Commercial Disk Research Articles

Evaluation of phenotypic detection methods for metallo-β-lactamases (MBLs) in clinical isolates of Pseudomonas aeruginosa

Metallo-beta-lactamase (MBL) production in Pseudomonas aeruginosa is a growing issue across the globe. Fast and reliable diagnostic tools are needed for appropriate implementation of infection control measures. In this study we evaluated the performance of three commercial combined disk tests, two EDTA based in-house combined disk tests and the Carba NP test in comparison to molecular detection of MBL genes on 133 meropenem non-susceptible non-duplicate P. aeruginosa clinical isolates. The meropenem/DPA based commercial KPC + MBL-confirm ID kit (Rosco Diagnostica, Denmark) and the MASTDISCS™ ID carbapenemase (Enterobacteriaceae) detection disc set (MAST Diagnostics, UK) showed sensitivities of 31.1 % and 28.8 % and specificities of 69.3 % and 79.6 %, respectively. The total MBL confirm kit (Rosco Diagnostica, Denmark) contains imipenem/DPA and imipenem/EDTA combination disks. Evaluation of the single disk combinations revealed 84.4 % sensitivity and 81.8 % specificity for the imipenem/DPA assay and 86.7 % sensitivity and 51.1 % specificity for the imipenem/EDTA test. Applying both tests simultaneously resulted in a slightly higher sensitivity of 88.9 % but a lower specificity of 48.9 % when compared to the single tests alone. The Carba NP test showed 93.3 % sensitivity and 96.6 % specificity. All phenotypic combined disk tests lacked either sensitivity or specificity for the detection of MBL in P. aeruginosa. The Carba NP test showed excellent test properties, but suffers from drawbacks in handling and high costs. The optimal diagnostic approach needs to be chosen depending on the epidemiological situation, laboratory resources and availability of molecular confirmation tests.

Localization of plastic deformation along shear bands in Vitreloy bulk metallic glass during high pressure torsion

Microscopic plastic behavior of high purity commercial Vitreloy 1b glassy disks subjected to high pressure torsion was investigated by analyzing the distortion of a marker grid produced by focused ion beam milling. Scanning electron microscopy and atomic force microscopy are applied to measure offsets of shear bands at the surface. Unlike in other macroscopic deformation tests, short and wavy shear bands with submicron offsets and substantial normal offset components are observed indicating concurrent formation of numerous bands. Material pile-ups along major shear bands result in healing of the glass counterparts.

Mucoadhesive chitosan films as a potential ocular delivery system for ofloxacin: preliminary in vitro studies

The objective of the study is to evaluate the physical properties, in vitro release profile, and antibacterial efficiency of chitosan films prepared with ofloxacin. Mucoadhesive films were prepared by means of a casting and solvent evaporation technique performed in a 2 wt% acetic acid solution and distilled water. Physical properties were characterized by release and swelling studies, differential scanning calorimetry (DSC) analysis, and attenuated total reflectance Fourier transformed infrared spectroscopy (ATR-FTIR) analysis. The in vitro evaluation of the films was performed by inhibiting Staphylococcus aureus and Pseudomonas aeruginosa through activity studies. Circular ofloxacin-loaded chitosan-developed films with 0.3 mg of drug weighed 7 mg were 110 μm thick and 5 mm in diameter. The DSC curve of ofloxacin-loaded chitosan films suggests an amorphous dispersion of ofloxacin within these films. ATR-FTIR analysis showed that ofloxacin is indeed present in the matrix film. The drug was released in vitro over a 1-h period. No statistical difference could be observed between the ofloxacin-loaded chitosan films and sterile disk soaked for 1 min in 0.3% commercial ofloxacin ophthalmic solution for S. aureus and P. aeruginosa (P = 0.1686, P = 0.1172, respectively).The films presented a significantly larger mean bacterial inhibition zone of S. aureus than did the commercial ciprofloxacin control disk (P = 0.0002) and a significantly larger mean bacterial kill zone of P. aeruginosa than did the commercial enrofloxacin control disk (P < 0.0001). Ofloxacin was successively incorporated onto chitosan films and was not inactivated during the process of manufacturing, thus preserving antibacterial proprieties.

