As effective building blocks for high-mobility transistor polymers, oligothiophenes are receiving attention for polymer solar cells (PSCs) because the resulting polymers can effectively suppress ...charge recombination. Here we investigate two series of in-chain donor–acceptor copolymers, PTPDnT and PBTInT, based on thieno3,4-cpyrrole-4,6-dione (TPD) or bithiopheneimide (BTI) as electron acceptor units, respectively, and oligothiophenes (nTs) as donor counits, for high-performance PSCs. Intramolecular S···O interaction leads to more planar TPD polymer backbones, however backbone torsion yields greater open-circuit voltages for BTI polymers. Thiophene addition progressively raises polymer HOMOs but marginally affects their band gaps. FT-Raman spectra indicate that PTPDnT and PBTInT conjugation lengths scale with nT catenation up to n = 3 and then saturate for longer oligomer. Furthermore, the effects of oligothiophene alkylation position are explored, revealing that the alkylation pattern greatly affects film morphology and PSC performance. The 3T with “outward” alkylation in PTPD3T and PBTI3T affords optimal π-conjugation, close stacking, long-range order, and high hole mobilities (0.1 cm2/(V s)). These characteristics contribute to the exceptional ∼80% fill factors for PTPD3T-based PSCs with PCE = 7.7%. The results demonstrate that 3T is the optimal donor unit among nTs (n = 1–4) for photovoltaic polymers. Grazing incidence wide-angle X-ray scattering, transmission electron microscopy, and time-resolved microwave conductivity measurements reveal that the terthiophene-based PTPD3T blend maintains high crystallinity with appreciable local mobility and long charge carrier lifetime. These results provide fundamental materials structure-device performance correlations and suggest guidelines for designing oligothiophene-based polymers with optimal thiophene catenation and appropriate alkylation pattern to maximize PSC performance.
Heterogeneity of cancer stem/progenitor cells that give rise to different forms of cancer has been well demonstrated for leukemia. However, this fundamental concept has yet to be established for ...solid tumors including breast cancer. In this communication, we analyzed solid tumor cancer stem cell markers in human breast cancer cell lines and primary specimens using flow cytometry. The stem/progenitor cell properties of different marker expressing-cell populations were further assessed by in vitro soft agar colony formation assay and the ability to form tumors in NOD/SCID mice. We found that the expression of stem cell markers varied greatly among breast cancer cell lines. In MDA-MB-231 cells, PROCR and ESA, instead of the widely used breast cancer stem cell markers CD44(+)/CD24(-/low) and ALDH, could be used to highly enrich cancer stem/progenitor cell populations which exhibited the ability to self renew and divide asymmetrically. Furthermore, the PROCR(+)/ESA(+) cells expressed epithelial-mesenchymal transition markers. PROCR could also be used to enrich cells with colony forming ability from MB-361 cells. Moreover, consistent with the marker profiling using cell lines, the expression of stem cell markers differed greatly among primary tumors. There was an association between metastasis status and a high prevalence of certain markers including CD44(+)/CD24(-/low), ESA(+), CD133(+), CXCR4(+) and PROCR(+) in primary tumor cells. Taken together, these results suggest that similar to leukemia, several stem/progenitor cell-like subpopulations can exist in breast cancer.
Careful selection of processing solvents to tune optimal active layer morphology in a donor‐acceptor copolymer blend PTB7:P(NDI2OD‐T2) yields bulk heterojunction microstructures with intradomain ...percolative pathways and enhanced charge transport. Such microstructures afford all‐polymer solar cells with power conversion efficiencies as high as 2.7%.
