Ammonia assimilation in Klebsiella pneumoniae F-5-2 that can utilize ammonium and nitrate ions simultaneously: purification and characterization of glutamate dehydrogenase and glutamine synthetase

The two ammonia-assimilating enzymes glutamate dehydrogenase (GDH; EC 1.4.1.4) and glutamine synthetase (GS; EC 6.3.1.2) were synthesized steadily during the cell growth of Klebsiella pneumoniae F-5-2 that can utilize NH4+ and NO3- simultaneously under aerobic conditions. The enzymes were purified to homogeneity from cell extracts and characterized. The molecular mass of the purified GDH was 300 kDa with six identical 52-kDa subunits. GDH showed its maximal activity (aminating) at pH 8.0 and was stable between pHs 5.5 and 11.5. The enzyme was NADP-specific and strongly inhibited by Ag+. It catalyzed the amination of 2-ketovalerate, 2-ketoadipate, and 2-ketobutyrate, in addition to 2-ketoglutarate. The purified GS has a molecular mass of 470 kDa with eight identical 60-kDa subunits. GS showed its maximal activity at pH 8.0 and was stable between pHs 6.0 and 7.0. The enzyme was strongly inhibited by Fe3+, Hg2+, and Cu2+.     

An investigation of the pH-activity relationships of Cex, a family 10 xylanase from Cellulomonas fimi: xylan inhibition and the influence of nitro-substituted aryl-beta-D-xylobiosides on xylanase activity

The kinetic parameters of Cex, a family 10 xylanase from Cellulomonas fimi, were determined at various pH levels using soluble birchwood xylan (BWX) as a natural polymeric substrate along with three other synthetic aryl-beta-D-xylobioside substrates. Using BWX, a high level of substrate inhibition was observed which increased with decreasing pH. In contrast, typical Michaelis-Menten-type profiles were obtained using the three aryl-beta-D-xylobiosides as substrates. The k(cat) values determined using o-nitrophenyl-beta-D-xylobioside did not change as the pH increased, whereas the k(cat) values obtained with BWX, phenyl-beta-D-xylobioside and p-nitrophenyl-beta-D-xylobioside decreased, suggesting that the presence of an ortho nitro group affects the activity displayed by Cex. These differences were not observed with XynB from Clostridium stercorarium F9, a member of the same family of xylanases as Cex. These results indicate that a careful evaluation is required when employing substituted aryl-beta-D-xylobiosides in the characterization of xylanases.     

Intra-body data transmission for the personal area network

Intra-body communication is a wireless means of exchanging information within a personal area network (PAN) between wearable electronic sensors and devices. The feasibility of intra-body communication is confirmed through several experiments on signal propagation within the human body, and a human phantom is designed and used to obtain reproducible results over repeated experiments. Based on the results of these experiments, a prototype transmission system is constructed using aluminum electrodes powered by 3 V DC and operating in the 10.7 MHz frequency modulation (FM) band. This prototype is demonstrated to be capable of transmitting analog signals through the human subjects in the presence of external noise. Digital data transmission at 9600 bps is also achieved using newly fabricated 10.7 MHz frequency shift keying (FSK) transmitter and receiver devices. The carrier frequency of 10.7 MHz is the intermediate frequency of FM radio receivers, meaning that the proposed system can make use of a wide selection of inexpensive, commercial radio frequency devices.     

Address‐While‐Display technique combined with gas‐discharge AND logic for driving AC‐PDPs

A hybrid AWD/AND drive technique has been developed in which an Address‐While‐Display (AWD) scheme is combined with an AND logic characteristic that gas discharges demonstrate. The AWD technique enables AC‐PDPs to be driven at high luminance, while the AND logic reduces the number of scan drivers by an order of magnitude. A detailed analysis of the addressing operation has been made. The hybrid drive utilizes the AND logic in two ways: (1) a combination of two voltage pulses and (2) a combination of a voltage pulse and discharge‐priming particles. It was found that the addressing operation requires the establishment of a discharge between the scan and data electrodes, and also between the scan and display electrodes.     

Preparation of BaTiO3 ultrafine particles by micro-emulsion charring method

Ultrafine BaTiO₃ particles were prepared by a micro-emulsion charring (MEC) method. The MEC method consisted of two steps. The first step is the preparation of a water/oil micro-emulsion with BaTiO₃ elements, and the second is a low temperature firing process in N₂ atmosphere, which includes charring of oil in an emulsion and powdering BaTiO₃ particles with the char. The char formed around BaTiO₃ particles prevents an agglomeration of BaTiO₃ particles during firing. In the present experiment, the W/O ratio and the amount of emulsifier greatly influenced the size of droplets of the emulsion. The charring temperature was another important experimental factor in order to obtain the desired BaTiO₃ particles. The finally obtained BaTiO₃ charring powders were monodispersed spherical particles and the particle size was 0.1 m to 0.5 m.     

