Lattice constant measurement from electron backscatter diffraction patterns.

Kikuchi bands in election backscattered diffraction patterns (EBSP) contain information about lattice constants of crystallographic samples that can be extracted via the Bragg equation. An advantage of lattice constant measurement from EBSPs over diffraction (XRD) is the ability to perform local analysis. In this study, lattice constants of cubic STN and cubic YSZ in the pure materials and in co-sintered composites were measured from their EBSPs acquired at 10 kV using a silicon single crystal as a calibration reference. The EBSP distortion was corrected by spherical back projection and Kikuchi band analysis was made using in-house software. The error of the lattice constant measurement was determined to be in the range of 0.09-1.12% compared to values determined by XRD and from literature. The confidence level of the method is indicated by the standard deviation of the measurement, which is approximately 0.04 Å. Studying Kikuchi band size dependence of the measurement precision shows that the measurement error decays with increasing band size (i.e. decreasing lattice constant). However, in practice, the sharpness of wide bands tends to be low due to their low intensity, thus limiting the measurement precision. Possible methods to improve measurement precision are suggested.

Ion beam polishing for three-dimensional electron backscattered diffraction.

Serial sectioning by focused ion beam milling for three-dimensional electron backscatter diffraction (3D-EBSD) can create surface damage and amorphization in certain materials and consequently reduce the EBSD signal quality. Poor EBSD signal causes longer data acquisition time due to signal averaging and/or poor 3D-EBSD data quality. In this work a low kV focused ion beam was successfully implemented to automatically polish surfaces during 3D-EBSD of La- and Nb-doped strontium titanate of volume 12.6 × 12.6 × 3.0 µm. The key to achieving this technique is the combination of a defocused low kV high current ion beam and line scan milling. The line scan was used to restrict polishing to the sample surface and the ion beam was defocused to ensure the beam contacted the complete sample surface. In this study 1 min polishing time per slice increases total acquisition time by approximately 3.3% of normal 3D-EBSD mapping compared to a significant increase of indexing percentage and pattern quality. The polishing performance in this investigation is discussed, and two potential methods for further improvement are presented.

Transmission electron microscopy specimen preparation method for multiphase porous functional ceramics.

An optimum method is proposed to prepare thin foil transmission electron microscopy (TEM) lamellae of multiphase porous functional ceramics: prefilling the pore space of these materials with an epoxy resin prior to focused ion beam milling. Several advantages of epoxy impregnation are demonstrated by successful preparation of TEM specimens that maintain the structural integrity of the entire lamella. Feasibility of the TEM alignment procedure is demonstrated, and ideal TEM analyses are illustrated on solid oxide fuel cell and solid oxide electrolysis cell materials. Some potential drawbacks of the TEM specimen preparation method are listed for other samples.

Effects of focused ion beam milling on electron backscatter diffraction patterns in strontium titanate and stabilized zirconia.

This study investigates the effect of focused ion beam (FIB) current and accelerating voltage on electron backscatter diffraction pattern quality of yttria-stabilized zirconia (YSZ) and Nb-doped strontium titanate (STN) to optimize data quality and acquisition time for 3D-EBSD experiments by FIB serial sectioning. Band contrast and band slope were used to describe the pattern quality. The FIB probe currents investigated ranged from 100 to 5000 pA and the accelerating voltage was either 30 or 5 kV. The results show that 30 kV FIB milling induced a significant reduction of the pattern quality of STN samples compared to a mechanically polished surface but yielded a high pattern quality on YSZ. The difference between STN and YSZ pattern quality is thought to be caused by difference in the degree of ion damage as their backscatter coefficients and ion penetration depths are virtually identical. Reducing the FIB probe current from 5000 to 100 pA improved the pattern quality by 20% for STN but only showed a marginal improvement for YSZ. On STN, a conductive coating can help to improve the pattern quality and 5 kV polishing can lead to a 100% improvement of the pattern quality relatively to 30 kV FIB milling. For 3D-EBSD experiments of a material such as STN, it is recommended to combine a high kV FIB milling and low kV polishing for each slice in order to optimize the data quality and acquisition time.

Geometrical characterization of interconnected phase networks in three dimensions.

