Atmospheric visibility and PM10 as indicators of new particle formation in an urban environment

It is well-known that new particle formation (NPF) in the atmosphere is inhibited by pre-existing particles in the air that act as condensation sinks to decrease the concentration and, thus, the supersaturation of precursor gases. In this study, we investigate the effects of two parameters - atmospheric visibility, expressed as the particle back-scatter coefficient (BSP), and PM10 particulate mass concentration, on the occurrences of NPF events in an urban environment where the majority of precursor gases originate from motor vehicle and industrial sources. This is the first attempt to derive direct relationships between each of these two parameters and the occurrence of NPF. NPF events were identified from data obtained with a neutral cluster and air ion spectrometer over 245 days within a calendar year. Bayesian logistic regression was used to determine the probability of observing NPF as functions of BSP and PM10. We show that the BSP at 08 h on a given day is a reliable indicator of an NPF event later that day. The posterior median probability of observing an NPF event was greater than 0.5 (95%) when the BSP at 08 h was less than 6.8 Mm-1.

On the breakdown of the most probable distribution for mayer clusters

We present an analysis of the breakdown of the most probable approximation to the Mayer cluster size distribution for clusters of size comparable to the size of the system. This failure is illustrated by considering an ideal Bose gas for which exact volume dependent reducible cluster integrals are available.

Complexes of lanthanide perchlorates with two new O,N,O ligands derived from antipyraldehyde and acetic and benzoic acid hydrazides

Antipyrine is a well known ligand for lanthanides (I). A forage through the organic literature of pyrazolones reveals that the 4-position of antipyrine is amenable to a wide variety of organic reactions. It should thus be possible to introduce suitable functional groups at this position and design new multidentate ligands for metal ions. It is also found that the coordination chemistry of lanthanides is much less well developed and far fewer ligands have been used for complexation with lanthanide ions compared to that of the d-transition metal ions. Keeping these points in view we have reported earlier, complexes of lanthanides with a bidentate ligand N,N-diethyl-antipyrine-4-carboxamide (2). In this communication we report the synthesis of two new ligands from Schiff base condensation of antipyraldehyde and the hydrazides of acetic and benzoic acids and the complexes formed by these hydrazones with lanthanide perchlorates.

Insights into the growth of newly formed particles in a subtropical urban environment

The role of different chemical compounds, particularly organics, involved in the new particle formation (NPF) and its consequent growth are not fully understood. Therefore, this study was conducted to investigate the chemical composition of aerosol particles during NPF events in an urban subtropical environment. Aerosol chemical composition was measured along with particle number size distribution (PNSD) and several other air quality parameters at five sites across an urban subtropical environment. An Aerodyne compact Time-of-Flight Aerosol Mass Spectrometer (c-TOF-AMS) and a TSI Scanning Mobility Particle Sizer (SMPS) measured aerosol chemical composition (particles above 50 nm in vacuum aerodynamic diameter) and PNSD (particles within 9-414 nm in mobility diameter), respectively. Five NPF events, with growth rates in the range 3.3-4.6 nm, were detected at two of the sites. The NPF events happened on relatively warmer days with lower condensation sink (CS). Temporal percent fractions of organics increased after the particles grew enough to have a significant contribution to particles volume, while the mass fraction of ammonium and sulphate decreased. This uncovered the important role of organics in the growth of newly formed particles. Three organic markers, factors f43, f44 and f57, were calculated and the f44 vs f43 trends were compared between nucleation and non-nucleation days. K-means cluster analysis was performed on f44 vs f43 data and it was found that they follow different patterns on nucleation days compared to non-nucleation days, whereby f43 decreased for vehicle emission generated particles, while both f44 and f43 decreased for NPF generated particles. It was found for the first time that vehicle generated and newly formed particles cluster in different locations on f44 vs f43 plot and this finding can be potentially used as a tool for source apportionment of measured particles.

