Graphene production by cracking.

In recent years, graphene has found its use in numerous industrial applications due to its unique properties. While its impermeable and conductive nature can replace currently used anticorrosive toxic pigments in coating systems, due to its large strength to weight ratio, graphene can be an important component as a next-generation additive for automotive, aerospace and construction applications. The current bottlenecks in using graphene and graphene oxide and other two-dimensional materials are the availability of cost-effective, high-quality materials and their effective incorporation (functionalization and dispersion) into the product matrices. On overcoming these factors, graphene may attract significant demands in terms of volume consumption. Graphene can be produced on industrial scales and through cost-effective top-down routes such as chemical, electrochemical and/or high-pressure mechanical exfoliation. Graphene, depending on end applications, can be chemically tuned and modified via functionalization so that easy incorporation into product matrices is possible. This paper discusses different production methods and their impact on the quality of graphene produced in terms of energy input. Graphene with an average thickness below five layers was produced by both methods with varied defects. However, a higher yield of graphene with a lower number of layers was produced via the high-pressure exfoliation route. This article is part of a discussion meeting issue 'A cracking approach to inventing new tough materials: fracture stranger than friction'.

[Surgical management of ankylosing spondylitis (Bechterew's disease)]. / Operationen bei ankylosierender Spondylitis (Morbus Bechterew).

Ankylosing spondylitis is an inflammatory rheumatic disease that is often associated with back pain and restricted spinal movement. In the later stages of the disease, complete ossification of the entire spine and severe deformity can occur, often resulting in a marked reduction in quality of life and an increased risk of loss of independence due to diminished visual field. Patients with ankylosing spondylitis are at greater risk of spinal fractures. These are generally complex fractures associated with high morbidity and mortality; in addition, neurological deficits are not unusual. Conventional radiological diagnosis is often insufficient to establish a diagnosis. Conservative treatment of fractures of the spine in this patient group is unsatisfactory. Surgical procedures, if necessary combined with decompression, are often the preferred treatment of choice in the fractured or malaligned ankylosed spine. Rebalancing of the sagittal profile with normalization of the visual axis and an improvement of quality of life is achieved through corrective osteotomies. Despite the high rate of complications, long-term results following spinal surgery in patients with ankylosing spondylitis are good. Minimally invasive surgery is appropriate for a further reduction in the complication rate. Meticulous preoperative planning is essential in the treatment of patients with ankylosing spondylitis.

[Simultaneous thoracoscopically assisted anterior release in prone position and posterior scoliosis correction : What are the limits?]. / Thorakoskopisches ventrales Release in Bauchlage simultan zur dorsalen Korrekturspondylodese : Wo sind die Grenzen?

BACKGROUND: In spite of modern pedicle-based systems, the correction of a rigid rib hump or hypokyphosis remains a problem in posterior-only scoliosis surgery. As there has so far been no reliable method of predicting the intraoperative extent of kyphosis restoration or rib hump correction by posterior-only surgery, it has been difficult to determine the indication for an additional anterior release. METHODS: The method described here circumvents this dilemma. Like an optional module, horacoscopically assisted release in prone position (TARP) can be added when it is obvious during posterior surgery that the correction is insufficient. RESULTS: Between 1996 and 2005, a total of 161 patients (115 male, 46 female) under the age of 30, including 113 cases of idiopathic scoliosis, were released by simultaneous TARP and posterior surgery. Using the two-portal technique, 131 were mobilized from the right and 30 from the left hand side. Average surgical time spanned 69 min, in which on average 3.2 apical segments were addressed. In 3 individuals, an additional retroperitoneoscopic release was used to liberate a rigid lumbar curve. After 10 years, in a prospectively evaluated subgroup of 32 patients with adolescent idiopathic scoliosis, the index curve had maintained a coronal correction of 70 % (immediately post-surgery 75 %), kyphosis was permanently normalized at 30° (Th5-Th12), and indirect rib hump was reduced to 2.2 cm. In 23 out of 32 patients the lumbar curve corrected spontaneously, obviating the need for fusion. In 13 patients, the lower instrumented vertebra lay at Th12 or higher, thus leaving the thoraco-lumbar junction fairly free. Minor complications (Huang 1or 2) occurred in 4 patients; 1 patient with hematothorax required revision. A distance <25 mm from the spine to the chest wall precludes TARP. Other limitations (e.g., pleural adhesions) were not encountered. CONCLUSION: Long-term evaluation after 10-18 years shows that an additional thoracoscopically assisted anterior release at the same time as a posterior standard scoliosis procedure is a justified and effective tool, yielding better results and maintaining them.

