Simulation Study: The Impact of Structural Variations on the Characteristics of a Buried-Channel-Array Transistor (BCAT) in DRAM

As the physical dimensions of cell transistors in dynamic random-access memory (DRAM) have been aggressively scaled down, buried-channel-array transistors (BCATs) have been adopted in industry to suppress short channel effects and to achieve a better performance. In very aggressively scaled-down BCATs, the impact of structural variations on the electrical characteristics can be more significant than expected. Using a technology computer-aided design (TCAD) tool, the structural variations in BCAT (e.g., the aspect ratio of the BCAT recess-to-gate length, BCAT depth, junction depth, fin width, and fin fillet radius) were simulated to enable a quantitative understanding of its impact on the device characteristics, such as the input/output characteristics, threshold voltage, subthreshold swing, on-/off-current ratio, and drain-induced barrier lowering. This work paves the road for the design of a variation-robust BCAT.

General and Device-Specific Reasons for ENDS Use: A Qualitative Study with Adult ENDS Users

BACKGROUND

A scientific consensus on the public health impact of electronic nicotine delivery systems (ENDS) remains elusive. This is partly due to the wide variation in product characteristics often lumped together under one category. Research is needed to better understand what ENDS device type characteristics motivate their use by adults.

METHODS

Nine focus groups of 32 current ENDS users who were 18+ years old, had used ENDS in the previous 30 days, and had been using ENDS for more than two months were held either in person or online between February and June 2020.

RESULTS

Participants' reasons for their choice of ENDS characteristics included both general, applying to all ENDS products, and specific, relating to particular ENDS devices. Health benefits and the lack of offensive odor were commonly identified as important reasons for using ENDS in general. Flavor and product discreteness were both general and device-specific determinants of ENDS use. Conversely, nicotine delivery, cloud size, battery properties, aesthetics, ease of use, and cost were device-specific drivers of participants' choice.

CONCLUSIONS

The reasons that adults choose to use ENDS are complex and sometimes related to both ENDS as a category and as specific ENDS product types. Regulations and public communication campaigns should reflect their ultimate objective and consider both general and specific motivations when attempting to achieve public health objectives.

E-cigarette use behaviors and device characteristics of daily exclusive e-cigarette users in Maryland: Implications for product toxicity

INTRODUCTION

Few studies to date have characterized daily exclusive e-cigarette users, device characteristics, and use behaviors. This study describes daily e-cigarette user characteristics, and assesses the association between user behaviors and demographics.

METHODS

From 2015–2017, 100 daily exclusive e-cigarette users and 50 non-users were recruited in Maryland, USA. Sociodemographic characteristics, health status, e-cigarette/tobacco use behaviors, device characteristics, and reasons for e-cigarette use were collected by interview. Chi-squared tests (categorical variables), Student’s t-test (continuous variables), and linear regressions were used to assess relationships between variables.

RESULTS

Most daily exclusive e-cigarette users were men, White, former smokers, used MODs/tanks, and vaped on average 365 puffs/day (SD: 720). A third of users first vaped within 5 minutes of waking in the morning, and 56% vaped throughout the day. E-liquid consumption ranged from 5–240 mL/week (median: 32.5), with nicotine concentration 0–24 mg/mL (median: 3). E-cigarette users were more likely to report wheezing/whistling and hypertension than controls, although the finding was not statistically significant after adjustment. Less than half planned to quit vaping.

CONCLUSIONS

Daily e-cigarette users between 2015–2017 most commonly vaped MOD/tank devices. Being male and of lower education was associated with higher usage. Daily users with no intention to quit may be at risk for increased exposure to emissions from e-cigarettes that include inorganic (metals) and organic (e.g. acrolein, formaldehyde) compounds with known toxic effects, particularly to the lung. Further research is needed to characterize the long-term health effects of daily e-cigarette use.