Removal of Stair-Step Effects in Binder Jetting Additive Manufacturing Using Grayscale and Dithering-Based Droplet Distribution

Binder jetting is a layer-based additive manufacturing process for three-dimensional parts in which a print head selectively deposits binder onto a thin layer of powder. After the deposition of the binder, a new layer of powder is applied. This process repeats to create three-dimensional parts. The binder jetting principle can be adapted to many different materials. Its advantages are the high productivity and the high degree of freedom of design without the need for support structures. In this work, the combination of binder jetting and casting is utilized to fabricate metal parts. However, the achieved properties of binder jetting parts limit the potential of this technology, specifically regarding surface quality. The most apparent surface phenomenon is the so-called stair-step effect. It is considered an inherent feature of the process and only treatable by post-processing. This paper presents a method to remove the stair-step effect entirely in a binder jetting process. The result is achieved by controlling the binder saturation of the individual voxel volumes by either over or underfilling them. The saturation is controlled by droplet size variation as well as dithering, creating a controlled migration of the binder between powder particles. This work applies the approach to silica sand particle material with an organic binder for casting molds and cores. The results prove the effectiveness of this approach and outline a field of research not identified previously.     

Can Finite Element Method Obtain SVET Current Densities Closer to True Localized Corrosion Rates?

In this paper, the finite element method was used to simulate the response of the scanning vibrating electrode technique (SVET) across an iron–zinc cut-edge sample in order to provide a deeper understanding of the localized corrosion rates measured using SVET. It was found that, if the diffusion layer was neglected, the simulated current density using the Laplace equation fitted the experimental SVET current density perfectly. However, the electrolyte was not perturbed by a vibrating SVET probe in the field, so a diffusion layer existed. Therefore, the SVET current densities obtained from the local conductivity of the electrolyte would likely be more representative of the true corrosion rates than the SVET current densities obtained from the bulk conductivity. To help overcome this difference between natural conditions and those imposed by the SVET experiment, a local electrolyte corrected conductivity SVET (LECC-SVET) current density was introduced, which was obtained by replacing the bulk electrolyte conductivity measured experimentally by the local electrolyte conductivity simulated using the Nernst−Einstein equation. Although the LECC-SVET current density did not fit the experimental SVET current density as perfectly as that obtained from the Laplace equation, it likely represents current densities closer to the true, unperturbed corrosion conditions than the SVET data from the bulk conductivity.     

Peer Reviewed: Differences in Health and Health Behaviors Between State Employees and Other Employed Adults in Oregon, 2007

Introduction

Worksite health promotion and interventions have gained popularity among state agencies. We studied the health behaviors and health characteristics of adults employed in state agencies in Oregon and compared those state employees with the statewide population of employed, insured adults.

Methods

We used data from the Oregon Behavioral Risk Factor Surveillance System (BRFSS) and a modified BRFSS survey administered to state employees. State employees were compared with employed, insured BRFSS respondents in total and then separately for men and women.

Results

The prevalence of healthy weight was lower among state employees compared with the statewide population of employed, insured adults (29% vs 35%), and the prevalence of obesity was higher (35% vs 26%). State employees were also less likely to meet physical activity recommendations (44% vs 56%). Diabetes prevalence was higher among state employees (7% vs 5%), and self-reported excellent or very good health status was lower (54% vs 64%).

Conclusions

State employees differ from the statewide population of employed, insured adults on a number of health behaviors and conditions. These differences suggest obesity prevention and diabetes control as priority areas for state agency worksite interventions.     

Extensively drug-resistant (XDR) Neisseria gonorrhoeae causing possible gonorrhoea treatment failure with ceftriaxone plus azithromycin in Austria,April 2022

We describe a gonorrhoea case with ceftriaxone plus high-level azithromycin resistance. In April 2022, an Austrian heterosexual male was diagnosed with gonorrhoea after sexual intercourse with a female sex worker in Cambodia. Recommended treatment with ceftriaxone (1 g) plus azithromycin (1.5 g) possibly failed. Worryingly, this is the second strain in an Asian Neisseria gonorrhoeae genomic sublineage including high-level azithromycin-resistant strains that developed ceftriaxone resistance by acquisition of mosaic penA-60.001. Enhanced resistance surveillance and actions are imperative to prevent spread.     

