Investigation Into the Effects of Intra-Articular Steroid on Post-Traumatic Osteoarthritis in Distal Radius Fractures: A Randomized Controlled Pilot Study.

PURPOSE: The aim of this prospective, randomized, controlled, double-blinded pilot study was to determine the rates of post-traumatic osteoarthritis and assess joint space width in the presence or absence of a single intra-articular injection of corticosteroid after an acute, intra-articular distal radius fracture (DRF). METHODS: Forty patients received a single, intra-articular, radiocarpal joint injection of 4 mg of dexamethasone (DEX) (n = 19) or normal saline placebo (n = 21) within 2 weeks of a surgically or nonsurgically treated intra-articular DRF. The primary outcome measure was minimum radiocarpal joint space width (mJSW) on noncontrast computed tomography scans at 2 years postinjection. Secondary outcomes were obtained at 3 months, 6 months, 1 year, and 2 years postinjection and included Disabilities of the Arm, Shoulder, and Hand; Michigan Hand Questionnaire; Patient-Rated Wrist Evaluation; wrist range of motion; and grip strength. RESULTS: At 2-year follow-up, there was no difference in mean mJSW between the DEX group (2.2 mm; standard deviation, 0.6; range, 1.4-3.2) and the placebo group (2.3 mm; standard deviation, 0.7; range, 0.9-3.9). Further, there were no differences in any secondary outcome measures at any postinjection follow-up interval. CONCLUSIONS: Radiocarpal joint injection of corticosteroid within 2 weeks of an intra-articular DRF does not appear to affect the development of post-traumatic osteoarthritis within 2 years follow-up in a small pilot cohort. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic II.

Targeted Muscle Reinnervation to Reduce Postoperative Pain in Patients Undergoing Hindquarter Resections.

BACKGROUND/AIM: Pre-emptive targeted muscle reinnervation (TMR) at the time of amputation results in less phantom limb pain (PLP) compared with untreated amputee controls. There is limited literature describing the technique in patients undergoing hindquarter amputation despite up to 90% of these patients reporting PLP and 50% presenting with painful neuroma. The purpose of the current study was to describe the motor nerves accessible through a primary hind-quarter amputation to be used for TMR and review pain outcomes in clinical case correlates of patients with TMR. PATIENTS AND METHODS: Six limbs were obtained from three fresh adult cadavers and proximal sensory and motor nerves were dissected. A review of patients undergoing hindquarter amputation with TMR was conducted. RESULTS: Transfers for the sciatic, femoral, and obturator nerves were identified in cadavers. In reviews of patients, they were taking narcotic and neuro-leptic pain medication for a mean of 23 days and 168 days. At most recent follow-up, no patient reported debilitating phantom pain nor pain associated with neuromas. CONCLUSION: Given the positive preliminary results in our study group as well as the accessible neuroanatomy, pre-emptive TMR should be considered at the time of surgery to limit PLP and dependence on pain medications.

Maximizing Solid Organ and Face Transplant Procurement Team Coordination: The Posterior Tibial Artery Flap as an Ideal Sentinel Flap.

Face transplantation became a reality with the first case performed in 2005. Facial tissue allograft procurement is technically complex and time-intensive. Brain-dead deceased donors are frequently, if not always, multiorgan donors. Every effort should be made during face allograft recovery to minimize any risk to the recovery of lifesaving solid organs. Some programs require the procurement of a myofascial vascularized skin graft to function as a sentinel flap allowing frequent monitoring for rejection without negatively impacting the esthetics of the face graft. Up till now, the flap used has been the radial forearm flap. Procuring the radial forearm flap places the procuring team in close proximity to the head and torso, where the face recovery and the solid organ recovery teams would require unhindered access. Here, we present the posterior tibial artery flap as an alternative flap that would provide benefits to the coordination of the multiple teams working to procure organs from a deceased donor.

Coordination Chemistry as a Universal Strategy for a Controlled Perovskite Crystallization.

