A majority-logic device using an irreversible single-electron box

We describe a majority-logic gate device suitable for use in developing single-electron integrated circuits. The device consists of a capacitor array for input summation and an irreversible single-electron box for threshold operation. It accepts three binary inputs and produces a corresponding output, a complementary majority-logic output, by using the change in its tunneling threshold caused by the input signals; it produces a logical 1 output if two or three of the inputs are logical 0 and a logical 0 output if two or three of the inputs are logical 1. We combined several of these gate devices to form subsystems, a shift register and a full adder, and confirmed their operation by computer simulation. The gate device is simple in structure and powerful in terms of implementing digital functions with a small number of devices. These superior features will enable the device to contribute to the development of single-electron integrated circuits.     

Human apolipoprotein A-I gene promoter mutation influences plasma low density lipoprotein cholesterol response to dietary fat saturation

Numerous studies have demonstrated an association between polycyclic aromatic hydrocarbons (PAHs) and lymphocyte toxicity. The present study shows that, consistent with its effects on Ca2+ homeostasis, benzo[a]pyrene (BaP) induces apoptosis in Daudi cells. Terminal deoxynucleotidal transferase-mediated dUTP-biotin nick end labeling (TUNEL) analysis at 18 h revealed a significant increase in the number of cells undergoing apoptosis in response to BaP (75%), BaP-7, 8-dihydrodiol (110%), and BaP-7,8-9,10-diol epoxide (BPDE) (215%) over DMSO vehicle control cultures. By 36 h, the trend toward increasing numbers of apoptotic cells continued with the parent compound producing a 125% increase over control values and the 7, 8-dihydrodiol and BPDE metabolites producing 195% and 370% increases over controls, respectively. DNA fragmentation assays demonstrated the presence of internucleosomal cleavage products consistent with the increasing numbers of TUNEL-positive cells responding to PAHs at 18 and 36 h. Analysis of poly(ADP-ribose) polymerase (PARP) protein in BaP- and BaP-7,8-dihydrodiol-treated cells strongly suggested the involvement of cysteine proteases by the appearance of an 85-kD fragment derived from hydrolytic cleavage of PARP, a phenomenon that has been associated with apoptosis in many systems. Immunoblot analysis demonstrated that both BaP and its 7,8-dihydrodiol metabolite affected a pathway involving Bcl-2 and Bax cytosolic proteins. Daudi cells undergoing apoptosis at 36 h in response to 10 microM BaP, the parent compound, expressed moderately reduced amounts of Bcl-2 (78% of vehicle controls). At the same time point, the 7,8-dihydrodiol and BDPE metabolites at 3 microM resulted in Bcl-2 protein expression that was 52% of that seen in vehicle controls. Parallel samples analyzed for expression of Bax protein displayed a 130% increase over vehicle control in Bax expression in response to the parent compound, while the 7,8-dihydrodiol metabolite produced a 257% increase in Bax. Furthermore, the effects on increased Bax expression were observed as early as 3 h after PAH exposure. The apoptotic response to PAHs in Daudi cells was sensitive to 4-h pretreatment with 0.3 microM alpha-naphthoflavone (ANF), a known inhibitor of cytochrome P450. In TUNEL assays of cells exposed to PAHs following pretreatment with ANF, at 18 h there was a significant reduction in the number of cells undergoing apoptosis in response to ANF compared to cells that were not pretreated with the compound. The effect of the parent compound at 18 h was completely blocked with ANF pretreatment, while ANF exerted a relatively weaker, but significant, effect on BaP-7, 8-dihydrodiol-induced apoptosis. With regard to modulation of expression of apoptosis-related proteins, Bax expression was restored to that observed in vehicle-control cultures at all time points tested (3, 18, and 36 h). Bcl-2 expression was most responsive to ANF at later time points following PAH exposure (18 and 36 h); however, Bcl-2 appeared to be more sensitive to the effects of ANF alone. Taken together, these data suggest that modulation of Bcl-2 family proteins, perhaps secondary to altered Ca2+ homeostasis, plays an important role in human B cell apoptosis induced by BaP.     

Protein modification by a Maillard reaction intermediate methylglyoxal. Immunochemical detection of fluorescent 5-methylimidazolone derivatives in vivo

Methylglyoxal (MG), an endogenous metabolite that increases in diabetes, is a common intermediate in nonenzymatic glycation (Maillard reaction) in vivo. Here we describe the immunochemical approach to the detection of MG adducts in proteins in vitro and in atherosclerotic lesions of human aorta in vivo. The reaction of protein (bovine serum albumin) with MG led to selective loss of arginine and lysine residues, accompanied by the formation of 5-methylimidazolone (N delta-(5-methylimidazolon-2-yl)ornithine) and imidazolysine (1,3-di-lysino-4-methylimidazole) derivatives, respectively. The anti-5-methylimidazolone antibody was prepared by immunizing rabbits with a MG-keyhole limpet hemocyanin conjugate and purifying the serum on an affinity gel prepared by covalent attachment of the 5-methylimidazolone derivative. The antibody cross-reacted with the proteins treated with not only MG but trioses, such as hydroxyacetone, dihydroxyacetone, and glyceraldehyde. The immunohistochemical analysis revealed that atherosclerotic lesions of human aorta contained 5-methylimidazolone derivatives whose distributions were identical to those of advanced glycation end products (AGEs) detected by the anti-AGE antibody.     

Preparation of Nb3Ge films by chemical transport reaction and their critical properties

Niobium-germanium films have been deposited on sapphire substrates at 900 C by a chemical transport reaction method. The highest superconducting transition onset temperature T _C,on of 22.4 K is observed for a nearly stoichiometric Nb₃Ge film with the A15-type structure (thickness ~ 93.5 m). Lattice constants for the Nb₃Ge phase formed in the Nb-Ge films with both T _C,on above 22 K and T _C,midpoint above 21 K are found to extend from 5.143 to 5.153 ». Deposition rates for the obtained films are in the range of 2–10 m/min. Critical current densities for the Nb₃Ge film with the highest T _C,on value are observed to be relatively low (~ 10³ A/cm² at 19 K at self-field). This is due to the coarse grain structure of the film or the low density of effectual pinning centers in the film. Field variations of the pinning forces operating in this film in magnetic fields both parallel to the film surface and perpendicular to the film surface are found to follow closely b ^1/2(1\s-b)², to which the pinning force for flux pinning at the surface of normal regions, such as grain boundaries, film surfaces, etc., is proportional, and where b is the reduced magnetic induction (B/B _C2).A small increase in J _C at low fields is caused by the presence of a small amount of the Nb₅Ge₃ phase in a Nb₃Ge film, and seems attributable to additional flux pinning on Nb₅Ge₃-phase particles in the film.Supported by Deutsche Forschungsgemeinschaft.