Multiple particle tracking microrheology (MPT) is a passive microrheological technique that measures the Brownian motion of probe particles embedded in a sample to characterize material rheological properties. MPT is a powerful tool that quantifies material rheology in the low moduli range while requiring only small sample volumes and relatively simple data acquisition using video microscopy. MPT quantitatively characterizes spatiotemporal rheological properties and is particularly well suited for the investigation of evolving materials with complex microenvironments. MPT has expanded the study of a variety of materials including biofilms, colloidal gels, hydrogels, stimuli-responsive materials, and cell-laden biomaterials. The aim of this Tutorial is to summarize the fundamentals, illustrate the versatility, and highlight recent advances in MPT. In each application, we will highlight how MPT is uniquely positioned to gather rheological properties, which would be difficult, if not impossible, to attain with other rheological characterization techniques and highlight how MPT can be used to supplement other measurement techniques. This Tutorial should provide researchers with the fundamental basis and skills needed to use MPT and develop new MPT techniques to characterize materials for their unique applications.
For the interlayer dielectric in microelectronics, light element compounds are preferably accepted due to less electronic polarization. Here, the nontrivial dielectric nature of the Sb 4 O 6 cage-molecular crystal, known as α-antimony trioxide (α-Sb 2 O 3 ), is reported. The gas-phase synthesized α-Sb 2 O 3 nanoflakes are of high crystal quality, from which the abnormal local admittance responses were revealed by scanning microwave impedance microscopy (sMIM). The remarkably low dielectric constant (k), 2.0∼2.5, is corroborated by the analysis of the thickness-dependent sMIM-capacitance signal. In light of the theoretical calculations, the ultralow molecular density and the significantly suppressed ionic polarization are both crucial to the highly reduced k. Combining with the excellent optical band gap, thermal stability, and breakdown strength, α-Sb 2 O 3 is a promising low k dielectric. KEYWORDS: low k, α-Sb 2 O 3 , Sb 4 O 6 cage, molecular crystal, interlayer dielectric
A total of 52 novel 1,2,4-triazole
thioether and thiazolo[3,2-b]-1,2,4-triazole derivatives
bearing the 6-fluoroquinazolinyl
moiety were designed, synthesized, and evaluated as antimicrobial
agents in agriculture based on the molecular hybridization strategy.
Among them, molecular structures of compounds 5g and 6m were further confirmed via the single-crystal X-ray diffraction
method. The bioassay results indicated that some of the target compounds
possessed excellent antibacterial activities in vitro against the
pathogen Xanthomonas oryzae pv. oryzae
(Xoo). For example, compound 6u demonstrated
a strong anti-Xoo efficacy with an EC50 value of 18.8 μg/mL, nearly 5-fold more active than that of
the commercialized bismerthiazol (EC50 = 93.6 μg/mL).
Moreover, the anti-Xoo mechanistic studies revealed
that compound 6u exerted its antibacterial effects by
increasing the permeability of bacterial membrane, reducing the content
of extracellular polysaccharide, and inducing morphological changes
of bacterial cells. Importantly, in vivo assays revealed its pronounced
protection and curative effects against rice bacterial blight, proving
its potential as a promising bactericide candidate for controlling Xoo. Moreover, compound 6u had a good pesticide-likeness
based on Tice’s criteria. More interestingly, compound 6u with high anti-Xoo activity also demonstrated
a potent inhibitory effect of 80.8% against the fungus Rhizoctonia solani at 50 μg/mL, comparable
to that of the commercialized chlorothalonil (85.9%). Overall, the
current study will provide useful guidance for the rational design
of more efficient agricultural antimicrobial agents using the thiazolo[3,2-b]-1,2,4-triazole derivatives bearing the 6-fluoroquinazolinyl
moiety as lead compounds.
A total of 29 novel quinazoline-2-aminothiazole hybrids
containing
a 4-piperidinylamide linker were designed, synthesized, and evaluated
for their anti-microbial properties against phytopathogenic fungi
and bacteria of agricultural importance. The anti-fungal assays indicated
that some of the target compounds exhibited excellent inhibitory effects
in vitro against Rhizoctonia solani. For example, 11 compounds within this series (including 4a, 4g, 4h, 4j, 4o, 4s, 4t, 4u, 4v, 4y, and 4b′) were found to possess
EC50 values (effective concentration for 50% activity)
ranging from 0.42 to 2.05 μg/mL against this pathogen. In particular,
compound 4y with a 2-chloro-6-fluorophenyl substituent
displayed a potent anti-R. solani efficacy
with EC50 = 0.42 μg/mL, nearly threefold more effective
than the commercialized fungicide Chlorothalonil (EC50 =
1.20 μg/mL) and also slightly superior to the other fungicide
Carbendazim (EC50 = 0.53 μg/mL). Moreover, compound 4y could efficiently inhibit the growth of R. solani in vivo on the potted rice plants, displaying an impressive protection
efficacy of 82.3% at 200 μg/mL, better than those of the fungicides
Carbendazim (69.8%) and Chlorothalonil (48.9%). Finally, the mechanistic
studies showed that compound 4y exerted its anti-fungal
effects by altering the mycelial morphology, increasing the cell membrane
permeability, and destroying the cell membrane integrity. On the other
hand, some compounds demonstrated good anti-bacterial effects in vitro
against Xanthomonas oryzae pv. oryzae (Xoo). Overall, the presented results
implied that 4-piperidinylamide-bridged quinazoline-2-aminothiazole
hybrids held the promise of acting as lead compounds for developing
more efficient fungicides to control R. solani.
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