Impact of inkjet printed ZnO electron transport layer on the characteristics of polymer solar cells

In this paper, we demonstrate that zinc oxide (ZnO) layers deposited by inkjet printing (IJP) can be successfully applied to the low-temperature fabrication of efficient inverted polymer solar cells (i-PSCs). The effects of ZnO layers deposited by IJP as electron transport layer (ETL) on the performance of i-PSCs based on PTB7-Th:PC₇₀BM active layers are investigated. The morphology of the ZnO-IJP layers was analysed by AFM, and compared to that of ZnO layers deposited by different techniques. The study shows that the morphology of the ZnO underlayer has a dramatic effect on the band structure and non-geminate recombination kinetics of the active layer deposited on top of it. Charge carrier and transient photovoltage measurements show that non-geminate recombination is governed by deep trap states in devices made from ZnO-IJP while trapping is less significant for other types of ZnO. The power conversion efficiency of the devices made from ZnO-IJP is mostly limited by their slightly lower J_SC, resulting from non-optimum photon conversion efficiency in the visible part of the solar spectrum. Despite these minor limitations their J–V characteristics compare very favourably with that of devices made from ZnO layer deposited using different techniques.

In this paper, we demonstrate that zinc oxide (ZnO) layers deposited by inkjet printing (IJP) can be successfully applied to the low-temperature fabrication of efficient inverted polymer solar cells (i-PSCs).     

The relevance of mind altering drugs to the counselling process

There has been much discussion about ‘needs-led’ health service provision in recent years. In the UK, this has been driven, in part, by legislative changes designed to make service providers demonstrably more accountable to consumers. Consumer audit (CA), as described in this paper, is a means by which this can be achieved. It involves eliciting the consumer perspective on the delivery and content of services. Once gathered, such data can be used systematically to inform service development. By starting from what consumers feel to be important, CA has the potential to facilitate needs-led services. A model of this process, derived from the authors' CA of a substance misuse service in London, is presented. Some issues and problems associated with CA are discussed.     

Changes of infections due to drug resistant bacteria and its control

The development and use of antibiotics for the chemotherapy of bacterial infections was one of the most remarkable accomplishments in medicine of the 20th. However, antibiotic-resistant bacteria were found in clinical isolates soon after the introduction of the earliest antimicrobial agents into the market. Significant increases in prevalence of resistance to antimicrobial agents have been observed in common pathogens of humans in the worldwide and problems of resistance are still presently serious among the immunocompromised host. The most important of these organisms are methicillin-resistant Staphylococcus aureus penicillin-resistant Streptococcus pneumoniae, vancomycin-resistant Enterococcus, and certain gram-negative bacilli due to extended-spectrum beta-lactamase production. These antibiotic resistances have made antimicrobial therapy of many infections extremely difficult or virtually impossible in some instances. In this article, we reviewed the history of antibiotic-resistance and discussed on the future.     

UV degradation of the interface between perovskites and the electron transport layer

The stability of the perovskite/electron transport layer (ETL) interface is critical for perovskite solar cells due to the presence of ultraviolet (UV) light in the solar spectrum. Herein, we have studied the decomposition process and performance evolution of the perovskite layer in contact with different ETLs under strong ultraviolet irradiation. The normally used SnO₂ layer has lower photocatalytic activity in comparison with the TiO₂ layer, but the perovskite/SnO₂ interface is still severely decomposed along with the formation of hole structures. Such UV light-induced decomposition, on the one hand, leads to the decomposition of the perovskite phase into PbI₂ and more seriously, the formed hole structure significantly limits the carrier injection at the interface owing to the separation of the perovskite active layer from ETLs. Under the same conditions, the perovskite/PCBM interface is very stable and maintains a highly efficient carrier injection. There is no significant efficiency degradation of the encapsulated PCBM-based devices measured outdoors for about three months.

Using SnO₂ as the ETL in perovskite solar cells can degrade the interface and cause device performance degradation under UV light.     

Progress in the synthesis of imide-based N-type polymer semiconductor materials

Based on the development situation and challenge of organic photovoltaics (OPVs) and organic field-effect transistors (OFETs), it is necessary to develop N-type polymer building blocks with specific structures and performance. After decades of development, some excellent polymer receptor building blocks have been developed to construct N-type organic semiconductors, which have been applied in OFETs and OPVs. In this paper, four kinds of imide (bisthiophene imide BTI, bisthiazolimide BTz, naphthalimide NDI, and perylene imide PDI)-based N-type polymer semiconductor materials are introduced, and their applications in OFETs and OPVs are analyzed, too. The molecular structure design and the performance of corresponding materials are summarized to provide further guidance and reference for the design and development of high performance N-type polymer semiconductors.

