In silico evaluation of a new compound incorporating 4(3H)-quinazolinone and sulfonamide as a potential inhibitor of a human carbonic anhydrase.

The present study investigates the potential of a new compound containing sulfonamide and 4(3H)-quinazolinone to inhibit the hCA-IIX enzyme using in silico methods. Density functional theory-based calculations of electronic properties have been addressed through the analysis of frontier molecular orbitals, molecule electrostatic potential, and IR and UV-vis spectroscopy data. A molecular electrostatic potential analysis predicts that the target protein will be most inhibited by the sulfonamide groups since it has the highest potential spots for electrophile and nucleophile attack. The investigated compound exhibited good ADMET properties and satisfied the Lipinski rule of drug likeness. The hCA-IIX protein binding affinity with the proposed compound was determined by molecular docking analysis, which revealed a stable conformation with more negative binding energy (-12.19 kcal/mol) than the standard AZA drug (-7.36 kcal/mol). Moreover, a molecular dynamics study confirmed the docking results through trajectory analysis. The RMSD and RMSF both showed convergence and no significant fluctuations during the simulation time, which revealed a stable interaction within the active domain of the target protein. According to these findings, the proposed compound has a good pharmacological nature and could potentially be an efficient drug against hCAIX enzymes.

Unveiling the Impact of Drying Methods on Phytochemical Composition and Antioxidant Activity of Anthemis palestina.

Different drying techniques may alter the chemical composition of plant extracts and consequently affect their bioactivity potential. The current study was designed to reveal the effect of four different drying methods on the phytochemical composition and antioxidant activity of hydrodistilled essential oil (HD-EO) and methanolic (APM) extract obtained from the aerial part of Anthemis palestina from Jordan. Aerial parts of A. palestina in their fresh (FR) form and after drying in shade (ShD), sun (SD), oven at 40 °C (O40D) and 60 °C (O60D), in addition to microwave (MWD), were used to extract their essential oils by hydrodistillation and to prepare the different methanolic extracts (APM). GC/MS analysis of the different HD-EOs revealed qualitative and quantitative differences among the different samples. While FR, O40D, O60D, and MWD EO samples contained mainly sesquiterpene hydrocarbons (35.43%, 29.04%, 53.69%, and 59.38%, respectively), ShD sample was rich in oxygenated monoterpenes (33.57%), and SD-EO contained mainly oxygenated sesquiterpenes (40.36%). Principal component analysis (PCA) and Cluster analysis (CA) grouped the different drying methods based on their impact on the concentration of chemical constituents. SD-EO demonstrated high DPPH and ABTS antioxidant activity (1.31 ± 0.03) × 10-2; (1.66 ± 0.06) × 10-2 µg/mL, respectively). Furthermore, A. paleistina methanolic extracts (APM) obtained after subjecting the plant to different drying methods showed interesting patterns in terms of their TPC, TFC, antioxidant activity, and phytochemical profiling. Of all extracts, SD-APM extract had the highest TPC (105.37 ± 0.19 mg GA/g DE), highest TFC (305.16 ± 3.93 mg Q/g DE) and demonstrated the highest DPPH and ABTS scavenging activities ((4.42 ± 0.02) × 10-2; (3.87 ± 0.02) × 10-2 mg/mL, respectively); all were supported by correlation studies. LC-MS/MS analysis of the different extracts revealed the richness of the SD-APM extract in phenolic acids and flavonoids.

Influence of thermal relaxation time on thermomechanical interactions in biological tissue during hyperthermia treatment.

This study presents an analytical analysis of thermo-mechanical interactions within living tissues using a generalized biothermoelastic model with one thermal relaxation time. Utilizing Laplace transforms and associated techniques, we investigate the response of living tissue to a pulse boundary heat flux that decays exponentially on a traction-free surface. Through detailed graphical illustrations, we elucidate the influence of key parameters such as thermal relaxation time, blood perfusion rate, and the characteristic time of the pulsing heat flux on temperature distribution, displacement, and thermal strain. Our results are presented through comprehensive graphical representations. Furthermore, a parametric analysis is conducted to guide the selection of optimal design factors, enhancing the accuracy of hyperthermia treatments.