The most efficient and stable perovskite solar cells (PSCs) are made from a complex mixture of precursors. Typically, to then form a thin film, an extreme oversaturation of the perovskite precursor is initiated to trigger nucleation sites, e.g., by vacuum, an airstream, or a so-called antisolvent. Unfortunately, most oversaturation triggers do not expel the lingering (and highly coordinating) dimethyl sulfoxide (DMSO), which is used as a precursor solvent, from the thin films; this detrimentally affects long-term stability. In this work, (the green) dimethyl sulfide (DMS) is introduced as a novel nucleation trigger for perovskite films combining, uniquely, high coordination and high vapor pressure. This gives DMS a universal scope: DMS replaces other solvents by coordinating more strongly and removes itself once the film formation is finished. To demonstrate this novel coordination chemistry approach, MAPbI3 PSCs are processed, typically dissolved in hard-to-remove (and green) DMSO achieving 21.6% efficiency, among the highest reported efficiencies for this system. To confirm the universality of the strategy, DMS is tested for FAPbI3 as another composition, which shows higher efficiency of 23.5% compared to 20.9% for a device fabricated with chlorobenzene. This work provides a universal strategy to control perovskite crystallization using coordination chemistry, heralding the revival of perovskite compositions with pure DMSO.

Microvascular Free Flap Reconstruction of Thigh Defects After Tumor Resection in the Setting of Radiation.

BACKGROUND: Soft tissue reconstruction of the thigh defects can usually be achieved with local options. Free tissue transfer may be indicated in very large defects with exposed vital structures and/or a history of radiation therapy where the healing potential of local option is poor. In this study, we evaluated our experience on microsurgical reconstruction of oncological and irradiated thigh defects to assess the risk factors for complications. METHODS: Institutional review board-approved retrospective case series study using electronic medical records from 1997 to 2020 was conducted. All patients with irradiated thigh defects derived from oncological resections who underwent microsurgical reconstruction were included. Patient demographics and clinical and surgical characteristics were recorded. RESULTS: Twenty free flaps were transferred in 20 patients. Mean age was 60 ± 11.8 years, and median follow-up time was 24.3 months (interquartile range [IQR], 71.4-9.2 months). The most common type of cancer was liposarcoma (n = 5). Neoadjuvant radiation therapy was performed in 60%. Most commonly used free flaps were latissimus dorsi muscle/musculocutaneous flap (n = 7) and anterolateral thigh flap (n = 7) Nine flaps were transferred immediately after resection. Overall, 70% of arterial anastomoses were end-to-end, whereas 30% were end-to-side. Deep femoral artery branches were chosen as the recipient artery in the 45%. Median length of hospital stay was 11 days (IQR, 16.0-8.3 days), and median time to start weight-bearing was 20 days (IQR, 49.0-9.5 days). All were successful except for 1 patient who required additional pedicled flap coverage. The overall major-complication rate was 25% (n = 5, hematoma = 2, venous congestion requiring emergent exploration surgery = 1, wound dehiscence = 1, surgical site infection = 1). Cancer recurred in 3 patients. One required amputation due to cancer recurrence. Age (hazard ratio [HR], 1.14; P = 0.0163), tumor volume (HR, 18.8; P = 0.0006), and resection volume (HR, 2.24; P = 0.0019) were statistically significantly associated with having a major complication. CONCLUSIONS: Based on the data, microvascular reconstruction of irradiated post-oncological resection defects shows high flap survival rate and success. Given the large size of flap required, the complex nature and size of these wounds, and history of radiation, wound healing complications are common. Despite this, free flap reconstruction should be considered in irradiated thighs with large defects. Studies with larger cohort and longer follow-up are still required.

Radical polymeric p-doping and grain modulation for stable, efficient perovskite solar modules.

High-quality perovskite light harvesters and robust organic hole extraction layers are essential for achieving high-performing perovskite solar cells (PSCs). We introduce a phosphonic acid-functionalized fullerene derivative in mixed-cation perovskites as a grain boundary modulator to consolidate the crystal structure, which enhances the tolerance of the film against illumination, heat, and moisture. We also developed a redox-active radical polymer, poly(oxoammonium salt), that can effectively p-dope the hole-transporting material by hole injection and that also mitigates lithium ion diffusion. Power conversion efficiencies of 23.5% for 1-square-centimeter mixed-cation-anion PSCs and 21.4% for 17.1-square-centimeter minimodules were achieved. The PSCs retained 95.5% of their initial efficiencies after 3265 hours at maximum power point tracking under continuous 1-sun illumination at 70° ± 5°C.

