Ultrahigh vacuum deposition of organic molecules by electrospray ionization

An electrospray apparatus for deposition of organic molecules on surfaces in ultrahigh vacuum is presented. The kinetic energy at the impact and mass to charge ratio of deposited ions can be controlled by an electrostatic quadrupole deflector and an in-line quadrupole mass spectrometer. With an ion funnel in the first two vacuum stages a high ion transmission is achieved. Experiments on porphyrin cations and deoxyribonucleic acid deposited on a Au(111) surface demonstrate the capabilities of the instrument.     

Synthesis and flash sintering of (Hf1-xZrx)B2 solid solution powders

(Hf_1-xZr_x)B₂ solid solution powders were synthesized by two methods. First, solution-based processing of HfCl₄, ZrCl₄, sucrose, and H₃BO₃ was conducted followed by heat treatment in Argon to carry out the carbothermal reduction (CTR) reaction to form the diboride powders. Alternatively, in the so-called borohydride reduction (BHR) method, HfCl₄, ZrCl₄ and NaBH₄ were mixed in an Argon glove box followed by heat treatment in Argon at 700?1500 °C. The synthesized powders were characterized by XRD, SEM, TEM, EDS, and TGA, and the influence of different parameters such as starting composition, heat treatment temperature and time on products characteristics were revealed. Both CTR and BHR solid solution powders were then consolidated within ～5 min in a homemade flash sintering (FS) setup. The composition, microstructure, hardness, and thermal-oxidation properties of flash sintered ceramics were characterized, and the implication of this study and directions for future research were discussed.     

Non-isothermal decomposition kinetics of nano-scale CaCO3 as a function of particle size variation

We report the synthesis of nanocrystalline calcium carbonate with varying particle sizes by precipitation techniques from an aqueous solution of calcium nitrate and sodium carbonate at controlled pH. The particle size of the carbonate powder was precisely controlled by changing the precursor concentration. The synthesized carbonate powders were characterized by using scanning electron microscopy, X-ray diffraction technique, and transmission electron microscopy. The particle size, along with the crystallite size of as-synthesized carbonate powder, decreases with increasing precursor concentration. The non-isothermal decomposition kinetics of the carbonate powder was also evaluated by using near to the modified Arrhenius equation's exact solution. The experimental results were best fitted at n = 0.5, and the one-dimensional diffusion-controlled transport process mechanism (D₁) and one-dimensional phase boundary movement mechanism (R₁) was found to be very close fit of the corresponding evaluated g(α) value. The apparent activation energy of the nano calcium carbonate decomposition was found in the range of 120–175 kJ/mol, which is also inherently functioning with the average particle size. The apparent activation energy of decomposition of CaCO₃ found to be decreased with decreasing average particle size of nanocrystalline calcium carbonate.     

Eco-Friendly Smokeless Al2O3-SiC-C Brick for Hot Metal Ladle

Hot metal transfer ladles were historically lined with high alumina refractories because of compatibility of high alumina refractories with the highly acidic slag, which is transferred .from the iron making plant along with hot metal. With the introduction of higher capacity ladles, technological advancement in the process and increased productivity, calls for a higher campaign life of hot metal ladles, which could not be performed by ordinary high alumina refractories. Resin bonded Al2O3- SiC-C （hereinafter ASC ） bricks gradually developed which at present taking place replacing the conventional refractories. Considerable work has been carried out in developing the ASC refractory to reach the present state. However, for higher capacity ladles still there is a lot of scope for improvement. The present paper deals with the newly developed ASC bricks, which was used in 165 ton capacity hot metal ladles in one European plant and has given a substantial increase in performance. But, the customer was not fuUy satisfied since the brick was reported to produce smokes during preheating of the ladle. In the subsequent supply the smoke generation problem was taken care by adjusting the binders and additives and eco-friendly bricks were re-engineered and supplied to the same plant, which also performed splendidly and created all time record in their plant history.     