Three-dimensional analysis of cranial growth from 6 to 12 months of age.

The aim of this study was to generate three-dimensional data of the physiological growth of the infant's cranium in the significant growth phase from 6 to 12 months of age. In a longitudinal observational study non-invasive 3D data using an optical surface scanner were generated of the entire head of 52 Caucasian infants (27 females and 25 males) between the ages of 6 (T1) and 12 (T2) months. The circumference of the head increased by 6.51 per cent (from 43.50 to 46.33cm). Analysis of width and length showed that the head grows 2.84 per cent more in length, resulting in a decrease in the cranial index of 2.52 per cent (from 83.87 to 81.76 per cent). The highest increment observed was in the total volume of the cranium, with an increase of 18.76 per cent (from 1229.01 to 1459.57cm(3)). Comparison of the left and right sides of the head by measuring the diagonal symmetry difference showed a difference of only 0.37cm. Overall, the symmetry-related parameters showed an almost symmetric development of the cranium in infants. The findings should provide valuable information on physiological growth and development of the infant's cranium. Therefore the high growth rate of the cranium in the first year of life suggests that this period is a critical period in which the disruption of developmental processes may have long-lasting effects on the morphology of the cranium with a prognostically unfavourable effect of the further growth of the viscerocranium.

Experimental investigation and modeling of the kinetics of CCl4 pyrolysis behind reflected shock waves using high-repetition-rate time-of-flight mass spectrometry.

The pyrolysis kinetics of CCl(4) behind reflected shock waves was studied with high-repetition-rate time-of-flight mass spectrometry. For modeling, quantum mechanical calculations were performed to evaluate the dissociation energies of CCl bonds for the different CCl(x) (x = 1 to 4) radicals. Good agreement with the JANAF thermochemical table was found. With the reaction mechanism developed for CCl(4) decomposition satisfactory agreement with experimental results was obtained. The investigations show the importance of C(2)Cl(2) formation for understanding the processes of carbon cluster growth leading to carbonaceous particle formation.

[Non-unions. From diagnosis to healing]. / Pseudarthrosen. Von der Diagnose bis zur Ausheilung.

Non-unions are a relevant medical and socio-economic problem. Hyper-, oligo- and atrophic non-unions as well as septic and aseptic non-unions are differentiated. Correct classification is essential for the selected therapy. The "diamond concept" describes five pillars, on which bone healing is based and that have to be considered in the treatment of non-unions: osteogenic cells (mesenchymal stem cells), osteoinduction (growth factors), osteoconduction (scaffolds), mechanical stability, and vascularization. Factors that predispose to non-union also influence fracture healing. The gold standard of therapy are still resection of the non-union, decortication and autologous bone grafting. No advantage could be proven for any of the numerous procedures in monotherapy. But the combination of various procedures - polytherapy - seems to be promising. The aim is to optimize these concepts.

Experimental and modeling study of carbon suboxide decomposition behind reflected shock waves.

At temperatures between 1150 and 2000 K and pressures between 0.1 and 0.2 MPa, the thermal decomposition of carbon suboxide (C(3)O(2)) behind reflected shock waves was investigated with a high-repetition-rate time-of-flight mass spectrometer (HRR-TOF-MS) connected to the end flange of a shock tube enabling rapid repetitive (100 kHz) measurements of the gas-phase composition. Concentration-time profiles for C(3)O(2) and CO were measured and compared to simulations based on an improved mechanism for C(3)O(2) decomposition and carbon cluster growth. In addition, relative concentrations of C atoms and C(2) molecules were detected and related to model predictions. For temperatures up to 1800 K, satisfactory agreement between experimental data and calculations was obtained. At higher temperatures, measurements and simulations differed noticeably. The importance of C(2) for the growth of carbon clusters was confirmed.

