Psi particle

Before discovery of the hadron particle (designated psi or J), and after much experimental and theoretical effort, physicists had about concluded that three massive, fractionally charged entities (quarks) were the primary building blocks of the universe. However, discovery of the psi particles in 1974 indicated a fourth quark was required. Previously, in the thrcc-quark model, all mesons were made up of one quark and one aiitiquark baryons, of three quarks and all anti-baryons, of three antiquarks. Prior to 1974, all of the known hadrons could be accommodated within this basic scheme Three of the possible meson combinations of quark-antiquark could have the same quantum numbers as the photon, and hence could be produced abundantly in e+e annihilation. These three predicted states had all been found. 

PSI PARTICLE. Discovery of this subatomic particle in 1974 was announced independently by Ting (Brookhaven National Laboratory) who named it the J particle and by B.D. Richter (Stanford) who named it the psi particle. The discovery of this particle resolved a number of important problems in particle physics. Intensive research on the psi particle was carried out by Richter and the Stanford group during 1975 and 1976 and is reported firsthand by Richter (Science, 196, 1286-1297.1977). As pointed out by Richter, the four-quark theoretical model became much more compelling with the discovery of the psi particles, The long life of the psi is explained by the fact that the decay of the psi into ordinary hadrons requires the conversion of both c and c into other quarks and antiquarks. See also Particles (Subatomic). 

Particle size reduction of a material suspended in a liquid medium can be affected by a Microi uidizeP processor (MicroLuidics Corp., Newton, MA, http //www.microLuidicscorp.com/ processors.html). A schematic of a MicroLuidizer processor is presented in Figure 17.6. In a Micro-Luidizer processor, a liquid stream is bifurcated and the two streams are directed upon each other under pressures as high as 40,000 psi. Particles suspended in the liquid are reduced in size by forces of shear and cavitation. Suspensions can be prepared with the MicroLuidizer processor with mean particle sizes in the micron to submicron range. 

Fig. 4. ESR spectra of Aj and A0 of illuminated PSI particles. Left PeaPSI at 200K (Aj) and215K (Aj and A0). Right Phormidium lamlnosum PSI at 205K and 230K (Smith et al., 1987)...

In this paper we describe an easy, reproducible, and fast procedure for obtaining PSI-enriched particles by a non-detergent method from the thermophilic cyanobacterium Phormidium lamirtosum. These particles showed a PSI activity (ascorbate/DCPIP MV) of up to 200 (imole 02 taken up per mg chlorophyll per h, and negligible PSII activity (H20 DMBQ or ferricyanide). We also present evidence on the feasibility of H2 photoproduction and phosphoribulokinase photoactivation mediated by such PSI particles coupled to hydrogenase or to a Fd/TRX system. 

Hydrogenase activities were measured using MV chemically reduced with sodium dithionite or photochemically with PSI particles. Photoproduction pf H2 was carried out in 15 ml glass vials under a nitrogen atmosphere, at 30 °C, in a shaking water bath illuminated with white light of intensity 250 pE m 2 s 1 H2 evolved was determined gas chromatographically (Rao et al., 1978). 

The absorption spectra of the fractions obtained during the purification of the PSI particles are shown in Fig la. Both the sonicate and the original 40,000 xg supernatant showed a major peak at 620 nm due to soluble phycobiliproteins, which can be completely removed by batch chromatography on DE AE-cellulose. Thus, the A620/A676 ratio, which compares the absorption maxima of blue pigments to that of chlorophyll was 2.73 in the sonicate, 3.81 in the 40,000 xg supernatant, and only 0.27 in the DE-52 eluate. 

Finally, in order to ascertain if our PSI-particles were also useful for enzyme activation by potochemically reduced TRX, the purc/1. cylindrica PRuK was incubated with PSI-enriched particles, TRX and Fd-TRX reductase purified from /l. cylindrica (Serra et al., 1987) and a number of natural and artificial electron mediators as described under Materials and Methods. As shown in Fig. 5, PRuK was activated by photoreduced TRX and the degree of activation achieved depended on the time of pieincubation (compare curves b-d). No activation was observed when the enzyme was preincubated in the dark with the complete Fd/TRX system, or when the Fd-TRX reductase was omitted. 

Fig. 4. H2 photoevolution from ascorbate via P. laminosum PSI particles under different conditions of immobilization. The complete assay system contained 100 mM Mes-NaOH buffer, pH 7.0 75 mM sodium ascorbate 15 mM DTT 2 mM TMPD 1% (w/v) BSA PSI particles (30 pg Chi) 50 pi (saturating amount) of Clostridium pasteurianum hydrogenase and 12.5 pM Spirulina maxima Fd as electron mediator, (a) Conditions all components free (b) hydrogenase immobilized in Ca alginate according to Gisby and Hall (1980) (c) PSI particles immobilized in Ca alginate (d) hydrogenase and PSI coimmobilized in Ca alginate.

