Singlet Fission in a New Series of Systematically Designed Through-space Coupled Tetracene Oligomers.

Singlet fission (SF) holds great promise for current photovoltaic technologies, where tetracenes, with their relatively high triplet energies, play a major role for application in silicon-based solar cells. However, the SF efficiencies in tetracene dimers are low due to the unfavorable energetics of their singlet and triplet energy levels. In the solid state, tetracene exhibits high yields of triplet formation through SF, raising great interest about the underlying mechanisms. To address this discrepancy, we designed and prepared a novel molecular system based on a hexaphenylbenzene core decorated with 2 to 6 tetracene chromophores. The spatial arrangement of tetracene units, induced by steric hindrance in the central part, dictates through-space coupling, making it a relevant model for solid-state chromophore organization. We then revealed a remarkable increase in SF quantum yield with the number of tetracenes, reaching quantitative (196 %) triplet pair formation in hexamer. We observed a short-lived correlated triplet pair and limited magnetic effects, indicating ineffective triplet dissociation in these through-space coupled systems. These findings emphasize the crucial role of the number of chromophores involved and the interchromophore arrangement for the SF efficiency. The insights gained from this study will aid designing more efficient and technology-compatible SF systems for applications in photovoltaics.

Effects of Deuterium Isotopes on Pt(II) Complexes and Their Impact on Organic NIR Emitters.

Insight into effect of deuterium isotopes on organic near-IR (NIR) emitters was explored by the use of self-assembled Pt(II) complexes H-3-f and HPh-3-f, and their deuterated analogues D-3-f and DPh-3-f, respectively (Scheme 2). In vacuum deposited thin film, albeit having nearly identical emission spectral feature maximized at ~810 nm, H-3-f and D-3-f exhibit remarkable difference in photoluminescence quantum yield (PLQY) of 29 % and 50 %, respectively. Distinction in PLQY is also observed for HPh-3-f (800 nm, 50 %) and DPh-3-f (798 nm, 67 %). We then elucidated the theoretical differences in the impact on near-infrared (NIR) luminescence between Pt(II) complexes and organic small molecules upon deuteration. The results establish a general guideline for the deuteration on NIR emission efficiency. From a perspective of practical application, NIR OLEDs based on D-3-f and DPh-3-f emitters attain EQEmax of 15.5 % (radiance 31,287 mW Sr-1 m-2 ) and 16.6 % (radiance of 32,279 mW Sr-1 m-2 ) at 764 nm and 796 nm, respectively, both of which set new records for NIR OLEDs of >750 nm.

Hydrogen-Bonded Thiol Undergoes Unconventional Excited-State Intramolecular Proton-Transfer Reactions.

The chapter on the thiol-related hydrogen bond (H-bond) and its excited-state intramolecular proton-transfer (ESIPT) reaction was recently opened where compound 4'-diethylamino-3-mercaptoflavone (3NTF) undergoes ESIPT in both cyclohexane solution and solid, giving a 710 nm tautomer emission with an anomalously large Stokes shift of 12,230 cm-1. Considering the thiol H-bond to be unconventional compared to the conventional Pauling-type -OH or -NH H-bond, it is thus essential and timely to probe its fundamental difference between their ESIPT. However, thiol-associated ESIPT tends to be nonemissive due to the dominant nπ* character of the tautomeric lowest excited state. Herein, based on the 3-mercaptoflavone scaffold and π-elongation concept, a new series of 4'-substituted-7-diethylamino-3-mercaptoflavones, NTFs, was designed and synthesized with varied H-bond strength and 690-720 nm tautomeric emission upon ultraviolet (UV) excitation in cyclohexane. The order of their H-bonding strength was experimentally determined to be N-NTF < O-NTF < H-NTF < F-NTF, while the rate of -SH ESIPT measured by fluorescence upconversion was F-NTF (398 fs)-1 < H-NTF (232 fs)-1 < O-NTF (123 fs)-1 < N-NTF (101 fs)-1 in toluene. Unexpectedly, the strongest H-bonded F-NTF gives the slowest ESIPT, which does not conform to the traditional ESIPT model. The results are rationalized by the trend of carbonyl oxygen basicity rather than -SH acidity. Namely, the thiol acidity relevant to the H-bond strength plays a minor role in the driving force of ESIPT. Instead, the proton-accepting strength governs ESIPT. That is to say, the noncanonical thiol H-bonding system undergoes an unconventional type of ESIPT.

Safety and efficacy of hyaluronic acid injectable filler in the treatment of nasolabial fold wrinkle: a randomized, double-blind, self-controlled clinical trial.

