Photoelectrochemical and Photovoltaic Properties of p–n Cu₂O Homojunction Films and Their Photocatalytic Performance

The improvement of photoinduced charge separation is the key for light-harvesting systems in both photovoltaic and photoelectrochemical solar cells. In this study, the charge separation efficiency has been modulated through varying the magnitude of interfacial electric field in p–n Cu₂O homojunction films prepared by simple electrodeposition method. The photoelectrochemical and surface photovoltage measurements were used to investigate the behaviors of photoinducded charge carriers in different p–n Cu₂O homojunction films. The results confirmed that the p–n Cu₂O homojunction film which exhibited the highest charge separation efficiency resulted in the highest activity in photocatalytic reduction of methyl viologen. These implied that it is possible to achieve high charge separation efficiency via constructing a large magnitude of interfacial electric field within a semiconductor using a simple electrodeposition method

Self-decontaminating properties of fluorinated copolymers integrated with ciprofloxacin for synergistically inhibiting the growth of <i>Escherichia coli</i>

<div><p>In this paper, copolymers composed of antibacterial monomer containing ciprofloxacin, methyl methacrylate (MMA), and 2-perfluorooctylethyl methacrylate (FMA) were prepared, and the surface properties and antibacterial performance of the copolymers and blends-mixed PMMA were investigated. Surface characterization using dynamic contact angle measurement and X-ray photoelectron spectroscopy showed that anti-adhesive fluorinated moieties and antimicrobial moieties were highly concomitant on the material surface. All the copolymers and blends films exhibited excellent antibacterial properties. It was found that the fluorinated antibacterial copolymers showed significantly enhanced antibacterial efficiency toward <i>Escherichia coli</i> bacterium, and even markedly prevented the formation of biofilm for long term. The PMMA films blended with fluorinated antibacterial polymer also show similar results. In contrast, the common copolymer without fluorinated units cannot effectively resist bacterial adhesion, proliferation, and prevent biofilm formation. The desirable antibacterial polymer prohibiting the biofilm formation performance of copolymer with special push-me/pull-you structure which weaken the interaction among polymer chains resulted in the more easy segregation of ciprofloxacin on surface in real environment by the help of synergistic effect of fluorinated units, potentially enabling the design of new self-decontaminating biomaterials for control biofouling.</p></div

Influences of chilling stress pre-treatments performed with various durations of chilling stress at 16/12°C on occurrence and development of Alternaria disease.

<p>Cotton seedlings were pre-treated with various duration of chilling stress at 16/12°C, then inoculated with <i>A. alternata</i> isolate A1, and removed to grow at optimal temperature of 28/20°C; Different letters behind the disease index indicate significant difference with the <i>P</i> value of 0.05. The first letters indicate the comparison among various duration of chilling stress at 16/12°C and the second letters indicate the comparison between XLZ13 and XLZ33.</p

Changes in chlorophyll contents during Alternaria disease development promoted by chilling stress pre-treatment.

<p>a: the control cotton plants sustained growing at optimal temperature of 28/20°C. b, c, d: Cotton plants performed with chilling stress pre-treatments at 20/16°C, 16/12°C, 12/8°C for 3 days respectively, then inoculated with 1.2×10⁴ conidial/mL inoculum suspension of <i>A. alternata</i> isolate A1, and returned to grow at 28/20°C. All collected data (mean ± standard deviation SD with 6 replicates) were presented as relative values to the chlorophyll contents (SPAD unit) at −3 d (100% chlorophyll content = 41.5 for XLZ13 and 44.0 for XLZ33 leaves, respectively). The chilling stress pre-treatment period was indicated by time points from −3 to 0, and the period after inoculation was indicated by time points from 0 to 15.</p

Effect of Surface Compositional Heterogeneities and Microphase Segregation of Fluorinated Amphiphilic Copolymers on Antifouling Performance

