Comparison of charged nanoparticle concentrations near busy roads and overhead high-voltage power lines

Overhead high-voltage power lines are known sources of corona ions. These ions rapidly attach to aerosols to form charged particles in the environment. Although the effect of ions and charged particles on human health is largely unknown, much attention has focused on the increasing exposure as a result of the expanding power network in urban residential areas. However, it is not widely known that a large number of charged particles in urban environments originate from motor vehicle emissions. In this study, for the first time, we compare the concentrations of charged nanoparticles near busy roads and overhead power lines. We show that large concentrations of both positive and negative charged nanoparticles are present near busy roadways and that these concentrations commonly exceed those under high-voltage power lines. We estimate that the concentration of charged nanoparticles found near two freeways carrying around 120 vehicles per minute exceeded the corresponding maximum concentrations under two corona-emitting overhead power lines by as much as a factor of 5. The difference was most pronounced when a significant fraction of traffic consisted of heavy-duty diesel vehicles which typically have high particle and charge emission rates.

Peptide-functionalized polymeric nanoparticles for active targeting of damaged tissue in animals with experimental autoimmune encephalomyelitis

Increased permeability of blood vessels is an indicator for various injuries and diseases, including multiple sclerosis (MS), of the central nervous system. Nanoparticles have the potential to deliver drugs locally to sites of tissue damage, reducing the drug administered and limiting associated side effects, but efficient accumulation still remains a challenge. We developed peptide-functionalized polymeric nanoparticles to target blood clots and the extracellular matrix molecule nidogen, which are associated with areas of tissue damage. Using the induction of experimental autoimmune encephalomyelitis in rats to provide a model of MS associated with tissue damage and blood vessel lesions, all targeted nanoparticles were delivered systemically. In vivo data demonstrates enhanced accumulation of peptide functionalized nanoparticles at the injury site compared to scrambled and naive controls, particularly for nanoparticles functionalized to target fibrin clots. This suggests that further investigations with drug laden, peptide functionalized nanoparticles might be of particular interest in the development of treatment strategies for MS.

Magnetic nanoparticles boosting the osmotic efficiency of a polymeric FO draw agent: Effect of polymer conformation

Poly sodium acrylate (PSA)-coated Magnetic Nanoparticles (PSA-MNPs) were synthesized as smart osmotic draw agent (SMDA) for water desalination by forward osmosis (FO) process. The PSA-coated MNPs demonstrated significantly higher osmotic pressure (~ 30 fold) as well as high FO water flux (~ 2–3 fold) when compared to their polymer (polyelectrolyte) counterpart, even at a very low concentration of ~ 0.13 wt.% in the draw solution. The PSA polymer chain conformation – coiled to extended – demonstrates a significant impact on the availability of the polymer hydrophilic groups in solution which is the driving force to attain higher osmotic pressure and water flux. When an optimum concentration of the polymer was anchored to a NP surface, the polymer chains assume an extended open conformation making the functional hydrophilic groups available to attract water molecules. This in turn boosts the osmotic pressure and FO water flux of the PSA-MNP draw agents. The low concentration of the PSA-MNP osmotic agent and the associated high water flux enhances the cost-effectiveness of our proposed SMDA system. In addition, easier magnetic separation and regeneration of the SMDA also improves its usability making it efficient, cost-effective and environment-friendly.

Visible light enhanced oxidant free dehydrogenation of aromatic alcohols using Au-Pd alloy nanoparticle catalysts

We find that visible light irradiation of gold–palladium alloy nanoparticles supported on photocatalytically inert ZrO2 significantly enhances their catalytic activity for oxidant-free dehydrogenation of aromatic alcohols to the corresponding aldehydes at ambient temperatures. Dehydrogenation is also the dominant process in the selective oxidation of the alcohols to the corresponding aldehydes with molecular oxygen. The alloy nanoparticles strongly absorb light and exhibit superior catalytic and photocatalytic activity when compared to either pure palladium or gold nanoparticles. Analysis with a free electron gas model for the bulk alloy structure reveals that the alloying increases the surface charge heterogeneity on the alloy particle surface, which enhances the interaction between the alcohol molecules and the metal NPs. The increased surface charge heterogeneity of the alloy particles is confirmed with density function theory applied to small alloy clusters. Optimal catalytic activity was observed with a Au : Pd molar ratio of 1 : 186, which is in good agreement with the theoretical analysis. The rate-determining step of the dehydrogenation is hydrogen abstraction. The conduction electrons of the nanoparticles are photo-excited by the incident light giving them the necessary energy to be injected into the adsorbed alcohol molecules, promoting the hydrogen abstraction. The strong chemical adsorption of alcohol molecules facilitates this electron transfer. The results show that the alloy nanoparticles efficiently couple thermal and photonic energy sources to drive the dehydrogenation. These findings provide useful insight into the design of catalysts that utilize light for various organic syntheses at ambient temperatures.

