Two-dimensional half-metals MSi2N4 (M = Al, Ga, In, Tl) with intrinsic p-type ferromagnetism and ultrawide bandgaps

Intrinsic half-metallic nanomaterials with 100% spin polarization are highly demanded for next-generation spintronic devices. Here, by using first-principles calculations, we have designed a class of new two-dimensional (2D) p-type half-metals, MSi2N4 (M = Al, Ga, In and Tl), which show high mechanical, thermal and dynamic stabilities. MSi2N4 not only have ultrawide electronic bandgaps for spin-up channels in the range of 4.05 to 6.82 eV but also have large half-metallic gaps in the range of 0.75 to 1.47 eV, which are large enough to prevent the spin-flip transition. The calculated magnetic moment is 1 μB per cell, resulting from polarized N1-px/py orbitals. Moreover, MSi2N4 possess robust long-range ferromagnetic orderings with Curie temperatures in the range of 35-140 K, originating from the interplay of N1-M-N1 superexchange interactions. Furthermore, spin dependent electronic transport calculations reveal 100% spin polarization. Our results highlight new promising 2D ferromagnetic half-metals toward future spintronic applications.

Investigation of nonlinear optical properties in α-A2BB'O6 (A = Li, Na, K; B = Ti, Zr, Hf; B' = Se, Te) by first-principles calculations

Nonlinear optical (NLO) crystals based on oxides typically have wide bandgaps and large laser damage thresholds (LDTs), which are important for generating high-power and continuous terahertz radiation. Recently, a new family of NLO materials α-A2BB'O6 including Li2TiTeO6 (LTTO) with a strong second harmonic generation (SHG) efficiency of 26 × KH2PO4 (KDP) and a large LDT of 550 MW cm-2 were reported. Herein, we systematically study the electronic structures and NLO properties of α-A2BB'O6 (A = Li, Na, K; B = Ti, Zr, Hf; B' = Se, Te) to explore the relationship between the structure and SHG coefficient. First, 15 members of the A2BB'O6 family are demonstrated to be highly stable and NLO materials, excluding K2TiTeO6, K2TiSeO6 and K2ZrSeO6. Then, the electronic band structure, dipole moment and distortion of BO6/B'O6 octahedrons, SHG coefficient and terahertz absorption spectrum are calculated comprehensively with the element variation of A-site, B-site and B'-site. Finally, the magnitude of the SHG coefficient is found to be directly proportional to the value of total dipole moment and distortion, and inversely proportional to the bandgap value. Most importantly, among the A2BB'O6 materials, K2HfSeO6 shows the smallest direct bandgap of 2.99 eV, the largest SHG coefficient d33 of about 5 × LTTO and low terahertz absorbance from 0.1 to 9 THz. Our results provide new NLO crystals that may have potential application in terahertz radiation sources and other nonlinear electronics.

Exploration of the origin of the excellent charge-carrier dynamics in Ruddlesden-Popper oxysulfide perovskite Y2Ti2O5S2

Although the efficient separation of electron-hole (e-h) pairs is one of the most sought-after electronic characteristics of materials, due to thermally induced atomic motion and other factors, they do not remain separated during the carrier transport process, potentially leading to rapid carrier recombination. Here, we utilized real-time time-dependent density functional theory in combination with nonadiabatic molecular dynamics (NAMD) to explore the separated dynamic transport path within Ruddlesden-Popper oxysulfide perovskite Y2Ti2O5S2 caused by the dielectric layer and phonon frequency difference. The underlying origin of the efficient overall water splitting in Y2Ti2O5S2 is systematically explored. We report the existence of the bi-directional e-h separate-path transport, in which, the electrons transport in the Ti2O5 layer and the holes diffuse in the rock-salt layer. This is in contrast to the conventional e-h separated distribution with a crowded transport channel, as observed in SrTiO3 and hybrid perovskites. Such a unique feature finally results in a long carrier lifetime of 321 ns, larger than that in the SrTiO3 perovskite (160 ns) with only one carrier transport channel. This work provides insights into the carrier transport in lead-free perovskites and yields a novel design strategy for next-generation functionalized optoelectronic devices.

Theoretical Dissection of Cation-Deficient Layered Ruddlesden-Popper Oxysulfide Perovskites with a High-Efficiency Carrier Transport Channel

The search for lead-free perovskite materials has triggered intensive interest. Here, we study the electronic structures and optical properties of cation-deficient Ruddlesden-Popper oxysulfide perovskites Ln2Ti2O5S2 (Ln = Sc, Y, or La), with a tunable band gap of 1.45-2.1 eV and a small exciton binding energy of ∼0.1 eV, among which Y2Ti2O5S2 has been synthesized experimentally. Sc2Ti2O5S2 possesses the largest light absorbance in the visible region. We further rationalize the light absorption via the transition dipole moment and suggest potential applications of Sc2Ti2O5S2 in solar cells and Y2Ti2O5S2 and La2Ti2O5S2 in water splitting. In addition, this family exhibits small effective masses within the x-y plane and large ones along the z direction. Most importantly, electron gas-like carrier behaviors are observed within the Ti-O bond region, offering a diffusion channel for electron transport. These findings greatly advance our understanding of lead-free perovskites and offer a novel material platform for future optoelectronic devices.

