Formic Acid Treatment Research Articles

A Combined Process of Formic Acid Pretreatment for Low-Temperature Bonding of Copper Electrodes

A new combined process of formic acid pretreatment for low temperature Cu direct bonding was proposed. Cu film and Cu micro-electrodes samples were treated by formic acid and successfully bonded together at 200°C. Cu surface oxide was reduced at 200°C using formic acid treatment without/with Pt catalyst. Particularly, the treatment with heated Pt catalyst is more effective for Cu surface reduction than that without Pt catalyst or with room temperature Pt catalyst. After formic acid treatment under various conditions, Cu film and Cu micro-electrodes samples were bonded together at 200°C in N2. Among them, the bonded samples treated by formic acid using heated Pt catalyst showed the strongest bonding strength. Very few oxide and carbon was remained at the bonding interface. It also proves that the treatment can reduce surface oxide resulting in strong bonding at low temperature.

Lactobacillus plantarum effects on silage fermentation and in vitro microbial yield

In four parallel experiments, herbage [three harvests of alfalfa (308 to 379g dry matter (DM)/kg), one of whole-plant corn (331g DM/kg)] was ensiled with three different treatments: no inoculant (control), Lactobacillus plantarum (LP) or formic acid (FA), in 1-L mini-silos and fermented for 60d at room temperature (22°C). Mini-silos were opened and analyzed for fermentation characteristics and soluble N fractions. A subsample of wet silage from each mini-silo was ground to 4mm and stored at −20°C. Silages were thawed and subjected to 9h ruminal in vitro incubations to measure gas production and volatile fatty acid (VFA) production as well as microbial biomass yield (MBY) and microbial non-ammonia N (MNAN) formation using 15N as a marker. In all four experiments, silage fermentation products and pH indicated good preservation across all treatments. Analysis of data showed that FA- and LP-treated silages had lower concentrations of ammonia-N and free amino acids N than control. The FA treatment was lower in soluble N, but higher in peptide-N, than control. Silage pH was lowest in FA (4.25), followed by LP (4.28), and control (4.38). Ruminal in vitro gas production and VFA concentrations were not different among treatments (P>0.05). Compared to control, FA- and LP-treated silage yielded greater MNAN and MBY. These findings suggested that L. plantarum preserved more true protein during silage fermentation than control, which in turn increased in vitro ruminal microbial growth.

ChemInform Abstract: Bright White Light Emission from Ultrasmall Cadmium Selenide Nanocrystals.

AbstractThe fluorescence quantum yield of ultrasmall white‐light emitting CdSe nanocrystals is increased from 8% to 45% by formic acid treatment.

Involvement of astrocytes in transmissible spongiform encephalopathies: a confocal microscopy study

Astroglial proliferation associated with pathological prion protein (PrPsc) deposition is widely described in Transmissible Spongiform Encephalopathies (TSEs). However, little is known of the actual role played by glia in their pathogenesis. The aim of the study has been to determine whether PrPsc is located exclusively in neurons or in both neurons and glial cells present in the central nervous system in a natural Scrapie model. Samples of cerebellum from 25 Scrapie sheep from various flocks were sectioned. Following epitope retrieval with formic acid, proteinase K and heat treatment, primary antibody L42 and primary antibodies against glial fibrillary acidic protein were applied as prion- and astrocytic-specific markers, respectively. For visualization, a suitable mixture of fluorochrome-conjugated secondary antibodies was used. Relevant controls were processed in the same manner. As determined by confocal microscopy, PrPsc deposits co-localized with glial cells in all samples. Our results suggest that these cells can sustain active prion propagation, in agreement with similar findings from other studies of primary cell cultures and inoculated mice. Furthermore, despite ongoing debate regarding whether varied TSE sources show differences in their tropism for different cell lineages in the brains of affected animals, no differences in co-localization results were seen.

