Non-Fused π-Extension of Endcaps of Small Molecular Acceptors Enabling High-Performance Organic Solar Cells.

The modular structure of small molecular acceptors (SMAs) allows for versatile modifications of the materials and boosts the photovoltaic efficiencies of organic solar cells (OSCs) in recent years. As a critical component, the endcaps of SMAs have been intensively investigated and modified to control the molecular aggregation and photo-electronic conversion. However, most of the studies focus on halogenation or π-fusion extension of the endcap moieties, but overlook the non-fused π-extension approach, which could be a promising strategy to balance the self-aggregation and compatibility behaviors. Herein, we reported two new acceptors namely BTP-Th and BTP-FTh based on non-fused π-extension of the endcap by chlorinated-thiophene, of which the latter molecule has better co-planarity and crystallinity because of the intramolecular noncovalent interactions. Paired with donor PBDB-T, the optimal device of BTP-FTh reveals a greater efficiency of 14.81 % that that of BTP-Th (13.91 %). Nevertheless, the BTP-Th based device realizes a lower energy loss, enabling BTP-Th as a good candidate to serve as guest acceptor. As a result, the ternary solar cells of PM6 : BTP-eC9 : BTP-Th output a champion efficiency up to 18.71 % with enhanced open-circuit voltage. This study highlights the significance of rational decoration of endcaps for the design of high-performance SMAs and photovoltaic cells.

Effects of Halogenation on Cyclopentadithiophenevinylene-Based Acceptors with Excellent Responses in Binary Organic Solar Cells.

In recent years, non-fused non-fullerene acceptors (NFAs) have attracted increasing consideration due to several advantages, which include simple preparation, superior yield, and low cost. In the work reported here, we designed and synthesized three new NFAs with the same cyclopentadithiophenevinylene (CPDTV) trimer as the electron-donating unit and different terminal units (IC for FG10, IC-4F for FG8, and IC-4Cl for FG6). Both halogenated NFAs, i.e., FG6 and FG8, show red-shifted absorption spectra and higher electron mobilities (more pronounced for FG6) in comparison with FG10. Moreover, the dielectric constants of these materials also increased upon halogenation of the IC terminal units, thus leading to a reduction in the exciton binding energy, which is favorable for dissociation of excitons and subsequent charge transfer despite the driving force (highest occupied molecular orbital and lowest unoccupied molecular orbital offsets) being very small. The organic solar cells (OSCs) constructed using these acceptors and PBDB-T, as the donor, showed PCE values of 15.08, 12.56, and 9.04% for FG6, FG8, and FG10, respectively. The energy loss for the FG6-based device was the lowest (0.45 eV) of all the devices, and this may be attributed to it having the highest dielectric constant, which leads to a reduction in the binding energy of exciton and a small driving force for hole transfer from FG6 to PBDB-T. The results indicate that the NFA containing the CPDTV oligomer core and halogenated terminal units can efficiently spread the absorption spectrum to the NIR zone. Non-fused NFAs have a bright future in the quest to obtain efficient OSCs with low cost for marketable purposes.

Usefulness of the Round Endcap Expandable Cage Placed on the Vertebral Ring Apophysis in Anterior Spinal Reconstruction.

Rectangular endcap expandable cages are common in anterior thoracolumbar spine restoration. However, the cage is often too large to place in small, elderly women. In this study, we evaluated a method to place a round endcap expandable cage on the vertebral ring apophysis in elderly women. From April 2017 to August 2020, five women (mean age 75.8 years) underwent anterior-posterior spinal fusion with a round endcap expandable cage on the vertebral ring apophysis at the thoracolumbar junction. The local kyphotic angle, coronal Cobb angle, and intervertebral height were evaluated pre-and postoperatively. Cage subsidence and bone union were evaluated. The mean local kyphotic angle, coronal Cobb angle, and intervertebral height before surgery were 35.2°, 10.0°, and 65.3 mm, respectively. Immediately postoperatively, 1 week and 3 weeks after surgery, the kyphotic angle was 13.4°, 16.6°, and 18.5°; coronal Cobb angle was 2.8°, 2.2°, and 4.3°; and intervertebral height was 76.2 mm, 71.8 mm, and 70.6 mm. Cage subsidence was not observed and the bone union was achieved in all cases. An expandable cage with a round endcap was placed in small, elderly women by inserting the cage over the strong apophysis of the vertebral body. This technique may be useful to reduce the risk of postoperative subsidence and correction loss.

Minimally Invasive Lateral Retropleural Approach to the Thoracic Spine for Salvage of a Subsided Expandable Interbody Cage.