Understanding Trends in Electrochemical Methanol Oxidation Reaction Activity on a Single Transition-Metal Atom Embedded in N-Coordinated Graphene Catalysts

The lack of efficient catalysts and research on the mechanism for the methanol oxidation reaction (MOR) impedes the development of direct methanol fuel cells. In this work, based on density functional theory calculations, we systematically investigated the activity trends of electrochemical MOR on a single transition-metal atom embedded in N-coordinated graphene (M@N₄C). By calculating the free energy diagrams of MOR on M@N₄C, Co@N₄C was screened out to be the most effective MOR catalyst with a low limiting potential of 0.41 V due to the unique charge transfers and electronic structures. Importantly, one- and two-dimensional volcano relationships in MOR on M@N₄C catalysts are established based on the d-band center and the Gibbs free energy of ΔG*CH3OH and ΔG_*CO, respectively. In one word, this work provides theoretical guides toward the improved activity of MOR on M@N₄C and hints for the design of active and efficient MOR electrocatalysts.

[Clinical effects of island posterior femoral composite tissue flaps in the repair of sinus cavity pressure ulcers in the areas of ischial tuberosity and greater trochanter]

Objective: To explore the clinical effects of island posterior femoral composite tissue flaps in the repair of sinus cavity pressure ulcers in the areas of ischial tuberosity and greater trochanter. Methods: The retrospective observational study was conducted. From December 2018 to December 2021, 23 patients with sinus cavity pressure ulcers in the areas of ischial tuberosity and greater trochanter who met the inclusion criteria were admitted to Ganzhou People's Hospital, including 16 males and 7 females, aged 45 to 86 years. The size of pressure ulcers in ischial tuberosity ranged from 1.5 cm×1.0 cm to 8.0 cm×5.0 cm, and the size of pressure ulcers in greater trochanter ranged from 4.0 cm×3.0 cm to 20.0 cm×10.0 cm before debridement. After treatment of underlying diseases, debridement and vacuum sealing drainage for 5 to 14 days were performed. All the wounds were repaired by island posterior femoral composite tissue flaps, with area of 4.5 cm×3.0 cm-24.0 cm×12.0 cm, pedicle width of 3-5 cm, pedicle length of 5-8 cm, and rotation radius of 30-40 cm. Most of the donor site wounds were sutured directly, and only 4 donor site wounds were repaired by intermediate thickness skin graft from the contralateral thigh. The survival of composite tissue flaps, wound healing of the donor and recipient sites and the complications were observed. The recurrence of pressure ulcers, and the appearance and texture of flaps were observed during follow-up. Results: A total of 32 wounds in 23 patients were repaired by island posterior femoral composite tissue flaps (including 3 fascio subcutaneous flaps, 24 fascial flaps+fascio subcutaneous flaps, 2 fascial flaps+fascial dermal flaps, 2 fascial flaps+fascio subcutaneous flaps+femoral biceps flaps, and one fascial flap+fascio subcutaneous flap+gracilis muscle flap). Among them, 31 composite tissue flaps survived well, and a small portion of necrosis occurred in one fascial flap+fascio subcutaneous flap post surgery. The survival rate of composite tissue flap post surgery was 96.9% (31/32). Twenty-nine wounds in the recipient sites were healed, and 2 wounds were torn at the flap pedicle due to improper postural changes, and healed one week after bedside debridement. One wound was partially necrotic due to the flap bruising, and healed 10 days after re-debridement. Thirty-one wounds in the donor sites (including 4 skin graft areas) were healed, and one wound in the donor site was torn due to improper handling at discharge, and healed 15 days after re-debridement and suture. The complication rate was 12.5% (4/32), mainly the incision dehiscence of the flap pedicle and the donor sites (3 wounds), followed by venous congestion at the distal end of flap (one wound). During the follow-up of 3 to 24 months, the pressure ulcers did not recur and the flaps had good appearance and soft texture. Conclusions: The island posterior femoral composite tissue flaps has good blood circulation, large rotation radius, and sufficient tissue volume. It has a high survival rate, good wound healing, low skin grafting rate in the donor site, few postoperative complications, and good long-term effect in the repair of sinus cavity pressure ulcers in the areas of ischial tuberosity and greater trochanter.

Layer-stacking of chalcogenide-terminated MXenes Ti2CT2(T = O, S, Se, Te) and their applications in metal-ion batteries

Owning to limited supply of lithium for Li-ion batteries, the development of non-Li-ion batteries (such as Na⁺, K⁺Mg²⁺, Ca²⁺, and Al³⁺ion batteries) has attracted significant research interest. In this work, by means of the first-principles calculations, we systematically investigated the performance of chalcogenide-terminated MXenes Ti₂CT₂(T = O, S, Se, and Te) as electrodes for Li-ion and non-Li-ion batteries, as well as the layer-stacking and electronic properties of Ti₂CT₂. We find that the stacking type of O and Te terminated Ti₂C multilayers with AA stacking differs from that of S and Se terminated Ti₂C multilayers with AB stacking. More importantly, Ti₂CO₂monolayer can be potential anode material for Na- and K-ion batteries with high capacities and very low diffusion barriers (0.03-0.11 eV), while Ti₂CS₂and Ti₂CSe₂are promising anode materials with relatively low average open circuit voltages (OCVs) for Na-, K-, and Ca-ion batteries (0.4-0.87 V). Among these materials, Ti₂CS₂exhibits the largest ion capacity of 616 mAh g^-1. These results of our work may inspire further studies of Ti₂C-MXenes multilayers as electrodes for metal-ion batteries either experimentally or theoretically.