In electrochemical devices such as fuel cells or batteries the microstructure is a determining factor for the performance of the device. To be able to optimize the microstructure it is important to be able to quantitatively measure key structural parameters, such that systematic studies can be made. We present several general methods for quantitative characterization of network structures without prior assumptions of shape or application. The characterization is performed by extracting distributions of values rather than single value descriptions, thus allowing more detailed comparisons between samples to be made. The methods characterize tortuosity, path diameters, the novel dead ends property and a particle shape independent alternative to a particle size distribution. The parameters are calculated by the computation of arrival time maps by the fast marching method. The methods are applied to the analysis of each of the three phases in a solid oxide fuel cell sample.

Trends in obstetric practices and meconium aspiration syndrome: a population-based study.

OBJECTIVE: To determine trends in the incidence of meconium aspiration syndrome (MAS), and maternal factors and obstetric practices associated with any decline. DESIGN: Population-based cohort study. SETTING: New South Wales (NSW), Australia. POPULATION: All 877 037 liveborn, singleton, term infants (≥ 37 weeks of gestation) in the period 1997-2007. METHODS: Data were obtained from birth records linked to the neonatal hospital discharge records. The birth data provided information on maternal and obstetric factors, whereas the outcome of interest, MAS, was obtained from hospital data on the neonates. Multivariable logistic regression was used to estimate the risk of MAS while simultaneously adjusting for the explanatory variables. MAIN OUTCOME MEASURES: The incidence of MAS per 1000 births, and odds ratios and 95% confidence intervals for maternal and obstetric factors for the development of MAS. RESULTS: The incidence of MAS declined significantly by 11.3% per annum (95% CI 10.1-12.6; P < 0.001) from 4.1 per 1000 births in 1997 to 1.3 per 1000 births in 2007. This was associated with a statistically significant decline in risk factors: maternal smoking (from 20 to 12%), gestational age (from 57 to 47% ≥ 40 weeks of gestation), delivery at small hospitals (from 15 to 9%) and infants with birthweight below the third percentile (from 3.3 to 2.4%). There were simultaneous statistically significant increases in practices that reduce the risk of MAS: labour inductions (from 22 to 27%) and birth by caesarean section, both elective, prior to 40 weeks of gestation (from 7.3 to 13.8%), and emergency (from 3.0 to 5.3% prior to 40 weeks of gestation, and from 5.1 to 6.7% at 40 weeks of gestation or later). CONCLUSIONS: The rate of MAS is declining, and this decline is associated with a reduction in maternal and pregnancy risk factors, and an increase in protective obstetric practices.

Decreasing infection in neonatal intensive care units through quality improvement.

OBJECTIVE: To decrease the incidence of bloodstream infection (BSI) for neonates <29 weeks gestation through quality improvement. DESIGN: Commencing in September 2011, eight neonatal intensive care units (NICUs) in New South Wales and Australian Capital Territory, Australia participated in the Sepsis Prevention in NICUs Group project, a multicentre quality improvement initiative to reduce neonatal infection through implementation of potentially better practices and development of teaching resources. Data were collected for neonates <29 weeks gestation from D3 to 35, using point of care data entry, for BSI, central line-associated BSI (CLABSI) and antibiotic use. Exponentially weighted moving average data trend lines for rates of BSI, CLABSI and antibiotic use for each NICU were automatically generated and composite charts were provided each month to participating NICUs. RESULTS: Between January 2012 and December 2014, data were collected from D3 to 35 for 1075 neonates <29 weeks gestation who survived >48 h, for a total of 33 933 bed days and 14 447 central line days. There was a significant decrease from 2012 to 2014 in BSI/1000 bed days (7.8±3.0 vs 3.8±1.1, p=0.000), CLABSI/1000 bed days (4.6±2.1 vs 2.1±0.8, p=0.003), CLABSI/1000 central line days (9.9±4.3 vs 5.4±1.7, p=0.012) and antibiotic days/100 bed days (31.1±4.3 vs 25.5±4.2, p=0.046). CONCLUSIONS: This study demonstrates a >50% reduction in BSI in extremely premature neonates from D3 to 35 following a collaborative quality improvement project to reduce neonatal infection across an NICU network, supported by timely provision of data.

Childhood outcomes following preterm prelabor rupture of the membranes (PPROM): a population-based record linkage cohort study.

