Fluorescent antenna based on Förster resonance energy transfer (FRET) for optical wireless communications.

The use of fluorescent antennas in optical wireless communications (OWC) has been demonstrated previously, and it has been shown that it is an efficient method for enhancing receiver performance, providing both signal gain and a wide field of view (FoV). To achieve a high concentration gain at the receiver output, the selected fluorophores should have a high photoluminescence quantum yield (PLQY), limited overlap between their absorption and emission spectra, and emit light that can be efficiently detected. In addition, to support a high modulation bandwidth, the photoluminescence (PL) lifetime of the fluorophore needs to be short. In this paper, we propose a new fluorescent antenna architecture based on Förster resonance energy transfer (FRET). Our results show that, due to the photophysical interactions between the energy donor and energy acceptor, the use of FRET simultaneously increases PLQY and reduces PL lifetime. Additionally, employing FRET leads to an increased Stokes shift, ensuring that the emitted light has longer wavelengths, thus reducing self-absorption. This shift can also increase the efficiency with which the fluorescence is detected by a typical silicon (Si) photodetector. Consequently, our OWC results show that a new FRET-based antenna can achieve a significantly higher concentration gain and a wider transmission bandwidth than a conventional non-FRET antenna, leading to much higher data rates.

The ionization energy of α-sexithiophene and p-sexiphenyl in 2D and 3D thin films grown on silicon oxide surfaces.

The ionization energy (IE) of molecular thin films is sensitive to the molecular environments surrounding ionized molecules. In this study, we investigate the evolution of the IE on dimension-controlled 2D and 3D thin films of rod-like molecules, namely α-sexithiophene (α-6T) and p-sexiphenyl (p-6P), grown on SiO2 surfaces via photoelectron yield spectroscopy. In 2D thin films, the IE of α-6T and p-6P showed nearly constant values of 4.93 eV and 5.50 eV, respectively. In 3D thin films, however, with increasing coverage, the IE of the α-6T thin films gradually decreased to 4.84 eV at 15 ML (ML: monolayer) and the IE of the p-6P thin films gradually increased to 5.65 eV at 7 ML. These experimental findings underline the less significant impact of the domain size on the IE in 2D thin films and the significant impact of the neighboring layers on the IE in 3D thin films.

Study of using different colors of fluorescent fibers as optical antennas in white LED based-visible light communications.

A fluorescent fiber can be used as an optical antenna in visible light communication (VLC) for simultaneous optical filtering and light concentration and therefore to build a compact receiver. Since its light concentration principle is based on fluorescence, it can exceed the étendue limit and achieve both a high concentration gain and a wide field-of-view (FOV). In addition, because the photoluminescence (PL) lifetime of the fluorophore is typically only several nanoseconds, it can support high-speed data transmissions. When a fluorescent fiber antenna is used in a white light-emitting diode (LED)-based VLC system, the transmission performance highly depends on how the absorption and emission spectra of the fluorophore are associated with both the spectrum of the LED and the responsivity of the silicon photodetector. In this paper, we analyze the performance of several different commercially available fluorescent fibers. We show that, when the data rate is low or the transmission distance is long, since the light emitted from a red fluorescent fiber is associated with high silicon responsivities, it can result in high signal-to-noise ratios (SNRs) at the receiver output and therefore lead to low transmission error rates. In contrast, when the data rate is high or the transmission distance is relatively short, the bandwidth dominates the overall performance and consequently the green fluorescent fiber has better performance since it only absorbs the light emitted from the blue LED rather than the light emitted from the yellow phosphor.

Capillary-based fluorescent antenna for visible light communications.