Phage Display to Identify Nedd8‐Mimicking Peptides as Inhibitors of the Nedd8 Transfer Cascade

The Nedd8 activating enzyme (NAE) launches the transfer of the ubiquitin‐like protein Nedd8 through an enzymatic cascade to covalently modify a diverse array of proteins, thus regulating their biological functions in the cell. The C‐terminal peptide of Nedd8 extends deeply into the active site of NAE and plays an important role in the specific recognition of Nedd8 by NAE. We used phage display to profile C‐terminal mutant sequences of Nedd8 that could be recognized by NAE for the activation reaction. We found that NAE can accommodate diverse changes in the Nedd8 C‐terminal sequence (⁷¹LALRGG⁷⁶), including Arg and Ile replacing Leu71, Leu, Ser, and Gln replacing Ala72, and substitutions by bulky aromatic residues at positions 73 and 74. We also observed that short peptides corresponding to the C‐terminal sequences of the Nedd8 variants can be activated by NAE to form peptide～NAE thioester conjugates. Once NAE is covalently loaded with these Nedd8‐mimicking peptides, it can no longer activate full‐length Nedd8 for transfer to the neddylation targets, such as the cullin subunits of cullin‐RING E3 ubiquitin ligases (CRLs). We have thus developed a new method to inhibit protein neddylation by Nedd8‐mimicking peptides.     

Improved infrared photoluminescence characteristics from circularly ordered self-assembled Ge islands

The formation of circularly ordered Ge-islands on Si(001) has been achieved because of nonuniform strain field around the periphery of the holes patterned by focused ion beam in combination with a self-assembled growth using molecular beam epitaxy. The photoluminescence (PL) spectra obtained from patterned areas (i.e., ordered islands) show a significant signal enhancement, which sustained till 200 K, without any vertical stacking of islands. The origin of two activation energies in temperature-dependent PL spectra of the ordered islands has been explained in detail.     

Dextran–rare earth ion interactions. II. Solid‐state characteristics

The solid‐state characteristics of dextran complexes precipitated from aqueous solutions with three different light‐lanthanoid cations (La³⁺, Ce³⁺, and Nd³⁺) were investigated by spectroscopic and thermal methods. Spectroscopic characterization was realized by the comparative interpretation of the FTIR spectra, and the complexes were found to involve both ligating water and dextran through its O(2) and O(3) atoms. Remarkable spectral changes were noted, particularly with La³⁺, which parallels the previous solution studies. The order of La³⁺ > Ce³⁺ > Nd³⁺ was determined to display the tendency of the Ln³⁺ ion in favor of dextran throughout the competition between water and dextran. The thermal stabilities of the complexes were examined by thermogravimetry (TG), differential TG, and DSC methods. The decomposition steps and temperatures were assigned with respect to the lanthanoid ions used. The TG and DSC results indicated that the complexes are less stable thermally than dextran itself with increasing thermal stabilities in the order of La³⁺ < Ce³⁺ < Nd³⁺ in their anhydrous states. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2168–2174, 2002     

Structural characterisation and coloration of ligno-cellulose and protein fibre-blended structures

This study investigates the structures produced by blending ligno-cellulosic (ramie fibre, Boehmeria nivea L.) and protein fibres (mulberry silk, Bombyx Mori) with dissimilar mechanical properties. Ramie fibre, used for blending, is a ligno-cellulosic fibre with very high tenacity but low elongation. On the other hand, silk (mulberry) fibre has lower tenacity with better elongation. Blended fibrous structures have shown satisfactory tensile strength and elongation, while other physical properties, such as coefficient of friction, brightness and flexural rigidity, have also been improved. Technical findings revealed that the coefficient of friction reduced from 0.79 to 0.48 and specific work of rupture improved from 2.3 to 3.43 mJ/tex after incorporation of silk in the ligno-cellulosic fibre strand. Blended yarn cross-sectional images showed that finer silk fibres came to the surface, whereas the comparatively coarser cellulose-based ramie fibre migrated to the core. Atomic force microscopy of the blend structure was examined to assess the roughness and uniformity of the surface. Fourier Transform–infrared spectroscopy analysis verified the presence of amide groups (associated with silk fibre) and glucose ring groups (associated with the cellulose of Ramie fibre) in the same graph. In addition, innovative techniques of simultaneous coloration of the developed blends are also proposed scientifically.