Competitive effect between roughness and mask pattern on charging phenomena during plasma etching

In plasma etching process, the edge roughness and mask pattern usually play a significant role in the deformation of holes under the influence of charging effect. The competitive effect between these two factors has been investigated, focusing on the surface charging in a hexagonal array, with various values of roughness parameters (amplitude (A) and wavelength (W)) and distances between holes (L). A series of classical particle dynamic simulations of surface charging, surface etching and profile evolution were used to investigate the effect of roughness and pattern on charging. This study showed that various roughness and patterns (represented by different values of L) can significantly influence surface distributions of the electric-field (E-field) and the etching rates on the mask surface. The simulations also showed that (1) the shape of the pattern array influences the mask hole profile during etching process, i.e. a hexagonal array pattern tends to deform the profile of a circular mask hole into a hexagonal hole; (2) pattern roughness is aggravated during etching process. These factors were found to be significant only at a small feature pitch and may be ignored at a large feature pitch. Possible mechanisms of these results during etching process are discussed. This work sheds light on the ways to maintain pattern integrity and further improve the quality of the pattern transfer onto the substrate.

A Research on the Crisis Spillover Effect of Food Safety Incidents on Competitive Firms: The Influence of Political Connections and Charitable Donations

Taking the perspective of corporate social responsibility and institutional theory, this research establishes an innovative relationship between variables such as charitable donation, political connection and crisis spillover effect of firms through quantitative analysis using the event study method, regression analysis and the Heckman two-stage model. Taking 8 food safety incidents from 2011 to 2016 as research samples, this paper studies the impact of food safety incidents on the market value of both firms under crisis and their competitive firms, as well as the influence of political connection and charitable donation. Based on the current situation that the product crisis or reputation crisis of a firm will, inevitably, affect the market performance and value of its competitive firms in the same industry, this paper attempts to answer questions such as “what kind of firms are capable of minimizing this negative influence?” “will the political connection of competitive firms exert a positive or negative impact?” and “can actions taken before the crisis, such as charitable donation of competitive firms, help these firms in reducing the harm?” The conclusions are as follows: first, the occurrence of food safety incidents not only has a negative impact on the market value of the crisis firm, but also has a negative spillover effect on the competitive firm; second, charitable donations made by the competitive firm before the crisis demonstrates a positive competitive effect on the competitive firm, and the intensity of such charitable donations is positively correlated with this positive competitive effect; third, the political connection of the competitive firm has no significant impact on the crisis spillover effect. These findings provide enlightenment for the operation and management of firms in the food industry.

Solar Photovoltaic Investment Changes across China Regions Using a Spatial Shift-Share Analysis

Solar photovoltaic (PV) has become the fastest-growing new energy in China and one of the main contributors to China’s clean energy transition. From 2013 to 2019, China’s solar PV installed capacity grew from 15,890 MW to 204,180 MW, increasing by 11.85 times. To explore solar PV investment changes across China regions, we use spatial shift-share analysis model to decompose solar PV investment changes from 2013 to 2019 into four components: national energy investment growth effect (NEG), national energy investment structure effect (NES), neighbor–nation solar PV investment competitive effect (NNC), and region–neighbor solar PV investment competitive effect (RNC). Based on the decomposition results, we find that the value of NNC of most western provinces is negative for the entire period, while the NNC of most central and eastern provinces is in the middle and lower range. There is little difference in RNC among these regions. While comparing the influence caused by the four effects, NNC and RNC play dominant roles in solar PV investment changes in eastern and central provinces, which means NEG and NES have relatively small impacts. By contrast, NEG and NES affect the solar PV investment changes at a larger scale in most western provinces. Comparing the NNC and RNC, we find that RNC played a prominent role in the eastern and central regions, while NNC played a dominant role in the west.

Screening and evaluation of the strong endogenous promoters in Pichia pastoris

Background Due to its ability to perform fast and high-density fermentation, Pichia pastoris is not only used as an excellent host for heterologous protein expression but also exhibits good potential for efficient biosynthesis of small-molecule compounds. However, basic research on P. pastoris lags far behind Saccharomyces cerevisiae, resulting in a lack of available biological elements. Especially, fewer strong endogenous promoter elements available for foreign protein expression or construction of biosynthetic pathways were carefully evaluated in P. pastoris. Thus, it will be necessary to identify more available endogenous promoters from P. pastoris. Results Based on RNA-seq and LacZ reporter system, eight strong endogenous promoters contributing to higher transcriptional expression levels and β-galactosidase activities in three frequently-used media were screened out. Among them, the transcriptional expression level contributed by P0019, P0107, P0230, P0392, or P0785 was basically unchanged during the logarithmic phase and stationary phase of growth. And the transcriptional level contributed by P0208 or P0627 exhibited a growth-dependent characteristic (a lower expression level during the logarithmic phase and a higher expression level during the stationary phase). After 60 h growth, the β-galactosidase activity contributed by P0208, P0627, P0019, P0407, P0392, P0230, P0785, or P0107 was relatively lower than PGAP but higher than PACT1. To evaluate the availability of these promoters, several of them were randomly applied to a heterogenous β-carotene biosynthetic pathway in P. pastoris, and the highest yield of β-carotene from these mutants was up to 1.07 mg/g. In addition, simultaneously using the same promoter multiple times could result in a notable competitive effect, which might significantly lower the transcriptional expression level of the target gene. Conclusions The novel strong endogenous promoter identified in this study adds to the number of promoter elements available in P. pastoris. And the competitive effect observed here suggests that a careful pre-evaluation is needed when simultaneously and multiply using the same promoter in one yeast strain. This work also provides an effective strategy to identify more novel biological elements for engineering applications in P. pastoris.