The use of fluorescent optical antennas in visible light communications (VLC) systems can enhance their performance by selectively absorbing light from the transmitter and concentrating the resulting fluorescence, whilst preserving a wide field of view. In this paper, we introduce a new and flexible way of creating fluorescent optical antennas. This new antenna structure is a glass capillary which is filled with a mixture of epoxy and a fluorophore before the epoxy is cured. Using this structure, an antenna can be easily and efficiently coupled to a typical photodiode. Consequently, the leakage of photons from the antenna can be significantly reduced when compared to previous antennas created using microscope slides. Moreover, the process of creating the antenna is simple enough for the performance of antennas containing different fluorophores to be compared. In particular, this flexibility has been used to compare VLC systems that incorporate optical antennas containing three different organic fluorescent materials, Coumarin 504 (Cm504), Coumarin 6 (Cm6), and 4-(Dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM), when a white light-emitting diode (LED) is used as the transmitter. Results show that, since it only absorbs light emitted from the gallium nitride (GaN) LED, a fluorophore that hasn't previously been used in a VLC system, Cm504, can result in a significantly higher modulation bandwidth. In addition, the bit error rate (BER) performance at different orthogonal frequency-division multiplexing (OFDM) data rates of antennas containing different fluorophores is reported. These experiments show for the first time that the best choice of fluorophore depends on the illuminance at the receiver. In particular, when the illuminance is low, the overall performance of the system is dominated by the signal-to-noise ratio (SNR). Under these conditions, the fluorophore with the highest signal gain is the best choice. In contrast, when the illuminance is high, the achievable data rate is determined by the bandwidth of the system and therefore the fluorophore that results in the highest bandwidth is the best choice.

Low-intensity pulsed ultrasound is effective for progressive-stage lumbar spondylolysis with MRI high-signal change.

PURPOSE: This study aimed to investigate the treatment effects of low-intensity pulsed ultrasound (LIPUS) on progressive-stage spondylolysis. Spondylolysis is a stress fracture of the pars interarticularis. Based on the results of computed tomography, spondylolysis was classified into three categories: early, progressive, and terminal. Bone healing was prolonged or not obtained in progressive-stage spondylolysis. The progression of spondylolysis to nonunion has been associated with an increased incidence of spondylolisthesis. To prevent these clinical conditions, achieving bony healing of the spondylolysis site should be the goal of treatment. METHODS: 15 consecutive pediatric patients with progressive-stage spondylolysis (defects) with MRI high-signal change were analyzed. Nine patients were treated conservative treatment including avoidance of any sport activity and the use of a brace during treatment (conventional). Six patients were treated using LIPUS everyday during treatment in addition to conservative treatment. Approximately every 1.5 months, bone healing was evaluated via CT. Cases that retained defects after 4.5 months were defined as nonunion. RESULTS: Two patients dropped out during the study period. A total of 13 patients (mean 14.6 ± 2.5 years) from the database met with 19 interarticularis defects. The bone union rate in LIPUS group was significantly higher than that in conventional group (66.7 vs. 10.0%, p = 0.020). The treatment period to bone union was 3.8 months and 2.7 ± 0.3 months in conventional and LIPUS groups. CONCLUSIONS: This study revealed that LIPUS treatment might be effective for bone union in patients with progressive-stage spondylolysis with MRI high-signal change. LEVEL OF EVIDENCE: 4.

Postoperative hemorrhage after Le Fort I osteotomy hemostasis with angiographic embolization: report of two cases.

This study reported two cases of acute life-threatening hemorrhage after Le Fort I osteotomy. In both cases, computed tomography and angiography revealed damage to the descending palatine artery, which was successfully treated by angiographic embolization. Although massive hemorrhage after Le Fort I osteotomy is rare, acute hemorrhage from the postoperative area may occur. Angiographic embolization is useful in cases of such hemorrhage from the posterior nasal cavity where endoscopic hemostasis is not possible.

Donor-derived oral squamous cell carcinoma after allogeneic bone marrow transplantation.