Long-term survival analysis of free flap reconstruction in patients with collagen vascular disorders.

BACKGROUND: Collagen vascular disorders (CVD) are inflammatory diseases that can affect the blood vessels and soft tissues. Patients with CVD are often immunosuppressed, prone to hyper-coagulation, and represent a challenging patient cohort for free tissue transfer. METHODS: A retrospective review of patients with CVD who underwent free flap reconstructions from 2000-2020 was performed at our institution. Inclusion criteria were patients 18 years old or older with the clinical diagnosis of CVD, including rheumatoid arthritis, Raynaud phenomenon, systemic lupus erythematosus, scleroderma, and sarcoidosis. A time-to-event analysis was performed to identify predictors of surgical complications. RESULTS: A total of 78 patients and 96 free flaps were included. The most common CVD were rheumatoid arthritis (n=36) and Raynaud's phenomenon (n=9). Type of flap included abdominal-based flap (26%), trunk-based flaps (32.3%), and extremity-based flaps (19.8%). The mean age was 56.7±14.6 years, and the mean BMI was 27.5±5.9 kg/m2. Antibody positivity was present in 25.6% of patients; 59% were on chronic steroids, 6.4% were on chronic anticoagulation, 35.9% had radiation therapy, and 29.5% had chemotherapy. Nine percent of patients had a history of prior flap loss, and 11.5% had a history of DVT or arterial thrombosis. The flap loss rate was 3.8%. Steroid treatment was associated with an increased risk of major complications after adjusting for the type of flap HR 2.5(1.3-4.9), p= 0.01. Specifically associated with a higher risk of cellulitis, OR 5.1 (1.1-24.5), p=0.02, and abscess, OR 5.7 (1.2-27.1), p=0.01. CONCLUSION: Free flap reconstruction can be safely performed in patients with CVD. Perioperative optimization of steroids is important to promote wound healing and stabilize disease activity.

Vertical rectus abdominis myocutaneous flap to reconstruct thigh and groin defects: A retrospective cohort and systematic review.

BACKGROUND: The vertical rectus abdominis myocutaneous (VRAM) flap is one of the options for soft-tissue reconstruction in the groin and thigh. The aim of this study is to evaluate the clinical outcomes, risk factors for complications, and the utility of using mesh to prevent abdominal hernia. METHODS: A retrospective review of patients who underwent VRAM flap reconstruction to reconstruct proximal thigh and groin defects from 1997 to 2018 was performed. Data regarding patient demographics, surgical characteristics, and postoperative outcomes were collected. Proportional hazard regression analysis was performed to assess the association of the risk of recipient site complications. A systematic review was performed to assess the outcomes and summarize the evidence from published studies. RESULTS: Fifty-three patients were identified and included in this study. In most of the cases, the procedures were performed after tumor resection (77%) and in the rest of the cases, they were performed for chronic complicated wounds (23%). Twenty-five (47.2%) patients developed complications. Intraoperative and postoperative radiotherapy, chronic kidney disease, history of prior tumor resection, and reconstructions of chronic complicated wounds were associated with an increased risk of recipient site complications. A systematic review identified 9 articles, for a total of 189 reconstructions. The pooled complications and failure rates were 31.2% and 2.1%, respectively. Stratified analysis showed that the rate of abdominal hernia was similar in patients with mesh (16.7%) and in patients with primary closure only (15.1%; p = 0.761). CONCLUSION: Defects in the groin or proximal thigh can be treated successfully with the VRAM flap. Although wound complications and hernia rates are high, the reconstruction failure rate is low.

Clinical and Radiological Safety of Retained Implantable Doppler Devices Used for Free Flap Monitoring.

