Nanoparticle Assembling Dynamics Induced by Pulsed Optical Force

Femtosecond (fs) laser trapping dynamics is summarized for silica, hydrophobically modified silica, and polystyrene nanoparticles (NPs) in aqueous solution, highlighting their distinct optical trapping dynamics under CW laser. Mutually repulsive silica nanoparticles are tightly confined under fs laser compared to CW laser trapping and, upon increasing laser power, they are ejected from the focus as an assembly. Hydrophobically modified silica and polystyrene (PS) NPs are sequentially ejected just like a stream or ablated, giving bubbles. The ejection and bubbling take place with the direction perpendicular to laser polarization and its direction is randomly switched from one to the other. These characteristic features are interpreted from the viewpoint of single assembly formation of NPs at an asymmetric position in the optical potential. Temporal change in optical forces map is prepared for a single PS NP by calculating scattering, gradient, and temporal forces. The relative contribution of the forces changes with the volume increase of the assembly and, when the pushing force along the trapping pulse propagation overcome the gradient in the focal plane, the assembly undergoes the ejection. Further fs multiphoton absorption is induced for the larger assembly leading to bubble generation. The assembling, ejection, and bubbling dynamics of NPs are characteristic features of pulsed optical force and are considered as a new platform for developing new material fabrication method.

Design, synthesis and antiamoebic activity of dysprosium-based nanoparticles using contact lenses as carriers against Acanthamoeba sp

PURPOSE

Contact lenses have direct contact with the corneal surface and can induce sight-threatening infection of the cornea known as Acanthamoeba keratitis. The objective of this study was to evaluate the dysprosium-based nanoparticles (Dy-based NPs), namely Fe₃ O₄ -PEG-Dy₂ O₃ nanocomposites and Dy(OH)₃ nanorods, as an active component against Acanthamoeba sp., as well as the possibility of their loading onto contact lenses as the drug administering vehicle to treat Acanthamoeba keratitis (AK).

METHODS

The Dy-based NPs were synthesized, and they were loaded onto commercial contact lenses. The loading content of the NPs and their release kinetics was determined based on the absorbance of their colloidal solution before and after soaking the contact lenses. The cytotoxicity of the NPs was evaluated, and the IC₅₀ values of their antiamoebic activity against Acanthamoeba sp. were determined by MTT colorimetric assay, followed by observation on the morphological changes by using light microscopy. The mechanism of action of the Dy-based NPs against Acanthamoeba sp. was evaluated by DNA laddering assays.

RESULTS

The loading efficiencies of the Dy-based NPs onto the contact lens were in the range of 30.6-36.1% with respect to their initial concentration (0.5 mg ml^-1 ). The Dy NPs were released with the flux approximately 5.5-11 μg cm^-2  hr^-1 , and the release was completed within 10 hr. The emission of the NPs consistently showed a peak at 575 nm due to Dy³⁺ ion, offering the possible monitoring and tracking of the NPs. The SEM images indicated the NPs are aggregated on the surface of the contact lenses. The DNA ladder assay suggested that the cells underwent DNA fragmentation, and the cell death was due most probably to necrosis, rather than apoptosis. The cytotoxicity assay of Acanthamoeba sp. suggested that Fe₃ O₄ -PEG, Fe₃ O₄ -PEG-Dy₂ O₃ , Dy(NO₃ )₃ .6H₂ O and Dy(OH)₃ NPs have an antiamoebic activity with the IC₅₀ value being 4.5, 5.0, 9.5 and 22.5 μg ml^-1 , respectively.

CONCLUSIONS

Overall findings in this study suggested that the Dy-based NPs can be considered as active antiamoebic agents and possess the potential as drugs against Acanthamoeba sp. The NPs could be loaded onto the contact lenses; thus, they can be potentially utilized to treat Acanthamoeba keratitis (AK).

