Determination of phenols in soil by supercritical fluid extraction-capillary electrochromatography

A new analytical procedure is developed to couple supercritical fluid extraction with capillary electrochromatography (SFE-CEC) to extract and determine phenols in soil. Ten phenols consisting of phenol, methylphenols (p-cresol and o-cresol), dimethylphenols (3,5-xylenol, 3,4-xylenol and 2,6-xylenol), trimethylphenol, ethylphenols (p-ethylphenol and o-ethylphenol), and o-isopropylphenol are investigated. The use of supercritical CO2 with 10% methanol as the organic modifier was found to give satisfactory extraction of alkylphenols from soil at 1200 p.s.i. and 50 degrees C for 45 min under a total extractant flow-rate of 0.2 ml/min (1 p.s.i.=6894.76 Pa). Baseline resolution was achieved for the 10 selected phenols under optimised CEC conditions at 20 kV in a mobile phase of acetonitrile-4 mM Tris, pH 7.0 (35:65) in a 45 cm (25 cm packed with 3 microm ODS) x 75 microm I.D. fused-silica capillary column. Using SFE with a 10-fold preconcentration factor, all alkyl-substituted phenols in soil can be determined with detection limits ranging from 0.0032 to 0.014 mg/kg and working range from 0.019 to 2.72 mg/kg. The SFE-CEC procedure developed has been applied successfully to determine phenols extracted from real soil sample contaminated with medical disinfectant. It will provide a rapid method for the direct determination of phenol and alkyl-substituted phenol in soils, with capability for confirmation of unknown peaks.     

Molecular design of free volume as a route to low-kappa dielectric materials

Polymers incorporating the triptycene subunit were prepared for the molecular-level design of low dielectric constant (low-kappa) materials that can be used to manufacture faster integrated circuits. Triptycenes having restricted rotation by multiple point attachment to the polymer backbone are shown to introduce free volume into the films, thereby lowering their dielectric constants. The triptycene containing polymers exhibit a number of desirable properties including low-water absorption and high thermal stability. Systematic studies wherein comparisons are made between two separate classes of triptycene polymers and their non-triptycene containing analogues demonstrate that proper insertion of triptycenes into a polymer backbone can give rise to a reduction in the material's dielectric constant while also improving its mechanical properties. These characteristics are desired by the semiconductor industry for the next generation of microprocessors and memory to provide insulation of the increasingly shrinking features.     

Preparation of a Star Network PEG-based Gel Polymer Electrolyte and Its Application to Electrochromic Devices

A star network polymer with a pentaerythritol core linking four PEG-block polymeric arms was synthesized, and its corresponding gel polymer electrolyte based on lithium perchlorate and plasticizers EC/PC with the character being colorless and highly transparent has been also prepared. The polymer host was characterized and confirmed to be of a star network and an amorphous structure by FTIR, ^1H NMR and XRD studies. The polymer host hold good mechanical properties for pentaerythritol cross-linking. Maximum ionic conductivity of the prepared polymer electrolyte has reached 8.83 × 10 ^-4 S·cm^-1 at room temperature. Thermogravimetry （TG） of the polymer electrolyte showed that the thermal stability was up to at least 150 ℃. The gel polymer electrolyte was further evaluated in electrochromic devices fabricated by transparent PET-ITO and electrochromically active viologen derivative films, and its excellent performance promised the usage of the gel polymer electrolyte as ionic conductor material in electrochrornic devices.     

Electrochemical insertion of magnesium ions into V2O5 from aprotic electrolytes with varied water content

The electrochemical performance of V2O5 has been studied in propylene carbonate (PC)-containing magnesium perchlorate [Mg(ClO4)2] electrolytes in view of their application as positive electrode in the rechargeable magnesium batteries. V2O5 exhibited good properties in hosting magnesium ions and its electrochemical performance depended on the amount of H2O in the electrolytes. The highest first discharge specific capacities of V2O5 electrode was up to 158.6 mAh/g in 1 mol dm(-3) Mg(ClO4)2 + 1.79 mol dm(-3) H2O/PC electrolytes. Electrochemical impedance spectroscopy (EIS) and charging-discharging tests showed that a reasonable amount of H2O in the electrolyte solution facilitated the electrochemical performance of V2O5 electrodes.     