Over the past five years, a rapid progress in organometal‐halide perovskite solar cells has greatly influenced emerging solar energy science and technology. In perovksite solar cells, the overlying ...hole transporting material (HTM) is critical for achieving high power conversion efficiencies (PCEs) and for protecting the air‐sensitive perovskite active layer. This study reports the synthesis and implementation of a new polymeric HTM series based on semiconducting 4,8‐dithien‐2‐yl‐benzo1,2‐d;4,5‐d′bistriazole‐alt‐benzo1,2‐b:4,5‐b′dithiophenes (pBBTa‐BDTs), yielding high PCEs and environmentally‐stable perovskite cells. These intrinsic (dopant‐free) HTMs achieve a stabilized PCE of 12.3% in simple planar heterojunction cells—the highest value to date for a polymeric intrinsic HTM. This high performance is attributed to efficient hole extraction/collection (the most efficient pBBTa‐BDT is highly ordered and orients π‐face‐down on the perovskite surface) and balanced electron/hole transport. The smooth, conformal polymer coatings suppress aerobic perovskite film degradation, significantly enhancing the solar cell 85 °C/65% RH PCE stability versus typical molecular HTMs.
New in‐chain donor–acceptor semiconducting copolymers are designed and synthesized as dopant‐free perovskite solar cell hole transport materials. Combining the BDT donor and the BBTa acceptor building blocks yields pBBTa‐BDT copolymers with strong interchain interactions, substantial quinoidal π‐character, preferential π‐face‐on orientation, and therefore efficient hole extraction/collection and balanced electron/hole transport. Significant enhancement of solar cell performance and environmental stability are achieved.
Recent advances in polymer solar cell (PSC) performance have resulted from compressing the bandgap to enhance the short-circuit current while lowering the highest occupied molecular orbital to ...increase the open-circuit voltage. Nevertheless, PSC power conversion efficiencies are still constrained by low fill factors, typically below 70%. Here, we report PSCs with exceptionally high fill factors by combining complementary materials design, synthesis, processing and device engineering strategies. The donor polymers, PTPD3T and PBTI3T, when incorporated into inverted bulk-heterojunction PSCs with a PC71 BM acceptor, result in PSCs with fill factors of 76-80%. The enhanced performance is attributed to highly ordered, closely packed and properly oriented active-layer microstructures with optimal horizontal phase separation and vertical phase gradation. The result is efficient charge extraction and suppressed bulk and interfacial bimolecular recombination. The high fill factors yield power conversion efficiencies of up to 8.7% from polymers with suboptimal bandgaps, suggesting that efficiencies above 10% should be realizable by bandgap modification.
Intra-operative imaging techniques for obtaining the shape and morphology of soft-tissue surfaces in vivo are a key enabling technology for advanced surgical systems. Different optical techniques for ...3-D surface reconstruction in laparoscopy have been proposed, however, so far no quantitative and comparative validation has been performed. Furthermore, robustness of the methods to clinically important factors like smoke or bleeding has not yet been assessed. To address these issues, we have formed a joint international initiative with the aim of validating different state-of-the-art passive and active reconstruction methods in a comparative manner. In this comprehensive in vitro study, we investigated reconstruction accuracy using different organs with various shape and texture and also tested reconstruction robustness with respect to a number of factors like the pose of the endoscope as well as the amount of blood or smoke present in the scene. The study suggests complementary advantages of the different techniques with respect to accuracy, robustness, point density, hardware complexity and computation time. While reconstruction accuracy under ideal conditions was generally high, robustness is a remaining issue to be addressed. Future work should include sensor fusion and in vivo validation studies in a specific clinical context. To trigger further research in surface reconstruction, stereoscopic data of the study will be made publically available at www.open-CAS.com upon publication of the paper.
Bithiophene imide (BTI) and benzodithiophene (BDT) copolymers are synthesized for application in organic photovoltaic (OPV) cells. The electron deficiency of the BTI units leads to polymers with a ...low‐lying HOMOs (∼‐5.6 eV). Inverted solar cells are fabricated to investigate the OPV performance of the BTI‐based polymers and achieve power conversion efficiencies up to 5.5%, with substantial Vocs above 0.9 V which are among the highest Vocs reported to date for polymer/PCBM solar cells. The results indicate that the BTI is a promising building block for constructing polymer donors for OPV applications.