Insight into the adsorption kinetics, mechanism, and thermodynamics of methylene blue from aqueous solution onto pectin-alginate-titania composite microparticles

Abstract

In the present study, pectin-alginate-titania (PAT) composites were synthesized and the adsorptive removal behavior of methylene blue (MB) from aqueous solution, as a model of synthetic organic effluents, onto the prepared PAT composites were investigated by monitoring the effect of contact time, initial MB concentration, and temperature. The adsorption isotherm data were fitted well with the Freundlich isotherm model, suggesting the surface heterogeneity of the PAT composites and that the MB adsorption occurred on the active sites on multilayer surface of the composites. The adsorption kinetics of MB was demonstrated to be pseudo-second order, governed by two intraparticle diffusion rates, and the adsorption process was exothermic, spontaneous, and more disorder. The Langmuir isotherm model suggested that the maximum adsorption capacity of MB on the PAT composites was in the range of 435–637 mg g–1. In general, it increased with the TiO2 NPs content in the PAT composites, due most likely to the increase in surface area exposing more functional groups of the pectin and alginate to interact with the synthetic dye. The adsorptive removal of MB by the PAT composites was found to be more efficient compared with many other reported adsorbents, such as graphene oxide hybrids, pectin microspheres, magnetite-silica-pectin composites, clay-based materials, chemically treated minerals, and agricultural waste. The present study therefore demonstrated for the first time that PAT composites are not only promising to be utilized as an adsorbent in wastewater treatment, but also provide an insight into the adsorption mechanism of the synthetic dyes onto the biopolymers-titania composites.

Graphic abstract

Insight into the adsorption kinetics, mechanism, and thermodynamics of methylene blue from aqueous solution onto pectin-alginate-titania composite microparticles.

Clinical management protocol of an acute contagious bovine pleuropnuemonia in a 6- year-old Bunaji cow in Sakaru village of Soba local government area, Kaduna state, Nigeria

The test and slaughter policy of the federal government of Nigeria on contagious bovine pleuropneumonia (CBPP) in cattle is no longer feasible because it lacked the political will as a result, farmers tend to treat their cattle of the disease most which has been ineffective. herefore, the quest for a supportive clinical management protocol for CBPP in cattle aimed at enabling the cow regain its body condition in order to allow the farmer sell the cow for slaughter at a profit was the aim of this case report. A 6-year-old Bunaji cow weighing 350kg with history of not feeding well, lagging behind during grazing, difficulty in breathing, intermittent cough and bloat was presented. Physical examination was carried out and differential diagnoses which included contagious bovine pleuropneumonia, mango choke, Pasteurellosis and tuberculosis were considered. After a careful scrutiny of the differentials, a tentative diagnosis of contagious bovine pleuropneumonia which was confirmed by the Latex agglutination test (LAT) was arrived at. A supportive clinical management protocol was instituted with the sole aim of enabling the cow regain its body condition in order to allow the farmer sell the cow for slaughter at a profit. The protocol involved isolation of the cow and administration of 20% tetracycline long acting through a combination of conventional (intra-muscular) and non-conventional (intra-venous) routes of administration along with an anti-inflammatory agent and an appetite stimulant. Six days after the commencement of therapy, the observed clinical signs subsided greatly and the cow became apparently healthy. The study showed that, the protocol of administering 20%tetracycline long acting through a combination of conventional (intra-muscular) and nonconventional (intra-venous) routes along with an anti-inflammatory agent (dexamethasone) and an appetite stimulant (vit. B. complex) was effective and profitable to the farmer. The client was advised to sell the cow for slaughter after observing the 21- day withdrawal period of the drugs. 

Phytochemicals, mineral contents, antioxidants, and antimicrobial activities of propolis produced by Brunei stingless bees Geniotrigona thoracica, Heterotrigona itama, and Tetrigona binghami

The present study focused on the evaluation of phytochemical properties, essential mineral elements, and heavy metals contained in raw propolis produced by stingless bees Geniotrigona thoracica, Heterotrigona itama, and Tetrigona binghami found in the same ecological conditions and environment in Brunei Darussalam. The results indicated that propolis of the three stingless bee species mainly consisted of lipids (45.60–47.86%) and very low carbohydrate (0.17–0.48%) and protein contents (0.18–1.18%). The propolis was rich in mineral elements, thus good sources of minerals, while they contained low concentrations of all heavy metals. Propolis of the different bee species could be distinguished based on their mineral compositions. The vibrational and absorption spectra suggested that propolis contains π-conjugated aliphatic and aromatic compounds as well as aromatic acids having amine, ester, carbonyl, alkyl, and hydroxyl functional groups which might be attributed to the presence of phenolic and flavonoid compounds. The antioxidant capacity of the propolis, based on radical scavenging activity of their ethanol extract, was in line with their total phenolic content. The ethanol extract of the propolis also showed antimicrobial activities against four bacterial strains (Bacillus subtilis, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa). The propolis showed slightly higher antibacterial activity against Gram-positive (B. subtilis and S. aureus) bacteria, indicating that the antimicrobial active compounds could be associated with flavonoids, which were quantified to be approximately comparable in all the propolis.

