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Sample records for acid hydrofluoric acid

  1. [Hydrofluoric acid burns].

    PubMed

    Holla, Robin; Gorter, Ramon R; Tenhagen, Mark; Vloemans, A F P M Jos; Breederveld, Roelf S

    2016-01-01

    Hydrofluoric acid is increasingly used as a rust remover and detergent. Dermal contact with hydrofluoric acid results in a chemical burn characterized by severe pain and deep tissue necrosis. It may cause electrolyte imbalances with lethal consequences. It is important to identify high-risk patients. 'High risk' is defined as a total affected body area > 3% or exposure to hydrofluoric acid in a concentration > 50%. We present the cases of three male patients (26, 31, and 39 years old) with hydrofluoric acid burns of varying severity and describe the subsequent treatments. The application of calcium gluconate 2.5% gel to the skin is the cornerstone of the treatment, reducing pain as well as improving wound healing. Nails should be thoroughly inspected and possibly removed if the nail is involved, to ensure proper healing. In high-risk patients, plasma calcium levels should be evaluated and cardiac monitoring is indicated.

  2. [Hydrofluoric acid burns].

    PubMed

    Holla, Robin; Gorter, Ramon R; Tenhagen, Mark; Vloemans, A F P M Jos; Breederveld, Roelf S

    2016-01-01

    Hydrofluoric acid is increasingly used as a rust remover and detergent. Dermal contact with hydrofluoric acid results in a chemical burn characterized by severe pain and deep tissue necrosis. It may cause electrolyte imbalances with lethal consequences. It is important to identify high-risk patients. 'High risk' is defined as a total affected body area > 3% or exposure to hydrofluoric acid in a concentration > 50%. We present the cases of three male patients (26, 31, and 39 years old) with hydrofluoric acid burns of varying severity and describe the subsequent treatments. The application of calcium gluconate 2.5% gel to the skin is the cornerstone of the treatment, reducing pain as well as improving wound healing. Nails should be thoroughly inspected and possibly removed if the nail is involved, to ensure proper healing. In high-risk patients, plasma calcium levels should be evaluated and cardiac monitoring is indicated. PMID:27189091

  3. Hydrofluoric acid poisoning

    MedlinePlus

    ... your skin or eyes, you may have: Blisters Burns Pain Vision loss Hydrofluoric acid poisoning can have ... urine tests Camera down the throat to see burns in the esophagus and the stomach (endoscopy) Fluids ...

  4. [Hydrofluoric acid poisoning: case report].

    PubMed

    Cortina, Tatiana Judith; Ferrero, Hilario Andrés

    2013-01-01

    Hydrofluoric acid is a highly dangerous substance with industrial and domestically appliances. Clinical manifestations of poisoning depend on exposure mechanism, acid concentration and exposed tissue penetrability. Gastrointestinal tract symptoms do not correlate with injury severity. Patients with history of hydrofluoric acid ingestion should undergo an endoscopy of the upper gastrointestinal tract. Intoxication requires immediate intervention because systemic toxicity can take place. We present a 5 year old girl who accidentally swallowed 5 ml of 20% hydrofluoric acid. We performed gastrointestinal tract endoscopy post ingestion, which revealed erythematous esophagus and stomach with erosive lesions. Two months later, same study was performed and revealed esophagus and stomach normal mucous membrane.

  5. Treating burns caused by hydrofluoric acid.

    PubMed

    Summers, Anthony

    2011-06-01

    Hydrofluoric acid is an ingredient of many common household and industrial solutions. Even seemingly minor burns caused by this acid can have catastrophic effects if they are treated inappropriately or late. This article describes the signs and symptoms, the pathophysiology and the emergency management of hydrofluoric acid burns.

  6. A review of hydrofluoric acid burn management.

    PubMed

    McKee, Daniel; Thoma, Achilleas; Bailey, Kristy; Fish, Joel

    2014-01-01

    Hydrofluoric acid (HF) causes a unique chemical burn. Much of the current treatment knowledge of HF burns is derived from case reports, small case series, animal studies and anecdotal evidence. The management can be challenging because clinical presentation and severity of these burns vary widely. Plastic surgeons managing burn patients must have a basic understanding of the pathophysiology, the range of severity in presentation and the current treatment options available for HF burns. The present article reviews the current understanding of the pathophysiology and systemic effects associated with severe HF burns. Furthermore, it distinguishes between minor and life-threatening HF burns and describes several of the basic techniques that are available to treat patients with HF burns.

  7. A review of hydrofluoric acid burn management.

    PubMed

    McKee, Daniel; Thoma, Achilleas; Bailey, Kristy; Fish, Joel

    2014-01-01

    Hydrofluoric acid (HF) causes a unique chemical burn. Much of the current treatment knowledge of HF burns is derived from case reports, small case series, animal studies and anecdotal evidence. The management can be challenging because clinical presentation and severity of these burns vary widely. Plastic surgeons managing burn patients must have a basic understanding of the pathophysiology, the range of severity in presentation and the current treatment options available for HF burns. The present article reviews the current understanding of the pathophysiology and systemic effects associated with severe HF burns. Furthermore, it distinguishes between minor and life-threatening HF burns and describes several of the basic techniques that are available to treat patients with HF burns. PMID:25114621

  8. Corrosion Behavior of Nickel Alloys in Wet Hydrofluoric Acid

    SciTech Connect

    Rebak, R B

    2004-02-06

    Hydrofluoric acid is a water solution of hydrogen fluoride (HF). Hydrofluoric acid is used widely in diverse types of industrial applications; traditionally, it is used in pickling solutions in the metal industry, in the fabrication of chlorofluorocarbon compounds, as an alkylation agent for gasoline and as an etching agent in the industry of glass. In recent years, hydrofluoric acid has extensively been used in the manufacture of semiconductors and microelectronics during the wet chemical cleaning of silicon wafers. Hydrofluoric acid can be considered a reducing acid and although it is chemically classified as weaker than, for example, sulfuric or hydrochloric acids, it is extremely corrosive. This acid is also particularly toxic and poses greater health hazard than most other acids. The corrosion behavior of metals in hydrofluoric acid has not been as systematic studied in the laboratory as for other common inorganic acids. This is largely because tests using hydrofluoric acid cannot be run in standard equipment and because of the toxic nature of this acid. Moreover, short-term weight loss laboratory corrosion tests in hydrofluoric acid can be frustrating since the results are not as highly reproducible as in the case of other acids such as sulfuric or hydrochloric. One of the reasons is because hydrofluoric acid commonly attacks the coupons used for testing in a non-uniform manner. That is, the corrosive power of this acid is not aimed to uniform thinning but mostly to localized penetration below the skin of the metal in the form of thin cracks, voids, pits, trenches and sometimes intergranular attack. Figure 1 shows the cross section of a coupon of Alloy 600 (N06600) exposed for 336 h to the vapor phase of a solution of 20% HF at 93 C. In cases where internal penetration occurs such as in Figure 1, it may not be recommended to use corrosion rates based on weight loss for material selection.

  9. Hydrofluoric acid burns: a 15-year experience.

    PubMed

    Stuke, Lance E; Arnoldo, Brett D; Hunt, John L; Purdue, Gary F

    2008-01-01

    Hydrofluoric acid (HF) is a strong inorganic acid commonly used in many domestic and industrial settings. It is one of the most common chemical burns encountered in a burn center and frequently engenders controversy in its management. We report our 15 year experience with management of HF burns. We reviewed our experience from 1990 to 2005 for patients admitted with HF burns. Primary treatment was with calcium gluconate gel. Arterial infusion of calcium and fingernail removal were reserved for unrelenting symptoms. There were 7944 acute burn admissions to our center during this study period, 204 of which were chemical burns. HF burns comprised 17% of these chemical burn admissions (35 patients). All were men, with a mean burn size of 2.1 +/- 1.5% (range, 1-6%) and hospital stay of 1.6 +/- 0.7 days (range, 0-3 days). The most common seasonal time of injury was in the summer. Twelve patients (34%) were admitted to the intensive care unit for a total of 14 intensive care unit days, primarily for arterial infusions. Ventilator support was not required in any patient. No electrolyte abnormalities occurred. All burns were either partial thickness or small full thickness with no operative intervention required and no deaths. The upper extremity was most commonly involved (29 patients, 83%). The most common cause was air conditioner cleaner (8 patients, 23%). HF is a common cause of chemical burns. Although hospital admission is usually required for vigorous treatment and pain control, burn size is usually small and does not cause electrolyte abnormalities, significant morbidity, or death. PMID:18849854

  10. Accidental intoxication with hydrochloric acid and hydrofluoric acid mixture.

    PubMed

    Smędra-Kaźmirska, A; Kędzierski, M; Barzdo, M; Jurczyk, Ap; Szram, S; Berent, J

    2014-01-01

    The paper describes a fatal case of accidental ingestion of a mixture of hydrochloric acid and hydrofluoric acid. The man was admitted to hospital, where appropriate treatment, adequate to his condition, was instituted. Numerous ventricular fibrillation episodes, for which the patient was defibrillated repeatedly, were observed during the period of hospitalization. The patient was in a critical condition, with progressive symptoms of hypovolemic shock and multiorgan failure. On the next day after admission, signs of electromechanical dissociation progressing to asystole were noted. The instituted resuscitation procedure proved ineffective and the patient died. Autopsy revealed brownish discoloration of the esophageal, gastric, and small intestinal mucous membranes. Numerous ulcerations without signs of perforation were found both in the esophagus and in the stomach. The mucous membrane of the small intestine demonstrated focal rubefactions, whereas no focal lesions of the large intestinal mucosa were seen. Microscopic investigation of the biopsy specimens collected from the stomach, duodenum and small intestine revealed mucous membrane necrosis foci, reaching the deeper layers of the wall of these organs. The mucous membrane of the large intestine was congested. Bioptates obtained from the lungs indicated the presence of hemorrhagic infarcts and focal extravasations. Poisoning with the aforementioned acids with consequent necrosis of the esophageal, gastric, duodenal and small intestinal walls with hemorrhages to the gastrointestinal tract, as well as extravasations and hemorrhagic infarcts in the lungs was considered to be the cause of death.

  11. 40 CFR 415.80 - Applicability; description of the hydrofluoric acid production subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... hydrofluoric acid production subcategory. 415.80 Section 415.80 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Hydrofluoric Acid Production Subcategory § 415.80 Applicability; description of the hydrofluoric acid production subcategory. The provisions of this subpart are applicable to discharges...

  12. 40 CFR 721.4461 - Hydrofluoric acid, reaction products with octane (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Hydrofluoric acid, reaction products... New Uses for Specific Chemical Substances § 721.4461 Hydrofluoric acid, reaction products with octane... identified generically as a hydrofluoric acid, reaction products with octane (PMN P-99-0052) is subject...

  13. 40 CFR 721.4461 - Hydrofluoric acid, reaction products with octane (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Hydrofluoric acid, reaction products... New Uses for Specific Chemical Substances § 721.4461 Hydrofluoric acid, reaction products with octane... identified generically as a hydrofluoric acid, reaction products with octane (PMN P-99-0052) is subject...

  14. 40 CFR 721.4385 - Hydrofluoric acid, reaction products with heptane.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Hydrofluoric acid, reaction products... Specific Chemical Substances § 721.4385 Hydrofluoric acid, reaction products with heptane. (a) Chemical... hydrofluoric acid, reaction products with heptane (PMN P-98-1036; CAS No. 207409-71-0) is subject to...

  15. 40 CFR 721.4461 - Hydrofluoric acid, reaction products with octane (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Hydrofluoric acid, reaction products... New Uses for Specific Chemical Substances § 721.4461 Hydrofluoric acid, reaction products with octane... identified generically as a hydrofluoric acid, reaction products with octane (PMN P-99-0052) is subject...

  16. 40 CFR 721.4385 - Hydrofluoric acid, reaction products with heptane.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Hydrofluoric acid, reaction products... Specific Chemical Substances § 721.4385 Hydrofluoric acid, reaction products with heptane. (a) Chemical... hydrofluoric acid, reaction products with heptane (PMN P-98-1036; CAS No. 207409-71-0) is subject to...

  17. 40 CFR 721.4385 - Hydrofluoric acid, reaction products with heptane.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Hydrofluoric acid, reaction products... Specific Chemical Substances § 721.4385 Hydrofluoric acid, reaction products with heptane. (a) Chemical... hydrofluoric acid, reaction products with heptane (PMN P-98-1036; CAS No. 207409-71-0) is subject to...

  18. 40 CFR 721.4461 - Hydrofluoric acid, reaction products with octane (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Hydrofluoric acid, reaction products... New Uses for Specific Chemical Substances § 721.4461 Hydrofluoric acid, reaction products with octane... identified generically as a hydrofluoric acid, reaction products with octane (PMN P-99-0052) is subject...

  19. 40 CFR 721.4385 - Hydrofluoric acid, reaction products with heptane.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Hydrofluoric acid, reaction products... Specific Chemical Substances § 721.4385 Hydrofluoric acid, reaction products with heptane. (a) Chemical... hydrofluoric acid, reaction products with heptane (PMN P-98-1036; CAS No. 207409-71-0) is subject to...

  20. 40 CFR 721.4461 - Hydrofluoric acid, reaction products with octane (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Hydrofluoric acid, reaction products... New Uses for Specific Chemical Substances § 721.4461 Hydrofluoric acid, reaction products with octane... identified generically as a hydrofluoric acid, reaction products with octane (PMN P-99-0052) is subject...

  1. 40 CFR 721.4385 - Hydrofluoric acid, reaction products with heptane.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Hydrofluoric acid, reaction products... Specific Chemical Substances § 721.4385 Hydrofluoric acid, reaction products with heptane. (a) Chemical... hydrofluoric acid, reaction products with heptane (PMN P-98-1036; CAS No. 207409-71-0) is subject to...

  2. [Polishing of titanium prosthetics (Part 6). The chemical polishing baths containing hydrofluoric acid and nitric acid].

    PubMed

    Tamaki, Y; Miyazaki, T; Suzuki, E; Miyaji, T

    1989-01-01

    Titanium was polished using several chemical polishing baths containing different ratios of hydrofluoric acid and nitric acid. The meltage, surface roughness, and surface texture of titanium samples after chemical polishing were affected by the ratio of hydrofluoric acid and nitric acid. Generally the meltage increased and surface roughness decreased when the mole concentration of hydrofluoric acid was high and that of nitric acid was low. For example the chemical polishing bath containing 5 mole hydrofluoric acid and 5 mole nitric acid improved the surface texture in one minute, but SEM observation revealed a partially rough surface caused by the excessive solution. The chemical polishing bath containing 1 mole hydrofluoric acid and 5 mole nitric acid did not improve the surface texture in a short time because of low solubility, but improved the surface texture gradually with the extension of the immersion time and a good surface texture was observed by SEM. The chemical polishing using the chemical polishing bath with low solubility and immersion of the prosthetics for a rather long time were considered useful procedures to obtain a smooth surface of titanium prosthetics while maintaining their accuracy.

  3. Evaluation of optimal reuse system for hydrofluoric acid wastewater.

    PubMed

    Won, Chan-Hee; Choi, Jeongyun; Chung, Jinwook

    2012-11-15

    The treatment of hydrofluoric acid (HF) wastewater has been an important environmental issue in recent years due to the extensive use of hydrofluoric acid in the chemical and electronics industries, such as semiconductor manufacturers. Coagulation/precipitation and ion exchange technologies have been used to treat HF wastewater, but these conventional methods are ineffective in removing organics, salts, and fluorides, limiting its reuse for water quality and economic feasibility. One promising alternative is reverse osmosis (RO) after lime treatment. Based on pilot-scale experiment using real HF wastewater discharged from semiconductor facility, the spiral wound module equipped with polyamide membranes has shown excellent flux and chemical cleaning cycles. Our results suggest that coagulation/precipitation and spiral wound RO constitute the optimal combination to reuse HF wastewater.

  4. [Advances in the research of treatment of hydrofluoric acid burn].

    PubMed

    Wang, Xin-gang; Zhang, Yuan-hai; Han, Chun-mao

    2013-08-01

    Hydrofluoric acid (HF) is one of the most common inorganic acids used widely in industrial circle. HF not only causes cutaneous burn, but also induces systemic toxicity by its unique injury mechanism. Accurate and timely diagnosis and treatment are critical after HF burns. To date, the strategies for treating HF burns have been developed, mainly including topical treatments and systematic support. However, there is no standard treatment strategy with wide acceptance in the world. This paper presents a comprehensive overview of the advances in the research of strategies for the treatment of HF burns.

  5. Fatality due to acute fluoride poisoning following dermal contact with hydrofluoric acid in a palynology laboratory.

    PubMed

    Muriale, L; Lee, E; Genovese, J; Trend, S

    1996-12-01

    A fatal accident involving concentrated hydrofluoric acid in a palynological laboratory is described. Similar deaths due to dermal exposure to concentrated hydrofluoric acid have been reported in the literature. It is evident that rigorous control measures including proper personal protective equipment and first aid are of utmost importance in the prevention of death and injury when handling hydrofluoric acid. Possible factors that may have contributed to the accident are reviewed.

  6. Hydrofluoric acid-resistant composite window and method for its fabrication

    DOEpatents

    Ostenak, C.A.; Mackay, H.A.

    1985-07-18

    A hydrofluoric acid-resistant composite window and method for its fabrication are disclosed. The composite window comprises a window having first and second sides. The first side is oriented towards an environment containing hydrofluoric acid. An adhesive is applied to the first side. A layer of transparent hydrofluoric acid-resistant material, such as Mylar, is applied to the adhesive and completely covers the first side. The adhesive is then cured.

  7. Hydrofluoric acid-resistant composite window and method for its fabrication

    DOEpatents

    Ostenak, Carl A.; Mackay, Harold A.

    1987-01-01

    A hydrofluoric acid-resistant composite window and method for its fabrication are disclosed. The composite window comprises a window having first and second sides. The first side is oriented towards an environment containing hydrofluoric acid. An adhesive is applied to the first side. A layer of transparent hydrofluoric acid-resistant material, such as Mylar, is applied to the adhesive and completely covers the first side. The adhesive is then cured.

  8. Balloon-borne observations of mid-latitude hydrofluoric acid

    NASA Technical Reports Server (NTRS)

    Sen, B.; Toon, G. C.; Blavier, J.-F.; Szeto, J. T.; Fleming, E. L.; Jackman, C. H.

    1995-01-01

    Measurements of stratospheric hydrofluoric acid (HF) have been made by the JPL MkIV interferometer during high-altitude balloon flights. Infrared solar absorption spectra were acquired near 35 deg N at altitudes between local tropopause and 38 km. Volume mixing ratio profiles of HF derived from 4 flights (1990-93), in conjunction with simultaneously observed N2O profiles, indicate an average rate of HF increase of (5.5 +/- 0.3)% per year, in agreement with time-dependent, two-dimensional model simulations (6% per year) and ATMOS measurements.

  9. Use of hemodialysis after ingestion of a mixture of acids containing hydrofluoric acid.

    PubMed

    Antar-Shultz, M; Rifkin, S I; McFarren, C

    2011-11-01

    Hydrofluoric acid (HF) is a highly toxic poison that can be rapidly fatal. Death usually results from the many systemic effects of dissociated fluoride ions, including hypocalcemia, hypomagnesemia, hyperkalemia, and direct cardiotoxicity. A patient is described who accidentally ingested a hydrofluoric acid-containing substance and who likely benefited from hemodialysis. His fluoride level post-dialysis was reduced by approximately 70% from a level drawn three hours prior to the initiation of hemodialysis. However, the single treatment did not reduce the fluoride level to normal. A review of the pathophysiology of hydrofluoric acid intoxication and the outcomes of prior exposures suggests that hemodialysis could play a vital role in the management of poisonings with fluoride-containing substances. However, the initial hemodialysis treatment should be prolonged beyond the standard four-hour session.

  10. Hydrofluoric and nitric acid transport through lipid bilayer membranes.

    PubMed

    Gutknecht, J; Walter, A

    1981-06-01

    Hydrofluoric and nitric acid transport through lipid bilayer membranes were studied by a combination of electrical conductance and pH electrode techniques. Transport occurs primarily by nonionic diffusion of molecular HF and HNO3. Membrane permeabilities to HF and HNO3 ranged from 10(-4) to 10(-3) cm . s-1, five to seven orders of magnitude higher than the permeabilities to NO-3, F- and H+. Our results are consistent with the hypothesis that F- transport through biological membranes occurs mainly by nonionic diffusion of HF. Our results also suggest that of the two principal components of 'acid rain', HNO3 may be more toxic than H2SO4.

  11. Surface characteristics of dentin experimentally exposed to hydrofluoric acid.

    PubMed

    Pioch, Thomas; Jakob, Heiko; García-Godoy, Franklin; Götz, Hermann; Dörfer, Christof E; Staehle, Hans J

    2003-08-01

    The purpose of this study was to test the effect of hydrofluoric acid (HF) on the surface characteristics of dentin in vitro. Dentin was exposed in 50 human molars and divided into five groups according to different etching schedules: (i) no etching, (ii) 15 s HF, (iii) 15 s H3PO4, (iv) 15 s HF and 15 s H3PO4, (v) 15 s H3PO4 and 15 s HF. Teeth were examined under a scanning electron microscope equipped with energy-dispersive X-ray (EDX) or two layers of fluorescence-labeled primer followed by the composite were applied, and the teeth were sectioned and examined using confocal laser scanning microscopy (CLSM). With scanning electron microscopy, no openings of dentinal tubules were found in groups (i), (ii), and (iv). In group (v) only a few tubules were opened and in group (iii) the smear layer was completely removed and tubules appeared open. The EDX analysis revealed that fluoride was incorporated into the dentin surface when HF was used. With CLSM, distinct hybrid layers could be detected only in group (iii). In group (v) the hybrid layer appeared less established compared with group (iii). No dentin hybridization was found in groups (i), (ii), and (iv). It is concluded that HF has the ability to close the openings of dentin tubules which were opened due to etching by phosphoric acid and cannot dissolve the smear layer.

  12. Comparison of acidulated phosphate fluoride gel and hydrofluoric acid etchants for porcelain-composite repair.

    PubMed

    Tylka, D F; Stewart, G P

    1994-08-01

    Hydrofluoric acid etches porcelain to produce a porous surface visible under scanning electron microscopy when compared to an acidulated phosphate fluoride gel. Some investigators have suggested the greater porosity of the hydrofluoric acid etch produces a greater composite-to-porcelain bond. This investigation tested that assumption with two common fluoride etchants. The etched surfaces were first viewed under scanning electron microscopy to ensure that a characteristic etch was achieved. Both etchants yielded bond strengths that produced cohesive failure of all samples. This suggested that the intraoral use of hydrofluoric acid is no more effective than the less dangerous acidulated phosphate fluoride gel.

  13. Dental zirconia can be etched by hydrofluoric acid.

    PubMed

    Sriamporn, Tool; Thamrongananskul, Niyom; Busabok, Chumphol; Poolthong, Sushit; Uo, Motohiro; Tagami, Junji

    2014-01-01

    The surface morphology and crystal structure change of dental zirconia after hydrofluoric acid (HF) etching were evaluated. Four groups of sintered zirconia specimens were 1) control group, 2) immersion in 9.5%HF at 25°C for 1, 2, 3, or 24 h, 3) immersion in 9.5%HF at 80°C for 1, 3, 5, or 30 min and 4) immersion in 48%HF at 25°C for 30 or 60 min. The specimens were evaluated under SEM and XRD. The SEM analysis revealed changes in surface topography for all the HF-etched zirconia specimens. The irregularities surface increased with increasingly longer immersion times and higher etching solution temperatures. The XRD analysis of the HFetched zirconia specimens revealed the presence of a crystalline monoclinic phase along with a tetragonal form. It was concluded HF can etch dental zirconia ceramic, creating micro-morphological changes. Tetragonal-to-monoclinic phase transformation was induced on the etched zirconia surface.

  14. Injuries following a serious hydrofluoric acid leak: First aid and lessons.

    PubMed

    Zhang, Yuanhai; Wang, Xingang; Sharma, Komal; Mao, Xinxing; Qiu, Xuguang; Ni, Liangfang; Han, Chunmao

    2015-11-01

    Hydrofluoric acid is a dangerous inorganic acid that can cause local corrosion and systemic effects by ongoing absorption via the skin, mucosae, respiratory tract and digestive system. Recently, a serious toxic leak of low-concentration hydrofluoric acid solution occurred in the Pujiang area of Zhejiang Province, China. This accident resulted in 253 cases of chemical injury due to hydrofluoric acid exposure. Despite an immediate response by the local and provincial health-care system, as well as the local government, three people died due to acute poisoning and related complications. This article describes the events that took place leading to casualties as well as presenting the first-aid experience and the lessons learnt from this kind of mass injury.

  15. Injuries following a serious hydrofluoric acid leak: First aid and lessons.

    PubMed

    Zhang, Yuanhai; Wang, Xingang; Sharma, Komal; Mao, Xinxing; Qiu, Xuguang; Ni, Liangfang; Han, Chunmao

    2015-11-01

    Hydrofluoric acid is a dangerous inorganic acid that can cause local corrosion and systemic effects by ongoing absorption via the skin, mucosae, respiratory tract and digestive system. Recently, a serious toxic leak of low-concentration hydrofluoric acid solution occurred in the Pujiang area of Zhejiang Province, China. This accident resulted in 253 cases of chemical injury due to hydrofluoric acid exposure. Despite an immediate response by the local and provincial health-care system, as well as the local government, three people died due to acute poisoning and related complications. This article describes the events that took place leading to casualties as well as presenting the first-aid experience and the lessons learnt from this kind of mass injury. PMID:26188892

  16. Management of a Patient With Faciocervical Burns and Inhalational Injury Due to Hydrofluoric Acid Exposure.

    PubMed

    Yuanhai, Zhang; Xingang, Wang; Liangfang, Ni; Chunmao, Han

    2014-05-01

    Hydrofluoric acid, a highly dangerous substance, can cause tissue damage and systemic toxicity by its unique mechanisms. Many cases of severe faciocervical burns due to hydrofluoric acid exposure are lethal. Herein, we present a case of 37-year-old man who suffered from hydrofluoric acid burns to his face, anterior neck, lips, and nasal cavity. On admission, this patient coughed with much sputum, and the chest auscultation detected rough breath sounds, wheezes, and very weak heart sounds, indicating possible inhalation injury. This case highlights the extreme complexity of managing this kind of injury. Timely and accurate wound treatment and respiratory tract care, as well as active systematic support treatment, played vital roles in the management of this patient.

  17. Observation of hydrofluoric acid burns on osseous tissues by means of terahertz spectroscopic imaging.

    PubMed

    Baughman, William E; Yokus, Hamdullah; Balci, Soner; Wilbert, David Shawn; Kung, Patrick; Kim, Seongsin Margaret

    2013-07-01

    Terahertz technologies have gained great amount of attention for biomedical imaging and tissue analysis. In this study, we utilize terahertz imaging to study the effects of hydrofluoric acid on both compact bone tissue and cartilage. We compare the differences observed in the exposure for formalin fixed and raw, dried, tissue as well as those resulting from a change in hydrofluoric (HF) concentration. Measurements are performed with THz-TDS, and a variety of spectroscopic-based image reconstruction techniques are utilized to develop contrast in the features of interest.

  18. Hydrofluoric acid exposure: a case report and review on the clinical presentation and management.

    PubMed

    Strausburg, Matthew; Travers, Jeffrey; Mousdicas, Nico

    2012-01-01

    Exposure to hydrofluoric acid can cause severe skin damage via both corrosive and chemical means. Dermatologists should be aware of the various clinical presentations and knowledgeable of how to manage such patients. A case of a man with exposure of the hands after use of a consumer product containing hydrofluoric acid is presented. The presentation may vary depending on the concentration and duration of exposure. Patients experiencing exposure are at risk of serious complications, including death, resulting from electrolyte abnormalities. Information regarding the source of exposure will allow the physician to better predict the patient's course. The use of immediate flushing with water and the use of topical calcium gluconate can prevent extensive damage to the area of exposure and potentially fatal complications that may occur. More extensive burns may necessitate more invasive therapies. The treatment and the management and monitoring of such cases will allow for more optimal outcomes.

  19. [Hydrofluoric acid burns of the hands in the home environment: correct therapeutic approach].

    PubMed

    Nicoletti, Giovanni; Pellegatta, Tommaso

    2014-01-01

    The broad market penetration of products with components used primarily in the industrial sector requires the precise knowledge of their mechanism of action in order to perform a correct therapeutic approach. The article reports on three cases of domestic hydrofluoric acid burn that came to our Plastic Surgery Unit over the last three years. The treatment options are discussed in detail with emphasis on the importance of a constant update about such emerging diseases.

  20. Bonding to enamel/dentin etched with phosphoric and hydrofluoric acids.

    PubMed

    Barghi, Nassar; Covington, Kendra; Fischer, Dan E; Herbold, Edward T

    2004-10-01

    Repairing porcelain intraorally allows clinicians to provide their patients with a conservative means of treating fractured or debonded restorations. This requires, however, the etching of both porcelain and tooth structure with etching solutions. It is thus relevant to understand the effect that different etching procedures have on shear bond strengths of composite resins to both dentin and enamel structures. Based on the results of this investigation, the authors recommend isolation of tooth structures and the etching of porcelain with hydrofluoric acid.

  1. Quantitative analysis of mixed hydrofluoric and nitric acids using Raman spectroscopy with partial least squares regression.

    PubMed

    Kang, Gumin; Lee, Kwangchil; Park, Haesung; Lee, Jinho; Jung, Youngjean; Kim, Kyoungsik; Son, Boongho; Park, Hyoungkuk

    2010-06-15

    Mixed hydrofluoric and nitric acids are widely used as a good etchant for the pickling process of stainless steels. The cost reduction and the procedure optimization in the manufacturing process can be facilitated by optically detecting the concentration of the mixed acids. In this work, we developed a novel method which allows us to obtain the concentrations of hydrofluoric acid (HF) and nitric acid (HNO(3)) mixture samples with high accuracy. The experiments were carried out for the mixed acids which consist of the HF (0.5-3wt%) and the HNO(3) (2-12wt%) at room temperature. Fourier Transform Raman spectroscopy has been utilized to measure the concentration of the mixed acids HF and HNO(3), because the mixture sample has several strong Raman bands caused by the vibrational mode of each acid in this spectrum. The calibration of spectral data has been performed using the partial least squares regression method which is ideal for local range data treatment. Several figures of merit (FOM) were calculated using the concept of net analyte signal (NAS) to evaluate performance of our methodology.

  2. Quantitative analysis of mixed hydrofluoric and nitric acids using Raman spectroscopy with partial least squares regression.

    PubMed

    Kang, Gumin; Lee, Kwangchil; Park, Haesung; Lee, Jinho; Jung, Youngjean; Kim, Kyoungsik; Son, Boongho; Park, Hyoungkuk

    2010-06-15

    Mixed hydrofluoric and nitric acids are widely used as a good etchant for the pickling process of stainless steels. The cost reduction and the procedure optimization in the manufacturing process can be facilitated by optically detecting the concentration of the mixed acids. In this work, we developed a novel method which allows us to obtain the concentrations of hydrofluoric acid (HF) and nitric acid (HNO(3)) mixture samples with high accuracy. The experiments were carried out for the mixed acids which consist of the HF (0.5-3wt%) and the HNO(3) (2-12wt%) at room temperature. Fourier Transform Raman spectroscopy has been utilized to measure the concentration of the mixed acids HF and HNO(3), because the mixture sample has several strong Raman bands caused by the vibrational mode of each acid in this spectrum. The calibration of spectral data has been performed using the partial least squares regression method which is ideal for local range data treatment. Several figures of merit (FOM) were calculated using the concept of net analyte signal (NAS) to evaluate performance of our methodology. PMID:20441916

  3. DFT study of the energetic and noncovalent interactions between imidazolium ionic liquids and hydrofluoric acid.

    PubMed

    Velarde, Marco V; Gallo, Marco; Alonso, P A; Miranda, A D; Dominguez, J M

    2015-04-16

    In this work, we evaluated the energetic interactions between imidazolium ionic liquids (ILs) and hydrofluoric acid, as well as the cation-anion interactions in ILs. We used DFT calculations that include dispersion corrections employing the PBE and M06 functionals. We tested 22 ILs, including [C4MIM][PF6], [C4MIM][NTf2], and [C4MIM][CH3COO], obtaining interaction energies in the range of -27 to -13 kcal/mol with the PBE functional. The NCI (noncovalent interaction) index developed by Yang and collaborators ( J. Am. Chem. Soc. 2010 , 132 , 6498 - 6506 ; J. Chem. Theory Comput. 2011 , 7 , 625 - 632 ) also was used for mapping the key noncovalent interactions (hydrogen bonds, van der Waals, and steric repulsions) between the anions and cations of ILs and also for interactions of ILs with hydrofluoric acid (HF). The results obtained show that the anions have a stronger effect with respect to cations in their capacity for interacting with hydrofluoric acid, and the strongest interaction energies occur in systems where the key noncovalent interactions are mainly hydrogen bonds. The [C4MIM][PF6], [C4MIM][NTf2], and [C4MIM][BF4] ionic liquids displayed the weakest cation-anion interactions.

  4. The restoration of serial numbers on vehicle glass using hydrofluoric acid.

    PubMed

    Miller, Ruben J

    2013-05-10

    Very little research has been carried out investigating techniques for the restoration of obliterated serial numbers on vehicle glass. A study into the effectiveness of hydrofluoric (HF) acid, a known etchant for glass, has been performed. Character sequences previously etched into panes of vehicle glass were sanded to varying depths and attempts were made to restore the sequences by polishing and using a range of concentrations of HF acid. A concentration of 30% HF acid gave at least a 50% restoration of the sequence if up to approximately 30 μm of glass had been removed during obliteration. Recovery improves if less glass is removed, but not if the concentration of the acid is increased. It appears that removal of glass below the level of the original characters makes subsequent restoration using this technique impossible.

  5. [Study on porcelain veneer restorations. 2. Influence of hydrofluoric acid on bonding strength at the porcelain-resin interface].

    PubMed

    Gomi, A; Ikeda, M; Takeuchi, N; Ban, Y; Kamiya, K; Kanamori, K; Asai, T; Senda, A

    1990-06-01

    Recently, porcelain veneer restoratives have been introduced to the general practice, and their clinical performances have been confirmed through many longterm clinical investigations. It is expected that porcelain veneer restorations will perform successfully in esthetic, conservative and abhesive dentistry. It is an well known fact that the micro-mechanical bonding strength at the porcelain-resin interface which is achieved through the application of hydrofluoric acid to the porcelain surface is quite a strong bonding mechanism. However, there are very few studies reporting on the acid treatment of porcelain surfaces. The authors have been studying the influence of hydrofluoric acid on porcelain surfaces, and in our previous report we reported, the degrees of corroded porcelain treated with different concentrations of hydrofluoric acid for different durations of application. In the present study, shear bonding strength was measured between resin cements and porcelain surfaces treated with different concentrations (4, 6, 8%) of hydrofluoric acid and for different durations (1 to 24 min.), and the appropriate treatment of porcelain surfaces with regard to the bonding strength was determined. The results obtained were as follows. 1. As the treating time increased with any concentration (4, 6, 8%) of hydrofluoric acid, corrosion of the porcelain surface became more intense. Hardly any evidence of corrosion was observed on any porcelain surface treated for one minute, so it seems that the treatment of porcelain surfaces using 4 to 8% hydrofluoric acids should be continued for over three minutes. 2. Observation of the surface profile by SEM showed no significant differences between the surfaces treated for 3, 6, 12 and 24 minutes. 3. It was not clear as to how the differences of hydrofluoric acid concentrations (4, 6, 8%) plus the differences in the kinds of porcelain (Super Porcelain AAA, NORITAKE Co. Ltd., VMK 68, Vita Zahnfabrik Gmbh & Co., Cosmotech Porcelain, G

  6. Effect of hydrofluoric acid (HF) concentration to pores size diameter of silicon membrane.

    PubMed

    Burham, Norhafizah; Hamzah, Azrul Azlan; Majlis, Burhanuddin Yeop

    2014-01-01

    This paper studies parameters which affect the pore size diameter of a silicon membrane. Electrochemical etching is performed in characterise the parameter involved in this process. The parameter has been studied is volume ratio of hydrofluoric acid (HF) and ethanol as an electrolyte aqueous for electrochemical etch. This electrolyte aqueous solution has been mixed between HF and ethanol with volume ratio 3:7, 5:5, 7:3 and 9:1. As a result, the higher volume of HF in this electrolyte gives the smallest pore size diameter compared to the lower volume of HF. These samples have been dipped into HF and ethanol electrolyte aqueous with supplied 25 mA/cm2 current density for 20, 30, 40, and 50 minutes. The samples will inspect under Scanning Electron Microscope (SEM) to execute the pore formations on silicon membrane surface.

  7. Occupational Hydrofluoric Acid Injury from Car and Truck Washing--Washington State, 2001-2013.

    PubMed

    Reeb-Whitaker, Carolyn K; Eckert, Carly M; Anderson, Naomi J; Bonauto, David K

    2015-08-21

    Exposure to hydrofluoric acid (HF) causes corrosive chemical burns and potentially fatal systemic toxicity. Car and truck wash cleaning products, rust removers, and aluminum brighteners often contain HF because it is efficient in breaking down roadway matter. The death of a truck wash worker from ingestion of an HF-based wash product and 48 occupational HF burn cases associated with car and truck washing in Washington State during 2001-2013 are summarized in this report. Among seven hospitalized workers, two required surgery, and all but one worker returned to the job. Among 48 injured workers, job titles were primarily auto detailer, car wash worker, truck wash worker, and truck driver. Because HF exposure can result in potentially severe health outcomes, efforts to identify less hazardous alternatives to HF-based industrial wash products are warranted.

  8. Corrosion of high-alloy materials in aqueous hydrofluoric acid environments

    SciTech Connect

    Pawel, S.J. . Development Div.)

    1994-12-01

    A series of immersion tests for eight high-alloy materials was performed in a variety of hydrofluoric acid (HF) environments. Solution strengths of 0.05%, 1%, 10%, 24%, and 48% HF were examined at 24 C, 50 C, and 76 C. Coupons of each alloy were exposed fully immersed in solution and partially exposed in the aerated vapor above each solution. In addition, a limited number of U-bend tests were performed to examine susceptibility to stress corrosion cracking. Comparison of alloy performance (corrosion rate calculated from weight loss, metallographic evaluation of attack) indicated alloys C-22 (UNS N06022) and C-276 (UNS N10276) exhibited overall superior performance. Other alloys showed useful resistance for a limited range of conditions.

  9. Occupational Hydrofluoric Acid Injury from Car and Truck Washing--Washington State, 2001-2013.

    PubMed

    Reeb-Whitaker, Carolyn K; Eckert, Carly M; Anderson, Naomi J; Bonauto, David K

    2015-08-21

    Exposure to hydrofluoric acid (HF) causes corrosive chemical burns and potentially fatal systemic toxicity. Car and truck wash cleaning products, rust removers, and aluminum brighteners often contain HF because it is efficient in breaking down roadway matter. The death of a truck wash worker from ingestion of an HF-based wash product and 48 occupational HF burn cases associated with car and truck washing in Washington State during 2001-2013 are summarized in this report. Among seven hospitalized workers, two required surgery, and all but one worker returned to the job. Among 48 injured workers, job titles were primarily auto detailer, car wash worker, truck wash worker, and truck driver. Because HF exposure can result in potentially severe health outcomes, efforts to identify less hazardous alternatives to HF-based industrial wash products are warranted. PMID:26292206

  10. Nanopores in GaN by electrochemical anodization in hydrofluoric acid: Formation and mechanism

    NASA Astrophysics Data System (ADS)

    Chen, Danti; Xiao, Hongdi; Han, Jung

    2012-09-01

    We report the use of hydrofluoric acid (HF) as an electrolyte in etching and porosifying GaN. HF is found to be effective in rendering a wide range of nanoporous morphology, from curved branches to highly parallel straight pores. Under suitable conditions, the porosification proceeds at a rate greater than 100 μm/min. To elucidate the etching mechanism, cyclic voltammetry is performed, together with a parametric mapping of electrolysis variables such as the doping of GaN, the concentration of HF electrolyte, and the anodization voltage. We demonstrate that the formation of nanoporous structures is largely due to the local breakdown of the reverse-biased semiconductor junction. A quantitative agreement between the estimated width of space-charge region and the observed variation in morphology lends support to a depletion layer model developed previously in the etching of porous-Si.

  11. Influence of hydrofluoric acid concentration on the flexural strength of a feldspathic ceramic.

    PubMed

    Venturini, Andressa B; Prochnow, Catina; May, Liliana G; Bottino, Marco C; Felipe Valandro, Luiz

    2015-08-01

    This study evaluated the effects of etching with increasing hydrofluoric (HF) acid concentrations on the roughness and flexural strength of a feldspathic ceramic. One hundred and fifty ceramic specimens (14×4×1.2 mm(2)) were produced from ceramic blocks (VitaBlocks Mark II). All specimens were polished, chamfered and sonically cleaned in isopropyl alcohol. Specimens were randomly divided into 5 groups (n=30): SC (control) no ceramic surface etching; HF1, HF3, HF5 and HF10 ceramic surface etching for 60s with 1%, 3%, 5% and 10% HF acid concentrations, respectively. Profilometry was performed in all specimens to evaluate roughness prior to flexural strength testing. Data were analyzed using one-way ANOVA and Tukey׳s test (α=0.05). Weibull module (m) and characteristic stress (σc) were also determined. HF acid etching, regardless of the concentration used, led to significantly rougher surfaces than the control (p<0.05). However, the mean flexural strength values were not statistically different among the etched groups (106.47 to 102.02 MPa). Acid etching significantly reduced the mean flexural strength when compared with the control (143.3 MPa). Weibull modulus of the groups was similar, except for the HF5 group that was higher compared to HF3. Flexural strength was similarly affected by the different HF acid concentrations tested, but roughness increased higher the acid concentration. Ceramic etching led to a significant reduction in strength when compared to the untreated ceramic, regardless of its concentration.

  12. EXAFS study of the speciation of protactinium(V) in aqueous hydrofluoric acid solutions.

    PubMed

    De Sio, Stéphanie M; Wilson, Richard E

    2014-12-01

    The speciation of protactinium(V) in hydrofluoric acid (HF) solutions was studied using X-ray absorption spectroscopy. Extended X-ray absorption fine structure measurements were performed on an aqueous solution of 0.05 M protactinium(V) with various HF concentrations ranging from 0.5 to 27 M in order to probe the protactinium coordination sphere with respect to the identity and number of coordinating ligands. The resulting fits to the spectra suggest the presence of an eight-coordinate homoleptic fluoro complex in highly concentrated fluoride solutions (27 M), with equilibrium between seven- and eight-coordinate fluoro complexes at moderate acidities, and in more dilute solutions, results indicate that one water molecule is likely to replace a fluoride in the first coordination sphere, at a distance of 2.54-2.57 Å. Comparisons of this chemistry with group V metals, niobium and tantalum, are presented, and the potential implications for these results on the hydrolytic behavior of protactinium in aqueous systems are discussed.

  13. EXAFS study of the speciation of protactinium(V) in aqueous hydrofluoric acid solutions.

    PubMed

    De Sio, Stéphanie M; Wilson, Richard E

    2014-12-01

    The speciation of protactinium(V) in hydrofluoric acid (HF) solutions was studied using X-ray absorption spectroscopy. Extended X-ray absorption fine structure measurements were performed on an aqueous solution of 0.05 M protactinium(V) with various HF concentrations ranging from 0.5 to 27 M in order to probe the protactinium coordination sphere with respect to the identity and number of coordinating ligands. The resulting fits to the spectra suggest the presence of an eight-coordinate homoleptic fluoro complex in highly concentrated fluoride solutions (27 M), with equilibrium between seven- and eight-coordinate fluoro complexes at moderate acidities, and in more dilute solutions, results indicate that one water molecule is likely to replace a fluoride in the first coordination sphere, at a distance of 2.54-2.57 Å. Comparisons of this chemistry with group V metals, niobium and tantalum, are presented, and the potential implications for these results on the hydrolytic behavior of protactinium in aqueous systems are discussed. PMID:25389749

  14. Light Enhanced Hydrofluoric Acid Passivation: A Sensitive Technique for Detecting Bulk Silicon Defects.

    PubMed

    Grant, Nicholas E

    2016-01-01

    A procedure to measure the bulk lifetime (>100 µsec) of silicon wafers by temporarily attaining a very high level of surface passivation when immersing the wafers in hydrofluoric acid (HF) is presented. By this procedure three critical steps are required to attain the bulk lifetime. Firstly, prior to immersing silicon wafers into HF, they are chemically cleaned and subsequently etched in 25% tetramethylammonium hydroxide. Secondly, the chemically treated wafers are then placed into a large plastic container filled with a mixture of HF and hydrochloric acid, and then centered over an inductive coil for photoconductance (PC) measurements. Thirdly, to inhibit surface recombination and measure the bulk lifetime, the wafers are illuminated at 0.2 suns for 1 min using a halogen lamp, the illumination is switched off, and a PC measurement is immediately taken. By this procedure, the characteristics of bulk silicon defects can be accurately determined. Furthermore, it is anticipated that a sensitive RT surface passivation technique will be imperative for examining bulk silicon defects when their concentration is low (<10(12) cm(-3)).

  15. A review of treatment strategies for hydrofluoric acid burns: current status and future prospects.

    PubMed

    Wang, Xingang; Zhang, Yuanhai; Ni, Liangfang; You, Chuangang; Ye, Chunjiang; Jiang, Ruiming; Liu, Liping; Liu, Jia; Han, Chunmao

    2014-12-01

    Hydrofluoric acid (HF), a dangerous inorganic acid, can cause severe corrosive effects and systemic toxicity. HF enters the human body via where it contacts, such as skin and mucosa, alimentary and respiratory tracts, and ocular surfaces. In the recent years, the incidence of HF burn has tended to increase over time. The injury mechanism of HF is associated primarily with the massive absorption of HF and the release of hydrogen ions. Correct diagnosis and timely treatment are especially important for HF burns. The critical procedure to treat HF burn is to prevent on-going HF absorption, and block the progressive destruction caused by fluoride ions. Due to the distinct characteristics of HF burns, the topical treatment, as well as systemic support, has been emphasised. Whereas, management of patients with HF burns remains a great challenge in some situations. To date, there has been no widely accepted protocol for the rescue of HF burns, partly due to the diversity of HF burns. This paper overviews the current status and problems of treatment strategies for HF burns, for the purpose of promoting the future researches and improvement.

  16. Intra-Arterial Calcium Gluconate Treatment After Hydrofluoric Acid Burn of the Hand

    SciTech Connect

    Thomas, D. Jaeger, U.; Sagoschen, I.; Lamberti, C.; Wilhelm, K.

    2009-01-15

    Hydrofluoric acid (HF) is a colorless corrosive acid used in different industrial branches. Exposure to HF typically results from spills, and most often the hand or fingers are involved. Tissue damage through cutaneous HF exposure occurs through corrosive burns due to the free hydrogen ions and through skin penetration of the fluoride ions, causing a depletion of calcium in the deep tissue layers, ultimately leading to cell death and tissue necrosis. Treatment of HF burns consists of thoroughly flushing the exposed area with water and applying calcium gluconate gel to the skin. If topical treatment does not suffice, subcutaneous injections, as well as intravascular-both intravenous and intra-arterial-calcium gluconate therapy, have been advocated. We report for the first time a case of HF burn of the hand and digits associated with vasospasm. Pain and vasospasm were successfully treated by repeated intra-arterial calcium gluconate injection. We conclude that intra-arterial calcium gluconate injection is a successful and well-tolerated therapy for HF burn associated with Raynaud's syndrome. Intra-arterial injection allows for well-controlled delivery of therapy as well as assessment of the vascular status.

  17. A review of treatment strategies for hydrofluoric acid burns: current status and future prospects.

    PubMed

    Wang, Xingang; Zhang, Yuanhai; Ni, Liangfang; You, Chuangang; Ye, Chunjiang; Jiang, Ruiming; Liu, Liping; Liu, Jia; Han, Chunmao

    2014-12-01

    Hydrofluoric acid (HF), a dangerous inorganic acid, can cause severe corrosive effects and systemic toxicity. HF enters the human body via where it contacts, such as skin and mucosa, alimentary and respiratory tracts, and ocular surfaces. In the recent years, the incidence of HF burn has tended to increase over time. The injury mechanism of HF is associated primarily with the massive absorption of HF and the release of hydrogen ions. Correct diagnosis and timely treatment are especially important for HF burns. The critical procedure to treat HF burn is to prevent on-going HF absorption, and block the progressive destruction caused by fluoride ions. Due to the distinct characteristics of HF burns, the topical treatment, as well as systemic support, has been emphasised. Whereas, management of patients with HF burns remains a great challenge in some situations. To date, there has been no widely accepted protocol for the rescue of HF burns, partly due to the diversity of HF burns. This paper overviews the current status and problems of treatment strategies for HF burns, for the purpose of promoting the future researches and improvement. PMID:24946967

  18. Effect of stannous fluoride and dilute hydrofluoric acid on early enamel erosion over time in vivo.

    PubMed

    Hjortsjö, C; Jonski, G; Thrane, P S; Saxegaard, E; Young, A

    2009-01-01

    Recent experimental in vivo studies have shown that aqueous solutions of stannous fluoride (SnF(2)) and hydrofluoric acid (HF) can reduce enamel solubility after 5 min. The aim of this study was to evaluate the longer-term protective effect of SnF(2) (0.78%, pH 2.9) and HF (0.2%, pH 2.0) (both approximately 0.1 mol/l F) using the same experimental model. Labial surfaces of healthy anterior teeth (all four surfaces when possible, otherwise a pair of surfaces) in 103 subjects (n = 399 teeth) were exposed to citric acid (0.01 mol/l, pH 2.7). The acid was applied using a peristaltic pump (5 ml, 6 ml/min) and was collected in coded test tubes (etch I). The test solutions were then applied to the same surfaces of the teeth (1 min, 6 ml/min). After either 1, 7, 14 or 28 days, citric acid was again applied to the same surfaces and subsequently collected (etch II). Enamel solubility was examined by assessment of calcium concentration in etch I and etch II solutions using atom absorption spectroscopy. Median values were calculated for all time periods and statistical analysis was carried out using the Wilcoxon signed-ranks test. Results showed that HF reduced enamel solubility by 54 and 36% after 1 and 7 days, respectively. After 14 and 28 days, there was no longer any effect. SnF(2) showed no protective effect after the first day. Given these results, repeated application of HF and especially SnF(2) may be necessary to improve the protective effect of these fluorides, and this requires further testing.

  19. Hydrofluoric acid etched stainless steel wire for solid-phase microextraction.

    PubMed

    Xu, Hua-Ling; Li, Yan; Jiang, Dong-Qing; Yan, Xiu-Ping

    2009-06-15

    Stainless steel wire has been widely used as the substrate of solid-phase microextraction (SPME) fibers to overcome the shortcomings of conventional silica fibers such as fragility, by many researchers. However, in previous reports various sorbent coatings are always required in conjunction with the stainless steel wire for SPME. In this work, we report the bare stainless steel wire for SPME without the need for any additional coatings taking advantage of its high mechanical and thermal stability. To evaluate the performance of stainless steel wire for SPME, polycyclic aromatic hydrocarbons (PAHs), benzene, toluene, ethylbenzene, chlorobenzene, n-propylbenzene, aniline, phenol, n-hexane, n-octane, n-decane, n-undecane, n-dodecane, chloroform, trichloroethylene, n-octanol, and butanol were tested as analytes. Although the stainless steel wire had almost no extraction capability toward the tested analytes before etching, it did exhibit high affinity to the tested PAHs after etching with hydrofluoric acid. The etched stainless steel wire gave a much bigger enhancement factor (2541-3981) for the PAHs than the other analytes studied (< or = 515). Etching with hydrofluoric acid produced a porous and flower-like structure with Fe(2)O(3), FeF(3), Cr(2)O(3), and CrF(2) on the surface of the stainless steel wire, giving high affinity to the PAHs due to cation-pi interaction. On the basis of the high selectivity of the etched stainless steel wire for PAHs, a new SPME method was developed for gas chromatography with flame ionization detection to determine PAHs with the detection limits of 0.24-0.63 microg L(-1). The precision for six replicate extractions using one SPME fiber ranged from 2.9% to 5.3%. The fiber-to-fiber reproducibility for three parallel prepared fibers was 4.3-8.8%. One etched stainless steel wire can stand over 250 cycles of SPME without significant loss of extraction efficiency. The developed etched stainless steel wire is very stable, highly selective, and

  20. Arsenic contamination of coarse-grained and nanostructured nitinol surfaces induced by chemical treatment in hydrofluoric acid.

    PubMed

    Korotin, D M; Bartkowski, S; Kurmaev, E Z; Borchers, C; Müller, M; Neumann, M; Gunderov, D V; Valiev, R Z; Cholakh, S O

    2012-10-01

    XPS measurements of coarse-grained and nanostructured nitinol (Ni(50.2)Ti(49.8)) before and after chemical treatment in hydrofluoric acid (40% HF, 1 min) are presented. The nanostructured state, providing the excellent mechanical properties of nitinol, is achieved by severe plastic deformation. The near-surface layers of nitinol were studied by XPS depth profiling. According to the obtained results, a chemical treatment in hydrofluoric acid reduces the thickness of the protective TiO(2) oxide layer and induces a nickel release from the nitinol surface and an arsenic contamination, and can therefore not be recommended as conditioning to increase the roughness of NiTi-implants. A detailed evaluation of the resulting toxicological risks is given.

