Efficient and Stable All-Polymer Solar Cells Enabled by Dual Working Mechanism.

Ternary strategy with integration characteristics and adaptability is a simple and effective method for blooming of the performance of photovoltaic devices. Herein, a novel wideband gap polymer donor PBB2-Hs is synthesized as the guest component to optimize all-polymer solar cells (all-PSCs). High-energy photon absorption and long exciton lifetime of PBB2-Hs constitute efficient energy transfer. Good miscibility and cascade energy levels promote the formation of alloy-like structure between PBB2-Hs and host system. The dual working mechanisms greatly improve photon capture and charge transfer in active layers. Additionally, the introduction of PBB2-Hs also optimizes the ordered molecular stacking of acceptors and suppresses molecular peristalsis. Upon adding 15 wt% PBB2-Hs, the ternary all-PSC achieved a champion efficiency of 17.66%, and can still maintain 82% photostability (24 h) and 91% storage stability (1000 h) of the original PCE. Moreover, the strong molecular stacking and entanglement between PBB2-Hs and the host material increased the elongation at break of ternary blend film by 1.6 times (16.2%), allowing the flexible device to maintain 83% of the original efficiency after 800 bends (R = 5 mm). This work highlights the effectiveness of guest polymer on simultaneously improving photovoltaic performance, photostability and mechanical stability in all-PSCs.

Efficient Dual Mechanisms Boost the Efficiency of Ternary Solar Cells with Two Compatible Polymer Donors to Exceed 19.

Ternary strategyopens a simple avenue to improve the power conversion efficiency (PCE) of organic solar cells (OSCs). The introduction of wide bandgap polymer donors (PDs) as third component canbetter utilize sunlight and improve the mechanical and thermal stability of active layer. However, efficient ternary OSCs (TOSCs) with two PDs are rarely reported due to inferior compatibility and shortage of efficient PDs match with acceptors. Herein, two PDs-(PBB-F and PBB-Cl) are adopted in the dual-PDs ternary systems to explore the underlying mechanisms and improve their photovoltaic performance. The findings demonstrate that the third components exhibit excellent miscibility with PM6 and are embedded in the host donor to form alloy-like phase. A more profound mechanism for enhancing efficiency through dual mechanisms, that are the guest energy transfer to PM6 and charge transport at the donor/acceptor interface, has been proposed. Consequently, the PM6:PBB-Cl:BTP-eC9 TOSCs achieve PCE of over 19%. Furthermore, the TOSCs exhibit better thermal stability than that of binary OSCs due to the reduction in spatial site resistance resulting from a more tightly entangled long-chain structure. This work not only provides an effective approach to fabricate high-performance TOSCs, but also demonstrates the importance of developing dual compatible PD materials.

Impact of backbone linkage positions on the molecular aggregation behavior of polymer photovoltaic materials.

It is imperative to advance the structural design of conjugated materials to achieve a practical impact on the performance of photovoltaic devices. However, the effect of the linkage positions (meta-, para-) of the backbone on the molecular packing has been relatively little explored. In this study, we have synthesized two wide-bandgap polymer photovoltaic materials from identical monomers with different linkage positions, using dibenzo[c,h][2,6]-naphthyridine-5,11-(6H,12H)-dione (DBND) as the building block. This study shows that the para-connected polymer exhibits an unexpected 0.2 eV higher ionization potential and a resultant higher open-circuit voltage than the meta-connected counterpart. We found that different linkage positions result in different intermolecular binding energies and molecular aggregation conformations, leading to different HOMO energy levels and photovoltaic performances. Specifically, theoretical calculations and 2D-NMR indicate that P(p-DBND-f-2T) performs a segregated stacking of f-2T and DBND units, while P(m-DBND-f-2T) films form π-overlaps between f-2T and DBND. These results show that linkage position adjustment on the polymeric backbone exerts a profound influence on the molecular aggregation of the materials. Also, the effect of isomerism on the polymer backbone is crucial in designing polymer structures for photovoltaic applications.

Benzobis(Thiazole)-Based Conjugated Polymer with Varying Alkylthio Side-Chain Positions for Efficient Fullerene-Free Organic Solar Cells.

