Enhancing the photoluminescence of surface anchored metal-organic frameworks: mixed linkers and efficient acceptors.

We present two approaches to enhance the photoluminescence quantum yield (PLQY) of surface-anchored metal-organic frameworks (SURMOFs). In the first approach we fabricate SURMOFs from a mix of an emissive linker with an optically-inert linker of equivalent length, diluting the emissive linker while maintaining the SURMOF structure. This approach enhances the internal PLQY. However, the increase in internal PLQY is achieved at the expense of a drastic reduction in optical absorption, thus the external PLQY remains low. To overcome this limitation, a second approach is explored wherein energy-accepting guest chromophores are infiltrated into the framework of the active linker. At the correct acceptor concentration, an internal PLQY of 52% - three times higher than the previous approach - is achieved. Additionally, the absorption remains strong leading to an external PLQY of 8%, an order of magnitude better than the previous approach. Using this strategy, we demonstrate that SURMOFs can achieve PLQYs similar to their precursor chromophores in solution. This is of relevance to SURMOFs as emitter layers in general, and we examine the optimized emitter layer as part of a photon upconversion (UC) SURMOF heterostructure. Surprisingly, the same PLQY is not observed after triplet-triplet annihilation in the UC heterostructure as after its normal photoexcitation (although the UC layers exhibit low thresholds consistent with those reported in our previous work). We discuss the potential bottlenecks in energy transport that could lead to this unexpected reduction in PLQY after excitation via triplet-triplet annihilation, and how future design of SURMOF UC multilayers could overcome these limitations.

Infiltrated photonic crystals for light-trapping in CuInSe2 nanocrystal-based solar cells.

Solution processable nanocrystal solar cells combine the advantages of low-cost printing and wide range of accessible absorber materials, however high trap densities limit performance and layer thickness. In this work we develop a versatile route to realize the infiltration of a photonic crystal, with copper indium diselenide nanocrystal ink. The photonic crystal allows to couple incident light into pseudo-guided modes and thereby enhanced light absorption. For the presented design, we are able to identify individual guided modes, explain the underlying physics, and obtain a perfect match between the measured and simulated absorption peaks. For our relatively low refractive index layers, a 7% maximum integrated absorption enhancement is demonstrated.

Studies of TBX4 and chromosome 17q23.1q23.2: an uncommon cause of nonsyndromic clubfoot.

Clubfoot is a common birth defect characterized by inward posturing and rigid downward displacement of one or both feet. The etiology of syndromic forms of clubfoot is varied and the causes of isolated clubfoot are not well understood. A microduplication of 2.2 Mb on chromosome 17q23.1q23.2 which includes T-box 4 (TBX4), a hindlimb-specific gene, and 16 other genes was recently identified in 3 of 66 families reported as nonsyndromic clubfoot, but additional non-foot malformations place them in the syndromic clubfoot category. Our study assesses whether variation in or around TBX4 contributes to nonsyndromic clubfoot. To determine whether this microduplication was a common cause of nonsyndromic clubfoot, 605 probands (from 148 multiplex and 457 simplex families) with nonsyndromic clubfoot were evaluated by copy number and oligonucleotide array CGH testing modalities. Only one multiplex family (0.68%) that had 16 with clubfoot and 9 with other foot anomalies, had a 350 kb microduplication, which included the complete duplication of TBX4 and NACA2 and partial duplication of BRIP1. The microduplication was transmitted in an autosomal dominant pattern and all with the microduplication had a range of phenotypes from short wide feet and toes to bilateral clubfoot. Minimal evidence was found for an association between TBX4 and clubfoot and no pathogenic sequence variants were identified in the two known TBX4 hindlimb enhancer elements. Altogether, these results demonstrate that variation in and around the TBX4 gene and the 17q23.1q23.2 microduplication are not a frequent cause of this common orthopedic birth defect and narrows the 17q23.1q23.2 nonsyndromic clubfoot-associated region.

The effect of intermittent operation on a wind-powered membrane system for brackish water desalination.