Enhanced Antigen Retrieval of Amyloid β Immunohistochemistry

Senile plaques, extracellular deposits of amyloid β peptide (Aβ), are one of the pathological hallmarks of Alzheimer disease (AD). As the standard immunohistochemical detection method for Aβ deposits, anti-Aβ immunohistochemistry combined with antigen retrieval (AR) by formic acid (FA) has been generally used. Here, we present a more efficient AR for Aβ antigen. On brain sections of AD and its mouse model, a double combination of either autoclave heating in EDTA buffer or digestion with proteinase K plus FA treatment reinforced Aβ immunoreactivity. A further triple combination of digestion with proteinase K (P), autoclave heating in EDTA buffer (A), and FA treatment (F), when employed in this order, gave a more enhanced immunoreactivity. Our PAF method prominently visualized various forms of Aβ deposits in AD that have not been clearly detected previously and revealed numerous minute-sized plaques both in AD and the mouse model. Quantification of Aβ loads showed that the AR effect by the PAF method was 1.86-fold (in the aged human brain) and 4.64-fold (in the mouse brain) higher than that by the FA method. Thus, the PAF method could have the potential to be the most sensitive tool so far to study Aβ pathology in AD and its mouse model.

Toxicity Mechanism of Formic Acid is Directly Linked to ROS Burst and Oxidative Damage in Yeast <i>Saccharomyces cerevisiae</i>

In this paper the survival rate of Saccharomyces cerevisiae cells after the formic acid treatment of different concentration was determined firstly, and cells of Saccharomyces cerevisiae were labeled with fluorescent probes of reactive oxygen species (ROS) and treated with formic acid, then intracellular reactive oxygen species was detected with confocal microscopy and flow cytometer. The results show that formic acid can lead to the rapid burst of intracellular reactive oxygen species. We speculated that the outbreak of the formic acid-induced reactive oxygen species and corresponding oxidative damage is the leading cause of the yeast cells death.

포름산에서 고온 및 초음파 처리가 양모의 스케일 제거와 섬유분할화에 주는 영향

In this study, normal and dichlorodicyanuric acid (DCCA)-treated wool slivers and yarns were immersed in a formic acid solution at elevated temperatures as a pre-treatment in order to accelerate the scale removal and fiber splitting of wool by ultrasonication and the effect of pre-treatment on the morphology and fiber splitting of wools was investigated. As the formic acid concentration, the treatment temperature, and the treatment time increased, the scale removal on wool fiber increased, however, the occurrence of felting and yellowing regarding wool fiber also increased indicating that the treatment with 50% formic acid at for 3 hours was the optimum pre-treatment condition for wool fiber. The SEM observation revealed that the formic acid treatment on wool at followed by ultrasonication was the effective tool in order to produce split fibers for both normal and DCCA-treated wool. The comparative study of sliver and yarn revealed that ultrasonication could lead to the fiber splitting of wool sliver whereas it could not result in that of wool yarn. On the other hand, formic acid treatment at resulted in fiber splitting for both wool sliver and yarn.

Effect of Adding Various Organic Acids During the Feed Withdrawal Period on Salmonella Reduction in Broilers

3 Abstract: Salmonella contamination of broilers is a major problem that faces the poultry industry in Kuwait and elsewhere since it affects the consumption of poultry meat. Therefore, utilization of different control measures leading to the reduction of Salmonella contamination is an important task for the broiler industry and the public health authorities in Kuwait. An important strategy is to significantly reduce the levels of Salmonella at the farm level and improve the manufacturing practices in the processing plant to prevent the risk of cross contamination. In our Department, different treatments have been used to control the contamination of this pathogen at the farm level, one of which is presented in the current study. The objective of the current study is to determine the effect of using different organic acids in the drinking water during the feed withdrawal period on reducing Salmonella in broilers. One hundred and twenty broiler chicks were originally housed in each of 36 floor pens. At the time of feed withdrawal, the pens were divided into four groups of nine pens each and were used for one of four treatments. These treatments included the control group and received untreated water, the second group received water containing 0.1% acetic acid, the third group received water containing 0.1% formic acid and the fourth group received water containing 0.1% lactic acid for a period of eight hrs. This study was repeated both in the summer and winter seasons. The prevalence of Salmonella on the chicken body, ceca and in the crop was determined before and post treatment at the farm and then at the processing plant. In addition to reducing body Salmonella contamination significantly (p<0.05) post treatment at the farm, in both seasons, it was found that acid treatments, in the summer season, significantly (p<0.05) reduced Salmonella contamination in the carcass at the processing plant from 36% (control) to 16, 13, 13% for acetic, formic and lactic acid treatments, respectively. In the winter season, both formic and lactic acid treatments reduced Salmonella contamination in the carcass at the processing plant and the reduction was significant (p<0.05) for formic acid treatment. It can be co ncluded that using organic acids in the water during the feed withdrawal period, both in th e summer and winter seasons, can be beneficiary in reducing broiler Salmonella contamination both at the farm and at the processing plant.

