Many antiseptics have been used to treat wounds.
To compare the microbicidal efficacy of ClHO (Clortech®) with other antiseptics used on wounds, healthy skin and mucous membranes.
The microbicidal ...efficacy of 13 antiseptic products on eight micro-organisms (three Gram-positive; three Gram-negative; two yeasts) inoculated on organic germ-carriers was studied. In addition, the loss of efficacy against Staphylococcus aureus and Pseudomonas aeruginosa with biofilm was assessed with the six best-performing products.
Chlorhexidine (1%) had the highest microbicidal effect at 1 min. At 5 min, 500 and 1500 mg/L ClHO showed similar, or better, activity than the other antiseptics studied. The ClHO concentration of 300 mg/L achieved this same efficacy at 10 min. The product that lost the most efficacy due to biofilm was 1% chlorhexidine, while 1% PVP-I and ClHO at either 300 or 500 mg/L were moderately affected by biofilm. The most effective in the presence of biofilm was ClHO at 1500 mg/L.
ClHO at medium–low concentrations (300 or 500 mg/L) is a good antiseptic that can be used on wounds and mucous membranes for 5–10 min. Lower concentrations of ClHO, as well as of the other antiseptics studied, were less effective or more altered by the biofilm. ClHO at a concentration of 1500 mg/L is very effective in the presence or absence of biofilm that can be used on healthy skin for 5 min.
This letter presents a 4 × 4 single-layer dual-band array antenna operating in the K- and Ka-band using gap waveguide (GW) technology. Radiating elements consist of I-shaped slots located on the top ...plate of the antenna and backed by a novel coaxial cavity with the dual-frequency operation. The antenna presents two ports, one for each band, and radiates a directive far field pattern with linear polarization. A single-layer wideband corporate-feed network is used to excite the cavities. In addition, a diplexer is integrated as part of the network to separate both working bands. Experimental results show impedance and radiation pattern bandwidths larger than 2 GHz in both bands.
We present, for the first time to our knowledge, experimental demonstration of tunable optical beamforming for phased array antennas using a few-mode fiber. The double-clad step-index few-mode fiber ...is dispersion engineered such that it operates as a continuously tunable 5-sample true-time delay line, enabling continuous steering of the beam-pointing angle. Using this approach, we measure the radiation pattern from 5 elements of an in-house fabricated 8-element phased array antenna at the radiofrequency of 26 GHz and demonstrate continuous beam-steering over a 59° range by sweeping the optical wavelength from 1543 nm up to 1560 nm. Such a few-mode fiber-based beamformer could be beneficial to next-generation fiber-wireless communications and radar systems, as it provides further versatility and capacity along with reduced size, weight and power consumption.
Summary Microbial contamination of hospital surfaces may be a source of infection for hospitalized patients. We evaluated the efficacy of Glosair™ 400 against two American Type Culture Collection ...strains and 18 clinical isolates, placed on glass germ-carriers. Carriers were left to air-dry for 60 min and then exposed to a cycle before detection of any surviving micro-organisms. Antibiotic-susceptible Gram-negative bacilli were less susceptible (although not significantly) to this technique than resistant Gram-negative bacilli or Gram-positive cocci and yeasts (3, 3.4 and 4.6 log10 reduction, respectively). In conclusion, in areas that had not been cleaned, aerosolized hydrogen peroxide obtained >3 log10 mean destruction of patients' micro-organisms.
Waveguide slot arrays are a widely used solution to attain linearly polarized high-gain antennas. In this article, an all-metal T-shaped radiating element is conceived with the aim to replace the ...usual rectangular slots and attain circularly polarized arrays, preserving their good properties. The polarization conversion is made possible due to the inclusion of a parasitic arm perpendicular to the main active slot. Due to the fact that this second arm is not directly fed by the waveguide but coupled to the active slot, the T-shaped element can be used in any array originally formed by metallic rectangular slots. The design of resonant shunt arrays has been addressed here for validation purposes. The experimental results of two sample linear arrays at 30 GHz demonstrate the design accuracy and manufacturing reliability, reporting an axial ratio below 2 dB within a bandwidth of 1.9 GHz and a peak efficiency around 98%.