In animal models, tissue stem cells were proposed to exhibit an unexpected level of plasticity, although issues on cell fusions have lead to some controversies. Only transplantation experiments using genetically distinct recipients and donors can unequivocally show these changes in cell fate. We have analyzed oral squamous cell carcinomas arising in 8 long-term survivors of allogeneic bone marrow transplantation, in whom chronic graft-versus-host disease greatly favors development of squamous cell carcinomas, possibly as a consequence of lichenoid mucosal inflammation. With the use of 2 independent methods, (1) combined immunostaining and fluorescent in situ hybridization (FISH) analysis for X and Y chromosomes sequences in sex-mismatched grafts and (2) comparison of microsatellite typing of laser-microdissected tumor, donor, and recipient cells, in all tumors, we showed that 4 of these 8 epithelial tumors actually arose from the engrafted allogeneic bone marrow. Thus, donor-derived bone marrow cells, whether hematopoietic or mesenchymal, recruited to sites of chronic mucosal inflammation yielded epithelial tumors. Our observations therefore show that marrow cells in humans have a major role in epithelial cancer formation after allogeneic transplantation.

Evolution of the Ionization Energy in Two- and Three-Dimensional Thin Films of Pentacene Grown on Silicon Oxide Surfaces.

The ionization energy (IE) of pentacene in two- and three-dimensional (2D and 3D) thin films and its evolution with coverage were studied via photoelectron yield spectroscopy in ambient conditions. In the 2D thin films, the IE of pentacene was found to be nearly constant at 4.91 eV, irrespective of its island size, for an average island size exceeding 1.6 × 104 nm2. In the 3D thin films, however, a reduction in IE by 0.04 eV was clearly observed upon stacking an additional molecular layer on top of the monolayer film, and the IE decreased to 4.73 eV at 20 monolayers. These experimental findings demonstrate the IE evolution in the buried layers of the 3D thin films and the significant impact of the neighboring molecular layers on the IE in layered systems with molecular aggregation.

Photoexpansion of Biobased Polyesters: Mechanism Analysis by Time-Resolved Measurements of an Amorphous Polycinnamate Hard Film.

Cinnamate-based polyesters were synthesized, including poly(4-hydroxycinnamic acid), poly(4-hydroxy-3-methoxycinnamic acid), poly(3-hydroxycinnamic acid) (P3HCA), and hyperbranched poly(3,4-dihydroxycinnamic acid) (PdHCA). These materials were further processed into hard and dry membranes by casting and underwent photoreactions by ultraviolet (UV) light. The photodeformation behavior of the linear and hyperbranched polyester containing membranes with cinnamate derivatives in the main chain was observed macroscopically and microscopically. The PdHCA and P3HCA membranes were amorphous and exhibited photodeformations. The PdHCA surface visibly contracts, which is a typically observed phenomenon in photoresponsive polymers; however, the P3HCA surface showed a unique photoexpansion behavior. Time-resolution infrared spectroscopy of the P3HCA film revealed trans-to-cis isomerism in the polymer main chains that bent convexly as a result of photoexpansion of the UV-irradiated regions. Furthermore, photomasking created a micropattern on the P3HCA film, which supported the photoexpansion mechanism of the P3HCA film.

Controlling the concentration gradient in sequentially deposited bilayer organic solar cells via rubbing and annealing.

We elucidate the formation mechanism of adequate vertical concentration gradients in sequentially deposited poly(3-hexylthiophene-2,5-diyl) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) bilayer solar cells. Using advanced analytical techniques, we clarify the origins of the enhanced photovoltaic performances of as-deposited and annealed bilayer P3HT/PCBM organic solar cells upon P3HT layer rubbing prior to PCBM deposition. Energy-dispersive X-ray spectroscopy reveals the individual effects of rubbing and annealing on the formation of adequate concentration gradients in the photoactive layers. Repetitive rubbing of P3HT strongly affects the active layer nanomorphology, forming an intermixed layer in the as-deposited devices which is retained after the annealing process. Infrared p-polarized multiple-angle incidence resolution spectrometry measurements indicate that rubbing induces a minor reorganization of the P3HT molecules in the polymer-only thin films towards face-on orientation. However, the deposition of the upper PCBM layer reverts the P3HT molecules back to their original orientation. These findings suggest that the formation of an adequate concentration gradient upon rubbing corresponds to the dominant contribution to the improved photovoltaic characteristics of rubbed bilayer organic solar cells. Using the reference low bandgap copolymer PCDTBT, we demonstrate that rubbing can be successfully applied to increase the photovoltaic performances of PCDTBT/PCBM organic solar cells. We also demonstrate that rubbing can be an efficient and versatile strategy to improve the power conversion efficiency of non-fullerene solar cells by using the reference materials in the field, PBDB-T and ITIC.