Islet amyloid polypeptide in pancreatic islets from type 2 diabetic subjects

Aims/hypothesis: Islet amyloid polypeptide (IAPP) is a chief constituent of amyloid deposits in pancreatic islets, characteristic histopathology for type 2 diabetes. The goal of this study was to analyze islet cell composition in diabetic islets for the process of transforming water-soluble IAPP in β-cells to water-insoluble amyloid deposits by Immunocytochemical staining using different dilutions of anti-IAPP antibody. IAPP in β-cell granules may initiate β-cell necrosis through apoptosis to form interstitial amyloid deposits in type 2 diabetic islets. Results: Control islets revealed twice as much β-cells as α-cells whereas 15 of 18 type 2 diabetic cases (83%) revealed α- cells as major cells in larger islets. Diabetic islets consisted of more larger islets with more σ-cells than β-cells, which contribute to hyperglucagonemia. In control islets, percentage of IAPP-positive cells against β-cells was 40–50% whereas percentage for type 2 diabetic islets was about 25%. Amyloid deposits in diabetic islets were not readily immunostained for IAPP using 1: 800 diluted antibody, however, 1: 400 and 1: 200 diluted solutions provided stronger immunostaining in early stages of islet amyloidogenesis after treating the deparaffinized sections with formic acid. Methods: Using commercially available rabbit antihuman IAPP antibody, immunocytochemical staining was performed on 18 cases of pancreatic tissues from type 2 diabetic subjects by systematically immunostaining for insulin, glucagon, somatostatin (SRIF) and IAPP compared with controls. Sizes of islets were measured by 1 cm scale, mounted in 10X eye piece. Conclusions/Interpretation: α cells were major islet cells in majority of diabetic pancreas (83%) and all diabetic islets contained less IAPP-positive cells than controls, indicating that IAPP deficiency in pancreatic islets is responsible for decreased IAPP in blood. In diabetic islets, water-soluble IAPP disappeared in β-cell granules, which transformed to water-insoluble amyloid deposits. Amyloid deposits were not readily immunostained using IAPP 1: 800 diluted antibody but were stronger immunostained for IAPP in early stages of amyloid deposited islets using less diluted solutions after formic acid treatment. In early islet amyloidogenesis, dying β-cell cytoplasm was adjacently located to fine amyloid fibrils, supporting that IAPP in secretary granules from dying β cells served as nidus for islet β-sheet formation.

The influence of formic acid on the body surface proteolytic system at different developmental stages in Apis mellifera L. workers

SummaryTo verify the hypothesis that formic acid (FA) has a suppressive effect on the proteolytic system of Apis mellifera cuticle depending on the developmental stage of the insects, 1 to 4-day-old larvae, 8-day-old larvae, pupae, 1-day-old workers, and foragers were sampled from FA- treated and untreated colonies for seven weeks. Hydrophilic (H+) and hydrophobic protein (H-) solutions were washed out from the sampled individual body surfaces. Subsequently, protein concentration, protease activities and protease inhibitor activities were determined. Antifungal and antibacterial activities were also determined. Two-week exposure to FA increased H+ and H- protein concentration but when it was prolonged to three to seven weeks, the concentration fell below the level of untreated colonies. FA treatment decreased H+ protease activities in workers and larvae, but increased them in pupae. H- protease activities oscillated (destabilisation) up and down relative to the control level which was steady. Asparagine and serine proteases were present on apian cuticles independently of the developmental stage, while FA application additionally activated thiolic proteases. FA treatment considerably decreased both H+ and H- natural protease inhibitor activities in larvae and pupae but mostly increased them in workers. Antifungal and antibacterial activities of the body surface washings (in vivo microbiological tests) were suppressed in workers and larvae treated with FA. FA treatment may suppress proteolytic resistance of the bee cuticle but the responses of larvae and workers are different.