INTRODUCTION: Implantable Doppler devices are reliable adjuncts used for free flap monitoring. Occasionally, the probe/wire is not removed and remains in the soft tissues. The clinical safety of the retained probes and safety and compatibility with magnetic resonance imaging (MRI) have not been studied. We present a series of retained implantable Doppler probes examining clinic outcomes, safety and compatibility with MRI, and effect on MRI image quality. METHODS: A retrospective review was conducted of patients who had an implantable Doppler device for free flap monitoring between July 2007 and August 2018. Routine post-operative imaging was reviewed for all patients to identify incidental findings of a retained probe. A subset of patients with retained implantable Doppler probes who underwent MRI was identified. Magnetic resonance images were reviewed to detect any degradation of image quality. RESULTS: A total of 323 patients who had an implantable Doppler device placed were reviewed 18 (5.6%) patients were identified with a retained probe and were included in this study. Mean age was 49 years with mean follow-up of 34.4 months. One potential device-related complication occurred in 1 (5.6%) patient. A total of 32 MRI scans were performed in 8 patients with retained devices, including 6 patients who underwent a total of 21 MRIs of the surgical site. There were no complications related to the MRI scans, and we found no significant degradation of image quality. CONCLUSION: Retained implantable Doppler probes were not associated with substantial adverse clinical outcomes nor affected MRI image quality of the surgical site.

INTRODUCTION: Les dispositifs de Doppler implantables sont fiables pour compléter la surveillance des lambeaux libres. Il arrive que la sonde ou le fil ne soit pas retiré et demeure dans les tissus mous. La sécurité clinique de ces sondes et leur compatibilité avec l'imagerie par résonance magnétique n'ont pas fait l'objet d'études. Les auteurs examinent les résultats cliniques d'une série de sondes de Doppler implantables laissées dans les tissus, de même que leur sécurité, leur compatibilité avec l'IRM et leur effet sur la qualité de l'image d'IRM. MÉTHODOLOGIE: Les chercheurs ont effectué une analyse rétrospective des patients à qui on avait implanté un dispositif de Doppler pour surveiller un lambeau libre entre juillet 2007 et août 2018. Ils ont analysé l'imagerie postopératoire systématique de tous les patients pour trouver les observations fortuites de sonde laissée dans les tissus. Ils ont extrait un sous-groupe de patients qui présentaient une sonde de Doppler implantable laissée dans les tissus et ont examiné l'IRM pour déceler toute dégradation de la qualité de l'image. RÉSULTATS: Sur un total de 323 patients à qui on avait implanté un dispositif de Doppler, 18 (5,6%) présentaient une sonde laissée dans les tissus et ont été inclus dans l'étude. D'un âge moyen de 49 ans, ils avaient reçu un suivi moyen de 34,4 mois. Un patient (5,6%) a subi une complication susceptible d'avoir été causée par le dispositif. Au total, les chercheurs ont effectué 32 IRM chez huit patients dont une partie du dispositif avait été laissée dans les tissus, y compris six patients qui ont subi un total de 21 IRM au foyer chirurgical. Ils n'ont constaté aucune complication liée à l'IRM et aucune dégradation importante de la qualité de l'image. CONCLUSION: Les sondes de Doppler implantable laissées dans les tissus n'entraînaient pas de résultats cliniques indésirables importants ni ne nuisaient à la qualité de l'IRM au foyer chirurgical.

Frequency, Pattern, and Treatment of Hand Fractures in Children and Adolescents: A 27-Year Review of 4356 Pediatric Hand Fractures.

