Physiology and transcriptome of Eucommia ulmoides seeds at different germination stages

E. ulmoides (Eucommia ulmoides) has significant industrial and medicinal value and high market demand. E. ulmoides grows seedlings through sowing. According to previous studies, plant hormones have been shown to regulate seed germination. To understand the relationship between hormones and E. ulmoides seed germination, we focused on examining the changes in various indicators during the germination stage of E. ulmoides seeds. We measured the levels of physiological and hormone indicators in E. ulmoides seeds at different germination stages and found that the levels of abscisic acid (ABA), gibberellin (GA), and indole acetic acid (IAA) significantly varied as the seeds germinated. Furthermore, we confirmed that ABA, GA, and IAA are essential hormones in the germination of E. ulmoides seeds using Gene Ontology and Kyoto Encyclopedia of Genes and Genomics enrichment analyses of the transcriptome. The discovery of hormone-related synthesis pathways in the control group of Eucommia seeds at different germination stages further confirmed this conclusion. This study provides a basis for further research into the regulatory mechanisms of E. ulmoides seeds at different germination stages and the relationship between other seed germination and plant hormones.

The investigation of composition and thermal behavior of two types of backfilling gutta-percha

Background/purpose

In the warm gutta-percha technique, soft-type and regular-type gutta-percha are using for backfilling thermoplasticized injection system. However, there are limited reports about the properties of these backfilling gutta-percha. This study aimed to analyze and compare the composition, thermal behavior and compact force of two types of backfilling gutta-percha.

Materials and methods

Soft-type and regular-type backfilling gutta-percha (B&L BioTech, Fairfax, VA, USA) were investigated. The inorganic and organic fractions of these gutta-perchas were separated by quantitative chemical analysis (n = 6). Their composition was analyzed using energy dispersive spectroscopy. Thermal behavior in response to temperature variations was analyzed using differential scanning calorimetry. Additionally, a compaction model was used to investigate the relation between compaction force and temperature (n = 10).

Results

The soft-type contained more gutta-percha (3.69-5.85%), carbon ratio (38.96-48.52%) and less inorganic substance (86.51-90.45%), zinc ratio (29.36-35.67%). The composition ratio of two types gutta-percha were statistically significant different (P < 0.05). There were three phase transitions of the soft-type gutta-percha which started at 39.84 °C, 49.32 °C and 54.15 °C while the two phase transitions of the regular-type gutta-percha started at 40.48 °C and 53.45 °C. The glass transition temperature of the regular-type gutta-percha (44.24 °C) was higher than that of the soft-type gutta-percha (40.66 °C). Under various setting temperature, the higher compaction force in the regular-type gutta-percha was required (P < 0.05).

Conclusion

The different components in gutta-percha contribute to its differences in thermal behavior. The soft-type had a higher proportion of gutta-percha and lower ZnO which makes the fluidity better than the regular-type.

An Overview on Total Valorization of Litsea cubeba as a New Woody Oil Plant Resource toward a Zero-Waste Biorefinery

With the increasing global demand for edible oils and the restriction of arable land minimum in China, woody oil plants have gradually become the optimal solution to cover the shortage of current edible oil supply and to further improve the self-sufficiency rate. However, due to the lack of knowledge and technique, problems like “how to make full use of these plant resources?” and “how to guide consumers with reasonable data?” limit the development of woody oilseed industry towards a sustainable circular economy. In this review, several emerging unique woody oil plants in China were introduced, among which Litsea cubeba as a new woody oil plant was highlighted as a reference case based on its current research progress. Unlike other woody oil plants, essential oil rather than oil from Litsea cubeba has always been the main product through the years due to its interesting biological activities. Most importantly, its major component, citral, could be the base for other synthesized perfume compounds with added value. Moreover, the sustainable biorefinery of large amounts of waste residual after Litsea cubeba essential oil processing is now technically feasible, which could inspire a total valorization pathway for other woody oil plants to make more competitive plant-based products with both economic, social, and ecological benefits.

Thermal behavior and viscoelastic properties of gutta-percha used for back-filling the root canal

BACKGROUND/PURPOSE

In clinical operations, qualitative differences in the texture and operational feeling of the regular type and soft type back-filled gutta-percha are readily discernible. This study aimed to investigate and compare the thermal behavior and physical properties of the two gutta-percha materials.

MATERIALS AND METHODS

The chemical compositions of regular and soft type Gutta-Percha Obturator® pellets were examined via energy dispersive X-ray spectroscopy. The thermal behaviors of the pellets during heating and cooling were evaluated using a differential scanning calorimeter. Finally, the viscoelastic properties of the two materials during cooling were assessed using a modular compact rheometer.

RESULTS

The soft type gutta-percha contained a greater atomic percentage of zinc than the regular type material. In addition, the soft type gutta-percha exhibited exothermic peaks during cooling, whereas the regular type gutta-percha did not. The two materials exhibited different viscoelastic behaviors under cooling. In particular, the rate of change of the loss factor for the soft type gutta-percha was more than that of the regular type gutta-percha at temperature lower than 80°C.

CONCLUSION

The soft type gutta-percha underwent significant crystallization during cooling, and therefore exhibited pronounced volume shrinkage. Furthermore, the soft type gutta-percha underwent a greater rate of change in viscoelasticity under cooling than the regular type gutta-percha, and exhibited poorer physical stability. Consequently, in the back-packing procedure, soft type gutta-percha must be compacted more often over time than regular type gutta-percha to ensure the same quality of root canal obturation.