Efficient Synthesis of Tetrahydropyrimidines and Pyrrolidines by a Multicomponent Reaction of Dialkyl Acetylenedicarboxylates (=Dialkyl But‐2‐ynedioates), Amines,and Formaldehyde in the Presence of Iodine as a Catalyst

Iodine was explored as an efficient catalyst for the synthesis of tetrahydropyrimidines 4 and pyrrolidines 5 by a multicomponent reaction of dialkyl acetylenedicarboxylates (=dialkyl but‐2‐ynedioates) 1 , amines 2 , and HCHO 3 at room temperature (Scheme). When the molar ratios of these substrates were 1 : 2 : 4 and 1 : 1 : 4, tetrahydropyrimidines and pyrrolidines were formed, respectively. The products were obtained in high yields (73–85%) within a short period of time (25–35 min).     

Time-resolved red luminescence from europium-catalyzed single walled carbon nanotubes

The photo-physical properties of Eu-SWCNTs indicate that intrinsic excitonic properties of SWCNTs sensitize the lanthanoid element europium (Eu) to emit time-resolved red luminescence.     

Characterization of keratin–collagen 3D scaffold for biomedical applications

Fabrication of keratin–collagen (KC) 3D scaffold with improved thermal denaturation rate is reported. In vitro application of (KC) scaffold stimulates basic extra cellular matrix constituents. KC Scaffold considerably reduced undesirable properties of both collagen and keratin while collagen incorporation reduces the fragility with increases of strength and flexibility in the scaffold. In addition to this, the scaffold showed homogenous well‐interconnected pores in the range of 10–100 µm when observed in scanning electron microscope. Usage of keratin in KC scaffold offers increased biodegradation rate and higher denaturation rate in addition to its rapid cell growth with normal morphology ultimately reaching cell population of 3.9–9.7 million per cm³ after 48 hr in KC scaffold. Circular dichroism (CD) and Fourier transform spectroscopy (FT‐IR) of KC showed presence of helical structure of collagen and ß‐turns of keratin confirming retention of native structures of both the proteins KC scaffold showed good swelling behavior and water uptake. Our study strongly supports the superidity of KC scaffold over the collagen or keratin when they are independently used for tissue engineering applications. Copyright © 2011 John Wiley & Sons, Ltd.     

Synthesis of electron-poor hexa-peri-hexabenzocoronenes

The oxidative cyclodehydrogenation of electron-poor arenes was achieved using DDQ-CF(3)SO(3)H resulting in hexa-peri-hexabenzocoronenes with electron withdrawing Br, F and CF(3) groups. This method will lead to their expansion into a new class of electron transport materials.     

A novel oxidative transformation of alcohols to nitriles: an efficient utility of azides as a nitrogen source

An efficient methodology to oxidize benzylic and cinnamyl alcohols to their corresponding nitriles in excellent yields has been developed. This methodology employs DDQ as an oxidant and TMSN(3) as a source of nitrogen in the presence of a catalytic amount of Cu(ClO(4))(2)·6H(2)O.     

Comparison of Bacterial Communities in the Throat Swabs from Healthy Subjects and Pharyngitis Patients by Terminal Restriction Fragment Length Polymorphism

Terminal restriction fragment length polymorphism (T-RFLP) analysis was applied to characterize bacterial flora present in the throats of healthy subjects and pharyngitis patients. The 16S?rRNA genes of bacteria present in throat metagenome were amplified by PCR with 6-carboxy-fluorescein (6-FAM)-labeled universal forward primer (27?F) and a universal reverse primer (1513R). The 16S rDNAs were digested with restriction enzymes with 4-bp recognition sites (MspI or RsaI) and analyzed by using an automated DNA sequencer. T-RFLP patterns were numerically analyzed using computer programs. From analysis of the throat bacterial community, patterns derived from MspI and RsaI digested samples of healthy subjects and pharyngitis patients were grouped into different clusters, though RsaI digested samples showed some uncertainty. Pharyngitis throats generated an average species richness of 9 [±2.1 (SD)] and 10 (±2.9) for MspI and RsaI digests, respectively, whereas healthy throats generated 6.3 (±1.2) and 6.1 (±1.5) in MspI and RsaI digests, respectively. These results suggest that samples from pharyngitis patients contain an unexpected diversity of causative bacteria. The pharyngitis throats were colonized with a rich diversity of bacterial species than that of healthy throats. Using T-RFLP, we are able to detect a model bacterium, Streptococcus pyogenes SF370, and T-RF patterns were consistent with the Streptococcal T-RFLP patterns. Our study indicates that T-RFLP analysis is useful for the assessment of diversity of throat bacterial flora and rapid comparison of the community structure between subjects with and without pharyngitis.     