Alkylthio groups can be used to modulate energy levels and molecular packing of organic semiconductors, which makes it important in the design of materials for organic solar cell. However, its effect has not been sufficiently exploited as most of the studies report introducing an alkylthio group to the donor unit and seldom to the acceptor unit of donor-acceptor conjugated polymers. In this report, two alkylthio-substituted polymers, namely, PBB-TSA and PBB-TSD, with benzo[1,2-d:4,5-d']bis(thiazole) (BBT) as the acceptor unit and benzo[1,2-b:4,5-b']dithiophene (BDT) as the donor unit, were rationally designed, synthesized, and applied in organic photovoltaics. An alkylthio side chain was substituted on the BBT-accepting unit for PBB-TSA, while for PBB-TSD, the alkylthio side chain was substituted on the BDT donor unit. PBB-TSA and PBB-TSD show upshifted and downshifted energy levels, respectively, compared to the nonsulfur-substituted material. Both polymers exhibit dominate face-on orientation, while PBB-TSD exhibits higher crystallinity compared to PBB-TSA. With the contribution of lower energy level and beneficial film morphology, the device based on PBB-TSD/IT-4F has much higher power conversion efficiency (PCE) of 14.6%, whereas the PBB-TSA blend had a lower PCE of 10.7%. 1,8-Diiodooctane can effectively optimize the blend film morphology, and the effect on device performance has also been demonstrated in detail. This result indicates that introducing an alkylthio side chain into the donor or acceptor moieties would result in materials with different energy levels and thus would be utilized to match with various acceptors, achieving optimized performance in organic solar cells.

Dithieno[3,2-b:2',3'-d]silole-based conjugated polymers for bioimaging in the short-wave infrared region.

The short-wave infrared window (SWIR, 900-1700 nm) fluorescence imaging has been demonstrated to have excellent imaging performance in signal/noise ratio and tissue penetration compared to the conventional NIR biological window (NIR-I, 700-900 nm). Conventional organic SWIR fluorescent materials still suffer from low fluorescence quantum efficiency. In this work, a donor unit with sp3 hybrid configuration and an acceptor unit with small hindered alkyl side chains are employed to construct donor-acceptor (D-A) type conjugated polymers P1 and P2, which were substituted with one or two fluorine atoms. These structural features can alleviate the aggregation-caused quenching (ACQ) and contribute to charge transfer, resulting in a significantly improved fluorescence quantum efficiency. The SWIR fluorescent quantum efficiencies of P1 and P2 nanoparticles are 3.4% and 4.4%, respectively, which are some of the highest for organic SWIR fluorophores reported so far. Excellent imaging quality has been demonstrated with P2 nanoparticles for SWIR imaging of the vascular system of nude mice. The results indicate that our design strategy of introducing sp3 hybrid configuration and small hindered alkyl side chains to fabricate conjugated polymers is efficient in improving the fluorescent quantum efficiency as SWIR fluorescent imaging agents for potential clinical practice.

Amylase-Protected Ag Nanodots for in vivo Fluorescence Imaging and Photodynamic Therapy of Tumors.

BACKGROUND: Fluorescent metallic nanodots (NDs) have become a promising nanoprobe for a wide range of biomedical applications. Because Ag NDs have a high tendency to be oxidized, their synthesis and storage are a big challenge. Thus, the method for preparing stable Ag NDs is urgently needed. Surface modification and functionalization can enrich the capability of Ag NDs. METHODS: In this work, fluorescent Ag NDs were synthesized in deoxygenated water by using porcine pancreatic α-amylase (PPA) as the stabilizing/capping agent. The absorption and fluorescence of PPA-protected Ag NDs (PPA@AgNDs) were measured with a spectrophotometer and a spectrofluorometer, respectively. The morphology of PPA@AgNDs was characterized by high-angle annular dark-field (HAADF) scanning transmission electron microscopy (STEM). The biocompatibility of PPA@AgNDs was evaluated by tetrazolium (MTT)-based assay. PolyLys-Cys-SH (sequence: KKKKKKC) peptides were conjugated to PPA@AgNDs via heterobifunctional crosslinkers. PolyLys-Cys-linked PPA@AgNDs absorbed 5-aminolevulinic acid (ALA) by electrostatic interaction at physiological pH. The capability of tumor targeting was evaluated by intravenously injecting PPA@AgND-ALA into 4T1 breast cancer xenograft mouse models. Photodynamic therapy (PDT) against tumors was performed under 635 nm laser irradiation. RESULTS: PPA@AgNDs emitted at 640 nm with quantum yield of 2.1%. The Ag NDs exhibited strong photostability over a long period and a fluorescence lifetime of 5.1 ns. PPA@AgNDs easily entered the cells to stain the nuclei, showing the capabilities of living cell imaging with negligible cytotoxicity. ALA-loaded PPA@AgNDs (PPA@AgND-ALA) presented the superiority of passive tumor targeting via the enhanced permeability and retention (EPR) effect. Tumors were visualized in the near-infrared (NIR) region with reduced background noise. ALA molecules released from PPA@AgND-ALA was converted into the photosensitizer (PS) of protoporphyrin IX (PpIX) intracellularly and intratumorally, which greatly improved the PDT efficacy. CONCLUSION: Our approach opens a new way to design a novel theranostic nanoplatform of PPA@AgND-ALA for effective tumor targeting and fluorescence image-guided PDT.

