Experimental Study on the Effect of Locally Convergent Configurations on the Flow Pattern in PMMA Microchips

The geometries of micro-channel play a key role in forming of digital droplets, and can be real-time or effective controlling methodologies. Local convergence regions are designed in the rectangular cross-section channels on PMMA microchips, in which two-phase coaxial jets are introduced by inserting a syringe needle. The two-phase flow (lubricating oil (continuous phase, flow rate Q c)/deionized water (dispersed phase, flow rate Q d)) is considered. Two geometric control variables, the relative position (needle displacement x) and tapering characteristics (convergence angle α), are naturally adopted to discribe such geometry configurations. The micro-flow under the change of these two parameters is mainly studied in this paper. Four kinds of characteristic flow patterns, namely, sausages, slug, dripping and jetting, are found in the experiment, and their occurring parameters and developing dynamic characteristics are discussed. The experiment shows that the increase of inner needle displacement x can produce higher frequency and finer droplets, which is in consistent with our previous results obtained in round tube experiments and simulations. While increasing the convergence angle α, contrarily, takes opposite effects.

Synthesis of Nanofiber Polyvinyl Alcohol (PVA) with Electrospinning Method

PVA nanofibers are PVA solution-based nanofibers. PVA solution is a synthetic polymer that is non-toxic, soluble in air, and has excellent thermal, gas permeability, and chemical resistance qualities. Nanofibers were synthesized using PVA (Polyvinyl alcohol) solutions at concentrations of 8%, 10%, and 12%. The electrospinning method is used in this investigation, with input voltages of 17 kV and 20 kV, needle distances of 7 cm, 10 cm, and 15 cm from the collector, and a flow rate of 5 ml/hour for each concentration. An optical microscope was used to examine the nanofiber synthesis results in order to assess the morphology and diameter of the fiber. PVA nanofiber with the best fiber from electrospinning has a diameter of 1.06 μm and homogeneous fiber without beads is a synthesized nanofiber with a variation of 10% PVA solution concentration, 15 cm distance from the syringe needle to drum collector, and 20 kV voltage.

In-vitro assessment of release of silicone oil droplets with the use of variety of syringes and needles used in intravitreal injections

Purpose: To assess the variability of silicone oil (SO) particles released across syringes from the same lot and the role of different needle gauges. Materials and methods: Four syringe models and six needle models were assessed for SO release. About 50 microliters of a buffer solution were loaded into the syringe, needle or syringe/needle setup. The data were analyzed by imaging flow cytometry with fluorescently labeling for SO. Results: All syringe models had a high coefficient of variation in SO release across syringes from the same lot. The amount of SO was significantly greater in the syringe when the needle was attached. SO particles with the BD 30G needle attached to the syringe were statistically greater than the 27G counterpart ( p = 0.005). None of the other comparisons was statistically different. Finally, the number of SO particles was higher in the syringe/needle setup than in needles only ( p = 0.0024). Conclusion: We found a high variability in SO content across syringes from the same lot. Additionally, there was no clear association between needle gauge and the number of SO particles, as well as their coefficient of variation. Finally, the needles accounted for a small number of SO particles in comparison to the combined syringe-needle setup.

Ingested foreign body associated with tooth extraction: Report of a case

Aspiration and ingestion of teeth, dental prostheses and other foreign bodies in maxillofacial injuries is a known complication necessitating prompt recognition and early treatment to minimize potentially serious and, sometimes, even fatal consequences. However, an aspirated or ingested foreign body does not always produce untoward affects and may be overlooked when no acute respiratory distress is evident or multiple life-threatening injuries are present. Here, we report a case in its presentation; the patient underwent extraction of a left upper third molar. After extraction, alveolar irrigation was performed with syringe, needle and sterile saline. the patient ingested the irrigation needle. The patient was properly referred to the emergency room of the hospital of Santa Fé do Sul and referred to the care of the general surgeon, who removed the needle with endoscopic removal under sedation. Clinicians must be aware that the instrument used for dental treatment are mostly small and there is a risk of these falling into the oropharynx and being swallowed or inhaled. The paper also emphasizes that attention to the potentially serious consequences and to offer guidance on management.

Assessment of immunogenicity and protective efficacy of ZyCoV-D DNA vaccine candidates in Rhesus macaques against SARS-CoV-2 infection

Vaccines remain the key protective measure to achieve herd immunity to control the disease burden and stop COVID-19 pandemic. We have developed and assessed the immunogenicity and protective efficacy of two formulations (1mg and 2mg) of ZyCoV-D (a plasmid DNA based vaccine candidates) administered through Needle Free Injection System (NFIS) and syringe-needle (intradermal) in rhesus macaques with three dose vaccine regimens. The vaccine candidate 2mg dose administered using Needle Free Injection System (NFIS) elicited a significant immune response with development of SARS-CoV-2 S1 spike region specific IgG and neutralizing antibody (NAb) titers during the immunization phase and significant enhancement in the levels after the virus challenge. In 2 mg NFIS group the IgG and NAb titers were maintained and showed gradual rise during the immunization period (15 weeks) and till 2 weeks after the virus challenge. It also conferred better protection to macaques evident by the viral clearance from nasal swab, throat swab and bronchoalveolar lavage fluid specimens in comparison with macaques from other immunized groups. In contrast, the animals from placebo group developed high levels of viremia and lung disease following the virus challenge. Besides this, the vaccine candidate also induced increase lymphocyte proliferation and cytokines response (IL-6, IL-5).The administration of the vaccine candidate with NFIS generated a better immunogenicity response in comparison to syringe-needle (intradermal route). The study demonstrated immunogenicity and protective efficacy of the vaccine candidate, ZyCoV-D in rhesus macaques.