Discovery of Silurian sponge spicules from the Argentine Precordillera

An association of silicified spicules of hexactinellid sponges was collected from Silurian sandstones at the top of the La Chilca Formation, cropping out at Cerro del Fuerte, 20 km east of Jáchal, in the San Juan Precordillera of west‐central Argentina. This is the first occurrence of a Silurian spicule fauna recorded at higher palaeolatitudes from Argentina and the entire South American part of Gondwana. The spicules were extracted by means of formic acid treatment from sandstones of the uppermost part of the La Chilca Formation, which ranges in age from the late Hirnantian to Llandovery, based on graptolites, brachiopods and conodonts. The spicule association is composed only of scarce siliceous hexactine‐based spicules which cannot be attributed to any specific hexactinellid taxon. The fragmentary preservation of this allochthonous sponge assemblage points toward preburial transport. These spicules represent the only microfauna found in the uppermost sandstones. Macrofossils are absent. No conodonts have been recovered in these levels. Two interpretations on the spicules of the Precordillera can be argued: (a) that those early Silurian hexactinellids could have occurred in quartz sandstones of the shore‐facies to off‐shore transitional associations, in the upper La Chilca Formation, or (b) that these sponges flourished in mainly calcareous shales in quiet deep‐water conditions, and that their fragile spicules were removed and deposited by oceanic currents, on the top of the outer‐shelf sand bars.Both hypotheses on the palaeoenvironmental origin of these spicules are substantially different, but the scarcity of spicules does not allow a more precise interpretation. The discovery of these hexactinellid spicules provides a new perspective on Silurian sponge occurrence and distribution for the Argentine Precordillera. Copyright © 2011 John Wiley &amp; Sons, Ltd.

NMR Analysis of the Fibronectin Cell-Adhesive Sequence, Arg-Gly-Asp, in a Recombinant Silk-Like Protein and a Model Peptide

It is well established that by introducing the cell-adhesive sequence Arg-Gly-Asp (RGD) from fibronectin into Bombyx mori silk fibroin by covalent coupling or bioengineering techniques, excellent biomaterials have been developed with the modified silk fibroin. However, there is no report about the structure and dynamics of the RGD moiety in the silk fibroin. To clarify the origin of such a high cell adhesion character and to design new recombinant silk protein with higher cell adhesion ability, it is necessary to characterize the structure and dynamics of the RGD moiety introduced into silk fibroin. In this study, the structure and dynamics of the RGD moiety in a recombinant silk-like protein, SLPF(10), consisting of the repeated silk fibroin sequence (AGSGAG)(3) and the sequence ASTGRGDSPA including the RGD moiety, were studied using solution NMR. The (1)H, (15)N, and (13)C chemical shifts indicate that the RGD moiety, as well as the silk fibroin sequence, takes a random coil form with high mobility in aqueous solution. Next, a (13)C solid-state NMR study was performed on a (13)C selectively labeled model peptide, AGSGAG[3-(13)C]A(7)GSGAGAGSGGT[2-(13)C]G(19)R[1-(13)C]G(21)DSPAGGGAGAGSGAG. After formic acid treatment, an increase in the β-sheet fraction for the AGSGAG sequence and peak narrowing of the residues around the RGD moiety were observed in the dry state. The latter indicates a decrease in the chemical shift distribution although the RGD moiety is still in random coil. A decrease in the peak intensities of the RGD moiety in the swollen state after immersing it in distilled water was observed, indicating high mobility of the RGD sequence in the peptide in the swollen state. Thus, the random coil state of the RGD moiety in the recombinant silk-like protein is maintained in aqueous solution and also in both dry and swollen state. This is similar to the case of the RGD moiety in fibronectin. The presence of the linker ASTG at the N-terminus and SPAGG at the C-terminus seems important to maintain the random coil form and the flexible state of the RGD sequence in order to permit access for binding to various integrins.

