Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 20
Filter
1.
J Clin Orthop Trauma ; 53: 102438, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38975295

ABSTRACT

Background: Paediatric femoral shaft fractures can be managed with single- or double-leg hip spica casting between ages six-months and six-years. The aim of this review was to determine if single-leg hip spicas reduce the impact on family life without compromising fracture stability. Methods: The study was registered on PROSPERO (CRD42023454309). MEDLINE, Embase, Web of Science, Cochrane Library, and clinical trial registers were searched to May 2023 for level I-III evidence. Primary outcomes were impact on family life and fracture stability. Where appropriate, Meta-analysis was completed using RevMan v5.4. Risk of bias was assessed using RoB 2.0 (RCTs) and ROBINS-I (non-RCTs). Certainty of evidence was measured with GRADE. Results: From 234 identified papers, four met the inclusion criteria (two RCTs; two non-RCTs). A total of 339 children were included (single-leg spica: 176; double-leg spica: 163). Three studies were 'high risk' and one study 'moderate risk' of bias. Impact on family life parameters were too heterogenous for pooled meta-analysis. Non-pooled data identified significantly more missed work days in the double-leg spica group and the 'Impact on Family' Scale significantly favoured single-leg spicas. For fracture stability, meta-analysis identified that (i) mal-union rates were significantly lower in single-leg spica: OR 0.08 (95 % CI 0.01 to 0.69; p = 0.02); (ii) MUA in theatre was not significantly different: OR 0.97 (95 % CI 0.19 to 4.86; p = 0.97); and (iii) wedge adjustment was not significantly different: OR 3.46 (95 % CI 0.48 to 24.92; p = 0.22). Certainty of evidence was assessed as 'very low'. Conclusion: Single-leg hip spicas may be associated with reduced impact on family life without compromising fracture stability compared with double-leg hip spicas. However, the evidence is weak. Therefore, a propensity score matched observational study is required to understand if subgroups of patients (age, fracture pattern, mechanism of injury) would benefit from a single- or double-leg hip spica.

2.
Article in English | MEDLINE | ID: mdl-38878817

ABSTRACT

OBJECTIVE: To assess whether patient reported outcome measures (PROMs) improve after autologous conditioned serum (ACS) administration in patients with osteoarthritis. METHODS: Databases and clinical trial registers were searched to March 2024 for randomised controlled trial (RCTs) comparing ACS vs comparators/controls. Primary outcomes were pain, function and stiffness measured with Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and visual analogue scale (VAS). Secondary outcome was complications. Risk of bias (RoB) and certainty of evidence were assessed using RoB 2 and the Grades of Recommendation, Assessment, Development and Evaluation Working Group (GRADE) respectively. Meta-analysis was undertaken using RevMan v5.4. Results are presented as standardised mean differences (SMD) or mean differences (MD) with 95% confidence intervals (CI). Sensitivity analysis compared all comparators and saline control. RESULTS: Five RCTs were identified (n = 741 participants); two (n = 529 participants) compared ACS against saline (placebo). Three studies were "some concern" and two studies "high risk" for bias. Analysis comparing ACS with all comparators significantly favoured ACS at 6 months for WOMAC: SMD -0.61 (95% CI -1.01 to -0.21; p = 0.003); and VAS: SMD -1.24 (95% CI -2.11 to -0.38; p = 0.005); with high heterogeneity. Comparing ACS with saline, there was no significant difference in WOMAC or VAS at 6 months: SMD -0.40 (95% CI -0.93 to 0.12; p = 0.13) and MD -9.87 (95% CI -27.73 to 7.98, p = 0.28). Complications were similar: ACS (24.8%) vs saline (24.4%), with serious complications rare. CONCLUSION: There is currently insufficient data to support the use of ACS in osteoarthritis with conflicting results when compared to alternative therapies and saline control, with high heterogeneity. Before consideration as a potential treatment, a high-quality multicentre RCT is required to assess the efficacy of ACS.

