EFFECT OF PREEMPTIVE MAGNESIUM SULPHATE ON PAIN RELIEF AFTER LAPAROSCOPIC CHOLECYSTECTOMY

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Ravi Vasupalli

2016-09-01

Full Text Available BACKGROUND The concept of preemptive analgesia was introduced by C. J. Woolf et al demonstrating that a post-injury hypersensitivity results via a central mechanism. The effect of magnesium on perioperative analgesic requirements was first evaluated by Koinig and his colleagues in patients with identical levels of surgical stimulation. Magnesium Sulphate is an antagonist of Nmethyl-D-aspartate (NMDA receptors and its associated channels and regulation of calcium influx into the cell. Magnesium causes modulation of acute pain reducing postsurgical pain intensity and dosage of analgesics. Seyhan et al have reported that magnesium sulphate boluses were effective for postoperative pain relief after gynaecological surgery. Fucs-Budder et al, Kussman B et al used continuous infusion (15 mg/kg/hr. in addition to initial bolus (50 mg/kg of magnesium sulphate in their studies, which caused bradycardia and delayed extubation time, which can be attributed to the infusion of Iva Bacak Kochman et al studied effect of low dose MgSO4 (7.5 mg/kg as analgesic agent after induction in patients undergoing laparoscopic cholecystectomy. This bolus dose of MgSO4 given for control of sympathetic response during intubation also reduced early postoperative pain. Study conducted by O Mentes et al on postoperative analgesic efficacy of single dose MgSO4 (50 mg/kg after laparoscopic cholecystectomy measured significantly less VAS scores. On this background, our study was done to evaluate the postoperative analgesic efficacy of single dose of magnesium sulphate (50 mg/kg as preemptive analgesic and measured after laparoscopic cholecystectomy. In addition to VAS scores, total tramadol consumption and time for first rescue analgesia, postoperative haemodynamic parameters and side effects if any were evaluated. METHODS After obtaining Institutional Ethical committee clearance and written informed consent from the patients, a randomised prospective study was conducted at King

[Need for resuscitation in preterm neonates less than 32 weeks treated with antenatal magnesium sulphate for neuroprotection].

Science.gov (United States)

Lloreda-Garcia, Jose María; Lorente-Nicolás, Ana; Bermejo-Costa, Francisca; Martínez-Uriarte, Juan; López-Pérez, Rocío

2016-01-01

Magnesium sulphate administration is recommended for foetal neuroprotection in pregnant women at imminent risk of early preterm birth. To evaluate the relationship between intrapartum magnesium sulphate for foetal neuroprotection and delivery room resuscitation of preterm infants less 32 weeks. A prospective observational study was conducted on preterm infants less 32 weeks exposed to magnesium sulphate for neuroprotection, and a comparison made with another historic group immediately before starting this treatment. Cases in both groups that had not reached lung maturity with corticosteroids were rejected. The rates of resuscitation, morbidity and mortality for each of the groups were analysed and compared. There was a total of 107 preterm, with 56 exposed to magnesium sulphate. Rate of advanced resuscitation were similar between the two groups. There were no other differences in mortality, invasive mechanical ventilation, time to first stool, and other comorbidities. Intrapartum magnesium sulphate for foetal neuroprotection was not associated with an increased need for intensive delivery room resuscitation and other morbidities in these cohorts of less than 32 weeks preterm infants. Copyright © 2015 Sociedad Chilena de Pediatría. Publicado por Elsevier España, S.L.U. All rights reserved.

Magnesium sulphate as a safe treatment for persistent pulmonary hypertension of newborn resistant to mechanical hyperventilation

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Dehdashtian, M.; Tebatebae, K.

2007-01-01

To see the effects of magnesium sulphate in newborn with persistent pulmonary hypertension of newborn (PPHN) who did not respond to mechanical hyperventilation and are candidate for Extra Corporeal Membrane Oxygenation (ECMO). Ten newborn who were admitted to Neonatal Intensive Care Unit (NICU) with profound hypoxia and respiratory failure due to PPHN were treated with conventional mechanical ventilation and then mechanical hyperventilation. The newborns who did not respond to mechanical Hyperventilation were treated with magnesium sulphate infusion. Nine out of ten babies survived and one of them died. The differences between the mean AaDo2, OI index, and PH after mechanical hyperventilation and magnesium sulphate administration was significant. Magnesium has a role in the treatment of PPHN patients who do not respond to hyperventilation or may be applied instead of hyperventilation. (author)

Effect of anhydrous magnesium sulphate fertilizer and cutting ...

African Journals Online (AJOL)

Effect of anhydrous magnesium sulphate fertilizer on Panicum maximum yield and chemical composition of the resultant herbage harvested at 3, 4 and 5 weeks of age was investigated. The treatments were labeled T1 to T6. T1 was fertilized and harvested at 3 weeks cutting interval, T2 was fertilized and harvested at 4 ...

Magnesium sulphate and amiodarone prophylaxis for prevention of postoperative arrhythmia in coronary by-pass operations

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Huysal Kagan

2009-02-01

Full Text Available Abstract Background The aim of this study was to investigate the use of prophylactic magnesium sulphate and amiodarone in treating arrhythmias that may occur following coronary bypass grafting operations. Methods The study population consisted of 192 consecutive patients who were undergoing coronary artery bypass grafting (CABG. Sixty-four patients were given 3 g of magnesium sulphate (MgSO4 [20 ml = 24.32 mEq/L Mg+2] in 100 cc of isotonic 0.9% solution over 2 hours intravenously at the following times: 12 hours prior to the operation, immediately following the operation, and on postoperative days 1, 2, and 3 (Group 1. Another group of 64 patients was given a preoperative infusion of amiodarone (1200 mg on first post-operative day (Group 2. After the operation amiodarone was administered orally at a dose of 600 mg/day. Sixty-four patients in group 3 (control group had 100 cc. isotonic 0.9% as placebo, during the same time periods. Results In the postoperative period, the magnesium values were significantly higher in Group 1 than in Group 2 for all measurements. The use of amiodarone for total arrhythmia was significantly more effective than prophylactic treatment with magnesium sulphate (p = 0.015. There was no difference between the two drugs in preventing supraventricular arrhythmia, although amiodarone significantly delayed the revealing time of atrial fibrillation (p = 0.026. Ventricular arrhythmia, in the form of ventricular extra systole, was more common in the magnesium prophylaxis group. The two groups showed no significant differences in other operative or postoperative measurements. No side effects of the drugs were observed. Conclusion Prophylactic use of magnesium sulphate and amiodarone are both effective at preventing arrhythmia that may occur following coronary by-pass operations. Magnesium sulphate should be used in prophylactic treatment since it may decrease arrhythmia at low doses. If arrhythmia should occur despite this

High dose, fast delivery magnesium sulphate in a 3-year-old acute severe asthmatic

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John R Elton

2017-09-01

Full Text Available Acute severe asthma when respiratory failure is imminent is not addressed in world asthma guidelines. Intravenous magnesium sulphate, salbutamol and aminophylline all have advocates but what order, speed of delivery or dosage is left up to the individual physician treating the patient. A child in respiratory failure was given a large, fast dose of intravenous magnesium sulphate before intravenous salbutamol which relaxed bronchial smooth muscle immediately and tracheal intubation and lung ventilation was avoided. Justification for this treatment is discussed.

Studies on calcium, magnesium and sulphate in the Mandovi and Zuari river system (Goa)

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SenGupta, R.; Naik, S.

-conservative parameters. Sulphate, however behaves in a purely conservative manner and remains in a steady state in the rivers. A'Simple mixture'relationship is applied to calculate the dilution and mixing processes in the rivers using calcium, magnesium and sulphate...

Comparison of amiodarone vs magnesium sulphate in the prevention of atrial fibrillation after coronary artery bypass grafting surgery

International Nuclear Information System (INIS)

Bashir, I.; Abbas, S.

2013-01-01

Background: Atrial fibrillation (AF) is common in patients after coronary artery bypass grafting (CABG) and can result in increased morbidity and mortality, increased length of hospital stay, and increased cost. In this study we compared the efficacy of amiodarone versus magnesium sulphate in the prophylaxis of post-CABG atrial fibrillation. Objective: This study was carried out to assess the efficacy of amiodarone in comparison to magnesium sulphate in the prevention of atrial fibrillation after coronary artery bypass grafting. Study Design: Randomized controlled trials. Place and duration of study: The study was carried out at Armed Forces Institute of Cardiology and National Institute of Heart Diseases, Rawalpindi from July 2010 to December 2011 Patients and Methods: Total 240 patients were included in the study and randomly divided in two groups of 120 each using random number table. Patients in Group A (Amiodarone group) were given a loading dose of amiodarone 5 mg/Kg after induction of anesthesia which was then continued as infusion at 5 micro gm/Kg/minute on first postoperative day. This was followed by an oral dose of 600 mg/day postoperatively for 5 days. Those in Group B (Magnesium Sulphate group) received 2 g of magnesium sulphate in 100 ml of isotonic 0.9% solution intravenously over 1 hour at following times: preoperatively, immediately following the operation, and on postoperative days 1, 2, and 3. Results: Thirteen patients (10.8%) developed AF in Amiodarone group, compared to 31 patients (25.8%) in magnesium sulphate group. The results proved amiodarone to be more effective than magnesium sulphate in preventing post-CABG AF (p<0.001). Thirty one patients who developed AF postoperatively in the magnesium group were treated with amiodarone, and all patients recovered normal sinus rhythm. In the amiodarone prophylaxis group, 9 patients regained sinus rhythm in 6 - 8 hours, while for 4 remaining patients cardioversion was attempted out of which 2

Bone mineralization in newborns whose mothers received magnesium sulphate for tocolysis of premature labour

International Nuclear Information System (INIS)

Malaeb, Shadi N.; Rassi, Adriana I.; Yunis, Khalid A.; Haddad, Maurice C.; Seoud, Muhieddine A.

2004-01-01

Prolonged maternal magnesium sulphate infusion therapy for tocolysis of premature labour may result in secondary fetal hypermagnesaemia, which has been associated with bony abnormalities in the newborn. We report on four infants, members of two twin pregnancies, who were exposed to prolonged fetal hypermagnesaemia. Three of the infants, all appropriate for gestational age, showed abnormal radiological findings consisting of abnormal mineralisation of long-bone metaphyses owing to fetal hypermagnesaemia. The fourth infant, who was growth retarded, had normal bones. Intrauterine growth restriction appears to be protective against magnesium sulphate-induced abnormal bone mineralisation in the newborn. (orig.)

Bone mineralization in newborns whose mothers received magnesium sulphate for tocolysis of premature labour

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Malaeb, Shadi N.; Rassi, Adriana I.; Yunis, Khalid A. [Department of Pediatrics, American University of Beirut Medical Center, PO Box 11-0236, Beirut (Lebanon); Haddad, Maurice C. [Department of Diagnostic Radiology, American University of Beirut Medical Center, Beirut (Lebanon); Seoud, Muhieddine A. [Department of Obstetrics and Gynecology, American University of Beirut Medical Center, Beirut (Lebanon)

2004-05-01

Prolonged maternal magnesium sulphate infusion therapy for tocolysis of premature labour may result in secondary fetal hypermagnesaemia, which has been associated with bony abnormalities in the newborn. We report on four infants, members of two twin pregnancies, who were exposed to prolonged fetal hypermagnesaemia. Three of the infants, all appropriate for gestational age, showed abnormal radiological findings consisting of abnormal mineralisation of long-bone metaphyses owing to fetal hypermagnesaemia. The fourth infant, who was growth retarded, had normal bones. Intrauterine growth restriction appears to be protective against magnesium sulphate-induced abnormal bone mineralisation in the newborn. (orig.)

Assessing the neuroprotective benefits for babies of antenatal magnesium sulphate: An individual participant data meta-analysis.

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Caroline A Crowther

2017-10-01

Full Text Available Babies born preterm are at an increased risk of dying in the first weeks of life, and those who survive have a higher rate of cerebral palsy (CP compared with babies born at term. The aim of this individual participant data (IPD meta-analysis (MA was to assess the effects of antenatal magnesium sulphate, compared with no magnesium treatment, given to women at risk of preterm birth on important maternal and fetal outcomes, including survival free of CP, and whether effects differed by participant or treatment characteristics such as the reason the woman was at risk of preterm birth, why treatment was given, the gestational age at which magnesium sulphate treatment was received, or the dose and timing of the administration of magnesium sulphate.Trials in which women considered at risk of preterm birth (<37 weeks' gestation were randomised to magnesium sulphate or control treatment and where neurologic outcomes for the baby were reported were eligible for inclusion. The primary outcomes were infant death or CP and severe maternal outcome potentially related to treatment. Studies were identified based on the Cochrane Pregnancy and Childbirth search strategy using the terms [antenatal or prenatal] and [magnesium] and [preterm or premature or neuroprotection or 'cerebral palsy']. The date of the last search was 28 February 2017. IPD were sought from investigators with eligible trials. Risk of bias was assessed using criteria from the Cochrane Collaboration. For each prespecified outcome, IPD were analysed using a 1-stage approach. All 5 trials identified were included, with 5,493 women and 6,131 babies. Overall, there was no clear effect of magnesium sulphate treatment compared with no treatment on the primary infant composite outcome of death or CP (relative risk [RR] 0.94, 95% confidence interval (CI 0.85 to 1.05, 6,131 babies, 5 trials, p = 0.07 for heterogeneity of treatment effect across trials. In the prespecified sensitivity analysis restricted

Effects of preoperative magnesium sulphate on post-cesarean pain, a placebo controlled double blind study.

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Seyed Mohamad Mireskandari

2015-03-01

Full Text Available To study the role of preoperative intravenous magnesium sulphate in decreasing post-cesarean pain and opioid requirement during first 24hrs.In a double blind randomized clinical trial, prior to induction of general anesthesia, fifty elective cesarean candidates were randomly assigned to one of the two groups of placebo or magnesium sulfate. After surgery visual analogue scale (VAS and infused morphine by PCA during 24 hrs were recorded. The data were analyzed by mann-Whitney -test, analysis of variance, and student t- test.VAS was significantly lower among patients in the magnesium sulphate group at intervals of 1(st, 6(th & 12(th hours after cesarean section (C/S with the mean scales of (48.9 ± 19.6 VS 74.7 ± 18.4, (42.1 ± 0.9 VS 58.3 ± 16.5 and (25.2 ± 6.1VS 30 ± 8.1 respectively and p-value of <0.001, 0.002 and 0.05 respectively. However at 24 hrs there was no significant difference in VAS with mean VAS scales of 22.6 ± 4.5 VS 23.6 ± 4.9 and p-value of 0.49. The dose of infused Morphine during 24 hrs was significantly less in the magnesium sulphate group than the placebo group with the means of 4.36 ± 1.4 VS 7.02 ± 1.9 mg respectively (p < 0.001.Administration of bolus 50 mg/kg magnesium sulphate prior to induction of general anesthesia may significantly decreased the morphine requirement during immediate post operative period and can be recommended as one of the modalities of post-operative pain control in the pregnant patients.

The use of magnesium sulphate for the treatment of severe pre ...

African Journals Online (AJOL)

Background : Pre-eclampsia and eclampsia are important causes of maternal and perinatal morbidity and mortality in the developing countries. There is need to provide the most effective management to pre-eclamptic and eclamptic patients. There is now evidence that magnesium sulphate is the most effective ...

Evaluation of a single-dose of intravenous magnesium sulphate for prevention of postoperative pain after inguinal surgery

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Shashi Kiran

2011-01-01

Full Text Available This study was undertaken to study efficacy of single dose of intravenous magnesium sulphate to reduce post-operative pain in patients undergoing inguinal surgery. One hundred patients undergoing inguinal surgery were divided randomly in two groups of 50 each. The patients of magnesium sulphate group (Group-I received magnesium sulphate 50 mg/kg in 250 ml of isotonic sodium chloride solution IV whereas patients in control group (Group-II received same volume of isotonic sodium chloride over 30 minutes preoperatively. Anaesthesia was induced with propofol (2 mg/kg and pethidine (1 mg/kg. Atracurium besylate (0.5 mg/kg was given to facilitate insertion of LMA. Pain at emergence from anaesthesia and 2, 4, 6, 12 and 24 hours after surgery was evaluated. The timing and dosage of rescue analgesic during first 24 hrs after operation was noted. Pain in postop period was significantly lower in magnesium sulphate group in comparison to control group at emergence from anaesthesia and 2, 4, 6, 12 and 24 hrs postop [1.86 vs. 1.96 (P=0.138, 1.22 vs. 1.82 (P=0.001, 1.32 vs. 1.88 (P=0.000, 2.74 vs. 3.84 (P=0.000, 1.36 vs. 2.00 (P=0.000 and 0.78 vs 1.30 (P=0.000, respectively]. Patients in group-I were more sedated as compared to group-II [sedation score 1.86 vs. 1.40 (P=0.000]. Rescue analgesia requirement postoperatively in first 4, 8 and 16 hrs was significantly lower in patients of group-1 than in group- II [1.9 vs. 3.8 (P<0.05, 25.50 vs. 52.50 (P<0.05 and 0.000 vs. 7.5 (P<0.05]. Preoperative magnesium sulphate infusion decreases postop pain and requirement of rescue analgesia.

The impact of sulphate and magnesium on chloride binding in Portland cement paste

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De Weerdt, K., E-mail: klaartje.d.weerdt@ntnu.no [Department of Structural Engineering, Norwegian University of science and Technology, Trondheim (Norway); SINTEF Building and Infrastructure, Trondheim (Norway); Orsáková, D. [Department of Civil Engineering, Technical University of Brno, Brno (Czech Republic); Geiker, M.R. [Department of Structural Engineering, Norwegian University of science and Technology, Trondheim (Norway)

2014-11-15

The effect of magnesium and sulphate present in sea water on chloride binding in Portland cement paste was investigated. Ground well hydrated cement paste was exposed to MgCl{sub 2}, NaCl, NaCl + MgCl{sub 2}, MgSO{sub 4} + MgCl{sub 2} and artificial sea water solutions with a range of concentrations at 20 °C. Chloride binding isotherms are determined and pH of the solutions were measured. A selection of samples was examined by SEM-EDS to identify phase changes upon exposure. The experimental data were compared with calculations of a thermodynamic model. Chloride binding from sea water was similar to chloride binding for NaCl solutions. The magnesium content in the sea water lead to a slight decrease in pH, but this did not result in a notable increase in chloride binding. The sulphate present in sea water reduces both chloride binding in C–S–H and AFm phases, as the C–S–H incorporates more sulphates instead of chlorides, and part of the AFm phases converts to ettringite.

EFFECT OF PRETREATMENT WITH MAGNESIUM SULPHATE ON SUCCINYLCHOLINEINDUCED FASCICULATIONS AND MYALGIA

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Astha Raman

2016-12-01

Full Text Available BACKGROUND Succinylcholine, a depolarising muscle relaxant possesses a unique property of rapid onset and short duration of action, but is accompanied by side effects such as fasciculations and myalgia. A prospective randomised-controlled trial was designed to assess the effect of a combination of magnesium sulphate with propofol for induction of anaesthesia on succinylcholine-induced fasciculations and myalgia. MATERIALS AND METHODS 60 adult patients of ASA status I and II of both sexes for elective surgery under general anaesthesia were randomly allocated into two equal groups, group MG and group NS. The patients of MG group were pretreated with magnesium sulphate 40 mg/kg body weight in 10 mL volume, while patients of NS group were given isotonic saline 0.9% in the same volume (10 mL intravenously slowly over a period of 10 mins. Anaesthesia was administered with pentazocine 0.6 mg/kg and propofol 2 mg/kg, followed by administration of succinylcholine 2 mg/kg intravenously. Muscle fasciculations were observed and graded as nil, mild, moderate or severe. Postoperative myalgia was assessed after 24 hrs. of surgery and graded as nil, mild, moderate or severe. Observations were made in double blind manner where the observer and the patient were blinded. RESULTS Demographic data and baseline parameters of both groups were comparable (P>0.05. Muscle fasciculations occurred in 66.7% patients of MG group versus 100% patients of NS group with a significant difference (P<0.001. After 24 hrs. of surgery, 12 patients of MG group and 28 patients of NS group had myalgia with a significant difference (P<0.001. Statistically significant difference was found in MAP and heart rate at various intervals between the two groups (P<0.001. CONCLUSION Magnesium sulphate 40 mg/kg intravenously maybe used with propofol for induction of anaesthesia to control succinylcholineinduced fasciculations and myalgia.

Evaluation of the effect of magnesium sulphate vs. clonidine as adjunct to epidural bupivacaine

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Tanmoy Ghatak

2010-01-01

Full Text Available For treatment of intra and postoperative pain, no drug has yet been identified that specifically inhibits nociception without associated side effects. Magnesium has antinociceptive effects in animal and human models of pain. The current prospective randomised double-blind study was undertaken to establish the effect of addition of magnesium or clonidine, as adjuvant, to epidural bupivacaine in lower abdominal and lower limb surgeries. A total of 90 American Society of Anesthesiology (ASA grade I and II patients undergoing lower abdominal and lower limb surgeries were enrolled to receive either magnesium sulphate (Group B or clonidine (Group C along with epidural bupivacaine for surgical anaesthesia. All patients received 19 ml of epidural bupivacaine 0.5% along with 50 mg magnesium in group B, 150 mcg clonidine in Group C, whereas in control group (Group A, patients received same volume of normal saline. Onset time, heart rate, blood pressure, duration of analgesia, pain assessment by visual analogue score (VAS and adverse effects were recorded. Onset of anaesthesia was rapid in magnesium group (Group B. In group C there was prolongation of duration of anaesthesia and sedation with lower VAS score, but the incidence of shivering was higher. The groups were similar with respect to haemodynamic variables, nausea and vomiting. The current study establishes magnesium sulphate as a predictable and safe adjunct to epidural bupivacaine for rapid onset of anaesthesia and clonidine for prolonged duration of anaesthesia with sedation.

Fentanyl versus magnesium sulphate as adjuvant to peribulbar anesthesia in cataract surgery

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Mohamed M. Abu Elyazed

2017-04-01

Conclusions: Addition of fentanyl (2 μg/ml or magnesium sulphate (50 mg to peribulbar block in patients undergoing cataract surgery equally prolongs the duration of postoperative analgesia. In addition to this effect, fentanyl fastens the onset lid and globe akinesia and provides better akinesia score.

Yield of castor bean fertilized with sewage sludge and potassium and magnesium sulphate

OpenAIRE

Cavalcanti,Thâmara F. M.; Zuba,Geraldo R.; Sampaio,Regynaldo A.; Carneiro,João P.; Oliveira,Ely S. A. de; Rodrigues,Márcio N.

2015-01-01

ABSTRACTThe aim of this study was to evaluate the yield and nutrition of castor bean in response to fertilization with sewage sludge and potassium (K) and magnesium (Mg) sulphate. The experiment was carried out from January to July 2011. The treatments, in a randomized block design with three replicates, in a Nitosol, corresponded to a factorial scheme (2 x 4 +1): two doses of K and Mg sulphate combined with four doses of sewage sludge (0, 2.60, 5.20 and 10.40 t ha-1, dry basis), applied base...

Effects of magnesium sulphate on amplitude-integrated continuous EEG in asphyxiated term neonates

NARCIS (Netherlands)

Groenendaal, F; Rademaker, CMA; Toet, MC; de Vries, LS

2002-01-01

In this study it is hypothesized that magnesium sulphate in asphyxiated full-term neonates could lead to a gradual improvement in background pattern of the amplitude integrated EEG (aEEG), an early marker of hypoxic-ischaemic brain injury. In a double-blind, randomized, controlled pilot study of 22

Efficacy of magnesium sulphate and/or fentanyl as adjuvants to intrathecal low-dose bupivacaine in parturients undergoing elective caesarean section

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Shelly Rana

2017-01-01

Full Text Available Background and Aim: Recent developments in the field of intrathecal adjuvants have led to accelerated functional recovery with adequate postoperative analgesia following caesarean section. Encouraging results have been obtained with the use of intrathecal magnesium with or without fentanyl in parturients. This study was conceived to evaluate the effects of adding magnesium sulphate and/or fentanyl to low-dose intrathecal bupivacaine in parturients undergoing caesarean section under subarachnoid block (SAB. Materials and Methods: Ninety, American Society of Anesthesiologists I or II, parturients for the elective caesarean section were enrolled in this prospective randomized, double-blind study. The parturients were randomly assigned to three groups. In Group M, parturients received 8.5 mg (1.7 mL hyperbaric bupivacaine 0.5% with 50 mg (0.1 mL magnesium sulphate and 0.4 mL normal saline. Group F received 8.5 mg hyperbaric bupivacaine 0.5% with 20 μg (0.4 mL fentanyl and 0.1 mL of normal saline and Group MF parturients received 8.5 mg hyperbaric bupivacaine 0.5% with 20 μg fentanyl added to 50 mg magnesium sulphate. Results: Parturients in the group MF were pain free for longest period (273.70 ± 49.30 min as compared to group M (252.67 ± 40.76 min and group F (239.80 ± 38.45 mins [gp MF vs F and, gp M vs F (P = 0.00]. The total doses of rescue analgesics were least in group MF (2.43 ± 0.56 and maximum in group F (3.30 ± 0.63, with comparable neonatal outcomes in three groups. Conclusion: Our data supports synergistic action of intrathecal magnesium sulphate to fentanyl, and it is concluded that on addition of intrathecal magnesium sulphate and fentanyl to low-dose bupivacaine as adjuvant in subarachnoid block, results in prolonged duration of postoperative analgesia with lesser pain scores and lesser dose of rescue analgesia with better haemodynamic stability.

COMPARISON OF EFFICACY AND FETOMATERNAL OUTCOME WITH LOW DOSE AND STANDARD PRITCHARD’S REGIMEN OF MAGNESIUM SULPHATE IN ECLAMPSIA

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Nirmala Chamakuri

2017-11-01

Full Text Available BACKGROUND Eclampsia, a hypertensive disorder of pregnancy is a common obstetric emergency, which leads to significant maternal morbidity, perinatal morbidity and mortality. The Pritchard’s regimen of magnesium sulphate remains as the standard regimen worldwide. The aim of this study is to compare the effectiveness, side effects and fetomaternal outcome using low-dose magnesium sulphate with the results of Pritchard regime. MATERIALS AND METHODS A comparative prospective study including 120 eclampsia patients designed into group I and group II treated with low-dose magnesium sulphate and Pritchard’s regimen was conducted in the Department of Obstetrics and Gynaecology for a period of 18 months between January 2015 to June 2016. RESULTS In the present study, there was 100% control of seizures in both the groups. No recurrence of seizures were seen in 57 (95% of cases in group II (low-dose regimen and 3 (5% cases showed recurrence, which were controlled by giving additional doses. In group II, loss of patellar reflexes was seen in 6 (10%, reduced urine output was seen in 3 (5% of cases, mild PPH was observed in 3 (5% cases and perinatal mortality in 18 (30% cases, which were lower than that of group I (Pritchard’s regimen. CONCLUSION Low-dose magnesium sulphate is effective in controlling convulsions in eclampsia. This regimen is highly suitable for use in Indian women who are known to have low body mass index

Magnesium Sulphate and Dexmedetomidine used Intrathecally as Adjuvant to Bupivacaine: A Study

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Zameer Farooq

2017-08-01

Full Text Available Background: Intrathecal adjuvants are used for prolongation of duration of subarachnoid block, and provide adequate analgesia. Aim: To evaluate the onset of sensory and motor block, level of sensory block, highest sensory level and Bromage grade at time of onset, induced by Dexmedetomidine and Magnesium sulphate when given intrathecally with 0.5% hyperbaric Bupivacaine for spinal anaesthesia. Materials and methods: 90 patients, of ASA grade I and grade II, age 18-65 years, of either gender, height 150 cm and above and weight 50 kg to 80 kg, scheduled for lower abdominal and lower limb surgery under spinal anaesthesia. They were randomly assigned according to table of randomization into three groups, 30 patients in each group. Patients in Group A were given 15 mg hyperbaric Bupivacaine and 10 μg (0.1 ml Dexmedetomidine and those in Group B were given 15 mg hyperbaric Bupivacaine and 50 mg (0.1 ml magnesium sulphate. Patients in Group C were given 15 mg hyperbaric Bupivacaine and normal saline (0.1 ml as control. The onset of sensory block, motor block, level of sensory and grade of motor block were recorded at the time of onset. Results: Onset of sensory and motor block was shorter in group Dexmed as compared to other two groups, and prolonged in group magnesium as compared to other two groups. The level of sensory block was higher at the time of onset and grade of motor block was more in group Dexmed than other two groups. Conclusion: Addition of Dexmedetomidine to Bupivacaine shortens the onset time whereas addition of Magnesium delays onset.

Barriers and enablers to implementing antenatal magnesium sulphate for fetal neuroprotection guidelines: a study using the theoretical domains framework.

Science.gov (United States)

Bain, Emily; Bubner, Tanya; Ashwood, Pat; Van Ryswyk, Emer; Simmonds, Lucy; Reid, Sally; Middleton, Philippa; Crowther, Caroline A

2015-08-18

Strong evidence supports administration of magnesium sulphate prior to birth at less than 30 weeks' gestation to prevent very preterm babies dying or developing cerebral palsy. This study was undertaken as part of The WISH (Working to Improve Survival and Health for babies born very preterm) Project, to assess health professionals' self-reported use of antenatal magnesium sulphate, and barriers and enablers to implementation of 2010 Australian and New Zealand clinical practice guidelines. Semi-structured, one-to-one interviews were conducted with obstetric and neonatal consultants and trainees, and midwives in 2011 (n = 24) and 2012-2013 (n = 21) at the Women's and Children's Hospital, South Australia. Transcribed interview data were coded using the Theoretical Domains Framework (describing 14 domains related to behaviour change) for analysis of barriers and enablers. In 2012-13, health professionals more often reported 'routinely' or 'sometimes' administering or advising their colleagues to administer magnesium sulphate for fetal neuroprotection (86% in 2012-13 vs. 46% in 2011). 'Knowledge and skills', 'memory, attention and decision processes', 'environmental context and resources', 'beliefs about consequences' and 'social influences' were key domains identified in the barrier and enabler analysis. Perceived barriers were the complex administration processes, time pressures, and the unpredictability of preterm birth. Enablers included education for staff and women at risk of very preterm birth, reminders and 'prompts', simplified processes for administration, and influential colleagues. This study has provided valuable data on barriers and enablers to implementing magnesium sulphate for fetal neuroprotection, with implications for designing and modifying future behaviour change strategies, to ensure optimal uptake of this neuroprotective therapy for very preterm infants.

Incorporation of layered double nanomaterials in thin film nanocomposite nanofiltration membrane for magnesium sulphate removal

Science.gov (United States)

Hanis Tajuddin, Muhammad; Yusof, Norhaniza; Salleh, Wan Norharyati Wan; Fauzi Ismail, Ahmad; Hanis Hayati Hairom, Nur; Misdan, Nurasyikin

2018-03-01

Thin film nanocomposite (TFN) membrane with copper-aluminium layered double hydroxides (LDH) incorporated into polyamide (PA) selective layer has been prepared for magnesium sulphate salt removal. 0, 0.05, 0.1, 0.15, 0.2 wt% of LDH were dispersed in the trimesoyl chloride (TMC) in n-hexane as organic solution and embedded into PA layer during interfacial polymerization with piperazine. The fabricated membranes were further characterized to evaluate its morphological structure and membrane surface hydrophilicity. The TFN membranes performance were evaluated with divalent salt magnesium sulphate (MgSO4) removal and compared with thin film composite (TFC). The morphological structures of TFN membranes were altered and the surface hydrophilicity were enhanced with addition of LDH. Incorporation of LDH has improved the permeate water flux by 82.5% compared to that of TFC membrane with satisfactory rejection of MgSO4. This study has experimentally validated the potential of LDH to improve the divalent salt separation performance for TFN membranes.

Incorporation of layered double nanomaterials in thin film nanocomposite nanofiltration membrane for magnesium sulphate removal

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Tajuddin Muhammad Hanis

2018-01-01

Full Text Available Thin film nanocomposite (TFN membrane with copper-aluminium layered double hydroxides (LDH incorporated into polyamide (PA selective layer has been prepared for magnesium sulphate salt removal. 0, 0.05, 0.1, 0.15, 0.2 wt% of LDH were dispersed in the trimesoyl chloride (TMC in n-hexane as organic solution and embedded into PA layer during interfacial polymerization with piperazine. The fabricated membranes were further characterized to evaluate its morphological structure and membrane surface hydrophilicity. The TFN membranes performance were evaluated with divalent salt magnesium sulphate (MgSO4 removal and compared with thin film composite (TFC. The morphological structures of TFN membranes were altered and the surface hydrophilicity were enhanced with addition of LDH. Incorporation of LDH has improved the permeate water flux by 82.5% compared to that of TFC membrane with satisfactory rejection of MgSO4. This study has experimentally validated the potential of LDH to improve the divalent salt separation performance for TFN membranes.

The effect of magnesium sulphate infusion on the incidence and severity of emergence agitation in children undergoing adenotonsillectomy using sevoflurane anaesthesia.

Science.gov (United States)

Abdulatif, M; Ahmed, A; Mukhtar, A; Badawy, S

2013-10-01

This randomised, controlled, double-blind study investigated the effects of intra-operative magnesium sulphate administration on the incidence of emergence agitation in children undergoing adenotonsillectomy using sevoflurane anaesthesia. Seventy children were randomly allocated to receive a 30 mg.kg(-1) bolus of intravenous magnesium sulphate after induction of anaesthesia followed by a continuous infusion of 10 mg.kg(-1).h(-1) or an equal volume of saline 0.9%. All children received titrated sevoflurane anaesthesia adjusted to maintain haemodynamic stability. The Pediatric Anesthesia Emergence Delirium scale and the Children's Hospital of Eastern Ontario Score were used for the assessment of postoperative emergence agitation and pain, respectively. Emergence agitation was more common in the control group than in the magnesium group (23 (72%) and 12 (36%), respectively (p = 0.004)), with a relative risk of 0.51 (95% CI 0.31-0.84), an absolute risk reduction of 0.35 (95% CI 0.10-0.54), and number needed to treat of 3 (95% CI 2-9). Postoperative pain scores were comparable in the two groups. Magnesium sulphate reduces the incidence and severity of emergence agitation in children undergoing adenotonsillectomy using sevoflurane anaesthesia and is not associated with increased postoperative side-effects or delayed recovery. © 2013 The Association of Anaesthetists of Great Britain and Ireland.

Anesthetic effects of adding intrathecal neostigmine or magnesium sulphate to bupivacaine in patients under lower extremities surgeries

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Seyed Hamid Reza Faiz

2012-01-01

Full Text Available Background: Regional anesthesia is widely used to perform different surgical procedures including those performed on the extremities. In this study, the anesthetic effects of adding intrathecal neostigmine or magnesium sulphate to bupivacaine in patients under lower extremities surgeries were assessed. Materials and Methods: In this double-blind randomized clinical trial, 90 patients, candidate for lower extremities surgeries in a training hospital, were recruited. The patients with ASA class I and II aging from 20 to 65 years between 2009 and 2010 were evaluated. The selected patients were randomly assigned to receive either bupivacaine alone (Group A, n=30, or bupivacaine plus magnesium sulphate 50% (Group B, n=30, or bupivacaine plus neostigmine (Group C, n=30. Then sensory and motor onset and complete block and the time of recovery were measured. Results: The sensory block onset time were 3.03 ± 0.981 in group A, 3.90 ± 2.71 in group B and 3.7 ± 1.08 in group C and knee flexion time were not significantly different among the three groups (P > 0.05, whereas the time to complete motor block was significantly longer in group C and motor recovery time were significantly different between groups (P=0.001. Conclusions: According to the obtained results, it may be concluded that magnesium sulphate is a safe and effective adjuvant for increasing the onset time of motor block.

COMPARISON OF EFFECT OF MAGNESIUM SULPHATE AND PRESERVATIVE-FREE KETAMINE AS AN ADJUNCT TO EPIDURAL BUPIVACAINE FOR POSTOPERATIVE ANALGESIA IN ABDOMINAL HYSTERECTOMY

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Radha Korumbil Raghavan

2017-08-01

Full Text Available BACKGROUND Neuraxial blocks are the most common method of anaesthesia in abdominal hysterectomies and epidural technique has been used widely to provide both anaesthesia and postoperative analgesia. It has become a common practice to use polypharmacy approach for treatment of intra and postoperative pain, because no drug has yet been identified that specifically inhibit nociception without side effects. The aim of the study is to compare the effects of magnesium sulphate versus preservative-free ketamine as an adjunct to epidural bupivacaine for postoperative analgesia in abdominal hysterectomy. MATERIALS AND METHODS After obtaining informed consent, the patients were divided into 3 groups of 40 each to receive 20 mL 0.5% bupivacaine (group B, 19 mL 0.5% bupivacaine + 50 mg magnesium sulphate (group BM, 19 mL 0.5% bupivacaine + 50 mg preservative-free ketamine (group BK. Epidural catheter was inserted at L1-L2 space using standard technique. Correct placement was confirmed by a test dose of 2% lignocaine + adrenaline 1 in 2 lakhs. Postoperative analgesia were assessed by VAS score and 0.125% bupivacaine infusion and 1 g paracetamol IV infusion was given as rescue analgesics when VAS ≥4. Onset duration, motor block and side effects were also monitored. RESULTS Mean time of duration of onset in group B, BM, BK were 20, 14, 18 minutes, respectively. Mean time for rescue analgesia were 180, 240 and 480 minutes in group 1, 2 and 3, respectively. These differences were statistically significant. The side effects noticed in each group were not statistically significant. CONCLUSION The onset of effect is faster when magnesium sulphate were added as an adjunct to bupivacaine as compared to preservativefree ketamine. The postoperative analgesia is found to be more with preservative-free ketamine as compared to magnesium sulphate without any significant side effects.

Effect of adding magnesium sulphate to bupivacaine on the clinical profile of ultrasound-guided thoracic paravertebral block in patients undergoing modified radical mastectomy

Directory of Open Access Journals (Sweden)

Mohamed Elsayed Hassan

2015-01-01

Conclusion: Adding magnesium sulphate to bupivacaine in ultrasound-guided paravertebral block resulted in more efficient analgesia and opioid-sparing in female patients undergoing modified radical mastectomy.

COMPARATIVE STUDY OF ROPIVACAINE V/S ROPIVACAINE WITH MAGNESIUM SULPHATE FOR BRACHIAL PLUXUS BLOCK

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Nagarjuna Reddy

2015-09-01

Full Text Available BACKGROUND : The prime duty of any anesthesiologist is to relive pain in the perioperative period. Today regional anesthesia is well established as equal to general anesthesia in effectiveness and patient acceptability. Regional anesthesia is blocking of peripheral ner ve conduction in a reversible way using local anesthetic agents. For surgeries on upper extremities, particularly in emergency surgeries, regional anesthesia has many advantages over general anesthesia. The brachial plexus is approached at the level of tru nks and the compact arrangement of trunks at the supraclavicular level gives a high success rate with minimum local anesthetic drug volume and a dense and fast onset of the block. To prolong the duration of analgesia various drugs have been studied as adju vants to the local anesthetics. AIM : To compare the efficacy of Ropivacaine and Ropivacaine with Magnesium Sulphate for Brachial Plexus Block by Supraclavicular technique, for upper limb orthopedic surgeries. DESIGN : A Prospective randomized comparative st udy . METHODS : Sixty adult patients of both sexes in the age group of 20 - 60 years belonging to ASA I/II category posted for various types of upper limb surgeries. The patients were randomly allocated into two groups. Supraclavicular brachial plexus block wa s performed. Group – I (Ropivacaine alone – 30 patients received 29ml of 0.75% Ropiva caine with 1ml of normal saline .Group – II (Ropivacaine+Magnesium – 30 patients received 29ml of 0.75% Ropivacaine with Magnesium Sulphate 250mg (1ml of 500mg drug diluted wi th 1ml of distilled water. The following parameters were observed after performing Supraclavicular Brachial Plexus block in both the groups: 1. Time of onset of block (Sensory and Motor 2. Total Duration of Analgesia 3. Total Duration of Motor Blockade 4 . Dermatomes/Nerves blocked 5. Complications if any. RESULTS : There was no significant difference in onset of sensory blockade between Group I ( 4

Yield of castor bean fertilized with sewage sludge and potassium and magnesium sulphate

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Thâmara F. M. Cavalcanti

2015-08-01

Full Text Available ABSTRACTThe aim of this study was to evaluate the yield and nutrition of castor bean in response to fertilization with sewage sludge and potassium (K and magnesium (Mg sulphate. The experiment was carried out from January to July 2011. The treatments, in a randomized block design with three replicates, in a Nitosol, corresponded to a factorial scheme (2 x 4 +1: two doses of K and Mg sulphate combined with four doses of sewage sludge (0, 2.60, 5.20 and 10.40 t ha-1, dry basis, applied based on its nitrogen (N content and the N requirement for the crop and an additional treatment with NPK. The castor bean grain yield fertilized with sewage sludge did not differ from conventional fertilization, with the maximum value achieved at a dose of 7.5 t ha-1 of sewage sludge. The fertilization with sewage sludge increased zinc and copper levels in the soil to values close to or higher than those in conventional fertilization, without any influence on the concentrations in the leaf. Fertilization with K and Mg sulphate increased the levels of these cations in the soil without affecting the concentrations in the leaves. The fertilization with sewage sludge increased the contents of organic matter, sulfur, zinc, iron, copper and boron in the soil, and manganese and boron in castor bean leaves.

Accidental intravenous infusion of a large dose of magnesium sulphate during labor: A case report

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Kamal Kumar

2013-01-01

Full Text Available During labor and child delivery, a wide range of drugs are administered. Most of these medications are high-alert medications, which can cause significant harm to the patient due to its inadvertent use. Errors could be caused due to unfamiliarity with safe dosage ranges, confusion between similar looking drugs, mislabeling of drugs, equipment misuse, or malfunction and communication errors. We report a case of inadvertent infusion of a large dose of magnesium sulphate in a pregnant woman.

Comparison of different doses of magnesium sulphate and fentanyl as adjuvants to bupivacaine for infraumbilical surgeries under subarachnoid block

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Sarika Katiyar

2015-01-01

Full Text Available Background and Aims: Spinal anaesthesia is used for many years for surgeries below the level of umbilicus. It has certain disadvantages such as limited duration of blockade and post-operative analgesia. This study was undertaken to evaluate the effects of additives fentanyl and magnesium sulphate along with bupivacaine during spinal anaesthesia for prolongation of analgesia and motor blockade. Methods: This randomised study was conducted in 120 patients of either sex of American Society of Anesthesiologists physical status I and II, posted for infraumbilical surgeries. Patients were randomly allocated to four groups and were given the following drugs intrathecally as per group distribution; group A - bupivacaine 15 mg (0.5% heavy with fentanyl 25 μg, group B - bupivacaine 15 mg (0.5% heavy with magnesium 100 mg, group C - bupivacaine 15 mg (0.5% heavy with magnesium 50 mg and group D - bupivacaine 15 mg (0.5% heavy with 0.5 ml normal saline. Parameters monitored were duration of analgesia along with haemodynamic parameters and side effects. Data were analysed using the Student′s t-test for the continuous variables and two-tailed Fisher exact test or Chi-square test for categorical variables. Results: There was significant increase in duration of analgesia in group A (374.37 min and B (328.13 min as compared to group C (274.87 min and D (246.03 min. In group A, all haemodynamic parameters decreased by more than 20%, compared to baseline parameters, which was clinically and statistically significant as compared to other groups. There was also increase in duration of motor blockade in groups A and B. Conclusion: Addition of magnesium sulphate at 100 mg dose or fentanyl 25 μg as adjuvants to intrathecal bupivacaine significantly prolongs the duration of analgesia, though in the given doses, magnesium provides better haemodynamic stability than fentanyl, with fewer side effects.

Effect of intravenous magnesium sulphate or dexamethasone as adjuvants to sevoflurane anesthesia to prevent delirium during primary cleft palate repair, controlled randomized blind study

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M. Elsonbaty

2017-01-01

Conclusion: Co-administration of intravenous magnesium sulphate or dexamethasone with to sevoflurane anesthesia during primary cleft palate repair provides more vital hemodynamic state and decrease in postoperative vomiting and delirium when compared with control group.

Comparative study between magnesium sulphate and L-hyoscyamine on duodenal motility during ERCP under general anaesthesia: A prospective randomized study

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Emad El Hefnawy, MD

2017-01-01

Conclusion: Magnesium sulphate is a safe spasmolytic agent during general anaesthesia that improves the success rate of ERCP and it allows easy completion of the procedure by decreasing the duodenal motility. It decreases the duration of the procedure, subsequently shortens the period of anaesthesia and improves post procedure recovery. It reduces post ERCP pancreatitis, nausea and vomiting.

Magnesium oxychloride cement concrete

Indian Academy of Sciences (India)

TECS

exposure to water and salt attack by replacing 10% magnesium chloride solution by magnesium sulphate solution ... Having tremendous load bearing capacity, it can withstand .... retention coefficients for similar concrete compositions.

A Shortened versus Standard Matched Postpartum Magnesium ...

African Journals Online (AJOL)

Magnesium sulphate is currently the most ideal drug for the treatment of eclampsia but its use in Nigeria is still limited due its cost and clinicians inexperience with the drug. The purpose of this study was to determine whether a shortened postpartum course of magnesium sulphate is as effective as the standard Pritchard ...

Removal of radium from aqueous sulphate solutions

International Nuclear Information System (INIS)

Weir, D.R.; Masters, J.T.; Neven, M.

1983-01-01

Radium is often present in ores and an aqueous solution associated with the ore may consequently contain dissolved radium. It is frequently necessary to remove radium from such solutions to reduce the total radium content to a prescribed low level before the solution can be returned to the environment. The present invention is based on the discovery that the total radium content can be reduced to a satisfactory level within a reasonable time by adding a soluble barium salt to a radium-containing sulphate solution which also contains dissolved magnesium at a pH not greater than about 0 to precipitate radium as barium radium sulphate, raising the pH to at least 11 to precipitate an insoluble magnesium compound which collects the barium radium sulphate precipitate, and separating substantially all of the precipitates from the solution

Computerised analysis of sulphate action on model concrete piles

Digital Repository Service at National Institute of Oceanography (India)

Deshmukh, A.M.; Balasubramanian, S.; Venugopal, C.

Sulphate action severely affects the durability of marine structures. It is imperative to study precisely the effects of magnesium sulphate on pile foundations in the marine environment. In the present paper an attempt is made to assess and analyse...

Application of magnesium hydroxide and barium hydroxide for the ...

African Journals Online (AJOL)

Application of magnesium hydroxide and barium hydroxide for the removal of metals and sulphate from mine water. ... equivalent to the Ba(OH)2 dosage. During CO2-dosing, CaCO3 is precipitated to the saturation level of CaCO3. Keywords: Magnesium hydroxide; barium hydroxide; sulphate removal; water treatment ...

Long-Term Impact of Intrauterine Neuroinflammation and Treatment with Magnesium Sulphate and Betamethasone: Sex-Specific Differences in a Preterm Labor Murine Model

Science.gov (United States)

2017-12-20

intrauterine neuroinflammation and treatment with magnesium sulphate and betamethasone: Sex -specific differences in a preterm labor murine model...widespread use of Mg504 in clinical practice, its effects on adult offspring are not well known nor have sex -specific differences in therapeutic...injury. Prenatal treatment with MgSOJbetamethasone confers long-term benefits beyond cerebral palsy prevention with sex -specific differences in

Antenatal magnesium sulphate may prevent cerebral palsy in preterm infants--but are we convinced? Evaluation of an apparently conclusive meta-analysis with trial sequential analysis

DEFF Research Database (Denmark)

Huusom, L D; Secher, N J; Pryds, O

2011-01-01

Please cite this paper as: Huusom L, Secher N, Pryds O, Whitfield K, Gluud C, Brok J. Antenatal magnesium sulphate may prevent cerebral palsy in preterm infants-but are we convinced? Evaluation of an apparently conclusive meta-analysis with trial sequential analysis. BJOG 2011;118:1-5....

NASA GSFC Tin Whisker Homepage http://nepp.nasa.gov/whisker

Science.gov (United States)

Shaw, Harry

2000-01-01

The NASA GSFC Tin Whisker Homepage provides general information and GSFC Code 562 experimentation results regarding the well known phenomenon of tin whisker formation from pure tin plated substrates. The objective of this www site is to provide a central repository for information pertaining to this phenomenon and to provide status of the GSFC experiments to understand the behavior of tin whiskers in space environments. The Tin Whisker www site is produced by Code 562. This www site does not provide information pertaining to patented or proprietary information. All of the information contained in this www site is at the level of that produced by industry and university researchers and is published at international conferences.

Magnesium for acute exacerbation of chronic obstructive pulmonary disease: A systematic review of randomised trials

Directory of Open Access Journals (Sweden)

Mitrakrishnan Chrishan Shivanthan

2014-01-01

Full Text Available The efficacy of magnesium sulphate in chronic obstructive pulmonary disease (COPD was assessed by conducting a systematic review of published randomized clinical trials through extensive searches in MEDLINE and SCOPUS with no date limits, as well as manual review of journals. Outcome measures varied depending on route(s of administration of magnesium sulphate and medications co-administered. Risk of bias was evaluated and quality of evidence was graded. Four (4 randomized trials were included. All trials had a moderate risk of bias and were of average methodological quality. Magnesium sulphate given intravenously did not seem to have an immediate bronchodilatory effect; however it appears to potentiate the bronchodilatory effect of inhaled beta-2 agonists. Increase in peak expiratory flow rate (PEFR at 30 and 45 min was greater in those who received magnesium sulphate compared to placebo (P = 0.03, although the mean percentage change in PEFR was just 24%, without significant differences in dyspnoea scores, hospital admission rates, or emergency department readmission rates compared to placebo. Nebulized magnesium sulphate with salbutamol versus nebulized salbutamol with saline placebo showed no significant differences is forced expiratory volume in 1 s (FEV 1 measured at 90 min after adjustment for baseline FEV 1 (P = 0.34 or differences in the need for hospital admission. Combined inhalational and intravenous magnesium sulphate versus intravenous saline placebo and nebulized ipratropium bromide were comparable in terms of hospital admission, intubation and death, but the ipratropium bromide group showed better bronchodilator effect and improvement in arterial blood gas parameters. Overall, trial evidence for trial evidence for magnesium sulphate in acute exacerbation of COPD is poor, and further well-designed trials are needed.

NASA Goddard Space Flight Center Tin Whisker (and Other Metal Whisker) Homepage

Science.gov (United States)

Brusse, Jay; Sampson, Mike; Leidecker, Henning; Kadesch, Jong

2004-01-01

This website provides information about tin whiskers and related research. The independent research performed during the past 50+ years is so vast that it is impractical to cover all aspects of tin whiskers in this one resource. Therefore, the absence of information in this website about a particular aspect of tin whiskers should NOT be construed as evidence of absence.

The effects of dexmedetomidine and magnesium sulphate in adult patients undergoing endoscopic transnasal transsphenoidal resection of pituitary adenoma: A double-blind randomised study

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Rabie Soliman

2017-01-01

Full Text Available Background and Aim: Transnasal transsphenoidal resection of pituitary tumours is associated with blood loss and wide fluctuations in haemodynamic parameters. The aim of the present study was to compare the effect of dexmedetomidine and magnesium sulphate during the transsphenoidal resection of pituitary tumours. Methods: The study was a double-blind, randomised study and included 152 patients classified randomly into two groups: Group D: Dexmedetomidine was given as a loading dose 1 μg/kg over 10 min before induction followed by an infusion at 0.5 μg/kg/h during the surgery. Group M: Magnesium sulphate was given as loading dose of 50 mg/kg over 10 min followed by an infusion at 15 mg/kg/h during the surgery. The systolic, diastolic and mean arterial blood pressures, in addition to the amount of blood loss were measured at specific timepoints. Data were described in terms of mean ± standard deviation, median, frequencies, 95% confidence of interval of mean and percentages. Results: Mean bleeding score was lower in Group D than Group M (1.36 ± 0.48 vs. 3.05 ± 0.65, respectively; P = 0.002. Mean blood loss was lower in Group D (157.43 ± 48.79 ml vs.299.47 ± 77.28 ml in Group M; P < 0.001Heart rate, mean arterial pressure, fentanyl requirements, end-tidal sevoflurane concentration, and extubation and emergence times were lower, while incidence of bradycardia and hypotension were higher in Group D. Conclusions: During transsphenoidal pituitary resection, dexmedetomidine, compared to magnesium, is associated with lower blood loss and better operating conditions but with more hypotension and bradycardia

Is serum magnesium estimate necessary in patients with Eclampsia ...

African Journals Online (AJOL)

The therapeutic index of magnesium is said to be low, hence, there are fears of toxicity when used as anticonvulsant in eclamptic patients. The objective of this study was to determine the serum levels of magnesium in eclamptic patients treated with magnesium sulphate and relate the levels with clinical indicators. It was a ...

Mitigating tin whisker risks theory and practice

CERN Document Server

Handwerker, Carol A; Bath, Jasbir

2016-01-01

Discusses the growth mechanisms of tin whiskers and the effective mitigation strategies necessary to reduce whisker growth risks. This book covers key tin whisker topics, ranging from fundamental science to practical mitigation strategies. The text begins with a review of the characteristic properties of local microstructures around whisker and hillock grains to identify why these particular grains and locations become predisposed to forming whiskers and hillocks. The book discusses the basic properties of tin-based alloy finishes and the effects of various alloying elements on whisker formation, with a focus on potential mechanisms for whisker suppression or enhancement for each element. Tin whisker risk mitigation strategies for each tier of the supply chain for high reliability electronic systems are also described.

Metal Whiskers: A Discussion of Risks and Mitigation

Science.gov (United States)

2010-11-30

efforts to investigate – Chromate conversion finishes DO NOT appear to stop whisker formation [4] S. Arnold, "Repressing the Growth of Tin Whiskers...November 30, 2010 Metal Whiskers 10 Examples of Metal Whiskers Zinc-Plated Steel Bus Rail with Yellow Chromate Conversion Finish Zinc whiskers grew...Metal Whiskers 11 Examples of Metal Whiskers Tin-Plated D-Sub Connector Shell Connector Advertised as “RoHS Compliant” November 30, 2010 Metal

Microbial Growth in the Magnesium- Chloride - Sodium- Sulphate Ion System: Implications for Habitability in Terrestrial and Extraterrestrial Salts

Science.gov (United States)

Loudon, C. M.; Aka, S.; Cockell, C. S.