The effect of formic acid treatment on aggregated Aβ

The effect of formic acid treatment on aggregated Aβ

Fractionating lignocellulose by formic acid: Characterization of major components

Abstract Treatment of corn (Zea mays L.) cob under mild reaction conditions (60 °C and atmospheric pressure) in 88% formic acid was an effective method for separating cellulose from hemicellulose and lignin components in lignocellulose. Most of the hemicellulose degradation and lignin removal occurred within the first 90 min. After 6 h treatment, the decomposition of hemicellulose and the recovery of lignin were over 85% and 70%, respectively. Multi-level structures of lignin and solid residues were further characterized by FTIR, XRD, TG/DTG, SEM and SEC. Peaks attributable to lignin or hemicellulose disappeared in FTIR spectra, indicating complete removal of these two components. The remaining solid residues had a higher crystalline index. The major pyrolysis temperature of corncob was increased after formic acid treatment; the molecular weight (MW) of cellulose in solid residues was higher than that in intact cobs, whereas the hemicellulose remaining in the pulp had a lower MW than the original. Lignin was extracted in an esterified form designated as formic acid lignin (FAL). FAL had two thermal decomposition temperatures (Td) at 277 °C and 385 °C. The MW of lignin increased following formic acid treatment, which may make it a better starting material for chemical syntheses.

Fluxless Bonding Using Vacuum Ultraviolet and Formic Acid for 3D Interconnects

AbstractWe have developed a novel surface treatment process using vacuum ultraviolet (VUV) light with a wavelength of 172 nm and formic acid vapor. A previous study showed that the VUV process can help remove the organic contaminants on the bonding surfaces and improve the shear strength. This new work focuses on studying the effects of VUV/O3 and formic acid treatments. The formic acid (HCOOH) vapor removes the metal oxides from the surfaces before the bonding process. Evaporated Cu/Sn and immersion Au were used for the bonding micro-bumps and bonding pads in our evaluations. Different cleaning conditions with VUV/O3, formic acid vapor, or both were compared and evaluated. X-ray Photoelectron Spectroscopy (XPS) was used to study the surface elemental composition of the micro-bumps and pad surfaces before and after the cleaning process. The photoelectron spectra of C1s, Sn3d, and Au4f were obtained with XPS. The XPS results showed the atomic carbon concentrations were significantly decreased by the VUV/O3 treatment process, while the Sn and Au concentrations were increased by the VUV/O3 and formic acid treatment because of the removal of the organic contaminants and metal oxides from the surfaces. The bonding strength of the Cu/Sn bumps was evaluated using a shear test tool. The results shows that the combination of VUV/O3 and formic acid treatment obtains the highest average shear strength among the treatments tested, with a shear strength almost 2.5 times stronger than the untreated samples.

Fine-tuning scaffolds for tissue regeneration: effects of formic acid processing on tissue reaction to silk fibroin

Formic acid (FA) plays a key role in the preparation of silk fibroin (SF) scaffolds from cocoons of Bombyx mori and is used for fibre distribution. In this study, we used a subcutaneous implantation model in Wistar rats to examine SF scaffolds prepared by treating the degummed cocoon with FA for either 30 or 60 min. The tissue reaction and inflammatory response to SF was assessed by qualitative histology at intervals from 3 to 180 days. Additionally, dynamic biomaterial-induced vascularization and biomaterial degradation were quantified using a technique for analysing an image of the entire implanted biomaterial. Varying the FA treatment time led to different scaffold morphologies and resulted in two distinct peri-implant tissue reactions. The 30 min-treated scaffold was integrated into the surrounding tissue beginning at day 3 after implantation and vascularization increased 10-fold from 15 to 180 days, while the scaffold was continuously degraded throughout the first 90 days. In contrast, the 60 min-treated SF scaffold appeared as bulk for the first 90 days after implantation, after which a rapid degradation and vascularization process began. After 180 days, the tissue response was similar for both scaffolds, with eventual formation of a well vascularized connective tissue integrating the SF fibres. This study indicates that by modifying the FA treatment time, the tissue reaction to SF scaffolds can be tailored for different tissue-engineering applications. The tunability and biocompatibility of SF make it an attractive scaffold for exploration in regenerative medicine and clinical tissue engineering.