Effect of Perioperative Mental Status on Health-related Quality of Life in Patients With Adult Spinal Deformities.

STUDY DESIGN: A retrospective study. OBJECTIVE: We aimed to evaluate the impact of mental status on the clinical outcomes of patients with adult spinal deformity (ASD). SUMMARY OF BACKGROUND DATA: Limited information is currently available on how preoperative mental status affects postoperative health-related quality of life (HRQOL) in patients with ASD. METHODS: We enrolled 165 patients with ASD who underwent corrective surgery at a single university hospital between March 2010 and September 2015. We compared Scoliosis Research Society-22r (SRS-22r) and Oswestry Disability Index (ODI) scores using various x-ray parameters at these time points: preoperative period and postoperative 2 years. Additionally, to determine the associations between perioperative complications and mental health disorders, we examined these x-ray parameters: lumbar lordosis, thoracic kyphosis, sacral slope, pelvic incidence, pelvic tilt, sagittal vertical axis (SVA), and T1 pelvic angle (TPA). RESULTS: We found correlations between the preoperative SRS-22r total score and preoperative ODI (r = -0.692, P < 0.01) and postoperative ODI (r = -0.443, P < 0.01). Preoperative SRS-22r mental domain correlated with preoperative ODI (r = -0.561, P ≤ 0.01) and postoperative ODI (r = -0.315, P ≤ 0.01). Perioperative (preoperative and postoperative) SRS-22r mental domain did not correlate with the postoperative x-ray parameters except for SVA and TPA. Postoperative mental health correlated with early infection (P < 0.05), hematoma (P < 0.05), deep vein thrombosis (P < 0.05), and delirium (P < 0.05). Regression analysis revealed that preoperative SRS-22r mental health score correlated with preoperative ODI (P < 0.001) and postoperative ODI (P < 0.001). The regression coefficient number between preoperative SRS-22r mental health score and perioperative (preoperative and postoperative) ODI improved from -17.3 to -10.2 from preoperative to postoperative periods. CONCLUSION: Diminished preoperative mental health worsened postoperative HRQOL. Perioperative complications influence postoperative mental status and HRQOL; hence, screening preoperative mental health is important. LEVEL OF EVIDENCE: 3.

Long-lived exciplex formation and delayed exciton emission in bulk heterojunction blends of silole derivative and polyfluorene copolymer: the role of morphology on exciplex formation and charge separation.

Long-lived exciplex emission is observed in blend films of poly[9,9-dioctylfluorene-co-N-(4-methoxy-phenyl)diphenylamine] (TFMO) and the soluble silole derivative 2,5-bis-(2,2-bipyridin-6-yl)-1,1-dimethyl-3,4-diphenylsilacyclopentadiene (PyPySPyPy). The exciplex is characterized by a long-lived (approximately 40-90 ns) component in both the photoluminescence and electroluminescence spectra, which is red-shifted relative to the emission of the pristine materials. In addition to exciplex emission, delayed fluorescence from the TFMO singlet state is observed and is attributed to exciton regeneration through the interfacial exciplex state. Comparing blend films made using chlorobenzene and p-xylene solvents, we find that exciplex lifetime and exciton regeneration in the blend film are sensitive to the choice of solvent and the resulting morphology of the blend film. The exciplex emissive lifetime can be correlated to changes in photoluminescence quenching and efficiency of light-emitting diodes.

Endothelial cell chimerism associated with graft rejection after human lung transplantation.