2017-12-01

Icy moons in the outer solar system are key targets in the search for extra-terrestrial life as there is evidence that they harbour subsurface oceans. Observational evidence of icy moons such as Europa suggest that these likely brine oceans should be composed of chloride and sulphate salts. The effects of the ions that compose these salts on biology and how the interactions between them can create geochemical and geophysical barriers to life are poorly understood. Here we present an in depth study of four microorganisms grown in solutions with varying combinations of the magnesium- chloride- sodium- sulphate ions. We find that the ion composition of the brine solution can have a large effect on growth. Whilst the water activity must be permissible for growth we found that this alone could not predict the effects of the ions on growth, chaotropic effects and ion specific effects influenced by the specific physiology of organisms are also evident. For this reason we conclude that simply knowing which salts are present on icy moons is not sufficient information to determine their potential habitibility. A full sample of any brine ocean would need to be studied to fully determine the potential for biology on these outer solar system satellites.

Cellulose whisker/epoxy resin nanocomposites.

Science.gov (United States)

Tang, Liming; Weder, Christoph

2010-04-01

New nanocomposites composed of cellulose nanofibers or "whiskers" and an epoxy resin were prepared. Cellulose whiskers with aspect ratios of approximately 10 and approximately 84 were isolated from cotton and sea animals called tunicates, respectively. Suspensions of these whiskers in dimethylformamide were combined with an oligomeric difunctional diglycidyl ether of bisphenol A with an epoxide equivalent weight of 185-192 and a diethyl toluenediamine-based curing agent. Thin films were produced by casting these mixtures and subsequent curing. The whisker content was systematically varied between 4 and 24% v/v. Electron microscopy studies suggest that the whiskers are evenly dispersed within the epoxy matrix. Dynamic mechanical thermoanalysis revealed that the glass transition temperature (T(g)) of the materials was not significantly influenced by the incorporation of the cellulose filler. Between room temperature and 150 degrees C, i.e., below T(g), the tensile storage moduli (E') of the nanocomposites increased modestly, for example from 1.6 GPa for the neat polymer to 4.9 and 3.6 GPa for nanocomposites comprising 16% v/v tunicate or cotton whiskers. The relative reinforcement was more significant at 185 degrees C (i.e., above T(g)), where E' was increased from approximately 16 MPa (neat polymer) to approximately 1.6 GPa (tunicate) or approximately 215 MPa (cotton). The mechanical properties of the new materials are well-described by the percolation model and are the result of the formation of a percolating whisker network in which stress transfer is facilitated by strong interactions between the whiskers.

Tapered whiskers are required for active tactile sensation.

Science.gov (United States)

Hires, Samuel Andrew; Pammer, Lorenz; Svoboda, Karel; Golomb, David

2013-11-19

Many mammals forage and burrow in dark constrained spaces. Touch through facial whiskers is important during these activities, but the close quarters makes whisker deployment challenging. The diverse shapes of facial whiskers reflect distinct ecological niches. Rodent whiskers are conical, often with a remarkably linear taper. Here we use theoretical and experimental methods to analyze interactions of mouse whiskers with objects. When pushed into objects, conical whiskers suddenly slip at a critical angle. In contrast, cylindrical whiskers do not slip for biologically plausible movements. Conical whiskers sweep across objects and textures in characteristic sequences of brief sticks and slips, which provide information about the tactile world. In contrast, cylindrical whiskers stick and remain stuck, even when sweeping across fine textures. Thus the conical whisker structure is adaptive for sensor mobility in constrained environments and in feature extraction during active haptic exploration of objects and surfaces. DOI: http://dx.doi.org/10.7554/eLife.01350.001.

Successful Management of Phaeochromocytoma using Preoperative Oral Labetalol and Intraoperative Magnesium Sulphate; Report of four cases

Directory of Open Access Journals (Sweden)

Sanath Kumar B. S.

2014-05-01

Full Text Available Phaeochromocytoma is a rare neuroendocrine catecholamine-secreting tumour. This type of tumour poses multidimensional anaesthetic challenges as it has an unpredictable clinical course during surgical resection. The alpha-blocking agent phenoxybenzamine remained the mainstay in preoperative preparation before the introduction of beta-blocking agents. We report four cases operated between 2009–2012 at Sultan Qaboos University Hospital, Muscat, Oman. The cases were prepared with oral labetalol, as the alpha-blocking drug phenoxybenzamine was not immediately available. Responses to simulated stress were tested in the theatre before surgery. Anaesthesia was induced under invasive arterial pressure monitoring and magnesium sulphate infusion. Rare intraoperative surges in blood pressure during tumour manipulation were treated with sodium nitroprusside infusions and phentolamine boluses. All of the patients had an uneventful postoperative recovery. Preoperative treatment with labetalol has rarely been reported and can be considered as a potential therapeutic option with optimal patient monitoring if phenoxybenzamine is unavailable.

Dose evaluation for long-term magnesium treatment in aneurysmal subarachnoid haemorrhage

NARCIS (Netherlands)

van Norden, A. G. W.; van den Bergh, W. M.; Rinkel, G. J. E.

2005-01-01

BACKGROUND: Magnesium is a neuroprotective agent that might prevent or reverse delayed cerebral ischaemia after aneurysmal subarachnoid haemorrhage (SAH). We are presently running a randomized, placebo-controlled, double blind trial with magnesium sulphate (64 mmol/day intravenously). We studied

Electric field stimulated growth of Zn whiskers

Energy Technology Data Exchange (ETDEWEB)

Niraula, D.; McCulloch, J.; Irving, R.; Karpov, V. G. [Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606 (United States); Warrell, G. R.; Shvydka, Diana, E-mail: diana.shvydka@utoledo.edu [Department of Radiation Oncology, University of Toledo Health Science Campus, Toledo, Ohio 43614 (United States)

2016-07-15

We have investigated the impact of strong (∼10{sup 4} V/cm) electric fields on the development of Zn whiskers. The original samples, with considerable whisker infestation were cut from Zn-coated steel floors and then exposed to electric fields stresses for 10-20 hours at room temperature. We used various electric field sources, from charges accumulated in samples irradiated by: (1) the electron beam of a scanning electron microscope (SEM), (2) the electron beam of a medical linear accelerator, and (3) the ion beam of a linear accelerator; we also used (4) the electric field produced by a Van der Graaf generator. In all cases, the exposed samples exhibited a considerable (tens of percent) increase in whiskers concentration compared to the control sample. The acceleration factor defined as the ratio of the measured whisker growth rate over that in zero field, was estimated to approach several hundred. The statistics of lengths of e-beam induced whiskers was found to follow the log-normal distribution known previously for metal whiskers. The observed accelerated whisker growth is attributed to electrostatic effects. These results offer promise for establishing whisker-related accelerated life testing protocols.

Electric field stimulated growth of Zn whiskers

Science.gov (United States)

Niraula, D.; McCulloch, J.; Warrell, G. R.; Irving, R.; Karpov, V. G.; Shvydka, Diana

2016-07-01

We have investigated the impact of strong (˜104 V/cm) electric fields on the development of Zn whiskers. The original samples, with considerable whisker infestation were cut from Zn-coated steel floors and then exposed to electric fields stresses for 10-20 hours at room temperature. We used various electric field sources, from charges accumulated in samples irradiated by: (1) the electron beam of a scanning electron microscope (SEM), (2) the electron beam of a medical linear accelerator, and (3) the ion beam of a linear accelerator; we also used (4) the electric field produced by a Van der Graaf generator. In all cases, the exposed samples exhibited a considerable (tens of percent) increase in whiskers concentration compared to the control sample. The acceleration factor defined as the ratio of the measured whisker growth rate over that in zero field, was estimated to approach several hundred. The statistics of lengths of e-beam induced whiskers was found to follow the log-normal distribution known previously for metal whiskers. The observed accelerated whisker growth is attributed to electrostatic effects. These results offer promise for establishing whisker-related accelerated life testing protocols.

Magnesium sulphate and (123)I-MIBG in pheochromocytoma: Two useful techniques for a complicated disease.

Science.gov (United States)

Vendrell, M; Martín, N; Tejedor, A; Ortiz, J T; Muxí, À; Taurà, P

2016-01-01

Pheochromocytoma is a tumour of the chromaffin tissue. It may, through catecholamine release, have deleterious effects on myocardial structure. A 48-year-old woman with a history of hypertension and type II diabetes mellitus (ASA II) was diagnosed of pheochromocytoma-induced myocarditis, which caused severe cardiogenic shock, with an ejection fraction of 20%. Extreme blood pressure swings required aggressive therapy with vasoactive drugs (norepinephrine and dopamine) and an intra-aortic balloon pump, despite which severe haemodynamic instability persisted. Finally, the use of magnesium sulphate allowed for cardiovascular stabilization and weaning off vasoactive drugs prior to surgery. (123)I-metaiodobenzylguanidine scintigraphy helps not only to functionally confirm tumour tissue, but also to assess severity and prognosis of cardiac failure. Prognosis of pheochromocytoma-induced heart failure can be very poor. The use of these two well-known and relatively simple 'tools' for treatment and prognosis is a helpful option to keep in mind. Copyright © 2014 Sociedad Española de Anestesiología, Reanimación y Terapéutica del Dolor. Publicado por Elsevier España, S.L.U. All rights reserved.

The crystallographic growth directions of Sn whiskers

International Nuclear Information System (INIS)

Stein, J.; Welzel, U.; Leineweber, A.; Huegel, W.; Mittemeijer, E.J.

2015-01-01

The growth directions of 55 Sn whiskers, i.e. the crystallographic orientation parallel to the whisker-growth axes, were determined using (i) a focused ion beam microscope for the determination of the physical growth angles of the whiskers with respect to a specimen (reference) coordinate system and (ii) an electron backscatter detector in a scanning electron microscope for the determination of the crystallographic orientation of the whiskers. The Sn whiskers were found to grow preferentially along low-index directions of the β-Sn crystal structure. The experimental findings of this study (and most of the results presented in the literature as well) were explained by applying, in a modified way, the Hartman–Perdok concept of periodic bond chains, i.e. chains of strong bonds running uninterruptedly through the structure, to the Sn whisker-growth phenomenon

Comparison of intrathecal clonidine and magnesium sulphate used as an adjuvant with hyperbaric bupivacaine in lower abdominal surgery

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Mamta Khandelwal

2017-01-01

Full Text Available Background and Aims: Use of various adjuvants to spinal anaesthesia is a well-known modality to provide intra- and post-operative analgesia. This study was designed to evaluate and compare the analgesic efficacy of clonidine and magnesium when used as an additive to intrathecal 0.5% hyperbaric bupivacaine. Methods: Ninety patients of the American Society of Anesthesiologists' physical status grade I or II, scheduled for lower abdominal surgery under spinal anaesthesia, were randomly allocated into three groups. Group B received 3 mL of 0.5% hyperbaric bupivacaine with 1 mL of normal saline, Group C received 3 mL of 0.5% hyperbaric bupivacaine with 1 mL (30 μg of clonidine and Group M received 3 mL of 0.5% hyperbaric bupivacaine with 1 mL (50 mg magnesium sulphate. The primary outcome variable was duration of analgesia and secondary outcome variables included onset and duration of sensory and motor block, sedation level and adverse effects. Data were analysed with ANOVA, Kruskal–Wallis and Chi-square tests. Results: The time to first rescue analgesia was significantly (P < 0.01 longer in the Group C (330.7 ± 47.7 min than both Groups. Group M (246.3 ± 55.9 min showed significantly prolonged analgesia than Group B (134.4 ± 17.9 min. Group C and Group M showed significantly prolonged duration of both sensory and motor block compared to Group B. Conclusion: Intrathecal clonidine added to bupivacaine prolongs the duration of post-operative analgesia, and hastens the onset and prolongs the duration of sensory and motor block compared to magnesium or controls.

Synthesis of Bi2Sr2CaCu2O8+δ whiskers and cross-whisker intrinsic Josephson junction

International Nuclear Information System (INIS)

Hatano, T.; Takano, Y.; Arisawa, S.; Ishii, A.; Togano, K.; Fukuyo, A.

2001-01-01

A synthesis technique of Bi 2 Sr 2 CaCu 2 O 8+δ single-crystal whiskers was studied. The whiskers were synthesized by heating glassy melt-quenched Bi-Sr-Ca-Cu-O (3:2:2:4 in cationic ratio) plates. The atmospheric condition of the whisker growth, especially oxygen partial pressure and gas flow, was investigated. It was found out that the whisker growth rate shows a maximum at P O2 =2/3 bar. For the crystalline quality of the whiskers, the airtight condition was found to be useful as compared to the conventional oxygen stream condition. The crystalline quality, especially the straightness and morphology of the surface, could be improved by keeping the growing whiskers under the equilibrium P Bi condition. Over 20-mm-long whisker crystals have been successfully synthesized by choosing optimum oxygen partial pressure around the P O2 =2/3 bar in the airtight condition. The growth condition and mechanism of the Bi 2 Sr 2 CaCu 2 O 8+δ whiskers were investigated by an in-situ high-temperature x-ray diffraction analysis and an in-situ high-temperature microscope observation. It was found that the whiskers grow in a partially melted state at a temperature of 10-40 degrees below the melting point. The result obtained demonstrates that Bi 2 Sr 2 CaCu 2 O 8+δ whiskers grow at their bottom by the conventional liquid-phase growth mechanism, as was proposed by Matsubara et al. (author)

Inorganic-whisker-reinforced polymer composites synthesis, properties and applications

CERN Document Server

Sun, Qiuju

2015-01-01

Inorganic-Whisker-Reinforced Polymer Composites: Synthesis, Properties and Applications gives a comprehensive presentation of inorganic microcrystalline fibers, or whiskers, a polymer composite filler. It covers whisker synthesis, surface modification, applications for reinforcing polymer-matrix composites, and analysis of resulting filled polymer composites. It focuses on calcium carbonate whiskers as a primary case study, introducing surface treatment methods for calcium carbonate whiskers and factors that influence them. Along with calcium carbonate, the book discusses potassium titanate and aluminum borate whiskers, which also comprise the new generation of inorganic whiskers. According to research results, composites filled by inorganic whiskers show improved strength, wear-resistance, thermal conductivity, and antistatic properties. It explains the importance of modifying polymer materials for use with inorganic whiskers and describes preparation and evaluation methods of polymers filled with inorganic ...

The Magpie Trial follow up study: outcome after discharge from hospital for women and children recruited to a trial comparing magnesium sulphate with placebo for pre-eclampsia [ISRCTN86938761

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2004-03-01

Full Text Available Abstract Background The Magpie Trial compared magnesium sulphate with placebo for women with pre-eclampsia. 10,141 women were recruited, 8804 before delivery. Overall, 9024 children were included in the analysis of outcome at discharge from hospital. Magnesium sulphate more than halved the risk of eclampsia, and probably reduced the risk of maternal death. There did not appear to be any substantive harmful effects on the baby, in the short term. It is now important to assess whether these benefits persist, and to provide adequate reassurance about longer term safety. The main objective of the Magpie Trial Follow Up Study is to assess whether in utero exposure to magnesium sulphate has a clinically important effect on the child's chance of surviving without major neurosensory disability. Other objectives are to assess long term outcome for the mother, and to develop and assess appropriate strategies for following up large numbers of children in perinatal trials. Study design Follow up is only feasible in selected centres. We therefore anticipate contacting 2800–3350 families, for 2435–2915 of whom the woman was randomised before delivery. A further 280–335 children would have been eligible for follow up if they had survived. The total sample size for the children is therefore 3080–3685, 2680–3210 of whom will have been born to women randomised before delivery. Families eligible for the follow up will be contacted, and surviving children screened using the Ages and Stages Questionnaires. Children who screen positive, and a sample of those who screen negative, will whenever possible have a paediatric and neurodevelopmental assessment. When women are contacted to ask how their child is, they will also be asked about their own health. The primary outcome is a composite measure of death or neurosensory disability for the child at 18 months. Discussion The Follow Up Study began in 2002, and now involves collaborators in 19 countries. Data

Sn whiskers removed by energy photo flashing

International Nuclear Information System (INIS)

Jiang, N.; Yang, M.; Novak, J.; Igor, P.; Osterman, M.

2012-01-01

Highlights: ► Sn whiskers were sintered by intense light flashing (Photosintering). ► Photosintering can effectively eliminate Sn whiskers. ► Photosintering would not damage electronic devices. ► Photosintering is a very promising approach to improve Sn-based electronic surface termination. - Abstract: Sn whiskers have been known to be the major issue resulting in electronic circuit shorts. In this study, we present a novel energy photo flashing approach (photosintering) to shorten and eliminate Sn whiskers. It has been found that photosintering is very effective to modify and remove Sn whiskers; only a sub-millisecond duration photosintering can amazingly get rid of over 90 vol.% of Sn whiskers. Moreover, this photosintering approach has also been proved to cause no damages to electronic devices, suggesting it is a potentially promising way to improve Sn-based electronic surface termination.

Comparison of the effects of magnesium sulphate and dexmedetomidine on surgical vision quality in endoscopic sinus surgery: randomized clinical study

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Akcan Akkaya

2014-12-01

Full Text Available Background and objectives: Even a small amount of bleeding during endoscopic sinus surgery can corrupt the endoscopic field and complicate the procedure. Various techniques, including induced hypotension, can minimize bleeding during endoscopic sinus surgery. The aim of this study was to compare the surgical vision quality, haemodynamic parameters, postoperative pain, and other effects of magnesium, a hypotensive agent, with that of dexmedetomidine, which was initially developed for short-term sedation in the intensive care unit but also is an alpha 2 agonist sedative. Method: 60 patients between the ages of 18 and 45 years were divided into either the magnesium group (Group M or the dexmedetomidine group (Group D. In Group M, magnesium sulphate was given at a pre-induction loading dose of 50 mg kg−1 over 10 min and maintained at 15 mg kg−1 h−1; in Group D, dexmedetomidine was given at 1 mcg kg−1 10 min before induction and maintained at 0.6 mcg kg−1 h−1. Intraoperatively, the haemodynamic and respiratory parameters and 6-point intraoperative surgical field evaluation scale were recorded. During the postoperative period, an 11-point numerical pain scale, the Ramsay sedation scale, the nausea/vomiting scale, the adverse effects profile, and itching parameters were noted. Results: Group D showed a significant decrease in intraoperative surgical field evaluation scale scale score and heart rate. The average operation time was 50 min, and Group M had a higher number of prolonged surgeries. No significant difference was found in the other parameters. Conclusions: Due to its reduction of bleeding and heart rate in endoscopic sinus surgery and its positive impacts on the duration of surgery, we consider dexmedetomidine to be a good alternative to magnesium.

Research on SiC Whisker Prepared by H-PSO

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WANG Yao

2017-10-01

Full Text Available SiC whiskers were prepared on the matrix of graphite by using high hydrogenous silicone oil(PSO as raw material. The effect of surface conditions of graphite and heating temperature on the growth of SiC whisker was mainly studied in this paper. The main factor which affects the nucleation and growth of SiC whisker is the heating temperature, with the heating temperature rising, the production of SiC whisker increases. The surface condition of graphite matrix also influences the growth of SiC whisker. With the nucleation points provided by graphite matrix defects increasing, the production of SiC whisker incleases and SiC whisker starts to overlap with each other. The formation process of SiC whisker includes two steps:nucleation and growth. SiC whisker nucleates at low temperature and grows at high temperature, which follows the VLS (vapor-liquid-solid growth mechanism.

Magnesium for aneurysmal subarachnoid haemorrhage (MASH-2): a randomised placebo-controlled trial

NARCIS (Netherlands)

Dorhout Mees, Sanne M.; Algra, Ale; Vandertop, W. Peter; van Kooten, Fop; Kuijsten, Hans A. J. M.; Boiten, Jelis; van Oostenbrugge, Robert J.; Al-Shahi Salman, Rustam; Lavados, Pablo M.; Rinkel, Gabriel J. E.; van den Bergh, Walter M.

2012-01-01

Background Magnesium sulphate is a neuroprotective agent that might improve outcome after aneurysmal subarachnoid haemorrhage by reducing the occurrence or improving the outcome of delayed cerebral ischaemia. We did a trial to test whether magnesium therapy improves outcome after aneurysmal

Bio-Inspired PVDF-Based, Mouse Whisker Mimicking, Tactile Sensor

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Mohsin Islam Tiwana

2016-10-01

Full Text Available The design and fabrication of a Polyvinylidene fluoride (PVDF based, mouse (or rodent whisker mimicking, tactile sensor is presented. Unlike previous designs reported in the literature, this sensor mimics the mouse whisker not only mechanically, but it also makes macro movements just like a real mouse whisker in a natural environment. We have developed a mathematical model and performed finite element analysis using COMSOL, in order to optimise the whisker to have the same natural frequency as that of a biological whisker. Similarly, we have developed a control system that enables the whisker mimicking sensor to vibrate at variable frequencies and conducted practical experiments to validate the response of the sensor. The natural frequency of the whisker can be designed anywhere between 35 and 110 Hz, the same as a biological whisker, by choosing different materials and physical dimensions. The control system of this sensor enables the whisker to vibrate between 5 and 236 Hz.

Identifying barriers to the availability and use of Magnesium Sulphate Injection in resource poor countries: a case study in Zambia.

Science.gov (United States)

Ridge, Anna L; Bero, Lisa A; Hill, Suzanne R

2010-12-16

Pre-eclampsia and eclampsia are serious complications of pregnancy and major causes of maternal mortality and morbidity worldwide. According to systematic reviews and WHO guidelines magnesium sulphate injection (MgSO4) should be the first -line treatment for severe pre-eclampsia and eclampsia. Studies have shown that this safe and effective medicine is unavailable and underutilized in many resource poor countries. The objective of this study was to identify barriers to the availability and use of MgSO4 in the Zambian Public Health System. A 'fishbone' (Ishikawa) diagram listing probable facilitators to the availability and use of MgSO4 identified from the literature was used to develop an assessment tool. Barriers to availability and use of MgSO4 were assessed at the regulatory/government, supply, procurement, distribution, health facility and health professional levels. The assessment was completed during August 2008 using archival data, and observations at a pragmatic sample of health facilities providing obstetric services in Lusaka District, Zambia. The major barrier to the availability of MgSO4 within the public health system in Zambia was lack of procurement by the Ministry of Health. Other barriers identified included a lack of demand by health professionals at the health centre level and a lack of in-service training in the use of MgSO4. Where there was demand by obstetricians, magnesium sulphate injection was being procured from the private sector by the hospital pharmacy despite not being registered and licensed for use for the treatment of severe pre-eclampsia and eclampsia by the national Pharmaceutical Regulatory Authority. The case study in Zambia highlights the complexities that underlie making essential medicines available and used appropriately. The fishbone diagram is a useful theoretical framework for illustrating the complexity of translating research findings into clinical practice. A better understanding of the supply system and of the pattern

Composition of Whiskers Grown on Copper in Repository Environment

International Nuclear Information System (INIS)

Hermansson, Hans-Peter; Tarkpea, Peeter; Holgersson, Stellan

2001-11-01

There is a hypothesis that a special family of local attack on copper based on growth of whiskers of sulfide, oxide/hydroxide and also carbonate/malachite could appear in the repository environment. It was earlier demonstrated that such whiskers could grow in a laboratory simulated repository environment, containing sulfide. A suggested composition of whiskers has earlier been forwarded but was not demonstrated. In the present work whiskers and their substrates were grown and characterized by investigations with a combination of SEM-EDS, XRD and LRS (Laser Raman Spectroscopy) techniques. SEM-EDS was used to determine the morphology and an elemental composition and distribution of whiskers and their substrate. A special effort was made to find out if the whisker growth is of a local or global character. The phase status could be determined locally and globally by combining XRD and LRS techniques on whiskers and substrates. Ideally, LRS gives a phase resolution down to a radius of 1 μm on the sample surface. This is of great value as it is of interest to study if there are phase differences in different parts of a whisker. Such information is important to understand the whisker growth mechanism. Cylindrical samples of pure copper were prepared and exposed to the selected de-aerated model groundwater containing, among other ions, chloride and sulfide. Exposure was performed in sealed glass flasks under de-aerated conditions. After exposure the copper sample was investigated on the surface, in cross section and on whiskers using the mentioned techniques. The results show that a black, easily detached layer of corrosion products is formed on the sample surface. The corrosion layer was subdivided into at least five parallel strata (probably more) of different composition. Numerous small pits and shallow pitting attacks with a larger radius were observed in the copper metal and the metal surface was in general very rough. A multitude of very easily detached whiskers or

Bulk Thermoelectric Materials Reinforced with SiC Whiskers

Science.gov (United States)

Akao, Takahiro; Fujiwara, Yuya; Tarui, Yuki; Onda, Tetsuhiko; Chen, Zhong-Chun

2014-06-01

SiC whiskers have been incorporated into Zn4Sb3 compound as reinforcements to overcome its extremely brittle nature. The bulk samples were prepared by either hot-extrusion or hot-pressing techniques. The obtained products containing 1 vol.% to 5 vol.% SiC whiskers were confirmed to exhibit sound appearance, high density, and fine-grained microstructure. Mechanical properties such as the hardness and fracture resistance were improved by the addition of SiC whiskers, as a result of dispersion strengthening and microstructural refinement induced by a pinning effect. Furthermore, crack deflection and/or bridging/pullout mechanisms are invoked by the whiskers. Regarding the thermoelectric properties, the Seebeck coefficient and electrical resistivity values comparable to those of the pure compound are retained over the entire range of added whisker amount. However, the thermal conductivity becomes large with increasing amount of SiC whiskers because of the much higher conductivity of SiC relative to the Zn4Sb3 matrix. This results in a remarkable degradation of the dimensionless figure of merit in the samples with addition of SiC whiskers. Therefore, the optimum amount of SiC whiskers in the Zn4Sb3 matrix should be determined by balancing the mechanical properties and thermoelectric performance.

Whiskers and Localized Corrosion on Copper in Repository Environment

International Nuclear Information System (INIS)

Hermansson, Hans-Peter; Gillen, Peter

2004-03-01

Previous studies have demonstrated that whiskers (thread/hair shaped structures) can form on copper in a sulphide containing environment. A remaining important question is whether the attack on the copper metal surface beneath a whisker is of a localized or of a general nature. This issue has not been clarified as whiskers are very fragile and have always detached and fallen off from the surface at some stage of handling. It has therefore been very difficult to link the growth root of the whisker to underlying structures in the metal surface. A study was therefore initiated to settle the important issue of the relation between whisker position and the type of underlying metal attack. The usage of a porous medium was originally planned to support the whiskers in order to keep them in place and by post examinations characterize the nature of the whisker roots and thus the type of attack on the metal. However, the early stages of the present experimental work clearly indicated that other ways of study were necessary. A photographic method for the registration and positioning of whisker growth was therefore developed. It proved to be a successful means to coordinate whisker position and to link it with the attack on the underlying metal. Shortage of sulphide in previous experiments caused a retarded growth rate of whiskers. Therefore, in present experiments the sulphide concentration was kept at a more constant level throughout an experiment and a hindered whisker growth did not limit the attack on underlying metal. Whiskers and substrates were observed with a video camera throughout an experiment and the phase composition was examined with Laser Raman Spectroscopy, LRS and the Raman video microscope. Post examinations were also performed using light optical microscopy. By combining the results from the optical methods it has been possible to distinguish two kinds of whisker roots (small/large diameter) with the underlying metal surface. It has also been demonstrated

Intravenous Magnesium Sulphate for Analgesia after Caesarean Section: A Systematic Review

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Andrew McKeown

2017-01-01

Full Text Available Objective. To summarise the evidence for use of intravenous magnesium for analgesic effect in caesarean section patients. Background. Postcaesarean pain requires effective analgesia. Magnesium, an N-methyl-D-aspartate receptor antagonist and calcium-channel blocker, has previously been investigated for its analgesic properties. Methods. A systematic search was conducted of PubMed, Scopus, MEDLINE, Cochrane Library, and Google Scholar databases for randomised-control trials comparing intravenous magnesium to placebo with analgesic outcomes in caesarean patients. Results. Ten trials met inclusion criteria. Seven were qualitatively compared after exclusion of three for unclear bias risk. Four trials were conducted with general anaesthesia, while three utilised neuraxial anaesthesia. Five of seven trials resulted in decreased analgesic requirement postoperatively and four of seven resulted in lower serial visual analogue scale scores. Conclusions. Adjunct analgesic agents are utilised to improve analgesic outcomes and minimise opioid side effects. Preoperative intravenous magnesium may decrease total postcaesarean rescue analgesia consumption with few side effects; however, small sample size and heterogeneity of methodology in included trials restricts the ability to draw strong conclusions. Therefore, given the apparent safety and efficacy of magnesium, its role as an adjunct analgesic in caesarean section patients should be further investigated with the most current anaesthetic techniques.

Chemical vapor deposition of tetraboron silicide whiskers

International Nuclear Information System (INIS)

Motozima, Seizi; Sugiyama, Kozoh; Takahashi, Yasutaka

1975-01-01

Growth conditions of B 4 Si whiskers were investigated at the temperature range of 1000 - 1100 0 C. Optimum composition of halides was determined as BCl 3 /SiCl 4 =2 - 0.5, and BCl 3 =1 - 6 vol%, SiCl 4 =1 - 7 vol%. Gold had an excellent impurity effect with optimum concentration of 20 - 50 μg/cm 2 on whisker growth, and gave wool like whiskers of 0.1 - 1 μ in thickness and 0.5 - 2 mm in length. B 4 Si whisker growth was explained in terms of a tip VLS mechanism, for a drop-like deposit of impurity was observed on each tip. (auth.)

Selection of Suitable Carbon, Nitrogen and Sulphate Source for the Production of Alkaline Protease by Bacillus licheniformis NCIM-2042

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Biswanath BHUNIA

2010-06-01

Full Text Available In this study, selection of suitable carbon, nitrogen and sulphate sources were carried out by one-variable-at-time approach for the production of alkaline protease enzyme by Bacillus licheniformis NCIM-2042. Maximum levels of alkaline protease were found in culture media supplemented with magnesium sulphate, starch and soybean meal as a good sulphate, carbon and nitrogen sources which influenced the maximum yield of this enzyme (137.694.57, 135.231.73 and 134.741.77, respectively in comparison with the other sulphate, carbon and nitrogen sources.

Reference values for urinary oxalate, calcium, citrate, uric acid, phosphate, magnesium, sulphate and sodium in biochemistry students at Universidad Nacional del Litoral, Argentina

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Verónica Fernández

2017-10-01

Full Text Available Introduction: Urolithiasis (UL is a common disease whose incidence increased in the last quarter of the twentieth century. Metabolic evaluation is necessary for diagnosis, which requires the establishment of reference values (RV for the population in question. Objective: To determine the RV for calcium, oxalate, citrate, uric acid, phosphate, magnesium, sulphate and sodium in 24-hour urine belonging to students from the School of Biochemistry and Biological Sciences at Universidad Nacional del Litoral, province of Santa Fe, Argentina. Once RV were established, a frequency of alterations was determined and then compared with literature data. Methods: The NCCLSC28-A3 guideline (2008 was used. The study group included 69 students. The enzymatic colorimetric method, a Metrolab 1600 plus spectrophotometer and a DIESTRO ionselective electrode were also employed. Results: The RV found (95 % CI were the following: oxalate, 1.96-45.08; calcium, 20.65-250.74; citrate, 112.78-666.01; uric acid, 58.73-782.17; phosphate, 238.37-1051.44; magnesium, 28.7-146.67, all these values expressed as mg/24h; sulphate, 3.15-25.18 mmol/24h, and sodium, 42.81-285.3 mEq/24h. These findings emerged as well: hyperoxaluria, 3 %; hypercalciuria 12 %; hypocitraturia, 3 %; hyperuricosuria, 6 %; hyperphosphaturia, 6 %; hypomagnesuria, 6 %; hypernatriuria, 7 %, and hypersulphaturia, 0 %. When RV were compared, some analyte levels were similar and others showed a considerable difference. Conclusions: The diagnosis of UL through the study of metabolic changes is different according to the reference value used. Applying reference values established for other populations, including those of commercial kits manufacturers, may lead to a diagnosis which does not match the clinical condition of the patient.

Magnesium stearine production via direct reaction of palm stearine and magnesium hydroxide

Science.gov (United States)

Pratiwi, M.; Ylitervo, P.; Pettersson, A.; Prakoso, T.; Soerawidjaja, T. H.

2017-06-01

The fossil oil production could not compensate with the increase of its consumption, because of this reason the renewable alternative energy source is needed to meet this requirement of this fuel. One of the methods to produce hydrocarbon is by decarboxylation of fatty acids. Vegetable oil and fats are the greatest source of fatty acids, so these can be used as raw material for biohydrocarbon production. From other researchers on their past researchs, by heating base soap from divalent metal, those metal salts will decarboxylate and produce hydrocarbon. This study investigate the process and characterization of magnesium soaps from palm stearine by Blachford method. The metal soaps are synthesized by direct reaction of palm stearine and magnesium hydroxide to produce magnesium stearine and magnesium stearine base soaps at 140-180°C and 6-10 bar for 3-6 hours. The operation process which succeed to gain metal soaps is 180°C, 10 bar, for 3-6 hours. These metal soaps are then compared with commercial magnesium stearate. Based on Thermogravimetry Analysis (TGA) results, the decomposition temperature of all the metal soaps were 250°C. Scanning Electron Microscope with Energy Dispersive X-ray (SEM-EDX) analysis have shown the traces of sodium sulphate for magnesium stearate commercial and magnesium hydroxide for both type of magnesium stearine soaps. The analysis results from Microwave Plasma-Atomic Emission Spectrometry (MP-AES) have shown that the magnesium content of magnesium stearine approximate with magnesium stearate commercial and lower compare with magnesium stearine base soaps. These experiments suggest that the presented saponification process method could produced metal soaps comparable with the commercial metal soaps.

Synthesis of Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} whiskers and cross-whisker intrinsic Josephson junction

Energy Technology Data Exchange (ETDEWEB)

Hatano, T.; Takano, Y.; Arisawa, S.; Ishii, A.; Togano, K. [National Research Inst. for Metals, Tsukuba, Ibaraki (Japan); Fukuyo, A. [Science Univ. of Tokyo (Japan)

2001-03-01

A synthesis technique of Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} single-crystal whiskers was studied. The whiskers were synthesized by heating glassy melt-quenched Bi-Sr-Ca-Cu-O (3:2:2:4 in cationic ratio) plates. The atmospheric condition of the whisker growth, especially oxygen partial pressure and gas flow, was investigated. It was found out that the whisker growth rate shows a maximum at P{sub O2}=2/3 bar. For the crystalline quality of the whiskers, the airtight condition was found to be useful as compared to the conventional oxygen stream condition. The crystalline quality, especially the straightness and morphology of the surface, could be improved by keeping the growing whiskers under the equilibrium P{sub Bi} condition. Over 20-mm-long whisker crystals have been successfully synthesized by choosing optimum oxygen partial pressure around the P{sub O2}=2/3 bar in the airtight condition. The growth condition and mechanism of the Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} whiskers were investigated by an in-situ high-temperature x-ray diffraction analysis and an in-situ high-temperature microscope observation. It was found that the whiskers grow in a partially melted state at a temperature of 10-40 degrees below the melting point. The result obtained demonstrates that Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} whiskers grow at their bottom by the conventional liquid-phase growth mechanism, as was proposed by Matsubara et al. (author)

[Magnesium sulphate in the treatment of ischemic-hypoxic neonatal encephalopathy].

Science.gov (United States)

Kornacka, M K

2001-01-01

Hypoxic-ischaemic encephalopathy (HIE) remains one of the most important neurological complications in full and near full term newborns. During HIE glutamate and other excitatory neurotransmitters are released and progressive energy failure in brain is observed. Toxicity of glutamate plays the main role in brain injury. Glutamate activates the specific receptors that, in turn, mediate an overwhelming influx of calcium into the postsynaptic neuron. The pathological changes are located particularly in hippocampus. Magnesium sulfate has been used safely for years to treat preclampsia. The animal experimental evidence support a neuroprotective role for magnesium in HIE.

Tin Whisker Testing and Modeling

Science.gov (United States)

2015-11-01

to 25°C/85%RH. The greatest whisker nucleation and growth occurred on the Cu alloy lead terminations. During high humidity isothermal exposure...Circuits, Lead-Free Solder, Electronic Assembly, Humidity Exposure, Thermal Cycling, Corrosion, Contamination, Whisker Length Statistics 16. SECURITY...rework fluxes, and immersion Sn finished Cu circuit board pads. The assemblies were exposed to various thermal cycling and isothermal high humidity and

Selection of Suitable Carbon, Nitrogen and Sulphate Source for the Production of Alkaline Protease by Bacillus licheniformis NCIM-2042

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Biswanath BHUNIA

2010-06-01

Full Text Available In this study, selection of suitable carbon, nitrogen and sulphate sources were carried out by one-variable-at-time approach for the production of alkaline protease enzyme by Bacillus licheniformis NCIM-2042. Maximum levels of alkaline protease were found in culture media supplemented with magnesium sulphate, starch and soybean meal as a good sulphate, carbon and nitrogen sources which influenced the maximum yield of this enzyme (137.69�4.57, 135.23�1.73 and 134.74�1.77, respectively in comparison with the other sulphate, carbon and nitrogen sources.

Identifying barriers to the availability and use of Magnesium Sulphate Injection in resource poor countries: A case study in Zambia

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Hill Suzanne R

2010-12-01

Full Text Available Abstract Background Pre-eclampsia and eclampsia are serious complications of pregnancy and major causes of maternal mortality and morbidity worldwide. According to systematic reviews and WHO guidelines magnesium sulphate injection (MgSO4 should be the first -line treatment for severe pre-eclampsia and eclampsia. Studies have shown that this safe and effective medicine is unavailable and underutilized in many resource poor countries. The objective of this study was to identify barriers to the availability and use of MgSO4 in the Zambian Public Health System. Methods A 'fishbone' (Ishikawa diagram listing probable facilitators to the availability and use of MgSO4 identified from the literature was used to develop an assessment tool. Barriers to availability and use of MgSO4 were assessed at the regulatory/government, supply, procurement, distribution, health facility and health professional levels. The assessment was completed during August 2008 using archival data, and observations at a pragmatic sample of health facilities providing obstetric services in Lusaka District, Zambia. Results The major barrier to the availability of MgSO4 within the public health system in Zambia was lack of procurement by the Ministry of Health. Other barriers identified included a lack of demand by health professionals at the health centre level and a lack of in-service training in the use of MgSO4. Where there was demand by obstetricians, magnesium sulphate injection was being procured from the private sector by the hospital pharmacy despite not being registered and licensed for use for the treatment of severe pre-eclampsia and eclampsia by the national Pharmaceutical Regulatory Authority. Conclusions The case study in Zambia highlights the complexities that underlie making essential medicines available and used appropriately. The fishbone diagram is a useful theoretical framework for illustrating the complexity of translating research findings into clinical

Pressureless sintering of whisker-toughened ceramic composites

Science.gov (United States)

Tiegs, T.N.

1993-05-04

A pressureless sintering method is disclosed for use in the production of whisker-toughened ceramic composites wherein the sintered density of composites containing up to about 20 vol. % SiC whiskers is improved by reducing the average aspect ratio of the whiskers to from about 10 to about 20. Sintering aids further improve the density, permitting the production of composites containing 20 vol. % SiC with sintered densities of 94% or better of theoretical density by a pressureless sintering method.

[Biomimetic mineralization of rod-like cellulose nano-whiskers and spectrum analysis].

Science.gov (United States)

Qu, Ping; Wang, Xuan; Cui, Xiao-xia; Zhang, Li-ping

2012-05-01

Cellulose nano-whiskers/nano-hydroxyapatite composite was prepared with biomimetic mineralization using rod-like cellulose nano-whiskers as template. The cellulose nano-whiskers and cellulose nano-whiskers/nano-hydroxyapatite composite were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscope-energy dispersive analysis of X-rays (SEM-EDXA). Variation and distribution of carbon, oxygen, calcium, and phosphorus in the composites were studied. The morphologies and growth mechanism of nano-hydroxyapatite were analyzed. The results showed that nano-hydroxyapatite was formed on the surface of cellulose nano-whiskers; the carbon-oxygen ratio of cellulose nano-whiskers and cellulose nano-whiskers/nano-hydroxyapatite composite was 1.81 and 1.54, respectively; the calcium-phosphorus ratio of the composite was 1.70. The nucleation of nano-hydroxyapatite was around the hydroxyl groups of cellulose nano-whiskers. It is suggested that there is coordination between the hydroxyl groups of cellulose nano-whiskers and calcium ions of nano-hydroxyapatite. The nano-hydroxyapatite can distribute in the matrix of cellulose nano-whiskers. From the atomic force microscope (AFM) images, we can see that the diameter of the spherical nano-hydroxyapatite particles was about 20 nm.

Efeitos neurotóxicos de sulfato de magnésio intratecal Efectos neurotóxicos de sulfuro de magnesio intratecal Neurotoxic effects of intrathecal magnesium sulphate

Directory of Open Access Journals (Sweden)

Levent Ozdogan

2013-02-01

ón de formaldehido al 10% en la aorta y los tejidos fueron pegados. La médula espinal se examinó y fue histopatológicamente evaluada bajo microscopio electrónico. El test de Kruskal-Wallis fue usado para la evaluación estadística. Un valor de p BACKGROUND AND OBJECTIVES: To assess the potential neurotoxic effects at the ultrastructural level of magnesium sulfate administered intrathecally as a single or multi-dose. METHODS: Our study was conducted with 24 Sprague-Dawley rats that weighed 250-300 g. After a 4-hour fast, the rats were given 10 mg.kg-1 xylazine chloride intraperitoneal and then randomly allocated into three groups. Group I (n = 8 received 0.9% normal saline, Group II (n = 8 was given one intrathecal injection of 0.02 mL of 15% magnesium sulphate, and Group III (n = 8 was given 0.02 mL of 15% magnesium sulphate once a day for seven days. The injections were given within 0.40x50 mm from the lumbar area. After seven days, the animals were sacrificed under anesthesia with an aortic injection of 10% formaldehyde and their tissues were fixed. The medulla spinalis was then examined and histopathologically evaluated under an electron microscope. The Kruskal-Wallis test was used for statistical evaluation. A value of p < .05 was considered to be statistically significant. RESULTS: Significant neurodegeneration was detected in rats given single or repeated magnesium sulphate injections compared to the control group. The histopathological evaluation score of this group was also high. CONCLUSIONS: Based on electron microscopic examination, we found that intrathecal magnesium sulphate administration induced neurodegeneration.

Anatomical pathways involved in generating and sensing rhythmic whisker movements

Directory of Open Access Journals (Sweden)

Laurens W.J. Bosman

2011-10-01

Full Text Available The rodent whisker system is widely used as a model system for investigating sensorimotor integration, neural mechanisms of complex cognitive tasks, neural development, and robotics. The whisker pathways to the barrel cortex have received considerable attention. However, many subcortical structures are paramount to the whisker system. They contribute to important processes, like filtering out salient features, integration with other senses and adaptation of the whisker system to the general behavioral state of the animal. We present here an overview of the brain regions and their connections involved in the whisker system. We do not only describe the anatomy and functional roles of the cerebral cortex, but also those of subcortical structures like the striatum, superior colliculus, cerebellum, pontomedullary reticular formation, zona incerta and anterior pretectal nucleus as well as those of level setting systems like the cholinergic, histaminergic, serotonergic and noradrenergic pathways. We conclude by discussing how these brain regions may affect each other and how they together may control the precise timing of whisker movements and coordinate whisker perception.

Surface modification and characterization of magnesium hydroxide sulfate hydrate nanowhiskers

Energy Technology Data Exchange (ETDEWEB)

Gao Chuanhui [Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100 (China); Li Xianguo, E-mail: chuanhuigao@foxmail.com [Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100 (China); Feng Lijuan; Lu Shaoyan; Liu Jinyan [Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100 (China)

2010-03-01

In order to enhance the compatibility with plastic polymers, magnesium hydroxide sulfate hydrate (MHSH) nanowhiskers were modified through grafting methyl methacrylate (MMA) on the surface of the nanowhiskers by emulsion polymerization. The influences of the reaction time, MMA monomer content, adding speed of monomer and the reaction temperature on the grafting ratio were investigated. Thermogravimetry (TG), Fourier transform infrared (FT-IR) spectroscopy, X-ray powder diffraction (XRD), scanning electron microscope (SEM), energy-dispersive X-ray (EDX) spectroscopy and surface contact angle measurement were used to characterize the effect of surface modification. The results showed that the MHSH nanowhiskers were uniformly coated by polymethyl methacrylate (PMMA), and a well-defined core-shell hybrid structure of MHSH/PMMA was obtained. The surface contact angle of the hybrid whiskers increased to 87.32 deg. from 12.71 deg. and the whiskers surface was changed from hydrophilic to lipophilic.

The development of SiC whisker fabrication technology for nuclear applications

International Nuclear Information System (INIS)

Kang, Thae Khapp; Kuk, Il Hiun; Kim, Chang Kyu; Lee, Jae Chun; Lee, Ho Jin; Park, Soon Dong; Im, Gyeong Soo

1991-02-01

Some important experiments for whisker growth reactions, fabrication processes, and experiments for fabricarion of whisker reinforced composites have been performed. In order to investigate growth reaction of SiC whiskers, a conventional carbothermic reaction was tested. Based on the results of carbothermic process, a new process called silicothermic reaction was planned and some basic experiments were performed. Reaction characteristics of silicon monoxide, core material for SiC whisker growth in both of the reactions were investigated for basic data. Additionally, a hydrofluoric acid leaching process was tested for developing SiC whisker recovery process, and powder metallurgy process and melt sqeeze process were tried to develop aluminum-SiC whisker composites. (Author)

Microstructure and growth mechanism of tin whiskers on RESn3 compounds

International Nuclear Information System (INIS)

Li Caifu; Liu Zhiquan

2013-01-01

Graphical abstract: Large amount of intact tin whiskers were firstly prepared without post handling, and their microstructures were investigated systematically with TEM. A growth model was proposed to explain the observed growth characteristics from Sn–RE alloys. - Abstract: An exclusive method was developed to prepare intact tin whiskers as transmission electron microscope specimens, and with this technique in situ observation of tin whisker growth from RESn 3 (RE = Nd, La, Ce) film specimen was first achieved. Electron irradiation was discovered to have an effect on the growth of a tin whisker through its root. Large quantities of tin whiskers with diameters from 20 nm to 10 μm and lengths ranging from 50 nm to 500 μm were formed at a growth rate of 0.1–1.8 nm s −1 on the surface of RESn 3 compounds. Most (>85%) of these tin whiskers have preferred growth directions of 〈1 0 0〉, 〈0 0 1〉, 〈1 0 1〉 and 〈1 0 3〉, as determined by statistics. This kind of tin whisker is single-crystal β-Sn even if it has growth striations, steps and kinks, and no dislocations or twin or grain boundaries were observed within the whisker body. RESn 3 compounds undergo selective oxidation during whisker growth, and the oxidation provides continuous tin atoms for tin whisker growth until they are exhausted. The driving force for whisker growth is the compressive stress resulting from the restriction of the massive volume expansion (38–43%) during the oxidation by the surface RE(OH) 3 layer. Tin atoms diffuse and flow to feed the continuous growth of tin whiskers under a compressive stress gradient formed from the extrusion of tin atoms/clusters at weak points on the surface RE(OH) 3 layers. A growth model was proposed to discuss the characteristics and growth mechanism of tin whiskers from RESn 3 compounds.

Whisker-Like Formations in Sn-3.0Ag-Pb Alloys

Directory of Open Access Journals (Sweden)

Koncz-Horváth D.

2017-06-01

Full Text Available In this study, different types of whisker-like formations of Sn-3.0Ag based alloy were presented. In the experimental process the amount of Pb element was changed between 1000 and 2000 ppm, and the furnace atmosphere and cooling rate were also modified. The novelty of this work was that whisker-like formations in macro scale size were experienced after an exothermic reaction. The whiskers of larger sizes than general provided opportunities to investigate the microstructure and the concentration nearby the whiskers. In addition, the whisker-like formations from Sn-Ag based bulk material did not only consist of pure tin but tin and silver phases. The whisker-like growth appeared in several forms including hillock, spire and nodule shaped formations in accordance with parameters. It was observed that the compound phases were clustered in many cases mainly at hillocks.

Vortex Shedding in the Wake Induced by a Real Elephant Seal Whisker

Science.gov (United States)

Turk, Jodi; Omilion, Alexis; Zhang, Wei; Kim, Jeong-Jae; Kim, Jeong-Ju; Choi, Woo-Rak; Lee, Sang-Joon

2017-11-01

Biomimicry has been adopted to create innovative solutions in a vast range of applications. One such application is the design of seal-whisker-inspired flow sensors for autonomous underwater vehicles (AUVs). In dark, cramped, and unstable terrain AUVs are not able to maneuver using visual and sonar-based navigation. Hence, it is critical to use underwater flow sensors to accurately detect minute disturbances in the surroundings. Certain seal whiskers exhibit a unique undulating three-dimensional morphology that can reduce vortex induced vibrations (VIVs) if the major axis of the whisker cross-section is aligned to the inflow. This allows the seal to precisely track prey fish upstream using solely their whiskers. The current study aims to understand the effect of a real seal whisker's morphology on the vortex shedding behavior. Despite extensive studies of wake induced by scaled whisker-like models, the vortex shedding in the wake of a real seal whisker is not well understood. A series of experiments are conducted with a high-speed Particle Imaging Velocimetry (PIV) system in a water channel to examine the vortex shedding downstream from a smooth whisker and an undulating whisker at a Reynolds number of a few hundred. Results of the vortex shedding induced by real seal whiskers can provide insights on developing high-sensitivity underwater flow sensors for AUVs and other whisker-inspired structures.

Strengthening and toughening of poly(L-lactide) composites by surface modified MgO whiskers

Energy Technology Data Exchange (ETDEWEB)

Wen, Wei [Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Luo, Binghong, E-mail: tluobh@jnu.edu.cn [Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Engineering Research Center of Artificial Organs and Materials, Ministry of Education, Guangzhou 510632 (China); Qin, Xiaopeng; Li, Cairong [Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Liu, Mingxian; Ding, Shan [Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Engineering Research Center of Artificial Organs and Materials, Ministry of Education, Guangzhou 510632 (China); Zhou, Changren, E-mail: tcrz9@jnu.edu.cn [Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Engineering Research Center of Artificial Organs and Materials, Ministry of Education, Guangzhou 510632 (China)

2015-03-30

Highlights: • The grafted PLLA chain on the surface of g-MgO whisker was ruled out by FTIR spectroscopy and TG/DTG analyses. • The excellent dispersion of g-MgO whiskers and the strong interfacial adhesion of g-MgO whiskers/PLLA composite were proved by FSEM. • Comparing to MgO particles and MgO whiskers, fibrous-like g-MgO whiskers are the most effective reinforcing and toughening fillers for PLLA. - Abstract: To improve both the strength and toughness of poly(L-lactide) (PLLA), fibrous-like MgO whiskers with diameters of 0.15–1 μm and lengths of 15–110 μm were prepared, and subsequently surface modified with L-lactide to obtain grafted MgO whiskers (g-MgO whiskers). The structures and properties of MgO whiskers and g-MgO whiskers were studied. Then, a series of MgO whiskers/PLLA and g-MgO whiskers/PLLA composites were prepared by solution casting method, for comparison, MgO particles/PLLA composite was prepared too. The resulting composites were evaluated in terms of hydrophilicity, crystallinity, dispersion of whiskers, interfacial adhesion and mechanical performance by means of polarized optical microscopy (POM), contact angle measurement, field emission scanning electron microscope (FSEM), transmission electron microscopy (TEM) and tensile testing. The results revealed that the crystallization rate and hydrophilicity of PLLA were improved by the introduction of MgO whiskers and g-MgO whiskers. The g-MgO whiskers can disperse more uniformly in and show stronger interfacial adhesion with the matrix than MgO whiskers as a result of the surface modification. Due to the bridge effect of the whiskers and the excellent interfacial adhesion between g-MgO whiskers and PLLA, g-MgO whiskers/PLLA composites exhibited remarkably higher strength, modulus and toughness compared to the pristine PLLA, MgO particles/PLLA and MgO whiskers/PLLA composites.

A novel biomimetic whisker technology based on fiber Bragg grating and its application

Science.gov (United States)

Zhao, Chenlu; Jiang, Qi; Li, Yibin

2017-09-01

The paper describes a novel, biomimetic whisker-based sensing technology following the basic design of the facial whiskers of animals such as rats and mice. The sensor consists of a 3× 2 whisker array on each side of a robot. In experiments with the artificial whiskers, the motor drives rotating whiskers, and the center wavelength of a fiber Bragg grating pasted on the whisker will shift when the whisker touches an obstacle. The distance will be obtained by processing the wavelength shift data with algorithms. Then the shape recognition can be realized by postprocessing the distance data. The experimental results prove that the whisker array is capable of accurately gathering the distance and shape information of an object.

Tin Whisker Growth and Mitigation with a Nanocrysytalline Nickel Coating

Science.gov (United States)

Janiuk, Szymon

Tin whiskers are a problem in the electronics industry since the EU banned the use of lead in Pb-Sn solders as part of the Restriction of Hazardous Substances (RoHS). The biggest concern with Sn whiskers is their ability to short-circuit electronics. High reliability applications such as the aerospace, defense, healthcare, and automotive industries are at most risk. This project explores Sn whisker mitigation and prevention with the use of nanocrystalline nickel coating over Sn surfaces. Sn was plated onto a pure Cu substrate using electroplating. A high temperature and high humidity condition, at 85°C and 85% RH, was effective at growing whiskers. A nNi coating was plated over Sn/Cu coupons. After subjecting the nNi/ Sn/Cu samples through 85°C/85% RH testing conditions, no whiskers were observed penetrating the surface. These results make nNi a viable material to use as a coating to prevent the growth of Sn whiskers in electronic assemblies.

