16 research outputs found
Research on the simulation of factors influencing maximum firing distance of acoustic homing torpedo
In the torpedo attack, the appropriate firing distance is the key to ensure the torpedo hit the target, it’s necessary to ensure the firing distance used is within the maximum firing distance. Therefore, under the premise of known firing conditions, it’s necessary to determine the maximum firing distance and be familiar with the factors that affect the value and the influencing rules of each factor. Based on the firing model of the acoustic homing torpedo, the expression of the maximum firing distance is established, and the main factors affecting the value are obtained. Through the simulation, the influence factors are analyzed quantitatively, and the rule of their influence on the maximum firing distance is founded out. This research can provide the necessary reference for the commanding officer in battle, in order to make full use of the research results and improve the hit probability of the acoustic homing torpedo
Facile Fabrication of Lubricant-Infused Wrinkling Surface for Preventing Thrombus Formation and Infection
Low Temperature (15 °C) Reduces Bacterial Diversity and Prolongs the Preservation Time of Volvariella volvacea
Straw mushroom (Volvariella volvacea) is the most commonly cultivated edible fungus in the world, but the challenges associated with the preservation have limited its marketability. Microbiology, especially bacteria, play a key role in the deterioration of food, this study aimed to reveal the succession of the bacterial community on the surfaces of V. volvacea fruit bodies under different temperature conditions. We amplified 16S rRNA genes of V4 regions, obtained the bacterial species information by using high-throughput sequencing technology, and analyzed the effects of environmental temperature and preservation time on bacterial communities. The relative abundances of Firmicutes, Bacilli, and Bacillales increased significantly when straw mushrooms began to rot. Furthermore, the relative abundances of Paenibacillus, Lysinibacillus and Solibacillus, which belong to Bacillales, increased with the decay of straw mushroom. The Shannon and Simpson indices of V. volvacea stored at 30 °C were significantly higher than those of V. volvacea stored at 15 °C, which indicates that a high temperature contributes to the improvement in the species diversity. According to the linear discriminant analysis (LDA) effect size (LEfSe) results, the number of biomarkers in the 30 °C group (32, 42.11%) was significantly higher than that in the 15 °C group (17, 22.37%), indicating that a high temperature has a clustering effect on some bacterial communities. A Spearman correlation analysis showed that Pseudomonas, Stenotrophomonas and Solibacillus promoted the decay of straw mushroom. In conclusion, a high temperature increases the bacterial diversity on the straw mushroom surfaces and has a clustering effect on the bacterial communities. The bacterial community consisting of Firmicutes, Bacilli, Bacillales, Paenibacillus, Lysinibacillus, Pseudomonas, Stenotrophomonas and Solibacillus could promote the decay of straw mushroom, so new preservation materials research can focus on inhibiting anaerobic and decay-causing bacteria to prolong preservation time
Facile Fabrication of Lubricant-Infused Wrinkling Surface for Preventing Thrombus Formation and Infection
Despite
the advanced modern biotechniques, thrombosis and bacterial infection
of biomedical devices remain common complications that are associated
with morbidity and mortality. Most antifouling surfaces are in solid
form and cannot simultaneously fulfill the requirements for antithrombosis
and antibacterial efficacy. In this work, we present a facile strategy
to fabricate a slippery surface. This surface is created by combining
photografting polymerization with osmotically driven wrinkling that
can generate a coarse morphology, and followed by infusing with fluorocarbon
liquid. The lubricant-infused wrinkling slippery surface can greatly
prevent protein attachment, reduce platelet adhesion, and suppress
thrombus formation in vitro. Furthermore, <i>E. coli</i> and <i>S. aureus</i> attachment on the slippery surfaces
is reduced by ∼98.8% and ∼96.9% after 24 h incubation,
relative to poly(styrene-<i>b</i>-isobutylene-<i>b</i>-styrene) (SIBS) references. This slippery surface is biocompatible
and has no toxicity to L929 cells. This surface-coating strategy that
effectively reduces thrombosis and the incidence of infection will
greatly decrease healthcare costs
Nuclease-Functionalized Poly(Styrene‑<i>b</i>‑isobutylene‑<i>b</i>‑styrene) Surface with Anti-Infection and Tissue Integration Bifunctions
Hydrophobic thermoplastic elastomers,
e.g., poly(styrene-<i>b</i>-isobutylene-<i>b</i>-styrene) (SIBS), have found
various in vivo biomedical applications. It has long been recognized
that biomaterials can be adversely affected by bacterial contamination
and clinical infection. However, inhibiting bacterial colonization
while simultaneously preserving or enhancing tissue-cell/material
interactions is a great challenge. Herein, SIBS substrates were functionalized
with nucleases under mild conditions, through polycarboxylate grafts
as intermediate. It was demonstrated that the nuclease-modified SIBS
could effectively prevent bacterial adhesion and biofilm formation.
