Search

In this contribution, we developed a simple, scalable, and universal strategy to exfoliate conjugated porous polymers (CPPs) into 2D nanosheets. A series of pyrenyl (Py)-, benzene (B)-, thienyl (T)-, thieno[3,2-b]thiophene (Tt)- and dithieno[3,2-b:2′,3′-d]thiophene (Ttt)-based CPPs were facilely exfoliated into 2D ultrathin sheets with a thickness of 5–18 nm in reasonable yields of 6–20% upon sonication in N-methyl pyrrolidone. Owing to more exposed active sites and shorter migration distances of charge carriers, the photocatalytic hydrogen production rate of the CPP 2-D nanosheets is 1.5–20 times higher than those of their bulk counterparts. The current study represents the first systematic report on the solvent-assisted exfoliation of CPP materials to produce 2D ultrathin lamellae from bulk CPPs with common structures, which might provide new possibilities for the practical application of 2D CPPs.

How to prompt higher photocatalytic hydrogen production (PHP) efficiency from water to achieve practical applications still remains a big challenge with conjugated porous polymers (CPP)-based photocatalysts. Herein, we developed a simple and efficient cosolvent-assisted strategy to significantly improve the photocatalytic efficiency of CPP-based photocatalysts by introducing water-soluble aprotic bipolar co-solvents, including N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), and N-methyl pyrrolidone (NMP). The PHP activity of the pyrene–bithiophene-based CPP (named CP-St) using ascorbic acid (AA) as a sacrificial electron donor could be excellently accelerated in the presence of an aprotic bipolar NMP solvent. CP-St dispersed in an NMP/H2O/AA mixed solution under visible-light (λ > 420 nm) irradiation without the aid of a Pt cocatalyst achieved an unprecedented hydrogen evolution rate (HER) of 190.7 mmol h−1 g−1. As a result, 6 mg CP-St amazingly produced 128.1 mL H2 (∼5.72 mmol) under visible-light irradiation for only 5 h. Excitingly, by introducing 0.5 wt% Pt cocatalyst into the NMP/H2O/AA system, the HER of CP-St could be further boosted to 303.7 mmol h−1 g−1 (1.82 mmol h−1/6 mg), which represents the highest photocatalytic HER ever reported. This outstanding photocatalytic performance is mainly ascribed to the enhanced dispersity, strong hydrogen-bond interactions, and exfoliation effect by the NMP solvent. This study provides us with some new design ideas and opportunities for effectively catering to the actual hydrogen production demand.

A series of four conjugated porous polymer CPPs (CPs1–4) with various geometries have all been readily synthesized via direct C–H arylation between bithiophene (BT) and 1,3,6,8-tetrabromopyrene (TBPy), 2,2′,7,7′-tetrabromo-9,9′-spirofluorene (TBSF), 1,3,5-tribromobenzene (TBB) and 1,4-dibromobenzene (DB) respectively. The photocatalytic hydrogen evolution from water splitting by these CPPs under visible light irradiation is studied in detail. An amazing hydrogen evolution rate (HER) of 95.85 μmol h−1 was successfully achieved by the four-directional Py-BT-based CPP (CP1, 6 mg), using ascorbic acid (AA) and N,N-dimethylformamide (DMF)/water as a sacrificial agent and co-solvents respectively. Such a HER value is 8-fold higher than that of applying commonly used MeOH/water as a co-solvent in the same photocatalytic system. Significantly, when a 0.5 wt% platinum (Pt) co-catalyst was added into the above photocatalytic system, an unprecedented HER of 184.86 μmol h−1 (6 mg) was further realized. The combination of atom-economically synthesized CPPs and accelerating the HER by means of simply tuning the composition of co-solvents provided herein represents a promising step toward accessing green energy by green chemistry.

