This study uses first-principles calculations to investigate the mechanical properties and effect of strain on the electronic properties of the 2D material 1H-PbX2 (X: S, Se). Firstly, the stability of the 1H Pb-dichalcogenide structures was evaluated using Born’s criteria. The obtained results show that the 1H-PbS2 material possesses the greatest ideal strength of 3.48 N/m, with 3.68 N/m for 1H-PbSe2 in biaxial strain. In addition, 1H-PbS2 and 1H-PbSe2 are direct semiconductors at equilibrium with band gaps of 2.30 eV and 1.90 eV, respectively. The band gap was investigated and remained almost unchanged under the strain εxx but altered significantly at strains εyy and εbia. At the fracture strain in the biaxial direction (19 %), the band gap of 1H-PbS2 decreases about 60 %, and that of 1H-PbSe2 decreases about 50 %. 1H-PbS2 and 1H-PbSe2 can convert from direct to indirect semiconductor under the strain εyy. Our findings reveal that the two structures have significant potential for application in nanoelectronic devices.

A combination of Polycarbonate (PC) material and Polymethylmethacrylate (PMMA), fabricated using an injection molding machine, has been investigated to determine its advantages, as studied in Ref. 1). This paper aims to investigate the optimization of PMMA/PC blend for both tensile yield strength and impact strength. Furthermore, interaction effects of process conditions on mechanical properties including tensile yield strength and impact strength of PMMA/PC blend by injection molding process are interpreted in this study. Tensile and impact specimens are designed following ASTM, type V, and are fabricated by injection molding process. The processing conditions such as melt temperature, mold temperature, packing pressure, and cooling time are applied; each factor has three levels. As a result, in comparison with optimization of separated responses, mechanical properties of PMMA/PC are found to decrease when optimizing both tensile and impact strengths simultaneously. The melt temperature is found to be the most significant interaction parameter with the mold temperature and packing pressure. In addition, there is more interaction between the mold temperature and cooling time. This investigation provides a useful understanding of the control of injection molding processing of polymer blends in optical application.

딸기는 세계적으로 중요하고 인기있는 과채류이며 ‘설향’은 국내 시장에서 재배되고 있는 주요 품종 중 하나이다. 딸기의 생장과 화아 유도는 이 작물의 과실에 수량에 직접적으로 영향을 미치는 과정이다. 본 연구에서는 벤질아데닌(BA), 지베렐린 산(GA3), 살리실 산(SA)이 ‘설향’ 딸기의 생장과 화아 유도에 미치는 영향 을 조사하였다. 21구 트레이에서 번식된 지 3주가 경과한 런너묘를 온도는 25oC/15oC(주간/야간), 상대습도는 70%, 광원은 백색 LED, 광도는 300 μmol·m-2·s-1 PPFD로 유지되는 생장 챔버에서 재배하였다. BA, GA3 및 SA를 각 0(대조구), 100, 200 mg·L-1로 런너묘에 처리하였다. 이러한 생장조절제를 런너묘의 잎에 2주 간격으로 2회 엽면살포하였다. 9주 후의 생육을 비교한 결과, 생장조절제를 엽면살포한 모든 처리에서 대조구에 비해 근장과 엽록소함량(SPAD)이 감소하는 경향을 보였다. GA3 처리에서 엽록소함량(SPAD)이 가장 낮았다. 하지만 GA3 200 mg·L-1 처리에서 엽면적, 잎 생체중, 식물 생체중이 증가하였다. 화아유도율과 화수는 SA 200 mg·L-1 처리에서 각 85%와 식물체당 4.3개로 가장 높았고 그 다음으로 SA 200 mg·L-1 처리에서 높았다. 전체적으로 GA3 처리에서 식물 생장을 향상시켰고, SA 처리에서는 개화를 촉진하였다. 더 나아가 GA3와 SA를 혼합한 처리를 추가한 연구를 수행하여 생장조절제간의 관계를 구명하고 그 결과에서의 분자 메커니즘과 관련된 반응을 조사하는 것이 필요하다고 판단된다.

In this study, the principal objective was to investigate the effect of light quality and vessel ventilation on the growth and development, physiology, activities of antioxidant enzymes, and contents of mineral nutrients of carnation (Dianthus caryophyllus L.) ‘Marble Beauty’. Single node cuttings stuck into the plant growth regulator (PGR)-free MS medium in containers covered with caps with or without a ventilation filter were cultured first four weeks under white and then additional four weeks under either white (control), blue, red, or red + blue light emitting diodes (LEDs) for 56 days. Interestingly, a ventilated culture condition not only reduced the percentage of the hyperhydricity, but also increased the total chlorophyll content (Chl a + Chl b) of the plantlets as compared to the non-ventilated condition. In addition, blue LEDs produced plantlets with the greatest number of shoots and red LEDs produced plantlets with the greatest shoot length. The quality of plantlets was improved under a ventilation condition. Besides, under a ventilated condition, red + blue LEDs raised APX activity, and blue LEDs not only raised the activity of the CAT, but also increased tissue contents of such elements as K, Ca, Mg, Zn, Mn and Fe. The red LEDs increased contents of B and Si under a ventilated condition, and Na accumulation under a non-ventilated condition. Thus, including blue or red LEDs as the light source in a ventilated culture condition will produce plantlets of carnation ‘Marble Beauty’ in vitro with improved quality.