  1. Dermal absorption and skin damage following hydrofluoric acid exposure in an ex vivo human skin model.

    PubMed

    Dennerlein, Kathrin; Kiesewetter, Franklin; Kilo, Sonja; Jäger, Thomas; Göen, Thomas; Korinth, Gintautas; Drexler, Hans

    2016-04-25

    The wide industrial use of hydrofluoric acid (HF) poses a high risk for accidental dermal exposure. Despite local and systemic hazards associated with HF, information on percutaneous penetration and tissue damage is rare. In the present ex vivo study, the dermal absorption of HF (detected in terms of fluoride ions) was quantified and the skin damaging potential as a function of concentration and exposure duration was assessed. Percutaneous penetration of HF (c=5, 30, and 50%) at 3 exposure durations (3, 5, and 10 min) was investigated in a static diffusion cell model using freshly excised human skin. Alterations of skin were histologically evaluated. HF rapidly penetrated through skin under formation of a considerable intradermal reservoir (∼ 13-67% of total absorbed fluoride). Histologically, epidermal alterations were detected already after exposure to 5% HF for 3 min. The degree of skin damage increased with rising concentration and exposure duration leading to coagulation necrosis. For HF concentrations of ≥ 30%, skin damage progressed into deeper skin layers. Topically applied HF concentration was the principal parameter determining HF induced skin effects. The intradermal HF retention capacity associated with progression and prolongation of HF induced skin effects must be considered in the review of skin decontamination procedures.

  2. Possible hazardous effects of hydrofluoric acid and recommendations for treatment approach: a review.

    PubMed

    Ozcan, Mutlu; Allahbeickaraghi, Arezo; Dündar, Mine

    2012-02-01

    Hydrofluoric acid (HF) is commonly used for conditioning the glass ceramics either prior to cementation or for intraoral repair in prosthetic and restorative dentistry. The present study offers a review of chemical properties of HF used, highlight the possible hazardous effects of this agent, and to recommend the treatment approach for potential risks. Available published information documented in PubMed, Medline, and Picarta literature databases was reviewed. Additional information was derived from scientific reports, medical and chemical textbooks, handbooks, product information, manufacturers' instructions, Internet web sites of the HF manufacturers. No report was found on the incidence of the hazardous effects of HF in dentistry. Reports from other fields presented incidences of acute and chronic symptoms in exposure to HF. While acute symptoms include skin or nail burns, chronic ones involve systemic toxicity, eye injuries, inhalation and ingestion-related symptoms that can be even fatal. HF can be harmful and particularly aggressive to soft tissues, but symptoms may not be apparent immediately after exposure. The hazardous effects are not based on the pH value, but on the toxicity of HF. Potential hazards of HF known from other applications than dentistry should be considered also in dental applications. Especially the clinicians, who often deal with adhesive cementation or repair of glass ceramics, should take necessary precautions for possible hazards of HF.

  3. Dissolution of fluoride complexes following microwave-assisted hydrofluoric acid digestion of marine sediments.

    PubMed

    Muratli, Jesse M; McManus, James; Mix, Alan; Chase, Zanna

    2012-01-30

    Microwave-assisted, hydrofluoric acid digestion is an increasingly common tool for the preparation of marine sediment samples for analysis by a variety of spectrometric techniques. Here we report that analysis of terrigenous-dominated sediment samples occasionally results in anomalously low values for several elements, including Al, Ba, Ca, Mg, and Sr. Measured concentrations of these elements increased with time between sample preparation and sample analysis, reaching stable values after 8-29 days. This lag is explained by the formation and subsequent dissolution of poorly soluble fluoride phases during digestion. Other elements, such as Fe, Mn, and Ti, showed little or no lag and were quickly measurable at a stable value. Full re-dissolution of the least soluble fluorides, which incorporate Al and Mg, requires up to four weeks at room temperature, and this duration can vary among sedimentary matrices. This waiting time can be reduced to 6 days (or shorter) if the samples are heated to ≈ 60°C for 24h.

  4. Comparison of skin effects of immediate treatment modalities in experimentally induced hydrofluoric acid skin burns.

    PubMed

    Songur, Meltem K; Akdemir, Ovunc; Lineaweaver, William C; Cavusoglu, Turker; Ozsarac, Murat; Aktug, Huseyin; Songur, Ecmel; Tiftikcioglu, Yigit O

    2015-12-01

    Hydrofluoric acid (HF) burns cause immediate damage and painful long-term sequellae. Traditionally, chelating agents have been used as the initial treatment for such burns. We have introduced epidermal growth factor (EGF) into an HF model to compare EGF with Ca(2+) and Mg(2+) treatments; 40 Sprague Dawley rats were divided into five groups. Each rat suffered a 6 × 4 cm(2) burn induced by 40% HF. Group 1 had no treatment, group 2 had saline injected beneath the burn, group 3 received magnesium sulphate injections, group 4 received calcium gluconate and group 5 received EGF. Specimens were evaluated via planimetry and biopsy at intervals of 4, 8, 24 and 72 hours. Fluid losses were significantly less in the Mg(2+) and EGF groups. The EGF group had the smallest burn area, least oedema, least polymorphonuclear granulocyte (PMN) infiltration, most angiogenesis and highest fibroblast proliferation of any group (P < 0·005). EGF limited HF damage morphologically and histologically more effectively than Ca(2+) or Mg(2+). This finding indicates that HF treatment via growth factors may be an improvement over chelation therapy.

  5. Influence of solution volume on the dissolution rate of silicon dioxide in hydrofluoric acid.

    PubMed

    Shvartsev, Boris; Gelman, Danny; Komissarov, Ilia; Epshtein, Alon; Starosvetsky, David; Ein-Eli, Yair

    2015-02-01

    Experimental data and modeling of the dissolution of various Si/SiO2 thermal coatings in different volumes of hydrofluoric acid (HF) are reported. The rates of SiO2 -film dissolution, measured by means of various electrochemical techniques, and alteration in HF activity depend on the thickness of the film coating. Despite the small volumes (0.6-1.2 mL) of the HF solution, an effect of SiO2 -coating thickness on the dissolution rate was detected. To explain alterations detected in HF activity after SiO2 dissolution, spectroscopic analyses (NMR and FTIR) of the chemical composition of the solutions were conducted. This is associated with a modification in the chemical composition of the HF solution, which results in either the formation of an oxidized species in solution or the precipitation of dissolution products. HF2 (-) accumulation in the HF solution, owing to SiO2 dissolution was identified as the source of the chemical alteration.

  6. Functionalization of graphene and few-layer graphene with aqueous solution of hydrofluoric acid

    NASA Astrophysics Data System (ADS)

    Nebogatikova, N. A.; Antonova, I. V.; Volodin, V. A.; Prinz, V. Ya.

    2013-08-01

    In the present study, conditions suitable for efficient modification of graphene and few-layer graphene (FLG) films with aqueous solutions of hydrofluoric acid (HF) and for local protection of the graphene against such modification in isopropyl alcohol were identified. A combination of the two treatments gives one a key to nanodesign of graphene-based 2D devices. It was found that a few-minute treatment of graphene or FLG in HF aqueous solutions (∼1 min for graphene and ∼5 min for FLG films about 5 nm thick) leads to strong changes in the structural and electrical properties of graphene involving a step-like increase in resistivity (up to 1011 Ω/□). Two types of materials were obtained after different times of treatment: (i) promising for electronic applications of the material due to a combination of high carrier mobility, high conductivity, and strong current modulation by gate voltage (up to four orders of magnitude); (ii) a material with insulating properties and graphene quantum dots embedded in an insulating matrix.

  7. Fluorine distribution in soil in the vicinity of an accidental spillage of hydrofluoric acid in Korea.

    PubMed

    An, Jinsung; Lee, Hyun A; Lee, Junseok; Yoon, Hye-On

    2015-01-01

    This study assessed the status of fluorine (F) in soil in the vicinity of a spillage of anhydrous hydrofluoric acid in Korea. Gaseous hydrogen fluoride dispersed was suspected to have contaminated the surrounding soil environment. Total and water soluble F concentrations in soil within a 1 km radius of the spillage were determined. Total F concentrations (mean=222±70.1 mg kg(-1)) were lower than the Korean limit value (i.e., 400 mg kg(-1)) and several reported measurements of background F concentrations in soils except for a single outlying case. Soluble F concentrations ranged from 0.111 to 6.40 mg kg(-1) (mean=2.20±1.80 mg kg(-1)). A negative correlation between the soluble F concentration of soil and distance from the spillage was observed. This indicates that the soluble F concentration has a crucial role in fractionating the F concentration arising from a 'non natural input' i.e., the spillage. The F content of rice samples seemed to be significantly influenced by the soluble F concentrations of soils. Rice samples collected from the control and affected areas contained 41 mg kg(-1) and 578 mg kg(-1) of total F, respectively.

  8. Characteristics of fluoride in pore-water at accidental hydrofluoric acid spillage site, Gumi, Korea

    NASA Astrophysics Data System (ADS)

    Kwon, E. H.; Lee, H. A.; Lee, J.; Kim, D.; Lee, S.; Yoon, H. O.

    2015-12-01

    A leakage accident of hydrofluoric acid (HF) occurred in Gumi, South Korea at Sep. 2012. The study site is located in the borderline between a large-scale industrial complex and a rural area. The HF plume was made immediately, and moved toward the rural area through air. After the accident, 212 ha of farm land were influenced and most of crops were withered. To recover the soil, CaO was applied after six months. Although several studies have done to estimate the extension and movement of HF plume in the air and to assess the impact on human health or plant after the incident, the long-term fate of fluoride (F) in the affected soils is not identified clearly. Thus, this study aimed to understand the behavior of F in the soil after HF releasing from accident site through chemical analysis and geochemical modeling. Within the radius of 1 km of accident site, 16 pore-water and soil samples were collected. The semi-quantitative soil composition (i.e., Al, Ca, Fe, K, Mg, Mn, Na, P, Si, Ti), total F, total P, OM contents in soil, and soil pH have already been measured, and pore-water compositions are also identified. From these experimental and modeling data, we could be evaluate if impact of accident exists until now, and also could be select and identify existing form of fluoride in soil and pore-water.

  9. The effect of hydrofluoric acid treatment on titanium implant osseointegration in ovariectomized rats.

    PubMed

    Li, Yunfeng; Zou, Shujuan; Wang, Dazhang; Feng, Ge; Bao, Chongyun; Hu, Jing

    2010-04-01

    This study aimed to investigate the effects of hydrofluoric acid (HF) treatment of grit-blasted Ti implants on osseointegration in ovariectomized (OVX) rats. After blasting with aluminium oxide particles, half implants were treated with 0.2 vol.% HF, and the other half were kept non-modified as control. The topographical and chemical changes of implant surface were determined by Scanning Electron Microscope, Atomic Force Microscope, and X-ray Photoemission Spectroscopy. 12 Weeks after bilateral ovariectomy, each rat accepted two implants in distal femora, with the control implant on the left and the fluoride-modified on the right. As a result, fluoride modification induced markedly changed surface topography and chemical composition. 12 Weeks after implant insertion, the fluoride-modified implants showed improved osseointegration compared to control, with the bone area ratio and bone-to-implant contact increased by 0.9- and 1.4-fold in histomorphometry, the bone volume ratio and percent osseointegration by 0.8- and 1.3-fold in micro-CT evaluation, and the maximal push-out force and ultimate shear strength by 1.2- and 2.0-fold in biomechanical test. These promising results indicated that HF treatment of Ti surface improved implant osseointegration in OVX rats, and suggested the feasibility of using fluoride modification to improve Ti implant osseointegration in osteoporotic bone. PMID:20132983

  10. Characterization and adsorption properties of diatomaceous earth modified by hydrofluoric acid etching.

    PubMed

    Tsai, Wen-Tien; Lai, Chi-Wei; Hsien, Kuo-Jong

    2006-05-15

    This work was a study of the chemical modification of diatomaceous earth (DE) using hydrofluoric acid (HF) solution. Under the experimental conditions investigated, it was found that HF under controlled conditions significantly etched inward into the interior of the existing pore structure in the clay mineral due to its high content of silica, leaving a framework possessing a larger BET surface area (ca. 10 m2 g(-1)) in comparison with that (ca. 4 m2 g(-1)) of its precursor (i.e., DE). Further, the results indicated that the HF concentration is a more determining factor in creating more open pores than other process parameters (temperature, holding time, and solid/liquid ratio). This observation was also in close agreement with the examinations by the silicon analysis, scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. The adsorption kinetics and the adsorption isotherm of methylene blue onto the resulting clay adsorbent can be well described by a pseudo-second-order reaction model and the Freundlich model, respectively.

  11. Adhesion of resin composite to hydrofluoric acid-exposed enamel and dentin in repair protocols.

    PubMed

    Saracoglu, A; Ozcan, M; Kumbuloglu, O; Turkun, M

    2011-01-01

    Intraoral repairs of ceramic fixed-dental-prostheses (FDP) often include cervical recessions that require pretreatment of the exposed tooth surfaces either before or after the ceramic is conditioned with hydrofluoric (HF) acid gel. The sequence of repair protocol may cross-contaminate the exposed etched enamel or dentin surfaces during the application or rinsing process and thereby affect the adhesion. This study evaluated the influence of HF acid gel with two concentrations on bond strengths of composite to enamel and dentin. Human third molars (N=100, n=10 per group) with similar sizes were selected and randomly divided into 10 groups. Flat surfaces of enamel and dentin were created by wet ground finishing. Before or after the enamel (E) or dentin (D) was conditioned with phosphoric acid (P), substrate surfaces were conditioned with either 9.5% HF (HF(9.5)) or 5% HF (HF(5)). Subsequently, a bonding agent (B) was applied. The experimental groups by conditioning sequence were as follows where the first letter of the group abbreviation represents the substrate (E or D) followed by the acid type and concentration: group 1 (EPHF(9.5)), group 2 (EPHF(5)), group 3 (EHF(9.5)P), group 4 (EHF(5)P), group 5 (DPHF(9.5)), group 6 (DPHF(5)), group 7 (DHF(9.5)P), and group 8 (DHF(5)P). Group 9 (EPB) and group 10 (DPB) acted as the control groups. Repair resin was adhered incrementally onto the conditioned enamel and dentin in polyethylene molds. Each layer was photo-polymerized for 40 seconds. All specimens were thermocycled (×1000, 5°-55°C) and subjected to shear test (universal testing machine, 1 mm/min). Specimens that debonded during thermocycling were considered as 0 MPa. The bond strength data were analyzed using Kruskal-Wallis test and failure types using the chi-square test (α=0.05). Overall, the bond results (MPa) were lower on dentin than on enamel (p<0.01). EPB (25.6 ± 6.6) and DPB (20.2 ± 4.9) control groups showed significantly higher results than those of

  12. Adhesion of resin composite to hydrofluoric acid-exposed enamel and dentin in repair protocols.

    PubMed

    Saracoglu, A; Ozcan, M; Kumbuloglu, O; Turkun, M

    2011-01-01

    Intraoral repairs of ceramic fixed-dental-prostheses (FDP) often include cervical recessions that require pretreatment of the exposed tooth surfaces either before or after the ceramic is conditioned with hydrofluoric (HF) acid gel. The sequence of repair protocol may cross-contaminate the exposed etched enamel or dentin surfaces during the application or rinsing process and thereby affect the adhesion. This study evaluated the influence of HF acid gel with two concentrations on bond strengths of composite to enamel and dentin. Human third molars (N=100, n=10 per group) with similar sizes were selected and randomly divided into 10 groups. Flat surfaces of enamel and dentin were created by wet ground finishing. Before or after the enamel (E) or dentin (D) was conditioned with phosphoric acid (P), substrate surfaces were conditioned with either 9.5% HF (HF(9.5)) or 5% HF (HF(5)). Subsequently, a bonding agent (B) was applied. The experimental groups by conditioning sequence were as follows where the first letter of the group abbreviation represents the substrate (E or D) followed by the acid type and concentration: group 1 (EPHF(9.5)), group 2 (EPHF(5)), group 3 (EHF(9.5)P), group 4 (EHF(5)P), group 5 (DPHF(9.5)), group 6 (DPHF(5)), group 7 (DHF(9.5)P), and group 8 (DHF(5)P). Group 9 (EPB) and group 10 (DPB) acted as the control groups. Repair resin was adhered incrementally onto the conditioned enamel and dentin in polyethylene molds. Each layer was photo-polymerized for 40 seconds. All specimens were thermocycled (×1000, 5°-55°C) and subjected to shear test (universal testing machine, 1 mm/min). Specimens that debonded during thermocycling were considered as 0 MPa. The bond strength data were analyzed using Kruskal-Wallis test and failure types using the chi-square test (α=0.05). Overall, the bond results (MPa) were lower on dentin than on enamel (p<0.01). EPB (25.6 ± 6.6) and DPB (20.2 ± 4.9) control groups showed significantly higher results than those of

  13. Solution of rocks and refractory minerals by acids at high temperatures and pressures. Determination of silica after decomposition with hydrofluoric acid

    USGS Publications Warehouse

    May, I.; Rowe, J.J.

    1965-01-01

    A modified Morey bomb was designed which contains a removable nichromecased 3.5-ml platinium crucible. This bomb is particularly useful for decompositions of refractory samples for micro- and semimicro-analysis. Temperatures of 400-450?? and pressures estimated as great as 6000 p.s.i. were maintained in the bomb for periods as long as 24 h. Complete decompositions of rocks, garnet, beryl, chrysoberyl, phenacite, sapphirine, and kyanite were obtained with hydrofluoric acid or a mixture of hydrofluoric and sulfuric acids; the decomposition of chrome refractory was made with hydrochloric acid. Aluminum-rich samples formed difficultly soluble aluminum fluoride precipitates. Because no volatilization losses occur, silica can be determined on sample solutions by a molybdenum-blue procedure using aluminum(III) to complex interfering fluoride. ?? 1965.

  14. Acute health effects in a community after a release of hydrofluoric acid

    SciTech Connect

    Wing, J.S.; Brender, J.D.; Sanderson, L.M.; Perrotta, D.M.; Beauchamp, R.A. )

    1991-05-01

    {approximately} 3,000 persons were evacuated from a Texas community after 24,036 kg (53,000 lb) of caustic hydrofluoric acid (HF) were released from a nearby petrochemical plant. Emergency room and hospital records of 939 persons who were seen at two area hospitals were reviewed. Most persons who presented at the emergency rooms were female (56%) or black (60%), and their mean age was 33.9 y. The most frequently reported symptoms were eye irritation (41.5%), burning throat (21%), headache (20.6%), and shortness of breath (19.4%). Physical examination results were normal for 49% of the cases; however, irritation of the eyes, nose, throat, skin, and lungs were noted on other exams. Decreased pulmonary function was demonstrated by pulmonary function tests (forced expiratory volume in the first second, less than 80% of predicted value, 42.3%); hypoxemia (pO2 less than 80 mm Hg, 17.4%) and hypocalcemia (less than 8.5 mg/dl, 16.3%) were also noted. Ninety-four (10%) of the cases were hospitalized, and more than 83% of all cases were discharged with a primary diagnosis of HF exposure. There are several reports of individuals who are acutely and chronically exposed to HF; however, we are unaware of other published reports that describe exposure of a community to HF. This incident represented a unique opportunity to study the immediate health impact on a community of residents who were exposed to a hazardous materials release. Results of this analysis suggest that (a) initial health problems should be followed up, (b) any long-term health effects of HF exposure must be assessed, and (c) the health impact on the population at risk should be determined.

  15. Hydrofluoric-nitric-sulphuric-acid surface treatment of tungsten for carbon fibre-reinforced composite hybrids in space applications

    NASA Astrophysics Data System (ADS)

    Kanerva, M.; Johansson, L.-S.; Campbell, J. M.; Revitzer, H.; Sarlin, E.; Brander, T.; Saarela, O.

    2015-02-01

    Hybrid material systems, such as combinations of tungsten foils and carbon fibre-reinforced plastic (CFRP), are replacing metal alloy concepts in spacecraft enclosures. However, a good adhesion between the tungsten oxide scale and the epoxy resin used is required. Here, the effects of a hydrofluoric-nitric-sulphuric-acid (HFNS) treatment on tungsten oxides and subsequent adhesion to CFRP are analysed using atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and fracture testing. The work shows that HFNS treatment results in decreased oxygen content, over 50% thinner tungsten trioxide (WO3) layer and increased nano-roughness on thin tungsten foils. Fracture testing established a 39% increase in the average critical strain for tungsten-CFRP specimens after HFNS treatment was carried out on tungsten. The effect of the oxide scale modification regarding the critical strain energy release rate was ΔGc≈ 8.4 J/m2.

  16. Hydrofluoric Acid Controlled TiO2 Phase Transformation from Rutile to Anatase at Room Temperature and Their Photocatalytic Performance.

    PubMed

    Ge, Suxiang; Li, Dapeng; Jia, Gaoyang; Wang, Beibei; Yang, Zhen; Yang, Zongyang; Qiao, Hui; Zhang, Yange; Zheng, Zhi

    2015-09-01

    In this study, we first present rutile TiO2 superstructures could be successfully transformed into anatase TiO2 nanoparticles at room temperature by adjusting the amount of hydrofluoric acid (HF) used in aqueous solution. Photocatalytic experiments demonstrated that the as prepared anatase TiO2 exhibited better photocatalytic performance than that of rutile TiO2. We further studied the photocatalytic degradation of RhB on different TiO2 via active species trapping experiments and confirmed that the presence of surface F- on TiO2 was beneficial for the formation of *OH, which was thought to be mainly responsible for the enhancement of photocatalytic performance.

  17. Shear bond strength of metal brackets to feldspathic porcelain treated by Nd:YAG laser and hydrofluoric acid.

    PubMed

    Hosseini, Mohammad Hashem; Sobouti, Farhad; Etemadi, Ardavan; Chiniforush, Nasim; Shariati, Mahsa

    2015-02-01

    Adult orthodontic treatment requires bonding orthodontic attachment to dental restorations. Ceramics are commonly used as esthetic restorative materials for the crowns and bridges. The present study evaluated the shear bond strength of metal orthodontic brackets to the feldspathic porcelain surfaces following conditioning by different powers of neodymium-doped yttrium aluminum garnet (Nd:YAG) laser and hydrofluoric acid as a conventional method. Seventy-two glazed porcelain samples were prepared and randomly attributed to six equal groups of 12. In the conventional hydrofluoric (HF) group, the specimens were etched by 9.6% hydrofluoric acid for 4 min. In laser groups, samples were conditioned by 0.75-, 1-, 1.25-, 1.5-, and 2-W Nd:YAG laser for 10 s. Metal brackets were bonded to porcelain samples and after being stored in distilled water for 24 h, they were subjected to thermocycling for 500 cycles. The debonding was carried out by a Zwick testing machine. The data were statistically analyzed by ANOVA and Tamhane multiple comparisons tests. The mean ± SD of the shear bond strength in the laser group 0.75, 1, 1.25, 1.5, and 2 W and HF group was 2.2 ± 0.9, 4.2 ± 1.1, 4.9 ± 2.4, 7 ± 1.7, 9.6 ± 2.7, and 9.4 ± 2.5, respectively. Together with the increased power of laser, the mean shear bond strength was increased continuously and no significant differences were found between the HF group and the laser groups with power of 1.5 or 2 W. Also, there was no significant difference between all test groups in ARI scores. There was no significant difference between bond strength of laser groups with power of 1.5 and 2 W and HF-etched group. So, Nd:YAG laser with appropriate parameters can be used as an alternative method for porcelain etching.

  18. Improved corrosion resistance of Hastelloy G-30 in nitric/hydrofluoric acid solutions by welding with Inconel 72 weld wire

    SciTech Connect

    Norby, B.C.

    1992-03-03

    When welding Hastelloy G-30, secondary phases form in the weld metal. These phases cause the weld metal to be preferentially attacked in nitric acid (HN0{sub 3}) solutions contaminated with minor amounts of hydrofluoric acid (HF). A post weld solution anneal and water quench is necessary to assure that these phases redissolve into the solid. When a post weld solution anneal and water quench is not feasible, improved corrosion resistance can be obtained by welding with INCO 72 weld wire. When welding Hastelloy G-30 with INCO 72, there can be a region at the weldmetal/base-metal interface that does not benefit from the INCO 72 weld wire. This region consists of melted and resolidified Hastelloy G-30. This unmixed zone can be preferentially attacked in HN03 solutions contaminated with minor amounts of HF. Long term corrosion immersion tests have shown that the rate of attack at the weld-metal/base-metal interface can be as high as 50 mpy. Welding techniques that increase the mixing of the melted Hastelloy G-30 with the INCO 72 weld wire can reduce the interface corrosion rate.

  19. Detection of hydrofluoric acid by a SiO2 sol-gel coating fiber-optic probe based on reflection-based localized surface plasmon resonance.

    PubMed

    Chen, I-Cherng; Lin, Shiu-Shiung; Lin, Tsao-Jen; Du, Je-Kang

    2011-01-01

    A novel fiber-optic probe based on reflection-based localized surface plasmon resonance (LSPR) was developed to quantify the concentration of hydrofluoric acid (HF) in aqueous solutions. The LSPR sensor was constructed with a gold nanoparticle-modified PMMA fiber, integrated with a SiO(2) sol-gel coating. This fiber-sensor was utilized to assess the relationship between HF concentration and SiO(2) sol-gel layer etching reduction. The results demonstrated the LSPR sensor was capable of detecting HF-related erosion of hydrofluoric acid solutions of concentrations ranging from 1% to 5% using Relative RI Change Rates. The development of the LSPR sensor constitutes the basis of a detector with significant sensitivity for practical use in monitoring HF solution concentrations.

  20. Detection of Hydrofluoric Acid by a SiO2 Sol-Gel Coating Fiber-Optic Probe Based on Reflection-Based Localized Surface Plasmon Resonance

    PubMed Central

    Chen, I-Cherng; Lin, Shiu-Shiung; Lin, Tsao-Jen; Du, Je-Kang

    2011-01-01

    A novel fiber-optic probe based on reflection-based localized surface plasmon resonance (LSPR) was developed to quantify the concentration of hydrofluoric acid (HF) in aqueous solutions. The LSPR sensor was constructed with a gold nanoparticle-modified PMMA fiber, integrated with a SiO2 sol-gel coating. This fiber-sensor was utilized to assess the relationship between HF concentration and SiO2 sol-gel layer etching reduction. The results demonstrated the LSPR sensor was capable of detecting HF-related erosion of hydrofluoric acid solutions of concentrations ranging from 1% to 5% using Relative RI Change Rates. The development of the LSPR sensor constitutes the basis of a detector with significant sensitivity for practical use in monitoring HF solution concentrations. PMID:22319388

  1. In vitro degradation behavior and biocompatibility of Mg-Nd-Zn-Zr alloy by hydrofluoric acid treatment.

    PubMed

    Mao, Lin; Yuan, Guangyin; Niu, Jialin; Zong, Yang; Ding, Wenjiang

    2013-01-01

    In this paper, Mg-Nd-Zn-Zr alloy (denoted as JDBM) coated with hydrofluoric acid (HF) chemical conversion film (MgF2) was researched as a potential biodegradable cardiovascular stent material. The microstructures, in vitro degradation and biocompatibility were investigated. The field emission scanning electron microscopy (FE-SEM) and X-ray photoelectron spectroscopy (XPS) showed that a compact MgF2 film was formed on the surface of JDBM. The corrosion rate decreased in artificial plasma from 0.337 to 0.253 mm·y(-1) and the electrochemical measurement demonstrated that the corrosion resistance of JDBM alloy could be obviously improved due to the protective MgF2 film on the surface of the substrate. Meanwhile, the hemolysis ratio of JDBM decreased from 52.0% to 10.1% and the cytotoxicity met the requirement of cellular application after HF treatment. In addition, JDBM and MgF2 film showed good anti-platelet adhesion, which is a very favorable property for implant material in contact with blood directly.

  2. Seventy per cent hydrofluoric acid burns: delayed decontamination with hexafluorine® and treatment with calcium gluconate.

    PubMed

    Yoshimura, Carlos Alberto; Mathieu, Laurence; Hall, Alan H; Monteiro, Mário G Kool; de Almeida, Décio Moreira

    2011-01-01

    This is a case report of decontamination and treatment of a 70% hydrofluoric acid (HF) dermal splash injury. A worker was splashed with 70% HF, sustaining approximately 10% TBSA first- to third-degree chemical skin burns of the face, trunk, and left thigh and leg. Initial decontamination involved water rinsing, removal of contaminated clothing, more water rinsing, topical application of magnesium oxide, and administration of intravenous narcotics for management of severe pain. After a delay of approximately 3 hours, active skin washing with Hexafluorine®, 5 L, was performed, followed by intravenous, intradermal perilesional, and topical inunction administration of calcium gluconate. Pain relief and a cooling sensation were quite prompt after Hexafluorine® decontamination. Surgical debridement and skin grafting of the more severe burns were required. No significant systemic toxicity developed, although this has occurred in previously reported similar concentrated HF dermal splash exposure cases, some of which resulted in fatality. While burns did develop, the patient was released from the intensive care service after 2 days and, after skin grafting, had a good outcome at 90-day follow-up. Even after a long delay, decontamination with Hexafluorine® appeared to be beneficial in this case.

  3. Effect of hydrofluoric acid etching on shear bond strength of an indirect resin composite to an adhesive cement.

    PubMed

    Hori, Sayaka; Minami, Hiroyuki; Minesaki, Yoshito; Matsumura, Hideo; Tanaka, Takuo

    2008-07-01

    This study evaluated the effect of 1% hydrofluoric acid (HF) treatment on the bonding of an adhesive cement (Panavia F 2.0) to an indirect resin composite (Estenia C&B). Pairs of composite disks (10 and 8 mm in diameter by 3 mm thickness) were prepared. Adhesive surfaces were pretreated with either airborne particle abrasion or HF etching before being soaked for 30 seconds, five minutes or 10 minutes, with or without application of silane coupling agent. Adhesive specimens were fabricated by cementing a pair of treated disks. Shear bond strength was determined before and after 50,000 times of thermocycling (4 and 60 degrees C). All data were statistically analyzed using two-way ANOVA and Bonferroni's test (a=0.05). Bond strength achieved with five minutes of HF etching (18.3+/-1.1 MPa) was significantly higher (P=0.0025) than that obtained with airborne particle abrasion followed by application of silane coupling agent (14.3+/-1.8 MPa) after thermocycling.

  4. The Effect of Hydrofluoric Acid Etching Duration on the Surface Micromorphology, Roughness, and Wettability of Dental Ceramics.

    PubMed

    Ramakrishnaiah, Ravikumar; Alkheraif, Abdulaziz A; Divakar, Darshan Devang; Matinlinna, Jukka P; Vallittu, Pekka K

    2016-05-27

    The current laboratory study is evaluating the effect of hydrofluoric acid etching duration on the surface characteristics of five silica-based glass ceramics. Changes in the pore pattern, crystal structure, roughness, and wettability were compared and evaluated. Seventy-five rectangularly shaped specimens were cut from each material (IPS e-max™, Dentsply Celtra™, Vita Suprinity™, Vita mark II™, and Vita Suprinity FC™); the sectioned samples were finished, polished, and ultrasonically cleaned. Specimens were randomly assigned into study groups: control (no etching) and four experimental groups (20, 40, 80 and 160 s of etching). The etched surfaces' microstructure including crystal structure, pore pattern, pore depth, and pore width was studied under a scanning electron microscope, and the surface roughness and wettability were analyzed using a non-contact surface profilometer and a contact angle measuring device, respectively. The results were statistically analyzed using one-way analysis of variance (ANOVA) and the post hoc Tukey's test. The results showed a significant change in the pore number, pore pattern, crystal structure, surface roughness, and wettability with increased etching duration. Etching for a short time resulted in small pores, and etching for longer times resulted in wider, irregular grooves. A significant increase in the surface roughness and wettability was observed with an increase in the etching duration. The findings also suggested a strong association between the surface roughness and wettability.

  5. Properties of LaAlO Film after Waterless Process Using Organic Solvent Containing Anhydrous Hydrofluoric Acid

    NASA Astrophysics Data System (ADS)

    Masatomo Honjo,; Naoyoshi Komatsu,; Takuro Masuzumi,; Hidemitsu Aoki,; Daisuke Watanabe,; Chiharu Kimura,; Takashi Sugino,

    2010-04-01

    Lanthanum (La)-based oxide films have been studied as high-k (high dielectric constant) gate dielectrics. However, moisture absorption is a serious problem for oxide films containing La. We have attempted to use waterless solutions instead of water-based solutions to remove high-k films to suppress the moisture absorption of the lanthanum aluminate (LaAlO) film. We report the effect of an anhydrous hydrofluoric acid (AHF) and isopropyl alcohol (IPA) mixed solution as an etching solution and hydrofluoro-ether (HFE) as a rising solution on the properties of LaAlO films. We have succeeded in suppressing the moisture absorption of LaAlO films by using waterless solutions for a front end of line (FEOL) process. In addition, the selectivity (LaAlO/SiO2), the etching ratio of LaAlO to SiO2, was improved using this process. It is considered that this technology will be useful for the next-generation devices with lanthanum-based oxide films.

  6. Correlation of film density and wet etch rate in hydrofluoric acid of plasma enhanced atomic layer deposited silicon nitride

    NASA Astrophysics Data System (ADS)

    Provine, J.; Schindler, Peter; Kim, Yongmin; Walch, Steve P.; Kim, Hyo Jin; Kim, Ki-Hyun; Prinz, Fritz B.

    2016-06-01

    The continued scaling in transistors and memory elements has necessitated the development of atomic layer deposition (ALD) of silicon nitride (SiNx), particularly for use a low k dielectric spacer. One of the key material properties needed for SiNx films is a low wet etch rate (WER) in hydrofluoric (HF) acid. In this work, we report on the evaluation of multiple precursors for plasma enhanced atomic layer deposition (PEALD) of SiNx and evaluate the film's WER in 100:1 dilutions of HF in H2O. The remote plasma capability available in PEALD, enabled controlling the density of the SiNx film. Namely, prolonged plasma exposure made films denser which corresponded to lower WER in a systematic fashion. We determined that there is a strong correlation between WER and the density of the film that extends across multiple precursors, PEALD reactors, and a variety of process conditions. Limiting all steps in the deposition to a maximum temperature of 350 °C, it was shown to be possible to achieve a WER in PEALD SiNx of 6.1 Å/min, which is similar to WER of SiNx from LPCVD reactions at 850 °C.

  7. The Effect of Hydrofluoric Acid Etching Duration on the Surface Micromorphology, Roughness, and Wettability of Dental Ceramics

    PubMed Central

    Ramakrishnaiah, Ravikumar; Alkheraif, Abdulaziz A.; Divakar, Darshan Devang; Matinlinna, Jukka P.; Vallittu, Pekka K.

    2016-01-01

    The current laboratory study is evaluating the effect of hydrofluoric acid etching duration on the surface characteristics of five silica-based glass ceramics. Changes in the pore pattern, crystal structure, roughness, and wettability were compared and evaluated. Seventy-five rectangularly shaped specimens were cut from each material (IPS e-max™, Dentsply Celtra™, Vita Suprinity™, Vita mark II™, and Vita Suprinity FC™); the sectioned samples were finished, polished, and ultrasonically cleaned. Specimens were randomly assigned into study groups: control (no etching) and four experimental groups (20, 40, 80 and 160 s of etching). The etched surfaces’ microstructure including crystal structure, pore pattern, pore depth, and pore width was studied under a scanning electron microscope, and the surface roughness and wettability were analyzed using a non-contact surface profilometer and a contact angle measuring device, respectively. The results were statistically analyzed using one-way analysis of variance (ANOVA) and the post hoc Tukey’s test. The results showed a significant change in the pore number, pore pattern, crystal structure, surface roughness, and wettability with increased etching duration. Etching for a short time resulted in small pores, and etching for longer times resulted in wider, irregular grooves. A significant increase in the surface roughness and wettability was observed with an increase in the etching duration. The findings also suggested a strong association between the surface roughness and wettability. PMID:27240353

  8. Effect of hydrofluoric acid etching duration on the roughness and flexural strength of a lithium disilicate-based glass ceramic.

    PubMed

    Zogheib, Lucas Villaça; Bona, Alvaro Della; Kimpara, Estevão Tomomitsu; McCabe, John F

    2011-01-01

    The aim of this study was to examine the effect of different acid etching times on the surface roughness and flexural strength of a lithium disilicate-based glass ceramic. Ceramic bar-shaped specimens (16 mm x 2 mm x 2 mm) were produced from ceramic blocks. All specimens were polished and sonically cleaned in distilled water. Specimens were randomly divided into 5 groups (n=15). Group A (control) no treatment. Groups B-E were etched with 4.9% hydrofluoric acid (HF) for 4 different etching periods: 20 s, 60 s, 90 s and 180 s, respectively. Etched surfaces were observed under scanning electron microscopy. Surface profilometry was used to examine the roughness of the etched ceramic surfaces, and the specimens were loaded to failure using a 3-point bending test to determine the flexural strength. Data were analyzed using one-way ANOVA and Tukey's test (?=0.05). All etching periods produced significantly rougher surfaces than the control group (p<0.05). Roughness values increased with the increase of the etching time. The mean flexural strength values were (MPa): A=417 ± 55; B=367 ± 68; C=363 ± 84; D=329 ± 70; and E=314 ± 62. HF etching significantly reduced the mean flexural strength as the etching time increased (p=0.003). In conclusion, the findings of this study showed that the increase of HF etching time affected the surface roughness and the flexural strength of a lithium disilicate-based glass ceramic, confirming the study hypothesis.

  9. Sulfuric acid-methanol electrolytes as an alternative to sulfuric-hydrofluoric acid mixtures for electropolishing of niobium

    SciTech Connect

    Zhao, Xin; Corcoran, Sean G.; Kelley, Michael J.

    2011-06-01

    Attainment of the greatest possible interior surface smoothness is critical to meeting the performance demands placed upon niobium superconducting radiofrequency (SRF) accelerator cavities by next generation projects. Electropolishing with HF-H{sub 2}SO{sub 4} electrolytes yields cavities that meet SRF performance goals, but a less-hazardous, more environmentally-friendly process is desirable. Reported studies of EP on chemically-similar tantalum describe the use of sulfuric acid-methanol electrolytes as an HF-free alternative. Reported here are the results of experiments on niobium samples with this electrolyte. Voltammetry experiments indicate a current plateau whose voltage range expands with increasing acid concentration and decreasing temperature. Impedance spectroscopy indicates that a compact salt film is responsible for the current plateau. Equivalent findings in electropolishing chemically-similar tantalum with this electrolyte were interpreted due to as mass transfer limitation by diffusion of Ta ions away from the anode surface. We infer that a similar mechanism is at work here. Conditions were found that yield leveling and brightening comparable to that obtained with HF-H{sub 2}SO{sub 4} mixtures.

  10. Mechanism of hydrofluoric acid formation in ethylene carbonate electrolytes with fluorine salt additives

    NASA Astrophysics Data System (ADS)

    Tebbe, Jonathon L.; Fuerst, Thomas F.; Musgrave, Charles B.

    2015-11-01

    We utilized density functional theory to examine HF generation in lithium-ion battery electrolytes from reactions between H2O and the decomposition products of three electrolyte additives: LiPF6, LiPOF4, and LiAsF6. Decomposition of these additives produces PF5, AsF5, and POF3 along with LiF precipitates. We found PF5 and AsF5 react with H2O in two sequential steps to form two HF molecules and POF3 and AsOF3, respectively. PF5 (or AsF5) complexes with H2O and undergoes ligand exchange to form HF and PF4OH (AsF4OH) with an activation barrier of 114.2 (30.5) kJ mol-1 and reaction enthalpy of 14.6 (-11.3) kJ mol-1. The ethylene carbonate (EC) electrolyte forms a Lewis acid-base complex with the PF4OH (AsF4OH) product, reducing the barrier to HF formation. Reactions of POF3 were examined and are not characterized by complexation of POF3 with H2O or EC, while PF5 and AsF5 complex favorably with H2O and EC. HF formation from POF3 occurs with a reaction enthalpy of -3.8 kJ mol-1 and a 157.7 kJ mol-1 barrier, 43.5 kJ mol-1 higher than forming HF from PF5. HF generation in electrolytes employing LiPOF4 should be significantly lower than those using LiPF6 or LiAsF6 and LiPOF4 should be further investigated as an alternative electrolyte additive.

  11. Micro-shear bond strength and surface micromorphology of a feldspathic ceramic treated with different cleaning methods after hydrofluoric acid etching

    PubMed Central

    STEINHAUSER, Henrique Caballero; TURSSI, Cecília Pedroso; FRANÇA, Fabiana Mantovani Gomes; do AMARAL, Flávia Lucisano Botelho; BASTING, Roberta Tarkany

    2014-01-01

    Objective The aim of this study was to evaluate the effect of feldspathic ceramic surface cleaning on micro-shear bond strength and ceramic surface morphology. Material and Methods Forty discs of feldspathic ceramic were prepared and etched with 10% hydrofluoric acid for 2 minutes. The discs were randomly distributed into five groups (n=8): C: no treatment, S: water spray + air drying for 1 minute, US: immersion in ultrasonic bath for 5 minutes, F: etching with 37% phosphoric acid for 1 minute, followed by 1-minute rinse, F+US: etching with 37% phosphoric acid for 1 minute, 1-minute rinse and ultrasonic bath for 5 minutes. Composite cylinders were bonded to the discs following application of silane and hydrophobic adhesive for micro-shear bond strength testing in a universal testing machine at 0.5 mm/min crosshead speed until failure. Stereomicroscopy was used to classify failure type. Surface micromorphology of each treatment type was evaluated by scanning electron microscopy at 500 and 2,500 times magnification. Results One-way ANOVA test showed no significant difference between treatments (p=0.3197) and the most common failure types were cohesive resin cohesion followed by adhesive failure. Micro-shear bond strength of the feldspathic ceramic substrate to the adhesive system was not influenced by the different surface cleaning techniques. Absence of or less residue was observed after etching with hydrofluoric acid for the groups US and F+US. Conclusions Combining ceramic cleaning techniques with hydrofluoric acid etching did not affect ceramic bond strength, whereas, when cleaning was associated with ultrasound, less residue was observed. PMID:24676577

  12. Effects of hydrofluoric acid and anodised micro and micro/nano surface implants on early osseointegration in rats.

    PubMed

    Li, Yongfeng; Gao, Yuan; Shao, Bo; Xiao, Jianrui; Hu, Kaijin; Kong, Liang

    2012-12-01

    Our aim was to evaluate the effects of hydrofluoric acid and anodised micro and micro/nano surface implants on bony ingrowth in the earliest stage of implantation in rats. Sixty cylindrical screwed titanium alloy implants with machined, micro, and hierarchical hybrid micro/nano surfaces (n=20 in each group) were inserted into the distal femurs of 30 female Sprague-Dawley rats. In vivo microcomputed tomography (micro CT) was used to assess microarchitectural changes in the bone around the implants 2 weeks after implantation. All the animals were then killed and the femurs with implants harvested for histological analysis and pull-out testing. Micro CT analysis showed that the trabecular thickness and the bone:volume ratio (bone volume:total volume) (BV:TV) increased significantly in the micro/nano group compared with the other two groups, while the trabecular separation decreased significantly in the micro/nano group compared with the machined group. The mean (SD) bone-implant contacts (%) were 38.94 (9.48), 41.67 (8.71), and 51.49 (12.49) in the machined, micro, and micro/nano groups, respectively. The maximum pull-out forces (N) were 64.95 (6.11), 71.45 (7.15), and 81.90 (13.1), respectively. Both bone-implant contacts and maximum pull-out forces were significantly higher in the micro/nano group, but there was no significant difference between the micro group and the machined group. These data indicate that the hierarchical hybrid micro/nano surface of the implant can promote osseointegration in the earliest stage of implantation, and may be a promising option for further clinical use.

  13. Using hydrofluoric acid for morphological investigations of Zoanthids (Cnidaria: Anthozoa): a critical assessment of methodology and necessity.

    PubMed

    Reimer, James Davis; Nakachi, Shu; Hirose, Mamiko; Hirose, Euichi; Hashiguchi, Shinji

    2010-10-01

    Zoanthids comprise an order of benthic, generally colonial cnidarians, which can usually be distinguished from other hexacorallians by embedded sand and detritus in their mesoglea to help strengthen their structure. These animals are becoming increasingly important research subjects in biochemistry and other research fields. Their inclusion of both calcium and silica results in the need for both decalcification and desilification for internal morphological examinations. Since the methodology of hydrofluoric acid (HF) desilification has rarely been documented in zoanthids, histological surveys for zoanthid taxonomy have often been abandoned and their taxonomy is often problematic. Recent investigations utilizing molecular methods have brought a clearer understanding of zoanthid diversity, but standardization of HF treatments are still needed to provide a link between molecular and more traditional techniques, and to properly examine specimens for which molecular methods may not be an option (e.g., formalin-preserved specimens, etc.). Here, we use both "straight" HF and, for the first time with zoanthids, buffered HF (BHF) treatments at different treatment lengths (1-48 h) on polyps from three different species of zoanthids for histological examination. Section conditions were judged based on the presence/absence of embedded detritus, drag marks, and tissue condition. Results show that the BHF treatment resulted in slightly better tissue conditions for all specimens, and suggest that desilification works well regardless of treatment time for species with smaller (polyp diameter <0.5 cm), less heavily encrusted polyps. Desilification of heavily encrusted Palythoa mutuki polyps were still problematic, with at least 24 h treatment needed. To aid future research, we provide guidelines for HF treatments of zoanthid specimens.

  14. HYDROFLUORIC ACID SCRUBBER SYSTEMS

    SciTech Connect

    PANESKO JV; MERRITT HD

    2011-05-18

    Each year over a million gallons of water are used to scrub hydrogen fluoride (HP) vapors from waste off-gas streams. Use of other potential scrubber solutions such as potassium hydroxide (KOH), aluminum nitrate nonahydrate (ANN), and monobasic aluminum nitrate (monoban) would result in significant volume reductions. A laboratory study was initiated to (1) demonstrate the effectiveness of these scrubber solutions to sorb HF, (2) determine if unexpected reactions occurred at flowsheet conditions, and (3) determine the consequences of deviation from flowsheet conditions. Caustic or aluminum scrubber solutions remove hydrogen fluoride from off-gas streams. Solids which appear with aluminum could be avoided by heating the scrubber solution.

  15. Part 2. Comparison of emergency washing solutions in 70% hydrofluoric acid-burned human skin in an established ex vivo explants model

    PubMed Central

    Burgher, François; Mathieu, Laurence; Lati, Elian; Gasser, Philippe; Peno-Mazzarino, Laurent; Blomet, Joël; Hall, Alan H; Maibach, Howard I

    2011-01-01

    Background: Hydrofluoric acid (HF) is a small and partially dissociated acid (pKa 3.2), able to deeply penetrate into human skin in addition to the corrosiveness of the hydrogen ion (H+) and the toxicity of the fluoride ion (F-). However, there has been a lack of experimental studies to objectively characterize the results of human HF skin exposure decontamination. Methodology/principal findings: A previously established experimental method using a human skin explants ex vivo model (Part 1. Experimental 70% hydrofluoric acid (HF) burns: Histological observations in an established human skin explants ex vivo model) described the lesions that appeared following 70% HF penetration. Within 5min, 70% HF penetrates to the dermis. Using the same experimental conditions, a comparison study of two different washing protocols was performed: water + topical calcium gluconate (CaG) versus Hexafluorine®. In these conditions, washing for 15min with running tap water followed by topical CaG ointment only delayed burn onset, while severe tissue damage appeared later. In contrast, after washing with Hexafluorine® over 10 min, no histological lesions developed. These results are in accordance with the results of accidental human industrial case reports. Conclusion/significance: Amphoteric and hypertonic Hexafluorine® can deactivate H+ and chelate F- ions. Based on these results, it should be considered as a promising first-aid decontamination solution to prevent or minimize significant local and systemic consequences of concentrated HF skin exposures. PMID:21083510

  16. Plasma-Enhanced Atomic Layer Deposition of SiN-AlN Composites for Ultra Low Wet Etch Rates in Hydrofluoric Acid.

    PubMed

    Kim, Yongmin; Provine, J; Walch, Stephen P; Park, Joonsuk; Phuthong, Witchukorn; Dadlani, Anup L; Kim, Hyo-Jin; Schindler, Peter; Kim, Kihyun; Prinz, Fritz B

    2016-07-13

    The continued scaling in transistors and memory elements has necessitated the development of atomic layer deposited (ALD) of hydrofluoric acid (HF) etch resistant and electrically insulating films for sidewall spacer processing. Silicon nitride (SiN) has been the prototypical material for this need and extensive work has been conducted into realizing sufficiently lower wet etch rates (WERs) as well as leakage currents to meet industry needs. In this work, we report on the development of plasma-enhanced atomic layer deposition (PEALD) composites of SiN and AlN to minimize WER and leakage current density. In particular, the role of aluminum and the optimum amount of Al contained in the composite structures have been explored. Films with near zero WER in dilute HF and leakage currents density similar to pure PEALD SiN films could be simultaneously realized through composites which incorporate ≥13 at. % Al, with a maximum thermal budget of 350 °C.

  17. Micro-PIXE and micro-RBS characterization of micropores in porous silicon prepared using microwave-assisted hydrofluoric acid etching.

    PubMed

    Ahmad, Muthanna; Grime, Geoffrey W

    2013-04-01

    Porous silicon (PS) has been prepared using a microwave-assisted hydrofluoric acid (HF) etching method from a silicon wafer pre-implanted with 5 MeV Cu ions. The use of microbeam proton-induced X-ray emission (micro-PIXE) and microbeam Rutherford backscattering techniques reveals for the first time the capability of these techniques for studying the formation of micropores. The porous structures observed from micro-PIXE imaging results are compared to scanning electron microscope images. It was observed that the implanted copper accumulates in the same location as the pores and that at high implanted dose the pores form large-scale patterns of lines and concentric circles. This is the first work demonstrating the use of microwave-assisted HF etching in the formation of PS.

  18. The effect of hydrofluoric acid treatment of titanium surface on nanostructural and chemical changes and the growth of MC3T3-E1 cells.

    PubMed

    Lamolle, Sébastien F; Monjo, Marta; Rubert, Marina; Haugen, Håvard J; Lyngstadaas, Ståle P; Ellingsen, Jan E

    2009-02-01

    Fluoride-modification of dental titanium (Ti) implants is used to improve peri-implant bone growth and bone-to-implant contact and adhesion strength. In this study, the surface topography, chemistry and biocompatibility of polished Ti surfaces treated with hydrofluoric acid solution (HF) were studied. Murine osteoblasts (MC3T3-E1) were cultured on the different groups of Ti surfaces. Surfaces treated with HF had higher roughness, lower cytotoxicity level and better biocompatibility than controls. For short treatment times (40 and 90 s), fluorine was detected only within the first 5 nm of the surface layer (X-ray Photoemission Spectroscopy, XPS), whereas longer treatment time (120 and 150 s) caused fluoride ions to penetrate deeper (Secondary Ion Mass Spectrometry, SIMS). These results suggest that submerging Ti implants in a weak HF solution instigate time-dependant specific surface changes that are linked to the improved biocompatibility of these surfaces.

  19. Plasma-Enhanced Atomic Layer Deposition of SiN-AlN Composites for Ultra Low Wet Etch Rates in Hydrofluoric Acid.

    PubMed

    Kim, Yongmin; Provine, J; Walch, Stephen P; Park, Joonsuk; Phuthong, Witchukorn; Dadlani, Anup L; Kim, Hyo-Jin; Schindler, Peter; Kim, Kihyun; Prinz, Fritz B

    2016-07-13

    The continued scaling in transistors and memory elements has necessitated the development of atomic layer deposited (ALD) of hydrofluoric acid (HF) etch resistant and electrically insulating films for sidewall spacer processing. Silicon nitride (SiN) has been the prototypical material for this need and extensive work has been conducted into realizing sufficiently lower wet etch rates (WERs) as well as leakage currents to meet industry needs. In this work, we report on the development of plasma-enhanced atomic layer deposition (PEALD) composites of SiN and AlN to minimize WER and leakage current density. In particular, the role of aluminum and the optimum amount of Al contained in the composite structures have been explored. Films with near zero WER in dilute HF and leakage currents density similar to pure PEALD SiN films could be simultaneously realized through composites which incorporate ≥13 at. % Al, with a maximum thermal budget of 350 °C. PMID:27295338

  20. Texturing a pyramid-like structure on a silicon surface via the synergetic effect of copper and Fe(III) in hydrofluoric acid solution

    NASA Astrophysics Data System (ADS)

    Cao, Ming; Li, Shaoyuan; Deng, Jianxin; Li, Yuping; Ma, Wenhui; Zhou, Yang

    2016-05-01

    An innovative approach is proposed to texture a pyramid structure on a silicon surface via Cu-catalyzed chemical etching in the HF/FeCl3 system. The surface and cross-section morphologies of the formed pyramid structure were examined by scanning electron microscopy and atomic force microscopy. The results revealed that numerous silicon pyramid-like structures with hemlines of 0.1 ∼ 3 μm and height of 0.1 ∼ 2 μm are close together, and the top angle of the pyramid structure is 90°. Additionally, the systematic study of the effects of the etching time and the concentration of FeCl3 on the pyramid-like structures by the atom configuration model of silicon crystal faces demonstrated that the etching proceeds preferentially along the <1 0 0> directions of silicon. A formation mechanism of the pyramid-like structure is proposed. The results imply that the synergetic effect of Cu nanoparticles and Fe(III) could conveniently generate a pyramid-like architecture on the surface of silicon in hydrofluoric acid solution.

