min vs (8. 87 +/- 6. 84) min, P<0. 01; extubation time : (7. 23+/-4. 35) min vs (10. 62+/-8. 16) min, P<0. 05]. (3) The incidences of nausea, vomiting and chill in the treatment group were significantly less than those in the control group (all P<0. 05). (4) The irritation of urethral catheters on urethra in the treatment group was significantly less than that in the control group (P<0. 001). CONCLUSION: The assisted-electroacupuncture anesthesia could reduce the dosage of remifentanil and sevoflurane in mPCNL fast tracking anesthesia in urinary surgery, reduce the incidences of nausea, vomiting, chill and irritation of urethral catheters during recovery stage, and prompt recovery of mPCNL patients.

Electroacupuncture induced spinal plasticity is linked to multiple gene expressions in dorsal root deafferented rats.

The underlying mechanism for electroacupuncture (EA) associated functional improvement in patients suffering from spinal cord injury (SCI) is largely unknown. Collateral sprouting is one plausible factor, where the cord microenvironment may contribute greatly. The present study evaluated the effects of EA on collateral sprouting from spared dorsal root ganglion (DRG), sensory functional restorations, and differential gene expressions in spinal cord after partial DRG removal in the rat. Following EA, N1 waveform latencies for cortical somatosensory evoked potential significantly shortened. The densities of terminal sprouting from the spared DRG significantly increased on the EA versus the non-EA side. Microarray analysis revealed that several genes were upregulated on the acupunctured side at different time points; they were ciliary neurotrophic factor (CNTF) at 1 day postoperation (dpo), fibroblast growth factor (FGF)-1, insulin-like growth factor (IGF) 1 receptor, neuropeptide Y, and FGF-13 at 7 dpo, and CNTF and calcitonin gene-related polypeptide-alpha at 14 dpo, respectively. Meanwhile, five genes (CNTF, p75-like apoptosis-inducing death domain protein, IGF-1, transforming growth factor-beta 2, and FGF-4) were downregulated at 7 dpo. Furthermore, reverse transcriptase polymerase chain reaction results supported the gene chip analysis. It was concluded that the EA induced sensory functional restorations following partial DRG ganglionectomies could be brought about by intraspinal sprouting from the spared DRG, as well as multiple differential gene expressions in the spinal cord. The results could have clinical application in EA treatment of patients after spinal injury.

[Bonding structure in silicon nitride thin films containing silicon nano-particles].

Non-stoichiometric hydrogenated amorphous silicon nitride (a-SiNx : H) film was deposited by helico-wave plasma-enhanced chemical vapour deposition (HWP-CVD) technique. The microstructure and bonding characteristics of both as-deposited and annealed thin films were studied. Raman scattering measurement shows that excess silicon exists in the form of amorphous silicon particles in the as-deposited sample. The microstructure of crystalline nano-particles silicon embedded in silicon nitride matrix in the post-annealed sample was formed. Comparing the results of both the Fourier transform infrared spectra and the optical absorption spectra of the samples deposited under different conditions, it is shown that the microstructure of the thin film depended on the gas flow ratio and annealing process. The sample with lower excess silicon shows a lower density of defect state at the silicon nanocrystal/SiNx interface due to a higher binding hydrogen content. The annealing process induces the decrease in Si-H and N--H binding densities. Because of the formation of silicon nanocrystals, the annealed samples exhibit a higher structure disorder degree.

[Study on hyperuricemia with hyperlipaemia, high blood sugar and hypertension in 1320 elderly people].

OBJECTIVE: To investigate the prevalence of hyperuricemia with hyperlipaemia, high blood sugar and hypertension among elderly people. METHODS: Serum uric acid (SUA), cholesterol, triglycerides, blood sugar and blood pressure were detected in 1320 elderly people and 6107 people at young and middle age. RESULTS: The mean SUAs in elderly male and female groups were significantly higher than that in young and middle aged male groups respectively (P < 0.05). The prevalence rates of hyperuricemia in elderly male and female groups were significantly higher than in young and middle aged male groups respectively (P < 0.05). The prevalence rates of hyperlipaemia, high blood sugar and hypertension in the elderly people of hyperuricemia were significantly higher than that in the elderly people of normal serum uric acid (P < 0.05). The prevalence rates of hyperuricemia in the elderly people were complicated by hyperlipaemia, high blood sugar and hypertension which was significantly higher than that in young and middle aged people of hyperuricemia (P < 0.05). CONCLUSION: Hyperuricemia is a common disease in elderly people and more attention should be paid to the closer relations among hyperuricemia with hyperlipaemia, high blood sugar and hypertension among the elderly.