Synthesis and Biological Activity of New Chiral N‐Acylsulfonamide Bis‐oxazolidin‐2‐ones

A new series of chiral 5‐substituted bis‐oxazolidinones containing an acylsulfonamide moiety has been synthesized starting from chlorosulfonyl isocyanate, (l )‐ethyl lactate, and oxazolidin‐2‐ones. All the reactions were conducted at ambient temperature, and the N‐acylsulfonamide bis‐oxazolidin‐2‐ones were obtained with high yields within 2 h. Some of the newly synthesized compounds were evaluated in vitro against the virulent strain RH of Toxoplasma gondii and the human lymphocytes, and showed promising results.     

Efficient broadband silicon-on-insulator grating coupler with low backreflection

We design and fabricate an efficient broadband grating coupler on a 400 nm thick silicon-on-insulator wafer. The measured coupling loss is 3 dB when coupling to a single-mode fiber at 1310 nm wavelength with TE polarization. The spectral FWHM and backreflection are determined to be 58 nm and -27 dB, respectively.     

Minimal time of controllability of two parabolic equations with disjoint control and coupling domains

We consider two parabolic equations coupled by a matrix A(x)=q(x)A₀$A(x)=q(x)A_0$, where A₀$A_0$ is a Jordan block of order 1, and controlled by a single localized function, or by a single boundary control. The support of the coupling coefficient, q  , and the control domain may be disjoint. We exhibit an explicit minimal time of null-controllability, T₀(q)∈[0,+∞]$T_0(q)\in [0,+\infty ]$.     

On the sharpness of Bruen’s bound for intersection sets in Desarguesian affine spaces

In this note we investigate the sharpness of Bruen’s bound on the size of a t-fold blocking set in \(AG(n,q)\) with respect to the hyperplanes. We give a construction for t-fold blocking sets meeting Bruen’s bound with \(t=q-n+2\) . This construction is used further to find the minimal size of a t-fold affine blocking set with \(t=q-n+1\) . We prove that for blocking sets in the geometries \(AG(n,2)\) the difference between the size of an optimal t-fold blocking set and tn exceeds any given number. In particular, we deviate infinitely from Bruen’s bound as n goes to infinity. We conclude with a construction that gives t-fold blocking sets with \(t=q-n+3\) whose size is close to the lower bounds known so far.     

Carleman estimates for stratified media

We consider anisotropic elliptic and parabolic operators in a bounded stratified media in Rn characterized by discontinuities of the coefficients in one direction. The surfaces of discontinuities cross the boundary of the domain. We prove Carleman estimates for these operators with an arbitrary observation region.     

Interpolymer Complexes of Poly(N,N-Dimethylacrylamide/Poly(Styrene-co-Acrylic Acid): Thermal Stability and FTIR Analysis

Summary: This contribution will focus on the elaboration and characterizations of new materials with optimal properties as interpolymer complexes, upon mixing poly (styrene-co-acrylic acid containing 18, 27 and 32 mol % of acrylic acid (SAA-x) and poly (N,N-dimethylacrylamide) (PDMA), through the control of the densities, strength, self-association and accessibility of the interacting species. These elaborated interpolymer complexes, of different structures, investigated by DSC and TGA, exhibited a significant improved thermal stability. Their DSC analysis showed that all these materials showed one composition-dependence glass transition temperature Tg, indicating the formation of a single homogeneous phase. The different behaviors of Tg-initial composition observed with these systems were analyzed by the approaches of Kwei and Brostow et al., recently developed. The specific interactions that occurred within the elaborated materials were evidenced qualitatively by ATR/FTIR spectroscopy, from the appearance of new bands in the 1800–1550 cm⁻¹ region.     

Chemical composition and antioxidant activity of aerial parts of Ferula longipes Coss. ex Bonnier and Maury

This is the first study on the phytochemistry and antioxidant activity of Ferula longipes Coss. ex Bonnier and Maury (Apiaceae). A new flavonoid quercetin-3-O-α-L-rhamnopyranoside-7-O-ß-D-[2-O-caffeoyl]-glucopyranoside (1), along with 10 known compounds kaempferol-3-O-α-L-rhamnopyranoside (2), quercetin-3-O-α-L-rhamnopyranoside (3), kaempferol-3-O-ß-D-glucopyranoside-7-O-α-L-rhamnopyranoside (4), isorhamnetin-3-O-α-L-rhamnopyranoside-7-O-ß-D-glucopyranoside (5), quercetin-3-O-α-L-rhamnopyranoside-7-O-ß-D-glucopyranoside (6), isorhamnetin-3,7-di-O-β-D-glucopyranoside (7), apigenin (8), apigenin-7-O-ß-D-glucopyranoside (9), 3,5-dicaffeoylquinic acid (10), deltoin (11) were isolated from the aerial parts of Ferula longipes Coss. Structures elucidation was performed by comprehensive 1D and 2D NMR analyses, mass spectrometry and by comparison with literature data. The compounds 1, 3, 4, 6, 7 and 10 were evaluated for their antioxidant activity, compound 1 exhibited the best antiradical activity potential and showed IC₅₀ and A_0.5 values 5.70, 7.25, 5.00, and 2.63 μg/mL towards DPPH free radical-scavenging, ABTS, CUPRAC, and reducing power assays, respectively compared with BHA, BHT and ascorbic acid which were used as positive controls.     

Chemical synthesis and molecular recognition of phosphatase-resistant analogues of phosphatidylinositol-3-phosphate

The remodeling of phosphatidylinositol polyphosphates in cellular membranes by phosphatases and kinases orchestrates the signaling by these lipids in space and time. To provide chemical tools to study the changes in cell physiology mediated by these lipids, three new metabolically stabilized (ms) analogues of phosphatidylinositol-3-phosphate (PtdIns(3)P) were synthesized. We describe herein the total asymmetric synthesis of 3-methylphosphonate, 3-(monofluoromethyl)phosphonate and 3-phosphorothioate analogues of PtdIns(3)P. From differentially protected D-myo-inositol key intermediates, a versatile phosphoramidite reagent was employed in the synthesis of PtdIns(3)P analogues with diacylglyceryl moieties containing dioleoyl, dipalmitoyl, and dibutyryl chains. In addition, we introduce a new phosphorylation reagent, (monofluoromethyl)phosphonyl chloride, which has general applications for the preparation of "pKa-matched" monofluorophosphonates. These ms-PtdIns(3)P analogues exhibited reduced binding activities with 15N-labeled FYVE and PX domains, as significant 1H and 15N chemical shift changes in the FYVE domain were induced by titrating ms-PtdIns(3)P analogues into membrane-mimetic dodecylphosphocholine micelles. In addition, the PtdIns(3)P analogues with dioleoyl and dipalmitoyl chains were substrates for the 5-kinase enzyme PIKfyve; the corresponding phosphorylated ms-PI(3,5)P2 products were detected by radio-TLC analysis.