Renewable energy powered membrane systems that are directly-connected must take account of both the inherent fluctuations and the intermittency of the energy resource. In order to determine the effect of intermittent operation, a membrane system was tested with variables of (i) amplitude from 60 to 300 W and (ii) length of time with no power from 0.5 to 3 min. This was performed over one hour periods with six on/off cycles to simulate the system operating under intermittent operation for short periods of time when directly-connected to a small wind turbine. The setup used a Filmtec BW30-4040 brackish water reverse osmosis membrane with feed waters of 2,750 mg/L and 5,500 mg/L NaCl. The results showed that the membrane system produced potable water under the majority of intermittency experiments performed. There was a relatively large increase in the average salt concentration of the permeate, especially when the system was off for shorter periods of time (0.5-1 min). Longer periods of no power (1-3 min) did not have as significant an effect on the average water quality. This is important when the need for energy buffering or short term storage is considered for these systems as it shows the potential for improving the overall flux and water quality using temporary energy storage.

Measurement method for photoluminescent quantum yields of fluorescent organic dyes in polymethyl methacrylate for luminescent solar concentrators.

A method for measuring the photoluminescent quantum yields (PLQY) of luminescent organic dyes is presented. The self-absorption probability calculated at different dye concentrations is used to determine the absolute quantum yield from the observed values. The results for a range of commercially available dyes show high quantum yields, even at high concentrations, and an absence of quenching. The PLQY of several dye mixtures are also presented. The results indicate an absence of any reduction of PLQY in a dye mixture as compared with the individual PLQY of the dyes.

Delayed infections following posterior spinal instrumentation for the treatment of idiopathic scoliosis.

Ten patients who had been managed with posterior spinal arthrodesis and Texas Scottish Rite Hospital instrumentation because of idiopathic scoliosis had a delayed deep wound infection at an average of twenty-five months after the operation. The signs of infection included spontaneous drainage in eight patients and fluctuance in two patients. In addition, six patients--including five of the eight who had drainage--had mild pain in the back. The average erythrocyte sedimentation rate was thirty-nine millimeters per hour (range, nineteen to eighty-one millimeters per hour). The instrumentation was removed from all of the patients. In two patients, a pseudarthrosis that had not been noted on preoperative radiographs was noted intraoperatively; in both patients, the pseudarthrosis occurred at a level at which two hooks had been placed in one intervertebral space. Primary closure was performed in seven patients, and delayed primary closure was performed on the third postoperative day in three patients. All wounds healed uneventfully. Cultures of specimens taken from deep within the wound were positive for Propionibacterium acnes (five patients), Staphylococcus epidermidis (two patients), a rare coagulase-negative Staphylococcus species (one patient), or Micrococcus varians (one patient). No organisms grew on culture of the specimen obtained from the remaining patient. Propionibacterium acnes required an extended period of incubation before identification. Antibiotics were administered parenterally to all of the patients after the removal of the hardware, and this treatment was followed by oral administration of antibiotics for nine of the patients. We suspect--but can not prove--that several of the delayed infections resulted from intraoperative seeding and remained subclinical for an extended period of time.

Subluxation of the femoral head in coxa plana.

Twenty-two patients who had severe coxa plana had closed reduction for lateral subluxation of the femoral head, as determined radiographically. All had painful limitation of motion of the hip that prevented proper positioning of the femoral head using a brace. The average age when the patients were first seen was eight years and six months. General anesthesia was required in order to obtain the reduction, and percutaneous tenotomy of the adductor longus was done whenever necessary. After the reduction, a Petrie cast was worn for several months. The length of follow-up averaged three years and eight months (range, two years to six years and eight months). Radiographic evaluation at the time of the last follow-up showed nine hips to be spherically congruent, twelve to be spherically congruent, and one to be incongruent. Thus, in 95 per cent of the hips, a congruent joint was obtained using this method of treatment. These results strongly support the concept that all treatment should be directed at containing the femoral head within the acetabulum during the clinically active phase of coxa plana.

Acute slipped capital femoral epiphysis: the importance of physeal stability.

