Estimation of Organic Carbon Normalized Sorption Coefficient (<i>K</i>_OC) for Soils Using the Fragment Constant Method

A fragment constant model for prediction of KOC was developed and evaluated with a diverse database of 592 chemicals belonging to 17 classes. The range of experimental KOC covered 7.65 log-units. The 592 chemicals were randomly divided into a training set and a testing set for model development and validation. A general model was then established using the entire database having 74 fragment constants and 24 structural factors. Statistically, the regression model accounted for as much as 96.96% of the variation in the measured log KOC. The mean residual between the experimental and predicted KOC values was 0.366 log-units. In more than 74% of the chemicals studied the residual values were less than 0.5 log-units. The robustness of the regression model, with respect to either specific individual chemicals or particular compound classes, was evaluated through use of jackknife tests. The experimental results confirmed the ability of the fragment model to predict KOC for a wide variety of untested chemicals

A new Sr(II)-based coordination polymer: structural insight and anti-gastric cancer activity

In this work, a new Sr(II)-based coordination polymer (CP) with the chemical formula of [Sr3(L)2(H2O)4] (1) (H3L = 4'-hydroxy-[1,1'-biphenyl]-3,3',5-tricarboxylic acid) has been successfully prepared by reaction of Sr(NO3)2 with the non-planar tripodal carboxylate ligand H3L in a mixed solvent of DMF and water. Furthermore, an ultrasonic treatment method was used to produce the crystalline samples in nanometer region. After treated with nano complex, the cell proliferation of MKN45 gastric cancer cells was detected by the Cell Counting Kit-8 (CKK-8) assay. In addition to this, the Annexin V-FITC/PI apoptosis detection Kit was performed in flow cytometer to measure the percentage of the apoptotic MKN45 cells after nano complex treatment. Finally, the expression of the apoptotic proteins was detected by western blot.</p

Palladium-Catalyzed Cascade Oxidation/<i>sp</i>² C–H Acylation of Azoarenes with Aryl Methanes

A Pd-catalyzed cascade oxidation/sp2 C–H bond acylation of azoarenes was developed in which readily available aryl methanes were used as the in situ generated acyl sources. This reaction provides a convenient access to ortho-acyl azoarenes under mild conditions

Pd-Catalyzed Tandem Cyclization of Ethyl Glyoxalate and Amines: Rapid Assembly of Highly Substituted Cyclic Dehydro-α-Amino Acid Derivatives

A novel cascade cyclization of ethyl glyoxalate and amines proceeds in the presence of Pd(TFA)₂ (5 mol %) to give the cyclic dehydro-α-amino acid derivatives. This method provides a fast and simple access to highly substituted dihydro-pyrrol-2-ones in good yields

Assessment of Oral Bioaccessibility of Organochlorine Pesticides in Soil Using an In Vitro Gastrointestinal Model

A static in vitro gastrointestinal model was used to investigate the oral bioaccessibility of organochlorine pesticides (OCPs) including hexachlorocyclohexane isomers (HCHs) and dichlorodiphenyltrichloroethane and metabolites in contaminated soils with different organic matter contents. A key hypothesis tested was that a fraction of the mobilized contaminants is sorbed on the solid after digestion, and this fraction could be desorbed and become bioaccessible in the intestinal tract due to absorption of the dissolved fraction by the small intestine. The bioaccessibility would be underestimated if the sorbed fraction was separated from the fluid by centrifugation or filtration in an in vitro test. In our experiment, a procedure using multiple fluid-to-solid ratios was developed to characterize the sorption. It was found that 8−38% of the mobilized OCPs were sorbed on the residue and remained in the solid phase after the separation. Taking into consideration the sorbed fraction, the measured bioaccessibilities of the OCPs varied from 4% to 97% depending on the properties of the soils and the compounds. The enantiomeric ratios of chiral compounds studied were also determined to distinguish biotic (enzymatic) and abiotic (chemical extraction) processes in the in vitro digestion model. It was found that although α-HCH in the raw soils was racemic, (+)-α-HCH was enriched in the gastric digestive fluid but depleted in the intestinal digestive fluid

Pd(II)-Catalyzed Pyridine <i>N</i>‑Oxides Directed Arylation of Unactivated C_sp^₃–H Bonds

A novel Pd­(II)-catalyzed pyridine <i>N</i>-oxide directed remote arylation of unactivated C_sp³–H bonds in aliphatic amides with aryl iodides has been developed. This protocol allows installing various aryl groups at the β- or γ-C_sp³ atom of alkyl carboxylic acid amides. The key palladabicyclic intermediate of this transformation has been identified by HR-MS and ¹H NMR method

Dietary Intake and Human Milk Residues of Hexachlorocyclohexane Isomers in Two Chinese Cities

Residues of hexachlorocyclohexane isomers (HCHs, including α-HCH, β-HCH, γ-HCH, and δ-HCH) in human milk of two populations from Beijing and Shenyang, China were studied. In addition to human milk samples from 76 women, 271 composite food samples covering major food categories were also collected for HCH analysis. The food consumption and social-demographic characteristics of the studied populations were investigated and dietary intakes of HCHs of the milk donors on an individual basis were calculated. The dependences of HCH concentration in the human milk on food consumption, dietary intake of HCHs, and demographic characteristics were studied. It was found that β-HCH dominated the HCHs detected in the human milk. Although there were dramatic declines in HCHs in the human milk compared to historical data, the current levels (312 ± 377 ng/g fat and 360 ± 235 ng/g fat as the means and standard deviations for Beijing and Shenyang, respectively) were still much higher than those reported in other cities within China and around the world. It was revealed that the residual level of HCHs in the human milk was positively correlated (p p p < 0.01) were significantly correlated with human milk HCHs. A nonlinear model was developed to predict the residues of HCHs in human milk using both dietary intake and BMI as independent variables. Potential risk of the HCH exposure of breastfed infants is discussed

Pd(II)-Catalyzed Pyridine <i>N</i>‑Oxides Directed Arylation of Unactivated C_sp^₃–H Bonds

A novel Pd­(II)-catalyzed pyridine <i>N</i>-oxide directed remote arylation of unactivated C_sp³–H bonds in aliphatic amides with aryl iodides has been developed. This protocol allows installing various aryl groups at the β- or γ-C_sp³ atom of alkyl carboxylic acid amides. The key palladabicyclic intermediate of this transformation has been identified by HR-MS and ¹H NMR method

Palladium(II)-Catalyzed Enantioselective Arylation of α‑Imino Esters

A protocol for Pd­(II)-catalyzed asymmetric arylation of <i>N</i>-aryl imino esters has been developed. The method affords a practical and direct access to chiral arylglycine derivatives in good yields and with high enantioselectivities

Ruthenium(II)-Catalyzed Regioselective Reductive Coupling of α‑Imino Esters with Dienes

A method for the highly regioselective reductive coupling reaction of <i>N</i>-aryl-α-imino esters with dienes is described. The method utilizes the RuHCl(CO)(PPh₃)₃/<i>i</i>PrOH catalytic system under an Ar atmosphere and provides α-branched allylic α-amino acid derivatives. Application of this transformation to the concise synthesis of a natural plant growth regulator is demonstrated