New client acceptance decisions are critical for auditors. Audit quality can be negatively affected by limited knowledge of the new client's operations and finances. This may be mitigated for auditors with industry specialization. We examine whether new clientele negatively affect audit quality at the individual level and how the association with audit quality varies across auditors with different levels of industry specialization. Our study fills a gap in the literature by directly addressing the effects of new clients on audit quality for specialist and non-specialist auditors, as well as portfolio-concentration experts, and sheds light on the nature of risks associated with new client acceptance decisions. We find both industry specialists and portfolio-concentration experts can maintain their audit quality when accepting new clients, while there is a decline in quality for auditors who are neither industry specialists nor portfolio-concentration experts.

Prior empirical auditing research has typically used linear regression analysis to analyze auditor relationships. However, because audit firms, audit partners, and audit clients are nested and clustered, data on them lacks independence, and violates the assumptions necessary for valid tests using simple linear regressions. This deficiency can be overcome by employing the hierarchical linear modeling (HLM) technique to conduct empirical tests. We illustrate this by employing HLM to explain the relationship between audit quality and audit firm, and audit partner tenure. We show that employing HLM yields different results than those found using ordinary least squares.

In order to delineate target region for magnetic resonance image (MRI) with diseases, the classical multifractal spectrum (MFS)-segmentation method and latest multifractal detrended fluctuation spectrum (MF-DFS)-based segmentation method are employed in our study. One of our main conclusions from experiments is that both of the two multifractal-based methods are workable for handling MRIs. The best result is obtained by MF-DFS-based method using Lh10 as local characteristic. The anti-noises experiments also suppot the conclusion. This interest finding shows that the features can be better represented by the strong fluctuations instead of the weak fluctuations for the MRIs. By comparing the multifractal nature between lesion and non-lesion area on the basis of the segmentation results, an interest finding is that the gray value's fluctuation in lesion area is much severer than that in non-lesion area.

Affiliated business groups play important roles in markets, especially emerging markets. Both International Auditing and Assurance Standards Board (IAASB) and Public Company Accounting Oversight Board (PCAOB) have expressed strong concerns about the audit quality of group financial statements. Audit quality is closely related with auditor independence (Tepalagul & Lin, 2015). In this study, we examine whether audit partners are more likely to compromise their independence for clients affiliated with consolidated business groups. We incorporate the impact of business group in the construction of client importance proxy in order to explore the potential impact of clientele's business group affiliation. Our findings support that there is no evidence on Big N audit partners compromising their independence for economically important clients no matter whether the clients are affiliated or not. However, we find that the previously documented relation between client importance and audit partner independence in non-Big N audit partners rests with business-group-affiliated and unlisted clients. Therefore, we conclude that non-Big N audit partners tend to compromise their independence for economically important clients who are within affiliated business groups and not listed in stock exchanges.

Background: Sublingual immunotherapy (SLIT) is a clinically effective treatment in allergic conjunctivitis (AC); however, the mechanism of the underlying pharmacodynamics remains unclear. Here, we investigate the efficacy and the mechanism of a sublingually administered Dermatophagoides farinae (Der f) vaccine in a murine AC model. Methods: A murine model of AC caused by Der f extract was developed in BALB/c mice by repeated application of allergen. Sensitized mice were SLIT treated by Der f drops and subsequently analyzed for AC symptoms, histopathological and immunological parameters. Results: In this study, Der f extract successfully induced the symptoms of AC in BALB/c mice. In these sensitized mice, clinical symptoms (scratching behavior, lacrimation, conjunctival hyperemia and edema), immunological and histopathological findings (inflammatory cell infiltration) were very similar to those in human AC. SLIT treatment of sensitized mice markedly reduced the clinical and histopathological symptoms and decreased the expression levels of total immunoglobulin E (IgE), Der f-specific IgE and T helper cell 2 (Th2) cytokine interleukin-4, with a significant increase in Der f-specific IgG4 and Th1 cytokine interferon-γ. Conclusions: SLIT with Der f drops is a potentially effective means of immunotherapy for Der f-induced AC by modulating the Th2-biased allergic immune response.

