Metal forming

Metal forming to make large parts, take large reductions, use high strength materials, work to net shape (precision flashless closed die forging), and use cold forming to obtain certain physical properties all require high forming forces. These forces may be larger than the capacity of existing machinery.

33p vcuong222 13-05-2015 55 4   Download

In this study, the effect of angle and length of copper made slope plate on the microstructure of A360-Aluminum alloy is investigated. Microstructure study of metallographic samples in different conditions revealed that for 400mm slope length and 60° slope angle the optimum sphierized and homogenized microstructure is achieved.

6p tohitohi 19-05-2020 12 0   Download

In this paper, an extended forming limit stress diagram (EFLSD) was applied to predict neck initiation failure in tube hydroforming of metal bellows. The proposed EFLSD was used in conjunction with ABAQUS/ EXPLICIT finite element simulations to predict the onset of necking in tube hydroforming of metal bellows.

10p tohitohi 19-05-2020 19 1   Download

Bioremediation presents a potentially low cost and environmentally agreeable alternative to current physico-chemical remediation strategies. However, heavy metals such as mercury cannot be converted into non-toxic forms by naturally occurring bacteria. Annual global emissions estimates for mercury released into the environment are in the thousands of tons per year [1,2] while the remediation cost is in the thousands of dollars per pound. Finding new bioremediation technologies is an urgent need.

8p zingzing09 24-04-2013 48 4   Download

The structure of peptidase T, or tripeptidase, was deter-mined by multiple wavelength anomalous dispersion (MAD) methodology and re®ned to 2.4 A Ê resolution. Pep-tidase T comprises two domains; a catalytic domainwith an active site containing two metal ions, and a smaller domain formed through a long insertion into the catalytic domain. The twometal ions, presumablyzinc, are separatedby3.3 AÊ , and are coordinated by ®ve carboxylate and histidine ligands.

8p research12 23-04-2013 31 4   Download

We studied the interaction of several metal ions with the copper chaperone fromEnterococcus hirae(EhCopZ). We show that the stoichiometry of the protein–metal complex varies with the experimental conditions used. At high con-centration of the protein in a noncoordinatingbuffer, a dimer, (EhCopZ)2–metal, was formed. The presence of a potentially coordinatingmolecule L in the solution leads to the formation of a monomeric ternary complex, EhCopZ– Cu–L, where L can be a buffer or a coordinatingmole-cule (glutathione, tris(2-carboxyethyl)phosphine). ...

11p dell39 03-04-2013 53 6   Download

H2 -forming methylenetetrahydromethanopterin dehydro-genase (Hmd) is an unusual hydrogenase present in many methanogenic archaea. The homodimeric enzyme dubbed
metal-free hydrogenase does not contain iron–sulfur clus-ters or nickel and thus differs from [Ni-Fe] and [Fe-Fe] hydrogenases, which are all iron–sulfur proteins. Hmd preparations were found to contain up to 1 mol iron per 40 kDa subunit, but the iron was considered to be a con-taminant as none of the catalytic and spectroscopic pro-perties of the enzyme indicated that it was an essential component....

10p dell39 03-04-2013 52 4   Download

Metal binding to the amyloidb-peptide is suggested to be involved in the pathogenesis of Alzheimer’s disease. We used high-resolution NMR to study zinc binding to amyloid b-peptide 1–40 at physiologic pH. Metal binding induces a structural change in the peptide, which is in chemical exchange on an intermediate rate, between the apo-form and the holo-form, with respect to the NMR timescale.

14p inspiron33 23-03-2013 50 6   Download

Vertebrate metallothioneins are found to contain Zn(II) and variable amounts of Cu(I),in vivo, and are believed to be important for d 10 -metal control. To date, structural information is available for the Zn(II) and Cd(II) forms, but not for the Cu(I) or mixed metal forms. Cu(I) binding to metallothionein-1 has been investigated by circular dichroism, luminescence and 1 H NMR using two synthetic fragments representing thea- and the b-domain.

14p galaxyss3 19-03-2013 34 5   Download

TheLactococcus lactisNRRL B-1821 prolidase gene was cloned and over-expressed in Escherichia coli. Under suboptimum growth conditions, recombinant soluble and active prolidase was produced; in contrast, inclu-sion bodies were formed under conditions preferred for cell growth.