Elucidating dominant factors of PO43-, Cd2+ and nitrobenzene removal by biochar: A comparative investigation based on distinguishable biochars

Four distinct biochars were employed to remove three typical pollutants, meanwhile, path analysis, a multi-statistical regression method, was performed to elucidate the dominant factors of biochar adsorption. This work can provide a new insight to prepare a targeted biochar as adsorbents.     

A dinuclear uranium(IV) complex of the chelating ligand 1,2,3,4‐tetra­methyl‐5‐(2‐pyridyl)­cyclo­penta­diene

The ligand 1,2,3,4‐tetra­methyl‐5‐(2‐pyridyl)­cyclo­penta­diene (cp*py) forms a dinuclear complex with U^IV, i.e. di‐μ‐oxo‐bis­{chloro­(diethyl ether‐κO)[(η⁵,κN)‐1,2,3,4‐tetra­methyl‐5‐(2‐pyridyl)­cyclo­penta­dienyl]uranium(IV)}, [U₂Cl₂O₂(C₁₄H₁₆N)₂(C₄H₁₀O)₂], in which cp*py acts as a chelating ligand, being bound to the metal atom by the cyclo­penta­dienyl unit and also by the N atom of the pyridyl ring.     

Syntheses of sulfoxide derivatives in the benzodiazine series. Diazines. Part 37

Syntheses of new sulfinylcinnolines, quinoxalines, quinazolines and phtalazines have been investigated starting from the appropriate halogenobenzodiazine derivatives. The latter were converted in one step to the corresponding sulfanyl benzodiazines which upon oxidation with m-CPBA led to the corresponding sulfoxide derivatives of benzodiazines in moderate to good yields. In parallel to this study, an improved method for the synthesis of 2-methylsulfinylquinoxaline starting from 2-sulfanylquinoxaline is also described and in the quinazoline series a synthetic route has been developed to prepare 2-tert-butyl-5-phenylsulfinylquinazoline with satisfactory yield as well as 2-tert-butyl-5-tert-butylsulfinyl-4(3H)-quinazolinone and 2-tert-butyl-8-tert-butylsulfinyl-4(3H)-quinazolinone.     

PHOTOVOLTATC EFFICIENCIES OF MICROCRYSTALLINE AND ANHYDROUS CHLOROPHYLL a

Abstract— A thin layer of chlorophyll a (around 2000 Å). a p -type organic semiconductor. was sandwiched between two different metals. aluminum and silver. We used the photovoltaic effect in order to study the efficiency of light conversion by the crystalline and anhydrous forms of Chl a . When the photovoltaic cell is illuminated through the semi-transparent aluminum electrode. an action spectrum similar to the visible absorption spectrum of Chl a is obtained. The anhydrous form. always shows a maximum, in the red, at 672 nm and the crystalline one at 746 nm to 738 nm depending on the amount of water vapor present in the measuring area. The light conversion efficiency has been measured at the maximum absorption in the red for both forms of Chl a . For the anhydrous form, we found values as high as 0.036%, which is very significant even compared to 0.21%, the highest value found for the crystalline form. In both cases. the incident light power was approximately 10 μW on the cell. The light conversion efficiency of both forms of Chl a cells was found to depend on a combine effect of the nature of the gas (O₁. N₂. air. Ar. N₂O. SF ₆ , H₂) and the amount of water vapor present in the measuring area. The best conversion efficiency was obtained with O ₂ , or air saturated with water. This combined effect was very large for the crystalline form whereas the anhydrous form was only slightly affected.     

Mammalian cell growth studiedin situ by fourier transform infrared spectroscopy

Fourier transform infrared techniques were used to monitor mammalian cell growth plated on attenuated total reflection (ATR) crystals. Consistently, the growth kinetics plots generated from the obtained spectra demonstrated a sigmoidal curve representing a sequence of slow, rapid, then tapering cell growth which correlated well with non-spectral cell growth determinations. Significant advantages over traditional methods of measuring cell growth kinetics are demonstrated. The technique has promising potential to be used to study events in areas such as toxicology and cell biology.