Au-Pd alloy nanoparticle catalyzed selective oxidation of benzyl alcohol and tandem synthesis of imines at ambient conditions

Alloy nanoparticles (NPs) of gold and palladium on ZrO2 support (Au–Pd@ZrO2) were found to be highly active in oxidation of benzyl alcohols and can be used for the tandem synthesis of imines from benzyl alcohols and amines via a one-pot, two-step process at mild reaction conditions. The first step of the process is oxidation of benzyl alcohol to benzaldehyde, excellent yields were achieved after 7 h reaction at 40 °C without addition of any base. In the second step, aniline was introduced into the reaction system to produced N-benzylideneaniline. The benzaldehyde obtained in the first step was completely consumed within 1 h. A range of benzyl alcohols and amines were investigated for the general applicability of the Au–Pd alloy catalysts. It is found that the performance of the catalysts depends on the Au–Pd metal contents and composition. The optimal catalyst is 3.0 wt% Au–Pd@ZrO2 with a Au:Pd molar ratio 1:1. The alloy NP catalyst exhibited superior catalytic properties to pure AuNP or PdNP because the surface of alloy NPs has higher charge heterogeneity than that of pure metal NPs according to simulation of density function theory (DFT)

Two-dimensional coordination polymeric structures in caesium complexes with ring-substituted phenoxyacetic acids

The two-dimensional polymeric structures of the caesium complexes with the phenoxyacetic acid analogues (4-fluorophenoxy)acetic acid, (3-chloro-2-methylphenoxy)acetic acid and the herbicidally active (2,4-dichlorophen­oxy)acetic acid (2,4-D), namely poly[[5-(4-fluorophenoxy)acetato][4-(4-fluorophenoxy)acetato]dicaesium], [Cs2(C8H6FO3)2]n, (I), poly[aqua[5-(3-chloro-2-methylphenoxy)acetato]caesium], [Cs(C9H8ClO3)(H2O)]n, (II), and poly[[7-(2,4-di­chlorophenoxy)acetato][(2,4-dichlorphenoxy)acetic acid]caesium], [Cs(C8H5Cl2O3)(C8H6Cl2O3)]n, (III), are described. In (I), the Cs+ cations of the two individual irregular coordination polyhedra in the asymmetric unit (one CsO7 and the other CsO8) are linked by bridging carboxylate O-atom donors from the two ligand molecules, both of which are involved in bidentate chelate Ocarboxy,Ophenoxy interactions, while only one has a bidentate carboxylate O,O'-chelate inter­action. Polymeric extension is achieved through a number of carboxylate O-atom bridges, with a minimum CsCs separation of 4.3231 (9) Å, giving layers which lie parallel to (001). In hydrated complex (II), the irregular nine-coordination about the Cs+ cation comprises a single monodentate water molecule, a bidentate Ocarboxy,Ophenoxy chelate interaction and six bridging carboxylate O-atom bonding interactions, giving a CsCs separation of 4.2473 (3) Å. The water mol­ecule forms intralayer hydrogen bonds within the two-dimensional layers, which lie parallel to (100). In complex (III), the irregular centrosymmetric CsO6Cl2 coordination environment comprises two O-atom donors and two ring-substituted Cl-atom donors from two hydrogen bis[(2,4-dichlorophenoxy)acetate] ligand species in a bidentate chelate mode, and four O-atom donors from bridging carboxyl groups. The duplex ligand species lie across crystallographic inversion centres, linked through a short O-HO hydrogen bond involving the single acid H atom. Structure extension gives layers which lie parallel to (001). The present set of structures of Cs salts of phenoxyacetic acids show previously demonstrated trends among the alkali metal salts of simple benzoic acids with no stereochemically favourable interactive substituent groups for formation of two-dimensional coordination polymers.

