Collagen structure changes during chrome tanning in propylene carbonate

The pancreas of cow was applied as bating agent for wet-salted scrotum skins of goat. The bated skins were then applied with vetetable tanning, chrome-agent and the combination of both agents. The tanned skins were analyzed their tensile strength and elasticity. The results showed that there were significant differencis on those parameters. The tensile strength and elasticity of chrome tanned, vegetable tanned, and the combination of chrome and vegetable tanned-skins were 107,75 kg/cm 2 and 100,5%; 56,83 kg/cm 2 and 27,83 %; and 52,28 kg/cm 2 and 55,67% respectively. The tensile strength and elasticity of tanned skins indicated a tendency to increase when the concentration of cow pancreas was increased up to 1.5 % and decreased when the concentration reaches 2 % for chrome tanned skins. Keywords : cow pancreas, goat scrotum skin, vegetable tanning, chrome tanning.

Nanoparticles due to their size and high reactivity towards collagen provide potential applications in the tanning process. The current study aims to investigate the potential of ionic liquid functionalized cerium oxide nanoparticles as a combination tanning agent with minimum utilization of the chromium. The experimental results indicate that the presence of nanoparticles increases the thermal stability from 62°C to 92°C. The physical strength and organoleptic characteristics of the nanoparticles-BCS tanned leather are on par with conventional chrome tanned leather. Antibacterial studies reveal that the leather tanned with nanoparticles shows improved antibacterial activity. Thus, nanoparticle based tanning system invokes a considerable array of interest as an alternative tanning process with minimal and efficient usage of chromium.

Several bacterial solute transport mechanisms involve members of the periplasmic binding protein (PBP) superfamily that bind and deliver ligand to integral membrane transport proteins in the ATP-binding cassette, tripartite tricarboxylate transporter, or tripartite ATP-independent (TRAP) families. PBPs involved in ATP-binding cassette transport systems have been well characterized, but only a few PBPs involved in TRAP transport have been studied. We have measured the thermal stability, determined the oligomerization state by small angle x-ray scattering, and solved the x-ray crystal structure to 1.9 A resolution of a TRAP-PBP (open reading frame tm0322) from the hyperthermophilic bacterium Thermotoga maritima (TM0322). The overall fold of TM0322 is similar to other TRAP transport related PBPs, although the structural similarity of backbone atoms (2.5-3.1 A root mean square deviation) is unusually low for PBPs within the same group. Individual monomers within the tetrameric asymmetric unit of TM0322 exhibit high root mean square deviation (0.9 A) to each other as a consequence of conformational heterogeneity in their binding pockets. The gel filtration elution profile and the small angle x-ray scattering analysis indicate that TM0322 assembles as dimers in solution that in turn assemble into a dimer of dimers in the crystallographic asymmetric unit. Tetramerization has been previously observed in another TRAP-PBP (the Rhodobacter sphaeroides alpha-keto acid-binding protein) where quaternary structure formation is postulated to be an important requisite for the transmembrane transport process.

Single-Crystalline Mesoporous Palladium and Palladium-Copper Nanocubes for Highly Efficient Electrochemical CO ₂ Reduction

Toward environment-friendly composites of poly(propylene carbonate) reinforced with cellulose nanocrystals

Characterization of water/sodium bis(2-ethylhexyl) sulfosuccinate/sodium bis(amyl) sulfosuccinate/ n-heptane mixed reverse micelles and w/o microemulsion systems: The influence of water and sodium bis(amyl) sulfosuccinate content

Raman spectroscopy can detect conformational changes in collagen structures and these findings are reviewed in this article. More specifically, some progressive diseases are mainly caused by alterations of collagen molecules but what is occurring at the biochemical level of this complex molecule usually remains unclear. While it may be true that a number of analytical techniques can analyze collagen, most of them have a series of limitations that limit their applicability to a wide range of samples. To understand in more detail the progression of a disease due to changes in the collagen structure, a technique that can detect subtle alterations at the biochemical level is needed. Raman spectroscopy is a label-free and noninvasive technique that can easily pick up on any conformational changes reflected primarily at the lipids, amides and proline and hydroxyproline regions. This review is the first compilation of studies of conformational changes in collagen molecules, providing help to understand changes in collagen biochemistry that can be of relevance to the human wound healing, ageing and pathologies.

Carbonaceous feeds, such as oil, gas, and coal, can be catalytically converted to useful products. Many of these reactions are conducted under harsh conditions, where the metal catalysts will rapidly sinter and lose activity. Overcoating is a methodology which preserves catalyst integrity under reaction conditions by depositing protective layers around the catalysts. Recently, we show that overcoating the metal nanoparticles with alumina using atomic layer deposition (ALD) will reduce the sintering and coking while the lifetime and reactivity of catalyst increase dramatically compared to the catalyst without ALD overcoating. It is believed that nano-sized pore (less than 2 nm) was formed during the calcination of ALD overlayer at high temperature. However, the mechanism of pore formation is still poorly understood due to the limited characterization technique.Understanding the mechanism of the pore formation and further controlling the pore size are crucial for the development of the ALD overcoated catalyst. Recently, we demonstrated that small angle X-ray scattering (SAXS) can be used to characterize these ALD overcoated catalysts. From SAXS analysis, the thermal treatment resulted in the formation of ~ 3.5 nm pores. Moreover, the evolution of pore size was monitored by in situ SAXS technique. The pore size increases with increasing annealing temperature. In this proposal, we aim to investigate the mechanism of pore formation during the calcination using in situ SAXS as well as wide angle X-ray scattering, to understand how the ramping rate, gas used, nature of supports and overcoated materials affect the formation of the pore.