  1. Molecular evaluation of soil organic matter characteristics in three agricultural soils by improved off-line thermochemolysis: the effect of hydrofluoric acid demineralisation treatment.

    PubMed

    Spaccini, Riccardo; Song, XiangYun; Cozzolino, Vincenza; Piccolo, Alessandro

    2013-11-13

    The molecular composition of soil organic matter (SOM) in three agricultural fields under different managements, was evaluated by off-line thermochemolysis followed by gas chromatography mass spectrometry analysis (THM-GC-MS). While this technique enabled the characterization of SOM components in coarse textured soil, its efficiency in heavy textured soils was seriously affected by the interference of clay minerals, which catalyzed the formation of secondary artifacts in pyrolysates. Soil demineralization with hydrofluoric acid (HF) solutions effectively improved the reliable characterization of organic compounds in clayey soils by thermochemolysis, while did not alter significantly the results of coarse textured soil. A wide range of lignin monomers and lipids molecules, of plant and microbial origin, were identified in the pyrograms of HF treated soils, thereby revealing interesting molecular differences between SOM management practices. Our results indicated that clay removal provided by HF pretreatment enhanced the capacity of thermochemolysis to be a valuable and accurate technique to study the SOM dynamics also in heavy-textured and OC-depleted cultivated soils.

  2. Trapping of hydrochloric and hydrofluoric acid at vacancies on and underneath the ice I(h) basal-plane surface.

    PubMed

    Pinheiro Moreira, Pedro Augusto Franco; de Koning, Maurice

    2013-10-31

    We investigate the uptake of HCl and HF at lattice vacancies in ice Ih as a function of their distance to the basal-plane surface layer using density-functional theory calculations. The results for HCl display large dispersions in the binding-energy results due to the appearance of distinct dissociation states. The layer-averaged results suggest that the uptake of HCl is most favorable in the two layers just below the surface, which is consistent with available experimental indications. The behavior of HF is found to be manifestly different due to the fact that it is a weaker acid. The dispersion in the binding-energy values is significantly less compared to the case of HCl, and the average values are essentially equal to the bulk value, regardless of layer position. This suggests that, in contrast to the case of HCl, there should not be any tendency for accumulation of HF near the surface.

  3. The Influence of Composition upon Surface Degradation and Stress Corrosion Cracking of the Ni-Cr-Mo Alloys in Wet Hydrofluoric Acid

    SciTech Connect

    Crook, P; Meck, N S; Rebak, R B

    2006-12-04

    At concentrations below 60%, wet hydrofluoric acid (HF) is extremely corrosive to steels, stainless steels and reactive metals, such as titanium, zirconium, and tantalum. In fact, only a few metallic materials will withstand wet HF at temperatures above ambient. Among these are the nickel-copper (Ni-Cu) and nickel-chromium-molybdenum (Ni-Cr-Mo) alloys. Previous work has shown that, even with these materials, there are complicating factors. For example, under certain conditions, internal attack and stress corrosion cracking (SCC) are possible with the Ni-Cr-Mo alloys, and the Ni-Cu materials can suffer intergranular attack when exposed to wet HF vapors. The purpose of this work was to study further the response of the Ni-Cr-Mo alloys to HF, in particular their external corrosion rates, susceptibility to internal attack and susceptibility to HF-induced SCC, as a function of alloy composition. As a side experiment, one of the alloys was tested in two microstructural conditions, i.e. solution annealed (the usual condition for materials of this type) and long-range ordered (this being a means of strengthening the alloy in question). The study of external corrosion rates over wide ranges of concentration and temperature revealed a strong beneficial influence of molybdenum content. However, tungsten, which is used as a partial replacement for molybdenum in some Ni-Cr-Mo alloys, appears to render the alloys more prone to internal attack. With regard to HF-induced SCC of the Ni-Cr-Mo alloys, this study suggests that only certain alloys (i.e., those containing tungsten) exhibit classical SCC. It was also discovered that high external corrosion rates inhibit HF-induced SCC, presumably due to rapid progression of the external attack front. With regard to the effects of long-range ordering, these were only evident at the highest test temperatures, where the ordered structure exhibited much higher external corrosion rates than the annealed structure.

  4. Interaction between a transition-metal fluoride and a transition-metal hydride: water-mediated hydrofluoric acid evolution following fluoride solvation.

    PubMed

    Chierotti, Michele R; Rossin, Andrea; Gobetto, Roberto; Peruzzini, Maurizio

    2013-11-01

    The reaction between the nickel(II) PCP pincer fluoride complex ((tBu)PCP)Ni(F) [(tBu)PCP = 2,6-C6H3(CH2P(t)Bu2)2] and the tungsten(II) carbonyl hydride CpW(H)(CO)3 (Cp = η(5)-C5H5(-)) leads to hydrofluoric acid evolution and formation of the bimetallic isocarbonylic species [CpW(CO)2(μ-κ,C:κ,O-CO)···Ni((tBu)PCP)]. The process has been monitored through multinuclear ((19)F, (31)P{(1)H}, (1)H) variable-temperature NMR spectroscopy, collecting (19)F T1 data values for a fluoride ligand bound to a transition metal. The extremely short relaxation time (minimum value of 13 ms at 193 K) is ascribed to the large chemical shift anisotropy of the Ni-F bond (688 ppm). The in-depth NMR analysis has revealed that the fluoride-hydride interaction is not direct but water-mediated, at odds with what was previously observed for the "hydride-hydride" case ((tBu)PCP)Ni(H)/CpW(H)(CO)3. Kinetic measurements have unveiled that the first step of the overall mechanism is thought to be solvation of the fluoride ligand (as a result of Ni-F···H2O hydrogen bonding), while further reaction of the solvated fluoride with CpW(H)(CO)3 is extremely slow and competes with the side reaction of fluoride replacement by a water molecule on the nickel center to form the [((tBu)PCP)Ni(H2O)](+) aquo species. Finally, density functional theory analysis of the solvation process through a discrete + continuum model has been accomplished, at the M06//6-31+G(d,p) level of theory, to support the mechanistic hypothesis.

  5. Characterization of Group V Dubnium Homologs on DGA Extraction Chromatography Resin from Nitric and Hydrofluoric Acid Matrices

    SciTech Connect

    Despotopulos, J D; Sudowe, R

    2012-02-21

    somewhere between Nb and Pa. Much more recent studies have examined the properties of Db from HNO{sub 3}/HF matrices, and suggest Db forms complexes similar to those of Pa. Very little experimental work into the behavior of element 114 has been performed. Thermochromatography experiments of three atoms of element 114 indicate that the element 114 is at least as volatile as Hg, At, and element 112. Lead was shown to deposit on gold at temperatures about 1000 C higher than the atoms of element 114. Results indicate a substantially increased stability of element 114. No liquid phase studies of element 114 or its homologs (Pb, Sn, Ge) or pseudo-homologs (Hg, Cd) have been performed. Theoretical predictions indicate that element 114 is should have a much more stable +2 oxidation state and neutral state than Pb, which would result in element 114 being less reactive and less metallic than Pb. The relativistic effects on the 7p{sub 1/2} electrons are predicted to cause a diagonal relationship to be introduced into the periodic table. Therefore, 114{sup 2+} is expected to behave as if it were somewhere between Hg{sup 2+}, Cd{sup 2+}, and Pb{sup 2+}. In this work two commercially available extraction chromatography resins are evaluated, one for the separation of Db homologs and pseudo?homologs from each other as well as from potential interfering elements such as Group IV Rf homologs and actinides, and the other for separation of element 114 homologs. One resin, Eichrom's DGA resin, contains a N,N,N',N'-tetra-n-octyldiglycolamide extractant, which separates analytes based on both size and charge characteristics of the solvated metal species, coated on an inert support. The DGA resin was examined for Db chemical systems, and shows a high degree of selectivity for tri-, tetra-, and hexavalent metal ions in multiple acid matrices with fast kinetics. The other resin, Eichrom's Pb resin, contains a di-t-butylcyclohexano 18-crown-6 extractant with isodecanol solvent, which separates

  6. Distribution of Components in Ion Exchange Materials Taken from the K East Basin and Leaching of Ion Exchange Materials by Nitric/Hydrofluoric Acid and Nitric/Oxalic Acid

    SciTech Connect

    Delegard, C.H.; Rinehart, D.E.; Hoopes, F.V.

    1999-04-02

    Laboratory tests were performed to examine the efficacy of mixed nitric/hydrofluoric acid followed by mixed nitric/oxalic acid leach treatments to decontaminate ion exchange materials that have been found in a number of samples retrieved from K East (KE)Basin sludge. The ion exchange materials contain organic ion exchange resins and zeolite inorganic ion exchange material. Based on process records, the ion exchange resins found in the K Basins is a mixed-bed, strong acid/strong base material marketed as Purolite NRW-037. The zeolite material is Zeolon-900, a granular material composed of the mineral mordenite. Radionuclides sorbed or associated with the ion exchange material can restrict its disposal to the Environmental Restoration Disposal Facility (ERDF). The need for testing to support development of a treatment process for K Basin sludge has been described in Section 4.2 of ''Testing Strategy to Support the Development of K Basins Sludge Treatment Process'' (Flament 1998). Elutriation and washing steps are designed to remove the organic resins from the K Basin sludge. To help understand the effects of the anticipated separation steps, tests were performed with well-rinsed ion exchange (IX) material from KE Basin floor sludge (sample H-08 BEAD G) and with well-rinsed IX having small quantities of added KE canister composite sludge (sample KECOMP). Tests also were performed to determine the relative quantities of organic and inorganic IX materials present in the H-08 K Basin sludge material. Based on chemical analyses of the separated fractions, the rinsed and dry IX material H-08 BEAD G was found to contain 36 weight percent inorganic material (primarily zeolite). The as-received (unrinsed) and dried H-08 material was estimated to contain 45 weight percent inorganic material.

  7. The Effect of Hydrofluoric Acid Concentration on the Bond Strength and Morphology of the Surface and Interface of Glass Ceramics to a Resin Cement.

    PubMed

    Sundfeld Neto, D; Naves, L Z; Costa, A R; Correr, A B; Consani, S; Borges, G A; Correr-Sobrinho, L

    2015-01-01

    The purpose of this study was to evaluate the influence of various concentrations of hydrofluoric acid (HF) on the surface/interface morphology and μ-shear bond strength (μSBS) between IPS Empress Esthetic (EST) (Ivoclar Vivadent) and IPS e.max Press (EMX) (Ivoclar Vivadent) ceramics and resin cement. Ceramic blocks were divided into 12 groups for each kind of ceramic. Six different HF concentrations were evaluated: 1%, 2.5%, 5%, 7.5%, 10%, and 15%. All groups were silanated after etching, and half of the specimens within each group received a thin layer of unfilled resin (UR). Three resin cement cylinders were prepared on each ceramic block for μSBS testing. The specimens were stored in distilled water at 37°C for 24 hours. The μSBS test was carried out in a universal testing machine at a crosshead speed of 0.5 mm/min until fracture. The data were submitted to three-way analysis of variance and multiple comparisons were performed using the Tukey post hoc test (p<0.05). The etched surfaces and bonded interfaces were evaluated using scanning electron microscopy. μSBS means (MPa) for 1%, 2.5%, 5%, 7.5%, 10%, and 15% HF concentrations were, respectively, 25.2, 27.2, 30.1, 31.4, 33.3, and 31.8. μSBS means with or without UR application measured 32.24 and 27.4, respectively; EST and EMX measured 29.8 and 29.9, respectively. For the HF concentrations, 10% and 15% showed higher μSBS means than did 1% and 2.5% (p<0.05); 7.5% was higher than 1% (p<0.05); and no statistical differences were found among the other concentrations (p>0.05). When evaluating UR, μSBS mean was significantly higher and better infiltration was observed on the etched surfaces. No statistical difference was found between the ceramics. The HF concentration and UR influenced the bond strength and surface/interface morphology.

  8. Redox buffered hydrofluoric acid etchant for the reduction of galvanic attack during release etching of MEMS devices having noble material films

    DOEpatents

    Hankins, Matthew G.

    2009-10-06

    Etchant solutions comprising a redox buffer can be used during the release etch step to reduce damage to the structural layers of a MEMS device that has noble material films. A preferred redox buffer comprises a soluble thiophosphoric acid, ester, or salt that maintains the electrochemical potential of the etchant solution at a level that prevents oxidation of the structural material. Therefore, the redox buffer preferentially oxidizes in place of the structural material. The sacrificial redox buffer thereby protects the exposed structural layers while permitting the dissolution of sacrificial oxide layers during the release etch.

  9. [Case of continuous trans-arterial calcium gluconate infusion using a direct arterial sphygmomanometry line that exhibited dramatic improvement of chemical burns on the fingers caused by hydrofluoric acid].

    PubMed

    Miyamoto, Kazuyuki; Shimizu, Makiko; Tanaka, Kotaro; Minemura, Atsuko; Tamatsukuri, Tatsuro; Miyake, Yasufumi; Aruga, Tohru

    2014-12-01

    Hydrofluoric acid (HFA) is commonly used and many injuries occur on the upper extremities following exposure to HFA. The use of calcium gluconate (CG) -containing gel or local injections of CG are widely used for the initial treatment of HFA exposure. However, severe pain continues in some cases despite the treatment. There was a report that trans-arterial CG infusion could improve HFA burns, however, such treatment is not an established clinical procedure. A 30-year-old male presented at our hospital with severe pain in his left thumb. He had been cleaning tiles with an HFA-containing detergent. We diagnosed him with a chemical burn due to HFA exposure. Local CG injections were tried several times, but his terrible pain continued. Therefore, a direct arterial sphygmomanometry line was inserted from the left radial artery, and continuous transarterial CG injection was performed. His terrible pain dramatically improved. Direct arterial sphygmomanometry systems are widely used in the critical care field to monitor the hemodynamics and ICU staffs are used to dealing with it. Moreover, continuous saline infusion prevents the tube obstruction. Continuous CG infusion from a direct arterial sphygmomanometry line is simple and safe way to administer CG in HFA burns.

  10. Vacuum-jacketed hydrofluoric acid solution calorimeter

    USGS Publications Warehouse

    Robie, R.A.

    1965-01-01

    A vacuum-jacketed metal calorimeter for determining heats of solution in aqueous HF was constructed. The reaction vessel was made of copper and was heavily gold plated. The calorimeter has a cooling constant of 0.6 cal-deg -1-min-1, approximately 1/4 that of the air-jacketed calorimeters most commonly used with HF. It reaches equilibrium within 10 min after turning off the heater current. Measurements of the heat of solution of reagent grade KCl(-100 mesh dried 2 h at 200??C) at a mole ratio of 1 KCl to 200 H2O gave ??H = 4198??11 cal at 25??C. ?? 1965 The American Institute of Physics.

  11. Square-wave anodic-stripping voltammetric determination of Cd, Pb, and Cu in a hydrofluoric acid solution of siliceous spicules of marine sponges (from the Ligurian Sea, Italy, and the Ross Sea, Antarctica).

    PubMed

    Truzzi, C; Annibaldi, A; Illuminati, S; Bassotti, E; Scarponi, G

    2008-09-01

    Square-wave anodic-stripping voltammetry (SWASV) was set up and optimized for simultaneous determination of cadmium, lead, and copper in siliceous spicules of marine sponges, directly in the hydrofluoric acid solution (approximately 0.55 mol L(-1) HF, pH approximately 1.9). A thin mercury-film electrode (TMFE) plated on to an HF-resistant epoxy-impregnated graphite rotating-disc support was used. The optimum experimental conditions, evaluated also in terms of the signal-to-noise ratio, were as follows: deposition potential -1100 mV vs. Ag/AgCl, KCl 3 mol L(-1), deposition time 3-10 min, electrode rotation 3000 rpm, SW scan from -1100 mV to +100 mV, SW pulse amplitude 25 mV, frequency 100 Hz, DeltaE(step) 8 mV, t(step) 100 ms, t(wait) 60 ms, t(delay) 2 ms, t(meas) 3 ms. Under these conditions the metal peak potentials were Cd -654 +/- 1 mV, Pb -458 +/- 1 mV, Cu -198 +/- 1 mV. The electrochemical behaviour was reversible for Pb, quasi-reversible for Cd, and kinetically controlled (possibly following chemical reaction) for Cu. The linearity of the response with concentration was verified up to approximately 4 microg L(-1) for Cd and Pb and approximately 20 microg L(-1) for Cu. The detection limits were 5.8 ng L(-1), 3.6 ng L(-1), and 4.3 ng L(-1) for Cd, Pb, and Cu, respectively, with t(d) = 5 min. The method was applied for determination of the metals in spicules of two specimens of marine sponges (Demosponges) from the Portofino natural reserve (Ligurian Sea, Italy, Petrosia ficiformis) and Terra Nova Bay (Ross Sea, Antarctica, Sphaerotylus antarcticus). The metal contents varied from tens of ng g(-1) to approximately 1 microg g(-1), depending on the metal considered and with significant differences between the two sponge species. PMID:18642105

  12. Comparison of Buffer Effect of Different Acids During Sandstone Acidizing

    NASA Astrophysics Data System (ADS)

    Umer Shafiq, Mian; Khaled Ben Mahmud, Hisham; Hamid, Mohamed Ali

    2015-04-01

    The most important concern of sandstone matrix acidizing is to increase the formation permeability by removing the silica particles. To accomplish this, the mud acid (HF: HCl) has been utilized successfully for many years to stimulate the sandstone formations, but still it has many complexities. This paper presents the results of laboratory investigations of different acid combinations (HF: HCl, HF: H3PO4 and HF: HCOOH). Hydrofluoric acid and fluoboric acid are used to dissolve clays and feldspar. Phosphoric and formic acids are added as a buffer to maintain the pH of the solution; also it allows the maximum penetration of acid into the core sample. Different tests have been performed on the core samples before and after the acidizing to do the comparative study on the buffer effect of these acids. The analysis consists of permeability, porosity, color change and pH value tests. There is more increase in permeability and porosity while less change in pH when phosphoric and formic acids were used compared to mud acid. From these results it has been found that the buffer effect of phosphoric acid and formic acid is better than hydrochloric acid.

  13. Folic Acid

    MedlinePlus

    Folic acid is a B vitamin. It helps the body make healthy new cells. Everyone needs folic acid. For women who may get pregnant, it is really important. Getting enough folic acid before and during pregnancy can prevent major birth ...

  14. Folic Acid

    MedlinePlus

    Folic acid is used to treat or prevent folic acid deficiency. It is a B-complex vitamin needed by ... Folic acid comes in tablets. It usually is taken once a day. Follow the directions on your prescription label ...

  15. Amino acids

    MedlinePlus

    ... amino acids are: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan , and valine. Nonessential amino acids "Nonessential" means that our bodies produce an amino ...

  16. Acid Rain.

    ERIC Educational Resources Information Center

    Openshaw, Peter

    1987-01-01

    Provides some background information on acid deposition. Includes a historical perspective, describes some effects of acid precipitation, and discusses acid rain in the United Kingdom. Contains several experiments that deal with the effects of acid rain on water quality and soil. (TW)

  17. Acid rain

    SciTech Connect

    Not Available

    1985-01-01

    This report has four parts: they discuss acid rain in relation to acid soils, agriculture, forests, and aquatic ecosystems. Among findings: modern sources of acid deposition from the atmosphere for all the acid soils in the world, nor even chiefly responsible for those of northern U.S. Agriculture has its problems, but acid precipitation is probably not one of them. More research is needed to determine to what extent acid precipitation is responsible for forest declines and for smaller detrimental effects on forest growth where no damage to the foliage is evident. Many lakes and streams are extremely sensitive to added acids.

  18. An Effective Acid Combination for Enhanced Properties and Corrosion Control of Acidizing Sandstone Formation

    NASA Astrophysics Data System (ADS)

    Umer Shafiq, Mian; Khaled Ben Mahmud, Hisham

    2016-03-01

    To fulfill the demand of the world energy, more technologies to enhance the recovery of oil production are being developed. Sandstone acidizing has been introduced and it acts as one of the important means to increase oil and gas production. Sandstone acidizing operation generally uses acids, which create or enlarge the flow channels of formation around the wellbore. In sandstone matrix acidizing, acids are injected into the formation at a pressure below the formation fracturing pressure, in which the injected acids react with mineral particles that may restrict the flow of hydrocarbons. Most common combination is Hydrofluoric Acid - Hydrochloric with concentration (3% HF - 12% HCl) known as mud acid. But there are some problems associated with the use of mud acid i.e., corrosion, precipitation. In this paper several new combinations of acids were experimentally screened to identify the most effective combination. The combinations used consist of fluoboric, phosphoric, formic and hydrofluoric acids. Cores were allowed to react with these combinations and results are compared with the mud acid. The parameters, which are analyzed, are Improved Permeability Ratio, strength and mineralogy. The analysis showed that the new acid combination has the potential to be used in sandstone acidizing.

  19. Aminocaproic Acid

    MedlinePlus

    Aminocaproic acid is used to control bleeding that occurs when blood clots are broken down too quickly. This type ... the baby is ready to be born). Aminocaproic acid is also used to control bleeding in the ...

  20. Ethacrynic Acid

    MedlinePlus

    Ethacrynic acid, a 'water pill,' is used to treat swelling and fluid retention caused by various medical problems. It ... Ethacrynic acid comes as a tablet to take by mouth. It is usually taken once or twice a day ...

  1. Aristolochic Acids

    MedlinePlus

    ... Sciences NIH-HHS www.niehs.nih.gov Aristolochic Acids Key Points Report on Carcinogens Status Known to be human carcinogens Aristolochia Clematitis Aristolochic Acids n Known human carcinogens n Found in certain ...

  2. Obeticholic Acid

    MedlinePlus

    Obeticholic acid is used alone or in combination with ursodiol (Actigall, Urso) to treat primary biliary cholangitis (PBC; a ... were not treated successfully with ursodiol alone. Obeticholic acid is in a class of medications called farnesoid ...

  3. Acid mucopolysaccharides

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/003368.htm Acid mucopolysaccharides To use the sharing features on this page, please enable JavaScript. Acid mucopolysaccharides is a test that measures the amount ...

  4. Incorporation of stratospheric acids into water ice

    NASA Technical Reports Server (NTRS)

    Elliott, Scott; Turco, Richard P.; Toon, Owen B.; Hamill, Patrick

    1990-01-01

    Hydrochloric and hydrofluoric acids are absorbed within the water ice lattice at mole fractions maximizing below 0.00001 and 0.0001 in a variety of solid impurity studies. The absorption mechanism may be substitutional or interstitial, leading in either case to a weak permeation of stratospheric ices by the acids at equilibrium. Impurities could also inhabit grain boundaries, and the acid content of atmospheric ice crystals will then depend on details of their surface and internal microstructures. Limited evidence indicates similar properties for the absorption of HNO3. Water ice lattices saturated with acid cannot be a significant local reservoir for HCl in the polar stratosphere.

  5. Fatty acids - trans fatty acids

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The data supporting a negative effect of dietary trans fatty acids on cardiovascular disease risk is consistent. The primary dietary sources of trans fatty acids include partially hydrogenated fat and rudiment fat. The adverse effect of trans fatty acids on plasma lipoprotein profiles is consisten...

  6. Ultra-Trace Detection of Fluoride Ion and Hydrofluoric Acid

    SciTech Connect

    Timothy M. Swager

    2005-03-17

    Describes general synthetic strategies developed under this grant to control interchain electronic communications within conjugated polymers (CPs). Novel chemical architectures built on iptycenes, metallorotaxanes, and canopied pyrroles restrict the dimensionality of electronic structures responsible for excition and charge transport. Structure-property relationships emerging from studies of selected systems are discussed, focusing on their implications for the sensitivity of these materials as sensors.

  7. Aspartic acid

    MedlinePlus

    ... Hormone production and release Normal nervous system function Plant sources of aspartic acid include: Legumes such as soybeans, garbanzo beans, and lentils Peanuts, almonds, walnuts, and flaxseeds Animal ...

  8. Usnic acid.

    PubMed

    Ingólfsdóttir, K

    2002-12-01

    Since its first isolation in 1844, usnic acid [2,6-diacetyl-7,9-dihydroxy-8,9b-dimethyl-1,3(2H,9bH)-dibenzo-furandione] has become the most extensively studied lichen metabolite and one of the few that is commercially available. Usnic acid is uniquely found in lichens, and is especially abundant in genera such as Alectoria, Cladonia, Usnea, Lecanora, Ramalina and Evernia. Many lichens and extracts containing usnic acid have been utilized for medicinal, perfumery, cosmetic as well as ecological applications. Usnic acid as a pure substance has been formulated in creams, toothpaste, mouthwash, deodorants and sunscreen products, in some cases as an active principle, in others as a preservative. In addition to antimicrobial activity against human and plant pathogens, usnic acid has been shown to exhibit antiviral, antiprotozoal, antiproliferative, anti-inflammatory and analgesic activity. Ecological effects, such as antigrowth, antiherbivore and anti-insect properties, have also been demonstrated. A difference in biological activity has in some cases been observed between the two enantiomeric forms of usnic acid. Recently health food supplements containing usnic acid have been promoted for use in weight reduction, with little scientific support. The emphasis of the current review is on the chemistry and biological activity of usnic acid and its derivatives in addition to rational and ecologically acceptable methods for provision of this natural compound on a large scale.

  9. Acid rain

    SciTech Connect

    Elsworth, S.

    1985-01-01

    This book was written in a concise and readable style for the lay public. It's purpose was to make the public aware of the damage caused by acid rain and to mobilize public opinion to favor the elimination of the causes of acid rain.

  10. Acid rain

    SciTech Connect

    White, J.C. )

    1988-01-01

    This book presents the proceedings of the third annual conference sponsored by the Acid Rain Information Clearinghouse (ARIC). Topics covered include: Legal aspects of the source-receptor relationship: an energy perspective; Scientific uncertainty, agency inaction, and the courts; and Acid rain: the emerging legal framework.

  11. How Acidic Is Carbonic Acid?

    PubMed

    Pines, Dina; Ditkovich, Julia; Mukra, Tzach; Miller, Yifat; Kiefer, Philip M; Daschakraborty, Snehasis; Hynes, James T; Pines, Ehud

    2016-03-10

    Carbonic, lactic, and pyruvic acids have been generated in aqueous solution by the transient protonation of their corresponding conjugate bases by a tailor-made photoacid, the 6-hydroxy-1-sulfonate pyrene sodium salt molecule. A particular goal is to establish the pK(a) of carbonic acid H2CO3. The on-contact proton transfer (PT) reaction rate from the optically excited photoacid to the carboxylic bases was derived, with unprecedented precision, from time-correlated single-photon-counting measurements of the fluorescence lifetime of the photoacid in the presence of the proton acceptors. The time-dependent diffusion-assisted PT rate was analyzed using the Szabo-Collins-Kimball equation with a radiation boundary condition. The on-contact PT rates were found to follow the acidity order of the carboxylic acids: the stronger was the acid, the slower was the PT reaction to its conjugate base. The pK(a) of carbonic acid was found to be 3.49 ± 0.05 using both the Marcus and Kiefer-Hynes free energy correlations. This establishes H2CO3 as being 0.37 pK(a) units stronger and about 1 pK(a) unit weaker, respectively, than the physiologically important lactic and pyruvic acids. The considerable acid strength of intact carbonic acid indicates that it is an important protonation agent under physiological conditions. PMID:26862781

  12. Acid rain

    SciTech Connect

    Sweet, W.

    1980-06-20

    Acid precipitation includes not only rain but also acidified snow, hail and frost, as well as sulfur and nitrogen dust. The principal source of acid precipitation is pollution emitted by power plants and smelters. Sulfur and nitrogen compounds contained in the emissions combine with moisture to form droplets with a high acid content - sometimes as acidic as vinegar. When sufficiently concentrated, these acids can kill fish and damage material structures. Under certain circumstances they may reduce crop and forest yields and cause or aggravate respiratory diseases in humans. During the summer, especially, pollutants tend to collect over the Great Lakes in high pressure systems. Since winds typically are westerly and rotate clockwise around high pressure systems, the pollutants gradually are dispersed throughout the eastern part of the continent.

  13. Asparagusic acid.

    PubMed

    Mitchell, Stephen C; Waring, Rosemary H

    2014-01-01

    Asparagusic acid (1,2-dithiolane-4-carboxylic acid) is a simple sulphur-containing 5-membered heterocyclic compound that appears unique to asparagus, though other dithiolane derivatives have been identified in non-food species. This molecule, apparently innocuous toxicologically to man, is the most probable culprit responsible for the curious excretion of odorous urine following asparagus ingestion. The presence of the two adjacent sulphur atoms leads to an enhanced chemical reactivity, endowing it with biological properties including the ability to substitute potentially for α-lipoic acid in α-keto-acid oxidation systems. This brief review collects the scattered data available in the literature concerning asparagusic acid and highlights its properties, intermediary metabolism and exploratory applications.

  14. Acid rain

    SciTech Connect

    Bess, F.D.

    1980-01-01

    The acid rain problem in the northeastern U.S. has been growing in severity and geographical areas affected. Acid rain has damaged, or will result in damage to visibility, physical structures and materials, aquatic life, timber, crops, and soils. The principal causes of acid rain in the northeastern U.S. are sulfur oxide and nitrogen oxide emissions from large power plants and smelters in the Ohio River Valley. Immediate corrective action and appropriate research are needed to reduce acid precipitation. Short-term programs that will define the rate of environmental deterioration, remaining environmental capacity to resist sudden deterioration, mechanisms of acid rain formation, and costs of various control options must be developed. (3 maps, 13 references, 1 table)

  15. Asparagusic acid.

    PubMed

    Mitchell, Stephen C; Waring, Rosemary H

    2014-01-01

    Asparagusic acid (1,2-dithiolane-4-carboxylic acid) is a simple sulphur-containing 5-membered heterocyclic compound that appears unique to asparagus, though other dithiolane derivatives have been identified in non-food species. This molecule, apparently innocuous toxicologically to man, is the most probable culprit responsible for the curious excretion of odorous urine following asparagus ingestion. The presence of the two adjacent sulphur atoms leads to an enhanced chemical reactivity, endowing it with biological properties including the ability to substitute potentially for α-lipoic acid in α-keto-acid oxidation systems. This brief review collects the scattered data available in the literature concerning asparagusic acid and highlights its properties, intermediary metabolism and exploratory applications. PMID:24099657

  16. Acid fog

    SciTech Connect

    Hileman, B.

    1983-03-01

    Fog in areas of southern California previously thought to be pollution-free has been shown to have a pH as low as 1.69. It has been found to be most acidic after smoggy days, suggesting that it forms on the aerosol associated with the previously exiting smog. Studies on Whiteface Mountain in the Adirondacks show that fog water is often 10 times as acidic as rainwater. As a result of their studies, California plans to spend $4 million on acid deposition research in the coming year. (JMT)

  17. Tranexamic Acid

    MedlinePlus

    ... is used to treat heavy bleeding during the menstrual cycle (monthly periods) in women. Tranexamic acid is in ... tablets for more than 5 days in a menstrual cycle or take more than 6 tablets in a ...

  18. Mefenamic Acid

    MedlinePlus

    ... as mefenamic acid may cause ulcers, bleeding, or holes in the stomach or intestine. These problems may ... like coffee grounds, blood in the stool, or black and tarry stools.Keep all appointments with your ...

  19. Acid Precipitation

    ERIC Educational Resources Information Center

    Likens, Gene E.

    1976-01-01

    Discusses the fact that the acidity of rain and snow falling on parts of the U.S. and Europe has been rising. The reasons are still not entirely clear and the consequences have yet to be well evaluated. (MLH)

  20. Acidic precipitation

    SciTech Connect

    Martin, H.C.

    1987-01-01

    At the International Symposium on Acidic Precipitation, over 400 papers were presented, and nearly 200 of them are included here. They provide an overview of the present state of the art of acid rain research. The Conference focused on atmospheric science (monitoring, source-receptor relationships), aquatic effects (marine eutrophication, lake acidification, impacts on plant and fish populations), and terrestrial effects (forest decline, soil acidification, etc.).

  1. Salicylic acids

    PubMed Central

    Hayat, Shamsul; Irfan, Mohd; Wani, Arif; Nasser, Alyemeni; Ahmad, Aqil

    2012-01-01

    Salicylic acid is well known phytohormone, emerging recently as a new paradigm of an array of manifestations of growth regulators. The area unleashed yet encompassed the applied agriculture sector to find the roles to strengthen the crops against plethora of abiotic and biotic stresses. The skipped part of integrated picture, however, was the evolutionary insight of salicylic acid to either allow or discard the microbial invasion depending upon various internal factors of two interactants under the prevailing external conditions. The metabolic status that allows the host invasion either as pathogenesis or symbiosis with possible intermediary stages in close systems has been tried to underpin here. PMID:22301975

  2. Stearic Acid

    ERIC Educational Resources Information Center

    Young, Jay A.

    2004-01-01

    A chemical laboratory information profile (CLIP) is presented for the chemical, stearic acid. The profile lists the chemical's physical and harmful characteristics, exposure limits, and symptoms of major exposure, for the benefit of teachers and students, who use the chemical in the laboratory.

  3. Trichloroacetic acid

    Integrated Risk Information System (IRIS)

    Trichloroacetic acid ( TCA ) ; CASRN 76 - 03 - 9 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Nonca

  4. Acrylic acid

    Integrated Risk Information System (IRIS)

    Acrylic acid ( CASRN 79 - 10 - 7 ) Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Eff

  5. Selenious acid

    Integrated Risk Information System (IRIS)

    Selenious acid ; CASRN 7783 - 00 - 8 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic E

  6. Dichloroacetic acid

    Integrated Risk Information System (IRIS)

    Dichloroacetic acid ; CASRN 79 - 43 - 6 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogeni

  7. Cacodylic acid

    Integrated Risk Information System (IRIS)

    Cacodylic acid ; CASRN 75 - 60 - 5 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Eff

  8. Phosphoric acid

    Integrated Risk Information System (IRIS)

    Phosphoric acid ; CASRN 7664 - 38 - 2 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic

  9. Benzoic acid

    Integrated Risk Information System (IRIS)

    Benzoic acid ; CASRN 65 - 85 - 0 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Effec

  10. Formic acid

    Integrated Risk Information System (IRIS)

    Formic acid ; CASRN 64 - 18 - 6 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Effect

  11. [Hyaluronic acid].

    PubMed

    Pomarede, N

    2008-01-01

    Hyaluronic Acid (HA) is now a leader product in esthetic procedures for the treatment of wrinkles and volumes. The structure of HA, its metabolism, its physiological function are foremost breaking down then its use in aesthetic dermatology: steps of injection, possible side effects, benefits and downsides of the use of HA in aesthetic dermatology.

  12. Hydroxycarboxylic acids and salts

    DOEpatents

    Kiely, Donald E; Hash, Kirk R; Kramer-Presta, Kylie; Smith, Tyler N

    2015-02-24

    Compositions which inhibit corrosion and alter the physical properties of concrete (admixtures) are prepared from salt mixtures of hydroxycarboxylic acids, carboxylic acids, and nitric acid. The salt mixtures are prepared by neutralizing acid product mixtures from the oxidation of polyols using nitric acid and oxygen as the oxidizing agents. Nitric acid is removed from the hydroxycarboxylic acids by evaporation and diffusion dialysis.

  13. Methylmalonic acid blood test

    MedlinePlus

    ... acid is a substance produced when proteins, called amino acids, in the body break down. The health care ... Cederbaum S, Berry GT. Inborn errors of carbohydrate, ammonia, amino acid, and organic acid metabolism. In: Gleason CA, Devaskar ...

  14. Folic Acid and Pregnancy

    MedlinePlus

    ... 5 Things to Know About Zika & Pregnancy Folic Acid and Pregnancy KidsHealth > For Parents > Folic Acid and ... before conception and during early pregnancy . About Folic Acid Folic acid, sometimes called folate, is a B ...

  15. Understanding Acid Rain

    ERIC Educational Resources Information Center

    Damonte, Kathleen

    2004-01-01

    The term acid rain describes rain, snow, or fog that is more acidic than normal precipitation. To understand what acid rain is, it is first necessary to know what an acid is. Acids can be defined as substances that produce hydrogen ions (H+), when dissolved in water. Scientists indicate how acidic a substance is by a set of numbers called the pH…

  16. Incinerator ash dissolution model for the system: Plutonium, nitric acid and hydrofluoric acid

    SciTech Connect

    Brown, E V

    1988-06-01

    This research accomplished two goals. The first was to develop a computer program to simulate a cascade dissolver system. This program would be used to predict the bulk rate of dissolution in incinerator ash. The other goal was to verify the model in a single-stage dissolver system using Dy/sub 2/O/sub 3/. PuO/sub 2/ (and all of the species in the incinerator ash) was assumed to exist as spherical particles. A model was used to calculate the bulk rate of plutonium oxide dissolution using fluoride as a catalyst. Once the bulk rate of PuO/sub 2/ dissolution and the dissolution rate of all soluble species were calculated, mass and energy balances were written. A computer program simulating the cascade dissolver system was then developed. Tests were conducted on a single-stage dissolver. A simulated incinerator ash mixture was made and added to the dissolver. CaF/sub 2/ was added to the mixture as a catalyst. A 9M HNO/sub 3/ solution was pumped into the dissolver system. Samples of the dissolver effluent were analyzed for dissolved and F concentrations. The computer program proved satisfactory in predicting the F concentrations in the dissolver effluent. The experimental sparge air flow rate was predicted to within 5.5%. The experimental percentage of solids dissolved (51.34%) compared favorably to the percentage of incinerator ash dissolved (47%) in previous work. No general conclusions on model verification could be reached. 56 refs., 11 figs., 24 tabs.

  17. Precipitation: its acidic nature.

    PubMed

    Frohliger, J O; Kane, R

    1975-08-01

    A comparison of the free hydrogen ion concentration and the total hydrogen ion concentration of rain samples shows that rain is a weak acid. The weak acid nature of rain casts doubt on the concepts that the acidity of rain is increasing and that these increases are due to strong acids such as sulfuric acid.

  18. Preliminary observations of lung injury produced by instillation of HF in acidic and neutral buffer

    SciTech Connect

    Brainard, J.R.; Kinkead, S.A.; Kober, E.M.; Sebring, R.J.; Stavert, D.M.; Lehnert, B.E.

    1990-01-01

    Perfluoroisobutylene (PFIB) is an extremely toxic organofluoride that can be produced during pyrolysis of tetrafluoroethylene polymers, including Teflon{reg sign}. Inhalation of PFIB at very low concentrations causes acute lung injury, the hallmark of which is pulmonary edema. Several lines of evidence have suggested that hydrolysis of PFIB and resulting production of hydrofluoric acid may be responsible for pulmonary damage. In order to investigate the potential involvement of hydrofluoric acid in producing lung injury and its relationship to the mechanism of fluorocarbon toxicity, we have compared the pulmonary injury produced by PFIB, by dissociated (H{sup +} and F{sup {minus}}), and by undissociated (HF) hydrofluoric acid in the deep lung. By delivering hydrofluoric acid by intratracheal instillation in neutral buffer, we demonstrate that F{sup {minus}} produces no significant pulmonary injury as assessed by increased in lung weight and ultrastructural changes. Similarly, instillation of acid buffer alone demonstrated that H{sup +} did not produce detectable lung injury. Instillation of HF produced changes in lung weight and ultrastructure similar to those observed in PFIB-treated rats. However, the ultrastructural studies show that in contrast to inhalation of PFIB, which produces both endothelial and epithelial cell damage, instillation of HF appears to exert its injurious effects only upon epithelial cells. 9 refs., 1 fig.

  19. Amino Acid Metabolism Disorders

    MedlinePlus

    ... defects & other health conditions > Amino acid metabolism disorders Amino acid metabolism disorders E-mail to a friend Please ... baby’s newborn screening may include testing for certain amino acid metabolism disorders. These are rare health conditions that ...

  20. Carbolic acid poisoning

    MedlinePlus

    Phenol poisoning; Phenylic acid poisoning; Hydroxybenzene poisoning; Phenic acid poisoning; Benzenol poisoning ... Below are symptoms of carbolic acid poisoning in different parts of the ... urine Decreased urine output No urine output EYES, EARS, ...

  1. Azelaic Acid Topical

    MedlinePlus

    Azelaic acid gel is used to clear the bumps, lesions, and swelling caused by rosacea (a skin disease that ... redness, flushing, and pimples on the face). Azelaic acid cream is used to treat acne. Azelaic acid ...

  2. Uric acid test (image)

    MedlinePlus

    Uric acid urine test is performed to check for the amount of uric acid in urine. Urine is collected over a 24 ... testing. The most common reason for measuring uric acid levels is in the diagnosis or treatment of ...

  3. Facts about Folic Acid

    MedlinePlus

    ... Information For... Media Policy Makers Facts About Folic Acid Language: English Español (Spanish) Recommend on Facebook Tweet ... of the baby's brain and spine. About folic acid Folic acid is a B vitamin. Our bodies ...

  4. Acid Lipase Disease

    MedlinePlus

    ... Awards Enhancing Diversity Find People About NINDS NINDS Acid Lipase Disease Information Page Synonym(s): Cholesterol Ester Storage ... Trials Related NINDS Publications and Information What is Acid Lipase Disease ? Acid lipase disease or deficiency occurs ...

  5. Acid distribution in phosphoric acid fuel cells

    SciTech Connect

    Okae, I.; Seya, A.; Umemoto, M.

    1996-12-31

    Electrolyte acid distribution among each component of a cell is determined by capillary force when the cell is not in operation, but the distribution under the current load conditions had not been clear so far. Since the loss of electrolyte acid during operation is inevitable, it is necessary to store enough amount of acid in every cell. But it must be under the level of which the acid disturbs the diffusion of reactive gases. Accordingly to know the actual acid distribution during operation in a cell is very important. In this report, we carried out experiments to clarify the distribution using small single cells.

  6. Polymorph-dependent titanium dioxide nanoparticle dissolution in acidic and alkali digestions

    EPA Science Inventory

    Multiple polymorphs (anatase, brookite and rutile) of titanium dioxide nanoparticles (TiO2-NPs) with variable structures were quantified in environmental matrices via microwave-based hydrofluoric (HF) and nitric (HNO3) mixed acid digestion and muffle furnace (MF)-based potassium ...

  7. A solvent extraction approach to recover acetic acid from mixed waste acids produced during semiconductor wafer process.

    PubMed

    Shin, Chang-Hoon; Kim, Ju-Yup; Kim, Jun-Young; Kim, Hyun-Sang; Lee, Hyang-Sook; Mohapatra, Debasish; Ahn, Jae-Woo; Ahn, Jong-Gwan; Bae, Wookeun

    2009-03-15

    Recovery of acetic acid (HAc) from the waste etching solution discharged from silicon wafer manufacturing process has been attempted by using solvent extraction process. For this purpose 2-ethylhexyl alcohol (EHA) was used as organic solvent. In the pre-treatment stage >99% silicon and hydrofluoric acid was removed from the solution by precipitation. The synthesized product, Na(2)SiF(6) having 98.2% purity was considered of commercial grade having good market value. The waste solution containing 279 g/L acetic acid, 513 g/L nitric acid, 0.9 g/L hydrofluoric acid and 0.030 g/L silicon was used for solvent extraction study. From the batch test results equilibrium conditions for HAc recovery were optimized and found to be 4 stages of extraction at an organic:aqueous (O:A) ratio of 3, 4 stages of scrubbing and 4 stages of stripping at an O:A ratio of 1. Deionized water (DW) was used as stripping agent to elute HAc from organic phase. In the whole batch process 96.3% acetic acid recovery was achieved. Continuous operations were successfully conducted for 100 h using a mixer-settler to examine the feasibility of the extraction system for its possible commercial application. Finally, a complete process flowsheet with material balance for the separation and recovery of HAc has been proposed.

  8. Acid tolerance in amphibians

    SciTech Connect

    Pierce, B.A.

    1985-04-01

    Studies of amphibian acid tolerance provide information about the potential effects of acid deposition on amphibian communities. Amphibians as a group appear to be relatively acid tolerant, with many species suffering increased mortality only below pH 4. However, amphibians exhibit much intraspecific variation in acid tolerance, and some species are sensitive to even low levels of acidity. Furthermore, nonlethal effects, including depression of growth rates and increases in developmental abnormalities, can occur at higher pH.

  9. Bioconversions of ferulic acid, an hydroxycinnamic acid.

    PubMed

    Mathew, Sindhu; Abraham, T Emilia

    2006-01-01

    Ferulic acid is the most abundant hydroxycinnamic acid in the plant world and is ester linked to arabinose, in various plant polysaccharides such as arabinoxylans and pectins. It is a precursor to vanillin, one of the most important aromatic flavor compound used in foods, beverages, pharmaceuticals, and perfumes. This article presents an overview of the various biocatalytic routes, focusing on the relevant biotransformations of ferulic acid using plant sources, microorganisms, and enzymes.

  10. Determination of the Efficiency of Mixed-Acid Digestions of Sediments

    SciTech Connect

    Huerta Vazquez, Alejandra I.; Gill, Gary A.

    2007-01-01

    Mixed-acid digestion is a method often used for the determination of elemental analysis of sediment samples. It is crucial that efficiency details associated with the digestion method be well understood on an element by element basis. Battelle’s Marine Sciences Laboratory Standard Operating Procedure for Sediment Mixed-Acid Digestions was modified to identify conditions which produce optimal recovery of elements. The parameters that were adjusted for testing were mass of sediment, mixed-acid volume, mixed-acid composition and digestion time. Digestion involves treatment of the sediment sample with mixed-acid mixtures at 135º C ± 10º in a Teflon® digestion bomb. Typical analytical methods include Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) and Inductively Coupled Plasma – Mass Spectrometry (ICP-MS). Initial experiments involved determining the optimal ratio of acid volume to mass of sediment. Experiments were designed to identify the point at which insufficient acid was used to effectively digest a given mass of sediment. When the mass of sediment was varied between 0.2 and 1.0 gram using a 4 mL aqua regia acid mixture (3 mL hydrochloric acid and 1 mL nitric acid), there was no effect on the recovery of the elements Al, Ba, Ca, Co, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Sr, Ti, V, and Zn. The next experiments focused on a time study to resolve the shortest digestive time for optimal elemental recovery. Two masses of sediment were investigated, 0.25 and 0.7 g, again utilizing aqua regia digestion (4 mL). Maximum recovery was reached after 4 hours of digestion; additional digestion time released no or only minimal amounts of elements from the sediments. The final set of experiments was designed to identify optimal conditions for the total digestion of sediment using a mixture of hydrochloric acid, nitric acid, hydrofluoric acid, hydrogen peroxide, and boric acid. These experiments were designed to determine the optimal volume of hydrofluoric acid

  11. Acid Thunder: Acid Rain and Ancient Mesoamerica

    ERIC Educational Resources Information Center

    Kahl, Jonathan D. W.; Berg, Craig A.

    2006-01-01

    Much of Mesoamerica's rich cultural heritage is slowly eroding because of acid rain. Just as water dissolves an Alka-Seltzer tablet, acid rain erodes the limestone surfaces of Mexican archaeological sites at a rate of about one-half millimeter per century (Bravo et al. 2003). A half-millimeter may not seem like much, but at this pace, a few…

  12. Quantity of acid in acid fog

    SciTech Connect

    Deal, W.J.

    1983-07-01

    This communication notes the actual magnitude of the acidity in acidic fog particles and suggests a possible line of inquiry into the health effects of such fog so that it can be determined whether a typical fog is detrimental or beneficial relative to dry air.

  13. Use of super acids to digest chrysotile and amosite asbestos in simple mixtures or matrices found in building materials compositions

    SciTech Connect

    Sugama, T.; Petrakis, L.; Webster, R.P.

    1999-12-21

    A composition for converting asbestos-containing material to environmentally benign components is provided. The composition comprises a fluoro acid decomposing agent which can be applied to either amosite-containing thermal insulation or chrysotile-containing fire-proof material or to any asbestos-containing material which includes of chrysotile and amosite asbestos. The fluoro acid decomposing agent includes FP{sub 0}(OH){sub 2}, hexafluorophosphoric acid, a mixture of hydrofluoric and phosphoric acid and a mixture of hexafluorophosphoric acid and phosphoric acid. A method for converting asbestos-containing material to environmentally benign components is also provided.

  14. Lactic acid test

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/003507.htm Lactic acid test To use the sharing features on this page, please enable JavaScript. Lactic acid is mainly produced in muscle cells and red ...

  15. Omega-6 Fatty Acids

    MedlinePlus

    ... types of fats. Some types are found in vegetable oils, including corn, evening primrose seed, safflower, and soybean ... from studying specific omega-6 fatty acids or plant oils containing omega-6 fatty acids. See the separate ...

  16. Fatty acid analogs

    DOEpatents

    Elmaleh, David R.; Livni, Eli

    1985-01-01

    In one aspect, a radioactively labeled analog of a fatty acid which is capable of being taken up by mammalian tissue and which exhibits an in vivo beta-oxidation rate below that with a corresponding radioactively labeled fatty acid.

  17. Deoxycholic Acid Injection

    MedlinePlus

    Deoxycholic acid injection is used to improve the appearance and profile of moderate to severe submental fat ('double chin'; fatty tissue located under the chin). Deoxycholic acid injection is in a class of medications called ...

  18. Aminocaproic Acid Injection

    MedlinePlus

    Aminocaproic acid injection is used to control bleeding that occurs when blood clots are broken down too quickly. This ... the baby is ready to be born). Aminocaproic acid injection is also used to control bleeding in ...

  19. Zoledronic Acid Injection

    MedlinePlus

    ... acid (Reclast) is used to prevent or treat osteoporosis (condition in which the bones become thin and ... Zoledronic acid (Reclast) is also used to treat osteoporosis in men, and to prevent or treat osteoporosis ...

  20. Uric Acid Test

    MedlinePlus

    ... limited. Home Visit Global Sites Search Help? Uric Acid Share this page: Was this page helpful? Also known as: Serum Urate; UA Formal name: Uric Acid Related tests: Synovial Fluid Analysis , Kidney Stone Analysis , ...

  1. Methylmalonic Acid Test

    MedlinePlus

    ... limited. Home Visit Global Sites Search Help? Methylmalonic Acid Share this page: Was this page helpful? Also known as: MMA Formal name: Methylmalonic Acid Related tests: Vitamin B12 and Folate , Homocysteine , Intrinsic ...

  2. Hydrochloric acid poisoning

    MedlinePlus

    Hydrochloric acid is a clear, poisonous liquid. It is highly corrosive, which means it immediately causes severe ... discusses poisoning due to swallowing or breathing in hydrochloric acid. This article is for information only. Do ...

  3. Mixed Acid Oxidation

    SciTech Connect

    Pierce, R.A.

    1999-10-26

    Several non-thermal processes have been developed to destroy organic waste compounds using chemicals with high oxidation potentials. These efforts have focused on developing technologies that work at low temperatures, relative to incineration, to overcome many of the regulatory issues associated with obtaining permits for waste incinerators. One such technique with great flexibility is mixed acid oxidation. Mixed acid oxidation, developed at the Savannah River Site, uses a mixture of an oxidant (nitric acid) and a carrier acid (phosphoric acid). The carrier acid acts as a non-volatile holding medium for the somewhat volatile oxidant. The combination of acids allows appreciable amounts of the concentrated oxidant to remain in the carrier acid well above the oxidant''s normal boiling point.

  4. Microscopic residues of bone from dissolving human remains in acids.

    PubMed

    Vermeij, Erwin; Zoon, Peter; van Wijk, Mayonne; Gerretsen, Reza

    2015-05-01

    Dissolving bodies is a current method of disposing of human remains and has been practiced throughout the years. During the last decade in the Netherlands, two cases have emerged in which human remains were treated with acid. In the first case, the remains of a cremated body were treated with hydrofluoric acid. In the second case, two complete bodies were dissolved in a mixture of hydrochloric and sulfuric acid. In both cases, a great variety of evidence was collected at the scene of crime, part of which was embedded in resin, polished, and investigated using SEM/EDX. Apart from macroscopic findings like residual bone and artificial teeth, in both cases, distinct microscopic residues of bone were found as follows: (partly) digested bone, thin-walled structures, and recrystallized calcium phosphate. Although some may believe it is possible to dissolve a body in acid completely, at least some of these microscopic residues will always be found.

  5. Microscopic residues of bone from dissolving human remains in acids.

    PubMed

    Vermeij, Erwin; Zoon, Peter; van Wijk, Mayonne; Gerretsen, Reza

    2015-05-01

    Dissolving bodies is a current method of disposing of human remains and has been practiced throughout the years. During the last decade in the Netherlands, two cases have emerged in which human remains were treated with acid. In the first case, the remains of a cremated body were treated with hydrofluoric acid. In the second case, two complete bodies were dissolved in a mixture of hydrochloric and sulfuric acid. In both cases, a great variety of evidence was collected at the scene of crime, part of which was embedded in resin, polished, and investigated using SEM/EDX. Apart from macroscopic findings like residual bone and artificial teeth, in both cases, distinct microscopic residues of bone were found as follows: (partly) digested bone, thin-walled structures, and recrystallized calcium phosphate. Although some may believe it is possible to dissolve a body in acid completely, at least some of these microscopic residues will always be found. PMID:25677640

  6. Plant fatty acid hydroxylases

    DOEpatents

    Somerville, Chris; Broun, Pierre; van de Loo, Frank

    2001-01-01

    This invention relates to plant fatty acyl hydroxylases. Methods to use conserved amino acid or nucleotide sequences to obtain plant fatty acyl hydroxylases are described. Also described is the use of cDNA clones encoding a plant hydroxylase to produce a family of hydroxylated fatty acids in transgenic plants. In addition, the use of genes encoding fatty acid hydroxylases or desaturases to alter the level of lipid fatty acid unsaturation in transgenic plants is described.