Representative molecular structures of four N-type polymer semiconductors materials (a: N2000; b: PPDI-DTT, c: TBDI-DT and d: PDTzTIT) based on NDI, PDI, BTI and BTzI, respectively.     

Mechanism of mupirocin transport into sensitive and resistant bacteria.

Pseudomonic acid A (mupirocin) blocks protein synthesis in bacteria by inhibition of bacterial isoleucyl-tRNA synthetase. [16, 17-3H]mupirocin, isolated from a methionine auxotroph of Pseudomonas fluorescens, was used to study transport of this antibiotic into sensitive and resistant strains of Bacillus subtilis, Staphylococcus aureus, and Escherichia coli. The transport of mupirocin into sensitive bacteria was energy independent and temperature dependent (decreased uptake at lower temperatures), indicating non-carrier-mediated passive diffusion. Uptake was also saturable with time or increasing antibiotic concentration. The saturable intracellular binding site, most likely the target isoleucyl-tRNA synthetase as determined by the amount of bound mupirocin (2,700 to 3,100 molecules per cell), caused concentration of the antibiotic within the cell. E. coli transformed with a plasmid containing ileS overproduced the target enzyme and demonstrated greater accumulation of mupirocin than a strain containing a control plasmid. The concentrations needed to half saturate (Kd) these binding sites in B. subtilis and S. aureus were 35 and 7 nM, respectively. In gram-positive organisms trained for mupirocin resistance, uptake was not saturable with increasing antibiotic concentration, and intra- and extracellular concentrations of drug equilibrated with time. Kinetic analysis of crude isoleucyl-tRNA synthetase from trained and untrained B. subtilis strains revealed differences in apparent Ki for mupirocin (resistant strain SB23T, Ki = 71.1 nM; sensitive strain SB23, Ki = 33.5 nM), while the Km for isoleucine remained unchanged (2.7 to 2.9 microM). A Km of 0.4 micromolar isoleucine and Ki of 24 nM mupirocin was demonstrated for isoleucyl-tRNA synthetase from sensitive S. aureus 730a, while no isoleucyl-tRNA synthetase activity was detected in extracts of resistance-trained S. aureus 3000 even at 40 micromolar isoleucine, suggesting instability of the enzyme. Free isoleucine pools differed between sensitive (0.26 micromolar) and resistance-trained (1.06 micromolar) S. aureus. Our results demonstrate that (i) mupirocin enters cells by passive diffusion, (ii) mupirocin concentrates in sensitive bacteria due to binding to isoleucyl-tRNA synthetase, and (iii) resistance to mupirocin involves restricted access to the binding site of isoleucyl-tRNA synthetase.     

Improving charge transport by the ultrathin QDs interlayer in polymer solar cells

Lead sulfide (PbS) quantum dots (QDs) have been incorporated into PTB7:PC₇₁BM BHJ active layers to fabricate polymer solar cells (PSCs) and gather on the top surface of active layers to form an ultrathin interlayer. The PbS QDs ultrathin interlayer with an appropriate thickness increases the carrier transport capacity, exciton dissociation and reduces the carrier recombination, which leads to a higher short circuit current (J_sc) and fill factor (FF). Finally, the power conversion efficiency (PCE) improves from 7.03% (control devices) to 7.87% with an ultrathin interlayer by doping 5% PbS QDs, while the current density (J_sc) and fill factor (FF) enhances from 13.83 mA cm⁻² to 14.81 mA cm⁻² and from 68.70% to 70.85%, respectively.

Lead sulfide (PbS) quantum dots (QDs) have been incorporated into PTB7:PC₇₁BM BHJ active layers to fabricate polymer solar cells (PSCs) and gather on the top surface of active layers to form an ultrathin interlayer.     

Mitochondrial electron transport in models of neuropathic and inflammatory pain

Although peripheral nerve function is strongly dependent on energy stores, the role of the mitochondrial electron transport chain, which drives ATP synthesis, in peripheral pain mechanisms, has not been examined. In models of HIV/AIDS therapy (dideoxycytidine), cancer chemotherapy (vincristine), and diabetes (streptozotocin)-induced neuropathy, inhibitors of mitochondrial electron transport chain complexes I, II, III, IV, and V significantly attenuated neuropathic pain-related behavior in rats. While inhibitors of all five complexes also attenuated tumor necrosis factor alpha-induced hyperalgesia, they had no effect on hyperalgesia induced by prostaglandin E2 and epinephrine. Two competitive inhibitors of ATP-dependent mechanisms, adenosine 5'-(beta,gamma-imido) triphosphate and P1,P4-di(adenosine-5') tetraphosphate, attenuated dideoxycytidine, vincristine, and streptozotocin-induced hyperalgesia. Neither of these inhibitors, however, affected tumor necrosis factor alpha, prostaglandin E2 or epinephrine hyperalgesia. These experiments demonstrate a role of the mitochondrial electron transport chain in neuropathic and some forms of inflammatory pain. The contribution of the mitochondrial electron transport chain in neuropathic pain is ATP dependent.     