Evaluating a novel patient pathway to manage symptomatic breast referrals (the blue flag clinic): a longitudinal observational study.

INTRODUCTION: A novel referral pathway for exhibited breast symptom (EBS) referrals to manage increasing referrals of urgent suspected cancer (USC) was implemented in our trust. We report on the safety and effect on compliance with the 2-week-wait rule (2WW). METHODS: A single-centre longitudinal observational study included all patients referred to a UK breast unit during 13 May 2019 to 27 March 2020 (period 1) and 8 February 2021 to 31 January 2022 (period 2). USC referrals were assessed in a one-stop clinic (red flag clinic [RFC]); EBS referrals were assessed in a new clinic in which clinical evaluation was performed and imaging occurred subsequently (blue flag clinic [BFC]). Patients were followed up to determine the symptomatic interval cancer rate. RESULTS: There were 9,695 referrals; 1,655 referrals (17%) were assessed in the BFC after 63 exclusions. Some 95.9% of patients had a benign clinical examination (P1/P2), 80.1% had imaging (mammogram or ultrasound) and 4% had a tissue biopsy. In total, 16/1,655 (0.97%) BFC patients and 510/7,977 (8.2%) RFC patients were diagnosed with breast cancer (breast cancer detection rate). Some 1,631 patients (with 1,639 referrals) were discharged and followed up for a median of 17 months (interquartile range 12-32) with one subsequent cancer diagnosis (symptomatic interval cancer rate, 0.06%). Implementation of the BFC pathway increased 3-month average trust performance of USC referrals with 2WW standard from 8.5% to 98.7% (period 1) and from 30% to 66% (period 2). CONCLUSIONS: The BFC pathway for EBS patients is safe and implementation led to improvement against the 2WW target for USC referrals, ensuring resources are prioritised to patients with the highest likelihood of breast cancer.

Experimental and Computational Exploration of Chitin, Pectin, and Amylopectin Polymers as Efficient Eco-Friendly Corrosion Inhibitors for Mild Steel in an Acidic Environment: Kinetic, Thermodynamic, and Mechanistic Aspects.

Herein, the inhibition impacts of chitin, pectin, and amylopectin as carbohydrate polymers on the corrosion of mild steel in 0.5 M HCl were researched utilizing various experimental and theoretical tools. The acquired outcomes showed that the inhibition efficiencies (% IEs) of the tested carbohydrate polymers were increased by raising their concentrations and these biopolymers acting as mixed-kind inhibitors with major anodic ones. The acquired % IEs values were reduced with rising temperature. The higher % IEs of the tested polymers were inferred via powerful adsorption of the polymeric molecules on the steel surface and such adsorption obeyed the Langmuir isotherm. The computed thermodynamic and kinetic quantities confirmed the mechanism of physical adsorption. The kinetics and mechanisms of corrosion and its protection by polymeric compounds were illuminated. The results obtained from all the techniques used confirmed that there was good agreement with each other, and that the % of IEs followed the sequence: chitin > amylopectin > pectin.

Inhibitory Activity of Saussurea costus Extract against Bacteria, Candida, Herpes, and SARS-CoV-2.