INTRODUCTION: The injectable skin fillers available for soft tissue augmentation are constantly growing, providing esthetic surgeons with more options in the treatment of scars, lines, and wrinkles. Hyaluronic acid (HA)-derived injectable fillers are ideal to reduce the appearance of nasolabial folding. This study investigated the efficacy and safety of the commercially available HA filler from Maxigen Biotech Inc. (MBI-FD) in the treatment of nasolabial folds (NLFs). METHODS: We analyzed 1,4-butanediol diglycidyl ether (BDDE) residues and injection force test and observed the protein content in MBI-FD, and then was cultured in fibroblast L929 cells and examined for cytotoxicity. Finally, 95 healthy participants underwent dermal filler injection therapy to evaluate the efficacy and safety for 24 and 52 weeks, respectively. RESULTS: BDDE residues in MBI-FD was <0.125 µg/mL. MBI-FD was fitted using 27- and 30-G injection needles with an average pushing force of 14.30 ± 2.07 and 36.43 ± 3.11 N, respectively. Sodium hyaluronate protein in MBI-FD was 7.19 µg/g. The cell viabilities of 1× and 0.5× MBI-FD were 83.25% ± 3.58% and 82.23% ± 1.85%, respectively, indicating MBI-FD had no cytotoxicity, and decreased NLF wrinkles with no serious adverse events. CONCLUSION: MBI-FD is an effective filler for tissue augmentation of the NLFs and may be a suitable candidate as an injectable dermal filler for tissue augmentation in humans in the future.

Timoshenko & Lekhnitskii's puzzle ‒ Rule of swapping for the torsional rigidity of a rectangular bar.

Timoshenko presented the torsional rigidity of an isotropic rectangular bar, and Lekhnitskii presented that of an orthotropic rectangular bar. The solutions of Timoshenko and Lekhnitskii (T&L) are functions of the bar's length, width, thickness and shear modulus or moduli. However, the functions of T&L solutions become different from their original ones when the width and thickness are swapped. Swapping the width and thickness definitions does not alter the bar's physical properties, named the "rule of swapping" by the authors. In the last century, no research has shown the T&L solutions to satisfy the rule of swapping, an observation hereinafter referred to as the "Timoshenko & Lekhnitskii Puzzle". Roughly 90 years later, Tsai et al. re-solved T&L cases using the TSAI technique. The derived solutions are nearly if not completely identical to T&L's numerically and satisfy the rule of swapping automatically. The rule of swapping is a novel issue and has never been mentioned before. Based on the Weierstrass factorization theorem, this study mathematically proves that they are identical for isotropic and orthotropic bars and satisfy the rule of swapping. The result of a torsional pendulum test is analyzed to support the rule.

Rational Design of Asymmetric Polymethines to Attain NIR(II) Bioimaging at >1100 nm.

Organic molecules having emission in the NIR(II) region are emergent and receiving enormous attention. Unfortunately, attaining accountable organic emission intensity around the NIR(II) region is hampered by the dominant internal conversion operated by the energy gap law, where the emission energy gap and the associated internal reorganization energy λint play key roles. Up to the current stage, the majority of the reported organic NIR(II) emitters belong to those polymethines terminated by two symmetric chromophores. Such a design has proved to have a small λint that greatly suppresses the internal conversion. However, the imposition of symmetric chromophores is stringent, limiting further development of organic NIR(II) dyes in diversity and versatility. Here, we propose a new concept where as far as the emissive state of the any asymmetric polymethines contains more or less equally transition density between two terminated chromophores, λint can be as small as that of the symmetric polymethines. To prove the concept, we synthesize a series of new polymethines terminated by xanthen-9-yl-benzoic acid and 2,4-diphenylthiopyrylium derivatives, yielding AJBF1112 and AEBF1119 that reveal emission peak wavelength at 1112 and 1119 nm, respectively. The quantum yield is higher than all synthesized symmetric polymethines of 2,4-diphenylthiopyrylium derivatives (SC1162, 1182, 1185, and 1230) in this study. λint were calculated to be as small as 6.2 and 7.3 kcal/mol for AJBF1112 and AEBF1119, respectively, proving the concept. AEBF1119 was further prepared as a polymer dot to demonstrate its in vitro specific cellular imaging and in vivo tumor/bone targeting in the NIR(II) region.

Comprehensive Thione-Derived Perylene Diimides and Their Bio-Conjugation for Simultaneous Imaging, Tracking, and Targeted Photodynamic Therapy.