Evaluation of the Quality of Commercial Antibacterial Discs Available in Nigeria

Journal of Pharmaceutical Research International (ISSN: 2456-9119) is dedicated to publish high quality papers in all areas of pharmaceutical Science including pharmaceutical drugs, community pharmacy, hospital pharmacy, clinical pharmacy, compounding pharmacy, consultant pharmacy, internet pharmacy, veterinary pharmacy, nuclear pharmacy, military pharmacy, pharmacy informatics, pharmaceutics, medicinal chemistry, pharmacognosy, pharmacotherapy, pharmacodynamics, pharmacokinetics, clinical pharmacology, neuropharmacology, psychopharmacology, pharmacogenetics, pharmacogenomics, pharmacoepidemiology, toxicology, theoretical pharmacology, posology, pharmacognosy, behavioral pharmacology, environmental pharmacology, medicine development and safety testing, drug legislation and safety, pharmaceutical microbiology, pharmaceutical molecular biology, pharmaceutical biotechnology. The journal also encourages the submission of useful reports of negative results. This is a quality controlled, OPEN peer reviewed, open access INTERNATIONAL journal.

Application of enrofloxacin and orbifloxacin disks approved in Japan for susceptibility testing of representative veterinary respiratory pathogens.

ABSTRACTIn this study, susceptibilities of Pasteurella multocida, Mannheimia haemolytica and Actinobacillus pleuropneumoniae to enrofloxacin and orbifloxacin were tested using an agar diffusion method with the commercial disks and a broth microdilution method. Good correlation between the 2 methods for enrofloxacin and orbifloxacin was observed for P. multocida (r = −0.743 and −0.818, respectively), M. haemolytica (r = −0.739 and −0.800, respectively) and A. pleuropneumoniae (r = −0.785 and −0.809, respectively). Based on the Clinical and Laboratory Standards Institute interpretive criteria for enrofloxacin, high-level categorical agreement between the 2 methods was found for P. multocida (97.9%), M. haemolytica (93.8%) and A. pleuropneumoniae (92.0%). Our findings indicate that the tested commercial disks can be applied for susceptibility testing of veterinary respiratory pathogens.

A highly efficient dilute alkali deacetylation and mechanical (disc) refining process for the conversion of renewable biomass to lower cost sugars

The deconstruction of renewable biomass feedstocks into soluble sugars at low cost is a critical component of the biochemical conversion of biomass to fuels and chemicals. Providing low cost high concentration sugar syrups with low levels of chemicals and toxic inhibitors, at high process yields is essential for biochemical platform processes using pretreatment and enzymatic hydrolysis. In this work, we utilize a process consisting of deacetylation, followed by mechanical refining in a disc refiner (DDR) for the conversion of renewable biomass to low cost sugars at high yields and at high concentrations without a conventional chemical pretreatment step. The new process features a low temperature dilute alkaline deacetylation step followed by disc refining under modest levels of energy consumption. The proposed process was demonstrated using a commercial scale Andritz double disc refiner. Disc refined and deacetylated corn stover result in monomeric glucose yields of 78 to 84% and monomeric xylose yields of 71 to 77% after enzymatic hydrolysis at process-relevant solids and enzyme loadings. The glucose and xylose yields of the disc refined substrates in enzymatic hydrolysis are enhanced by 13% and 19%, respectively. Fermentation of the DDR substrates at 20% total solids with Z.mobilis utilized almost all sugars in 20hrs indicating the sugar hydrolyzate produced from the DDR process is highly fermentable due to low levels of chemical contaminants. The ethanol titer and ethanol process yield are approximately 70 g/L and 90% respectively. The proposed new process has been demonstrated using pilot scale deacetylation and disc refiners. The deacetylated and disc refined corn stover was rapidly deconstructed to monomeric sugars at 20% wt solids with enzymatic hydrolysis. High process sugar conversions were achieved, with high concentrations of monomeric sugars that exceeded 150 g/L. The sugar syrups produced were found to have low concentrations of known major fermentation inhibitors: acetic acid, furfural and HMF. The low levels of these fermentation inhibitors lead to high fermentation yields. The results suggest that this process is a very promising development for the nascent cellulosic biofuels industry.

