Strongyloidiasis - diagnostic and therapeutic dilemmas in hyperinfection patients: a case series.

The helminth infection caused by Strongyloides stercoralis is widespread in tropical regions, but rare in European countries. Unfamiliarity with the disease and diagnostic obstacles could contribute to its lethal outcome. Frequent use of corticosteroids during the COVID-19 pandemic could increase its significance. The aim of this retrospective descriptive study was to explore disease patterns and discuss clinical dilemmas in patients with S. stercoralis hyperinfection treated at the University Hospital for Infectious Diseases 'Dr. Fran Mihaljevic' in Zagreb, Croatia, between 2010 and 2021. Five out of 22 (22.7%) immunosuppressed patients treated due to strongyloidiasis developed hyperinfection. All patients were male, median 64 years; four were immunosuppressed by corticosteroids (although ileum resection could have been the trigger in one) and one by rituximab. The diagnosis was established after a median of 1.5 months of symptom duration, accidentally in all patients, by visualizing the parasite in the gastric/duodenal mucosa in four cases, and bronchial aspirate in one. All patients were cachectic, four out of five had severe hypoalbuminemia and all suffered secondary bacterial/fungal infection. Despite combined antibiotic, antifungal and antihelmintic therapy, three out of five of the patients died, after failing to clear living parasites from stool samples. We can conclude that significant delays in diagnosis and lack of clinical suspicion were observed among our patients with the most severe clinical presentations of strongyloidiasis. Although being beyond diagnostic recommendations for strongyloidiasis, an early upper gastrointestinal endoscopy with mucosal sample analysis could expedite diagnosis in severe, immunosuppressed patients. The persistence of viable parasites in the stool despite antihelmintic therapy should be further investigated.

Detection of multi-class pesticide residues with surface-enhanced Raman spectroscopy.

The excessive use of pesticides disturbs the natural balance in the environment, creates resistance to pesticides and leads to water and food contamination. Therefore, the implementation of fast, robust and cost effective techniques for the monitoring of pesticides is required. In this work surface-enhanced Raman spectroscopy (SERS) was used for the detection of four common pesticides: atrazine, simazin, irgarol, and diuron. SERS is nowadays considered an effective technique for detection of various analytes in low concentration. Sensitivity of the SERS method depends on the type of substrate that can be either a colloidal solution of metal nanoparticles (NPs) or a metal surface with a suitable nanostructured topology. Here, we have investigated the application of silver nanospheres and silver nanoprisms as SERS substrates in pesticides detection. Colloids with spherical NPs were produced by chemical reduction while Ag nanoprisms were prepared by reducing silver nitrate with borohydride (with citrate as a stabilizing agent) and stirring under a UV lamp for 4 and 10 h. The SERS results have shown that, in the presence of synthesized NPs, it was possible to detect millimolar concentrations of aforementioned pesticides with the exception of diuron.

Controlling the flux of reactive species: a case study on thin film deposition in an aniline/argon plasma.

The plasma based synthesis of thin films is frequently used to deposit ultra-thin and pinhole-free films on a wide class of different substrates. However, the synthesis of thin films by means of low temperature plasmas is rather complex due to the great number of different species (neutrals, radicals, ions) that are potentially involved in the deposition process. This contribution deals with polymerization processes in a capacitively coupled discharge operated in a mixture of argon and aniline where the latter is a monomer, which is used for the production of plasma-polymerized polyaniline, a material belonging to the class of conductive polymers. This work will present a particular experimental approach that allows to (partially) distinguish the contribution of different species to the film growth and thus to control to a certain extent the properties of the resulting material. The control of the species flux emerging from the plasma and contributing to the film growth also sheds new light on the deposition process, in particular with respect to the role of the ion component. The analysis of the produced films has been performed by means of Fourier Transform Infrared spectroscopy (FTIR) and Near Edge X-ray Absorption Fine Structure spectroscopy (NEXAFS).

Towards large-scale in free-standing graphene and N-graphene sheets.