In this study, the chromophore 3,4,9,10-perylenetetracarboxylic diimide (PDI) is anchored with phenyl substituents at the imide N site, followed by thionation, yielding a series of thione products 1S-PDI-D, 2S-cis-PDI-D, 2S-trans-PDI-D, 3S-PDI-D, and 4S-PDI-D, respectively, with n = 1, 2, 3, and 4 thione. The photophysical properties are dependent on the number of anchored thiones, where the observed prominent lower-lying absorption is assigned to the S0 → S2(ππ*) transition and is red-shifted upon increasing the number of thiones; the lowest-lying excited state is ascribed to a transition-forbidden S1(nπ*) configuration. All nS-PDIs are non-emissive in solution but reveal an excellent two-photon absorption cross-section of >800 GM. Supported by the femtosecond transient absorption study, the S1(nπ*) → T1(ππ*) intersystem crossing (ISC) rate is > 1012 s-1, resulting in ∼100% triplet population. The lowest-lying T1(ππ*) energy is calculated to be in the order of 1S-PDI-D > 2S-cis-PDI-D ∼ 2S-trans-PDI-D > 3S-PDI-D > 4S-PDI-D, where the T1 energy of 1S-PDI-D (1.10 eV) is higher than that (0.97 eV) of the 1O2 1Δg state. 1S-PDI-D is further modified by either conjugation with peptide FC131 on the two terminal sides, forming 1S-FC131, or linkage with peptide FC131 and cyanine5 dye on each terminal, yielding Cy5-1S-FC131. In vitro experiments show power of 1S-FC131 and Cy5-1S-FC131 in recognizing A549 cells out of other three lung normal cells and effective photodynamic therapy. In vivo, both molecular composites demonstrate outstanding antitumor ability in A549 xenografted tumor mice, where Cy5-1S-FC131 shows superiority of simultaneous fluorescence tracking and targeted photodynamic therapy.

Comment on "Metal-Free Triplet Phosphors with High Emission Efficiency and High Tunability".

A series of ß-hydroxy-vinylimine boron compounds 1-7 have been reported to exhibit unique dual emission, consisting of fluorescence and room temperature phosphorescence (RTP) in solution. This finding triggered intensive research of RTP in ß-hydroxy-vinylimine boron derivatives. Herein, we show clear evidence that the associated dual emission, especially RTP, is caused by the experimental artifact, where bright emission intensity saturates the detection dynamic range of the fluorimeter.

Clinical applications of the pedicled anterolateral thigh flap in reconstruction.

BACKGROUND: Reconstruction of extensive defects of the lower abdomen, penoscrotum, trochanter, groin and knee without using complex microsurgery is a reconstructive challenge. Pedicled anterolateral thigh (ALT) flaps offer many advantages over other regional flaps for this purpose, such as the large skin area and soft-tissue availability, a remarkable pedicle length, and possessing multiple components and reliability. We present our experience of using pedicled ALT flaps for repairing various defects. METHODS: From September 2006 to December 2013, 42 pedicled ALT flaps were used in 41 patients for defects of the lower abdomen (three patients), trochanter (26 patients), penoscrotum (10 patients), groin (one patient) and knee (one patient). Twenty-eight were men and 13 were women, and their mean age was 70.5 years (range, 22-103 years). The characteristics of the patients' age, sex, cause, flap size, flap component, follow-up and donor sites were recorded. RESULTS: The flap size ranged from 8 × 5 cm (40 cm2 ) to 11 × 18 cm (198 cm2 ). The length of the pedicle ranged from 9 to 16 cm, which was enough to reach the defect without tension. No surgery-related mortality occurred. In 34 flaps, donor sites were closed primarily and eight underwent split-skin grafting. Satisfactory coverage was achieved in all patients. CONCLUSION: Our experience has shown the wide arc of rotation, large skin replacement potential, multiple components and reliability of pedicled ALT flaps. They are technically simple to apply as myocutaneous/fasciocutaneous flaps with minimal donor site morbidity.

A huge acquired smooth muscle hamartoma of the scrotum.

Smooth muscle hamartoma (SMH) is a rare benign proliferation of the smooth muscle. It usually arises on the back and proximal extremities, although it develops on the scrotum in rare cases. Here, we present a 58-year-old man who presented with a huge mass of the scrotum, which was first noticed 10 years previously. The scrotum was considerably enlarged and affected the patient's gait. We performed wide excision of the mass, measuring 32.5 × 20 × 14 cm in size and weighing 3600 g. The residual uninvolved scrotal skin flap was well vascularised and elastic, and the testis could be properly contained within the scrotum after primary closure of the defect. A split-thickness skin graft was used to resurface the skin defect of the penile shaft. The patient was satisfied with the shape and texture of the scrotum after reconstruction. The postoperative course was uneventful. We assess our experience in the successful reconstruction of a large penoscrotal skin defect using a scrotal skin flap and split-thickness skin graft. This procedure is safe and uncomplicated with the patient regaining a normal genital contour and satisfactory functional recovery.

Comparison of hatchet-shaped tensor fascia lata flap and pedicle anterior lateral thigh flap for treatment of trochanteric sores: a retrospective analysis of 48 patients.