Multirate Adaptive Compensation of Uncertain Resonances Beyond the Nyquist Frequency

In this paper, an add-on multirate adaptive control scheme is proposed for compensation of uncertain mechanical resonant modes beyond the Nyquist frequency in mechatronic systems. A polynomial transformation technique is applied to obtain the mixed-rate model of the control system that is suitable for multirate adaptive control design. To preserve the performance of the pre-designed nominal controller, an auxiliary error is utilized in the parameter estimation process instead of tracking error. The proposed multirate adaptive control combined with a Recursive Least-Squares (RLS) algorithm and a dead-zone ensures boundedness of all the closed-loop signals and convergence of the auxiliary error. Our simulation results on the model of the Voice Coil Motor (VCM) actuator in a commercial Hard Disk Drive (HDD) demonstrate the effectiveness of our proposed compensation scheme in attenuating the mechanical resonances beyond the Nyquist frequency.

Bacterial Aetiological Agents of Vended Foods in Vom, Plateau State, Nigeria

Aims: Foodborne diseases are multifactorial in origin and are major cause of death worldwide. This study was aimed at detecting the presence of bacterial pathogens in already prepared vended foods in Vom. Methodology and results: Two hundred (200) cooked food (ready-to-eat) samples were subjected to bacteriological examinations using differential, selective and enriched culture media. A total of 228 bacterial isolates were obtained. These includes Aeromonas hydrophila (3)1.5%, Bacillus species (32)16%, Citrobacter freundii (18)9%, Citrobacter braekii (9)4.5%, Citrobacter youngae (1)0.5%, Chryseomonas luteola (1)0.5%, Enterobacter cloacae (28)14%, Escherichia coli (14)7%, Klebsiella pneumoniae (6)3%, Kluyvera species (1)0.5%, Morganella morganii (3)1.5%, Providencia species (4)2%, Pseudomonas aeruginosa (5)2.5%, Proteus mirabilis (2)1%, Salmonella species (12)6%, Staphylococcus aureus (34)17%, coagulase negative Staphylococcus (49)24.5%, Streptococcus faecalis (5)2.5% and Vibrio hollisae (1)0.5%, twenty one (21) samples had no bacterial growth. The identification of the Gram-negative organisms were confirmed using API 20E. These isolates were further subjected to antimicrobial sensitivity testing using the Abtex commercial disc. Most isolates were resistant to Amoxycillin, Cloxacillin, Cotrimoxazole and Erythromycin. Ciprofloxacin had about 99% activity against all the isolates. Conclusion: The isolation of bacterial pathogens is indicative of bacterial contamination in vended foods in Vom within the period of the study.

Magnetoplasmonic crystals based on commercial digital discs

Transversal magneto-optical Kerr effect (TKE) controlled by surface plasmon-polariton resonances is studied in nickel and combined silver/nickel magnetoplasmonic crystals fabricated on the base of commercial digital discs with periods of 320 nm, 740 nm, and 1500 nm. Wood's anomaly is observed in visible and near IR spectral ranges due to fulfilment of phase-matching conditions between surface plasmons and −1, −2, and +1 diffraction orders for the samples with these periods, respectively. Strong asymmetrical Fano-shape resonances are observed in TKE spectra in the vicinity of surface plasmons' resonances.

Antibiotic Resistance in Enterococcus faecalis Isolated from Hospitalized Patients.

Background and aims Enterococci are Gram-positive cocci that often occur in pairs (diplococci) or short chains. Be-side developing high level of antibiotic resistance, these bacteria can cause wide range of disease in human, thus to help provide an effective treatment for infections caused by this genus, this study was conceived to provide information on Enterococcus faecalis Antibiotic resistance to widely used antibiotics in hospitalized patients. Materials and methods Disk diffusion agar and Broth dilution methods were used to perform Antibiogram test on isolated Enterococcus faecalis. Culture medium used for Disk diffusion agar test was Muller Hinton agar, and for Broth dilution methods, Muller Hinton broth culture medium was utilized. In disk diffusion agar method, different commercial antibiotics disks produced by Pharmaceutical companies were used. Microsoft Excel software was used to perform statistical analysis. Results Based on antibiograms of 105 cases, a high resistance to Synercid, Nalidixic acid, Oxacillin and Teofilin was de-tected whereas the lowest resistance observed in Nitrofurantoin, Vancomycin, Linezolid and Teicoplanin antibiotics. Conclusion According to the results, Teicoplanin, Vancomycin, Linezolid and Nitrofurantoin are recommended against E. faecalis species.

