Palladium-catalyzed disilylation of ortho-halophenylethylenes enabled by 2-pyridone ligand.

A palladium-catalyzed disilylation reaction applicable for a variety of non-, α-, or ß-substituted and α,ß-disubstituted ortho-halophenylethylenes has been developed. This reaction proceeds with high yields and very low catalyst loadings. The two C-Si bonds of the disilylated products could be well-differentiated chemoselectively in the reaction with various electrophiles.

Palladium-catalyzed cross-coupling of unreactive C(sp3)-H bonds with azole C(sp2)-H bonds by using bromide as a traceless directing group.

A palladium-catalyzed intermolecular cross-coupling of unreactive C(sp3)-H bonds and azole C(sp2)-H bonds with bromide as a traceless directing group is described. The judicious selection of the bulky and electron-rich phosphine ligand is the key for the success of this cascade process. The protocol features a broad substrate scope, excellent regioselectivity, and good functional group tolerance.

Phosphorylation of C(sp3)-H Bonds via 1,4-Palladium Migration.

1,4-Palladium migration has emerged as a reliable method for directed C-H functionalization. In contrast to coupling with carbon nucleophiles, limited examples with heteroatom nucleophiles have been reported. Herein we report a palladium-catalyzed intermolecular C(sp3)-H phosphorylation reaction via 1,4-palladium migration, which is often difficult because of the strong coordination of phosphorus reagents to palladium catalysts. Phosphorylation of C(sp3)-H bonds is accomplished in good reaction yields with excellent regioselectivity. The judicious selection of the phosphine ligand proved to be the key to the success of this cascade process.

Bacteria-Anchoring Hybrid Liposome Capable of Absorbing Multiple Toxins for Antivirulence Therapy of Escherichia coli Infection.

Antivirulence therapy by cell membrane coated nanoparticles has shown promise against bacterial infections. However, current approaches remain unsatisfactory when facing Escherichia coli (E. coli) infections, since the E. coli secretes multiple bacterial toxins including endotoxins and exotoxins that are challenging to eliminate simultaneously. What is worse, the absorptive scavengers normally rely on random contact of the diffuse toxins, which is not efficient. For the current cell membrane coated platform, the single type of cell membrane cannot fully meet the detoxing requirement facing multiple toxins. To address these problems, a polymyxin B (PMB)-modified, red blood cell (RBC)-mimetic hybrid liposome (P-RL) was developed. The P-RL was fabricated succinctly through fusion of PMB-modified lipids and the RBC membranes. By the strong interaction between PMB and the E. coli membrane, P-RL could attach and anchor to the E. coli; attributed to the fused RBC membrane and modified PMB, the P-RL could then efficiently neutralize both endotoxins and exotoxins from the toxin fountainhead. In vitro and in vivo results demonstrated the P-RL had a significant anchoring effect to E. coli. Moreover, compared with the existing RBC vesicles or PMB-modified liposomes, P-RL exhibited a superior therapeutic effect against RBC hemolysis, macrophage activation, and a mixed-toxin infection in mice. Potently, P-RL could inhibit E. coli O157:H7-induced skin damage, intestinal infection, and mouse death. Overall, the P-RL could potentially improve the detoxing efficiency and markedly expand the detoxification spectrum of current antivirulence systems, which provides different insights into drug-resistant E. coli treatment.

Silver-promoted synthesis of vinyl sulfones from vinyl bromides and sulfonyl hydrazides in water.

The synthesis of vinyl sulfones via silver-promoted cross-coupling of vinyl bromides with sulfonyl hydrazides was realized. Water was used as the sole solvent. Multisubstituted vinyl sulfones were easily prepared with excellent alkyl group tolerance. A mechanism involving nucleophilic attack of a sulfinate anion was proposed.

Germination Response of Four Alien Congeneric Amaranthus Species to Environmental Factors.

Seed germination is the key step for successful establishment, growth and further expansion of population especially for alien plants with annual life cycle. Traits like better adaptability and germination response were thought to be associated with plant invasion. However, there are not enough empirical studies correlating adaptation to environmental factors with germination response of alien invasive plants. In this study, we conducted congeneric comparisons of germination response to different environmental factors such as light, pH, NaCl, osmotic and soil burials among four alien amaranths that differ in invasiveness and have sympatric distribution in Jiangsu Province, China. The data were used to create three-parameter sigmoid and exponential decay models, which were fitted to cumulative germination and emergence curves. The results showed higher maximum Germination (Gmax), shorter time for 50% germination (G50) and the rapid slope (Grate) for Amaranthus blitum (low-invasive) and A. retroflexus (high-invasive) compare to intermediately invasive A. spinosus and A. viridis in all experimental regimes. It indicated that germination potential does not necessarily constitute a trait that can efficiently distinguish highly invasive and low invasive congeners in four Amaranthus species. However, it was showed that the germination performances of four amaranth species were more or less correlated with their worldwide distribution area. Therefore, the germination performance can be used as a reference indicator, but not an absolute trait for invasiveness. Our results also confirmed that superior germination performance in wide environmental conditions supplementing high seed productivity in highly invasive A. retroflexus might be one of the reasons for its prolific growth and wide distribution. These findings lay the foundation to develop more efficient weed management practice like deep burial of seeds by turning over soil and use of tillage agriculture to control these invasive weed species.