  7. PRODUCTION OF TRIFLUOROACETIC ACID

    DOEpatents

    Haworth, W.N.; Stacey, M.

    1949-07-19

    A method is given for the production of improved yields of trifluoroacetic acid. The compound is prepared by oxidizing m-aminobenzotrifluoride with an alkali metal or alkaline earth metal permanganate at a temperature in the range of 80 deg C to 100 deg C while dissolved ln a mixture of water with glacial acetic acid and/or trifluoroacetic acid. Preferably a mixture of water and trifluoroacetic acid ls used as the solvent.

  8. Quantity of acid in acid fog

    SciTech Connect

    Deal, W.J.

    1983-07-01

    The chemical composition of fog particles has become of considerable interest, because of both the possibility of interpreting atmospheric- chemistry processes in fog particles in terms of the principles of aqueous chemistry and the potential health effects of species present in fog particles. The acidity of fog particles has received wide attention. This communication noted the actual magnitude of the excess acidity in acidic fog particles and suggested a possible line of inquiry into the health effects of such fog so that it can be determined whether a typical fog is detrimental or beneficial relative to dry air. (DP)

  9. Acid Rain Study Guide.

    ERIC Educational Resources Information Center

    Hunger, Carolyn; And Others

    Acid rain is a complex, worldwide environmental problem. This study guide is intended to aid teachers of grades 4-12 to help their students understand what acid rain is, why it is a problem, and what possible solutions exist. The document contains specific sections on: (1) the various terms used in conjunction with acid rain (such as acid…

  10. The Acid Rain Reader.

    ERIC Educational Resources Information Center

    Stubbs, Harriett S.; And Others

    A topic which is often not sufficiently dealt with in elementary school textbooks is acid rain. This student text is designed to supplement classroom materials on the topic. Discussed are: (1) "Rain"; (2) "Water Cycle"; (3) "Fossil Fuels"; (4) "Air Pollution"; (5) "Superstacks"; (6) "Acid/Neutral/Bases"; (7) "pH Scale"; (8) "Acid Rain"; (9)…

  11. What Is Acid Rain?

    ERIC Educational Resources Information Center

    Likens, Gene E.

    2004-01-01

    Acid rain is the collective term for any type of acidified precipitation: rain, snow, sleet, and hail, as well as the presence of acidifying gases, particles, cloud water, and fog in the atmosphere. The increased acidity, primarily from sulfuric and nitric acids, is generated as a by-product of the combustion of fossil fuels such as coal and oil.…

  12. [alpha]-Oxocarboxylic Acids

    ERIC Educational Resources Information Center

    Kerber, Robert C.; Fernando, Marian S.

    2010-01-01

    Several [alpha]-oxocarboxylic acids play key roles in metabolism in plants and animals. However, there are inconsistencies between the structures as commonly portrayed and the reported acid ionization constants, which result because the acids are predominantly hydrated in aqueous solution; that is, the predominant form is RC(OH)[subscript 2]COOH…

  13. Nucleic acid detection compositions

    DOEpatents

    Prudent, James R.; Hall, Jeff G.; Lyamichev, Victor I.; Brow, Mary Ann; Dahlberg, James L.

    2008-08-05

    The present invention relates to means for the detection and characterization of nucleic acid sequences, as well as variations in nucleic acid sequences. The present invention also relates to methods for forming a nucleic acid cleavage structure on a target sequence and cleaving the nucleic acid cleavage structure in a site-specific manner. The structure-specific nuclease activity of a variety of enzymes is used to cleave the target-dependent cleavage structure, thereby indicating the presence of specific nucleic acid sequences or specific variations thereof.

  14. Cleavage of nucleic acids

    DOEpatents

    Prudent, James R.; Hall, Jeff G.; Lyamichev, Victor I.; Brow, Mary Ann D.; Dahlberg, James E.

    2000-01-01

    The present invention relates to means for the detection and characterization of nucleic acid sequences, as well as variations in nucleic acid sequences. The present invention also relates to methods for forming a nucleic acid cleavage structure on a target sequence and cleaving the nucleic acid cleavage structure in a site-specific manner. The structure-specific nuclease activity of a variety of enzymes is used to cleave the target-dependent cleavage structure, thereby indicating the presence of specific nucleic acid sequences or specific variations thereof.

  15. Nucleic acid detection assays

    DOEpatents

    Prudent, James R.; Hall, Jeff G.; Lyamichev, Victor I.; Brow, Mary Ann; Dahlberg, James E.

    2005-04-05

    The present invention relates to means for the detection and characterization of nucleic acid sequences, as well as variations in nucleic acid sequences. The present invention also relates to methods for forming a nucleic acid cleavage structure on a target sequence and cleaving the nucleic acid cleavage structure in a site-specific manner. The structure-specific nuclease activity of a variety of enzymes is used to cleave the target-dependent cleavage structure, thereby indicating the presence of specific nucleic acid sequences or specific variations thereof.

  16. Cleavage of nucleic acids

    DOEpatents

    Prudent, James R.; Hall, Jeff G.; Lyamichev, Victor L.; Brow, Mary Ann D.; Dahlberg, James E.

    2007-12-11

    The present invention relates to means for the detection and characterization of nucleic acid sequences, as well as variations in nucleic acid sequences. The present invention also relates to methods for forming a nucleic acid cleavage structure on a target sequence and cleaving the nucleic acid cleavage structure in a site-specific manner. The structure-specific nuclease activity of a variety of enzymes is used to cleave the target-dependent cleavage structure, thereby indicating the presence of specific nucleic acid sequences or specific variations thereof.

  17. Cleavage of nucleic acids

    SciTech Connect

    Prudent, James R.; Hall, Jeff G.; Lyamichev, Victor I.; Brow; Mary Ann D.; Dahlberg, James E.

    2010-11-09

    The present invention relates to means for the detection and characterization of nucleic acid sequences, as well as variations in nucleic acid sequences. The present invention also relates to methods for forming a nucleic acid cleavage structure on a target sequence and cleaving the nucleic acid cleavage structure in a site-specific manner. The structure-specific nuclease activity of a variety of enzymes is used to cleave the target-dependent cleavage structure, thereby indicating the presence of specific nucleic acid sequences or specific variations thereof.

  18. Editorial: Acid precipitation

    SciTech Connect

    1995-09-01

    This editorial focuses on acid rain and the history of public and governmental response to acid rain. Comments on a book by Gwineth Howell `Acid Rain and Acid Waters` are included. The editor feels that Howells has provide a service to the environmental scientific community, with a textbook useful to a range of people, as well as a call for decision makers to learn from the acid rain issue and use it as a model for more sweeping global environmental issues. A balance is needed among several parameters such as level of evidence, probability that the evidence will lead to a specific direction and the cost to the global community. 1 tab.

  19. [Safety of folic acid].

    PubMed

    Ströhle, Alexander; Wolters, Maike; Hahn, Andreas

    2015-08-01

    Improving dietary folate intake is a central public health goal. However, critical voices have become louder warning of too high intake of folic acid. Safety concerns of a high folic acid exposure are usually limited to synthetic folic acid contained in drugs and food supplements. Against this background, the present article focuses on two matters: (a) How do the absorption and metabolism of synthetic folic acid differ from that of other folates? (b) How has the longterm safety of folic acid to be judged, especially regarding the risk of colorectal cancer, autism, asthma, impaired immune defence, masking vitamin B12 deficiency and interactions with the methotrexate metabolism?

  20. Amino acid analysis

    NASA Technical Reports Server (NTRS)

    Winitz, M.; Graff, J. (Inventor)

    1974-01-01

    The process and apparatus for qualitative and quantitative analysis of the amino acid content of a biological sample are presented. The sample is deposited on a cation exchange resin and then is washed with suitable solvents. The amino acids and various cations and organic material with a basic function remain on the resin. The resin is eluted with an acid eluant, and the eluate containing the amino acids is transferred to a reaction vessel where the eluant is removed. Final analysis of the purified acylated amino acid esters is accomplished by gas-liquid chromatographic techniques.

  1. Acidic Ionic Liquids.

    PubMed

    Amarasekara, Ananda S

    2016-05-25

    Ionic liquid with acidic properties is an important branch in the wide ionic liquid field and the aim of this article is to cover all aspects of these acidic ionic liquids, especially focusing on the developments in the last four years. The structural diversity and synthesis of acidic ionic liquids are discussed in the introduction sections of this review. In addition, an unambiguous classification system for various types of acidic ionic liquids is presented in the introduction. The physical properties including acidity, thermo-physical properties, ionic conductivity, spectroscopy, and computational studies on acidic ionic liquids are covered in the next sections. The final section provides a comprehensive review on applications of acidic ionic liquids in a wide array of fields including catalysis, CO2 fixation, ionogel, electrolyte, fuel-cell, membrane, biomass processing, biodiesel synthesis, desulfurization of gasoline/diesel, metal processing, and metal electrodeposition.

  2. Nucleic acid detection kits

    DOEpatents

    Hall, Jeff G.; Lyamichev, Victor I.; Mast, Andrea L.; Brow, Mary Ann; Kwiatkowski, Robert W.; Vavra, Stephanie H.

    2005-03-29

    The present invention relates to means for the detection and characterization of nucleic acid sequences, as well as variations in nucleic acid sequences. The present invention also relates to methods for forming a nucleic acid cleavage structure on a target sequence and cleaving the nucleic acid cleavage structure in a site-specific manner. The structure-specific nuclease activity of a variety of enzymes is used to cleave the target-dependent cleavage structure, thereby indicating the presence of specific nucleic acid sequences or specific variations thereof. The present invention further relates to methods and devices for the separation of nucleic acid molecules based on charge. The present invention also provides methods for the detection of non-target cleavage products via the formation of a complete and activated protein binding region. The invention further provides sensitive and specific methods for the detection of nucleic acid from various viruses in a sample.

  3. Acidic Ionic Liquids.

    PubMed

    Amarasekara, Ananda S

    2016-05-25

    Ionic liquid with acidic properties is an important branch in the wide ionic liquid field and the aim of this article is to cover all aspects of these acidic ionic liquids, especially focusing on the developments in the last four years. The structural diversity and synthesis of acidic ionic liquids are discussed in the introduction sections of this review. In addition, an unambiguous classification system for various types of acidic ionic liquids is presented in the introduction. The physical properties including acidity, thermo-physical properties, ionic conductivity, spectroscopy, and computational studies on acidic ionic liquids are covered in the next sections. The final section provides a comprehensive review on applications of acidic ionic liquids in a wide array of fields including catalysis, CO2 fixation, ionogel, electrolyte, fuel-cell, membrane, biomass processing, biodiesel synthesis, desulfurization of gasoline/diesel, metal processing, and metal electrodeposition. PMID:27175515

  4. Boric acid and boronic acids inhibition of pigeonpea urease.

    PubMed

    Reddy, K Ravi Charan; Kayastha, Arvind M

    2006-08-01

    Urease from the seeds of pigeonpea was competitively inhibited by boric acid, butylboronic acid, phenylboronic acid, and 4-bromophenylboronic acid; 4-bromophenylboronic acid being the strongest inhibitor, followed by boric acid > butylboronic acid > phenylboronic acid, respectively. Urease inhibition by boric acid is maximal at acidic pH (5.0) and minimal at alkaline pH (10.0), i.e., the trigonal planar B(OH)3 form is a more effective inhibitor than the tetrahedral B(OH)4 -anionic form. Similarly, the anionic form of phenylboronic acid was least inhibiting in nature.

  5. Biotransformation of cinnamic acid, p-coumaric acid, caffeic acid, and ferulic acid by plant cell cultures of Eucalyptus perriniana.

    PubMed

    Katsuragi, Hisashi; Shimoda, Kei; Kubota, Naoji; Nakajima, Nobuyoshi; Hamada, Hatsuyuki; Hamada, Hiroki

    2010-01-01

    Biotransformations of phenylpropanoids such as cinnamic acid, p-coumaric acid, caffeic acid, and ferulic acid were investigated with plant-cultured cells of Eucalyptus perriniana. The plant-cultured cells of E. perriniana converted cinnamic acid into cinnamic acid β-D-glucopyranosyl ester, p-coumaric acid, and 4-O-β-D-glucopyranosylcoumaric acid. p-Coumaric acid was converted into 4-O-β-D-glucopyranosylcoumaric acid, p-coumaric acid β-D-glucopyranosyl ester, 4-O-β-D-glucopyranosylcoumaric acid β-D-glucopyranosyl ester, a new compound, caffeic acid, and 3-O-β-D-glucopyranosylcaffeic acid. On the other hand, incubation of caffeic acid with cultured E. perriniana cells gave 3-O-β-D-glucopyranosylcaffeic acid, 3-O-(6-O-β-D-glucopyranosyl)-β-D-glucopyranosylcaffeic acid, a new compound, 3-O-β-D-glucopyranosylcaffeic acid β-D-glucopyranosyl ester, 4-O-β-D-glucopyranosylcaffeic acid, 4-O-β-D-glucopyranosylcaffeic acid β-D-glucopyranosyl ester, ferulic acid, and 4-O-β-D-glucopyranosylferulic acid. 4-O-β-D-Glucopyranosylferulic acid, ferulic acid β-D-glucopyranosyl ester, and 4-O-β-D-glucopyranosylferulic acid β-D-glucopyranosyl ester were isolated from E. perriniana cells treated with ferulic acid.

  6. Process for the preparation of lactic acid and glyceric acid

    DOEpatents

    Jackson, James E [Haslett, MI; Miller, Dennis J [Okemos, MI; Marincean, Simona [Dewitt, MI

    2008-12-02

    Hexose and pentose monosaccharides are degraded to lactic acid and glyceric acid in an aqueous solution in the presence of an excess of a strongly anionic exchange resin, such as AMBERLITE IRN78 and AMBERLITE IRA400. The glyceric acid and lactic acid can be separated from the aqueous solution. Lactic acid and glyceric acid are staple articles of commerce.

  7. Well acidizing compositions and methods

    SciTech Connect

    Swanson, B. L.

    1980-12-23

    Gelled acidic compositions suitable for matrix acidizing or fracture acidizing of subterranean formations are provided comprising water, a water-dispersible polymeric viscosifier such as a polymer of acrylamide, an acid, and a polyphenolic material such as lignite.

  8. Bile acids but not acidic acids induce Barrett's esophagus.

    PubMed

    Sun, Dongfeng; Wang, Xiao; Gai, Zhibo; Song, Xiaoming; Jia, Xinyong; Tian, Hui

    2015-01-01

    Barrett's esophagus (BE) is associated with the development of esophageal adenocarcinoma (EAC). Bile acids (BAs) refluxing into the esophagus contribute to esophageal injury, which results in BE and subsequent EAC. We developed two animal models to test the role of BAs in the pathogenesis of BE. We surgically generated BA reflux, with or without gastric acid, in rats. In a second experiment, we fed animals separately with BAs and gastric acid. Pathologic changes were examined and the expression of Muc2 and Cdx2 in BE tissue was tested by immunostaining. Inflammatory factors in the plasma, as well as differentiation genes in BE were examined through highly sensitive ELISA and semi-quantitative RT-PCR techniques. We found that BAs are sufficient for the induction of esophagitis and Barrett's-like metaplasia in the esophagus. Overexpression of inflammatory cells, IL-6, and TNF-α was observed both in animals fed with BAs and surgically generated BA reflux. Furthermore, elevated levels of Cdx2, Muc2, Bmp4, Kit19, and Tff2 (differentiation genes in BE) were found in BA-treated rats. In conclusion, BAs, but not gastric acid, are a major causative factor for BE. We confirmed that BAs contribute to the development of BE by inducing the inflammatory response in the esophagus. Inhibiting BAs may be a promising therapy for BE.

  9. Microorganisms for producing organic acids

    DOEpatents

    Pfleger, Brian Frederick; Begemann, Matthew Brett

    2014-09-30

    Organic acid-producing microorganisms and methods of using same. The organic acid-producing microorganisms comprise modifications that reduce or ablate AcsA activity or AcsA homolog activity. The modifications increase tolerance of the microorganisms to such organic acids as 3-hydroxypropionic acid, acrylic acid, propionic acid, lactic acid, and others. Further modifications to the microorganisms increase production of such organic acids as 3-hydroxypropionic acid, lactate, and others. Methods of producing such organic acids as 3-hydroxypropionic acid, lactate, and others with the modified microorganisms are provided. Methods of using acsA or homologs thereof as counter-selectable markers are also provided.

  10. Acid-Base Homeostasis.

    PubMed

    Hamm, L Lee; Nakhoul, Nazih; Hering-Smith, Kathleen S

    2015-12-01

    Acid-base homeostasis and pH regulation are critical for both normal physiology and cell metabolism and function. The importance of this regulation is evidenced by a variety of physiologic derangements that occur when plasma pH is either high or low. The kidneys have the predominant role in regulating the systemic bicarbonate concentration and hence, the metabolic component of acid-base balance. This function of the kidneys has two components: reabsorption of virtually all of the filtered HCO3(-) and production of new bicarbonate to replace that consumed by normal or pathologic acids. This production or generation of new HCO3(-) is done by net acid excretion. Under normal conditions, approximately one-third to one-half of net acid excretion by the kidneys is in the form of titratable acid. The other one-half to two-thirds is the excretion of ammonium. The capacity to excrete ammonium under conditions of acid loads is quantitatively much greater than the capacity to increase titratable acid. Multiple, often redundant pathways and processes exist to regulate these renal functions. Derangements in acid-base homeostasis, however, are common in clinical medicine and can often be related to the systems involved in acid-base transport in the kidneys.

  11. Bone growth enhancement in vivo on press-fit titanium alloy implants with acid etched microtexture.

    PubMed

    Daugaard, Henrik; Elmengaard, Brian; Bechtold, Joan E; Soballe, Kjeld

    2008-11-01

    Early bone ongrowth secures long-term fixation of primary implants inserted without cement. Implant surfaces roughened with a texture on the micrometer scale are known to be osseoconductive. The aim of this study was to evaluate the bone formation at the surface of acid etched implants modified on the micro-scale. We compared implants with a nonparticulate texture made by chemical milling (hydrofluoric acid, nitric acid) (control) with implants that had a dual acid etched (hydrofluoric acid, hydrochloric acid) microtexture surface superimposed on the primary chemically milled texture. We used an experimental joint replacement model with cylindrical titanium implants (Ti-6Al-4V) inserted paired and press-fit in cancellous tibia metaphyseal bone of eight canines for 4 weeks and evaluated by histomorphometric quantification. A significant twofold median increase was seen for bone ongrowth on the acid etched surface [median, 36.1% (interquartile range, 24.3-44.6%)] compared to the control [18.4% (15.6-20.4%)]. The percentage of fibrous tissue at the implant surface and adjacent bone was significantly less for dual acid textured implants compared with control implants. These results show that secondary roughening of titanium alloy implant surface by dual acid etching increases bone formation at the implant bone interface. PMID:18186059

  12. Bone growth enhancement in vivo on press-fit titanium alloy implants with acid etched microtexture

    PubMed Central

    Daugaard, Henrik; Elmengaard, Brian; Bechtold, Joan E.; Soballe, Kjeld

    2013-01-01

    Early bone ongrowth secures long-term fixation of primary implants inserted without cement. Implant surfaces roughened with a texture on the micrometer scale are known to be osseoconductive. The aim of this study was to evaluate the bone formation at the surface of acid etched implants modified on the micro-scale. We compared implants with a nonparticulate texture made by chemical milling (hydrofluoric acid, nitric acid) (control) with implants that had a dual acid etched (hydrofluoric acid, hydrochloric acid) microtexture surface superimposed on the primary chemically milled texture. We used an experimental joint replacement model with cylindrical titanium implants (Ti-6Al-4V) inserted paired and press-fit in cancellous tibia metaphyseal bone of eight canines for 4 weeks and evaluated by histomorphometric quantification. A significant twofold median increase was seen for bone ongrowth on the acid etched surface [median, 36.1% (interquartile range, 24.3–44.6%)] compared to the control [18.4% (15.6–20.4%)]. The percentage of fibrous tissue at the implant surface and adjacent bone was significantly less for dual acid textured implants compared with control implants. These results show that secondary roughening of titanium alloy implant surface by dual acid etching increases bone formation at the implant bone interface. PMID:18186059

  13. Citric Acid Alternative to Nitric Acid Passivation

    NASA Technical Reports Server (NTRS)

    Lewis, Pattie L. (Compiler)

    2013-01-01

    The Ground Systems Development and Operations GSDO) Program at NASA John F. Kennedy Space Center (KSC) has the primary objective of modernizing and transforming the launch and range complex at KSC to benefit current and future NASA programs along with other emerging users. Described as the launch support and infrastructure modernization program in the NASA Authorization Act of 2010, the GSDO Program will develop and implement shared infrastructure and process improvements to provide more flexible, affordable, and responsive capabilities to a multi-user community. In support of the GSDO Program, the purpose of this project is to demonstratevalidate citric acid as a passivation agent for stainless steel. Successful completion of this project will result in citric acid being qualified for use as an environmentally preferable alternative to nitric acid for passivation of stainless steel alloys in NASA and DoD applications.

  14. Enzymatic gallic acid esterification.

    PubMed

    Weetal, H H

    1985-02-01

    Gallic acid esters of n-propyl and amyl alcohols have been produced by enzymatic synthesis in organic solvents using immobilized tannase. Studies indicate that maximum esterification of gallic acid occurs with amyl alcohol. The enzyme shows broad alcohol specificity. However, the enzyme exhibits absolute specificity for the acid portion of the ester. Studies were carried out on K(m), V(max), pH, and temperature optima.

  15. Amino acids and proteins.

    PubMed

    van Goudoever, Johannes B; Vlaardingerbroek, Hester; van den Akker, Chris H; de Groof, Femke; van der Schoor, Sophie R D

    2014-01-01

    Amino acids and protein are key factors for growth. The neonatal period requires the highest intake in life to meet the demands. Those demands include amino acids for growth, but proteins and amino acids also function as signalling molecules and function as neurotransmitters. Often the nutritional requirements are not met, resulting in a postnatal growth restriction. However, current knowledge on adequate levels of both amino acid as well as protein intake can avoid under nutrition in the direct postnatal phase, avoid the need for subsequent catch-up growth and improve later outcome.

  16. USGS Tracks Acid Rain

    USGS Publications Warehouse

    Gordon, John D.; Nilles, Mark A.; Schroder, LeRoy J.

    1995-01-01

    The U.S. Geological Survey (USGS) has been actively studying acid rain for the past 15 years. When scientists learned that acid rain could harm fish, fear of damage to our natural environment from acid rain concerned the American public. Research by USGS scientists and other groups began to show that the processes resulting in acid rain are very complex. Scientists were puzzled by the fact that in some cases it was difficult to demonstrate that the pollution from automobiles and factories was causing streams or lakes to become more acidic. Further experiments showed how the natural ability of many soils to neutralize acids would reduce the effects of acid rain in some locations--at least as long as the neutralizing ability lasted (Young, 1991). The USGS has played a key role in establishing and maintaining the only nationwide network of acid rain monitoring stations. This program is called the National Atmospheric Deposition Program/National Trends Network (NADP/NTN). Each week, at approximately 220 NADP/NTN sites across the country, rain and snow samples are collected for analysis. NADP/NTN site in Montana. The USGS supports about 72 of these sites. The information gained from monitoring the chemistry of our nation's rain and snow is important for testing the results of pollution control laws on acid rain.

  17. Recovery of organic acids

    DOEpatents

    Verser, Dan W.; Eggeman, Timothy J.

    2011-11-01

    A method is disclosed for the recovery of an organic acid from a dilute salt solution in which the cation of the salt forms an insoluble carbonate salt. A tertiary amine and CO.sub.2 are introduced to the solution to form the insoluble carbonate salt and a complex between the acid and an amine. A water immiscible solvent, such as an alcohol, is added to extract the acid/amine complex from the dilute salt solution to a reaction phase. The reaction phase is continuously dried and a product between the acid and the solvent, such as an ester, is formed.

  18. Recovery of organic acids

    DOEpatents

    Verser, Dan W.; Eggeman, Timothy J.

    2009-10-13

    A method is disclosed for the recovery of an organic acid from a dilute salt solution in which the cation of the salt forms an insoluble carbonate salt. A tertiary amine and CO.sub.2 are introduced to the solution to form the insoluble carbonate salt and a complex between the acid and an amine. A water immiscible solvent, such as an alcohol, is added to extract the acid/amine complex from the dilute salt solution to a reaction phase. The reaction phase is continuously dried and a product between the acid and the solvent, such as an ester, is formed.

  19. A review on methods of recovery of acid(s) from spent pickle liquor of steel industry.

    PubMed

    Ghare, N Y; Wani, K S; Patil, V S

    2013-04-01

    Pickling is the process of removal of oxide layer and rust formed on metal surface. It also removes sand and corrosion products from the surface of metal. Acids such as sulfuric acid, hydrochloric acid are used for pickling. Hydrofluoric acid-Nitric acid mixture is used for stainless steel pickling. Pickling solutions are spent when acid concentration in pickling solutions decreases by 75-85%, which also has metal content up to 150-250 g/ dm3. Spent pickling liquor (SPL) should be dumped because the efficiency of pickling decreases with increasing content of dissolved metal in the bath. The SPL content depends on the plant of origin and the pickling method applied there. SPL from steel pickling in hot-dip galvanizing plants contains zinc(II), iron, traces of lead, chromium. and other heavy metals (max. 500 mg/dm3) and hydrochloric acid. Zinc(II) passes tothe spent solution after dissolution of this metal from zinc(II)-covered racks, chains and baskets used for transportation of galvanized elements. Unevenly covered zinc layers are usually removed in another pickling bath. Due to this, zinc(II) concentration increases even up to 110 g/dm3, while iron content may reach or exceed even 80 g/dm3 in the same solution. This review presents an overview on different aspects of generation and treatment of SPL with recourse to recovery of acid for recycling. Different processes are described in this review and higher weightage is given to membrane processes.

  20. Mutant fatty acid desaturase

    DOEpatents

    Shanklin, John; Cahoon, Edgar B.

    2004-02-03

    The present invention relates to a method for producing mutants of a fatty acid desaturase having a substantially increased activity towards fatty acid substrates with chains containing fewer than 18 carbons relative to an unmutagenized precursor desaturase having an 18 carbon atom chain length substrate specificity. The method involves inducing one or more mutations in the nucleic acid sequence encoding the precursor desaturase, transforming the mutated sequence into an unsaturated fatty acid auxotroph cell such as MH13 E. coli, culturing the cells in the absence of supplemental unsaturated fatty acids, thereby selecting for recipient cells which have received and which express a mutant fatty acid desaturase with an elevated specificity for fatty acid substrates having chain lengths of less than 18 carbon atoms. A variety of mutants having 16 or fewer carbon atom chain length substrate specificities are produced by this method. Mutant desaturases produced by this method can be introduced via expression vectors into prokaryotic and eukaryotic cells and can also be used in the production of transgenic plants which may be used to produce specific fatty acid products.

  1. Amino Acid Crossword Puzzle

    ERIC Educational Resources Information Center

    Sims, Paul A.

    2011-01-01

    Learning the 20 standard amino acids is an essential component of an introductory course in biochemistry. Later in the course, the students study metabolism and learn about various catabolic and anabolic pathways involving amino acids. Learning new material or concepts often is easier if one can connect the new material to what one already knows;…

  2. Toxicology of Perfluoroalkyl acids

    EPA Science Inventory

    The Perfluoroalkyl acids(PFAAs) area a family of organic chemicals consisting of a perflurinated carbon backbone (4-12in length) and a acidic functional moiety (Carboxylate or sulfonate). These compounds have excellent surface-tension reducing properties and have numerous industr...

  3. Uric acid - blood

    MedlinePlus

    ... High levels of uric acid can sometimes cause gout or kidney disease. You may have this test if you have had or are about to have certain types of chemotherapy. Rapid weight loss, which may occur with such treatments, can increase the amount of uric acid in ...

  4. Bile acid transporters

    PubMed Central

    Dawson, Paul A.; Lan, Tian; Rao, Anuradha

    2009-01-01

    In liver and intestine, transporters play a critical role in maintaining the enterohepatic circulation and bile acid homeostasis. Over the past two decades, there has been significant progress toward identifying the individual membrane transporters and unraveling their complex regulation. In the liver, bile acids are efficiently transported across the sinusoidal membrane by the Na+ taurocholate cotransporting polypeptide with assistance by members of the organic anion transporting polypeptide family. The bile acids are then secreted in an ATP-dependent fashion across the canalicular membrane by the bile salt export pump. Following their movement with bile into the lumen of the small intestine, bile acids are almost quantitatively reclaimed in the ileum by the apical sodium-dependent bile acid transporter. The bile acids are shuttled across the enterocyte to the basolateral membrane and effluxed into the portal circulation by the recently indentified heteromeric organic solute transporter, OSTα-OSTβ. In addition to the hepatocyte and enterocyte, subgroups of these bile acid transporters are expressed by the biliary, renal, and colonic epithelium where they contribute to maintaining bile acid homeostasis and play important cytoprotective roles. This article will review our current understanding of the physiological role and regulation of these important carriers. PMID:19498215

  5. Analysis of Organic Acids.

    ERIC Educational Resources Information Center

    Griswold, John R.; Rauner, Richard A.

    1990-01-01

    Presented are the procedures and a discussion of the results for an experiment in which students select unknown carboxylic acids, determine their melting points, and investigate their solubility behavior in water and ethanol. A table of selected carboxylic acids is included. (CW)

  6. Omega-3 Fatty Acids

    MedlinePlus

    Omega-3 fatty acids are used together with lifestyle changes (diet, weight-loss, exercise) to reduce the amount of triglycerides (a fat-like ... people with very high triglycerides. Omega-3 fatty acids are in a class of medications called antilipemic ...

  7. Toxicology of Perfluoroalkyl Acids*

    EPA Science Inventory

    The perfluoroalkyl acids (PFAAs) are a family of organic chemicals consisting of a perfluorinated carbon backbone (4-12 in length) and an acidic functional moiety (carboxylate or sulfonate). These compounds are chemically stable, have excellent surface-tension reducing properties...

  8. Salicylic Acid Topical

    MedlinePlus

    ... skin blemishes in people who have acne. Topical salicylic acid is also used to treat skin conditions that involve scaling or overgrowth of skin ... water for 15 minutes.Do not apply topical salicylic acid to skin that is broken, red, swollen, irritated, or infected. ...

  9. Uric acid and hypertension.

    PubMed

    Feig, Daniel I

    2011-09-01

    A link between serum uric acid and the development of hypertension was first hypothesized in the 1870s. Although numerous epidemiologic studies in the 1980s and 1990s suggested an association, relatively little attention was paid to it until recently. Animal models have suggested a two-step pathogenesis by which uric acid initially activates the renin angiotensin system and suppresses nitric oxide, leading to uric acid-dependent increase in systemic vascular resistance, followed by a uric acid-mediated vasculopathy, involving renal afferent arterioles, resulting in a late sodium-sensitive hypertension. Initial clinical trials in young patients have supported these mechanisms in young patients but do not yet support pharmacologic reduction of serum uric acid as first-line therapy for hypertension.

  10. Biosynthesis of pulcherriminic acid

    PubMed Central

    MacDonald, J. C.

    1965-01-01

    1. Candida pulcherrima was grown on a complex medium to which various compounds had been added to determine their effect on the biosynthesis of pulcherriminic acid. Most of the pulcherriminic acid synthesized by C. pulcherrima PRL2019 was derived from the l-[1-14C]leucine added to the medium. 2. The cyclic dipeptide of l-leucine (cyclo-l-leucyl-l-leucyl) was shown, by trapping experiments involving cycloleucyl-leucyl isomers, to be synthesized by strain PRL2019. Cyclo-l-leucyl-l-leucyl was derived from l-leucine and was converted into pulcherriminic acid. Cyclo-l-leucyl-l-leucyl was a precursor of pulcherriminic acid in strain PRL2007 also. 3. The results supported the hypothesis that pulcherriminic acid is derived from l-leucine and that cyclo-l-leucyl-l-leucyl is an intermediate in the biosynthesis. PMID:5837792

  11. Total syntheses of cis-cyclopropane fatty acids: dihydromalvalic acid, dihydrosterculic acid, lactobacillic acid, and 9,10-methylenehexadecanoic acid.

    PubMed

    Shah, Sayali; White, Jonathan M; Williams, Spencer J

    2014-12-14

    cis-Cyclopropane fatty acids (cis-CFAs) are widespread constituents of the seed oils of subtropical plants, membrane components of bacteria and protozoa, and the fats and phospholipids of animals. We describe a systematic approach to the synthesis of enantiomeric pairs of four cis-CFAs: cis-9,10-methylenehexadecanoic acid, lactobacillic acid, dihydromalvalic acid, and dihydrosterculic acid. The approach commences with Rh2(OAc)4-catalyzed cyclopropenation of 1-octyne and 1-decyne, and hinges on the preparative scale chromatographic resolution of racemic 2-alkylcycloprop-2-ene-1-carboxylic acids using a homochiral Evan's auxiliary. Saturation of the individual diastereomeric N-cycloprop-2-ene-1-carbonylacyloxazolidines, followed by elaboration to alkylcyclopropylmethylsulfones, allowed Julia-Kocienski olefination with various ω-aldehyde-esters. Finally, saponification and diimide reduction afforded the individual cis-CFA enantiomers. PMID:25321346

  12. Gluconic acid production.

    PubMed

    Anastassiadis, Savas; Morgunov, Igor G

    2007-01-01

    Gluconic acid, the oxidation product of glucose, is a mild neither caustic nor corrosive, non toxic and readily biodegradable organic acid of great interest for many applications. As a multifunctional carbonic acid belonging to the bulk chemicals and due to its physiological and chemical characteristics, gluconic acid itself, its salts (e.g. alkali metal salts, in especially sodium gluconate) and the gluconolactone form have found extensively versatile uses in the chemical, pharmaceutical, food, construction and other industries. Present review article presents the comprehensive information of patent bibliography for the production of gluconic acid and compares the advantages and disadvantages of known processes. Numerous manufacturing processes are described in the international bibliography and patent literature of the last 100 years for the production of gluconic acid from glucose, including chemical and electrochemical catalysis, enzymatic biocatalysis by free or immobilized enzymes in specialized enzyme bioreactors as well as discontinuous and continuous fermentation processes using free growing or immobilized cells of various microorganisms, including bacteria, yeast-like fungi and fungi. Alternatively, new superior fermentation processes have been developed and extensively described for the continuous and discontinuous production of gluconic acid by isolated strains of yeast-like mold Aureobasidium pullulans, offering numerous advantages over the traditional discontinuous fungi processes.

  13. Trans Fatty Acids

    NASA Astrophysics Data System (ADS)

    Doyle, Ellin

    1997-09-01

    Fats and their various fatty acid components seem to be a perennial concern of nutritionists and persons concerned with healthful diets. Advice on the consumption of saturated, polyunsaturated, monounsaturated, and total fat bombards us from magazines and newspapers. One of the newer players in this field is the group of trans fatty acids found predominantly in partially hydrogenated fats such as margarines and cooking fats. The controversy concerning dietary trans fatty acids was recently addressed in an American Heart Association (AHA) science advisory (1) and in a position paper from the American Society of Clinical Nutrition/American Institute of Nutrition (ASCN/AIN) (2). Both reports emphasize that the best preventive strategy for reducing risk for cardiovascular disease and some types of cancer is a reduction in total and saturated fats in the diet, but a reduction in the intake of trans fatty acids was also recommended. Although the actual health effects of trans fatty acids remain uncertain, experimental evidence indicates that consumption of trans fatty acids adversely affects serum lipid levels. Since elevated levels of serum cholesterol and triacylglycerols are associated with increased risk of cardiovascular disease, it follows that intake of trans fatty acids should be minimized.

  14. Sulfuric Acid on Europa

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Frozen sulfuric acid on Jupiter's moon Europa is depicted in this image produced from data gathered by NASA's Galileo spacecraft. The brightest areas, where the yellow is most intense, represent regions of high frozen sulfuric acid concentration. Sulfuric acid is found in battery acid and in Earth's acid rain.

    This image is based on data gathered by Galileo's near infrared mapping spectrometer.

    Europa's leading hemisphere is toward the bottom right, and there are enhanced concentrations of sulfuric acid in the trailing side of Europa (the upper left side of the image). This is the face of Europa that is struck by sulfur ions coming from Jupiter's innermost moon, Io. The long, narrow features that crisscross Europa also show sulfuric acid that may be from sulfurous material extruded in cracks.

    Galileo, launched in 1989, has been orbiting Jupiter and its moons since December 1995. JPL manages the Galileo mission for NASA's Office of Space Science, Washington DC. JPL is a division of the California Institute of Technology, Pasadena, CA.

  15. Strongly Acidic Auxin Indole-3-Methanesulfonic Acid

    PubMed Central

    Cohen, Jerry D.; Baldi, Bruce G.; Bialek, Krystyna

    1985-01-01

    A radiochemical synthesis is described for [14C]indole-3-methanesulfonic acid (IMS), a strongly acidic auxin analog. Techniques were developed for fractionation and purification of IMS using normal and reverse phase chromatography. In addition, the utility of both Fourier transform infrared spectrometry and fast atom bombardment mass spectrometry for analysis of IMS has been demonstrated. IMS was shown to be an active auxin, stimulating soybean hypocotyl elongation, bean first internode curvature, and ethylene production. IMS uptake by thin sections of soybean hypocotyl was essentially independent of solution pH and, when applied at a 100 micromolar concentration, IMS exhibited a basipetal polarity in its transport in both corn coleoptile and soybean hypocotyl sections. [14C]IMS should, therefore, be a useful compound to study fundamental processes related to the movement of auxins in plant tissues and organelles. PMID:16664007

  16. Understanding acid rain

    SciTech Connect

    Budiansky, S.

    1981-06-01

    The complexities of the phenomenon of acid rain are described. Many factors, including meteorology, geology, chemistry, and biology, all play parts. Varying weather, varying soils, the presence of other pollutants and species differences all act to blur the connections between industrial emissions, acid rain, and environmental damage. Some experts believe that the greatest pH shock to lakes occurs during snow melt and runoff in the spring; others believe that much of the plant damage ascribed to acid rain is actually due to the effects of ozone. Much work needs to be done in the area of sampling. Historical data are lacking and sampling methods are not sufficiently accurate. (JMT)

  17. Understanding Acid Base Disorders.

    PubMed

    Gomez, Hernando; Kellum, John A

    2015-10-01

    The concentration of hydrogen ions is regulated in biologic solutions. There are currently 3 recognized approaches to assess changes in acid base status. First is the traditional Henderson-Hasselbalch approach, also called the physiologic approach, which uses the relationship between HCO3(-) and Pco2; the second is the standard base excess approach based on the Van Slyke equation. The third approach is the quantitative or Stewart approach, which uses the strong ion difference and the total weak acids. This article explores the origins of the current concepts framing the existing methods to analyze acid base balance.

  18. Acid rain and soil.

    PubMed

    vanLoon, G W

    1984-08-01

    A summary of important chemical properties of soil is given and the way in which acid rain may affect these properties is discussed. Acid rain may suppress microbiological decomposition and nitrification processes, thus influencing the nutrient status of soils. It has also been found that soil organic matter is less soluble in more acid solutions. Changed nutrient availability patterns are predicted in a low pH environment and enhanced leaching of essential elements from the soil exchange complex has been observed. Increased solubility of potentially toxic elements such as aluminium may also occur from soils which have been exposed to acidified rainfall.

  19. Optical measurement for the concentrations of the pickling acid with near infrared spectroscopy in steel making industry

    NASA Astrophysics Data System (ADS)

    Kang, Gumin; Lee, Kwangchil; Park, Haesung; Lee, Jinho; Jung, Youngjean; Kim, Kyoungsik

    2010-08-01

    In the manufacturing process of stainless steel, it is essential to pickle the oxide layer of steel surface for high corrosion resistance and fine surface quality. Pickling liquor of stainless steel is commonly composed of mixed hydrofluoric and nitric acid. Real time monitoring of concentrations of each acid is crucial to optimize pickling process. It also reduces cost of production and decreases the generation of waste acid. We used non-contact near infrared spectroscopy technique and rapid analysis method, for the quantification of each acid in an on-line manner. Multivariate calibration such as partial least square regression method is employed for the better prediction results.

  20. Epidermal lipids and the natural history of hydrofluoric acid (HF) injury.

    PubMed

    Noonan, T; Carter, E J; Edelman, P A; Zawacki, B E

    1994-06-01

    To explain several fortuitous observations, we hypothesized that there is a naturally occurring lipid 'barrier' to HF injury in guinea-pig skin and sought to characterize both the barrier and its role in the natural history of such injuries. Under anaesthesia, the dorsal trunk skin of groups of guinea-pigs was gently clipped of hair, washed with chloroform, soap and water, acetone or nothing (controls), and examined histologically for the presence of neutral lipid. Thereafter, in animal groups similarly washed, 1.5 in x 1.5 in (38 mm x 38 mm) areas were exposed to 40 per cent HF for up to 50 min and: (a) mean percentages of exposed areas with gross necrosis 5 days postinjury plotted on dose-response curves; or (b) less than 4 h after exposure to HF, intra-aortic India ink was injected and skin specimens examined to discern depth of ischaemia and necrosis. In contrast to controls, washing reduced neutral lipid in epidermis and significantly (at P < 0.001) increased susceptibility to injury by HF. With very rare (but interesting) exceptions, HF injury was found to be full thickness in depth with ischaemia and coagulative necrosis. In this study, development of guinea-pig skin necrosis due to HF was typically an 'all-or-nothing' 'barrier-penetration' phenomenon relating as much to the integrity of an epidermal lipid barrier as to the duration and intensity of noxious exposure.

  1. High-quality fiber fabrication in buffered hydrofluoric acid solution with ultrasonic agitation.

    PubMed

    Zhong, Nianbing; Liao, Qiang; Zhu, Xun; Wang, Yongzhong; Chen, Rong

    2013-03-01

    An etching method for preparing high-quality fiber-optic sensors using a buffered etchant with ultrasonic agitation is proposed. The effects of etching conditions on the etch rate and surface morphology of the etched fibers are investigated. The effect of surface roughness is discussed on the fibers' optical properties. Linear etching behavior and a smooth fiber surface can be repeatedly obtained by adjusting the ultrasonic power and etchant pH. The fibers' spectral quality is improved as the ratio of the pit depth to size decreases, and the fibers with smooth surfaces are more sensitive to a bacterial suspension than those with rough surfaces.

  2. Disorders of Amino Acid Metabolism

    MedlinePlus

    ... Aspiration Syndrome Additional Content Medical News Disorders of Amino Acid Metabolism By Lee M. Sanders, MD, MPH NOTE: ... Metabolic Disorders Disorders of Carbohydrate Metabolism Disorders of Amino Acid Metabolism Disorders of Lipid Metabolism Amino acids are ...

  3. Pantothenic acid and biotin

    MedlinePlus

    ... well as other nutrients, are provided in the Dietary Reference Intakes (DRIs) developed by the Food and Nutrition Board ... level that is thought to ensure enough nutrition. Dietary Reference Intakes for pantothenic acid: Age 0 to 6 months: ...

  4. Amino Acid Metabolism Disorders

    MedlinePlus

    Metabolism is the process your body uses to make energy from the food you eat. Food is ... One group of these disorders is amino acid metabolism disorders. They include phenylketonuria (PKU) and maple syrup ...

  5. Folic acid - test

    MedlinePlus

    ... folic acid before and during pregnancy helps prevent neural tube defects, such as spina bifida. Women who ... take more if they have a history of neural tube defects in earlier pregnancies. Ask your provider ...

  6. Nitric acid poisoning

    MedlinePlus

    Symptoms from swallowing nitric acid may include: Abdominal pain - severe Burns to skin or mouth Drooling Fever Mouth pain - severe Rapid drop in blood pressure (shock) Throat swelling, which leads to breathing difficulty ...

  7. Difficult Decisions: Acid Rain.

    ERIC Educational Resources Information Center

    Miller, John A.; Slesnick, Irwin L.

    1989-01-01

    Discusses some of the contributing factors and chemical reactions involved in the production of acid rain, its effects, and political issues pertaining to who should pay for the clean up. Supplies questions for consideration and discussion. (RT)

  8. Hyaluronic acid fillers.

    PubMed

    Monheit, Gary D; Coleman, Kyle M

    2006-01-01

    Although hyaluronic acids are a relatively new treatment for facial lines and wrinkles, they have provided numerous advances in the area of cosmetic surgery. This article discusses the inherent properties of hyaluronic acid fillers that make them ideal for treatment of facial lines. It encompasses a review of the current literature on U.S. Food and Drug Administration-approved hyaluronic acid fillers and the role that each of these fillers currently has in facial cosmetics. This article also discusses the potential pitfalls and adverse effects that can be associated with using hyaluronic acids for filling facial lines. Finally, it serves as an overview of current techniques for clinical assessment of patients as well as administration and treatment of facial lines and wrinkles.

  9. Boric acid poisoning

    MedlinePlus

    Borax poisoning ... The main symptoms of boric acid poisoning are blue-green vomit, diarrhea, and a bright red rash on the skin. Other symptoms may include: Blisters Collapse Coma Convulsions Drowsiness ...

  10. Stomach acid test

    MedlinePlus

    Gastric acid secretion test ... The test is done after you have not eaten for a while so fluid is all that remains in ... injected into your body. This is done to test the ability of the cells in the stomach ...

  11. Aminolevulinic Acid Topical

    MedlinePlus

    ... under the skin that result from exposure to sunlight and can develop into skin cancer) of the ... acid will make your skin very sensitive to sunlight (likely to get sunburn). Avoid exposure of treated ...

  12. Amino Acids and Chirality

    NASA Technical Reports Server (NTRS)

    Cook, Jamie E.

    2012-01-01

    Amino acids are among the most heavily studied organic compound class in carbonaceous chondrites. The abundance, distributions, enantiomeric compositions, and stable isotopic ratios of amino acids have been determined in carbonaceous chondrites fi'om a range of classes and petrographic types, with interesting correlations observed between these properties and the class and typc of the chondritcs. In particular, isomeric distributions appear to correlate with parent bodies (chondrite class). In addition, certain chiral amino acids are found in enantiomeric excess in some chondrites. The delivery of these enantiomeric excesses to the early Earth may have contributed to the origin of the homochirality that is central to life on Earth today. This talk will explore the amino acids in carbonaceous chondritcs and their relevance to the origin of life.

  13. (Acid rain workshop)

    SciTech Connect

    Turner, R.S.

    1990-12-05

    The traveler presented a paper entitled Susceptibility of Asian Ecosystems to Soil-Mediated Acid Rain Damage'' at the Second Workshop on Acid Rain in Asia. The workshop was organized by the Asian Institute of Technology (Bangkok, Thailand), Argonne National Laboratory (Argonne, Illinois), and Resource Management Associates (Madison, Wisconsin) and was sponsored by the US Department of Energy, the United Nations Environment Program, the United Nations Economic and Social Commission for Asia and the Pacific, and the World Bank. Papers presented on the first day discussed how the experience gained with acid rain in North America and Europe might be applied to the Asian situation. Papers describing energy use projections, sulfur emissions, and effects of acid rain in several Asian countries were presented on the second day. The remaining time was allotted to discussion, planning, and writing plans for a future research program.

  14. Folic acid in diet

    MedlinePlus

    ... a regular supply of the vitamin in the foods you eat. ... vitamins have been added to the food. Many foods are now fortified with folic acid. Some of these are enriched breads, cereals, flours, ...

  15. Valproic Acid and Pregnancy

    MedlinePlus

    ... in the treatment of epilepsy, and to treat bipolar disorder and migraines. I have been taking valproic acid ... that women with seizure disorders and women with bipolar disorder might have menstrual problems and difficulty getting pregnant. ...

  16. Citric acid urine test

    MedlinePlus

    ... The test is used to diagnose renal tubular acidosis and evaluate kidney stone disease. Normal Results The ... level of citric acid may mean renal tubular acidosis and a tendency to form calcium kidney stones. ...

  17. Folic Acid Quiz

    MedlinePlus

    ... more easily than natural food folate. Close × Answer: D CORRECT: Folic acid reduces the risk for spina ... g., orange juice and green vegetables). Close × Answer: D CORRECT: Spina bifida and anencephaly are neural tube ...

  18. Determination of the gram-positive bacterial content of soils and sediments by analysis of teichoic acid components

    NASA Technical Reports Server (NTRS)

    Gehron, M. J.; Davis, J. D.; Smith, G. A.; White, D. C.

    1984-01-01

    Many gram-positive bacteria form substituted polymers of glycerol and ribitol phosphate esters known as teichoic acids. Utilizing the relative specificity of cold concentrated hydrofluoric acid in the hydrolysis of polyphosphate esters it proved possible to quantitatively assay the teichoic acid-derived glycerol and ribitol from gram-positive bacteria added to various soils and sediments. The lipids are first removed from the soils or sediments with a one phase chloroform-methanol extraction and the lipid extracted residue is hydrolyzed with cold concentrated hydrofluoric acid. To achieve maximum recovery of the teichoic acid ribitol, a second acid hydrolysis of the aqueous extract is required. The glycerol and ribitol are then acetylated after neutralization and analyzed by capillary gas-liquid chromatography. This technique together with measures of the total phospholipid, the phospholipid fatty acid, the muramic acid and the hydroxy fatty acids of the lipopolysaccharide lipid A of the gram-negative bacteria makes it possible to describe the community structure environmental samples. The proportion of gram-positive bacteria measured as the teichoic acid glycerol and ribitol is higher in soils than in sediments and increases with depth in both.

  19. Portable nucleic acid thermocyclers.

    PubMed

    Almassian, David R; Cockrell, Lisa M; Nelson, William M

    2013-11-21

    A nucleic acid thermal cycler is considered to be portable if it is under ten pounds, easily carried by one individual, and battery powered. Nucleic acid amplification includes both polymerase chain reaction (e.g. PCR, RT-PCR) and isothermal amplification (e.g. RPA, HDA, LAMP, NASBA, RCA, ICAN, SMART, SDA). There are valuable applications for portable nucleic acid thermocyclers in fields that include clinical diagnostics, biothreat detection, and veterinary testing. A system that is portable allows for the distributed detection of targets at the point of care and a reduction of the time from sample to answer. The designer of a portable nucleic acid thermocycler must carefully consider both thermal control and the detection of amplification. In addition to thermal control and detection, the designer may consider the integration of a sample preparation subsystem with the nucleic acid thermocycler. There are a variety of technologies that can achieve accurate thermal control and the detection of nucleic acid amplification. Important evaluation criteria for each technology include maturity, power requirements, cost, sensitivity, speed, and manufacturability. Ultimately the needs of a particular market will lead to user requirements that drive the decision between available technologies.

  20. Neutron Nucleic Acid Crystallography.

    PubMed

    Chatake, Toshiyuki

    2016-01-01

    The hydration shells surrounding nucleic acids and hydrogen-bonding networks involving water molecules and nucleic acids are essential interactions for the structural stability and function of nucleic acids. Water molecules in the hydration shells influence various conformations of DNA and RNA by specific hydrogen-bonding networks, which often contribute to the chemical reactivity and molecular recognition of nucleic acids. However, X-ray crystallography could not provide a complete description of structural information with respect to hydrogen bonds. Indeed, X-ray crystallography is a powerful tool for determining the locations of water molecules, i.e., the location of the oxygen atom of H2O; however, it is very difficult to determine the orientation of the water molecules, i.e., the orientation of the two hydrogen atoms of H2O, because X-ray scattering from the hydrogen atom is very small.Neutron crystallography is a specialized tool for determining the positions of hydrogen atoms. Neutrons are not diffracted by electrons, but are diffracted by atomic nuclei; accordingly, neutron scattering lengths of hydrogen and its isotopes are comparable to those of non-hydrogen atoms. Therefore, neutron crystallography can determine both of the locations and orientations of water molecules. This chapter describes the current status of neutron nucleic acid crystallographic research as well as the basic principles of neutron diffraction experiments performed on nucleic acid crystals: materials, crystallization, diffraction experiments, and structure determination. PMID:26227050

  1. Neutron Nucleic Acid Crystallography.

    PubMed

    Chatake, Toshiyuki

    2016-01-01

    The hydration shells surrounding nucleic acids and hydrogen-bonding networks involving water molecules and nucleic acids are essential interactions for the structural stability and function of nucleic acids. Water molecules in the hydration shells influence various conformations of DNA and RNA by specific hydrogen-bonding networks, which often contribute to the chemical reactivity and molecular recognition of nucleic acids. However, X-ray crystallography could not provide a complete description of structural information with respect to hydrogen bonds. Indeed, X-ray crystallography is a powerful tool for determining the locations of water molecules, i.e., the location of the oxygen atom of H2O; however, it is very difficult to determine the orientation of the water molecules, i.e., the orientation of the two hydrogen atoms of H2O, because X-ray scattering from the hydrogen atom is very small.Neutron crystallography is a specialized tool for determining the positions of hydrogen atoms. Neutrons are not diffracted by electrons, but are diffracted by atomic nuclei; accordingly, neutron scattering lengths of hydrogen and its isotopes are comparable to those of non-hydrogen atoms. Therefore, neutron crystallography can determine both of the locations and orientations of water molecules. This chapter describes the current status of neutron nucleic acid crystallographic research as well as the basic principles of neutron diffraction experiments performed on nucleic acid crystals: materials, crystallization, diffraction experiments, and structure determination.