Background: The frequency, pattern, and treatment of pediatric hand fractures are rarely reported. We sought to review our institution's experience in the management of pediatric hand fractures. Methods: A retrospective review of children and adolescents (younger than 18 years) treated for hand fractures between January 1990 and June 2017 was preformed. Fractures were categorized into metacarpal, proximal/middle phalanx, distal phalanx, or intra-articular metacarpophalangeal (MCP)/proximal interphalangeal (PIP)/distal interphalangeal (DIP) fractures. Patients were categorized into 3 age groups (0-5, 6-11, and 12-17 years). Results: A total of 4356 patients were treated for hand fractures at a mean ± SD age of 12.2 ± 3.5 years. Most fractures occurred in patients aged 12 to 17 years (n = 2775, 64%), followed by patients aged 6 to 11 years (n = 1347, 31%). Only 234 (5%) fractures occurred in children younger than 5 years. Most fractures occurred in the proximal/middle phalanx (48%), followed by metacarpal (33%), distal phalangeal (12%), and intra-articular MCP/PIP/DIP joints (7%). Proximal/middle phalangeal fractures were the most common in all age groups. About 58% of intra-articular MCP/PIP/DIP fractures in patients aged between 0 and 5 years required open reduction ± fixation, and the remaining 42% fractures were amenable to closed reduction. In patients older than 5 years, about 70% of these fractures were amenable to closed reduction. All age groups included, most metacarpal (93%), proximal/middle phalangeal (92%), and distal phalangeal (86%) fractures were amenable to closed reduction alone. Conclusions: The frequency, pattern, and treatment of hand fractures vary among different age groups. Understanding the pattern of these fractures helps making the right diagnosis and guides choosing the appropriate treatment.

Free Flap Coverage for Complex Primary and Revision Total Knee Arthroplasty.

BACKGROUND: Free flap coverage in the setting of a total knee arthroplasty is rare. The purpose of the current study was to evaluate the outcome of patients who underwent a free flap to assist with soft-tissue coverage following a complex total knee arthroplasty. METHODS: The authors used their institutional total joint registry to retrospectively review patients undergoing a free soft-tissue flap in the setting of complex primary and revision total knee arthroplasty. Among 29,069 primary and 6433 revision total knee arthroplasties from 1994 to 2017, eight (0.02 percent) required a free flap for wound coverage. This included three primary total knee arthroplasties (0.01 percent) for posttraumatic arthritis and five revision total knee arthroplasties (0.07 percent) in the setting of infection. Median follow-up was 4 years. RESULTS: Free flaps included vertical rectus abdominis (n = 3), anterior lateral thigh (n = 2), latissimus (n = 2), and transverse rectus abdominis (n = 1). There were no total flap losses; however, one patient required additional skin grafting. Reoperation occurred in six patients, of which four were revisions of the total knee arthroplasty for infection (n = 2) and tibial component loosening (n = 2). One patient ultimately underwent transfemoral amputation for persistent infection. Following reconstruction, there was improvement in the median Knee Society Score (49 versus 82; p = 0.03) and total range of motion between preoperative and postoperative assessments (70 degrees versus 85 degrees; p = 0.14). CONCLUSION: Free flap coverage in the setting of total knee arthroplasty was associated with a high rate of reoperation; however, the limb was able to be preserved in the majority of patients, with a reasonable functional outcome. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.

Internal Magnetic Lengthening and Reconstruction with Free TRAM Flap After Traumatic Transfemoral Amputation: A Case Report.

CASE: This is a case of a 41-year-old man who sustained a traumatic proximal transfemoral amputation with loss of adductor function and inadequate soft tissue. Wound closure was achieved with split-thickness skin grafting. Subsequently, femoral lengthening was achieved with an internal magnetic lengthening nail. He underwent a free transverse rectus abdominis myocutaneous (TRAM) flap to resurface the limb and provide more stable soft tissue, adductor repair, and further lengthening because of his prominent abduction contracture and inadequate soft tissue. This allowed independent ambulation with a prosthetic. CONCLUSION: Femoral lengthening with soft-tissue reconstruction improved prosthetic function and ambulation in a patient with a short transfemoral amputation.

Nanoscale Phase Segregation in Supramolecular π-Templating for Hybrid Perovskite Photovoltaics from NMR Crystallography.

