Automated Electrokinetic Stretcher for Manipulating Nanomaterials

In this work, we present an automated platform for trapping and stretching individual micro- and nanoscale objects in solution using electrokinetic forces. The platform can trap objects at the stagnation point of a planar elongational electrokinetic field for long time scales, as demonstrated by the trapping of ~100 nanometer polystyrene beads and DNA molecules for minutes, with a standard deviation in displacement from the trap center < 1 micrometer. This capability enables the stretching of deformable nanoscale objects in a high-throughput fashion, as illustrated by the stretching of more than 400 DNA molecules within ~4 hours. The flexibility of the electrokinetic stretcher opens up numerous possibilities for contact-free manipulation, with size-based sorting of DNA molecules performed as an example. The platform described provides an automated, high-throughput method to track and manipulate objects for real-time studies of micro- and nanoscale systems.Comment: 9 pages, 7 figure

The impact of source establishment & negative eWOM on brand loyalty.

The purpose of this study aims to establish a counter-intuitive proposition which contravenes the popular notion that consumers tend to perceive a more established source to be more trustworthy. More specifically, this study purports that when exposed to a negatively written electronic word-of-mouth (eWOM) on a chosen brand, the impact on brand loyalty is greater for the less established source (Experiment group) as compared to the more established source (Control group). To do so, a paired sampled t-test was employed to generate the means and significance level for the survey results. In the survey, a group of 71 college students were randomly divided into the Control and Experiment group. The Control group is given the more established source as its stimulus, while the Experiment group is given the less established source. Both sources contain the same piece of negative eWOM gathered from various online mediums. The findings from this study indicate and support our hypothesis; thereby establishing that the less established source which carries a negative eWOM article has effect a greater impact on the respondents’ brand loyalty towards the chosen brand. This result has exhibited the counter-intuitiveness and contradicts what used to be a popular belief.BUSINES

Automated electrokinetic stretcher for manipulating nanomaterials

In this work, we present an automated platform for trapping and stretching individual micro- and nanoscale objects in solution using electrokinetic forces. The platform can trap objects at the stagnation point of a planar elongational electrokinetic field for long time scales, as demonstrated by the trapping of <100 nm polystyrene beads and DNA molecules for minutes, with a standard deviation in displacement from the trap center <1 μm. This capability enables the stretching of deformable nanoscale objects in a high-throughput fashion, as illustrated by the stretching of more than 400 DNA molecules within ∼4 hours. The flexibility of the electrokinetic stretcher opens up numerous possibilities for complex manipulation, with sequential stretching of a molecule at different voltages and multiple stretch-relaxation cycles of the same molecule as examples. The platform described provides an automated, high-throughput method to track and manipulate objects for real-time studies of micro- and nanoscale systems.Agency for Science, Technology and Research (A*STAR)National Research Foundation (NRF)The authors acknowledge funding from the Accelerated Materials Development for Manufacturing Program via the AME Programmatic Fund by the Agency for Science, Technology and Research (A*STAR) under Grant No. A1898b0043 and Career Development Fund by A*STAR under Grant No. C222812024. K. H. also acknowledges funding from the NRF Fellowship NRF-NRFF13-2021-0011

Assessment of acute kidney injury risk using a machine-learning guided generalized structural equation model: a cohort study

10.1186/s12882-021-02238-9BMC Nephrology2216

Employment of a high throughput functional assay to define the critical factors that influence vaccine induced cross-variant neutralizing antibodies for SARS-CoV-2

10.1038/s41598-023-49231-wSCIENTIFIC REPORTS13

Employment of a high throughput functional assay to define the critical factors that influence vaccine induced cross-variant neutralizing antibodies for SARS-CoV-2

Acknowledgements: This work was supported by the Biomedical Research Council (BMRC), A*CRUSE (Vaccine monitoring project), the A*ccelerate GAP-funded project (ACCL/19-GAP064-R20H-H) from Agency of Science, Technology and Research (A*STAR), Singapore National Medical Research Council COVID-19 Research Fund (COVID19RF-001; COVID19RF-007; COVID19RF-0008; COVID19RF-060) and A*STAR COVID-19 Research funding (H/20/04/g1/006). This study is funded by the Singapore National Medical Research Council (R-571-000-081-213, R-711-000-058-598), Ministry of Health (R-571-000-093-114), National University of Singapore (R-571-000-081-213), and the Singapore-HUJ Alliance for Research and Enterprise (R-571-002-012-592). We thank Protein Production Platform of Nanyang Technological University for their help in making the nucleocapsid expression constructs and small-scale protein expression tests. We thank Assoc Prof. Tan Yee Joo, Department of Microbiology and Immunology, Yong Loo Lin, School of Medicine, National University of Singapore (NUS) for the ACE2 stably expressing CHO cells and plasmid encoding SARS-CoV-2 S protein for the pseudotyped lentiviral production. We thank Ms. Lang Si Min and Ms. Tan Siang Ling Isabelle for helping with the performance of experiments.AbstractThe scale and duration of neutralizing antibody responses targeting SARS-CoV-2 viral variants represents a critically important serological parameter that predicts protective immunity for COVID-19. In this study, we describe the development and employment of a new functional assay that measures neutralizing antibodies for SARS-CoV-2 and present longitudinal data illustrating the impact of age, sex and comorbidities on the kinetics and strength of vaccine-induced antibody responses for key variants in an Asian volunteer cohort. We also present an accurate quantitation of serological responses for SARS-CoV-2 that exploits a unique set of in-house, recombinant human monoclonal antibodies targeting the viral Spike and nucleocapsid proteins and demonstrate a reduction in neutralizing antibody titres across all groups 6 months post-vaccination. We also observe a marked reduction in the serological binding activity and neutralizing responses targeting recently newly emerged Omicron variants including XBB 1.5 and highlight a significant increase in cross-protective neutralizing antibody responses following a third dose (boost) of vaccine. These data illustrate how key virological factors such as immune escape mutations combined with host demographic factors such as age and sex of the vaccinated individual influence the strength and duration of cross-protective serological immunity for COVID-19.</jats:p

Lower vaccine-acquired immunity in the elderly population following two-dose BNT162b2 vaccination is alleviated by a third vaccine dose

Understanding the impact of age on vaccinations is essential for the design and delivery of vaccines against SARS-CoV-2. Here, we present findings from a comprehensive analysis of multiple compartments of the memory immune response in 312 individuals vaccinated with the BNT162b2 SARS-CoV-2 mRNA vaccine. Two vaccine doses induce high antibody and T cell responses in most individuals. However, antibody recognition of the Spike protein of the Delta and Omicron variants is less efficient than that of the ancestral Wuhan strain. Age-stratified analyses identify a group of low antibody responders where individuals ≥60 years are overrepresented. Waning of the antibody and cellular responses is observed in 30% of the vaccinees after 6 months. However, age does not influence the waning of these responses. Taken together, while individuals ≥60 years old take longer to acquire vaccine-induced immunity, they develop more sustained acquired immunity at 6 months post-vaccination. A third dose strongly boosts the low antibody responses in the older individuals against the ancestral Wuhan strain, Delta and Omicron variants