Doping Dependence of Semiconductor-Metal Transition in InP at High Pressures

The resistivity of selenium-doped n-InP single crystal layers grown by liquid-phase epitaxy with electron concentrations varying from 6.7 x 10$^18$ to 1.8 x 10$^20$ cm$^{-3}$ has been measured as a function of hydrostatic pressure up to 10 GPa. Semiconductor-metal transitions were observed in each case with a change in resistivity by two to three orders of magnitude. The transition pressure p$_c$ decreased monotonically from 7.24 to 5.90 GPa with increasing doping concentration n according to the relation $p_c = p_o [1 - k(n/n_m)^a]$, where n$_m$ is the concentration (per cubic centimetre) of phosphorus donor sites in InP atoms, p$_o$ is the transition pressure at low doping concentrations, k is a constant and $\alpha$ is an exponent found experimentally to be 0.637. The decrease in p$_c$ is considered to be due to increasing internal stress developed at high concentrations of ionized donors. The high-pressure metallic phase had a resistivity (2.02-6.47) x 10$^{-7}$ $\Omega$ cm, with a positive temperature coefficient dependent on doping.

ESR evidence for 2 coexisting liquid phases in deeply supercooled bulk water

Using electron spin resonance spectroscopy (ESR), we measure the rotational mobility of probe molecules highly diluted in deeply supercooled bulk water and negligibly constrained by the possible ice fraction. The mobility increases above the putative glass transition temperature of water, T-g = 136 K, and smoothly connects to the thermodynamically stable region by traversing the so called "no man's land" (the range 150-235 K), where it is believed that the homogeneous nucleation of ice suppresses the liquid water. Two coexisting fractions of the probe molecules are evidenced. The 2 fractions exhibit different mobility and fragility; the slower one is thermally activated (low fragility) and is larger at low temperatures below a fragile-to-strong dynamic cross-over at approximate to 225 K. The reorientation of the probe molecules decouples from the viscosity below approximate to 225 K. The translational diffusion of water exhibits a corresponding decoupling at the same temperature [Chen S-H, et al. (2006) The violation of the Stokes-Einstein relation in supercooled water. Proc Natl Acad Sci USA 103:12974-12978]. The present findings are consistent with key issues concerning both the statics and the dynamics of supercooled water, namely the large structural fluctuations [Poole PH, Sciortino F, Essmann U, Stanley HE (1992) Phase behavior of metastable water. Nature 360: 324-328] and the fragile-to-strong dynamic cross-over at approximate to 228 K [Ito K, Moynihan CT, Angell CA (1999) Thermodynamic determination of fragility in liquids and a fragile-tostrong liquid transition in water. Nature 398: 492-494].

Estimation Of Properties Of Rare-Gas Solids From Compression Characteristics Of Closed-Shell Ions

We present a unified approach to repulsion in ionic and van der Waals solids based on a compressible-ion/atom model. Earlier studies have shown that repulsion in ionic crystals can be viewed as arising from the compression energy of ions, described by two parameters per ion. Here we obtain the compression parameters of the rare-gas atoms Ne. Ar. Kr and Xe by interpolation using the known parameters of related equi-electronic ions (e.g. Ar from S2-. Cl-, K- and Ca2-). These parameters fit the experimental zero-temperature interatomic distances and compressibilities of the rare-gas crystals satisfactorily. A hightemperature equation of state based on an Einstein model of thermal motions is used to calculate the thermal expansivities, compressibilities and their temperature derivatives for Ar. Kr and Xe. It is argued that an instability at higher temperatures represents the limit to which the solid can be superheated. beyond which sublimation must occur.

Tetrahydroquinoxaline based squaraines: Synthesis and photophysical properties

Tetrahydroquinoxaline based squaraine dyes synthesized by the condensation reaction between squaric acid and different tetrahydroquinoxaline derivatives are described. The squaraines gave a strong intense peak at 700 nm and were found to exhibit good molar extinction coefficient (>105 M−1 cm−1). Metal binding studies were carried out with different metal ions and it was found that it was selective in the case of copper metal. Using Job's plot it was ascertained that the squaraines bind to the copper metal in the ratio of 2:1.

Portrait of Elisabeth, Queen of Belgium Portraits Women

Autographed dedication: An Margot Einstein in innigem Gedenken an ihrem Vater, meinem grossen and teueren Freund Albert Einstein. Herzlichst Elisabeth April 1956

Heats of reaction between aniline and formaldehyde by solution calorimetry: Reaction in neutral medium

The enthalpies of reaction between aniline and HCHO at various molar proportions under neutral conditions were determined by solution calorimetry. These measurements are new in the field of aniline and HCHO condensation polymers. The specific heats of the products formed were determined by differential scanning calorimetry and were used in the enthalpy calculations. Plots of enthalpy of reaction calculated with respect to aniline and HCHO vs. different A/F molar ratios were made. From the enthalpy data it appears that the reactions between different A/F molar ratios yield different products.