The in vivo fate of nanoparticles and nanoparticle-loaded microcapsules after oral administration in mice: Evaluation of their potential for colon-specific delivery

Anti-cancer drug loaded-nanoparticles (NPs) or encapsulation of NPs in colon-targeted delivery systems shows potential for increasing the local drug concentration in the colon leading to improved treatment of colorectal cancer. To investigate the potential of the NP-based strategies for colon-specific delivery, two formulations, free Eudragit® NPs and enteric-coated NP-loaded chitosan–hypromellose microcapsules (MCs) were fluorescently-labelled and their tissue distribution in mice after oral administration was monitored by multispectral small animal imaging. The free NPs showed a shorter transit time throughout the mouse digestive tract than the MCs, with extensive excretion of NPs in faeces at 5 h. Conversely, the MCs showed complete NP release in the lower region of the mouse small intestine at 8 h post-administration. Overall, the encapsulation of NPs in MCs resulted in a higher colonic NP intensity from 8 h to 24 h post-administration compared to the free NPs, due to a NP ‘guarding’ effect of MCs during their transit along mouse gastrointestinal tract which decreased NP excretion in faeces. These imaging data revealed that this widely-utilised colon-targeting MC formulation lacked site-precision for releasing its NP load in the colon, but the increased residence time of the NPs in the lower gastrointestinal tract suggests that it is still useful for localised release of chemotherapeutics, compared to NP administration alone. In addition, both formulations resided in the stomach of mice at considerable concentrations over 24 h. Thus, adhesion of NP- or MC-based oral delivery systems to gastric mucosa may be problematic for colon-specific delivery of the cargo to the colon and should be carefully investigated for a full evaluation of particulate delivery systems.

Imaging tumour distribution of a polymeric drug delivery platformin vivoby PET-MRI

Background Over the past decade, molecular imaging has played a key role in the progression of drug delivery platforms from concept to commercialisation. Of the molecular imaging techniques commonly utilised, positron emission tomography (PET) can yield a breadth of information not easily accessible by other methodologies and when combined with other complementary imaging modalities, is a powerful tool for pre- and clinical development of therapeutics. However, very little research has focussed on the information available from complimentary imaging modalities. This paper reports on the data-rich methodologies of contrast enhanced PET/CT and PET/MRI for probing efficacy of polymer drug delivery platforms. Results The information available from an ExiTron nano 6000 contrast enhanced PET/CT and a gadolinium (Gd) enhanced PET/MRI image of a 64Cu labeled HBP in the same mouse was qualitatively compared. Conclusions Gd contrast enhanced PET/MRI offers a powerful methodology for investigating the distribution of polymer drug delivery platforms in vivo and throughout a tumour volume. Furthermore, information about depth of penetration away from primary blood vessels can be gleaned, potentially leading to development of more efficacious delivery vehicles for clinical use.

Accelerated Multistress Aging of Outdoor Polymeric Insulators

Multistress aging of outdoor composite polymeric insulators continues to be a topic of interest for power transmission research community. Aging due to dry conditions alone at elevated temperatures and electric stress in the presence of UV radiation environment probably has not been explored. This paper deals with long-term accelerated multistress aging under the above conditions on full-scale 11 kV distribution class composite silicone rubber insulators. To evaluate the long-term synergistic effect of electric stress, temperature and UV radiation on insulators, they were subjected to accelerated aging in a specially designed multistress-aging chamber for 12000 hours. Chemical, physical and electrical changes due to degradation have been assessed using various techniques. It has been found that the content of low molecular weight molecules and hydrophobicity reduced significantly. Also, due to oxidation and aging there is appreciable increase in surface roughness and weight percentage of oxygen. Study is under progress and only intermediate results are presented in this paper.