Toward Efficient All-Polymer Solar Cells via Halogenation on Polymer Acceptors.

Although halogenation has been widely regarded as an effective approach to adjust the properties of organic semiconductors, systematic investigation on the comparison of nonhalogenated and halogenated polymer acceptors only received minor attention in all-polymer solar cell (all-PSC) community. Herein, we report three IDIC-based narrow band gap polymer acceptors, PIDIC2T, PIDIC2T2F, and PIDIC2T2Cl, which are composed of IDIC-C16 building blocks as acceptor units, linking pristine bithiophene, fluorinated bithiophene, or chlorinated bithiophene as donor units. Although these three polymer acceptors exhibit nearly identical lowest unoccupied molecular orbital (LUMO) levels of ca. -3.87 eV with a similar optical band gap of ca. 1.54 eV, we found that different halogen species significantly affect the electron mobility and thin-film morphology of the polymer acceptors. All-PSCs were fabricated by pairing three polymer acceptors with a PBDB-T polymer donor, while PIDIC2T2Cl delivered a highest power conversion efficiency (PCE) of 5.34% due to its favorable bulk morphology with smaller root-mean-square (rms) roughness values, which induce the relatively more balanced charge carrier mobilities. By blending the fluorinated analogue of PBDB-T, PM6, further improved VOC, JSC, and fill factor (FF) of devices were achieved (5.46% for PM6:PIDIC2T, 4.96% for PM6:PIDIC2T2F, 7.11% for PM6:PIDIC2T2Cl), which can be due to the synergistic effect of the deeper highest occupied molecular orbital (HOMO) energy level of PM6, enhanced crystallinity, and more matched charge transport. This systematic study provides an insight into the influence of halogenation (fluorination and chlorination) on the optoelectrical properties of n-type organic semiconductors and demonstrates an efficient strategy that the design guideline for polymer acceptors can be enriched by backbone halogenation to further develop high-performance all-PSCs.

Fuse the π-Bridge to Acceptor Moiety of Donor-π-Acceptor Conjugated Polymer: Enabling an All-Round Enhancement in Photovoltaic Parameters of Nonfullerene Organic Solar Cells.

The D-π-A conjugated polymers with a benzotriazole (BTz) unit as the A moiety have been intensively investigated as donor materials in nonfullerene solar cells. However, these BTz even the fluorinated-BTz constructed D-π-A polymers mostly suffered from upward highest occupied molecular orbital (HOMO) energy levels, leading to inferior open-circuit voltage (VOC) and efficiencies in the fabricated solar cells. Herein, we explored a new approach in response to this issue via the strategy of π-bridge fusion to A moiety. As a result, the medium band gap D-π-A polymer PY2 was evolved into wide band gap D-A polymer PY1 with fused-DTBTz as the new A moiety, accompanied with a greatly declined HOMO energy level by 0.26 eV, a remarkable blue-shifted absorption onset by about 51 nm, and concurrently moderately enhanced face-on stacking orientations in neat polymer and donor/acceptor blend films. The synergetic optimizations in energy level, absorption characteristic and molecular stacking feature via the π-bridge fusion design witness an all-round improvement in photovoltaic parameters including the focused VOC, short-circuit current density (JSC), and fill factor (FF), with narrow band gap ITIC as the acceptor material. Specifically, the PY1-based solar cells produce an optimal power conversion efficiency (PCE) of 12.49%, with superior VOC of 0.94 V, JSC of 18.46 mA cm-2, and FF of 0.72, significantly surpassing those of PY2-based optimal device with a PCE of 7.39%, VOC of 0.77 V, JSC of 14.54 mA cm-2, and FF of 0.66 and even the reported classical fluorinated-BTz based polymer J51 (VOC of 0.82 V, PCE of 9.26%). Promisingly, there is a huge room for improvement in photovoltaic properties with rational fluorination or chlorination of the fused-DTBTz unit or the D moiety of the D-A polymers.