4.
Knee ; 46: 27-33, 2024 Jan.
Article in English | MEDLINE | ID: mdl-38039840

ABSTRACT

BACKGROUND: Knee osteoarthritis in the presence of severe obesity (BMI ≥ 40) is becoming an increasing presentation to healthcare services. When progressing to arthroplasty, this group is known to have higher complication rates. METHOD: A retrospective cohort study at a tertiary referral centre (UK) with all sequential patients undergoing TKA between 2019 and 2020 included following identification from the UK National Joint Registry. Patients were divided by BMI < 40 and BMI ≥ 40 (86, 16.3%). Analysis of BMI with pre-operative parameters including age, ASA, and blood parameters was performed. Primary outcome was re-operation rate. Secondary outcomes included length of stay, complications, and re-admission. RESULTS: Five hundred and twenty-eight sequential TKA patients were included. The BMI < 40 group (442 patients, 83.7%) were mean 5.4 years younger (p < 0.001), had a higher ASA grade (p < 0.001) lower albumin (p < 0.001) and higher HbA1c (p < 0.001) than the BMI ≥ 40 group (86 patients, 16.3%). The BMI ≥ 40 group had a higher rate of re-operation (8% vs 2%, p = 0.012), and longer length of stay (mean 1.2 days longer p < 0.001), most commonly due to wound discharge, which alongside dehiscence was significantly higher (11.6% vs 4.3% p = 0.02). Overall, re-admission rates were also higher (18.6% vs 6.1% p = 0.06) with wound dehiscence, superficial infection, and deep infection the most common causes. CONCLUSIONS: Those patients undergoing TKA with a BMI ≥ 40 are younger and have higher reoperation rates, greater length of stay, higher re-admission rates and more postoperative complications, providing a target for the development of pre-operative optimisation programmes.


Subject(s)
Arthroplasty, Replacement, Knee , Obesity, Morbid , Humans , Obesity, Morbid/complications , Obesity, Morbid/surgery , Arthroplasty, Replacement, Knee/adverse effects , Retrospective Studies , Obesity/complications , Obesity/epidemiology , Postoperative Complications/epidemiology , Postoperative Complications/etiology
5.
Cureus ; 13(3): e14114, 2021 Mar 25.
Article in English | MEDLINE | ID: mdl-33927925

ABSTRACT

Background The coronavirus disease 2019 (COVID-19) pandemic has led to a focus on non-face-to-face (NF2F) orthopedic clinics. In this study, our aim was to establish whether NF2F clinics are sustainable according to the "triple bottom line" framework by taking into account the impact on patients, the planet, and the financial cost. Methodology This retrospective cohort study was carried out at a large district general hospital with 261 patients identified as having undergone face-to-face (F2F) or NF2F orthopedic consultations (April 2020). These patients were contacted by telephone to establish their experience, mode of transport, and preference for future consultations. Data were also collected relating to environmental and financial costs to the patient and the trust. Results The final analysis included 180 (69%) patients: 42% had an F2F consultation and 58% NF2F consultation. There was no significant difference between each group in terms of convenience, ease of communication, subjective patient safety, or overall satisfaction rating (p > 0.05). Overall, 80% of NF2F patients would be happy with virtual consultations in the future. The mean journey distance was 18.6 miles leading to a reduction in total carbon emissions of 563.9 kgCO2e (66%), equating to 2,106 miles in a medium-sized car. The hospital visit carbon cost (heating, lighting, and waste generation) was reduced by 3,967 kgCO2e (58%). The financial cost (petrol and parking) was also reduced by an average of £8.96 per person. Conclusions NF2F consultations are aligned to the National Health Service's "Long Term Plan": (i) delivering high patient satisfaction with equivalent outcomes as F2F consultations; (ii) reducing carbon emissions from transportation and hospital running; and (iii) becoming cheaper.