The purpose of this study is to examine the association of managerial incentives and political costs with hospital financial distress, recovery or closure. The Medicare Payment Advisory Commission has stated that hospital closures are important for evaluating the distribution of cost, quality and access to healthcare throughout the US. Using Logistic regression, we demonstrate that hospital closure is associated with low occupancy, return on investment, asset turnover, and lack of affiliation with a multihospital system. It is also significantly associated with urban location, teaching programs, high Medicare and Medicaid patient populations, and high debt. Essential access nonprofit hospitals are less likely to close, while this does not affect governmental and for-profit hospitals. Our research hypotheses are supported by these results.

SUMMARY: Regulators and legislators have focused significant attention on financial statement restatements in recent years, and the U.S. Securities and Exchange Commission (SEC) and financial statement users view restatements as audit failures. The SEC (2000, 2003a) suggests that shareholder voting on auditor ratification will be impacted by perceptions of audit quality. In this paper we examine shareholder voting on auditor ratifications in 2005 or 2006 following restatement announcements by SEC registrants. We find that shareholders are more likely to vote against auditor ratification after a restatement when compared with votes at (1) firms without restatements or (2) restating firms in the preceding period. Overall, the results provide empirical support to the SEC's assertion that shareholder voting on auditor ratification will be related to perceptions of audit quality, and also support recent actions by shareholder activists to require all firms to submit the selection of the auditor for a ratification vote by shareholders.

The composition of coal-derived light oil (IBP-220 °C) was separated into 5 fractions by atmospheric distillation and analyzed by gas chromatography/mass spectrometry (GC/MS). The light oil was made at 0.1 t/d coal direct liquefaction bench scale unit (BSU) at China Coal Research Institute (CCRI). Six groups of organics, including acyclic hydrocarbon, alicyclic hydrocarbon, aromatics, phenols, polynuclear aromatics and heterocyclics, were found and 80 compounds were tentatively identified in total. Alicyclic hydrocarbon is the main component of the light oil compared to other groups whether in relative mass percentage or the number of compounds in group. The predominant oxygen-contained compound is phenols, and the nitrogen-containing compound is pyridine. No sulfur-containing compound is detected.

Casterella, Francis, Lewis, and Walker (CFLW 2004) find, using survey data from 1993, that (1) there is a Big 6 industry specialization audit fee premium in the small client segment of the U.S. audit market, but (2) audit fees decrease for large companies as the client becomes increasingly large relative to an auditor's clientele. In this study, we first replicate and confirm the results of CFLW (2004), using audit fee data from SEC filings for fiscal 2000 and 2001. In the post-SOX period, we find that the results related to specialization continue to hold in fiscal 2004 but not in 2003—suggesting that 2003 is perhaps a unique year due to the flux in the audit market following the enactment of SOX. With respect to client bargaining power, our results in the post-SOX period differ from CFLW (2004) in that we observe a negative association between client bargaining power and audit fees for both the small and large client segments.

The aim of this study was to compare the roles of dihydropyridine calcium antagonists nifedipine, nitrendipine, amlodipine on doxorubicin (DXR)-induced nephrotoxicity in rats using biochemical, histopathological and immunohistochemical approaches. Male Sprague-Dawley rats were randomly divided into five experimental groups: control; DXR; DXR+nifedipine (15 mg/kg); DXR+nitrendipine (10 mg/kg); DXR+amlodipine (5 mg/kg). Results showed that treatment with DXR alone caused significant changes in the levels of urinary protein, serum creatinine (SCr), and blood urea nitrogen (BUN). Co-administration with amlodipine effectively reversed the effect of DXR on these parameters. In contrast, nifedipine and nitrendipine either had no effect or worsened DXR induced changes in the levels of urinary protein, SCr and BUN. Furthermore, DXR treatment caused significant increases in the levels of malondialdehyde (MDA), nitric oxide (NO), nitric oxide synthase (NOS) and significant decreases in the levels of reduced glutathione (GSH), glutathione-S-transferase (GST), and superoxide dismutase (SOD). These effects were significantly reduced by co-administration with amlodipine but not affected by nifedipine and worsened by nitrendipine. In addition to the biochemical changes, histopathological studies showed that DXR caused significant structural damages in the kidneys. Glomerular cell apoptosis, a decrease in Bcl-2 expression and an increase in Bax expression were observed in all rats treated with DXR. Co-administration with amlodipine effectively reversed the effect of DXR while nifedipine and nitrendipine had no effect. In conclusion, this study clearly indicated that amlodipine protected against DXR-induced nephrotoxicity while nifedipine and nitrendipine had no effect.