OBJECTIVE: The objective of this study is to determine child health, development and educational outcomes for infants born following preterm prelabor rupture of the membrane (PPROM). STUDY DESIGN: Population-based record linkage cohort study using data from NSW, Australia, 2001 to 2014. RESULTS: Of 121 822 births at 20 to 37 weeks, 18 799 (15%) followed PPROM, 56 406 (46%) followed spontaneous labor and 46 617 (38%) were planned. Compared with infants of a similar gestational age born following spontaneous labor or planned delivery, exposure to PPROM did not increase the risk of childhood mortality, childhood hospitalization, developmentally vulnerable at school entry, low reading or numeracy scores. Median latency ranged from 12 days (interquartile range 3 to 37 days) at 25 weeks to 1 day (0 to 2 days) at 36 weeks. Longer latency and more advanced gestational age at birth were associated with better outcomes. CONCLUSION: Infants born following PPROM are at no greater risk of adverse child health, development and education outcomes than those of similar gestational age born without PPROM.

Normative data for iliac bone histomorphometry in growing children.

Many insights into normal and pathologic bone development can only be gained by bone histomorphometry. However, the use of this technique in pediatrics has so far been hampered by the lack of reference data. Therefore, we obtained transfixing iliac bone samples from 58 individuals between 1.5 and 22.9 years of age (25 male; tetracycline labeling performed in 48 subjects), who underwent surgery for reasons independent of abnormalities in bone development and metabolism. The results of histomorphometric analyses of cancellous parameters and cortical width are presented as means and standard deviations, as well as medians and ranges in five age groups. In addition, the original data are available from the authors. There were significant age-dependent increases in both cortical width and cancellous bone volume, the latter being due to an increase in trabecular thickness. Osteoid thickness did not vary significantly with age. Bone surface-based indicators of bone formation showed an age-dependent decline, reflecting similar changes in activation frequency. Mineral apposition rate decreased continuously with age. Parameters of bone resorption did not vary significantly between age groups. Paired biopsies from adjacent sites, obtained in eight subjects, were used to examine the reproducibility of histomorphometric parameters in children. The lowest coefficients of variation (<10%) were found for structural measures, as well as mineral apposition rate and wall thickness. The highest variability was found for cellular parameters. The availability of reference material will greatly facilitate the use of histomorphometry in pediatrics.

Mammographic localization and biopsy of nonpalpable breast lesions. A 5-year study.

A malignancy rate of 24% was achieved as a result of needle localizations and biopsies of 548 nonpalpable mammographically detected breast lesions in 507 consecutive patients during a 5-year period. Malignancy was present in 74 (23.8%) of 311 irregular soft-tissue densities, in 40 (19.6%) of 204 cases with clustered microcalcifications, and in 33 cases (54.5%) when both features were present. Same-day admission and discharge were achieved in 491 patients and local anesthesia supplemented with intravenous sedation was used in 73 (74%) of the 98 patients (in 1989) by the end of the study period. Nonpalpable cancers were categorized pathologically as stage 0 in 25 patients (20.8%), stage I in 67 patients (55.8%), stage IIA in 24 patients (20.0%), and stage IIB in four patients (3.3%). The malignancy rate rose sharply from the fourth to the fifth decade.

Protrusio acetabuli in neurofibromatosis: nondysplastic and dysplastic forms.

Protrusio acetabuli (PA) in neurofibromatosis is not well documented in the literature. Two forms of PA, a nondysplastic and dysplastic type, are noted. Twenty-one percent of hips (13 patients) in neurofibromatosis were found to have some form of acetabular protrusion abnormality. In the control group (83 patients) without stigmata of neurofibromatosis, only 9% of hips were associated with PA. The progressive dysplastic form of PA is usually associated with contiguous soft-tissue neurofibromas and lumbar dural ectasia. The nondysplastic, nonprogressive form has less of an association with regional soft-tissue abnormalities and almost no association with dural dysplasia.

Change in the management of adult groin hernia.

Three hundred fifty-seven groin hernia repairs were performed under local anesthesia using a long-lasting local anesthetic agent. An ilioinguinal, iliohypogastric, and twelfth intercostal nerve block was carried out initially, followed by regional infiltration of the agent, using a technic first described by Ponka [8] with several modifications. This technic can be employed suffessfully in the majority of groin hernia repairs. It requires careful attention to detail in the administration of preoperative sedation and analgesia and the use of sharp dissection only and greater gentleness in the handling of tissue. We have observed a significant reduction in postoperative discomfort and the virtual elimination of urinary retention, urinary sepsis, atelectasis, and phlebitis in these cases. All patients are fully ambulatory, without assistance immediately after surgery and the majority are discharged the same day or the following morning. This results in a marked reduction in the total cost of repairing a groin hernia.