Fig. 5. Time course of the photoactivated A. cylindrica PR.uK activity. The pure enzyme was photoactivated by preincubation in the light in the presence of TRX, Fd-TRX reductase, P. laminosum PSI particles and several electron donors and mediators, as described under Materials and Methods. Preincubation conditions complete system either in the dark for any time or in the light at zero time, or in the absence of Fd-TRX reductase after 30 min in the light (a) complete system in the light for 10 min, (b) 20 min, (c) 30 min, (d). The activity in (d) was 6.9 pmol of ribulose 1, 5-bisphosphate formed min-1 mg protein-1.

At more positive potentials two other secondary acceptors have been discovered. The first observation demonstrating the presence of an Fe-S center in PSI particles, reducible in light at cryogenic temperatures (10 °K) occurred simultaneously using ESR spectroscopy (center A, g = 2.05, 1.94 and 1.86) [60] and optical spectroscopy... 

Figure 7. A photovoltaic cell assemble consisting of a PSI particle bound membrane.

Residual moistures will be reduced in comparison to standard plate and frame units and RVF s by up to one-third, due to the high driving force created by the hydraulic membrane of up to 375 psi. Particles can be retained to one micron, which can eliminate the need for a precoat and save on waste disposal. As the cake developed in the pressure chamber is relatively even, and the wash delivered is also consistent, washing efficiency is high. (See Fig. 12.)... 

The lateral mobility of proteins and lipids in natural and artificial lipid bilayer membranes was determined by different methods. For long-range mobility, fluorescence recovery after photobleaching (13-15) and electrophoresis of membrane components (16) were employed. We employed the electrophoresis method for determination of the eletrophoretic and diffusional mobilities of PSI in the plane of hypotonically inflated, spherical thylakoid vesicles. To monitor the redistribution of PSI particles, we made use of the spatial characteristics of the contribution of PSI particles to electrophotoluminescence (EPL) (17, 18). The contribution of PSII to EPL was eliminated by heat treatment of the chloroplasts (19). The EPL originates from the PSI particles at the hemisphere of the vesicles at which the induced electrical field destabilizes the photoinduced charge separation (18). The electrophoretic and diffusional mobilities were measured in vesicular suspensions to avoid immobilization for microscopic visualization (20). The photosynthetic membranes are devoid of cytoskeletal elements that might interfere with the lateral mobility. 

Figure 2. Scheme of the experimental procedure. A, Electrophoretic propagation of PSI particles along the surface of the vesicle that causes accumulation on one pole and depletion on the other one. B, EPL from the depleted or the enriched (electrode signs in brackets) hemispheres. (Reproduced with permission from reference 20. Copyright 1989 Biophysical Society.)... 

In this theory the three original quark-antiquark pairs were supplemented by a fourtii pair - the charmed quark and its antiquark. The psi particle itself is a meson having zero charm as it consists of the charmed pair. However, charmed hadrons do exist they are said to possess naked charm. 

In November 1974 the discovery of the y (psi) particle initiated what later came to be Imown as the November revolution . At the time, any known hadron could be described as some combination of u, d, or s quarks. These hadrons were very short-lived with lifetimes of about 10 s. The ly particle, however, had a lifetime of lO s i.e. a thousand times longer. This suggested a com-... 

Figure 2. Polypeptide profile of thylakoids, PSII particles, PSI particles and solubilised virus (V). Plants were controls (mock infected (M)) or infected with PV42 (42) or PV230 (230) virus.

TABLE 1. The loss of NADP photoreduction activity and the maximal flash-Induced P700 absorption change In PSI particles prepared by anaerobic photolnhlblted chloroplasts. 

SDS-PAGE analysis of stroma lamellae and PSI-particles cross-linked with plastocyanin. 

PSI particles were produced by digitonin fragmentation of chloroplasts (7). The measurements were made using a 145 000 X g fraction precipitated after 100 000 x g. SDS-PAG electrophoresis of pigment-protein complexes of chloroplasts and PSI peirticles was performed by the method described (8). The radioactivity of the bands was meeisured on "Rackbeta" scintillation counter (LKB). The densitograms of separated chlorophyll-proteins were recorded by a DU-8 spectrophotometer (Beckman) at 675 urn. 

TABLE 3. Redistribution of chlorophyll in chlorophyll-protein complexis of PSI particles as a consequence of protein phosphorylation (P, phosphorylated ... 

Figure 1 Immunoblot of thylakoids, PSI particles, PSII particles and ChlPKl with rabbit anti-ChlPKl...

NEM-thylakoids 3,NEM-thylakoids+ChlPKl 4 Control thylakoids+ChlPKl 5 Control PSI particles 6, NEM-PSI particles 7 NEM-PSI particles+ChlPKl 8, PSI particles+ChlPKl... 

Porous Si-polymer composites may be designed in diverse configurations. Figure 1 schematically illustrates the most common structures PSi infiltrated with a poljoner, poljoner-coated PSi, polymer-capped PSi, released PSi film supported by a polymer, PSi particles encapsulated by a polymer, and composite microparticles. Each of these structures possesses different properties, which can be further refined by a proper choice of the polymer constituent and the PSi nanostructure. 

Another simple technique for preparation of PSi-polymer composites is by dispersing PSi particles within a molten poljoner or a polymeric solution (Fig. 2c). Further processing of these... 

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