Self-cooling of a micromirror by radiation pressure.

Cooling of mechanical resonators is currently a popular topic in many fields of physics including ultra-high precision measurements, detection of gravitational waves and the study of the transition between classical and quantum behaviour of a mechanical system. Here we report the observation of self-cooling of a micromirror by radiation pressure inside a high-finesse optical cavity. In essence, changes in intensity in a detuned cavity, as caused by the thermal vibration of the mirror, provide the mechanism for entropy flow from the mirror's oscillatory motion to the low-entropy cavity field. The crucial coupling between radiation and mechanical motion was made possible by producing free-standing micromirrors of low mass (m approximately 400 ng), high reflectance (more than 99.6%) and high mechanical quality (Q approximately 10,000). We observe cooling of the mechanical oscillator by a factor of more than 30; that is, from room temperature to below 10 K. In addition to purely photothermal effects we identify radiation pressure as a relevant mechanism responsible for the cooling. In contrast with earlier experiments, our technique does not need any active feedback. We expect that improvements of our method will permit cooling ratios beyond 1,000 and will thus possibly enable cooling all the way down to the quantum mechanical ground state of the micromirror.

Avoiding CT scans in children with single-suture craniosynostosis.

INTRODUCTION: During the last decades, computed tomography (CT) has become the predominant imaging technique in the diagnosis of craniosynostosis. In most craniofacial centers, at least one three-dimensional (3D) computed tomographic scan is obtained in every case of suspected craniosynostosis. However, with regard to the risk of radiation exposure particularly in young infants, CT scanning and even plain radiography should be indicated extremely carefully. MATERIAL AND METHODS: Our current diagnostic protocol in the management of single-suture craniosynostosis is mainly based on careful clinical examination with regard to severity and degree of the abnormality and on ophthalmoscopic surveillance. Imaging techniques consist of ultrasound examination in young infants while routine plain radiographs are usually postponed to the date of surgery or the end of the first year. CT and magnetic resonance imaging (MRI) are confined to special diagnostic problems rarely encountered in isolated craniosynostosis. The results of this approach were evaluated retrospectively in 137 infants who were referred to our outpatient clinic for evaluation and/or treatment of suspected single suture craniosynostosis or positional deformity during a 2-year period (2008-2009). RESULTS: In 133 (97.1%) of the 137 infants, the diagnosis of single-suture craniosynostosis (n = 110) or positional plagiocephaly (n = 27) was achieved through clinical analysis only. Two further cases were classified by ultrasound, while the remaining two cases needed additional digital radiographs. In no case was CT scanning retrospectively considered necessary for establishing the diagnosis. Yet in 17.6% of cases, a cranial CT scan had already been performed elsewhere (n = 16) or had been definitely scheduled (n = 8). CONCLUSION: CT scanning is rarely necessary for evaluation of single-suture craniosynostosis. Taking into account that there is a quantifiable risk of developing cancer in further lifetime, every single CT scan should be carefully indicated.

[Instrumented gait and movement analysis of musculoskeletal diseases]. / Instrumentelle Gang- und Bewegungsanalyse bei muskuloskelettalen Erkrankungen.

Instrumented 3-dimensional gait analysis is increasingly being used for the evaluation of movement disorders in orthopedic and neurological musculoskeletal diseases. Due to the high reliability of the measurements the procedures are appropriate for diagnostic purposes as well as for outcome assessment after conservative or surgical interventions. Contrary to conventional clinical assessments gait analysis parameters are able to demonstrate a normal physiological gait pattern that can be achieved with improved kinematic and kinetic parameters. For a suitable application in clinically relevant problems the limitations of the procedures should be taken into account. Due to the high instrumental involvement combined with time and cost expenditure instrumented gait analysis will probably not develop to a clinical routine procedure. Nevertheless, an excellent set of information for answering clinical questions is provided. The present contribution presents selected measurement procedures and technologies and illustrates the wide variety of possibilities with the use of selected clinical examples.