Experience with the EEA stapling device.

The EEA stapling instrument was used to perform 48 anastomoses without operative mortality. One of the 29 colorectal anastomoses developed a leak. Two intraabdominal abscesses were noted, one after an intraperitoneal colocolostomy and one after a colorectal anastomosis. No leaks were demonstrated in the 12 esophageal anastomoses. Minor bleeding that occurred in one of the colorectal anastomoses ceased spontaneously without need for transfusion. One esophageal and one colorectal anastomosis became narrowed postoperatively, but both were corrected with dilatation without further problem. In two of the very low colorectal anastomoses, transient fecal soilage occurred for 4 to 5 months postoperatively. On the basis of our experience, we believe that the EEA instruments has a definite place in gastrointestinal surgery. Its greatest virtue is that it provides a means to perform the heretofore technically difficult and frequently insecure colorectal and esophageal anastomoses with greater facility and security.

Epiphyseal-metaphyseal enchondromatosis. A new clinical entity.

We reviewed the cases of eight unrelated children who had an unusual form of enchondromatosis characterized by unilateral enchondromas arising within the epiphyseal and metaphyseal regions of the long tubular bones of the lower extremity. Unlike previously described enchondromas, the lesions developed extensively within the epiphysis before closure of the growth plate and there was direct extension across the epiphyseal growth plate into the metaphysis. The lesions resulted in severe limb-length discrepancy and angular deformity (which increased in every patient after the time of presentation), asymmetrical premature physeal arrest, and joint incongruity, all of which necessitated numerous operative procedures. Seven patients had limb-lengthening and one had a Boyd amputation without lengthening. Five patients had a second lengthening procedure. Twenty-seven osteotomies (range, one to five procedures per patient) were done; six patients had a repeat osteotomy. Four patients had an epiphyseodesis. We believe that these lesions represent a previously undescribed clinical entity, which we termed epiphyseal-metaphyseal enchondromatosis.

Adolescent idiopathic scoliosis: treatment with the Wilmington brace. A comparison of full-time and part-time use.

We reviewed the clinical records and the radiographs of 188 patients who had adolescent idiopathic scoliosis. Our purpose was to determine whether part-time and full-time bracing had been equally effective in preventing progression of the curve. Full-time bracing had been used for ninety-eight patients; part-time bracing, for forty-nine; and electrical stimulation, for forty-one. Eighty-eight patients had had a curve of less than 30 degrees and 100 patients, a curve of 30 to 40 degrees. The treatment was considered a failure if the curve had increased 5 degrees or more. The curve progressed 5 degrees or more in thirteen (36 per cent) of the thirty-six patients who had had full-time bracing for a curve of less than 30 degrees, in thirteen (41 per cent) of the thirty-two who had had part-time bracing for such a curve, and in fourteen (70 per cent) of the twenty who had had electrical stimulation for such a curve. Compared with electrical stimulation, both full-time and part-time bracing prevented progression significantly more effectively (p < 0.02 and p < 0.04, respectively). With the numbers available, the difference in progression between the groups that had had full-time and parttime bracing was not significant (p < 0.18). The curve progressed 5 degrees or more in thirty-six (58 per cent) of the sixty-two patients who had had full-time bracing for a curve of 30 to 40 degrees, in ten of the seventeen who had had part-time bracing for such a curve, and in eighteen (86 per cent) of the twenty-one who had had electrical stimulation for such a curve. The difference in progression between each bracing program and electrical stimulation was significant (p < 0.03 for the full-time program and p < 0.05 for the part-time program). With the numbers available, the difference in progression between full-time and part-time bracing was not significant (p < 1.14).

Evaluation and treatment of diastematomyelia.