Endotheliitis is a major sign of graft rejection. Recipient-derived endothelial cells found in two series of liver and kidney transplants were related to graft rejection. Here, we assessed the presence and the number of chimeric endothelial cells in lung transplants, and their relation with graft rejection. In six males grafted with female lungs out of 193 lung transplantations, endothelial chimerism was studied by combined XY-fluorescent in situ hybridization with CD31 and CD45 immunostainings and blood group antigens. On samples graded according to the revised working formulation for lung allograft rejection, we found chimeric macrophages (73.1 to 87.2%) in all cases and chimeric endothelial cells (1.3 to 2.1%) in four patients. Another method using ABO blood group also showed endothelial cells positive for recipient-type blood group antigens in three patients. By both methods, presence of chimeric endothelial cells was related to pathological signs of acute rejection (P<0.05).

Sonication-assisted supramolecular nanorods of meso-diaryl-substituted porphyrins.

Supramolecular nanorods of 5,15-diaryl-substituted porphyrins prepared by sonication method exhibit a broad absorption property, which is confirmed by photocurrent generation measurement in a photoelectrochemical cell.

Mirror slides for high-sensitivity cell and tissue fluorescence imaging.

Fluorescence microscopy has become the method of choice in the majority of life-science applications. We describe development and use of mirror slides to significantly enhance the fluorescence signal using standard air microscope objectives. This technique offers sufficient gain to achieve high-sensitivity imaging, together with wide field of observation and large depth of focus, two major breakthroughs for routine analysis and high-throughput screening applications on cells and tissue samples.

A phase I study of concurrent chemoradiotherapy with S-1 for T2N0 glottic carcinoma.

OBJECTIVE: Chemoradiation based on S-1, a novel oral antitumor agent of fluorinated pyrimidines, is the treatment for T2N0 glottic carcinoma; however, the optimal scheduling and dosing have still not been established. A phase I study was conducted to determine the maximum tolerated dose of S-1 with radiotherapy of 2 Gy/day for 5 days a week to a total dose of 60 Gy. Endpoints of this study were to examine the toxicity profile of this regimen and to determine the recommended dose of S-1. METHODS: Concomitant administration with the above-mentioned radiotherapy of S-1 once a day for 2 weeks, beginning on the day therapy was started, followed by 2 weeks off the drug and 2 weeks on the drug with the dose escalating from S-1 60 mg/body (level 1) to 80 mg/body/day (level 2), and then to 100 mg/body/day (level 3). RESULTS: Twenty-one patients were valid for safety. Eighteen patients were enrolled in the dose-escalation phase. In all patients, S-1 was administered. The maximum tolerated dose was determined to be 100 mg/body/day and the dose-limiting toxicity was indicated by the onset of grade 3 chemoradiation dermatitis. Therefore, the determined recommended dose of S-1 was 80 mg/body/day. Objective response according to Response Evaluation Criteria in Solid Tumors were observed in 20 of 21 patients who had measurable disease (95.2%). CONCLUSION: Concurrent S-1 and radiotherapy was feasible and well tolerated, and was suggested to produce a worthwhile response in T2N0 glottic carcinoma. These results warrant further investigation, and a phase II has already been started.

T cell receptor BV gene repertoire of lymphocytes in bronchoalveolar lavage fluid of polymyositis/dermatomyositis patients with interstitial pneumonitis.