  2. Utilization of acid tars

    SciTech Connect

    Frolov, A.F.; Denisova, T.L.; Aminov, A.N.

    1987-01-01

    Freshly produced acid tar (FPAT), obtained as refinery waste in treating petroleum oils with sulfuric acid and oleum, contains 80% or more sulfuric acid. Of such tars, pond acid tars, which contain up to 80% neutral petroleum products and sulfonated resins, are more stable, and have found applications in the production of binders for paving materials. In this article the authors are presenting results obtained in a study of the composition and reactivity of FPAT and its stability in storage in blends with asphalts obtained in deasphalting operations, and the possibility of using the FPAT in road construction has been examined. In this work, wastes were used which were obtained in treating the oils T-750, KhF-12, I-8A, and MS-14. Data on the change in group chemical composition of FPAT are shown, and the acidity, viscosity, needle penetration, and softening point of acid tars obtained from different grades of oils are plotted as functions of the storage time. It is also shown that the fresh and hardened FPATs differ in their solubilities in various solvents.

  3. Method for isolating nucleic acids

    SciTech Connect

    Hurt, Jr., Richard Ashley; Elias, Dwayne A.

    2015-09-29

    The current disclosure provides methods and kits for isolating nucleic acid from an environmental sample. The current methods and compositions further provide methods for isolating nucleic acids by reducing adsorption of nucleic acids by charged ions and particles within an environmental sample. The methods of the current disclosure provide methods for isolating nucleic acids by releasing adsorbed nucleic acids from charged particles during the nucleic acid isolation process. The current disclosure facilitates the isolation of nucleic acids of sufficient quality and quantity to enable one of ordinary skill in the art to utilize or analyze the isolated nucleic acids for a wide variety of applications including, sequencing or species population analysis.

  4. Acidification and Acid Rain

    NASA Astrophysics Data System (ADS)

    Norton, S. A.; Veselã½, J.

    2003-12-01

    Air pollution by acids has been known as a problem for centuries (Ducros, 1845; Smith, 1872; Camuffo, 1992; Brimblecombe, 1992). Only in the mid-1900s did it become clear that it was a problem for more than just industrially developed areas, and that precipitation quality can affect aquatic resources ( Gorham, 1955). The last three decades of the twentieth century saw tremendous progress in the documentation of the chemistry of the atmosphere, precipitation, and the systems impacted by acid atmospheric deposition. Chronic acidification of ecosystems results in chemical changes to soil and to surface waters and groundwater as a result of reduction of base cation supply or an increase in acid (H+) supply, or both. The most fundamental changes during chronic acidification are an increase in exchangeable H+ or Al3+ (aluminum) in soils, an increase in H+ activity (˜concentration) in water in contact with soil, and a decrease in alkalinity in waters draining watersheds. Water draining from the soil is acidified and has a lower pH (=-log [H+]). As systems acidify, their biotic community changes.Acidic surface waters occur in many parts of the world as a consequence of natural processes and also due to atmospheric deposition of strong acid (e.g., Canada, Jeffries et al. (1986); the United Kingdom, Evans and Monteith (2001); Sweden, Swedish Environmental Protection Board (1986); Finland, Forsius et al. (1990); Norway, Henriksen et al. (1988a); and the United States (USA), Brakke et al. (1988)). Concern over acidification in the temperate regions of the northern hemisphere has been driven by the potential for accelerating natural acidification by pollution of the atmosphere with acidic or acidifying compounds. Atmospheric pollution ( Figure 1) has resulted in an increased flux of acid to and through ecosystems. Depending on the ability of an ecosystem to neutralize the increased flux of acidity, acidification may increase only imperceptibly or be accelerated at a rate that

  5. FURNACE INJECTION OF ALKALINE SORBENTS FOR SULFURIC ACID CONTROL

    SciTech Connect

    Gary M. Blythe

    2000-12-01

    This document summarizes progress on the Cooperative Agreement DE-FC26-99FT40718, Furnace Injection of Alkaline Sorbents for Sulfuric Acid Control, during the time period April 1, 2000 through September 30, 2000. The objective of this project is to demonstrate the use of alkaline reagents injected into the furnace of coal-fired boilers as a means of controlling sulfuric acid emissions. The coincident removal of hydrochloric acid and hydrofluoric acid will also be determined, as will the removal of arsenic, a known poison for NOX selective catalytic reduction (SCR) catalysts. EPRI, the Tennessee Valley Authority (TVA), First Energy Corporation, and the Dravo Lime Company are project co-funders. URS Corporation is the prime contractor. This is the second reporting period for the subject Cooperative Agreement. During this period, the first of four short-term sorbent injection tests were conducted at the First Energy Bruce Mansfield Plant. This test determined the effectiveness of dolomite injection through out-of-service burners as a means of controlling sulfuric acid emissions from this unit. The tests showed that dolomite injection could achieve up to 95% sulfuric acid removal. Balance of plant impacts on furnace slagging and fouling, air heater fouling, ash loss-on-ignition, and the flue gas desulfurization system were also determined. These results are presented and discussed in this report.

  6. Discovery of essential fatty acids

    PubMed Central

    Spector, Arthur A.; Kim, Hee-Yong

    2015-01-01

    Dietary fat was recognized as a good source of energy and fat-soluble vitamins by the first part of the 20th century, but fatty acids were not considered to be essential nutrients because they could be synthesized from dietary carbohydrate. This well-established view was challenged in 1929 by George and Mildred Burr who reported that dietary fatty acid was required to prevent a deficiency disease that occurred in rats fed a fat-free diet. They concluded that fatty acids were essential nutrients and showed that linoleic acid prevented the disease and is an essential fatty acid. The Burrs surmised that other unsaturated fatty acids were essential and subsequently demonstrated that linolenic acid, the omega-3 fatty acid analog of linoleic acid, is also an essential fatty acid. The discovery of essential fatty acids was a paradigm-changing finding, and it is now considered to be one of the landmark discoveries in lipid research. PMID:25339684

  7. Boric acid catalyzed chemoselective esterification of alpha-hydroxycarboxylic acids.

    PubMed

    Houston, Todd A; Wilkinson, Brendan L; Blanchfield, Joanne T

    2004-03-01

    Boric acid catalyzes the selective esterification of alpha-hydroxycarboxylic acids without causing significant esterification to occur with other carboxylic acids. The procedure is simple, high-yielding, and applicable to the esterification of alpha-hydroxy carboxylates in the presence of other carboxylic acids including beta-hydroxyacids within the same molecule. [reaction: see text

  8. Acid Rain, pH & Acidity: A Common Misinterpretation.

    ERIC Educational Resources Information Center

    Clark, David B.; Thompson, Ronald E.

    1989-01-01

    Illustrates the basis for misleading statements about the relationship between pH and acid content in acid rain. Explains why pH cannot be used as a measure of acidity for rain or any other solution. Suggests that teachers present acidity and pH as two separate and distinct concepts. (RT)

  9. Amino-acid contamination of aqueous hydrochloric acid.

    NASA Technical Reports Server (NTRS)

    Wolman, Y.; Miller, S. L.

    1971-01-01

    Considerable amino-acid contamination in commercially available analytical grade hydrochloric acid (37% HCl) was found. One bottle contained 8,300 nmol of amino-acids per liter. A bottle from another supplier contained 6,700 nmol per liter. The contaminants were mostly protein amino-acids and several unknowns. Data on the volatility of the amino-acids during HCl distillation were also obtained.

  10. Analysis of Bile Acids

    NASA Astrophysics Data System (ADS)

    Sjövall, Jan; Griffiths, William J.; Setchell, Kenneth D. R.; Mano, Nariyasu; Goto, Junichi

    Bile acids constitute a large family of steroids in vertebrates, normally formed from cholesterol and carrying a carboxyl group in a side-chain of variable length. Bile alcohols, also formed from cholesterol, have similar structures as bile acids, except for the absence of a carboxyl group in the steroid skeleton. The conversion of cholesterol to bile acids and/or bile alcohols is of major importance for maintenance of cholesterol homeostasis, both from quantitative and regulatory points of view (Chiang, 2004; Kalaany and Mangelsdorf, 2006; Moore, Kato, Xie, et al., 2006; Scotti, Gilardi, Godio, et al., 2007). Appropriately conjugated bile acids and bile alcohols (also referred to as bile salts) are secreted in bile and serve vital functions in the absorption of lipids and lipid-soluble compounds (Hofmann, 2007). Reliable analytical methods are required for studies of the functions and pathophysiological importance of the variety of bile acids and bile alcohols present in living organisms. When combined with genetic and proteomic studies, analysis of these small molecules (in today's terminology: metabolomics, steroidomics, sterolomics, cholanoidomics, etc.) will lead to a deeper understanding of the integrated metabolic processes in lipid metabolism.

  11. Optical high acidity sensor

    DOEpatents

    Jorgensen, B.S.; Nekimken, H.L.; Carey, W.P.; O`Rourke, P.E.

    1997-07-22

    An apparatus and method for determining acid concentrations in solutions having acid concentrations of from about 0.1 Molar to about 16 Molar is disclosed. The apparatus includes a chamber for interrogation of the sample solution, a fiber optic light source for passing light transversely through the chamber, a fiber optic collector for receiving the collimated light after transmission through the chamber, a coating of an acid resistant polymeric composition upon at least one fiber end or lens, the polymeric composition in contact with the sample solution within the chamber and having a detectable response to acid concentrations within the range of from about 0.1 Molar to about 16 Molar, a measurer for the response of the polymeric composition in contact with the sample solution, and a comparer of the measured response to predetermined standards whereby the acid molarity of the sample solution within the chamber can be determined. Preferably, a first lens is attached to the end of the fiber optic light source, the first lens adapted to collimate light from the fiber optic light source, and a second lens is attached to the end of the fiber optic collector for focusing the collimated light after transmission through the chamber. 10 figs.

  12. Optical high acidity sensor

    DOEpatents

    Jorgensen, Betty S.; Nekimken, Howard L.; Carey, W. Patrick; O'Rourke, Patrick E.

    1997-01-01

    An apparatus and method for determining acid concentrations in solutions having acid concentrations of from about 0.1 Molar to about 16 Molar is disclosed. The apparatus includes a chamber for interrogation of the sample solution, a fiber optic light source for passing light transversely through the chamber, a fiber optic collector for receiving the collimated light after transmission through the chamber, a coating of an acid resistant polymeric composition upon at least one fiber end or lens, the polymeric composition in contact with the sample solution within the chamber and having a detectable response to acid concentrations within the range of from about 0.1 Molar to about 16 Molar, a measurer for the response of the polymeric composition in contact with the sample solution, and, a comparer of the measured response to predetermined standards whereby the acid molarity of the sample solution within the chamber can be determined. Preferably, a first lens is attached to the end of the fiber optic light source, the first lens adapted to collimate light from the fiber optic light source, and a second lens is attached to the end of the fiber optic collector for focusing the collimated light after transmission through the chamber.

  13. Acid sludge utilization

    SciTech Connect

    Suarez, M.

    1980-09-01

    The Peak Oil Company of Tampa, Florida, in cooperation with the United States Department of Energy, has completed an initial study for the incorporation of acid-sludge derived from the rerefining of used lubricating oil into a useful and salable building material. Both bricks and paving materials have been produced using a formulation developed by Peak. Equipment has been designed and constructed for the specific purpose of preparing emulsions containing the acid-sludge, which is a vital ingredient in the final formulation. Testing of products obtained from these initial efforts shows that the acid in the sludge has been effectively neutralized and that heavy metals are not leached from the bricks or paving material in normal testing. While some properties of the building materials that incorporate the acid-sludge by-product are below standards for clay and shale brick, uses are defined for the product as is, and there is some promise of eventual production of building materials that meet all specifications for competitive materials. Initial cost estimations are encouraging, indicating that a profit can be derived by converting a hazardous and noxious by-product of rerefining to a construction material. Acid-sludge has presented a complex and costly disposal problem to the industry resulting in a serious depletion in the capacity for rerefining used lubricating oil.

  14. Domoic acid epileptic disease.

    PubMed

    Ramsdell, John S; Gulland, Frances M

    2014-03-01

    Domoic acid epileptic disease is characterized by spontaneous recurrent seizures weeks to months after domoic acid exposure. The potential for this disease was first recognized in a human case study of temporal lobe epilepsy after the 1987 amnesic shellfish-poisoning event in Quebec, and was characterized as a chronic epileptic syndrome in California sea lions through investigation of a series of domoic acid poisoning cases between 1998 and 2006. The sea lion study provided a breadth of insight into clinical presentations, unusual behaviors, brain pathology, and epidemiology. A rat model that replicates key observations of the chronic epileptic syndrome in sea lions has been applied to identify the progression of the epileptic disease state, its relationship to behavioral manifestations, and to define the neural systems involved in these behavioral disorders. Here, we present the concept of domoic acid epileptic disease as a delayed manifestation of domoic acid poisoning and review the state of knowledge for this disease state in affected humans and sea lions. We discuss causative mechanisms and neural underpinnings of disease maturation revealed by the rat model to present the concept for olfactory origin of an epileptic disease; triggered in dendodendritic synapases of the olfactory bulb and maturing in the olfactory cortex. We conclude with updated information on populations at risk, medical diagnosis, treatment, and prognosis. PMID:24663110

  15. Domoic Acid Epileptic Disease

    PubMed Central

    Ramsdell, John S.; Gulland, Frances M.

    2014-01-01

    Domoic acid epileptic disease is characterized by spontaneous recurrent seizures weeks to months after domoic acid exposure. The potential for this disease was first recognized in a human case study of temporal lobe epilepsy after the 1987 amnesic shellfish-poisoning event in Quebec, and was characterized as a chronic epileptic syndrome in California sea lions through investigation of a series of domoic acid poisoning cases between 1998 and 2006. The sea lion study provided a breadth of insight into clinical presentations, unusual behaviors, brain pathology, and epidemiology. A rat model that replicates key observations of the chronic epileptic syndrome in sea lions has been applied to identify the progression of the epileptic disease state, its relationship to behavioral manifestations, and to define the neural systems involved in these behavioral disorders. Here, we present the concept of domoic acid epileptic disease as a delayed manifestation of domoic acid poisoning and review the state of knowledge for this disease state in affected humans and sea lions. We discuss causative mechanisms and neural underpinnings of disease maturation revealed by the rat model to present the concept for olfactory origin of an epileptic disease; triggered in dendodendritic synapases of the olfactory bulb and maturing in the olfactory cortex. We conclude with updated information on populations at risk, medical diagnosis, treatment, and prognosis. PMID:24663110

  16. A Demonstration of Acid Rain

    ERIC Educational Resources Information Center

    Fong, Man Wai

    2004-01-01

    A demonstration showing acid rain formation is described. Oxides of sulfur and nitrogen that result from the burning of fossil fuels are the major pollutants of acid rain. In this demonstration, SO[subscript 2] gas is produced by the burning of matches. An acid-base indicator will show that the dissolved gas turns an aqueous solution acidic.

  17. DOCOSAHEXAENOIC ACID AND ARACHIDONIC ACID PREVENT ESSENTIAL FATTY ACID DEFICIENCY AND HEPATIC STEATOSIS

    PubMed Central

    Le, Hau D.; Meisel, Jonathan A.; de Meijer, Vincent E.; Fallon, Erica M.; Gura, Kathleen M.; Nose, Vania; Bistrian, Bruce R.; Puder, Mark

    2012-01-01

    Objectives Essential fatty acids are important for growth, development, and physiologic function. Alpha-linolenic acid and linoleic acid are the precursors of docosahexaenoic and arachidonic acid, respectively, and have traditionally been considered the essential fatty acids. However, we hypothesized that docosahexaenoic acid and arachidonic acid can function as the essential fatty acids. Methods Using a murine model of essential fatty acid deficiency and consequent hepatic steatosis, we provided mice with varying amounts of docosahexaenoic and arachidonic acids to determine whether exclusive supplementation of docosahexaenoic and arachidonic acids could prevent essential fatty acid deficiency and inhibit or attenuate hepatic steatosis. Results Mice supplemented with docosahexaenoic and arachidonic acids at 2.1% or 4.2% of their calories for 19 days had normal liver histology and no biochemical evidence of essential fatty acid deficiency, which persisted when observed after 9 weeks. Conclusion Supplementation of sufficient amounts of docosahexaenoic and arachidonic acids alone without alpha-linolenic and linoleic acids meets essential fatty acid requirements and prevents hepatic steatosis in a murine model. PMID:22038210

  18. Biodegradation of cyanuric acid.

    PubMed

    Saldick, J

    1974-12-01

    Cyanuric acid biodegrades readily under a wide variety of natural conditions, and particularly well in systems of either low or zero dissolved-oxygen level, such as anaerobic activated sludge and sewage, soils, muds, and muddy streams and river waters, as well as ordinary aerated activated sludge systems with typically low (1 to 3 ppm) dissolved-oxygen levels. Degradation also proceeds in 3.5% sodium chloride solution. Consequently, there are degradation pathways widely available for breaking down cyanuric acid discharged in domestic effluents. The overall degradation reaction is merely a hydrolysis; CO(2) and ammonia are the initial hydrolytic breakdown products. Since no net oxidation occurs during this breakdown, biodegradation of cyanuric acid exerts no primary biological oxygen demand. However, eventual nitrification of the ammonia released will exert its usual biological oxygen demand.

  19. Exposures to acidic aerosols.

    PubMed

    Spengler, J D; Keeler, G J; Koutrakis, P; Ryan, P B; Raizenne, M; Franklin, C A

    1989-02-01

    Ambient monitoring of acid aerosols in four U.S. cities and in a rural region of southern Ontario clearly show distinct periods of strong acidity. Measurements made in Kingston, TN, and Steubenville, OH, resulted in 24-hr H+ ion concentrations exceeding 100 nmole/m3 more than 10 times during summer months. Periods of elevated acidic aerosols occur less frequently in winter months. The H+ determined during episodic conditions in southern Ontario indicates that respiratory tract deposition can exceed the effects level reported in clinical studies. Observed 12-hr H+ concentrations exceeded 550 nmole/m3 (approximately 27 micrograms/m3 H2SO4). The maximum estimated 1-hr concentration exceeded 1500 nmole/m3 for H+ ions. At these concentrations, an active child might receive more than 2000 nmole of H+ ion in 12 hr and in excess of 900 nmole during the hour when H2SO4 exceeded 50 micrograms/m3.

  20. Biodegradation of Cyanuric Acid

    PubMed Central

    Saldick, Jerome

    1974-01-01

    Cyanuric acid biodegrades readily under a wide variety of natural conditions, and particularly well in systems of either low or zero dissolved-oxygen level, such as anaerobic activated sludge and sewage, soils, muds, and muddy streams and river waters, as well as ordinary aerated activated sludge systems with typically low (1 to 3 ppm) dissolved-oxygen levels. Degradation also proceeds in 3.5% sodium chloride solution. Consequently, there are degradation pathways widely available for breaking down cyanuric acid discharged in domestic effluents. The overall degradation reaction is merely a hydrolysis; CO2 and ammonia are the initial hydrolytic breakdown products. Since no net oxidation occurs during this breakdown, biodegradation of cyanuric acid exerts no primary biological oxygen demand. However, eventual nitrification of the ammonia released will exert its usual biological oxygen demand. PMID:4451360

  1. Calorimetry of Nucleic Acids.

    PubMed

    Rozners, Eriks; Pilch, Daniel S; Egli, Martin

    2015-12-01

    This unit describes the application of calorimetry to characterize the thermodynamics of nucleic acids, specifically, the two major calorimetric methodologies that are currently employed: differential scanning (DSC) and isothermal titration calorimetry (ITC). DSC is used to study thermally induced order-disorder transitions in nucleic acids. A DSC instrument measures, as a function of temperature (T), the excess heat capacity (C(p)(ex)) of a nucleic acid solution relative to the same amount of buffer solution. From a single curve of C(p)(ex) versus T, one can derive the following information: the transition enthalpy (ΔH), entropy (ΔS), free energy (ΔG), and heat capacity (ΔCp); the state of the transition (two-state versus multistate); and the average size of the molecule that melts as a single thermodynamic entity (e.g., the duplex). ITC is used to study the hybridization of nucleic acid molecules at constant temperature. In an ITC experiment, small aliquots of a titrant nucleic acid solution (strand 1) are added to an analyte nucleic acid solution (strand 2), and the released heat is monitored. ITC yields the stoichiometry of the association reaction (n), the enthalpy of association (ΔH), the equilibrium association constant (K), and thus the free energy of association (ΔG). Once ΔH and ΔG are known, ΔS can also be derived. Repetition of the ITC experiment at a number of different temperatures yields the ΔCp for the association reaction from the temperature dependence of ΔH.

  2. Acid rain in Asia

    NASA Astrophysics Data System (ADS)

    Bhatti, Neeloo; Streets, David G.; Foell, Wesley K.

    1992-07-01

    Acid rain has been an issue of great concern in North America and Europe during the past several decades. However, due to the passage of a number of recent regulations, most notably the Clean Air Act in the United States in 1990, there is an emerging perception that the problem in these Western nations is nearing solution. The situation in the developing world, particularly in Asia, is much bleaker. Given the policies of many Asian nations to achieve levels of development comparable with the industrialized world—which necessitate a significant expansion of energy consumption (most derived from indigenous coal reserves)—the potential for the formation of, and damage from, acid deposition in these developing countries is very high. This article delineates and assesses the emissions patterns, meteorology, physical geology, and biological and cultural resources present in various Asian nations. Based on this analysis and the risk factors to acidification, it is concluded that a number of areas in Asia are currently vulnerable to acid rain. These regions include Japan, North and South Korea, southern China, and the mountainous portions of Southeast Asia and southwestern India. Furthermore, with accelerated development (and its attendant increase in energy use and production of emissions of acid deposition precursors) in many nations of Asia, it is likely that other regions will also be affected by acidification in the near future. Based on the results of this overview, it is clear that acid deposition has significant potential to impact the Asian region. However, empirical evidence is urgently needed to confirm this and to provide early warning of increases in the magnitude and spread of acid deposition and its effects throughout this part of the world.

  3. Acid Precipitation; (USA)

    SciTech Connect

    Rushing, J.W.; Hicks, S.C.

    1991-01-01

    This publication, Acid Precipitation (APC) announces on a monthly basis the current worldwide information on acid precipitation and closely related subjects, including wet and dry deposition, long-range transport, environmental effects, modeling, and socioeconomic factors. Information on the following subjects is included within the scope of this publication, but all subjects may not appear in each issue: Pollution sources and pollution control technology; atmospheric transport and chemistry; terrestrial transport and chemistry; aquatic transport and chemistry; biological effects; corrosive effects; and socioeconomics, policy, and legislation.

  4. Whither acid rain?

    PubMed

    Brimblecombe, P

    2001-04-01

    Acid rain, the environmental cause célèbre of the 1980s seems to have vanished from popular conscience. By contrast, scientific research, despite funding difficulties, has continued to produce hundreds of research papers each year. Studies of acid rain taught much about precipitation chemistry, the behaviour of snow packs, long-range transport of pollutants and new issues in the biology of fish and forested ecosystems. There is now evidence of a shift away from research in precipitation and sulfur chemistry, but an impressive theoretical base remains as a legacy.

  5. NITRIC ACID PICKLING PROCESS

    DOEpatents

    Boller, E.R.; Eubank, L.D.

    1958-08-19

    An improved process is described for the treatment of metallic uranium surfaces preparatory to being given hot dip coatings. The process consists in first pickling the uraniunn surInce with aqueous 50% to 70% nitric acid, at 60 to 70 deg C, for about 5 minutes, rinsing the acid solution from the uranium article, promptly drying and then passing it through a molten alkali-metal halide flux consisting of 42% LiCl, 53% KCla and 5% NaCl into a molten metal bath consisting of 85 parts by weight of zinc and 15 parts by weight of aluminum

  6. Fatty acids of Thiobacillus thiooxidans.

    PubMed

    Levin, R A

    1971-12-01

    Fatty acid spectra were made on Thiobacillus thiooxidans cultures both in the presence and absence of organic compounds. Small additions of glucose or acetate had no significant effect either on growth or fatty acid content. The addition of biotin had no stimulatory effect but did result in slight quantitative changes in the fatty acid spectrum. The predominant fatty acid was a C(19) cyclopropane acid.

  7. Fatty Acids of Thiobacillus thiooxidans

    PubMed Central

    Levin, Richard A.

    1971-01-01

    Fatty acid spectra were made on Thiobacillus thiooxidans cultures both in the presence and absence of organic compounds. Small additions of glucose or acetate had no significant effect either on growth or fatty acid content. The addition of biotin had no stimulatory effect but did result in slight quantitative changes in the fatty acid spectrum. The predominant fatty acid was a C19 cyclopropane acid. PMID:4945206

  8. The Acid-Base Titration of a Very Weak Acid: Boric Acid

    ERIC Educational Resources Information Center

    Celeste, M.; Azevedo, C.; Cavaleiro, Ana M. V.

    2012-01-01

    A laboratory experiment based on the titration of boric acid with strong base in the presence of d-mannitol is described. Boric acid is a very weak acid and direct titration with NaOH is not possible. An auxiliary reagent that contributes to the release of protons in a known stoichiometry facilitates the acid-base titration. Students obtain the…

  9. Lactic acid bacterial cell factories for gamma-aminobutyric acid.

    PubMed

    Li, Haixing; Cao, Yusheng

    2010-11-01

    Gamma-aminobutyric acid is a non-protein amino acid that is widely present in organisms. Several important physiological functions of gamma-aminobutyric acid have been characterized, such as neurotransmission, induction of hypotension, diuretic effects, and tranquilizer effects. Many microorganisms can produce gamma-aminobutyric acid including bacteria, fungi and yeasts. Among them, gamma-aminobutyric acid-producing lactic acid bacteria have been a focus of research in recent years, because lactic acid bacteria possess special physiological activities and are generally regarded as safe. They have been extensively used in food industry. The production of lactic acid bacterial gamma-aminobutyric acid is safe and eco-friendly, and this provides the possibility of production of new naturally fermented health-oriented products enriched in gamma-aminobutyric acid. The gamma-aminobutyric acid-producing species of lactic acid bacteria and their isolation sources, the methods for screening of the strains and increasing their production, the enzymatic properties of glutamate decarboxylases and the relative fundamental research are reviewed in this article. And the potential applications of gamma-aminobutyric acid-producing lactic acid bacteria were also referred to.

  10. [Studies on interaction of acid-treated nanotube titanic acid and amino acids].

    PubMed

    Zhang, Huqin; Chen, Xuemei; Jin, Zhensheng; Liao, Guangxi; Wu, Xiaoming; Du, Jianqiang; Cao, Xiang

    2010-06-01

    Nanotube titanic acid (NTA) has distinct optical and electrical character, and has photocatalysis character. In accordance with these qualities, NTA was treated with acid so as to enhance its surface activity. Surface structures and surface groups of acid-treated NTA were characterized and analyzed by Transmission Electron Microscope (TEM) and Fourier Transform Infrared Spectrometry (FT-IR). The interaction between acid-treated NTA and amino acids was investigated. Analysis results showed that the lengths of acid-treated NTA became obviously shorter. The diameters of nanotube bundles did not change obviously with acid-treating. Meanwhile, the surface of acid-treated NTA was cross-linked with carboxyl or esterfunction. In addition, acid-treated NTA can catch amino acid residues easily, and then form close combination.

  11. Docosahexaenoic acid and lactation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Docosahexaenoic acid (DHA) is an important component of membrane phospholipids in the retina, and brain, and accumulates rapidly in these tissues during early infancy. DHA is present in human milk, but the amount varies considerably and is largely dependent on maternal diet. This article reviews dat...

  12. Orphenadrinium picrate picric acid

    PubMed Central

    Fun, Hoong-Kun; Hemamalini, Madhukar; Siddaraju, B. P.; Yathirajan, H. S.; Narayana, B.

    2010-01-01

    The asymmetric unit of the title compound N,N-dimethyl-2-[(2-methyl­phen­yl)phenyl­meth­oxy]ethanaminium picrate picric acid, C18H24NO+·C6H2N3O7 −·C6H3N3O7, contains one orphenadrinium cation, one picrate anion and one picric acid mol­ecule. In the orphenadrine cation, the two aromatic rings form a dihedral angle of 70.30 (7)°. There is an intra­molecular O—H⋯O hydrogen bond in the picric acid mol­ecule, which generates an S(6) ring motif. In the crystal structure, the orphenadrine cations, picrate anions and picric acid mol­ecules are connected by strong inter­molecular N—H⋯O hydrogen bonds, π⋯π inter­actions between the benzene rings of cations and anions [centroid–centroid distance = 3.5603 (9) Å] and weak C—H⋯O hydrogen bonds, forming a three-dimensional network. PMID:21580426

  13. Acid Rain Investigations.

    ERIC Educational Resources Information Center

    Hugo, John C.

    1992-01-01

    Presents an activity in which students investigate the formation of solid ammonium chloride aerosol particles to help students better understand the concept of acid rain. Provides activity objectives, procedures, sample data, clean-up instructions, and questions and answers to help interpret the data. (MDH)

  14. The Acid Rain Debate.

    ERIC Educational Resources Information Center

    Oates-Bockenstedt, Catherine

    1997-01-01

    Details an activity designed to motivate students by incorporating science-related issues into a classroom debate. Includes "The Acid Rain Bill" and "Position Guides" for student roles as committee members, consumers, governors, industry owners, tourism professionals, senators, and debate directors. (DKM)

  15. Acid rain bibliography

    SciTech Connect

    Sayers, C.S.

    1983-09-01

    This bibliography identifies 900 citations on various aspects of Acid Rain, covering published bibliographies, books, reports, conference and symposium proceedings, audio visual materials, pamphlets and newsletters. It includes five sections: citations index (complete record of author, title, source, order number); KWIC index; title index; author index; and source index. 900 references.

  16. Acid Rain Classroom Projects.

    ERIC Educational Resources Information Center

    Demchik, Michael J.

    2000-01-01

    Describes a curriculum plan in which students learn about acid rain through instructional media, research and class presentations, lab activities, simulations, design, and design implementation. Describes the simulation activity in detail and includes materials, procedures, instructions, examples, results, and discussion sections. (SAH)

  17. The Acid Rain Debate.

    ERIC Educational Resources Information Center

    Bybee, Rodger; And Others

    1984-01-01

    Describes an activity which provides opportunities for role-playing as industrialists, ecologists, and government officials. The activity involves forming an international commission on acid rain, taking testimony, and, based on the testimony, making recommendations to governments on specific ways to solve the problem. Includes suggestions for…

  18. The Acid Rain Game.

    ERIC Educational Resources Information Center

    Rakow, Steven J.; Glenn, Allen

    1982-01-01

    Provides rationale for and description of an acid rain game (designed for two players), a problem-solving model for elementary students. Although complete instructions are provided, including a copy of the game board, the game is also available for Apple II microcomputers. Information for the computer program is available from the author.…

  19. Targeting tumor acidity

    NASA Astrophysics Data System (ADS)

    Reshetnyak, Yana K.; Engelman, Donald M.; Andreev, Oleg A.

    2012-02-01

    One of the main features of solid tumors is extracellular acidity, which correlates with tumor aggressiveness and metastatic potential. We introduced novel approach in targeting of acidic tumors, and translocation of cell-impermeable cargo molecules across cellular membrane. Our approach is based on main principle of insertion and folding of a polypeptide in lipid bilayer of membrane. We have identified family of pH Low Insertion Peptides (pHLIPs), which are capable spontaneous insertion and folding in membrane at mild acidic conditions. The affinity of peptides of pHLIP family to membrane at low pH is several times higher than at neutral pH. The process of peptides folding occurs within milliseconds. The energy released in a result of folding (about 2 kcal/mol) could be used to move polar cargo across a membrane, which is a novel concept in drug delivery. pHLIP peptides could be considered as a pH-sensitive single peptide molecular transporters and conjugated with imaging probes for fluorescence, MR, PET and SPECT imaging, they represent a novel in vivo marker of acidity. The work is supported by NIH grants CA133890 and GM073857 to OAA, DME, YRK.

  20. Spermatotoxicity of dichloroacetic acid

    EPA Science Inventory

    The testicular toxicity of dichloroacetic acid (DCA), a disinfection byproduct of drinking water, was evaluated in adult male rats given both single and multiple (up to 14 d) oral doses. Delayed spermiation and altered resorption of residual bodies were observed in rats given sin...

  1. Plant fatty acid hydroxylase

    DOEpatents

    Somerville, Chris; van de Loo, Frank

    2000-01-01

    The present invention relates to the identification of nucleic acid sequences and constructs, and methods related thereto, and the use of these sequences and constructs to produce genetically modified plants for the purpose of altering the composition of plant oils, waxes and related compounds.

  2. Alkyl phosphonic acids and sulfonic acids in the Murchison meteorite

    NASA Technical Reports Server (NTRS)

    Cooper, George W.; Onwo, Wilfred M.; Cronin, John R.

    1992-01-01

    Homologous series of alkyl phosphonic acids and alkyl sulfonic acids, along with inorganic orthophosphate and sulfate, are identified in water extracts of the Murchison meteorite after conversion to their t-butyl dimethylsilyl derivatives. The methyl, ethyl, propyl, and butyl compounds are observed in both series. Five of the eight possible alkyl phosphonic acids and seven of the eight possible alkyl sulfonic acids through C4 are identified. Abundances decrease with increasing carbon number as observed of other homologous series indigenous to Murchison. Concentrations range downward from approximately 380 nmol/gram in the alkyl sulfonic acid series, and from 9 nmol/gram in the alkyl phosphonic acid series.

  3. A Direct, Biomass-Based Synthesis of Benzoic Acid: Formic Acid-Mediated Deoxygenation of the Glucose-Derived Materials Quinic Acid and Shikimic Acid

    SciTech Connect

    Arceo, Elena; Ellman, Jonathan; Bergman, Robert

    2010-05-03

    An alternative biomass-based route to benzoic acid from the renewable starting materials quinic acid and shikimic acid is described. Benzoic acid is obtained selectively using a highly efficient, one-step formic acid-mediated deoxygenation method.

  4. 49 CFR 173.158 - Nitric acid.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... material. (b) Nitric acid in any concentration which does not contain sulfuric acid or hydrochloric acid as... sulfuric acid or hydrochloric acid as impurities, when offered for transportation or transported by...

  5. 49 CFR 173.158 - Nitric acid.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... material. (b) Nitric acid in any concentration which does not contain sulfuric acid or hydrochloric acid as... sulfuric acid or hydrochloric acid as impurities, when offered for transportation or transported by...

  6. 49 CFR 173.158 - Nitric acid.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... material. (b) Nitric acid in any concentration which does not contain sulfuric acid or hydrochloric acid as... sulfuric acid or hydrochloric acid as impurities, when offered for transportation or transported by...

  7. Synthesis of acid addition salt of delta-aminolevulinic acid from 5-bromo levulinic acid esters

    DOEpatents

    Moens, Luc

    2003-06-24

    A process of preparing an acid addition salt of delta-aminolevulinc acid comprising: a) dissolving a lower alkyl 5-bromolevulinate and hexamethylenetetramine in a solvent selected from the group consisting of water, ethyl acetate, chloroform, acetone, ethanol, tetrahydrofuran and acetonitrile, to form a quaternary ammonium salt of the lower alkyl 5-bromolevulinate; and b) hydrolyzing the quaternary ammonium salt with an inorganic acid to form an acid addition salt of delta-aminolevulinic acid.

  8. Photostabilization of ascorbic acid with citric acid, tartaric acid and boric acid in cream formulations.

    PubMed

    Ahmad, I; Ali Sheraz, M; Ahmed, S; Shad, Z; Vaid, F H M

    2012-06-01

    This study involves the evaluation of the effect of certain stabilizers, that is, citric acid (CT), tartaric acid (TA) and boric acid (BA) on the degradation of ascorbic acid (AH(2) ) in oil-in-water cream formulations exposed to the UV light and stored in the dark. The apparent first-order rate constants (0.34-0.95 × 10(-3) min(-1) in light, 0.38-1.24 × 10(-2) day(-1) in dark) for the degradation reactions in the presence of the stabilizers have been determined. These rate constants have been used to derive the second-order rate constants (0.26-1.45 × 10(-2) M(-1) min(-1) in light, 3.75-8.50 × 10(-3) M(-1) day(-1) in dark) for the interaction of AH(2) and the individual stabilizers. These stabilizers are effective in causing the inhibition of the rate of degradation of AH(2) both in the light and in the dark. The inhibitory effect of the stabilizers is in the order of CT > TA > BA. The rate of degradation of AH(2) in the presence of these stabilizers in the light is about 120 times higher than that in the dark. This could be explained on the basis of the deactivation of AH(2) -excited triplet state by CT and TA and by the inhibition of AH(2) degradation through complex formation with BA. AH(2) leads to the formation of dehydroascorbic acid (A) by chemical and photooxidation in cream formulations.

  9. Fatty acid-producing hosts

    DOEpatents

    Pfleger, Brian F; Lennen, Rebecca M

    2013-12-31

    Described are hosts for overproducing a fatty acid product such as a fatty acid. The hosts include an exogenous nucleic acid encoding a thioesterase and, optionally, an exogenous nucleic acid encoding an acetyl-CoA carboxylase, wherein an acyl-CoA synthetase in the hosts are functionally delected. The hosts prefereably include the nucleic acid encoding the thioesterase at an intermediate copy number. The hosts are preferably recominantly stable and growth-competent at 37.degree. C. Methods of producing a fatty acid product comprising culturing such hosts at 37.degree. C. are also described.

  10. Acid diffusion through polyaniline membranes

    SciTech Connect

    Su, T.M.; Huang, S.C.; Conklin, J.A.

    1995-12-01

    Polyaniline membranes in the undoped (base) and doped (acid) forms are studied for their utility as pervaporation membranes. The separation of water from mixtures of propionic acid, acetic acid and formic acid have been demonstrated from various feed compositions. Doped polyaniline displays an enhanced selectivity of water over these organic acids as compared with undoped polyaniline. For as-cast polyaniline membranes a diffusion coefficient (D) on the order of 10{sup -9} cm{sup 2}/sec has been determined for the flux of protons through the membranes using hydrochloric acid.

  11. Network flow model analysis of the impact of chlorofluorocarbon phaseout on acid-grade fluorspar. Information circular/1994

    SciTech Connect

    Slatnick, J.A.; Fulton, R.B.

    1994-12-31

    Chlorofluorocarbons (CFC`s) are being phased out and eventually banned under extensive international agreements because the chlorine in CFC`s is thought to deplete the Earth`s ozone layer. As a result, the fluorspar mining industry, which is the source of fluorine in fluorocarbons through intermediate hydrofluoric acid, is being affected. Concern for this impact has led the U.S. Bureau of Mines to employ its capabilities to analyze various scenarios in the evolution of CFC replacements and substitutes to determine their effect on fluorspar mining. This report utilizes a network flow model to examine the effects of proposed replacements for CFC`s, in terms of fluorine content, on fluorspar operations worldwide and on hydrofluoric acid plants in North America and Europe.

  12. A review on methods of recovery of acid(s) from spent pickle liquor of steel industry.

    PubMed

    Ghare, N Y; Wani, K S; Patil, V S

    2013-04-01

    Pickling is the process of removal of oxide layer and rust formed on metal surface. It also removes sand and corrosion products from the surface of metal. Acids such as sulfuric acid, hydrochloric acid are used for pickling. Hydrofluoric acid-Nitric acid mixture is used for stainless steel pickling. Pickling solutions are spent when acid concentration in pickling solutions decreases by 75-85%, which also has metal content up to 150-250 g/ dm3. Spent pickling liquor (SPL) should be dumped because the efficiency of pickling decreases with increasing content of dissolved metal in the bath. The SPL content depends on the plant of origin and the pickling method applied there. SPL from steel pickling in hot-dip galvanizing plants contains zinc(II), iron, traces of lead, chromium. and other heavy metals (max. 500 mg/dm3) and hydrochloric acid. Zinc(II) passes tothe spent solution after dissolution of this metal from zinc(II)-covered racks, chains and baskets used for transportation of galvanized elements. Unevenly covered zinc layers are usually removed in another pickling bath. Due to this, zinc(II) concentration increases even up to 110 g/dm3, while iron content may reach or exceed even 80 g/dm3 in the same solution. This review presents an overview on different aspects of generation and treatment of SPL with recourse to recovery of acid for recycling. Different processes are described in this review and higher weightage is given to membrane processes. PMID:25464702

  13. A review on methods of recovery of acid(s) from spent pickle liquor of steel industry.

    PubMed

    Ghare, N Y; Wani, K S; Patil, V S

    2013-04-01

    Pickling is the process of removal of oxide layer and rust formed on metal surface. It also removes sand and corrosion products from the surface of metal. Acids such as sulfuric acid, hydrochloric acid are used for pickling. Hydrofluoric acid-Nitric acid mixture is used for stainless steel pickling. Pickling solutions are spent when acid concentration in pickling solutions decreases by 75-85%, which also has metal content up to 150-250 g/ dm3. Spent pickling liquor (SPL) should be dumped because the efficiency of pickling decreases with increasing content of dissolved metal in the bath. The SPL content depends on the plant of origin and the pickling method applied there. SPL from steel pickling in hot-dip galvanizing plants contains zinc(II), iron, traces of lead, chromium. and other heavy metals (max. 500 mg/dm3) and hydrochloric acid. Zinc(II) passes tothe spent solution after dissolution of this metal from zinc(II)-covered racks, chains and baskets used for transportation of galvanized elements. Unevenly covered zinc layers are usually removed in another pickling bath. Due to this, zinc(II) concentration increases even up to 110 g/dm3, while iron content may reach or exceed even 80 g/dm3 in the same solution. This review presents an overview on different aspects of generation and treatment of SPL with recourse to recovery of acid for recycling. Different processes are described in this review and higher weightage is given to membrane processes. PMID:25508333

  14. Treatment of Bile Acid Amidation Defects with Glycocholic Acid

    PubMed Central

    Heubi, James E.; Setchell, Kenneth D.R.; Jha, Pinky; Buckley, Donna; Zhang, Wujuan; Rosenthal, Philip; Potter, Carol; Horslen, Simon; Suskind, David

    2014-01-01

    Bile acid amidation defects were predicted to present with fat/fat soluble vitamin malabsorption with minimal cholestasis. We identified and treated 5 patients (1 male/4 females) from 4 families with defective bile acid amidation due to a genetically confirmed deficiency in bile acid CoA:amino acid N-acyl transferase (BAAT) with the conjugated bile acid, glycocholic acid (GCA). Fast atom bombardment-mass spectrometry analysis of urine and bile at baseline revealed predominantly unconjugated cholic acid and absence of the usual glycine and taurine conjugated primary bile acids. Treatment with 15 mg/kg GCA resulted in total duodenal bile acid concentrations of 23.3 ± 19.1 mmol/L (mean ± SD) and 63.5 ± 4.0% of the bile acids were secreted in bile in the conjugated form of which GCA represented 59.6 ± 9.3% of the total biliary bile acids. Unconjugated cholic acid continued to be present in high concentrations in bile because of partial intestinal deconjugation of orally administered GCA. Serum total bile acid concentrations did not significantly differ between pretreatment and post-treatment samples and serum contained predominantly unconjugated cholic acid. These findings confirmed efficient intestinal absorption, hepatic extraction and biliary secretion of the administered GCA. Oral tolerance tests for vitamin D2 (1000 IU vitamin D2/kg) and tocopherol (100 IU/kg tocopherol acetate) demonstrated improvement in fat-soluble vitamin absorption after GCA treatment. Growth improved in 3/3 growth-delayed prepubertal patients. Conclusions: Oral glycocholic acid therapy is safe and effective in improving growth and fat-soluble vitamin absorption in children and adolescents with inborn errors of bile acid metabolism due to amidation defects. PMID:25163551

  15. [Lipid synthesis by an acidic acid tolerant Rhodotorula glutinis].

    PubMed

    Lin, Zhangnan; Liu, Hongjuan; Zhang, Jian'an; Wang, Gehua

    2016-03-01

    Acetic acid, as a main by-product generated in the pretreatment process of lignocellulose hydrolysis, significantly affects cell growth and lipid synthesis of oleaginous microorganisms. Therefore, we studied the tolerance of Rhodotorula glutinis to acetic acid and its lipid synthesis from substrate containing acetic acid. In the mixed sugar medium containing 6 g/L glucose and 44 g/L xylose, and supplemented with acetic acid, the cell growth was not:inhibited when the acetic acid concentration was below 10 g/L. Compared with the control, the biomass, lipid concentration and lipid content of R. glutinis increased 21.5%, 171% and 122% respectively when acetic acid concentration was 10 g/L. Furthermore, R. glutinis could accumulate lipid with acetate as the sole carbon source. Lipid concentration and lipid yield reached 3.20 g/L and 13% respectively with the initial acetic acid concentration of 25 g/L. The lipid composition was analyzed by gas chromatograph. The main composition of lipid produced with acetic acid was palmitic acid, stearic acid, oleic acid, linoleic acid and linolenic acid, including 40.9% saturated fatty acids and 59.1% unsaturated fatty acids. The lipid composition was similar to that of plant oil, indicating that lipid from oleaginous yeast R. glutinis had potential as the feedstock of biodiesel production. These results demonstrated that a certain concentration of acetic acid need not to be removed in the detoxification process when using lignocelluloses hydrolysate to produce microbial lipid by R. glutinis. PMID:27349116

  16. NAPAP (National Acid Precipitation Assessment Program) results on acid rain

    SciTech Connect

    Not Available

    1990-06-01

    The National Acid Precipitation Assessment Program (NAPAP) was mandated by Congress in 1980 to study the effects of acid rain. The results of 10 years of research on the effect of acid deposition and ozone on forests, particularly high elevation spruce and fir, southern pines, eastern hardwoods and western conifers, will be published this year.

  17. Acid Earth--The Global Threat of Acid Pollution.

    ERIC Educational Resources Information Center

    McCormick, John

    Acid pollution is a major international problem, but the debate it has elicited has often clouded the distinction between myth and facts. This publication attempts to concerning the acid pollution situation. This publication attempts to identify available facts. It is the first global review of the problem of acid pollution and the first to…

  18. Usnic acid controls the acidity tolerance of lichens.

    PubMed

    Hauck, Markus; Jürgens, Sascha-René

    2008-11-01

    The hypotheses were tested that, firstly, lichens producing the dibenzofuran usnic acid colonize substrates characterized by specific pH ranges, secondly, this preferred pH is in a range where soluble usnic acid and its corresponding anion occur in similar concentrations, and thirdly, usnic acid makes lichens vulnerable to acidity. Lichens with usnic acid prefer an ambient pH range between 3.5 and 5.5 with an optimum between 4.0 and 4.5. This optimum is close to the pK(a1) value of usnic acid of 4.4. Below this optimum pH, dissolved SO(2) reduces the chlorophyll fluorescence yield more in lichens with than without their natural content of usnic acid. This suggests that usnic acid influences the acidity tolerance of lichens. The putative mechanism of the limited acidity tolerance of usnic acid-containing lichens is the acidification of the cytosol by molecules of protonated usnic acid shuttling protons through the plasma membrane at an apoplastic pH

  19. College Chemistry Students' Mental Models of Acids and Acid Strength

    ERIC Educational Resources Information Center

    McClary, LaKeisha; Talanquer, Vicente

    2011-01-01

    The central goal of this study was to characterize the mental models of acids and acid strength expressed by advanced college chemistry students when engaged in prediction, explanation, and justification tasks that asked them to rank chemical compounds based on their relative acid strength. For that purpose we completed a qualitative research…

  20. Acid hydrolysis of cellulose

    SciTech Connect

    Salazar, H.

    1980-12-01

    One of the alternatives to increase world production of etha nol is by the hydrolysis of cellulose content of agricultural residues. Studies have been made on the types of hydrolysis: enzimatic and acid. Data obtained from the sulphuric acid hydrolysis of cellulose showed that this process proceed in two steps, with a yield of approximately 95% glucose. Because of increases in cost of alternatives resources, the high demand of the product and the more economic production of ethanol from cellulose materials, it is certain that this technology will be implemented in the future. At the same time further studies on the disposal and reuse of the by-products of this production must be undertaken.

  1. [Progress in glucaric acid].

    PubMed

    Qiu, Yuying; Fang, Fang; Du, Guocheng; Chen, Jian

    2015-04-01

    Glucaric acid (GA) is derived from glucose and commonly used in chemical industry. It is also considered as one of the "Top value-added chemicals from biomass" as carbohydrate monomers to produce various synthetic polymers and bioenergy. The demand for GA in food manufacture is increasing. GA has also attracted public attentions due to its therapeutic uses such as regulating hormones, increasing the immune function and reducing the risks of cancers. Currently GA is produced by chemical oxidation. Research on production of GA via microbial synthesis is still at preliminary stage. We reviewed the advances of glucaric acid applications, preparation and quantification methods. The prospects on production of GA by microbial fermentation were also discussed. PMID:26380405

  2. Eucomic acid methanol monosolvate

    PubMed Central

    Li, Guo-Qiang; Li, Yao-Lan; Wang, Guo-Cai; Liang, Zhi-Hong; Jiang, Ren-Wang

    2011-01-01

    In the crystal structure of the title compound [systematic name: 2-hy­droxy-2-(4-hy­droxy­benz­yl)butane­dioic acid methanol monosolvate], C11H12O6·CH3OH, the dihedral angles between the planes of the carboxyl groups and the benzene ring are 51.23 (9) and 87.97 (9)°. Inter­molecular O—H⋯O hydrogen-bonding inter­actions involving the hy­droxy and carb­oxy­lic acid groups and the methanol solvent mol­ecule give a three-dimensional structure. PMID:22091200

  3. Industrial ecotoxicology "acid rain".

    PubMed

    Astolfi, E; Gotelli, C; Higa, J

    1986-01-01

    The acid rain phenomenon was studied in the province of Cordoba, Argentina. This study, based on a previously outlined framework, determined the anthropogenic origin of the low pH due to the presence of industrial hydrochloric acid wastage. This industrial ecotoxicological phenomenon seriously affected the forest wealth, causing a great defoliation of trees and shrubs, with a lower effect on crops. A survey on its effects on human beings has not been carried out, but considering the corrosion caused to different metals and its denouncing biocide effect on plants and animals, we should expect to find some kind of harm to the health of the workers involved or others engaged in farming, and even to those who are far away from the polluting agent. PMID:3758667

  4. Industrial ecotoxicology "acid rain".

    PubMed

    Astolfi, E; Gotelli, C; Higa, J

    1986-01-01

    The acid rain phenomenon was studied in the province of Cordoba, Argentina. This study, based on a previously outlined framework, determined the anthropogenic origin of the low pH due to the presence of industrial hydrochloric acid wastage. This industrial ecotoxicological phenomenon seriously affected the forest wealth, causing a great defoliation of trees and shrubs, with a lower effect on crops. A survey on its effects on human beings has not been carried out, but considering the corrosion caused to different metals and its denouncing biocide effect on plants and animals, we should expect to find some kind of harm to the health of the workers involved or others engaged in farming, and even to those who are far away from the polluting agent.

  5. (Radioiodinated free fatty acids)

    SciTech Connect

    Knapp, Jr., F. F.

    1987-12-11

    The traveler participated in the Second International Workshop on Radioiodinated Free Fatty Acids in Amsterdam, The Netherlands where he presented an invited paper describing the pioneering work at the Oak Ridge National Laboratory (ORNL) involving the design, development and testing of new radioiodinated methyl-branched fatty acids for evaluation of heart disease. He also chaired a technical session on the testing of new agents in various in vitro and in vivo systems. He also visited the Institute for Clinical and Experimental Nuclear Medicine in Bonn, West Germany, to review, discuss, plan and coordinate collaborative investigations with that institution. In addition, he visited the Cyclotron Research Center in Liege, Belgium, to discuss continuing collaborative studies with the Osmium-191/Iridium-191m radionuclide generator system, and to complete manuscripts and plan future studies.

  6. Immunomodulatory spherical nucleic acids.

    PubMed

    Radovic-Moreno, Aleksandar F; Chernyak, Natalia; Mader, Christopher C; Nallagatla, Subbarao; Kang, Richard S; Hao, Liangliang; Walker, David A; Halo, Tiffany L; Merkel, Timothy J; Rische, Clayton H; Anantatmula, Sagar; Burkhart, Merideth; Mirkin, Chad A; Gryaznov, Sergei M

    2015-03-31

    Immunomodulatory nucleic acids have extraordinary promise for treating disease, yet clinical progress has been limited by a lack of tools to safely increase activity in patients. Immunomodulatory nucleic acids act by agonizing or antagonizing endosomal toll-like receptors (TLR3, TLR7/8, and TLR9), proteins involved in innate immune signaling. Immunomodulatory spherical nucleic acids (SNAs) that stimulate (immunostimulatory, IS-SNA) or regulate (immunoregulatory, IR-SNA) immunity by engaging TLRs have been designed, synthesized, and characterized. Compared with free oligonucleotides, IS-SNAs exhibit up to 80-fold increases in potency, 700-fold higher antibody titers, 400-fold higher cellular responses to a model antigen, and improved treatment of mice with lymphomas. IR-SNAs exhibit up to eightfold increases in potency and 30% greater reduction in fibrosis score in mice with nonalcoholic steatohepatitis (NASH). Given the clinical potential of SNAs due to their potency, defined chemical nature, and good tolerability, SNAs are attractive new modalities for developing immunotherapies.

