Electrophoretic separation of gold nanoparticles according to bifunctional molecules‐induced charge and size

Gold nanospheres modified with bifunctional molecules have been separated and characterized by using agarose gel electrophoresis as well as optical spectroscopy and electron microscopy. The electrophoretic mobility of a gold nanosphere capped with 11‐mercaptoundecanoic acid (MUA) has been found to depend on the number of MUA molecules per gold nanosphere, indicating that it increases with the surface charge of the nanoparticle. The extinction spectrum of gold nanospheres capped with MUA at an MUA molecules per gold nanosphere value of 1000 and connected via 1,6‐hexanedithiol (HDT) decreases by 33% in magnitude and shifts to the red as largely as 22 nm with the increase of the molar ratio of HDT to MUA (R_HM). Gold nanospheres capped with MUA and connected via HDT have been separated successfully using gel electrophoresis and characterized by measuring reflectance spectra of discrete electrophoretic bands directly in the gel and by monitoring transmission electron microscope images of gold nanoparticles collected from the discrete bands. Electrophoretic mobility has been found to decrease substantially with the increment of HDT to MUA, indicating that the size of aggregated gold nanoparticles increases with the concentration of HDT.     

Recyclable N-heterocyclic carbene/palladium catalyst on graphene oxide for the aqueous-phase Suzuki reaction

Graphene oxide (GO) was functionalized with a N-heterocyclic carbene (NHC) precursor, 3-(3-aminopropyl)-1-methylimidazolium bromide ([APMIm][Br]) for the immobilization of palladium catalyst. The GO-supported NHC precursor (IMGO) formed a stable complex with Pd(OAc)₂ (GO–NHC–Pd), which showed excellent catalytic activity and fast reaction kinetics in the aqueous-phase Suzuki reaction of aryl bromides and chlorides at relatively mild conditions (1 h at 50 °C). The GO–NHC–Pd catalyst was reused several times without any loss of its catalytic activity in the Suzuki reaction of aryl bromide.     

Precise characterization method of antibody‐conjugated magnetic nanoparticles for pathogen detection using stuffer‐free multiplex ligation‐dependent probe amplification

Antibody‐conjugated magnetic nanoparticles (Ab‐MNPs) have potential in pathogen detection because they allow target cells to be easily separated from complex sample matrices. However, the sensitivity and specificity of pathogen capture by Ab‐MNPs generally vary according to the types of MNPs, antibodies, and sample matrices, as well as preparation methods, including immobilization. Therefore, achieving a reproducible analysis utilizing Ab‐MNPs as a pathogen detection method requires accurate characterization of Ab‐MNP capture ability and standardization of all handling processes. In this study, we used high‐resolution CE‐single strand conformational polymorphism coupled with a stuffer‐free multiplex ligation‐dependent probe amplification system to characterize Ab‐MNPs. The capture ability of Ab‐MNPs targeting Salmonella enteritidis and nine pathogens, including S. enteritidis, was analyzed in phosphate buffer and milk. The effect of storage conditions on the stability of Ab‐MNPs was also assessed. The results showed that the stuffer‐free multiplex ligation‐dependent probe amplification system has the potential to serve as a standard characterization method for Ab‐MNPs. Moreover, the precise characterization of Ab‐MNPs facilitated robust pathogen detection in various applications.     

Synthesis of novel 2,4,6,8,10-pentaaza[3.3.3]propellane derivatives

Propellanes and azapropellanes are attractive compounds for their unique structure and valuable applications but there are few synthetic studies for highly N-substituted azapropellanes. Several novel derivatives of 2,4,6,8,10-pentaaza[3.3.3]propellane, such as 3, 4, and 5 were successfully synthesized from readily available diethyl tartrate. Most of the synthetic steps were efficient. Their propellane structures were established by spectroscopic data and confirmed with single crystal X-ray analyses.     

Preparation of 2,2-difluoro-1-trialkylsilylethenylstannanes and their cross-coupling reactions

Reaction of 2 with bis(tributyltin) in the presence of 3 mol % Pd₂(dba)₃, 6 mol % XPhos, and 30 equiv of LiBr in wet and air bubbled THF at reflux for 8 h afforded the desired products 3 in 73–74% yields. The cross-coupling reaction of 3a with aryl iodides in the presence of 10 mol % Pd(PPh₃)₄ and 10 mol % CuI afforded the coupled products 4a–p in 47–90% yields. The coupling reaction of 3b with various alkynyl bromides having aryl-, alkyl, or trialkylsilyl group also afforded the corresponding 1,3-enynes 5a–g in 61–77% yields.     

