Recent advances

The main advances in air/gas dehydration have been in the areas of  

The tendency in dehydration construction and acid distribution materials is towards increased use of strongly corrosion resistant  

Both are simplifying initial construction, decreasing maintenance and extending plant life (Sulphur, 2004). 

1 brick lined carbon steel 1 brick lined steel 1 steel tower, 316L cone roof, brick lined 

Teflon Teflon mesh 6.7m dia. 0.15m thick Alloy 20-Teflon pad 

The main advances in air/gas dehydration have been in the areas of materials of construction and ceramic packing and packing supports (Louie, 2008). 

The tendency in ceramic packing is toward high surface area, low gas flow resistance perforated saddles (Fig. 6.6). These saddles give rapid dehydration with low resistance to gas flow. 

An alternative to saddle-type packing is structured packing. Stmctured packing is constructed of corrugated ceramic sheets and is supplied as shown in Fig. 6.7. Each structured packing unit is stacked in the tower and oriented to maximize efficiency. 

In addition, new tandem mass spectrometry technologies were also among the important innovations. Apart from traditional collision-induced dissociation (CID) [89-91], a variety of activation methods (used to add energy to mass-selected ions) based on inelastic collisions and photon absorption have been widely utilized. They include IR multiphoton excitation [92,93], UV laser excitation [94—97], surface-induced dissociation (SID) [98-100], black body radiation (101, 102], thermal dissociation [103], and others. As the fragmentation of peptide/protein ions is a central topic in proteomics, there is strong interest in such novel ion dissociation methods as electron capture dissociation (ECD) [104, 105] and electron transfer dissociation [22]. These new methods can provide structural information that complements that obtained by traditional collisional activation. Also, very recently, ambient ion dissociation methods such as atmospheric pressure thermal dissociation [106] and low temperature plasma assisted ion dissociation [107] have been reported. 

Ambient MS is another advance in the field. It allows the analysis of samples with little or no sample preparation. Following the introduction of desorption electrospray ionization (DESI) [108,109], direct analysis in real time (DART) [110], and desorption atmospheric pressure chemical ionization (DAPCI) [111, 112], a number of ambient ionization methods have been introduced. They include electrospray-assisted laser desorption/ionization (ELDI) [113], matrix-assisted laser desorption electrospray ionization (MALDESI) [114], atmospheric solids analysis probe (ASAP) [115], jet desorption ionization (JeDI) [116], desorption sonic spray ionization (DeSSI) [117], field-induced droplet ionization (FIDI) [118], desorption atmospheric pressure photoionization (DAPPI) [119], plasma-assisted desorption ionization (PADI) [120], dielectric barrier discharge ionization (DBDI) [121], and the liquid microjunction surface sampling probe method (LMJ-SSP) [122], etc. All these techniques have shown that ambient MS can be used as a rapid tool to provide efficient desorption and ionization and hence to allow mass spectrometric characterization of target compounds. 

Because of space limitation and the broad scope of the field, it is impractical to attempt to provide a comprehensive list of all recent advances in mass spectrometry. Nevertheless, there is no doubt that we will continue to see rapid development in all areas of mass spectrometry in the near future. 

Overview of the Study of lon/Molecule Reactions in the Gas Phase by Mass Spectrometry 

By using MCT, Leal-Calderon et al. [ 10] measured the total repulsive force between tiny colloidal droplets stabilized with sodium dodecyl sulfate (SDS) (Fig. 2.5). The measurements were performed for emulsions with three different concentrations 

In this expression, e is the dielectric permittivity of the suspending medium, is the electric surface potential, and k is the inverse Debye length [17], defined as  

Because the inverse Debye length is calculated from the ionic surfactant concentration of the continuous phase, the only unknown parameter is the surface potential i/io this can be obtained from a fit of these expressions to the experimental data. The theoretical values of FeQx) are shown by the continuous curves in Eig. 2.5, for the three surfactant concentrations. The agreement between theory and experiment is spectacular, and as expected, the surface potential increases with the bulk surfactant concentration as a result of the adsorption equilibrium. Consequently, a higher surfactant concentration induces a larger repulsion, but is also characterized by a shorter range due to the decrease of the Debye screening length. 