Carnation (Dianthus caryophyllus L.) ‘Purple Beauty’ at micropropagation stage 3 was cultured under two levels each of medium sucrose concentration (0 and 30 g·L-1), photosynthetic photon flux density (50 and 200 μmol·m-2·s-1 PPFD), and CO2 concentration (350 and 1,000 μmol·mol-1), in a factorial experimental design, consisting of all eight possible treatment combinations. Shoot tip explants, obtained from in vitro-grown plantlets, were cultured on 50 mL agar-solidified Murashige and Skoog medium per container. Each culture container was sealed with a rigid lid vented by a high-efficiency particulate air filter attached to a 10 mm diameter hole made in the lid center, with an estimated number of 2.8 air exchanges per hour. All cultures were maintained for four weeks at 24°C/22°C (day/night) temperatures, 70%–80% relative humidity, and a 16 h/8 h (day/night) photoperiod was provided by white light-emitting diodes. The treatment combining high light intensity (200 μmol·m-2·s-1), high CO2 concentration (1,000 μmol·mol-1), and without supplementation of sucrose to the medium (i.e., photo-autotrophic conditions) resulted in better plantlet growth and development, with higher values being observed in terms of total fresh weight, tissue water content, leaf length, leaf width, and total chlorophyll content than in plantlets grown under the other treatments.

Ampelopsis brevipedunculata (Maxim.) Trautv., also known as porcelain berry, has been used for many years as herbal folk medicine to treat liver diseases. This study was conducted to assess the influence of various factors on the rooting of hardwood stem cuttings of this plant species, collected from Jeju Island (Korea). Three experiments were conducted: (1) Stems of three diameters (≤ 4.5, > 4.5 – < 6.5, or ≥ 6.5 mm), (2) four types of rooting media [rockwool cubes, perlite, peat moss + perlite (3:1, v/v), or vermiculite] and (3) indole-3-butyric acid (IBA) at four treatment concentrations (0, 100, 200, or 400 mg·L-1). For the IBA concentration experiments, cuttings of the various diameters were inserted to a depth of 2 cm in a commercial propagation medium in 72-cell plug trays. The planted stem cuttings were initially placed on a fog bench for 16 days at 95% ± 5% relative humidity at a temperature of 25°C ± 3°C under 95% shade. The stem cuttings were then transferred to a greenhouse bench under ambient light and fed a nutrient solution on a daily basis for 2 weeks. Among the tested stem diameters, cuttings with a stem diameter ≥ 6.5 mm produced the largest stem diameter (2.6 mm) of new shoot, but without root growth. Initial stem diameter significantly affected the length of the new shoot, and the longest shoot length (67.8 mm) was observed in cuttings with an initial stem diameter of ≥ 6.5 mm. Cuttings inserted in vermiculite produced the largest diameter of new shoot (2.4 mm), whereas cuttings grown in rockwool cubes produced the shortest, stem diameter of new shoot growth (1.9 mm). No significant differences (p ≤ 0.05) were observed in the length of new shoot growth among the various rooting media and IBA concentrations. Furthermore, all tested IBA concentrations failed to induce rooting. Collectively, these results suggest that porcelain berry cuttings with an initial diameter of ≥ 6.5 mm have higher survival and bud break, but they did not produce rooting. Further studies are needed to optimize the protocol for the rooting of hardwood stem cuttings of A. brevipedunculata (Maxim.) Trautv.

다양한 지질명소가 국내에 분포하고 있음에도 불구하고, 지질명소를 야외학습장으로 활용하지 못하고 있다. 이 연구의 목적은 상세한 지질조사를 통해 서낭바위 일대를 야외학습장으로 활용 가능하게 하는데 있다. 서낭바위는 강원도 죽왕면 송지호해수욕장 부근에 위치하며, 송지호에서 남동쪽으로 약 1km 떨어져 있다. 서낭바위 일대는 중생대 백악기 속초화강암과 이를 부정합으로 충적층이 덮고 있는 단순한 암석분포를 보인다. 서낭바위 일대는 초중등학생과 일반인들에게 화강암 암상, 구성광물, 풍화과정뿐만 아니라, 절리(N50E/80SW, N40W/84NW), 단층(N42W/83SW), 엽리(N32E/54SE), 암맥(N35E/40SE, N26W/63SW)과 같은 지질구조와, 토르, 타포니, 그루부, 나마와 같은 지형들을 학습할 수 있는 장소이다. 그러므로 서낭바위 일대는 작은 규모의 공간에서 여러 지질 및 지형학적 현상들을 학습하고 서낭바위의 성인을 토론할 수 있는 최적의 야외학습장이다.