Synthesis of a tetrazine-quaterthiophene copolymer and its optical, structural and photovoltaic properties.

Herein, we report the synthesis of a novel, tetrazine-based conjugated polymer. Tetrazines have the benefit of being strong electron acceptors, while little steric hindrance is imposed on the flanking thiophene rings. Conversion of a suitably substituted nitrile precursor led to 3,6-bis(5-bromo-4-(2-octyldodecyl)thiophen-2-yl)-1,2,4,5-tetrazine (2OD-TTz). Palladium-catalyzed copolymerization of 2OD-TTz with a bithiophene monomer yielded an alternating tetrazine-quaterthiophene copolymer (PTz4T-2OD). The polymer PTz4T-2OD showed an optical band gap of 1.8 eV, a deep HOMO energy level of - 5.58 eV and good solubility. In combination with the non-fullerene acceptor ITIC-F, solar cells with power conversion efficiencies of up to 2.6% were obtained.

A Simple Phenyl Group Introduced at the Tail of Alkyl Side Chains of Small Molecular Acceptors: New Strategy to Balance the Crystallinity of Acceptors and Miscibility of Bulk Heterojunction Enabling Highly Efficient Organic Solar Cells.

Research on fused-ring small-molecular-acceptors (SMAs) has deeply advanced the development of organic solar cells (OSCs). Compared to fruitful studies of ladder-type cores and end-caps of SMAs, the exploration of side chains is monotonous. The widely utilized alkyl and aryl side chains usually produce a conflicting association between SMAs' crystallinity and miscibility. Herein, a fresh idea about the modification of side chains is reported to explore the subtle balance between the crystallinity and miscibility. Specifically, a phenyl is introduced to the tail of the alkyl side chain whereby a new acceptor IDIC-C4Ph is reported. Moderately weakened crystallinity is observed, while maintaining preferred absorption profiles and face-on orientations. Concurrently, remarkably improved heterojunction morphologies and stacking orientations are detected. PBDB-T:IDIC-C4Ph devices exhibit greater efficiency of 11.50% than devices from alky and aryl modified acceptors. Notably, the as-cast OSCs of PBDB-TF:IDIC-C4Ph reveal outstanding FF over 76% with the best efficiency up to 13.23%. The annealed devices reveal further increased efficiency exceeding 14% with the state of the art FF of 78.32%. Overall, an effective but easily navigable approach is demonstrated to modulate the crystallinity of SMAs toward synergistically improved morphologies and molecular orientations of bulk heterojunction enabling highly efficient OSCs.

Prognostic factors in patients with penile cancer after surgical management.

PURPOSE: To examine the possible prognostic factors in patients with penile cancer after surgical management and to identify the independent predictive factors of the prognosis. MATERIALS AND METHODS: Clinical data of 135 patients with penile cancer who underwent surgical management in two medical centers were collected. Follow-up data were available for 103 patients. Possible prognostic factors including patient's age; smoking or not; course of disease; phimosis or not; type of surgery; tumor stage; nodal stage; tumor grade and pathological lymph nodes metastasis were retrospectively analyzed by univariate and multivariate analyses with Cox regression. RESULTS: Five-year cancer-specific survival (CSS) and 1-year CSS were 88.5 and 98.1%, respectively. Univariate Cox analysis revealed that nodal stage and pathological lymph nodes metastasis were significant prognostic factors. Multivariate Cox analysis revealed pathological lymph nodes metastasis was the independent predictive factor of the prognosis. CONCLUSION: Pathological lymph nodes metastasis is the independent predictive factor worsening the prognosis in patients with penile cancer.

Pyran-Bridged Indacenodithiophene as a Building Block for Constructing Efficient A-D-A-Type Nonfullerene Acceptors for Polymer Solar Cells.

In recent years, nonfullerene acceptors have attracted much attention, owing to their great potential for use in high-performance polymer solar cells.The ladder-type building block, pyran-bridged indacenodithiophene (PDT), was used for constructing A-D-A nonfullerene acceptors through introduction of oxygen atoms into an indacenodithiophene (IDT) unit. The synthesis of PDT is accomplished by a BBr3 -mediated tandem cyclization-deprotection reaction to construct the pyran ring. Hence, molecular acceptor PTIC was synthesized and used in a polymer solar cell device. Compared to the IDT-based acceptor, PTIC exhibits higher HOMO levels and wider optical band gap at 550-800 nm. Devices fabricated with poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b']dithiophene)-co-(1,3-di(5-thiophene-2-yl)-5,7-bis(2-ethylhexyl)-benzo[1,2-c:4,5-c']dithiophene-4,8-dione)] (PBDB-T):PTIC as the active layer give a power conversion efficiency (PCE) of 7.66 %.