We reviewed the results for forty-three patients who had a diastematomyelia. All of the patients had been skeletally immature when the diagnosis was made, the mean age being six years (range, birth to thirteen years), and were skeletally mature by the time that they were evaluated by us. When they were first seen at our institution, twenty-four patients (56 per cent) had a cutaneous lesion, such as hairy patch, dimple, hemangioma, subcutaneous mass, or teratoma at or near the level of the diastematomyelia; thirty-four patients (79 per cent) had congenital scoliosis; and forty-two patients (98 per cent) had at least one associated musculoskeletal anomaly, such as spinal dysraphism, asymmetry of the lower extremities, club foot, or a cavus foot. In twenty-seven patients (63 per cent), the diastematomyelia was located in the lumbar spine. Thirty-six patients had eighty-four neurological manifestations. Resection of the spur was performed in thirty-three patients at a mean age of seven years (range, three months to seventeen years). Twenty-two patients who had a resection had no change in neurological condition, nine patients had improvement, and one patient had one symptom improve and another symptom worsen after the operation. We believe that resection of the spur should be performed in patients who have progressive neurological manifestations. Patients who do not have progressive neurological manifestations should be observed; if progression is noted, a resection should then be performed.

Varus derotation osteotomy in the treatment of persistent dysplasia in congenital dislocation of the hip.

We have attempted to define the indications for and limitations of varus derotation osteotomy in the treatment of persistent dysplasia in congenital dislocation of the hip. We studied the cases of thirty-four patients (forty-four hips) who were divided into three groups according to age at operation, and evaluated the influence of femoral remodeling, age, acetabular response, instability, and pre-existing avascular necrosis with respect to the final results. The length of follow-up ranged from five to twenty-two years. Rapid return to a valgus femoral neck-shaft angle by remodeling was not a cause of failure in any age group. There were consistently good results in the patients who were less than four years old at the time of operation. Acetabular correction by remodeling occurred through the age of eight years, but four of thirteen hips in patients who were between the ages of four and eight showed persistent dysplasia despite the operative procedure. The results were less predictable as the patients approached the age of eight years. There was no benefit from isolated femoral osteotomy in ten of eleven hips in patients who were older than eight. Pre-existing avascular necrosis appeared to compromise the results of the procedure in all age groups.

Multiplier method for predicting limb-length discrepancy.

BACKGROUND: In patients with a congenital or developmental limb-length discrepancy, the short limb grows at a rate proportional to that of the normal, long limb. This is the basis of predicting limb-length discrepancy with existing methods, which are complicated and require multiple data points. The purpose of our study was to derive a simple arithmetic formula that can easily and accurately predict limb-length discrepancy at skeletal maturity. METHODS: Using available databases, we divided the femoral and tibial lengths at skeletal maturity by the femoral and tibial lengths at each age for each percentile group. The resultant number was called the multiplier. Using the multiplier, we derived formulae to predict the limb-length discrepancy and the amount of growth remaining. We verified the accuracy of these formulae by evaluating two groups of patients with congenital shortening who were managed with epiphysiodesis or limb-lengthening. We also calculated and compared the multipliers for other databases according to radiographic, clinical, and anthropological lower-limb measurements. RESULTS: The multipliers for the femur and tibia were equivalent in all percentile groups, varying only by age and gender. Because congenital limb-length discrepancy increases at a rate proportional to growth, the discrepancy at maturity can be calculated as the current discrepancy times the multiplier for the current age and the gender. This calculation can be performed with use of a single measurement of limb-length discrepancy. For progressive developmental (noncongenital) discrepancies, the discrepancy at skeletal maturity can be calculated as the current discrepancy plus the growth inhibition times the amount of growth remaining. The timing of the epiphysiodesis can also be calculated with the multiplier. The predictions made with use of the multiplier method correlated well with those made with use of the Moseley method as well as with the actual limb-length discrepancy in both the limb-lengthening and epiphysiodesis groups. The multipliers derived from the radiographic, clinical, and anthropological measurements of femora and tibiae were all similar to each other despite differences in race, ethnicity, and generation. CONCLUSIONS: The multiplier method allows for a quick calculation of the predicted limb-length discrepancy at skeletal maturity, without the need to plot graphs, and is based on as few as one or two measurements. This method is independent of percentile groups and is the same for the prediction of femoral, tibial, and total-limb lengths. The multiplier values are also independent of generation, height, socioeconomic class, ethnicity, and race. We verified the accuracy of this method clinically by evaluating patients who had been managed with limb-lengthening or epiphysiodesis. The method was also comparable with or more accurate than the Moseley method of limb-length prediction.