To account for their data (Fig. 2.7), Mondain-Monval et al. hypothesized that these two forces simply add and that the repulsion between micelles and droplets increases the effective diameter of the droplets (or micelles) [22]. This force is derived by integrating the osmotic pressure Posm over the accessible zone for micelles of diameter 2r (r = 2.35 nm) from 6 = n to 9 = 7t -Oi, with 9i defined in Fig. 2.6. The distance at which the small micelles are excluded from the gap between the droplets is evidently influenced by the electrostatic micelle-droplet repulsion. To account for this repulsion, droplets (or micelles) may be considered as particles of effective radius (a + S) [or micelles of radius (r + 5)]. From 

On the basis of this description, a relationship between the two lengths 8 and K can be established. Different 5 values are obtained by gradually increasing the amount of micelles and fitting the force profiles. The evolution of 5 as a function of the calculated Debye length is plotted in Fig. 2.8. The thickness 5 increases linearly with The inherent coupling between depletion and doublelayer forces is reflected by this empirical linear relationship which is a consequence of the electrostatic repulsion between droplets and micelles. The thickness 5 may be conceptually defined as a distance of closer approach between droplets and micelles and thus may be empirically obtained by writing  

Industrial membrane separators must have high surface area (SA) to volume (V) ratios. Conventional flat and tubular configurations have SA/V ratios of 30 and 250 m2 m-3, respectively [4, 216]. Therefore, membranes are being developed that address the requirement of assembly into compact, high-throughput modules. Spin-extruded ceramic hoUow fibers (diameter 1 mm) consisting of a-alumina coated with y-alumina were coated with 2 to 3 gm thick layers of palladium [184]. 

Some efforts involve supporting ultra-thin ( 1 gm) palladium films on various types of engineered porous supports. Perforated supports within modules have been fabricated and coated with thin layers of palladium alloys through micromachining and manufacturing techniques borrowed from the integrated circuit 

PSS composite membranes with an oxide interlayer have demonstrated stability for more than 6000 h at 350-450 °C [156]. 

Complex substrate modifications involving intermediate layers and palladium alloy deposition methods are often required for superior membrane performance. Modification of a membrane support surface before palladium deposition by sintering on smaller particles can create a smoother surface with smaller pores, facilitating the deposition of a defect-free palladium layer. Nickel microparticles have been sintered together to form a porous support that was sputter-coated with palladium and then copper [118]. Thermal treatment at 700 °C for 1 h promoted reflow to create a durable, pinhole-free membrane with a Pd-Cu-Ni alloy film. In another case, starting with commercially available PSS with a 0.5 pm particle filtration cut-ofF, submicron nickel particles were dispersed on the surface, vacnium sintered for 5 h at 800 °C, and then sputtered with UN [159]. The nickel particles created a smoother surface with smaller pores, so a thinner palladium alloy layer 

For a composite membrane that is relatively free of pinholes, there is apparently a limiting palladium thickness that depends primarily on support quaUty and somewhat on deposition method. For example, unmodified PSS requires at least 10 pm of palladium to bridge a majority of the pores [149, 227]. Invariably, a few macrodefects remain that preclude the attainment of perfect hydrogen permselectivity. On porous asymmetric a-alumina supports with 100-200 nm pore size on the surface, approximately 7 pm appears to be the limiting thickness that is proba- 

Moreover, developments in three areas are improving the geologist s ability to better qnantify available information and to better predict the position and distribution of coal seams between and beyond drill holes (1) improved geophysical techniques, (2) modeling of the deposition environments, and (3) manipulating available information with computer programs. 

Modeling of depositional environments is gradually becoming more accepted as a better means of predicting what happens to the coal seam and adjacent rocks beyond the outcrops and drill holes. Not only does it allow the geologist to extrapolate the presence and thickness of seams, but also to predict the rock type that overlies and underlies the coal. All of this information is important for mine planning. 