Cell adhesion assays confirmed that nuclease coatings generally had
no negative effects on L929 cell adhesion, compared with the virgin
SIBS reference. Therefore, the as-reported nuclease coating may present
a promising approach to inhibit bacterial infection, while preserving
tissue-cell integration on polymeric biomaterials
Nonleaching Bacteria-Responsive Antibacterial Surface Based on a Unique Hierarchical Architecture
Bacteria-responsive
surfaces popularly exert their smart antibacterial activities by bacteria-triggered
delivery of antibacterial agents; however, the antibacterial agents
should be additionally reloaded for the renewal of these surfaces.
Herein, a reversible, nonleaching bacteria-responsive antibacterial
surface is prepared by taking advantage of a hierarchical polymer
brush architecture. In this hierarchical surface, a pH-responsive
poly(methacrylic acid) (PMAA) outer layer serves as an actuator modulating
the surface behavior on demand, while antimicrobial peptides (AMP)
are covalently immobilized on the inner layer. The PMAA hydration
layer renders the hierarchical surface resistant to initial bacterial
attachment and biocompatible under physiological conditions. When
bacteria colonize the surface, the bacteria-triggered acidification
allows the outermost PMAA chains to collapse, therefore exposing the
underlying bactericidal AMP to on-demand kill bacteria. In addition,
the dead bacteria can be released once the PMAA chains resume their
hydrophilicity because of the environmental pH increase. The functionality
of the nonleaching surface is reversible without additional reloading
of the antibacterial agents. This approach provides a new methodology
for the development of smart surfaces in a variety of practical biomedical
applications
Hierarchical Polymer Brushes with Dominant Antibacterial Mechanisms Switching from Bactericidal to Bacteria Repellent
Although
polycationic surfaces have high antimicrobial efficacies,
they suffer from high toxicity to mammalian cells and severe surface
accumulation of dead bacteria. For the first time, we propose a surface-initiated
photoiniferter-mediated polymerization (SI-PIMP) strategy of constructing
a “cleaning” zwitterionic outer layer on a polycationic
bactericidal background layer to physically hinder the availability
of polycationic moieties for mammalian cells in aqueous service. In
dry conditions, the polycationic layer exerts the contact-active bactericidal
property toward the adherent bacteria, as the zwitterionic layer collapses.
In aqueous environment, the zwitterionic layer forms a hydration layer
to significantly inhibit the attachment of planktonic bacteria and
the accumulation of dead bacteria, while the polycationic layer kills
bacteria occasionally deposited on the surface, thus preserving the
antibacterial capability for a long period. More importantly, the
zwitterionic hydrated layer protects the mammalian cells from toxicity
induced by the bactericidal background layer, and therefore hierarchical
antibacterial surfaces present much better biocompatibility than that
of the naked cationic references. The dominant antibacterial mechanism
of the hierarchical surfaces can switch from the bactericidal efficacy
in dry storage to the bacteria repellent capability in aqueous service,
showing great advantages in the infection-resistant applications
Fabricating a Cycloolefin Polymer Immunoassay Platform with a Dual-Function Polymer Brush via a Surface-Initiated Photoiniferter-Mediated Polymerization Strategy
The development of technologies for
a biomedical detection platform is critical to meet the global challenges
of various disease diagnoses. In this study, an inert cycloolefin
polymer (COP) support was modified with two-layer polymer brushes
possessing dual functions, i.e., a low fouling poly[poly(ethylene
glycol) methacrylate] [p(PEGMA)] bottom layer and a poly(acrylic acid)
(PAA) upper layer for antibody loading, via a surface-initiated photoiniferter-mediated
polymerization strategy for fluorescence-based immunoassay. It was
demonstrated through a confocal laser scanner that, for the as-prepared
COP-<i>g</i>-PEG-<i>b</i>-PAA-IgG supports, nonspecific
protein adsorption was suppressed, and the resistance to nonspecific
protein interference on antigen recognition was significantly improved,
relative to the COP-<i>g</i>-PAA-IgG references. This strategy
for surface modification of a polymeric platform is also applicable
to the fabrication of other biosensors
Temperature-Responsive Hierarchical Polymer Brushes Switching from Bactericidal to Cell Repellency
Unlike conventional
poly(<i>N</i>-isopropylacrylamide) (PNIPAM)-based surfaces
switching from bactericidal activity to bacterial repellency upon
decreasing temperature, we developed a hierarchical polymer architecture,
which could maintain bactericidal activities at room temperature while
presenting bacterial repellency at physiological temperature. In this
architecture, a thermoresponsive bactericidal upper layer consisting
of PNIPAM-based copolymer and vancomycin (Van) moieties was built
on an antifouling poly(sulfobetaine methacrylate) (PSBMA) bottom layer
via sequential surface-initiated photoiniferter-mediated polymerization.
At room temperature below the lower critical solution temperature
(LCST), the PNIPAM-based upper layer was stretchable, facilitating
contact killing of bacteria by Van. At physiological temperature (above
the LCST), the PNIPAM-based layer collapsed, thus leading to the burial
of Van and exposure of bottom PSBMA brushes, finally displaying notable
performances in bacterial inhibition, dead bacteria detachment, and
biocompatibility, simultaneously. Our strategy provides a novel pathway
in the rational design of temperature-sensitive switchable surfaces,
which shows great advantages in the real-world infection-resistant
applications