Silk fibroin biopolymer films as efficient hosts for DFB laser operation

Biopolymer hosts can be successfully used for the fabrication of multifunctional photonic devices due to their good optical properties, biocompatibility, remarkable mechanical properties and a wealth of chemical functionalization. Particularly, the silk fibroin (SF) biopolymer presents a wide range of suitable properties for photonic applications that were not fully exploited. In the present work, we demonstrate the operation of a distributed feedback (DFB) laser based on SF films doped with Rhodamine 6G (Rh6G) dye and films containing Rh6G and silica or silver nanoparticles. The SF grating structures were fabricated using a commercial blank digital versatile disc (DVD) as the template. The addition of silica or silver nanoparticles to the SF film led to enhanced emission due to the multiple scattering of light by the silica nanoparticles and a reduction of the emission linewidth. The laser wavelength was centered between ≈560 and ≈575 nm corresponding to the fourth-order diffraction of a 750 nm period of the SF grating. The results show that regenerated SF films are promising matrices for DFB lasers because of the excellent optical quality and large potential for biomedicine regarding biocompatibility and benign processing conditions.

Ultrathin Si/C graded layer to improve tribological properties of Co magnetic films

An ultrathin Si layer (≤1 nm) deposited on Co magnetic films was bombarded with energetic C+ ions to form a Co/Si/C mixed layer. This layer improved the tribological properties of the Co film as compared with those of a commercial hard disk media with 3.0 nm carbon overcoat and 1.4 nm of lubricant. Formation of a network of C-C and Si-C bonds at the outermost layer and the bulk of the Si/C film as well as formation of chemical bonds between the Co surface and the mixed layer was found as the main factors to improve the tribological properties.

Writing Process Induced Media Noise Measurement

Writing processes can cause extra medium noise, which is the dominant noise in the perpendicular recording system. This work describes the methodology of using averaging methods to measure the writer footprints and its noise profiles, which are recorded at different writing currents on a Spin-stand. Two different commercial heads have been used for the evaluation. The test is performed on a 2.5 inch commercial disc at the middle diameter (MD) location, rotating at 5400 RPM spindle speed, and at 0 skew angle. The center track is DC erased over an AC erased background and then recorded with a repetitive footprint data pattern and an alignment data pattern. Multiple revolution averaging and down track footprint averaging are used to retrieve the noise free footprint profile of the writer. Using the noise free footprint profile, the statistical characteristics of noise can be derived from the individual noisy footprint which shows the media noise characteristics induced by writing process. Using footprint and noise profile data, signal to noise ratio (SNR) for regions near the trailing edge of the writer profile are calculated and suggests that the ideal writing condition for writer A and B to be 55 and 25 mA respectively.

Development of a compact micro-stereolithography (MSTL) system using a Blu-ray optical pickup unit

In this paper, a compact micro-stereolithography (MSTL) apparatus of tabletop size was designed and constructed using a Blu-ray optical pickup unit (OPU), which came from a commercial Blu-ray optical disk driver. This is the very first application of a Blu-ray OPU to a light source of a MSTL system. A three-axis stage was adopted to obtain 3D motions, and a simple optic system was added to extend the focal length of a Blu-ray OPU for avoiding the physical interference. A liquid photo-curable resin suitable for the system was recomposed by modifying previously reported one. Then, the fabrication characteristics were investigated by constructing single-line structures at varying parameters such as laser power, scan speed and aperture diameter. The cured depth and width of the single-line structures decreased as the irradiated energy, which is determined by laser power and scan speed, decreased. Interestingly, the result also showed that the aperture diameter can effectively control the aspect ratio of cured depth and width. The increase of aperture diameter brings about the decrease of cured depth and increase of cured width. Based on the results of single-line exposure experiment, various 3D micro-structures were successfully fabricated. From this study, it can be shown that the Blu-ray-based MSTL system and the resin are suitable for fabricating complicated 3D micro-structures with reproducibility.