An asymmetric approach to bicyclo[2.2.1]heptane-1-carboxylates via a formal [4 + 2] cycloaddition reaction enabled by organocatalysis.

An organocatalytic formal [4 + 2] cycloaddition reaction has been realized that permits rapid access to a wide range of bicyclo[2.2.1]heptane-1-carboxylates in a highly enantioselective manner from simple starting materials under mild and operationally simple conditions.

Divergent total synthesis of the Lycopodium alkaloids huperzine A, huperzine B, and huperzine U.

Huperzine A, huperzine B, and huperzine U are congeners isolated from the Chinese herb Huperzia serrata (= Lycopodium serratum ) in minuscule amounts. The most efficient total synthesis of huperzine A, the first asymmetric total syntheses of huperzine B, and the first total synthesis of huperzine U have been achieved efficiently in overall yields of 17%, 10%, and 9%, respectively, each spanning 10-13 steps from (R)-pulegone. The featured steps include palladium-catalyzed Buchwald-Hartwig coupling and Heck cyclization reactions and an Ir-catalyzed olefin isomerization reaction. This work has established the absolute configurations of huperzine B and huperzine U and revealed that natural huperzine A, huperzine B, and huperzine U possess the same set of absolute stereochemistries, thus providing support for the potential role of huperzine B and huperzine U in the biosynthesis of huperzine A.

[Study on uniformity of optical field in static Fourier transform spectrometer].

Since the Fourier transform spectrometer based on multi-micro mirrors samples the interferogram image which corresponds to each OPD in the transverse optical field, the spatial distribution of the irradiance has much effect on the quality of the interferogram. In the present paper, distribution function is introduced in this spectrometer system. By means of simulation, the contrast of the interferogram modulated by distribution function is depressed in the fringe area and the concomitant line appears in the spectrum. According to theory analysis, the decline of the contrast lies on the distribution function which scans the interferogram periodically. And the concomitant line is the effect of the spectrum shift, which belongs to the modulation function. Finally, the difference image and conversed recovery arithmetic are proposed. Via the simulation, the conversed recovery arithmetic can recover the interferogram and the spectrum evidently.

Construction of highly functional quaternary carbon stereocenters via an organocatalytic tandem cyanation-allylic alkylation reaction.

The first tertiary amine-catalyzed tandem cyanation-allyic alkylation (CAA) reaction of aldehydes, appropriate cyanide sources, and Morita-Baylis-Hillman (MBH) adducts has been developed, which provides a facile access to densely functionalized products containing O-substituted quaternary centers.

Further evaluation of the characteristics of Treponema pallidum-specific IgM antibody in syphilis serofast reaction patients.

Syphilis serofast reaction (SSR) is common in clinical work. From June 2005 to May 2009, 1208 syphilis patients were chosen for research by the Xiamen Center of Clinical Laboratory in China. Serologic tests were performed with toluidine red unheated serum test (TRUST) and Treponema pallidum particle agglutination (TPPA). Then, T. pallidum-specific IgM antibody (TP-IgM) was detected with fluorescent treponemal antibody absorption (FTA-Abs) and TPPA. In this study, patients were divided into the following experimental groups according to the results of TRUST and TPPA: (1) the SSR group consisted of 411 cases with (+) TRUST and (+) TPPA, and without clinical manifestations after 1 year of recommended syphilis treatment; (2) the serum cure group, which was further subdivided into group A consisting of 251cases with (-) TRUST and (+) TPPA; (3) group B consisting of 546 cases with (-) TRUST and (-) TPPA; and (4) the blood donor control group which consisted of 100 cases. We demonstrated that a total of 136 cases (33.09%) of 411 SSR patients were TP-IgM positive by TPPA, and this percentage was markedly higher than that in serum cure group A (9.16%). FTA-Abs analyses revealed similar results. All samples in serum cure group B and the control group were TP-IgM negative, which is identical to our previous report. The present study also indicated that the TP-IgM positive rate was not significantly different among patients with different ages, genders, and clinical phases after 1 year of recommended therapy. From the total of 1208 syphilis patients, 289 were randomly selected for TP-DNA detection by fluorescence quantitative polymerase chain reaction, and the positive rate of TP-DNA was 32.53%, which was slightly higher than that of FTA-Abs TP-IgM, and no statistically significant difference by chi-square tests, indicating the TP-DNA result is preferably consistent with FTA-Abs and supporting our deduction that TP-IgM could be used as a serologic marker for the relapse and infection of syphilis.