The efficacy of sequential therapy and the applicability of genotypic resistance to guide the selection of antibiotics in the third-line treatment of Helicobacter pylori have not been reported. We ...aimed to assess the efficacy of genotypic resistance-guided sequential therapy in third-line treatment.
Genotypic and phenotypic resistances were determined in patients who failed at least two eradication therapies by PCR with direct sequencing and agar dilution test, respectively. The patients were retreated with sequential therapy containing esomeprazole and amoxicillin for the first 7 days, followed by esomeprazole and metronidazole plus clarithromycin, levofloxacin or tetracycline for another 7 days (all twice daily), according to genotypic resistance determined using gastric biopsy specimens. Eradication status was determined by the (13)C-urea breath test. Trial registered at clinicaltrials.gov (identifier: NCT01032655).
The overall eradication rate was 80.7% (109/135, 95% CI 73.3%-86.5%) in the intention-to-treat analysis. The presence of amoxicillin resistance (OR 6.83, 95% CI 1.62-28.86, P = 0.009) and prior sequential therapy (OR 4.77, 95% CI 1.315-17.3, P = 0.017), but not tetracycline resistance (tetracycline group), were associated with treatment failure. The eradication rates in patients who received clarithromycin-, levofloxacin- and tetracycline-based sequential therapies were 78.9% (15/19), 92.2% (47/51) and 71.4% (25/35) in strains susceptible to clarithromycin, levofloxacin and tetracycline, respectively.
A simple molecular method guiding sequential therapy can achieve a high eradication rate in the third-line treatment of refractory H. pylori infection.
Shear-printing is a promising processing technique in organic electronics for microstructure/charge transport modification and large-area film fabrication. Nevertheless, the mechanism by which ...shear-printing can enhance charge transport is not well-understood. In this study, a printing method using natural brushes is adopted as an informative tool to realize direct aggregation control of conjugated polymers and to investigate the interplay between printing parameters, macromolecule backbone alignment and aggregation, and charge transport anisotropy in a conjugated polymer series differing in architecture and electronic structure. This series includes (i) semicrystalline hole-transporting P3HT, (ii) semicrystalline electron-transporting N2200, (iii) low-crystallinity hole-transporting PBDTT-FTTE, and (iv) low-crystallinity conducting PEDOT:PSS. The (semi-)conducting films are characterized by a battery of morphology and microstructure analysis techniques and by charge transport measurements. We report that remarkably enhanced mobilities/conductivities, as high as 5.7×/3.9×, are achieved by controlled growth of nanofibril aggregates and by backbone alignment, with the adjusted R² (R²adj) correlation between aggregation and charge transport as high as 95%. However, while shear-induced aggregation is important for enhancing charge transport, backbone alignment alone does not guarantee charge transport anisotropy. The correlations between efficient charge transport and aggregation are clearly shown, while mobility and degree of orientation are not always well-correlated. These observations provide insights into macroscopic charge transport mechanisms in conjugated polymers and suggest guidelines for optimization.
Asthma is a chronic inflammatory airway disease accounting for severe morbidity and mortality in children. To determine the characteristics of traditional Chinese medicine (TCM) used to treat ...pediatric asthma, we conducted a nationwide population‐based study by analyzing a cohort of one million randomly sampled patients from the beneficiaries of the National Health Insurance Program in Taiwan from 2002 to 2010. Children under 18 years of age with newly diagnosed asthma (ICD‐9‐CM code: 493, N = 45 833) were enrolled, and 57.95% (N = 26 585) of them had used TCM. The number of TCM users was significantly more than that of non‐TCM users in school‐age children. The most commonly prescribed TCM formula is Ding‐chuan‐tang, or Xing‐ren (Semen Armeniacae Amarum) for the single herb. Our study is the first to reveal characteristics and prescription patterns of the use of TCM in children with asthma. Further research is needed to elucidate the efficacy and safety of these Chinese herbal products.
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