Investigation of Fluorination on Donor Moiety of Donor-Acceptor 4,7-Dithienylbenzothiadiazole-Based Conjugated Polymers toward Enhanced Photovoltaic Efficiency.

It is known that fluorination on π-conjugated donor-acceptor (D-A) polymers can significantly affect the optoelectronic properties and fluorination on A moiety has been well established for design of efficient photovoltaic materials. For example, polymers based on 4,7-dithienyl-5,6-difluorobenzothiadiazole (DTffBT) have been intensively investigated and exhibited excellent performance, but the corresponding DTBT-based polymers without fluorine often display an unfavorable efficiency. With the purpose of improving photovoltaic efficiency of DTBT-based D-A polymers, we design three polymers PDTBT-TxfBT (x = 0, 1, 2) with fluorination on D moiety (TxfBT) and systematically investigate fluorination on the photophysical/electrochemical and photovoltaic properties. The results show that polymer solar cells (PSCs) based on PDTBT-TBT exhibit moderate power conversion efficiency (PCE) of 5.84%. However, the bis-fluorination on TffBT moiety (PDTBT-TffBT) can greatly enhance the molecular planarity and intermolecular interaction, improve the charge transport and heterojunction morphology, and further suppress the charge recombination losses. PSCs based on PDTBT-TffBT demonstrate obviously improved photovoltaic efficiency with the best PCE up to 7.53% without any processing additives, which ranks among the top DTBT-based PSCs. However, it should be noted that unsymmetrical fluorination on TfBT moiety (PDTBT-TfBT) impairs the regularity of polymer backbone and intermolecular interaction, increases the recombination losses, and seriously reduces the short-circuit current density and efficiency (5.44%). The results exhibit that fluorination on D moiety is a helpful strategy for design high-performance photovoltaic materials and the regularity of fluorination is crucial to improving efficiencies.

Aromatic Heterocycle 1,3,4-Oxadiazole-Substituted Thieno[3,4-b]thiophene to Build Low-Bandgap Polymer for Photovoltaic Application.

Electron-deficient heterocycle 1,3,4-oxadiazole is first introduced to the 2-position of thieno[3,4-b]thiophene (TT) to construct a new building block 2-(thieno[3,4-b]thiophen-2-yl)-5-(alkylthio)-1,3,4-oxadiazole (TTSO) with alkylthio chain. The polymer PBDT-TTSO based on TTSO and benzodithiophene (BDT) exhibits a deep lying highest occupied molecular orbital (HOMO) energy level of -5.32 eV and low-bandgap of 1.62 eV. The power conversion efficiency (PCE) of 5.86% is obtained with a relatively high V OC of 0.74 V, a J SC of 13.1 mA cm(-2), and FF of 60.5%. Furthermore, as S atom in thioether can be oxidized easily, the optoelectronic properties of PBDT-TTSO treated with different oxidants are preliminary investigated. Interestingly, the oxidation products still maintain high PCE with reduction less than 30%. This work demonstrates a new method to regulate HOMO energy levels by introducing electron-deficient aromatic heterocyclic moiety.

New benzo[1,2-b:4,5-b']dithiophene-based small molecules containing alkoxyphenyl side chains for high efficiency solution-processed organic solar cells.

A new acceptor-donor-acceptor (A-D-A) small molecule, namely, BDT-PO-DPP, based on the alkoxyphenyl (PO)-substituted benzo[1,2-b:4,5-b']dithiophene (BDT) derivative and the diketopyrrolopyrrole (DPP) unit was synthesized as an electron donor for solution-processed small-molecule organic solar cells (SMOSCs). BDT-PO-DPP exhibited good thermal stability, with a 5 % weight-lost temperature at 401 °C under a nitrogen atmosphere. BDT-PO-DPP exhibited a lower HOMO energy level of -5.25 eV and a weaker aggregation ability than alkoxy-substituted BDT-O-DPP. A bulk heterojunction SMOSC device based on BDT-PO-DPP and [6,6]-phenyl-C61 -butyric acid methyl ester was prepared, and it showed a power conversion efficiency up to 5.63% with a high open-circuit voltage of 0.83 V, a short circuit current density of 11.23 mA cm(-2) , and a fill factor of 60.37% by using 1,2-dichlorobenzene as the co-solvent after thermal annealing at 110 °C. The results indicate that the alkoxyphenyl-substituted BDT derivative is a promising electron-donor building block for constructing highly efficient solution-processed SMOSCs.