6.
Am J Cardiol ; 143: 145-153, 2021 03 15.
Article in English | MEDLINE | ID: mdl-33352210

ABSTRACT

Aortic Z-score (Z-score) is utilized in clinical trials to monitor the effect of medications on aortic dilation rate in Marfan (MFS) patients. Z-scores are reported in relation to body surface area and therefore are a function of height and weight. However, an information void exists regarding natural, non-pharmacological changes in Z-scores as children age. We had concerns that Z-score decrease attributed to "therapeutic" effects of investigational drugs for Marfan disease connective tissue diseases might simply reflect normal changes ("filling out" of body contour) as children age. This investigation studies natural changes with age in Z-score in normal and untreated MFS children, teasing out normal effects that might erroneously be attributed to drug benefit. (1) We first compared body mass index (BMI) and Z-scores (Boston Children's Hospital calculator) in 361 children with "normal" single echo exams in four age ranges (0 to 1, 5 to 7, 10 to 12, 15 to 18 years). Regression analysis revealed that aging itself decreases ascending Z-score, but not root Z-score, and that increase in BMI with aging underlies the decreased Z-scores. (2) Next, we examined Z-score findings in both "normal" and Marfan children (all pharmacologically untreated) as determined on sequential echo exams over time. Of 27 children without aortic disease with sequential echos, 19 (70%) showed a natural decrease in root Z-score and 24 (89%) showed a natural decrease in ascending Z- score, over time. Of 25 untreated MFS children with sequential echos, 12 (40%) showed a natural decrease in root Z-score and 10 (33%) showed a natural decrease in ascending Z-score. Thus, Z-score is over time affected by natural factors even in the absence of any aneurysmal pathology or medical intervention. Specifically, Z-score decreases spontaneously as a natural phenomenon as children age and with fill out their BMI. Untreated Marfan patients often showed a spontaneous decrease in Z-score. In clinical drug trials in aneurysm disease, decreasing Z-score has been interpreted as a sign of beneficial drug effect. These data put such conclusions into doubt.


Subject(s)
Aorta/growth & development , Aortic Aneurysm/diagnostic imaging , Marfan Syndrome/diagnostic imaging , Adolescent , Aorta/diagnostic imaging , Aortic Aneurysm/drug therapy , Aortic Aneurysm/etiology , Body Mass Index , Body Surface Area , Case-Control Studies , Child , Child, Preschool , Clinical Trials as Topic , Echocardiography , Female , Humans , Infant , Infant, Newborn , Male , Marfan Syndrome/complications , Marfan Syndrome/drug therapy , Outcome Assessment, Health Care
7.
Cureus ; 12(7): e8977, 2020 Jul 03.
Article in English | MEDLINE | ID: mdl-32775059

ABSTRACT

Courses to help medical students pass 'Finals' already exist but are typically expensive or can only be attended by a limited number of students. We describe the success of 'The National Finals Revision Day' (NFRD) course, which we believe is sustainable and unique in terms of its combined scale and cost (£10 per person). The course was organised and taught by 12 junior doctors. In total, 300 students attended from 55% of UK medical schools. Attendees found the course both relevant (96.4%) and cost-effective (97%), whilst the 11 medical and surgical talks were of a high standard (90.1%). The organising committee felt confident to organise their own teaching course in the future with 100% having already run a course themselves since the NFRD course. The NFRD course was also used by 11/12 (91.7%) of the organising committee to achieve their Annual Review of Competency Progression (ARCP) and 12/12 (100%) of the organising committee to obtain jobs on training programmes in the UK. We provide guidance about how to organise similar large-scale events for those interested. Moving forward, the teaching course will be run at: (i) multiple times; (ii) multiple UK venues; (iii) run over two days to cover more medical and surgical topics; and (iv) include the option of attending via video link.