We analyzed the T cell receptor (TCR) repertoire of bronchoalveolar lavage fluid (BALF) lymphocytes from polymyositis (PM) and dermatomyositis (DM) patients with interstitial pneumonitis (IP) to elucidate the pathogenic mechanisms of IP in these disorders. Samples from 2 PM patients, 1 DM patient and 3 healthy controls were used. RNA was isolated from BALF, cDNAs were synthesized, and family PCR and Southern blot analysis were performed by primers specific for TCR BV1-25 and TCR BC to determine TCR repertoire. We examined single-strand conformation polymorphism (SSCP) to evaluate T cell clonality. The CDR3 region of TCR BV genes in BALF T cells were determined by DNA sequencer. Our examination showed that TCR repertoire of T cells in BALF was heterogeneous both in patients with PM/DM and control subjects. SSCP analysis demonstrated an increased number of accumulated T cell clones in BALF of three PM/DM patients, but not in the healthy subjects and the junctional sequence analysis showed the presence of conserved amino acid motifs (RGS, GLA, LQG, SGG, DRG, GTS, TSGR, GGS, GQA, GAG, GTG) in the TCR-CDR3 region of BALF lymphocytes from PM/DM patients, which were not detected in the control. Our findings suggest that T cells in BALF may recognize the restricted antigen and accumulate via antigen-driven stimulation, suggesting that T cells may play a crucial role in the development of IP in patients with PM/DM.

Indications for surgery in intestinal Behçet's disease.

BACKGROUND/AIMS: As advances in steroids and immunosuppressants made medical treatment first-line therapy for Behçet's disease, the criteria for elective surgery became unclear. The aim of this paper is to establish surgical criteria for Behçet's. METHODOLOGY: We reviewed the medical records of 8 consecutive Japanese patients who were diagnosed with intestinal Behçet's at Tsukuba University Hospital between 1976 and 2001. Records were examined for medical treatment including dose of steroids, and surgical treatment including length of resected intestine, incidence of recurrence, and the form and site of recurrence. RESULTS: Elective surgery was performed in cases where the preoperative steroid administration could not be reduced to under 40mg/day, once steroids exceeded 40mg/day to control symptoms and inflammation. Cases with emergency operations (perforated cases), the preoperative doses of steroids were not so high (0, 0, 10, 20mg/day). In all cases, the post-surgical steroid dose was reduced under 20mg/day. Three cases showed recurrence after surgery within 2 years. These cases also had an increase in steroid dosage at the time of recurrence, but have been controlled medically so far. CONCLUSIONS: Surgery should be strongly considered when the steroid dose exceeds 40mg/day.

[Adjuvant chemotherapy with TS-1 for head and neck cancer--side effect of two-week application followed by one-week rest regimen].

Multimodality therapy incorporated with radiotherapy, surgery and chemotherapy are used in the treatment of head and neck cancer in order to improve the local control and survival rate. TS-1, a newly developed oral antitumor agent which could achieve the same therapeutic concentration as that of 5-FU under continuous and intravenous treatment, has been used as adjuvant therapy for carcinomas in recent years. We presented our experience applying a new regimen of TS-1 and its side effects. TS-1 has been applied for head and neck carcinomas since 2001. The oral application of TS-1 has been used in 32 cases of head and neck cancer in our department since 2003, and the agent has been applied in 22 of 32 cases as adjuvant therapy. The primary sites of malignancy included hypopharyngx (7 cases), larynx (6 cases), maxillary sinus (2 cases), oropharynx (2 cases), oral cavity (4 cases), submandibular gland (1 case) and one case in which the primary site was unknown. A regimen of four-week application followed by two-week rest had been used in 6 cases in the first part of this trial. However, a high frequency of blood toxicity was found from the third week, requiring alteration of the protocol. Thus, a new regimen of two-week application followed by one week rest was thereafter used in the other 16 cases. Blood toxicity was found in 66.7% of those cases receiving a four-week application followed by two-week rest regimen. In the 16 cases receiving the two-week application followed by one-week rest regimen, only one case showed grade 2 leucopenia while continuous application for more than eight weeks was possible in 9 cases. Mild macrocytic anemia was found in some of these cases, however none of which required any necessary interruption of the treatment. Side effects other than blood toxicity, such as edema or pigmentation of lower limbs, erythema of skin and diarrhea, were found in the other cases, requiring suspension of the treatment. But the subsequent application was possible after a break or decreasing the dosage. We concluded that the new regimen of two-week application followed by one-week rest is less likely to be interrupted by the side effects and is safer to be used outpatiently, compared with the four-week application followed by two-week rest.