Medicinal herbs have long been utilized to treat various diseases or to relieve the symptoms of some ailments for extended periods. The present investigation demonstrates the phytochemical profile, molecular docking, anti-Candida activity, and anti-viral activity of the Saussurea costus acetic acid extract. GC-MS analysis of the extract revealed the presence of 69 chemical compounds. The chemical compounds were alkaloids (4%), terpenoids (79%), phenolic compounds (4%), hydrocarbons (7%), and sterols (6%). Molecular docking was used to study the inhibitory activity of 69 identified compounds against SARS-CoV-2. In total, 12 out of 69 compounds were found to have active properties exhibiting SARS-CoV-2 inhibition. The binding scores of these molecules were significantly low, ranging from -7.8 to -5.6 kcal/mol. The interaction of oxatricyclo [20.8.0.0(7,16)] triaconta-1(22),7(16),9,13,23,29-hexaene with the active site is more efficient. Furthermore, the extract exhibited significant antimicrobial activity (in vitro) against Candida albicans, which was the most susceptible microorganism, followed by Bacillus cereus, Salmonella enterica, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa, respectively. On the other hand, its antiviral activity was evaluated against HSV-1 and SARS-CoV-2, and the results showed a significant positive influence against HSV-1 (EC50 = 82.6 g/mL; CC50 = 162.9 g/mL; selectivity index = 1.9). In spite of this, no impact could be observed in terms of inhibiting the entry of SARS-CoV-2 in vitro.

Computational Foretelling and Experimental Implementation of the Performance of Polyacrylic Acid and Polyacrylamide Polymers as Eco-Friendly Corrosion Inhibitors for Copper in Nitric Acid.

Copper is primarily used in many industrial processes, but like many other metals, it suffers from corrosion damage. Polymers are not only one of the effective corrosion inhibitors but also are environmentally friendly agents in doing so. Hence, in this paper, the efficacy of two polyelectrolyte polymers, namely poly(acrylic acid) (PAA) and polyacrylamide (PAM), as corrosion inhibitors for copper in molar nitric acid medium was explored. Chemical, electrochemical, and microscopic tools were employed in this investigation. The weight-loss study revealed that the computed inhibition efficiencies (% IEs) of both PAA and PAM increased with their concentrations but diminished with increasing HNO3 concentration and temperature. The results revealed that, at similar concentrations, the values of % IEs of PAM are slightly higher than those recorded for PAA, where these values at 298 K reached 88% and 84% in the presence of a 250 mg/L of PAM and PAA, respectively. The prominent IE% values for the tested polymers are due to their strong adsorption on the Cu surface and follow the Langmuir adsorption isoform. Thermodynamic and kinetic parameters were also calculated and discussed. The kinetics of corrosion inhibition by PAA and PAM showed a negative first-order process. The results showed also that the used polymers played as mixed-kind inhibitors with anodic priority. The mechanisms of copper corrosion in nitric acid medium and its inhibition by the tested polymers were discussed. DFT calculations and molecular dynamic (MD) modelling were used to investigate the effect of PAA and PAM molecular configuration on their anti-corrosion behavior. The results indicated that the experimental and computational study are highly consistent.

Effect of nano silver on gastroprotective activity against ethanol-induced stomach ulcer in rats.

Silver nanoparticles (Ag NPs) have unique properties and display an important role in bioactivities such as antimicrobial, antiviral, antifungal, and anticancer. Stable Ag NPs were prepared by reaction of silver nitrate solution with extract of Melissa and characterized by UV-Vis spectroscopy, AFM, SEM, XRD, and Zeta potential. The resulted Ag NPs have a size range between 20 and 35 nm. The current study aims to evaluate the gastroprotective effect of Ag NPs against ethanol-induced gastric ulcers in rats. Thirty rats were randomly divided into five groups. The experimental groups were fed 175 and 350 ppm/p.o of Ag NPs orally. Ag NPs improved the adversative influence of ethanol-induced stomach damage as confirmed by declining ulcer index and raised the percentage of ulcer prevention. Significantly reduced ethanol-induced gastric lesions were evidenced by increased mucus secretion and pH of stomach content, decreased ulcer area, nonappearance of edema, and leucocyte penetration of the subcutaneous layer. In gastric homogenate, Ag NPs displayed a substantial upsurge in superoxide dismutase (SOD), catalase (CAT) activities, and significantly reduced malondialdehyde (MDA) levels., Ag NPs increased the intensity of periodic acid Schiff stained (PAS) and produced over-regulation of HSP-70 and down-regulation of Bax proteins. Ag NPs confirmed gastro-protection which might be attributed to its antioxidant effect, increased mucus secretion, increased SOD, and CAT, reduced MDA level, over-regulation of HSP-70 protein, and down-regulation of Bax protein.