Genetic control of alpha-fetoprotein synthesis in the mouse

To approach the genetic mechanism that turns off the synthesis of alpha-fetoprotein (AFP) after birth, we assumed that a change in this mechanism might affect the low basal level of AFP that can be detected in the adult organism. The concentration of AFP was therefore determined for serum from adult mice of 27 different inbred strains. With one exception, this basal level was between 34 and 173 ng/ml, which is about 10(5)-fold less than the serum concentration at birth. In one strain, BALB/c/J, the AFP level was found to be considerably increased; it was about 10-fold higher than in other strains at 9-10 wk of age. Two other substrains of BALF/c mice showed normally low AFP levels. Kinetic studies show that the rate with which AFP disappears from serum after birth is reduced in BALB/c/J mice as compared to other strains. The increased AFP level of BALB/c/J mice appears to be due to an increased rate of synthesis of AFP, since the rate of catabolism of AFP was found to be normal in these mice. Genetic analysis was performed by crossing BALB/c/J mice with mice having an ordinary AFP level, followed by determination of AFP levels in mice of the F1 and F2 generations as well as in back-cross mice. The results clearly indicate that the increased AFP level in BALB/c/J mice is controlled by a single recessive Mendelian gene, which has been named Raf (for regulation of alphafetoprotein). The Raf gene could be directly involved in the regulation of AFP synthesis, but it may also control AFP levels only indirectly, e.g., by regulating the synthesis of a hormone that controls AFP synthesis.     

Intracellular messengers and the control of protein synthesis

The molecular events responsible for controlling cell growth and development, as well as their coordinate interaction is only beginning to be revealed. At the basis of these controlling events are hormones, growth factors and mitogens which, through transmembrane signalling trigger an array of cellular responses, initiated by receptor-associated tyrosine kinases, which in turn either directly or indirectly mediate their effects through serine/threonine protein kinases. Utilizing the obligatory response of activation of protein synthesis in cell growth and development, we describe efforts to work backwards along the regulatory pathway to the receptor, identifying those molecular components involved in modulating the rate of translation. We begin by describing the components and steps of protein synthesis and then discuss in detail the regulatory pathways involved in the mitogenic response of eukaryotic cells and during meiotic maturation of oocytes. Finally we discuss possible future work which will further our understanding of these systems.     

Conductive polymer doped two-dimensional MXene materials: opening the channel of magnesium ion transport

MXene has a series of advantages, such as high specific surface and conductivity, abundant surface functional groups, and effectively accelerating the electron conduction of electrochemically active sites. It is worth noting that due to the van der Waals force between MXene layers, the layers attract each other and the layer spacing becomes smaller, which cannot give full scope to the performance of MXene. Therefore, we introduce a conductive polymer PANI. The purpose of introducing acidified PANI to construct PANI/Ti₃C₂ composites is to make full use of the conductive framework of Ti₃C₂, the abundant functional groups on the surface, and the synergistic effect between the composites, to alleviate the stacking of Ti₃C₂ layers by occupying the active sites on the surface of Ti₃C₂ with PANI. At the same time, the proportion of PANI is changed to 40% of Ti₃C₂, and the composite when used as the cathode of magnesium ion batteries shows a mass-specific capacity of 132.2 mA h g⁻¹ and a series of excellent electrochemical properties at 50 mA g⁻¹ current. This provides a new design idea for the subsequent development of high-performance magnesium storage cathode materials.

A simple preparation method is used to obtain two-dimensional MXene material doped with a conductive polymer, which is used as cathode material of magnesium ion batteries to open the transmission channel of magnesium ions.     

Escape mechanism of intracellular parasitic bacteria and prospect of new approach to infection control

Intracellular parasitic bacteria are capable of escaping from the intracellular killing inside macrophages by virtue of highly sophisticated molecular mechanism. Because of the escape from phagocytic defense, infection caused by these bacteria is difficult to be controlled even in the presence of normal host defense system. In order to understand the mechanism of intracellular parasitism of particular types of bacteria, the basic mechanism of intracellular killing inside phagocyte and the strategy of escape by some representative intracellular bacteria are reviewed. Based on the mechanism of T-cell dependent protective immunity, some possible approaches to the infection by intracellular bacteria, especially to tuberculosis, have been discussed.     