For commercial leather processing, chrome tanning is the most used approach but it significantly contributes to environmental pollution. Vegetable tannins, which are large polyphenolic compounds, form strong interactions with proteins and carbohydrates, thereby enhancing the adaptability and value of vegetable-tanned leather as well as reducing environmental impact. In this study, vegetable tannins were extracted from the leaves of Guava plants (Psidium guajava) using ethanol as the solvent, facilitated by ultrasound. Extracted tannins were quantified using the Folin–Ciocâlteu reagent with ultraviolet-visible spectroscopic method. Ultrasound enhanced the extraction process producing a high yield in less time due to its mechanical, thermal, and cavitation impacts. The extracted tannins were characterized by a variety of spectroscopic techniques, including Proton (1H) Nuclear magnetic resonance, Fourier-transform infrared, and ultraviolet-visible spectroscopy. The effect of various process variables, such as temperature, solid-liquid ratio, ultrasonic power, extraction period, and powder fineness, were also investigated to optimize the extraction process. Finally, the extracted tannins were employed in leather tanning processes to assess their potential as tanning agents. The extracted tannins ensured uniform diffusion of tannins, improved thermal stability and reduced the number of tannins in effluent by 68% making it an environmentally friendly leather tanning process.

The growth mechanism and kinetics of mesoporous silica nanoparticles (MSNs) were investigated for the first time by using a synchrotron time-resolved small-angle X-ray scattering (SAXS) analysis. The synchrotron SAXS offers unsurpassed time resolution and the ability to detect structural changes of nanometer sized objects, which are beneficial for the understanding of the growth mechanism of small MSNs (∼20 nm). The Porod invariant was used to quantify the conversion of tetraethyl orthosilicate (TEOS) in silica during MSN formation, and the growth kinetics were investigated at different solution pH and temperature through calculating the scattering invariant as a function of reaction time. The growth of MSNs was found to be accelerated at high temperature and high pH, resulting in a higher rate of silica formation. Modeling SAXS data of micelles, where a well-defined electrostatic interaction is assumed, determines the size and shape of hexadecyltrimethylammonium bromide (CTAB) micelles before and after the addition of TEOS. The results suggested that the micelle size increases and the micelle shape changes from ellipsoid to spherical, which might be attributed to the solubilization of TEOS in the hydrophobic core of CTAB micelles. A new "swelling-shrinking" mechanism is proposed. The mechanism provides new insights into understanding MSN growth for the formation of functional mesoporous materials exhibiting controlled morphologies. The SAXS analyses were correlated to the structure of CTAB micelles and chemical reaction of TEOS. This study has provided critical information to an understanding of the growth kinetics and mechanism of MSNs.

Characterization of metal nanoparticles prepared by photoreduction in aqueous solutions of various surfactants using UV–vis, EXAFS and SAXS

The mechanism of nanoparticle formation during reverse sequence polymerization-induced self-assembly (PISA) is studied by small-angle X-ray scattering (SAXS). More specifically, N,N'-dimethylacrylamide (DMAC) monomer is added to a trithiocarbonate-capped poly(ɛ-caprolactone) (PCL) precursor and initially polymerized in the bulk at 80°C via reversible addition-fragmentation chain transfer (RAFT) polymerization. SAXS indicates the unexpected formation of molten PCL droplets dispersed within DMAC monomer. After 5min (14% DMAC conversion) at 80°C, the reaction mixture is diluted with water, and the aqueous milieu is analyzed using a flow cell. A transient lamellar phase is formed immediately after water addition that subsequently transforms into nascent spherical nanoparticles. During the remaining DMAC polymerization, the overall nanoparticle diameter remains essentially constant with a concomitant reduction in the PCL core radius and the aggregation number. This suggests that individual PCL-PDMAC chains are in equilibrium with the nanoparticles. SAXS analysis indicates that the amorphous PCL cores have a mean diameter of 8.8nm at 80°C: X-ray diffraction (XRD) studies confirm that such nanoscale confinement prevents their crystallization on cooling to 20°C. Finally, this formulation can be combined with crystallization-driven self-assembly (CDSA): UV-initiated DMAC polymerization at 15°C produces rod-like PCL-PDMAC nanoparticles with semicrystalline PCL cores.

Study of bioaccumulation and biotransformation by microanalytical X-ray techniques: investigation of distribution and speciation of Cu and Cr in the body of the plant-feeding nematode, Xiphinema vuittenezi

Nanoporous layered silicate AMH-3/cellulose acetate nanocomposite membranes for gas separations

Synthesis of anisotropic silver nanostructures in presence of polyvinyl pyrrolidone (PVP): LSPR and SAXS analysis