Tuning low-temperature CO oxidation activities via N-doping on graphene-supported three-coordinated nickle single-atom catalysts

Nitrogen doping is identified as an intriguing way to regulate graphene-supported single-atom catalysts (SACs) for heterogeneous catalysis. However, little theoretical effort has been directed towards exploring the activity trend in terms of N-doping level. In this study, we systematically investigated the N-doping effect on CO oxidation activities for graphene-supported three-coordinated Ni SACs (Ni-N_xC_3-x) in virtue of density functional theory (DFT) calculations and microkinetic modeling. We found that N-doping will shift the d-band center of single-atom Ni upwards, enhance the adsorption of intermediates, and tune the activation barrier to the overall reaction activities. Ni-N₁C₂ exhibits excellent catalytic performance with the highest total reaction rate comparable to that of noble metal SACs. These findings are helpful for understanding the N-doping influence and rationalizing the art of designing novel SACs for CO oxidation at low temperatures.

[Study on the pharmacodynamic activity of combinations with the new anti-tuberculosis drug pyrifazimine in vitro and in vivo in mouse]

Objective: To evaluate two-drug combination interaction between pyrifazimine(TBI-166) and anti-drug-resistant tuberculosis group A drugs Bedaquiline (BDQ), Moxifloxacin (MFX) and the new anti-tuberculosis drug Delamanid (DLM), SQ109, Q203, and PBTZ169 in vitro and in vivo in mouse, so as to provide basis for TBI-166 combination therapy. Methods: This study was performed from September 2020 to July 2021. The chessboard method was used to evaluate the interaction between TBI-166 and BDQ, MFX, DLM, SQ109, and PBTZ169. The time-killing kinetics method was used to evaluate the anti-tuberculosis activity of the two-drug combination with partial synergy. The BALB/c mouse acute infection model was used to evaluate the anti-tuberculosis activity at 4 and 8 weeks in the two-drug combination group (TBI-166+BDQ, TBI-166+SQ109, TBI-166+PBTZ169, TBI-166+Q203) and monotherapy groups (TBI-166, BDQ, SQ109, PBTZ169, Q203). Data analysis was performed using an independent sample t-test. Results: After TBI-166 combined with anti-tuberculosis drugs, MIC was reduced to 6.25% to 25.00% of TBI-166 monotherapy. After TBI-166 combined with BDQ, SQ109 and PBTZ169, the partial inhibitory concentration index (FICI) values were 0.53, 0.75 and 0.75, respectively; the time sterilization experiment showed that the viable population of Mycobacterium tuberculosis treated with two-drug combination of TBI-166 and BDQ, SQ109, PBTZ169 for 14 days decreased at least 3 log₁₀ CFU/ml. In the mouse experiments, it was found that, the amount of viable bacteria in lung tissue of BDQ, SQ109 and PBTZ169 combined with TBI-166 groups was lower than that of the monotherapy group,respectively. The lung tissue culture of mice in the TBI-166+BDQ group was negative after 4 weeks of treatment, and the number of live bacteria in the lungs of the TBI-166+BDQ group was 1.49 log₁₀CFU lower than that of the BDQ monotherapy group(P<0.01). Conclusion: In vitro and in vivo experiments in mice revealed that TBI-166 had synergistic anti-tuberculosis activity after being combined with BDQ, SQ109 and PBTZ169, respectively.

[Utility of GPR68 and TIL in TPF-induced chemotherapy and prognosis evaluation in middle-advanced hypopharyngeal squamous cell carcinoma]

Objective: To evaluate the roles of G Protein-Coupled Receptor 68 (GPR68) and tumor infiltrating lymphocytes (TIL) in TPF-(paclitaxel, cisplatin and 5-fluorouracil) induced chemotherapy for middle-advanced hypopharyngeal squamous cell carcinomas. Methods: A total of 31 patients with middle-advanced hypopharyngeal squamous cell carcinoma before TPF-inducted chemotherapy were enrolled from September 2012 to November 2017 in Beijing Tongren Hospital, Capital Medical University, including 28 males and 3 females, aged 43 to 71 years old. The expression of GPR68 and tumor infiltrating CD4⁺and CD8⁺T cells before chemotherapy was detected by immunohistochemical staining, and the relationships between GPR68 expression and clinical features, chemotherapy efficacy and overall survival (OS) were analyzed using t-test. Results: After 3 cycles of chemotherapy, there were 4, 14, 10 and 3 patients respectively with complete response (CR), partial response (PR), stable disease (SD) and progressive disease (PD). The positive rates of GPR68 and CD8 were 25% and 40% respectively in the effective group (CR+PR), while 50% and 15% in the ineffective group (SD+PD), with statistically significant differences between two groups (t=5.17 and 12.86,P<0.001). Linear regression analysis showed that GPR68 was negatively correlated with CD8⁺T cells (r=-0.64,P<0.001). There was no significant correlation between the CD4 expression and TPF efficacy (P>0.05). The mean OS was 12.5 months in patients with high-expressed GPR68 and 25.0 months in patients with low-expressed GPR68, with a statistically significant difference (P=0.005). And mean OS was 25.0 months in patients with high-expressed CD8 and 14.5 months in low-expressed CD8, with a statistically significant difference (HR=2.58, P=0.019). Cox regression analysis showed that GPR68 and CD8⁺T cells were significant prognostic factors (OR(95%CI)=3.27(2.46-5.97) and 1.53(0.78-1.82), all P<0.05), while CD4 had no significant effect on prognosis (P>0.05). Conclusion: GPR68 and CD8⁺T cells are expected to be biomarkers for evaluating the efficacy and prognosis of TPF-induced chemotherapy in patients with middle-advanced hypopharyngeal squamous cell carcinoma.