Multifunctional leather surface embedded with zinc oxide nanoparticles by pulsed laser ablation method.

A simple procedure was used to generate and decorate leather structures with different amounts from zinc oxide (ZnO) nanoparticles to produce multifunctional leather structure by pulsed laser ablation method in liquid media based on changing the ablation time in just one-pot method. The impact of varying concentrations of ZnO nanoparticles embedded on the surface of leather on water resistance, water vapor permeability, mechanical characteristics, and UV-shielding efficiency was examined by different characterization techniques like X-ray diffraction, surface area, UV-visible spectroscopy, scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy, and thermogravimetric analysis. The results showed that the combination between the external functional groups of leather with ZnO nanoparticles was discovered. ZnO nanoparticles effectively coated the surface of leather tissue, as seen by SEM images, and their form a spherical morphology. Leather with ZnO nanoparticles added had the highest capacity to kill Escherichia coli bacteria, exceeding leather without modification and ZnO nanoparticles alone in 50-hr incubation. In addition, the incubation period had a substantial impact on the suppression of Staphylococcus aureus bacteria growth by leather samples.

Serological Investigation of Bovine Chlamydia abortus in Wasit Province, Iraq.

Chlamydia abortus is one of the most common infectious and zoonotic bacteria, which causes abortion in different ruminants as well as other animals and humans. For the first time in Iraq, the current study aimed to identify the prevalence of C. abortus in cattle using the enzyme-linked immunosorbent assay (ELISA). A total of 276 venous blood samples were collected from November (2021) to January (2022), subjected to obtaining sera that ELISA tested. Infection severity and estimation of the relationship between serum positivity and risk factors (including age, sex and region) were evaluated. An overall 17.03% of samples were being positive for C. abortus, which classified as mild (63.83%), moderate (25.53%) and severe (10.64%) infections with OD values of 0.32710.0085, 0.5270.0139 and 0.70840.0256, respectively. The association of positivity to risk factors revealed that there was significant variation in their values as follows: for age, significant increases in prevalence and risk factors were detected in cattle aged <3 years when compared to 3-6 and >6 years; whereas, for sex, significant increases were found in females more than males. For the region, significant higher and lower prevalence and risk exposure to were reported in Al-Hai and Al-Kut, respectively. The association of mild, moderate and severe infections to risk factors showed that moderate infection was elevated significantly in cattle of <3 years, while the mild infection increased significantly in cattle aged 3-6 and >6 years with the absence of severe infection in both last age groups. In females and males and all study regions, mild infection appeared more significantly than moderate and severe infections (P<0.05). The present study was the first serological detection of C. abortus in cattle in Wasit province (Iraq); furthermore, studies are necessary to estimate the prevalence of C. abortus in cattle and other field animals.

A review on toxoplasmosis in humans and animals from Egypt.

The present paper summarizes prevalence, epidemiology and clinical disease of natural Toxoplasma gondii infections in humans and animals from Egypt. The current situation of toxoplasmosis in Egypt is confusing. There is no central laboratory or group of researchers actively investigating toxoplasmosis in humans or animals, and no reports on the national level are available. Based on various serological tests and convenience samples, T. gondii infections appear highly prevalent in humans and animals from Egypt. Living circumstances in Egypt favour the transmission of T. gondii. Up to 95% of domestic cats, the key host of T. gondii, are infected with T. gondii; they are abundant in rural and suburban areas, spreading T. gondii oocysts. Many women have been tested in maternity clinics, most with no definitive diagnosis. Toxoplasma gondii DNA and IgM antibodies have been found in blood samples of blood donors. Clinical toxoplasmosis in humans from Egypt needs further investigations using definitive procedures. Reports on congenital toxoplasmosis are conflicting and some reports are alarming. Although there are many serological surveys for T. gondii in animals, data on clinical infections are lacking. Here, we critically review the status of toxoplasmosis in Egypt, which should be useful to biologist, public health workers, veterinarians and physicians.