10p media19 05-03-2013 44 2   Download

Molybdenum insertion into the dithiolene group on the 6-alkyl side-chain of molybdopterin is a highly specific process that is catalysed by the MoeA and MogA proteins in Escherichia coli. Ligation of molybdate to molybdopterin generates the molybdenum cofactor, which can be inserted directly into molybdoenzymes binding the molybdopterin form of the molybdenum cofactor,

12p vinaphone15 28-02-2013 34 1   Download

Alzheimer’s disease, a neurodegenerative disorder causing synaptic impair-ment and neuronal cell death, is strongly correlated with aggregation of the amyloid-bpeptide (Ab). Divalent metal ions such as Cu 2+ and Zn 2+ are known to significantly affect the rate of aggregation and morphology of Abassembliesin vitro and are also found at elevated levels within cerebral plaquesin vivo.

10p vinaphone15 25-02-2013 45 4   Download

The formation and structure of proinsulin C-peptide oligomers has been investigated by PAGE, NMR spectroscopy and dynamic light scattering. The results obtained show that C-peptide forms oligomers of different sizes, and that their formation and size distribution is altered by salt and divalent metal ions, which indicates that the aggregation process is medi-ated by electrostatic interactions.

10p viettel02 19-02-2013 40 3   Download

Complexometric titrations many metals form complex with a ligand: Cu++ + NH3 ⇔ Cu(NH3)++ Cu(NH3)2+ + NH3 ⇔ Cu (NH3)22+ Cu (NH3)22+ + NH3 ⇔ Cu (NH3)32+ Cu (NH3)32+ + NH3 ⇔ Cu (NH3)42+ Kf1 Kf2 Kf3 Kf4 Zn (NH3) complexes vs lg NH3 α .• theoretically could titrate Zn with ammonia • stepwise Kf very similar • difficult to know stoichiometry • to ensure all one form, need excess NH3 • titration never gives good equivalence point • can’t use monodentate ligand to titrate metals Titrations with EDTA • • • • use multidentate ligands e.g.

13p doilan 26-01-2013 42 3   Download

The aim of the study was to investigate the crystallization kinetics and solidification behaviour of Fe60Co8Mo5Zr10W2B15 bulk glass forming alloy. The solidification behaviour in near-equilibrium and non-equilibrium cooling conditions was studied. The eutectic and peritectic reactions were found to exist in the solidification sequence of the alloy. The bulk metallic glass formation was achieved by using two methods: quenching from the liquid state and quenching from the semi-state.

140p dontetvui 21-01-2013 83 12   Download

The iron responsive regulator Irr is found in a wide range ofa-proteobac-teria, where it regulates many genes in response to the essential but toxic metal iron. Unlike Fur, the transcriptional regulator that is used for iron homeostasis by almost all other bacterial lineages, Irr does not sense Fe 2+ directly, but, rather, interacts with a physiologically important form of iron, namely heme.

11p cosis54 05-01-2013 44 4   Download

A variety of organisms have been investigated to evaluate their potential as biological indicators of different forms of pollution in the aquatic environment (e.g. review by Gunkel 1994). Certain species have been identified as being highly sensitive either in their physiological response to aquatic contaminants or in their ability to accumulate particular toxins in a dose-time dependent manner.

8p nhoxden_20101991 13-06-2011 84 5   Download

The addition of clay in the form of bauxite refining residue (red mud) prior to composting has been suggested as a way to control heavy metal mobility in compost. Leachability and plant availability of metals in a mixture of grass clippings and sawdust spiked with metal solution was markedly reduced during the composting process.

7p tudoia 06-04-2011 103 8   Download

Carbonylation is one of the most important reactions leading to C-C bond formation. Direct synthesis of carbonyl compounds with CO gives rise to carboxylic acids and their derivatives, such as esters, amides, lactones, lactams etc. The process can be represented by the simple reactions of Scheme 5.1. In general, carbonylation proceeds via activation of a C-H or a C-X bond in the olefins and halides or alcohols, respectively, followed by COinsertion into the metal-carbon bond.

17p boyminsk 10-06-2010 121 13   Download