The area of modern coal exploration that has possibly seen the greatest change is in the collection and interpretation of geological data. An increased use of computers and accessories provides rapid handling of large amounts of data. Once the data are entered, the computer will construct a variety of maps, do statistical calculations, and tabulate requested information. Furthermore, the ability to handle vastly greater amounts of information coupled with the need for consistency has resulted in data collection standards that are much more rigorous than they were 25 years ago. 

Readily available geological data, accurate maps, and reasonable projections of reserves quality and quantity, all serve to reduce operational costs, assist in mine planning, and improve financial forecasts (Ruppert et al., 1999 Watson et al., 2001 Rohrbacher et al., 2005 Heriawan and Koike, 2008). Coal exploration has become a much more vital and valuable part of coal-mining operations and will continue to serve these needs in the future. 

The most economical method of coal extraction from coal seams depends on the depth and quality of the seams, the geology of the deposit, and environmental factors (Table 5.1). Coal-mining processes are differentiated by whether they operate on the surface or underground. Coal-mining operations 

The nonequilibrium anionic ROP of cyclosUoxanes exploits the reactive ring-strained cyclotrisiloxanes as monomers, and this allows the polymerization to be performed with minimal back-biting and chain randomization. The polymerization must be quenched soon after a high monomer conversion is obtained, in order to reduce the re-equilibration reactions that occur during the second stage of the process [13, 34]. In this particular issue, MALDI-ToF mass spectrometry has served as an important tool when studying the mechanism of polymerization of D3 initiated by sec-BuLi [35] and n-Bull [36], in THF. The technique also provides an accurate assessment of the polymer end-groups [35], 

The choice of a specific initiator or initiator/solvent system to eUminate the redistribution reactions is cmcial, and several means of achieving this have been explored  

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One of the more recent advances in XPS is the development of photoelectron microscopy [ ]. By either focusing the incident x-ray beam, or by using electrostatic lenses to image a small spot on the sample, spatially-resolved XPS has become feasible. The limits to the spatial resolution are currently of the order of 1 pm, but are expected to improve. This teclmique has many teclmological applications. For example, the chemical makeup of micromechanical and microelectronic devices can be monitored on the scale of the device dimensions. 

Some recent advances in stimulated desorption were made with the use of femtosecond lasers. For example, it was shown by using a femtosecond laser to initiate the desorption of CO from Cu while probing the surface with SHG, that the entire process is completed in less than 325 fs [90]. The mechanism for this kind of laser-induced desorption has been temied desorption induced by multiple electronic transitions (DIMET) [91]. Note that the mechanism must involve a multiphoton process, as a single photon at the laser frequency has insufScient energy to directly induce desorption. DIMET is a modification of the MGR mechanism in which each photon excites the adsorbate to a higher vibrational level, until a suflBcient amount of vibrational energy has been amassed so that the particle can escape the surface. 

Hase W L 1998 Some recent advances and remaining questions regarding unimolecular rate theory Acc. Chem. Res. 31 659-65... 

Marowsky G and Smirnov V N (eds) 1992 Coherent Raman Spectroscopy Recent Advances (Berlin Springer)... 

Many of the fiindamental physical and chemical processes at surfaces and interfaces occur on extremely fast time scales. For example, atomic and molecular motions take place on time scales as short as 100 fs, while surface electronic states may have lifetimes as short as 10 fs. With the dramatic recent advances in laser tecluiology, however, such time scales have become increasingly accessible. Surface nonlinear optics provides an attractive approach to capture such events directly in the time domain. Some examples of application of the method include probing the dynamics of melting on the time scale of phonon vibrations [82], photoisomerization of molecules [88], molecular dynamics of adsorbates [89, 90], interfacial solvent dynamics [91], transient band-flattening in semiconductors [92] and laser-induced desorption [93]. A review article discussing such time-resolved studies in metals can be found in... 