To test the traditional classification system of slipped capital femoral epiphysis, we evaluated the presenting symptoms and radiographs of fifty-four patients and reclassified the slipped epiphyses as unstable or stable, rather than acute, chronic, or acute-on-chronic. Slips were considered to be unstable when the patient had such severe pain that weight-bearing was not possible even with crutches. Slips were considered to be stable when the patient could bear weight, with or without crutches. We reviewed the records on fifty-five hips in which the slip would have been classified as acute because the duration of symptoms was less than three weeks; thirty of these were unstable and twenty-five were stable. All slips were treated with internal fixation. A reduction occurred in twenty-six of the unstable hips and in two of the stable hips. Fourteen (47 per cent) of the thirty unstable hips and twenty-four (96 per cent) of the twenty-five stable hips had a satisfactory result. Avascular necrosis developed in fourteen (47 per cent) of the unstable hips and in none of the stable hips. We were not able to demonstrate an association between early reduction and the development of avascular necrosis.

Measurement error in assessment of vertebral rotation using the Perdriolle torsionmeter.

The Perdriolle torsionmeter assesses vertebral rotation on a spinal radiograph. It is frequently used to measure improvement in spinal derotation following Cotrel-Dubousset instrumentation for scoliosis. In this study, intraobserver and interobserver measurement error was examined during use of the torsionmeter. Intraobserver error was as follows: 53% of the measurements were accurate to within 5 degrees, and 21% erred greater than 10 degrees. Error from the actual value averaged 6 degrees. Interobserver error was as follows: Among six observers, only one third of the radiographs had measurements within 5 degrees of each other. Another one third erred by more than 10 degrees. Because of this significant intraobserver and interobserver error, precise measurements of rotation using the torsionmeter cannot be expected. Efforts to quantify spinal derotation with the torsionmeter after Cotrel-Dubousset instrumentation may not be valid.

Lumbar curve response in type II idiopathic scoliosis after posterior instrumentation of the thoracic curve.

Twenty-four patients with King Type II scoliosis were retrospectively studied to determine if preoperative assessment of lumbar curve flexibility was predictive of postoperative spinal balance. All patients had preoperative lumbar curves exceeding 40 degrees and all underwent selective thoracic fusion with Cotrel-Dubousset or Texas Scottish Rite Hospital instrumentation. The lumbar curves corrected 73% on preoperative bend radiographs. Despite this significant flexibility, the lumbar curves remained larger after surgery than the instrumented thoracic curves and spinal imbalance occurred. This finding was due, in part, to postoperative persistence of obliquity between L4 and the pelvis. When using Cotrel-Dubousset or Texas Scottish Rite Hospital instrumentation, preoperative assessment of the large lumbar curve's flexibility is not particularly helpful in predicting its response to selective thoracic fusion, especially regarding whether postoperative imbalance may occur.

Preventing the crankshaft phenomenon by combining anterior fusion with posterior instrumentation. Does it work?

STUDY DESIGN: Fourteen skeletally immature patients with idiopathic scoliosis (Group I) were retrospectively studied to determine if the crankshaft phenomenon was prevented by combining anterior spinal fusion with posterior instrumentation and fusion. They were compared with 12 similar patients who underwent posterior procedures only (Group II). OBJECTIVES: To determine whether the addition of anterior spinal fusion was beneficial in preventing progressive spinal deformity in the very young patient. SUMMARY OF BACKGROUND DATA: The crankshaft phenomenon had been well documented in young patients undergoing posterior fusion only. No previous study compared the results of a similar group of patients some of whom underwent combined anterior and posterior fusion and the others who underwent posterior fusion only. METHODS: Patients who were Risser O and had open triradiate cartilages at surgery were evaluated for curve correction, correction loss, changes in rib vertebral angle differences, rotational changes, and spinal balance. Crankshaft was defined as a progression in curve magnitude greater than 10 degrees and accompanied by an increase in rib vertebral angle difference greater than 10 degrees. In Group I, age at surgery averaged 10.7 years, and follow-up averaged 37 months. In Group II, age at surgery averaged 11.0 years, and follow-up averaged 64 months. RESULTS: Group I: Thoracic curve correction averaged 77% after surgery and 68% at follow-up. At follow-up, two patients had curves progress more than 10 degrees, and three patients had an increase in rib vertebral angle difference of 10 degrees or more, but none of the patients had these changes simultaneously. Group II: During the course of follow-up, five of the 12 patients had progressive changes of 10 degrees or more in curve size and rib vertebral angle difference. Four other patients had an increase exceeding 10 degrees in one of the two categories. CONCLUSIONS: In skeletally immature children (open triradiate cartilage and Risser O) with idiopathic scoliosis, the addition of anterior spinal fusion to posterior instrumentation and fusion is helpful in preventing the crankshaft phenomenon.