The use of layered perovskites is an important strategy to improve the stability of hybrid perovskite materials and their optoelectronic devices. However, tailoring their properties requires accurate structure determination at the atomic scale, which is a challenge for conventional diffraction-based techniques. We demonstrate the use of nuclear magnetic resonance (NMR) crystallography in determining the structure of layered hybrid perovskites for a mixed-spacer model composed of 2-phenylethylammonium (PEA+) and 2-(perfluorophenyl)ethylammonium (FEA+) moieties, revealing nanoscale phase segregation. Moreover, we illustrate the application of this structure in perovskite solar cells with power conversion efficiencies that exceed 21%, accompanied by enhanced operational stability.

Vapor-assisted deposition of highly efficient, stable black-phase FAPbI3 perovskite solar cells.

Mixtures of cations or halides with FAPbI3 (where FA is formamidinium) lead to high efficiency in perovskite solar cells (PSCs) but also to blue-shifted absorption and long-term stability issues caused by loss of volatile methylammonium (MA) and phase segregation. We report a deposition method using MA thiocyanate (MASCN) or FASCN vapor treatment to convert yellow δ-FAPbI3 perovskite films to the desired pure α-phase. NMR quantifies MA incorporation into the framework. Molecular dynamics simulations show that SCN- anions promote the formation and stabilization of α-FAPbI3 below the thermodynamic phase-transition temperature. We used these low-defect-density α-FAPbI3 films to make PSCs with >23% power-conversion efficiency and long-term operational and thermal stability, as well as a low (330 millivolts) open-circuit voltage loss and a low (0.75 volt) turn-on voltage of electroluminescence.

Long-term clinical and patient-reported outcomes in free flap reconstruction of the weight-bearing heel pad and non-weight-bearing Achilles tendon regions.

BACKGROUND: The non-weight-bearing (NWB) Achilles tendon and weight-bearing (WB) heel pad regions are technically challenging to reconstruct with distinct functional and aesthetic considerations that have not been previously considered in the literature. This study is the first to characterize the long-term clinical and patient-reported outcomes of these components to better inform patients about the postreconstruction period. METHODS: A retrospective review of medical records and phone-based survey of adult patients who underwent free flap reconstruction of the heel/ankle with 6-month minimum clinical follow-up was performed. RESULTS: Forty-three patients, with 31 (72.1%) NWB and 12 (27.9%) WB defects, treated from January 1, 2000 to February 28, 2017 were included. Muscle flaps were more common than fasciocutaneous flaps (N = 36 [83.7%] vs. 7 [16.3%]). Flap survival rate was 95.3% and limb salvage rate was 93.0% at median follow-up of 12.0 months (interquartile range [IQR] 6.2, 25.5). Flap ulceration occurred more frequently in the WB region (41.7 vs. 6.5%, p = .0123). The survey response rate was 63.6%. The majority of patients complete daily tasks with no/little impairment (76.2%), walk half a mile or more (85.7%), returned to work (86.6%), and fit shoes "fair" or "well" (71.4%). Most patients were "very satisfied" with heel/ankle function (71.4%) and would "very likely" undergo the same procedure if needed (76.2%). CONCLUSIONS: Free flap reconstruction in both the NWB Achilles tendon and WB heel pad has excellent limb salvage and flap survival rates. Patients were satisfied with heel/ankle function, but additional counseling is recommended for variance in appearance and higher ulceration rates in WB defects.

Complex Microsurgical Reconstruction After Tumor Resection in the Trunk and Extremities.

Reconstruction of soft tissue defects following tumor ablation procedures in the trunk and extremities can challenge the microsurgeon. The goal is not just to provide adequate soft tissue coverage but also to restore form and function and minimize donor site morbidity. Although the principles of the reconstructive ladder still apply in the trunk and extremities, free tissue transfer is used in many cases to optimally restore form and function. Microsurgery has changed the practice in soft tissue tumors, and amputation is less frequently necessary.

Maximizing the Utility of the Pedicled Anterolateral Thigh Flap for Locoregional Reconstruction: Technical Pearls and Pitfalls.

The pedicled anterolateral thigh (PALT) flap is an underutilized flap for locoregional reconstruction largely because methods to maximize its reach are neither universally implemented nor fully understood. In addition, most of the available literature has focused on the utility of the free anterolateral thigh flap with less emphasis on the PALT flap. Moreover, flap design concepts to maximize its utility and reach and optimize outcomes have not been comprehensively described. In an effort to address this knowledge gap, the authors sought to review their institution's experience with the PALT flap for locoregional reconstruction.

