Automated Mechanical Exfoliation of MoS2 and MoTe2 Layers for 2D Materials Applications.

An automated technique is presented for mechanically exfoliating single-layer and few-layer transition metal dichalcogenides using controlled shear and normal forces imposed by a parallel plate rheometer. A thin sample that is removed from bulk MoS2 or MoTe2 is initially attached to the movable upper fixture of the rheometer using blue dicing tape while the lower base plate also has the same tape to capture and exfoliate samples when the two plates are brought into contact then separated. A step-and-repeat exfoliation process is initiated using a preprogrammed contact force and liftoff speed. It was determined that atomically thin films of these materials could be obtained reproducibly using this technique, achieving single-layer and few-layer thicknesses for engineering novel 2D transistor devices for future electronic technologies. We show that varying the parameters of the rheometer program can improve the mechanical exfoliation process.

Knowledge and attitudes to prescription charges in New Zealand and England.

BACKGROUND: Prescription charge regimes vary between countries but there is little research on how much people know about these or support values underlying them. OBJECTIVE: To explore, in New Zealand (NZ) and England, the public's knowledge of, and attitudes to, charges and whether knowledge and attitudes varied by demographic characteristics or by values about entitlement to public goods. METHOD: A questionnaire was developed and administered to people over 18 recruited in public places in NZ and England. RESULTS: 451 people in NZ and 300 people in England participated. Less than half in each country knew the current prescription charge. In each country 62% of people were unaware of arrangements to protect people from excessive annual charges. Support for free or lower cost medicines for children, people over 65, people on low incomes, people on benefits, and people with chronic health problems was higher in England than in NZ. Support varied by participants' demographic characteristics and, in the case of people on low incomes and people on benefits, by values about universal entitlements. DISCUSSION: Gaps in knowledge, particularly about mechanisms to protect people from high costs, are concerning and may lead to people paying excessive charges. There was consensus about the elderly, children and the chronically ill being "deserving" of lower prescription charges, but people who did not believe in universal access to public goods appeared to see people on low incomes or benefits as less "deserving". In general, public views resembled those underlying the prescription charge regime in their country.

In vitro conservation and sustained production of breadfruit (Artocarpus altilis, Moraceae): modern technologies for a traditional tropical crop.

Breadfruit (Artocarpus altilis, Moraceae) is a traditionally cultivated, high-energy, high-yield crop, but widespread use of the plant for food is limited by poor quality and poor storage properties of the fruit. A unique field genebank of breadfruit species and cultivars exists at the National Tropical Botanical Garden in the Hawaiian Islands and is an important global resource for conservation and sustainable use of breadfruit. However, this plant collection could be damaged by a random natural disaster such as a hurricane. We have developed a highly efficient in vitro plant propagation system to maintain, conserve, mass propagate, and distribute elite varieties of this important tree species. Mature axillary shoot buds were collected from three different cultivars of breadfruit and proliferated using a cytokinin-supplemented medium. The multiple shoots were maintained as stock cultures and repeatedly used to develop whole plants after root differentiation on a basal or an auxin-containing medium. The plantlets were successfully grown under greenhouse conditions and were reused to initiate additional shoot cultures for sustained production of plants. Flow cytometry was used to determine the nuclear deoxyribonucleic acid content and the ploidy status of the in vitro grown population. The efficacy of the micropropagation protocols developed in this study represents a significant advancement in the conservation and sustained mass propagation of breadfruit germplasm in a controlled environment free from contamination.

Assessment of genetic stability of the germplasm lines of medicinal plant Scutellaria baicalensis Georgi (Huang-qin) in long-term, in vitro maintained cultures.

An approach of combining flow cytometry (FCM) analysis with morphological and chemical profiling was used to assess the genetic stability and bioactive compound diversity in a Scutellaria baicalensis Georgi (Huang-qin) germplasm collection that was clonally maintained in in vitro for a period of over 6 years. Based on the FCM analysis of nuclei samples from young shoots, the nuclear DNA content of S. baicalensis was calculated as 0.84 pg/2C. FCM analysis showed no significant variation in the nuclear DNA contents and ploidy levels in the long-term in vitro maintained germplasm lines. Germplasm lines, acclimatized to ex vitro conditions, exhibited distinctive plant growth and bioactive compound production capacities. The high level of genetic stability observed in in vitro maintained S. baicalensis lines opens up a variety of opportunities such as allowing long-term aseptic preservation and easy distribution of well-characterized germplasm lines of this medicinal plant species. This study represents a novel approach for continuous maintenance, monitoring, and production of medicinal plant tissues with specific chemistry.

Genetic diversity in seed populations of Echinacea purpurea controls the capacity for regeneration, route of morphogenesis and phytochemical composition.

The production of new varieties and higher quality products from Echinacea spp. requires a greater understanding of the regulation of plant growth and the production of specific phytometabolites. The current studies were designed to generate elite varieties of Echinacea purpurea based on regeneration efficiency and chemical profile. Clonal propagation of seedling-derived regenerants and screening for antioxidant potential and concentrations of caftaric acid, chlorogenic acid, cichoric acid, cynarin, and echinacoside identified 58 unique germplasm lines. Chemical profiles varied significantly among germplasm lines but were consistent within clones of each line. In temporary immersion bioreactors, exogenous application of the auxin indolebutyric acid significantly increased the cichoric acid and caftaric acid concentration in the root tissues. Together, these demonstrate the potential for selective breeding of elite, highly regenerative, chemically superior, clonally propagated varieties from the naturally occurring genetic variability in the seed populations of E. purpurea.