Impact of water/PDMS phase ratio,volume of PDMS,and sampling time on Stir Bar Sorptive Extraction (SBSE) recovery of some pesticides with different KO/W

In Stir Bar Sorptive Extraction (SBSE) organic analytes are enriched from aqueous samples by sorption onto a thick film of polydimethylsiloxane (PDMS) coated on a glass‐enveloped magnet. Sampled analytes are recovered by thermodesorption (TDS) and analysed on‐line by cGC‐MS. This study evaluates the SBSE recovery as a function of K_O/W, the phase ratio (β), PDMS volume (20, 40, and 110 μL), sample volumes (4, 10, 100, and 1000 mL), and sampling time (0.67, 1, 2, 4, 5, 6, and 24 h) for three pesticides with different K_O/W [parathion methyl (K_O/W: 7.24×10²), β‐endosulfan (K_O/W: 6.8×10³), and buprofezin (K_O/W: 2.0×10⁴)]. Experimental recoveries with SBSE in reasonable sampling times were found to be mainly conditioned by β, which must be as low as possible either by operating on small sample volumes or by using stir bars coated with high PDMS volume when samples of relatively large volume are analysed.     

A constraint linearization method for nondifferentiable convex minimization

Summary This paper presents a readily implementable algorithm for solving constrained minimization problems involving (possibly nonsmooth) convex functions. The constraints are handled as in the successive quadratic approximations methods for smooth problems. An exact penalty function is employed for stepsize selection. A scheme for automatic limitation of penalty growth is given. Global convergence of the algorithm is established, as well as finite termination for piecewise linear problems. Numerical experience is reported.Sponsored by Program CPBP 02.15     

On Khachian's algorithm and minimal ellipsoids

Summary Khachian's algorithm for solving a system of linear inequalities is accelerated by choosing smaller ellipsoids than in the original version. Furthermore, certain inequalities can be successively eliminated, from the constraints, yielding a different stopping rule.     

抽象凸空间上的弱KKM映射, 相交定理和极大极小不等式

In this paper,we introduce the concept of weakly KKM map on an abstract convex space without any topology and linear structure,and obtain Fan＇s matching theorem and intersection theorem under very weak assumptions on abstract convex spaces.Finally,we give several minimax inequality theorems as applications.These results generalize and improve many known results in recent literature.     

Hyperpolarized He diffusion MRI and histology of secreted frizzled related protein-1 (SFRP1) deficient lungs in a Murine model

Secreted frizzled related protein-1 (SFRP1) plays a key role in many diverse processes, including embryogenesis, tissue repair, bone formation, and tumor genesis. Previous studies have shown the effects of the SFRP1 gene on lung development using the SFRP1 knockout mouse model via histological and physiological studies. In this study, the feasibility of ADC (acquired via HP ³He) to detect altered lung structure in the SFRP1 knockout (SFRP1^−/−) mice was investigated, and compared to analysis by histology. This study consisted of two groups, the wild-type (WT) mice and the knockout (KO) mice with n = 6 mice for each group. ³He ADC MRI and histology were performed on all of the animals. The global L_m values of WT and KO mice were 35.0 ± 0.8 μm and 38.4 ± 3.8 μm, respectively, which translated to an increase of 9.58% in the L_m of KO mice. The mean global ADCs for the WT and KO mice were 0.12 ± 0.01 cm²/s and 0.13 ± 0.01 cm²/s, respectively, which equated to a relative increase of 8.0% in the KO mice compared to the WT mice. In the sub-analysis of the anterior, medial and posterior lung regions, L_m increased by 10.50%, 6.66% and 11.84% in the KO mice, respectively, whereas the differences in ADC between the two groups in the anterior, medial, and posterior regions were 7.3%, 8.3%, and 4.6%, respectively. These results suggest that HP MRI measurements can be used as a suitable substitute for histology to obtain valuable information about lung geometry non-invasively. This technique is also advantageous as regional measurements can be performed, which can identify lung destruction more precisely. Most importantly, this approach extends far beyond the specific pathology analyzed in this study, as it can be applied to many other pathological conditions in the lung tissue, as well to many other embryonic studies.