BACKGROUND: Cylindrical expandable cages are commonly used as interbody grafts after cervical, thoracic, or lumbar corpectomy in patients with osteomyelitis. Unfortunately, there is a high incidence of hardware subsidence due to small-diameter footplates. Newer expandable intervertebral cages with large rectangular endcaps use the anatomic strength of the vertebral epiphyseal ring to prevent subsidence. CASE DESCRIPTION: A 67-year-old man with medically refractory thoracic osteomyelitis and discitis presented to our service for further management of debilitating back pain secondary to a persistent infection and associated progressive spinal kyphotic deformity. He underwent a transpedicular T9-10 corpectomy, placement of an expandable interbody cage, and posterior instrumented spinal fusion from T7 to T12. On postoperative day 2, upright thoracic radiographs demonstrated cage subsidence of >50% into the T8 vertebral body. The patient was returned to the operating room for hardware revision and placement of an expandable intervertebral cage with rectangular endcaps through a minimally invasive lateral retropleural approach to the thoracic spine. The patient tolerated the procedure well, and no evidence of subsidence occurred after the revision after 2 years of follow-up. CONCLUSIONS: Expandable intervertebral cages with rectangular endcaps can be used to prevent and/or correct preexisting cage subsidence in patients in need of anterior column instrumentation, especially in those with bone-weakening pathologies. Prospective studies should be entertained to evaluate subsidence rates in cages with cylindrical versus rectangular endcaps.

An in-tether sulfoxide chiral center influences the biophysical properties of the N-capped peptides.

Thanks to their large binding interfaces, peptides are attractive ligands targeting protein-protein interactions compared with small molecules. Various strategies to improve peptides' pharmaceutical properties have been developed to constrain peptides into their functional three-dimensional structures. In our previous work, we reported that an in-tether chiral center could modulate peptides' biophysical properties. Herein, we applied this concept to construct a chiral sulfoxide center into the N-terminal end-cap system. We proved that this in-tether sulfoxide chiral center influences the structure of this N-capped template. In addition, longer peptides targeting estrogen receptor were also synthesized and we revealed that this chiral center could also modulate binding affinity to estrogen receptor alpha with enhanced protease resistance.

Contribution of Round vs. Rectangular Expandable Cage Endcaps to Spinal Stability in a Cadaveric Corpectomy Model.

BACKGROUND: Expandable cages are gaining popularity in anterior reconstruction of the thoracolumbar spine following corpectomy as they can provide adjustable distraction and deformity correction. Rectangular, rather than circular, endcaps provide increased resistance to subsidence by spanning the apophyseal ring; however their impact on construct stability is not known. The objective of this study was to investigate the contribution of expandable corpectomy cage endcap shape (round vs. rectangular) and fixation method (anterior plate vs. posterior pedicle screws) to the stability of an L1 sub-total corpectomy construct. METHODS: Eight fresh-frozen cadaveric specimens (T11-L3) were subjected to multi-directional flexibility testing to 6 N·m with a custom spine simulator. Test conditions were: intact, L1 sub-total corpectomy defect, expandable cage (round endcap) alone, expandable cage (round endcap) with anterior plate, expandable cage (round endcap) with bilateral pedicle screws, expandable cage (rectangular endcap) alone, expandable cage (rectangular endcap) with anterior plate, expandable cage (rectangular endcap) with bilateral pedicle screws. Range-of-motion across T12-L2 was measured with an optoelectronic system. RESULTS: The expandable cage alone with either endcap provided significant stability to the corpectomy defect, reducing motion to intact levels in flexion-extension with both endcap types, and in lateral bending with rectangular endcaps. Round endcaps allowed greater motion than intact in lateral bending, and axial rotation ROM was greater than intact for both endcaps. Supplemental fixation provided the most rigid constructs, although there were no significant differences between instrumentation or endcap types. CONCLUSIONS: These results suggest anterior-only fixation may be adequate when using an expandable cage in a sub-total corpectomy application and choice of endcap type may be driven by other factors such as subsidence resistance.

A protocol for assay of poly(lactide-co-glycolide) in clinical products.

Poly(lactide-co-glycolide) (PLGA) is the key component of long acting drug products responsible for providing sustained release in a controlled manner. The objective of the current study was to develop and validate an analytical protocol to determine key properties of PLGA used in commercial long-acting drug products. Procedures to isolate PLGA from commercial products have been established and the key properties of PLGA, such as polymer molecular weight, lactide:glycolide (L:G) ratio, and nature of polymer end-cap, have been determined. Identification of the polymer end-cap was confirmed by using two PLGA polymers with acid and ester end-caps. Trelstar(®) and Risperdal Consta(®) were chosen as model products. The calculated L:G ratios of PLGA used in Trelstar(®) and Risperdal(®) are 52:48 and 78:22, respectively. PLGAs from both Trelstar(®) and Risperdal Consta(®) possess ester end-caps. Since the properties of specific PLGA in clinically used formulations are not readily available, this protocol will be useful in developing PLGA-based long acting drug products.