Prevalence of Eimeria Species in Water Buffaloes (Bubalus bubalis) from Egypt and First Report of Eimeria bareillyi Oocysts.

Coccidiosis is a common disease of livestock, including water buffaloes. Reports discussing the prevalence and identity of coccidian parasites in water buffaloes from Egypt are few, and nothing is known concerning the most pathogenic species, Eimeria bareillyi. Fresh feces collected from 175 water buffaloes in Dakahlia Governorate, Egypt, were processed using the standard flotation technique. Eimerian oocysts were found in 49 (28%) samples, and 10 species were identified. Eimeria bareillyi oocysts were found in 10 samples (5.7%), and this was the single species in 3 diarrheic calves. Typical oocysts of Eimeria auburnensis with smooth oocyst walls were observed in 4 (2.3%) samples. Closely similar oocysts were found in a single sample (0.6%) together with those of E. auburnensis. These oocysts had a rough granulated or mammillated wall and are referred to as E. auburnensis-like oocysts. A molecular study is needed to clarify whether E. auburnensis and E. auburnensis-like oocysts are from different species. Other identified Eimeria species were: Eimeria alabamensis (0.6%), Eimeria bovis (10.8%), Eimeria canadensis (1.1%), Eimeria cylindrica (4%), Eimeria ellipsoidalis (2.3%), Eimeria subspherica (2.8%), and Eimeria zuernii (9.7%). This is the first report of E. bareillyi oocysts in water buffaloes from Egypt.

Prevalence of Eimeria Species in Camels (Camelus dromedarius) from Egypt and Variability in Structure of Eimeria cameli Oocysts.

Coccidiosis is a common disease of camels, and camels are important for the economy of Asia and the Arabian Peninsula. Little is known regarding the prevalence of coccidian parasites in camels in Egypt. Fecal samples collected from the rectums of 200 camels at the Cairo slaughterhouse were processed using the sucrose flotation technique. Eimeria species oocysts were found in 38%. Three Eimeria species were identified: Eimeria cameli-like in 31%, Eimeria rajasthani in 18%, and Eimeria dromedarii in 14%. The morphology of E. rajasthani and E. dromedarii oocysts was identical to that in literature. However, there was great variability in size and structure among E. cameli oocysts; oocysts were 70-100 µm long and truncate to ovoid. Four morphotypes (types 1 to 4) were recognized. Types 1 and 2 oocysts had similar truncate ovoid shape and were dark brown, but their shape indices were different. Both types could be easily distinguished from type 3 (elongate ovoid and light brown). All oocysts were enclosed in a transparent outer covering (capsule), although this capsule was barely seen in types 3 and 4. An extension from the capsule situated in front of the micropyle, referred to as polar cap-like structure (PCL), was characteristic for types 1 and 2. The PCL of type 1 resembled the crown, while in type 2 it looked like a small thickening with a smooth top. The PCL was absent in types 3 and 4 oocysts. The latter was found only in a single oocyst. Experimental infections with E. cameli oocysts and molecular studies are needed to determine whether the monotypes described here are different species or strain variations or both.

A review of sarcocystosis in camels and redescription of Sarcocystis cameli and Sarcocystis ippeni sarcocysts from the one-humped camel (Camelus dromedarius).