PURPOSE: Surgical reconstruction of trochanteric sores remains a formidable task for plastic surgeons. Diverse types of flaps have been proposed for use in this situation, each with particular advantages and limitations. This study aimed to compare the surgical outcomes between the hatchet-shaped tensor fascia lata (TFL) flap and the pedicle anterior lateral thigh (ALT) flap in treatment of trochanteric sores. METHODS: Forty-eight patients with trochanteric sores were operated on under spinal or general anesthesia using TFL or ALT flaps between August 2007 and November 2010. In the TFL group, 26 hatchet-shaped TFL musculocutaneous flaps were performed on 24 patients. In the ALT group, 25 pedicle ALT musculocutaneous flaps were performed on 24 patients. Surgical outcomes were retrospectively analyzed. RESULTS: No significant difference was detected between the TFL and ALT groups in terms of age, preoperative disease period, obesity (body mass index), American Society of Anesthesiologists score, comorbidity, the defect size, follow-up time, and complication rate. The recurrence rate and the flap size were significantly higher in the TFL group than in the ALT group (P = 0.022; P < 0.001). The operation time was longer in the ALT group (P < 0.001). CONCLUSIONS: The pedicle ALT flap is a more effective treatment than the TFL flap for the surgical management of trochanteric sores. The hatchet-shaped TFL flap should be reserved for the reconstruction of recurrent trochanteric sores or for use in the critically ill patient who cannot tolerate longer anesthesia and operation time.

The lower trapezius musculocutaneous flap for head and neck reconstruction: two decades of clinical experience.

BACKGROUND: Microsurgical free flap has gained the popularity over pedicle flap nowadays in the reconstruction of head and neck. However, pedicled flaps remain a promising alternative and have a remarkable position in selected patients. This review study aimed to determine the reliability and versatility of the lower trapezius musculocutaneous flap for reconstructing complex defects in the head and neck. METHODS: Between 1993 and 2012, 22 male and 10 female patients underwent a total of 32 lower trapezius flap reconstructions for complex defects that included neoplasm extirpation (n = 21), radionecrosis (n = 6), dehisced laminectomy (n = 2), pressure sore (n = 2), and necrotizing fasciitis (n = 1). The most common site of defect was the perioral region, followed by the neck, posterior skull, back, temporal region, shoulder, and the upper arm. Flap design was based on the defect size and location, as well as the ability to close the donor site primarily and to preserve muscle function. Outcome has been evaluated by the hospital course, postoperative morbidity, mortality, resultant cosmetics, and function at donor and recipient sites. RESULTS: Stable wound coverage with total flap survival was achieved in 30 (93.75%) patients, 2 patients had partial flap necrosis which required flap reinsertion and skin graft coverage. All donor sites were closed primarily. Seroma developed in 2 (6.25%) patients, which were solved by needle aspiration. All muscle function was preserved. Eight patients died of their primary disease. CONCLUSIONS: For selected patients who have advanced stage cancer, surgical sequelae after free flap surgery, unable to tolerate microsurgery, or special defect location, pedicled lower trapezius musculocutaneous flap provides efficient and effective reconstruction for complex defects especially in the head and neck.

Treatment of nonhealing diabetic lower extremity ulcers with skin graft and autologous platelet gel: a case series.

Lower extremity ulcers in diabetic patients are difficult to treat. Recently, the use of human blood platelet-derived components in this indication has been raising interest. In this study, we have evaluated the safety and efficacy of the combination of autologous platelet gel (PG) and skin graft for treating large size recalcitrant ulcers. Eight consecutive diabetic patients aged 25 to 82 with nine nonhealing lower extremity ulcers (median size of 50 cm(2); range 15-150 cm(2)) were treated. Skin ulcer was debrided, and the wound was sprayed after 7 to 10 days with autologous platelet-rich plasma and thrombin. Thin split-thickness skin graft with multiple slits was then applied on the wound bed and fixed with staples or cat-gut sutures. There were no adverse reactions observed during the study. Eight out of 9 skin grafts took well. The interval between skin graft and complete wound healing ranged from 2 to 3 weeks in the 8 successful cases. No ulcer recurrence was noted in those patients during the follow-up period of 2 to 19 months. In this study, the combination of autologous platelet gel and skin grafting has proven beneficial to heal large-size recalcitrant ulcers.

Three abdominal defects, three pedicled flaps.

The reconstruction of complex defects in the abdominal wall after wound infection or trauma can be challenging. In this article, a superficial inferior epigastric artery flap, a tensor fascia lata flap, and an anterolateral thigh flap used for 3 different abdominal wall reconstructions are described. The authors conclude that different specific abdominal wall defects can be successfully reconstructed using different pedicled flaps in simple and effective single-stage reconstructions.