Reider G A and Heinz T F 1995 Second-order nonlinear optical effects at surfaces and interfaces recent advances Photonio Probes of Surfaoes ed P Halevi (Amsterdam Elsevier) pp 413-78... 

It is interesting to note the analogy of developments in light microscopy during the last few decades. The confocal microscope as a scaiming beam microscope exceeds by far the nomial fluorescence light microscope in resolution and detection level. Very recent advances in evanescent wave and interference microscopy seem to promise to provide even higher resolution (B1.18). 

Hansma H G, Sinsheimer R L, Groppe J, Bruice T C, Elings V, Gurley G, Bezanilla M, Mastrangelo I A, Hough P V C and Hansma P K 1993 Recent advances in atomic force microscopy of DMA Scanning 15 296... 

Yoshizawa H, Chen Y L and Israelachvili J N 1993 Recent advances in molecular level understanding of adhesion, friction and lubrication Wear 6B 161-6... 

However, recent advances in teclmiques will ensure fiirther diversification and complexification of solved surface structures. The present maturity of teclmiques will thus iucreasmgly allow the analysis of structures chosen for their practical interest rather than for their simplicity. 

Powell M J D 1971 Recent advances in unconstrained optimization Math. Prog. 1 26... 

Floudas C and Pardalos P M 1991 Recent Advances in Giobai Optimization (Princeton, NJ Princeton University Press)... 

Ausman K D, Benedetto A F, Samuelsand D A and Weisman R B 1998 Recent Advances in the Chemistry of Fuiierenes and Reiated Materiais(The Eiectrochemicai Society Proceedings Series) vol 6, ed K M Kadish and R S Ruoff (Pennington, NJ The Electrochemical Society) p 281... 

Schemes for classifying surfactants are based upon physical properties or upon functionality. Charge is tire most prevalent physical property used in classifying surfactants. Surfactants are charged or uncharged, ionic or nonionic. Charged surfactants are furtlier classified as to whetlier tire amphipatliic portion is anionic, cationic or zwitterionic. Anotlier physical classification scheme is based upon overall size and molecular weight. Copolymeric nonionic surfactants may reach sizes corresponding to 10 000-20 000 Daltons. Physical state is anotlier important physical property, as surfactants may be obtained as crystalline solids, amoriDhous pastes or liquids under standard conditions. The number of tailgroups in a surfactant has recently become an important parameter. Many surfactants have eitlier one or two hydrocarbon tailgroups, and recent advances in surfactant science include even more complex assemblies [7, 8 and 9].

To use direct dynamics for the study of non-adiabatic systems it is necessary to be able to efficiently and accurately calculate electronic wave functions for excited states. In recent years, density functional theory (DFT) has been gaining ground over traditional Hartree-Fock based SCF calculations for the treatment of the ground state of large molecules. Recent advances mean that so-called time-dependent DFT methods are now also being applied to excited states. Even so, at present, the best general methods for the treatment of the photochemistry of polyatomic organic molecules are MCSCF methods, of which the CASSCF method is particularly powerful. 

In this chapter, recent advances in the theory of conical intersections for molecules with an odd number of electrons are reviewed. Section II presents the mathematical basis for these developments, which exploits a degenerate perturbation theory previously used to describe conical intersections in nonrelativistic systems [11,12] and Mead s analysis of the noncrossing rule in molecules with an odd number of electrons [2], Section III presents numerical illustrations of the ideas developed in Section n. Section IV summarizes and discusses directions for future work. 

M A 1997. Recent Advances in Ligand Design Methods. In Lipkowitz K B and D B Boyd itors) Reviews in Computational Chemistry Volume 11. New York, VCH Publishers, pp. 1-66. 

Gresho, P. M., Lee, R. L. and Sani, R. L., 1980. On the time-dependent solution of the incompressible Navier-Stokes equations in two and three dimensions. In Recent Advances in Numerical Methods in fluids, Ch. 2, Pineridge Press, Swansea, pp. 27-75. 