Amide-catalysed isomerisation of 5,6-dihydroisoquinolines: a novel synthesis of 1,2-dihydroisoquinolines

Knoevenagel condensation of 2-acylcyclohexanones or 2-ethoxycarbonylcyclohexanone with either cyanoacetamide or malononitrile followed by silver salt alkylation gave the 5,6,7,8-tetrahydroisoquinolines (3a–i). Chromic acid oxidation of the 5,6,7,8-tetrahydroisoquinolines (3a–i) to the corresponding tetralones (4a–i) followed by sodium borohydride reduction and p-toluenesulphonic acid-catalysed dehydration of the resulting alcohols (5a–i) gave the 5,6-dihydroisoquinolines (6a–i). Reaction of 5,6-dihydroisoquinolines (6a–g) with potassium amide in liquid ammonia gave a mixture of the 1,3-dihydroisoquinolines (7a–g) and the isoquinolines (8a–g). The C-1 unsubstituted 1,2-dihydroisoquinoline (7c) was found to be very unstable. In the case of the 5,6-dihydroisoquinolines (6h and 6i), reaction of potassium amide in liquid ammonia resulted in a mixture of 1-aminoisoquinoline (9) and the isoquinolines (8h and 8i). All the above compounds have been characterised by spectral data. A probable pathway for the formation of the 1,2-dihydroisoquinolines (7a–g) and the isoquinolines (8a–i) is suggested.

Specificity of protein - Nucleic acid interaction and the biochemical evolution

The water soluble carbodiimide mediated condensation of dipeptides of the general form Gly-X was carried out in the presence of mono- and poly-nucleotides. The observed yield of the tetrapeptide was found to be higher for peptide-nucleotide system of higher interaction specificity following mainly the anticodon-amino acid relationship (Basu, H.S. & Podder, S.K., 1981, Ind. J. Biochem. Biophys.,19, 251-253). The yield of the condensation product of L-peptide was more because of its higher interaction specificity. The extent of the racemization during the condensation of Gly-L-Phe, Gly-L-Tyr and Gly-D-Phe was found to be dependent on the specificity of the interaction -the higher the specificity, the lesser the racemization. The product formed was shown to have a catalytic effect on the condensation reaction. These data thus provide a mechanism showing how the specific interaction between amino acids/dipeptides and nucleic acids could lead to the formation of the lsquoprimitiversquo translation machinery.

Lichtenau, Baden; Jewish Community Collection 1985-1996

Clippings on the dedication of the memorial of the former Jewish community of Lichtenau held on April 13 1986; commemoration speech by Ilse Noel.

A convenient sample preparation protocol for scanning electron microscope examination of xylem-occluding bacterial biofilm on cut flowers and foliage

Microbes and their exopolysaccharides (EPS) can block xylem vessels, thereby increasing the hydraulic resistance and decreasing the vase life of cut flowers and foliage. Scanning electron microscopy (SEM) provides a powerful tool for investigation of bacteria-induced xylem occlusion. However, conventional preparation protocols for SEM involving chemicals can cause loss of hydrated EPS material, and thereby damage the bacterial biofilms during dehydration. A modified chemical fixation protocol involving pre-fixation with 75 mM lysine plus 2.5% glutaraldehyde followed by the normal fixation in 3% glutaraldehyde was, therefore, tested for improved preservation of bacterial biofilm at the stem-ends of cut Acacia holosericea foliage stems. Stem-end segments with different stages of bacterial growth were obtained from stems stood into water. The lysine-based protocol was compared with four other processing protocols of critical point drying (CPD) without fixation (control), freeze-drying (FD), conventional chemical fixation followed by drying with hexamethyldisilazane (HMDS), and conventional chemical fixation with CPD. The non-fixed control. FD and the glutaraldehyde fixation with HMDS drying gave poor preservation of hydrated material, including bacterial EPS. Conventional glutaraldehyde fixation followed by CPD was superior to these three methods in terms of better preserving the EPS. However, this fourth method gave condensation of biofilms during dehydration. In contrast, the modified lysine-based protocol resulted in superior preservation of EPS and biofilm structure. Thus, this fifth method was the most appropriate for examination of bacterial stem-end blockage in cut ornamentals. (C) 2012 Elsevier B.V. All rights reserved.