8.
J Cardiothorac Vasc Anesth ; 32(1): 170-177, 2018 02.
Article in English | MEDLINE | ID: mdl-29217251

ABSTRACT

OBJECTIVE: To determine the effectiveness and safety of aprotinin use in adult patients undergoing thoracic aortic surgery. DESIGN: Single-center, retrospective study. SETTING: All cases performed at a single university hospital. PARTICIPANTS: Between January 2004 and December 2014, 846 adult patients underwent thoracic aortic surgery. Due to missing or duplicated data on primary outcomes, 314 patients were excluded. The final sample of 532 patients underwent surgery on the thoracic aorta. INTERVENTIONS: The patients were divided in the following 2 groups: 107 patients (20.1%) received aprotinin during the surgery, which represented the study group, whereas the remaining 425 patients (79.9%) underwent surgery without the use of aprotinin. MEASUREMENTS AND MAIN RESULTS: To adjust for patient selection and preoperative characteristics, a propensity score-matched analysis was conducted. Mean total blood loss at 12 hours after surgery was similar between the 2 groups. The blood product transfusion rates did not differ in the 2 groups, except for the rate of fresh frozen plasma transfusion being significantly higher in the aprotinin group. Re-exploration for bleeding and the incidence of a major postoperative bleeding event were similar between the groups. Rates of in-hospital mortality, renal failure, and cerebrovascular accidents did not show any statistically significant difference. Aprotinin did not represent a risk factor for mortality over the long term (hazard ratio 1.14, 95% confidence interval 0.62-2.08, p = 0.66). CONCLUSIONS: The use of aprotinin demonstrated a limited effect in reducing postoperative bleeding and prevention of major bleeding events. Aprotinin did not adversely affect early outcomes and long-term survival.


Subject(s)
Aorta, Thoracic/surgery , Aprotinin/therapeutic use , Cardiac Surgical Procedures/adverse effects , Hemostatics/therapeutic use , Postoperative Hemorrhage/drug therapy , Aged , Aged, 80 and over , Cardiac Surgical Procedures/mortality , Cardiac Surgical Procedures/trends , Cohort Studies , Female , Hospital Mortality/trends , Humans , Male , Middle Aged , Postoperative Hemorrhage/etiology , Postoperative Hemorrhage/mortality , Prospective Studies , Retrospective Studies , Treatment Outcome
9.
Eur J Cardiothorac Surg ; 51(suppl 1): i4-i14, 2017 Jan.
Article in English | MEDLINE | ID: mdl-28108563

ABSTRACT

SummaryAortic arch surgery requires complex patient management beyond the manual replacement of the diseased vessel. These procedures include (i) a thorough and pathologically adjusted preoperative evaluation, (ii) initiation and control of cardiopulmonary bypass, (iii) cerebral protection strategies and (iv) techniques to protect the abdominal end organs during prolonged operations. Due to the complexity of aortic arch procedures, multimodal real-time surveillance is required during all stages of the operation. Although having the patient survive the operation is the major goal, further observation is necessary because of the chronicity of the disease. This review summarizes specific aspects of patient management during and after operations requiring periods of circulatory arrest, without necessarily referring to all studies on this topic. The pros and cons of different strategies are weighed against each other, including the personal experience of the authors. A number of questions are raised without providing a 'right' or 'wrong' answer. We show that a number of different well-established strategies can result in comparable excellent long-lasting surgical results.


Subject(s)
Aorta, Thoracic/surgery , Aortic Diseases/surgery , Perioperative Care/methods , Brain Ischemia/prevention & control , Cardiac Catheterization/methods , Cardiopulmonary Bypass/methods , Disease Management , Humans , Monitoring, Intraoperative/methods , Neuropsychological Tests
10.
Physiol Rep ; 4(11)2016 Jun.
Article in English | MEDLINE | ID: mdl-27288059

