Characterization and chlorine reactivity of particulate matter released by bathers in indoor swimming pools

Disinfecting swimming pool water is essential for preventing waterborne diseases. An unforeseen consequence of treating water with disinfectants is the formation of disinfection by-products (DPBs) that can cause harmful effects to health through the interactions between the added disinfectant and organic matter in the water. The present work focuses on the chlorine reactivity with particles released by bathers. Such particles are collected in the filter backwash water of swimming pools and this study intends to distinguish DPBs generated from dissolved chemicals from those formed by particulate matter. Therefore, filtered and unfiltered backwash waters were collected from several swimming pools, analysed physicochemically and chemically, and then chlorinated as is (79 mgL^-1) and as diluted suspensions (36.2 and 11.9 mgL^-1) at varying concentrations of chlorine (1.2 mg and 24 mgCl₂L^-1). Utilizing a DPD colorimetric technique and GC-ECD, respectively, the kinetics of chlorine consumption and DPBs production have been investigated. Up to 25.7 μgL^-1 of chloroform was produced within 96 h at 1.2 mgCl₂L^-1, followed by haloacetic acids (HAAs) and haloacetonitriles (HANs). Within 96 h, the concentration of trichloroacetic acid reached a maximum of 231.8 μgL^-1 at a chlorine concentration of 231.8 μgL^-1. The formations of 0.13 μmol THMs, 0.31 μmol HAAs, and 0.04 μmol HANs per mg of dissolved organic carbon (DOC) were finally determined by correlating the organic content of particles with the nature of the DBPs generated. Comparing the quantities of DBPs generated in filtered and unfiltered samples helps us conclude that ∼50% of DBPs formed during the chlorination of swimming pool water are derived from particles brought by bathers.

Corneal haze post photorefractive keratectomy

Corneal haze represents subepithelial corneal fibrosis, a manifestation of a pathological healing process. It occurs as a result of an epithelial-stromal lesion involving a break in the epithelial barrier. It is an inflammatory response that involves the migration, multiplication and differentiation of keratocytes into mature myofibroblasts, causing loss of corneal transparency. Although it is a transient phenomenon, this complication is feared following refractive photokeratectomy (PRK), because it can cause alterations in the quality of vision, refractive regression and decreased visual acuity. The severity of these symptoms is correlated with the severity of the corneal haze, which can be assessed clinically or by objective means such as corneal densitometry measurement. The frequency and severity of corneal haze increase with the depth of photoablation in PRK and are therefore increased during the treatment of severe ametropia. Considering that no consensus exists, the application of mitomycin C (MMC) intraoperatively and topical corticosteroids postoperatively are conventionally used to inhibit collagen synthesis, sometimes in combination with various protocols depending on the center or surgeon. This review of the literature reports the current knowledge on corneal haze, in order to better understand it and optimise its prevention in the context of a decreased MMC supply, which has occurred in the past and could recur in the future.

A drop does not fall in a straight line: a rationale for the width of stalagmites

Drops loaded in calcium ions detach from stalactites and impact the underlying stalagmites, thereby allowing these latter to grow through calcite precipitation. Nevertheless, little is known about the influence of the drop free fall and splash dynamics on stalagmite shape and width. Through high-speed imaging of impacting drops on stalagmites from several caves, we observed that the impact point position of the drops is scattered, sometimes over several centimetres. We show that this dispersal has no external cause and must, therefore, be self-induced. Using a Langevin-like equation, we then propose a prediction of the impact point dispersal as a function of the falling height travelled by the drops. We finally show that measured stalagmite widths are correlated to the dispersal in the impact point position of the drop.

The properties of new epoxy networks swollen with ionic liquids

In this work, ionic liquids based on trihexyl(tetradecyl)phosphonium associated with bis(2,4,4-trimethylpentyl)phosphinate [TMP] and dicyanamide [DCA] counter anions were used as reactive additives within epoxy/amine networks.

[Abdominal necrotizing fasciitis after caesarean delivery]

Necrotizing fasciitis (NF) is a rare infection (0,2 to 0,4/100,000 adults) of the dermis and hypodermis extending along muscular fascia1. The absence of pathognomonic symptoms makes its diagnosis difficult. Rapidly progressive, it is a life-threatening emergency whose prognosis is letal in 30 % of cases. Treatment of necrotizing fasciitis is mixed and involves aggressive surgical debridement and medical treatment with antibiotics and supportive agents. This article is presenting the case of a young woman who developed abdominal necrotizing fasciitis following a caesarean section. In forty-eight hours, the patient developed septic shock with an extensive and rapid destruction of her abdominal wall. After hysterectomy and multiple surgical debridements, evolution was favorable. After one month, a reconstruction of the abdominal wall could be performed.