[Influence of extended light source on spectral reconstruction in a micro FTIR].

The influence of extended light source on spectral reconstruction in the FTIR (fourier transform infrared spectrometer) based on step mirrors was discussed in the present paper. The relationship between coherent intensity and solid angle was calculated. It was found that the coherent length became shorter and the spectrum resolving power became lower as a result of solid angle produced by the extended light source. The spectrum resolving power of system could reach the value as the theoretic design if the solid angle of extended light source is smaller than 0.001. The radiance will reduce if the size of extended light source is shortened. Therefore, a suitable size of extended light source can be chosen, considering the requirement of SNR in the optical design.

Expression of inflammatory and apoptosis factors following coronary stent implantation in coronary heart disease patients.

We investigated the changes in characteristics of neutrophil CD11b, monocyte CD11b, platelet CD62P, endothelin (ET), and neutrophil CD178 in patients with coronary heart disease (CHD) before and after primary coronary stenting. A total of 41 patients with CHD who underwent coronary stenting and 40 control subjects were enrolled in the study. In CHD patients, peripheral blood samples were taken 24 h before and 30 min, 24 h, and 72 h after successful coronary stenting. All markers were significantly elevated in patients with CHD compared with controls (P<0.05). Time-course studies revealed that the expressions of neutrophil CD11b, monocyte CD11b, platelet CD62P, and ET were lower at 30 min post-operation (PO) compared with that at 24 h before operation (BO) (P<0.05). All levels significantly increased from 30 min PO to 24 h PO (P<0.05) and decreased thereafter until 72 h PO (P>0.05). Time course changes in neutrophil CD11b levels after coronary stenting were significantly higher in patients with unstable angina pectoris than in patients with stable angina pectoris (P<0.05). CD11b levels were related to CD62P in patients with CHD (P<0.05). Neutrophil CD11b and monocyte CD11b levels were significantly increased in patients with CHD who underwent coronary stenting compared with controls (P<0.05). Results show that CD11b levels increased, meanwhile, the levels of CD62P and ET increased in CHD patients after coronary stenting. In addition, neutrophil CD178 levels of apoptosis factor in patients, which is important for regression of inflammation, remained high for a period of time after coronary stenting.

[Analysis of collimation error in Fourier transform infrared spectrometer based on step mirrors].

The collimation error in Fourier transform spectrometer has many effects on the interferogram and the spectrogram. By means of modulation, the authors found the reverse of contrast in the interferogram and the side slope noise in the spectrogram due to the collimation error. The authors analyzed the signal-to-noise ratio and resolution at different factor of beam divergence. When the factor of the beam divergence is 0.15 degrees x mm(-1), the signal-to-noise ratio can reduce to 6 dB and the resolution can go bad to 13.4 cm(-1).

[Analysis of diffraction in Fourier-transform infrared spectrometer based on step mirrors].

Diffraction in the Fourier-transform infrared spectrometer based on step mirrors was analyzed in the present paper, and the influence of diffraction on the spectrum reconstruction with different width of step mirrors, wavelengths and distance was also discussed. It is shown that the influence of diffraction is low when the distance is less than 10 cm and the width of mirror is more than 0.5 mm. Also, a method to reduce the noises in spectrum reconstuction is discussed in this paper. The results could be used in the design of the spectrometer and the data processing in the next step.

[Development and application of geographic information system of Aedes vector in Chaozhou city, Guangdong province].

OBJECTIVE: To explore the spatial distribution character of dengue fever and the change of Aedes' population, so as to provide macroscopical decision-making evidences of prevention and supervision on dengue fever. METHODS: (1) Collecting data on morbidity of dengue and supervision on vector's population in the corresponding period. (2) Drawing digitized map of Chaozhou in scale of 1:50,000, including elements of boundary, residential areas, road and traffic, altitude, water systems etc. (3) Measuring the latitude and longitude of center position of surveillance safes on the scene. (4) Processing spatial analysis by the ArcGIS 8.5 software. RESULTS: Distribution of Aedes showed spatial cluster in Chaozhou, while its density was related to the distance to the watersides. The closer to the watersides, the higher the density was. Map on spatial distribution showed that although the Aedes epidemic situation changed yearly, but primarily be kept in high, middle, low regions. Cross-validation effects of the distribution maps were satisfactory. CONCLUSION: Geographic information system was promising in analyzing data on dengue fever, and better than other routine research methods.