Impurity characterization of magnesium diuranate using simultaneous TG–DTA–FTIR measurements

Energy Technology Data Exchange (ETDEWEB)

Raje, Naina, E-mail: nraje@barc.gov.in [Analytical Chemistry Division, B.A.R.C., Mumbai 400 085 (India); Ghonge, Darshana K. [Analytical Chemistry Division, B.A.R.C., Mumbai 400 085 (India); Hemantha Rao, G.V.S. [NFC, ECIL Post, Hyderabad (India); Reddy, A.V.R. [Analytical Chemistry Division, B.A.R.C., Mumbai 400 085 (India)

2013-05-15

Current studies describe the application of simultaneous thermogravimetry–differential thermal analysis – evolved gas analysis techniques for the compositional characterization of magnesium diuranate (MDU) with respect to the impurities present in the matrix. The stoichiometric composition of MDU was identified as MgU{sub 2}O{sub 7}⋅3H{sub 2}O. Presence of carbonate and sulphate as impurities in the matrix was confirmed through the evolved gas analysis using Fourier Transformation Infrared Spectrometry detection. Carbon and magnesium hydroxide content present as impurities in magnesium diuranate have been determined quantitatively using TG and FTIR techniques and the results are in good agreement. Powder X-ray diffraction analysis of magnesium diuranate suggests the presence of magnesium hydroxide as impurity in the matrix. Also these studies confirm the formation of magnesium uranate, uranium sesquioxide and uranium dioxide above 1000 °C, due to the decomposition of magnesium diuranate.

Peripheral optogenetic stimulation induces whisker movement and sensory perception in head-fixed mice.

Science.gov (United States)

Park, Sunmee; Bandi, Akhil; Lee, Christian R; Margolis, David J

2016-06-08

We discovered that optical stimulation of the mystacial pad in Emx1-Cre;Ai27D transgenic mice induces whisker movements due to activation of ChR2 expressed in muscles controlling retraction and protraction. Using high-speed videography in anesthetized mice, we characterize the amplitude of whisker protractions evoked by varying the intensity, duration, and frequency of optogenetic stimulation. Recordings from primary somatosensory cortex (S1) in anesthetized mice indicated that optogenetic whisker pad stimulation evokes robust yet longer latency responses than mechanical whisker stimulation. In head-fixed mice trained to report optogenetic whisker pad stimulation, psychometric curves showed similar dependence on stimulus duration as evoked whisker movements and S1 activity. Furthermore, optogenetic stimulation of S1 in expert mice was sufficient to substitute for peripheral stimulation. We conclude that whisker protractions evoked by optogenetic activation of whisker pad muscles results in cortical activity and sensory perception, consistent with the coding of evoked whisker movements by reafferent sensory input.

Controlled growth of filamentary crystals and fabrication of single-crystal whisker probes

International Nuclear Information System (INIS)

Givargizov, E. I.

2006-01-01

The growth of filamentary crystals (whiskers) on a single-crystal substrate through the vapour-liquid-solid mechanism is described. The possibility of fabricating oriented systems of whiskers on the basis of this mechanism of crystal growth is noted. A phenomenon that is important for nanotechnology is noted: the existence of a critical diameter of whiskers, below which they are not formed. The phenomenon of radial periodic instability, which is characteristic of nanowhiskers, is described and the ways of its elimination are shown. The possibility of transforming whiskers into single-crystal tips and the growth of crystalline diamond particles at their apices are noted as important for practice. Possible applications of systems of whiskers and tips are described briefly. Particular attention is paid to the latest direction in whisker technology-fabrication of single-crystal whisker probes for atomic force microscopy

Quantifying the Effect of Stress on Sn Whisker Nucleation Kinetics

Science.gov (United States)

Chason, Eric; Vasquez, Justin; Pei, Fei; Jain, Nupur; Hitt, Andrew

2018-01-01

Although Sn whiskers have been studied extensively, there is still a need to understand the driving forces behind whisker nucleation and growth. Many studies point to the role of stress, but confirming this requires a quantitative comparison between controlled stress and the resulting whisker evolution. Recent experimental studies applied stress to a Sn layer via thermal cycling and simultaneously monitored the evolution of the temperature, stress and number of nuclei. In this work, we analyze these nucleation kinetics in terms of classical nucleation theory to relate the observed behavior to underlying mechanisms including a stress dependent activation energy and a temperature and stress-dependent whisker growth rate. Non-linear least squares fitting of the data taken at different temperatures and strain rates to the model shows that the results can be understood in terms of stress decreasing the barrier for whisker nucleation.

Design of the Intravenous Magnesium Efficacy in Acute Stroke (IMAGES) trial

OpenAIRE

Bradford, A.; Lees, K.

2000-01-01

The Intravenous Magnesium Efficacy in Acute Stroke (IMAGES) trial is a multicentre,randomised, placebo-controlled trial of magnesium sulphate (MgSO4) funded by the UK Medical Research Council. When complete, it will be the largest single neuroprotective study undertaken to date. Conscious patients presenting within 12 h of acute stroke with limb weakness are eligible. The primary outcome measure is combined death and disability as measured using the Barthel Index at 90-day follow up. By rando...

Microstructure and fracture in SiC whisker reinforced 2124 aluminum composite

Science.gov (United States)

Nieh, T. G.; Raninen, R. A.; Chellman, D. J.

1985-01-01

The microstructures of extruded and hot-rolled 2124 Al-15 percent (by weight) SiC whisker composites have been investigated, experimentally. Among the specific factors studied were: the strength of the whisker-matrix interfaces; (2) the presence of oxides; (3) the presence of defective whiskers; (4) and the presence of distribution of intermetallic compounds, impurities in the SiC(w) powder, and microstructural inhomogeneities. Modifications in the microstructure of the SiC/AL composites due to hot rolling and extrusion are illustrated in a series of microphotographs. It was found that hot rolling along the axis of extrusion was associated with some types of whisker damage, while the whiskers still retain their original orientation. Hot-rolling perpendicular to the axis of extrusion, however, tended to rotate the whiskers and produced a nearly isotropic material. Whisker free zones were virtually eliminated or reduced in size by hot rolling. In situ Auger fractography of the composite showed that the interfacial bonding between the SiC and the Al matrix was good and that Al2O2 had no significant influence on the fracture mechanics of the composite.

Understanding and predicting metallic whisker growth and its effects on reliability : LDRD final report.

Energy Technology Data Exchange (ETDEWEB)

Michael, Joseph Richard; Grant, Richard P.; Rodriguez, Mark Andrew; Pillars, Jamin; Susan, Donald Francis; McKenzie, Bonnie Beth; Yelton, William Graham

2012-01-01

Tin (Sn) whiskers are conductive Sn filaments that grow from Sn-plated surfaces, such as surface finishes on electronic packages. The phenomenon of Sn whiskering has become a concern in recent years due to requirements for lead (Pb)-free soldering and surface finishes in commercial electronics. Pure Sn finishes are more prone to whisker growth than their Sn-Pb counterparts and high profile failures due to whisker formation (causing short circuits) in space applications have been documented. At Sandia, Sn whiskers are of interest due to increased use of Pb-free commercial off-the-shelf (COTS) parts and possible future requirements for Pb-free solders and surface finishes in high-reliability microelectronics. Lead-free solders and surface finishes are currently being used or considered for several Sandia applications. Despite the long history of Sn whisker research and the recently renewed interest in this topic, a comprehensive understanding of whisker growth remains elusive. This report describes recent research on characterization of Sn whiskers with the aim of understanding the underlying whisker growth mechanism(s). The report is divided into four sections and an Appendix. In Section 1, the Sn plating process is summarized. Specifically, the Sn plating parameters that were successful in producing samples with whiskers will be reviewed. In Section 2, the scanning electron microscopy (SEM) of Sn whiskers and time-lapse SEM studies of whisker growth will be discussed. This discussion includes the characterization of straight as well as kinked whiskers. In Section 3, a detailed discussion is given of SEM/EBSD (electron backscatter diffraction) techniques developed to determine the crystallography of Sn whiskers. In Section 4, these SEM/EBSD methods are employed to determine the crystallography of Sn whiskers, with a statistically significant number of whiskers analyzed. This is the largest study of Sn whisker crystallography ever reported. This section includes a

Magnesium sulphate’s influence on calcium carbonate minerals

DEFF Research Database (Denmark)

Nielsen, Mia Rohde

The purpose of this PhD thesis was to explore the influence of magnesium sulphate (MgSO4 (aq)) on calcium carbonate (CaCO3) minerals and what role the MgSO40 ion pair had. CaCO3 minerals are abundant and widespread on Earth, particularly in marine environments, and have been so throughout Earth...

A radial map of multi-whisker correlation selectivity in the rat barrel cortex.

Science.gov (United States)

Estebanez, Luc; Bertherat, Julien; Shulz, Daniel E; Bourdieu, Laurent; Léger, Jean-François

2016-11-21

In the barrel cortex, several features of single-whisker stimuli are organized in functional maps. The barrel cortex also encodes spatio-temporal correlation patterns of multi-whisker inputs, but so far the cortical mapping of neurons tuned to such input statistics is unknown. Here we report that layer 2/3 of the rat barrel cortex contains an additional functional map based on neuronal tuning to correlated versus uncorrelated multi-whisker stimuli: neuron responses to uncorrelated multi-whisker stimulation are strongest above barrel centres, whereas neuron responses to correlated and anti-correlated multi-whisker stimulation peak above the barrel-septal borders, forming rings of multi-whisker synchrony-preferring cells.

Numerical study of whisker field lines in the periphery of the Large Helical Device

International Nuclear Information System (INIS)

Akao, Hideki

1990-01-01

The behavior of periphery magnetic field lines in the standard Large-Helical Device (l=2 heliotron/torsatron type) configuration is studied numerically. Three different types of behavior are found, corresponding to three different regions: the stochastic region near the outermost magnetic surface, the whisker region, and the inter-whisker region outside the stochastic region. The behavior of whisker and inter-whisker field lines is specifically analyzed. It is found that whisker field lines exhibit both regular and irregular types of behavior, whereas inter-whisker field lines exhibit only regular behavior. The connection lengths for the whisker field lines are usually as long as several tens of toroidal pitches, whereas those for the inter-whisker field lines are usually less than ten toroidal pitch lengths. Whisker field lines are characterized by three fundamental processes; stretching, folding, and nesting associated with the motion of a residual X-point of the separatrix. Simple modeling is performed to reproduce these three fundamental processes. (author)

Management of Eclampsia at AKTH: Before and After Magnesium ...

African Journals Online (AJOL)

This study is aimed to evaluate the effect of the introduction of magnesium sulphate for the management of eclamptic seizures on maternal and fetal indices in Aminu Kano Teaching Hospital [AKTH], Kano. A retrospective study of all patients who presented with eclampsia in AKTH, Kano. The study period included 3years ...

Microwave absorption behaviors of tetra-needle-like ZnO whiskers

International Nuclear Information System (INIS)

Zhou Zuowan; Chu Longsheng; Hu Shuchun

2006-01-01

A novel type of microwave absorption coating was prepared using tetra-needle-like zinc oxide whiskers as the main functional agent. The results of the experiments show that the composite coatings containing ZnO whisker appear to have good efficiency of microwave absorption, and the effect is influenced by the aspect ratio (length to diameter, L/D), the content of the T-ZnO whiskers and the resistivity of the whiskers. Microwave-heat transformation of this kind of whisker and its composite was investigated, and the results indicated that the apparent density affected the efficiency of the heat generating. The suitable value of the apparent density is 0.16-0.18 g/cm 3 . The mechanism of microwave absorption and microwave-heat transformation was explained by the semiconductive networks formed by the tetra-needle shape, diffuse reflections results from quasi-antenna, multipoles due to charge concentration and the multi-interfaces in the composites

Synthesis of whiskers of SiC microwave assisted; Sintesis de whiskers de SiC asistida por microondas

Energy Technology Data Exchange (ETDEWEB)

Garza-Mendez, F. J.; Vanegas, A. J.; Vazquez, B. A.; Garza-Paz, J.

2013-06-01

We developed a new process for the synthesis of SiC whiskers assisted by microwaves; this is based on the mixture of silica xerogels and graphite powder. As energy source were used microwaves of 2.45 GHz and 1.0 kW of power RMS. On the other hand, mesoporous silica was synthesized via sol-gel, the precursors used were TEOS/H{sub 2}O and ethanol. Through analysis of the BET is determined the value of average pore size (3.0 nm) and the surface area (1090 m2/g).By mean of X-Ray diffraction it was demonstrated that the silica obtained is an amorphous solid and, the powders obtained in the microwave synthesis are {beta}-SiC. Synthesized SiC powders were observed using a SEM in secondary electron mode, it was observed that this powders consists of SiC whiskers. The effect of microwaves on the synthesis of whiskers of SiC is discussed in the present work. (Author) 19 refs.

A comparison of intraperitoneal bupivacaine-tramadol with bupivacaine-magnesium sulphate for pain relief after laparoscopic cholecystectomy: A prospective, randomised study

Directory of Open Access Journals (Sweden)

Anurag Yadava

2016-01-01

Full Text Available Background and Aims: In laparoscopic surgeries, intraperitoneal instillation of local anaesthetics and opioids is gaining popularity, for better pain relief. This study compared the quality and duration of post-operative analgesia using intraperitoneal tramadol plus bupivacaine (TB or magnesium plus bupivacaine (MB. Methods: In this study, 186 patients undergoing laparoscopic cholecystectomy were randomly divided into two groups: group TB received intraperitoneal tramadol with bupivacaine and group MB received intraperitoneal magnesium sulphate (MgSO 4 with bupivacaine. The visual analogue scale (VAS to assess pain, haemodynamic variables and side effects were noted and compared at different time points. The primary outcome was to compare the analgesic efficacy and duration of pain relief. The secondary outcomes included comparison of haemodynamic parameters and side effects among the two groups. The data analysis was carried out with unpaired Student′s t-test and Chi-square test using software SPSS 20.0 version. Results: The mean of VAS pain score after 1, 2, 4, 6 and 24 h of surgery was more in TB group compared to MB group, and the difference was statistically significant (P < 0.05. The total rescue analgesia consumption in 24 h after surgery was 2.4 g (mean of paracetamol in TB group and 1.4 g (mean of paracetamol in MB group which was statistically significant (P < 0.05. There were no statistically significant differences in the secondary outcomes. Conclusion: Intraperitoneal instillation of bupivacaine-MgSO 4 renders patients relatively pain-free in first 24 h after surgery, with longer duration of pain-free period and less consumption of rescue analgesic as compared to bupivacaine-tramadol combination.

Sulphate solubility and sulphate diffusion in oxide glasses: implications for the containment of sulphate-bearing nuclear wastes

International Nuclear Information System (INIS)

Lenoir, M.

2009-09-01

The thesis deals with sulphate solubility and sulphate diffusion in oxide glasses, in order to control sulphate incorporation and sulphate volatilization in nuclear waste glasses. It was conducted on simplified compositions, in the SiO 2 -B 2 O 3 -R 2 O (R = Li, Na, K, Cs), SiO 2 -B 2 O 3 -BaO and V 2 O 5 -B 2 O 3 -BaO systems. These compositions allowed us to study the influence of the nature of network-modifying ions (Li + , Na + , K + , Cs + or Ba 2+ ) and also of former elements (Si, B, V), on structure and properties of glasses. Sulphate volatility is studied in sodium borosilicate melts using an innovative technique of sulphate quantitation with Raman spectroscopy. This technique is useful to obtain kinetic curves of sulphate volatilization. The establishment of a model to fit these curves leads to the determination of diffusion coefficients of sulphate. These diffusion coefficients can thus be compared to diffusion coefficients of other species, determined by other techniques and presented in the literature. They are also linked to diffusion coefficients in relation with the viscosity of the melts. Concerning sulphate solubility in glasses, it depends on glass composition and on the nature of sulphate incorporated. Sulphate incorporation in alkali borosilicate glasses leads to the formation of a sulphate layer floating on top of the melt. Sulphate incorporation in barium borosilicate and boro-vanadate glasses leads to the crystallization of sulphate species inside the vitreous matrix. Moreover, sulphate solubility is higher in these glasses than in alkali borosilicates. Finally, exchanges between cations present in glasses and cations present in the sulphate phase are also studied. (author)

Bacterial Reduction Of Barium Sulphate By Sulphate-Reducing Bacteria

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Luptáková Alena

2015-12-01

Full Text Available Acid mine drainage (AMD is a worldwide problem leading to contamination of water sources. AMD are characterized by low pH and high content of heavy metals and sulphates. The barium salts application presents one of the methods for the sulphates removing from AMD. Barium chloride, barium hydroxide and barium sulphide are used for the sulphates precipitation in the form of barium sulphate. Because of high investment costs of barium salts, barium sulphide is recycled from barium sulphate precipitates. It can be recycled by thermic or bacterial reduction of barium sulphate. The aim of our study was to verify experimentally the possibility of the bacterial transformation of BaSO4 to BaS by sulphate-reducing bacteria. Applied BaSO4 came from experiments of sulphates removal from Smolnik AMD using BaCl2.

Synthesis and growth mechanisms of ZrC whiskers fabricated by a VLS process

Energy Technology Data Exchange (ETDEWEB)

Lee, Dongju [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of). Nuclear Materials Development Division; Song, Sung Ho [Kongju National Univ., Chungnam (Korea, Republic of). Division of Advanced Materials Engineering

2017-08-15

The mechanisms of nano-sized ZrC whisker formation by a vapor-liquid-solid process (VLS) are investigated, which produces a very high purity, single crystal whisker. Rectangular ZrC whiskers with a cross-sectional diameter of 100-200 nm and lengths up to tens of microns are formed under the catalytic effect of nickel. The ZrC whiskers are characterized using scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. ZrC whiskers can be used as a potential reinforcing and strengthening phase for ceramic composites.

Removal of sulphates from waste waters by sulphate-reducing bacteria

Directory of Open Access Journals (Sweden)

Luptáková Alena

2002-03-01

Full Text Available are present in almost all types of water, usually as a simple anion SO42-. The sulphates together with hydrogencarbonates and chlorides are principal anions in natural waters. In typical underground and surface waters, the concentration of sulphates is in the range from ten to hundreds milligrams per litre.Nowadays, the importance of the control of sulphate concentration in waste waters increases. According to the Slovak legislation the limit concentration of sulphates in surface and drinking waters is 250 mg.l-1 . In rivers the contents of sulphates increases mainly by the discharge of waste waters, which are coming mainly from chemical, textile, metallurgical, pharmaceutical, paper and mining industry. The concentration of sulphates in these waters is in the order of grams per litre.Many technologies for the sulphates removal from waste waters exist, including biologico-chemical processes. The principle of one of these methods is the reduction of sulphates by sulphate-reducing bacteria to hydrogen-sulphide.The objective of this work was to study the effect of initial sulphates concentration on the activity of anaerobic sulphate reducers as well as the kinetics of the anaerobic sulphate reduction. The batch reactor was used at temperature of 30°C and pH 7,5. Lactate was used as the carbon source.

Fabrication of α-chitin whisker-reinforced poly(vinyl alcohol) nanocomposite nanofibres by electrospinning

International Nuclear Information System (INIS)

Junkasem, Jirawut; Rujiravanit, Ratana; Supaphol, Pitt

2006-01-01

The present contribution reports, for the first time, the successful fabrication of α-chitin whisker-reinforced poly(vinyl alcohol) (PVA) nanocomposite nanofibres by electrospinning. The α-chitin whiskers were prepared from α-chitin flakes from shrimp shells by acid hydrolysis. The as-prepared chitin whiskers exhibited lengths in the range 231-969 nm and widths in the range 12-65 nm, with the average length and width being about 549 and 31 nm, respectively. Successful incorporation of the chitin whiskers within the as-spun PVA/chitin whisker nanocomposite nanofibres was verified by infrared spectroscopic and thermogravimetric methods. The incorporation of chitin whiskers within the as-spun nanocomposite fibre mats increased the Young's modulus by about 4-8 times over that of the neat as-spun PVA fibre mat

Calcium silicate ceramic scaffolds toughened with hydroxyapatite whiskers for bone tissue engineering

International Nuclear Information System (INIS)

Feng, Pei; Wei, Pingpin; Li, Pengjian; Gao, Chengde; Shuai, Cijun; Peng, Shuping

2014-01-01

Calcium silicate possessed excellent biocompatibility, bioactivity and degradability, while the high brittleness limited its application in load-bearing sites. Hydroxyapatite whiskers ranging from 0 to 30 wt.% were incorporated into the calcium silicate matrix to improve the strength and fracture resistance. Porous scaffolds were fabricated by selective laser sintering. The effects of hydroxyapatite whiskers on the mechanical properties and toughening mechanisms were investigated. The results showed that the scaffolds had a uniform and continuous inner network with the pore size ranging between 0.5 mm and 0.8 mm. The mechanical properties were enhanced with increasing hydroxyapatite whiskers, reached a maximum at 20 wt.% (compressive strength: 27.28 MPa, compressive Young's modulus: 156.2 MPa, flexural strength: 15.64 MPa and fracture toughness: 1.43 MPa·m 1/2 ) and then decreased by addition of more hydroxyapatite whiskers. The improvement of mechanical properties was due to whisker pull-out, crack deflection and crack bridging. Moreover, the degradation rate decreased with the increase of hydroxyapatite whisker content. A layer of bone-like apatite was formed on the scaffold surfaces after being soaked in simulated body fluid. Human osteoblast-like MG-63 cells spread well on the scaffolds and proliferated with increasing culture time. These findings suggested that the calcium silicate scaffolds reinforced with hydroxyapatite whiskers showed great potential for bone regeneration and tissue engineering applications. - Highlights: • HA whiskers were incorporated into CS to improve the properties. • The scaffolds were successfully fabricated by SLS. • Toughening mechanisms was whisker pull-out, crack deflection and bridging. • The scaffolds showed excellent apatite forming ability

Calcium silicate ceramic scaffolds toughened with hydroxyapatite whiskers for bone tissue engineering

Energy Technology Data Exchange (ETDEWEB)

Feng, Pei [State Key Laboratory of High Performance Complex Manufacturing, Central South University, Changsha 410083, PR China, (China); Wei, Pingpin [Cancer Research Institute, Central South University, Changsha 410078 (China); Li, Pengjian; Gao, Chengde [State Key Laboratory of High Performance Complex Manufacturing, Central South University, Changsha 410083, PR China, (China); Shuai, Cijun, E-mail: shuai@csu.edu.cn [State Key Laboratory of High Performance Complex Manufacturing, Central South University, Changsha 410083, PR China, (China); Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, SC 29425 (United States); Peng, Shuping, E-mail: shuping@csu.edu.cn [Cancer Research Institute, Central South University, Changsha 410078 (China)

2014-11-15

Calcium silicate possessed excellent biocompatibility, bioactivity and degradability, while the high brittleness limited its application in load-bearing sites. Hydroxyapatite whiskers ranging from 0 to 30 wt.% were incorporated into the calcium silicate matrix to improve the strength and fracture resistance. Porous scaffolds were fabricated by selective laser sintering. The effects of hydroxyapatite whiskers on the mechanical properties and toughening mechanisms were investigated. The results showed that the scaffolds had a uniform and continuous inner network with the pore size ranging between 0.5 mm and 0.8 mm. The mechanical properties were enhanced with increasing hydroxyapatite whiskers, reached a maximum at 20 wt.% (compressive strength: 27.28 MPa, compressive Young's modulus: 156.2 MPa, flexural strength: 15.64 MPa and fracture toughness: 1.43 MPa·m{sup 1/2}) and then decreased by addition of more hydroxyapatite whiskers. The improvement of mechanical properties was due to whisker pull-out, crack deflection and crack bridging. Moreover, the degradation rate decreased with the increase of hydroxyapatite whisker content. A layer of bone-like apatite was formed on the scaffold surfaces after being soaked in simulated body fluid. Human osteoblast-like MG-63 cells spread well on the scaffolds and proliferated with increasing culture time. These findings suggested that the calcium silicate scaffolds reinforced with hydroxyapatite whiskers showed great potential for bone regeneration and tissue engineering applications. - Highlights: • HA whiskers were incorporated into CS to improve the properties. • The scaffolds were successfully fabricated by SLS. • Toughening mechanisms was whisker pull-out, crack deflection and bridging. • The scaffolds showed excellent apatite forming ability.

Design of the Intravenous Magnesium Efficacy in Acute Stroke (IMAGES) trial [ISRCTN19943732

OpenAIRE

Bradford, Andrew; Lees, Kennedy

2000-01-01

Abstract The Intravenous Magnesium Efficacy in Acute Stroke (IMAGES) trial is a multicentre,randomised, placebo-controlled trial of magnesium sulphate (MgSO4) funded by the UK Medical Research Council. When complete, it will be the largest single neuroprotective study undertaken to date. Conscious patients presenting within 12 h of acute stroke with limb weakness are eligible. The primary outcome measure is combined death and disability as measured using the Barthel Index at 90-day follow up....

The development of SiC whisker fabrication technology for nuclear applications

International Nuclear Information System (INIS)

Kang, Thae Khapp; Kuk, Il Hiun; Lee, Jae Chun; Rhee, Chang Kyu; Lee, Ho Jin; Park, Soon Dong

1990-02-01

Important process factors of carbothermic process for the growth of SiC whiskers were investigated. The crystalline form of silicon dioxide, amount of carbon addition, graphite, silicon, catalysts, additive and reaction temperature were chosen as the main factors. Morphology of the resultant products was grouped into 3 different types; whisker,noodle and power types. The addition of catalyst affected in most the formation of SiC whiskers. Effects of catalyst and additive additions and reaction atmospheres on the morphology anf growth of SiC whiskers were investigated, silicon monoxide power and carbon monoxide gas were used as the raw materials. The addition of an iron containing catalyst resulted in a very long thread-like growth of the whiskers, while that of sodium chloride helical curlings. Addition of hydrogen to the non-oxidizing atmosphere enhanced the whisker formations. Crystallization of amorphous silicon monoxide raw powder was investigated at high temperatures up to 1500 deg C in Ar atmosphere using graphite crucible. Up to 900 deg C no crystallization occurred, while at 1100 - 1300 deg C silicon formation, and at 1500 deg C silicon dioxide and silicon carbide formations were detected. A slight weight loss began 1300 deg C, and the weight loss became about 33 % at 1500 deg C. After the formation reaction of SiC whiskers, the reaction products were leached by hydrofluoric acids. The optimum concentration of the hydrofluoric acid was 2 %. (author)

Nanoreinforced biocompatible hydrogels from wood hemicelluloses and cellulose whiskers

Science.gov (United States)

Muzaffer Ahmet Karaaslan; Mandla A. Tshabalala; Daniel J. Yelle; Gisela Buschle-Diller

2011-01-01

Nanoreinforced hydrogels with a unique network structure were prepared from wood cellulose whiskers coated with chemically modified wood hemicelluloses. The hemicelluloses were modified with 2-hydroxyethylmethacrylate prior to adsorption onto the cellulose whiskers in aqueous medium. Synthesis of the hydrogels was accomplished by in situ radical polymerization of the...

Effect of TiC whisker addition on properties of YG1OF alloy

Institute of Scientific and Technical Information of China (English)

无

2007-01-01

The cemented carbide material (YG10F) with different additions of TiC whisker (0%, 0.3%, 0.6%, mass fraction) was prepared by different techniques. The effect of TiC whisker addition on the density, microhardness and toughness of the experimental material was investigated. The results indicate that after the wet-milling for 8 h and sintering in vacuum at 1 440 ℃, the toughness of YG10F is remarkably improved and meanwhile higher microhardness is obtained by 0.3% TiC whisker addition. Preliminary analysis suggests that the main toughening mechanism of TiC whisker in YG10F is whisker pull-out and bridging phenomena.

Muscular Basis of Whisker Torsion in Mice and Rats.

Science.gov (United States)

Haidarliu, Sebastian; Bagdasarian, Knarik; Shinde, Namrata; Ahissar, Ehud

2017-09-01

Whisking mammals move their whiskers in the rostrocaudal and dorsoventral directions with simultaneous rolling about their long axes (torsion). Whereas muscular control of the first two types of whisker movement was already established, the anatomic muscular substrate of the whisker torsion remains unclear. Specifically, it was not clear whether torsion is induced by asymmetrical operation of known muscles or by other largely unknown muscles. Here, we report that mystacial pads of newborn and adult rats and mice contain oblique intrinsic muscles (OMs) that connect diagonally adjacent vibrissa follicles. Each of the OMs is supplied by a cluster of motor end plates. In rows A and B, OMs connect the ventral part of the rostral follicle with the dorsal part of the caudal follicle. In rows C-E, in contrast, OMs connect the dorsal part of the rostral follicle to the ventral part of the caudal follicle. This inverse architecture is consistent with previous behavioral observations [Knutsen et al.: Neuron 59 (2008) 35-42]. In newborn mice, torsion occurred in irregular single twitches. In adult anesthetized rats, microelectrode mediated electrical stimulation of an individual OM that is coupled with two adjacent whiskers was sufficient to induce a unidirectional torsion of both whiskers. Torsional movement was associated with protracting movement, indicating that in the vibrissal system, like in the ocular system, torsional movement is mechanically coupled to horizontal and vertical movements. This study shows that torsional whisker rotation is mediated by specific OMs whose morphology and attachment sites determine rotation direction and mechanical coupling, and motor innervation determines rotation dynamics. Anat Rec, 300:1643-1653, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Sulphate in Pregnancy

Directory of Open Access Journals (Sweden)

Paul A. Dawson

2015-03-01

Full Text Available Sulphate is an obligate nutrient for healthy growth and development. Sulphate conjugation (sulphonation of proteoglycans maintains the structure and function of tissues. Sulphonation also regulates the bioactivity of steroids, thyroid hormone, bile acids, catecholamines and cholecystokinin, and detoxifies certain xenobiotics and pharmacological drugs. In adults and children, sulphate is obtained from the diet and from the intracellular metabolism of sulphur-containing amino acids. Dietary sulphate intake can vary greatly and is dependent on the type of food consumed and source of drinking water. Once ingested, sulphate is absorbed into circulation where its level is maintained at approximately 300 μmol/L, making sulphate the fourth most abundant anion in plasma. In pregnant women, circulating sulphate concentrations increase by twofold with levels peaking in late gestation. This increased sulphataemia, which is mediated by up-regulation of sulphate reabsorption in the maternal kidneys, provides a reservoir of sulphate to meet the gestational needs of the developing foetus. The foetus has negligible capacity to generate sulphate and thereby, is completely reliant on sulphate supply from the maternal circulation. Maternal hyposulphataemia leads to foetal sulphate deficiency and late gestational foetal death in mice. In humans, reduced sulphonation capacity has been linked to skeletal dysplasias, ranging from the mildest form, multiple epiphyseal dysplasia, to achondrogenesis Type IB, which results in severe skeletal underdevelopment and death in utero or shortly after birth. Despite being essential for numerous cellular and metabolic functions, the nutrient sulphate is largely unappreciated in clinical settings. This article will review the physiological roles and regulation of sulphate during pregnancy, with a particular focus on animal models of disturbed sulphate homeostasis and links to human pathophysiology.

Tin Whisker Formation — A Stress Relieve Phenomenon

Science.gov (United States)

Dittes, M.; Oberndorff, P.; Crema, P.; Su, P.

2006-02-01

With the move towards lead-free electronics also the solderable finish of electronic components' terminations are converted. While the typical finish was containing 5 % to 20 % lead (Pb) and thus was almost whisker free, lead (Pb)-free finishes such as pure tin or high tin alloys are rather prone to grow whisker. These whiskers are spontaneous protrusions that grow to a significant length of up to millimeters with a typical diameter in the range of few microns and are suspect to cause shorts in electronic assemblies. The latest details of the mechanisms are not yet understood. However it appears to be well established that the driving force for tin whisker growth is a compressive stress in the tin layer and that this stress is released by whisker formation. Besides the mechanism for whisker growth therefore the mechanism of the stress induction is of interest. The origin of that stress may have multiple sources. Among others the most important one is the volume increase within the tin layer due the formation of intermetallics at the interface to the base material. This applies to all copper based material. For base materials with a coefficient of thermal expansion (cte) significantly different from the tin finish another mechanism plays the dominant role. This is the induction of stress during thermal cycling due to the different expansion of the materials with every temperature change. Another mechanism for stress induction may be the oxidation of the finish, which also leads to a local volume increase. Based on the knowledge of stress induction various mitigation strategies can be deducted. Most common is the introduction of a diffusion barrier (e.g. Ni) in order to prevent the growth of the Cu-Sn intermetallics, the controlled growth of Cu-Sn intermetallics in order to prevent their irregularity or the introduction of a mechanical buffer material targeting at the minimisation of the cte mismatch between base and finish material. With respect to the stress

COMPARATIVE STUDY OF DEXMEDETOMIDINE AND MAGNESIUM SULPHATE AS AN ADJUVANT TO BUPIVACAINE IN SPINAL ANESTHESIA

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Rakesh Kumar

2015-08-01

Full Text Available INTRODUCTI ON: spinal anaesthesia is a widely used simple anaesthethetic technique providing adequate analgesia and muscle relaxation. Search for an adjuvant providing satisfactory intra and post - operative analgesia is still continuing. This study aims to compare the dexmedetomidine and magnesium sulphate as an adjuvant to spi nal anaesthesia. MATERIAL AND METHODS: After obtaining institutional ethical committee approval and written informed consent from patients 90 ASA grade I &II patients of either sex having height between 140 - 180 cm and weight between 40 - 90 kg were randomly divided in 3 groups of 30 patients each (n=30. Group C: Received 3.0 ml 0.5% bupivacaine heavy + 0.5 ml NS . Group M: Received 3.0 ml 0.5% bupivacaine heavy + 50 mg MgSO 4 diluted to 0.5 ml of NS . Group D: Received 3.0 ml 0.5% bupivacaine heavy 10 +dexmedet omidine 10μg diluted to 0.5 ml NS . RESULTS: onset of sensory and motor block was delayed in Group M as compared to group D and group C. Onset of sensory and motor block in group D was significantly faster as compared to group C and group M. Total duration of sensory anaesthesia, duration of sensory block and duration of motor block was significantly prolonged in group D as compared to group M and group C. Patients were hemodynamically stable in all the groups. There were no incidences of any significant adv erse effect in any group. CONCLUSION: intrathecal dexmedetomidine is a better adjuvant to intrathecal bupivacaine because of rapid onset of sensory and motor blockade and prolonged duration of sensory and motor blockade without any potential side effects

Effect of linear alcohol molecular size on the self-assembly of fullerene whiskers

International Nuclear Information System (INIS)

Amer, Maher S.; Todd, T. Kyle; Busbee, John D.

2011-01-01

Highlights: → The longer the alcohol molecule, the shorter the length of the assembled whisker. → Interaction between alcohol and fullerene solvent is the key factor. → The stronger the alcohol/solvent interaction, the longer the whisker. - Abstract: The recent development of self-assembled fullerene whiskers and wires has created an enormous potential and resolved a serious challenge for utilizing such unique class of carbon material in advanced nano-scale, molecular-based electronic, optical, and thermal devices. In this paper we investigate, the self-assembly of C 60 molecules into one-dimensional whiskers using a series of linear alcohols H(CH 2 ) n OH, with n changing from 1 (methanol) to 3 (isopropyl alcohol), to elucidate the effect of alcohol molecular size on the size distribution of the self-assemble fullerene whiskers. Our results show that the length of the produced fullerene whiskers is affected by the molecular size of the alcohol used in the process. The crucial role played by solvent/alcohol interaction in the assembly process is discussed. In addition, Raman spectroscopy measurements support the notion that the self-assembled whiskers are primarily held by depletion forces and no evidence of fullerene polymerization was observed.

Precision rodent whisker stimulator with integrated servo-locked control and displacement measurement.

Science.gov (United States)

Walker, Jennifer L; Monjaraz-Fuentes, Fernanda; Pedrow, Christi R; Rector, David M

2011-03-15

We developed a high speed voice coil based whisker stimulator that delivers precise deflections of a single whisker or group of whiskers in a repeatable manner. The device is miniature, quiet, and inexpensive to build. Multiple stimulators fit together for independent stimulation of four or more whiskers. The system can be used with animals under anesthesia as well as awake animals with head-restraint, and does not require trimming the whiskers. The system can deliver 1-2 mm deflections in 2 ms resulting in velocities up to 900 mm/s to attain a wide range of evoked responses. Since auditory artifacts can influence behavioral studies using whisker stimulation, we tested potential effects of auditory noise by recording somatosensory evoked potentials (SEP) with varying auditory click levels, and with/without 80 dBa background white noise. We found that auditory clicks as low as 40 dBa significantly influence the SEP. With background white noise, auditory clicks as low as 50 dBa were still detected in components of the SEP. For behavioral studies where animals must learn to respond to whisker stimulation, these sounds must be minimized. Together, the stimulator and data system can be used for psychometric vigilance tasks, mapping of the barrel cortex and other electrophysiological paradigms. Copyright © 2010 Elsevier B.V. All rights reserved.

Mystacial Whisker Layout and Musculature in the Guinea Pig (Cavia porcellus): A Social, Diurnal Mammal.

Science.gov (United States)

Grant, Robyn A; Delaunay, Mariane G; Haidarliu, Sebastian

2017-03-01

All mammals (apart from apes and humans) have whiskers that make use of a similar muscle arrangement. Whisker specialists, such as rats and mice, tend to be nocturnal and arboreal, relying on their whisker sense of touch to guide exploration around tree canopies at night. As such, nocturnal arboreal rodents have many whiskers that are organised into a grid-like pattern, and moved using a complex array of muscles. Indeed, most arboreal, nocturnal mammals tend to have specialised whiskers that are longer and arranged in a dense, regular grid, compared with terrestrial, diurnal mammals. The guinea pig diverged early from murid rodents (around 75 million years ago), and are ground-dwelling, diurnal animals. It would be predicted that, as a terrestrial mammal, they may have less whiskers and a reduced muscle architecture compared to arboreal, nocturnal rodents. We examined the mystacial whisker layout, musculature and movement capacity of Guinea pig (Cavia porcellus) whiskers and found that they did indeed have a disorganized whisker layout, with a fortification around the eye area. In addition, there was a reduction in musculature, especially in the intrinsic muscles. Despite guinea pigs not cyclically moving their whiskers, the mystacial musculature was still very similar to that of murid rodents. We suggest that the conserved presence of whisker layout and musculature, even in visual mammals such as primates and guinea pigs, may indicate that whiskers still play an important role in these animals, including protecting the eyes and being involved in tactile social behaviors. Anat Rec, 300:527-536, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Development of 9Al2O3{center_dot}2B2O3 whiskers reinforced piston by squeeze casting. Manufacturing process and characteristics of whiskers preform; Squeeze cast ho ni yoru 9Al2O3{center_dot}2B2O3 whisker kyoka piston no kaihatsu

Energy Technology Data Exchange (ETDEWEB)

Yamauchi, T; Suzuki, M; Takahashi, M; Takada, I; Toda, M [Suzuki Motor Co. Ltd., Shizuoka (Japan)

1997-10-01

The properties of 9Al2O3 {center_dot} 2B2O3 whisker reinforced aluminum alloy is excellent compared with conventional material at elevated temperatures. 9Al2O3 {center_dot} 2B2O3 whisker reinforced aluminum alloy was applied to the piston head of two cycle engines. This piston was produced by a squeeze casting process with the granulated whiskers preform which was infiltrated by a molten aluminum alloy under high pressure. Since the permeability of the granulated whiskers preform is larger than that of the uniform preform in which whiskers are distributed randomly and uniformly, it became possible to suppress the preform deformation using the developed preform. 7 refs., 8 figs., 2 tabs.

Magnesium sulphate for fetal neuroprotection: benefits and challenges of a systematic knowledge translation project in Canada.

Science.gov (United States)

Teela, Katherine C; De Silva, Dane A; Chapman, Katie; Synnes, Anne R; Sawchuck, Diane; Basso, Melanie; Liston, Robert M; von Dadelszen, Peter; Magee, Laura A

2015-12-22

Administration of magnesium sulphate (MgSO4) to women with imminent preterm birth at e-learning module available to all SOGC members, and at MAG-CP participating sites, on-site educational rounds and focus group discussions, and circulation of an anonymous 'Barriers and Facilitators' survey for the systematic identification of facilitators and barriers for uptake of practice change. We compared these strategies according to: (i) breadth of respondents reached; (ii) rates and richness of identified barriers, facilitators, and knowledge needed; and (iii) cost. No individual KT method was superior to the others by all criteria, and in combination, they provided richer information than any individual method. The e-learning module reached the most diverse audience of health care providers, the site visits provided opportunity for iterative dialogue, and the survey was the least expensive. Although the site visits provided the most detailed information around individual and organizational barriers, the 'Barriers and Facilitators' survey provided more detail regarding social-level barriers. The facilitators identified varied by KT method. The type of knowledge needed was further defined by the e-learning module and surveys. Our findings suggest that a multifaceted approach to KT is optimal for translating national obstetric guidelines into clinical practice. As audit and feedback are essential parts of the process by which evidence to practice gaps are closed, MAG-CP is continuing the iterative KT process described in this paper concurrent with tracking of MgSO4 use for fetal neuroprotection and maternal and child outcomes until September 2015; results are anticipated in 2016.

Enhancing Mechanical and Thermal Properties of Epoxy Nanocomposites via Alignment of Magnetized SiC Whiskers.

Science.gov (United States)

Townsend, James; Burtovyy, Ruslan; Aprelev, Pavel; Kornev, Konstantin G; Luzinov, Igor

2017-07-12

This research is focused on the fabrication and properties of epoxy nanocomposites containing magnetized SiC whiskers (MSiCWs). To this end, we report an original strategy for fabrication of magnetically active SiCWs by decorating the whiskers with magnetic (iron oxide) nanoparticles via polymer-polymer (poly(acrylic acid)/poly(2-vinyl pyridine)) complexation. The obtained whiskers demonstrated a substantial magnetic response in the polymerizing epoxy resin, with application of only a 20 mT (200 G) magnetic field. We also found that the whiskers chemically reacted with the epoxy resin, causing formation of an extended interphase near the boundary of the whiskers. The SiC whiskers oriented with the magnetic field demonstrated positive effects on the behavior of epoxy-based nanocomposites. Namely, the aligned MSiCWs enhanced the thermomechanical properties of the materials significantly above that of the neat epoxy and epoxy nanocomposite, with randomly oriented whiskers.

Improved mechanical properties of hydroxyapatite whisker-reinforced poly(L-lactic acid) scaffold by surface modification of hydroxyapatite.

Science.gov (United States)

Fang, Zhou; Feng, Qingling

2014-02-01

To improve the mechanical properties of porous hydroxyapatite/poly(L-lactic acid) (HA/PLLA) composites, HA whiskers with high crystallinity and high aspect ratio were synthesized. HA whiskers were modified with γ-aminopropyltriethoxysilane (APTES) to improve the interface between HA whiskers and PLLA. The composite scaffold consists of a porous PLLA matrix with HA whiskers distributed homogeneously. The morphology and the distributions of pore sizes of PLLA scaffold was not influenced by introducing HA whiskers, while the mechanical properties were improved. Both the compressive strength and compressive modulus were increased with the weight ratio of APTES-modified HA whiskers up to 30 wt.%, but only up to 15 wt.% for non-modified HA whiskers. With more than 15 wt.% HA whiskers, the mechanical properties of HA/PLLA scaffold were better improved with APTES-modified HA whiskers than non-modified. The HA whisker/PLLA scaffold with high porosity and improved mechanical properties is attractive in the application of tissue engineering. Copyright © 2013 Elsevier B.V. All rights reserved.

Plasma deposition of polymer composite films incorporating nanocellulose whiskers

Science.gov (United States)

Samyn, P.; Airoudj, A.; Laborie, M.-P.; Mathew, A. P.; Roucoules, V.

2011-11-01

In a trend for sustainable engineering and functionalization of surfaces, we explore the possibilities of gas phase processes to deposit nanocomposite films. From an analysis of pulsed plasma polymerization of maleic anhydride in the presence of nanocellulose whiskers, it seems that thin nanocomposite films can be deposited with various patterns. By specifically modifying plasma parameters such as total power, duty cycle, and monomer gas pressure, the nanocellulose whiskers are either incorporated into a buckled polymer film or single nanocellulose whiskers are deposited on top of a polymeric film. The density of the latter can be controlled by modifying the exact positioning of the substrate in the reactor. The resulting morphologies are evaluated by optical microscopy, AFM, contact angle measurements and ellipsometry.

Low-temperature strain gauges based on silicon whiskers

Directory of Open Access Journals (Sweden)

Druzhinin A. A.

2008-08-01

Full Text Available To create low-temperature strain gauges based on p-type silicon whiskers tensoresistive characteristics of these crystals in 4,2—300 K temperature range were studied. On the basis of p-type Si whiskers with different resistivity the strain gauges for different materials operating at cryogenic temperatures with extremely high gauge factor at 4,2 K were developed, as well as strain gauges operating at liquid helium temperatures in high magnetic fields.

Innovation Incubator: Whisker Labs Technical Evaluation

Energy Technology Data Exchange (ETDEWEB)

Sparn, Bethany F. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Frank, Stephen M. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Earle, Lieko [National Renewable Energy Lab. (NREL), Golden, CO (United States); Scheib, Jennifer G. [National Renewable Energy Lab. (NREL), Golden, CO (United States)

2017-08-01

The Wells Fargo Innovation Incubator (IN2) is a program to foster and accelerate startup companies with commercial building energy-efficiency and demand management technologies. The program is funded by the Wells Fargo Foundation and co-administered by the National Renewable Energy Laboratory (NREL). Whisker Labs, an Oakland, California-based company, was one of four awardees in the first IN2 cohort and was invited to participate in the program because of its novel electrical power sensing technology for circuit breakers. The stick-on Whisker meters install directly on the front face of the circuit breakers in an electrical panel using adhesive, eliminating the need to open the panel and install current transducers (CTs) on the circuit wiring.

DC Characterisation of C60 Whiskers and Nanowhiskers

DEFF Research Database (Denmark)

Larsson, Michael; Kjelstrup-Hansen, Jakob; Lucyszyn, Stepan

2007-01-01

C60 whiskers exhibit increasing conductivity with decreasing diameter. At diameters of 1 mm and below, a single-crystal structure predominates, and enhanced electrical characteristics are expected; however, no supporting data exists in the literature. Here, results of four-point probe measurements......, indicating strong potential for use in organic electronic applications of the future. Repeated current cycling in air is observed to promote sample degradation, possibly due to progressive oxidation of the carbon structure. A micromachined four-point probe is also used to try to establish non...... on C60 whiskers and nanowhiskers with diameters in the range 650 nm to 1.3 mm are reported for the first time. Samples are attached to pre-patterned planar and raised electrodes using FIB-deposited tungsten. A low resistivity of 3 Wcm is measured in air, on a C60 whisker having a diameter of 650 nm...

Efek Pemberian Magnesium Sulfat Intravena Perioperatif terhadap Nilai Visual Analog Scale (VAS dan Kebutuhan Analgetik Pascabedah pada Pasien yang Menjalani Pembedahan Abdominal Ginekologi dengan Anestesi Umum

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Dhany Budipratama

2013-08-01

Full Text Available Magnesium sulphate is N-methyl-D-aspartate (NMDA receptor antagonist and calcium channel blocker with antinociceptive and antihyperalgesia effects. A randomized, double blind, controlled study was conducted to evaluate the effect of perioperative magnesium sulphate infusion on visual analog scale (VAS scores and cumulative rescue analgesic petidin consumption in 30 ASA physical status I–II female patients, aged 18– 60 years, scheduled for gynaecological surgery under general anaesthesia in central operating theatre Dr. Hasan Sadikin Hospital-Bandung within June–September 2011. Subjects were divided into two groups that received either intravenous bolus and maintenance of MgSO4 (M group or 0.9% normal saline (S group. The results showed that postoperative VAS score during movement and the number of analgesic pethidin were significantly lower in M group compared to S group (p<0.05. In conclusions, intravenous bolus of magnesium sulphate perioperative are able to demonstrate the lower value of VAS during mobilization and reducing the amount of analgesic rescue petidin postoperative abdominal gynaecological surgery.

The use of magnesium sulphate (MgSO4) for seizure prophylaxis ...

African Journals Online (AJOL)

MJP

administer drugs due to paucity of infusion pumps. Magnesium toxicity can ... respiratory rate and urine output are currently well recognised. .... infusion, the sample was collected from the contra- ... stored at 2-8ºC until analysis in the Central Science laboratory .... weight 2.40± 0.74kg) was a major problem; babies of severe ...

Effects of local film properties on the nucleation and growth of tin whiskers and hillocks

Science.gov (United States)

Sarobol, Pylin

Whiskers and hillocks grow spontaneously on Pb-free Sn electrodeposited films as a response to thin film stresses. Stress relaxation occurs by atom deposition to specific grain boundaries in the plane of the film, with hillocks being formed when grain boundary migration accompanies growth out of the plane of the film. The implication for whisker formation in electronics is serious: whiskers can grow to be millimeters long, sometimes causing short circuiting between adjacent components and, thereby, posing serious electrical reliability risks. In order to develop more effective whisker mitigation strategies, a predictive physics-based model has been needed. A growth model is developed, based on grain boundary faceting, localized Coble creep, as well as grain boundary sliding for whiskers, and grain boundary sliding with shear induced grain boundary migration for hillocks. In this model of whisker formation, two mechanisms are important: accretion of atoms by Coble creep on grain boundary planes normal to the growth direction inducing a grain boundary shear and grain boundary sliding in the direction of whisker growth. The model accurately captures the importance of the geometry of "surface grains"---shallow grains on film surfaces whose depths are significantly less than their in-plane grain sizes. A critical factor in the analysis is the ratio of the grain boundary sliding coefficient to the in-plane film compressive stress. If the accretion-induced shear stresses are not coupled to grain boundary motion and sliding occurs, a whisker forms. If the shear stress is coupled to grain boundary migration, a hillock forms. Based on this model, long whiskers grow from shallow surface grains with easy grain boundary sliding in the direction of growth. Other observed growth morphologies will be discussed in light of our model. Additional insights into the preferred sites for whisker and hillock growth were developed based on elastic anisotropy, local film microstructure

In vitro corrosion and cytocompatibility properties of nano-whisker hydroxyapatite coating on magnesium alloy for bone tissue engineering applications.

Science.gov (United States)

Yang, Huawei; Yan, Xueyu; Ling, Min; Xiong, Zuquan; Ou, Caiwen; Lu, Wei

2015-03-17

We report here the successful fabrication of nano-whisker hydroxyapatite (nHA) coatings on Mg alloy by using a simple one-step hydrothermal process in aqueous solution. The nHA coating shows uniform structure and high crystallinity. Results indicate that nHA coating is promising for improving the in vitro corrosion and cytocompatibility properties of Mg-based implants and devices for bone tissue engineering. In addition, the simple hydrothermal deposition method used in the current study is also applicable to substrates with complex shapes or surface geometries.

Theoretical and experimental analysis of the toughening behavior of whisker reinforcement in ceramic matrix composites

International Nuclear Information System (INIS)

Becher, P.F.; Hsueh, C.H.; Angelini, P.; Tiegs, T.N.

1988-01-01

Analytical solutions are presented describing the experimentally verified toughening of whisker reinforced ceramics. Clear insights are provided into the interrelationships of whiskers, matrices, and interfaces in the case of strong interfaces with minimized whisker pullout

Whiskers and fibers of hydroxyapatite; Whiskers e fibras de hidroxiapatita

Energy Technology Data Exchange (ETDEWEB)

Cardoso, G.B.C.; Motisuke, M.; Zavaglia, C.A.C., E-mail: guicardoso@fem.unicamp.b [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Fac. de Engenharia Mecanica. Dept. de Engenharia de Materiais; Arruda, A.C.F. [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Fac. de Engenharia Mecanica. Dept. de Engenharia de Petroleo

2009-07-01

Hydroxyapatite is a bioactive ceramic, which acts in tissue engineering by attracting bone cells. Occasionally it can be used as a biocompatible reinforcement. The mechanical role of this biomaterial can be defined depending of some characteristics analyzed by scanning electron microscope and X ray power diffraction. It can be classified in whiskers and fibers; each one has their own properties, which were discussed in this work. For its use as reinforcement it is necessary matrix with specific characteristics. (author)

Investigating the Changes of Sulphate in Potabale Water of Yasuj City and preparing it's Qualitative Plan by Means of GIS Tools

International Nuclear Information System (INIS)

Pasereh, F.; Hasani, A.; Hoseini, N.; Javid, A.

2016-01-01

Water has always some soluble salts, such as sulphate. Sulphate enters the water through different resources such as, dissolved gypsum, waste water of industrial factories and automobiles smoke, dissolved in rain. Presence of sulphate in potable water has an enormous role in creating constant hardness.On the other hand Presence of sulphate with high density in drinking water, causes changes in taste and it's combination with Calcium and Magnesium anions has laxative effect. The goal of this study is to assess the amount of existing sulphate in Yasuj city potable ground water, and determining the procedure of changes in chemical parameters of sulphate and recognizing effective factors on these parameters and preparing qualitative plan for water resources for sulphate parameter by means of GIS tools. Method: In the study described above, 42 specimens in the 7 early months of the year 1387 were acquired and tested. Sulphate tests were done based on the measuring method of the instrument of Filter photometer (Model: 7000). For analysing the results, Excel software and for preparing qualitative plan, GIS software was used. Findings: This study showed that sulfate levels in water resources by reducing water level in summer and autumn and with a water level of under ground water resources increases. Discussion and Conclusion: Decrease of ground water resources of Yasuj city, causes the sulphate density to increase.

Extraction and characterization of whiskers from Panicum grass cellulose fibers

International Nuclear Information System (INIS)

Martins, Douglas F.; Vieira, Julia G.; Pasquini, Daniel

2011-01-01

In this work are presented studies of the extraction of cellulose whiskers from Panicum grass fibers (Panicum maximum) by acid hydrolysis performed with H 2 SO 4 11.22 M. The fibers used in the hydrolysis process were previously purified and the efficiency of the purification process was evaluated by determining the lignin content by Klason method, before and after purification. The hydrolysis was performed at 40 degree C for 30 minutes. The whiskers were characterized by x-ray diffraction (XRD) and thermogravimetric analysis (TGA). It was verified a reduction in the crystallinity index and also a reduction of the degradation temperature of the whiskers in relation to the purified grass Panicum fibers. (author)

In Vitro Corrosion and Cytocompatibility Properties of Nano-Whisker Hydroxyapatite Coating on Magnesium Alloy for Bone Tissue Engineering Applications

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Huawei Yang

2015-03-01

Full Text Available We report here the successful fabrication of nano-whisker hydroxyapatite (nHA coatings on Mg alloy by using a simple one-step hydrothermal process in aqueous solution. The nHA coating shows uniform structure and high crystallinity. Results indicate that nHA coating is promising for improving the in vitro corrosion and cytocompatibility properties of Mg-based implants and devices for bone tissue engineering. In addition, the simple hydrothermal deposition method used in the current study is also applicable to substrates with complex shapes or surface geometries.