마이크로 캔틸레버 굽힘 측정을 위한 센싱시스템

. Abstract: This paper presents a sensing system to measure the deflection of a microcantilever in an atomic force microscope. In general, the optical lever method and interferometry are used for the sensing system; however, their size and cost leaves considerable room for improvement. Therefore, we used an optical pickup head whose operating principle is based on the astigmatism of the commercial optical disk drives. The developed sensing system was applied to a laboratory atomic force microscope, and satisfactory results were obtained.

Robust vibration control at critical resonant modes using indirect-driven self-sensing actuation in mechatronic systems

This paper presents an improved indirect-driven self-sensing actuation circuit for robust vibration control of piezoelectrically-actuated flexible structures in mechatronic systems. The circuit acts as a high-pass filter and provides better self-sensing strain signals with wider sensing bandwidth and higher signal-to-noise ratio. An adaptive non-model-based control is used to compensate for the structural vibrations using the strain signals from the circuit. The proposed scheme is implemented in a PZT-actuated suspension of a commercial dual-stage hard disk drive. Experimental results show improvements of 50% and 75% in the vibration suppression at 5.4kHz and21kHz respectively, compared to the conventional PI control.

An evaluation of the Mast D69C AmpC Detection Disc Set for the detection of inducible and derepressed AmpC -lactamases

Sir, The emergence of Enterobacteriaceae that can produce AmpC b-lactamases is a major worldwide concern. They have arisen through acquisition of a plasmid-mediated ampC gene or hyperproduction of an inducible chromosomal AmpC enzyme, either by induction or derepression. These organisms are resistant to penicillins, first-, secondand third-generation cephalosporins and b-lactamase inhibitor/b-lactam combinations. Therapeutic options to treat these infections are severely limited and often not included in empirical therapy guidelines for serious infections. Rapid detection of AmpC-producing Enterobacteriaceae is therefore essential in order that patients can be optimally managed at an early stage without indiscriminate use of broad-spectrum antibiotics. Methods available for the detection of AmpC producers are relatively unsatisfactory and there are no established guidelines, as there are for the detection of extended-spectrum b-lactamase (ESBL)-producing organisms. We evaluated the commercial D69C AmpC Detection Disc Set (Mast Group Ltd, UK). This system is based on a combination disc method that incorporates cefpodoxime (CPD10) as the screening agent in the presence of AmpC-inducing or -inhibiting agents (exact formulations undisclosed), enabling the detection of both plasmid-mediated and chromosomal AmpC, whether inducible or derepressed. An ESBL inhibitor is additionally included to unmask and minimize interference from any ESBL that may be present on the AmpC detection system. Three discs are used: A (CPD10+AmpC inducer), B (CPD10+AmpC inducer+ESBL inhibitor) and C (CPD10+AmpC inducer+ESBL inhibitor+AmpC inhibitors). A total of 103 previously characterized isolates (comprising 80 AmpC+, 15 AmpC2/ESBL+, 1 AmpC2/KPC+ and 7 AmpC2/ ESBL2 strains) were blindly tested using the detection kit. These isolates were a combination of reference strains and clinical isolates that had been characterized by genotypic or disc diffusion methods, and included strains with chromosomal derepressed, inducible and plasmid-mediated AmpC resistance mechanisms. The Enterobacteriaceae represented were Escherichia coli, Klebsiella pneumoniae, Morganella morganii, Citrobacter freundii, Enterobacter cloacae, Enterobacter aerogenes and Serratia marcescens. Testing and interpretation were performed according to the manufacturer’s instructions. Isolates were sub-cultured onto Mueller–Hinton agar to achieve semi-confluent growth. The three discs were placed on the plate as far apart as possible, and the plate was incubated at 378C in air for 18–24 h. The organisms were interpreted as ‘AmpC negative’ if all zone sizes differed by ≤3 mm and as ‘AmpC positive’ if the zone size of disc C exceeded those of both discs A and B by at least 5 mm. If zone sizes of both discs B and C exceeded that of disc A by at least 5 mm and the zone sizes of discs B and C had a difference of ,5 mm, the isolate was classified as ‘AmpC negative, but exhibits a different resistance mechanism’. As shown in Table 1, The D69C kit correctly determined the AmpC status of all 80 AmpC+ and 23 AmpC2 isolates tested. Amongst the 23 AmpC2 isolates, 12 out of the 15 AmpC2/ ESBL+ isolates and the 1 AmpC2/KPC+ isolate were correctly classified as ‘AmpC negative, but exhibits a different resistance mechanism’. All seven AmpC2/ESBL2 isolates were correctly identified as ‘AmpC negative’. The kit failed to detect the presence of a different resistance mechanism in 3 out of 15 AmpC2/ESBL+ isolates—they were an SHV ESBL+ K. pneumoniae, a TEM/CTX-M ESBL+ E. coli and a TEM/SHV+ ESBL+ E. coli. There is no immediate explanation for these results, particularly since several other TEM, SHV and CTX-M ESBL+ isolates were correctly identified as ‘exhibiting another resistance mechanism’. The ESBL activity might have been masked by the AmpC inducer (incorporated into all three discs), and hence these results highlight an important limitation of the D69C kit, i.e. it is solely a method for AmpC detection, and its use cannot be extrapolated to ESBL detection. The ESBL inhibi-

