Enhancing the Water Splitting Efficiency of Sn‐Doped Hematite Nanoflakes by Flame Annealing

The effect of flame annealing on the water‐splitting properties of Sn decorated hematite (α‐Fe₂O₃) nanoflakes has been investigated. It is shown that flame annealing can yield a considerable enhancement in the maximum photocurrent under AM 1.5 (100 mW cm^?2) conditions compared to classic furnace annealing treatments. Optimizing the annealing time (10 s at 1000 °C) leads to a photocurrent of 1.1 mA cm^?2 at 1.23 V (vs. RHE) with a maximum value 1.6 mA cm^?2 at 1.6 V (vs. RHE) in 1 M KOH. The improvement in photocurrent can be attributed to the fast direct heating that maintains the nanoscale morphology, leads to optimized Sn decoration, and minimizes detrimental substrate effects.     

Cyclodextrin‐Templated Porphyrin Nanorings

α‐ and β‐Cyclodextrins have been used as scaffolds for the synthesis of six‐ and seven‐legged templates by functionalizing every primary CH₂OH with a 4‐pyridyl moiety. Although these templates are flexible, they are very effective for directing the synthesis of macrocyclic porphyrin oligomers consisting of six or seven porphyrin units. The transfer of chirality from the cyclodextrin templates to their nanoring hosts is evident from NMR and circular dichroism spectroscopy. Surprisingly, the mean effective molarity for binding the flexible α‐cyclodextrin‐based template within the six‐porphyrin nanoring (74 M ) is almost as high as for the previously studied rigid hexadentate template (180 M ). The discovery that flexible templates are effective in this system, and the availability of a template with a prime number of binding sites, open up many possibilities for the template‐directed synthesis of larger macrocycles.     

Synthesis of sulfur-bridged piperazinediones by reaction of 3,6-dibromo-1,4-dimethyl-2,5-piperazinedione with geminal dithiols

The reaction of several geminal dithiols with 3,6-dibromo-1,4-dimethyl-2,5-piperazinedione gave in good yields piperazinedione derivatives substituted at the 3,6-position with a geminal dithiol-bridging group. These sulfur-bridged piperazinediones formally represent derivatives of the 2,4-dithia-6,8-diaza-7,9-dioxobicyclo[3.2.2]nonane ring system. Attempts to transform these sulfur-bridged piperazinediones to 3,6-epidithiopiperazinediones by removal of the bridging group common to the sulfur functionality were unsuccessful. Studies also are reported of addition of thioacetic acid to 3,6-dimethylene-2,5-piperazinedione to give 3,6-diacetylthio-3,6-dimethyl-2,5-piperazinedione. Conversion of the 3,6-diacetylthio derivative to the epithiopiperazinedione ring system yielded a mixture of epimono- and epidithiopiperazinediones.     

A chemometric study of active parameters and their interaction effects in a nebulized sheath-liquid electrospray interface for capillary electrophoresis-mass spectrometry

A chemometrics approach has been used for evaluating the effect of four experimental parameters when coupling capillary electrophoresis (CE) to electrospray ionization-mass spectrometry (ESI-MS). Electrospray voltage, sheath-liquid flow rate, nebulizing gas flow rate, and spray needle position in respect to the MS orifice were varied according to a full factorial design. In addition to main effects, two interaction effects could be identified as significant when measuring the peak intensity of the analytes, from a sample mixture containing peptides and pharmaceuticals. The first interaction effects, between the nebulizing gas flow rate and the sheath-liquid flow rate, and the second interaction effect, between the nebulizing gas flow rate and the spray position, could further explain the impact that these variables have on the spray performance. The number of theoretical plates and the baseline noise were also measured. The sheath-liquid flow was found to significantly affect the separation efficiency, while the noise level mainly was controlled by the nebulizing gas flow. The same factorial design was also used for a CE capillary with lower internal diameter (ID) and the effects of the same variables were compared on those capillaries using equal injection volume for both capillaries. Similar trends were obtained in both capillaries but capillary ID was shown to be a significant variable when evaluating both capillaries in a single model. It was found that a capillary with 25 microm ID provided improved CE-MS performance over than corresponding 50 microm ID capillary. Enhanced sensitivity was obtained using the narrow-bore capillary, and at lower sheath-liquid flow rate the 25 microm ID capillary also gave rise to more efficient peaks.     

An analytical and experimental comparison of optimal actuator and error sensor location for vibration attenuation

Feedforward active control of the flexural waves in a single and L-shaped plate has been analytically and experimentally investigated. The plates are simply supported along two parallel edges, and free at the other two ends. Point forces were used to generate the primary and secondary plate excitations. The plate flexural displacement is described by a combination of a travelling wave solution and a modal expansion. The flexural wave coefficients were determined using the boundary conditions, continuity equations at the driving force locations, and continuity equations at the corner junction for the L-shaped plate. The control actuator and error sensor are optimally located in order to achieve the best control performance.     

Targeted drug delivery to chemoresistant cells: folic acid derivatization of FdUMP[10] enhances cytotoxicity toward 5-FU-resistant human colorectal tumor cells

Current chemotherapy protocols that include fluoropyrimidines, such as 5-fluorouracil (5-FU), are limited by the development of chemoresistance during the course of treatment. Our laboratory has developed a novel class of fluoropyrimidines, FdUMP[N], that are oligodeoxynucleotides (ODNs) composed of some number, N, of 5-fluoro-2'-deoxyuridine-5'-O-monphosphate (FdUMP) nucleotides. Novel synthetic procedures are described that permit conjugation of folic acid to the 5'-OH of FdUMP[10] via a phosphodiester linkage using automated synthesis. The synthetic methods developed are generally applicable for ODN conjugation with folic acid. The folic acid conjugate FA-FdUMP[10] showed improved cytotoxicity toward human colorectal tumor cells (H630), and 5-FU-resistant colorectal tumor cells (H630-10). Enhanced cytotoxicity was observed for FA-FdUMP[10] relative to nonconjugated FdUMP[10] for cells grown under folate-restricted conditions, consistent with cellular uptake being, in part, receptor-mediated. Folate receptor alpha (FRalpha) mRNA was shown by RT-PCR to be overexpressed 26.3-fold in 5-FU-resistant H630-10 cells relative to H630 cells. Thus, FA-FdUMP[N] may prove useful for the treatment of 5-FU-resistant malignancies.     

Applications of Fruit Polyphenols and Their Functionalized Nanoparticles Against Foodborne Bacteria: A Mini Review

The ingestion of contaminated water and food is known to cause food illness. Moreover, on assessing the patients suffering from foodborne disease has revealed the role of microbes in such diseases. Concerning which different methods have been developed for protecting food from microbes, the treatment of food with chemicals has been reported to exhibit an unwanted organoleptic effect while also affecting the nutritional value of food. Owing to these challenges, the demand for natural food preservatives has substantially increased. Therefore, the interest of researchers and food industries has shifted towards fruit polyphenols as potent inhibitors of foodborne bacteria. Recently, numerous fruit polyphenols have been acclaimed for their ability to avert toxin production and biofilm formation. Furthermore, various studies have recommended using fruit polyphenols solely or in combination with chemical disinfectants and food preservatives. Currently, different nanoparticles have been synthesized using fruit polyphenols to curb the growth of pathogenic microbes. Hence, this review intends to summarize the current knowledge about fruit polyphenols as antibacterial agents against foodborne pathogens. Additionally, the application of different fruit extracts in synthesizing functionalized nanoparticles has also been discussed.