Phenanthrene-Fused-Quinoxaline as a Key Building Block for Highly Efficient and Stable Sensitizers in Copper-Electrolyte-Based Dye-Sensitized Solar Cells.

Dye-sensitized solar cells (DSSCs) based on CuII/I bipyridyl or phenanthroline complexes as redox shuttles have achieved very high open-circuit voltages (VOC , more than 1 V). However, their short-circuit photocurrent density (JSC ) has remained modest. Increasing the JSC is expected to extend the spectral response of sensitizers to the red or NIR region while maintaining efficient electron injection in the mesoscopic TiO2 film and fast regeneration by the CuI complex. Herein, we report two new D-A-π-A-featured sensitizers termed HY63 and HY64, which employ benzothiadiazole (BT) or phenanthrene-fused-quinoxaline (PFQ), respectively, as the auxiliary electron-withdrawing acceptor moiety. Despite their very similar energy levels and absorption onsets, HY64-based DSSCs outperform their HY63 counterparts, achieving a power conversion efficiency (PCE) of 12.5 %. PFQ is superior to BT in reducing charge recombination resulting in the near-quantitative collection of photogenerated charge carriers.

Tailored Amphiphilic Molecular Mitigators for Stable Perovskite Solar Cells with 23.5% Efficiency.

Passivation of interfacial defects serves as an effective means to realize highly efficient and stable perovskite solar cells (PSCs). However, most molecular modulators currently used to mitigate such defects form poorly conductive aggregates at the perovskite interface with the charge collection layer, impeding the extraction of photogenerated charge carriers. Here, a judiciously engineered passivator, 4-tert-butyl-benzylammonium iodide (tBBAI), is introduced, whose bulky tert-butyl groups prevent the unwanted aggregation by steric repulsion. It is found that simple surface treatment with tBBAI significantly accelerates the charge extraction from the perovskite into the spiro-OMeTAD hole-transporter, while retarding the nonradiative charge carrier recombination. This boosts the power conversion efficiency (PCE) of the PSC from ≈20% to 23.5% reducing the hysteresis to barely detectable levels. Importantly, the tBBAI treatment raises the fill factor from 0.75 to the very high value of 0.82, which concurs with a decrease in the ideality factor from 1.72 to 1.34, confirming the suppression of radiation-less carrier recombination. The tert-butyl group also provides a hydrophobic umbrella protecting the perovskite film from attack by ambient moisture. As a result, the PSCs show excellent operational stability retaining over 95% of their initial PCE after 500 h full-sun illumination under maximum-power-point tracking under continuous simulated solar irradiation.

Extremity free fillet flap for reconstruction of massive oncologic resection-Surgical technique and outcomes.

BACKGROUND AND OBJECTIVES: The purpose of this study is to present our experience using free fillet flaps to reconstruct massive oncologic defects of the upper and lower extremity. METHODS: A retrospective chart review was performed to include patients who underwent oncologic resection followed by reconstruction using free fillet flaps from July 2001 to October 2018. Patient demographics, clinical and surgical characteristics, and postoperative complications were reviewed. RESULTS: In total, 12 patients were identified and included in this study. Mean age was 48.9 years old. Five patients had extended forequarter amputations and seven patients had external hemipelvectomies, all for locally advanced tumors. Mean tumor size was 15 ± SD 6.4 cm, and negative tumor margins were achieved in all the patients. Mean flap size was 1028 ± SD 869 cm2 . The mean follow-up was 13 months. There were no partial or total flap losses in the postoperative period. Two patients had flap-related postoperative complications, including flap bleeding and wound dehiscence. Median survival was 18 months. CONCLUSION: The free fillet flap is a safe, reliable, and valuable approach for reconstructing oncological defects. It offers the advantage of avoiding donor site morbidity, while providing extensive soft-tissue coverage as a one-step solution for massive oncologic defects.