Underreporting of Energy Intake Increases over Pregnancy: An Intensive Longitudinal Study of Women with Overweight and Obesity

(1) Background: Energy intake (EI) underreporting is a widespread problem of great relevance to public health, yet is poorly described among pregnant women. This study aimed to describe and predict error in self-reported EI across pregnancy among women with overweight or obesity. (2) Methods: Participants were from the Healthy Mom Zone study, an adaptive intervention to regulate gestational weight gain (GWG) tested in a feasibility RCT and followed women (n = 21) with body mass index (BMI) ≥25 from 8–12 weeks to ~36 weeks gestation. Mobile health technology was used to measure daily weight (Wi-Fi Smart Scale), physical activity (activity monitor), and self-reported EI (MyFitnessPal App). Estimated EI was back-calculated daily from measured weight and physical activity data. Associations between underreporting and gestational age, demographics, pre-pregnancy BMI, GWG, perceived stress, and eating behaviors were tested. (3) Results: On average, women were 30.7 years old and primiparous (62%); reporting error was −38% ± 26 (range: −134% (underreporting) to 97% (overreporting)), representing an ~1134 kcal daily underestimation of EI (1404 observations). Estimated (back-calculated), but not self-reported, EI increased across gestation (p < 0.0001). Higher pre-pregnancy BMI (p = 0.01) and weekly GWG (p = 0.0007) was associated with greater underreporting. Underreporting was lower when participants reported higher stress (p = 0.02) and emotional eating (p < 0.0001) compared with their own average. (4) Conclusions: These findings suggest systemic underreporting in pregnant women with elevated BMI using a popular mobile app to monitor diet. Advances in technology that allow estimation of EI from weight and physical activity data may provide more accurate dietary self-monitoring during pregnancy.     

SOLEIL: single-objective lens inclined light sheet localization microscopy

High-NA light sheet illumination can improve the resolution of single-molecule localization microscopy (SMLM) by reducing the background fluorescence. These approaches currently require custom-made sample holders or additional specialized objectives, which makes the sample mounting or the optical system complex and therefore reduces the usability of these approaches. Here, we developed a single-objective lens-inclined light sheet microscope (SOLEIL) that is capable of 2D and 3D SMLM in thick samples. SOLEIL combines oblique illumination with point spread function PSF engineering to enable dSTORM imaging in a wide variety of samples. SOLEIL is compatible with standard sample holders and off-the-shelve optics and standard high NA objectives. To accomplish optimal optical sectioning we show that there is an ideal oblique angle and sheet thickness. Furthermore, to show what optical sectioning delivers for SMLM we benchmark SOLEIL against widefield and HILO microscopy with several biological samples. SOLEIL delivers in 15 μm thick Caco2-BBE cells a 374% higher intensity to background ratio and a 54% improvement in the estimated CRLB compared to widefield illumination, and a 184% higher intensity to background ratio and a 20% improvement in the estimated CRLB compared to HILO illumination.     

Integration of Hot Isostatic Pressing and Heat Treatment for Advanced Modified γ-TiAl TNM Alloys

The conventional processing route of TNM (Ti-Nb-Mo) alloys combines casting and Hot Isostatic Pressing (HIP) followed by forging and multiple heat treatments to establish optimum properties. This is a time-consuming and costly process. In this study we present an advanced alternative TNM alloy processing route combining HIP and heat treatments into a single process, which we refer to as IHT (integrated HIP heat treatment), applied to a modified TNM alloy with 1.5B. A Quintus HIP lab unit with a quenching module was used, achieving fast and controlled cooling, which differs from the slow cooling rates of conventional HIP units. A Ti-42.5Al-3.5Nb-1Mo-1.5B (at.%) was subjected to an integrated two HIP steps at 200 MPa, one at 1250 °C for 3 h and another at 1260 °C for 1 h, both under a protective Ar atmosphere and followed by cooling at 30 K/min down to room temperature. The results were compared against the Ti-43.5Al-3.5Nb-1Mo-0.8B (at.%) thermomechanically processed in a conventional way. Applying IHT processing to the 1.5B alloy does indeed achieve good creep strength, and the secondary creep rate of the IHT processed materials is similar to that of conventionally forged TNM alloys. Thus, the proposed advanced IHT processing route could manufacture more cost-effective TiAl components.