There is considerable confusion concerning Sarcocystis species in camels. Five species: Sarcocystis cameli, Sarcocystis ippeni, Sarcocystis camelicanis, Sarcocystis camelocanis and Sarcocystis miescheri were named with inadequate descriptions and no type specimens. Here, we review literature on sarcocystosis in camels worldwide and redescribe structure of S. cameli and S. ippeni sarcocysts by light- and transmission electron microscopy (LM and TEM). Eight sarcocysts from the oesophagi of two camels (Camelus dromedarius) from Egypt were studied. By LM, all sarcocysts were thin-walled with barely visible projections on the cyst walls. By TEM, two structurally distinct sarcocysts were recognized by unique villar protrusions (vp) not found in sarcocysts from any other host. Sarcocysts of S. cameli had vp of type 9 j. The sarcocyst wall had upright slender vp, up to 3.0 µM long and 0.5 µM wide; the total thickness of the sarcocyst wall with ground substance (gs) layer was 3.5 µM. On each vp, there were rows of knob-like protrusions that appeared to be interconnected. The vp had microtubules that originated at midpoint of the gs and continued up to the tip; microtubules were smooth, without any granules or dense areas. Bradyzoites were approximately 14-15 × 3-4 µM in size with typical organelles. Sarcocystis ippeni sarcocysts had type 32 sarcocyst wall characterized by conical vp with an electron dense knob. The total thickness of the sarcocyst wall (from the base of gs to vp tip) was 2.3-3.0 µM. The vp were up to 1.2 µM wide at the base and 0.25 µM at the tip. Microtubules in vp originated at midpoint of gs and continued up to tip; microtubules were criss-crossed, smooth and without granules or dense areas. Bradyzoites were 12.0-13.5 × 2.0-3.0 µM in size. Sarcocystis camelicanis, S. camelocanis and S. miescheri are considered invalid.

Occult hepatitis B virus coinfection in HIV-positive African migrants to the UK: a point prevalence study.

OBJECTIVES: Occult (surface antigen-negative/DNA-positive) hepatitis B virus (HBV) infection is common in areas of the world where HBV is endemic. The main objectives of this study were to determine the prevalence of occult HBV infection in HIV-infected African migrants to the UK and to determine factors associated with occult coinfection. METHODS: This anonymized point-prevalence study identified Africans attending three HIV clinics, focussing on patients naïve to antiretroviral therapy (ART). Stored blood samples were tested for HBV DNA. Prevalence was calculated in the entire cohort, as well as in subpopulations. Risk factors for occult HBV coinfection were identified using logistic regression analysis. RESULTS: Among 335 HIV-positive African migrants, the prevalence of occult HBV coinfection was 4.5% [95% confidence interval (CI) 2.8-7.4%] overall, and 6.5% (95% CI 3.9-10.6%) and 0.8% (95% CI 0.2-4.6%) in ART-naïve and ART-experienced patients, respectively. Among ART-naïve anti-HBV core (anti-HBc)-positive patients, the prevalence was 16.4% (95% CI 8.3-25.6%). The strongest predictor of occult coinfection was anti-HBc positivity [odds ratio (OR) 7.4; 95% CI 2.0-27.6]. Median HBV DNA and ALT levels were 54 IU/mL [interquartile range (IQR) 33-513 IU/mL] and 22 U/L (IQR 13-27 U/L), respectively. CONCLUSIONS: Occult HBV coinfection remains under-diagnosed in African HIV-infected patients in the UK. Given the range of HBV DNA levels observed, further studies are warranted to determine its clinical significance and to guide screening strategies and ART selection in these patients.

Some determinants of factors associated with HIV/AIDS risk behaviours among University of Dodoma students in Tanzania.