Peculiarities of magnetoresistance in InSb whiskers at cryogenic temperatures

Energy Technology Data Exchange (ETDEWEB)

Druzhinin, A., E-mail: druzh@polynet.lviv.ua [Lviv Polytechnic National University, Bandera Str., 12, 79013 Lviv (Ukraine); International Laboratory of High Magnetic Fields and Low Temperatures, Gajowicka 95, Wroclaw (Poland); Ostrovskii, I.; Khoverko, Yu. [Lviv Polytechnic National University, Bandera Str., 12, 79013 Lviv (Ukraine); International Laboratory of High Magnetic Fields and Low Temperatures, Gajowicka 95, Wroclaw (Poland); Liakh-Kaguy, N.; Khytruk, I. [Lviv Polytechnic National University, Bandera Str., 12, 79013 Lviv (Ukraine); Rogacki, K. [International Laboratory of High Magnetic Fields and Low Temperatures, Gajowicka 95, Wroclaw (Poland)

2015-12-15

Highlights: • Magnetoresistance in InSb whiskers with impurity concentration near MIT is studied. • SdH oscillations of transverse and longitudinal magnetoresistance are examined. • Mechanisms of electron scattering are determined • Main crystal parameters of InSb whiskers are determined. - Abstract: The study of the magnetoresistance in InSb whiskers with an impurity concentration in the vicinity to the metal-insulator phase transition, at low temperature range 4.2–77 K, and in fields, with induction up to 14 T, was conducted. The presence of Shubnikov-de Haas oscillations in both transverse and longitudinal magnetoresistance was observed. The following parameters of InSb whiskers were defined: period of oscillations 0.1 T{sup −1}, cyclotron effective mass of electrons m{sub c} ≈ 0.14m{sub o,} concentration of charge carriers 2.3 × 10{sup 17} cm{sup −3}, g-factor g{sup *} ≈ 30 and Dingle temperature T{sub D} = 14.5 K. To determine the nature of crystal defects, the electron scattering processes on the short-range potential, caused by interaction with polar and nonpolar optical phonons, piezoelectric and acoustic phonons, static strain centers and ionized impurities in n-InSb whiskers, with defect concentration 2.9 × 10{sup 17} cm{sup −3}, are considered. The temperature dependences of electron mobility in the range 4.2–500 K were calculated.

Properties of ZnO whiskers under CO2-laser irradiation

International Nuclear Information System (INIS)

Shkumbatyuk, P. S.

2010-01-01

Needlelike ZnO single crystals (whiskers) 0.3-0.8 mm long and 1-10 μm in diameter with a resistivity from 3 x 10 2 to 1 Ω cm have been grown under cw CO 2 -laser irradiation. The whiskers exhibit weak electroluminescence caused by injection from contacts with participation of intrinsic defects, which affect the electric field distribution.

Fast feedback in active sensing: touch-induced changes to whisker-object interaction.

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Dudi Deutsch

Full Text Available Whisking mediated touch is an active sense whereby whisker movements are modulated by sensory input and behavioral context. Here we studied the effects of touching an object on whisking in head-fixed rats. Simultaneous movements of whiskers C1, C2, and D1 were tracked bilaterally and their movements compared. During free-air whisking, whisker protractions were typically characterized by a single acceleration-deceleration event, whisking amplitude and velocity were correlated, and whisk duration correlated with neither amplitude nor velocity. Upon contact with an object, a second acceleration-deceleration event occurred in about 25% of whisk cycles, involving both contacting (C2 and non-contacting (C1, D1 whiskers ipsilateral to the object. In these cases, the rostral whisker (C2 remained in contact with the object throughout the double-peak phase, which effectively prolonged the duration of C2 contact. These "touch-induced pumps" (TIPs were detected, on average, 17.9 ms after contact. On a slower time scale, starting at the cycle following first touch, contralateral amplitude increased while ipsilateral amplitude decreased. Our results demonstrate that sensory-induced motor modulations occur at various timescales, and directly affect object palpation.

Effect of SiC whisker addition on the microstructures and mechanical properties of Ti(C, N)-based cermets

International Nuclear Information System (INIS)

Wu, Peng; Zheng, Yong; Zhao, Yongle; Yu, Haizhou

2011-01-01

Ti(C, N)-based cermets with addition of SiC whisker (SiC w ) were prepared by vacuum sintering. The microstructures of the prepared cermets were investigated by using X-ray diffractometry (XRD) and scanning electron microscopy (SEM). Mechanical properties such as transverse rupture strength (TRS), fracture toughness (K IC ) and hardness (HRA) were also measured. It was found that the grain size of the cermets was affected by the SiC whisker addition. The cermets with 1.0 wt.% SiC whisker addition exhibited the smallest grain size. The porosities of the cermets increased with increasing SiC whisker additions. The addition of the SiC whisker had no influence on the phase constituents of the cermets. Compared with the cermets with no whisker addition, the highest TRS and fracture toughness for cermets with 1.0 wt.% SiC whisker addition increased by about 24% and 29%, respectively. The strengthening mechanisms were attributed to finer grain size, homogeneous microstructure and moderate thickness of rim phase. The toughening mechanisms were characterized by crack deflection, whisker bridging and whisker pulling-out.

In-situ measurement of bending strength of TiC whiskers in the scanning electron microscope

Energy Technology Data Exchange (ETDEWEB)

Seino, Yutaka; Shin, Shoichiro; Nagai, Satoshi [National Research Lab. of Metrology, Tsukuba, Ibaraki (Japan)

1995-10-01

The three-point bending strength of TiC whiskers was measured in a scanning electron microscope. The whisker samples have {approximately} 50 {micro}m length and 2 {approximately} 4 {micro}m diameter and are commercially available as reinforcements. For composite materials. The distribution of the bending strengths of the whiskers showed a double peak around 5.2GPa and 30.4GPa, respectively. The difference in these values is attributed to differences in the cleavage strength of two crystal planes depending on whisker growth direction.

Behavior’s Evolution of Micro-Concretes in Combined Sulphate and Magnesium Aggressive Environments, at Three -Years Old

Directory of Open Access Journals (Sweden)

Mircea Rujanu

2010-03-01

Full Text Available In the present paper is analysed concrete behavior from strength structure elements, subjected to combined sulphatic and magnesian aggressive actions. In order to clearly relieve cement influence regarding corrosion behavior and to be as close as possible of concrete structural characteristics, tests are realized on standard mortars, which from compositional point of view are mocro-concretes. These were used different W/C ratios in order to obtain different structural characteristics, knowing that in the first period after casting, when concrete porosity is sensibly higher, corrosion process is more emphatic, with subsequent negative effects. It was taken into account the fact that sulphatic corrosion effect appears after a long duration of aggressive agent action, in the present paper proposing a three year duration for aggressive attack. In the same time it was considered the fact that usual cement for structural elements is composite cement type CEM II/A-S 32,5, studying combined sulphatic and magnesian corrosion evolution on a large type of micro-concrete compositions with different compactness and aggressive agent concentrations.

Contributions of stress and oxidation on the formation of whiskers in Pb-free solders

Energy Technology Data Exchange (ETDEWEB)

Duncan, A. J. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Hoffman, E. N. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

2016-01-01

Understanding the environmental factors influencing formation of tin whiskers on electrodeposited lead free, tin coatings over copper (or copper containing) substrates is the topic of this study . An interim report* summarized initial observations as to the role of stress and oxide formation on whisker growth. From the initial results, two main areas were chosen to be the focus of additional research: the demonstration of effects of elastic stress state in the nucleation of whiskers and the confirmation of the effect of oxygen content in the formation of whiskers. Different levels of elastic stress were induced with the incorporation of a custom designed fixture that loaded the sample in a four-point bending configuration and were maintained in an environmental chamber under conditions deemed favorable for whisker growth. The effects of oxygen content were studied by aging substrates in gas vials of varying absolute pressure and different oxygen partial pressure.

Structure and Properties of Chitin Whisker Reinforced Papers for Food Packaging Application

Directory of Open Access Journals (Sweden)

Zhihan Li

2015-04-01

Full Text Available In recent years, concerns about environmental waste caused by petroleum-derived chemicals as well as the consumer's demand for high quality food products, have prompted people to pay more attention to developing biodegradable food packaging materials using natural resources such as cellulose fibers and chitin derivatives. In this study, chitin whiskers have been successfully generated by hydrolyzing the α-chitin sample. Then the synthesized nano-sized chitin whiskers were used at ratios from 0.1% to 2% (wt% for improving strength properties of paper sheets by the dip-coating method. Transmission electron microscopy (TEM and field emission scanning electron microscopy (FE-SEM were used to investigate the morphology of chitin whiskers and cellulose fiber compounds. The results showed that coating with chitin whiskers brought about an increase in tear strength, burst strength, and wet and dry tensile strength, with a decrease in Zeta-potential value.

Characterization of microstructure of Si3N4 whisker reinforced glass ceramic

International Nuclear Information System (INIS)

Han, Byoung Sung; Choi, Shung Shaon

1993-01-01

Glass ceramics, especially fiber-reinforced composite ceramics, have attracted a great deal of attention in improving the reliability of ceramic components because of the improvement in various mechanical properties. Through hot-pressing and sintering, 225 cordierite was transformed with glass ceramic and mullite phase. Particularly glass glain size increased with the increasing of the sintering temperature and the heat treatment enhance the toughness and hardness of materials. Like the increased sintering temperature, the roughness increased with increasing whisker vol.%. In case of whisker-rinforced glass ceramic, the fracture surface of samples has been associated with a whisker orientation of samples. (Author)

Hydrothermal Formation Of Hemi-hydrate Calcium Sulfate Whiskers In The Presence Of Additives

International Nuclear Information System (INIS)

Luo, K. B.; Li, C. M.; Li, H. P.; Ning, P.; Xiang, L.

2010-01-01

The influence of addictives on the hydrothermal formation of hemi-hydrate calcium sulfate (CaSO 4 ·0.5H 2 O) whiskers were discussed in this paper, using CaCl 2 and Na 2 SO 4 as the reactants. The presence of NaCl, CaCl 2 or Na 2 SO 4 increased the concentrations of Ca 2+ and SO 4 2- , leading to the formation of CaSO 4 ·0.5H 2 O whiskers with aspect ratio lower than 50. The one dimensional growth of CaSO 4 ·0.5H 2 O whiskers was enhanced in water with no additives owing to the low super-saturation, leading to the formation of uniform whiskers with a length of 200-2000 μm and an aspect ratio higher than 100.

Isolation of whiskers from natural sources and their dispersed in a non-aqueous medium

Directory of Open Access Journals (Sweden)

Mauro Vestena

Full Text Available Abstract Whiskers have been used as a nanomaterial dispersed in polymer matrices to modify the microscopic and macroscopic properties of the polymer. These nanomaterials can be isolated from cellulose, one of the most abundant natural renewable sources of biodegradable polymer. In this study, whiskers were isolated from sugarcane bagasse and corn cob straw fibers. Initially, the cellulose fiber was treated through an alkaline/oxidative process followed by acid hydrolysis. Dimethylformamide and dimethyl sulfoxide were used to replace the aqueous medium for the dispersion of the whiskers. For the solvent exchange, dimethylformamide or dimethyl sulfoxide was added to the aqueous dispersion and the water was then removed by fractional distillation. FTIR, TGA, XRD, TEM, Zeta and DLS techniques were used to evaluate the efficiency of the isolation process as well as the morphology and dimensions of the whiskers. The dimensions of the whiskers are comparable with values reported in the literature, maintaining the uniformity and homogeneity in both aqueous and non-aqueous solvents.

Isolation of whiskers from natural sources and their dispersed in a non-aqueous medium

Energy Technology Data Exchange (ETDEWEB)

Vestena, Mauro; Gross, Idejan Padilha; Pires, Alfredo Tiburcio Nunes; Muller, Carmen Maria Olivera, E-mail: mauro@utfpr.edu.br [Universidade Federal Santa Catarina (UFSC), Florianopolis, SC (Brazil)

2016-10-15

Whiskers have been used as a nano material dispersed in polymer matrices to modify the microscopic and macroscopic properties of the polymer. These nanomaterials can be isolated from cellulose, one of the most abundant natural renewable sources of biodegradable polymer. In this study, whiskers were isolated from sugarcane bagasse and corn cob straw fibers. Initially, the cellulose fiber was treated through an alkaline/oxidative process followed by acid hydrolysis. Dimethylformamide and dimethyl sulfoxide were used to replace the aqueous medium for the dispersion of the whiskers. For the solvent exchange, dimethylformamide or dimethyl sulfoxide was added to the aqueous dispersion and the water was then removed by fractional distillation. FTIR, TGA, XRD, TEM, Zeta and DLS techniques were used to evaluate the efficiency of the isolation process as well as the morphology and dimensions of the whiskers. The dimensions of the whiskers are comparable with values reported in the literature, maintaining the uniformity and homogeneity in both aqueous and non-aqueous solvents. (author)

Contributions of Stress and Oxidation on the Formation of Whiskers in Pb-free Solders

Science.gov (United States)

2016-01-29

nucleation of whiskers and the confirmation of the effect of oxygen content in the formation of whiskers. Different levels of elastic stress were...substrate P Load RH Relative humidity max Stress at the top surface of the film SE Secondary Electrons SEM Scanning Electron Microscopy SRNL...demonstration of effects of stress state in the nucleation of whiskers and the confirmation of the effect of oxygen content in the formation of

Silicon carbide whiskers with superlattice structure: A precursor for a new type of nanoreactor

International Nuclear Information System (INIS)

Lutsenko, Vadym G.

2008-01-01

Silicon carbide whiskers exhibit growth predominantly in the direction. The high level of impurities, stacking faults and nanosized twins govern the formation of homojunctions and heterojunctions in crystals. The structure of the whiskers comprises a hybrid superlattice, i.e. contains elements of doped and composite superlattices. An individual SiC whisker can contain hundreds of quantum wells with anomalous chemical properties. This paper shows that it is possible to selectively etch quantum wells and to construct whiskers with quasi-regularly distributed slit-like nanopores (nanoreactors), which are bordered by polar planes {1 1 1}, {0 0 0 1} or a combination of them, and also to produce flat SiC nanocrystals bordered by polar planes

A new paradigm for the reversible blockage of whisker sensory transmission.

Science.gov (United States)

Gener, Thomas; Reig, Ramon; Sanchez-Vives, Maria V

2009-01-30

The objective of this study was to explore a paradigm that would allow a temporary deprivation of whisker information lasting for a few hours. An additional requirement was to be non-invasive in order to be usable in awake chronically implanted rats without inducing stress. With that aim, electrophysiological recordings from the barrel cortex of anesthetized rats were obtained. The pressure of an air-puff (5-10 ms) delivered to the whiskers was adjusted to evoke a consistent response of around 100 microV (extracellular) or approximately 5 mV (intracellular) in the contralateral cortex. Lidocaine was then locally applied in different forms (cream, local injection, aerosol, drops) and concentrations (2-10%) to the base of the whiskers. The stimulus-induced response was monitored once every 5s for several hours (3-6h) in order to characterize its course of action. Local injection of lidocaine induced the fastest and most complete blockage, but was ruled out for being invasive. Out of the remaining forms of application, a lidocaine drop (0.4 ml, 10%) to the base of the whiskers was found to induce a reliable blockage (to an average 9% the original response). The maximum effect was reached after 150-200 min, and the response was totally recovered approximately 300 min after lidocaine application. This characterization should be useful to induce an efficient, short term and reversible blockage of whisker sensory transmission in both anesthetized and awake preparations, while not causing stress in an awake animal.

Comparative efficacy of ropivacaine and levobupivacaine in combined femoral and lateral femoral cutaneous nerve block with adjuvant magnesium for post-operative analgesia

Directory of Open Access Journals (Sweden)

Prakash Khairnar

2016-01-01

Full Text Available Background and Aims: Patients with burns may require multiple surgeries, but poor general condition and underlying protein energy malnutrition make them unsuitable candidates for general or spinal anaesthesia. This study evaluated the role of magnesium sulphate as an adjuvant with levobupivacaine and ropivacaine used in combined femoral and lateral femoral cutaneous nerve (LFCN blocks in burn patients with relative sparing of thigh portion. Methods: This prospective, randomised, double-blind study included 54 adult patients of 18-65 years age, undergoing split-thickness skin graft harvest from the thigh, allotted to three equal groups of 18 each. Group L patients received femoral nerve (FN block with 15 mL of 0.5% levobupivacaine and 8 mL for LFCN block; Group LM patients received 14 mL of 0.5% levobupivacaine along with 1.0 mL of 15% magnesium sulphate for FN block, 7.5 mL of 0.5% levobupivacaine with 0.5 mL of 15% of magnesium sulphate to LFCN block and Group R patients received 15 mL of 0.5% ropivacaine for FN block and 8 mL of 0.5% ropivacaine for LFCN block. Time to block onset and complete surgical block, duration of analgesia, total analgesic dose and the overall analgesia satisfaction score were measured in the first 24 h post-operatively. Quantitative data were analysed with ANOVA and qualitative data subjected to Chi-square tests. Intergroup comparison was performed with independent t-test. Results: The duration of post-operative analgesia did not differ with the addition of magnesium (P = 0.610. Time to onset of the block was significantly decreased with the addition of magnesium (P = 0.0341, but time to complete surgical block onset was similar across the groups. Conclusion: Both ropivacaine and levobupivacaine have good perioperative analgesic efficacy. Magnesium as an analgesia adjuvant with levobupivacaine does not prolong the duration of post-operative analgesia.

Nanocomposite polymer electrolyte based on whisker or microfibrils polyoxyethylene nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Alloin, Fannie, E-mail: fannie.alloin@lepmi.grenoble-inp.f [LEPMI, Laboratoire d' Electrochimie et de Physicochimie des Materiaux et des Interfaces, Grenoble-INP-UJF-CNRS, UMR 5631, BP 75, 38041 Grenoble Cedex 9 (France); D' Aprea, Alessandra [Laboratoire de Rheologie, Grenoble-INP-UJF, UMR 5520, BP 53, 38041 Grenoble Cedex 9 (France); LEPMI, Laboratoire d' Electrochimie et de Physicochimie des Materiaux et des Interfaces, Grenoble-INP-UJF-CNRS, UMR 5631, BP 75, 38041 Grenoble Cedex 9 (France); Ecole Internationale du Papier, de la communication imprimee et des Biomateriaux, PAGORA- Grenoble-INP, BP 65, 38402 Saint Martin d' Heres Cedex (France); Kissi, Nadia El [Laboratoire de Rheologie, Grenoble-INP-UJF, UMR 5520, BP 53, 38041 Grenoble Cedex 9 (France); Dufresne, Alain [Ecole Internationale du Papier, de la communication imprimee et des Biomateriaux, PAGORA- Grenoble-INP, BP 65, 38402 Saint Martin d' Heres Cedex (France); Bossard, Frederic [Laboratoire de Rheologie, Grenoble-INP-UJF, UMR 5520, BP 53, 38041 Grenoble Cedex 9 (France)

2010-07-15

Nanocomposite polymer electrolytes composed of high molecular weight poly(oxyethylene) PEO as a matrix, LiTFSI as lithium salt and ramie, cotton and sisal whiskers with high aspect ratio and sisal microfibrils (MF), as reinforcing phase were prepared by casting-evaporation. The morphology of the composite electrolytes was investigated by scanning electron microscopy and their thermal behavior (characteristic temperatures, degradation temperature) were investigated by thermogravimetric analysis and differential scanning calorimetry. Nanocomposite electrolytes based on PEO reinforced by whiskers and MF sisal exhibited very high mechanical performance with a storage modulus of 160 MPa at high temperature. A weak decrease of the ionic conductivity was observed with the incorporation of 6 wt% of whiskers. The addition of microfibrils involved a larger decrease of the conductivity. This difference may be associated to the more restricted PEO mobility due to the addition of entangled nanofibers.

A truncated conical beam model for analysis of the vibration of rat whiskers.

Science.gov (United States)

Yan, Wenyi; Kan, Qianhua; Kergrene, Kenan; Kang, Guozheng; Feng, Xi-Qiao; Rajan, Ramesh

2013-08-09

A truncated conical beam model is developed to study the vibration behaviour of a rat whisker. Translational and rotational springs are introduced to better represent the constraint conditions at the base of the whiskers in a living rat. Dimensional analysis shows that the natural frequency of a truncated conical beam with generic spring constraints at its ends is inversely proportional to the square root of the mass density. Under all the combinations of the classical free, pinned, sliding or fixed boundary conditions of a truncated conical beam, it is proved that the natural frequency can be expressed as f = α(rb/L(2))E/ρ and the frequency coefficient α only depends on the ratio of the radii at the two ends of the beam. The natural frequencies of a representative rat whisker are predicted for two typical situations: freely whisking in air and the tip touching an object. Our numerical results show that there exists a window where the natural frequencies of a rat whisker are very sensitive to the change of the rotational constraint at the base. This finding is also confirmed by the numerical results of 18 whiskers with their data available from literature. It can be concluded that the natural frequencies of a rat whisker can be adjusted within a wide range through manipulating the constraints of the follicle on the rat base by a behaving animal. Copyright © 2013 Elsevier Ltd. All rights reserved.

Spontaneous growth of whiskers on RE-bearing intermetallic compounds of Sn-RE, In-RE, and Pb-RE

International Nuclear Information System (INIS)

Liu Meng; Xian Aiping

2009-01-01

A phenomenon of the whiskers growth on the bulk rare earth (RE)-intermetallic compounds of NdSn 3 , NdIn 3 , and LaPb 3 is reported. The whiskers formed spontaneously on all of the RE-intermetallic compounds after exposed to room ambience (21-28 deg. C/20-56% RH, relative humidity) for several days. Among the samples, the propensity of whisker growth for NdSn 3 is the strongest, on which the tin whiskers were flourishing and covered all of the surfaces after exposed to room ambience for 22 days; while LaPb 3 is the secondary and NdIn 3 is the last one. Observed by SEM, the whiskers were exhibited as different morphology, size, and number density. The XRD analysis confirms the existence of RE(OH) 3 after whiskers formed, also, the weight gain curve of the samples exposed to room ambience supports that a spontaneous chemical reaction of the RE-intermetallic compounds with water in room ambience takes place. In discussion, it is proposed that the fresh metal atoms released by the chemical reaction could be causative to result in nucleation and spontaneous growth of the whiskers, while the anisotropy of crystal structure could be a reason to understand the difference of the whisker growth behaviors between Sn and Pb.

Sensory prediction on a whiskered robot: A tactile analogy to "optic flow"

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Christopher L Schroeder

2012-10-01

Full Text Available When an animal moves an array of sensors (e.g., the hand, the eye through the environment, spatial and temporal gradients of sensory data are related by the velocity of the moving sensory array. In vision, the relationship between spatial and temporal brightness gradients is quantified in the optical flow equation. In the present work, we suggest an analog to optical flow for the rodent vibrissal (whisker array, in which the perceptual intensity that flows over the array is bending moment. Changes in bending moment are directly related to radial object distance, defined as the distance between the base of a whisker and the point of contact with the object. Using both simulations and a 1x5 array (row of artificial whiskers, we demonstrate that local object curvature can be estimated based on differences in radial distance across the array. We then develop two algorithms, both based on tactile flow, to predict the future contact points that will be obtained as the whisker array translates along the object. The translation of the robotic whisker array represents the rat's head velocity. The first algorithm uses a calculation of the local object slope, while the second uses a calculation of the local object curvature. Both algorithms successfully predict future contact points for simple surfaces. The algorithm based on curvature was found to more accurately predict future contact points as surfaces became more irregular. We quantify the inter-related effects of whisker spacing and the object’s spatial frequencies, and examine the issues that arise in the presence of real-world noise, friction, and slip.

Whiskers aid anemotaxis in rats.

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Yu, Yan S W; Graff, Matthew M; Bresee, Chris S; Man, Yan B; Hartmann, Mitra J Z

2016-08-01

Observation of terrestrial mammals suggests that they can follow the wind (anemotaxis), but the sensory cues underlying this ability have not been studied. We identify a significant contribution to anemotaxis mediated by whiskers (vibrissae), a modality previously studied only in the context of direct tactile contact. Five rats trained on a five-alternative forced-choice airflow localization task exhibited significant performance decrements after vibrissal removal. In contrast, vibrissal removal did not disrupt the performance of control animals trained to localize a light source. The performance decrement of individual rats was related to their airspeed threshold for successful localization: animals that found the task more challenging relied more on the vibrissae for localization cues. Following vibrissal removal, the rats deviated more from the straight-line path to the air source, choosing sources farther from the correct location. Our results indicate that rats can perform anemotaxis and that whiskers greatly facilitate this ability. Because air currents carry information about both odor content and location, these findings are discussed in terms of the adaptive significance of the interaction between sniffing and whisking in rodents.

Growth of cadmium oxide whiskers on cadmium sulphide single crystals with copper as growth activator

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Koparanova, N.; Simov, S. (Bylgarska Akademiya na Naukite, Sofia. Inst. po Fizika na Tvyrdoto Tyalo); Genchev, D. (Bylgarska Akademiya na Naukite, Sofia. Inst. za Yadrena Izsledvaniya i Yadrena Energetika); Metchenov, G. (Research Inst. of Criminalistics and Criminology, Sofia (Bulgaria))

1985-02-01

Some results on the growth and morphology of cadmium oxide whiskers, obtained on cadmium sulphide single crystals with copper as a growth activator, are presented in this work. Cadmium oxide whiskers have been obtained on brace 112-bar0 brace faces of cadmium sulphide plates with a copper layer deposited in advance. The whiskers grew during the annealing of the plates in a weak stream of technically pure argon at temperatures 670 to 730 deg C for 15 min to 3.5 h. Details about the procedure have been given elsewhere. The composition and morphology of the whiskers have been studied by an X-ray microanalyser JEOL 35 DDS and a scanning electron microscope JEOL, JSM 35. The optical microscopic observations have shown that after annealing, a gray-black granular layer is formed on the cadmium sulphide single crystals and this layer can easily be separated from the crystal substrate. Under the granular layer the crystal is heavily damaged. The whiskers grow on the granular layer and they are coloured yellow-brown or red-brown. The maximum whisker length attains several hundreds of micrometres and in some cases up to 1 mm or more.

Growth of cadmium oxide whiskers on cadmium sulphide single crystals with copper as growth activator

International Nuclear Information System (INIS)

Koparanova, N.; Simov, S.

1985-01-01

Some results on the growth and morphology of cadmium oxide whiskers, obtained on cadmium sulphide single crystals with copper as a growth activator, are presented in this work. Cadmium oxide whiskers have been obtained on brace 112-bar0 brace faces of cadmium sulphide plates with a copper layer deposited in advance. The whiskers grew during the annealing of the plates in a weak stream of technically pure argon at temperatures 670 to 730 deg C for 15 min to 3.5 h. Details about the procedure have been given elsewhere. The composition and morphology of the whiskers have been studied by an X-ray microanalyser JEOL 35 DDS and a scanning electron microscope JEOL, JSM 35. The optical microscopic observations have shown that after annealing, a gray-black granular layer is formed on the cadmium sulphide single crystals and this layer can easily be separated from the crystal substrate. Under the granular layer the crystal is heavily damaged. The whiskers grow on the granular layer and they are coloured yellow-brown or red-brown. The maximum whisker length attains several hundreds of micrometres and in some cases up to 1 mm or more. (author)

The Effects of Oxidation Layer, Temperature, and Stress on Tin Whisker Growth: A Short Review

Science.gov (United States)

Mahim, Z.; Salleh, M. A. A.; Khor, C. Y.

2018-03-01

In order to reduce the Tin (Sn) whisker growth phenomenon in solder alloys, the researcher all the world has studied the factor of this behaviour. However, this phenomenon still hunted the electronic devices and industries. The whiskers growth were able to cause the electrical short, which would lead to the catastrophic such as plane crush, the failure of heart pacemaker, and the lost satellite connection. This article focuses on the three factors that influence the whiskers growth in solder alloys which is stress, oxidation layer and temperature. This findings were allowed the researchers to develop various method on how to reduce the growth of the Sn whiskers.

Antenatal magnesium individual participant data international collaboration: assessing the benefits for babies using the best level of evidence (AMICABLE

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2012-03-01

Full Text Available Abstract Background The primary aim of this study is to assess, using individual participant data (IPD meta-analysis, the effects of administration of antenatal magnesium sulphate given to women at risk of preterm birth on important clinical outcomes for their child such as death and neurosensory disability. The secondary aim is to determine whether treatment effects differ depending on important pre-specified participant and treatment characteristics, such as reasons at risk of preterm birth, gestational age, or type, dose and mode of administration of magnesium sulphate. Methods Design The Antenatal Magnesium Individual Participant Data (IPD International Collaboration: assessing the benefits for babies using the best level of evidence (AMICABLE Group will perform an IPD meta-analysis to answer these important clinical questions. Setting/Timeline The AMICABLE Group was formed in 2009 with data collection commencing late 2010. Inclusion Criteria Five trials involving a total 6,145 babies are eligible for inclusion in the IPD meta-analysis. Primary study outcomes For the infants/children: Death or cerebral palsy. For the women: Any severe maternal outcome potentially related to treatment (death, respiratory arrest or cardiac arrest. Discussion Results are expected to be publicly available in 2012.

Spontaneous growth of whiskers on RE-bearing intermetallic compounds of Sn-RE, In-RE, and Pb-RE

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Liu Meng [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Science, 72 Wenhua Road, Shenyang 110016 (China); Xian Aiping, E-mail: ap.xian@imr.ac.c [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Science, 72 Wenhua Road, Shenyang 110016 (China)

2009-11-03

A phenomenon of the whiskers growth on the bulk rare earth (RE)-intermetallic compounds of NdSn{sub 3}, NdIn{sub 3}, and LaPb{sub 3} is reported. The whiskers formed spontaneously on all of the RE-intermetallic compounds after exposed to room ambience (21-28 deg. C/20-56% RH, relative humidity) for several days. Among the samples, the propensity of whisker growth for NdSn{sub 3} is the strongest, on which the tin whiskers were flourishing and covered all of the surfaces after exposed to room ambience for 22 days; while LaPb{sub 3} is the secondary and NdIn{sub 3} is the last one. Observed by SEM, the whiskers were exhibited as different morphology, size, and number density. The XRD analysis confirms the existence of RE(OH){sub 3} after whiskers formed, also, the weight gain curve of the samples exposed to room ambience supports that a spontaneous chemical reaction of the RE-intermetallic compounds with water in room ambience takes place. In discussion, it is proposed that the fresh metal atoms released by the chemical reaction could be causative to result in nucleation and spontaneous growth of the whiskers, while the anisotropy of crystal structure could be a reason to understand the difference of the whisker growth behaviors between Sn and Pb.

The Reclamation of Industrial Wastes Inclusive Sulphates by Sulphate-Reducing Bacteria

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Mária Kušnierová

2004-12-01

Full Text Available The objective of our study was to verify experimentally the possibility of using coal mine drainage and gypsum from the „stabilizate“ (the final product from the combustion desulphurisation as the source of sulphate for the cultivation of SRB with the prospect of: purging of mine waste waters inclusive sulphates, recycling of desulphurisation agent (limestone and production of elemental sulphur from hydrogen sulphide. The results confirmed the theoretical assumptions on the use of gypsum, which forms the substantial component of „stabilizate“, as the source of sulphate for sulphate-reducing bacteria, which produce hydrogen sulphide in the process of bacterial reduction of sulphates. They also showed the possibility of recycling the desulphurisation agent – limestone, as well as the realistic alternative of using „stabilizate“ in the production of elemental sulphur which still represents an important raw material needed in chemical, paper or other industries.

Cultured embryonic non-innervated mouse muzzle is capable of generating a whisker pattern.

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Andrés, F L; Van Der Loos, H

1983-01-01

The whisker pattern on the muzzle of the mouse is mapped in the contralateral parietal neocortex, each whisker follicle projecting to its own multineuronal unit ('barrel'). To determine the role, if any, of the peripheral innervation in the establishment of the vibrissal array, we cultured non-innervated prospective whiskerpads from 9- and 10-day-old embryos, mostly on chorioallantoic membrane. The results show that skin, alone, is capable of generating the whisker pattern, thus adducing a strong argument for the hypothesis that the central brain maps have their origin in the periphery. Copyright © 1983. Published by Elsevier Ltd.

Effect of magnesium treatment and glucose levels on delayed cerebral ischemia in patients with subarachnoid hemorrhage: a substudy of the Magnesium in Aneurysmal Subarachnoid Haemorrhage trial (MASH-II).

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Leijenaar, Jolien F; Dorhout Mees, Sanne M; Algra, Ale; van den Bergh, Walter M; Rinkel, Gabriel J E

2015-10-01

Magnesium treatment did not improve outcome in patients with aneurysmal subarachnoid haemorrhage in the Magnesium in Aneurysmal Subarachnoid Haemorrhage II trial. We hypothesized that high glucose levels may have offset a potential beneficial effect to prevent delayed cerebral ischemia. We investigated if magnesium treatment led to less delayed cerebral ischemia and if glucose levels interacted with magnesium treatment in the Magnesium in Aneurysmal Subarachnoid Haemorrhage II trial. To investigate the effect of magnesium treatment on occurrence of delayed cerebral ischemia and the interaction between glucose levels and magnesium treatment in subarachnoid hemorrhage patients. The Magnesium in Aneurysmal Subarachnoid Haemorrhage was a phase III randomized placebo-controlled trial assessing the effect of magnesium sulphate on clinical outcome in aneurysmal subarachnoid hemorrhage patients. For the current study, we included only the patients admitted to the University Medical Centre-Utrecht. We calculated hazard ratios for occurrence of delayed cerebral ischemia in patients treated with magnesium vs. placebo for the entire study population, and separately in the subgroups of patients with high and low mean fasting and mean daily glucose levels until onset of delayed cerebral ischemia. We used the cross-product of magnesium and glucose in the regression analysis to evaluate whether an interaction between magnesium and glucose existed. We included 616 patients: 307 received magnesium and 309 placebo; 156 patients had delayed cerebral ischemia. Hazard ratio for magnesium on occurrence of delayed cerebral ischemia was 1·0 (95% confidence interval: 0·7-1·4). Results were similar in patients with low or high fasting or daily glucose levels. We found no interactions between magnesium treatment and high fasting (P = 0·54) and daily glucose (P = 0·60). Magnesium treatment did not reduce the risk of delayed cerebral ischemia in patients with aneurysmal

In vitro formation of the Merkel cell-neurite complex in embryonic mouse whiskers using organotypic co-cultures.

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Ishida, Kentaro; Saito, Tetsuichiro; Mitsui, Toshiyuki

2018-06-01

A Merkel cell-neurite complex is a touch receptor composed of specialized epithelial cells named Merkel cells and peripheral sensory nerves in the skin. Merkel cells are found in touch-sensitive skin components including whisker follicles. The nerve fibers that innervate Merkel cells of a whisker follicle extend from the maxillary branch of the trigeminal ganglion. Whiskers as a sensory organ attribute to the complicated architecture of the Merkel cell-neurite complex, and therefore it is intriguing how the structure is formed. However, observing the dynamic process of the formation of a Merkel cell-neurite complex in whiskers during embryonic development is still difficult. In this study, we tried to develop an organotypic co-culture method of a whisker pad and a trigeminal ganglion explant to form the Merkel cell-neurite complex in vitro. We initially developed two distinct culture methods of a single whisker row and a trigeminal ganglion explant, and then combined them. By dissecting and cultivating a single row from a whisker pad, the morphogenesis of whisker follicles could be observed under a microscope. After the co-cultivation of the whisker row with a trigeminal ganglion explant, a Merkel cell-neurite complex composed of Merkel cells, which were positive for both cytokeratin 8 and SOX2, Neurofilament-H-positive trigeminal nerve fibers and Schwann cells expressing Nestin, SOX2 and SOX10 was observed via immunohistochemical analyses. These results suggest that the process for the formation of a Merkel cell-neurite complex can be observed under a microscope using our organotypic co-culture method. © 2018 Japanese Society of Developmental Biologists.

Solid-state synthesis of Li_4Ti_5O_1_2 whiskers from TiO_2-B

International Nuclear Information System (INIS)

Yao, Wenjun; Zhuang, Wei; Ji, Xiaoyan; Chen, Jingjing; Lu, Xiaohua; Wang, Changsong

2016-01-01

Highlights: • The Li_4Ti_5O_1_2 whiskers were synthesized from TiO_2-B whiskers via a solid state reaction. • The TiO_2-B crystal structure for lithium diffusion is easier than anatase. • The separated diffusion and reaction process is crucial for the solid-state syntheses of Li_4Ti_5O_1_2 whiskers. - Abstract: In this work, Li_4Ti_5O_1_2 (LTO) was synthesized from the precursors of TiO_2-B and anatase whiskers, respectively. The synthesized LTO whiskers from TiO_2-B whiskers via a solid state reaction at 650 °C have a high degree of crystallinity with an average diameter of 300 nm. However, when anatase whiskers were used as the precursor, only particle morphology LTO was produced at 750 °C. The further analysis of the precursors, the intermediate products and the final products reveal that the crystal structure of the anatase hinders the diffusion of lithium, leading to a typical reaction–diffusion process. Under this condition, only particle morphology LTO can be produced. However, the crystal structure of the TiO_2-B is easy for lithium diffusion and the process is performed in two separated steps (i.e., diffusion and reaction), which makes it possible to decrease the solid-state reaction temperature down to 650 °C and then maintain the morphologies of whiskers.

Increases in Intravenous Magnesium Use among Hospitalized Patients: An Institution Cross-Sectional Experience

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Bryce A. Kiberd

2015-06-01

Full Text Available Background: Among hospitalized patients, indications for the measurement of magnesium levels and treatment of hypomagnesemia with intravenous magnesium are not well defined. Recently, there have been reports of worldwide shortages of intravenous magnesium sulphate. Objective: To examine secular trends in the administration of intravenous magnesium on hospital wards at a tertiary care institution. The secondary objective is to identify factors associated with magnesium use among admitted patients. Methods: Retrospective cross-section review of hospitalized patients at a single Canadian tertiary care center. Utilization of non-parental nutrition intravenous magnesium from 2003 to 2013 stratified by hospital ward was examined. In addition, patient level data from select wards (including medical and surgical services was examined at early and more recent time period (4/2006 versus 4/2013. Results: Among the 248,329 hospitalized patients, intravenous magnesium use increased by 2.86 fold from 2003 to 2013. Not all wards had an increase whereas some had nearly a 10 fold increase in use. In the sample ( n = 769, (adjusting for admission magnesium level, presence of an indication for intravenous magnesium, ward location, comorbidity and demographics intravenous magnesium administration was higher (25.8 % versus 5.5 % in 2013 versus 2006 (OR 13.91 (95 % CI, 6.21–31.17, p < 0.001. Despite this increase in intravenous magnesium administration, <3 % of patients were admitted on oral magnesium in 2006 and 2013. For patients receiving intravenous magnesium only a minority were discharged on oral therapy despite low levels. Conclusions: This center has witnessed a considerable increase in the use of in-hospital intravenous magnesium over the last 6 years that cannot be explained for by medical indications. The risks and benefits of this therapy deserve further study. If this change in practice is representative of other North American hospitals, it may be

Effect of carbon coating on spontaneous C12A7 whisker formation

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Zaikovskii, Vladimir I.; Volodin, Alexander M.; Stoyanovskii, Vladimir O.; Cherepanova, Svetlana V.; Vedyagin, Aleksey A.

2018-06-01

A carbon nanoreactor concept was applied to study the stabilization effect of carbon shell on phase composition and morphology of dodecacalcium hepta-aluminate Ca12Al14O33. The starting C12A7 powder was obtained using aluminum and calcium hydroxides as precursors. Carbon shell was formed by a chemical vapor deposition of divinyl at 550 °C. After the calcination at 1400 °C, the product was characterized by X-ray diffraction analysis (XRD) and high resolution transmission electron microscopy (HRTEM). It was observed for a first time that spontaneous formation of calcium aluminate whiskers take place under the conditions described. Each whisker consists of a 'head' (globular particle of 0.5 microns in diameter) and a 'tail' (prolonged whisker of few microns in length and 0.1-0.2 microns in diameter). According to HRTEM, the 'head' is characterized with microcrystal lattice of Ca12Al14O33 compound. XRD data show the presence of CaAl2O4 phase traces. The 'head' and 'tail' of the whisker are covered with structured graphene layers of 10 nm and 3 nm, correspondingly.

Growth, characterization, and physical properties of Bi-Sr-Ca-Cu-O superconducting whiskers

International Nuclear Information System (INIS)

Kraak, W.; Thiele, P.

1996-01-01

Single crystal whiskers of the Bi-based high-T c superconductors have been grown directly from the stoichiometric melt. Conditions for the preferable growth of the (2212) phase and annealing conditions for the conversion from the (2212) phase to the (2223) and (2234) Bi-based superconducting phases are achieved. The orientation and chemical composition of the crystals were characterized by X-ray diffractometry and energy dispersive X-ray analysis. Characteristic structural properties of the whiskers (incommensurable modulation in b-direction, peculiarities of dislocation networks) have been revealed by transmission electron microscopy and electron diffraction. Some special features of the broad superconducting transition in multiphase whiskers have been examined by spatially resolved measurements using low-temperature scanning electron microscopy. (orig.)

An Empirical Model for Estimating the Probability of Electrical Short Circuits from Tin Whiskers. Part 2

Science.gov (United States)

Courey, Karim; Wright, Clara; Asfour, Shihab; Onar, Arzu; Bayliss, Jon; Ludwig, Larry

2009-01-01

In this experiment, an empirical model to quantify the probability of occurrence of an electrical short circuit from tin whiskers as a function of voltage was developed. This empirical model can be used to improve existing risk simulation models. FIB and TEM images of a tin whisker confirm the rare polycrystalline structure on one of the three whiskers studied. FIB cross-section of the card guides verified that the tin finish was bright tin.

Grinding Characteristics Of Directionally Aligned SiC Whisker Wheel-Comparison With Al2O3 Fiber Wheel

Institute of Scientific and Technical Information of China (English)

魏源迁; 山口胜美; 菊泽贤二; 洞口严; 中根正喜

2003-01-01

A unique SiC whisker wheel was invented,in which the whiskers were aligned normally to the grinding wheel surface.In this paper,grindabilities of the SiC whisker wheel are investigated and compared with those of other wheels of SiC grains,Al2O3 grains,as well as Al2O3 long and short fibres which were also aligned normally to the grinding wheel surface,respectively.The main research contents concern grinding characteristics of a directionally aligned SiC whisker wheel such as material-removal volume,wheel-wear rates,integrity of the ground surfaces,grinding ratios and grinding efficiency.Furthermore,grinding wheels of whiskers and fibres have a common disadvantage:they tend to load easily.The authors have proposed a simple method of loading-free grinding to overcome this propensity and investigate some related grinding characteristics under loading-free grinding conditions.

Stability to irradiation of SiGe whisker crystals used for sensors of physical values

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Druzhinin A. A.

2011-04-01

Full Text Available An influence of g-irradiation (Co60 with doze up to 1—1018 сm–2 and magnetic field with induction up to 14 T on conduction of 1–xGex (х = 0,03 whisker crystals with resistivity of 0,08—0,025 Оhm·сm in temperature range 4,2—300 K have been studied. It is shown that whisker crystals resistance faintly varies under irradiation with doze 2·1017 сm–2, while their magnetoresistance substantially changes. The strain sensors stable to irradiation action operating in high magnetic fields on the base of the whiskers have been designed.

Neonatal Whisker Trimming Impairs Fear/Anxiety-Related Emotional Systems of the Amygdala and Social Behaviors in Adult Mice.

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Hitomi Soumiya

Full Text Available Abnormalities in tactile perception, such as sensory defensiveness, are common features in autism spectrum disorder (ASD. While not a diagnostic criterion for ASD, deficits in tactile perception contribute to the observed lack of social communication skills. However, the influence of tactile perception deficits on the development of social behaviors remains uncertain, as do the effects on neuronal circuits related to the emotional regulation of social interactions. In neonatal rodents, whiskers are the most important tactile apparatus, so bilateral whisker trimming is used as a model of early tactile deprivation. To address the influence of tactile deprivation on adult behavior, we performed bilateral whisker trimming in mice for 10 days after birth (BWT10 mice and examined social behaviors, tactile discrimination, and c-Fos expression, a marker of neural activation, in adults after full whisker regrowth. Adult BWT10 mice exhibited significantly shorter crossable distances in the gap-crossing test than age-matched controls, indicating persistent deficits in whisker-dependent tactile perception. In contrast to controls, BWT10 mice exhibited no preference for the social compartment containing a conspecific in the three-chamber test. Furthermore, the development of amygdala circuitry was severely affected in BWT10 mice. Based on the c-Fos expression pattern, hyperactivity was found in BWT10 amygdala circuits for processing fear/anxiety-related responses to height stress but not in circuits for processing reward stimuli during whisker-dependent cued learning. These results demonstrate that neonatal whisker trimming and concomitant whisker-dependent tactile discrimination impairment severely disturbs the development of amygdala-dependent emotional regulation.

Beta 2-adrenergic receptors are colocalized and coregulated with whisker barrels in rat somatosensory cortex

International Nuclear Information System (INIS)

Vos, P.; Kaufmann, D.; Hand, P.J.; Wolfe, B.B.

1990-01-01

Autoradiography has been used to visualize independently the subtypes of beta-adrenergic receptors in rat somatosensory cortex. Beta 2-adrenergic receptors, but not beta 1-adrenergic receptors colocalize with whisker barrels in this tissue. Thus, each whisker sends a specific multisynaptic pathway to the somatosensory cortex that can be histochemically visualized and only one subtype of beta-adrenergic receptor is specifically associated with this cortical representation. Additionally, neonatal lesion of any or all of the whisker follicles results in loss of the corresponding barrel(s) as shown by histochemical markers. This loss is paralleled by a similar loss in the organization of beta 2-adrenergic receptors in the somatosensory cortex. Other results indicate that these beta 2-adrenergic receptors are not involved in moment-to-moment signal transmission in this pathway and, additionally, are not involved in a gross way in the development of whisker-barrel array

High-temperature deformation of SiC-whisker-reinforced MgO-PSZ/mullite composites

International Nuclear Information System (INIS)

Parthasarathy, T.A.; Hay, R.S.; Ruh, R.

1996-01-01

The effect of 33.5 vol% SiC whisker loading on high-temperature deformation of 1 wt% MgO-38.5 wt% zirconia-mullite composites was studied between 1,300 and 1,400 C. At strain rates of 10 -6 to 5 x 10 -4 /s the creep resistance of zirconia-mullite composites without SiC reinforcement was inferior to monolithic mullite of similar grain size. Analysis of the results suggested that the decreased creep resistance of mullite-zirconia composites compared to pure mullite could be at least partially explained by mechanical effects of the weaker zirconia phase, increased effective diffusivity of mullite by zirconia addition, and to the differences in mullite grain morphology. With SiC whisker reinforcement, the deformation rate at high stress was nearly the same as that of the unreinforced material, but at low stress the creep rates of the SiC-reinforced material were significantly lowered. The stress dependence of the creep rate of unreinforced material suggested that diffusional creep was the operative mechanism, while the reinforced material behaved as if a threshold stress for creep existed. The threshold stress could be rationalized based on a whisker network model. This was supported by data on other whisker-containing materials; however, the threshold stress had a temperature dependence that was orders of magnitude higher than the elastic constants, leaving the physical model incomplete. The effects of residual stresses and amorphous phases at whisker/matrix interfaces are invoked to help complete the physical model for creep threshold stress

The 'whisker sign' as an indicator of ochronosis in skeletal scintigraphy

International Nuclear Information System (INIS)

Paul, R.; Ylinen, S.L.

1991-01-01

A patient with alkaptonuria and ochronotic arthrosis was imaged twice with ( 99m Tc-DPD) - once during a bout of arthritic knee pain and once when symptom-free. There was a marked accumulation of radioactivity in the large joints. During the episode of arthritis the knee joints had a higher uptake than when the patient was without symptoms. The intervertebral discs showed a high uptake which extended laterally from the axial vertebral column; the finding gave an impression of whiskers, and this 'whisker sign' may be characteristic of ochronosis. (orig.)

The Formation of Graphite Whiskers in the Primitive Solar Nebula

Science.gov (United States)

Nuth, Joseph A., III; Kimura, Yuki; Lucas, Christopher; Ferguson, Frank; Johnson, Natasha M.

2010-01-01

It has been suggested that carbonaceous grains are efficiently destroyed in the interstellar medium and must either reform in situ at very low pressures and temperatures or in an alternative environment more conducive to grain growth. Graphite whiskers have been discovered associated with high-temperature phases in meteorites such as calcium aluminum inclusions and chondrules, and it has been suggested that the expulsion of such material from proto stellar nebulae could significantly affect the optical properties of the average interstellar grain population. We have experimentally studied the potential for Fischer-Tropsch and Haber-Bosch type reactions to produce organic materials in protostellar systems from the abundant H2, CO, and N2 reacting on the surfaces of available silicate grains. When graphite grains are repeatedly exposed to H2, CO, and N2 at 875 K abundant graphite whiskers are observed to form on or from the surfaces of the graphite grains. In a dense, turbulent nebula, such extended whiskers are very likely to be broken off, and fragments could be ejected either in polar jets or by photon pressure after transport to the outer reaches of the nebula.

Whisker motor cortex reorganization after superior colliculus output suppression in adult rats.

Science.gov (United States)

Veronesi, Carlo; Maggiolini, Emma; Franchi, Gianfranco

2013-10-01

The effect of unilateral superior colliculus (SC) output suppression on the ipsilateral whisker motor cortex (WMC) was studied at different time points after tetrodotoxin and quinolinic acid injections, in adult rats. The WMC output was assessed by mapping the movement evoked by intracortical microstimulation (ICMS) and by recording the ICMS-evoked electromyographic (EMG) responses from contralateral whisker muscles. At 1 h after SC injections, the WMC showed: (i) a strong decrease in contralateral whisker sites, (ii) a strong increase in ipsilateral whisker sites and in ineffective sites, and (iii) a strong increase in threshold current values. At 6 h after injections, the WMC size had shrunk to 60% of the control value and forelimb representation had expanded into the lateral part of the normal WMC. Thereafter, the size of the WMC recovered, returning to nearly normal 12 h later (94% of control) and persisted unchanged over time (1-3 weeks). The ICMS-evoked EMG response area decreased at 1 h after SC lesion and had recovered its baseline value 12 h later. Conversely, the latency of ICMS-evoked EMG responses had increased by 1 h and continued to increase for as long as 3 weeks following the lesion. These findings provide physiological evidence that SC output suppression persistently withdrew the direct excitatory drive from whisker motoneurons and induced changes in the WMC. We suggest that the changes in the WMC are a form of reversible short-term reorganization that is induced by SC lesion. The persistent latency increase in the ICMS-evoked EMG response suggested that the recovery of basic WMC excitability did not take place with the recovery of normal explorative behaviour. © 2013 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Thermodynamic analysis of dust sulphation reactions

Energy Technology Data Exchange (ETDEWEB)

Yang Yongxiang; Jokilaakso, A.

1997-12-31

Sulphation reactions of metal oxides with SO{sub 2} and O. or SO{sub 3} play significant roles in sulphation roasting of sulphide and oxide minerals as well as in desulphurisation process of combustion gases. In metallurgical waste-heat boilers for sulphide smelting, the sulphation of the oxidic flue dust in the atmosphere containing sulphur oxides is an unavoidable process, and the sulphation reactions have to be guided in a controlled way in the proper parts of the gas handling equipment. In this report, some thermodynamic analyses were conducted for the oxide sulphation reactions in relation to sulphide smelting processes. The phase stability of Me-S-O systems especially for oxides - sulphates equilibrium was studied under different thermodynamic conditions of gas compositions and temperatures. The sulphate stability was analysed for an example of gas compositions in the copper flash smelter of Outokumpu Harjavalta Metals Oy, in relation to temperature. In the report, most of the information was from literature. Moreover, a number of thermodynamic computations were carried out with the HSC program, and the constructed phase stability diagrams were compared with those from the literature whenever possible. The maximum temperatures for stable sulphates under normal operating conditions of the waste-heat boilers in sulphide smelting processes were obtained. This report will serve as the basis for the kinetic studies of the sulphation reactions and the sulphation reaction modelling in pyrometallurgical processes. (orig.) SULA 2 Programme. 36 refs.

Solid-state synthesis of Li{sub 4}Ti{sub 5}O{sub 12} whiskers from TiO{sub 2}-B

Energy Technology Data Exchange (ETDEWEB)

Yao, Wenjun [State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, No. 5 Xin Mofan Road, Nanjing 210009 (China); Zhuang, Wei [State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, No. 5 Xin Mofan Road, Nanjing 210009 (China); College of Biotechnology and Pharmaceutical Engineering, National Engineering Technique Research Center for Biotechnology, Nanjing Tech University, No. 30, Puzhu South Road, Nanjing 211816 (China); Ji, Xiaoyan [Division of Energy Science/Energy Engineering, Luleå University of Technology, Luleå 97187 Sweden (Sweden); Chen, Jingjing; Lu, Xiaohua [State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, No. 5 Xin Mofan Road, Nanjing 210009 (China); Wang, Changsong, E-mail: wcs@njtech.edu.cn [State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, No. 5 Xin Mofan Road, Nanjing 210009 (China)

2016-03-15

Highlights: • The Li{sub 4}Ti{sub 5}O{sub 12} whiskers were synthesized from TiO{sub 2}-B whiskers via a solid state reaction. • The TiO{sub 2}-B crystal structure for lithium diffusion is easier than anatase. • The separated diffusion and reaction process is crucial for the solid-state syntheses of Li{sub 4}Ti{sub 5}O{sub 12} whiskers. - Abstract: In this work, Li{sub 4}Ti{sub 5}O{sub 12} (LTO) was synthesized from the precursors of TiO{sub 2}-B and anatase whiskers, respectively. The synthesized LTO whiskers from TiO{sub 2}-B whiskers via a solid state reaction at 650 °C have a high degree of crystallinity with an average diameter of 300 nm. However, when anatase whiskers were used as the precursor, only particle morphology LTO was produced at 750 °C. The further analysis of the precursors, the intermediate products and the final products reveal that the crystal structure of the anatase hinders the diffusion of lithium, leading to a typical reaction–diffusion process. Under this condition, only particle morphology LTO can be produced. However, the crystal structure of the TiO{sub 2}-B is easy for lithium diffusion and the process is performed in two separated steps (i.e., diffusion and reaction), which makes it possible to decrease the solid-state reaction temperature down to 650 °C and then maintain the morphologies of whiskers.