Selective isopentane formation from CH3OH on a new one-atomic layer ZrO2/ZSM-5 hybrid catalyst

A new one-atomic layer ZrO₂/ZSM-5 hybrid catalyst was prepared by using the repeated reactions between Zr(OC₂H₅)₄ and of the OH groups of the external surfaces of ZSM-5, followed by calcination. The one-atomic layer ZrO₂ attached on the ZSM-5 surface was characterized by means of X-ray diffraction, X-ray fluorescence and EXAFS. The ZrO₂ overlayer is suggested to epitaxially grow on the ZSM-5(001) plane in a [111] direction of tetragonal ZrO₂. The one-atomic layer ZrO₂/ZSM-5 is a unique catalyst which produces selectively isopentane from CH₃OH.     

Inhibition of intimal hyperplasia after vein grafting by in vivo transfer of human senescent cell-derived inhibitor-1 gene

OBJECTIVE: To define the distribution and determinants of cardiovascular disease events among participants undergoing long-term antihypertensive therapy, and to stratify them into risk groups on the basis of pretreatment clinical profiles. DESIGN: A prospective cohort study of participants in a worksite-based antihypertensive treatment program in New York city (1973-1994). PATIENTS: We studied 8690 systematically treated patients who had at least 6 months of follow-up (average of 5.7 years) and, at entry, had had a systolic blood pressure of > or = 160 mmHg or a diastolic blood pressure of > or = 95 mmHg (after 1992 > or = 140/90 mmHg), or had been being administered antihypertensive medication. MAIN OUTCOME MEASURES: Blood pressure and incidence of morbid and mortal cardiovascular events. RESULTS: Blood pressure control (to 140 +/- 3/87 +/- 7 mmHg) was achieved by the first year and maintained through 18 years of therapy. In nearly 50,000 person-years of follow-up, there were 468 cardiovascular disease events [myocardial infarction including revascularization (282), strokes (93), congestive heart failure (30) and other cardiovascular deaths (63)]. Deaths from cardiovascular disease events accounted for 68% of all deaths. Myocardial infarction was most common throughout, but congestive heart failure incidence surpassed stroke incidence after 10 years. A scheme for risk stratification was constructed after analysis of the independent association of baseline factors and incident cardiovascular events. Upon the basis of ease of ascertainment and their demonstrated associations with occurrence of cardiovascular disease during treatment, we selected five pretreatment factors (history of heart attack, stroke, diabetes, age > or = 55 years and pulse pressure > or = 60 mmHg) to stratify patients into four groups. Those with no risk factor had a low risk (n=2999), those with one had a moderate risk (3042), those with two had a high risk (2237), and those with three or more had a very high risk (412). Overall, the unadjusted rates of incidence of cardiovascular disease events per 1000 person-years for patients in very high and low risk groups differed by factors of six and 14 for men and women, respectively. CONCLUSION: These results demonstrate that long-term control of blood pressure can be achieved in a general population. Nevertheless, cardiovascular disease events still accounted for most morbidity and mortality among these 'recovered' hypertensive patients. At entry, on the basis of readily identifiable characteristics, it was possible to stratify patients according to likelihood of subsequent events occurring despite control of blood pressure. This scheme could provide the basis for targeting more aggressive therapy where the potential for further cardioprotection is greatest.     

The characterization of low energy molecular hydrogen ion—induced defects in synthetic diamond by optical absorption

The results of optical absorption analysis of the synthetic diamonds(type Ib) which were implanted with 40 keV molecular hydrogen ions at doses of 10^15-10^17H/cm^2(at 100K),showed that the increase of optical density(OD) of modified layer(-140nm) in UV-VIS region was dependent upon the damage level caused by ion implantation process.The range of relative optical band gap(Er.opt) around 2.0eV suggested that an amorphous carbon network structure like a-C film,which probably contains some localized subtetrabedral-coordinated clusters embedded in the fourflod(sp^3) sites.was tentatively found in this layer,basing on the optical gap of carbon materials.The evolution of Er,opt with ion fluence indicated that no more hydrogenated carbon compositions were produced in as -implanted samples,while the increase of Er,opt with annealing temperature was very similar to that of hydrogen content dependence of Eopt in hydrogenately amorphous carbon(a-C:H):In addition the optical inhomogeneity of type Ib diamond has been revealed by a 2-dimension topograph in transmission mode at λ=430nm。