The paper examines whether variables of HIV/AIDS related knowledge, attitude and beliefs of Dodoma University students (UDOM) can predict practices which risk HIV infection. A pre-designed questionnaire was administered in a sample of 547 (539 students and 8 staff members). Since variables involved were many and in many cases highly correlated and unobservable, data were analyzed using factor analysis. Multiple regression analysis were used to analyze factor scores obtained from factor analysis. Based on responses of students to practice questions, two factors emerged and were labeled as sex with high risk persons and common risk sexual behavior. The common predictors in the Multiple Linear Regression (MLR) for sex with high risk persons score (R2 = 5.1%, p < 0.001, F = 4.873) and sex under the influence of alcohol (p < 0.001) respectively both had significant contribution from gender, knowledge on transmission through sexual contact, beliefs about HIV/AIDS and attitudes toward VCT testing. The MLR for common risk sexual behavior score (R2 = 5.4%, p < 0.001, F = 5.147) and sex without condom (p < 0.001) respectively both had significant contributions from gender and attitudes toward condom use. Knowledge on transmission through sexual contact, beliefs about HIV/AIDS and attitudes toward VCT testing and condom use appeared to be common determinants of HIV/AIDS risk behaviors among students.

Total synthesis of isofregenedadiol.

The first total synthesis of isofregenedadiol, a bicyclic diterpene isolated from H. Viscosum, is reported starting from a D-(-)-pantolactone chiral pool. A one-pot quadruple reaction sequence comprising an enyne ring-closing metathesis/cross-metathesis/Diels-Alder/aromatization for the construction of a target skeleton is the highlight of the present synthesis.

The versatile colour gamut of coatings of plasmonic metal nanoparticles.

We have investigated the colour gamut of coatings produced by the growth of plasmonically-active coatings of cap-shaped Au or Ag nanoparticles on a transparent substrate. The control of colour and spectral selectivity that can be obtained by the manipulation of the rates of nucleation and growth were explored using a combination of experiment and calculation. In our experimental work the Au nanoparticles were grown in situ using a wet chemical electroless plating technique while the Ag nanoparticles were produced by physical vapour deposition. The optical properties were numerically simulated using the discrete dipole approximation. The resulting measured or calculated transmission spectra were mapped to the CIE L-a -b colour space. The aspect ratio of the nanoparticles was the primary factor in determining the colours in both cases. However, increasing the nucleation rate of the particles resulted in them becoming more closely packed, which also red-shifted the optical extinction peak of the structure due to interactions of their near-fields. This caused an enhancement in the blue component of the transmitted light. Coatings of Ag particles had a significantly wider and brighter colour gamut than those of Au.

The preparation of a plasmonically resonant VO2 thermochromic pigment.

Vanadium dioxide (VO(2)) undergoes a reversible metal-insulator transition, normally at approximately 68 degrees C. While the properties of continuous semi-transparent coatings of VO(2) are well known, there is far less information available concerning the potential use of discrete VO(2) nanoparticles as a thermochromic pigment in opaque coatings. Individual VO(2) nanoparticles undergo a localized plasmon resonance with near-infrared light at about 1100 nm and this resonance can be switched on and off by simply varying the temperature of the system. Therefore, incorporation of VO(2) nanoparticles into a coating system imbues the coating with the ability to self-adaptively modulate its own absorptive efficiency in the near-infrared. Here we examine the magnitude and control of this phenomenon. Prototype coatings are described, made using VO(2) powder produced by an improved process. The materials are characterized using calorimetry, x-ray diffraction, high-resolution scanning electron microscopy, transmission electron microscopy, and by measurement of optical properties.

Mie and Bragg plasmons in subwavelength silver semi-shells.

2D arrays of silver semi-shells of 100 and 200 nm diameter display complex reflection and transmission spectra in the visible and near-IR. Here these spectral features are deconstructed and it is demonstrated that they result from the coupling of incident light into a delocalized Bragg plasmon, and the latter's induction of localized Mie plasmons in the arrays. These phenomena permit the excitation of transverse dipolar plasmon resonances in the semi-shells despite an ostensibly unfavorable orientation with respect to normally incident light. The resulting spectral feature in the mid-visible is strong and tunable.