Anterior correction of idiopathic scoliosis using TSRH instrumentation.

The first 14 consecutive patients with idiopathic lumbar scoliosis treated by anterior Texas Scottish Rite Hospital (TSRH) instrumentation are reported. Frontal curve correction averaged 76%, with a 5 degrees (9%) loss of correction in the follow-up period, which averaged 17.6 months (range, 12-29). Spinal balance was improved an average of 1.8 cm toward the center sacral line, and apical vertebral rotation was corrected an average of 49%. Instrumentational kyphosis was minimal, with total L1-S1 lordosis decreasing an average of 1 degree, and no measured compensatory hyperlordosis caudal to the instrumented segment. One hundred percent of disc spaces were radiographically fused by 8 months. There were no neurologic, septic, or implant complications. The contoured solid rod used in this construct provides the same frontal and rotatory correction as previous systems, and minimizes instrumentational kyphosis. Fusion occurs rapidly and reliably because of the stiffness of the construct, which also may eliminate the need for postoperative immobilization.

Prediction of the crankshaft phenomenon by peak height velocity.

STUDY DESIGN: Retrospective review. OBJECTIVES: To evaluate the relation of the peak height velocity with the occurrence of the crankshaft phenomenon after posterior arthrodesis and instrumentation in idiopathic scoliosis. SUMMARY OF BACKGROUND DATA: Although patients with closed triradiate cartilages are unlikely to exhibit the crankshaft phenomenon after a posterior spinal fusion and instrumentation, open triradiate cartilages do not necessitate that crankshafting will occur. Less than half of patients with idiopathic scoliosis and open triradiate cartilages will exhibit the crankshaft phenomenon. METHODS: The authors reviewed 43 patients with idiopathic scoliosis who were Risser 0 at the time of posterior spinal fusion. Twenty-three patients had open triradiate cartilages and twenty had closed. The timing of peak height velocity was identified. RESULTS: All patients with closed triradiate cartilages were beyond their peak height velocity at the time of surgery. Among those with open triradiate cartilages, 8 were operated on before or during their peak and 15 were operated on afterward. All patients fused before or during the peak crankshafted. Two of the fifteen patients fused after the peak crankshafted. In one, it was low grade. In the other, it appears that the fusion blunted the peak height velocity to a point at which it was unidentifiable. CONCLUSIONS: In patients with open triradiate cartilages, surgery performed before or during the peak height velocity is a strong predictor of the crankshaft phenomenon, and later surgery is a strong negative predictor of the crankshafting (P = 0.000009). Isolated posterior fusion before the height velocity decelerates results in the crankshaft phenomenon, whereas fusion during the deceleration phase does not.

A comparison of single-rod instrumentation with double-rod instrumentation in adolescent idiopathic scoliosis.

STUDY DESIGN: A consecutive series of patients with idiopathic scoliosis treated with single-rod instrumentation was followed prospectively. Outcomes were compared with results obtained from a retrospective review of a consecutive series of patients treated with double-rod instrumentation. OBJECTIVE: To compare single-rod instrumentation with segmental fixation with double-rod instrumentation for the treatment of adolescent idiopathic scoliosis. SUMMARY OF BACKGROUND DATA: Mechanical testing of single-rod instrumentation with segmental fixation at every level showed it to be as resistant to torsion as a double-rod construct. A clinical trial was initiated to document the clinical outcome in single-rod patients. METHODS: A total of 43 of 51 consecutive patients underwent spinal fusion with a single rod. Outcome was evaluated at a minimum of 2 years after surgery. The control group comprised 103 patients who had standard double-rod instrumentation at the same institution. RESULTS: The single- and double-rod groups were similar with respect to age, sex, curve type, length of follow-up, curve magnitude, and best bend. For King III-V curves undergoing posterior spinal fusion, there was significantly less blood loss in the single-rod group (703 mL vs 1011 mL), less cell saver collection (189 mL vs 367 mL), and less operating time (220 minutes vs 260 minutes). Blood loss and operating time were not different for patients with King I and King II curves. There were eight patients (19%) requiring reoperation because of hardware-related problems in the single-rod group compared with four (4%) in the double-rod group. There were nine patients (21%) with broken rods in the single-rod group, six of whom were symptomatic and five of whom required reoperation. Two patients required multiple operations because of pseudarthrosis in the single-rod group. There were no broken rods in the double-rod group. The single-rod group had 2 early postoperative infections and no late infections compared with 10 late infections in the double-rod group. There was a statistically significant relationship between hardware problems and fusion below L1 in the single-rod group. CONCLUSION: Because of rod failure, single-rod instrumentation should be considered only in curves that can be instrumented to L1 and higher.