Chimeric ferritin H in hybrid crucian carp exhibits a similar down-regulation in lipopolysaccharide-induced NF-κB inflammatory signal in comparison with Carassius cuvieri and Carassius auratus red var

Ferritin H can participate in the regulation of teleostean immunity. ORF sequences of RCC/WCC/WR-ferritin H were 609 bp, while WR-ferritin H gene possessed chimeric fragments or offspring-specific mutations. In order to elucidate regulation of immune-related signal transduction, three fibroblast-like cell lines derived from caudal fin of red crucian carp (RCC), white crucian carp (WCC) and their hybrid offspring (WR) were characterized and designated as RCCFCs, WCCFCs and WRFCs. A sharp increase of ferritin H mRNA was observed in RCCFCs, WCCFCs and WRFCs following lipopolysaccharide (LPS) challenge. Overexpression of RCC/WCC/WR-ferritin H can decrease MyD88-IRAK4 signal and antagonize NF-κB, TNFα promoter activity in RCCFCs, WCCFCs and WRFCs, respectively. These results indicated that ferritin H in hybrid offspring harbors highly-conserved domains with a close sequence similarity to those of its parents, playing a regulatory role in inflammatory signals.

Many-body effects in an MXene Ti2CO2 monolayer modified by tensile strain: GW-BSE calculations

MXenes, two-dimensional (2D) layered transition metal carbide/nitride materials with a lot of advantages including high carrier mobility, tunable band gap, favorable mechanical properties and excellent structural stability, have attracted research interest worldwide. It is imperative to accurately understand their electronic and optical properties. Here, the electronic and optical response properties of a Ti₂CO₂ monolayer, a typical member of MXenes, are investigated on the basis of first-principles calculations including many-body effects. Our results show that the pristine Ti₂CO₂ monolayer displays an indirect quasi-particle (QP) band gap of 1.32 eV with the conduction band minimum (CBM) located at the M point and valence band maximum (VBM) located at the Γ point. The optical band gap and binding energy of the first bright exciton are calculated to be 1.26 eV and 0.56 eV, respectively. Under biaxial tensile strains, the lowest unoccupied band at the Γ point shifts downward, while the lowest unoccupied band at the M point shifts upward. Then, a direct band gap appears at the Γ point in 6%-strained Ti₂CO₂. Moreover, the optical band gap and binding energy of the first bright exciton decrease continuously with the increase of the strain due to the increase of the lattice parameter and the expansion of the exciton wave function. More importantly, the absorbed photon flux of Ti₂CO₂ is calculated to be 1.76-1.67 mA cm^-2 with the variation of the strain, suggesting good sunlight optical absorbance. Our work demonstrates that Ti₂CO₂, as well as other MXenes, hold untapped potential for photo-detection and photovoltaic applications.

Electronic properties and oxygen reduction reaction catalytic activity of h-BeN2 and MgN2 by first-principles calculations

Currently, identifying suitable oxygen reduction reaction (ORR) catalysts in novel two-dimensional (2D) materials has attracted more and more research attention. Here, we have studied the catalytic activities of 2D h-BeN₂ and MgN₂ monolayers for ORR by using first-principles calculations. The calculated results reveal that the direct quasiparticle bandgap of BeN₂ monolayer is 3.32 eV, and the indirect bandgap of MgN₂ is 3.42 eV. 2D h-BeN₂ and MgN₂ exhibit high exciton binding energies of 1.07 and 0.83 eV respectively, and their optical properties are determined by bound exciton transitions due to the strong quantum confinement effects. Importantly, h-BeN₂ and MgN₂ monolayers with positive-charged (+1.6 e) metal atom (Be/Mg) on the surface exhibit excellent adsorption ability for O₂ and ORR intermediates, and show better CO tolerance than Pt(111). The calculated free energy plots are always downhill for ORR catalyzed by BeN₂ in both acid and alkaline environments, and by MgN₂ in alkaline environments. The detailed reaction mechanism analyses show that high-efficient four-electron pathway is the optimal pathway for ORR catalyzed by BeN₂ in acid environments. Surprisingly, there is a low overpotential of 0.45 eV for ORR catalyzed by BeN₂ in the acid solution and no overpotential in the alkaline solution. Our studies found for the first time that 2D h-BeN₂ shows huge potential as a non-precious metal ORR catalyst in acid and alkaline environments.