Trends in measles cases in Bayelsa state, Nigeria: a five-year review of case-based surveillance data (2014-2018)

BACKGROUND

Measles is a vaccine preventable, highly transmissible viral infection that affects mostly children under five years. It has been ear marked for elimination and Nigeria adopted the measles elimination strategies of the World Health Organization (WHO) African region to reduce cases and deaths. This study was done to determine trends in measles cases in Bayelsa state, to describe cases in terms of person and place, identify gaps in the case-based surveillance data collection system and identify risk factors for measles infection.

METHODS

We carried out a secondary data analysis of measles case-based surveillance data for the period of January 2014 to December 2018 obtained in Microsoft Excel from the State Ministry of Health. Cases were defined according to WHO standard case definitions. We calculated frequencies, proportions, estimated odds ratios (OR), 95% confidence intervals (CI) and multivariate analysis.

RESULTS

A total of 449 cases of measles were reported. There were 245(54.6%) males and the most affected age group was 1-4 years with 288(64.1%) cases. Of all cases, 289(9.35%) were confirmed and 70 (48.27%) had received at least one dose of measles vaccine. There was an all-year transmission with increased cases in the 4th quarter of the year. Yenegoa local government area had the highest number of cases. Timeliness of specimen reaching the laboratory and the proportion of specimens received at the laboratory with results sent to the national level timely were below WHO recommended 80% respectively. Predictors of measles infection were, age less than 5 years (AOR: 0.57, 95% CI: 0.36-0.91) and residing in an urban area (AOR: 1.55, 95% CI:1.02-2.34).

CONCLUSIONS

Measles infection occurred all-year round, with children less than 5 years being more affected. Measles case-based surveillance system showed high levels of case investigation with poor data quality and poor but improving indicators. Being less than 5 years was protective of measles while living in urban areas increased risk for infection. We recommended to the state government to prioritize immunization activities in the urban centers, start campaigns by the 4th quarter and continue to support measles surveillance activities and the federal government to strengthen regional laboratory capacities.

N-[(E)-Quinolin-2-ylmethylidene]-1,2,4-triazol-4-amine hemihydrate

The title hemihydrate, C12H9N5·0.5H2O, was isolated from the condensation reaction of quinoline-2-carbaldehyde with 4-amino-4H-1,2,4-triazole. The Schiff base molecule adopts an E configuration about the C=N bond and is approximately planar, with a dihedral angle between the quinoline ring system and the 1,2,4-triazole ring of 12.2 (1)°. In the crystal, one water molecule bridges two Schiff base molecules via O—H...N hydrogen bonds. The Schiff base molecules are interconnected by π–π stacking interactions [centroid-centroid distances of 3.7486 (7) and 3.9003 (7) Å] into columns along [1\overline{1}0].

2-[1-(1,3-Dioxo-1,3-dihydro-2H-inden-2-ylidene)ethyl]hydrazinecarbothioamide

The title compound, C12H11N3O2S, was synthesized by a condensation reaction of 2-acetylindan-1,3-dione and thiosemicarbazide in ethanol in the presence of glacial acetic acid. The molecule adopts a thioketone form. The dihedral angle between the mean planes of 1H-inden-1,3(2H)-dione and hydrazinecarbothioamide units is 86.32 (7)°. Weak intramolecular N—H...O and C—H...O hydrogen bonds are observed. In the crystal, molecules are linked via pairs of weak intermolecular N—H...O hydrogen bonds, forming inversion dimers. The dimers are further linked into a three-dimensional network through N—H...S and N—H...O hydrogen bonds, and π–π interactions [centroid–centroid distances = 3.5619 (10)–3.9712 (9) Å].

Simultaneous adsorption of lanthanum and yttrium from aqueous solution by durian rind biosorbent

This paper presents the adsorption capacity of a biosorbent derived from the inner part of durian (Durio zibethinus) rinds, which are a low-cost and abundant agro-waste material. The durian rind sorbent has been successfully utilized to remove lanthanum (La) and yttrium (Y) ions from their binary aqueous solution. The effects of several adsorption parameters including contact time, pH, concentrations of La and Y, and temperature on the removal of La and Y ions were investigated. The adsorption isotherm and kinetics of the metal ions were also evaluated in detail. Both La and Y ions were efficiently adsorbed by the biosorbent with optimum adsorption capacity as high as 71 mg La and 35 mg Y per gram biosorbent, respectively. The simultaneous adsorption of La and Y ions follows Langmuir isotherm model, due to the favorable chelation and strong chemical interactions between the functional groups on the surface of the biosorbent and the metal ions. The addition of oxygen content after adsorption offers an interpretation that the rare-earth metal ions are chelated and incorporated most probably in the form of metal oxides. With such high adsorption capacity of La and Y ions, the durian rind sorbent could potentially be used to treat contaminated wastewater containing La and Y metal ions, as well as for separating and extracting rare-earth metal ions from crude minerals.