ABSTRACT

The atrioventricular node (AVN) of the cardiac conduction system coordinates atrial-ventricular excitation and can act as a subsidiary pacemaker. Recent evidence suggests that an inward background sodium current, IB,Na, carried by nonselective cation channels (NSCCs), contributes to AVN cell pacemaking. The study of the physiological contribution of IB,Na has been hampered, however, by a lack of selective pharmacological antagonists. This study investigated effects of the NSCC inhibitor SKF-96365 on spontaneous activity, IB,Na, and other ionic currents in AVN cells isolated from the rabbit. Whole-cell patch-clamp recordings of action potentials (APs) and ionic currents were made at 35-37°C. A concentration of 10 µmol/L SKF-96365 slowed spontaneous action potential rate by 13.9 ± 5.3% (n = 8) and slope of the diastolic depolarization from 158.1 ± 30.5 to 86.8 ± 30.5 mV sec(-1) (P < 0.01; n = 8). Action potential upstroke velocity and maximum diastolic potential were also reduced. Under IB,Na-selective conditions, 10 µmol/L SKF-96365 inhibited IB,Na at -50 mV by 36.1 ± 6.8% (n = 8); however, effects on additional channel currents were also observed. Thus, the peak l-type calcium current (ICa,L) at +10 mV was inhibited by 38.6 ± 8.1% (n = 8), while the rapid delayed rectifier current, IKr, tails at -40 mV following depolarization to +20 mV were inhibited by 55.6 ± 4.6% (n = 8). The hyperpolarization-activated current, If, was unaffected by SKF-96365. Collectively, these results indicate that SKF-96365 exerts a moderate inhibitory effect on IB,Na and slows AVN cell pacemaking. However, additional effects of the compound on ICa,L and IKr confound the use of SKF-96365 to dissect out selectively the physiological role of IB,Na in the AVN.


Subject(s)
Action Potentials/drug effects , Atrioventricular Node/drug effects , Calcium Channel Blockers/pharmacology , Imidazoles/pharmacology , Ion Transport/drug effects , Myocytes, Cardiac/drug effects , Animals , Atrioventricular Node/cytology , Male , Myocytes, Cardiac/cytology , Patch-Clamp Techniques , Rabbits
11.
Aorta (Stamford) ; 4(4): 124-130, 2016 Aug.
Article in English | MEDLINE | ID: mdl-28097194

ABSTRACT

Reliable methods for measuring the thoracic aorta are critical for determining treatment strategies in aneurysmal disease. Z-scores are a pragmatic alternative to raw diameter sizes commonly used in adult medicine. They are particularly valuable in the pediatric population, who undergo rapid changes in physical development. The advantage of the Z-score is its inclusion of body surface area (BSA) in determining whether an aorta is within normal size limits. Therefore, Z-scores allow us to determine whether true pathology exists, which can be challenging in growing children. In addition, Z-scores allow for thoughtful interpretation of aortic size in different genders, ethnicities, and geographical regions. Despite the advantages of using Z-scores, there are limitations. These include intra- and inter-observer bias, measurement error, and variations between alternative Z-score nomograms and BSA equations. Furthermore, it is unclear how Z-scores change in the normal population over time, which is essential when interpreting serial values. Guidelines for measuring aortic parameters have been developed by the American Society of Echocardiography Pediatric and Congenital Heart Disease Council, which may reduce measurement bias when calculating Z-scores for the aortic root. In addition, web-based Z-score calculators have been developed to aid in efficient Z-score calculations. Despite these advances, clinicians must be mindful of the limitations of Z-scores, especially when used to demonstrate beneficial treatment effect. This review looks to unravel the mystery of the Z-score, with a focus on the thoracic aorta. Here, we will discuss how Z-scores are calculated and the limitations of their use.

13.
Int J Angiol ; 24(3): 189-97, 2015 Sep.
Article in English | MEDLINE | ID: mdl-26417187

ABSTRACT

Thoracic aortic aneurysms are common and are associated with a high morbidity and mortality. Despite this lethal diagnosis, there is an increasing body of evidence to suggest that the diagnosis of an aneurysm, specifically in the ascending thoracic aorta, may significantly reduce the risk of developing systemic atherosclerosis. Clinical observations in the operating room have shown pristine blood vessels in patients undergoing surgery for thoracic aortic aneurysms. There is now evidence that both the carotid intima-media thickness and arterial calcification, which are early and late signs of atherosclerosis respectively, are decreased in those with thoracic aortic aneurysms. These clinical studies are supported by molecular, genetic, and pharmacological evidence. Two principle mechanisms have been identified to explain the relationship of a proaneurysmal state conferring protection from atherosclerosis. These include an excess proteolytic balance of matrix metalloproteinase activity, leading to fragmentation of elastic lamellae and disordered collagen deposition. In addition, transforming growth factor ß modulates vascular smooth muscle cells, extracellular matrix, and leukocytes. This confers protection from the initial plaque formation and, later provides stability to the plaque possibly through alteration of the types I and II transforming growth factor ß receptor ratio. Furthermore, studies are now beginning to establish an important role for statins and estradiol in modulating these complex pathways. In the future, as our understanding of these complex mechanisms underlying aneurysmal protection against atherosclerosis increases, corresponding therapies may be developed to offer protection from atherosclerosis.