[Comparison of endoscopic features between colorectal sessile serrated adenoma/polyp with or without cytologic dysplasia and hyperplastic polyp]

Objective: To investigate the morphological features of colorectal sessile serrated adenoma/polyp (SSA/P) and hyperplastic polyp (HP) by white light endoscope (WLE) and Image enhancement endoscope (IEE) . Methods: The data of 7 384 patients who underwent colonoscopy at the Center of Digestive Endoscopy, Peking University International Hospital from August 1, 2016 to February 29, 2018 were analyzed retrospectively. WLE and IEE[Fuji intelligent chromo endoscopy (FICE) or Blue Laser Imaging (BLI) ]were used to compare the morphological features of SSA/P with HP, SSA/P-CD(+)with SSA/P-CD(-). The diagnostic values of endoscopic features in SSA/P and SSA/P-CD(+)were analyzed. Results: A total of 3 401 polyps were detected in 7 384 patients, including 164 SSA/Ps (135 patients). During the same period, there were 270 HPs (223 patients) in accordance with the admission criteria. Compared with HP group, SSA/P group was more common in the right colon with a diameter>5 mm and more likely to be manifested as: Ⅱ-O pit pattern, surface mucus, cumulus-like surface, irregular morphology, VMV, redness, and also more likely to be associated with colon adenoma, colon cancer elsewhere in the colorectum. The differences were statistically significant (P<0.01). Compared with SSA/P-CD(-)group, SSA/P-CD(+)group was more common in the right colon with a diameter>5 mm and more likely to be manifested as: Ⅱ-O pit pattern, surface mucus, cumulus-like surface, irregular morphology, VMV. The differences were statistically significant (P<0.001). The differential diagnosis between SSA/P and HP was predicted by combining any two endoscopic morphological features (right colon, Ⅱ-O pit pattern, surface mucus, cumulus surface, irregular morphology, VMV, diameter>5 mm, at least 2 of 7 endoscopic features). The sensitivity, specificity, accuracy, positive likelihood ratio and negative likelihood ratio were 59.15%, 95.56%, 81.80%, 13.32 and 0.43, respectively. Similarly, the differential diagnosis between SSA/P-CD(+) and HP was predicted. The sensitivity, specificity, accuracy, positive likelihood ratio and negative likelihood ratio were 92.16%, 95.56%, 95.02%, 20.76 and 0.08, respectively. Conclusion: Comprehensive analysis of the WLE and FICE/BLI morphological features of the lesions can effectively distinguish SSA/P from HP, especially SSA/P-CD(+) from HP.

Enhancement of photoluminescence and hole mobility in 1- to 5-layer InSe due to the top valence-band inversion: strain effect

Recently, two-dimensional (2D) few-layer InSe nanosheets have become one of the most interesting materials due to their excellent electron transport, wide bandgap tunability and good metal contact. However, their low photoluminescence (PL) efficiency and hole mobility seriously restrict their application in 2D InSe-based nano-devices. Here, by exerting a suitable compressive strain, a remarkable modification for the electronic structure and the optical and transport properties of 1- to 5-layer InSe has been confirmed by powerful GW-BSE calculations. Both top valence band inversion and indirect-to-direct bandgap transition are induced; the light polarization is reversed from E||c to E⊥c; and the PL intensity and hole mobility are enhanced greatly. Surprisingly, under 6% compressive strain, the light emission of monolayer InSe with E⊥c is allowed at 2.58 eV, which has never been observed previously. Meanwhile, for the 2D few-layer InSe, the PL with E⊥c polarization increases over 10 times in intensity and has a blue-shift at about 0.6-0.7 eV, and the hole mobility increases two orders of magnitude up to 103 cm2 V-1 s-1, as high as electron mobility. The strained few-layer InSe are thus a promising candidate for future 2D electronic and optoelectronic nano-devices.

Modulation of electronic and magnetic properties in InSe nanoribbons: edge effect

Quite recently, the two-dimensional (2D) InSe nanosheet has become a hot material with great promise for advanced functional nano-devices. In this work, for the first time, we perform first-principles calculations on the structural, electronic, magnetic and transport properties of 1D InSe nanoribbons with/without hydrogen or halogen saturation. We find that armchair ribbons, with various edges and distortions, are all nonmagnetic semiconductors, with a direct bandgap of 1.3 (1.4) eV for bare (H-saturated) ribbons, and have the same high electron mobility of about 10³ cm²V^-1s^-1 as the 2D InSe nanosheet. Zigzag InSe nanoribbons exhibit metallic behavior and diverse intrinsic ferromagnetic properties, with the magnetic moment of 0.5-0.7 μ _B per unit cell, especially for their single-edge spin polarization. The edge spin orientation, mainly dominated by the unpaired electrons of the edge atoms, depends sensitively on the edge chirality. Hydrogen or halogen saturation can effectively recover the structural distortion, and modulate the electronic and magnetic properties. The binding energy calculations show that the stability of InSe nanoribbons is analogous to that of graphene and better than in 2D InSe nanosheets. These InSe nanoribbons, with novel electronic and magnetic properties, are thus very promising for use in electronic, spintronic and magnetoresistive nano-devices.