Lower-limb joint-coordination and coordination variability during gait in children with cerebral palsy.

BACKGROUND: Children with cerebral palsy present with poor motor control, altering their ability to perform tasks such as walking. Continuous relative phase analysis is a popular method to quantify motor control impairments via inter-joint coordination and coordination variability; however, it has not been explored in children with cerebral palsy. METHODS: 45 children with cerebral palsy and 45 typically developing children walked while fit with retroreflective markers. Continuous relative phase analysis for knee-hip and ankle-knee joint pairs quantified inter-joint coordination and coordination variability. The Gait Profile Score estimated gait pathology. Group differences were assessed with unpaired t-tests for coordination amplitude and variability (knee-hip, ankle-knee) across gait events. For the cerebral palsy group, correlations assessed the relation between the gait profile score and coordination metrics. FINDINGS: The cerebral palsy group showed more in-phase patterns for knee-hip coupling compared to the typically developing group (initial contact, loading response, mid-stance, terminal swing) (p ≤ 0.03). The cerebral palsy group showed lower knee-hip coordination variability (mid-stance, mid-swing) (p ≤ 0.037) and lower ankle-knee coordination variability (initial contact, loading response, terminal swing) (p < 0.001). The gait profile score correlated weakly to moderately (r = [0.323-0.472]), and negatively with the knee-hip inter-joint coordination (initial contact, loading response, mid-stance, terminal swing) (p ≤ 0.042). INTERPRETATION: Children with cerebral palsy showed a more in-phase gait strategy during challenging transitional gait cycle phases (beginning and end) and less flexible and adaptable motor behaviors. Moreover, the correlation between in-phase joint patterns and increased gait deviations (gait profile score) reinforces the relevance of coordination analysis to assess motor control impairment.

Is shortening of Tibialis Anterior in addition to calf muscle lengthening required to improve the active dorsal extension of the ankle joint in patients with Cerebral Palsy?

INTRODUCTION: Shortening of the tibialis anterior tendon (TATS) has been shown to improve the ankle dorsiflexion in swing following the calf muscle lengthening procedure (CMLP) in patients with cerebral palsy (CP). Others have reported the similar improvements following CMLP but without TATS. However there are no studies comparing both procedures. Therefore the purpose of the study was to compare the ankle dorsiflexion in swing and foot position in the sagittal plane during gait following TATS and CMLP to that of CMLP alone. MATERIALS AND METHODS: A retrospective study was carried out in CP patients who presented with fixed equinus deformity. They were grouped into unilateral CP and bilateral CP. Depending on the procedures, each group was again subdivided into subgroup CMLP only and subgroup CMLP and TATS (CMLPTATS). All patients were subjected to pre and postoperative clinical and gait analysis. RESULTS: 44 feet in 44 patients were included in the study. Of these, 24 feet (24 patients) belonged to unilateral and 20 feet (20 patients) to bilateral CP group. The mean age of the patients at surgery was 11.5 years (6.0 - 29.0) in the unilateral CP group and 10.5 years (5.0-34.0) in the bilateral CP group. In the unilateral CP group, 12 feet belonged to subgroup CMLP and 12 to subgroup CMLPTATS with a mean equinus contracture of 7.5° in both subgroups. In bilateral CP group, 11 feet belonged to subgroup CMLP with a mean equinus contracture of 5° and 9 to subgroup CMLPTATS, with a mean equinus contracture of 10°. The subgroups did not vary significantly in the demographics, anthropometry, kinematics and kinetics of ankle joint preoperatively. The mean follow up time was 19.7 months. The surgery produced significant changes in both groups and subgroups. However, none of the relevant gait parameters were significantly different between groups and subgroups. SIGNIFICANCE: Adding TATS to CMLP, compared to CMLP alone did not improve ankle dorsiflexion in swing and the foot position more than CMLP alone.