Predictors of extra care among magnesium sulphate treated eclamptic patients at Muhimbili National Hospital, Tanzania.

Science.gov (United States)

Muganyizi, Projestine S; Shagdara, Mohammed S

2011-06-03

The inclusion of Magnesium Sulphate (MgSO4) as a gold standard in the treatment of eclampsia has substantially reduced incidences of repeated fits, eclamptic morbidity and deaths. However, despite treatment with MgSO4, a proportion of patients need extra medical/nursing attention and prolonged stay in the intensive care unit (ICU). The literature on the underlying factors for the need of extra care in the MgSO4 era is lacking. This study sought to establish predictors of extra care in ICU among eclamptic patients after treatment with MgSO4 at Muhimbili National Hospital (MNH). Data were obtained from hospital records of eclamptic patients who were admitted at MNH and treated with MgSO4 from January 1st to December 31st, 2008. Based on set criteria, patients who needed extra care were identified. Analysis was performed using PASW statistics 18 whereby frequencies, cross-tabulations, bivariate and multiple logistic regressions were performed. A total of 366 eclamptic patients were admitted and treated with MgSO4 at MNH during a 12 month study period in 2008. Most of these (76%) were referred from district hospitals and 132 (36%) met the criteria for extra care in ICU. After adjusting for other variables, the risk of extra care in ICU for patients who were admitted with altered consciousness was double (OR = 2.3; 95% CI: 1.3-4.0) that of the ones admitted in alert state. The risk or need of extra care increased by increasing time to delivery and was doubled (OR = 2.0; 95% CI:1.1-3.7) if it was between 12 and 24 hours and tenfold elevated (OR = 10.0; 95% CI:4.3-23.6) if beyond 24 hours as compared to when time to delivery was less than 12 hours.Abdominal delivery was also independently associated with increased risk compared to vaginal delivery (OR = 2.5; 95%CI: 1.4-4.5). The type of referral and number of fits were associated with extra care in ICU but this association was wholly explained by the clinical status of the patient on admission to MNH and prolonged time

Predictors of extra care among magnesium sulphate treated eclamptic patients at Muhimbili National Hospital, Tanzania

Directory of Open Access Journals (Sweden)

Shagdara Mohammed S

2011-06-01

Full Text Available Abstract Background The inclusion of Magnesium Sulphate (MgSO4 as a gold standard in the treatment of eclampsia has substantially reduced incidences of repeated fits, eclamptic morbidity and deaths. However, despite treatment with MgSO4, a proportion of patients need extra medical/nursing attention and prolonged stay in the intensive care unit (ICU. The literature on the underlying factors for the need of extra care in the MgSO4 era is lacking. This study sought to establish predictors of extra care in ICU among eclamptic patients after treatment with MgSO4 at Muhimbili National Hospital (MNH. Methods Data were obtained from hospital records of eclamptic patients who were admitted at MNH and treated with MgSO4 from January 1st to December 31st, 2008. Based on set criteria, patients who needed extra care were identified. Analysis was performed using PASW statistics 18 whereby frequencies, cross-tabulations, bivariate and multiple logistic regressions were performed. Results A total of 366 eclamptic patients were admitted and treated with MgSO4 at MNH during a 12 month study period in 2008. Most of these (76% were referred from district hospitals and132 (36% met the criteria for extra care in ICU. After adjusting for other variables, the risk of extra care in ICU for patients who were admitted with altered consciousness was double (OR = 2.3; 95% CI: 1.3-4.0 that of the ones admitted in alert state. The risk or need of extra care increased by increasing time to delivery and was doubled (OR = 2.0; 95% CI:1.1-3.7 if it was between 12 and 24 hours and tenfold elevated (OR = 10.0; 95% CI:4.3-23.6 if beyond 24 hours as compared to when time to delivery was less than 12 hours. Abdominal delivery was also independently associated with increased risk compared to vaginal delivery (OR = 2.5; 95%CI: 1.4-4.5. The type of referral and number of fits were associated with extra care in ICU but this association was wholly explained by the clinical status of the

Preparation of mullite whiskers reinforced SiC/Al2O3 composites by microwave sintering

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Wei Li

2016-12-01

Full Text Available Mullite whiskers reinforced SiC/Al2O3 composites were prepared by microwave sintering in a microwave chamber with TE666 resonant mode. Original SiC particles were coated with SiO2 using sol-gel processing and mixed with Al2O3 particles. Mullite was formed in the reaction between SiO2 and Al2O3. The isostatically pressed cylindrical pellets were sintered from 1350 °C to 1600 °C for 30 min. Physical and chemical responses were investigated by detecting changes in reflected power during the microwave sintering process. XRD was carried out to characterize the samples and showed that mullite could be formed at 1200 °C. Bridging of mullite whiskers between Al2O3 and SiC particles was observed by SEM and is due to a so-called local hot spot effect, which was the unique feature for microwave sintering. The optimized microwave sintering temperature was 1500 °C corresponding to the maximum amount of mullite whiskers within SiC/Al2O3 composites. The high electro-magnetic field enhanced the decomposition of mullite at higher temperatures above 1550 °C. The mechanical properties of mullite whiskers reinforced SiC/Al2O3 composites are much better than the SiC/Al2O3 composites without mullite whiskers.

Biopolymer nanocomposite films reinforced with nanocellulose whiskers

Science.gov (United States)

Amit Saxena; Marcus Foston; Mohamad Kassaee; Thomas J. Elder; Arthur J. Ragauskas

2011-01-01

A xylan nanocomposite film with improved strength and barrier properties was prepared by a solution casting using nanocellulose whiskers as a reinforcing agent. The 13C cross-polarization magic angle spinning (CP/MAS) nuclear magnetic resonance (NMR) analysis of the spectral data obtained for the NCW/xylan nanocomposite films indicated the signal intensity originating...

Sulphate removal from sodium sulphate-rich brine and recovery of barium as a barium salt mixture.

Science.gov (United States)

Vadapalli, Viswanath R K; Zvimba, John N; Mulopo, Jean; Motaung, Solly

2013-01-01

Sulphate removal from sodium sulphate-rich brine using barium hydroxide and recovery of the barium salts has been investigated. The sodium sulphate-rich brine treated with different dosages of barium hydroxide to precipitate barium sulphate showed sulphate removal from 13.5 g/L to less than 400 mg/L over 60 min using a barium to sulphate molar ratio of 1.1. The thermal conversion of precipitated barium sulphate to barium sulphide achieved a conversion yield of 85% using coal as both a reducing agent and an energy source. The recovery of a pure mixture of barium salts from barium sulphide, which involved dissolution of barium sulphide and reaction with ammonium hydroxide resulted in recovery of a mixture of barium carbonate (62%) and barium hydroxide (38%), which is a critical input raw material for barium salts based acid mine drainage (AMD) desalination technologies. Under alkaline conditions of this barium salt mixture recovery process, ammonia gas is given off, while hydrogen sulfide is retained in solution as bisulfide species, and this provides basis for ammonium hydroxide separation and recovery for reuse, with hydrogen sulfide also recoverable for further industrial applications such as sulfur production by subsequent stripping.

Hydrothermal Preparation and Characterization of Ultralong Strontium-Substituted Hydroxyapatite Whiskers Using Acetamide as Homogeneous Precipitation Reagent

Science.gov (United States)

Xu, Jianqiang; Yang, Yaoqi; Wan, Rong; Zhang, Weibin

2014-01-01

The ultralong strontium- (Sr-) substituted hydroxyapatite (SrHAp) whiskers were successfully prepared using acetamide as homogeneous precipitation reagent. The effect of the Sr substitution amount on the lattice constants and proliferation of human osteoblast cells (MG-63) was further investigated. The results showed that the SrHAp whiskers with diameter of 0.2–12 μm and ultralong length up to 200 μm were obtained and the Sr substitution level could be facilely tailored by regulating the initial molar ratio of Sr/(Sr + Ca) in raw materials. The Sr2+ replaced part of Ca2+ and the lattice constants increased apparently with the increase of the Sr substitution amount. Compared with the pure HAp whiskers, the Sr substitution apparently stimulated the proliferation of MG-63 at certain extracted concentrations. Our study suggested that the obtained SrHAp whiskers might be used as bioactive and mechanical reinforcement materials for hard tissue regeneration applications. PMID:24592192

Repeated whisker stimulation evokes invariant neuronal responses in the dorsolateral striatum of anesthetized rats: a potential correlate of sensorimotor habits.

Science.gov (United States)

Mowery, Todd M; Harrold, Jon B; Alloway, Kevin D

2011-05-01

The dorsolateral striatum (DLS) receives extensive projections from primary somatosensory cortex (SI), but very few studies have used somesthetic stimulation to characterize the sensory coding properties of DLS neurons. In this study, we used computer-controlled whisker deflections to characterize the extracellular responses of DLS neurons in rats lightly anesthetized with isoflurane. When multiple whiskers were synchronously deflected by rapid back-and-forth movements, whisker-sensitive neurons in the DLS responded to both directions of movement. The latency and magnitude of these neuronal responses displayed very little variation with changes in the rate (2, 5, or 8 Hz) of whisker stimulation. Simultaneous recordings in SI barrel cortex and the DLS revealed important distinctions in the neuronal responses of these serially connected brain regions. In contrast to DLS neurons, SI neurons were activated by the initial deflection of the whiskers but did not respond when the whiskers moved back to their original position. As the rate of whisker stimulation increased, SI responsiveness declined, and the latencies of the responses increased. In fact, when whiskers were deflected at 5 or 8 Hz, many neurons in the DLS responded before the SI neurons. These results and earlier anatomic findings suggest that a component of the sensory-induced response in the DLS is mediated by inputs from the thalamus. Furthermore, the lack of sensory adaptation in the DLS may represent a critical part of the neural mechanism by which the DLS encodes stimulus-response associations that trigger motor habits and other stimulus-evoked behaviors that are not contingent on rewarded outcomes.

Anomalous growth of whisker-like bismuth-tin extrusions from tin-enriched tin-Bi deposits

International Nuclear Information System (INIS)

Hu, C.-C.; Tsai, Y.-D.; Lin, C.-C.; Lee, G.-L.; Chen, S.-W.; Lee, T.-C.; Wen, T.-C.

2009-01-01

This article shows the first finding that the anomalous growth of Bi-Sn extrusions from tin-enriched alloys (Sn-xBi with x between 20 and 10 wt.%) can be induced by post-plating annealing in N 2 between 145 and 260 deg. C for 10 min although metal whiskers were commonly formed on the surface of pure metals or alloys of the enriched component. From SEM observations, very similar to Sn whiskers, Bi-Sn extrusions vary in size, shape, length, and diameter with changing the annealing temperature, which are highly important in regarding the potential for failure of electronic products. Annealing resulting in thermal expansion of Sn grains is believed to squeeze the Bi-Sn alloys with relatively low melting points to form whisker-like extrusions although the exact mechanism is unclear

Whiskers de fibra de sisal obtidos sob diferentes condições de hidrólise ácida: efeito do tempo e da temperatura de extração Whiskers from sisal fibers obtained under different acid hydrolysis conditions: effect of time and temperature of extraction

Directory of Open Access Journals (Sweden)

Kelcilene B. R. Teodoro

2011-01-01

Full Text Available Neste trabalho, os efeitos de diferentes condições de tempo e temperatura usados para a preparação de whiskers de sisal foram investigados com o objetivo de se determinar a influência destes parâmetros experimentais na morfologia, cristalinidade e estabilidade térmica dos materiais preparados. A obtenção dos whiskers deu-se após o pré-branqueamento da fibra de sisal com solução alcalina de peróxido de hidrogênio. A fibra branqueada foi submetida ao processo de hidrólise com solução de ácido sulfúrico 60% (m/m sob três diferentes condições de temperatura e tempos de extração: 45 °C e 60 minutos (WS45_60; 45 °C e 75 minutos (WS45_75 e 60 °C e 30 minutos (WS60_30. Os whiskers foram caracterizados quanto à morfologia por microscopia eletrônica de transmissão (MET, quanto à cristalinidade (DRX, carga superficial (potencial zeta , teor de enxofre (análise elementar e quanto à estabilidade térmica por termogravimetria (TGA. Os resultados mostraram que os whiskers de sisal apresentaram comprimento e diâmetro médios e 210 nm e 5 nm respectivamente. Devido à alta aglomeração dos whiskers, diferenças relativas às características dimensionais não puderam ser determinadas. Os resultados obtidos revelaram uma forte dependência da cristalinidade final dos whiskers com a temperatura e tempo de extração. O uso de temperatura mais alta (60 °C associado a um menor tempo de extração (30 minutos resulta em whiskers com boa estabilidade térmica (235 °C, maior cristalinidade e sem o comprometimento da estrutura cristalina da celulose.In this work, the effects of different conditions of time and temperature, used for the preparation of whiskers from sisal, were investigated to determine the influence of experimental parameters on morphology, crystallinity and thermal stability of materials prepared. The whiskers were obtained after the bleaching of sisal raw fiber with a solution of hydrogen peroxide alkaline. The

An Investigation of the Electrical Short Circuit Characteristics of Tin Whiskers

Science.gov (United States)

Courey, Karim J.

2008-01-01

Existing risk simulations make the assumption that when a free tin whisker has bridged two adjacent exposed electrical conductors, the result is an electrical short circuit. This conservative assumption is made because shorting is a random event that has a currently unknown probability associated with it. Due to contact resistance electrical shorts may not occur at lower voltage levels. In this experiment, we study the effect of varying voltage on the breakdown of the contact resistance which leads to a short circuit. From this data we can estimate the probability of an electrical short, as a function of voltage, given that a free tin whisker has bridged two adjacent exposed electrical conductors. Also, three tin whiskers grown from the same Space Shuttle Orbiter card guide used in the aforementioned experiment were cross-sectioned and studied using a focused ion beam (FIB). The rare polycrystalline structure seen in the FIB cross section was confirmed using transmission electron microscopy (TEM). The FIB was also used to cross section two card guides to facilitate the measurement of the grain size to determine that the tin plating on the card guides had a bright finish.

Microscopic Structure of Metal Whiskers

Science.gov (United States)

Borra, Vamsi; Georgiev, Daniel G.; Karpov, V. G.; Shvydka, Diana

2018-05-01

We present TEM images of the interior of metal whiskers (MWs) grown on electroplated Sn films. Along with earlier published information, our observations focus on a number of questions, such as, why MWs' diameters are in the micron range (significantly exceeding the typical nanosizes of nuclei in solids), why the diameters remain practically unchanged in the course of MW growth, what the nature of MW diameter stochasticity is, and what the origin of the well-known striation structure of MW side surfaces is. In an attempt to address such questions, we perform an in-depth study of MW structure at the nanoscale by detaching a MW from its original film, reducing its size to a thin slice by cutting its sides by a focused ion beam, and performing TEM on that structure. Also, we examine the root of the MW and Cu-Sn interface for the intermetallic compounds. Our TEM observations reveal a rich nontrivial morphology suggesting that MWs may consist of many side-by-side grown filaments. This structure appears to extend to the outside whisker surface and be the reason for the striation. In addition, we put forward a theory where nucleation of multiple thin metal needles results in micron-scale and larger MW diameters. This theory is developed in the average field approximation similar to the roughening transitions of metal surfaces. The theory also predicts MW nucleation barriers and other observed features.

The role of whiskers in compensation of visual deficit in a mouse model of retinal degeneration.

Science.gov (United States)

Voller, Jaroslav; Potužáková, Barbora; Šimeček, Vojtěch; Vožeh, František

2014-01-13

Sensory deprivation in one modality can enhance the development of the remaining modalities via mechanisms of synaptic plasticity. Mice of the C3H strain suffer from RD1 retinal degeneration that leads to visual impairment at weaning age. We examined a role of whiskers in compensation of the visual deficit. In order to differentiate the contribution of the whiskers from other mechanisms that can take part in the compensation, we investigated the effect of both chronic and acute tactile deprivation. Three-month-old mice were used. We examined motor skills (rotarod, beam walking test), gait control (CatWalk system), spontaneous motor activity (open field) and CNS excitability to an acoustic stimulus for assessment of compensatory changes in auditory system (audiogenic epilepsy). In the sighted mice, the only effect was a decline in their rotarod test performance after acute whisker removal. In the blind animals, chronic tactile deprivation caused changes in their gait and impaired the performance in motor tests. Some other compensatory mechanisms were involved but the whiskers are essential for the compensation as it emerged from more marked change of gait and the worsening of the motor performance after the acute whisker removal. Both chronic and acute tactile deprivation induced anxiety-like behaviour. Only a combination of blindness and chronic tactile deprivation led to an increased sense of hearing. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Sulphate reduction in the Aespoe HRL tunnel

International Nuclear Information System (INIS)

Gustafson, G.; Pedersen, K.; Tullborg, E.L.; Wallin, B.; Wikberg, P.

1995-12-01

Evidence and indications of sulphate reduction based on geological, hydrogeological, groundwater, isotope and microbial data gathered in and around the Aespoe Hard Rock Laboratory tunnel have been evaluated. This integrated investigation showed that sulphate reduction had taken place in the past but is most likely also an ongoing process. Anaerobic sulphate-reducing bacteria can live in marine sediments, in the tunnel sections under the sea and in deep groundwaters, since there is no access to oxygen. The sulphate-reducing bacteria seem to thrive when the Cl - concentration of the groundwater is 4000-6000 mg/l. Sulphate reduction is an in situ process but the resulting hydrogen-sulphide rich water can be transported to other locations. A more vigorous sulphate reduction takes place when the organic content in the groundwater is high (>10 mg/l DOC) which is the case in the sediments and in the groundwaters under the sea. Some bacteria use hydrogen as an electron donor instead of organic carbon and can therefore live in deep environments where access to organic material is limited. The sulphate-reducing bacteria seem to adapt to changing flow situations caused by the tunnel construction relatively fast. Sulphate reduction seems to have occurred and will probably occur where conditions are favourable for the sulphate-reducing bacteria such as anaerobic brackish groundwater with dissolved sulphate and organic carbon or hydrogen. 59 refs, 37 figs, 6 tabs

Estimating the Probability of Electrical Short Circuits from Tin Whiskers. Part 2

Science.gov (United States)

Courey, Karim J.; Asfour, Shihab S.; Onar, Arzu; Bayliss, Jon A.; Ludwig, Larry L.; Wright, Maria C.

2010-01-01

To comply with lead-free legislation, many manufacturers have converted from tin-lead to pure tin finishes of electronic components. However, pure tin finishes have a greater propensity to grow tin whiskers than tin-lead finishes. Since tin whiskers present an electrical short circuit hazard in electronic components, simulations have been developed to quantify the risk of said short circuits occurring. Existing risk simulations make the assumption that when a free tin whisker has bridged two adjacent exposed electrical conductors, the result is an electrical short circuit. This conservative assumption is made because shorting is a random event that had an unknown probability associated with it. Note however that due to contact resistance electrical shorts may not occur at lower voltage levels. In our first article we developed an empirical probability model for tin whisker shorting. In this paper, we develop a more comprehensive empirical model using a refined experiment with a larger sample size, in which we studied the effect of varying voltage on the breakdown of the contact resistance which leads to a short circuit. From the resulting data we estimated the probability distribution of an electrical short, as a function of voltage. In addition, the unexpected polycrystalline structure seen in the focused ion beam (FIB) cross section in the first experiment was confirmed in this experiment using transmission electron microscopy (TEM). The FIB was also used to cross section two card guides to facilitate the measurement of the grain size of each card guide's tin plating to determine its finish .

Two whisker motor areas in the rat cortex: evidence from thalamocortical connections.

Science.gov (United States)

Mohammed, Hisham; Jain, Neeraj

2014-02-15

In primates, the motor cortex consists of at least seven different areas, which are involved in movement planning, coordination, initiation, and execution. However, for rats, only the primary motor cortex has been well described. A rostrally located second motor area has been proposed, but its extent, organization, and even definitive existence remain uncertain. Only a rostral forelimb area (RFA) has been definitively described, besides few reports of a rostral hindlimb area. We have previously proposed existence of a second whisker area, which we termed the rostral whisker area (RWA), based on its differential response to intracortical microstimulation compared with the caudal whisker area (CWA) in animals under deep anesthesia (Tandon et al. [2008] Eur J Neurosci 27:228). To establish that RWA is distinct from the caudally contiguous CWA, we determined sources of thalamic inputs to the two proposed whisker areas. Sources of inputs to RFA, caudal forelimb area (CFA), and caudal hindlimb region were determined for comparison. The results show that RWA and CWA can be distinguished based on differences in their thalamic inputs. RWA receives major projections from mediodorsal and ventromedial nuclei, whereas the major projections to CWA are from the ventral anterior, ventrolateral, and posterior nuclei. Moreover, the thalamic nuclei that provide major inputs to RWA are the same as for RFA, and the nuclei projecting to CWA are same as for CFA. The results suggest that rats have a second rostrally located motor area with RWA and RFA as its constituents. Copyright © 2013 Wiley Periodicals, Inc.

Repeated whisker stimulation evokes invariant neuronal responses in the dorsolateral striatum of anesthetized rats: a potential correlate of sensorimotor habits

OpenAIRE

Mowery, Todd M.; Harrold, Jon B.; Alloway, Kevin D.

2011-01-01

The dorsolateral striatum (DLS) receives extensive projections from primary somatosensory cortex (SI), but very few studies have used somesthetic stimulation to characterize the sensory coding properties of DLS neurons. In this study, we used computer-controlled whisker deflections to characterize the extracellular responses of DLS neurons in rats lightly anesthetized with isoflurane. When multiple whiskers were synchronously deflected by rapid back-and-forth movements, whisker-sensitive neur...

Neurons within the trigeminal mesencephalic nucleus encode for the kinematic parameters of the whisker pad macrovibrissae.

Science.gov (United States)

Mameli, Ombretta; Caria, Marcello A; Biagi, Francesca; Zedda, Marco; Farina, Vittorio

2017-05-01

It has been recently shown in rats that spontaneous movements of whisker pad macrovibrissae elicited evoked responses in the trigeminal mesencephalic nucleus (Me5). In the present study, electrophysiological and neuroanatomical experiments were performed in anesthetized rats to evaluate whether, besides the whisker displacement per se, the Me5 neurons are also involved in encoding the kinematic properties of macrovibrissae movements, and also whether, as reported for the trigeminal ganglion, even within the Me5 nucleus exists a neuroanatomical representation of the whisker pad macrovibrissae. Extracellular electrical activity of single Me5 neurons was recorded before, during, and after mechanical deflection of the ipsilateral whisker pad macrovibrissae in different directions, and with different velocities and amplitudes. In several groups of animals, single or multiple injections of the tracer Dil were performed into the whisker pad of one side, in close proximity to the vibrissae follicles, in order to label the peripheral terminals of the Me5 neurons innervating the macrovibrissae (whisking-neurons), and therefore, the respective perikaria within the nucleus. Results showed that: (1) the whisker pad macrovibrissae were represented in the medial-caudal part of the Me5 nucleus by a single cluster of cells whose number seemed to match that of the macrovibrissae; (2) macrovibrissae mechanical deflection elicited significant responses in the Me5 whisking-neurons, which were related to the direction, amplitude, and frequency of the applied deflection. The specific functional role of Me5 neurons involved in encoding proprioceptive information arising from the macrovibrissae movements is discussed within the framework of the whole trigeminal nuclei activities. © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

Design of the Intravenous Magnesium Efficacy in Acute Stroke (IMAGES) trial.

Science.gov (United States)

Bradford, Andrew; Lees, Kennedy

2000-01-01

The Intravenous Magnesium Efficacy in Acute Stroke (IMAGES) trial is a multicentre,randomised, placebo-controlled trial of magnesium sulphate (MgSO4) funded by the UK Medical Research Council. When complete, it will be the largest single neuroprotective study undertaken to date. Conscious patients presenting within 12 h of acute stroke with limb weakness are eligible. The primary outcome measure is combined death and disability as measured using the Barthel Index at 90-day follow up. By randomizing 2700 patients, the study will have 84% power to detect a 5.5% absolute reduction in the primary end-point. By April 2000, 86 centres were participating, with representation in Canada, USA, Europe, South America, Singapore and Australia. So far, 1206 patients have been randomised, of whom 37% were treated within 6 h. Overall 3-month mortality was 20% and the primary outcome event rate was 43%. The study is ongoing and centres worldwide are encouraged to participate.

Galvano-magnetic properties and Shubnikov de Haas effect of Te-whiskers

International Nuclear Information System (INIS)

Berezovets, Veacheslav; Bondarchuk, Nikolai; Nikolaeva, Albina; Nijankovskii, Victor

2009-01-01

The work is devoted to investigation of the peculiarities of magnetoresistance, Hall effect and Shubnikov de Haas oscillations in Te-whiskers. Te-whiskers was prepared from vapor-gas phase on the substrate pure tellurium and grown naturally, of the walls of a crucible in the course of growing Te single crystals by the Czochralski method . The measurements of the galvanomagnetic properties and Shubnikov de Haas oscillation correspond to the notion of the occurrence of the effect of intraband magnetic breakdown when two different quasi-classical cyclotron trajectories coexist simultaneously in a magnetic field. This effect is a consequence of the presence of the saddle point in the dispersion law of the tellurium valence band. (authors)

Copper sulphate poisoning in horses

Energy Technology Data Exchange (ETDEWEB)

Bauer, M

1975-01-01

In the archives of the Clinic for Internal Diseases of Domestic Animals at the Veterinary Faculty of Zagreb University some thirty cases of horse disease diagnosed as copper sulphate poisoning were noted. The data correspond in many respects to the clinical findings of copper sulphate poisoning in other domestic animals. A series of experimental horse poisonings were undertaken in order to determine the toxicity of copper sulphate. The research results are as follows: Horses are sensitive to copper sulphate. Even a single application of 0.125 g/kg body weight in 1% concentration by means of incubation into the stomach causes stomach and gut disturbances and other poisoning symptoms. Poisoning occurs in two types: acute and chronic. The former appears after one to three applications of copper sulphate solution and is characterized by gastroenteritis, haemolysis, jaundice and haemoglobinuria with signs of consecutive damage of kidney, liver and other organs. The disease, from the first application to death lasts for two weeks. Chronic poisoning is caused by ingestion of dry copper sulphate in food (1% solution dried on hay or clover) for two or more months. There are chronic disturbances of stomach and gut and loss of weight, and consecutive (three to four) haemolytic crises similar to those of acute poisoning. From the beginning of poisoning to death six or more months can elapse.

The 'whisker sign' as an indicator of ochronosis in skeletal scintigraphy

Energy Technology Data Exchange (ETDEWEB)

Paul, R.; Ylinen, S.L. (Turku Univ. (Finland). Dept. of Nuclear Medicine)

1991-03-01

A patient with alkaptonuria and ochronotic arthrosis was imaged twice with ({sup 99m}Tc-DPD) - once during a bout of arthritic knee pain and once when symptom-free. There was a marked accumulation of radioactivity in the large joints. During the episode of arthritis the knee joints had a higher uptake than when the patient was without symptoms. The intervertebral discs showed a high uptake which extended laterally from the axial vertebral column; the finding gave an impression of whiskers, and this 'whisker sign' may be characteristic of ochronosis. (orig.).

Magnesium, magnesium alloys, and magnesium composites

National Research Council Canada - National Science Library

Gupta, M; Sharon, Nai Mui Ling

2011-01-01

"Properties of Magnesium Composites for Material Scientists, Engineers and Selectors is the first book-length reference to provide an insight into current and future magnesium-based materials in terms...

A QUASI EXPERIMENTAL STUDY TO EVALUATE EFFECTIVENESS OF GLYCERIN MAGNESIUM SULPHATE DRESSING ON PHLEBITIS AMONG PATIENTS UNDERGOING PERIPHERAL INTRAVENOUS INFUSION IN SELECTED HOSPITAL,VADODARA

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Ravindra HN, Patel Krupa D

2015-07-01

Full Text Available Introduction: Intravenous therapy is indicated for many reasons. A significant number of patients admitted into hospital receive some forms of intravenous therapy through peripheral venous cannula, which is a common procedure carried out in hospital to allow rapid and accurate administration of medication. However, the intravenous cannulation can have undesirable effects, the most of which is phlebitis, which is due to mechanical, chemical or infectious cause. Method: In this study quasi-experimental research approach was used. Non probability purposive sampling technique was used to select the sample from the selected hospital. The research design adopted for the study was pre-test, post-test control group design. In the present study a sample of 60 hospitalised patients and who met the inclusion criteria was selected from the target population. In this study the instruments used are baseline Performa, structured interview schedule to assess the subjective symptoms and observation scale to observe the objective symptoms. Result: In experimental group post test mean score 1.10, SD was 0.71 respectively. In control group post test mean score 2.53, SD was 0.78 respectively. The obtained value 7.454 statistically was significant at 0.001 levels. So research hypothesis was accepted. So there was significant difference between post intervention phlebitis among the experimental group and control group. Discussion: In the research study findings revealed that Glycerin Magnesium sulphate dressing is highly effective in decrease phlebitis level to the patients.

Reinforcement of thermoplastic chitosan hydrogel using chitin whiskers optimized with response surface methodology.

Science.gov (United States)

Sun, Guohui; Zhang, Xin; Bao, Zixian; Lang, Xuqian; Zhou, Zhongzheng; Li, Yang; Feng, Chao; Chen, Xiguang

2018-06-01

To strengthen the mechanical strength of thermo-sensitive hydroxybutyl chitosan (HBC) hydrogel, chitin whiskers were used as sticker to fabricate reinforced HBC (HBCW) hydrogel by using response surface methodology. Unlike the intrinsic network of HBC hydrogel, HBCW hydrogel showed a laminar shape with firm structure. The preparation condition was optimized by three-factor-three-level Box-Behnken design. The maximum mechanical strength (1011.11 Pa) was achieved at 50 °C, when the concentrations of HBC and chitin whiskers were 5.1 wt% and 2.0 wt%, respectively. The effects of temperature, pH value and NaCl concentration on mechanical strength of HBCW hydrogels were investigated via the oscillatory stress sweeps. The results showed that HBCW hydrogel could reach the maximum stiffness (∼1126 Pa) at 37 °C pH 12.0. Low pH and high salty ions could decrease the stability of hydrogel, while chitin whiskers could increase the stress tolerance and related ruptured strain of HBCW hydrogels. Copyright © 2018. Published by Elsevier Ltd.

A dose-finding randomised controlled trial of magnesium sulphate as an adjuvant in ultrasound-guided supraclavicular brachial plexus block

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Versha Verma

2017-01-01

Full Text Available Background and Aim: Magnesium sulphate (MgSO4 has been used as an adjuvant in brachial plexus block with encouraging results; however, there is no consensus regarding its optimal dose. Thereby, we compared the efficacy of two doses of MgSO4 as an adjuvant in ultrasound (USG guided supraclavicular brachial plexus block. Methods: Ninety patients, aged 20–60 years, belonging to American Society of Anesthesiologists physical status 1 or 2, were given USG-guided supraclavicular block. Group B (n = 30 received 20 ml of 0.5%bupivacaine + 5 ml normal saline (NS, Group BM0.5(n = 30 received 20 ml of 0.5%bupivacaine + 3.75 ml NS and 125 mg MgSO4 (1.25 ml and Group BM1(n = 30 received 20 ml of 0.5%bupivacaine + 2.5 ml NS and 250 mg MgSO4 (2.5 ml. The primary outcome of study was the duration of post-operative analgesia. The normally distributed data were analysed using analysis of variance and categorical data analysed using Chi-square test. Results: Duration of post-operative analgesia was prolonged in Groups BM1 and BM0.5 (665.13 ± 97.874, 475.10 ± 53.294 min respectively as compared to Group B (272.03 ± 40.404 min: P = 0.00. The onset times of sensory and motor block were shorter in Group BM1 (5.17 ± 2.2 minas compared to Groups BM0.5 and B (8.9 ± 2.3 and 17.7 ± 5.1 min: P = 0.00 respectively. Sensory and motor block durations were prolonged in Group BM1 as compared to BM0.5 and B (P = 0.00. Conclusions: MgSO4 as adjuvant in brachial plexus block increases the duration of post-operative analgesia. MgSO4 in the dose of 250mg has greater efficacy as compared to 125 mg.

Radioprotective effects of dextran sulphate in mice

International Nuclear Information System (INIS)

Vacek, A.; Bartonickova, A.; Rotkovska, D.; Palyga, G.F.; Zhukova, N.A.

1981-01-01

Influence of a single i.p. injection of dextran sulphate on radiosensitivity of mice was investigated. The administration of dextran sulphate 24, 48 and 72 hours prior to irradiation increased formation of endogenous colonies of the hemopoietic tissue on the surface of the spleen. DRF calculated from an equieffective exposure for 5 colonies was 1.96 when dextran sulphate was administered 24 hours before irradiation, and 2.25 when dextran sulphate was administered 72 hours before irradiation. The radioprotective effects of dextran sulphate were manifested also in the survival of animals exposed to lethal doses of short-termed as well as long-termed gamma radiation. (orig.) [de

Silicon carbide whisker reinforced composites and method for making same

Science.gov (United States)

Wei, G.C.

1984-02-09

The present invention is directed to the fabrication of ceramic composites which possess improved mechanical properties, especially increased fracture toughness. In the formation of these ceramic composites, the single-crystal SiC whiskers are mixed with fine ceramic powders of a ceramic material such as Al/sub 2/O/sub 3/, mullite, or B/sub 4/C. The mixtures which contain a homogeneous dispersion of the SiC whiskers are hot pressed at pressures in a range of about 28 to 70 MPa and temperatures in the range of about 1600 to 1950/sup 0/C with pressing times varying from about 0.75 to 2.5 hours. The resulting ceramic composites show an increase in fracture toughness of up to about 9 MPa.m/sup 1/2/ which represents as much as a two-fold increase over that of the matrix material.

Extraction and characterization of cellulose nano whiskers from balsa wood

International Nuclear Information System (INIS)

Morelli, Carolina L.; Bretas, Rosario E.S.; Marconcini, Jose M.; Pereira, Fabiano V.; Branciforti, Marcia C.

2011-01-01

In this study cellulose nano whiskers were obtained from balsa wood. For this purpose, fibers of balsa wood were subjected to hydrolysis reactions for lignin and hemi cellulose digestion and acquisition of nano-scale cellulose. Cellulose nano crystals obtained had medium length and thickness of 176 nm and 7 nm respectively. Infrared spectroscopy and x-ray diffraction showed that the process used for extracting nano whiskers could digest nearly all the lignin and hemi cellulose from the balsa fiber and still preserve the aspect ratio and crystallinity, satisfactory enough for future application in polymer nano composites. Thermogravimetry showed that the onset temperature of thermal degradation of cellulose nano crystals (226 degree C) was higher than the temperature of the balsa fiber (215 degree C), allowing its use in molding processes with many polymers from the molten state.(author)

Temperature-dependent transformation from whisker- to nanoparticle-strengthened composite interface in the Al2O3/Ag-based alloy system and mechanical properties of the joints

International Nuclear Information System (INIS)

Wang, Yifeng; Cao, Jian; Wang, Zhijie; Chen, Zhe; Song, Xiaoguo; Feng, Jicai

2015-01-01

Al 4 B 2 O 9 -whisker-coated Al 2 O 3 ceramics were bonded by AgCu–4.5 wt.%Ti alloy in vacuum. The microstructure of the whisker-coated Al 2 O 3 joints was investigated by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. A continuous (Cu,Al) 3 Ti 3 O layer formed against the alloy at lower bonding temperatures, and a complex transition zone bordering the whiskers was observed, which consisted of Ag nanoparticles, titanium oxides, TiB 2 , (Cu,Al) 3 Ti 3 O nanoparticles and possible Ag 3 Al. As the bonding temperature increased, the Al 2 O 3 /AgCuTi interface was found to transform from whisker- to nanoparticle-strengthened composite region. Bend test results revealed that both the whiskers grown on Al 2 O 3 and the dispersive nanoscale products in the alloy played positive roles in improving the joint properties. The maximum bend strength of the whisker-coated Al 2 O 3 joints was 313 MPa at the bonding temperature of 820 °C. - Highlights: • Al 4 B 2 O 9 -whisker-coated Al 2 O 3 ceramics were bonded by AgCu–4.5 wt.%Ti alloy in vacuum. • Microstructures of whisker-coated Al 2 O 3 joints were investigated in detail. • Both whiskers and the dispersive nanoscale products can improve the joint properties. • The maximum bend strength of the whisker-coated Al 2 O 3 joints was 313 MPa.

Sulphate solubility and sulphate diffusion in oxide glasses: implications for the containment of sulphate-bearing nuclear wastes; Solubilite et cinetiques de diffusion des sulfates dans differents verres d'oxydes: application au conditionnement des dechets nucleaires sulfates

Energy Technology Data Exchange (ETDEWEB)

Lenoir, M.

2009-09-15

The thesis deals with sulphate solubility and sulphate diffusion in oxide glasses, in order to control sulphate incorporation and sulphate volatilization in nuclear waste glasses. It was conducted on simplified compositions, in the SiO{sub 2}-B{sub 2}O{sub 3}-R{sub 2}O (R = Li, Na, K, Cs), SiO{sub 2}-B{sub 2}O{sub 3}-BaO and V{sub 2}O{sub 5}-B{sub 2}O{sub 3}-BaO systems. These compositions allowed us to study the influence of the nature of network-modifying ions (Li{sup +}, Na{sup +}, K{sup +}, Cs{sup +} or Ba{sup 2+}) and also of former elements (Si, B, V), on structure and properties of glasses. Sulphate volatility is studied in sodium borosilicate melts using an innovative technique of sulphate quantitation with Raman spectroscopy. This technique is useful to obtain kinetic curves of sulphate volatilization. The establishment of a model to fit these curves leads to the determination of diffusion coefficients of sulphate. These diffusion coefficients can thus be compared to diffusion coefficients of other species, determined by other techniques and presented in the literature. They are also linked to diffusion coefficients in relation with the viscosity of the melts. Concerning sulphate solubility in glasses, it depends on glass composition and on the nature of sulphate incorporated. Sulphate incorporation in alkali borosilicate glasses leads to the formation of a sulphate layer floating on top of the melt. Sulphate incorporation in barium borosilicate and boro-vanadate glasses leads to the crystallization of sulphate species inside the vitreous matrix. Moreover, sulphate solubility is higher in these glasses than in alkali borosilicates. Finally, exchanges between cations present in glasses and cations present in the sulphate phase are also studied. (author)

Electrochemical preparation of Al–Sm intermetallic compound whisker in LiCl–KCl Eutectic Melts

International Nuclear Information System (INIS)

Ji, De−Bin; Yan, Yong−De; Zhang, Mi−Lin; Li, Xing; Jing, Xiao−Yan; Han, Wei; Xue, Yun; Zhang, Zhi−Jian; Hartmann, Thomas

2015-01-01

Highlights: • The reduction process of Sm(III) was investigated in LiCl–KCl melt on an aluminum electrode at 773 K. • Al–Sm alloy with different phase structure (Al 2 Sm and Al 3 Sm) was prepared by potentiostatic electrolysis on an aluminum electrode with the change of electrolytic potentials and time in LiCl–KCl–SmCl 3 melts. • Al − Sm alloy containing whiskers (Al 4 Sm) was obtained by potentiostatic electrolysis (−2.10 V) on an aluminum electrode for 7 hours with the change of electrolytic temperature and cooling rate in LiCl–KCl–SmCl 3 (16.5 wt. %) melts. The results from micro–hardness test and potentiodynamic polarization test show the micro hardness and corrosion property are remarkably improved with the help of Al–Sm intermetallic compound whiskers. - Abstract: This work presents the electrochemical study of Sm(III) on an aluminum electrode in LiCl–KCl melts at 773 K by different electrochemical methods. Three electrochemical signals in cyclic voltammetry, square wave voltammetry, open circuit chronopotentiometry, and cathode polarization curve are attributed to different kinds of Al–Sm intermetallic compounds, Al 2 Sm, Al 3 Sm, and Al 4 Sm, respectively. Al–Sm alloy with different phase structure (Al 2 Sm and Al 3 Sm) could be obtained by the potentiostatic electrolysis with the change of electrolytic potentials and time. Al–Sm alloy containing whiskers (Al 4 Sm) was obtained by potentiostatic electrolysis (−2.10 V) on an aluminum electrode for 7 hours with the change of electrolytic temperature and cooling rate in LiCl–KCl–SmCl 3 (16.5 wt. %) melts. The XRD and SEM&EDS were employed to investigate the phase composition and microstructure of Al–Sm alloy. SEM analysis shows that lots of needle−like precipitates formed in Al–Sm alloy, and their ratios of length to diameter are found to be greater than 10 to 1. The TEM and electron diffraction pattern were performed to investigate the crystal structure of the

Tin Whisker Electrical Short Circuit Characteristics. Part 2

Science.gov (United States)

Courey, Karim J.; Asfour, Shihab S.; Onar, Arzu; Bayliss, Jon A.; Ludwig, Lawrence L.; Wright, Maria C.

2009-01-01

Existing risk simulations make the assumption that when a free tin whisker has bridged two adjacent exposed electrical conductors, the result is an electrical short circuit. This conservative assumption is made because shorting is a random event that has an unknown probability associated with it. Note however that due to contact resistance electrical shorts may not occur at lower voltage levels. In our first article we developed an empirical probability model for tin whisker shorting. In this paper, we develop a more comprehensive empirical model using a refined experiment with a larger sample size, in which we studied the effect of varying voltage on the breakdown of the contact resistance which leads to a short circuit. From the resulting data we estimated the probability distribution of an electrical short, as a function of voltage. In addition, the unexpected polycrystalline structure seen in the focused ion beam (FIB) cross section in the first experiment was confirmed in this experiment using transmission electron microscopy (TEM). The FIB was also used to cross section two card guides to facilitate the measurement of the grain size of each card guide's tin plating to determine its finish.

Fabrication and characterization of intrinsic Josephson junctions in RE-123 whiskers

International Nuclear Information System (INIS)

Okutsu, T.; Ueda, S.; Ishii, S.; Nagasawa, M.; Takano, Y.

2008-01-01

The series of REBa 2 Cu 3 O 7-δ RE-123; RE = Y, Eu, Gd, Dy, Ho, Er, Tm, and Lu) single-crystal whiskers have been successfully grown using the Te- or Sb-doping method. Intrinsic Josephson junctions (IJJs) were fabricated from the whiskers using a focused ion beam (FIB). As-grown IJJs with T c > 70 K showed a Josephson current but no multi-branches in the current-voltage (I-V) characteristics. Under-doped specimens were obtained by a post-annealing process. As-grown IJJs with lower T c and all the specimens of the post-annealed IJJs showed clear multi-branched structure. The post-annealing reduced the critical temperature (T c ) and the critical current density (J c ) of the IJJs, and increased the anisotropic parameter γ

Fabricação de compósitos com matriz de alumina reforçada com whiskers de mulita

OpenAIRE

Salles, Mário César Fernandez de

2008-01-01

Neste trabalho foram fabricados compósitos cerâmicos utilizando alumina como matriz e whiskers de mulita como reforço. As composições de whiskers foram 10, 20, 30 e 40% em peso. Os whiskers de mulita utilizados como matérias-primas foram obtidos através do tratamento térmico do mineral topázio incolor no Laboratório de Tratamento Térmico de Materiais do ICEB/UFOP. A alumina de elevada pureza foi fornecida pela empresa Alfa Apesar. As matérias primas, após serem pesadas, foram submetidas a um ...

Effect of heating parameters on sintering behaviors and properties of mullite whisker frameworks

Science.gov (United States)

Zhang, Y. M.; Zeng, D. J.; Wang, B.; Yang, J. F.

2018-04-01

Mullite whisker frameworks were fabricated by vapor-solid reaction with SiO2, Al2O3 and AlF3 powders as the whisker forming agent at high temperatures. The effects of heating temperature and soaking time on the weight loss, liner shrinkage, porosity, microstructure and compressive strength were investigated. The results showed that with the increasing of the sintering temperature and soaking time, the weight loss and liner shrinkage of the samples increased and the porosities decreased due to the accelerated vapor-solid reaction, resulting in strong bonding and grain growth of the mullite frameworks. The compressive strength of the samples increased with increasing the sintering temperature from 1500 to 1650 °C, and decreased with the soaking time extended to more than 5 h for 1500 °C and 2 h for 1650 °C. A maximum compressive strength of 142 MPa at a porosity of 62.3% was obtained for the mullite whisker framework heated at 1500 °C for 5 h. The enhanced strength was attributed to the strong bonding strength and fine mullite grains resulting from a relative lower heating temperature and a modest soaking time.

An Empirical Model for Estimating the Probability of Electrical Short Circuits from Tin Whiskers-Part I

Science.gov (United States)

Courey, Karim; Wright, Clara; Asfour, Shihab; Bayliss, Jon; Ludwig, Larry

2008-01-01

Existing risk simulations make the assumption that when a free tin whisker has bridged two adjacent exposed electrical conductors, the result is an electrical short circuit. This conservative assumption is made because shorting is a random event that has a currently unknown probability associated with it. Due to contact resistance, electrical shorts may not occur at lower voltage levels. In this experiment, we study the effect of varying voltage on the breakdown of the contact resistance which leads to a short circuit. From this data, we can estimate the probability of an electrical short, as a function of voltage, given that a free tin whisker has bridged two adjacent exposed electrical conductors. In addition, three tin whiskers grown from the same Space Shuttle Orbiter card guide used in the aforementioned experiment were cross sectioned and studied using a focused ion beam (FIB).

Fabrication and properties of aluminum silicate fibrous materials with in situ synthesized K2Ti6O13 whiskers

Science.gov (United States)

Liu, Hao; Wei, Nan; Wang, Zhou-fu; Wang, Xi-tang; Ma, Yan

2017-11-01

To improve their mechanical and thermal insulation properties, aluminum silicate fibrous materials with in situ synthesized K2Ti6O13 whiskers were prepared by firing a mixture of short aluminum silicate fibers and gel powders obtained from a sol-gel process. During the preparation process, the fiber surface was coated with K2Ti6O13 whiskers after the fibers were subjected to a heat treatment carried out at various temperatures. The effects of process parameters on the microstructure, compressive strength, and thermal conductivity were analyzed systematically. The results show that higher treatment temperatures and longer treatment durations promoted the development of K2Ti6O13 whiskers on the surface of aluminum silicate fibers; in addition, the intersection structure between whiskers modulated the morphology and volume of the multi-aperture structure among fibers, substantially increasing the fibers' compressive strength and reducing their heat conduction and convective heat transfer at high temperatures.

Design of the Intravenous Magnesium Efficacy in Acute Stroke (IMAGES trial [ISRCTN19943732

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Lees Kennedy

2000-12-01

Full Text Available Abstract The Intravenous Magnesium Efficacy in Acute Stroke (IMAGES trial is a multicentre,randomised, placebo-controlled trial of magnesium sulphate (MgSO4 funded by the UK Medical Research Council. When complete, it will be the largest single neuroprotective study undertaken to date. Conscious patients presenting within 12 h of acute stroke with limb weakness are eligible. The primary outcome measure is combined death and disability as measured using the Barthel Index at 90-day follow up. By randomizing 2700 patients, the study will have 84% power to detect a 5.5% absolute reduction in the primary end-point. By April 2000, 86 centres were participating, with representation in Canada, USA, Europe, South America, Singapore and Australia. So far, 1206 patients have been randomised, of whom 37% were treated within 6 h. Overall 3-month mortality was 20% and the primary outcome event rate was 43%. The study is ongoing and centres worldwide are encouraged to participate.

Formation of magnesium silicate hydrate (M-S-H) cement pastes using sodium hexametaphosphate

Energy Technology Data Exchange (ETDEWEB)

Zhang, Tingting [Faculty of Infrastructure Engineering, Dalian University of Technology, Dalian 116024 (China); Department of Materials, Centre for Advanced Structural Ceramics, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom); Department of Civil and Environmental Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom); Vandeperre, Luc J. [Department of Materials, Centre for Advanced Structural Ceramics, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom); Cheeseman, Christopher R., E-mail: c.cheeseman@imperial.ac.uk [Department of Civil and Environmental Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom)

2014-11-15

Magnesium silicate hydrate (M-S-H) gel is formed by the reaction of brucite with amorphous silica during sulphate attack in concrete and M-S-H is therefore regarded as having limited cementing properties. The aim of this work was to form M-S-H pastes, characterise the hydration reactions and assess the resulting properties. It is shown that M-S-H pastes can be prepared by reacting magnesium oxide (MgO) and silica fume (SF) at low water to solid ratio using sodium hexametaphosphate (NaHMP) as a dispersant. Characterisation of the hydration reactions by x-ray diffraction and thermogravimetric analysis shows that brucite and M-S-H gel are formed and that for samples containing 60 wt.% SF and 40 wt.% MgO all of the brucites react with SF to form M-S-H gel. These M-S-H cement pastes were found to have compressive strengths in excess of 70 MPa.

Conversion of wood flour/SiO2/phenolic composite to porous SiC ceramic containing SiC whiskers

Directory of Open Access Journals (Sweden)

Li Zhong

2013-01-01

Full Text Available A novel wood flour/SiO2/phenolic composite was chosen to be converted into porous SiC ceramic containing SiC whiskers via carbothermal reduction. At 1550°C the composite is converted into porous SiC ceramic with pore diameters of 10~40μm, and consisting of β-SiC located at the position of former wood cell walls. β-SiC wire-like whiskers of less than 50 nm in diameter and several tens to over 100 μm in length form within the pores. The surface of the resulting ceramic is coated with β-SiC necklace-like whiskers with diameters of 1~2μm.

Removal heavy metals and sulphate from waste waters by sulphate-reducing bacteria

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Kušnierová Mária

2000-09-01

Full Text Available This article is devoted to the process of bacterial sulphate reduction, which is used to removal of heavy metals and sulphate ions from waste waters.The life of animals and plants depends on the existence of microscopic organisms – microorganisms (MO, which play an important role in cycle changes of biogenic elements on the earth. The sulphur cycle in the nature is considered as one of the oldest and most significant biological systems (Fig. 1. The sulphate-reducing bacteria (SRB miss the assimilatory part of the cycle and produce sulphides. The microbial population of this dissimilatory part is called “sulfuretum”. The SRB can be found in anaerobic mud and sediments of freshwater, thermal or non-thermal sulphur springs, mining waters from sulphide deposits, oil deposits, sea and ocean beds, and in the gastrointestinal tract of man and animals. The SRB represent a group of chemoorganotrophic, strictly anaerobic and gramnegative bacteria, which exhibit a great morphological and physiological diversity. Despite of their considerable morphological variety, they have one property in common, which is the ability to utilise preferentially sulphates (occasionally sulphites, thiosulphates, tetrathionates as electron acceptors, which are reduced to sulphides, during anaerobic respiration. The electron donors in these processes are simple organic compounds as lactate, malate, etc.,(heterotrophically reduction or gaseous hydrogen (autotrophically reduction. SRB can produce a considerable amount of hydrogen sulphide, which reacts easily in aqueous solution with the cations of heavy metals, forming metal sulphides that have low solubility. The bacterial sulphate reduction can be used for the treatment of acid mine drainage waters, which is considered to be the major problem associated with mining activities.In order to remove heavy metals from waste waters, e.g., from galvanizing plants, mine waters (Smolnik, Šobov locality and metallurgic plants (works

Crystalline instability of Bi-2212 superconducting whiskers near room temperature

International Nuclear Information System (INIS)

Cagliero, Stefano; Khan, Mohammad Mizanur Rahman; Agostino, Angelo; Truccato, Marco; Orsini, Francesco; Marinone, Massimo; Poletti, Giulio; Lascialfari, Alessandro

2009-01-01

We report new evidences for the thermodynamic instability of whisker crystals in the Bi-Sr-Ca-Cu-O (BSCCO) system. Annealing treatments at 90 C have been performed on two sets of samples, which were monitored by means of X-rays diffraction (XRD) and atomic force microscopy (AFM) measurements, respectively. Two main crystalline domains of Bi 2 Sr 2 CuCa 2 O 8+x (Bi-2212) were identified in the samples by the XRD data, which underwent an evident crystalline segregation after about 60 hours. Very fast dynamics of the surface modifications was also described by the AFM monitoring. Two typologies of surface structures formed after about 3 annealing hours: continuous arrays of dome shaped bodies were observed along the edges of the whiskers, while in the central regions a dense texture of flat bodies was found. These modifications are described in terms of the formation of simple oxide clusters involving a degradation of the internal layers. (orig.)

Crystalline instability of Bi-2212 superconducting whiskers near room temperature

Energy Technology Data Exchange (ETDEWEB)

Cagliero, Stefano; Khan, Mohammad Mizanur Rahman [Torino Universita, ' NIS' Centre of Excellence, Dip. Chimica Generale e Chimica Organica, and CNISM UdR, Turin (Italy); Torino Universita, ' NIS' Centre of Excellence, Dip. Fisica Sperimentale, and CNISM UdR, Turin (Italy); Agostino, Angelo [Torino Universita, ' NIS' Centre of Excellence, Dip. Chimica Generale e Chimica Organica, and CNISM UdR, Turin (Italy); Truccato, Marco [Torino Universita, ' NIS' Centre of Excellence, Dip. Fisica Sperimentale, and CNISM UdR, Turin (Italy); Orsini, Francesco; Marinone, Massimo; Poletti, Giulio [Universita degli Studi di Milano, Istituto di Fisiologia Generale e Chimica Biologica, Milan (Italy); CNR-INFM-S3 NRC, Modena (Italy); Lascialfari, Alessandro [Universita degli Studi di Milano, Istituto di Fisiologia Generale e Chimica Biologica, Milan (Italy); CNR-INFM-S3 NRC, Modena (Italy); Universita degli Studi di Pavia, INFM-CNR c/o Dipartimento di Fisica A. Volta, Pavia (Italy)

2009-05-15

We report new evidences for the thermodynamic instability of whisker crystals in the Bi-Sr-Ca-Cu-O (BSCCO) system. Annealing treatments at 90 C have been performed on two sets of samples, which were monitored by means of X-rays diffraction (XRD) and atomic force microscopy (AFM) measurements, respectively. Two main crystalline domains of Bi{sub 2}Sr{sub 2}CuCa{sub 2}O{sub 8+x} (Bi-2212) were identified in the samples by the XRD data, which underwent an evident crystalline segregation after about 60 hours. Very fast dynamics of the surface modifications was also described by the AFM monitoring. Two typologies of surface structures formed after about 3 annealing hours: continuous arrays of dome shaped bodies were observed along the edges of the whiskers, while in the central regions a dense texture of flat bodies was found. These modifications are described in terms of the formation of simple oxide clusters involving a degradation of the internal layers. (orig.)