Isolation and characterization of wheat straw lignin with a formic acid process

There is a commercial need to increase the amount of industrial produced lignin. An 86.24 wt.% formic acid solution with 0.2 M H 2SO 4 as the catalyst was used to isolate the lignin of dewaxed wheat straw at different residence times and reaction temperatures. Lignin was extracted and purified separately from hydrolysates and residual solids after treatment. The lignin obtained has been characterized by FTIR (Fourier transform infrared), GPC (Gel permeation chromatography), and 1H NMR (Nuclear magnetic resonance). Results from these analyses indicated that oxidative cleavage of bonds in the lignin macromolecule has occurred during the formic acid treatment, leading to formation of oligomers of lignin with lower molecular weight. Moreover, it was found that guaiacyl unit is the main structure, the content of syringyl unit is higher than that of the hydroxybenzyl unit and β-O-4 together with β-5 ether bonds is also identified in the molecular structure of lignin of wheat straw obtained from the formic acid process.

Short-Term Fumigation of Honey Bee (Hymenoptera: Apidae) Colonies with Formic and Acetic Acids for the Control of &lt;I&gt;Varroa destructor&lt;/I&gt; (Acari: Varroidae)

Controlling populations of varroa mites is crucial for the survival of the beekeeping industry. Many treatments exist, and all are designed to kill mites on adult bees. Because the majority of mites are found under capped brood, most treatments are designed to deliver active ingredients over an extended period to control mites on adult bees, as developing bees and mites emerge. In this study, a 17-h application of 50% formic acid effectively killed mites in capped worker brood and on adult bees without harming queens or uncapped brood. Neither acetic acid nor a combined treatment of formic and acetic acids applied to the West Virginia formic acid fumigator was as effective as formic acid alone in controlling varroa mites. In addition, none of the treatments tested in late summer had an effect on the late-season prevalence of deformed wing virus. The short-term formic acid treatment killed > 60% of varroa mites in capped worker brood; thus, it is a promising tool for beekeepers, especially when such treatments are necessary during the nectar flow.

Silklike materials constructed from sequences of Bombyx mori silk fibroin, fibronectin, and elastin

Two silklike proteins, [TGRGDSPAGG(GAGAGS)3AS]5 (FS5) and [TGRGDSPA-(GVPGV)2GG(GAGAGS)3AS]8 (FES8) were designed to demonstrate the superior performance as biomaterials of silklike proteins. The former protein consists of the crystalline domain sequence, (GAGAGS)n from Bombyx mori silk fibroin and cell-adhesive sequence TGRGDSPA coming from fibronectin-containing RGD triplet. The additional sequence (GVPGV)n from elastin was included in the latter protein. The considerably higher cell-adhesion activities of these proteins for NHDF and VERO cells were observed by comparing with those of silklike materials without RGD sequences and also the crystalline fraction of B. mori silk fibroin. This tendency was independent of the treatments, 4.5M LiClO4 or formic acid (FA), on silklike proteins. Their activities are also higher than those of commercial Fibronectin F for NHDF cell. Their structural characterization was studied using 13C solid-state NMR. Although the overlapped peaks in usual 13C CP/MAS NMR spectra make the detailed structural analysis difficult, the methyl resonance regions observed using dipolar dephasing NMR were very useful for the analysis. The presence of both random coil and beta-sheet structures was observed in these proteins clearly. The content of beta-sheet structure in both proteins increases after FA treatment when compared with the lyophilized samples. The production of electrospun nanofibers from their hexafluoroacetone solution was also tried. The silklike protein FES8 could prepare nonwoven silk fibers although FS5 could not.

Structure and Function of the c-myc DNA-unwinding Element-binding Protein DUE-B

Local zones of easily unwound DNA are characteristic of prokaryotic and eukaryotic replication origins. The DNA-unwinding element of the human c-myc replication origin is essential for replicator activity and is a target of the DNA-unwinding element-binding protein DUE-B in vivo. We present here the 2.0A crystal structure of DUE-B and complementary biochemical characterization of its biological activity. The structure corresponds to a dimer of the N-terminal domain of the full-length protein and contains many of the structural elements of the nucleotide binding fold. A single magnesium ion resides in the putative active site cavity, which could serve to facilitate ATP hydrolytic activity of this protein. The structure also demonstrates a notable similarity to those of tRNA-editing enzymes. Consistent with this structural homology, the N-terminal core of DUE-B is shown to display both D-aminoacyl-tRNA deacylase activity and ATPase activity. We further demonstrate that the C-terminal portion of the enzyme is disordered and not essential for dimerization. However, this region is essential for DNA binding in vitro and becomes ordered in the presence of DNA.