Anionic clay-Pt metal nanoparticle composite through intercalation of hexachloroplatinate in nickel zinc hydroxysalt

Nickel zinc hydroxysalt–Pt metal nanoparticle composite was prepared by intercalation of the anionic platinum complex, [PtCl6]2− in nickel zinc hydroxysalt through ion exchange reaction and subsequent reduction of the platinum complex by ethanol. Powder X-ray diffraction and microscopy studies indicate that the process of reduction of the platinum complex in the interlayer region of the anionic clay takes place topotactically without destroying the layers.

Optical and nonlinear absorption properties of Na doped ZnO nanoparticle dispersions

We report linear and nonlinear optical properties of the biologically important Na doped ZnO nanoparticle dispersions. Interesting morphological changes involving a spherical to flowerlike transition have been observed with Na doping. Optical absorption measurements show an exciton absorption around 368 nm. Photoluminescence measurements reveal exciton recombination emission, along with shallow and deep trap emissions. The increased intensity of shallow trap emission with Na doping is attributed to oxygen deficiency and shape changes associated with doping. Nonlinear optical measurements show a predominantly two-photon induced, excited state absorption, when excited with 532 nm, 5 ns laser pulses, indicating potential optical limiting applications.

Formation and Degradation of Polymeric Peroxides

An attempt has been made to bring the literature on polymeric peroxides together from all angles in order to present a comprehensive picture about them. Both polyperoxides, where the peroxide group has been attached to the main chain, and polymeric hydroperoxides, where the peroxide group is present as a side chain, have been considered. Various aspects such as formation, thermal decomposition characteristics, photodecomposition, and analysis of peroxides have been discussed.

Plasma-enhanced synthesis of bioactive polymeric coatings from monoterpene alcohols: A combined experimental and theoretical study

This paper describes the synthesis and characterization of a novel organic polymer coating for the prevention of the growth of Pseudomonas aeruginosa on the solid surface of three-dimensional objects. Substrata were encapsulated with polyterpenol thin films prepared from terpinen-4-ol using radio frequency plasma enhanced chemical vapor deposition. Terpinen-4-ol is a constituent of tea tree oil with known antibacterial properties. The influence of deposition power on the chemical structure, surface composition, and ultimately the antibacterial inhibitory activity of the resulting polyterpenol thin films was studied using X-ray photoelectron spectroscopy (XPS), water contact angle measurement, atomic force microscopy (AFM), and 3-D interactive visualization and statistical approximation of the topographic profiles. The experimental results were consistent with those predicted by molecular simulations. The extent of bacterial attachment and extracellular polymeric substances (EPS) production was analyzed using scanning electron microscopy (SEM) and confocal scanning laser microscopy (CSLM). Polyterpenol films deposited at lower power were particularly effective against P. aeruginosa due to the preservation of original terpinen-4-ol molecules in the film structure. The proposed antimicrobial and antifouling coating can be potentially integrated into medical and other clinically relevant devices to prevent bacterial growth and to minimize bacteria-associated adverse host responses.

Radio frequency plasma enhanced synthesis of antifouling polymeric coatings from monoterpene alcohols

Radio frequency plasma enhanced chemical vapor deposition is currently used to fabricate a broad range of functional coatings. This work described fabrication and characterization of a novel bioactive coating, polyterpenol, for encapsulation of three-dimensional indwelling medical devices. The materials are synthesized from monoterpene alcohols under different input power conditions. The chemical composition and structure of the polyterpenol thin films were determined by Xray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, contact angle measurements, and atomic force microscopy (AFM). The application of polyterpenol coating to the substrate reduced surface roughness from 1.5 to 0.4 of a nanometer, and increased the water contact angle from to 9 to 72 degrees. The extent of attachment and extracellular polysaccharide (EPS) production of two medically relevant pathogens, Staphylococcus aureus and Staphylococcus epidermis were analyzed using scanning electron microscopy (SEM) and confocal scanning laser microscopy (CSLM). Application of polyterpenol coating fabricated at 10 W significantly inhibited attachment and growth of both pathogens compared to unmodified substrates, whilst addition of 50 W films resulted in an increased attachment, proliferation and EPS production by both types of bacteria when compared to unmodified surface. Marked dissimilarity in bacterial response between two coatings was attributed to changes in surface chemistry, nano-architecture and surface energy of polymer thin films deposited under different input power conditions.