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In this research, we developed a facile method for the synthesis of silver chloride: polypyrrole (AgCl: PPy) nanocomposites with enhanced structural, thermal, optical, and conducting properties. Polypyrrole monomer was in-situ doped with varying weight percentages of assynthesized Ag nanoparticles by following simple chemical oxidation polymerization technique to form AgCl: PPy nanocomposites. The AgCl nanostructures with tree-like coral morphology are distributed uniformly into the PPy matrix without any segregation. The Fourier transform infrared spectroscopy results reveal the successful incorporation of AgCl in the organic structure of PPy. X-ray diffraction analysis shows the formation of AgCl nanostructures in the PPy matrix during the chemical polymerization process that increases the crystallinity of amorphous PPy. The TGA analysis demonstrates the improved thermal stability of PPy nanocomposites due to the development of physiochemical interactions between the AgCl and PPy moities, this is also inferred from Fourier transform infrared results. It is noted that the electrical conductivity of AgCl: PPy nanocomposites is significantly controlled by the weight percentage of dispersed Ag nanoparticles in the polymerization assembly. The highest conductivity (1335 S cm-1) of PPy nanocomposite is attributed to the decrease in particle size, shortening of the PPy chain length, and lower bandgap energy presented at the critical weight percentage of Ag nanoparticles.

Summary Background Pakistan is currently facing the largest outbreak of ceftriaxone-resistant Salmonella enterica serotype Typhi described to date. Here we aimed to report the outbreak investigation done in Hyderabad, Pakistan, and identify disease risk factors. Methods We did an age-matched case-control (1:4) study, in which cases of ceftriaxone-resistant S Typhi were identified from active sentinal sites (three hospitals in Hyderabad, Pakistan), community, and laboratory-based surveillance. Ceftriaxone-resistant S Typhi infection (ie, resistance to ampicillin, chloramphenicol, co-trimoxazole, fluoroquinole, and ceftriaxone) was confirmed using blood culture. Healthy participants (controls) were enrolled for the first 200 people (cases) with ceftriaxone-resistant S Typhi. A structured questionnaire was administered to identify exposures 4 weeks before the illness (cases) or enrolment (controls). Cases were included if written informed consent was provided. Four controls were selected from the same community as the corresponding case, matched on age, being healthy at the time of enrolment, and with no febrile illness in the 4 weeks before enrolment. Samples of drinking water from households and community water sources (ie, hand pumps or taps in common areas outside households) were collected for testing. Conditional logistic regression analysis was used to assess the risk factors for ceftriaxone-resistant S Typhi outbreak in Hyderabad. Findings Between Nov 30, 2016, and Dec 30, 2017, 486 people with ceftriaxone-resistant S Typhi were identified from Hyderabad. Of the 486 cases, 296 (61%) were male and 447 (92%) were aged 15 years or younger. Several factors were significantly associated with acquisition of ceftriaxone-resistant S Typhi, including male sex (adjusted odds ratio [aOR] 1·53, 95% CI 1·06–2·21), eating outside of the house (aOR 1·48, 1·01–2·19), exposure to a patient with S Typhi infection (aOR 3·81, 2·21–6·83), and a history of antimicrobial use (aOR 4·25, 2·53–7·13). Nine (69%) of 13 water samples taken from the households of people with ceftriaxone-resistant S Typhi infection were positive for Escherichia coli, indicating faecal contamination. S Typhi DNA was detected in 12 (22%) of 55 water samples from community water sources. Geospatial mapping showed clustering of cases around sewerage lines. Interpretation Hyderabad faces the largest reported outbreak of ceftriaxone-resistant S Typhi. The outbreak is suspected to be attributed to the contaminated drinking water, especially the mixing of sewage with drinking water. The risk of ceftriaxone-resistant S Typhi infection is increased among children aged 15 years and younger, male individuals, and those eating outside the house. Vaccination and chlorination of water are recommended for the containment of the outbreak. Funding None.

This paper presents a Riemannian approach for free-space extraction and path planning using color catadioptric vision. The problem is formulated considering color catadioptric images as Riemannian manifolds and solved using the Riemannian Eikonal equation with an anisotropic fast marching numerical scheme. This formulation allows the integration of adapted color and spatial metrics in an incremental process. First, the traversable ground (namely free-space) is delimited using a color structure tensor built on the multi-dimensional components of the catadioptric image. Then, the Eikonal equation is solved in the image plane incorporating a generic metric tensor for central catadioptric systems. This built Riemannian metric copes with the geometric distortions in the catadioptric image plane introduced by the curved mirror in order to compute the geodesic distance map and the shortest path between image points. We present comparative results using Euclidean and Riemannian distance transforms and show the effectiveness of the Riemannian approach to produce safest path planning.