Enhancement of hole mobility in InSe monolayer via an InSe and black phosphorus heterostructure

To enhance the low hole mobility (∼40 cm² V^-1 s^-1) of InSe monolayer, a novel two-dimensional (2D) van der Waals heterostructure made of InSe and black phosphorus (BP) monolayers with high hole mobility (∼10³ cm² V^-1 s^-1) has been constructed and its structural and electronic properties are investigated using first-principles calculations. We find that the InSe/BP heterostructure exhibits a direct band gap of 1.39 eV and type-II band alignment with electrons (holes) located in the InSe (BP) layer. The band offsets of InSe and BP are 0.78 eV for the conduction band minimum and 0.86 eV for the valence band maximum, respectively. Surprisingly, the hole mobility in the InSe/BP heterostructure exceeds 10⁴ cm² V^-1 s^-1, which is one order of magnitude larger than the hole mobility of BP and three orders larger than that of the InSe monolayer. The electron mobility is also increased to 3 × 10³ cm² V^-1 s^-1. The physical reason has been analyzed deeply, and a universal method is proposed to improve the carrier mobility of 2D materials by forming heterostructures with them and other 2D materials with complementary properties. The InSe/BP heterostructure can thus be widely used in nanoscale InSe-based field-effect transistors, photodetectors and photovoltaic devices due to its type-II band alignment and high carrier mobility.

Anomalous Light Emission and Wide Photoluminescence Spectra in Graphene Quantum Dot: Quantum Confinement from Edge Microstructure

The physical origin of the observed anomalous photoluminescence (PL) behavior, that is, the large-size graphene quantum dots (GQDs) exhibiting higher PL energy than the small ones and the broadening PL spectra from deep ultraviolet to near-infrared, has been debated for many years. Obviously, it is in conflict with the well-accepted quantum confinement. Here we shed new light on these two notable debates by state-of-the-art first-principles calculations based on many-body perturbation theory. We find that quantum confinement is significant in GQDs with remarkable size-dependent exciton absorption/emission. The edge environment from alkaline to acidic conditions causes a blue shift of the PL peak. Furthermore, carbon vacancies are inclined to assemble at the GQD edge and form the tiny edge microstructures. The bound excitons, localized inside these edge microstructures, determine the anomalous PL behavior (blue and UV emission) of large-size GQDs. The bound excitons confined in the whole GQD lead to the low-energy transition.

Tetradecyl 2,3-dihydroxybenzoate promotes functional recovery after spinal cord injury in adult rats

Tetradecyl 2,3-dihydroxybenzoate (ABG001) is a small molecule separated from gentian extract that has a similar effect to nerve growth factor. It is not clear whether it can promote functional recovery in animals suffering from a central nervous system injury. In order to explore the role of ABG001 in restoration of tissue structure and motor function of rats with spinal cord injury (SCI), ABG001 (0.4 mg/kg) was administered intraperitoneally. Subsequently, behavioral assessments and morphological studies were performed to detect recovery of hind limb motor function and neuroregeneration. The results showed that compared with DMSO group, the rats in the ABG treatment group had better performance in BBB score and grip strength test (P < 0.05), the area of necrosis was smaller (P < 0.05), GFAP expression was significantly reduced (P < 0.01), and Map-2 expression was significantly increased (P < 0.01). Additionally, after ABG treatment, the number of fluorogold positive cells transported reversely to red nucleus increased (P < 0.05). The results suggest that ABG001 can promote recovery of hind limb motor function in rats with SCI, which may be related to its functions of inhibiting glial cell proliferation and promoting neuroregeneration.

[The analysis and discussion of clinical features and treatment of tumor like Sjögren's syndrome in 46 cases]

OBJECTIVE

Manifestations and treatment of tumor-like Sjögren's syndrome(SS) is varying, it is difficulty to differentiate it from other diseases. The purpose of this paper was to identify the peculiarity of the manifestations and treatment of tumor like SS.

METHODS

The data of 46 cases suffering from tumor like SS had been analyzed retrospectively and discussed with published articles about its clinical features and treatment.

RESULTS

There were one or more than one masses in salivary gland, general manifestations were found in 46 cases, dry mouth 41%,dry eye 23%, autoantibody 17%. The result of treatment showed recurrence site of operation group was out of primary region, recurrence rate was 20%. Effective rate of drug group was about 81%,however, recurrence rate was up to 38%. Malignant change occurred in three cases.

CONCLUSION

The local feature of tumor like SS is mass in salivary gland, general manifestations are accompanied in some patients. It presents chronic benign process, malignant change may occur in a few patients. Combined therapy should be taken reasonably, local with general, drug with operation. The diagnosis should be identified before treatment, drug therapy is used at first, and operation is adopted after failure of drug treatment.

Effect of dopamine depletion on DARPP-32 protein in ischemic rat striatum

AIM

To study the effects of dopamine depletion on the phosphorylation level, intracellular distribution, and mRNA expression of DARPP-32 in the ischemic striatum and to elucidate the mechanisms underlying the ischemic injury.

METHODS

A complex model of SN lesioning with 6-OHDA to deplete dopamine and four vessels occlusion for inducing forebrain ischemia was constructed in rats. DARPP-32 was investigated with autoradiogram, immunohistochemistry and in situ hybridization.

RESULTS

The [32P]phosphate incorporation of DARPP-32 was reduced in vitro following ischemia. However, the [32P]phosphate incorporation, the numbers of positive neurons, and mRNA expression of DARPP-32 were increased in SN lesioning plus ischemic rats with denervated striatum.

CONCLUSION

Dopamine depletion reduced the DARPP-32 phosphorylation in vivo following ischemia, and protected DARPP-32 immunoreactivity and mRNA expression level against the reduction induced by ischemia.