A comparison between the Boston brace and the Charleston bending brace in adolescent idiopathic scoliosis.

STUDY DESIGN: The authors studied 319 patients with adolescent idiopathic scoliosis treated at the same institution with either a Boston brace or a Charleston bending brace. OBJECTIVES: To determine if both orthoses are equally effective in stopping curve progression and preventing the need for surgical correction. SUMMARY OF BACKGROUND DATA: Early reports suggest that the Charleston brace may be comparable to the Boston brace in its effectiveness and that both braces positively influence the natural history of idiopathic scoliosis. METHODS: Skeletally immature (Risser 0, 1, or 2) patients with idiopathic scoliosis who were 10 years old or older at the time of brace prescription, had curves from 25 degrees to 45 degrees, and had no prior treatment were studied retrospectively. All measurements were collected by a single observer, and all patients were followed up to skeletal maturity. RESULTS: The Boston brace is more effective than the Charleston brace, both in preventing curve progression and in avoiding the need for surgery. These findings were most notable for patients with curves of 36 degrees-45 degrees, in whom 83% of the those treated with a Charleston brace had curve progression of more than 5 degrees, compared with 43% of those treated with the Boston brace (p < 0.0001). CONCLUSION: When given the choice between these two orthoses in the treatment of adolescent idiopathic scoliosis, the authors recommend use of the Boston brace. The Charleston brace should be considered only in the treatment of smaller single thoracolumbar or single lumbar curves.

Treatment of adolescent idiopathic scoliosis using Texas Scottish Rite Hospital instrumentation.

STUDY DESIGN: To determine the effectiveness of posterior TSRH instrumentation for the treatment of idiopathic scoliosis, 103 patients with a 2-year minimum followup were retrospectively studied. METHODS: Patients who underwent operations between October 1988 and April 1991 were evaluated for curve correction, spinal balance, and complications. Age at surgery averaged 14.3 years. Follow-up averaged 2.5 years. RESULTS: Thoracic curve correction averaged 65% in those with King Type III/IV curves and 54% in those with Type II curves. With follow-up, correction loss averaged approximately 13% for each group. Lumbar curve correction after instrumentation in Type I and II curves averaged 48% postop but lost approximately 20% with follow-up. Trunk balance improved 77% toward midline after surgery in those with Type III/IV curves. Improvement in trunk balance was less impressive in patients with Type II curves, particularly after selective thoracic fusions. Thoracic sagittal contour improved 43% for hypokyphotic (< 20 degrees) patients but, in the remainder, no significant radiographic change was evident. No neurologic complications occurred. Delayed deep infections developed in ten patients (10%) between 11 and 45 months postoperative. Cultures eventually grew Propionibacterium acnes, staph epidermidis, or staph coagulase negative in eight patients. Two patients had pseudarthroses. CONCLUSIONS: Frontal and sagittal thoracic curve correction can be satisfactorily obtained using TSRH instrumentation. Continued efforts are being made to improve lumbar hook patterns and technique to achieve and maintain better lumbar curve correction.

Frontal plane and sagittal plane balance following Cotrel-Dubousset instrumentation for idiopathic scoliosis.

Postoperative decompensation has been reported following Cotrel-Dubousset instrumentation for right thoracic idiopathic scoliosis. The authors examined balance in the frontal and sagittal planes in 53 patients to determine optimal levels for fusion. King et al Type II curves, particularly larger ones, shifted to the left when the thoracic curve was fused to the stable vertebra or just below. Most Type III curves balanced well regardless of the levels fused. One-third of all patients developed mild radiographic junctional kyphosis at the lower level instrumented, more commonly when instrumentation ended at or above T12. The authors recommend fusing one segment short of the stable vertebra in most Type II curves. Large Type II curves need both curves fused for optimal balance. Type III curves can be fused short of the stable vertebra.

