Preparation of heterotactic-rich poly(methyl methacrylate) with narrow molecular weight distribution bytert-butyllithium/bis(2,6-di-tert-butylphenoxy)methylaluminum

Summary Polymerization of methyl methacrylate (MMA) withtert-butyllithium (t-C₄H₉Li) in toluene in the presence of aluminum alkoxides such as ethoxide,tert-butoxide and 2,6-di-tert-butylphenoxide, were examined at various Al/Li ratios. In the cases of ethoxide andtert-butoxide, predominantly isotactic polymers with broad molecular weight distribution were obtained. Combinations oft-C₄H₉Li and bis(2,6-ditert-butylphenoxy)methylaluminum [MeAl(ODBP)₂] were found to be an efficient initiating system for heterotactic polymerization of MMA, which gives PMMA rich in heterotactic triads up to 68% with narrow molecular weight distribution (Mw/Mn=1.09–1.17). End group analysis by¹H NMR indicated thatt-C₄H₉Li initiates the polymerization and MeAl(ODBP)₂ works as a stereospecific modifier. From stereosequence analysis of the heterotactic PMMA by¹³C NMR, it was found that the calculated pentad fractions from the first-order Markovian statistics (Pm/r=0.742, Pr/m=0.627) fitted the observed ones better than those from Bernoullian statistics. The glass transition temperature of the heterotactic PMMA was 13°C lower than that of syndiotactic PMMA, and the intrinsic viscosity in tetrahydrofuran was close to that of isotactic PMMA with a similar molecular weight but higher than that of syndiotactic PMMA.     

Multifocal ventricular tachycardia after resuscitation by direct current counter shock in a dog

Cardiac arrest occurred in a male Labrador Retriever dog weighing 27.8 kg during induction to anesthesia. Immediately after the failure of resuscitation by the external cardiac compression, thoracotomy was performed and open chest direct current (DC) counter shocks were applied with routine emergency medications. Then the dog recovered consciousness. Although cardiac rhythm just after resuscitation was sinus tachycardia with paroxysmal supraventricular tachycardia, multifocal ventricular arrhythmia occurred 2 hr after resuscitation. This arrhythmia might be the result from reversible cardiac lesions due to DC counter shock.     

Osteoclastogenesis inhibitory factor exhibits hypocalcemic effects in normal mice and in hypercalcemic nude mice carrying tumors associated with humoral hypercalcemia of malignancy

In the present study, we attempted to determine the extent to which an anterior capsulorrhexis carried out during cataract surgery contracts postoperatively. The size of the continuous curvilinear capsulorrhexis (CCC) was measured at the end of surgery and at the final follow-up examination in 52 eyes of 40 patients who underwent phacoemulsification/aspiration and implantation of an intraocular lens (IOL) with 6-mm optics. Images obtained by video during surgery and by slit-lamp microscopy were used to determine the CCC size with reference to the optics of the IOL. The average CCC size was 5.0 mm at the end of surgery; it contracted to 4.4 mm by the final postoperative examination. The contraction of the anterior capsule progressed rapidly in the first 50 days following surgery and then gradually thereafter. The extent of contraction was greater in older patients. The smaller the CCC size immediately after surgery, the more rapidly it contracted. The size of the capsulorrhexis contracted an average of 22% following cataract surgery. The contraction rate tended to be higher in older patients. The results suggest that the capsulorrhexis carried out in cataract surgery for elderly patients should be sufficiently large, but not larger than the optics size of the IOL.     

Determination of assigned configurational parameters for cross propagation in radical copolymerization of methyl methacrylate and trityl methacrylate

Summary Copolymer of methyl methacrylate-d₈(M₁) with a small amount of trityl methacrylate(M₂) was radically prepared in tetrahydrofuran and converted into the copolymer of methyl methacrylate-d₈ with a small amount of undeuterated methyl methacrylate by the selective hydrolysis of the trityl group and subsequent methylation with diazomethane. From the ¹H NMR spectrum of the derived copolymer the assigned coisotactic parameters ₁₂ and ₂₁ were determined to be 0.14 and 0.61, respectively. This may be the first example of the unequivocal determination of assigned configurational parameters in cross propagation for copolymerization.     

Formation and characterization of copper tetrakis (4-cumylphenoxy) phthalocyanine:perylene solar cells

Perylene-based bulk heterojunction solar cells with copper tetrakis (4-cumylphenoxy) phthalocyanine (Tc-CuPc) and heterojunction solar cells with copper phthalocyanine (CuPc) were produced and characterized. A device based on CuPc and perylene provided better efficiency, fill factor, short-circuit current and open-circuit voltage compared to those of a device based on Tc-CuPc and perylene. The Tc-CuPc:perylene structure was examined by transmission electron microscopy, which indicated mixtured microstructure. Energy levels of the molecules were calculated and discussed.     

High drive current NMOS with Si-SiGe heterostructure low electric field channel

A drive-current enhancement in NMOS with a compressively strained SiGe structure, which had been a difficult challenge for CMOS integration with strained SiGe high-hole-mobility PMOS, was successfully achieved using a Si-SiGe heterostructure low electric field channel of optimum thickness. A 4-nm-thick Si low-field-channel NMOS with a 4-nm-thick Si/sub 0.8/Ge/sub 0.2/ layer improved drive current by 10% with a 20% reduction in gate leakage current compared with Si-control, while suppressing threshold-voltage rolloff characteristic degradation, and demonstrated excellent I/sub on/--I/sub off/ characteristics of I/sub on/ = 1 mA//spl mu/m for I/sub off/ = 100 nA//spl mu/m. These results are the best in ever reported NMOS with a compressively strained SiGe structure and indicate that a Si-SiGe heterostructure low-field-channel NMOS integrated with a compressively strained SiGe channel PMOS is a promising candidate for high-speed CMOS in 65-nm node logic technology.     

Dynamic load balancing among multiple fabrication lines through estimation of minimum inter-operation time

We propose a load balancing method which balances all processing operations of products among multiple semiconductor wafer fabrication lines (fabs) by using predictive scheduling results. Through a simulation experiment we confirmed that the proposed method enabled improved load balancing (compared to conventional methods) among multiple fabrication lines each of which can independently fabricate wafers and has different wafer processing capacity. The load balancing feature effectively reduces the waiting time at each process step and the lead time of all products in multiple fabs. Another promising application of the proposed method is performance evaluation of automated material handling systems (AMHS) in terms of inter-operation time, and we have used the method to evaluate the transportation efficiency of actual fabs.