14.
Rev Sci Instrum ; 85(4): 043908, 2014 Apr.
Article in English | MEDLINE | ID: mdl-24784627

ABSTRACT

We investigated the launch and target impact of laser-driven Al flyer plates using photon Doppler velocimetry (PDV). We studied different flyer designs launched by laser pulses of different energies, pulse durations and beam diameters, that produced km s(-1) impacts with transparent target materials. Laser-launching Al flyers 25-100 µm thick cemented to glass substrates is usually thought to involve laser vaporization of a portion of the flyer, which creates many difficulties associated with loss of integrity and heating of the flyer material. However, in the system used here, the launch mechanism was surprising and unexpected: it involved optical damage at the glass/cement/flyer interface, with very little laser light reaching the flyer itself. In fact the flyers launched in this manner behaved almost identically to multilayer flyers that were optically shielded from the laser pulses and insulated from heat generated by the pulses. Launching flyers with nanosecond laser pulses creates undesirable reverberating shocks in the flyer. In some cases, with 10 ns launch pulses, the thickest flyers were observed to lose integrity. But with stretched 20 ns pulses, we showed that the reverberations damped out prior to impact with targets, and that the flyers maintained their integrity during flight. Flyer impacts with salt, glass, fused silica, and acrylic polymer were studied by PDV, and the durations of fully supported shocks in those media were determined, and could be varied from 5 to 23 ns.

16.
J Genet Couns ; 23(2): 156-63, 2014 Apr.
Article in English | MEDLINE | ID: mdl-23793969

ABSTRACT

This study explores neurologists' and psychiatrists' knowledge, attitudes, and practices concerning genetic tests. Psychiatrists (n = 5,316) and neurologists (n = 2,167) on the American Medical Association master list who had agreed to receive surveys were sent an email link to a survey about their attitudes and practices regarding genetic testing; 372 psychiatrists and 163 neurologists responded. A higher proportion of neurologists (74%) than psychiatrists (14%) who responded to the survey had ordered genetic testing in the past 6 months. Overall, most respondents thought that genetic tests should be performed more frequently, but almost half believed genetic tests could harm patients psychologically and considered legal protections inadequate. Almost half of neurologists (49%) and over 75% of psychiatrists did not have a genetics professional to whom to refer patients; those who had ordered genetic tests were more likely than those who did not do so to have access to a genetic counselor. Of respondents, 10% had received patient requests not to document genetic information and 15% had received inquiries about direct-to-consumer genetic testing. Neurologists reported themselves to be relatively more experienced and knowledgeable about genetics than psychiatrists. These data, the first to examine several important issues concerning knowledge, attitudes and behaviors of neurologists and psychiatrists regarding genetic tests, have important implications for future practice, research, and education.


Subject(s)
Genetic Testing/statistics & numerical data , Health Knowledge, Attitudes, Practice , Inservice Training/organization & administration , Neurology , Psychiatry , Animals , Cats , Female , Humans , Male , Neurology/education , Psychiatry/education , Workforce
17.
ACS Appl Mater Interfaces ; 4(7): 3493-9, 2012 Jul 25.
Article in English | MEDLINE | ID: mdl-22642391

