Selaginellin derivatives from Selaginella tamariscina and evaluation for anti-breast cancer activity.

A phytochemical investigation of Selaginella tamariscina led to the isolation of 17 selaginellin derivatives. Their inhibitory activities against breast cancer cells were screened, and preliminary structure-activity relationships were also established. Among them, dimeric selaginellin 17 showed potential activity against MDA-MB-231 cells with an IC50 value of 3.2 ± 0.1 µM, corresponding to 4-fold higher potency than the reference compound 5-FU (IC50 14.8 ± 0.2 µM). Mechanistic studies indicated that 17 could cause G2/M phase arrest in MDA-MB-231 cells and induce apoptosis accompanied by increased ROS levels.

The application of an intraoral banana peel suturing model in surgical training of dental students.

OBJECTIVES: This study investigated the application of an intraoral banana peel suturing model in helping students to acquire intraoral surgical techniques. METHODS: This is a self-control study conducted from January 2021 to March 2021. An intraoral banana peel suturing model was implemented to provide oral suture experience for undergraduates majoring in stomatology. The sutures students placed in the model were photographed and evaluated blindly by a professional team using an established scoring system. Training scores were recorded before (training 1) and after 2 months of training (training 2). Linear regression was used to examine factors related to the scores. Suturing training was conducted in the School and Hospital of Stomatology at Peking University. A total of eighty-two students in Peking University School and Hospital of Stomatology were in their fourth pre-clinical year and followed a workshop on surgical sutures according to the curriculum. All students who should take this course were included, and the response rate was 100%. RESULTS: The mean training 2 score (23.04 ± 3.83) was higher than the mean training 1 score (13.94 ± 3.15). The training 1 score was not significantly correlated with any of the students' general characteristics. The training 2 score was correlated with the training 1 score and the cumulative duration of practice outside of class. CONCLUSION: The intraoral banana peel suturing model can be used for suture training, and dental students' suture ability was improved after using the banana peel for suture practice.

[Early effects of forest harvesting gap on understory plant diversity of three different plantations in Baiyun Mountain, China.] / 采伐林窗对白云山3ç§äººå·¥æž—æž—ä¸‹æ¤ç‰©å¤šæ ·æ€§çš„æ—©æœŸå½±å“.

Pinus massoniana, Cunninghamia lanceolata, and Phyllostachys edulis are the main afforesting species in the low hilly areas and valley of the southern Yangtze River for commercial purpose. Ecological problems such as the monotonous community structure and low biodiversity are common in these plantations. To understand the effect of forest harvesting gap on the understory plant diversity in the three plantations, different size gaps with identical habitats were conducted with cano-pies as control in the three plantations in Baiyun Mountain. The life form spectrum of plants and plant diversity were compared among the different forest gaps. The results showed that species richness was the highest in C. lanceolata plantation (57 species), followed by P. edulis plantation (53 species) and P. massoniana plantation (41 species) in two years after harvesting. In the early period, plant species were more abundant in the gaps than that in the controls in C. lanceolata and P. edulis plantations, but there was no significant difference between the gaps and the control in P. masso-niana plantation. The percentage of phanerophyte plants were significantly higher in the forest gaps covered 500 m2 area than that with other sizes. The percentage of the hemicryptophyte and therophyte plants were higher in the forest gaps covered 250 m2 area. The percentage of geophyte plants were higher in the forest gaps with 50 m2 area than the others. The resembling coefficients between the different size gaps were higher than that between the gaps and the control in the same plantation. The resembling coefficients between different size gaps in the same plantation were higher than that between different size gaps in different plantations. The resembling coefficients between the gaps and the control in different plantations were generally lower than the others. The species richness, Simpson ecological dominance index, and Shannon diversity index differed significantly for different size gaps. Except for Simpson ecological dominance index, the indices were significantly influenced by the plantation types. The effects of the interaction between plantation types and gap sizes on these indices were not statistically significant. Forest harvesting gaps altered life form spectrum of understory plants and increased plant diversity in the three plantations.

Analysis of graphene TE surface plasmons in the terahertz regime.

Unlike common metals, graphene can support transverse electric (TE) surface modes when the imaginary part of its conductivity is negative. We have theoretically investigated and numerically simulated plasmonic properties of graphene TE surface plasmons (SPs) in the terahertz regime. The influence of the external magnetic field, gate voltage and temperature as the tuning schemes of the SPs have been investigated. The results show that graphene TE modes can be realized by tuning the magnetic fields or gate voltage. If the permeability of the dielectrics on both sides of the graphene layer differs enough, the graphene TE modes can still be achieved. The work presented here has the potential for application to graphene-based plasmonic devices in photonics and optoelectronics, such as sensors, polarizers and modulators.

Numerical analysis of the propagation properties of subwavelength semiconductor slit in the terahertz region.

The propagation properties of terahertz (THz) waves passing through heavily doped semiconductor slit have been numerically investigated by using the transfer matrix method. The effects of geometrical parameters, carrier concentration, and dielectric materials filling in the slit have been considered. The contour for carrier concentration and slit width show that as slit width and carrier concentration decreases, the effective indices increase and the propagation lengths decrease. For the case of water filling in the slit, temperature has more effect on the imaginary part of propagation constant than the real part. Most of the energy stored in the slit is in the form of electric energy, which firstly decreases and then increases with the decreasing of slit width. It is expected that the semiconductor slit structure is very useful for the practical applications of THz waves in the fields of biological specimen analysis and medical diagnosis.