Oxide films on magnesium and magnesium alloys

International Nuclear Information System (INIS)

Shih, T.-S.; Liu, J.-B.; Wei, P.-S.

2007-01-01

Magnesium alloys are very active and readily ignite during heating and melting. In this study, we discuss the combustion of magnesium and magnesium alloys and propose prospective anti-ignition mechanisms for magnesium alloys during the heating process. When magnesium and magnesium alloys were heated in air, the sample surfaces produced layers of thermally formed oxides. These thermally formed oxides played an important role in affecting the combustion of the magnesium and magnesium alloys. When magnesium was heated in air, brucite that formed in the early stage was then transformed into periclase by dehydroxylation. By extending the heating time, more periclase formed and increased in thickness which was associated with microcracks formation. When magnesium was heated in a protective atmosphere (SF 6 ), a film of MgF 2 formed at the interface between the oxide layer and the Mg substrate. This film generated an anti-ignition behavior which protected the substrate from oxidation. When solution-treated AZ80 alloy was heated, spinel developed at the interface between the thermally formed oxide layer and the Mg substrate, improving the anti-ignition properties of the substrate. In addition, we also explain the effects of beryllium in an AZB91 alloy on the ignition-proofing behavior

Removal of Sulphate and Manganese on Synthetic Wastewater in Sulphate Reducing Bioreactor Using Indonesian Natural Zeolite

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Endah Retnaningrum

2017-07-01

Full Text Available The present research was conducted to investigate sulphate and manganese removal from synthetic wastewater. The continuous laboratory scale of down-flow fluidized-bed reactor (DFBR using sulphate reducing bacteria (SRB consortium and Indonesian natural zeolite as a bacterial support material was designed. At 9 days operation, maximum sulphate and manganese removal was observed to be 23% and 15.4%, respectively. The pH values were also changed to neutral. The population of SRB increased which effect on the raising of their activity for removing sulphate and manganese. Using the scanning electronic microscopy (SEM, it was observed that natural zeolite possesses excellent physical characteristics as a bacterial support material in DFBR. The imaging SEM result of SRB consortium on zeolite surface clearly showed the developed SRB biofilm on that particle. Analysis result of EDX confirmed that manganese was precipitated as manganese–sulfides.

Demonstration of immunogenic keratan sulphate in commercial chondroitin 6-sulphate from shark cartilage. Implications for ELISA assays

DEFF Research Database (Denmark)

Møller, H J; Møller-Pedersen, T; Damsgaard, T E

1995-01-01

The prototype monoclonal keratan sulphate (KS) antibody 5D4 that is widely used for detection of KS in tissues and biological fluids reacts strongly with commercial low grade shark cartilage chondroitin 6-sulphate. Characterization of the immunogenic material by chondroitinase ABC digestion, ELISA...... cartilage chondroitin 6-sulphate is an easy accessible source of immunogenic KS that can be used as a reference standard and as coating antigen in KS-ELISAs. The concentration of immunogenic KS in synovial fluid measured with an ELISA based solely on reagents of shark cartilage chondroitin 6-sulphate...... correlated well (r = 0.90) with the concentrations obtained with a traditional KS-ELISA that uses purified aggrecan as standard and coating antigen, and KS in both serum and synovial fluid could be measured with sufficient linearity....

CO2 fixation using magnesium silicate minerals part 1: Process description and performance

International Nuclear Information System (INIS)

Fagerlund, Johan; Nduagu, Experience; Romão, Inês; Zevenhoven, Ron

2012-01-01

This paper describes a staged carbonation process for magnesium silicate mineral carbonation. This carbon dioxide capture and storage (CCS) alternative involves the production of magnesium hydroxide, followed by its carbonation in a pressurised fluidised bed (PFB) reactor. The goal is to utilise the heat of the carbonation reaction to drive the Mg(OH) 2 production step. The results show that Mg(OH) 2 can be produced successfully (up to 78% Mg extraction extent achieved so far) and efficiently from different serpentinite minerals from locations worldwide (Finland, Lithuania, Australia, Portugal…). From the extraction step, ammonium sulphate is recovered while iron oxides (from the mineral) are obtained as by-products. The carbonation step, while still being developed, resulted in >50%-wt conversion in 10 min (500 °C, 20 bar) for > 300 μm serpentinite-derived Mg(OH) 2 particles. Thus the reaction rate achieved so far is much faster than what is currently being considered fast in the field of mineral carbonation. -- Highlights: ► Magnesium silicate-based rock can sequester CO 2 as stable magnesium carbonate. ► Abundance of rock material offers a larger capacity than other CCS methods. ► Mg(OH) 2 production is followed by its carbonation in a pressurised fluidised bed. ► Carbonation reaches >50% in around 10 min for >0.3 mm particles. ► Mg(OH) 2 produced from different rock material show the same performance.

Electroluminescence of Zn{sub 2}GeO{sub 4}:Mn through SiC whisker electric field enhancement

Energy Technology Data Exchange (ETDEWEB)

Wagstaff, Brandon, E-mail: wagstabj@mcmaster.ca [McMaster University, Department of Engineering Physics, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4L8 (Canada); Kitai, Adrian, E-mail: kitaia@mcmaster.ca [McMaster University, Department of Engineering Physics, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4L8 (Canada); McMaster University, Department of Materials Science and Engineering, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4L8 (Canada)

2015-11-15

Alternating current (AC) electroluminescence of thin film oxide phosphors is well known. However in this work electroluminescence of bulk oxide powder phosphors is achieved. A new type of AC Electroluminescent (ACEL) device has been created and developed by integrating SiC whiskers into a phosphor matrix composed of manganese-activated zinc germanate (Zn{sub 2}GeO{sub 4}:Mn{sup 2+}). The conductive SiC whiskers enhance the average electric field in specific regions of the phosphor such that localized breakdown of the phosphor occurs, thus emitting green light. This field enhancement allows light emission to occur in thick film oxide powder phosphors and is notably the first time that bright and reasonably efficient electroluminescence of zinc germanate has been observed without using expensive thin film deposition techniques. Light emission has been achieved in thick pressed pellets using surface-deposited electrodes and the brightness-voltage characteristics of light emission are shown to be consistent with field emission of carriers from the embedded whiskers. - Highlights: • A new electroluminescent phosphor, Zn{sub 2}GeO{sub 4}Mn{sup 2+}+SiC whiskers, is proposed. • A procedure is described to fabricate a solid sample of this composite material. • Under an AC voltage, green light is emitted only in samples containing the SiC whiskers. • A brightness of 25 Cd/m{sup 2} and efficiency of 0.25 Lm/W is observed 9.6×10{sup 6} V/m. • This is notably the first time that ACEL has been observed in bulk Zn{sub 2}GeO{sub 4}Mn{sup 2+}.

Demonstration of immunogenic keratan sulphate in commercial chondroitin 6-sulphate from shark cartilage. Implications for ELISA assays

DEFF Research Database (Denmark)

Møller, H J; Møller-Pedersen, T; Damsgaard, T E

1995-01-01

The prototype monoclonal keratan sulphate (KS) antibody 5D4 that is widely used for detection of KS in tissues and biological fluids reacts strongly with commercial low grade shark cartilage chondroitin 6-sulphate. Characterization of the immunogenic material by chondroitinase ABC digestion, ELISA...... inhibition studies, immunoblotting and HPLC analyses confirmed the presence of substantial amounts of KS, probably as a large proteoglycan (> 120 kDa). Commercial and heterogenic glycosaminoglycan preparations therefore must be used with great caution in immunological analyses. On the other hand the shark...... cartilage chondroitin 6-sulphate is an easy accessible source of immunogenic KS that can be used as a reference standard and as coating antigen in KS-ELISAs. The concentration of immunogenic KS in synovial fluid measured with an ELISA based solely on reagents of shark cartilage chondroitin 6-sulphate...

Extraction of sulphates by long chain amines

International Nuclear Information System (INIS)

Boirie, Ch.

1959-05-01

The extraction of sulphuric acid by long chain amines in organic solution has been studied with a view to determining the value of the stability constants of the amine sulphates and bi-sulphates formed. We have concentrated chiefly on uranium sulphate and thorium sulphate. The formulae of the complexes extractable with amines have been established, as well as the corresponding dissociation constants. We have observed that for uranium sulphate the formula of the complex depends only on the nature of the amine, whereas for thorium this formula varies with the amine structure. From the formulae determined and the value of the constants calculated, we have been able to establish the best conditions for uranium and thorium extraction and also for a separation of these two elements. Finally we propose an application of this study to the determination of uranium in ores, where the separation of uranium by this method is particularly easy and complete. (author) [fr

Temperature-dependent transformation from whisker- to nanoparticle-strengthened composite interface in the Al{sub 2}O{sub 3}/Ag-based alloy system and mechanical properties of the joints

Energy Technology Data Exchange (ETDEWEB)

Wang, Yifeng; Cao, Jian, E-mail: cao_jian@hit.edu.cn; Wang, Zhijie; Chen, Zhe; Song, Xiaoguo; Feng, Jicai

2015-11-15

Al{sub 4}B{sub 2}O{sub 9}-whisker-coated Al{sub 2}O{sub 3} ceramics were bonded by AgCu–4.5 wt.%Ti alloy in vacuum. The microstructure of the whisker-coated Al{sub 2}O{sub 3} joints was investigated by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. A continuous (Cu,Al){sub 3}Ti{sub 3}O layer formed against the alloy at lower bonding temperatures, and a complex transition zone bordering the whiskers was observed, which consisted of Ag nanoparticles, titanium oxides, TiB{sub 2}, (Cu,Al){sub 3}Ti{sub 3}O nanoparticles and possible Ag{sub 3}Al. As the bonding temperature increased, the Al{sub 2}O{sub 3}/AgCuTi interface was found to transform from whisker- to nanoparticle-strengthened composite region. Bend test results revealed that both the whiskers grown on Al{sub 2}O{sub 3} and the dispersive nanoscale products in the alloy played positive roles in improving the joint properties. The maximum bend strength of the whisker-coated Al{sub 2}O{sub 3} joints was 313 MPa at the bonding temperature of 820 °C. - Highlights: • Al{sub 4}B{sub 2}O{sub 9}-whisker-coated Al{sub 2}O{sub 3} ceramics were bonded by AgCu–4.5 wt.%Ti alloy in vacuum. • Microstructures of whisker-coated Al{sub 2}O{sub 3} joints were investigated in detail. • Both whiskers and the dispersive nanoscale products can improve the joint properties. • The maximum bend strength of the whisker-coated Al{sub 2}O{sub 3} joints was 313 MPa.

Sulphate deposition by precipitation into Lake Ontario

Energy Technology Data Exchange (ETDEWEB)

Shaw, R W; Whelpdale, D M

1973-01-01

Measurements of sulphate concentration in precipitation from individual snow storms of several hours duration in the western Lake Ontario region indicate that approximately 9-66 mg/M/sub 2/ of SO/sub 4//sup 2 -/ is being deposited into the lake per storm. This amount is up to several times more than daily average values over long periods found by other workers. Using a mean sulphate concentration of 4 mg/l and an annual accumulation of precipitation of 760 mm, the yearly sulphate deposition by precipitation is about 0.1% of the total mass of sulphate in the lake; however, more significantly, it is of the same order of magnitude as that discharged directly into the lake by industry.

Mortar and concrete based on calcium sulphate binders

NARCIS (Netherlands)

Bakker, J.J.F.; Brouwers, H.J.H.; Fischer, H.B

2006-01-01

In this study both hemi-hydrate and anhydrite are tested as calcium sulphate binders for structural mortar and concrete. The advantage of using calcium sulphates instead of cement as a binder is the fact that the production of calcium sulphate is more environmental friendly than that of cement. For

Physicochemical and in vitro deposition properties of salbutamol sulphate/ipratropium bromide and salbutamol sulphate/excipient spray dried mixtures for use in dry powder inhalers.

Science.gov (United States)

Corrigan, Deirdre O; Corrigan, Owen I; Healy, Anne Marie

2006-09-28

The physicochemical and aerodynamic properties of spray dried powders of the drug/drug mixture salbutamol sulphate/ipratropium bromide were investigated. The in vitro deposition properties of spray dried salbutamol sulphate and the spray dried drug/excipient mixtures salbutamol sulphate/lactose and salbutamol sulphate/PEG were also determined. Spray drying ipratropium bromide monohydrate resulted in a crystalline material from both aqueous and ethanolic solution. The product spray dried from aqueous solution consisted mainly of ipratropium bromide anhydrous. There was evidence of the presence of another polymorphic form of ipratropium bromide. When spray dried from ethanolic solution the physicochemical characterisation suggested the presence of an ipratropium bromide solvate with some anhydrous ipratropium bromide. Co-spray drying salbutamol sulphate with ipratropium bromide resulted in amorphous composites, regardless of solvent used. Particles were spherical and of a size suitable for inhalation. Twin impinger studies showed an increase in the fine particle fraction (FPF) of spray dried salbutamol sulphate compared to micronised salbutamol sulphate. Co-spray dried salbutamol sulphate:ipratropium bromide 10:1 and 5:1 systems also showed an increase in FPF compared to micronised salbutamol sulphate. Most co-spray dried salbutamol sulphate/excipient systems investigated demonstrated FPFs greater than that of micronised drug alone. The exceptions to this were systems containing PEG 4000 20% or PEG 20,000 40% both of which had FPFs not significantly different from micronised salbutamol sulphate. These two systems were crystalline unlike most of the other spray dried composites examined which were amorphous in nature.

Sulphate reduction and vertical distribution of sulphate-reducing bacteria quantified by rRNA slot-blot hybridization in a coastal marine sediment

DEFF Research Database (Denmark)

Sahm, K.; MacGregor, BJ; Jørgensen, BB

1999-01-01

In the past, enumeration of sulphate-reducing bacteria (SRB) by cultivation-based methods generally contradicted measurements of sulphate reduction, suggesting unrealistically high respiration rates per cell. Here, we report evidence that quantification of SRB rRNA by slot-blot hybridization......, directly above the sulphate reduction maximum. Cell numbers calculated by converting the relative contribution of SRB rRNA to the percentage of DAPI-stained cells indicated a population size for SRB of 2.4-6.1 x 10(8) cells cm(-3) wet sediment. Cellular sulphate reduction rates calculated on the basis...

Sr{sub 1.98}Eu{sub 0.02}SiO{sub 4} luminescence whisker based on vapor-phase deposition: Facile synthesis, uniform morphology and enhanced luminescence properties

Energy Technology Data Exchange (ETDEWEB)

Xu, Jian, E-mail: xujian@stu.xmu.edu.cn [Department of Materials Science and Engineering, Xiamen University, Xiamen 361005 (China); Hassan, Dhia A. [Department of Materials Science and Engineering, Xiamen University, Xiamen 361005 (China); Department of Chemistry, College of Education for Pure Science, University of Basrah, 61004 (Iraq); Zeng, Renjie; Peng, Dongliang [Department of Materials Science and Engineering, Xiamen University, Xiamen 361005 (China); Fujian Key Lab of Advanced Special Material, Xiamen University, Xiamen 361005 (China); Key Laboratory of High Performance Ceramic Fibers, Ministry of Education, Xiamen 361005 (China)

2015-11-15

Highlights: • For the first time, it is possible to obtain Sr{sub 1.98}Eu{sub 0.02}SiO{sub 4} whisker. • The whiskers are smooth and uniform with L/D ratio over 50. • Durability and thermal stability of the whisker are enhanced. - Abstract: A high performance strontium silicate phosphor has been successfully synthesized though a facile vapor-phase deposition method. The product consists of single crystal whiskers which are smooth and uniform, and with a sectional equivalent diameter of around 5 μm; the aspect ratio is over 50 and no agglomeration can be observed. X-ray diffraction result confirmed that the crystal structure of the whisker was α’-Sr{sub 2}SiO{sub 4}. The exact chemical composition was Sr{sub 1.98}Eu{sub 0.02}SiO{sub 4} which was analyzed by energy dispersive spectrometer and inductively coupled plasma-mass spectrometer. The whisker shows broad green emission with peak at 523 nm ranging from 470 to 600 nm (excited at 370 nm). Compared with traditional Sr{sub 2}SiO{sub 4}:Eu phosphor, durability (at 85% humidity and 85 °C) and thermal stability of the whisker are obviously improved. Moreover, growth mechanism of the Sr{sub 1.98}Eu{sub 0.02}SiO{sub 4} whiskers is Vapor–Liquid–Solid. On a macro-scale, the product is still powder which makes it suitable for the current packaging process of WLEDs.

Whisker and Hillock formation on Sn, Sn-Cu and Sn-Pb electrodeposits

International Nuclear Information System (INIS)

Boettinger, W.J.; Johnson, C.E.; Bendersky, L.A.; Moon, K.-W.; Williams, M.E.; Stafford, G.R.

2005-01-01

High purity bright Sn, Sn-Cu and Sn-Pb layers, 3, 7 and 16 μm thick were electrodeposited on phosphor bronze cantilever beams in a rotating disk apparatus. Beam deflection measurements within 15 min of plating proved that all electrodeposits had in-plane compressive stress. In several days, the surfaces of the Sn-Cu deposits, which have the highest compressive stress, develop 50 μm contorted hillocks and 200 μm whiskers, pure Sn deposits develop 20 μm compact conical hillocks, and Sn-Pb deposits, which have the lowest compressive stress, remain unchanged. The differences between the initial compressive stresses for each alloy and pure Sn is due to the rapid precipitation of Cu 6 Sn 5 or Pb particles, respectively, within supersaturated Sn grains produced by electrodeposition. Over longer time, analysis of beam deflection measurements indicates that the compressive stress is augmented by the formation of Cu 6 Sn 5 on the bronze/Sn interface, while creep of the electrodeposit tends to decrease the compressive stress. Uniform creep occurs for Sn-Pb because it has an equi-axed grain structure. Localized creep in the form of hillocks and whiskers occurs for Sn and Sn-Cu because both have columnar structures. Compact hillocks form for the Sn deposits because the columnar grain boundaries are mobile. Contorted hillocks and whiskers form for the Sn-Cu deposits because the columnar grain boundary motion is impeded

Magnesium Gluconate

Science.gov (United States)

Magnesium gluconate is used to treat low blood magnesium. Low blood magnesium is caused by gastrointestinal disorders, prolonged vomiting or ... disease, or certain other conditions. Certain drugs lower magnesium levels as well.This medication is sometimes prescribed ...

Irradiation induced creep in whiskers of NaCl

International Nuclear Information System (INIS)

Khan, J.A.A.

1977-09-01

Whiskers of NaCl have been grown and irradiated under flexion by X-rays (approximately 2x10 7 R/h) at room temperature and the residual curvature measured. Complete recovery of the initial form of the whisker within an hour's annealing at 400 0 C proves clearly that the observed deformation (creep) is due to the presence of dislocation loops. The choice of NaCl extremely simplifies the experiment and its interpretation since X-rays create point defects one by one. Moreover, this mode of irradiation, at room temperature, produces a very simple situation: perfect interstitial dislocation loops and immobile point defects which are little influenced by the applied stress. The flexion leads to a stress system which hardly differs from an uniaxial stress. One can study separately the preferential nucleation of dislocation loops and their differential growth by carrying out an irradiation under stress followed by an irradiation without stress and vice versa. It is shown that the induced creep is mostly due to the preferential nucleation of dislocation loops and is little affected by the differential growth of these loops. The nucleation period of the loops is very short: a dose of approximately 10 -5 d.p.a. is largely sufficient for the quasi completion of dislocation loops in a crystal having an impurity concentration of approximately 10 -3 [fr

Magnetic whiskers of p-aminobenzoic acid and their use for preparation of filled and microchannel silicone rubbers

International Nuclear Information System (INIS)

Semenov, V. V.; Loginova, V. V.; Zolotareva, N. V.; Razov, E. N.; Kotomina, V. E.; Kruglov, A. V.

2016-01-01

A thin cobalt layer has been formed on the surface of p-aminobenzoic acid whiskers by chemical vapor deposition (CVD). The metallized crystals have been oriented in liquid polydimethylsiloxane rubber by applying a dc magnetic field. After vulcanization, the filler has been removed by processing in an alcohol solution of trifluoroacetic acid. The cobalt deposition on the surface of the organic compound and the properties of metallized whiskers are investigated by optical microscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM).

Magnetic whiskers of p-aminobenzoic acid and their use for preparation of filled and microchannel silicone rubbers

Energy Technology Data Exchange (ETDEWEB)

Semenov, V. V., E-mail: vvsemenov@iomc.ras.ru; Loginova, V. V.; Zolotareva, N. V. [Russian Academy of Sciences, Razuvaev Institute of Organometallic Chemistry (Russian Federation); Razov, E. N. [Lobachevsky Nizhny Novgorod State University (Russian Federation); Kotomina, V. E.; Kruglov, A. V. [Lobachevsky Nizhny Novgorod State University, Physical‒Technical Research Institute (Russian Federation)

2016-07-15

A thin cobalt layer has been formed on the surface of p-aminobenzoic acid whiskers by chemical vapor deposition (CVD). The metallized crystals have been oriented in liquid polydimethylsiloxane rubber by applying a dc magnetic field. After vulcanization, the filler has been removed by processing in an alcohol solution of trifluoroacetic acid. The cobalt deposition on the surface of the organic compound and the properties of metallized whiskers are investigated by optical microscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM).

Sulphate reduction and vertical distribution of sulphate-reducing bacteria quantified by rRNA slot-blot hybridization in a coastal marine sediment

DEFF Research Database (Denmark)

Sahm, K.; MacGregor, BJ; Jørgensen, BB

1999-01-01

In the past, enumeration of sulphate-reducing bacteria (SRB) by cultivation-based methods generally contradicted measurements of sulphate reduction, suggesting unrealistically high respiration rates per cell. Here, we report evidence that quantification of SRB rRNA by slot-blot hybridization...... between 18% and 25% to the prokaryotic rRNA pool. The dominant SRB were related to complete oxidizing genera (Desulphococcus, Desulphosarcina and Desulphobacterium), while Desulpho-bacter could not be detected. The vertical profile and quantity of rRNA from SRB was compared with sulphate reduction rates......, directly above the sulphate reduction maximum. Cell numbers calculated by converting the relative contribution of SRB rRNA to the percentage of DAPI-stained cells indicated a population size for SRB of 2.4-6.1 x 10(8) cells cm(-3) wet sediment. Cellular sulphate reduction rates calculated on the basis...

Helical patterns of magnetization and magnetic charge density in iron whiskers

Science.gov (United States)

Templeton, Terry L.; Hanham, Scott D.; Arrott, Anthony S.

2018-05-01

Studies with the (1 1 1) axis along the long axis of an iron whisker, 40 years ago, showed two phenomena that have remained unexplained: 1) In low fields, there are six peaks in the ac susceptibility, separated by 0.2 mT; 2) Bitter patterns showed striped domain patterns. Multipole columns of magnetic charge density distort to form helical patterns of the magnetization, accounting for the peaks in the susceptibility from the propagation of edge solitons along the intersections of the six sides of a (1 1 1) whisker. The stripes follow the helices. We report micromagnetic simulations in cylinders with various geometries for the cross-sections from rectangular, to hexagonal, to circular, with wide ranges of sizes and lengths, and different anisotropies, including (0 0 1) whiskers and the hypothetical case of no anisotropy. The helical patterns have been there in previous studies, but overlooked. The surface swirls and body helices are connected, but have their own individual behaviors. The magnetization patterns are more easily understood when viewed observing the scalar divergences of the magnetization as isosurfaces of magnetic charge density. The plus and minus charge densities form columns that interact with unlike charges attracting, but not annihilating as they are paid for by a decrease in exchange energy. Just as they start to form the helix, the columns are multipoles. If one could stretch the columns, the self-energy of the charges in a column would be diminished while making the attractive interactions of the unlike charges larger. The columns elongate by becoming helical. The visualization of 3-D magnetic charge distributions aids in the understanding of magnetization in soft magnetic materials.

Piriform cortical glutamatergic and GABAergic neurons express coordinated plasticity for whisker-induced odor recall.

Science.gov (United States)

Liu, Yahui; Gao, Zilong; Chen, Changfeng; Wen, Bo; Huang, Li; Ge, Rongjing; Zhao, Shidi; Fan, Ruichen; Feng, Jing; Lu, Wei; Wang, Liping; Wang, Jin-Hui

2017-11-10

Neural plasticity occurs in learning and memory. Coordinated plasticity at glutamatergic and GABAergic neurons during memory formation remains elusive, which we investigate in a mouse model of associative learning by cellular imaging and electrophysiology. Paired odor and whisker stimulations lead to whisker-induced olfaction response. In mice that express this cross-modal memory, the neurons in the piriform cortex are recruited to encode newly acquired whisker signal alongside innate odor signal, and their response patterns to these associated signals are different. There are emerged synaptic innervations from barrel cortical neurons to piriform cortical neurons from these mice. These results indicate the recruitment of associative memory cells in the piriform cortex after associative memory. In terms of the structural and functional plasticity at these associative memory cells in the piriform cortex, glutamatergic neurons and synapses are upregulated, GABAergic neurons and synapses are downregulated as well as their mutual innervations are refined in the coordinated manner. Therefore, the associated activations of sensory cortices triggered by their input signals induce the formation of their mutual synapse innervations, the recruitment of associative memory cells and the coordinated plasticity between the GABAergic and glutamatergic neurons, which work for associative memory cells to encode cross-modal associated signals in their integration, associative storage and distinguishable retrieval.

Sulphate rocks as an arena for karst development

Directory of Open Access Journals (Sweden)

Andrejchuk V.

1996-01-01

Full Text Available The rocks in which karst systems develop are most commonly composed of carbonate sulphate and chloride minerals. The sulphate minerals are quite numerous, but only gypsum and anhydrite form extensive masses in sedimentary sequences. Other minerals, which represent sulphates of K, Mg and Na, normally occur as minor beds (0.1-5.0 m, or as inclusions associated with chloride rocks. However some minerals precipitated in salt-generating basins, such as mirabilite and glauberite (typically formed in the Kara-Bogaz-Gol Gulf, salt lakes of Siberia and in China, form sequences up to 5-10 m thick where karst may develop. Due to the very high solubility of Na -sulphates, karst processes and features occurring in these rocks resemble salt karst. Thus, the term sulphate karst, although not strictly correct, is used mainly to indicate karst developed in gypsum and anhydrite.

Sulphate reduction experiment: SURE-1

International Nuclear Information System (INIS)

Pedersen, K.; Arlinger, J.; Bengtsson, A.; Edlund, J.; Eriksson, L.; Hallbeck, L.; Johansson, J.; Paeaejaervi, A.; Rabe, L.

2013-11-01

It was previously concluded that opposing gradients of sulphate and methane, observations of 16S rDNA sequences displaying great similarity to those of anaerobic methane-oxidizing Archaea, and a peak in sulphide concentration in groundwater from a depth of 250-350 m in Olkiluoto, Finland, indicated proper conditions for methane oxidation with sulphate. In the present research (SURE-1), pressure-resistant, gas-tight circulating systems were constructed to enable the investigation of attached and unattached anaerobic microbial populations from a depth of 327 m in Olkiluoto under in situ pressure (2.4 MPa), diversity, dissolved gas, and hydrochemical conditions of groundwater station ONKPVA6. Three parallel flow cell cabinets were configured to allow observation of the influence on microbial metabolic activity of 11 mM methane, 11 mM methane plus 10 mM H 2 , or 2.1 mM O 2 plus 7.9 mM N 2 (i.e., air). The concentrations of these gases and of organic acids and carbon, sulphur chemistry, pH and E h , ATP, numbers of cultivable microorganisms, and total numbers of cells and bacteriophages were subsequently recorded under batch conditions for 105 d. The system containing H 2 and methane displayed microbial reduction of 0.7 mM sulphate to sulphide, while the system containing only methane produced 0.2 mM reduced sulphate. The system containing added air became inhibited and displayed no signs of microbial activity. Added H 2 and methane induced increasing numbers of lysogenic bacteriophages per cell. It appears possible that a microbial anaerobic methane-oxidizing process coupled to acetate formation and sulphate reduction may be ongoing in aquifers at a depth of 250-350 m in Olkiluoto, but clear evidence of such an AOM process was not obtained. (orig.)

Sulphate reduction experiment: SURE-1

Energy Technology Data Exchange (ETDEWEB)

Pedersen, K.; Arlinger, J.; Bengtsson, A.; Edlund, J.; Eriksson, L.; Hallbeck, L.; Johansson, J.; Paeaejaervi, A.; Rabe, L. [Microbial Analytics Sweden AB, Moelnlycke (Sweden)

2013-11-15

It was previously concluded that opposing gradients of sulphate and methane, observations of 16S rDNA sequences displaying great similarity to those of anaerobic methane-oxidizing Archaea, and a peak in sulphide concentration in groundwater from a depth of 250-350 m in Olkiluoto, Finland, indicated proper conditions for methane oxidation with sulphate. In the present research (SURE-1), pressure-resistant, gas-tight circulating systems were constructed to enable the investigation of attached and unattached anaerobic microbial populations from a depth of 327 m in Olkiluoto under in situ pressure (2.4 MPa), diversity, dissolved gas, and hydrochemical conditions of groundwater station ONKPVA6. Three parallel flow cell cabinets were configured to allow observation of the influence on microbial metabolic activity of 11 mM methane, 11 mM methane plus 10 mM H{sub 2}, or 2.1 mM O{sub 2} plus 7.9 mM N{sub 2} (i.e., air). The concentrations of these gases and of organic acids and carbon, sulphur chemistry, pH and E{sub h}, ATP, numbers of cultivable microorganisms, and total numbers of cells and bacteriophages were subsequently recorded under batch conditions for 105 d. The system containing H{sub 2} and methane displayed microbial reduction of 0.7 mM sulphate to sulphide, while the system containing only methane produced 0.2 mM reduced sulphate. The system containing added air became inhibited and displayed no signs of microbial activity. Added H{sub 2} and methane induced increasing numbers of lysogenic bacteriophages per cell. It appears possible that a microbial anaerobic methane-oxidizing process coupled to acetate formation and sulphate reduction may be ongoing in aquifers at a depth of 250-350 m in Olkiluoto, but clear evidence of such an AOM process was not obtained. (orig.)

Isotopic evolution of aqueous sulphate in northern Chile water

International Nuclear Information System (INIS)

Aravena, R.; Suzuki, O.; Fritz, P.; Pena, H.; Rauert, W.

1987-01-01

Full text: The extremely arid condition of northern Chile is the main obstacle to the present and future development of urban centres and economic activities in the region. The existing water resources are scarce. During the last decade, isotope techniques have been applied to investigate aspects such as the origin and residence time of the groundwater, these being extremely important for water development and water management. This paper presents 18 O and 34 S data in aqueous sulphate, as well as 18 O, 2 H, and 3 H from springs, rivers and groundwater samples of the Pampa del Tamarugal and Salar de Llamara basins. The principal aim of this study was to investigate the isotope evolution of the sulphate, the origin of the sulphur, the groundwater flow path, and the possibility of using the 18 O of the sulphate as a tracer for estimation of the residence time of the groundwater. Springs that have their recharge area in the high Altiplano (Salar del Huasco basin) show δ values between +5.0 per mille and +6.0 per mille for the 18 O and +5.0 per mille and +9.0 per mille for the 34 S isotope. Springs from lower altitude, show an isotope content between + 8.6 per mille and + 10.6 per mille for 18 O and +7.4 per mille and + 11.7 per mille for 34 S. The groundwaters in the Pampa aquifers, based on their hydrogen and oxygen isotope composition, are associated with different recharge areas. However, these waters show an isotope range for the sulphate similar to .he one of the springs, and no clear relationships are observed between isotope content, flow path and residence time. This pattern could be related to the poorly defined aquifer systems present in the Pampa. The Llamara groundwaters have a uniform isotope content and are the most enriched in the region (δ 18 O = -6.0 per mille and δ 2 H = -50 per mille). The isotope composition of their sulphate compares well with the Pampa groundwater, indicating a similar sulphate source. The isotope composition of gypsum

Sulphate Removal from Water by Carbon Residue from Biomass Gasification: Effect of Chemical Modification Methods on Sulphate Removal Efficiency

Directory of Open Access Journals (Sweden)

Hanna Runtti

2016-02-01

Full Text Available Sulphate removal from mine water is a problem because traditional chemical precipitation does not remove all sulphates. In addition, it creates lime sediment as a secondary waste. Therefore, an inexpensive and environmental-friendly sulphate removal method is needed in addition to precipitation. In this study, carbon residues from a wood gasification process were repurposed as precursors to a suitable sorbent for SO42- ion removal. The raw material was modified using ZnCl2, BaCl2, CaCl2, FeCl3, or FeCl2. Carbon residues modified with FeCl3 were selected for further consideration because the removal efficiency toward sulphate was the highest. Batch sorption experiments were performed to evaluate the effects of the initial pH, initial SO42- ion concentration, and contact time on sulphate removal. The removal of SO42- ions using Fe-modified carbon residue was notably higher compared with unmodified carbon residue and commercially available activated carbon. The sorption data exhibited pseudo-second-order kinetics. The isotherm analysis indicated that the sorption data of Fe-modified carbon residues can be represented by the bi-Langmuir isotherm model.

Chemical sulphate removal for treatment of construction and demolition debris leachate.

Science.gov (United States)

Kijjanapanich, Pimluck; Annachhatre, Ajit P; Esposito, Giovanni; Lens, Piet N L

2014-08-01

Construction and demolition debris (CDD) is a product of construction, renovation or demolition activities. It has a high gypsum content (52.4% of total gypsum), concentrated in the CDD sand (CDDS) fraction. To comply with the posed limit of the maximum amount of sulphate present in building sand, excess sulphate needs to be removed. In order to enable reuse of CDDS, a novel treatment process is developed based on washing of the CDDS to remove most of the gypsum, and subsequent sulphate removal from the sulphate-rich CDDS leachate. This study aims to assess chemical techniques, i.e. precipitation and adsorption, for sulphate removal from the CDDS leachate. Good sulphate removal efficiencies (up to 99.9%) from the CDDS leachate can be achieved by precipitation with barium chloride (BaCl2) and lead(II) nitrate (Pb(NO3)2). Precipitation with calcium chloride (CaCl2), calcium carbonate (CaCO3) and calcium oxide (CaO) gave less efficient sulphate removal. Adsorption of sulphate to aluminium oxide (Al2O3) yielded a 50% sulphate removal efficiency, whereas iron oxide-coated sand as adsorbent gave only poor (10%) sulphate removal efficiencies.

Uranium and sulphate values from carbonate leach process

International Nuclear Information System (INIS)

Berger, B.

1983-01-01

The process concerns the recovery of uraniferous and sulphur values from liquor resulting from the attack of sulphur containing uraniferous ores by an alkaline solution of sodium carbonate and/or bicarbonate. Ammonia is introduced into the liquor to convert any HCO 3 - to CO 3 2- . The neutralised liquor from this step is then contacted with an anion exchange resin to fix the uranium and sulphate ions, leaving a liquor containing ammonia, sodium carbonate and/or bicarbonate in solution. Uranium and sulphate ions are eluted with an ammonia carbonate and/or bicarbonate solution to yield a solution of ammonium uranyl carbonate complex and ammonium sulphate. The solution is subjected to thermal treatment until a suspension of precipitated ammonium uranate and/or diuranate is obtained in a solution of the ammonium sulphate. Carbon dioxide, ammonia and water vapor are driven off. The precipitated ammonium uranate and/or diuranate is then separated from the solution of ammonium sulphate and the precipitate is calcined to yield uranium trioxide and ammonia

Spontaneous growth of whiskers from an interlayer of Mo sub 2 C beneath a diamond particle deposited in a combustion-flame

Energy Technology Data Exchange (ETDEWEB)

Okada, Katsuyuki; Komatsu, Shojiro; Ishigaki, Takamasa; Matsumoto, Seiichiro; Moriyoshi, Yusuke (National Inst. for Research in Inorganic Materials, Tsukuba, Ibaraki (Japan))

1992-02-01

When diamond particles deposited on a molybdenum substrate in a C{sub 2}H{sub -}O{sub 2} combustion-flame were kept for one year in the ambient atmosphere at room temperature, spontaneous whisker growth from an interlayer of Mo{sub 2}C beneath the diamond particles took place. The whiskers were clarified by electron probe micro-analysis (EPMA) and transmission electron microscopy (TEM) in a polycrystal composed of MoO{sub 2}, MoOC, and Mo{sub 2}C. The growth mechanism of them is discussed from two different points of view as follows: One is that the oxidation of an interlayer of Mo{sub 2}C beneath a diamond particle effectively reduces the surface free energy between the interlayer and diamond particle; consequently, the whisker can grow by using a screw dislocation. The other is that the internal stress existing between a diamond particle and an Mo{sub 2}C interlayer provides a very reactive zone where the growth of whisker takes place through the oxidation of Mo{sub 2}C. (orig.).

Production of magnesium metal

Science.gov (United States)

Blencoe, James G [Harriman, TN; Anovitz, Lawrence M [Knoxville, TN; Palmer, Donald A [Oliver Springs, TN; Beard, James S [Martinsville, VA

2010-02-23

A process of producing magnesium metal includes providing magnesium carbonate, and reacting the magnesium carbonate to produce a magnesium-containing compound and carbon dioxide. The magnesium-containing compound is reacted to produce magnesium metal. The carbon dioxide is used as a reactant in a second process. In another embodiment of the process, a magnesium silicate is reacted with a caustic material to produce magnesium hydroxide. The magnesium hydroxide is reacted with a source of carbon dioxide to produce magnesium carbonate. The magnesium carbonate is reacted to produce a magnesium-containing compound and carbon dioxide. The magnesium-containing compound is reacted to produce magnesium metal. The invention further relates to a process for production of magnesium metal or a magnesium compound where an external source of carbon dioxide is not used in any of the reactions of the process. The invention also relates to the magnesium metal produced by the processes described herein.

Magnesium sulphate as an adjuvant to bupivacaine in ultrasound-guided transversus abdominis plane block in patients scheduled for total abdominal hysterectomy under subarachnoid block

Directory of Open Access Journals (Sweden)

Shelly Rana

2016-01-01

Full Text Available Background and Aims: Transversus abdominis plane (TAP block has proven to be an effective component of multimodal analgesic regimens for a variety of abdominal procedures. Magnesium sulphate (MgSO4 N-methyl-D-aspartate receptor antagonist has the potential to be an ideal adjuvant in TAP block. We studied the efficacy of MgSO4as an adjuvant to bupivacaine in TAP block in patients scheduled for total abdominal hysterectomy (TAH under subarachnoid block (SAB. Methods: Sixty-five women belonging to American Society of Anesthesiologists physical status 1 or 2, aged between 35 and 70 years, scheduled for TAH under SAB were recruited. Patients in Group B (n = 32 received 18 mL 0.25% bupivacaine (45 mg with 2 mL normal saline (NS, whereas those in Group BM (n = 33 received 18 mL 0.25% bupivacaine (45 mg with 1.5 mL (150 mg MgSO4and 0.5 mL NS in the ultrasound (USG-guided TAP block performed on each side after the completion of the surgery under SAB. They were evaluated for pain at 0, 2, 4, 6, 12 and 24 h, time to first rescue analgesic and duration of postoperative analgesia were noted. Results: The post-operative visual analogue scale (VAS scores were lower in Group BM at 4, 6 and 12 h (P < 0.05. Mean duration of analgesia was significantly prolonged in Group BM with lesser requirement of rescue analgesic (P < 0.05 up to 12 h. Conclusion: MgSO4 (150 mg as an adjuvant to bupivacaine in USG-guided TAP block reduces post-operative pain scores, prolongs the duration of analgesia and decreases demands for rescue analgesics.

Ethanolic extract of Astragali radix and Salviae radix prohibits oxidative brain injury by psycho-emotional stress in whisker removal rat model.

Directory of Open Access Journals (Sweden)

Hyeong-Geug Kim

Full Text Available Myelophil, an ethanolic extract of Astragali Radix and Salviae Radix, has been clinically used to treat chronic fatigue and stress related disorders in South Korea. In this study, we investigated the protective effects of Myelophil on a whisker removal-induced psycho-emotional stress model. SD rats were subjected to whisker removal after oral administration of Myelophil or ascorbic acid for consecutive 4 days. Whisker removal considerably increased total reactive oxygen species in serum levels as well as cerebral cortex and hippocampal regions in brain tissues. Lipidperoxidation levels were also increased in the cerebral cortex, hippocampus regions, and brain tissue injuries as shown in histopathology and immunohistochemistry. However, Myelophil significantly ameliorated these alterations, and depletion of glutathione contents in both cerebral cortex and hippocampus regions respectively. Serum levels of corticosterone and adrenaline were notably altered after whisker removal stress, whereas these abnormalities were significantly normalized by pre-treatment with Myelophil. The NF-κB was notably activated in both cerebral cortex and hippocampus after whisker removal stress, while it was efficiently blocked by pre-treatment with Myelophil. Myelophil also significantly normalizes alterations of tumor necrosis factor-α, interleukin (IL-1β, IL-6 and interferon-γ in both gene expressions and protein levels. These results suggest that Myelophil has protective effects on brain damages in psycho-emotional stress, and the underlying mechanisms involve regulation of inflammatory proteins, especially NF-κB modulation.

Timeline (Bioavailability) of Magnesium Compounds in Hours: Which Magnesium Compound Works Best?

Science.gov (United States)

Uysal, Nazan; Kizildag, Servet; Yuce, Zeynep; Guvendi, Guven; Kandis, Sevim; Koc, Basar; Karakilic, Aslı; Camsari, Ulas M; Ates, Mehmet

2018-04-21

Magnesium is an element of great importance functioning because of its association with many cellular physiological functions. The magnesium content of foods is gradually decreasing due to food processing, and magnesium supplementation for healthy living has become increasingly popular. However, data is very limited on the bioavailability of various magnesium preparations. The aim of this study is to investigate the bioavailability of five different magnesium compounds (magnesium sulfate, magnesium oxide, magnesium acetyl taurate, magnesium citrate, and magnesium malate) in different tissues. Following a single dose 400 mg/70 kg magnesium administration to Sprague Dawley rats, bioavailability was evaluated by examining time-dependent absorption, tissue penetration, and the effects on the behavior of the animals. Pharmacokinetically, the area under the curve calculation is highest in the magnesium malate. The magnesium acetyl taurate was found to have the second highest area under the curve calculation. Magnesium acetyl taurate was rapidly absorbed, able to pass through to the brain easily, had the highest tissue concentration level in the brain, and was found to be associated with decreased anxiety indicators. Magnesium malate levels remained high for an extended period of time in the serum. The commonly prescribed dietary supplements magnesium oxide and magnesium citrate had the lowest bioavailability when compared to our control group. More research is needed to investigate the bioavailability of magnesium malate and acetyl taurate compounds and their effects in specific tissues and on behavior.

Zinc oxide crystal whiskers as a novel sorbent for solid-phase extraction of flavonoids.

Science.gov (United States)

Wang, Licheng; Shangguan, Yangnan; Hou, Xiudan; Jia, Yong; Liu, Shujuan; Sun, Yingxin; Guo, Yong

2017-08-15

As a novel solid-phase extraction material, zinc oxide crystal whiskers were used to extract flavonoid compounds and showed good extraction abilities. X-ray diffraction, scanning electron microscopy with energy dispersive X-ray spectroscopy and surface area/pore volume characterized the sorbent. The zinc oxide was packed into a solid-phase extraction micro-column and its extraction ability was evaluated by four model flavonoid compounds. The sample loading and elution parameters were optimized and the zinc oxide based analytical method for flavonoids was established. It showed that the method has wide linearities from 1 to 150μg/L and low limits of detection at 0.25μg/L. The relative standard deviations of a single column repeatability and column to column reproducibility were less than 6.8% and 10.6%. Several real samples were analyzed by the established method and satisfactory results were obtained. The interactions between flavonoids and zinc oxide were calculated and proved to be from the Van der Waals' forces between the 4p and 5d orbitals from zinc atom and the neighboring π orbitals from flavonoid phenyl groups. Moreover, the zinc oxide crystal whiskers showed good stability and could be reused more than 50 times under the operation conditions. This work proves that the zinc oxide crystal whiskers are a good candidate for flavonoids enrichment. Copyright © 2017. Published by Elsevier B.V.

Sulphate Incorporation in Borosilicate Glasses and Melts: a Kinetic Approach

Energy Technology Data Exchange (ETDEWEB)

Lenoir, M. [CEA, DEN, Laboratoire d' etude et de Developpement de Matrices de Conditionnement, Centre de Marcoule, 30207 Bagnols-sur-Ceze (France); Physique des Mineraux et Magmas, UMR 7047, CNRS- Institut de Physique du Globe de Paris, 7 place Jussieu, 75252 Paris 05 (France); Grandjean, A. [Institut de Chimie Separative de Marcoule, UMR 5257, Laboratoire des Nanomateriaux Autoreparants, Marcoule, 30207 Bagnols-sur-Ceze (France); Dussossoy, J.L. [CEA, DEN, Laboratoire d' etude et de Developpement de Matrices de Conditionnement, Centre de Marcoule, 30207 Bagnols-sur-Ceze (France); Neuville, D.R. [Physique des Mineraux et Magmas, UMR 7047, CNRS- Institut de Physique du Globe de Paris, 7 place Jussieu, 75252 Paris 05 (France)

2008-07-01

The kinetics of sulphate departure in a sodium borosilicate melt were studied using in situ Raman spectroscopy. This technique allows the quantification of the amount of sulphate dissolved in a borosilicate glass as a function of heating time by comparison with measurements obtained by microprobe wavelength dispersive spectrometry. To quantify the sulphate content obtained with Raman spectroscopy, the integrated intensity of the sulphate band at 990 cm{sup -1} was scaled to the sum of the integrated bands between 800 and 1200 cm{sup -1}, bands that are assigned to Qn silica units on the basis of previous literature. Calibration curves were then determined for two different samples. An evaluation of the kinetics of departure of sulphate could thus be made as a function of the viscosity of the borosilicate glass, showing that the kinetics were controlled by the diffusion of sulphate and its volatilization from the melt. This experimental method allows in situ measurements of sulphate content at high temperature which cannot be obtained by any other simple technique. (authors)

Strain gradient plasticity effects in whisker-reinforced metals

DEFF Research Database (Denmark)

Niordson, Christian Frithiof

2002-01-01

A metal reinforced by fibers in the micron range is studied using the strain gradient plasticity theory of Fleck and Hutchinson (2001). Cell-model analyzes are used to study the influence of the material length parameters numerically. Different higher order boundary conditions are considered...... at the fiber-matrix interface. The results are presented as overall stress-strain curves for the whisker-reinforced metal, and also contour plots of effective plastic strain are shown. The strain gradient plasticity theory predicts a significant stiffening effect when compared to conventional models...

Electrochemical migration, whisker formation, and corrosion behavior of printed circuit board under wet H2S environment

International Nuclear Information System (INIS)

Zou, Shiwen; Li, Xiaogang; Dong, Chaofang; Ding, Kangkang; Xiao, Kui

2013-01-01

Highlights: •The electrochemical migration, whisker formation, and corrosion behavior of PCB under wet H 2 S environment were observed and studied systematically. •The process of electrochemical migration of solder joints is explained. •The corrosion mechanism of PCB interconnectors induced by micro pores under wet H 2 S environment is discussed, and the corrosion reaction model is proposed. -- Abstract: Electrochemical migration, whisker formation, and corrosion behavior of printed circuit board (PCB) under wet H 2 S environment were analyzed by environment scanning electron microscope (ESEM), Energy dispersive X-ray spectroscopy (EDS) with mapping and element phase cluster (EPC) techniques, Raman Spectrum analysis and electrochemical impedance spectroscopy (EIS) technology. The results showed that nonuniform corrosion behavior occurred on PCB surfaces under 1 ppm wet H 2 S at 40 °C; whiskers formed on the inner sidewall of via-holes with a growth rate of 1.2 Å/s; numerous corrosion products migrated through the pore of plated gold layer, which broke off the protective layer. The corrosion rate was accelerated according to the big-cathode-small-anode model

Magnesium and Osteoporosis

Directory of Open Access Journals (Sweden)

Ferda Özdemir

2004-03-01

Full Text Available Osteoporosis (OP is a condition of bone fragility resulting from micro-architectural deterioration and decreased bone mass. OP depends on the interaction of genetic, hormonal, environmental and nutritional factors. Chronic low intakes of vitamin D and possibly magnesium, zinc, fluoride and vitamins K, B12, B6 and folic acid may predispose to osteoporosis. Magnesium is a mineral needed by every cell of your body. It helps maintain normal muscle and nerve function, keeps heart rhythm steady, and bones strong. Mg serves as co-factors for enzymes that help build bone matrix. Magnesium deficiency occurs due to excessive loss of magnesium in urine, gastrointestinal system disorders that cause a loss of magnesium or limit magnesium absorption, or a chronic low intake of magnesium. Signs of magnesium deficiency include confusion, disorientation, loss of appetite, depression, muscle contractions and cramps, tingling, numbness, abnormal heart rhythms, coronary spasm, and seizures. Magnesium deficiency alters calcium metabolism and the hormones that regulates calcium. Several studies have suggested that magnesium supplementation may improve bone mineral density and prevent fractures.

Magnesium Borohydride: From Hydrogen Storage to Magnesium Battery**

OpenAIRE

Mohtadi, Rana; Matsui, Masaki; Arthur, Timothy S; Hwang, Son-Jong

2012-01-01

Beyond hydrogen storage: The first example of reversible magnesium deposition/stripping onto/from an inorganic salt was seen for a magnesium borohydride electrolyte. High coulombic efficiency of up to 94 % was achieved in dimethoxyethane solvent. This Mg(BH_4)_2 electrolyte was utilized in a rechargeable magnesium battery.

Developing an Empirical Model for Estimating the Probability of Electrical Short Circuits from Tin Whiskers. Part 2

Science.gov (United States)

Courey, Karim J.; Asfour, Shihab S.; Onar, Arzu; Bayliss, Jon A.; Ludwig, Larry L.; Wright, Maria C.

2009-01-01

To comply with lead-free legislation, many manufacturers have converted from tin-lead to pure tin finishes of electronic components. However, pure tin finishes have a greater propensity to grow tin whiskers than tin-lead finishes. Since tin whiskers present an electrical short circuit hazard in electronic components, simulations have been developed to quantify the risk of said short circuits occurring. Existing risk simulations make the assumption that when a free tin whisker has bridged two adjacent exposed electrical conductors, the result is an electrical short circuit. This conservative assumption is made because shorting is a random event that had an unknown probability associated with it. Note however that due to contact resistance electrical shorts may not occur at lower voltage levels. In our first article we developed an empirical probability model for tin whisker shorting. In this paper, we develop a more comprehensive empirical model using a refined experiment with a larger sample size, in which we studied the effect of varying voltage on the breakdown of the contact resistance which leads to a short circuit. From the resulting data we estimated the probability distribution of an electrical short, as a function of voltage. In addition, the unexpected polycrystalline structure seen in the focused ion beam (FIB) cross section in the first experiment was confirmed in this experiment using transmission electron microscopy (TEM). The FIB was also used to cross section two card guides to facilitate the measurement of the grain size of each card guide's tin plating to determine its finish.

Gastrointestinal tract wall visualization and distention during abdominal and pelvic multidetector CT with a neutral barium sulphate suspension: comparison with positive barium sulphate suspension and with water.

Science.gov (United States)

Oliva, M R; Erturk, S M; Ichikawa, T; Rocha, T; Ros, P R; Silverman, S G; Mortele, K J

2012-01-01

When examining patients with contrast-enhanced multidetector-row CT, we determined if the stomach and small bowel were visualized and distended better with a neutral barium sulphate suspension than with positive barium sulphate suspension or water. After obtaining approval from our institutional review board, 156 patients (women: 84; mean age: 54 yrs) with no history of gastrointestinal tract disease were randomized prospectively to receive orally either 900 ml of neutral (0.1% w/v) barium sulphate suspension (n = 53), 900 ml of positive (2.1% w/v) barium sulphate suspension (n = 53), or 900 ml of water (n = 50), prior to undergoing contrast-enhanced abdominal and pelvic multidetector-row CT. Two independent radiologists evaluated the stomach, and small bowel, for luminal distension and wall visualization, using a five point scale. Results were compared using Kruskal-Wallis and Mann-Whitney U tests. The walls of the stomach, and small bowel were visualized better in patients who were administered neutral barium sulphate suspension than those who were administered either positive barium sulphate suspension (p barium sulphate suspension, the stomach and small bowel were distended better compared to patients administered water (p barium sulphate suspension (p contrast-enhanced abdominal and pelvic multidetector-row CT, orally administered neutral barium sulphate suspension allows the gastrointestinal tract to be visualized and distended better than either positive barium sulphate suspension, or water.

Effects of agmatine sulphate on facial nerve injuries.

Science.gov (United States)

Surmelioglu, O; Sencar, L; Ozdemir, S; Tarkan, O; Dagkiran, M; Surmelioglu, N; Tuncer, U; Polat, S

2017-03-01

To evaluate the effect of agmatine sulphate on facial nerve regeneration after facial nerve injury using electron and light microscopy. The study was performed on 30 male Wistar albino rats split into: a control group, a sham-treated group, a study control group, an anastomosis group, and an anastomosis plus agmatine sulphate treatment group. The mandibular branch of the facial nerve was dissected, and a piece was removed for histological and electron microscopic examination. Regeneration was better in the anastomosis group than in the study control group. However, the best regeneration findings were seen in the agmatine sulphate treatment group. There was a significant difference between the agmatine group and the others in terms of median axon numbers (p Agmatine sulphate treatment with anastomosis in traumatic facial paralysis may enhance nerve regeneration.

The reducibility of sulphuric acid and sulphate in aqueous solution

International Nuclear Information System (INIS)

Grauer, R.

