Control of Localized Single- and Many-Body Dark States in Waveguide QED.

Subradiant states in a finite chain of two-level quantum emitters coupled to a one-dimensional reservoir are a resource for superior photon storage and their controlled release. As one can maximally store one energy quantum per emitter, storing multiple excitations requires delocalized states, which typically exhibit fermionic correlations and antisymmetric wave functions, thus making them hard to access experimentally. Here we identify a new class of quasilocalized dark states with up to half of the qubits excited, which only appear for lattice constants of an integer multiple of the wavelength. These states allow for a high-fidelity preparation and minimally invasive readout in state-of-the-art setups. In particular, we suggest an experimental implementation using a coplanar waveguide coupled to superconducting transmon qubits on a chip. With minimal free space and intrinsic losses, virtually perfect dark states can be achieved for a low number of qubits featuring fast preparation and precise manipulation.

Sources and atmospheric processing of size segregated aerosol particles revealed by stable carbon isotope ratios and chemical speciation.

Size-segregated aerosol particles were collected during winter sampling campaigns at a coastal (55°37' N, 21°03'E) and an urban (54°64' N, 25°18' E) site. Organic compounds were thermally desorbed from the samples at different temperature steps ranging from 100 °C to 350 °C. The organic matter (OM) desorbed at each temperature step is analysed for stable carbon isotopes using an isotope ratio mass spectrometer (IRMS) and for individual organic compounds using a Proton Transfer Reaction Time-of-Flight Mass Spectrometer (PTR-MS). The OM desorbed at temperatures <200 °C was classified as less refractory carbon and the OM desorbed at temperatures between 200 °C and 350 °C was classified as more refractory carbon. At the coastal site, we identified two distinct time periods. The first period was more frequently influenced by marine air masses than the second time period, which was characterized by Easterly wind directions and continental air masses. During the first period OM contained a large fraction of hydrocarbons and had a carbon isotopic signature typical of liquid fossil fuels in the region. Organic mass spectra provide strong evidence that shipping emissions are a significant source of OM at this coastal site. The isotopic and chemical composition of OM during the second period at the coastal site was similar to the composition at the urban site. There was a clear distinction in source contribution between the less refractory OM and the more refractory OM at these sites. According to the source apportionment method used in this study, we were able to identify fossil fuel burning as predominant source of the less refractory OM in the smallest particles (D50 < 0.18 µm), and biomass burning as predominant source of the more refractory OM in the larger size range (0.32 < D50 < 1 µm).

Solubilization and stabilization of human liver glycoprotein sialyltransferase.

Triton X-100 is increasingly effective in solubilizing human liver glycoprotein (asialofetuin) sialytransferase (CMP-N-acetylneuraminate:D-galactosyl-glycoprotien N-acetylneuraminyltransferase, EC 2.4.99.1) activity as its concentration is increased in the homogenizing buffer. At the optimal concentration of 1.5% (v/v), essentially all of the homogenate sialyltransferase activity was solubilized into the supernatant fluid. Higher concentrations of Triton X-100 inhibited sialyltransferase activity. Several kinetic properties of the solubilized asialofetuin-sialyltransferase activity were compared to those of the membrane-bound enzyme(s) (in homogenates made without Triton X-100 or in resuspended pellets). No major difference was apparent, suggesting that solubilization has not significantly altered the properties of sialyltransferase. The solubilized sialyltransferase activity is quite unstable, losing approximately 50% of its activity after one week of storage at 4 degrees C. Various detergents (Zwittergent, sodium taurocholate and sodium deoxycholate) are differentially effective in stabilizing the solubilized activity. Sodium taurocholate (1.5%, w/v) was most effective with no loss in activity after 40 days and minimal loss (14%) after 60 days storage at 4 degrees C. The solubilized sialyltransferase preparation retains full activity after storage in the frozen state (-20 degrees C) for at least 159 days.

Glycohydrolases in diabetes: characterization of acid alpha-glucosidase from liver and neutral alpha-glucosidase from sera of diabetic patients and controls.

Acid alpha-glucosidase activity measured in the supernatant fraction of liver homogenates obtained from adult-onset diabetic patients is significantly decreased when compared to controls (2.86 +/- 1.18 and 5.79 +/- 1.82 nmoles/min/mg protein +/- S.D., respectively). The biochemical properties (Km values, thermostability, pH optimum, isoelectric focusing profiles) of acid alpha-glucosidase obtained from the livers of diabetic patients were similar to those of acid alpha-glucosidase obtained from the livers of controls. Mixing studies gave additivity of acid alpha-glucosidase activity suggesting that neither inhibitors nor activators are present (in diabetic and control livers, respectively). Neutral alpha-glucosidase activity measured in the sera of diabetic patients was significantly increased when compared to controls (4.35 +/- 1.82 and 2.44 +/- 1.05 nmoles/h/ml +/- S.D., respectively). Neutral alpha-glucosidase in the sera of diabetic and control patients has a similar pH optimum but the enzyme in the serum of diabetics has a slightly lower apparent Km value for the 4-methylumbelliferyl substrate (0.6 vs. 0.9 mmol/L) and slightly increased thermostability. Experiments involving dialysis of patient serum, addition of glucose to patient serum and mixing of control and diabetic patient sera all suggest that glucose exhibits only slight inhibition of serum neutral alpha-glucosidase activity. Isoelectric focusing indicates that neutral alpha-glucosidase activity in the sera of diabetic patients is consistently different from the enzyme in the sera of control patients in that a significantly smaller percentage of activity is found in the acidic region with pI values less than 4.8.

Activity levels and properties of acid alpha-glucosidase from liver and neutral alpha-glucosidase from sera of cystic fibrosis patients and controls.