Recent Advances in Density Functional Theory D. P. Chong, Ed., World Scientihc, Singapore (1995). 

The study of organic semiconductors and conductors is highly iaterdisciplinary, involving the fields of chemistry, soHd-state physics, engineering, and biology. This article provides a treatment of the theoretical aspects of organic semiconductors as well as an overview of recent advances ia the field and the uses of these materials based on their conductive and optical properties. 

J. Coleby in C. Hanson, ed.. Recent Advances in Eiquid—Eiquid Extraction, Pergamon Press, Oxford, UK, 1971. 

Recent advances in Eischer-Tropsch technology at Sasol include the demonstration of the slurry-bed Eischer-Tropsch process and the new generation Sasol Advanced Synthol (SAS) Reactor, which is a classical fluidized-bed reactor design. The slurry-bed reactor is considered a superior alternative to the Arge tubular fixed-bed reactor. Commercial implementation of a slurry-bed design requires development of efficient catalyst separation techniques. Sasol has developed proprietary technology that provides satisfactory separation of wax and soHd catalyst, and a commercial-scale reactor is being commissioned in the first half of 1993. 

F. Molesky in Recent Advances in Flame Retardamy of Polymeric Materials, Stamford, Coim., 1990 F. Molesky, "The Use of Magnesium Hydroxide for Flame Retarded Low Smoke Polypropylene," Polyolefins IHInternational Conference, Feb. 24,1991, Houston, Tex. 

D. Paul, "A New Phosphate Plasticizer for Low Smoke Wire and Cable AppHcations," paper presented at 3rd Annual BCC Conference on Recent advances in Flame Retardany of Polymeric Materials, Stamford, Conn., May 19—21,1992. 

E. D. Wed and A. M. Aaronson, "Phosphoms Flame Retardants— Some Effects on Smoke and Combustion Products," lecture at University of Detroit Polymer Conference on Recent Advances in Combustion and Smoke Retardance of Polymers, Mich., May 1976. 

Kinetic as weU as thermodynamic problems are encountered in fluorination. The rate of reaction must be decelerated so that the energy Hberated may be absorbed or carried away without degrading the molecular stmcture. The most recent advances in direct fluorination ate the LaMar process (18—20) and the Exfluot process (21—24), which is practiced commercially by 3M. 

S. B. Alpert and D. F. Spencer, Methanol and Eiquid Fuels From Coal—Recent Advances, Electric Power Research Institute, Palo Alto, Calif., 1987. 

J. P. Hanrahan, Recent Advances in Einimal Nutrition, Butterworths, London, 1986, pp. 125—138. 

J. Scott, ed.. Membrane and Ultrafiltration Technology 1980, Recent Advances, Chemical Technology Review No. 147, Noyes Data Corp., Park Ridge, N.J.,... 

P. W. Lenz, Recent Advances in Fiquid Crystalline Polymers, Elsevier Apphed Science Pubhshets, Denmark, 1983. 

T. Hogen-Esch andj. Smid, eds.. Recent Advances in Anionic Polymerisation, Elsevier, New York, 1987. 

E. N. Cogswell, ia L. L. Chapoy, Recent Advances in Eiquid Cystalline Polymers, Elseviei, New Yoik, 1985. 

Future Developments. The most recent advance in detergent alkylation is the development of a soHd catalyst system. UOP and Compania Espanola de Petroleos SA (CEPSA) have disclosed the joint development of a fixed-bed heterogeneous aromatic alkylation catalyst system for the production of LAB. Petresa, a subsidiary of CEPSA, has announced plans for the constmction of a 75,000 t/yr LAB plant in Quebec, Canada, that will use the UOP / -paraffin dehydrogenation process and the new fixed-bed alkylation process (85). 

B. V. Voia, P. R. Pujado, T. Imai, and T. R. Fritsch, Recent Advances in the Production of Detergent Olefins and Pinear Alkylbenyenes, Society of Chemical Industry, University of Cambridge, England, Mar. 26—28, 1990. 

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