1991-07-01

In connection with the Swedish project for final storage of spent fuel elements it was necessary to assess whether dissolved sulphate can corrode the copper canister. A simple reaction between copper and sulphate is thermodynamically impossible, but copper can react to give copper sulphide if an additional electron donor such as iron(II) is available. The problem was extended to the more general question of the reducibility of sulphur(VI) in dilute aqueous solution. Chemical reduction of sulphate does not take place in dilute solution at temperatures below 100 o C. In experiments on the reduction of sulphates under hydrothermal conditions a reaction only takes place at temperatures above 275-300 o C. The oxidising action of sulphuric acid on metals becomes perceptible only at acid concentrations over 45-50%. In experiments on the cathodic reduction of 74% sulphuric acid the formation of hydrogen sulphide and elementary sulphur starts, depending on the current density, at 50-130 o C, and polarographic measurements suggest that the reducible species is not the hydrogen sulphate ion but molecular sulphuric acid. The resistance of copper to oxygen-free sulphuric acid up to a concentration of 60% is well-known. Numerous processes in industrial electrochemistry take place in sulphuric acid or sulphate electrolytes. The reversible metal/metal-sulphate electrodes of lead and cadmium are unstable relative to the corresponding metal sulphides. Nevertheless the reversible lead sulphate electrode does not fail from sulphide formation. All these facts confirm that sulphur(VI) in dilute solution is completely inert towards chemical reducing agents and also to cathodic reduction. Thus corrosion of copper by sulphate under final-storage conditions and in the absence of sulphate reducing bacteria can be almost certainly be ruled out. (author) 5 figs., 85 refs

Whisker and Nose Tactile Sense Guide Rat Behavior in a Skilled Reaching Task

Directory of Open Access Journals (Sweden)

Pierantonio Parmiani

2018-02-01

Full Text Available Skilled reaching is a complex movement in which a forelimb is extended to grasp food for eating. Video-recordings analysis of control rats enables us to distinguish several components of skilled reaching: Orient, approaching the front wall of the reaching box and poking the nose into the slot to locate the food pellet; Transport, advancing the forelimb through the slot to reach-grasp the pellet; and Withdrawal of the grasped food to eat. Although food location and skilled reaching is guided by olfaction, the importance of whisker/nose tactile sense in rats suggests that this too could play a role in reaching behavior. To test this hypothesis, we studied skilled reaching in rats trained in a single-pellet reaching task before and after bilateral whisker trimming and bilateral infraorbital nerve (ION severing. During the task, bilaterally trimmed rats showed impaired Orient with respect to controls. Specifically, they detected the presence of the wall by hitting it with their nose (rather than their whiskers, and then located the slot through repetitive nose touches. The number of nose touches preceding poking was significantly higher in comparison to controls. On the other hand, macrovibrissae trimming resulted in no change in reaching/grasping or withdrawal components of skilled reaching. Bilaterally ION-severed rats, displayed a marked change in the structure of their skilled reaching. With respect to controls, in ION-severed rats: (a approaches to the front wall were significantly reduced at 3–5 and 6–8 days; (b nose pokes were significantly reduced at 3–5 days, and the slot was only located after many repetitive nose touches; (c the reaching-grasping-retracting movement never appeared at 3–5 days; (d explorative paw movements, equal to zero in controls, reached significance at 9–11 days; and (e the restored reaching-grasping-retracting sequence was globally slower than in controls, but the success rate was the same. These findings

Anthropogenic influence on the distribution of tropospheric sulphate aerosol

Energy Technology Data Exchange (ETDEWEB)

Langner, J; Rodhe, H; Crutzen, P J; Zimmermann, P [Swedish Meteorological and Hydrological Institute, Norrkoeping (Sweden)

1992-10-22

Human activities have increased global emissions of sulphur gases by about a factor of three during the past century, leading to increased sulphate aerosol concentrations, mainly in the Northern Hemisphere. Sulphate aerosols can affect the climate directly, by increasing the backscattering of solar radiation in cloud-free air, and indirectly, by providing additional cloud condensation nuclei. Here a global transport-chemistry model is used to estimate the changes in the distribution of tropospheric sulphate aerosol and deposition of non-seasalt sulphur that have occurred since pre-industrial times. The increase in sulphate aerosol concentration is small over the Southern Hemisphere oceans, but reaches a factor of 100 over northern Europe in winter. Calculations indicate, however, that at most 6% of the anthropogenic sulphur emissions is available for the formation of new aerosol particles. This is because about one-half of the sulphur dioxide is deposited on the Earth's surface, and most of the remainder is oxidized in cloud droplets so that the sulphate becomes associated with pre-existing particles. Even so, the rate of formation of new sulphate particles may have doubled since pre-industrial times. 18 refs., 3 figs.

3D printed biomimetic whisker-based sensor with co-planar capacitive sensing

NARCIS (Netherlands)

Delamare, John; Sanders, Remco G.P.; Krijnen, Gijsbertus J.M.

2016-01-01

This paper describes the development of a whisker sensor for tactile purposes and which is fabricated by 3D printing. Read-out consists of a capacitive measurement of a co-planar capacitance which is affected by a dielectric that is driven into the electric field of the capacitance. The current

Controlling Barium Sulphate Scale Deposition Problems in an unbleached Kraft Paper Mill

CSIR Research Space (South Africa)

Sithole, Bruce

2015-06-01

Full Text Available Troubleshooting of scale deposits and defects in paper samples showed that the problem was caused by barium sulphate and calcium sulphate scales. However, it was ascertained that barium sulphate was more of a concern than calcium sulphate...

Sulphate in Liquid Nuclear Waste: from Production to Containment

Energy Technology Data Exchange (ETDEWEB)

Lenoir, M.; Grandjean, A.; Ledieu, A.; Dussossoy, J.L.; Cau Dit Coumes, C.; Barre, Y.; Tronche, E. [CEA Marcoule, DEN/DTCD/SECM/LDMC, Batiment 208 BP17171, Bagnols sur Ceze, 30207 (France)

2009-06-15

Nuclear industry produces a wide range of low and intermediate level liquid radioactive wastes which can include different radionuclides such as {sup 90}Sr. In La Hague reprocessing plant and in the nuclear research centers of CEA (Commissariat a l'Energie Atomique), the coprecipitation of strontium with barium sulphate is the technique used to treat selectively these contaminated streams with the best efficiency. After the decontamination process, low and intermediate level activity wastes incorporating significant quantities of sulphate are obtained. The challenge is to find a matrix easy to form and with a good chemical durability which is able to confine this kind of nuclear waste. The current process used to contain sulphate-rich nuclear wastes is bituminization. However, in order to improve properties of containment matrices and simplify the process, CEA has chosen to supervise researches on other materials such as cements or glasses. Indeed, cements are widely used for the immobilization of a variety of wastes (low and intermediate level wastes) and they may be an alternative matrix to bitumen. Even if Portland cement, which is extensively used in the nuclear industry, presents some disadvantages for the containment of sulphate-rich nuclear wastes (risk of swelling and cracking due to delayed ettringite formation), other cement systems, such as calcium sulfo-aluminate binders, may be valuable candidates. Another matrix to confine sulphate-rich waste could be the glass. One of the advantages of this material is that it could also immobilize sulphate containing high level nuclear waste which is present in some countries. This waste comes from the use of ferrous sulfamate as a reducing agent for the conversion of Pu{sup 4+} to Pu{sup 3+} in the partitioning stage of the actinides during reprocessing. Sulphate solubility in borosilicate glasses has already been studied in CEA at laboratory and pilot scales. At a pilot scale, low level liquid waste has been

Magnesium borohydride: from hydrogen storage to magnesium battery.

Science.gov (United States)

Mohtadi, Rana; Matsui, Masaki; Arthur, Timothy S; Hwang, Son-Jong

2012-09-24

Beyond hydrogen storage: The first example of reversible magnesium deposition/stripping onto/from an inorganic salt was seen for a magnesium borohydride electrolyte. High coulombic efficiency of up to 94 % was achieved in dimethoxyethane solvent. This Mg(BH(4))(2) electrolyte was utilized in a rechargeable magnesium battery. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Peculiarities of physical and chemical processes of clinker formation in raw mixes with increased content of magnesium oxide in presence of barite waste

Science.gov (United States)

Novoselova, I. N.; Novosyolov, A. G.

2018-03-01

The article considers the influence of barite waste on clinker formation processes in raw mixes with the increased content of magnesium oxide. A by-product of the barite concentrate manufacture of Tolcheinskoye deposit has been used as a barite waste, its predominant content of barium sulphate BaSO4 amounts to 76,11%. The impact of BaO and SO3 has been revealed, particularly the impact of barium oxide on clinker formation processes in raw mixes with the increased content of magnesium oxide. It has been clarified that the addition of barite waste into a raw mix causes the formation of dicalcium silicate in two modifications, reduces the amount of alite and influences on the composition of tricalcium aluminate. Barium mono-alluminate is formed in the composition of the intermediate material. Solid solutions with barium oxide are formed in clinker phases. The authors have determined the saturation speed of calcium oxide in magnesium-bearing raw mixes with saturation coefficient (SC) 0,91 and 0,80 in the presence of 2 and 3% barite waste in the temperature range 1300-1450°C.

Interdependent action of nickel sulphate and X-rays on human lymphoblastoid leukeamic cells

International Nuclear Information System (INIS)

Bensimon, Jacques

1977-01-01

In a first experiment, cells were cultured in media supplemented by nickel sulphate, irradiated in same media and cultured in same media after irradiation. In a second experiment, cells were cultured during 18hrs. in media supplemented by nickel sulphate, and then cells were washed and cultured in normal media where they were irradiated. The nickel sulphate toxicity appears as a creasing function of the nickel sulphate concentration and the nickel sulphate action endurance. The nickel sulphate toxic effect is amplified by X-rays. This amplification is a time function that depends on the X-ray dose, nickel sulphate concentration and period of time from the outset of culture to the irradiation. The nickel sulphate toxic effect appears faster when nickel works after X-rays [fr

Ion irradiation effects on the matrix phase of SiCf/SiC composites prepared by the whisker growing assisted CVI process

International Nuclear Information System (INIS)

Park, Kyeong Hwan; Park, Ji Yeon; Kang, Suk Min; Kim, Weon Ju; Jung, Choong Hwan; Ryu, Woo Seog

2005-01-01

SiC f /SiC composites are one of promising candidates for structural material of the next generation energy system such as GFR and fusion reactors. A number of fabrication methods have been studied for obtaining an outstanding SiC f /SiC composite with a high density, high crystallinity and purity. SiC f /SiC composites consisted of whisker-reinforced matrix have a great potential at the viewpoint both of the fabrication process and the mechanical properties. SiC whiskers formed between SiC fibers improve the densification of SiC matrix during CVI process. In addition, the reinforced whiskers would be likely to enhance the mechanical properties of matrix and SiC f /SiC composite. While there has been significant developmental work on manufacturing the SiC f /SiC composite by the whisker growing assisted CVI process, detailed understanding of what effects the complex in the operating conditions combined with realistic materials property data is not adequately understood. Especially, its irradiation effects are even less clear and not well understood. A method of charged-particle irradiation is the most important R and D topics for simulating the core conditions of the advanced nuclear systems. Many studies on radiation effects of SiC and SiC f /SiC composites using a method of ion irradiation have in progress for R and D of the advanced nuclear systems. In this present work, changes of the mechanical property of SiC whisker-reinforced matrix in SiC f /SiC composite were evaluated by means of the depth sensing indentation method before and after chargedparticle irradiation

Magnesium in pregnancy.

Science.gov (United States)

Dalton, Lynne M; Ní Fhloinn, Deirdre M; Gaydadzhieva, Gergana T; Mazurkiewicz, Ola M; Leeson, Heather; Wright, Ciara P

2016-09-01

Magnesium deficiency is prevalent in women of childbearing age in both developing and developed countries. The need for magnesium increases during pregnancy, and the majority of pregnant women likely do not meet this increased need. Magnesium deficiency or insufficiency during pregnancy may pose a health risk for both the mother and the newborn, with implications that may extend into adulthood of the offspring. The measurement of serum magnesium is the most widely used method for determining magnesium levels, but it has significant limitations that have both hindered the assessment of deficiency and affected the reliability of studies in pregnant women. Thus far, limited studies have suggested links between magnesium inadequacy and certain conditions in pregnancy associated with high mortality and morbidity, such as gestational diabetes, preterm labor, preeclampsia, and small for gestational age or intrauterine growth restriction. This review provides recommendations for further study and improved testing using measurement of red cell magnesium. Pregnant women should be counseled to increase their intake of magnesium-rich foods such as nuts, seeds, beans, and leafy greens and/or to supplement with magnesium at a safe level. © The Author(s) 2016. Published by Oxford University Press on behalf of the International Life Sciences Institute. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Mesophilic and thermophilic anaerobic digestion of sulphate-containing wastewaters.

Science.gov (United States)

Colleran, E; Pender, S

2002-01-01

The effect of sulphate at an influent chemical oxygen demand (COD):sulphate ratio of 4 on the operational performance of anaerobic hybrid reactors treating molasses wastewater was investigated under mesophilic and thermophilic conditions in a long-term laboratory-scale study over a 1,081 day period. The presence of sulphate reduced the COD removal efficiency under both mesophilic and thermophilic conditions. At 55 degrees C, effluent acetate levels were consistently greater than 4000 mg l(-1) indicating that thermophilic acetate-utilising methane-producing bacteria (MPB) or sulphate-reducing bacteria (SRB) had not developed in the reactor under the conditions applied. At 37 degrees C, acetate was exclusively utilised by acetoclastic methanogens, whereas H2-utilising SRB predominated over H2-utilising MPB in the competition for hydrogen. By contrast, hydrogenotrophic MPB were shown to outcompete H2-utilising SRB during long-term thermophilic operation. 16SrDNA analysis of the seed sludge and reactor biomass on conclusion of the 37 degrees C and 55 degrees C trials illustrated that the dominant methanogen present on conclusion of the thermophilic trial in the absence of influent sulphate was related to Methanocorpusculum parvuum, and was capable of growth on both acetate and hydrogen. By contrast, an organism closely related to Methanobacterium thermoautotrophicum was the dominant methanogen present in the sulphate-fed reactor on completion of the thermophilic trial.

Effects of Adaptation on Discrimination of Whisker Deflection Velocity and Angular Direction in a Model of the Barrel Cortex

Directory of Open Access Journals (Sweden)

Mainak J. Patel

2018-06-01

Full Text Available Two important stimulus features represented within the rodent barrel cortex are velocity and angular direction of whisker deflection. Each cortical barrel receives information from thalamocortical (TC cells that relay information from a single whisker, and TC input is decoded by barrel regular-spiking (RS cells through a feedforward inhibitory architecture (with inhibition delivered by cortical fast-spiking or FS cells. TC cells encode deflection velocity through population synchrony, while deflection direction is encoded through the distribution of spike counts across the TC population. Barrel RS cells encode both deflection direction and velocity with spike rate, and are divided into functional domains by direction preference. Following repetitive whisker stimulation, system adaptation causes a weakening of synaptic inputs to RS cells and diminishes RS cell spike responses, though evidence suggests that stimulus discrimination may improve following adaptation. In this work, I construct a model of the TC, FS, and RS cells comprising a single barrel system—the model incorporates realistic synaptic connectivity and dynamics and simulates both angular direction (through the spatial pattern of TC activation and velocity (through synchrony of the TC population spikes of a deflection of the primary whisker, and I use the model to examine direction and velocity selectivity of barrel RS cells before and after adaptation. I find that velocity and direction selectivity of individual RS cells (measured over multiple trials sharpens following adaptation, but stimulus discrimination using a simple linear classifier by the RS population response during a single trial (a more biologically meaningful measure than single cell discrimination over multiple trials exhibits strikingly different behavior—velocity discrimination is similar both before and after adaptation, while direction classification improves substantially following adaptation. This is the

Rat whisker movement after facial nerve lesion: Evidence for autonomic contraction of skeletal muscle.

NARCIS (Netherlands)

Heaton, J.T.; Sheu, S.H.; Hohman, M.H.; Knox, C.J.; Weinberg, J.S.; Kleiss, I.J.; Hadlock, T.A.

2014-01-01

Vibrissal whisking is often employed to track facial nerve regeneration in rats; however, we have observed similar degrees of whisking recovery after facial nerve transection with or without repair. We hypothesized that the source of non-facial nerve-mediated whisker movement after chronic

Are high rates of sulphate reduction associated with anaerobic oxidation of methane

Energy Technology Data Exchange (ETDEWEB)

Devol, A H; Ahmed, S I

1981-01-01

Classical models of sulphur diagenesis in marine sediments are based on the assumption that the rate of sulphate reduction is first order with respect to oxidizable particulate organic carbon (POC). This assumption requires that oxidizable POC, sulphate concentration and the sulphate reduction rate be highest at the top of the sulphate reduction zone and decrease exponentially with increasing sediment depth. However, to explain recent observations of concave upwards methane distributions, the anaerobic consumption of methane has been proposed. Furthermore, it has been proposed that this consumption takes place near the bottom of the sulphate reducing zone where sulphate concentrations are low. Thus, if sulphate reducing bacteria are associated with the anaerobic oxidation of methane, a peak in sulphate reduction rate might be expected in this deep consumption zone. The importance of the process in sedimentary sulphur diagenesis is indicated by calculations estimating that 30 to 75% of the downward sulphate flux at depth may be consumed by methane oxidation within this zone. We present here profiles of sulphate reduction rate in anoxic sediments that show distinct local maxima at the depth where the anaerobic oxidation of methane would be expected. Our measurements were made during July and August 1978 in Saanich Inlet, an anoxic fjord located on the south-east of Vancouver Island, British Columbia. The inlet has a shallow sill (approx 70 m) which restricts circulation of the deeper water (maximum depth 225 m) inside the basin to the extent that for about 8 months of the year the bottom waters contain hydrogen sulphide, the inlet is an ideal location for studying sedimentary sulphate reduction because reactions with oxygen and the effects of burrowing organisms can be neglected.

Analysis of the collar-whisker structure of temperate lactococcal bacteriophage TP901-1

DEFF Research Database (Denmark)

Vegge, Christina Skovgaard; Neve, Horst; Brøndsted, Lone

2006-01-01

Proteins homologous to the protein NPS (neck passage structure) are widespread among lactococcal phages. We investigated the hypothesis that NPS is involved in the infection of phage TP901-1 by analysis of an NPS mutant. NPS was determined to form a collar-whisker complex but was shown to be none...

Magnesium stannide as a high-capacity anode for magnesium-ion batteries

Science.gov (United States)

Nguyen, Dan-Thien; Song, Seung-Wan

2017-11-01

Driven by the limited global resources of lithium, magnesium metal batteries are considered as potential energy storage systems. The battery chemistry of magnesium metal anode, however, limits the selection of electrolytes, cathode materials and working temperature, making the realization of magnesium metal batteries complicated. Herein, we report the development of a new magnesium-insertion anode, magnesium stannide (Mg2Sn), and demonstrate reversible electrochemical Mg2+-extraction and insertion of Mg2Sn anode at 0.2 V versus Mg, delivering discharge capacity of 270 mAhg-1 in a half-cell with the electrolyte of PhMgCl/THF and enabling of room temperature magnesium-ion batteries with Mg2Sn anode combined with Mg-free oxide cathode and conventional-type electrolyte of Mg(TFSI)2/diglyme. The combination of Mg2Sn anode with various cathodes and electrolytes holds great promise for enabling room temperature magnesium-ion batteries.

Effect of magnesium deficiency on renal magnesium and calcium transport in the rat.

OpenAIRE

Carney, S L; Wong, N L; Quamme, G A; Dirks, J H

1980-01-01

Recollection of micropuncture experiments were performed on acutely thyroparathyroidectomized rats rendered magnesium deficient by dietary deprivation. Urinary magnesium excretion fell from a control of 15 to 3% of the filtered load after magnesium restriction. The loop of Henle, presumably the thick ascending limb, was the major modulator for renal magnesium homeostasis. The transport capacity for magnesium, however, was less in deficient rats than control animals. Absolute magnesium reabsor...

Magnesium, magnesium alloys, and magnesium composites

National Research Council Canada - National Science Library

Gupta, M; Sharon, Nai Mui Ling

2011-01-01

.... With the popularity of magnesium-based materials in the automotive, aerospace, electronics, and sports equipment industries, and its unique role as a lightweight, energy-saving and high-performance...

Myth or Reality-Transdermal Magnesium?

Science.gov (United States)

Gröber, Uwe; Werner, Tanja; Vormann, Jürgen; Kisters, Klaus

2017-07-28

In the following review, we evaluated the current literature and evidence-based data on transdermal magnesium application and show that the propagation of transdermal magnesium is scientifically unsupported. The importance of magnesium and the positive effects of magnesium supplementation are extensively documented in magnesium deficiency, e.g., cardiovascular disease and diabetes mellitus. The effectiveness of oral magnesium supplementation for the treatment of magnesium deficiency has been studied in detail. However, the proven and well-documented oral magnesium supplementation has become questioned in the recent years through intensive marketing for its transdermal application (e.g., magnesium-containing sprays, magnesium flakes, and magnesium salt baths). In both, specialist and lay press as well as on the internet, there are increasing numbers of articles claiming the effectiveness and superiority of transdermal magnesium over an oral application. It is claimed that the transdermal absorption of magnesium in comparison to oral application is more effective due to better absorption and fewer side effects as it bypasses the gastrointestinal tract.

Low magnesium level

Science.gov (United States)

Low magnesium level is a condition in which the amount of magnesium in the blood is lower than normal. The medical ... that convert or use energy ( metabolism ). When the level of magnesium in the body drops below normal, ...

System and process for production of magnesium metal and magnesium hydride from magnesium-containing salts and brines

Science.gov (United States)

McGrail, Peter B.; Nune, Satish K.; Motkuri, Radha K.; Glezakou, Vassiliki-Alexandra; Koech, Phillip K.; Adint, Tyler T.; Fifield, Leonard S.; Fernandez, Carlos A.; Liu, Jian

2016-11-22

A system and process are disclosed for production of consolidated magnesium metal products and alloys with selected densities from magnesium-containing salts and feedstocks. The system and process employ a dialkyl magnesium compound that decomposes to produce the Mg metal product. Energy requirements and production costs are lower than for conventional processing.

Bacterial sulphate reduction and the development of alkalinity. II. Laboratory experiments with soils

Energy Technology Data Exchange (ETDEWEB)

Abd-El-Malek, Y; Rizk, S G

1963-01-01

In waterlogged soils sulphate reduction was characterized by increases in counts of sulphate reducers, and increase in titratable alkalinity, insoluble carbonate, and soluble sulphides, and a decrease in soluble Ca/sup 2 +/ + Mg/sup 2 +/. Presence of organic matter greatly enhanced sulphate reduction. A linear relationship between the amount of sulphate reduced and increases in titratable alkalinity and insoluble carbonate were apparent. The potential effects of sulphate reduction on soil fertility through the development of alkalinity are discussed.

Anticorrosive magnesium hydroxide coating on AZ31 magnesium alloy by hydrothermal method

International Nuclear Information System (INIS)

Zhu Yanying; Wu Guangming; Xing Guangjian; Li Donglin; Zhao Qing; Zhang Yunhong

2009-01-01

Magnesium alloys are potential biodegradable biomaterials in orthopedic surgery. However, the rapid degradation rate has limited their application in biomedical field. A great deal of studies have been done to improve the resistance of magnesium alloys. In this article, An anticorrosive magnesium hydroxide coating with a thickness of approximately 100μm was formed on an AZ31 magnesium alloy by hydrothermal method. The morphology of the coatings were observed by an optical microscope and SEM. And the samples were soaked in hank's solution (37 deg. C) to investigate the corrosion resistance. Magnesium alloy AZ31 with magnesium hydroxide coatings present superior corrosion resistance than untreated samples.

Magnesium and Space Flight

Science.gov (United States)

Smith, Scott M.; Zwart, Sara R.

2015-01-01

Magnesium is an essential nutrient for muscle, cardiovascular, and bone health on Earth, and during space flight. We sought to evaluate magnesium status in 43 astronauts (34 male, 9 female; 47 ± 5 years old, mean ± SD) before, during, and after 4–6-month space missions. We also studied individuals participating in a ground analog of space flight (head-down-tilt bed rest; n = 27 (17 male, 10 female), 35 ± 7 years old). We evaluated serum concentration and 24-h urinary excretion of magnesium, along with estimates of tissue magnesium status from sublingual cells. Serum magnesium increased late in flight, while urinary magnesium excretion was higher over the course of 180-day space missions. Urinary magnesium increased during flight but decreased significantly at landing. Neither serum nor urinary magnesium changed during bed rest. For flight and bed rest, significant correlations existed between the area under the curve of serum and urinary magnesium and the change in total body bone mineral content. Tissue magnesium concentration was unchanged after flight and bed rest. Increased excretion of magnesium is likely partially from bone and partially from diet, but importantly, it does not come at the expense of muscle tissue stores. While further study is needed to better understand the implications of these findings for longer space exploration missions, magnesium homeostasis and tissue status seem well maintained during 4–6-month space missions. PMID:26670248

Magnesium and Space Flight

Directory of Open Access Journals (Sweden)

Scott M. Smith

2015-12-01

Full Text Available Magnesium is an essential nutrient for muscle, cardiovascular, and bone health on Earth, and during space flight. We sought to evaluate magnesium status in 43 astronauts (34 male, 9 female; 47 ± 5 years old, mean ± SD before, during, and after 4–6-month space missions. We also studied individuals participating in a ground analog of space flight (head-down-tilt bed rest; n = 27 (17 male, 10 female, 35 ± 7 years old. We evaluated serum concentration and 24-h urinary excretion of magnesium, along with estimates of tissue magnesium status from sublingual cells. Serum magnesium increased late in flight, while urinary magnesium excretion was higher over the course of 180-day space missions. Urinary magnesium increased during flight but decreased significantly at landing. Neither serum nor urinary magnesium changed during bed rest. For flight and bed rest, significant correlations existed between the area under the curve of serum and urinary magnesium and the change in total body bone mineral content. Tissue magnesium concentration was unchanged after flight and bed rest. Increased excretion of magnesium is likely partially from bone and partially from diet, but importantly, it does not come at the expense of muscle tissue stores. While further study is needed to better understand the implications of these findings for longer space exploration missions, magnesium homeostasis and tissue status seem well maintained during 4–6-month space missions.

Kinetics and mechanism of protection of thymine from sulphate ...

Indian Academy of Sciences (India)

Unknown

The rate constant of sulphate radical anion with caffeic acid has been ... transfer of radical sites from base moiety to sugar moiety. Strand ... titrated with a standard ceric ammonium sulphate solution as reported by Kapoor et al.7. At room ...

Whiskers growth and self-healing in Ti-based metallic glasses during ion irradiation

Science.gov (United States)

Zhang, Kun; Hu, Zheng; Zhao, Ziqiang; Wei, Bingchen; Li, Yansen; Wei, Yuhang

2018-04-01

Ti-based metallic glasses were subjected to a 20 MeV Cl4+ ion radiation under liquid-nitrogen cooling. Their responses, as well as effects of the electronic excitation and nucleus-nucleus collision were evaluated. The collision cascade during irradiation typically changes the structure by increasing the liquid-like zone/cluster, or the content of the free volume. However, along the ion incident depth, the structure change is inhomogeneous. Numerous whiskers appear and aggregate on the side of the irradiation surface, which are several micrometers away from the edge. This corresponds with the maximum collision depth obtained by the Monte Carlo simulation, where nuclear loss plays a dominant role. Moreover, the liquid-like zone continually forms, which add to the whiskers growth and subsequent self-healing. Results suggest that the irradiation-induced local shear stress combines with the well-localized liquid-like zone results in the observed phenomena. This study demonstrates that metallic glasses have high morphological instability under ion irradiation, which assets can pave new paths for their further applications.

Bacterial sulphate reduction and the development of alkalinity. I. Experiments with synthetic media

Energy Technology Data Exchange (ETDEWEB)

Abd-El-Malek, Y; Rizk, S G

1963-01-01

In liquid cultures of desulphovibrio desulphuricans the effects of the following on sulphate reduction were determined: The type of cation (ca++ or na+) attached to the sulphate ion; the presence of calcium carbonate alone and with sodium chloride; the concentration of sodium sulphate, sodium lactate and sodium chloride; and the initial pH. The titratable alkalinity formed as a result of sulphate reduction was found to be quantitatively related to the sulphate reduced, and apparently unaffected by strain variation or energy source.

Preparation of Polyaniline-Doped Fullerene Whiskers

Directory of Open Access Journals (Sweden)

Bingzhe Wang

2013-01-01

Full Text Available Fullerene C60 whiskers (FWs doped with polyaniline emeraldine base (PANI-EB were synthesized by mixing PANI-EB/N-methyl pyrrolidone (NMP colloid and FWs suspension based on the nature of the electron acceptor of C60 and electron donor of PANI-EB. Scanning electron microscopy (SEM, Fourier transform infrared (FT-IR, and ultraviolet-visible (UV-Vis spectra characterized the morphology and molecular structure of the FWs doped with PANI-EB. SEM observation showed that the smooth surface of FWs was changed to worm-like surface morphology after being doped with PANI-EB. The UV-Vis spectra suggested that charge-transfer (CT complex of C60 and PANI-EB was formed as PANI-EBδ+-C60δ-. PANI-EB-doped FWs might be useful as a new type of antibacterial and self-cleaning agent as well as multifunctional material to improve the human health and living environment.

Sulphation reactions of oxidic dust particles in waste heat boiler environment. Literature review

Energy Technology Data Exchange (ETDEWEB)

Ranki, T.

1999-09-01

Sulphation of metal oxides has an important role in many industrial processes. In different applications sulphation reactions have different aims and characteristics. In the flash smelting process sulphation of oxidic flue dust is a spontaneous and inevitable phenomena, which takes place in the waste heat boiler (WHB) when cooling down hot dust laden off-gases from sulphide smelters. Oxidic dust particles (size 0 - 50 {mu}m) react with O{sub 2} and SO{sub 2} or SO{sub 3} in a certain temperature range (500 - 800 deg C). Sulphation reactions are highly exothermic releasing large amount of heat, which affects the gas cooling and thermal performance of the boiler. Thermodynamics and kinetics of the system have to be known to improve the process and WHB operation. The rate of sulphation is affected by the prevailing conditions (temperature, gas composition) and particle size and microstructure (porosity, surface area). Some metal oxides (CuO) can react readily with SO{sub 2} and O{sub 2} and act as self-catalysts, but others (NiO) require the presence of an external catalyst to enhance the SO{sub 3} formation and sulphation to proceed. Some oxides (NiO) sulphate directly, some (CuO) may form first intermediate phases (basic sulphates) depending on the reaction conditions. Thus, the reaction mechanisms are very complex. The aim of this report was to search information about the factors affecting the dust sulphation reactions and suggested reaction mechanisms and kinetics. Many investigators have studied sulphation thermodynamics and reaction kinetics and mechanisms of macroscopical metal oxide pieces, but only few articles have been published about sulphation of microscopical particles, like dust. All the found microscale studies dealt with sulphation reactions of calcium oxide, which is not present in the flash smelting process, but used as an SO{sub 2} absorbent in the combustion processes. However, also these investigations may give some hints about the sulphation

Thermal decomposition of uranyl sulphate hydrate

International Nuclear Information System (INIS)

Sato, T.; Ozawa, F.; Ikoma, S.

1980-01-01

The thermal decomposition of uranyl sulphate hydrate (UO 2 SO 4 .3H 2 O) has been investigated by thermogravimetry, differential thermal analysis, X-ray diffraction and infrared spectrophotometry. As a result, it is concluded that uranyl sulphate hydrate decomposes thermally: UO 2 SO 4 .3H 2 O → UO 2 SO 4 .xH 2 O(2.5 = 2 SO 4 . 2H 2 O → UO 2 SO 4 .H 2 O → UO 2 SO 4 → α-UO 2 SO 4 → β-UO 2 SO 4 → U 3 O 8 . (author)

Thermometric titration of sulphate.

Science.gov (United States)

Williams, M B; Janata, J

1970-06-01

Direct thermometric titration of sulphate with a solution of barium perchlorate is proposed. The stoichiometry of the titration is shown to be critically dependent on the concentration of ethanol in the titration medium. The titration is rapid and suffers from only a few interferences.

In vitro studies on magnesium uptake by rumen epithelium using magnesium-28

International Nuclear Information System (INIS)

Martens, H.; Harmeyer, J.; Breves, G.

1976-01-01

Magnesium-28 transfer across the rumen epithelium has been studied using surviving epithelia in an in vitro system. Net absorption of magnesium in the direction from lumen to blood could be observed as the result of two opposite unidirectional fluxes of different magnitude. Net uptake of magnesium occurred against an electrical potential difference, and was associated with the presence of an unaltered transmural potential difference in the mucosal tissue. Both the net transfer of magnesium and the transmural potential difference decreased during two hours of incubation. Unidirectional fluxes of magnesium and net efflux from the lumen were markedly reduced although not completely inhibited by the addition of ouabain (10 -4 mol/l). The findings suggest that the mechanism of magnesium absorption by the rumen epithelium can be considered as an active transport process, and that the rumen is the main area of magnesium absorption in the living animal. (author)

Sulphate, more than a nutrient, protects the microalga Chlamydomonas moewusii from cadmium toxicity

Energy Technology Data Exchange (ETDEWEB)

Mera, Roi; Torres, Enrique, E-mail: torres@udc.es; Abalde, Julio

2014-03-01

Highlights: • Sulphate effect on cadmium toxicity in the microalga Chlamydomonas moewusii Gerloff. • Cadmium increases the sulphur requirements in Chlamydomonas moewusii. • Kinetic coefficients for sulphate utilization and cadmium effect on them. • Sulphate and cadmium influence on the biosynthesis of low-molecular mass thiols. • Cadmium toxicity reduction by sulphate due to higher biosynthesis of thiols. - Abstract: Sulphur is an essential macroelement that plays important roles in living organisms. The thiol rich sulphur compounds, such as cysteine, γ-Glu–Cys, glutathione and phytochelatins participate in the tolerance mechanisms against cadmium toxicity. Plants, algae, yeasts and most prokaryotes cover their demand for reduced sulphur by reduction of inorganic sulphate. The aim of this study was to investigate, using a bifactorial experimental design, the effect of different sulphate concentrations in the nutrient solution on cadmium toxicity in the freshwater microalga Chlamydomonas moewusii. Cell growth, kinetic parameters of sulphate utilization and intracellular concentrations of low-molecular mass thiol compounds were determined. A mathematical model to describe the growth of this microalga based on the effects of sulphate and cadmium was obtained. An ANOVA revealed an interaction between them, 16% of the effect sizes was explained by this interaction. A higher amount of sulphate in the culture medium allowed a higher cadmium tolerance due to an increase in the thiol compound biosynthesis. The amount of low-molecular mass thiol compounds, mainly phytochelatins, synthesized by this microalga was significantly dependent on the sulphate and cadmium concentrations; the higher phytochelatin content was obtained in cultures with 4 mg Cd/L and 1 mM sulphate. The maximum EC{sub 50} value (based on nominal cadmium concentration) reached for this microalga was 4.46 ± 0.42 mg Cd/L when the sulphate concentration added to the culture medium was also 1 m

Relationship between sulphate and sulphur dioxide in the air

Energy Technology Data Exchange (ETDEWEB)

Fugas, M; Gentilizza, M

1978-01-01

The relationship between the sulphate in suspended particulates and sulphur dioxide in the air was studied in various urban and industrial areas. The relationship is best described by the equation y = ax/sup b/, where y is the percentage of the sulphate S in the total S (sulphate and sulphur dioxide) and x is the concentration of the total S in the air. The regression coefficients a and b seem to be characteristics of the area. In urban areas studied so far a was between 316 and 378 and b between -0.74 and -0.83. In industrial areas polluted by dust which contains elevated concentrations of metals a was between 91 and 107 and b between -0.35 and -0.49. In the area polluted by cement dust there was practically no correlation between the sulphate S (%) and the total S, but a relatively high correlation between absolute amounts of the sulphate S and the total S. The relations indicate that the limitation of SO/sub 2/ conversion is influenced by aerosol composition. Aerosols containing certain metals may promote the conversion by a catalytic effect while alkaline substances by increasing the pH. Whether this can only happen in the plume or in the air as well remains to be clarified.

Magnesium, magnesium alloys, and magnesium composites

National Research Council Canada - National Science Library

Gupta, M; Sharon, Nai Mui Ling

2011-01-01

... of science, characteristics, and applications. It emphasizes the properties of magnesium-based composites and the effects of different types of reinforcements, from micron length to nanometer scale, on the properties of the resulting composites...

Poly(Butylene Terephthalate Based Composites Containing Alumina Whiskers: Influence of Filler Functionalization on Dielectric Properties

Directory of Open Access Journals (Sweden)

Pietro Russo

2014-01-01

Full Text Available Poly(butylene terephthalate (PBT is one of the most widely used semicrystalline thermoplastics polyester because of its superior thermal and mechanical properties, high dimensional stability and excellent processability. In this research PBT-based nanocomposites, including various amounts (up to 10 wt% of commercial alumina whiskers, have been prepared by using a Brabender internal chamber mixer and analysed in terms of morphological features and dielectric properties. Specific attention has been focused on the effect of the filler functionalization considering 3-glycidoxy propylmethoxysilane (GPS or 3-methacryloxypropyltrimethoxysilane (MPS as coupling agents. Tests, performed on compounds filled with neat and functionalized alumina whiskers, show a clear dependence of relative dielectric permittivity εr, invariance of dissipation factor (tgδ, and a sensible increase of volume electrical resistivity (ρv with the filler’s content and are encouraging for a future introduction of such composites in many electrical applications.

Growth of single-crystal W whiskers during humid H2/N2 reduction of Ni, Fe-Ni, and Co-Ni doped tungsten oxide

International Nuclear Information System (INIS)

Wang Shiliang; He Yuehui; Zou Jou; Wang Yong; Huang Han

2009-01-01

Numbers of W whiskers were obtained by reducing Ni, Ni-Fe, and Ni-Co doped tungsten oxide in a mixed atmosphere of humid H 2 and N 2 . The phases and morphologies of the reduction products were characterized by XRD and SEM. Intensive TEM and EDS analyses showed that the obtained whiskers were W single crystals which typical have alloyed particles (Ni-W, Fe-Ni, or Co-Ni-W) at the growth tips. The formed W whiskers were presumed to be induced by the alloyed particles. Our experimental results revealed that, during the reduction process of tungsten oxide, the pre-reduced Ni, Fe-Ni, or Co-Ni particles not only served as nucleation aids for the initial growth of W phase from W oxide but also played the roles of catalysts during the reductive decomposition of gaseous WO 2 (OH) 2 .

Bone mineral response to ammonium sulphate offered as a lick supplement in beef calves

Directory of Open Access Journals (Sweden)

L.E. Motsei

2006-06-01

Full Text Available Sixteen Bonsmara calves (4 males, 12 females between 10 and 18 months of age were blocked according to age and sex and randomly assigned to 2 groups. They were offered licks containing bone meal and salt (50:50 ratio (control and bone meal and ammonium sulphate (NH4SO4 at 1.25, 2.5, 5, 10, 15, and 18 % (treatment to evaluate the effects of dietary anions on bone phosphate (P concentration. Bone P concentration was significantly (P<0.05 higher in the NH4SO4 group compared with the control group, indicating that NH4SO4 was able to increase the P content of bone at each of the 6 concentrations used in the lick relative to the control animals, thereby improving the P status of the animals. Ammonium sulphate at 15% and 18% in the lick also significantly (P <0.05 increased bone P compared with the lower concentrations of NH4SO4. Bone calcium (Ca fluctuated as a result of the acidogenic lick. There was absorption of Ca when P was being resorbed and resorption of Ca when P was being absorbed into and out of bone. Bone Ca:P ratio ranged from 3.2 to 6.4 among the control group and 1.6 to 4.3 among the treatment group. Animals receiving the acidogenic lick had a higher percentage ash compared to the control group for most of the experimental period. Bone magnesium (Mg fluctuated in response to the acidogenic lick, and it was difficult to show a relationship between bone Mg and Ca or P. The overall mean cortical bone thickness was significantly (P < 0.05 greater in treatment (1.60 mm compared with control (1.43 mm calves and this was also true at sampling periods 2, 4, 5 and 6. Bone thickness followed bone P and not bone Ca. Results from this research indicate that the addition of ammonium sulphate to a lick had a beneficial effect in improving the P status by increasing bone P and improving the mineral status of bone by increasing the thickness of cortical bone and percentage ash.

Feasibility of lead removal from industrial effluents by sulphate reducing bacteria

International Nuclear Information System (INIS)

Nunez, L. A.; Diez, M.; Rodriguez, F. J.

2009-01-01

Battery manufacturing wastewater contains high concentration of sulphate and lead at low pH values. Biogical treatment by anaerobic reduction of sulphate to sulphite, with organic matter as electron donor, increases alkalinity and allow precipitating lead as sulphide. the type of organic matter, COD/SO 4 ratio and lead concentration over sulphate reduction rate are investigated in this work. (Author)

Differential responses of freshwater wetland soils to sulphate pollution

NARCIS (Netherlands)

Lamers, L.P.M.; Dolle, ten G.E.; Berg, van den S.T.G.; Delft, van S.P.J.; Roelofs, J.G.M.

2001-01-01

Sulphate (SO42-) reduction rates are generally low in freshwater wetlands and are regulated by the scarce availability of the ion. Increased concentrations of this electron acceptor due to sulphur (S) pollution of groundwater and surface water may, however, lead to high sulphate reduction rates now

Sulphated glycosaminoglycans and proteoglycans in the developing vertebral column of juvenile Atlantic salmon (Salmo salar)

OpenAIRE

Hannesson, Kirsten O.; Ytteborg, Elisabeth; Takle, Harald; Enersen, Grethe; B?verfjord, Grete; Pedersen, Mona E.

2015-01-01

In the present study, the distribution of sulphated glycosaminoglycans (GAGs) in the developing vertebral column of Atlantic salmon (Salmo salar) at 700, 900, 1100 and 1400?d? was examined by light microscopy. The mineralization pattern was outlined by Alizarin red S and soft structures by Alcian blue. The temporal and spatial distribution patterns of different types of GAGs: chondroitin-4-sulphate/dermatan sulphate, chondroitin-6-sulphate, chondroitin-0-sulphate and keratan sulphate were add...

Magnesium Hydroxide

Science.gov (United States)

Magnesium hydroxide is used on a short-term basis to treat constipation.This medication is sometimes prescribed ... Magnesium hydroxide come as a tablet and liquid to take by mouth. It usually is taken as ...

Optogenetic probing of nerve and muscle function after facial nerve lesion in the mouse whisker system

Science.gov (United States)

Bandi, Akhil; Vajtay, Thomas J.; Upadhyay, Aman; Yiantsos, S. Olga; Lee, Christian R.; Margolis, David J.

2018-02-01

Optogenetic modulation of neural circuits has opened new avenues into neuroscience research, allowing the control of cellular activity of genetically specified cell types. Optogenetics is still underdeveloped in the peripheral nervous system, yet there are many applications related to sensorimotor function, pain and nerve injury that would be of great benefit. We recently established a method for non-invasive, transdermal optogenetic stimulation of the facial muscles that control whisker movements in mice (Park et al., 2016, eLife, e14140)1. Here we present results comparing the effects of optogenetic stimulation of whisker movements in mice that express channelrhodopsin-2 (ChR2) selectively in either the facial motor nerve (ChAT-ChR2 mice) or muscle (Emx1-ChR2 or ACTA1-ChR2 mice). We tracked changes in nerve and muscle function before and up to 14 days after nerve transection. Optogenetic 460 nm transdermal stimulation of the distal cut nerve showed that nerve degeneration progresses rapidly over 24 hours. In contrast, the whisker movements evoked by optogenetic muscle stimulation were up-regulated after denervation, including increased maximum protraction amplitude, increased sensitivity to low-intensity stimuli, and more sustained muscle contractions (reduced adaptation). Our results indicate that peripheral optogenetic stimulation is a promising technique for probing the timecourse of functional changes of both nerve and muscle, and holds potential for restoring movement after paralysis induced by nerve damage or motoneuron degeneration.

Research Progress in Plasma arc welding of Magnesium Alloys and Magnesium Matrix Composites

Science.gov (United States)

Hui, Li; Yang, Zou; Yongbo, Li; Lei, Jiao; Ruijun, Hou

2017-11-01

Magnesium alloys and magnesium matrix composites by means of its excellent performance have wide application prospect in electronics, automotive, biotechnology, aerospace field, and welding technology has become a key of restricting its application. This paper describes the welding characteristics of magnesium, the obvious advantages in the application and the domestic and foreign research advance technology of plasma arc welding of magnesium, and summarizes the existing problems and development trends of plasma arc welding technology of magnesium.

Microwave assisted synthesis of nano sized sulphate doped hydroxyapatite

International Nuclear Information System (INIS)

Alshemary, Ammar Z.; Goh, Yi-Fan; Akram, Muhammad; Razali, Ili Rabihah; Abdul Kadir, Mohammed Rafiq; Hussain, Rafaqat

2013-01-01

Highlights: ► Phase pure nano-sized sulphur doped hydroxyapatite has been synthesized. ► TEM analysis confirmed formation of needle shaped structure. ► Lattice parameters and cell volume increased with increase in sulphate doping. ► Crystallite size decreased as sulphate content inside the structure increased. ► Degree of crystallinity decreased with increase in sulphate substitution. - Abstract: Inorganic sulphate is required by all mammalian cells to function properly, it is the fourth most abundant anion in the human plasma. Sulphate ions are the major source of sulphur which is considered an important element for sustenance of life as it is present in the essential amino and is required by cells to function properly. In this study we have successfully substituted sulphate ions (SO 4 2− ) into hydroxyapatite (Ca 10 (PO 4 ) 6−x (SO 4 ) x (OH) 2−x ) lattice via ion exchange process with phosphate group. Concentration of SO 4 2− ions was varied between X = 0.05–0.5, using (Ca (NO 3 ) 2 ·4H 2 O), ((NH 4 ) 2 HPO 4 ) and (Na 2 SO 4 ) as starting materials. X-ray diffraction (XRD), Fourier transform IR spectroscopy (FTIR), showed that the substitution of SO 4 2− ions into the lattice resulted in peak broadening and reduced peak height due to the amorphous nature and reduced crystallinity of the resulting HA powder. Transmission electron microscopy (TEM) and field emission electron microscopy (FESEM) analysis confirmed the formation of needle shaped particles of 41 nm size with homogenous and uniform distribution of element within the HA structure

Sulphate removal from uraniferous liquors

International Nuclear Information System (INIS)

Berger, B.

1983-01-01

A process for the recovery of uranium from liquor resulting from the attack of sulphur containing uraniferous ores by an alkaline solution of sodium carbonate and/or sodium bicarbonate is claimed. An ion exchange resin is used to separate the uranium from the solution of sodium carbonate and/or bicarbonate and sodium sulphate. The ion exchange resin is then eluted with a solution of ammonium carbonate and/or bicarbonate to provide an eluate containing ammonium uranyl tricarbonate, ammonium carbonate and/or bicarbonate and ammonium sulphate. The eluate is heated to boiling to convert the ammonium uranyl tricarbonate to ammonium uranate and/or diuranate. Ammonia, carbon dioxide and water vapor are released. The precipitated ammonium uranate and/or diuranate is separated from the remaining liquor and calcined to give uranium trioxide

Serum and urinary oestrone sulphate in pregnancy and delivery measured by a direct radioimmunoassay

International Nuclear Information System (INIS)

Honjo, Hideo; Kitawaki, Jo; Itoh, Masafumi; Yasuda, Jinsuke; Yamamoto, Takara; Yamamoto, Takao; Okada, Hiroji; Ohkubo, Tadashi; Nambara, Toshio

1986-01-01

Serum and urinary levels of oestrone sulphate in pregnancy and delivery were measured by a direct radioimmunoassay without hydrolysis. the serum and urinary oestrone sulphate increased as pregnancy progressed. the mean level of serum oestrone sulphate increased to the highest peak of 494 pmol/ml at the 35th gestational week and then decreased. The mean level of urinary oestrone sulphate increased to the highest peak of 1.28 μmol/l at the 34th gestational week and the decreased. At vaginal deliveries, the mean level of maternal peripheral serum oestrone sulphate increased hourly at as high a level as 979 pmol/ml. The mean serum level of oestrone sulphate was 204 pmol/ml in the umbilical artery and 145 pmol/ml in the umbilical vein. At Caesarean section, on the other hand, the maternal peripheral serum level of oestrone sulphate averaged 362 pmol/ml. The mean serum levels of oestrone sulphate wre 90.7 pmol/ml and 171 pmol/ml in the umbilical artery and umbilical vein, respectively. These results suggest a maternal origin of oestrone sulphate in pregnancy, with fluctuations in the levels being of interest in relation to labour pain. (author)

FOCUS ON MAGNESIUM BASED DRUGS

Directory of Open Access Journals (Sweden)

I. I. Esenova

2011-01-01

Full Text Available Magnesium deficiency in the organism is one of the most common human deficiency states. The prevalence of magnesium deficiency is about 15%, and suboptimal magnesium level is observed more than in 30% of people in the general population. Clinical signs of hypomagnesaemia are observed in 40% of patients in general care hospitals, in 70% of patients - in intensive care units, and magnesium deficiency occurs in 90% of patients with acute coronary syndrome. Magnesium metabolic disorders in the organism accelerate significantly development of complications of coronary heart disease, hypertension, type 2 diabetes, asthma and a number of neurological and psychiatric diseases. The value of this macro in the body is well studied, and its daily need is identified depending on age and sex. It is known that magnesium intake with the food does not cover an organism need. It is a rationale for preventive and therapeutic use of magnesium based drugs in various diseases. Organic salts of magnesium are recommended for these purposes. Magnesium metabolic disorders, approaches to pharmacotherapeutic correction of magnesium deficiency, advantages of magnesium salts of orotic acid are reviewed.

To evaluate the efficacy of intrathecal magnesium sulphate for hysterectomy under subarachnoid block with bupivacaine and fentanyl: A prospective randomized double blind clinical trial

Directory of Open Access Journals (Sweden)

Mridu Paban Nath

2012-01-01

Full Text Available Background: Intrathecal magnesium has been found to prolong the duration of analgesia in various surgical procedures like lower limb surgeries and as adjuncts to general anesthesia for pain management. The present study was designed to examine whether addition of intrathecal magnesium sulfate would enhance the analgesic efficacy of intrathecal bupivacaine and fentanyl in patients undergoing total abdominal hysterectomy. Methods: After taking informed consent, 60 patients were randomised into two groups with 30 patients. Group "S" received 2.5 mL (12.5 mg of hyperbaric bupivacaine + 0.5 mL (25 mcg of fentanyl + 0.5 mL of normal saline and Group "M" received 2.5 mL (12.5 mg of hyperbaric bupivacaine + 0.5 mL (25 mcg of fentanyl + 0.5 mL (100 mg of magnesium sulfate. Onset of sensory, motor block and duration of analgesia was noted. Results: Demographic profile and duration of surgery were comparable (P>0.5. Time of onset of sensory and motor blockade was delayed in Group M compared with Group S, and this was statistically significant. A statistically significant longer duration of analgesia was observed in Group M compared with the control Group S. However, the recovery of motor blockade was found to be statistically insignificant in both the groups. The hemodynamic parameters were comparable in the perioperative period (P>0.05. The incidence of side-effects in both the groups were also comparable (P>0.05. Conclusion: The addition of 100 mg intrathecal magnesium led to prolonged duration of analgesia significantly without increasing the incidence of side-effects. Also, there was a significant delay in the onset of both sensory and motor blockade.

Process development for elemental recovery from PGM tailings by thermochemical treatment: Preliminary major element extraction studies using ammonium sulphate as extracting agent.

Science.gov (United States)

Mohamed, Sameera; van der Merwe, Elizabet M; Altermann, Wladyslaw; Doucet, Frédéric J

2016-04-01

Mine tailings can represent untapped secondary resources of non-ferrous, ferrous, precious, rare and trace metals. Continuous research is conducted to identify opportunities for the utilisation of these materials. This preliminary study investigated the possibility of extracting major elements from South African tailings associated with the mining of Platinum Group Metals (PGM) at the Two Rivers mine operations. These PGM tailings typically contain four major elements (11% Al2O3; 12% MgO; 22% Fe2O3; 34% Cr2O3), with lesser amounts of SiO2 (18%) and CaO (2%). Extraction was achieved via thermochemical treatment followed by aqueous dissolution, as an alternative to conventional hydrometallurgical processes. The thermochemical treatment step used ammonium sulphate, a widely available, low-cost, recyclable chemical agent. Quantification of the efficiency of the thermochemical process required the development and optimisation of the dissolution technique. Dissolution in water promoted the formation of secondary iron precipitates, which could be prevented by leaching thermochemically-treated tailings in 0.6M HNO3 solution. The best extraction efficiencies were achieved for aluminium (ca. 60%) and calcium (ca. 80%). 35% iron and 32% silicon were also extracted, alongside chromium (27%) and magnesium (25%). Thermochemical treatment using ammonium sulphate may therefore represent a promising technology for extracting valuable elements from PGM tailings, which could be subsequently converted to value-added products. However, it is not element-selective, and major elements were found to compete with the reagent to form water-soluble sulphate-metal species. Further development of this integrated process, which aims at achieving the full potential of utilisation of PGM tailings, is currently underway. Copyright © 2016 Elsevier Ltd. All rights reserved.

Magnesium Oxide

Science.gov (United States)

Magnesium is an element your body needs to function normally. Magnesium oxide may be used for different reasons. Some people use it as ... one to four times daily depending on which brand is used and what condition you have. Follow ...

The hypobranchial mucin of the whelk Buccinum undatum L. The polysaccharide sulphate component.

Science.gov (United States)

Hunt, S; Jevons, F R

1966-02-01

1. A polysaccharide sulphate has been isolated from the hypobranchial mucin of the whelk Buccinum undatum. 2. The molecular weight of this polysaccharide, which is a glucan carrying one ester sulphate group per monosaccharide residue, is 1.7x10(5). 3. Some investigations bearing on the location of the ester sulphate groups are reported. 4. The viscosity of the whole mucin has been shown to depend mainly on the glucan sulphate.