  7. Acid rain in Asia

    SciTech Connect

    Bhatti, N.; Streets, D.G. ); Foell, W.K. )

    1991-01-01

    Acid rain has been an issue of widespread concern in North America and Europe for more than fifteen years. However, there is an emerging feeling that the problem in Europe and North America is nearing solution, largely as a result of existing and newly enacted legislation, decreased energy use due to conservation and efficiency improvements, and/or trends in energy policy away from fossil fuels. The situation in Asia appears much bleaker. Fossil fuels are already used in large quantities, such that local air pollution is becoming a serious problem and high deposition levels are being measured. Emission regulations in most countries (with the notable exception of Japan) are not very stringent. Energy plans in many countries (particularly PRC, India, Thailand, and South Korea) call for very large increases in coal combustion in the future. Finally, there is not presently a strong scientific or public constituency for action to mitigate the potential effects of acid deposition. These factors imply potentially serious problems in the future for long-range transport and deposition of sulfur and nitrogen species and consequent damage to ecosystems and materials. The political ramifications of transboundary environmental pollution in this region are also potentially serious. The purpose of this paper is to provide background information on the acid deposition situation in Asia, with the intention of laying the foundation for the development of a possible research program for this region. 36 refs., 8 figs., 8 tabs.

  8. Immunomodulatory spherical nucleic acids

    PubMed Central

    Radovic-Moreno, Aleksandar F.; Chernyak, Natalia; Mader, Christopher C.; Nallagatla, Subbarao; Kang, Richard S.; Hao, Liangliang; Walker, David A.; Halo, Tiffany L.; Merkel, Timothy J.; Rische, Clayton H.; Anantatmula, Sagar; Burkhart, Merideth; Mirkin, Chad A.; Gryaznov, Sergei M.

    2015-01-01

    Immunomodulatory nucleic acids have extraordinary promise for treating disease, yet clinical progress has been limited by a lack of tools to safely increase activity in patients. Immunomodulatory nucleic acids act by agonizing or antagonizing endosomal toll-like receptors (TLR3, TLR7/8, and TLR9), proteins involved in innate immune signaling. Immunomodulatory spherical nucleic acids (SNAs) that stimulate (immunostimulatory, IS-SNA) or regulate (immunoregulatory, IR-SNA) immunity by engaging TLRs have been designed, synthesized, and characterized. Compared with free oligonucleotides, IS-SNAs exhibit up to 80-fold increases in potency, 700-fold higher antibody titers, 400-fold higher cellular responses to a model antigen, and improved treatment of mice with lymphomas. IR-SNAs exhibit up to eightfold increases in potency and 30% greater reduction in fibrosis score in mice with nonalcoholic steatohepatitis (NASH). Given the clinical potential of SNAs due to their potency, defined chemical nature, and good tolerability, SNAs are attractive new modalities for developing immunotherapies. PMID:25775582

  9. Perfluorooctanoic acid and environmental risks

    EPA Science Inventory

    Perfluorooctanoic acid (PFOA) is a member of the perfluoroalkyl acids (PFAA) family of chemicals, which consist of a carbon backbone typically four to fourteen carbons in length and a charged functional moiety.

  10. Folic Acid Questions and Answers

    MedlinePlus

    ... swallow large pills. How can I take a vitamin with folic acid? A : These days, multivitamins with folic acid come in chewable chocolate or fruit flavors, liquids, and large oval or smaller round ...

  11. Omega-3 fatty acids (image)

    MedlinePlus

    Omega-3 fatty acids are a form of polyunsaturated fat that the body derives from food. Omega-3s (and omega-6s) are known as essential fatty acids (EFAs) because they are important for good health. ...

  12. Acid rain: Reign of controversy

    SciTech Connect

    Kahan, A.M.

    1986-01-01

    Acid Rain is a primer on the science and politics of acid rain. Several introductory chapters describe in simple terms the relevant principles of water chemistry, soil chemistry, and plant physiology and discuss the demonstrated or postulated effects of acid rain on fresh waters and forests as well as on statuary and other exposed objects. There follow discussions on the economic and social implications of acid rain (for example, possible health effects) and on the sources, transport, and distribution of air pollutants.

  13. Sedimentation of sulfuric acid in acid tars from current production

    SciTech Connect

    Denisova, T.L.; Frolov, A.F.; Aminov, A.N.; Novosel'tsev, S.P.

    1987-09-01

    Acid tars obtained in treating T-750, KhF-12, and I-8A oils were investigated for purposes of recovering sulfuric acid and asphalt binders from the compositions and of determining the effects of storage time on the recovery. The consumption and sedimentation levels of sulfuric acid during storage for different periods and at different temperatures were assessed. The characteristics of an asphalt binder obtained by neutralizing acid tar with a paste consisting of asphalts from deasphalting operations and slaked lime, followed by oxidation of the mixture with atmospheric air, were determined. The sulfuric acid recovered in the settling process could be burned in order to purify it of organic contaminants.

  14. FURNACE INJECTION OF ALKALINE SORBENTS FOR SULFURIC ACID CONTROL

    SciTech Connect

    Gary M. Blythe

    2000-12-01

    A test program is being sponsored by the US Department of Energy (DOE), EPRI, FirstEnergy, and TVA to investigate furnace injection of alkaline sorbents as a means of reducing sulfuric acid concentrations in the flue gas from coal-fired boilers. This test program is being conducted at the FirstEnergy Bruce Mansfield Plant (BMP), although later testing will be conducted at a TVA plant. A sorbent injection test was conducted the week of April 18, 2000. The test was the first of several short-term (one- to two-week duration) tests to investigate the effectiveness of various alkaline sorbents for sulfuric acid control and the effects of these sorbents on boiler equipment performance. This first short-term test investigated the effect of injecting dry dolomite powder (CaCO{sub 3} {center_dot} MgCO{sub 3}), a mineral similar to limestone, into the furnace of Unit 2. During the test program, various analytical techniques were used to assess the effects of sorbent injection. These primarily included sampling with the controlled condensation system (CCS) for determining flue gas SO{sub 3} content and an acid dew-point (ADP) meter for determining the sulfuric acid dew point (and, indirectly, the concentration of sulfuric acid) of the flue gas. EPA Reference Method 26a was used for determining hydrochloric acid (HCl) and hydrofluoric acid (HF), as well and chlorine (Cl{sub 2}) and fluorine (F{sub 2}) concentrations in the flue gas. Fly ash resistivity was measured using a Southern Research Institute (SRI) point-to-plane resistivity probe, and unburned carbon in fly ash was determined by loss on ignition (LOI). Coal samples were also collected and analyzed for a variety of parameters. Finally, visual observations were made of boiler furnace and convective pass surfaces prior to and during sorbent injection.

  15. Sequential injection redox or acid-base titration for determination of ascorbic acid or acetic acid.

    PubMed

    Lenghor, Narong; Jakmunee, Jaroon; Vilen, Michael; Sara, Rolf; Christian, Gary D; Grudpan, Kate

    2002-12-01

    Two sequential injection titration systems with spectrophotometric detection have been developed. The first system for determination of ascorbic acid was based on redox reaction between ascorbic acid and permanganate in an acidic medium and lead to a decrease in color intensity of permanganate, monitored at 525 nm. A linear dependence of peak area obtained with ascorbic acid concentration up to 1200 mg l(-1) was achieved. The relative standard deviation for 11 replicate determinations of 400 mg l(-1) ascorbic acid was 2.9%. The second system, for acetic acid determination, was based on acid-base titration of acetic acid with sodium hydroxide using phenolphthalein as an indicator. The decrease in color intensity of the indicator was proportional to the acid content. A linear calibration graph in the range of 2-8% w v(-1) of acetic acid with a relative standard deviation of 4.8% (5.0% w v(-1) acetic acid, n=11) was obtained. Sample throughputs of 60 h(-1) were achieved for both systems. The systems were successfully applied for the assays of ascorbic acid in vitamin C tablets and acetic acid content in vinegars, respectively.

  16. Nervonic acid and demyelinating disease.

    PubMed

    Sargent, J R; Coupland, K; Wilson, R

    1994-04-01

    Demyelination in adrenoleukodystrophy (ALD) is associated with an accumulation of very long chain saturated fatty acids such as 26:0 stemming from a genetic defect in the peroxisomal beta oxidation system responsible for the chain shortening of these fatty acids. Long chain monoenoic acids such as erucic acid, 22:1(n-9), can normalise elevated serum levels of 26:0 in ALD by depressing their biosynthesis from shorter chain saturated fatty acids. Sphingolipids from post mortem ALD brain have decreased levels of nervonic acid, 24:1(n-9), and increased levels of stearic acid, 18:0. Increased levels of 26:0 are accompanied by decreased nervonic acid biosynthesis in skin fibroblasts from ALD patients. Sphingolipids from post mortem MS brain have the same decreased 24:1(n-9) and increased 18:0 seen in post mortem ALD brain. The 24:1(n-9) content of sphingomyelin is depressed in erythrocytes from multiple sclerosis (MS) patients. Defects in the microsomal biosynthesis of very long chain fatty acids including 24:1(n-9) in 'jumpy' and 'quaking' mice are accompanied by impaired myelination. An impairment in the provision of nervonic acid in demyelinating diseases is indicated, suggesting that dietary therapy with oils rich in very long chain monenoic acid fatty acids may be beneficial in such conditions.

  17. Pantothenic acid biosynthesis in zymomonas

    SciTech Connect

    Tao, Luan; Tomb, Jean-Francois; Viitanen, Paul V.

    2014-07-01

    Zymomonas is unable to synthesize pantothenic acid and requires this essential vitamin in growth medium. Zymomonas strains transformed with an operon for expression of 2-dehydropantoate reductase and aspartate 1-decarboxylase were able to grow in medium lacking pantothenic acid. These strains may be used for ethanol production without pantothenic acid supplementation in seed culture and fermentation media.

  18. An Umbrella for Acid Rain.

    ERIC Educational Resources Information Center

    Randal, Judith

    1979-01-01

    The Environmental Protection Agency has awarded several grants to study effects of and possible solutions to the problem of "acid rain"; pollution from atmospheric nitric and sulfuric acids. The research program is administered through North Carolina State University at Raleigh and will focus on biological effects of acid rain. (JMF)

  19. Carboxylic acid sorption regeneration process

    DOEpatents

    King, C.J.; Poole, L.J.

    1995-05-02

    Carboxylic acids are sorbed from aqueous feedstocks into an organic liquid phase or onto a solid adsorbent. The acids are freed from the sorbent phase by treating it with aqueous alkylamine thus forming an alkylammonium carboxylate which is dewatered and decomposed to the desired carboxylic acid and the alkylamine. 10 figs.

  20. Carboxylic acid sorption regeneration process

    DOEpatents

    King, C. Judson; Poole, Loree J.

    1995-01-01

    Carboxylic acids are sorbed from aqueous feedstocks into an organic liquid phase or onto a solid adsorbent. The acids are freed from the sorbent phase by treating it with aqueous alkylamine thus forming an alkylammonium carboxylate which is dewatered and decomposed to the desired carboxylic acid and the alkylamine.

  1. Heterogeneous uptake of amines by citric acid and humic acid.

    PubMed

    Liu, Yongchun; Ma, Qingxin; He, Hong

    2012-10-16

    Heterogeneous uptake of methylamine (MA), dimethylamine (DMA), and trimethylamine (TMA) onto citric acid and humic acid was investigated using a Knudsen cell reactor coupled to a quadrupole mass spectrometer at 298 K. Acid-base reactions between amines and carboxylic acids were confirmed. The observed uptake coefficients of MA, DMA, and TMA on citric acid at 298 K were measured to be 7.31 ± 1.13 × 10(-3), 6.65 ± 0.49 × 10(-3), and 5.82 ± 0.68 × 10(-3), respectively, and showed independence of sample mass. The observed uptake coefficients of MA, DMA, and TMA on humic acid at 298 K increased linearly with sample mass, and the true uptake coefficients of MA, DMA, and TMA were measured to be 1.26 ± 0.07 × 10(-5), 7.33 ± 0.40 × 10(-6), and 4.75 ± 0.15 × 10(-6), respectively. Citric acid, having stronger acidity, showed a higher reactivity than humic acid for a given amine; while the steric effect of amines was found to govern the reactivity between amines and citric acid or humic acid.

  2. Composition for nucleic acid sequencing

    SciTech Connect

    Korlach, Jonas; Webb, Watt W.; Levene, Michael; Turner, Stephen; Craighead, Harold G.; Foquet, Mathieu

    2008-08-26

    The present invention is directed to a method of sequencing a target nucleic acid molecule having a plurality of bases. In its principle, the temporal order of base additions during the polymerization reaction is measured on a molecule of nucleic acid, i.e. the activity of a nucleic acid polymerizing enzyme on the template nucleic acid molecule to be sequenced is followed in real time. The sequence is deduced by identifying which base is being incorporated into the growing complementary strand of the target nucleic acid by the catalytic activity of the nucleic acid polymerizing enzyme at each step in the sequence of base additions. A polymerase on the target nucleic acid molecule complex is provided in a position suitable to move along the target nucleic acid molecule and extend the oligonucleotide primer at an active site. A plurality of labelled types of nucleotide analogs are provided proximate to the active site, with each distinguishable type of nucleotide analog being complementary to a different nucleotide in the target nucleic acid sequence. The growing nucleic acid strand is extended by using the polymerase to add a nucleotide analog to the nucleic acid strand at the active site, where the nucleotide analog being added is complementary to the nucleotide of the target nucleic acid at the active site. The nucleotide analog added to the oligonucleotide primer as a result of the polymerizing step is identified. The steps of providing labelled nucleotide analogs, polymerizing the growing nucleic acid strand, and identifying the added nucleotide analog are repeated so that the nucleic acid strand is further extended and the sequence of the target nucleic acid is determined.

  3. Evolution of rosmarinic acid biosynthesis.

    PubMed

    Petersen, Maike; Abdullah, Yana; Benner, Johannes; Eberle, David; Gehlen, Katja; Hücherig, Stephanie; Janiak, Verena; Kim, Kyung Hee; Sander, Marion; Weitzel, Corinna; Wolters, Stefan

    2009-01-01

    Rosmarinic acid and chlorogenic acid are caffeic acid esters widely found in the plant kingdom and presumably accumulated as defense compounds. In a survey, more than 240 plant species have been screened for the presence of rosmarinic and chlorogenic acids. Several rosmarinic acid-containing species have been detected. The rosmarinic acid accumulation in species of the Marantaceae has not been known before. Rosmarinic acid is found in hornworts, in the fern family Blechnaceae and in species of several orders of mono- and dicotyledonous angiosperms. The biosyntheses of caffeoylshikimate, chlorogenic acid and rosmarinic acid use 4-coumaroyl-CoA from the general phenylpropanoid pathway as hydroxycinnamoyl donor. The hydroxycinnamoyl acceptor substrate comes from the shikimate pathway: shikimic acid, quinic acid and hydroxyphenyllactic acid derived from l-tyrosine. Similar steps are involved in the biosyntheses of rosmarinic, chlorogenic and caffeoylshikimic acids: the transfer of the 4-coumaroyl moiety to an acceptor molecule by a hydroxycinnamoyltransferase from the BAHD acyltransferase family and the meta-hydroxylation of the 4-coumaroyl moiety in the ester by a cytochrome P450 monooxygenase from the CYP98A family. The hydroxycinnamoyltransferases as well as the meta-hydroxylases show high sequence similarities and thus seem to be closely related. The hydroxycinnamoyltransferase and CYP98A14 from Coleus blumei (Lamiaceae) are nevertheless specific for substrates involved in RA biosynthesis showing an evolutionary diversification in phenolic ester metabolism. Our current view is that only a few enzymes had to be "invented" for rosmarinic acid biosynthesis probably on the basis of genes needed for the formation of chlorogenic and caffeoylshikimic acid while further biosynthetic steps might have been recruited from phenylpropanoid metabolism, tocopherol/plastoquinone biosynthesis and photorespiration. PMID:19560175

  4. Evolution of rosmarinic acid biosynthesis.

    PubMed

    Petersen, Maike; Abdullah, Yana; Benner, Johannes; Eberle, David; Gehlen, Katja; Hücherig, Stephanie; Janiak, Verena; Kim, Kyung Hee; Sander, Marion; Weitzel, Corinna; Wolters, Stefan

    2009-01-01

    Rosmarinic acid and chlorogenic acid are caffeic acid esters widely found in the plant kingdom and presumably accumulated as defense compounds. In a survey, more than 240 plant species have been screened for the presence of rosmarinic and chlorogenic acids. Several rosmarinic acid-containing species have been detected. The rosmarinic acid accumulation in species of the Marantaceae has not been known before. Rosmarinic acid is found in hornworts, in the fern family Blechnaceae and in species of several orders of mono- and dicotyledonous angiosperms. The biosyntheses of caffeoylshikimate, chlorogenic acid and rosmarinic acid use 4-coumaroyl-CoA from the general phenylpropanoid pathway as hydroxycinnamoyl donor. The hydroxycinnamoyl acceptor substrate comes from the shikimate pathway: shikimic acid, quinic acid and hydroxyphenyllactic acid derived from l-tyrosine. Similar steps are involved in the biosyntheses of rosmarinic, chlorogenic and caffeoylshikimic acids: the transfer of the 4-coumaroyl moiety to an acceptor molecule by a hydroxycinnamoyltransferase from the BAHD acyltransferase family and the meta-hydroxylation of the 4-coumaroyl moiety in the ester by a cytochrome P450 monooxygenase from the CYP98A family. The hydroxycinnamoyltransferases as well as the meta-hydroxylases show high sequence similarities and thus seem to be closely related. The hydroxycinnamoyltransferase and CYP98A14 from Coleus blumei (Lamiaceae) are nevertheless specific for substrates involved in RA biosynthesis showing an evolutionary diversification in phenolic ester metabolism. Our current view is that only a few enzymes had to be "invented" for rosmarinic acid biosynthesis probably on the basis of genes needed for the formation of chlorogenic and caffeoylshikimic acid while further biosynthetic steps might have been recruited from phenylpropanoid metabolism, tocopherol/plastoquinone biosynthesis and photorespiration.

  5. Microbial transformations of isocupressic acid.

    PubMed

    Lin, S J; Rosazza, J P

    1998-07-01

    Microbial transformations of the labdane-diterpene isocupressic acid (1) with different microorganisms yielded several oxygenated metabolites that were isolated and characterized by MS and NMR spectroscopic analyses. Nocardia aurantia (ATCC 12674) catalyzed the cleavage of the 13,14-double bond to yield a new nor-labdane metabolite, 2. Cunninghamella elegans (-) (NRRL 1393) gave 7beta-hydroxyisocupressic acid (3) and labda-7,13(E)-diene-6beta,15, 17-triol-19-oic acid (4), and Mucor mucedo (ATCC 20094) gave 2alpha-hydroxyisocupressic acid (5) and labda-8(17),14-diene-2alpha, 13-diol-19-oic acid (6).

  6. Invasive cleavage of nucleic acids

    DOEpatents

    Prudent, James R.; Hall, Jeff G.; Lyamichev, Victor I.; Brow, Mary Ann D.; Dahlberg, James E.

    2002-01-01

    The present invention relates to means for the detection and characterization of nucleic acid sequences, as well as variations in nucleic acid sequences. The present invention also relates to methods for forming a nucleic acid cleavage structure on a target sequence and cleaving the nucleic acid cleavage structure in a site-specific manner. The structure-specific nuclease activity of a variety of enzymes is used to cleave the target-dependent cleavage structure, thereby indicating the presence of specific nucleic acid sequences or specific variations thereof.

  7. Invasive cleavage of nucleic acids

    DOEpatents

    Prudent, James R.; Hall, Jeff G.; Lyamichev, Victor I.; Brow, Mary Ann D.; Dahlberg, James E.

    1999-01-01

    The present invention relates to means for the detection and characterization of nucleic acid sequences, as well as variations in nucleic acid sequences. The present invention also relates to methods for forming a nucleic acid cleavage structure on a target sequence and cleaving the nucleic acid cleavage structure in a site-specific manner. The structure-specific nuclease activity of a variety of enzymes is used to cleave the target-dependent cleavage structure, thereby indicating the presence of specific nucleic acid sequences or specific variations thereof.

  8. The politics of acid rain

    SciTech Connect

    Wilcher, M.E. )

    1989-01-01

    This work examines and compares the acid rain policies through the different political systems of Canada, Great Britain and the United States. Because the flow of acid rain can transcend national boundaries, acid rain has become a crucial international problem. According to the author, because of differences in governmental institutions and structure, the extent of governmental intervention in the industrial economy, the degree of reliance on coal for power generation, and the extent of acid rain damage, national responses to the acid rain problem have varied.

  9. [A catalogue of fatty acids].

    PubMed

    Canalejo, E; Martín Peña, G; Gómez Molero, L; Ruiz Galiana, J

    1996-01-01

    Fatty acids structure and function is an area of renewed interest because of its effects on plasma lipids, biosynthesis of prostaglandins, leucotrienes and thromboxanes, and the obligatory demands of some fatty acids, especially for the newborn. Fatty acids are identified in three different ways: by the classical nomenclature, by its trivial name, and by the new methods also known as the omega system. These three different methods have created some confusion. The aim of this article is to revise fatty acids chemical structure and to compile a list of nutritional important fatty acids with the three different terminologies.

  10. Tested Demonstrations: Color Oscillations in the Formic Acid-Nitric Acid-Sulfuric Acid System.

    ERIC Educational Resources Information Center

    Raw, C. J. G.; And Others

    1983-01-01

    Presented are procedures for demonstrating the production of color oscillations when nitric acid is added to a formic acid/concentrated sulfuric acid mixture. Because of safety considerations, "Super-8" home movie of the color changes was found to be satisfactory for demonstration purposes. (JN)

  11. Twinning of dodecanedicarboxylic acid

    NASA Technical Reports Server (NTRS)

    Sen, R.; Wilcox, W. R.

    1986-01-01

    Twinning of 1,10-dodecanedicarboxyl acid (DDA) was observed in 0.1 mm thick films with a polarizing microscope. Twins originated from polycrystalline regions which tended to nucleate on twin faces, and terminated by intersection gone another. Twinning increased dramatically with addition of organic compounds with a similar molecular size and shape. Increasing the freezing rate, increasing the temperature gradient, and addition of silica particles increased twinning. It is proposed that twins nucleate with polycrystals and sometimes anneal out before they become observable. The impurities may enhance twinning either by lowering the twin energy or by adsorbing on growing faces.

  12. Mycophenolic Acid in Silage

    PubMed Central

    Schneweis, Isabell; Meyer, Karsten; Hörmansdorfer, Stefan; Bauer, Johann

    2000-01-01

    We examined 233 silage samples and found that molds were present in 206 samples with counts between 1 × 103 and 8.9 × 107 (mean, 4.7 × 106) CFU/g. Mycophenolic acid, a metabolite of Penicillium roqueforti, was detected by liquid chromatography-mass spectrometry in 74 (32%) of these samples at levels ranging from 20 to 35,000 (mean, 1,400) μg/kg. This compound has well-known immunosuppressive properties, so feeding with contaminated silage may promote the development of infectious diseases in livestock. PMID:10919834

  13. Synthesis of amino acids

    DOEpatents

    Davis, J.W. Jr.

    1979-09-21

    A method is described for synthesizing amino acids preceding through novel intermediates of the formulas: R/sub 1/R/sub 2/C(OSOC1)CN, R/sub 1/R/sub 2/C(C1)CN and (R/sub 1/R/sub 2/C(CN)O)/sub 2/SO wherein R/sub 1/ and R/sub 2/ are each selected from hydrogen and monovalent hydrocarbon radicals of 1 to 10 carbon atoms. The use of these intermediates allows the synthesis steps to be exothermic and results in an overall synthesis method which is faster than the synthesis methods of the prior art.

  14. Beyond acid rain

    SciTech Connect

    Gaffney, J.S.; Streit, G.E.; Spall, W.D.; Hall, J.H.

    1987-06-01

    This paper discussed the effects of the interactions of soluble oxidants and organic toxins with sulfur dioxide and nitrogen dioxide. It suggested that these chemical reactions in the atmosphere produced a more potent acid rain which was harmful not only because it had a low pH but because it contained oxidants and organic toxins which were harmful to surface vegetation and the organisms found in surface waters. It was stressed that air pollution is a global problem and that is is necessary to develop a better fundamental understanding of how air pollution is causing damage to the streams and forests of the world. 50 references.

  15. Interstellar isothiocyanic acid

    NASA Technical Reports Server (NTRS)

    Frerking, M. A.; Linke, R. A.; Thaddeus, P.

    1979-01-01

    Isothiocyanic acid (HNCS) has been identified in Sgr B2 from millimeter-wave spectral line observations. We have definitely detected three rotational lines, and have probably detected two others. The rotational temperature of HNCS in Sgr B2 is 14 plus or minus 5 K, its column density is 2.5 plus or minus 1.0 x 10 to the 13th per sq cm, and its abundance relative to HNCO is consistent with the cosmic S/O ratio, 1/42.

  16. 20-hydroxyeicosatetraenoic acid and epoxyeicosatrienoic acids and blood pressure.

    PubMed

    McGiff, J C; Quilley, J

    2001-03-01

    The properties of 20-hydroxyeicosatetraenoic acid and epoxyeicosatrienoic acids, vasoactivity and modulation of ion transport and mediation/modulation of the effects of vasoactive hormones, such as angiotensin II and endothelin, underscore their importance to renal vascular mechanisms and electrolyte excretion. 20-Hydroxyeicosatetraenoic acid is an integral component of renal autoregulation and tubuloglomerular feedback as well as cerebral autoregulation, eliciting vasoconstriction by the inhibition of potassium channels. Nitric oxide inhibits 20-hydroxyeicosatetraenoic acid formation, the removal of which contributes to the vasodilator effect of nitric oxide. In contrast, epoxyeicosatrienoic acids are generally vasodilatory by activating potassium channels and have been proposed as endothelium-derived hyperpolarizing factors. 20-Hydroxyeicosatetraenoic acid modulates ion transport in key nephron segments by influencing the activities of sodium--potassium-ATPase and the sodium--potassium--chloride co-transporter; however, the primacy of the various arachidonate oxygenases that generate products affecting these activities changes with age. The range and diversity of activity of 20-hydroxyeicosatetraenoic acid is influenced by its metabolism by cyclooxygenase to products affecting vasomotion and salt/water excretion. 20-Hydroxyeicosatetraenoic acid is the principal renal eicosanoid that interacts with several hormonal systems that are central to blood pressure regulation. This article reviews the most recent studies that address 20-hydroxyeicosatetraenoic acid and epoxyeicosatrienoic acids in vascular and renal tubular function and hypertension.

  17. Vibrational structure of the polyunsaturated fatty acids eicosapentaenoic acid and arachidonic acid studied by infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Kiefer, Johannes; Noack, Kristina; Bartelmess, Juergen; Walter, Christian; Dörnenburg, Heike; Leipertz, Alfred

    2010-02-01

    The spectroscopic discrimination of the two structurally similar polyunsaturated C 20 fatty acids (PUFAs) 5,8,11,14,17-eicosapentaenoic acid and 5,8,11,14-eicosatetraenoic acid (arachidonic acid) is shown. For this purpose their vibrational structures are studied by means of attenuated total reflection (ATR) Fourier-transform infrared (FT-IR) spectroscopy. The fingerprint regions of the recorded spectra are found to be almost identical, while the C-H stretching mode regions around 3000 cm -1 show such significant differences as results of electronic and molecular structure alterations based on the different degree of saturation that both fatty acids can be clearly distinguished from each other.

  18. Nucleic acid detection methods

    DOEpatents

    Smith, C.L.; Yaar, R.; Szafranski, P.; Cantor, C.R.

    1998-05-19

    The invention relates to methods for rapidly determining the sequence and/or length a target sequence. The target sequence may be a series of known or unknown repeat sequences which are hybridized to an array of probes. The hybridized array is digested with a single-strand nuclease and free 3{prime}-hydroxyl groups extended with a nucleic acid polymerase. Nuclease cleaved heteroduplexes can be easily distinguish from nuclease uncleaved heteroduplexes by differential labeling. Probes and target can be differentially labeled with detectable labels. Matched target can be detected by cleaving resulting loops from the hybridized target and creating free 3-hydroxyl groups. These groups are recognized and extended by polymerases added into the reaction system which also adds or releases one label into solution. Analysis of the resulting products using either solid phase or solution. These methods can be used to detect characteristic nucleic acid sequences, to determine target sequence and to screen for genetic defects and disorders. Assays can be conducted on solid surfaces allowing for multiple reactions to be conducted in parallel and, if desired, automated. 18 figs.

  19. Nucleic Acid Detection Methods

    DOEpatents

    Smith, Cassandra L.; Yaar, Ron; Szafranski, Przemyslaw; Cantor, Charles R.

    1998-05-19

    The invention relates to methods for rapidly determining the sequence and/or length a target sequence. The target sequence may be a series of known or unknown repeat sequences which are hybridized to an array of probes. The hybridized array is digested with a single-strand nuclease and free 3'-hydroxyl groups extended with a nucleic acid polymerase. Nuclease cleaved heteroduplexes can be easily distinguish from nuclease uncleaved heteroduplexes by differential labeling. Probes and target can be differentially labeled with detectable labels. Matched target can be detected by cleaving resulting loops from the hybridized target and creating free 3-hydroxyl groups. These groups are recognized and extended by polymerases added into the reaction system which also adds or releases one label into solution. Analysis of the resulting products using either solid phase or solution. These methods can be used to detect characteristic nucleic acid sequences, to determine target sequence and to screen for genetic defects and disorders. Assays can be conducted on solid surfaces allowing for multiple reactions to be conducted in parallel and, if desired, automated.

  20. Cryoprotection from lipoteichoic acid

    NASA Astrophysics Data System (ADS)

    Rice, Charles V.; Middaugh, Amy; Wickham, Jason R.; Friedline, Anthony; Thomas, Kieth J.; Johnson, Karen; Zachariah, Malcolm; Garimella, Ravindranth

    2012-10-01

    Numerous chemical additives lower the freezing point of water, but life at sub-zero temperatures is sustained by a limited number of biological cryoprotectants. Antifreeze proteins in fish, plants, and insects provide protection to a few degrees below freezing. Microbes have been found to survive at even lower temperatures, and with a few exceptions, antifreeze proteins are missing. Survival has been attributed to external factors, such as the high salt concentration of brine veins and adhesion to particulates or ice crystal defects. We have discovered an endogenous cryoprotectant in the cell wall of bacteria, lipoteichoic acid biopolymers. Adding 1% LTA to bacteria cultures immediately prior to freezing provides 50% survival rate, similar to the results obtained with 1% glycerol. In the absence of an additive, bacterial survival is negligible as measured with the resazurin cell viability assay. The mode of action for LTA cryoprotection is unknown. With a molecular weight of 3-5 kDa, it is unlikely to enter the cell cytoplasm. Our observations suggest that teichoic acids could provide a shell of liquid water around biofilms and planktonic bacteria, removing the need for brine veins to prevent bacterial freezing.

  1. Bicyclic glutamic acid derivatives.

    PubMed

    Meyer, Udo; Bisel, Philippe; Weckert, Edgar; Frahm, August Wilhelm

    2006-05-15

    For the second-generation asymmetric synthesis of the trans-tris(homoglutamic) acids via Strecker reaction of chiral ketimines, the cyanide addition as the key stereodifferentiating step produces mixtures of diastereomeric alpha-amino nitrile esters the composition of which is independent of the reaction temperature and the type of the solvent, respectively. The subsequent hydrolysis is exclusively achieved with concentrated H(2)SO(4) yielding diastereomeric mixtures of three secondary alpha-amino alpha-carbamoyl-gamma-esters and two diastereomeric cis-fused angular alpha-carbamoyl gamma-lactams as bicyclic glutamic acid derivatives, gained from in situ stereomer differentiating cyclisation of the secondary cis-alpha-amino alpha-carbamoyl-gamma-esters. Separation was achieved by CC. The pure secondary trans-alpha-amino alpha-carbamoyl-gamma-esters cyclise on heating and treatment with concentrated H(2)SO(4), respectively, to diastereomeric cis-fused angular secondary alpha-amino imides. Their hydrogenolysis led to the enantiomeric cis-fused angular primary alpha-amino imides. The configuration of all compounds was completely established by NMR methods, CD-spectra, and by X-ray analyses of the (alphaR,1R,5R)-1-carbamoyl-2-(1-phenylethyl)-2-azabicyclo[3.3.0]octan-3-one and of the trans-alphaS,1S,2R-2-ethoxycarbonylmethyl-1-(1-phenylethylamino)cyclopentanecarboxamide. PMID:16596563

  2. Ribonucleic acid purification.

    PubMed

    Martins, R; Queiroz, J A; Sousa, F

    2014-08-15

    Research on RNA has led to many important biological discoveries and improvement of therapeutic technologies. From basic to applied research, many procedures employ pure and intact RNA molecules; however their isolation and purification are critical steps because of the easy degradability of RNA, which can impair chemical stability and biological functionality. The current techniques to isolate and purify RNA molecules still have several limitations and the requirement for new methods able to improve RNA quality to meet regulatory demands is growing. In fact, as basic research improves the understanding of biological roles of RNAs, the biopharmaceutical industry starts to focus on them as a biotherapeutic tools. Chromatographic bioseparation is a high selective unit operation and is the major option in the purification of biological compounds, requiring high purity degree. In addition, its application in biopharmaceutical manufacturing is well established. This paper discusses the importance and the progress of RNA isolation and purification, considering RNA applicability both in research and clinical fields. In particular and in view of the high specificity, affinity chromatography has been recently applied to RNA purification processes. Accordingly, recent chromatographic investigations based on biorecognition phenomena occurring between RNA and amino acids are focused. Histidine and arginine have been used as amino acid ligands, and their ability to isolate different RNA species demonstrated a multipurpose applicability in molecular biology analysis and RNA therapeutics preparation, highlighting the potential contribution of these methods to overcome the challenges of RNA purification. PMID:24951289

  3. Titration of phosphonic acid derivatives in mixtures.

    PubMed

    Wittmann, Z

    1980-01-01

    An analytical procedure is described for the determination of the weak acids phosphonomethyliminodiacetic acid and phosphonomethyliminoacetic acid in their mixtures, and the dissociation constants of phosphonomethyliminoacetic acid are reported.

  4. Growth of nitric acid hydrates on thin sulfuric acid films

    NASA Technical Reports Server (NTRS)

    Iraci, Laura T.; Middlebrook, Ann M.; Wilson, Margaret A.; Tolbert, Margaret A.

    1994-01-01

    Type I polar stratospheric clouds (PSCs) are thought to nucleate and grow on stratospheric sulfate aerosols (SSAs). To model this system, thin sulfuric acid films were exposed to water and nitric acid vapors (1-3 x 10(exp -4) Torr H2O and 1-2.5 x 10(exp -6) Torr HNO3) and subjected to cooling and heating cycles. Fourier Transform Infrared (FTIR) spectroscopy was used to probe the phase of the sulfuric acid and to identify the HNO3/H2O films that condensed. Nitric acid trihydrate (NAT) was observed to grow on crystalline sulfuric acid tetrahydrate (SAT) films. NAT also condensed in/on supercooled H2SO4 films without causing crystallization of the sulfuric acid. This growth is consistent with NAT nucleation from ternary solutions as the first step in PSC formation.

  5. Determination of benzoic acid, chlorobenzoic acids and chlorendic acid in water

    SciTech Connect

    Dietz, E.A.; Cortellucci, N.J.; Singley, K.F. )

    1993-01-01

    To characterize and conduct treatment studies of a landfill leachate an analysis procedure was required to determine concentrations of benzoic acid, the three isomers of chlorobenzoic acid and chlorendic acid. The title compounds were isolated from acidified (pH 1) water by extraction with methyl t-butyl ether. Analytes were concentrated by back-extracting the ether with 0.1 N sodium hydroxide which was separated and acidified. This solution was analyzed by C[sub 18] reversed-phase HPLC with water/acetonitrile/acetic acid eluent and UV detection at 222 nm. The method has detection limits of 200 [mu]g/L for chlorendic acid and 100 [mu]g/L for benzoic acid and each isomer of chlorobenzoic acid. Validation studies with water which was fortified with the analytes at concentrations ranging from one to ten times detection limits resulted in average recoveries of >95%.

  6. Acid rain: Rhetoric and reality

    SciTech Connect

    Park, C.C.

    1987-01-01

    Acid rain is now one of the most serious environmental problems in developed countries. Emissions and fallout were previously extremely localized, but since the introduction of tall stacks policies in both Britain and the US - pardoxically to disperse particulate pollutants and hence reduce local damage - emissions are now lifted into the upper air currents and carried long distances downwind. The acid rain debate now embraces many western countries - including Canada, the US, England, Scotland, Wales, Sweden, Norway, Denmark, West Germany, the Netherlands, Austria, Switzerland - and a growing number of eastern countries - including the Soviet Union, Poland, East Germany, and Czechoslovakia. The problem of acid rain arises, strictly speaking, not so much from the rainfall itself as from its effects on the environment. Runoff affects surface water and groundwater, as well as soils and vegetation. Consequently changes in rainfall acidity can trigger off a range of impacts on the chemistry and ecology of lakes and rivers, soil chemistry and processes, the health and productivity of plants, and building materials, and metallic structures. The most suitable solutions to the problems of acid rain require prevention rather than cure, and there is broad agreement in both the political scientific communities on the need to reduce emissions of sulfur and nitrogen oxides to the atmosphere. Book divisions discuss: the problem of acid rain, the science of acid rain, the technology of acid rain, and the politics of acid rain, in an effort to evaluate this growing global problem of acid rain.

  7. Therapeutic targeting of bile acids

    PubMed Central

    Gores, Gregory J.

    2015-01-01

    The first objectives of this article are to review the structure, chemistry, and physiology of bile acids and the types of bile acid malabsorption observed in clinical practice. The second major theme addresses the classical or known properties of bile acids, such as the role of bile acid sequestration in the treatment of hyperlipidemia; the use of ursodeoxycholic acid in therapeutics, from traditional oriental medicine to being, until recently, the drug of choice in cholestatic liver diseases; and the potential for normalizing diverse bowel dysfunctions in irritable bowel syndrome, either by sequestering intraluminal bile acids for diarrhea or by delivering more bile acids to the colon to relieve constipation. The final objective addresses novel concepts and therapeutic opportunities such as the interaction of bile acids and the microbiome to control colonic infections, as in Clostridium difficile-associated colitis, and bile acid targeting of the farnesoid X receptor and G protein-coupled bile acid receptor 1 with consequent effects on energy expenditure, fat metabolism, and glycemic control. PMID:26138466

  8. Bile Acid Metabolism and Signaling

    PubMed Central

    Chiang, John Y. L.

    2015-01-01

    Bile acids are important physiological agents for intestinal nutrient absorption and biliary secretion of lipids, toxic metabolites, and xenobiotics. Bile acids also are signaling molecules and metabolic regulators that activate nuclear receptors and G protein-coupled receptor (GPCR) signaling to regulate hepatic lipid, glucose, and energy homeostasis and maintain metabolic homeostasis. Conversion of cholesterol to bile acids is critical for maintaining cholesterol homeostasis and preventing accumulation of cholesterol, triglycerides, and toxic metabolites, and injury in the liver and other organs. Enterohepatic circulation of bile acids from the liver to intestine and back to the liver plays a central role in nutrient absorption and distribution, and metabolic regulation and homeostasis. This physiological process is regulated by a complex membrane transport system in the liver and intestine regulated by nuclear receptors. Toxic bile acids may cause inflammation, apoptosis, and cell death. On the other hand, bile acid-activated nuclear and GPCR signaling protects against inflammation in liver, intestine, and macrophages. Disorders in bile acid metabolism cause cholestatic liver diseases, dyslipidemia, fatty liver diseases, cardiovascular diseases, and diabetes. Bile acids, bile acid derivatives, and bile acid sequestrants are therapeutic agents for treating chronic liver diseases, obesity, and diabetes in humans. PMID:23897684

  9. Bile acid interactions with cholangiocytes.

    PubMed

    Xia, Xuefeng; Francis, Heather; Glaser, Shannon; Alpini, Gianfranco; LeSage, Gene

    2006-06-14

    Cholangiocytes are exposed to high concentrations of bile acids at their apical membrane. A selective transporter for bile acids, the Apical Sodium Bile Acid Cotransporter (ASBT) (also referred to as Ibat; gene name Slc10a2) is localized on the cholangiocyte apical membrane. On the basolateral membrane, four transport systems have been identified (t-ASBT, multidrug resistance (MDR)3, an unidentified anion exchanger system and organic solute transporter (Ost) heteromeric transporter, Ostalpha-Ostbeta. Together, these transporters unidirectionally move bile acids from ductal bile to the circulation. Bile acids absorbed by cholangiocytes recycle via the peribiliary plexus back to hepatocytes for re-secretion into bile. This recycling of bile acids between hepatocytes and cholangiocytes is referred to as the cholehepatic shunt pathway. Recent studies suggest that the cholehepatic shunt pathway may contribute in overall hepatobiliary transport of bile acids and to the adaptation to chronic cholestasis due to extrahepatic obstruction. ASBT is acutely regulated by an adenosine 3', 5'-monophosphate (cAMP)-dependent translocation to the apical membrane and by phosphorylation-dependent ubiquitination and proteasome degradation. ASBT is chronically regulated by changes in gene expression in response to biliary bile acid concentration and inflammatory cytokines. Another potential function of cholangiocyte ASBT is to allow cholangiocytes to sample biliary bile acids in order to activate intracellular signaling pathways. Bile acids trigger changes in intracellular calcium, protein kinase C (PKC), phosphoinositide 3-kinase (PI3K), mitogen-activated protein (MAP) kinase and extracellular signal-regulated protein kinase (ERK) intracellular signals. Bile acids significantly alter cholangiocyte secretion, proliferation and survival. Different bile acids have differential effects on cholangiocyte intracellular signals, and in some instances trigger opposing effects on cholangiocyte

  10. Citric acid production patent review.

    PubMed

    Anastassiadis, Savas; Morgunov, Igor G; Kamzolova, Svetlana V; Finogenova, Tatiana V

    2008-01-01

    Current Review article summarizes the developments in citric acid production technologies in East and West last 100 years. Citric acid is commercially produced by large scale fermentation mostly using selected fungal or yeast strains in aerobe bioreactors and still remains one of the runners in industrial production of biotechnological bulk metabolites obtained by microbial fermentation since about 100 years, reflecting the historical development of modern biotechnology and fermentation process technology in East and West. Citric acid fermentation was first found as a fungal product in cultures of Penicillium glaucum on sugar medium by Wehmer in 1893. Citric acid is an important multifunctional organic acid with a broad range of versatile uses in household and industrial applications that has been produced industrially since the beginning of 20(th) century. There is a great worldwide demand for citric acid consumption due to its low toxicity, mainly being used as acidulant in pharmaceutical and food industries. Global citric acid production has reached 1.4 million tones, increasing annually at 3.5-4.0% in demand and consumption. Citric acid production by fungal submerged fermentation is still dominating, however new perspectives like solid-state processes or continuous yeast processes can be attractive for producers to stand in today's strong competition in industry. Further perspectives aiming in the improvement of citric acid production are the improvement of citric acid producing strains by classical and modern mutagenesis and selection as well as downstream processes. Many inexpensive by-products and residues of the agro-industry (e.g. molasses, glycerin etc.) can be economically utilized as substrates in the production of citric acid, especially in solid-state fermentation, enormously reducing production costs and minimizing environmental problems. Alternatively, continuous processes utilizing yeasts which reach 200-250 g/l citric acid can stand in today

  11. Bile acid interactions with cholangiocytes

    PubMed Central

    Xia, Xuefeng; Francis, Heather; Glaser, Shannon; Alpini, Gianfranco; LeSage, Gene

    2006-01-01

    Cholangiocytes are exposed to high concentrations of bile acids at their apical membrane. A selective transporter for bile acids, the Apical Sodium Bile Acid Cotransporter (ASBT) (also referred to as Ibat; gene name Slc10a2) is localized on the cholangiocyte apical membrane. On the basolateral membrane, four transport systems have been identified (t-ASBT, multidrug resistance (MDR)3, an unidentified anion exchanger system and organic solute transporter (Ost) heteromeric transporter, Ostα-Ostβ. Together, these transporters unidirectionally move bile acids from ductal bile to the circulation. Bile acids absorbed by cholangiocytes recycle via the peribiliary plexus back to hepatocytes for re-secretion into bile. This recycling of bile acids between hepatocytes and cholangiocytes is referred to as the cholehepatic shunt pathway. Recent studies suggest that the cholehepatic shunt pathway may contribute in overall hepatobiliary transport of bile acids and to the adaptation to chronic cholestasis due to extrahepatic obstruction. ASBT is acutely regulated by an adenosine 3', 5’-monophosphate (cAMP)-dependent translocation to the apical membrane and by phosphorylation-dependent ubiquitination and proteasome degradation. ASBT is chronically regulated by changes in gene expression in response to biliary bile acid concentration and inflammatory cytokines. Another potential function of cholangiocyte ASBT is to allow cholangiocytes to sample biliary bile acids in order to activate intracellular signaling pathways. Bile acids trigger changes in intracellular calcium, protein kinase C (PKC), phosphoinositide 3-kinase (PI3K), mitogen-activated protein (MAP) kinase and extracellular signal-regulated protein kinase (ERK) intracellular signals. Bile acids significantly alter cholangiocyte secretion, proliferation and survival. Different bile acids have differential effects on cholangiocyte intracellular signals, and in some instances trigger opposing effects on cholangiocyte

  12. Interactions of amino acids, carboxylic acids, and mineral acids with different quinoline derivatives

    NASA Astrophysics Data System (ADS)

    Kalita, Dipjyoti; Deka, Himangshu; Samanta, Shyam Sundar; Guchait, Subrata; Baruah, Jubaraj B.

    2011-03-01

    A series of quinoline containing receptors having amide and ester bonds are synthesized and characterised. The relative binding abilities of these receptors with various amino acids, carboxylic acids and mineral acids are determined by monitoring the changes in fluorescence intensity. Among the receptors bis(2-(quinolin-8-yloxy)ethyl) isophthalate shows fluorescence enhancement on addition of amino acids whereas the other receptors shows fluorescence quenching on addition of amino acids. The receptor N-(quinolin-8-yl)-2-(quinolin-8-yloxy) propanamide has higher binding affinity for amino acids. However, the receptor N-(quinolin-8-yl)-2-(quinolin-8-yloxy)acetamide having similar structure do not bind to amino acids. This is attributed to the concave structure of the former which is favoured due to the presence of methyl substituent. The receptor bis(2-(quinolin-8-yloxy)ethyl) isophthalate do not bind to hydroxy carboxylic acids, but is a good receptor for dicarboxylic acids. The crystal structure of bromide and perchlorate salts of receptor 2-bromo-N-(quinolin-8-yl)-propanamide are determined. In both the cases the amide groups are not in the plane of quinoline ring. The structure of N-(quinolin-8-yl)-2-(quinolin-8-yloxy)acetamide, N-(2-methoxyphenethyl)-2-(quinolin-8-yloxy)acetamide and their salts with maleic acid as well as fumaric acid are determined. It is observed that the solid state structures are governed by the double bond geometry of these two acid. Maleic acid forms salt in both the cases, whereas fumaric acid forms either salt or co-crystals.

  13. Acidity of Strong Acids in Water and Dimethyl Sulfoxide.

    PubMed

    Trummal, Aleksander; Lipping, Lauri; Kaljurand, Ivari; Koppel, Ilmar A; Leito, Ivo

    2016-05-26

    Careful analysis and comparison of the available acidity data of HCl, HBr, HI, HClO4, and CF3SO3H in water, dimethyl sulfoxide (DMSO), and gas-phase has been carried out. The data include experimental and computational pKa and gas-phase acidity data from the literature, as well as high-level computations using different approaches (including the W1 theory) carried out in this work. As a result of the analysis, for every acid in every medium, a recommended acidity value is presented. In some cases, the currently accepted pKa values were revised by more than 10 orders of magnitude. PMID:27115918

  14. Esterification by the Plasma Acidic Water: Novel Application of Plasma Acid

    NASA Astrophysics Data System (ADS)

    Gu, Ling

    2014-03-01

    This work explores the possibility of plasma acid as acid catalyst in organic reactions. Plasma acidic water was prepared by dielectric barrier discharge and used to catalyze esterification of n-heptanioc acid with ethanol. It is found that the plasma acidic water has a stable and better performance than sulfuric acid, meaning that it is an excellent acid catalyst. The plasma acidic water would be a promising alternative for classic mineral acid as a more environment friendly acid.

  15. 49 CFR 173.158 - Nitric acid.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 2 2012-10-01 2012-10-01 false Nitric acid. 173.158 Section 173.158... Nitric acid. (a) Nitric acid exceeding 40 percent concentration may not be packaged with any other material. (b) Nitric acid in any concentration which does not contain sulfuric acid or hydrochloric acid...

  16. Acid rain degradation of nylon

    SciTech Connect

    Kyllo, K.E.

    1984-01-01

    Acid rain, precipitation with a pH less than 5.6, is known to damage lakes, vegetation and buildings. Degradation of outdoor textiles by acid rain is strongly suspected but not well documented. This study reports the effects of sunlight, aqueous acid, heat and humidity (acid rain conditions) on spun delustered nylon 6,6 fabric. Untreated nylon and nylon treated with sulfuric acid of pH 2.0, 3.0, and 4.4 were exposed to light in an Atlas Xenon-arc fadeometer at 63/sup 0/C and 65% R.H. for up to 640 AATCC Fading Units. The untreated and acid treated nylon fabrics were also exposed to similar temperature and humidity condition without light. Nylon degradation was determined by changes in breaking strength, elongation, molecular weight, color, amino end group concentration (NH/sub 2/) and /sup 13/C NMR spectra. Physical damage was assessed using SEM.

  17. A Simpler Nucleic Acid

    NASA Technical Reports Server (NTRS)

    Orgel, Leslie

    2000-01-01

    It has been supposed that for a nucleic acid analog to pair with RNA it must, like RNA, have a backbone with at least a sixatom repeat; a shorter backbone presumably would not stretch far enough to bind RNA properly. The Eschenmoser group has shown, however, that this first impression is incorrect.As they report in their new paper, Eschenmoser and co-workers ( I ) have now synthesized a substantial number of these polymers, which are called (L)-a-threofuranosyl oligonucleotides or TNAs. They are composed of bases linked to a threose sugar-phosphate backbone, with phosphodiester bonds connecting the nucleotides. The investigators discovered that pairs of complementary TNAs do indeed form stable Watson-Crick double helices and, perhaps more importantly, that TNAs form stable double helices with complementary RNAs and DNAs.

  18. Laser restoring the glass surface treated with acid-based paint

    NASA Astrophysics Data System (ADS)

    Strusevich, Anastasia V.; Poltaev, Yuriy A.; Sinev, Dmitrii A.

    2013-11-01

    The modern city facilities are often being attacked by graffiti artists, and increasingly vandals leave "tags" using paints, which compound based on acids, hydrofluoric or acetic commonly. These paints not only ink the surface, but also increase the surface roughness, and such impact can not be corrected by conventional cleaning. Thus, it was requested to develop technology that would not only clean the surface, but also to restore its structure by smoothing out irregularities and roughness formed after exposure in acid. In this work we investigated the effect of restoring the surface of the glass, spoiled by acid-based paint and then treated with CO2-laser. During the experiments, it was found that it is real to create the single-step laser surface restoring technology.

  19. Preparation and characterization Al3+-bentonite Turen Malang for esterification fatty acid (palmitic acid, oleic acid and linoleic acid)

    NASA Astrophysics Data System (ADS)

    Abdulloh, Abdulloh; Aminah, Nanik Siti; Triyono, Mudasir, Trisunaryanti, Wega

    2016-03-01

    Catalyst preparation and characterization of Al3+-bentonite for esterification of palmitic acid, oleic acid and linoleic acid has been done. Al3+-bentonite catalyst was prepared from natural bentonite of Turen Malang through cation exchange reaction using AlCl3 solution. The catalysts obtained were characterized by XRD, XRF, pyridine-FTIR and surface area analyser using the BET method. Catalyst activity test of Al3+-bentonite for esterification reaction was done at 65°C using molar ratio of metanol-fatty acid of 30:1 and 0.25 g of Al3+-bentonite catalyst for the period of ½, 1, 2, 3, 4 and 5 hours. Based on the characterization results, the Al3+-bentonite Turen Malang catalyst has a d-spacing of 15.63 Ǻ, acid sites of Brönsted and Lewis respectively of 230.79 µmol/g and 99.39 µmol/g, surface area of 507.3 m2/g and the average of radius pore of 20.09 Å. GC-MS analysis results of the oil phase after esterification reaction showed the formation of biodiesel (FAME: Fatty acid methyl ester), namely methyl palmitate, methyl oleate and methyl linoleate. The number of conversions resulted in esterification reaction using Al3+-bentonite Turen Malang catalyst was 74.61%, 37.75%, and 20, 93% for the esterification of palmitic acid, oleic acid and linoleic acid respectively.

