Studies on the anionic polymerization of methyl methacrylate with butyllithium by using perdeuterated monomer

Summary Methyl methacrylate-d₈ was polymerized by C₄H₉Li in toluene at –78°C and the resultant polymer and oligomer were studied for butyl group by ¹H NMR spectroscopy according to the precision coaxial tubing method (HATADA 1977a). A polymer and an oligomer molecule was found to have about one butyl group incorporated through the attack of C₄H₉Li on the carbonyl group as well as one terminal butyl group. The total amount of the C₄H₉Li residue introduced in both the polymer and oligomer molecules was measured to be 0.45mmol and almost corresponded to the amount of the C₄H₉Li used (0.50mmol).     

Diode-pumped 1 kW Q-switched Nd:YAG rod laser with high peak power and high beam quality

We have demonstrated high-peak-power generation at 1 kW average power by applying an acousto-optic Q switch to a quasi-cw diode-pumped Nd:YAG master oscillator power amplifier. We achieved a maximum peak power of 2.3 MW by driving the Q switch in burst mode. The average repetition rate was 6 kHz. The corresponding beam quality was M2 = 9.     

High-power and high-efficiency operation of a CW-diode-side-pumpedNd:YAG rod laser

We have demonstrated high-power and high efficiency performance of a continuous-wave (CW) Nd:YAG laser with a simple and scalable side-pumping configuration. The maximum output power of 147 W was obtained in low brightness operation of M²=45. The corresponding electric efficiency is 14.8%. To our knowledge, this is the highest value reported for diode side-pumped Nd:YAG lasers. By using a rate and photon transport calculation, we have estimated the pumping efficiency of 72%. High brightness operation was also carried out by applying bifocusing compensation of the Nd:YAG rod. The brightness of 272 MW/cm² sr with beam quality of M²=5.9 and output power of 107 W was obtained at the electric efficiency of 11.6%. The brightness and the electric efficiency are comparable with those of industrial high-power CO₂ lasers that have been the first option for industrial applications     

A new logistic model for bacterial growth

A new logistic model for bacterial growth was developed in this study. The model is based on a logistic model, which is often applied for biological and ecological population kinetics. The new model is described by a differential equation and contains an additional term for suppression of the growth rate during the lag phase, compared with the original logistic equation. The new model successfully described sigmoidal growth curves of Escherichia coli and Salmonella under various initial conditions. Data for E. coli were obtained from our experiments and data for Salmonella from the literature. When the new model was compared with a modified Gompertz model, which is widely used by many predictive microbiology researchers, it proved to be superior to the Gompertz model. Further, Salmonella growth at varying temperature could be well simulated by the new model. These results indicate that the new model will be a useful tool to predict bacterial growth under various temperature profiles.     

MRT letter: Expression of ATP sensor protein in Caenorhabditis elegans

Adenosine 5'-triphosphate (ATP) is the major energy currency and is involved in many biological processes. The ATP-monitoring system for cells in animals can be helpful to study the relationship between energy metabolism and biological processes. The fluorescent ATP biosensor ATeam (ATP indicator based on Epsilon subunit for Analytical Measurements), which has been reported to monitor ATP levels in cultured cells on the basis of fluorescence resonance energy transfer (FRET), was introduced into nematodes by microinjection and UV-irradiation method. To confirm whether ATeam functions as an ATP sensor in nematode cells, the authors measured FRET of ATeam in cells of transgenic nematode. The ATeam was expressed in target cells in nematode. In vulva cells, ATP levels in the cytosol were higher than those in mitochondria. ATeam also sensed ATP level change in cultured cells from the transgenic nematode. These experiments indicated that ATeam is available for detection of changes in ATP levels in nematode cells.     

Primary obsessional slowness: long-term findings

BACKGROUND: The purpose of this work is to analyze the fertility of the hydatid cysts from ovine, animal species of great epidemiological interest in the hydatid disease, and the ability of the gerbil (Meriones unguiculatus) as model experimental for the study "in vivo" of this hidatyd disease as preliminary phase of therapeutic studies. METHODS: It has been carried out a study of the fertility and viability of hydatid cysts from lungs and livers of ovine from Castilla and Leon by examination and evaluation of parameters among these is the production of a secondary hydatid disease in laboratory animals. RESULTS: The total cystic index was 8.57 cysts by infested ovine (5.97 cysts by infested lung and 5.57 cysts by infested liver). The fertility percentage obtained in hydatid cysts from ovine with "in vitro" viables protoescoleces was 43.97% being 43.02% a pulmonary cysts and 46.16% in hepatic cysts. The viability of protoscoleces was demonstrated by production of a secondary hydatid disease in 100% of gerbils infested. CONCLUSIONS: It is emphasized the validity of the criteria used to study the viability "in vitro" of the protoescoleces from hydatid cysts of origin ovine. The secondary hydatid produced in gerbil leads us to consider them as experimental animal for investigation "in vivo" of hydatid disease of origin ovine.     

Effect of eicosapentaenoic acid ethyl ester on proteinuria of streptozotocin-induced diabetes mellitus in rats

Streptozotocin (45 mg/kg) was intravenously administered to 7-week-old Wistar rats through their tail veins. After 11 days, the rats were divided into two groups. One group was fed a lipid-free diet (90%, w/w) plus lard (8%) and safflower oil (2%) for four weeks (Diet 1 group, n=12). The other group was fed in the same way, except that safflower oil was replaced by 90% pure eicosapentaenoic acid (EPA) ethyl ester (Diet 2 group, n=13). Twenty-four-hour urine was collected just before the diets started and during the experiment at 7-day intervals. In the second and third week, the levels of proteinuria were significantly lower in the Diet 2 group than they were in the Diet 1 group. There was no significant difference in the levels of creatinine, urea nitrogen, or lipids in plasma or in body weights between the two groups after four weeks on the diets. Because Diet 2 reduced proteinuria of diabetic rats compared to Diet 1, an EPA-rich diet may retard the development of diabetic nephropathy.