One of the greatest challenges in the commercialization of graphene and derivatives is production of high quality material in bulk quantities at low price and in a reproducible manner. The very limited control, or even lack of, over the synthesis process is one of the main problems of conventional approaches. Herein, we present a microwave plasma-enabled scalable route for continuous, large-scale fabrication of free-standing graphene and nitrogen doped graphene sheets. The method's crucial advantage relies on harnessing unique plasma mechanisms to control the material and energy fluxes of the main building units at the atomic scale. By tailoring the high energy density plasma environment and complementarily applying in situ IR and soft UV radiation, a controllable selective synthesis of high quality graphene sheets at 2 mg/min yield with prescribed structural qualities was achieved. Raman spectroscopy, scanning electron microscopy, high resolution transmission electron microscopy, X-ray photoelectron spectroscopy and Near Edge X-ray-absorption fine-structure spectroscopy were used to probe the morphological, chemical and microstructural features of the produced material. The method described here is scalable and show a potential for controllable, large-scale fabrication of other graphene derivatives and promotes microwave plasmas as a competitive, green, and cost-effective alternative to presently used chemical methods.

Growth process of nanosized aluminum thin films by pulsed laser deposition for fluorescence enhancement.

Pulsed laser deposition was used to deposit aluminum thin films of various thicknesses (tAl) ranging from 5 to 40 nm and to investigate their growth process when they are deposited onto SiO2 and Y2O3. Atomic force microscopy and x-ray reflectivity measurements show that the structure of the Al films are related to the wettability properties of the underlaying layer. Onto SiO2, ultra-smooth layers of aluminum are obtained, due to a perfect wetting of SiO2 by Al. In contrast when deposited onto Y2O3, percolated Al layers are observed with apparent pore size decreasing from 200 to 82 nm as t(Al) is increased from 5 to 40 nm, respectively. This particular morphology is related to partial dewetting of Al on Y2O3. These two different growth mechanisms of aluminum depend therefore on the surface properties of SiO2 and Y2O3. The plasmon resonance of such Al nanostructures in the UV region was then analyzed by studying the coupling between Eu(3+) rare earth emitters and Al.

In situ characterization of nanoparticles during growth by means of white light scattering.

A simple method of characterization of suspensions of spherical nanoparticles with monotonically variable size is proposed. It allows for the in situ measurement of the particle size as well as spectral dependence of their refractive indices. The method requires three optical channels: one for the illumination of a suspension by white light and two for the measurements of the spectra of scattered light. Parameters of the particles are determined by fitting the measured temporal spectral surfaces by the calculated Mie scattering functions. The method is applied to the particles being grown in a low-pressure reactive plasma of a discharge in an acetylene-argon mixture.

Effect of transport of growing nanoparticles on capacitively coupled rf discharge dynamics.

We present experimental and numerical studies of the properties of a capacitively coupled 13.56MHz discharge in a mixture of Ar and C2H2 with growing nanosize particles. It is found that at the initial stage of the growth, nanoparticles are accumulated near the sheath-plasma boundaries, where the ionization by electrons is maximal. The nanoparticles suppress the ionization due to the absorbing fast electrons and stimulate a quick change of the plasma parameters followed by a transition between different modes of discharge operation. At that moment the peaked distribution of the dust particles transforms into a flat one.

Secondary electron emission of carbonaceous dust particles.

In this paper we present measurements of the secondary electron emission yield (gamma) of a carbonaceous dust particle material, which was grown in argon diluted acetylene plasmas. One aim was to reach a better understanding of charging and discharging processes of dust particles in complex plasmas due to secondary electron emission and consequently to try to explain the anomalous behavior of electron density observed in afterglows of pulsed rf plasmas. We compared the results of a simple model and of a Monte Carlo simulation to the previously measured time dependence of the electron density in complex plasma afterglow. It was found that the value of the intrinsic secondary electron yield from the carbonaceous dust material is too low to explain the increase of electron density in the afterglow. It is, however, possible that the electrons charging the particles are weakly attached so that they may be released with high efficiency by ion bombardment due to field induced emission or by other mechanisms.