  20. Acidic gas capture by diamines

    SciTech Connect

    Rochelle, Gary; Hilliard, Marcus

    2011-05-10

    Compositions and methods related to the removal of acidic gas. In particular, the present disclosure relates to a composition and method for the removal of acidic gas from a gas mixture using a solvent comprising a diamine (e.g., piperazine) and carbon dioxide. One example of a method may involve a method for removing acidic gas comprising contacting a gas mixture having an acidic gas with a solvent, wherein the solvent comprises piperazine in an amount of from about 4 to about 20 moles/kg of water, and carbon dioxide in an amount of from about 0.3 to about 0.9 moles per mole of piperazine.

  1. Molecular structural studies of lichen substances II: atranorin, gyrophoric acid, fumarprotocetraric acid, rhizocarpic acid, calycin, pulvinic dilactone and usnic acid

    NASA Astrophysics Data System (ADS)

    Edwards, Howell G. M.; Newton, Emma M.; Wynn-Williams, David D.

    2003-06-01

    The FT-Raman and infrared vibrational spectra of some important lichen compounds from two metabolic pathways are characterised. Key biomolecular marker bands have been suggested for the spectroscopic identification of atranorin, gyrophoric acid, fumarprotocetraric acid rhizocarpic acid, calycin, pulvinic dilactone and usnic acid. A spectroscopic protocol has been defined for the detection of these molecules in organisms subjected to environmental stresses such as UV-radiation exposure, desiccation and low temperatures. Use of the protocol will be made for the assessment of survival strategies used by stress-tolerant lichens in Antarctic cold deserts.

  2. Cryoprotection from bacterial teichoic acid

    NASA Astrophysics Data System (ADS)

    Rice, Charles V.; Harrison, William; Kirkpatrick, Karl; Brown, Eric D.

    2009-08-01

    Recent studies from our lab demonstrated that teichoic acid is surrounded by liquid water at -40 °C. The size and shape of the liquid water pockets has been visualized with fluorescence microscopy images of aqueous Rhodamine- B solutions. The long, thin channels surround ice crystals with a size of 5-20 microns. Subsequent studies show that B. subtilis Gram-positive bacteria are sequestered into large pockets without added teichoic acid. Here, the ice crystals are orders of manitude larger. When bacteria are mixed with teichoic acid solutions, the distribution of bacteria changes dramatically. The smaller ice crystals allow the bacteria to align in the thin channels of liquid water seen with teichoic acid only. The role of teichoic acid in the freeze tolerance was examined with live/dead fluorescence assays of bacteria mixed with teichoic acid. These quantitative assays were used to determine if teichoic acid acts in a synergetic fashion to enhance the survivability of E. coli, a gram-negative species which lacks teichoic acid. Additionally, we have obtained B. subtilis mutants lacking wall-associated teichoic acids to evaluate cryoprotection compared to the wild-type strain.

  3. Replacement of liquid H{sub 2}SO{sub 4} and HF with solid acid catalysts: A study of mixed metal phosphates as solid acid catalysts

    SciTech Connect

    Jackson, N.B.; Nenoff, T.M.; Thoma, S.G.; Kohler, S.D.

    1997-10-01

    The primary purpose of this LDRD was to identify and optimize materials as solid acid catalysts for the replacement of environmentally hazardous liquid acids such as H{sub 2}SO{sub 4} and HF which are used as catalysts in both the petroleum and chemical industries. Liquid acids have significant safety, environmental and engineering difficulties associated with their use in process chemistry. Special equipment/materials need to be used with liquid acids. Hydrofluoric acid poses unique safety problems due to it insipid attack on skin and tissue as well as its tendency to plume and travel long distances as a plume when it is released in the atmosphere. Therefore, any time a solid acid catalyst can be used to replace a liquid acid in a processes step, significant environmental, safety, and financial gains can be realized. The majority of work in this LDRD was performed on novel mixed metal phosphates which are a new solid acid catalyst material. Primarily the model reaction, 2-methyl-2-pentene isomerization, was used to determine acidity. These materials were tested for their activity, their deactivation and their stability. In addition, some of the phosphate materials were synthesized using templates in order to try to form a three dimensional network material from these phosphates. The amorphous sulfated zirconium-titanium phosphates were more acidic, as measured by olefin isomerization, than sulfated zirconia. However, they showed some of the same failings as sulfated zirconia in that they deactivated quickly and lost sulfur in a reducing atmosphere. Certain of the mixed metal phosphates, particularly tantalum-containing phosphates, showed strong acidity compared to sulfated zirconia as measured by olefin isomerization reaction.

  4. Sulfuric acid as autocatalyst in the formation of sulfuric acid.

    PubMed

    Torrent-Sucarrat, Miquel; Francisco, Joseph S; Anglada, Josep M

    2012-12-26

    Sulfuric acid can act as a catalyst of its own formation. We have carried out a computational investigation on the gas-phase formation of H(2)SO(4) by hydrolysis of SO(3) involving one and two water molecules, and also in the presence of sulfuric acid and its complexes with one and two water molecules. The hydrolysis of SO(3) requires the concurrence of two water molecules, one of them acting as a catalyzer, and our results predict an important catalytic effect, ranging between 3 and 11 kcal·mol(-1) when the catalytic water molecule is substituted by a sulfuric acid molecule or one of its hydrates. In these cases, the reaction products are either bare sulfuric acid dimer or sulfuric acid dimer complexed with a water molecule. There are broad implications from these new findings. The results of the present investigation show that the catalytic effect of sulfuric acid in the SO(3) hydrolysis can be important in the Earth's stratosphere, in the heterogeneous formation of sulfuric acid and in the formation of aerosols, in H(2)SO(4) formation by aircraft engines, and also in understanding the formation of sulfuric acid in the atmosphere of Venus.

  5. Hydrazides of carboxylic acids as inhibitors of steel acidic corrosion

    SciTech Connect

    Aitov, R.G.; Shein, A.B.; Lesnov, A.E.

    1994-09-01

    Hydrazides of carboxylic acids (HCA) inhibit the corrosion of ferrous materials in acids and netral solutions such as stratum and waste waters of oil deposits. In this work, the authors try to explain the above-mentioned difference and to consider HCA as inhibitors of steel hydrogenation.

  6. Fatty Acid Desaturases, Polyunsaturated Fatty Acid Regulation, and Biotechnological Advances

    PubMed Central

    Lee, Je Min; Lee, Hyungjae; Kang, SeokBeom; Park, Woo Jung

    2016-01-01

    Polyunsaturated fatty acids (PUFAs) are considered to be critical nutrients to regulate human health and development, and numerous fatty acid desaturases play key roles in synthesizing PUFAs. Given the lack of delta-12 and -15 desaturases and the low levels of conversion to PUFAs, humans must consume some omega-3 and omega-6 fatty acids in their diet. Many studies on fatty acid desaturases as well as PUFAs have shown that fatty acid desaturase genes are closely related to different human physiological conditions. Since the first front-end desaturases from cyanobacteria were cloned, numerous desaturase genes have been identified and animals and plants have been genetically engineered to produce PUFAs such as eicosapentaenoic acid and docosahexaenoic acid. Recently, a biotechnological approach has been used to develop clinical treatments for human physiological conditions, including cancers and neurogenetic disorders. Thus, understanding the functions and regulation of PUFAs associated with human health and development by using biotechnology may facilitate the engineering of more advanced PUFA production and provide new insights into the complexity of fatty acid metabolism. PMID:26742061

  7. Justification for Selecting Level A vs. Level B Personal Protective Equipment to Remediate a Room Containing Concentrated Acids, Bases and Radiological Constituents

    SciTech Connect

    Hylko, J. M.; Thompson, A. L.; Walter, J. F.; Deecke, T. A.

    2002-02-25

    Selecting the appropriate personal protective equipment (PPE) is based on providing an adequate level of employee protection relative to the task-specific conditions and hazards. PPE is categorized into four ensembles, based on the degree of protection afforded; e.g., Levels A (most restrictive), B, C, and D (least restrictive). What is often overlooked in preparing an ensemble is that the PPE itself can create significant worker hazards; i.e., the greater the level of PPE, the greater the associated risks. Furthermore, there is confusion as to whether a more ''conservative approach'' should always be taken since Level B provides the same level of respiratory protection as Level A but less skin protection. This paper summarizes the Occupational Safety and Health Administration regulations addressing Level A versus Level B, and provides justification for selecting Level B over Level A without under-protecting the employee during a particular remediation scenario. The scenario consisted of an entry team performing (1) an initial entry into a room containing concentrated acids (e.g., hydrofluoric acid), bases, and radiological constituents; (2) sampling and characterizing container contents; and (3) retrieving characterized containers. The invasive nature of the hydrofluoric acid sampling and characterization scenario created a high potential for splash, immersion, and exposure to hazardous vapors, requiring additional skin protection. The hazards associated with this scenario and the chemical nature of hydrofluoric acid provided qualitative evidence to justify Level A. Once the hydrofluoric acid was removed from the room, PPE performance was evaluated against the remaining chemical inventory. If chemical breakthrough from direct contact was not expected to occur and instrument readings confirmed the absence of any hazardous vapors, additional skin protection afforded by wearing a vapor-tight, totally-encapsulated suit was not required. Therefore, PPE performance and

  8. Effects of Acid Treatment on Dental Zirconia: An In Vitro Study.

    PubMed

    Xie, Haifeng; Shen, Shuping; Qian, Mengke; Zhang, Feimin; Chen, Chen; Tay, Franklin R

    2015-01-01

    The aim of this study was to evaluate the effects of hydrofluoric (HF) acid, acetic acid, and citric acid treatments on the physical properties and structure of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) at ambient temperature. In total, 110 bar-shaped zirconia specimens were randomly assigned to 11 groups. The specimens in the control group (C) received no surface treatment, while those in the Cage group were hydrothermally aged at 134°C and 0.2 MPa for 20 h. Ten specimens each were immersed at ambient temperature in 5% and 40% HF acid for 2 h (40HF0), 1 day (5HF1, 40HF1), and 5 days (5HF5, 40HF5), while 10 each were immersed at ambient temperature in 10% acetic acid and 20% citric acid for 7 (AC7, CI7) and 14 days (AC14, CI14). X-ray diffraction (XRD) was used to quantitatively estimate the monoclinic phase. Furthermore, flexural strength, surface roughness, and surface Vickers hardness were measured after treatment. Scanning electron microscopy (SEM) was used to characterize the surface morphology. The Cage group specimens exhibited an increased monoclinic phase and flexural strength. Furthermore, 40% HF acid immersion decreased the flexural strength and surface hardness and deteriorated the surface finish, while 5% HF acid immersion only decreased the surface hardness. All the HF acid-immersed specimens showed an etched surface texture on SEM observations, while the other groups did not. These findings suggest that the treatment of Y-TZP with 40% HF acid at ambient temperature causes potential damage, while treatment with 5% HF acid, acetic acid, and citric acid is safe.

  9. Effects of Acid Treatment on Dental Zirconia: An In Vitro Study

    PubMed Central

    Xie, Haifeng; Shen, Shuping; Qian, Mengke; Zhang, Feimin; Chen, Chen; Tay, Franklin R.

    2015-01-01

    The aim of this study was to evaluate the effects of hydrofluoric (HF) acid, acetic acid, and citric acid treatments on the physical properties and structure of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) at ambient temperature. In total, 110 bar-shaped zirconia specimens were randomly assigned to 11 groups. The specimens in the control group (C) received no surface treatment, while those in the Cage group were hydrothermally aged at 134°C and 0.2 MPa for 20 h. Ten specimens each were immersed at ambient temperature in 5% and 40% HF acid for 2 h (40HF0), 1 day (5HF1, 40HF1), and 5 days (5HF5, 40HF5), while 10 each were immersed at ambient temperature in 10% acetic acid and 20% citric acid for 7 (AC7, CI7) and 14 days (AC14, CI14). X-ray diffraction (XRD) was used to quantitatively estimate the monoclinic phase. Furthermore, flexural strength, surface roughness, and surface Vickers hardness were measured after treatment. Scanning electron microscopy (SEM) was used to characterize the surface morphology. The Cage group specimens exhibited an increased monoclinic phase and flexural strength. Furthermore, 40% HF acid immersion decreased the flexural strength and surface hardness and deteriorated the surface finish, while 5% HF acid immersion only decreased the surface hardness. All the HF acid-immersed specimens showed an etched surface texture on SEM observations, while the other groups did not. These findings suggest that the treatment of Y-TZP with 40% HF acid at ambient temperature causes potential damage, while treatment with 5% HF acid, acetic acid, and citric acid is safe. PMID:26301413

  10. A comparison of chromic acid and sulfuric acid anodizing

    NASA Technical Reports Server (NTRS)

    Danford, M. D.

    1992-01-01

    Because of federal and state mandates restricting the use of hexavalent chromium, it was deemed worthwhile to compare the corrosion protection afforded 2219-T87 aluminum alloy by both Type I chromic acid and Type II sulfuric acid anodizing per MIL-A-8625. Corrosion measurements were made on large, flat 2219-T87 aluminum alloy sheet material with an area of 1 cm(exp 2) exposed to a corrosive medium of 3.5-percent sodium chloride at pH 5.5. Both ac electrochemical impedance spectroscopy and the dc polarization resistance techniques were employed. The results clearly indicate that the corrosion protection obtained by Type II sulfuric acid anodizing is superior, and no problems should result by substituting Type II sulfuric acid anodizing for Type I chromic acid anodizing.

  11. Acid rain on Acid soil: a new perspective.

    PubMed

    Krug, E C; Frink, C R

    1983-08-01

    Acid rain is widely believed to be responsible for acidifying soil and water in areas of North America and northern Europe. However, factors commonly considered to make landscapes susceptible to acidification by acid rain are the same factors long known to strongly acidify soils through the natural processes of soil formation. Recovery from extreme and widespread careless land use has also occurred in regions undergoing acidification. There is evidence that acidification by acid rain is superimposed on long-term acidification induced by changes in land use and consequent vegetative succession. Thus, the interactions of acid rain, acid soil, and vegetation need to be carefully examined on a watershed basis in assessing benefits expected from proposed reductions in emissions of oxides of sulfur and nitrogen.

  12. Carbonic Acid Retreatment of Biomass

    SciTech Connect

    Baylor university

    2003-06-01

    This project sought to address six objectives, outlined below. The objectives were met through the completion of ten tasks. (1) Solidify the theoretical understanding of the binary CO{sub 2}/H{sub 2}O system at reaction temperatures and pressures. The thermodynamics of pH prediction have been improved to include a more rigorous treatment of non-ideal gas phases. However it was found that experimental attempts to confirm theoretical pH predictions were still off by a factor of about 1.8 pH units. Arrhenius experiments were carried out and the activation energy for carbonic acid appears to be substantially similar to sulfuric acid. Titration experiments have not yet confirmed or quantified the buffering or acid suppression effects of carbonic acid on biomass. (2) Modify the carbonic acid pretreatment severity function to include the effect of endogenous acid formation and carbonate buffering, if necessary. It was found that the existing severity functions serve adequately to account for endogenous acid production and carbonate effects. (3) Quantify the production of soluble carbohydrates at different reaction conditions and severity. Results show that carbonic acid has little effect on increasing soluble carbohydrate concentrations for pretreated aspen wood, compared to pretreatment with water alone. This appears to be connected to the release of endogenous acids by the substrate. A less acidic substrate such as corn stover would derive benefit from the use of carbonic acid. (4) Quantify the production of microbial inhibitors at selected reaction conditions and severity. It was found that the release of inhibitors was correlated to reaction severity and that carbonic acid did not appear to increase or decrease inhibition compared to pretreatment with water alone. (5) Assess the reactivity to enzymatic hydrolysis of material pretreated at selected reaction conditions and severity. Enzymatic hydrolysis rates increased with severity, but no advantage was detected for

  13. Carbonic Acid Pretreatment of Biomass

    SciTech Connect

    G. Peter van Walsum; Kemantha Jayawardhana; Damon Yourchisin; Robert McWilliams; Vanessa Castleberry

    2003-05-31

    This project sought to address six objectives, outlined below. The objectives were met through the completion of ten tasks. 1) Solidify the theoretical understanding of the binary CO2/H2O system at reaction temperatures and pressures. The thermodynamics of pH prediction have been improved to include a more rigorous treatment of non-ideal gas phases. However it was found that experimental attempts to confirm theoretical pH predictions were still off by a factor of about 1.8 pH units. Arrhenius experiments were carried out and the activation energy for carbonic acid appears to be substantially similar to sulfuric acid. Titration experiments have not yet confirmed or quantified the buffering or acid suppression effects of carbonic acid on biomass. 2) Modify the carbonic acid pretreatment severity function to include the effect of endogenous acid formation and carbonate buffering, if necessary. It was found that the existing severity functions serve adequately to account for endogenous acid production and carbonate effects. 3) Quantify the production of soluble carbohydrates at different reaction conditions and severity. Results show that carbonic acid has little effect on increasing soluble carbohydrate concentrations for pretreated aspen wood, compared to pretreatment with water alone. This appears to be connected to the release of endogenous acids by the substrate. A less acidic substrate such as corn stover would derive benefit from the use of carbonic acid. 4) Quantify the production of microbial inhibitors at selected reaction conditions and severity. It was found that the release of inhibitors was correlated to reaction severity and that carbonic acid did not appear to increase or decrease inhibition compared to pretreatment with water alone. 5) Assess the reactivity to enzymatic hydrolysis of material pretreated at selected reaction conditions and severity. Enzymatic hydrolysis rates increased with severity, but no advantage was detected for the use of carbonic

  14. Anacardic Acid, Salicylic Acid, and Oleic Acid Differentially Alter Cellular Bioenergetic Function in Breast Cancer Cells.

    PubMed

    Radde, Brandie N; Alizadeh-Rad, Negin; Price, Stephanie M; Schultz, David J; Klinge, Carolyn M

    2016-11-01

    Anacardic acid is a dietary and medicinal phytochemical that inhibits breast cancer cell proliferation and uncouples oxidative phosphorylation (OXPHOS) in isolated rat liver mitochondria. Since mitochondrial-targeted anticancer therapy (mitocans) may be useful in breast cancer, we examined the effect of anacardic acid on cellular bioenergetics and OXPHOS pathway proteins in breast cancer cells modeling progression to endocrine-independence: MCF-7 estrogen receptor α (ERα)+ endocrine-sensitive; LCC9 and LY2 ERα+, endocrine-resistant, and MDA-MB-231 triple negative breast cancer (TNBC) cells. At concentrations similar to cell proliferation IC50 s, anacardic acid reduced ATP-linked oxygen consumption rate (OCR), mitochondrial reserve capacity, and coupling efficiency while increasing proton leak, reflecting mitochondrial toxicity which was greater in MCF-7 compared to endocrine-resistant and TNBC cells. These results suggest tolerance in endocrine-resistant and TNBC cells to mitochondrial stress induced by anacardic acid. Since anacardic acid is an alkylated 2-hydroxybenzoic acid, the effects of salicylic acid (SA, 2-hydroxybenzoic acid moiety) and oleic acid (OA, monounsaturated alkyl moiety) were tested. SA inhibited whereas OA stimulated cell viability. In contrast to stimulation of basal OCR by anacardic acid (uncoupling effect), neither SA nor OA altered basal OCR- except OA inhibited basal and ATP-linked OCR, and increased ECAR, in MDA-MB-231 cells. Changes in OXPHOS proteins correlated with changes in OCR. Overall, neither the 2-hydroxybenzoic acid moiety nor the monounsaturated alky moiety of anacardic acid is solely responsible for the observed mitochondria-targeted anticancer activity in breast cancer cells and hence both moieties are required in the same molecule for the observed effects. J. Cell. Biochem. 117: 2521-2532, 2016. © 2016 Wiley Periodicals, Inc. PMID:26990649

  15. Production of Succinic Acid from Citric Acid and Related Acids by Lactobacillus Strains

    PubMed Central

    Kaneuchi, Choji; Seki, Masako; Komagata, Kazuo

    1988-01-01

    A number of Lactobacillus strains produced succinic acid in de Man-Rogosa-Sharpe broth to various extents. Among 86 fresh isolates from fermented cane molasses in Thailand, 30 strains (35%) produced succinic acid; namely, 23 of 39 Lactobacillus reuteri strains, 6 of 18 L. cellobiosus strains, and 1 of 6 unidentified strains. All of 10 L. casei subsp. casei strains, 5 L. casei subsp. rhamnosus strains, 6 L. mali strains, and 2 L. buchneri strains did not produce succinic acid. Among 58 known strains including 48 type strains of different Lactobacillus species, the strains of L. acidophilus, L. crispatus, L. jensenii, and L. parvus produced succinic acid to the same extent as the most active fresh isolates, and those of L. alimentarius, L. collinoides, L. farciminis, L. fructivorans (1 of 2 strains tested), L. malefermentans, and L. reuteri were also positive, to lesser extents. Diammonium citrate in de Man-Rogosa-Sharpe broth was determined as a precursor of the succinic acid produced. Production rates were about 70% on a molar basis with two fresh strains tested. Succinic acid was also produced from fumaric and malic acids but not from dl-isocitric, α-ketoglutaric, and pyruvic acids. The present study is considered to provide the first evidence on the production of succinic acid, an important flavoring substance in dairy products and fermented beverages, from citrate by lactobacilli. PMID:16347795

  16. Acid rain: a background report

    SciTech Connect

    Glustrom, L.; Stolzenberg, J.

    1982-07-08

    This Staff Brief was prepared for the Wisconsin Legislative Council's Special Committee on Acid Rain to provide an introduction to the issue of acid rain. It is divided into four parts. Part I provides an overview on the controversies surrounding the measurement, formation and effects of acid rain. As described in Part I, the term acid rain is used to describe the deposition of acidic components through both wet deposition (e.g., rain or snow) and dry deposition (e.g., direct contact between atmospheric constituents and the land, water or vegetation of the earth). Part II presents background information on state agency activities relating to acid rain in Wisconsin, describes what is known about the occurrence of, susceptibility to and effects of acid rain in Wisconsin, and provides information related to man-made sources of sulfur and nitrogen oxides in Wisconsin. Part III describes major policies and regulations relating to acid rain which have been or are being developed jointly by the United States and Canadian governments, by the United States government and by the State of Wisconsin. Part IV briefly discusses possible areas for Committee action.

  17. Acid Rain: An Educational Opportunity?

    ERIC Educational Resources Information Center

    Marion, James I.

    1984-01-01

    Deals with how educators can handle the subject of acid rain; illustrates suggestions with experiences of grade nine students visiting Frost Valley Environmental Education Center (Oliverea, New York) to learn scientific concepts through observation of outdoor phenomena, including a stream; and discusses acid rain, pH levels, and pollution control…

  18. Acid rain & electric utilities II

    SciTech Connect

    1997-12-31

    This document presents reports which were presented at the Acid Rain and Electric Utilities Conference. Topics include environmental issues and electric utilities; acid rain program overview; global climate change and carbon dioxide; emissions data management; compliance; emissions control; allowance and trading; nitrogen oxides; and assessment. Individual reports have been processed separately for the United States Department of Energy databases.

  19. Acid Rain: The Scientific Challenge.

    ERIC Educational Resources Information Center

    Godfrey, Paul J.

    1991-01-01

    Documents the workings and findings of the Massachusetts Acid Rain Monitoring Project, which has pooled the volunteer efforts of more than 1,000 amateur and professional scientists since 1983. Reports on the origins of air pollution, the prediction of acid rain, and its effects on both water life and land resources. (JJK)

  20. Acid Precipitation: Causes and Consequences.

    ERIC Educational Resources Information Center

    Babich, Harvey; And Others

    1980-01-01

    This article is the first of three articles in a series on the acid rain problem in recent years. Discussed are the causes of acid precipitation and its consequences for the abiotic and biotic components of the terrestrial and aquatic ecosystems, and for man-made materials. (Author/SA)

  1. Acid Rain: What's the Forecast?

    ERIC Educational Resources Information Center

    Bybee, Rodger

    1984-01-01

    Discusses various types of acid rain, considered to be a century-old problem. Topics include: wet and dry deposition, effects on a variety of environments, ecosystems subject to detrimental effects, and possible solutions to the problem. A list of recommended resources on acid rain is provided. (BC)

  2. Synthesis of pyromellitic acid esters

    NASA Technical Reports Server (NTRS)

    Fedorova, V. A.; Donchak, V. A.; Martynyuk-Lototskaya, A. N.

    1985-01-01

    The ester acids necessary for studyng the thermochemical properties of pyromellitic acid (PMK)-based peroxides were investigated. Obtaining a tetramethyl ester of a PMK was described. The mechanism of an esterification reaction is discussed, as is the complete esterification of PMK with primary alcohol.

  3. Getting Back to Basics (& Acidics)

    ERIC Educational Resources Information Center

    Rhodes, Sam

    2006-01-01

    This article describes a few novel acid-base experiments intended to introduce students to the basic concepts of acid-base chemistry and provide practical examples that apply directly to the study of biology and the human body. Important concepts such as the reaction between carbon dioxide and water, buffers and protein denaturation, are covered.…

  4. Acid Tests and Basic Fun.

    ERIC Educational Resources Information Center

    McBride, John W.

    1995-01-01

    Explores acids and bases using different indicators, such as turmeric, purple grape juice, and lichens. Because some of these indicators are not as sensitive as cabbage juice or litmus paper, determining to which acids and bases each indicator is sensitive presents an enjoyable, problem-solving challenge for students. Presents directions for…

  5. Acid rain and environmental policy

    SciTech Connect

    Jacobson, J.S.

    1981-10-01

    Various seemingly paradoxical scientific questions are posed which relate to the problem of acid rain and its effect on the environment and environmental policy. The first paradox discussed concerns the supposed increase in fossil fuel usage over the last several decades, with the resultant increases in emissions of pollutants from the combustion of fuels which cause acid rain. Despite these increases, experts do not agree on whether acidity of rain has increased in eastern North America. The second paradox concerns the effect of acid rain on vegetation. If the rain is supposedly harmful, why have some reports shown increases and others, decreases in the growth of crops and trees with the application of simulated acid rain. The third paradox concerns the effect of acid rains on fish life in lakes. If acid rain falls throughout eastern North America, why have some lakes become acid and lost fish populations while others have not. Since unequivocal answers to these scientific questions are not available, a systematic approach is needed for developing policy which can be useful for solving the problem. It appears that traditional cost-benefit analysis can not be the sole basis for decision-making, but that it will be helpful. Research needs must be identified, and the upper and lower limits for alternative strategies must be determined. 14 references, 1 table.

  6. Impacts of acid rain legislation

    SciTech Connect

    Addison, E.L.

    1983-01-01

    The author warns against hasty acid rain legislation that would involve billions of dollars and affect thousands of jobs. He recommends further study into the causes of high acidity in lakes and streams. He states that there are too many uncertainties of whether the problem would be solved by reducing sulfur dioxide emissions from coal-fired power plants. (DMC)

  7. Acid rain: effects on fish and wildlife

    SciTech Connect

    Mayer, K.S.; Multer, E.P.; Schreiber, R.K.

    1984-01-01

    The following questions concerning acid rain are discussed: what is acid rain; what causes acid rain; where do sulfur and nitrogen oxides originate; what areas in the U.S. are susceptible to acid rain; are there early warning signals of acidification to aquatic resources; how does acid rain affect fishery resources; does acid rain affect wildlife; and how can effects of acid rain be reduced.

  8. Lead-acid battery

    SciTech Connect

    Rowlette, J.J.

    1983-09-20

    A light weight lead-acid battery is disclosed having a positive terminal and a negative terminal and including one or more cells or grid stacks having a plurality of vertically stacked conductive monoplates with positive active material and negative active material deposited on alternating plates in the cell or grid stack. Electrolyte layers positioned between each monoplate are included to provide a battery cell having four sides which is capable of being electrically charged and discharged. Two vertical positive bus bars are provided on opposite sides of the battery cell for connecting the monoplates with positive active material together in parallel current conducting relation. In addition, two negative bus bars on opposite sides of the battery cell each being adjacent the positive bus bars are provided for connecting the monoplates with negative active material together in parallel current conducting relation. The positive and negative bus bars not only provide a low resistance method for connecting the plurality of conductive monoplates of their respective battery terminals but also provides support and structural strength to the battery cell structure. In addition, horizontal orientation of monoplates is provided in a vertical stacking arrangement to reduce electrolyte stratification and short circuiting due to flaking of positive and negative active materials from the monoplates.

  9. Lead-acid battery

    NASA Technical Reports Server (NTRS)

    Rowlette, John J. (Inventor)

    1983-01-01

    A light weight lead-acid battery (30) having a positive terminal (36) and a negative terminal (34) and including one or more cells or grid stacks having a plurality of vertically stacked conductive monoplates (10, 20) with positive active material and negative active material deposited on alternating plates in the cell or grid stack. Electrolyte layers (26, 28) positioned between each monoplate are included to provide a battery cell having four sides which is capable of being electrically charged and discharged. Two vertical positive bus bars (42, 43) are provided on opposite sides of the battery cell for connecting the monoplates (10) with positive active material together in parallel current conducting relation. In addition, two negative bus bars (38, 39) on opposite sides of the battery cell each being adjacent the positive bus bars are provided for connecting the monoplates (20) with negative active material together in parallel current conducting relation. The positive (42, 43) and negative (38, 39) bus bars not only provide a low resistance method for connecting the plurality of conductive monoplates of their respective battery terminals (36, 34) but also provides support and structural strength to the battery cell structure. In addition, horizontal orientation of monoplates (10, 20) is provided in a vertical stacking arrangement to reduce electrolyte stratification and short circuiting due to flaking of positive and negative active materials from the monoplates.

  10. Synthesis of higher monocarboxylic acids

    SciTech Connect

    Taikov, B.F.; Novakovskii, E.M.; Zhelkovskaya, V.P.; Shadrova, V.N.; Shcherbik, P.K.

    1981-01-01

    Brown-coal and peat waxes contain higher monocarboxylic acids, alcohols and esters of them as their main components. In view of this, considerable interest is presented by the preparation of individual compounds among those mentioned above, which is particularly important in the study of the composition and development of the optimum variants of the chemical processing of the waxes. In laboratory practice, to obtain higher monocarboxylic acids use is generally made of electrosynthesis according to Kolbe which permits unbranched higher aliphatic acids with given lengths of the hydrocarbon chain to be obtained. The aim of the present work was to synthesize higher monocarboxylic acids: arachidic, behenic, lignoceric, pentacosanoic, erotic, heptacosanoic, montanic, nonacosanoic, melissic, dotriacontanoic and tetratriacontanoic, which are present in waxes. Characteristics of synthesized acids are tabulated. 20 refs.

  11. Atmospheric dust and acid rain

    SciTech Connect

    Hedin, L.O.; Likens, G.E.

    1996-12-01

    Why is acid rain still an environmental problem in Europe and North America despite antipollution reforms? The answer really is blowing in the wind: atmospheric dust. These airborne particles can help neutralize the acids falling on forests, but dust levels are unusually low these days. In the air dust particles can neutralize acid rain. What can we do about acid rain and atmospheric dust? Suggestions range from the improbable to the feasible. One reasonable suggestion is to reduce emissions of acidic pollutants to levels that can be buffered by natural quantities of basic compounds in the atmosphere; such a goal would mean continued reductions in sulfur dioxide and nitrogen oxides, perhaps even greater than those prescribed in the 1990 Amendments to the Clean Air Act in the U.S. 5 figs.

  12. Amino acid management in cancer

    PubMed Central

    Tsun, Zhi-Yang; Possemato, Richard

    2016-01-01

    Amino acids have a dual role in cellular metabolism, as they are both the building blocks for protein synthesis and intermediate metabolites which fuel other biosynthetic reactions. Recent work has demonstrated that deregulation of both arms of amino acid management are common alterations seen in cancer. Among the most highly consumed nutrients by cancer cells are the amino acids glutamine and serine, and the biosynthetic pathways that metabolize them are required in various cancer subtypes and the object of current efforts to target cancer metabolism. Also altered in cancer are components of the machinery which sense amino acid sufficiency, nucleated by the mechanistic target of rapamycin (mTOR), a key regulator of cell growth via modulation of key processes including protein synthesis and autophagy. The precise ways in which altered amino acid management supports cellular transformation remain mostly elusive, and a fuller mechanistic understanding of these processes will be important for efforts to exploit such alterations for cancer therapy. PMID:26277542

  13. Fumaric acid production by fermentation

    PubMed Central

    Roa Engel, Carol A.; Zijlmans, Tiemen W.; van Gulik, Walter M.; van der Wielen, Luuk A. M.

    2008-01-01

    The potential of fumaric acid as a raw material in the polymer industry and the increment of cost of petroleum-based fumaric acid raises interest in fermentation processes for production of this compound from renewable resources. Although the chemical process yields 112% w/w fumaric acid from maleic anhydride and the fermentation process yields only 85% w/w from glucose, the latter raw material is three times cheaper. Besides, the fermentation fixes CO2. Production of fumaric acid by Rhizopus species and the involved metabolic pathways are reviewed. Submerged fermentation systems coupled with product recovery techniques seem to have achieved economically attractive yields and productivities. Future prospects for improvement of fumaric acid production include metabolic engineering approaches to achieve low pH fermentations. PMID:18214471

  14. Formation of acrylic acid from lactic acid in supercritical water

    SciTech Connect

    Mok, W.S.L.; Antal, M.J. Jr. ); Jones, M. Jr. )

    1989-09-15

    Supercritical (SC) water is an unusual medium in which fast and specific heterolytic reactions can be conducted at temperatures as high as 400{degree}C. In supercritical water, lactic acid decomposes into gaseous and liquid products via three primary reaction pathways. Products of the acid-catalyzed heterolytic decarbonylation pathway are carbon monoxide, water, and acetaldehyde. Products of the homolytic, decarboxylation pathway are carbon dioxide, hydrogen, and acetaldehyde. Products of the heterolytic, dehydration pathway are acrylic acid and water. The intramolecular nucleophilic displacement of the {alpha}-hydroxyl by the carbonyl group of lactic acid, producing {alpha}-propiolactone as an unstable intermediate which subsequently rearranges to become the unsaturated acid, is a likely mechanism for acrylic acid formation, although an intramolecular E2 elimination initiated by attack of the carbonyl oxygen on a methyl hydrogen cannot be ruled out. Support for the former mechanism comes in part from the observed 100% relative yield of acrylic acid from {beta}-propiolactone in SC water.

  15. Synthesis of l-(+)-Tartaric Acid from l-Ascorbic Acid via 5-Keto-d-Gluconic Acid in Grapes

    PubMed Central

    Saito, Kazumi; Kasai, Zenzaburo

    1984-01-01

    5-Keto-l-idionic acid (≡5-keto-d-gluconic acid, d-xylo-5-hexulosonic acid) was found as a metabolic product of l-ascorbic acid in slices of immature grapes, Vitis labrusca L. cv `Delaware'. Specifically labeled compounds, recognized as metabolic products of l-ascorbic acid in grapes, were fed to young grape tissues to investigate the metabolic pathway from l-ascorbic acid to l-(+)-tartaric acid. Label from dehydro-l-[1-14C]ascorbic acid, 2-keto-l-[1-14C]idonic acid (l-xylo-2-hexulosonic acid), l-[1-14C]idonic acid, or 5-keto-l-[1-14C] idonic acid was incorporated into l-(+)-tartaric acid in high yields as it was in the l-[1-14C]ascorbic acid experiment. In a double label experiment involving a mixture of l-[1-14C]idonic acid and l-[2-3H]idonic acid, the 3H/14C ratios of 5-keto-l-idonic acid and l-(+)-tartaric acid synthesized in young grape leaves were almost the same as the value of the l-idonic acid fed. Label from 5-keto-l-[6-14C]idonic acid was incorporated into sugars and insoluble residue in the same way as l-[6-14C]ascorbic acid was metabolized in grapes. These results provide strong evidence that in grapes l-(+)-tartaric acid is synthesized from the C4 fragment that corresponds to the C1 to C4 group of the 5-keto-l-idonic acid derived from l-ascorbic acid via 2-keto-l-idonic acid and l-idonic acid. PMID:16663792

  16. Molten fatty acid based microemulsions.

    PubMed

    Noirjean, Cecile; Testard, Fabienne; Dejugnat, Christophe; Jestin, Jacques; Carriere, David

    2016-06-21

    We show that ternary mixtures of water (polar phase), myristic acid (MA, apolar phase) and cetyltrimethylammonium bromide (CTAB, cationic surfactant) studied above the melting point of myristic acid allow the preparation of microemulsions without adding a salt or a co-surfactant. The combination of SANS, SAXS/WAXS, DSC, and phase diagram determination allows a complete characterization of the structures and interactions between components in the molten fatty acid based microemulsions. For the different structures characterized (microemulsion, lamellar or hexagonal phases), a similar thermal behaviour is observed for all ternary MA/CTAB/water monophasic samples and for binary MA/CTAB mixtures without water: crystalline myristic acid melts at 52 °C, and a thermal transition at 70 °C is assigned to the breaking of hydrogen bounds inside the mixed myristic acid/CTAB complex (being the surfactant film in the ternary system). Water determines the film curvature, hence the structures observed at high temperature, but does not influence the thermal behaviour of the ternary system. Myristic acid is partitioned in two "species" that behave independently: pure myristic acid and myristic acid associated with CTAB to form an equimolar complex that plays the role of the surfactant film. We therefore show that myristic acid plays the role of a solvent (oil) and a co-surfactant allowing the fine tuning of the structure of oil and water mixtures. This solvosurfactant behaviour of long chain fatty acid opens the way for new formulations with a complex structure without the addition of any extra compound. PMID:27241163

  17. Pentadecanoic and Heptadecanoic Acids: Multifaceted Odd-Chain Fatty Acids.

    PubMed

    Pfeuffer, Maria; Jaudszus, Anke

    2016-07-01

    The odd-chain fatty acids (OCFAs) pentadecanoic acid (15:0) and heptadecanoic acid (17:0), which account for only a small proportion of total saturated fatty acids in milk fat and ruminant meat, are accepted biomarkers of dairy fat intake. However, they can also be synthesized endogenously, for example, from gut-derived propionic acid (3:0). A number of studies have shown an inverse association between OCFA concentrations in human plasma phospholipids or RBCs and risk of type 2 diabetes and cardiovascular disease. We propose a possible involvement in metabolic regulation from the assumption that there is a link between 15:0 and 17:0 and the metabolism of other short-chain, medium-chain, and longer-chain OCFAs. The OCFAs 15:0 and 17:0 can be elongated to very-long-chain FAs (VLCFAs) such as tricosanoic acid (23:0) and pentacosanoic acid (25:0) in glycosphingolipids, particularly found in brain tissue, or can be derived from these VLCFAs. Their chains can be shortened, yielding propionyl-coenzyme A (CoA). Propionyl-CoA, by succinyl-CoA, can replenish the citric acid cycle (CAC) with anaplerotic intermediates and, thus, improve mitochondrial energy metabolism. Mitochondrial function is compromised in a number of disorders and may be impaired with increasing age. Optimizing anaplerotic intermediate availability for the CAC may help to cope with demands in times of increased metabolic stress and with aging. OCFAs may serve as substrates for synthesis of both odd-numbered VLCFAs and propionyl-CoA or store away excess propionic acid. PMID:27422507

  18. Pentadecanoic and Heptadecanoic Acids: Multifaceted Odd-Chain Fatty Acids.

    PubMed

    Pfeuffer, Maria; Jaudszus, Anke

    2016-07-01

    The odd-chain fatty acids (OCFAs) pentadecanoic acid (15:0) and heptadecanoic acid (17:0), which account for only a small proportion of total saturated fatty acids in milk fat and ruminant meat, are accepted biomarkers of dairy fat intake. However, they can also be synthesized endogenously, for example, from gut-derived propionic acid (3:0). A number of studies have shown an inverse association between OCFA concentrations in human plasma phospholipids or RBCs and risk of type 2 diabetes and cardiovascular disease. We propose a possible involvement in metabolic regulation from the assumption that there is a link between 15:0 and 17:0 and the metabolism of other short-chain, medium-chain, and longer-chain OCFAs. The OCFAs 15:0 and 17:0 can be elongated to very-long-chain FAs (VLCFAs) such as tricosanoic acid (23:0) and pentacosanoic acid (25:0) in glycosphingolipids, particularly found in brain tissue, or can be derived from these VLCFAs. Their chains can be shortened, yielding propionyl-coenzyme A (CoA). Propionyl-CoA, by succinyl-CoA, can replenish the citric acid cycle (CAC) with anaplerotic intermediates and, thus, improve mitochondrial energy metabolism. Mitochondrial function is compromised in a number of disorders and may be impaired with increasing age. Optimizing anaplerotic intermediate availability for the CAC may help to cope with demands in times of increased metabolic stress and with aging. OCFAs may serve as substrates for synthesis of both odd-numbered VLCFAs and propionyl-CoA or store away excess propionic acid.

  19. Acid soil and acid rain, 2nd edition

    SciTech Connect

    Kennedy, I.R.

    1992-01-01

    This book examines the basic chemical processes involved in acidification in order to better assess their long-term effects on the status of soils, the health of plants and other living species that depend on them. It also discusses acidity, pH and protons their significance in bioenergetics and the consequent role of autotrophic organisms in acidifying ecosystems. This edition incorporates and integrates recent findings that render more explanations of the causes of the environmental impacts of acidity, especially in forests and lakes. Also explores current research into acid rain and soil in order to devise appropriate measures for their amelioration.

  20. Functional nucleic acid probes and uses thereof

    DOEpatents

    Nilsen-Hamilton, Marit

    2006-10-03

    The present invention provides functional nucleic acid probes, and methods of using functional nucleic acid probes, for binding a target to carry out a desired function. The probes have at least one functional nucleic acid, at least one regulating nucleic acid, and at least one attenuator. The functional nucleic acid is maintained in an inactive state by the attenuator and activated by the regulating nucleic acid only in the presence of a regulating nucleic acid target. In its activated state the functional nucleic acid can bind to its target to carry out a desired function, such as generating a signal, cleaving a nucleic acid, or catalyzing a reaction.

  1. 21 CFR 184.1021 - Benzoic acid.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Benzoic acid. 184.1021 Section 184.1021 Food and... Substances Affirmed as GRAS § 184.1021 Benzoic acid. (a) Benzoic acid is the chemical benzenecarboxylic acid (C7H6O2), occurring in nature in free and combined forms. Among the foods in which benzoic acid...

  2. 21 CFR 184.1021 - Benzoic acid.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Benzoic acid. 184.1021 Section 184.1021 Food and... Substances Affirmed as GRAS § 184.1021 Benzoic acid. (a) Benzoic acid is the chemical benzenecarboxylic acid (C7H6O2), occurring in nature in free and combined forms. Among the foods in which benzoic acid...

  3. 21 CFR 184.1021 - Benzoic acid.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Benzoic acid. 184.1021 Section 184.1021 Food and... Substances Affirmed as GRAS § 184.1021 Benzoic acid. (a) Benzoic acid is the chemical benzenecarboxylic acid (C7H6O2), occurring in nature in free and combined forms. Among the foods in which benzoic acid...

  4. 21 CFR 184.1021 - Benzoic acid.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Benzoic acid. 184.1021 Section 184.1021 Food and....1021 Benzoic acid. (a) Benzoic acid is the chemical benzenecarboxylic acid (C7H6O2), occurring in nature in free and combined forms. Among the foods in which benzoic acid occurs naturally are...

  5. 21 CFR 189.155 - Monochloroacetic acid.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Monochloroacetic acid. 189.155 Section 189.155... Human Food § 189.155 Monochloroacetic acid. (a) Monochloroacetic acid is the chemical chloroacetic acid... in alcoholic and nonalcoholic beverages. Monochloroacetic acid is permitted in food package...

  6. Diabetes and Alpha Lipoic Acid

    PubMed Central

    Golbidi, Saeid; Badran, Mohammad; Laher, Ismail

    2011-01-01

    Diabetes mellitus is a multi-faceted metabolic disorder where there is increased oxidative stress that contributes to the pathogenesis of this debilitating disease. This has prompted several investigations into the use of antioxidants as a complementary therapeutic approach. Alpha lipoic acid, a naturally occurring dithiol compound which plays an essential role in mitochondrial bioenergetic reactions, has gained considerable attention as an antioxidant for use in managing diabetic complications. Lipoic acid quenches reactive oxygen species, chelates metal ions, and reduces the oxidized forms of other antioxidants such as vitamin C, vitamin E, and glutathione. It also boosts antioxidant defense system through Nrf-2-mediated antioxidant gene expression and by modulation of peroxisome proliferator activated receptors-regulated genes. ALA inhibits nuclear factor kappa B and activates AMPK in skeletal muscles, which in turn have a plethora of metabolic consequences. These diverse actions suggest that lipoic acid acts by multiple mechanisms, many of which have only been uncovered recently. In this review we briefly summarize the known biochemical properties of lipoic acid and then discussed the oxidative mechanisms implicated in diabetic complications and the mechanisms by which lipoic acid may ameliorate these reactions. The findings of some of the clinical trials in which lipoic acid administration has been tested in diabetic patients during the last 10 years are summarized. It appears that the clearest benefit of lipoic acid supplementation is in patients with diabetic neuropathy. PMID:22125537

  7. Cycloadditions for Studying Nucleic Acids.

    PubMed

    Kath-Schorr, Stephanie

    2016-02-01

    Cycloaddition reactions for site-specific or global modification of nucleic acids have enabled the preparation of a plethora of previously inaccessible DNA and RNA constructs for structural and functional studies on naturally occurring nucleic acids, the assembly of nucleic acid nanostructures, therapeutic applications, and recently, the development of novel aptamers. In this chapter, recent progress in nucleic acid functionalization via a range of different cycloaddition (click) chemistries is presented. At first, cycloaddition/click chemistries already used for modifying nucleic acids are summarized, ranging from the well-established copper(I)-catalyzed alkyne-azide cycloaddition reaction to copper free methods, such as the strain-promoted azide-alkyne cycloaddition, tetrazole-based photoclick chemistry and the inverse electron demand Diels-Alder cycloaddition reaction between strained alkenes and tetrazine derivatives. The subsequent sections contain selected applications of nucleic acid functionalization via click chemistry; in particular, site-specific enzymatic labeling in vitro, either via DNA and RNA recognizing enzymes or by introducing unnatural base pairs modified for click reactions. Further sections report recent progress in metabolic labeling and fluorescent detection of DNA and RNA synthesis in vivo, click nucleic acid ligation, click chemistry in nanostructure assembly and click-SELEX as a novel method for the selection of aptamers. PMID:27572987

  8. Phytic acid in green leaves.

    PubMed

    Hadi Alkarawi, H; Zotz, G

    2014-07-01

    Phytic acid or phytate, the free-acid form of myo-inositolhexakiphosphate, is abundant in many seeds and fruits, where it represents the major storage form of phosphorus. Although also known from other plant tissues, available reports on the occurrence of phytic acid, e.g. in leaves, have never been compiled, nor have they been critically reviewed. We found 45 published studies with information on phytic acid content in leaves. Phytic acid was almost always detected when studies specifically tried to detect it, and accounted for up to 98% of total P. However, we argue that such extreme values, which rival findings from storage organs, are dubious and probably result from measurement errors. Excluding these high values from further quantitative analysis, foliar phytic acid-P averaged 2.3 mg·g(-1) , and represented, on average, 7.6% of total P. Remarkably, the ratio of phytic acid-P to total P did not increase with total P, we even detected a negative correlation of the two variables within one species, Manihot esculenta. This enigmatic finding warrants further attention.

  9. Cycloadditions for Studying Nucleic Acids.

    PubMed

    Kath-Schorr, Stephanie

    2016-02-01

    Cycloaddition reactions for site-specific or global modification of nucleic acids have enabled the preparation of a plethora of previously inaccessible DNA and RNA constructs for structural and functional studies on naturally occurring nucleic acids, the assembly of nucleic acid nanostructures, therapeutic applications, and recently, the development of novel aptamers. In this chapter, recent progress in nucleic acid functionalization via a range of different cycloaddition (click) chemistries is presented. At first, cycloaddition/click chemistries already used for modifying nucleic acids are summarized, ranging from the well-established copper(I)-catalyzed alkyne-azide cycloaddition reaction to copper free methods, such as the strain-promoted azide-alkyne cycloaddition, tetrazole-based photoclick chemistry and the inverse electron demand Diels-Alder cycloaddition reaction between strained alkenes and tetrazine derivatives. The subsequent sections contain selected applications of nucleic acid functionalization via click chemistry; in particular, site-specific enzymatic labeling in vitro, either via DNA and RNA recognizing enzymes or by introducing unnatural base pairs modified for click reactions. Further sections report recent progress in metabolic labeling and fluorescent detection of DNA and RNA synthesis in vivo, click nucleic acid ligation, click chemistry in nanostructure assembly and click-SELEX as a novel method for the selection of aptamers.

  10. Terahertz spectrum of gallic acid

    NASA Astrophysics Data System (ADS)

    Wu, Meng; Zhao, Guozhong; Wang, Haiyan; Liang, Chengshen

    2009-11-01

    Gallic acid is natural polyphenol compound found in many green plants. More and more experiments have demonstrated that the gallic acid has comprehensive applications. In the field of medicine, the gallic acid plays an important role in antianaphylaxis, antineoplastic, antimycotic, anti-inflammatory, antivirotic, antiasthmatic and inhibiting the degradation of insulin. It also has a lot of applications in chemical industry, food industry and light industry. So it is important to study the terahertz time-domain spectroscopy of gallic acid. Terahertz time-domain spectroscopy (THz-TDS) is a new coherent spectral technology based on the femtosecond laser. In this work, the spectral characteristics of gallic acid in the range of 0.4 THz to 2.6 THz have been measured by THz-TDS. We obtained its absorption and refraction spectra at room temperature. The vibration absorption spectrum of the single molecule between 0.4 THz and 2.6 THz is simulated based on the Density Functional Theory (DFT). It is found that the gallic acid has the spectral response to THz wave in this frequency range. The results show the abnormal dispersion at 1.51 THz and 2.05 THz. These results can be used in the qualitative analysis of gallic acid and the medicine and food inspection.

  11. Determination of polyfluoroalkyl phosphoric acid diesters, perfluoroalkyl phosphonic acids, perfluoroalkyl phosphinic acids, perfluoroalkyl carboxylic acids, and perfluoroalkane sulfonic acids in lake trout from the Great Lakes region.

    PubMed

    Guo, Rui; Reiner, Eric J; Bhavsar, Satyendra P; Helm, Paul A; Mabury, Scott A; Braekevelt, Eric; Tittlemier, Sheryl A

    2012-11-01

    A comprehensive method to extract perfluoroalkyl carboxylic acids, perfluoroalkane sulfonic acids, perfluoroalkyl phosphonic acids, perfluoroalkyl phosphinic acids, and polyfluoroalkyl phosphoric acid diesters simultaneously from fish samples has been developed. The recoveries of target compounds ranged from 78 % to 121 %. The new method was used to analyze lake trout (Salvelinus namaycush) from the Great Lakes region. The results showed that the total perfluoroalkane sulfonate concentrations ranged from 0.1 to 145 ng/g (wet weight) with perfluorooctane sulfonate (PFOS) as the dominant contaminant. Concentrations in fish between lakes were in the order of Lakes Ontario ≈ Erie > Huron > Superior ≈ Nipigon. The total perfluoroalkyl carboxylic acid concentrations ranged from 0.2 to 18.2 ng/g wet weight. The aggregate mean perfluorooctanoic acid (PFOA) concentration in fish across all lakes was 0.045 ± 0.023 ng/g. Mean concentrations of PFOA were not significantly different (p > 0.1) among the five lakes. Perfluoroalkyl phosphinic acids were detected in lake trout from Lake Ontario, Lake Erie, and Lake Huron with concentration ranging from non-detect (ND) to 0.032 ng/g. Polyfluoroalkyl phosphoric acid diesters were detected only in lake trout from Lake Huron, at levels similar to perfluorooctanoic acid.

  12. Tropospheric cycle of nitrous acid

    NASA Astrophysics Data System (ADS)

    Harrison, Roy M.; Peak, John D.; Collins, Gareth M.

    1996-06-01

    Measurements of the land surface exchange of nitrous acid over grass and sugar beet surfaces reveal both upward and downward fluxes with flux reversal occurring at an ambient concentration of nitrogen dioxide of about 10 ppb. This confirms earlier preliminary findings and strengthens the hypothesis that substantial production of nitrous acid can occur on land surfaces from reaction of nitrogen dioxide and water vapor. Detailed measurements of nitrous acid have been made in central urban, suburban, and rural environments. These measurements, in conjunction with a simple box model, indicate that the atmospheric concentrations of nitrous acid are explicable in terms of a small number of basic processes in which the most important are the surface production of nitrous acid from nitrogen dioxide, atmospheric production from the NO-OH reaction and loss of nitrous acid by photolysis and dry deposition. In the suburban atmosphere, concentrations of nitrous acid are strongly correlated with nitrogen dioxide. In the rural atmosphere a different behavior is seen, with much higher nitrous acid to nitrogen dioxide ratios occurring in more polluted air with nitrogen dioxide concentrations in excess of 10 ppb. At lower nitrogen dioxide concentrations, net deposition of nitrous acid at the ground leads to very low concentrations in advected air. The model study indicates that during daytime in the suburban atmosphere, production of HONO from the NO-OH reaction can compete with photolysis giving a HONO concentration of a few tenths of a part per billion. At the highest observed daytime concentrations of HONO, production of OH radical from its photolysis can proceed at a rate more than 10 times faster than from photolysis of ozone.