ABSTRACT

Plasma treatment of polymer materials introduces chemical functionalities and modifies the material to make the native hydrophobic surface more hydrophilic. It is generally assumed that this process only affects the surface of the material. We used vibrationally resonant sum-frequency generation spectroscopy to observe changes in the orientation of phenyl groups in polystyrene (PS) thin films on various substrates before and after plasma treatment. VR-SFG selectively probes regions of broken symmetry, such as surfaces, but can also detect the emergence of anisotropy. On dielectric substrates, such as fused silica, the spectroscopic peak corresponding to the symmetric stretching (ν2) mode of the phenyl rings was undetectable after plasma treatment, showing that surface phenyl rings were altered. This peak also diminished on conducting substrates, but the intensity of another peak corresponding to the same mode in a bulklike environment increased significantly, suggesting that plasma treatment induces partial ordering of the bulk polymer. This ordering is seen on conducting substrates even when the polymer is not directly exposed to the plasma. Annealing reverses these effects on the polystyrene bulk; however, the surface phenyl rings do not return to the orientation observed for untreated films. These results call into question the assumption that the effects of plasma treatment are limited to the free surface and opens up other possibilities for material modification with low-temperature plasmas.

18.
Waste Manag Res ; 30(4): 381-91, 2012 Apr.
Article in English | MEDLINE | ID: mdl-22363024

ABSTRACT

Mechanical processing using predominantly particle size and density as separation criteria is currently applied in the production of solid-recovered fuel or refuse-derived fuel. It does not sufficiently allow for the optimization of the quality of heterogeneous solid waste for subsequent energy recovery. Material-specific processing, in contrast, allows the separation criterion to be linked to specific chemical constituents. Therefore, the technical applicability of material-specific sorting of heterogeneous waste, in order to optimize its routing options, was evaluated. Two sorting steps were tested on a pilot and a large scale. Near infrared multiplexed sensor-based sorting devices were used (1) to reduce the chlorine (Cl) respectively pollutant content, in order to broaden the utilization options of SRF in industrial co-incineration, and (2) to increase the biogenic carbon (C(bio)) content, which is highly relevant in the light of the EU emission trading scheme on CO2. It was found that the technology is generally applicable for the heterogeneous waste fractions looked at, if the sensor systems are appropriately adjusted for the sorting task. The first sorting step allowed for the removal of up to 40% of the Cl freight by separating only 3 to 5% of the material mass. Very low Cl concentrations were achieved in the output stream to be used as solid-recovered fuel stream and additionally, the cadmium (Cd) and lead (Pb) concentration was decreased. A two- to four-fold enriched C(bio) content was achieved by the second sorting step. Due to lower yields in the large-scale test further challenges need to be addressed.


Subject(s)
Biofuels/analysis , Refuse Disposal/methods , Spectrophotometry, Infrared/methods , Waste Products/classification , Biofuels/economics , Carbon/analysis , Chlorine/analysis , Metals, Heavy/analysis , Pilot Projects , Refuse Disposal/economics , Waste Products/economics
19.
Anal Chem ; 84(4): 1862-70, 2012 Feb 21.
Article in English | MEDLINE | ID: mdl-22264066

ABSTRACT

In vibrationally resonant sum-frequency generation (VR-SFG) spectra, the resonant signal contains information about the molecular structure of the interface, whereas the nonresonant signal is commonly treated as a background and has been assumed to be negligible on transparent substrates. The work presented here on model chromatographic stationary phases contradicts this assumption. Model stationary phases, consisting of functionalized fused-silica windows, were investigated with VR-SFG spectroscopy, both with and without experimental suppression of the nonresonant response. When samples are moved from CD(3)OD to D(2)O, the VR-SFG spectrum was found to change over time when the nonresonant signal was present but not when the nonresonant signal was suppressed. No effect was seen when the solvent was changed and pressurized to 900 psi. These results suggest that the response to the new solvent manifests primarily in the nonresonant response, not the resonant response. Any structural changes caused by the new solvent environment appear to be minor. The nonresonant signal is significant and must be properly isolated from the resonant signal to ensure a correct interpretation of the spectral data. Curve-fitting procedures alone are not sufficient to guarantee a proper interpretation of the experimental results.

SELECTION OF CITATIONS
SEARCH DETAIL
...