Efficient Diketopyrrolopyrrole‐Based Small‐Molecule Bulk‐Heterojunction Solar Cells with Different Electron‐Donating End‐Groups

A series of small molecules that contained identical π‐spacers (ethyne), a central diketopyrrolopyrrole (DPP) unit, and different aromatic electron‐donating end‐groups were synthesized and used in organic solar cells (OSCs) to study the effect of electron‐donating groups on the device performance. The three compounds, DPP‐A‐Ph , DPP‐A‐Na , and DPP‐A‐An , possessed intense absorption bands that covered a wide range, from 350 to 750 nm, and relatively low HOMO energy levels, from ?5.50 to ?5.55 eV. DPP‐A‐An , which contained anthracene end‐groups, demonstrated a stronger absorbance and a higher hole mobility than DPP‐A‐Ph , which contained phenyl groups, and DPP‐A‐Na , which contained naphthalene units. The power‐conversion efficiencies (PCEs) of OSCs based on organic:PC₇₁BM blends (1:1, w/w) with a processed DIO additive were 3.93 % for DPP‐A‐An , 3.02 % for DPP‐Na , and 2.26 % for DPP‐A‐Ph . These findings suggest that a DPP core that is functionalized with electron‐donating capping groups constitutes a promising new class of solution‐processable small molecules for OSC applications.     

A study on solidification of CaCO3 powder containing C-14 by using a low melting glass material

Journal of Radioanalytical and Nuclear Chemistry - CaCO3 powder containing C-14, which has a long half-life, is generated from the treatment process of spent activated carbons from the air cleaning...     

Process Development for the Detoxification of Fermentation Inhibitors from Acid Pretreated Microalgae Hydrolysate

The aim of this study was to remove 5-hydroxymethyl furfural (5-HMF) and furfural, known as fermentation inhibitors, in acid pretreated hydrolysates (APH) obtained from Scenedesmus obliquus using activated carbon. Microwave-assisted pretreatment was used to produce APH containing glucose, xylose, and fermentation inhibitors (5-HMF, furfural). The response surface methodology was applied to optimize key detoxification variables such as temperature (16.5–58.5 °C), time (0.5–5.5 h), and solid–liquid (S-L) ratio of activated carbon (0.6–7.4 w/v%). Three variables showed significant effects on the removal of fermentation inhibitors. The optimum detoxification conditions with the maximum removal of fermentation inhibitors and the minimum loss of sugars (glucose and xylose) were as follows: temperature of 36.6 °C, extraction time of 3.86 h, and S-L ratio of 3.3 w/v%. Under these conditions, removal of 5-HMF, furfural, and sugars were 71.6, 83.1, and 2.44%, respectively, which agreed closely with the predicted values. When the APH and detoxified APH were used for ethanol fermentation by S. cerevisiae, the ethanol produced was 38.5% and 84.5% of the theoretical yields, respectively, which confirmed that detoxification using activated carbon was effective in removing fermentation inhibitors and increasing fermentation yield without significant removal of fermentable sugars.     

Isolation of Novel Microalgae from Acid Mine Drainage and Its Potential Application for Biodiesel Production

Microalgae were selected and isolated from acid mine drainage in order to find microalgae species which could be cultivated in low pH condition. In the present investigation, 30 microalgae were isolated from ten locations of acid mine drainage in South Korea. Four microalgae were selected based on their growth rate, morphology, and identified as strains of KGE1, KGE3, KGE4, and KGE7. The dry biomass of microalgae species ranged between 1 and 2 g L^?1 after 21 days of cultivation. The growth kinetics of microalgae was well described by logistic growth model. Among these, KGE7 has the highest biomass production (2.05?±?0.35 g L^?1), lipid productivity (0.82?±?0.14 g L^?1), and C16–C18 fatty acid contents (97.6 %). These results suggest that Scenedesmus sp. KGE 7 can be utilized for biodiesel production based on its high biomass and lipid productivity.     

Visible-Light-Induced ortho-Selective Migration on Pyridyl Ring: Trifluoromethylative Pyridylation of Unactivated Alkenes

The photocatalyzed ortho-selective migration on a pyridyl ring has been achieved for the site-selective trifluoromethylative pyridylation of unactivated alkenes. The overall process is initiated by the selective addition of a CF₃ radical to the alkene to provide a nucleophilic alkyl radical intermediate, which enables an intramolecular endo addition exclusively to the ortho-position of the pyridinium salt. Both secondary and tertiary alkyl radicals are well-suited for addition to the C2-position of pyridinium salts to ultimately provide synthetically valuable C2-fluoroalkyl functionalized pyridines. Moreover, the method was successfully applied to the reaction with P-centered radicals. The utility of this transformation was further demonstrated by the late-stage functionalization of complex bioactive molecules.