[Evaluation of the new Canon HS-100 SD-OCT: Reproducibility of macular ganglion cell complex (GCC) thickness measurement in normal, hypertensive and glaucomatous eyes]

PURPOSE

To evaluate intra- and interobserver reproducibility of macular GCC thickness measurement by automated segmentation on the Canon HS-100 SD-OCT (Tokyo, Japan) in normal (N), hypertensive (OHT) and glaucomatous eyes.

METHODS

A total of 179 eyes of 93 patients were included: 90 N, 28 OHT and 36 early glaucoma and 25 advanced glaucoma. All patients underwent a complete ophthalmologic exam, central corneal thickness and 24-2 standard automated perimetry (HFA SITA standard). Each of two observers performed three macular acquisitions with the Canon OCT HS-100. Acquisitions were analyzed with the Glaucoma 3D mode, which estimated the macular GCC thickness in global, superior and inferior hemisectors, and in eight separate macular areas. Reproducibility was assessed by intraclass correlation coefficient (ICC), coefficient of variation (CV) and test-retest variability (TRTV) calculated as 1.96 times the standard deviation.

RESULTS

Mean GCC thickness was respectively 92.4 μm, 89.0 μm, 80.7 μm and 71.2 μm in N, OHT, early and advanced glaucomatous eyes. In all groups, intra- and interobserver reproducibility ranged respectively for ICC from 89.8 to 99.8% and from 90.2 to 99.4%, for CV from 0.43 to 1.95% and from 0.58 to 2.16% and for TRTV from 0.8 to 3.22 μm and from 1.04 to 3.53 μm. GCC thickness measurements using the new HS-100 SD-OCT were highly reproducible. However, in the advanced glaucoma group, while the reproducibility of GCC thickness measurement is good in the average, superior and inferior hemisectors of the macula, it was slightly less for the paracentral sectors, especially inferior. These sectors correspond generally to the areas most affected by glaucoma.

CONCLUSION

The reproducibility of GCC thickness measurements using the new Canon HS-100 SD-OCT is high for normal, OHT, and glaucomatous eyes. It is thus a reliable and reproducible ancillary test available to the clinician for the examination of glaucomatous optic neuropathies.

Inside the structure of a nanocomposite electrolyte membrane: how hybrid particles get along with the polymer matrix

Hybrid materials remain the target for a fruitful range of investigations, especially for energy devices. A number of hybrid electrolyte membranes consisting of inorganic and organic phases were then synthesized. Mechanical, solvent uptake and ionic transport properties were studied with the key point being the characteristic length scale of the interaction between the phases. A group of nanocomposite membranes made of polystyrenesulfonic acid-grafted silica particles embedded in a Poly(Vinylidene Fluoride-co-HexaFluoroPropene) (PVdF-HFP) matrix was studied by combining neutron and X-ray scatterings on the nanometer to angstrom scale. This approach allows for the variation in the morphology and structure as a function of particle loading to be described. These studies showed that the particles aggregate with increasing particle loading and these aggregates swell, creating a physical interaction with the polymer matrix. Particle loadings lower than 30 wt% induce a slight strain between both of the subphases, namely the polymer matrix and the particles. This strain is decreased with particle loading between 20 and 30 wt% conjointly with the beginning of proton conduction. Then the percolation of the aggregates is the beginning of a significant increase of the conduction without any strain. This new insight can give information on the variation in other important intrinsic properties.

[Guided bone augmentation in edentulous areas]

The use of autogenous onlay blocks placed together with self-tapping implants can achieve an excellent long-term success rate of individual implants. Autogenous bone chips or deproteinized bovine bone can be used to deal with fenestration and dehiscence defects when used in combination with e-PTFE membranes. The role of DFDBA as space maintainer under barrier membranes cannot be ignored. In most cases PTFE membranes are used because they offer reliable results. The use of a collagen membrane when supported by a bone substitute to maintain space gives good results, although long-term research is required. The future will be however tissue engineering. The principle is that a matrix, carrying stem cells and biological mediators like growth factors, is used. More research involves the use of human stem cells responsible for regeneration of different human tissues.

[The role of the psychiatric nurse in an emergency service]

Since september 1989, 3 psychiatric nurses have been working with the crisis and psychiatric emergencies unit of the emergency service of Saint-Luc Hospital in Brussels (Belgium). In this paper, the authors examine the specific functions of psychiatric nurses in the taking in charge of psychiatric emergencies and functional somatic complaints, as well as their role in relation with the nursing team as a whole.