Due to the market turbulence facing the hospital industry, the financial viability of teaching hospitals has been severely threatened. Their missions of education, research, and patient care even strengthen this crisis. Therefore, the objective of this study is to conduct a comparative analysis of the cost, volume, and profit (CVP) structure between large nonprofit urban teaching hospitals and small for-profit rural/suburban non-teaching hospitals. The following two hypotheses were developed: (1) large nonprofit urban teaching hospitals tend to have higher fixed cost, lower variable cost, lower total revenue adjusted by case mix index (CMI), and lower return on total assets (ROA); and (2) small for-profit rural/suburban non-teaching hospitals tend to have lower fixed cost, higher variable cost, higher total revenue adjusted by CMI, and higher ROA. Using 117 teaching hospitals and 102 non-teaching hospitals selected from the Medicare Cost Report database in 2005, the results from multiple regression indicated that large nonprofit teaching hospitals located in urban areas are more likely to have higher fixed cost and lower variable cost. While such cost structure doesn't necessarily affect their total revenue adjusted by CMI, it does lead to a lower return on hospitals' total assets. The results support our hypotheses in terms of fixed cost percentage, variable cost percentage, and ROA, but not total revenue adjusted by CMI. The results suggest that cost structure is significantly associated with hospitals' performance. Also, as teaching hospitals' portfolios of services and programs increase (e.g., provision of uncompensated care to Medicare and Medicaid patients and doing research), it becomes strategically necessary and critical to manage the allocation of resources or investments into the fixed capital that supports the business.

Sublingual immunotherapy (SLIT) is a clinically effective treatment in allergic conjunctivitis (AC); however, the mechanism of the underlying pharmacodynamics remains unclear. Here, we investigate the efficacy and the mechanism of a sublingually administered Dermatophagoides farinae (Der f) vaccine in a murine AC model.A murine model of AC caused by Der f extract was developed in BALB/c mice by repeated application of allergen. Sensitized mice were SLIT treated by Der f drops and subsequently analyzed for AC symptoms, histopathological and immunological parameters.In this study, Der f extract successfully induced the symptoms of AC in BALB/c mice. In these sensitized mice, clinical symptoms (scratching behavior, lacrimation, conjunctival hyperemia and edema), immunological and histopathological findings (inflammatory cell infiltration) were very similar to those in human AC. SLIT treatment of sensitized mice markedly reduced the clinical and histopathological symptoms and decreased the expression levels of total immunoglobulin E (IgE), Der f-specific IgE and T helper cell 2 (Th2) cytokine interleukin-4, with a significant increase in Der f-specific IgG4 and Th1 cytokine interferon-γ.SLIT with Der f drops is a potentially effective means of immunotherapy for Der f-induced AC by modulating the Th2-biased allergic immune response.

Through analyzing the process of tunnel construction using the finite element method, the authors conclude the regularization of ground surface movement, and take a contrastive analysis with the analysis result of ground surface movement and deformation by using the stochastic medium theory. The research shows that stochastic medium theory is adopted to predict the ground surface movement and deformation of crushed surrounding rock tunnel; the value of subsidence on the tunnel axis is maximal, and far away from the axis direction the value of subsidence decreases; the ground surface horizontal displacement on the cross section of mountain tunnel increases with the increase of distance from the central axis of tunnel, the value arrives the maximum at the point of inflection, after that decreases; when the mountain tunnel depth increases, the area of influence of ground surface movement and deformation enlarges and the strength of influence weakens. The actual ground surface movement of this tunnel by monitoring proves the reliability of this research.