In-vitro antibacterial activity of herbal aqueous extract against multi-drug resistant &lt;em&gt;Klebsiella sp.&lt;/em&gt; isolated from human clinical samples

The studies were carried out to evaluate antibacterial activity of 35 aqueous herbal extracts against a total of 20 clinical Klebshiella sp. isolates. The maximum antibacterial activity was found as 90% in crude extracts of Syzygium aromaticum (leaf) and Citrus limon L. (fruit) followed by 85% in Spondias pinnata (leaf). Sensitivity of these isolates was also evaluated for eight commercial antibiotic discs following disc diffusion assay where most of the isolates found to develop resistance against multiple commercial antibiotics. 85% of isolates exhibited resistant to chloramphenicol and erythromycin and 80% were resiatant to sulfamethoxazole and cephradine. The isolates showed their resistance between 55-60 % to the other four antibiotic discs, viz; gentamycin, streptomycin, ciprofloxacin and azithromycin. Among 35 herbal extracts tested, 19 herbal extrats were found to possess antimicrobial activity in all multi-drug resistant isolates. Therefore these herbal extracts could be used in future direction as alternative therapeutic agents for the treatment of human diseases caused by Klebsiella sp. DOI: http://dx.doi.org/10.3329/icpj.v1i6.10534 International Current Pharmaceutical Journal 2012, 1(6): 133-137

Pattern transfer nanomanufacturing using magnetic recording for programmed nanoparticle assembly

We report a novel nanomanufacturing technique that incorporates patterned arrays built entirely from Fe3O4 nanoparticles into a flexible and transparent polymer film. First, the nanoparticles are patterned using the enormous magnetic field gradients at the surface of commercial disk drive media, and then the resulting architecture is transferred to the surface of a polymer film by spin-coating and peeling. Since the particles are immobilized by the field gradients during the spin-coating process, the patterned array is preserved after peeling. To demonstrate the potential of this technology, we fabricate a 5 mm diameter all-nanoparticle diffraction grating capable of producing a white-light optical spectrum. We also demonstrate several extensions to this technology, where, by adding an external magnetic field during assembly, we create both periodic variations in topography, as well as a nanocomposite with two vertically and horizontally separated nanoparticle layers. As this technique leverages the nanometer resolution inherent in current magnetic recording technology, strong potential exists for low-cost nanomanufacturing of optical and electronic devices from a variety of nanomaterials with ∼10 nm resolution.

Laser Cutting Technology — A Commercial Perspective

AbstractSince the advent of commercial fibre and disk laser cutting machines there has been a lot of controversy about the performance of these devices – particularly in comparison to their more established CO2 counterparts. In the early days the sales staff promoting fibre technology would often declare that the new lasers would completely take over from CO2 technology very quickly – but this has not happened. Even taking into account the entrenched position of the older technology, fibre and disk lasers have not been as widely accepted as was predicted, although they have been proven to outperform CO2 lasers in certain important areas.This article presents a discussion of the advantages and disadvantages of both types of cutting technology from a commercial point of view – written from the perspective of a laser cutting jobshop owner trying to decide between buying a fibre or CO2 laser cutting machine.