Hemodilution as a method to reduce transfusion requirements in adolescent spine fusion surgery.

STUDY DESIGN: A case-control study. OBJECTIVES: 1) To determine if hemodilution adequately meets the transfusion needs in children who undergo posterior spinal fusion for idiopathic scoliosis and 2) to compare the efficacy of the various methods used to reduce the risk of allogeneic blood transfusion at the authors' institution. SUMMARY OF BACKGROUND DATA: Methods to reduce blood loss and avoid allogeneic blood transfusion caused by extensive spinal surgery in adolescents include 1) autologous blood predonation, 2) controlled hypotensive anesthesia, 3) intraoperative salvage of shed blood (cell saver), 4) acute normovolemic hemodilution, and 5) transfusion decisions by clinical judgment rather than by a preset value of hemoglobin. Although all methods have some efficacy, it is not clear which methods, separate or combined, are best in the adolescent scoliosis population. METHODS: Hemodilution, hypotensive anesthesia, and cell saver were used in 43 children between June 1996 and July 1997. A comparison group (43 children) underwent similar surgery with hypotensive anesthesia and cell saver, but no hemodilution (between July 1995 and December 1996). These two groups were similar with respect to means of age, levels of instrumentation, magnitude of curvature, estimated blood volume, mean arterial pressure, duration of surgery, duration of anesthesia, estimated blood loss, volume returned from cell saver, volume in the hemovac drain, and length of hospitalization. The groups differed in preoperative hemoglobin and hematocrit and in volume of crystalloid used. RESULTS: Transfusions were given to 34 of 43 patients (79%) in the nonhemodilution group. These patients received 61 units of packed cells (57 autologous, 2 donor directed, and 2 allogeneic). In comparison, 16 of 43 patients (37%) in the hemodilution group required transfusion. They received 16 units of packed cells (15 autologous and 1 allogeneic). There was no significant difference between the groups with respect to postoperative hemoglobin and hematocrit immediately after surgery (hemodilution, 10.2/29.2; nonhemodilution, 10.0/29.1), postoperative day 1 (hemodilution, 9.2/26.9; nonhemodilution, 9.2/27.3), and postoperative day 2 (hemodilution 9.0/26.4; nonhemodilution, 9.2/27.1). There were non complications related to the technique of hemodilution in the 43 patients of this group. Cell saver was used in all patients, but sufficient volume to return blood to the patient was available in only 23 hemodilution patients (mean volume, 230 mL) and 25 nonhemodilution patients (mean volume, 215 mL). In only two patients of each group (< 5%) did the volume returned prevent the absolute need for additional transfusions. CONCLUSIONS: Hemodilution was safely used as a method to satisfy the perioperative transfusion requirements of adolescents undergoing extensive spinal surgery. By allowing patients to arrive at surgery with a higher preoperative hemoglobin and hematocrit, and by decreasing the quantity of predonated autologous blood-collected and therefore used, the hemodilution method may indirectly decrease the quantity of postoperative autologous transfusions in this population. Cell saver was not shown to be effective, and its selective use is recommended.

Back pain in childhood and adolescence.

A variety of disorders can account for back pain in the child or adolescent (Outline 1). Some of these can result in significant morbidity if not properly diagnosed and treated. Fortunately, nearly all can be correctly diagnosed by taking a thorough medical history, performing a complete physical examination, and obtaining appropriate imaging and laboratory studies. Although back pain in children and adolescents may result from overuse or minor trauma and will respond to rest and anti-inflammatories, this review should enable the orthopaedist to systematically recognize those back disorders in need of more aggressive medical intervention.

Geropsychiatric nursing. Present issues and future challenges.

Geropsychiatric nursing has evolved over the past 20 years in response to the complex health care needs of our rapidly expanding older population. Because of the nonspecific presentation of both physical and mental symptoms, the assessments, interventions, and coordination of resources must occur from several vantage points. The challenge has been to blend gerontologic and psychiatric nursing and to incorporate community health and medical-surgical nursing. Older adults are vastly diverse in their past life experiences, culture, ethnicity, lifestyles, current physical and mental conditions, and resources. This necessitates and interdisciplinary approach to practice and presents many challenges for research.