Fiber-Optic pH Sensor

The new enhancement in the determination of pH using optical fiber system is described here. This work uses the membrane made of cellulose acetate membrane for reagent immobilization and congo red (pK _a 3.7) and neutral red (pK _a 7.2) as pH indicators. An effective covalent chemical binding procedure is used to immobilize the indicators. The response time, reversibility, linear range, reproducibility, and long-term stability of fiber optic sensor with congo red as well as neutral red have been determined. The linear range measured for the sensor based on the congo red and neutral red is 4.2–6.3 and 4.1–9.0, respectively. The response time of sensor membrane is measured by varying the substance pH values between 11.0 and 2.0.     

Asymptotic independence of queues under randomized load balancing

Randomized load balancing greatly improves the sharing of resources while being simple to implement. In one such model, jobs arrive according to a rate-??N Poisson process, with ??<1, in a system of N rate-1 exponential server queues. In Vvedenskaya et al. (Probl. Inf. Transm. 32:15?C29, 1996), it was shown that when each arriving job is assigned to the shortest of D, D??2, randomly chosen queues, the equilibrium queue sizes decay doubly exponentially in the limit as N????. This is a substantial improvement over the case D=1, where queue sizes decay exponentially. The reasoning in Vvedenskaya et al. (Probl. Inf. Transm. 32:15?C29, 1996) does not easily generalize to jobs with nonexponential service time distributions. A?modularized program for treating randomized load balancing problems with general service time distributions was introduced in Bramson et al. (Proc. ACM SIGMETRICS, pp.?275?C286, 2010). The program relies on an ansatz that asserts that, for a randomized load balancing scheme in equilibrium, any fixed number of queues become independent of one another as N????. This allows computation of queue size distributions and other performance measures of interest. In this article, we demonstrate the ansatz in several settings. We consider the least loaded balancing problem, where an arriving job is assigned to the queue with the smallest workload. We also consider the more difficult problem, where an arriving job is assigned to the queue with the fewest jobs, and demonstrate the ansatz when the service discipline is FIFO and the service time distribution has a decreasing hazard rate. Last, we show the ansatz always holds for a sufficiently small arrival rate, as long as the service distribution has 2 moments.     

Structural role of polyethylene glycol in the formation of anatase nanocrystalline titania at low temperature

Anatase nanocrystalline TiO₂ thin films were obtained by a sol–gel dip‐coating method, in which the nanocrystallization is effected by a simple hot water treatment of the deposited films at temperatures below 90 °C under atmospheric pressure for 1 h. The dip‐coating sol was prepared by reacting titanium tetra‐n‐butoxide [Ti(OⁿBu)₄] with polyethylene glycol (PEG) in ethanol. Films obtained from a sol that do not contain PEG show no sign of crystallization, demonstrating the importance of PEG in the crystallization process. Raman studies of reaction dynamics show that PEG undergoes a nucleophilic substitution reaction replacing butoxy groups in Ti(OⁿBu)₄. Stoichiometric reactions of Ti(OⁿBu)₄ with PEG in polar and nonpolar solvents were performed, and they yielded different titanium–PEG hybrid polymers, which were isolated and characterized by various spectroscopic techniques such as IR, Raman, solid‐state NMR and MALDI‐TOF‐MS. NMR studies evidenced the location and the way in which PEG is bonded with titanium atoms in the titanium–PEG hybrid polymers. On the basis of these studies, we have proposed structures for these polymers. It is demonstrated that the structure of the obtained polymers plays an important role in the formation of anatase TiO₂ nanoparticles in hot water at temperatures below 90 °C under atmospheric pressure. Copyright © 2009 John Wiley & Sons, Ltd.