  13. Gamma linolenic acid: an antiinflammatory omega-6 fatty acid.

    PubMed

    Kapoor, Rakesh; Huang, Yung-Sheng

    2006-12-01

    Inflammation plays an important role in health and disease. Most of the chronic diseases of modern society, including cancer, diabetes, heart disease, arthritis, Alzheimer's disease, etc. have inflammatory component. At the same time, the link between diet and disease is also being recognized. Amongst dietary constituents, fat has gained most recognition in affecting health. Saturated and trans fatty acids have been implicated in obesity, heart disease, diabetes and cancer while polyunsaturated fatty acids (PUFAs) generally have a positive effect on health. The PUFAs of omega-3 and omega-6 series play a significant role in health and disease by generating potent modulatory molecules for inflammatory responses, including eicosanoids (prostaglandins, and leukotrienes), and cytokines (interleukins) and affecting the gene expression of various bioactive molecules. Gamma linolenic acid (GLA, all cis 6, 9, 12-Octadecatrienoic acid, C18:3, n-6), is produced in the body from linoleic acid (all cis 6,9-octadecadienoic acid), an essential fatty acid of omega-6 series by the enzyme delta-6-desaturase. Preformed GLA is present in trace amounts in green leafy vegetables and in nuts. The most significant source of GLA for infants is breast milk. GLA is further metabolized to dihomogamma linlenic acid (DGLA) which undergoes oxidative metabolism by cyclooxygenases and lipoxygenases to produce anti-inflammatory eicosanoids (prostaglandins of series 1 and leukotrienes of series 3). GLA and its metabolites also affect expression of various genes where by regulating the levels of gene products including matrix proteins. These gene products play a significant role in immune functions and also in cell death (apoptosis). The present review will emphasize the role of GLA in modulating inflammatory response, and hence its potential applications as an anti-inflammatory nutrient or adjuvant.

  14. Solid acids for green chemistry.

    PubMed

    Clark, James H

    2002-09-01

    Solid acids and especially those based on micelle-templated silicas and other mesoporous high surface area support materials are beginning to play a significant role in the greening of fine and specialty chemicals manufacturing processes. A wide range of important organic reactions can be efficiently catalyzed by these materials, which can be designed to provide different types of acidity as well as high degrees of reaction selectivity. The solid acids generally have high turnover numbers and can be easily separated from the organic components. The combination of this chemistry with innovative reaction engineering offers exciting opportunities for innovative green chemical manufacturing in the future. PMID:12234209

  15. Arsanilic acid toxicity in rabbits.

    PubMed

    Confer, A W; Ward, B C; Hines, F A

    1980-04-01

    Rations from several rabbitries experiencing increased mortality, weight loss and diminished reproduction were analyzed for arsanilic acid. Levels of less than 56 ppm of arsanilic acid were found. A 30 day trial was conducted where arsanilic acid was given in doses of 1.6-16.2 mg/day in water to weanling and adult rabbits. The higher doses induced diarrhea, terminal convulsions and death. Weight loss or reduced weight gains occurred in six of seven treated groups. No significant gross or microscopic lesions were observed. Chemical analysis demonstrated the presence of increased total hepatic arsenic levels in treated compared to control rabbits.

  16. Chemiluminescent measurement of atmospheric acid

    NASA Technical Reports Server (NTRS)

    Stedman, D. H.; Kok, G. L.

    1974-01-01

    The design and construction of a gas phase acid sensitive analyzer are reported. These studies showed that the chemical system was a practical analytical method. A complete instrument was developed and prepared for field testing. A Titan 3-C rocket was scheduled for launching on February 11, 1974. Through preparations made by NASA Langley the instrument was set up to monitor the acid concentration in the rocket exhaust. Due to adverse wind conditions no acid was detected. This entire trip is described in detail.

  17. Be an acid rain detective

    SciTech Connect

    Atwill, L.

    1982-07-01

    Acid rain is discussed in a question and answer format. The article is aimed at educating sport fishermen on the subject, and also to encourage them to write their congressmen, senators, and the President about the acid rain problem. The article also announces the availability of an acid rain test kit available through the magazine, ''Sports Afield.'' The kit consists of pH-test paper that turns different shades of pink and blue according to the pH of the water tested. The color of the test paper is then compared to a color chart furnished in the kit and an approximate pH can be determined.

  18. Decarboxylative functionalization of cinnamic acids.

    PubMed

    Borah, Arun Jyoti; Yan, Guobing

    2015-08-14

    Decarboxylative functionalization of α,β-unsaturated carboxylic acids is an emerging area that has been developed significantly in recent years. This critical review focuses on the different decarboxylative functionalization reactions of cinnamic acids leading to the formation of various C-C and C-heteroatom bonds. Apart from metal carboxylates, decarboxylation in cinnamic acids has been achieved efficiently under metal-free conditions, particularly via the use of hypervalent iodine reagents. We believe this review will encourage organic chemists to develop vinylic decarboxylation in a more appealing way with an understanding of new mechanistic insight.

  19. PRODUCTION OF TRIFLUOROACETIC ACID COMPOUNDS

    DOEpatents

    Haworth, W.N.; Stacey, M.

    1949-08-30

    A process is described for the preparation of trifluoroacetic acid. Acetone vapor diluted wlth nitrogen and fluorine also diluted with nltrogen are fed separately at a temperature of about 210 deg C into a reaction vessel containing a catalyst mass selected from-the group consisting of silver and gold. The temperature in the reaction vessel is maintained in the range of 200 deg to 250 deg C. The reaction product, trifluoroacetyl fluoride, is absorbed in aqueous alkali solution. Trifluoroacetic acid is recovered from the solution by acidification wlth an acid such as sulfuric followed by steam distillation.

  20. Acid rain: chemistry and transport.

    PubMed

    Irwin, J G; Williams, M L

    1988-01-01

    This review describes the more important features of the emission, chemistry, transport and deposition of pollutants involved in acid deposition. Global emissions, both natural and man-made, of sulphur and nitrogen oxides are discussed and examples of spatial distributions and trends over the last century presented. The more significant chemical and physical processes involved in the transformation of the primary emissions into their acidic end products are described, including a summary of the approximate timescales of the processes involved. Measurements and modelled calculations of spatial and temporal patterns in the deposition of acidic pollutants by both wet and dry pathways are presented.

  1. Free acidity measurement - a review.

    PubMed

    Srinivasan, T G; Vasudeva Rao, P R

    2014-01-01

    Free acidity is an important parameter especially in the presence of hydrolysable ions. Several methods have been developed for the determination of free acidity, attributing due importance to the accuracy and the precision of the measurement with the aim of the easiness of the methodology as well as post-measurement recovery in mind. This review covers important methods for the determination of free acidity with emphasis on actinide containing solutions, reported in the literature over the past several decades classifying them into different categories.

  2. Amino Acids from a Comet

    NASA Technical Reports Server (NTRS)

    Cook, Jamie Elisla

    2009-01-01

    NASA's Stardust spacecraft returned samples from comet 81P/Wild 2 to Earth in January 2006. Examinations of the organic compounds in cometary samples can reveal information about the prebiotic organic inventory present on the early Earth and within the early Solar System, which may have contributed to the origin of life. Preliminary studies of Stardust material revealed the presence of a suite of organic compounds including several amines and amino acids, but the origin of these compounds (cometary- vs. terrestrial contamination) could not be identified. We have recently measured the carbon isotopic ratios of these amino acids to determine their origin, leading to the first detection of a coetary amino acid.

  3. Can crops tolerate acid rain

    SciTech Connect

    Kaplan, J.K.

    1989-11-01

    This brief article describes work by scientists at the ARS Air Quality-Plant Growth and Development Laboratory in Raleigh, North Carolina, that indicates little damage to crops as a result of acid rain. In studies with simulated acid rain and 216 exposed varieties of 18 crops, there were no significant injuries nor was there reduced growth in most species. Results of chronic and acute exposures were correlated in sensitive tomato and soybean plants and in tolerant winter wheat and lettuce plants. These results suggest that 1-hour exposures could be used in the future to screen varieties for sensitivity to acid rain.

  4. 40 CFR 721.10679 - Carboxylic acid, substituted alkylstannylene ester, reaction products with inorganic acid tetra...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... alkylstannylene ester, reaction products with inorganic acid tetra alkyl ester (generic). 721.10679 Section 721... Carboxylic acid, substituted alkylstannylene ester, reaction products with inorganic acid tetra alkyl ester... identified generically as carboxylic acid, substituted alkylstannylene ester, reaction products...

  5. Treatment of Amino Acid Metabolism Disorders

    MedlinePlus

    ... Treatment of amino acid metabolism disorders Treatment of amino acid metabolism disorders E-mail to a friend Please ... this page It's been added to your dashboard . Amino acid metabolism disorders are rare health conditions that affect ...

  6. Acid preservation systems for food products

    SciTech Connect

    Tiberio, J. E.; Cirigiano, M. C.

    1984-10-16

    Fumaric acid is used in combination with critical amounts of acetic acid to preserve acid containing food products from microbiological spoilage in the absence of or at reduced levels of chemical preservative.

  7. Genetics Home Reference: sialic acid storage disease

    MedlinePlus

    ... Home Health Conditions sialic acid storage disease sialic acid storage disease Enable Javascript to view the expand/ ... Download PDF Open All Close All Description Sialic acid storage disease is an inherited disorder that primarily ...

  8. Treatment of Fatty Acid Oxidation Disorders

    MedlinePlus

    ... of fatty acid oxidation disorders Treatment of fatty acid oxidation disorders E-mail to a friend Please ... page It's been added to your dashboard . Fatty acid oxidation disorders are rare health conditions that affect ...

  9. Molar extinction coefficients of some fatty acids

    NASA Astrophysics Data System (ADS)

    Sandhu, G. K.; Singh, Kulwant; Lark, B. S.; Gerward, L.

    2002-10-01

    The attenuation of gamma rays in some fatty acids, viz. formic acid (CH 2O 2), acetic acid (C 2H 4O 2), propionic acid (C 3H 6O 2), butyric acid (C 4H 8O 2), n-hexanoic acid (C 6H 12O 2), n-caprylic acid (C 8H 16O 2), lauric acid (C 12H 24O 2), myristic acid (C 14H 28O 2), palmitic acid (C 16H 32O 2), oleic acid (C 18H 34O 2) and stearic acid (C 18H 36O 2), has been measured at the photon energies 81, 356, 511, 662, 1173 and 1332 keV. Experimental values for the molar extinction coefficient, the effective atomic number and the electron density have been derived and compared with theoretical calculations. There is good agreement between experiment and theory.

  10. Biotechnological production of citric acid

    PubMed Central

    Max, Belén; Salgado, José Manuel; Rodríguez, Noelia; Cortés, Sandra; Converti, Attilio; Domínguez, José Manuel

    2010-01-01

    This work provides a review about the biotechnological production of citric acid starting from the physicochemical properties and industrial applications, mainly in the food and pharmaceutical sectors. Several factors affecting citric acid fermentation are discussed, including carbon source, nitrogen and phosphate limitations, pH of culture medium, aeration, trace elements and morphology of the fungus. Special attention is paid to the fundamentals of biochemistry and accumulation of citric acid. Technologies employed at industrial scale such as surface or submerged cultures, mainly employing Aspergillus niger, and processes carried out with Yarrowia lipolytica, as well as the technology for recovering the product are also described. Finally, this review summarizes the use of orange peels and other by-products as feedstocks for the bioproduction of citric acid. PMID:24031566

  11. Simulated acid rain on crops

    SciTech Connect

    Plocher, M.D.; Perrigan, S.C.; Hevel, R.J.; Cooper, R.M.; Moss, D.N.

    1985-10-01

    In 1981, simulated H/sub 2/SO/sub 4/ acid rain was applied to alfalfa and tall fescue and a 2:1 ratio of H/sub 2/SO/sub 4/:HNO/sub 3/ acid rain was applied to alfalfa, tall fescue, barley, wheat, potato, tomato, radish, and corn crops growing in the open field at Corvallis, Oregon. Careful attention was given to effects of the acid rain on the appearance of the foliage, and the effects on yield were measured. Because the effect of pH 4.0 rain on corn yield was the only significant effect noted in the 1981 studies, in 1982, more-extensive studies of the effect of simulated H/sub 2/SO/sub 4//HNO/sub 3/ rain on corn were conducted. No significant effects of acid rain were found on foliage appearance, or on yield of grain or stover in the 1982 studies.

  12. Low acid producing solid propellants

    NASA Technical Reports Server (NTRS)

    Bennett, Robert R.

    1995-01-01

    The potential environmental effects of the exhaust products of conventional rocket propellants have been assessed by various groups. Areas of concern have included stratospheric ozone, acid rain, toxicity, air quality and global warming. Some of the studies which have been performed on this subject have concluded that while the impacts of rocket use are extremely small, there are propellant development options which have the potential to reduce those impacts even further. This paper discusses the various solid propellant options which have been proposed as being more environmentally benign than current systems by reducing HCI emissions. These options include acid neutralized, acid scavenged, and nonchlorine propellants. An assessment of the acid reducing potential and the viability of each of these options is made, based on current information. Such an assessment is needed in order to judge whether the potential improvements justify the expenditures of developing the new propellant systems.

  13. Abiotic synthesis of fatty acids

    NASA Technical Reports Server (NTRS)

    Leach, W. W.; Nooner, D. W.; Oro, J.

    1978-01-01

    The formation of fatty acids by Fischer-Tropsch-type synthesis was investigated with ferric oxide, ammonium carbonate, potassium carbonate, powdered Pueblito de Allende carbonaceous chondrite, and filings from the Canyon Diablo meteorite used as catalysts. Products were separated and identified by gas chromatography and mass spectrometry. Iron oxide, Pueblito de Allende chondrite, and Canyon Diablo filings in an oxidized catalyst form yielded no fatty acids. Canyon Diablo filings heated overnight at 500 C while undergoing slow purging by deuterium produced fatty acids only when potassium carbonate was admixed; potassium carbonate alone also produced these compounds. The active catalytic combinations gave relatively high yields of aliphatic and aromatic hydrocarbons; substantial amounts of n-alkenes were almost invariably observed when fatty acids were produced; the latter were in the range C6 to C18, with maximum yield in C9 or 10.

  14. Biopreservation by lactic acid bacteria.

    PubMed

    Stiles, M E

    1996-10-01

    Biopreservation refers to extended storage life and enhanced safety of foods using the natural microflora and (or) their antibacterial products. Lactic acid bacteria have a major potential for use in biopreservation because they are safe to consume and during storage they naturally dominate the microflora of many foods. In milk, brined vegetables, many cereal products and meats with added carbohydrate, the growth of lactic acid bacteria produces a new food product. In raw meats and fish that are chill stored under vacuum or in an environment with elevated carbon dioxide concentration, the lactic acid bacteria become the dominant population and preserve the meat with a "hidden' fermentation. The same applies to processed meats provided that the lactic acid bacteria survive the heat treatment or they are inoculated onto the product after heat treatment. This paper reviews the current status and potential for controlled biopreservation of foods. PMID:8879414

  15. Phosphonic acid based exchange resins

    DOEpatents

    Horwitz, E.P.; Alexandratos, S.D.; Gatrone, R.C.; Chiarizia, R.

    1995-09-12

    An ion exchange resin is described for extracting metal ions from a liquid waste stream. An ion exchange resin is prepared by copolymerizing a vinylidene diphosphonic acid with styrene, acrylonitrile and divinylbenzene. 10 figs.

  16. Lead/acid battery myths

    NASA Astrophysics Data System (ADS)

    Moseley, P. T.

    The lead/acid battery deserves a more positive image than has been traditional heretofore—particularly with respect to a number of aspects that relate to its utility as a power source for electric vehicles. Recent results from a large internationally coordinated research programme indicate that: (i) with proper attention to construction, valve-regulated lead/acid batteries can be deep-discharged many times without capacity loss; (ii) lead/acid batteries can be recharged extremely rapidly so that long journeys of electric vehicles become a realistic possibility; (iii) ranges of over 150 km between charges are achievable, and (iv) the introduction of significant numbers of lead/acid-powered electric vehicles does offer a beneficial environmental impact.

  17. Making cents of acid recovery

    SciTech Connect

    Ondrey, G.; Shanley, A.

    1993-04-01

    Acid recovery may be expensive, but rising transportation and landfill costs may soon make it the only alternative. Traditionally, acids used in processes from titanium dioxide production to gasoline alkylation and metal pickling were neutralized and discharged into waterways or injected into deep wells. Today, however, discharge permits are being phased out in many countries, and deep well injection is coming under closer scrutiny. An even cheaper option was selling spent acid to fertilizer producers, who used it to dissolve phosphate ores. Health concerns, a depressed fertilizer market and tightening disposal regulations for gypsum byproduct have dried up this option. The paper discusses the processes and costs involved in spent acid regeneration, gypsum-free gas treatments, and problems with explosive contaminants.

  18. Glucaric acids from Leonurus japonicus.

    PubMed

    Jiang, Jianshuang; Li, Yixiu; Feng, Ziming; Yang, Yanan; Zhang, Peicheng

    2015-12-01

    Three new glucaric acids, namely 2-feruloyl-4-syringoyl or 5-feruloyl-3-syringoyl glucaric acid (1), 2-syringoyl-4-feruloyl or 5-syringoyl-3-feruloyl glucaric acid (2), and 3-feruloyl-4-syringoyl or 4-feruloyl-3-syringoyl glucaric acid (3), were isolated from Leonurus japonicus Houtt. Their structures were elucidated by detailed spectroscopic means including UV, IR, HR-ESI-MS, 1D and 2D NMR data spectra. The bioactive assays of compounds 1-3 against hepatoprotection activity were determined. The result suggested that compound 2 exhibited a moderate hepatoprotection activity and the cell survival rate was 74% (10(-5)mol/L), using bicyclol (survival rate: 66%, 10(-5)mol/L) as a positive control. Furthermore, compounds 1-3 were evaluated cytotoxic activities in vitro using HCT-8, Bel-7402, BGC-823, A-549, and A2780 model and the results exhibited no obvious cytotoxicity activity.

  19. Biopreservation by lactic acid bacteria.

    PubMed

    Stiles, M E

    1996-10-01

    Biopreservation refers to extended storage life and enhanced safety of foods using the natural microflora and (or) their antibacterial products. Lactic acid bacteria have a major potential for use in biopreservation because they are safe to consume and during storage they naturally dominate the microflora of many foods. In milk, brined vegetables, many cereal products and meats with added carbohydrate, the growth of lactic acid bacteria produces a new food product. In raw meats and fish that are chill stored under vacuum or in an environment with elevated carbon dioxide concentration, the lactic acid bacteria become the dominant population and preserve the meat with a "hidden' fermentation. The same applies to processed meats provided that the lactic acid bacteria survive the heat treatment or they are inoculated onto the product after heat treatment. This paper reviews the current status and potential for controlled biopreservation of foods.

  20. Microbial production of lactic acid.

    PubMed

    Eiteman, Mark A; Ramalingam, Subramanian

    2015-05-01

    Lactic acid is an important commodity chemical having a wide range of applications. Microbial production effectively competes with chemical synthesis methods because biochemical synthesis permits the generation of either one of the two enantiomers with high optical purity at high yield and titer, a result which is particularly beneficial for the production of poly(lactic acid) polymers having specific properties. The commercial viability of microbial lactic acid production relies on utilization of inexpensive carbon substrates derived from agricultural or waste resources. Therefore, optimal lactic acid formation requires an understanding and engineering of both the competing pathways involved in carbohydrate metabolism, as well as pathways leading to potential by-products which both affect product yield. Recent research leverages those biochemical pathways, while researchers also continue to seek strains with improved tolerance and ability to perform under desirable industrial conditions, for example, of pH and temperature.

  1. Phosphonic acid based exchange resins

    DOEpatents

    Horwitz, E. Philip; Alexandratos, Spiro D.; Gatrone, Ralph C.; Chiarizia, Ronato

    1995-01-01

    An ion exchange resin for extracting metal ions from a liquid waste stream. An ion exchange resin is prepared by copolymerizing a vinylidene diphosphonic acid with styrene, acrylonitrile and divinylbenzene.

  2. 21 CFR 184.1009 - Adipic acid.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Adipic acid. 184.1009 Section 184.1009 Food and... Substances Affirmed as GRAS § 184.1009 Adipic acid. (a) Adipic acid (C6H10O4, CAS Reg. No. 00124-04-9) is also known as 1,4-butanedicarboxylic acid or hexane-dioic acid. It is prepared by nitric acid...

  3. 21 CFR 184.1009 - Adipic acid.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Adipic acid. 184.1009 Section 184.1009 Food and... Substances Affirmed as GRAS § 184.1009 Adipic acid. (a) Adipic acid (C6H10O4, CAS Reg. No. 00124-04-9) is also known as 1,4-butanedicarboxylic acid or hexane-dioic acid. It is prepared by nitric acid...

  4. 21 CFR 184.1091 - Succinic acid.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Succinic acid. 184.1091 Section 184.1091 Food and... Substances Affirmed as GRAS § 184.1091 Succinic acid. (a) Succinic acid (C4H6O4, CAS Reg. No. 110-15-6), also referred to as amber acid and ethylenesuccinic acid, is the chemical 1,4-butanedioic acid. It...

  5. 21 CFR 184.1091 - Succinic acid.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Succinic acid. 184.1091 Section 184.1091 Food and....1091 Succinic acid. (a) Succinic acid (C4H6O4, CAS Reg. No. 110-15-6), also referred to as amber acid and ethylenesuccinic acid, is the chemical 1,4-butanedioic acid. It is commercially prepared...

  6. 21 CFR 184.1009 - Adipic acid.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Adipic acid. 184.1009 Section 184.1009 Food and... Substances Affirmed as GRAS § 184.1009 Adipic acid. (a) Adipic acid (C6H10O4, CAS Reg. No. 00124-04-9) is also known as 1,4-butanedicarboxylic acid or hexane-dioic acid. It is prepared by nitric acid...

  7. 21 CFR 184.1091 - Succinic acid.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Succinic acid. 184.1091 Section 184.1091 Food and... Substances Affirmed as GRAS § 184.1091 Succinic acid. (a) Succinic acid (C4H6O4, CAS Reg. No. 110-15-6), also referred to as amber acid and ethylenesuccinic acid, is the chemical 1,4-butanedioic acid. It...

  8. 21 CFR 184.1009 - Adipic acid.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Adipic acid. 184.1009 Section 184.1009 Food and... Substances Affirmed as GRAS § 184.1009 Adipic acid. (a) Adipic acid (C6H10O4, CAS Reg. No. 00124-04-9) is also known as 1,4-butanedicarboxylic acid or hexane-dioic acid. It is prepared by nitric acid...

  9. 21 CFR 184.1091 - Succinic acid.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Succinic acid. 184.1091 Section 184.1091 Food and... Substances Affirmed as GRAS § 184.1091 Succinic acid. (a) Succinic acid (C4H6O4, CAS Reg. No. 110-15-6), also referred to as amber acid and ethylenesuccinic acid, is the chemical 1,4-butanedioic acid. It...

  10. 21 CFR 184.1091 - Succinic acid.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Succinic acid. 184.1091 Section 184.1091 Food and... Substances Affirmed as GRAS § 184.1091 Succinic acid. (a) Succinic acid (C4H6O4, CAS Reg. No. 110-15-6), also referred to as amber acid and ethylenesuccinic acid, is the chemical 1,4-butanedioic acid. It...

  11. 21 CFR 184.1009 - Adipic acid.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Adipic acid. 184.1009 Section 184.1009 Food and....1009 Adipic acid. (a) Adipic acid (C6H10O4, CAS Reg. No. 00124-04-9) is also known as 1,4-butanedicarboxylic acid or hexane-dioic acid. It is prepared by nitric acid oxidation of cyclohexanol...

  12. Nucleic acid arrays and methods of synthesis

    DOEpatents

    Sabanayagam, Chandran R.; Sano, Takeshi; Misasi, John; Hatch, Anson; Cantor, Charles

    2001-01-01

    The present invention generally relates to high density nucleic acid arrays and methods of synthesizing nucleic acid sequences on a solid surface. Specifically, the present invention contemplates the use of stabilized nucleic acid primer sequences immobilized on solid surfaces, and circular nucleic acid sequence templates combined with the use of isothermal rolling circle amplification to thereby increase nucleic acid sequence concentrations in a sample or on an array of nucleic acid sequences.

  13. 21 CFR 172.862 - Oleic acid derived from tall oil fatty acids.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Oleic acid derived from tall oil fatty acids. 172... FOOD FOR HUMAN CONSUMPTION Multipurpose Additives § 172.862 Oleic acid derived from tall oil fatty acids. The food additive oleic acid derived from tall oil fatty acids may be safely used in food and...

  14. 21 CFR 172.862 - Oleic acid derived from tall oil fatty acids.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Oleic acid derived from tall oil fatty acids. 172... FOOD FOR HUMAN CONSUMPTION Multipurpose Additives § 172.862 Oleic acid derived from tall oil fatty acids. The food additive oleic acid derived from tall oil fatty acids may be safely used in food and...

  15. 21 CFR 172.862 - Oleic acid derived from tall oil fatty acids.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Oleic acid derived from tall oil fatty acids. 172... FOOD FOR HUMAN CONSUMPTION Multipurpose Additives § 172.862 Oleic acid derived from tall oil fatty acids. The food additive oleic acid derived from tall oil fatty acids may be safely used in food and...

  16. 40 CFR 721.10512 - Fatty acid maleic acid amides (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Fatty acid maleic acid amides (generic... Specific Chemical Substances § 721.10512 Fatty acid maleic acid amides (generic). (a) Chemical substance... fatty acid maleic acid amides (PMNs P-07-563 and P-07-564) are subject to reporting under this...

  17. 40 CFR 721.10512 - Fatty acid maleic acid amides (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Fatty acid maleic acid amides (generic... Specific Chemical Substances § 721.10512 Fatty acid maleic acid amides (generic). (a) Chemical substance... fatty acid maleic acid amides (PMNs P-07-563 and P-07-564) are subject to reporting under this...

  18. 21 CFR 172.350 - Fumaric acid and salts of fumaric acid.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Fumaric acid and salts of fumaric acid. 172.350... Nutritional Additives § 172.350 Fumaric acid and salts of fumaric acid. Fumaric acid and its calcium, ferrous... prescribed conditions: (a) The additives meet the following specifications: (1) Fumaric acid contains...

  19. 21 CFR 172.862 - Oleic acid derived from tall oil fatty acids.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Oleic acid derived from tall oil fatty acids. 172... FOOD FOR HUMAN CONSUMPTION Multipurpose Additives § 172.862 Oleic acid derived from tall oil fatty acids. The food additive oleic acid derived from tall oil fatty acids may be safely used in food and...

  20. Bile acids as metabolic regulators

    PubMed Central

    Li, Tiangang; Chiang, John Y. L.

    2015-01-01

    Summary Small molecule ligands that target to TGR5 and FXR have shown promise in treating various metabolic and inflammation-related human diseases. New insights into the mechanisms underlying the bariatric surgery and bile acid sequestrant treatment suggest that targeting the enterohepatic circulation to modulate gut-liver bile acid signaling, incretin production and microbiota represents a new strategy to treat obesity and type-2 diabetes. PMID:25584736

  1. Aqueous Photochemistry of Glyoxylic Acid.

    PubMed

    Eugene, Alexis J; Xia, Sha-Sha; Guzman, Marcelo I

    2016-06-01

    Aerosols affect climate change, the energy balance of the atmosphere, and public health due to their variable chemical composition, size, and shape. While the formation of secondary organic aerosols (SOA) from gas phase precursors is relatively well understood, studying aqueous chemical reactions contributing to the total SOA budget is the current focus of major attention. Field measurements have revealed that mono-, di-, and oxo-carboxylic acids are abundant species present in SOA and atmospheric waters. This work explores the fate of one of these 2-oxocarboxylic acids, glyoxylic acid, which can photogenerate reactive species under solar irradiation. Additionally, the dark thermal aging of photoproducts is studied by UV-visible and fluorescence spectroscopies to reveal that the optical properties are altered by the glyoxal produced. The optical properties display periodicity in the time domain of the UV-visible spectrum of chromophores with absorption enhancement (thermochromism) or loss (photobleaching) during nighttime and daytime cycles, respectively. During irradiation, excited state glyoxylic acid can undergo α-cleavage or participate in hydrogen abstractions. The use of (13)C nuclear magnetic resonance spectroscopy (NMR) analysis shows that glyoxal is an important intermediate produced during direct photolysis. Glyoxal quickly reaches a quasi-steady state as confirmed by UHPLC-MS analysis of its corresponding (E) and (Z) 2,4-dinitrophenylhydrazones. The homolytic cleavage of glyoxylic acid is proposed as a fundamental step for the production of glyoxal. Both carbon oxides, CO2(g) and CO(g) evolving to the gas-phase, are quantified by FTIR spectroscopy. Finally, formic acid, oxalic acid, and tartaric acid photoproducts are identified by ion chromatography (IC) with conductivity and electrospray (ESI) mass spectrometry (MS) detection and (1)H NMR spectroscopy. A reaction mechanism is proposed based on all experimental observations. PMID:27192089

  2. [Bile acids in coronary arteriosclerosis].

    PubMed

    Malaia, L T; Shelest, A N; Volkov, V I; Cherevatov, B G

    1984-10-01

    Seventy-six patients with chronic coronary heart disease of the atherosclerotic genesis were examined using clinical laboratory and instrumental research methods. The blood serum levels of total cholesterol, triglycerides, lipoproteins and bile acids were measured throughout the course of treatment. When hyperlipoproteinemias were divided according to phenotypes, type II hyperlipoproteinemia proved to be most commonly occurring (65.8%). The patients exhibited lower blood serum levels of bile acids as compared to control.

  3. Alternative to Nitric Acid Passivation

    NASA Technical Reports Server (NTRS)

    Kessel, Kurt R.

    2016-01-01

    Corrosion is an extensive problem that affects the National Aeronautics and Space Administration (NASA) and European Space Agency (ESA). The deleterious effects of corrosion result in steep costs, asset downtime affecting mission readiness, and safety risks to personnel. It is vital to reduce corrosion costs and risks in a sustainable manner. The primary objective of this effort is to qualify citric acid as an environmentally-preferable alternative to nitric acid for passivation of stainless steel alloys.

  4. FURNACE INJECTION OF ALKALINE SORBENTS FOR SULFURIC ACID CONTROL

    SciTech Connect

    Gary M. Blythe

    2001-11-06

    This document summarizes progress on Cooperative Agreement DE-FC26-99FT40718, Furnace Injection of Alkaline Sorbents for Sulfuric Acid Control, during the time period April 1, 2001 through September 30, 2001. The objective of this project is to demonstrate the use of alkaline reagents injected into the furnace of coal-fired boilers as a means of controlling sulfuric acid emissions. The coincident removal of hydrochloric acid and hydrofluoric acid is also being determined, as is the removal of arsenic, a known poison for NO{sub x} selective catalytic reduction (SCR) catalysts. EPRI, the Tennessee Valley Authority (TVA), FirstEnergy Corporation, and the Dravo Lime Company are project co-funders. URS Corporation is the prime contractor. During the current period, American Electric Power (AEP) joined the project as an additional co-funder and as a provider of a host site for testing. This is the fourth reporting period for the subject Cooperative Agreement. During this period, two long-term sorbent injection tests were conducted, one on Unit 3 at FirstEnergy's Bruce Mansfield Plant (BMP) and one on Unit 1 at AEP's Gavin Station. These tests determined the effectiveness of injecting alkaline slurries into the upper furnace of the boiler as a means of controlling sulfuric acid emissions from these units. The alkaline slurries tested included commercially available magnesium hydroxide slurry (Gavin Station), and a byproduct magnesium hydroxide slurry (both Gavin Station and BMP). The tests showed that injecting either the commercial or the byproduct magnesium hydroxide slurry could achieve up to 70 to 75% sulfuric acid removal. At BMP, the overall removal was limited by the need to maintain acceptable electrostatic precipitator (ESP) particulate control performance. At Gavin Station, the overall sulfuric acid removal was limited because the furnace injected sorbent was less effective at removing SO{sub 3} formed across the SCR system installed on the unit for NO{sub x

  5. FURNACE INJECTION OF ALKALINE SORBENTS FOR SULFURIC ACID CONTROL

    SciTech Connect

    Gary M. Blythe

    2002-04-29

    This document summarizes progress on Cooperative Agreement DE-FC26-99FT40718, Furnace Injection of Alkaline Sorbents for Sulfuric Acid Control, during the time period October 1, 2001 through March 31, 2002. The objective of this project is to demonstrate the use of alkaline reagents injected into the furnace of coal-fired boilers as a means of controlling sulfuric acid emissions. The coincident removal of hydrochloric acid and hydrofluoric acid is also being determined, as is the removal of arsenic, a known poison for NO{sub X} selective catalytic reduction (SCR) catalysts. EPRI, the Tennessee Valley Authority (TVA), FirstEnergy Corporation, American Electric Power (AEP) and the Dravo Lime Company are project co-funders. URS Corporation is the prime contractor. This is the fifth reporting period for the subject Cooperative Agreement. During the previous (fourth) period, two long-term sorbent injection tests were conducted, one on Unit 3 at FirstEnergy's Bruce Mansfield Plant (BMP) and one on Unit 1 at AEP's Gavin Plant. Those tests determined the effectiveness of injecting alkaline slurries into the upper furnace of the boiler as a means of controlling sulfuric acid emissions from these units. The alkaline slurries tested included commercially available magnesium hydroxide slurry (Gavin Plant) and a byproduct magnesium hydroxide slurry (at both Gavin and BMP). The tests showed that injecting either the commercial or the byproduct magnesium hydroxide slurry could achieve up to 70-75% overall sulfuric acid removal. At BMP, the overall removal was limited by the need to maintain acceptable electrostatic precipitator (ESP) particulate control performance. At Gavin Plant, the overall sulfuric acid removal was limited because the furnace injected sorbent was less effective at removing SO{sub 3} formed across the SCR system installed on the unit for NO{sub X} control than at removing SO{sub 3} formed in the furnace. The SO{sub 3} removal results were presented in the

  6. Photodissociation dynamics of hydroxybenzoic acids

    SciTech Connect

    Yang Yilin; Dyakov, Yuri; Lee, Y. T.; Ni, Chi-Kung; Sun Yilun; Hu Weiping

    2011-01-21

    Aromatic amino acids have large UV absorption cross-sections and low fluorescence quantum yields. Ultrafast internal conversion, which transforms electronic excitation energy to vibrational energy, was assumed to account for the photostability of amino acids. Recent theoretical and experimental investigations suggested that low fluorescence quantum yields of phenol (chromophore of tyrosine) are due to the dissociation from a repulsive excited state. Radicals generated from dissociation may undergo undesired reactions. It contradicts the observed photostability of amino acids. In this work, we explored the photodissociation dynamics of the tyrosine chromophores, 2-, 3- and 4-hydroxybenzoic acid in a molecular beam at 193 nm using multimass ion imaging techniques. We demonstrated that dissociation from the excited state is effectively quenched for the conformers of hydroxybenzoic acids with intramolecular hydrogen bonding. Ab initio calculations show that the excited state and the ground state potential energy surfaces change significantly for the conformers with intramolecular hydrogen bonding. It shows the importance of intramolecular hydrogen bond in the excited state dynamics and provides an alternative molecular mechanism for the photostability of aromatic amino acids upon irradiation of ultraviolet photons.

  7. Lactic acid utilization by the cutaneous Micrococcaceae.

    PubMed

    Smith, R F

    1971-04-01

    Human cutaneous staphylococci and micrococci utilized lactic acid as an energy source on a minimal medium. Propionic acid was not utilized, but l(+)-lactic acid and pyruvic acid could replace ld-lactic acid as a substrate. Selected strains of cocci were inhibited more by the l(+) and d(-) forms of lactic acid than the balanced ld form, particularly at pH 5.6. With proper dilution of substrate, lactic acid was utilized by selected strains in the presence of 10 mug of oleic and palmitic acids per ml.

  8. [On the phenolic acids of vegetables. IV. Hydroxycinnamic acids and hydroxybenzoic acids of vegetables and potatoes (author's transl)].

    PubMed

    Schmidtlein, H; Herrmann, K

    1975-12-16

    Lettuce, endive and chicory exclusively, cornsalad and sweet fennel almost exclusively contain caffeic acid derivatives beside traces of ferulic acid. Parsley exclusively and spinach almost exclusively show p-coumaric acid derivatives. Compared to root, fruit and seed vegetables the contents of phenolic acids in green leaves are considerably high. Rhubarb is the only vegetable, which contains gallic acid (chief phenolic acid) beside hydroxycinnamic, protocatechuic and vanillic acid derivatives. Furthermore hydroxybenzoic acid derivatives (salicylic, gentisic and vanillic acid) occur in cornsalad, sweet fennel, parsley and spinach in small concentrations; cornsalad shows p-hydroxybenzoic acid (ca. 20 mg/kg). Onions (Allium cepa) contain almost only protocatechuic acid beside small amounts of p-hydroxybenzoic and vanillic acid. In the outer dry coloured skins protocatechuic acid reaches concentrations up to 2% of plant material; the internal pulpy tissues show lower concentrations (ca. 20 mg/kg). On the contrary to the bulbs the green leaves of onions like chive and leek contain almost exclusively compounds of ferulic and p-coumaric acid. Garlic even shows a different phenolic acid pattern of skins and internal tissues. The caffeic acid derivatives of potatoes are mainly localized to a 1--2 mm thick outer layer. The different localization of phenolic acids in the different parts of vegetable plants is discussed.

  9. Fatty acid-amino acid conjugates diversification in lepidopteran caterpillars.

    PubMed

    Yoshinaga, Naoko; Alborn, Hans T; Nakanishi, Tomoaki; Suckling, David M; Nishida, Ritsuo; Tumlinson, James H; Mori, Naoki

    2010-03-01

    Fatty acid amino acid conjugates (FACs) have been found in noctuid as well as sphingid caterpillar oral secretions; in particular, volicitin [N-(17-hydroxylinolenoyl)-L-glutamine] and its biochemical precursor, N-linolenoyl-L-glutamine, are known elicitors of induced volatile emissions in corn plants. These induced volatiles, in turn, attract natural enemies of the caterpillars. In a previous study, we showed that N-linolenoyl-L-glutamine in larval Spodoptera litura plays an important role in nitrogen assimilation which might be an explanation for caterpillars synthesizing FACs despite an increased risk of attracting natural enemies. However, the presence of FACs in lepidopteran species outside these families of agricultural interest is not well known. We conducted FAC screening of 29 lepidopteran species, and found them in 19 of these species. Thus, FACs are commonly synthesized through a broad range of lepidopteran caterpillars. Since all FAC-containing species had N-linolenoyl-L-glutamine and/or N-linoleoyl-L-glutamine in common, and the evolutionarily earliest species among them had only these two FACs, these glutamine conjugates might be the evolutionarily older FACs. Furthermore, some species had glutamic acid conjugates, and some had hydroxylated FACs. Comparing the diversity of FACs with lepidopteran phylogeny indicates that glutamic acid conjugates can be synthesized by relatively primitive species, while hydroxylation of fatty acids is limited mostly to larger and more developed macrolepidopteran species.

  10. Fluorotelomer acids are more toxic than perfluorinated acids.

    PubMed

    Phillips, Michelle M MacDonald; Dinglasan-Panlilio, Mary Joyce A; Mabury, Scott A; Solomon, Keith R; Sibley, Paul K

    2007-10-15

    Saturated and unsaturated fluorotelomer carboxylic acids have been identified as intermediates in the degradation of fluorotelomer alcohols to perfluorinated carboxylic acids (PFCAs). Although surface waters are the likely environmental sink for telomer acids, no fate or toxicity data exist for this matrix. We assessed the acute toxicity of the 4:2, 6:2, 8:2, and 10:2 saturated (FTCA) and unsaturated (FTUCA) fluorotelomer carboxylic acids to Daphnia magna, Chironomus tentans, and Lemna gibba. In general, toxicity increased with increasing fluorocarbon (FC) chain length, particularly for telomer acids of > or =8 FCs. In addition, the FTCAs were generally more toxic than the corresponding FTUCAs. Acute EC50s ranged from 0.025 mg/L (0.04 micromol/L) for D. magna (10:2 FTCA, immobility) to 63 mg/L (167 micromol/L) for C. tentans (6:2 FTCA, growth). While chain-length trends observed in the current study agree with those previously reported for PFCAs, the toxicity thresholds generated here are up to 10,000 times smaller. Our data provide the first evidence that PFCA precursors are more toxic than the PFCAs themselves. PMID:17993163

  11. Extractive fermentation of acetic acid

    SciTech Connect

    Busche, R.M.

    1991-12-31

    In this technoeconomic evaluation of the manufacture of acetic acid by fermentation, the use of the bacterium: Acetobacter suboxydans from the old vinegar process was compared with expected performance of the newer Clostridium thermoaceticum bacterium. Both systems were projected to operate as immobilized cells in a continuous, fluidized bed bioreactor, using solvent extraction to recover the product. Acetobacter metabolizes ethanol aerobically to produce acid at 100 g/L in a low pH medium. This ensures that the product is in the form of a concentrated extractable free acid, rather than as an unextractable salt. Unfortunately, yields from glucose by way of the ethanol fermentation are poor, but near the biological limits of the organisms involved. Conversely, C. thermoaceticum is a thermophilic anaerobe that operates at high fermentation rates on glucose at neutral pH to produce acetate salts directly in substantially quantitative yields. However, it is severely inhibited by product, which restricts concentration to a dilute 20 g/L. An improved Acetobacter system operating with recycled cells at 50 g/L appears capable of producing acid at $0.38/lb, as compared with a $0.29/lb price for synthetic acid. However, this system has only a limited margin for process improvement. The present Clostridium system cannot compete, since the required selling price would be $0.42/lb. However, if the organism could be adapted to tolerate higher product concentrations at acid pH, selling price could be reduced to $0.22/lb, or about 80% of the price of synthetic acid.

  12. Anaerobic biotransformation of organoarsenical pesticides monomethylarsonic acid and dimethylarsinic acid

    USGS Publications Warehouse

    Sierra-Alvarez, R.; Yenal, U.; Feld, J.A.; Kopplin, M.; Gandolfi, A.J.; Garbarino, J.R.

    2006-01-01

    Monomethylarsonic acid (MMAV) and dimethylarsinic acid (DMAV) are extensively utilized as pesticides, introducing large quantities of arsenic into the environment. Once released into the environment, these organoarsenicals are subject to microbial reactions. Aerobic biodegradation of MMAV and DMAV has been evaluated, but little is known about their fate in anaerobic environments. The objective of this study was to evaluate the biotransformation of MMAV and DMAV in anaerobic sludge. Biologically mediated conversion occurred under methanogenic or sulfate-reducing conditions but not in the presence of nitrate. Monomethylarsonous acid (MMAIII) was consistently observed as an important metabolite of MMAV degradation, and it was recovered in molar yields ranging from 5 to 47%. The main biotransformation product identified from DMAV metabolism was MMAV, which was recovered in molar yields ranging from 8 to 65%. The metabolites indicate that reduction and demethylation are important steps in the anaerobic bioconversion of MMAV and DMAV, respectively. ?? 2006 American Chemical Society.

  13. Use of dilute hydrofluoric acid and deep eutectic solvent systems for back end of line cleaning in integrated circuit fabrication

    NASA Astrophysics Data System (ADS)

    Padmanabhan Ramalekshmi Thanu, Dinesh

    Fabrication of current generation integrated circuits involves the creation of multilevel copper/low-k dielectric structures during the back end of line processing. This is done by plasma etching of low-k dielectric layers to form vias and trenches, and this process typically leaves behind polymer-like post etch residues (PER) containing copper oxides, copper fluorides and fluoro carbons, on underlying copper and sidewalls of low-k dielectrics. Effective removal of PER is crucial for achieving good adhesion and low contact resistance in the interconnect structure, and this is accomplished using wet cleaning and rinsing steps. Currently, the removal of PER is carried out using semi-aqueous fluoride based formulations. To reduce the environmental burden and meet the semiconductor industry's environmental health and safety requirements, there is a desire to completely eliminate solvents in the cleaning formulations and explore the use of organic solvent-free formulations. The main objective of this work is to investigate the selective removal of PER over copper and low-k (Coral and Black DiamondRTM) dielectrics using all-aqueous dilute HF (DHF) solutions and choline chloride (CC) -- urea (U) based deep eutectic solvent (DES) system. Initial investigations were performed on plasma oxidized copper films. Copper oxide and copper fluoride based PER films representative of etch products were prepared by ashing g-line and deep UV photoresist films coated on copper in CF4/O2 plasma. PER removal process was characterized using scanning electron microscopy and X-ray photoelectron spectroscopy and verified using electrochemical impedance spectroscopy measurements. A PER removal rate of ~60 A/min was obtained using a 0.2 vol% HF (pH 2.8). Deaeration of DHF solutions improved the selectivity of PER over Cu mainly due to reduced Cu removal rate. A PER/Cu selectivity of ~20:1 was observed in a 0.05 vol% deaerated HF (pH 3). DES systems containing 2:1 U/CC removed PER at a rate of ~10 and ~20 A/min at 40 and 70°C respectively. A mixture of 10-90 vol% de-ionized water (W) with 2:1 U/CC in the temperature range of 20 to 40°C also effectively removed PER. Importantly, etch rate of copper and low-k dielectric in DES formulations were lower than that in conventional DHF cleaning solutions.

  14. Gallic Acid, Ellagic Acid and Pyrogallol Reaction with Metallic Iron

    NASA Astrophysics Data System (ADS)

    Jaén, J. A.; González, L.; Vargas, A.; Olave, G.

    2003-06-01

    The reaction between gallic acid, ellagic acid and pyrogallol with metallic iron was studied using infrared and Mössbauer spectroscopy. Most hydrolysable tannins with interesting anticorrosive or inhibition properties are structurally related to these compounds, thus they may be used as models for the study of hydrolysable tannins and related polyphenols. The interaction was followed up to 3 months. Results indicated two different behaviors. At polyphenol concentrations higher than 1% iron converts to sparingly soluble and amorphous ferric (and ferrous) polyphenolate complexes. At lower concentrations (0.1%), the hydrolysis reactions are dominant, resulting in the formation of oxyhydroxides, which can be further reduced to compounds like magnetite by the polyphenols.

  15. Gibberellic acid stimulates acid invertase secretion in pea ovary protoplasts.

    PubMed

    Estruch, J J; Beltrán, J P

    1991-02-25

    Protoplasts purified from mesocarp of nonpollinated pea (Pisum sativum L.) ovaries released acid invertase to the incubation medium. The association of the acid invertase with microsomal fractions, and the sensitivity to energy-metabolism inhibitors and to tunicamycin, indicated the secretory nature of the release process. In the presence of GA3 (10 microM), the protoplasts increased their invertase secretion at about 60 min, this effect being counteracted by tunicamycin but not by cycloheximide. Subcellular fractionation of GA3-treated protoplasts showed that higher invertase secretion was the result of a promotion of invertase transfer from endoplasmic reticulum (ER) to Golgi apparatus. PMID:2001743

  16. Lipoic acid functionalized amino acids cationic lipids as gene vectors.

    PubMed

    Su, Rong-Chuan; Liu, Qiang; Yi, Wen-Jing; Zheng, Li-Ting; Zhao, Zhi-Gang

    2016-10-01

    A series of reducible cationic lipids 4a-4f with different amino acid polar-head groups were prepared. The novel lipid contains a hydrophobic lipoic acid (LA) moiety, which can be reduced under reductive conditions to release of the encapsulated plasmid DNA. The particle size, zeta potential and cellular uptake of lipoplexes formed with DNA, as well as the transfection efficacy (TE) were characterized. The TE of the cationic lipid based on arginine was especially high, and was 2.5times higher than that of a branched polyethylenimine in the presence of 10% serum.

  17. Arterial Blood Carbonic Acid Inversely Determines Lactic and Organic Acids

    PubMed Central

    Aiken, Christopher Geoffrey Alexander

    2013-01-01

    Objective: To establish that arterial blood carbonic acid varies inversely with lactic acid in accordance with bicarbonate exchanging for lactate across cell membranes through the anion exchange mechanism to maintain the Gibbs-Donnan equilibrium. Study Design: Over 5 years, lactate was measured on all blood gases taken from neonatal admissions, as well as organic acid whenever electrolytes were required. Results: Arterial blood gases from 63 infants given high calcium TPN were analyzed. Twenty two needed continuous positive airways pressure (CPAP) only and 31 intermittent positive pressure ventilation (IPPV) and surfactant followed by CPAP to treat respiratory distress syndrome in 51 and meconium aspiration syndrome in 2. All survived and were free of infection. Excluded gases were those with high and falling lactate soon after delivery representing perinatal asphyxia, and those on dexamethasone. Strong inverse relations between carbonic and lactic acids were found at all gestational ages and, independent of glomerular filtration, between carbonic and organic acids. Lactate (mmol/L) = 62.53 X PCO2 -0.96(mmHg) r2 0.315, n 1232, p <0.001. Sixty divided by PCO2 is a convenient measure of physiological lactate at any given PCO2. In the first week, 9.13 ± 2.57% of arterial gases from infants on IPPV had lactates above 120/PCO2, significantly more than 4.74 ± 2.73% on CPAP (p<0.05) and 2.47 ± 2.39% on no support. Conclusion: Changes in arterial blood carbonic acid cause immediate inverse changes in lactic acid, because their anions interchange across cell membranes according to the Gibbs –Donnan equilibrium. Increasing PCO2 from 40 to 120 mmHg decreased lactate from 1.5 mmol/L to 0.5 mmol/L, so that the sum of carbonic and lactic acids increased from 2.72 mmol/L to only 4.17 mmol/L. This helps explain the neuroprotective effect of hypercapnoea and highlights the importance of avoiding any degree of hypocapnoea in infants on IPPV. PMID:24392387

  18. Folic acid: a biopharmaceutical evaluation.

    PubMed

    Bellavinha, Karime Resende; Silva-Barcellos, Neila Márcia; Souza, Janine Braga; Leite, Jaqueline Costa; Souza, Jacqueline de

    2015-01-01

    The aqueous solubility and drug product dissolution are important factors that determine the rate and extent of drug absorption from immediate release solid oral dosage forms. The aim of this article was to perform a folic acid biopharmaceutical study to evaluate the biowaiver of new products containing folic acid. We studied the solubility of its raw material and the dissolution profile of two commercially available products. Three different buffers (pH 1.2, 4.5 and 6.8) were used as the media of the solubility and dissolution tests (apparatus II, at 50 rpm and 900 mL of medium volume). We found that folic acid solubility and its release from tablets are pH dependent. The dissolution profiles of both tablets were compared by dissolution efficiency (%), using t-test or variance analysis (ANOVA). The dissolution profiles obtained for the two products at pH 1.2 medium were similar (p > 0.05), but they were dissimilar at pH 4.5 and 6.8 (p < 0.05). Furthermore, we could observe differences between all the dissolution profiles of folic acid for each product at three different dissolution media used. The results showed that physicochemical characteristics of folic acid affect its dissolution and absorption making it difficult to take a decision on their biowaiver based on BCS.

  19. Isothermal Amplification of Nucleic Acids.

    PubMed

    Zhao, Yongxi; Chen, Feng; Li, Qian; Wang, Lihua; Fan, Chunhai

    2015-11-25

    Isothermal amplification of nucleic acids is a simple process that rapidly and efficiently accumulates nucleic acid sequences at constant temperature. Since the early 1990s, various isothermal amplification techniques have been developed as alternatives to polymerase chain reaction (PCR). These isothermal amplification methods have been used for biosensing targets such as DNA, RNA, cells, proteins, small molecules, and ions. The applications of these techniques for in situ or intracellular bioimaging and sequencing have been amply demonstrated. Amplicons produced by isothermal amplification methods have also been utilized to construct versatile nucleic acid nanomaterials for promising applications in biomedicine, bioimaging, and biosensing. The integration of isothermal amplification into microsystems or portable devices improves nucleic acid-based on-site assays and confers high sensitivity. Single-cell and single-molecule analyses have also been implemented based on integrated microfluidic systems. In this review, we provide a comprehensive overview of the isothermal amplification of nucleic acids encompassing work published in the past two decades. First, different isothermal amplification techniques are classified into three types based on reaction kinetics. Then, we summarize the applications of isothermal amplification in bioanalysis, diagnostics, nanotechnology, materials science, and device integration. Finally, several challenges and perspectives in the field are discussed. PMID:26551336

  20. Fatty acid biosynthesis in actinomycetes

    PubMed Central

    Gago, Gabriela; Diacovich, Lautaro; Arabolaza, Ana; Tsai, Shiou-Chuan; Gramajo, Hugo

    2011-01-01

    All organisms that produce fatty acids do so via a repeated cycle of reactions. In mammals and other animals, these reactions are catalyzed by a type I fatty acid synthase (FAS), a large multifunctional protein to which the growing chain is covalently attached. In contrast, most bacteria (and plants) contain a type II system in which each reaction is catalyzed by a discrete protein. The pathway of fatty acid biosynthesis in Escherichia coli is well established and has provided a foundation for elucidating the type II FAS pathways in other bacteria (White et al., 2005). However, fatty acid biosynthesis is more diverse in the phylum Actinobacteria: Mycobacterium, possess both FAS systems while Streptomyces species have only the multi-enzyme FAS II system and Corynebacterium species exclusively FAS I. In this review we present an overview of the genome organization, biochemical properties and physiological relevance of the two FAS systems in the three genera of actinomycetes mentioned above. We also address in detail the biochemical and structural properties of the acyl-CoA carboxylases (ACCases) that catalyzes the first committed step of fatty acid synthesis in actinomycetes, and discuss the molecular bases of their substrate specificity and the structure-based identification of new ACCase inhibitors with anti-mycobacterial properties. PMID:21204864