Nearly exclusive growth of small diameter semiconducting single-wall carbon nanotubes from organic chemistry synthetic end-cap molecules.

The inability to synthesize single-wall carbon nanotubes (SWCNTs) possessing uniform electronic properties and chirality represents the major impediment to their widespread applications. Recently, there is growing interest to explore and synthesize well-defined carbon nanostructures, including fullerenes, short nanotubes, and sidewalls of nanotubes, aiming for controlled synthesis of SWCNTs. One noticeable advantage of such processes is that no metal catalysts are used, and the produced nanotubes will be free of metal contamination. Many of these methods, however, suffer shortcomings of either low yield or poor controllability of nanotube uniformity. Here, we report a brand new approach to achieve high-efficiency metal-free growth of nearly pure SWCNT semiconductors, as supported by extensive spectroscopic characterization, electrical transport measurements, and density functional theory calculations. Our strategy combines bottom-up organic chemistry synthesis with vapor phase epitaxy elongation. We identify a strong correlation between the electronic properties of SWCNTs and their diameters in nanotube growth. This study not only provides material platforms for electronic applications of semiconducting SWCNTs but also contributes to fundamental understanding of the growth mechanism and controlled synthesis of SWCNTs.

Extraction of Misplaced Endcap during Tibia Intramedullary Nailing by 'Fish-Hook' Technique: Technical Note

Endcap placement after intramedullary nailing can be cumbersome. Misplacement of the endcap which may be difficult to extract may occur. In this report, a simple Kirschner wire device with 'fish-hook' technique may ease the procedure without further violating bony or soft tissues.

Corpectomy cage subsidence with rectangular versus round endcaps.

Corpectomy cages with rectangular endcaps utilize the stronger peripheral part of the endplate, potentially decreasing subsidence risk. The authors evaluated cage subsidence during cyclic biomechanical testing, comparing rectangular versus round endcaps. Fourteen cadaveric spinal segments (T12-L2) were dissected and potted at T12 and L2, then assigned to a rectangular (n=7) or round (n=7) endcap group. An L1 corpectomy was performed and under uniform conditions a cage/plate construct was cyclically tested in a servo-hydraulic frame with increasing load magnitude. Testing was terminated if the test machine actuator displacement exceeded 6mm, or the specimen completed cyclic loading at 2400 N. Number of cycles, compressive force and force-cycles product at test completion were all greater in the rectangular endcap group compared with the round endcap group (cycles: 3027 versus 2092 cycles; force: 1943 N versus 1533 N; force-cycles product: 6162kN·cycles versus 3973 kN·cycles), however these differences were not statistically significant (p ⩾ 0.076). After normalizing for individual specimen bone mineral density, the same measures increased to a greater extent with the rectangular endcaps (cycles: 3014 versus 1855 cycles; force: 1944 N versus 1444 N; force-cycles product: 6040 kN·cycles versus 2980 kN·cycles), and all differences were significant (p⩽0.030). The rectangular endcap expandable corpectomy cage displayed increased resistance to subsidence over the round endcap cage under cyclic loading as demonstrated by the larger number of cycles, maximum load and force-cycles product at test completion. This suggests rectangular endcaps will be less susceptible to subsidence than the round endcap design.

Analysis of Endcap Effect for MRI Birdcage RF Coil by FDTD Method

PURPOSE: B1 field of birdcage RF (radiofrequency) coil that is used most for brain imaging in magnetic resonance imaging (MRI) decreases toward endring from the coil center. We investigated how much RF B1 homogeneity effect the endcap shield brings form the coil center as it towards to endcap region. MATERIALS AND METHODS: We compared RF B1 field distribution by each finite difference time domain (FDTD) simulations for lowpass, highpass and hybrid birdcage RF coils. We selected the highpass birdcage RF coil that was the highest RF B1 field condition as simulation result, and studied how much RF B1 homogeneity effect was occurred when endcap shield was applied to endring area. RESULTS: B1 field of the highpass birdcage RF coil was higher than other birdcage RF coil types as simulation result. However, the RF B1 homogeneity was lower than other coil types. RF B1 field of highpass birdcage RF coil with endcap shield is similar with RF B1 field of hybrid birdcage RF coil and the overall RF B1 homogeneity in sagittal direction was better. CONCLUSION: In this paper, proposed method can apply improving RF B1 homogeneity of RF coil in clinical examination.