Sarabjit Singh

Challenges in reporting surgical site infections to the national surgical site infection surveillance and suggestions for improvement

INTRODUCTIONnMandatory orthopaedic surgical site infection (SSI) data in England are used as a benchmark to compare infection rates between participating hospitals. According to the national guidelines, trusts are required to submit their data for at least one quarter of the year but they are free to report for all quarters. Owing to this ambiguity, there is a concern about robust reporting across trusts and therefore the accuracy of these data. There is also concern about the accuracy of collection methods. The aim of this five-year retrospective study was to assess the accuracy of SSI reporting at two hospitals in South East England under the same trust.nnnMETHODSnA retrospective review was carried out of five years of electronic medical records, microbiology data and readmission data of all patients who underwent hip and knee replacement surgery at these hospitals. These data were validated with the data submitted to Public Health England (PHE) and any discrepancy between the two was noted.nnnRESULTSnA significant difference was found in the SSI rates reported by the surveillance staff and our retrospective method.nnnCONCLUSIONSnOur study confirms the findings of a national survey, which raised concerns about the quality of SSI reporting and the usefulness of PHE SSI data for benchmarking purposes. To our knowledge, there are no previously published studies that have looked at the accuracy of the English orthopaedic SSI surveillance. In the light of our findings, there is an urgent need for external validation studies to identify the extent of the problem in the surveillance scheme. The governing bodies should also issue clear guidelines for reporting SSIs to maintain homogeneity and to present the true incidence of SSI. We suggest some measures that we have instituted to address these inadequacies that have led to significant improvements in reporting at our trust.

Structural, ferroelectric and piezoelectric properties of chemically processed, low temperature sintered piezoelectric BZT–BCT ceramics

0.5Ba(Zr0.2Ti0.8)O3–0.5(Ba0.7Ca0.3TiO3) nanopowders were synthesized at very low temperature using a soft chemical approach. The synthesized powders and the consolidated disks were structurally characterized thoroughly by XRD, SEM, TEM and EPMA and also by ultraviolet and Raman spectroscopy. The 1350 °C sintered BZT–BCT disk displayed the highest density, underwent diffused phase transition centered at ~100 °C and showed the highest dielectric constant (8917) and lowest dielectric loss (0.015). The sintered BZT–BCT sample with the highest density showed a maximum polarization (P max) of 13 μC cm–2 and remnant polarization of 6 μC cm–2. The same sample exhibited very high electrostrain of ~0.12% under a relatively low electrical field of 3.5 kV mm−1.

EFFECT OF COMPOSITIONAL MODIFICATIONS ON DIELECTRIC, FERROELECTRIC AND PYROELECTRIC RESPONSE OF PMN-PT SOLID SOLUTIONS NEAR MPB

Morphotropic phase boundary (MPB) compositions of (1-x)PMN-(x)PT system, where x=0.30, 0.32 and 0.34, were prepared in single perovskite phase by the B-site Columbite precursor method. Temperature dependence of dielectric behavior, measured at different frequencies, revealed the transformation of the system from relaxor to normal ferroelectric behavior and decrease in dielectric dispersion near transition temperature (Tc) with the increase in PT content. Appearance of an abnormal hump in the dielectric behavior of PMNT 68/32 composition confirms the MPB nature of the system. Remnant polarization, Pr was found to be ~ 23, 22 and 27 μC/cm2, whereas coercive field, Ec was found to be ~ 3.3, 3.9 and 3.6 kV/cm for PMNT 70/30, 68/32 and 66/34 compositions respectively. Strain versus electric field (S-E) behavior revealed the piezoelectric nature of these compositions with a maximum strain ~ 0.75% at 31 kV/cm applied electric field in PMNT 68/32 composition. Temperature variation of the pyroelectric coefficient,...

Structural and Dielectric Properties of PMN-PT (65/35) Bulk Ceramics Synthesized by Metal-Polymer Gel Auto Ignition Route

Ultra-fine PMN-PT (65/35) powder was synthesized following a polymer precursor based chemical synthesis technique. The auto-ignited powder containing negligible amounts of carbonaceous residue (∼0.6 wt%) could be sintered directly without any further calcination. A mixture of perovskite and pyrochlore phase was detected in the auto-ignited powder by XRD analysis. The amount of pyrochlore phase decreased with increasing the annealing temperature and pure perovskite phase was obtained in the sample at 950°C. Scanning electron microscopy of the uniaxially pressed and sintered samples revealed the rectangular shaped grains. The dielectric properties of the sintered pellets were measured at room temperature.

STRUCTURAL AND DILATOMETRIC PROPERTIES OF LANTHANUM-SUBSTITUTED PCT CERAMICS

Pb0.76-3x/2LaxCa0.24Mn0.02Ti0.98O3 (PLCT), x=0–0.08 (in steps of 0.02), ceramics were prepared by conventional mixed oxide technique. The samples were sintered at an optimized temperature of 1150°C. Phase and microstructural analysis were carried out using X-ray Diffraction (XRD) and scanning electron microscope (SEM) to study the effect of lanthanum on PCT ceramics. Both experimental and theoretical densities for all the samples were also determined. Phase analysis shows the single-phase material with tetragonal structure and the decrease in tetragonality is observed with the increase in the amount of lanthanum in the base composition. Detailed dilatometric investigations were performed in order to study the shrinkage behaviour and dominating shrinkage mechanism in the present system.

Effect of strain rate, off-axis loading and high-velocity impact damage on the compressive strength of C/SiC composite:

The compressive strength of C/SiC composite at different strain rates, off-axis orientations and after high-velocity impact was studied. The compressive strength was found to be 137u2009±u200923, 130u2009±u200946 and 162u2009±u200933u2009MPa at a strain rate of 3.3u2009×u200910−5, 3.3u2009×u200910−3, 3.3u2009×u200910−3 s−1, respectively. On the other hand, the compressive strength was found to be 130u2009±u200946, 99u2009±u200923 and 87u2009±u20099u2009MPa for 0°/90°, 30°/60° and 45°/45° fibre orientations to loading direction, respectively. After high-velocity impact, the residual compressive strength of C/SiC composite was found to be 58u2009±u200926, 44u2009±u200918 and 36u2009±u20093.5u2009MPa after impact with 100, 150 and 190u2009m/s, respectively. The formation of kink bands in fibre bundles was found to be dominant micro-mechanism for compressive failure of C/SiC composite for 0°/90° orientation. On the other hand, delamination and the fibre bundles rotation were found to be the dominant mechanism for off-axis failure of composite.

Ferroelectric Properties of Laser Ablated Sm Modified PCT Thin Films

Crystallized thin films of samarium modified lead calcium titanate ceramics with composition; Pb0.66Sm0.08Ca0.24Mn0.02Ti0.98O3 were deposited under different annealing and laser energy conditions. Thin films deposited at these conditions show a surface roughness, coercive field and remnant polarization in the range of 1.9–6.0 nm, 120–220 kV/cm and 4–11.5 μC/cm2, respectively. I-V and C-V measurements were also performed in order to study the electrical behaviour of the films.