In this paper, a series of fluorinated amphiphilic copolymers composed of 2-perfluorooctylethyl methacrylate (FMA) and 2-hydroxyethyl methacrylate (HEMA) monomers were prepared, and their surface properties and antifouling performance were investigated. Bovine serum albumin (BSA) and human plasma fibrinogen (HFg) were used as model proteins to study protein adsorption onto the fluorinated amphiphilic surfaces. All the fluorinated amphiphilic surfaces exhibit excellent resistant performance of protein adsorption measured by X-ray photoelectron spectroscopy (XPS). The surface compositional heterogeneities on the molecular scale play an important role in the antifouling properties. It was found that the copolymers exhibited better antifouling properties than the corresponding homopolymers did, when the percentage of hydrophilic hydroxyl groups is from 4% to 7% and the percentage of hydrophobic fluorinated moieties is from 4% to 14% on the surface. In addition, the protein molecular size scale and the pattern of microphase segregation domains on the surface strongly affect the protein adsorption behaviors. These results demonstrate the desirable protein-resistant performance from the fluorinated amphiphilic copolymers and provide deeper insight of the effect of surface compositional heterogeneity and microphase segregation on the protein adsorption behaviors

Changes in MDA content during Alternaria disease development promoted by chilling stress pre-treatment.

<p>a: the control cotton plants sustained growing at optimal temperature of 28/20°C. b, c, d: Cotton plants performed with chilling stress pre-treatments at 20/16°C, 16/12°C, 12/8°C for 3 days respectively, then inoculated with 1.2×10⁴ conidial/mL inoculum suspension of <i>A. alternata</i> isolate A1, and returned to grow at 28/20°C. All collected data (mean ± standard deviation SD with 6 replicates) were presented as relative values to the malondialdehyde contents at −3 d (100% MDA content = 22.4 nmol/gFW for XLZ13 and 21.8 nmol/gFW for XLZ33 leaves, respectively). The chilling stress pre-treatment period was indicated by time points from −3 to 0, and the period after inoculation was indicated by time points from 0 to 15.</p

Changes in soluble protein contents during Alternaria disease development promoted by chilling stress pre-treatment.

<p>a: the control cotton plants sustained growing at optimal temperature of 28/20°C. b, c, d: Cotton plants performed with chilling stress pre-treatments at 20/16°C, 16/12°C, 12/8°C for 3 days respectively, then inoculated with 1.2×10⁴ conidial/mL inoculum suspension of <i>A. alternata</i> isolate A1, and returned to grow at 28/20°C. All collected data (mean ± standard deviation SD with 6 replicates) were presented as relative values to the soluble protein content at −3 d (100% soluble protein content = 24.8 mg/gFW for XLZ13 and 27.5 mg/gFW for XLZ33 leaves, respectively). The chilling stress pre-treatment period was indicated by time points from −3 to 0, and the period after inoculation was indicated by time points from 0 to 15.</p

Appearance of Alternaria disease on cotton leaves pre-treated by chilling stress with various low temperatures.

<p>Chilling stress pre-treatments were performed with various low temperatures for 3 days. Then the pre- treated cotton leaves were inoculated with 1.2×10⁴ conidial/mL inoculum suspension of <i>A. alternata</i> isolate A1 by slightly brushing method and returned to grow at optimal temperature of 28/20°C. The mock inoculations were performed with sterilized water. Presented pictures photographed at 15 days after inoculation.</p

Influences of chilling stress pre-treatments performed with various low temperatures on occurrence and development of Alternaria disease.

<p>Cotton seedlings were pre-treated with chilling stress for 3 days, then inoculated with <i>A. alternata</i> isolate A1, and removed to grow at optimal temperature of 28/20°C; Different letters behind the disease index indicate significant difference with the <i>P</i> value of 0.05. The first letters indicate the comparison among different temperatures of chilling stress pre-treatment and the second letters indicate the comparison between XLZ13 and XLZ33.</p

Changes in Fv/Fm ratio during Alternaria disease development promoted by chilling stress pre-treatment.

<p>a: the control cotton plants sustained growing at optimal temperature of 28/20°C. b, c, d: Cotton plants performed with chilling stress pre-treatments at 20/16°C, 16/12°C, 12/8°C for 3 days respectively, then inoculated with 1.2×10⁴ conidial/mL inoculum suspension of <i>A. alternata</i> isolate A1, and returned to grow at 28/20°C. All collected data (mean ± standard deviation SD with 6 replicates) were presented as relative values to the maximal quantum yield of photosystem II photochemistry (Fv/Fm ratio) at −3 d (100% Fv/Fm ratio = 0.805 for XLZ13 and 0.812 for XLZ33 leaves). The chilling stress pre-treatment period was indicated by time points from −3 to 0, and the period after inoculation was indicated by time points from 0 to 15.</p