Physicochemical properties, antioxidant capacities, and metal contents of virgin coconut oil produced by wet and dry processes

Different from cooking oils which contain long-chain fatty acids, virgin coconut oil (VCO) has high medium-chain fatty acids, making it a potential functional food which can provide some health benefits. In this study, our objective is to investigate the physicochemical properties, antioxidant capacity, and metal contents of the VCO extracted through four different processing methods: chilling and centrifugation; fermentation; direct micro expelling-oven dried; and direct micro expelling-sun-dried processes. We found that the physicochemical properties, including moisture content, refractive index, viscosity, iodine value, saponification value, peroxide value, free fatty acid, and fatty acid content, of all the VCO conform to the Asian and Pacific Coconut Community (APCC) standard. All of the VCO predominantly contains lauric acid which is in the range of 48.40%-52.84% of the fatty acid content. The total phenolic content and DPPH radical-scavenging activity (IC 50) of the VCO was obtained to be in the range of 1.16-12.54 mg gallic acid equivalents (GAE)/g and 7.49-104.52 mg/ml, respectively, and the metal contents in the VCO were within the acceptable range of the recommended APCC limit. These findings ensure good quality and safety assurance of the VCO produced from the coconut grown in Brunei Darussalam through the different processing methods.

[1-(Pyrazin-2-yl)ethylidene]hydrazine: a new multitopic ligand for the design of hybrid molecular frameworks

Hydrazones and their derivatives are closely related to imine compounds and are potential antimicrobial agents. They have also found application in supramolecular chemistry as multitopic ligands to link multiple metal centres for the design of hybrid molecular frameworks. The molecule of the title compound, C₆H₈N₄, consists of an imine linkage with an N-N bond length of 1.3540 (14) Å. This asymmetric compound is nearly planar and adopts an E configuration about the azomethine C=N double bond. In the solid state, there are two intermolecular N-H...N interactions that interconnect the molecules into a two-dimensional network. The three-dimensional arrangement of the crystal packing is further stabilized by intermolecular π-π interactions interconnecting the centroids of the heterocyclic rings.

Size-Dependent Optical Properties of Grana Inside Chloroplast of Plant Cells

Well-packed thylakoids known as grana are one of the major functional sites for photosynthesis in algae and plants. Their highly ordered structures can be considered as a few hundred nanometer-sized particles having distinct scattering cross sections from other various macromolecular organizations inside plant cells. With this background we show that elastic light scattering imaging and microspectroscopy is an important tool for investigating structure and organization of grana inside a single chloroplast in plant cells. We have demonstrated this noninvasive method to identify the distribution of grana in intact fresh leaf of robust and rapidly growing Egaria densa, which is also known as Anachris and among the most popular aquarium plants. The scattering efficiency spectra of their individual grana fairly resemble cooperative absorption spectra of porphyrins and carotenoids. We found that the electronic structure of the stacked thylakoids shows granum size-dependence, indicating that size of grana is one of the critical parameters in the regulation of the photochemical functions in the thylakoid.

Enhanced optical confinement of dielectric nanoparticles by two-photon resonance transition

Two-photon resonance enhances optical confinement of nanoparticles.

Imaging Carotid Atherosclerosis Plaque Ulceration: Comparison of Advanced Imaging Modalities and Recent Developments

Atherosclerosis remains the leading cause of long-term mortality and morbidity worldwide, despite remarkable advancement in its management. Vulnerable atherosclerotic plaques are principally responsible for thromboembolic events in various arterial territories such as carotid, coronary, and lower limb vessels. Carotid plaque ulceration is one of the key features associated with plaque vulnerability and is considered a notable indicator of previous plaque rupture and possible future cerebrovascular events. Multiple imaging modalities have been used to assess the degree of carotid plaque ulceration for diagnostic and research purposes. Early diagnosis and management of carotid artery disease could prevent further cerebrovascular events. In this review, we highlight the merits and limitations of various imaging techniques for identifying plaque ulceration.