A V-band single-layer low-loss slot-array antenna is presented in this letter. Radiating slots are backed by coaxial cavities, which are fed through a groove gap waveguide E-plane corporate feed ...network. Cavity resonances are created by shortening nails with respect to the surrounding ones. This fact enables a compact single-layer architecture since coaxial cavities and feeding network can share the same bed of nails. A 16 × 16 array is designed, constructed, and measured to demonstrate the viability of this concept for high-gain single-layer slot-array antennas. In addition, this solution can be extended to circular polarization by seamlessly adding a polarizer above the slots without changing the feeding network piece. Measurements show a relative bandwidth of 10% with input reflection coefficient better than <inline-formula><tex-math notation="LaTeX">-</tex-math></inline-formula>10 dB and a mean antenna efficiency above 70% within the operating frequency band (57-66 GHz)
In this letter, a half-mode waveguide based on gap waveguide (GW) technology for rapid prototyping is explored. Two devices have been designed and measured for demonstration purposes: a power divider ...and a curved waveguide. Both devices are constructed from two noncontacting metal pieces. Both devices also follow the same design process. In the bottom piece, a horizontally polarized groove GW (GGW) is housed. The height of the groove is about half, which is required to propagate the fundamental mode. The top cover is a uniform pinned surface that acts as a high impedance surface (HIS) over the groove below. Both the power divider and the curved waveguide show measured reflection coefficient values of less than −15 dB in the bandwidth of interest (28-31 GHz) and are in excellent agreement with simulated results. These devices stand out for their ease of fabrication and open a horizon for cheaper and more robust GW designs for mass production.
Antibiotic resistance and decreased susceptibility to disinfectants are not usually associated in microorganisms, but we have found an exception to this rule: P. aeruginosa versus orthophthalaldehyde ...(OPA).
Bactericidal effect of OPA was measured at 10 minutes on endodoncy files contaminated with an ATCC strain (control) or 206 strains of P. aeruginosa recently isolated from 206 ICU and paraplegic patients in a tertiary university hospital, in two consecutive years.
Differences in bactericidal effect of OPA were found between the strains isolated each year (decreased susceptibility in the first period), but in both years the statistical differences (p < 0.05) were maintained according to whether the strains were "susceptible" to antibiotics, "resistant" (to one family of antibiotics) or "multi-resistant" (resistant to more than one family of antibiotics), exhibiting a reduction in their OPA susceptibility in parallel to an increase of their antibiotic resistance. In contrast, there were no differences depending on the type of sample (sputum, urine, faeces, pharynx) or of patient (paraplegic or ICU: adult, newborn, burn). Finally we selected 15 strains with an OPA effect below 3.5 log10 at 10 minutes and repeated the study with an OPA exposure of 15 minutes. In these conditions OPA showed a total bactericidal effect on these P. aeruginosa strains.
There was an association between antibiotic resistance and decreased OPA susceptibility. This normally does not require an increase in disinfection time, but, for endoscope disinfection or instruments from colonized/infected patients with resistant/multiresistant P. aeruginosa, we consider it better to use 15 min of OPA. Regular tests (e.g., once every 12 months) with germ-carriers, should be performed to assess ecological changes in susceptibility to high level disinfectants and must include not only ATCC strains, but also recently isolated microorganisms with different antibiotic sensitivities (susceptible, resistant and multi-resistant).
The use of alcohol-based hand rubs serves to reduce hospital-acquired infections. Many products of this type are now on offer and it is essential to know how to rank their efficacy. A sequence of ...tests is proposed here to compare any given new alcohol-based solution against the reference solution (60% 2-iso-propyl-alcohol) with 30 s of contact time: (i) in vitro (with pig skin as carrier) testing of >30 species of microorganism; (ii) in vitro assessment of residual efficacy (after 30 min of drying); (iii) in vivo study of transient microbiota (modification of the EN 1500 standard procedure) using four ATCC strains; (iv) in vivo study of resident hand microbiota. After performing the in vitro evaluation of seven alcohol-based hand rubs, the two most efficacious (chlorhexidine-quac-alcohol and mecetronium-alcohol) were chosen and studied, comparatively with the reference solution (60% iso-propyl alcohol), in vitro (for chemical sustainability on the skin) and in vivo (against transient and resident microbiota). Chlorhexidine-quac-alcohol proved to be significantly superior to mecetronium-alcohol or the reference solution in all tests, except against resident microbiota for which the improvement was not statistically significant.
An H-shaped all-metal radiating element comprising an active and a coupled slot has been proposed to design wideband high-efficiency circularly polarized antenna arrays. The proper excitation of ...several modes on the coupled slot enables a wide axial ratio (AR) bandwidth with high circular polarization (CP) purity. To feed an array of such radiating elements, a simple and scalable two-layer corporate network, implemented in groove gap waveguide (GGW) technology, is conceived. Those good frequency properties have been confirmed by the fabrication of a prototype, whose experimental results report a 1-dB AR bandwidth of 22%. In addition, a peak radiation efficiency of 97% with good pattern stability and an impedance bandwidth of 21% with high return loss have been measured. The high CP purity demonstrated by these wideband apertures makes them particularly suitable for Ka-band satellite communications' antennas.
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