The average activity levels of acid alpha-glucosidase are comparable in liver supernatant fluids for 15 cystic fibrosis patients and 12 controls (401 +/- 131 and 347 +/- 109 nmol/h/mg protein, respectively) and no significant differences were found for the cystic fibrosis and control liver acid alpha-glucosidases in their (a) apparent Km values for the 4-methylumbelliferyl substrate (1.1 mmol/l), (b) pH optima (4.2) and thermostability curves and (c) isoelectric profiles (one form with an isoelectric point of 4.5 +/- 0.2). In contrast, average neutral alpha-glucosidase activity levels were significantly increased (p less than 0.0002) in sera from 21 cystic fibrosis patients compared to 15 controls (10.7 and 2.7 nmol/h/ml). This increased activity is not due to (a) different stability upon storage at --20 degrees C, (b) the presence of activators in cystic fibrosis sera or inhibitors in normal sera (as determined by mixing studies), (c) altered Km values or (d) altered pH optima curves. Cystic fibrosis serum neutral alpha-glucosidase appears to be more thermostable and has a consistently altered isoelectric profile (greater percentage of activity above pI 4.8) when compared to the normal serum enzyme. This altered isoelectric composition may reflect changes in neutral alpha-glucosidase which contribute to its increased activity in cystic fibrosis sera.

Purification of human liver glycoprotein sialyltransferase by affinity chromatography.

A simple procedure has been developed for purifying solubilized human liver glycoprotein sialyltransferase (EC 2.4.99.1) 16000-fold in 4-5% yield. The procedure involves two centrifugation steps, affinity chromatography of the ultrasupernatant fluid on cytidine diphosphate-hexanolamine-agarose followed by gel filtration on Sephadex G-150. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) indicated that the purified sialyltransferase preparation contains approximately equivalent amounts of three protein bands (with apparent molecular weights of 61000, 63000 and 70000) and is highly purified if not homogeneous.

A plant chamber system with downstream reaction chamber to study the effects of pollution on biogenic emissions.

A system of two plant chambers and a downstream reaction chamber has been set up to investigate the emission of biogenic volatile organic compounds (BVOCs) and possible effects of pollutants such as ozone. The system can be used to compare BVOC emissions from two sets of differently treated plants, or to study the photochemistry of real plant emissions under polluted conditions without exposing the plants to pollutants. The main analytical tool is a proton-transfer-reaction time-of-flight mass spectrometer (PTR-TOF-MS) which allows online monitoring of biogenic emissions and chemical degradation products. The identification of BVOCs and their oxidation products is aided by cryogenic trapping and subsequent in situ gas chromatographic analysis.

Active atmosphere-ecosystem exchange of the vast majority of detected volatile organic compounds.

Numerous volatile organic compounds (VOCs) exist in Earth's atmosphere, most of which originate from biogenic emissions. Despite VOCs' critical role in tropospheric chemistry, studies for evaluating their atmosphere-ecosystem exchange (emission and deposition) have been limited to a few dominant compounds owing to a lack of appropriate measurement techniques. Using a high-mass resolution proton transfer reaction-time of flight-mass spectrometer and an absolute value eddy-covariance method, we directly measured 186 organic ions with net deposition, and 494 that have bidirectional flux. This observation of active atmosphere-ecosystem exchange of the vast majority of detected VOCs poses a challenge to current emission, air quality, and global climate models, which do not account for this extremely large range of compounds. This observation also provides new insight for understanding the atmospheric VOC budget.

Sialyltransferase, sialic acid and sialoglycoconjugates in metastatic tumor and human liver tissue.

1. The specific activities of sialytransferase in metastatic tumor sites were 5-37% of those of uninvolved non-cancerous tissue. The non-cancerous host tissues had a slightly lower average sialyltransferase activity than that of non-pathological control livers (986 vs 1194 dpm/min/mg protein). 2. The levels of total and bound sialic acid are increased 1.4 to 7.2-fold in homogenates, supernatants and resuspended pellets of metastatic tumor sites compared to non-cancerous and non-pathological control livers. For all these tissues, 24-29% of the bound sialic acid is found on soluble components (in the 16,300 g supernatant). 3. Soluble sialoglycoconjugates from most metastatic tumor sites give gel filtration profiles different from those of non-cancerous and non-pathological control livers.

Presence of an atypical thermolabile species of beta-hexosaminidase B in metastatic-tumour tissue of human liver.

An atypical thermolabile species of Hex B (hexosaminidase B) has been found in metastatic-tumour sites of human liver which has a thermostability curve similar to that of Hex A (hexosaminidase A), which is present in decreased amounts relative to the Hex A isoenzyme, and which exhibits decreased relative activity at acidic pH values (2.6-3.6) when compared with control-liver Hex B. This atypical Hex B isoenzyme has a normal apparent Michaelis constant (0.6 mM) for 4-methylumbelliferyl 2-deoxy-2-acetamido-beta-D-glucopyranoside. The presence of this atypical Hex B suggests that variant beta-chains are being produced in metastatic-tumour tissue.

Global air pollution crossroads over the Mediterranean.

The Mediterranean Intensive Oxidant Study, performed in the summer of 2001, uncovered air pollution layers from the surface to an altitude of 15 kilometers. In the boundary layer, air pollution standards are exceeded throughout the region, caused by West and East European pollution from the north. Aerosol particles also reduce solar radiation penetration to the surface, which can suppress precipitation. In the middle troposphere, Asian and to a lesser extent North American pollution is transported from the west. Additional Asian pollution from the east, transported from the monsoon in the upper troposphere, crosses the Mediterranean tropopause, which pollutes the lower stratosphere at middle latitudes.