细菌耐药现状与耐药细菌的预防控制策略

根据2010年我国细菌耐药性监测数据,了解和掌握目前细菌耐药的现状,借鉴国际指南中的耐药菌防控措施,提出耐药菌预防控制策略.监测数据显示我国细菌耐药性仍呈增长趋势,已对临床抗感染治疗带来极大的困难,对患者安全构成严重威胁.加强细菌耐药性监测、减少抗菌药物的使用强度、加强病原学检查、改善抗菌药物的使用、严格执行手卫生和消毒隔离制度是耐药菌预防和控制的重点.     

Effects of altering dosing on cationic liposome-mediated gene transfer to the respiratory epithelium.

Liposome-mediated gene transfer is currently sub-optimal with respect to both the extent and duration of transgene expression. We investigated whether simple changes in DNA dosing could enhance either of these outcomes. Increasing DNA doses produced highest transgene expression at an intermediate dose with toxicity observed at higher doses, thereby likely limiting expression. Adminis- tering an equivalent DNA dose in aliquots over a 1-3 day period resulted in significantly lower gene expression and did not increase the duration of expression. Administration at different times of the day (and hence wake/sleep cycles of the animals) did not alter gene expression. We conclude that such simple changes in dosing regimes are unlikely to contribute to improvements in gene transfer efficiency.     

Application of dynamic laser scattering to the quality control of injectable drugs: polymer formation in ampicillin solution

OBJECTIVE: To assess the usefulness of dynamic laser scattering for monitoring the stability of ampicillin after reconstitution from commercially available vials with respect to the polymer formation and potency. METHODS: Polymer formation and the remaining potency of the reconstituted ampicillin solution were estimated using dynamic laser scattering and high-performance liquid chromatography. RESULTS: The laser light-scattering submicron particle analyser was sufficiently sensitive for detecting both monomer and polymer aggregates with the average diameter of 1.1 +/- 0.2 and 7.3 +/- 1.7 nm, respectively, in the ampicillin solution. Polymer formation was dependent on both the storage temperature and the storage period, but it was detected, even when no precipitates were visible and when loss of potency was less than 10% of the initial value following storage at 4 or -15 degrees C. CONCLUSION: Submicron particle analysis using scanning electron microscopy, when used in combination with high-performance liquid chromatography, provides a useful method for studying polymer formation in antibiotic solutions and for the quality control of antibiotic injections during storage.     

Acetone-derived luminescent polymer dots: a facile and low-cost synthesis leads to remarkable photophysical properties

Carbon-based dots have been attracting much attention as potentially superior alternatives to more conventional semiconductor nanoparticles, due to their fascinating optical properties, chemical and photochemical stability, unique environmental-friendliness, and the versatility of fabrication routes. Many commercial materials and organic compounds have been considered so far as carbon precursors but in many cases the fabrication required high-temperature conditions or led to inhomogeneous final products. Here we report on a simple low-cost synthesis of non-conjugated carbon-rich polymer dots (PDs) that uses acetone as carbon precursor. Both hydrophilic and hydrophobic fractions of PDs were obtained, with the respective average diameters of 2–4 nm and ca. 6 nm. The as-obtained PDs reveal greenish-blue photoluminescence (PL) and high quantum yields (∼5–7%) and complex kinetics of the decays with the average lifetime of ∼3.5 ns. Such luminescent acetone-derived PDs may find application in several fields, including sensing and bioimaging.

Acetone-derived polymer dots (PDs) have been fabricated, according to a base-mediated synthesis route at room temperature. As-obtained hydrophobic and hydrophilic PDs revealed a strong greenish-blue emission due to the crosslink-enhanced effect.     

Enhancing the performance of blue quantum-dot light-emitting diodes through the incorporation of polyethylene glycol to passivate ZnO as an electron transport layer

The balance between charge transport and charge injection is always a key factor in enhancing the performance of quantum-dot light-emitting diodes (QD-LEDs), particularly for the blue QDs due to their large optical band gap and relatively low valence band level compared with their green and red counterparts. High performance blue QD-LEDs have been demonstrated by blending polyethylene glycol (PEG) into solution-processed ZnO nanocrystals as the electron transport layer. PEG can effectively tune the electron mobility of ZnO and simultaneously passivate its surface defect states. As a result, the maximum current efficiency (CE) and external quantum efficiency (EQE) of the blue QD-LEDs increased from 4.33 cd A⁻¹ and 9.98% for pure ZnO to 8.03 cd A⁻¹ and 14.84% for 4% PEG blended into ZnO, respectively. Furthermore, operational lifetime of the device is also significantly improved from 8.95 h to 25.06 h. This result indicates that PEG is a promising material for regulating the charge balance of the blue QD-LEDs.

Highly efficient blue quantum-dot light-emitting diodes have been realized by blending PEG into ZnO nanoparticles as an electron transport layer due to regulating charge balance and passivating the surface defect states of ZnO nanoparticles.