Development of new two-dimensional small molecules based on benzodifuran for efficient organic solar cells.

A new organic small molecule, DCA3TBDF, with a 2D benzo[1,2-b:4,5-b']difuran (BDF) moiety as the central core and octyl cyanoacetate units as the end-capped blocks, was designed and synthesized for solution-processed bulk heterojunction solar cells. DCA3TBDF possesses good solubility in common organic solvents such as toluene, CH2Cl2, chlorobenzene, and CHCl3 and good thermal stability with an onset decomposition temperature with 5% weight-loss occurring at 361 °C. The DCA3TBDF thin film showed a broad absorption at λ=320-700 nm and high crystallinity. Small-molecule organic solar cells based on DCA3TBDF and [6,6]-phenyl-C61-butyric acid methyl ester demonstrated promising power conversion efficiency with a high fill factor under the illumination of AM 1.5G (100 mW cm(-2)).

Total synthesis of the G2/M DNA damage checkpoint inhibitor psilostachyin C.

A concise total synthesis of the G2/M DNA damage checkpoint inhibitor psilostachyin C is reported using a 1,4-addition-aldol condensation-ring-closing metathesis (RCM) strategy. Initial biological studies indicate that psilostachyin C could enhance the sensitivity of the HeLa cell toward camptothecin (CPT) treatment via the activation of the caspase-3 mediated apoptosis pathway.

[Stereological study on the synapse loss in visual cortex of mouse after prenatal alcohol exposure].

In order to understand the alcohol's toxicity to the quantitative alternations of synapses in mouse visual cortex, the expression of synaptophysin after prenatal alcohol exposure was investigated. In present study, the experimental mice at P0, P7, P14 and P30 were grouped, as control, 2 g x kg(-1) alcohol treatment and 4 g x kg(-1) alcohol treatment. The pre-synaptic elements which were used to represent synapses were marked with synaptophysin (a synaptic vesicle associated protein) by immunocytochemistry technique. The synaptophysin positive boutons in layer VI of visual cortex were imaged under laser confocal microscope. With stereological methods, the number cal density of synapse in visual cortex was calculated in different groups at various ages. Moreover, Western blotting was carried out to detect the expression of synaptophysin in visual cortex. The results showed that prenatal alcohol exposure could cause synaptic loss with long-term effect and in a dose dependent manner. For instance, there were significant difference among the different treatment groups of P0, P14 and P30 as well (P < 0.05). Western blotting supported the results of immunofluorescent labeling. In conclusion, prenatal alcohol exposure can induce the synaptic loss dose dependently and with long-term effect. Our findings implicate that the synaptic loss with long-term effect in CNS probably contributes to the lifelong mental retardation and memorial lowliness associated with childhood FAS.

[Effects of alcohol exposure during pregnancy on dendritic spine and synapse of visual cortex in filial mice].

The prenatal ethanol exposure induced the alterations of dendritic spine and synapse in visual cortex and their long-term effect would be investigated in mice from P0 to P30. Pregnant mice were intubated ethanol daily from E5 through the pup's birth to establish mode of prenatal alcohol abuse. The dendritic spines of pyramidal cells in visual cortex of pups were labeled with DiI diolistic assay, and the synaptic ultrastructure was observed under transmission electron microscope. Prenatal alcohol exposure was associated with a significant decrease in the number of dendritic spines of pyramidal neurons in the visual cortex and an increase in their mean length; ultrastructural changes were also observed, with decreased numbers of synaptic vesicles, narrowing of the synaptic cleft and thickening of the postsynaptic density compared to controls. Prenatal alcohol exposure is associated with long-term changes in dendritic spines and synaptic ultrastructure. The changes were dose-dependent with long term effect even at postnatal 30.

Electrophile-induced cyclization/migration reaction for the synthesis of 2,3-dihydro-5-iodopyran-4-one.

A novel method for the construction of 2,3-dihydro-5-iodopyran-4-one through a domino cyclization/migration reaction of 1-alkynyl-2,3-epoxy alcohol was developed. Wet solvent is essential for this reaction. The resulting iodine-containing product can be readily elaborated to more complex products by using known organopalladium chemistry.