Relevance between striatal expression of Fos, proenkephalin mRNA, prodynorphin mRNA and rotation induced by l-stepholidine in 6-hydroxydopamine-lesioned rats

AIM

To study that l-stepholidine (SPD) regulates the expression of proenkephalin (PENK) and prodynorphin (PDYN) mRNA and Fos in the striatum after rotational test in the 6-hydroxydopamine (6-OHDA)-lesioned rats.

METHODS

PENK and PDYN mRNA levels were examined with in situ hybridization, and Fos expression was detected with immunocytochemistry. The data were semi-quantified with image analyzer.

RESULTS

(1) Following repeated SPD treatment, the rotation was kept on high activity in the 6-OHDA-lesioned rats. (2) SPD significantly elicited Fos expression in both sides of striatum, particularly in the denervated one. Repeated administration of SPD, Fos expression declined on both sides, particularly in the intact one. (3) In the denervated striatum of 6-OHDA-lesioned rats, the PENK mRNA level was extremely increased vs that in the intact striatum. This high level of PENK mRNA was significantly reduced by 7-d treatments of SPD. SPD also reduced the level of PENK mRNA in the intact striatum. However, the level of PDYN mRNA did not show significant change in both sides of striatum after denervation or SPD treatment.

CONCLUSION

In the 6-OHDA-lesioned rats, the rotation induced by SPD was kept on a high activity, which was in pace with the inducement of Fos expression and the reduction of expression of PENK mRNA in the denervated striatum. But then the lesion and SPD treatment had no remarkable effect on the expression of PDYN mRNA.

Dopamine-glutamate interaction in rat striatal slices: changes of CCDPK II, PKA, and LDH activity by receptor-mediated mechanisms

AIM

To study the effects of dopamine (DA) and glutamate (Glu) and their receptor agonists/antagonists on Ca2+/calmodulin-dependent protein kinase II (CCDPK II), cyclic AMP-dependent protein kinase A (PKA) activities and the LDH release in rat striatal slices, and to examine the interaction between DA and Glu transmitter systems in striatum.

METHODS

The activities of CCDPK II, PKA, and the release of LDH were determined with the 32P-incorporation and colorimetry respectively in rat striatal slices.

RESULTS

(1) Exogenous DA, D1 receptor agonist SKF 38393 and D2 receptor agonist LY 171555 reduced CCDPK II activity in striatal slices; Glu also inhibited CCPPK II activity in a concentration-dependent manner. NMDA receptor antagonist MK-801 could antagonize the inhibitory effect of SKF 38393 and LY 171555 on the CCDPK II activity. D1 and D2 receptor antagonists SCH 23390 and spiperone could also antagonize the decrease of CCDPK II activity induced by Glu; (2) DA and SKF 38393 markedly increased PKA activity in striatal slices, which was reduced by MK-801; (3) DA and Glu increased the release of LDH from the striatal neurons in a concentration-dependent manner. MK-801 antagonized the increase of LDH induced by DA. Spiperone, rather than SCH 23390, could reduce the release of LDH from striatal neuron in the presence of Glu.

CONCLUSION

The interaction between DA and Glu transmitter systems is found in the regulation of the CCDPK II and PKA activities and cell function in the striatum.

Antagonistic effect of l-stepholidine on striatal ischemic injury in rat

AIM

To elucidate the protection of l-stepholidine (SPD) on neuronal morphology and function against the striatal ischemic injury in rat.

METHODS

The forebrain ishemia to Sprague Dawley rats was induced with four-vessel occlusion. Histological examination was performed on the dorsolateral striatum with cresylviolet stain. In striatal slices of rat as an in vitro ischemic model, the activity of calcium/calmodulin-dependent protein kinase II (CCDPK) and lactate dehydrogenase (LDH) was examined by the method of 32P-incorporation and colorimetry, respectively.

RESULTS

In the SPD-treated groups, most of the neurons in the striatum kept the normal morphological appearance after 30-min ischemia followed by 6-h or 12-h reperfusion. The number of neurons was much more in SPD groups than that in vehicle group. The sparse and abnormal neurons were observed in the vehicle group. SPD attenuated the ischemic effect on the CCDPK activity in striatal slices. In addition, SPD inhibited the leakage of LDH from neurons induced by ischemia in incubated striatal slices.

CONCLUSION

SPD protected striatal neurons against ischemic injury and antagonized the inhibitory action on CCDPK activity induced by ischemia. SPD reduced the leakage of LDH from striatal neurons induced by ischemia.

[Primary research of development of a mouse model for non-bacterial sialoadenitis]

OBJECTIVE: To develope a mouse model for non-bacterial sialoadenitis similar to SS.The model of organ-specific to the submandibular gland of mouse has developed for this study. METHODS: Several of the mouse strains were used to the development of non-bacterial sialoadenitis.The injection of syngeneic salivary gland tissue with CFA induced inflammation in submandibular gland in mice.Not all mice had a predictable response. RESULTS: C(57) mice (500microg/ml and 750microg/ml group )appear histologically to be more prove to develop sialoadenitis. CONCLUSION: An animal model of non-bacterial sialoadenitis had been set up,the non-bacterial sialoadentitis may be similar to the autoimmune process in human SS.

[Experimental research on animal model and treatment of Sjogren's syndrome by traditional chinese medicine (TCM)]

OBJECTIVE:To confirm the function of SS Syrup used in our department. METHODS: Under the basis of TCM and differentiation symptoms of SS,the animal model was established and applied to test the function of SS syrup.There are three indices to be observed,weight change,volume of drinking water daily,cAMP change. RESULTS: The three observed indices of dificiency symptom model had been rectified by SS syrup. CONCLUSION: SS syrup has two main functions:(1)reinforcing of the spleen and tonifying qi;(2)nourishing liver-yin and kidney-yin as well as removing pathogentic heat and fire.

[Detection of clinical diagnosis and different symptoms of Sjogren's syndrome by traditional chinese medicine (TCM)]

OBJECTIVE:To search for the appropriate diagnostic criteria of SS and confirm the differentiation of SS.METHODS:The European di agnostic criteria has been used in clinic work for about two years,and differentiated the symptoms of SS by TCM. The specialty and relationship between them was made an inquiry.RESULTS:The European criteria set for SS offers the clinic work a practical method to correctly classify the patients suspected of having this disorder. It refers to the signs and symptoms caused by the insufficiency of spleen-qi with deficiency of liver-yin and kidney-yin.CONCLUSION:It has been further proved for easy to make up the diagnostic of SS and its treatment using traditional chinese medicine.

Involvement of dopamine D1 and D2 receptors in Fos immunoreactivity induced by stepholidine in both intact and denervated striatum of lesioned rats

Stepholidine (SPD), a natural product, has been demonstrated in previous studies as a D1 agonist and D2 antagonist. In this work SPD-induced Fos immunoreactivity was examined. In the normal rats, Fos was induced in the striatum by SPD (1-20 mg/kg, i.p.) dose-dependently. The distribution of Fos-positive cells induced by SPD showed a rostral-caudal decline, matching the distribution of D2 dopamine receptors. The Fos-positive cells were mainly found in striatal neurons retrogradely labeled with horseradish peroxidase (HRP) from GP but not from SN, and could be abolished by the pretreatment of a D2 agonist LY171555 (2 mg/kg, i.p.), suggesting that the Fos expression in normal rats was due to the D2 antagonistic action of SPD. In the unilateral 6-hydroxydopamine-lesioned rats, SPD (4 mg/kg, i.p.) induced Fos expression in intact and denervated side of the striatum with different characteristics. Similar to that of normal rats, the Fos expression in intact side possessed the rostral-caudal gradient and could be abolished by the pretreatment of LY171555. However, in the denervated side, the Fos positive cells were widely distributed, and mainly found in striatal neurons retrogradely labeled from SN but not from GP. Furthermore, this expression was prevented by the pretreatment of SCH23390 (0.2 mg/kg, i.p.) but not LY171555, suggesting that the Fos expression in denervated side was due to the D1 agonistic action of SPD. Therefore, we concluded that the Fos expression induced by SPD in intact and denervated striatum was mediated via D2 and D1 receptor respectively, supporting the previous standpoint that SPD possesses the dual action, i.e antagonist to D2 and agonist to D1 receptors. Furthermore, it is suggested that the contralateral turning behavior induced by SPD may result from the D1-mediated excitation of striatonigral neurons of the denervated side of the lesioned rats.

[Studies on the phospho-tyrosine proteins during the proliferation cycle of cultured aortic smooth muscle cells]

The dynamic change and distribution of phospho-tyrosine proteins (P-tyr-Pr) during the cell cycle of cultured rabbit aortic smooth muscle cells (ASMC) were studied by ELISA and immunohistochemical technique. The antibody which was specific for P-tyr-Pr was prepared by immunizing California white rabbits with synthesized phospho-tyrosine bovine serum albumin, and then the IgG obtained was purified and coupled to horseradish peroxidase to make it ready for use in ELISA. We find that the content of particle P-tyr-Pr fluctuated in G1 stage, both in the cytosol and in the nucleus, being the highest at late G1 stage (9 h after G0), and the content of particle P-tyr-Pr was much higher in the nucleus than in the cytosol throughout G1 stage. The immunohistochemical study, which locates the distribution of P-tyr-Pr in ASMC, also revealed that the nuclei were stained much darker than the cytosol, and the total P-tyr-Pr content (including both particle and soluble P-tyr-Pr) was the highest at late G1 stage, or higher than at G0 and before S stage (12 h after G0). But the distribution before S stage was similar to that at late G1 stage, and although the total content before S stage was lower than at late G1 stage, it was evidently higher than that at G0 stage. This last finding might have some bearing on the role of tyrosine protein kinase in the events of a cell cycle.

Effect of human growth hormone on the proliferation of human fetal islet cells in vitro

In this study it was shown that 1000 micrograms/L hGH in serum-free medium promoted the attachment, spreading and formation of monolayer of islet cells. The radioactivity test indicated that hGH significantly stimulated the DNA synthesis of islet cells (P < 0.001). Furthermore, after 48 h exposure to hGH (1000 micrograms/L), both the insulin contents and release of islet cells significantly increased (P < 0.001); hGH also enhanced the responsiveness of fetal islet cells to high-concentration glucose plus theophylline stimulation (P < 0.001). However, the effect of hGH in the medium containing 10% newborn calf serum was not so prominent in comparison with that in the serum-free medium. The morphologic assay for mitotic cells showed a combination of 1000 micrograms/L hGH and 10% serum was the most efficient for inducing the mitosis, the mitotic index being 5.95%. We conclude that hGH is an important growth factor for human islet cells.