Microwave assisted synthesis of nano sized sulphate doped hydroxyapatite

Energy Technology Data Exchange (ETDEWEB)

Alshemary, Ammar Z.; Goh, Yi-Fan; Akram, Muhammad; Razali, Ili Rabihah [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor Darul Ta’zim (Malaysia); Abdul Kadir, Mohammed Rafiq [Medical Implant Technology Group, Faculty of Biomedical Engineering and Health Science, Universiti Teknologi Malaysia,81310 UTM Skudai, Johor Darul Ta’zim (Malaysia); Hussain, Rafaqat, E-mail: rafaqat@kimia.fs.utm.my [Ibnu Sina Institute for Fundamental Science Studies, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor DarulTa’zim (Malaysia)

2013-06-01

Highlights: ► Phase pure nano-sized sulphur doped hydroxyapatite has been synthesized. ► TEM analysis confirmed formation of needle shaped structure. ► Lattice parameters and cell volume increased with increase in sulphate doping. ► Crystallite size decreased as sulphate content inside the structure increased. ► Degree of crystallinity decreased with increase in sulphate substitution. - Abstract: Inorganic sulphate is required by all mammalian cells to function properly, it is the fourth most abundant anion in the human plasma. Sulphate ions are the major source of sulphur which is considered an important element for sustenance of life as it is present in the essential amino and is required by cells to function properly. In this study we have successfully substituted sulphate ions (SO{sub 4}{sup 2−}) into hydroxyapatite (Ca{sub 10}(PO{sub 4}){sub 6−x}(SO{sub 4}){sub x}(OH){sub 2−x}) lattice via ion exchange process with phosphate group. Concentration of SO{sub 4}{sup 2−} ions was varied between X = 0.05–0.5, using (Ca (NO{sub 3}){sub 2}·4H{sub 2}O), ((NH{sub 4}){sub 2}HPO{sub 4}) and (Na{sub 2}SO{sub 4}) as starting materials. X-ray diffraction (XRD), Fourier transform IR spectroscopy (FTIR), showed that the substitution of SO{sub 4}{sup 2−} ions into the lattice resulted in peak broadening and reduced peak height due to the amorphous nature and reduced crystallinity of the resulting HA powder. Transmission electron microscopy (TEM) and field emission electron microscopy (FESEM) analysis confirmed the formation of needle shaped particles of 41 nm size with homogenous and uniform distribution of element within the HA structure.

Characteristics and antioxidant of Ulva intestinalis sulphated polysaccharides extracted with different solvents.

Science.gov (United States)

Peasura, Napassorn; Laohakunjit, Natta; Kerdchoechuen, Orapin; Wanlapa, Sorada

2015-11-01

Ulva intestinalis, a tubular green seaweed, is a rich source of nutrient, especially sulphated polysaccharides. Sulphated polysaccharides from U. intestinalis were extracted with distilled water, 0.1N HCl, and 0.1N NaOH at 80°C for 1, 3, 6, 12, and 24h to study the effect of the extraction solvent and time on their chemical composition and antioxidant activity. Different types of solvents and extraction time had a significant influence on the chemical characteristics and antioxidant activity (pMonosaccharide composition and FT-IR spectra analyses revealed that sulphated polysaccharides from all solvent extractions have a typical sugar backbone (glucose, rhamnose, and sulphate attached at C-2 or C-3 of rhamnose). Sulphated polysaccharides extracted with acid exhibited greater antioxidant activity than did those extracted with distilled water and alkali. The results indicated that solvent extraction could be an efficacious method for enhancing antioxidant activity by distinct molecular weight and chemical characteristic of sulphated polysaccharides. Copyright © 2015 Elsevier B.V. All rights reserved.

Quantitation and identification of methanogens and sulphate reducers in Olkiluoto groundwater

International Nuclear Information System (INIS)

Bomberg, M.; Nyyssoenen, M.; Itaevaara, M.

2010-08-01

The GEOFUNC Project focuses on the microbiology connected to safety and risk assessment of the final disposal of high radioactive nuclear waste. Methanogenic archaea and sulphate reducing bacteria are significant groups of microorganisms in anaerobic environments, and are of crucial concern for the safe long term storage of nuclear waste in deep bedrock. The sulphate reducing bacteria are able to produce sulphide which may cause corrosion of the copper in the radioactive waste storage capsules. Methanogens, on the other hand, may produce quantities of methane from various organic carbon compounds, CO 2 and H 2 . Methane may both serve as carbon source for methanotrophic microbial groups, and may also cause mobilization of radionuclides, as a result of gas discharge through fractures in the bedrock. The transition zones between the sulphate rich and methane rich waters are locations for microbial processes where the methane may serve as carbon source for sulphate reducing bacteria, which in turn would produce corrosive sulphides. It has been estimated that only 1-10 % of all the microorganisms present in the environment can be isolated and cultivated. Uncultured microorganisms can be identified and their numbers in the environment quantified by identification of specific marker genes that are essential for their functions by use of molecular methods. Methanogens, for example, can be identified by their genes for methyl coenzyme M reductase (mcrA), which is an essential enzyme involved in the production of methane. The mcrA is specifically present only in methanogenic archaea. Sulphate reducers are identified by their dissimilatory sulphite reductase genes (dsrB), which are present in and essential for all microorganisms performing dissimilatory sulphate reducing. In the GEOFUNC project, a quantitative PCR method (qPCR) was developed for the detection of methanogens and sulphate reducers. This method is based on specific quantitative detection of marker genes

Magnesium motorcycle applications

International Nuclear Information System (INIS)

Jianyong Cao; Zonghe Zhang; Dongxia Xiang; Jun Wang

2005-01-01

Magnesium, the lightest engineering structural metal, has been comprehensively used in castings of aviation and aerospace, communication and transportation, and IT components. This paper introduced the history, advantages and difficulties of magnesium castings for motorcycle application as well as its application state in China. It also indicated the production situation of magnesium motorcycle components in CQMST and difficulties need to overcome for further development. (orig.)

Magnesium sulfate reduces formalin-induced orofacial pain in rats with normal magnesium serum levels.

Science.gov (United States)

Srebro, Dragana P; Vučković, Sonja M; Dožić, Ivan S; Dožić, Branko S; Savić Vujović, Katarina R; Milovanović, Aleksandar P; Karadžić, Branislav V; Prostran, Milica Š

2018-02-01

In humans, orofacial pain has a high prevalence and is often difficult to treat. Magnesium is an essential element in biological a system which controls the activity of many ion channels, neurotransmitters and enzymes. Magnesium produces an antinociceptive effect in neuropathic pain, while in inflammatory pain results are not consistent. We examined the effects of magnesium sulfate using the rat orofacial formalin test, a model of trigeminal pain. Male Wistar rats were injected with 1.5% formalin into the perinasal area, and the total time spent in pain-related behavior (face rubbing) was quantified. We also spectrophotometrically determined the concentration of magnesium and creatine kinase activity in blood serum. Magnesium sulfate administered subcutaneously (0.005-45mg/kg) produced significant antinociception in the second phase of the orofacial formalin test in rats at physiological serum concentration of magnesium. The effect was not dose-dependent. The maximum antinociceptive effect of magnesium sulfate was about 50% and was achieved at doses of 15 and 45mg/kg. Magnesium did not affect increase the levels of serum creatine kinase activity. Preemptive systemic administration of magnesium sulfate as the only drug can be used to prevent inflammatory pain in the orofacial region. Its analgesic effect is not associated with magnesium deficiency. Copyright © 2017 Institute of Pharmacology, Polish Academy of Sciences. Published by Elsevier B.V. All rights reserved.

Function of magnesium aluminate hydrate and magnesium nitrate ...

Indian Academy of Sciences (India)

MgO was added both as spinel (MgAl2O4) forming precursor i.e. magnesium aluminate hydrate, and magnesium nitrate. Sintering investigations were conducted in the temperature range 1500–1600°C with 2 h soaking. Structural study of sintered pellets was carried out by extensive XRD analysis. Scanning electron mode ...

Dose-response testing with nickel sulphate using the TRUE test in nickel-sensitive individuals. Multiple nickel sulphate patch-test reactions do not cause an 'angry back'

DEFF Research Database (Denmark)

Andersen, Klaus Ejner; Lidén, C; Hansen, J

1993-01-01

The aim of this study was to employ the TRUE test assay to confirm the presence or absence of the 'angry back' phenomenon, i.e. that a strong positive patch-test reaction heightens adjacent patch-test response. In addition, we wished to establish the dose-response relationship for nickel sulphate...... back' phenomenon was not apparent in this study, as the spill-over effect was not statistically significant. Strong reactions to high concentrations of nickel sulphate did not enhance the response to adjacent lower concentrations of nickel sulphate....

Magnesium compounds

Science.gov (United States)

Kramer, D.A.

2007-01-01

Seawater and natural brines accounted for about 52 percent of U.S. magnesium compounds production in 2006. Dead-burned magnesia was produced by Martin Marietta Magnesia Specialties from well brines in Michigan. Caustic-calcined magnesia was recovered from sea-water by Premier Chemicals in Florida; from well brines in Michigan by Martin Marietta and Rohm and Haas; and from magnesite in Nevada by Premier Chemicals. Intrepid Potash-Wendover and Great Salt Lake Minerals recovered magnesium chloride brines from the Great Salt Lake in Utah. Magnesium hydroxide was produced from brucite by Applied Chemical Magnesias in Texas, from seawater by SPI Pharma in Delaware and Premier Chemicals in Florida, and by Martin Marietta and Rohm and Haas from their operations mentioned above. About 59 percent of the magnesium compounds consumed in the United States was used for refractories that are used mainly to line steelmaking furnaces. The remaining 41 percent was consumed in agricultural, chemical, construction, environmental and industrial applications.

The determination of lead, zinc, and magnesium in dolomite and its benefication products by use of x-ray-fluorescence spectrometry

International Nuclear Information System (INIS)

Jacobs, J.J.

1985-01-01

An investigation was undertaken on the development of fast, simple, and accurate methods of analysis for lead and zinc in tailings and middlings from dolomite, and for lead, zinc, and magnesium in concentrates obtained from dolomite. A pressed-powder technique and X-ray-fluorescence spectrometry (XRFS) were used. Good agreement was found between the XRFS values for lead and zinc in low concentrations and the values obtained by other techniques of analysis when the calibration for the XRFS method was effected by the use of synthetic standards comprising lead and zinc oxides in a dolomite matrix. For high concentrations of the analytes, all the oxides and sulphides of lead and zinc in the samples had to be converted to the sulphate form, and a matrix correction had to be applied to the assigned values of the oxide calibration standards. The lower limits of detection for lead, zinc, and magnesium were 0,004, 0,003, and 0,18 per cent respectively. The recommended methods are detailed in two appendices

Corrosion Performance of Inconel 625 in High Sulphate Content

Science.gov (United States)

Ismail, Azzura

2016-05-01

Inconel 625 (UNS N06625) is a type of nickel-chromium-molybdenum alloy with excellent corrosion resistance in a wide range of corrosive media, being especially resistant to pitting and crevice corrosion. However, in aggressive environment, Inconel 625 will suffer corrosion attack like other metals. This research compared the corrosion performance of Inconel 625 when exposed to higher sulphate content compared to real seawater. The results reveal that Inconel 625 is excellent in resist the corrosion attack in seawater. However, at increasing temperature, the corrosion resistance of this metal decrease. The performance is same in seawater with high sulphate content at increasing temperature. It can be concluded that sulphate promote perforation on Inconel 625 and become aggressive agents that accelerate the corrosion attack.

Innovative Vacuum Distillation for Magnesium Recycling

Science.gov (United States)

Zhu, Tianbai; Li, Naiyi; Mei, Xiaoming; Yu, Alfred; Shang, Shixiang

Magnesium recycling now becomes a very important subject as magnesium consumption increases fast around the world. All commonly used magnesium die-casting alloys can be recycled and recovered to the primary metal quality. The recycled materials may be comprised of biscuits, sprues, runners, flash, overflows, dross, sludge, scrap parts, and old parts that are returned from service, An innovative magnesium recycle method, vacuum distillation, is developed and proved out to be able to recycle magnesium scraps, especially machining chips, oily magnesium, smelting sludge, dross or the mixture. With this process at a specific temperature and environment condition, magnesium in scraps can be gasified and then solidified to become crystal magnesium crown. This `recycled' magnesium crown is collected and used as the raw material of magnesium alloys. The experimental results show the vacuum distillation is a feasible and plausible method to recycle magnesium. Further, the cost analysis will be addressed in this paper.

Combined treatment with progesterone and magnesium sulfate positively affects traumatic brain injury in immature rats.

Science.gov (United States)

Uysal, Nazan; Baykara, Basak; Kiray, Muge; Cetin, Ferihan; Aksu, Ilkay; Dayi, Ayfer; Gurpinar, Tugba; Ozdemir, Durgul; Arda, M Nuri

2013-01-01

It is well known that head trauma results in damage in hippocampal and cortical areas of the brain and impairs cognitive functions. The aim of this study is to explore the neuroprotective effect of combination therapy with magnesium sulphate (MgSO4) and progesterone in the 7-days-old rat pups subjected to contusion injury. Progesterone (8 mg/kg) and MgSO4 (150 mg/kg) were injected intraperitoneally immediately after induction of traumatic brain injury. Half of groups were evaluated 24 hours later, the remaining animals 3 weeks after trauma or sham surgery. Anxiety levels were assessed with open field activity and elevated plus maze; learning and memory performance were evaluated with Morris Water maze in postnatal 27 days. Combined therapy with progesterone and magnesium sulfate significantly attenuated trauma-induced neuronal death, increased brain VEGF levels and improved spatial memory deficits that appear later in life. Brain VEGF levels were higher in rats that received combined therapy compared to rats that received either medication alone. Moreover, rats that received combined therapy had reduced hipocampus and prefrontal cortex apoptosis in the acute period. These results demonstrate that combination of drugs with different mechanisms of action may be preferred in the treatment of head trauma.

Magnesium Therapy in Pre-eclampsia Prolongs Analgesia Following Spinal Anaesthesia with Fentanyl and Bupivacaine: An Observational Study

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Tülay Özkan Seyhan

2014-06-01

Full Text Available Background: Magnesium has anti-nociceptive effects and potentiates opioid analgesia following its systemic and neuraxial administration. However, there is no study evaluating the effects of intravenous (IV magnesium sulphate (MgSO4 therapy on spinal anaesthesia characteristics in severely pre-eclamptic patients. Aims: The aim of this study was to compare spinal anaesthesia characteristics in severely pre-eclamptic parturients treated with MgSO4 and healthy preterm parturients undergoing caesarean section. Thus, our primary outcome was regarded as the time to first analgesic request following spinal anaesthesia. Study Design: Case-control Study. Methods: Following approval of Institutional Clinical Research Ethics Committee and informed consent of the patients, 44 parturients undergoing caesarean section with spinal anaesthesia were enrolled in the study in two groups: Healthy preterm parturients (Group C and severely pre-eclamptic parturients with IV MgSO4 therapy (Group Mg. Following blood and cerebrospinal fluid (CSF sampling, spinal anaesthesia was induced with 9 mg hyperbaric bupivacaine and 20 µg fentanyl. Serum and CSF magnesium levels, onset of sensory block at T4 level, highest sensory block level, motor block characteristics, time to first analgesic request, maternal haemodynamics as well as side effects were evaluated. Results: Blood and CSF magnesium levels were higher in Group Mg. Sensory block onset at T4 were 257.1±77.5 and 194.5±80.1 sec in Group C and Mg respectively (p=0.015. Time to first postoperative analgesic request was significantly prolonged in Group Mg than in Group C (246.1±52.8 and 137.4±30.5 min, respectively, p<0.001; with a mean difference of 108.6 min and 95% CI between 81.6 and 135.7. Side effects were similar in both groups. Group C required significantly more fluids. Conclusion: Treatment with IV MgSO4 in severe pre-eclamptic parturients significantly prolonged the time to first analgesic request compared

Study of the sulphate expansion phenomenon in concrete: behaviour of the cemented radioactive wastes containing sulphate

International Nuclear Information System (INIS)

Li, Guanshu

1994-01-01

Sulphate attack is one of the major degradation processes of concrete. It is especially important in storing cemented radioactive wastes containing sulphate. In this thesis, we have thoroughly investigated the degradation mechanisms of cemented radioactive wastes by sulphate. The CaO-Al 2 O 3 -SO 3 -H 2 O systems with and without alkalis are studied. For the system without alkalis, experimental results show that it is the formation of a secondary ettringite under external water supply by steric effect that causes the expansion. For the system with alkalis, the ettringite does not appear while a new mineral called 'U', a sodium-substituted AFm phase is detected. This phase is shown to be responsible for the expansion and destruction of the specimens. The conditions for the formation, the product of solubility and many means of its synthesis are discussed, and a complete list of the inter-reticular distances file is given. The behaviour of the different types of cemented wastes containing sulphate are then studied with a special focus on the U phase on entity which was heretofore very little understood. The following three hypothetical mechanisms of sulphate expansion are proposed: the formation of the secondary U phase, the transformation of the U phase to the ettringite and the topochemical hydration of thenardite into mirabilite. Experiments on a simplified system have demonstrated clearly that the formation of the secondary U phase can induce enormous expansion by steric effect, this justifying the first assumption. Simulation by the mass and volume balances is carried out thereafter and enables us to estimate the expansion induced by the formation of the secondary U phase in the cemented wastes. The second assumption is also well verified by a series of leaching tests in different solutions on mixtures containing the U phase. On the basis of the analysis of the specimens under leaching, it has been assumed that the expansion is associated with the

INVESTIGATION OF MAGNESIUM ALLOYS MACHINABILITY

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Berat Barıs BULDUM

2013-01-01

Full Text Available Magnesium is the lightest structural metal. Magnesium alloys have a hexagonal lattice structure, which affects the fundamental properties of these alloys. Plastic deformation of the hexagonal lattice is more complicated than in cubic latticed metals like aluminum, copper and steel. Magnesium alloy developments have traditionally been driven by industry requirements for lightweight materials to operate under increasingly demanding conditions. Magnesium alloys have always been attractive to designers due to their low density, only two thirds that of aluminium and its alloys [1]. The element and its alloys take a big part of modern industry needs. Especially nowadays magnesium alloys are used in automotive and mechanical (trains and wagons manufacture, because of its lightness and other features. Magnesium and magnesium alloys are the easiest of all metals to machine, allowing machining operations at extremely high speed. All standard machining operations such as turning, drilling, milling, are commonly performed on magnesium parts.

The effect of water on the sulphation of limestone

Energy Technology Data Exchange (ETDEWEB)

Chunbo Wang; Lufei Jia; Yewen Tan; E.J. Anthony [North China Electric Power University, Baoding City (China). School of Energy and Power Engineering

2010-09-15

A series of tests was conducted in a thermogravimetric analyzer (TGA) to study the sulphation behaviour of limestone in the presence of water over the temperature range of 800-850{sup o}C. Four different Canadian limestones, all with a particle size range of 75-425 {mu}m, were sulphated using a synthetic flue gas with a composition of 15% CO{sub 2}, 3% O{sub 2}, 0% or 10% H{sub 2}O, 1750 ppm SO{sub 2} and the balance N{sub 2}. Water was shown to have a significant promotional effect on sulphation, especially in the diffusion-controlled stage. However, the effect of water during the kinetic-controlled stage appeared to be much less pronounced. Based on these results, it is proposed that the presence of water leads to the transient formation of Ca(OH){sub 2} as an intermediate, which in turn reacts with SO{sub 2} at a faster rate than CaO does. Alternatively stated, it appears that H{sub 2}O acts as catalyst for the sulphation reaction of CaO. 30 refs., 8 figs., 3 tabs.

The action of diazoxide and minoxidil sulphate on rat blood vessels: a comparison with cromakalim.

Science.gov (United States)

Newgreen, D. T.; Bray, K. M.; McHarg, A. D.; Weston, A. H.; Duty, S.; Brown, B. S.; Kay, P. B.; Edwards, G.; Longmore, J.; Southerton, J. S.

1990-01-01

1. The actions of diazoxide and minoxidil sulphate have been compared with those of cromakalim in rat aorta and portal vein. 2. Diazoxide and minoxidil sulphate hyperpolarized the rat portal vein in a similar manner to cromakalim. 3. Cromakalim, diazoxide and minoxidil sulphate increased 42K and 86Rb efflux from rat portal vein, although minoxidil sulphate had only a small effect on 86Rb efflux. 4. Cromakalim, diazoxide and minoxidil sulphate increased 42K efflux from rat aorta but only cromakalim and diazoxide increased 86Rb efflux from this tissue. 5. Glibenclamide inhibited the relaxant actions of cromakalim, diazoxide and minoxidil sulphate on rat aorta and the increase in 42K efflux produced by these agents in this tissue. 6. Diazoxide relaxed an 80 mM KCl-induced contraction of rat aorta, whilst cromakalim and minoxidil sulphate were without effect. 7. Cromakalim, diazoxide and minoxidil sulphate had no effect on cyclic AMP or cyclic GMP concentrations in rat aorta. 8. It is concluded that diazoxide and minoxidil sulphate like cromakalim exhibit K+ channel opening properties in vascular smooth muscle. Diazoxide exerts an additional inhibitory action not related to the production of cyclic AMP or cyclic GMP. The action of minoxidil sulphate may be primarily located at a K+ channel which is relatively impermeable to 86Rb. PMID:2167738

Fabrication of SiC Composites with Synergistic Toughening of Carbon Whisker and In Situ 3C-SiC Nanowire

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Zhang Yunlong

2016-01-01

Full Text Available The SiC composites with synergistic toughening of carbon whisker and in situ 3C-SiC nanowire have been fabricated by hot press sinter technology and annealed treatment technology. Effect of annealed time on the morphology of SiC nanowires and mechanical properties of the Cw/SiC composites was surveyed in detail. The appropriate annealed time improved mechanical properties of the Cw/SiC composites. The synergistic effect of carbon whisker and SiC nanowire can improve the fracture toughness for Cw/SiC composites. The vapor-liquid-solid growth (VLS mechanism was proposed. TEM photo showed that 3C-SiC nanowire can be obtained with preferential growth plane ({111}, which corresponded to interplanar spacing about 0.25 nm.

Magnesium compounds

Science.gov (United States)

Kramer, D.A.

2012-01-01

Seawater and natural brines accounted for about 57 percent of magnesium compounds produced in the United States in 2011. Dead-burned magnesia was produced by Martin Marietta Magnesia Specialties LLC from well brines in Michigan. Caustic-calcined magnesia was recovered from seawater by Premier Magnesia LLC in Florida, from well brines in Michigan by Martin Marietta and from magnesite in Nevada by Premier Magnesia. Intrepid Potash Wendover LLC and Great Salt Lake Minerals Corp. recovered magnesium chloride brines from the Great Salt Lake in Utah. Magnesium hydroxide was produced from seawater by SPI Pharma Inc. in Delaware and Premier Magnesia in Florida, and by Martin Marietta from its brine operation in Michigan.

Magnesium-based implants: a mini-review.

Science.gov (United States)

Luthringer, Bérengère J C; Feyerabend, Frank; Willumeit-Römer, Regine

2014-01-01

The goal of this review is to bring to the attention of the readership of Magnesium Research another facet of the importance of magnesium, i.e. magnesium-based biomaterials. A concise history of biomaterials and magnesium are thus presented. In addition, historical and current, clinical magnesium-based applications are presented.

Performance of cement solidification with barium for high activity liquid waste including sulphate

International Nuclear Information System (INIS)

Waki, Toshikazu; Yamada, Motoyuki; Horikawa, Yoshihiko; Kaneko, Masaaki; Saso, Michitaka; Haruguchi, Yoshiko; Yamashita, Yu; Sakai, Hitoshi

2009-01-01

The target liquid waste to be solidified is generated from PWR primary loop spent resin treatment with sulphate acid, so, its main constituent is sodium sulphate and the activity of this liquid is relatively high. Waste form of this liquid waste is considered to be a candidate for the subsurface disposal. The disposed waste including sulphate is anticipated to rise a concentration of sulphate ion in the ground water around the disposal facility and it may cause degradation of materials such as cement and bentonite layer and comprise the disposal facility. There could be two approaches to avoid this problem, the strong design of the disposal facility and the minimization of sulphaste ion migration from the solidified waste. In this study, the latter approach was examined. In order to keep the low concentration of sulphate ion in the ground water, it is effective to make barium sulphate by adding barium compound into the liquid waste in solidification. However, adding equivalent amount of barium compound with sulphate ion causes difficulty of mixing, because production of barium sulphate causes high viscosity. In this study, mixing condition after and before adding cement into the liquid waste was estimated. The mixing condition was set with consideration to keep anion concentration low in the ground water and of mixing easily enough in practical operation. Long term leaching behavior of the simulated solidified waste was also analyzed by PHREEQC. And the concentration of the constitution affected to the disposal facility was estimated be low enough in the ground water. (author)

Ionized magnesium in plasma and erythrocytes for the assessment of low magnesium status in alcohol dependent patients.

Science.gov (United States)

Ordak, Michal; Maj-Zurawska, Magdalena; Matsumoto, Halina; Bujalska-Zadrozny, Magdalena; Kieres-Salomonski, Ilona; Nasierowski, Tadeusz; Muszynska, Elzbieta; Wojnar, Marcin

2017-09-01

Studies on the homeostasis of magnesium in alcohol-dependent patients have often been characterized by low hypomagnesemia detection rates. This may be due to the fact that the content of magnesium in blood serum constitutes only 1% of the average magnesium level within the human body. However, the concentration of ionized magnesium is more physiologically important and makes up 67% of the total magnesium within a human organism. There are no data concerning the determination of the ionized fraction of magnesium in patients addicted to alcohol and its influence on mental health status. This study included 100 alcohol-dependent patients and 50 healthy subjects. The free magnesium fraction was determined using the potentiometric method by means of using ion-selective electrodes. The total magnesium level was determined by using a biochemical Indiko Plus analyzer. In this study, different psychometric scales were applied. Our results confirm the usefulness of ionized magnesium concentrations in erythrocytes and plasma as a diagnostic parameter of low magnesium status in alcohol-dependent patients. The lower the concentration of ionized magnesium, the worse the quality of life an alcohol-dependent person might experience. In the case of total magnesium, no such correlation was determined. Copyright © 2017 Elsevier B.V. All rights reserved.

Choline Magnesium Trisalicylate

Science.gov (United States)

Choline magnesium trisalicylate is used to relieve the pain, tenderness, inflammation (swelling), and stiffness caused by arthritis and painful ... used to relieve pain and lower fever. Choline magnesium trisalicylate is in a class of nonsteroidal anti- ...

Effect of temperature on sulphate reduction, growth rate and growth yield in five psychrophilic sulphate-reducing bacteria from Arctic sediments

DEFF Research Database (Denmark)

Knoblauch, C.; Jørgensen, BB

1999-01-01

Five psychrophilic sulphate-reducing bacteria (strains ASv26, LSv21, PSv29, LSv54 and LSv514) isolated from Arctic sediments were examined for their adaptation to permanently low temperatures, All strains grew at -1.8 degrees C, the freezing point of sea water, but their optimum temperature...... and T(opt). For strains LSv21 and LSv514, however, growth yields were highest at the lowest temperatures, around 0 degrees C. The results indicate that psychrophilic sulphate-reducing bacteria are specially adapted to permanently low temperatures by high relative growth rates and high growth yields...... at in site conditions....

Complete sulphate removal from neutralised acidic mine drainage with barium carbonate

CSIR Research Space (South Africa)

Swanepoel, H

2012-03-01

Full Text Available -barium-calcium) Desalination process which uses barium salts to further reduce the sulphate concentration to acceptable levels with the added advantage that sulphate removal can be controlled due to the low solubility of BaSO4. This paper reports on the results...

Combustion and extinction of magnesium fires

International Nuclear Information System (INIS)

Malet, J.C.; Duverger de Cuy, G.

1988-01-01

The studies made in France on magnesium combustion and extinguishing means are associated at the nuclear fuel of the graphite-gas reactor. Safety studies are made for ameliorate our knowledge on: - magnesium combustion - magnesium fire propagation - magnesium fire extinguishing [fr

Magnesium deficiency: What is our status

Science.gov (United States)

Low magnesium intake has been implicated in a broad range of cardiometabolic conditions, including diabetes, hypertension, and cardiovascular disease. Dietary magnesium and total body magnesium status have a widely-used but imperfect biomarker in serum magnesium. Despite serum magnesium’s limitation...

Development of melt compositions for sulphate bearing high level waste

International Nuclear Information System (INIS)

Jahagirdar, P.B.; Wattal, P.K.

1997-09-01

The report deals with the development and characterization of vitreous matrices for sulphate bearing high level waste. Studies were conducted in sodium borosilicate and lead borosilicate systems with the introduction of CaO, BaO, MgO etc. Lead borosilicate system was found to be compatible with sulphate bearing high level wastes. Detailed product evaluation carried on selected formulations is also described. (author)

Effect of surface coating with magnesium stearate via mechanical dry powder coating approach on the aerosol performance of micronized drug powders from dry powder inhalers.

Science.gov (United States)

Zhou, Qi Tony; Qu, Li; Gengenbach, Thomas; Larson, Ian; Stewart, Peter J; Morton, David A V

2013-03-01

The objective of this study was to investigate the effect of particle surface coating with magnesium stearate on the aerosolization of dry powder inhaler formulations. Micronized salbutamol sulphate as a model drug was dry coated with magnesium stearate using a mechanofusion technique. The coating quality was characterized by X-ray photoelectron spectroscopy. Powder bulk and flow properties were assessed by bulk densities and shear cell measurements. The aerosol performance was studied by laser diffraction and supported by a twin-stage impinger. High degrees of coating coverage were achieved after mechanofusion, as measured by X-ray photoelectron spectroscopy. Concomitant significant increases occurred in powder bulk densities and in aerosol performance after coating. The apparent optimum performance corresponded with using 2% w/w magnesium stearate. In contrast, traditional blending resulted in no significant changes in either bulk or aerosolization behaviour compared to the untreated sample. It is believed that conventional low-shear blending provides insufficient energy levels to expose host micronized particle surfaces from agglomerates and to distribute guest coating material effectively for coating. A simple ultra-high-shear mechanical dry powder coating step was shown as highly effective in producing ultra-thin coatings on micronized powders and to substantially improve the powder aerosolization efficiency.

Whisker growth: a new mechanism for helium blistering of surfaces in complex radiation environments

International Nuclear Information System (INIS)

McDonell, W.R.

1978-01-01

Implantation of helium concurrent with the generation of large numbers of displaced atoms in surface layers of materials exposed to 252 Cf α-particles and fission fragments produces a unique form of low temperature surface blistering. The purpose of this paper is to formulate a basis for the whisker-growth mechanism for helium blistering as an aid to the specification of conditions under which the mechanism might apply

Zirconia toughened SiC whisker reinforced alumina composites small business innovation research

Science.gov (United States)

Loutfy, R. O.; Stuffle, K. L.; Withers, J. C.; Lee, C. T.

1987-01-01

The objective of this phase 1 project was to develop a ceramic composite with superior fracture toughness and high strength, based on combining two toughness inducing materials: zirconia for transformation toughening and SiC whiskers for reinforcement, in a controlled microstructure alumina matrix. The controlled matrix microstructure is obtained by controlling the nucleation frequency of the alumina gel with seeds (submicron alpha-alumina). The results demonstrate the technical feasibility of producing superior binary composites (Al2O3-ZrO2) and tertiary composites (Al2O3-ZrO2-SiC). Thirty-two composites were prepared, consolidated, and fracture toughness tested. Statistical analysis of the results showed that: (1) the SiC type is the key statistically significant factor for increased toughness; (2) sol-gel processing with a-alumina seed had a statistically significant effect on increasing toughness of the binary and tertiary composites compared to the corresponding mixed powder processing; and (3) ZrO2 content within the range investigated had a minor effect. Binary composites with an average critical fracture toughness of 6.6MPam sup 1/2, were obtained. Tertiary composites with critical fracture toughness in the range of 9.3 to 10.1 MPam sup 1/2 were obtained. Results indicate that these composites are superior to zirconia toughened alumina and SiC whisker reinforced alumina ceramic composites produced by conventional techniques with similar composition from published data.

Spider silk as a template for obtaining magnesium oxide and magnesium hydroxide fibers

Directory of Open Access Journals (Sweden)

Dmitrović Svetlana

2018-01-01

Full Text Available Spider silk fibers, collected from Pholcus Phalangioides spider were used as a template for obtaining magnesium oxide (MgO, periclase as well as magnesium hydroxide (Mg(OH2, brucite fibers. Magnesium oxide fibers were obtained in a simple manner by heat induced decomposition of magnesium salt (MgCl2 in the presence of the spider silk fibers, while magnesium hydroxide fibers were synthesized by hydration of MgO fibers at 50, 70 and 90 C, for 48 and 96 h. According to Scanning electron microscopy (SEM, dimensions of spider silk fibers determined the dimension of synthesized MgO fibers, while for Mg(OH2 fibers, the average diameter was increased with prolonging the hydration period. The surface of Mg(OH2 fibers was noticed to be covered with brucite in a form of plates. X-Ray diffraction (XRD analysis showed that MgO fibers were single-phased (the pure magnesium oxide fibers were obtained, while Mg(OH2 fibers were two- or single-phased brucite depending on incubation period, and/or incubation temperature. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 45012

Magnesium Technology : Preface

NARCIS (Netherlands)

Sillekens, W.H.; Agnew, S.R.; Neelameggham, N.R.; Mathaudhu, S.N.

2011-01-01

The Magnesium Technology Symposium, which takes place every year at the TMS Annual Meeting & Exhibition, is one of the largest yearly gatherings of magnesium specialists in the world. Papers are presented in all aspects of the field, ranging from primary production to applications to recycling.

The Corrosion of Magnesium and of the Magnesium Aluminum Alloys Containing Manganese

Science.gov (United States)

Boyer, J A

1927-01-01

The extensive use of magnesium and its alloys in aircraft has been seriously handicapped by the uncertainties surrounding their resistance to corrosion. This problem has been given intense study by the American Magnesium Corporation and at the request of the Subcommittee on Materials for Aircraft of the National Advisory Committee for Aeronautics this report was prepared on the corrosion of magnesium. The tentative conclusions drawn from the experimental facts of this investigation are as follows: the overvoltage of pure magnesium is quite high. On immersion in salt water the metal corrodes with the liberation of hydrogen until the film of corrosion product lowers the potential to a critical value. When the potential reaches this value it no longer exceeds the theoretical hydrogen potential plus the overvoltage of the metal. Rapid corrosion consequently ceases. When aluminum is added, especially when in large amounts, the overvoltage is decreased and hydrogen plates out at a much lower potential than with pure magnesium. The addition of small amount of manganese raises the overvoltage back to practically that of pure metal, and the film is again negative.

Differential inhibition of polymorphonuclear leukocyte recruitment in vivo by dextran sulphate and fucoidan

Directory of Open Access Journals (Sweden)

N. Van Osselaer

1996-01-01

Full Text Available The selectin-mediated rolling of leukocytes along the endothelial cells is a prerequisite step followed by firm adhesion and extravasation into the inflamed tissue. This initial contact can be suppressed by sulphated polysaccharides. We have studied the effect of sulphated polysaccharides on the ultimate polymorphonuclear leukocyte (PMN recruitment and plasma leakage in rabbit skin in response to intradermal injection of various inflammatory mediators. PMN infiltration evoked by various PMN chemoattractants (FMLP, C5a desArg, LTB4 and IL-8 was significantly inhibited after intravenous injection of dextran sulphate (25 mg/kg, heparin (2 × 90 mg/kg or fucoidan (1 mg/kg. PMN-dependent plasma leakage was equally well reduced by the different sulphated polymers. Vascular permeability induced by histamine or thrombin acting via a PMN-independent mechanism was not reduced. Fucoidan was the only polysaccharide able to suppress IL-1-induced PMN infiltration for 60–70%. Local administration of dextran sulphate had no effect on PMN-dependent plasma leakage. Differential inhibition of PMN recruitment was determined after injection of dextran sulphate or fucoidan depending on the type of insult. Therefore, these results suggest that different adhesion pathways are utilized during PMN recruitment in vivo in response to chemoattractants and IL-1.

The reducibility of sulphuric acid and sulphate in aqueous solution (translated from German)

International Nuclear Information System (INIS)

Grauer, R.

1990-07-01

In connection with the Swedish project for the final storage of spent fuel elements it was necessary to assess whether dissolved sulphate can corrode the copper canister without the intervention of sulphate-reducing bacteria. A simple reaction between copper and sulphate is thermodynamically impossible. On the other hand, copper can react to give copper sulphide if an additional electron donor such as iron is available. Because little specific information is available about this subject the problem was extended to the much more general question of the reducibility of sulphur in dilute aqueous solution. It is a part of the general knowledge of chemistry, and there is also unanimity about it in the geochemical literature, that purely chemical reduction of sulphate does not take place in dilute solution at temperatures below 100 degrees C. This fact is, however, poorly documented and it was therefore necessary to substantiate it by drawing on numerous individual findings from different areas of pure and applied chemistry. The investigation confirms that sulphur in dilute solution is completely inert towards chemical reducing agents and also to cathodic reduction. Thus corrosion of copper by sulphate under final-storage conditions and in the absence of sulphate reducing bacteria can be ruled out with a probability verging on certainty. (85 refs.)

Influence on ammonium-sulphate fertilizer on P-uptake by upland rice

International Nuclear Information System (INIS)

Abdullah, N; Mitrosuhardjo, M.M.

1988-01-01

A greenhouse experiment to study the influence of ammonium -sulphate fertilizer on P-uptake by Atomita I/1 rice variety on latosol soil of Pasar Jumat has been conducted. Factorial experiment consisting of eight treatments was arrange in a fully randomized design. Each treatment was replicated three times. The rate of ammonium sulphate fertilizer was equivalent to 0, 30, 60, and 90 kg N/ha, and TSP at the rate of 90 and 180 kg P/ha. Ammonium sulphate fertilizer with 2% atom 15-N and TSP with specific activity of 0.2 mCi/g P2O5 were used in the experiment. The plant was harvested 70 days after planting, It was turned out that ammonium sulphate fertilizer gave a highly significant difference (p=<0.01) of dry weight of plant. The rate of TSP did not effect significantly on plant dry weight. Ammonium sulphate fertilizer gave highly significant difference on P-uptake. Fertilizer use efficiency was in the range of 3.88 - 6.60% for 90 kg P and 2.51 - 4.46% for 180 kg P. Fertilizer-N uptake was significantly increased (p=<0.05) with the increase of N rate. Rate of fertilizer-N use efficiency was in the range of 47-60% of the applied fertilizer. (authors). 4 refs, 9 tabs

Tyrosine sulphation is not required for microvillar expression of intestinal aminopeptidase N

DEFF Research Database (Denmark)

Danielsen, E M

1988-01-01

incorporation of [35S]sulphate into aminopeptidase N and other major microvillar hydrolases by 70-85% compared with controls, indicating an inhibition of their post-translational tyrosine sulphation. In labelling experiments with [35S]methionine from 0.5 to 5 h, DCNP was tested for its possible influence...... on synthesis, processing and microvillar expression of aminopeptidase N, but no effect on any of these parameters could be detected. It can therefore be concluded that tyrosine sulphation is not required (for instance as a sorting signal) for the targeting of newly synthesized enzymes to the microvillar...

Oxygen isotopic composition of sulphates from some mineral waters and mine waters in western Bohemia

International Nuclear Information System (INIS)

Smejkal, V.

1979-01-01

Two main genetic types of sulphate can be distinguished according to the delta 18 O(SO 4 2- ) measurements in sulphate-rich mineral and mine waters of western Bohemia - sulphates in descending mine waters and in weathered outcrops of graphitic pyrite slates from areas outside Tertiary basins, which originated in recent time by the oxidation of sulphides in the presence of atmospheric oxygen, have delta 18 O values from -2.1 to -6.1 per mille SMOW; and sulphates from springs of mineral waters of the renowned spas of Karlovy Vary, Frantiskovy Lazne and Marianske Lazne show distinctly heavier delta 18 O values - from +4.0 to +6.4 per mille, with maximum of values between +5.0 and +6.0 per mille. Similar delta 18 O values have been established in thenardites and in gypsum in Miocene claystones and in sulphates of some mine waters in the nearby Tertiary Cheb and Sokolov Basins. The presented results indicate that sulphates in mineral waters of the Karlovy Vary type originate mainly by leaching of Miocene sulphates and not by present-day oxidation of sulphidic sulphur. (author)

Possibilities of Sulphate Elimination from Mine Water

Directory of Open Access Journals (Sweden)

Heviánková Silvie

2004-12-01

Full Text Available The issue of „acid water“ (or AMD is well known in the world for some centuries. In the Eastern Slovakia, the most acid surface water occurs in the area of old mine Smolník, which is closed and submerged for 15 years. The submitted contribution deals with the sulphate-elimination from this locality. Recently, several methods of sulphate-elimination from the mine water are applied. The best-known methods are biological, physical-chemical and chemical precipitation. The method described in this contribution consists of chemical precipitation by sodium aluminate and calcium hydrate. Under application of this method very interesting results were obtained. The amount of SO42- anions decreased to almost zero-value, using optimal doses of the chemical reagents.

OS033. Correlates of maternal health outcomes associated with a low-costintervention in secondary facilities across Kano state, Nigeria.

Science.gov (United States)

Tukur, J; Ahonsi, B; Salisu, I; Oginni, A B; Okereke, E

2012-07-01

Nigeria has one of the highest rates of maternal mortality in the world. Eclampsia is a major contributor to the deaths especially in Northern Nigeria where the culture of teenage marriage is common. Kano is the state with the highest population in Nigeria. Despite its effectiveness, magnesium sulphate was been used to treat eclampsia and severe preclampsia in only one of 35 general hospitals inthe state as at 2007. In 2008, magnesium sulphate was introduced in 10 General Hospitals in Kano state of Northern Nigeria in a Population Council project funded by the MacArthur Foundation. The aim of the study was to determine if the maternal outcomes improved. Doctors and midwives from the 10 hospitals were trained on the use of magnesium sulphate. The trained health workers later conducted step down trainings at their health facilities. Magnesium sulphate, treatment protocol, patella hammer and calcium gluconate were then supplied to the hospitals. Data was collected through structured data forms. The data was analysed using SPSS. Within a year of the project, 1045 patients with severe preeclampsia and eclampsia were treated. The case fatality rate for severe preeclampsia and eclampsia fell from 20.9% (95% CI 18.7-23.2) recorded before the project to 2.3% (95%CI 1.5-3.5) after the project. The perinatal mortality rate in those that received magnesium sulphate was 12.3% (CI 10.4-14.5) while the 5min APGAR score for 72.9% of the babies was 7 or more. Training of health workers on updated evidence based interventions and providing an enabling environment for their practice are key components to the attainment of the Millennium Development Goals in developing countries. Copyright © 2012. Published by Elsevier B.V.

The Metal And Sulphate Removal From Mine Drainage Waters By Biological-Chemical Ways

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Jenčárová Jana

2015-06-01

Full Text Available Mine drainage waters are often characterized by high concentrations of sulphates and metals as a consequence of the mining industry of sulphide minerals. The aims of this work are to prove some biological-chemical processes utilization for the mine drainage water treatment. The studied principles of contamination elimination from these waters include sulphate reduction and metal bioprecipitation by the application of sulphate-reducing bacteria (SRB. Other studied process was metal sorption by prepared biogenic sorbent. Mine drainage waters from Slovak localities Banská Štiavnica and Smolník were used to the pollution removal examination. In Banská Štiavnica water, sulphates decreased below the legislative limit. The elimination of zinc by sorption experiments achieved 84 % and 65 %, respectively.

Photoluminescence of magnesium-associated color centers in LiF crystals implanted with magnesium ions

Science.gov (United States)

Nebogin, S. A.; Ivanov, N. A.; Bryukvina, L. I.; V. Shipitsin, N.; E. Rzhechitskii, A.; Papernyi, V. L.

2018-05-01

In the present paper, the effect of magnesium nanoparticles implanted in a LiF crystal on the optical properties of color centers is studied. The transmittance spectra and AFM images demonstrate effective formation of the color centers and magnesium nanoparticles in an implanted layer of ∼ 60-100 nm in thickness. Under thermal annealing, a periodical structure is formed on the surface of the crystal and in the implanted layer due to self-organization of the magnesium nanoparticles. Upon excitation by argon laser with a wavelength of 488 nm at 5 K, in a LiF crystal, implanted with magnesium ions as well as in heavily γ-irradiated LiF: Mg crystals, luminescence of the color centers at λmax = 640 nm with a zero-phonon line at 601.5 nm is observed. The interaction of magnesium nanoparticles and luminescing color centers in a layer implanted with magnesium ions has been revealed. It is shown that the luminescence intensity of the implanted layer at a wavelength of 640 nm is by more than two thousand times higher than that of a heavily γ-irradiated LiF: Mg crystal. The broadening of the zero-phonon line at 601.5 nm in the spectrum of the implanted layer indicates the interaction of the emitting quantum system with local field of the surface plasmons of magnesium nanoparticles. The focus of this work is to further optimize the processing parameters in a way to result in luminescence great enhancement of color centers by magnesium nanoparticles in LiF.

Volcanic lake systems as terrestrial analogue for sulphate-rich terrains on Mars

NARCIS (Netherlands)

Rodríguez, A.

2016-01-01

Remote-sensing observations and rover missions have documented the abundant presence of sulphate-rich mineral associations on the surface of Mars. Together with widespread occurrences of silica and frequent enrichments of chlorine and bromine in soils and rocks, the sulphate associations are

21 CFR 184.1443 - Magnesium sulfate.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Magnesium sulfate. 184.1443 Section 184.1443 Food... Specific Substances Affirmed as GRAS § 184.1443 Magnesium sulfate. (a) Magnesium sulfate (MgSO4·7H2O, CAS... magnesium oxide, hydroxide, or carbonate with sulfuric acid and evaporating the solution to crystallization...

Mineral resource of the month: magnesium

Science.gov (United States)

Kramer, Deborah A.

2012-01-01

Magnesium is the eighthmost abundant element in Earth’s crust, and the second-most abundant metal ion in seawater. Although magnesium is found in more than 60 minerals, only brucite, dolomite, magnesite and carnallite are commercially important for their magnesium content. Magnesium and its compounds also are recovered from seawater, brines found in lakes and wells, and bitterns (salts).

21 CFR 184.1431 - Magnesium oxide.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Magnesium oxide. 184.1431 Section 184.1431 Food and... Substances Affirmed as GRAS § 184.1431 Magnesium oxide. (a) Magnesium oxide (MgO, CAS Reg. No. 1309-48-4... powder (light) or a relatively dense white powder (heavy) by heating magnesium hydroxide or carbonate...

21 CFR 184.1426 - Magnesium chloride.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Magnesium chloride. 184.1426 Section 184.1426 Food... Specific Substances Affirmed as GRAS § 184.1426 Magnesium chloride. (a) Magnesium chloride (MgC12·6H2O, CAS... hydrochloric acid solution and crystallizing out magnesium chloride hexahydrate. (b) The ingredient meets the...

Risk minimisation of FGD gypsum leachates by incorporation of aluminium sulphate

Energy Technology Data Exchange (ETDEWEB)

Alvarez-Ayuso, E. [Department of Environmental Geology, Institute of Earth Sciences ' Jaume Almera' (CSIC), C/ Lluis Sole i Sabaris, s/n, 08028 Barcelona (Spain); Department of Environmental Geochemistry, IRNASA, CSIC, Apto. 257, 37071 Salamanca (Spain)], E-mail: ealvarez@ija.csic.es; Querol, X. [Department of Environmental Geology, Institute of Earth Sciences ' Jaume Almera' (CSIC), C/ Lluis Sole i Sabaris, s/n, 08028 Barcelona (Spain); Ballesteros, J.C.; Gimenez, A. [Endesa Generacion, S.A., C/ Ribera de Loira, 60, 28042 Madrid (Spain)

2008-11-15

The incorporation of aluminium sulphate to (flue gas desulphurisation) FGD gypsum before its disposal was investigated as a way to minimise the risk supposed by the high fluoride content of its leachates. Using a bath method the kinetic and equilibrium processes of fluoride removal by aluminium sulphate were studied at fluoride/aluminium molar concentration (F/Al) ratios in the range 1.75 10{sup -2}-1.75 under the pH conditions (about 6.5) of FGD gypsum leachates. It was found that fluoride removal was a very fast process at any of the (F/Al) ratios subject of study, with equilibrium attained within the first 15 min of interaction. High decreases in solution fluoride concentrations (50-80%) were found at the equilibrium state. The use of aluminium sulphate in the stabilization of FGD gypsum proved to greatly decrease its fluoride leachable content (in the range 20-90% for aluminium sulphate doses of 0.1-5%, as determined by the European standard EN 12457-4). Such fluoride leaching minimisation assures the characterization of this by-product as a waste acceptable at landfills for non-hazardous wastes according to the Council Decision 2003/33/EC on waste disposal. Furthermore, as derived from column leaching studies, the proposed stabilization system showed to be highly effective in simulated conditions of disposal, displaying fluoride leaching reduction values about 55 and 80% for aluminium sulphate added amounts of 1 and 2%, respectively.

Efeito do sulfato de magnésio sobre o índice de pulsatilidade das artérias uterinas, umbilical e cerebral média fetal de acordo com a persistência da incisura protodiastólica da artéria uterina na pré-eclâmpsia grave Effect of magnesium sulfate on pulsatility index of uterine, umbilical and fetal middle cerebral arteries according to the persistence of bilateral diastolic notch of uterine arteries in patients with severe preeclampsia

Directory of Open Access Journals (Sweden)

Alex Sandro Rolland Souza

2009-02-01

ção intravenosa de 6 g do sulfato de magnésio nas pacientes com pré-eclâmpsia grave, ocorre uma diminuição da pressão arterial e do IP das artérias uterinas, umbilicais e cerebral média fetal, além de aumento da frequência cardíaca materna, não influenciada pela presença de incisura protodiastólica bilateral nas artérias uterinas.PURPOSE: to evaluate the effect of magnesium sulphate on the pulsatility index (PI of the uterine, umbilical and fetal middle cerebral arteries, according to the persistency or not of the bilateral protodiastolic notch of the uterine arteries in severe pre-eclampsia. METHODS: a cohort study including 40 pregnant women with severe pre-eclampsia, 23 of them presenting bilateral protodiastolic notch, and 17, unilateral/absent notch. The patients were submitted to Doppler velocimetry before and 20 minutes after the intravenous administration of 6 g of magnesium sulphate. The examination was carried out with the patient in semi-Fowler position, the sonograms being obtained during fetal inactivity, in apnea and absent uterine contraction periods. All the exams were performed by two researchers, the average being considered as the final result. Wilcoxon's test was used to compare the PI, before and after magnesium sulphate in both groups. The difference between the two measurements (before and after magnesium sulphate was compared between the groups (bilateral incision and unilateral/absent incision using the Mann-Whitney test. RESULTS: there was a significant increase in the maternal heart rate (MHR and decrease in the maternal blood pressure, and in the PI medians of the two uterine arteries and in the fetal middle cerebral artery, after magnesium sulphate in both groups. There was a significant decrease in the PI of the left uterine artery and in the umbilical artery, only in the protodiastolic unilateral/absent notch group. Nevertheless, it was not found any significant difference regarding the PI of the right uterine artery, or the cerebral

Lightweight Heat Pipes Made from Magnesium

Science.gov (United States)

Rosenfeld, John N.; Zarembo, Sergei N.; Eastman, G. Yale

2010-01-01

Magnesium has shown promise as a lighter-weight alternative to the aluminum alloys now used to make the main structural components of axially grooved heat pipes that contain ammonia as the working fluid. Magnesium heat-pipe structures can be fabricated by conventional processes that include extrusion, machining, welding, and bending. The thermal performances of magnesium heat pipes are the same as those of equal-sized aluminum heat pipes. However, by virtue of the lower mass density of magnesium, the magnesium heat pipes weigh 35 percent less. Conceived for use aboard spacecraft, magnesium heat pipes could also be attractive as heat-transfer devices in terrestrial applications in which minimization of weight is sought: examples include radio-communication equipment and laptop computers.

21 CFR 862.1495 - Magnesium test system.

Science.gov (United States)

2010-04-01

... magnesium levels in serum and plasma. Magnesium measurements are used in the diagnosis and treatment of hypomagnesemia (abnormally low plasma levels of magnesium) and hypermagnesemia (abnormally high plasma levels of magnesium). (b) Classification. Class I. ...

Radioactive 210Po in magnesium supplements

International Nuclear Information System (INIS)

Struminska-Parulska, Dagmara Ida

2016-01-01

The aim of this pioneer study was to determine polonium 210 Po in the most popular magnesium supplements in Poland and estimate the possible related dose assessment to the consumers. The analyzed magnesium pharmaceutics contained organic or inorganic magnesium compounds; some from natural sources. The objectives of this research were to investigate the naturally occurring 210 Po activity concentrations in magnesium supplements, find the correlations between 210 Po concentration in medicament and magnesium chemical form, and calculate the effective radiation dose connected to analyzed magnesium supplement consumption. The highest 210 Po activity concentrations were determined in mineral tablets made from sedimentary rocks, namely dolomite - 3.84 ± 0.15 mBq g -1 (sample Mg17). The highest annual radiation dose from 210 Po taken with 1 tablet of magnesium supplement per day or with 400 mg of pure Mg daily would come from sample Mg17 (dolomite) - 1.35 ± 0.5 and 8.44 ± 0.33 μSv year -1 respectively.

Lumbosacral epidural magnesium prolongs ketamine analgesia in conscious sheep Sulfato de magnésio prolonga a analgesia epidural lombosacral induzida pela quetamina em carneiros

Directory of Open Access Journals (Sweden)

Rafael DeRossi

2012-02-01

Full Text Available PURPOSE: To determine the analgesic, motor, sedation and systemic effects of lumbosacral epidural magnesium sulphate added to ketamine in the sheep. METHODS: Six healthy adult male mixed-breed sheep; weighing 43 ± 5 kg and aged 20-36 months. Each sheep underwent three treatments, at least 2 weeks apart, via epidural injection: (1 ketamine (KE; 2.5 mg/kg, (2 magnesium sulphate (MG; 100 mg, and (3 KE + MG (KEMG; 2.5 mg/kg + 100 mg, respectively. Epidural injections were administered through the lumbosacral space. Analgesia, motor block, sedation, cardiovascular effects, respiratory rate, skin temperature, and rectal temperature were evaluated before (baseline and after drug administration as needed. RESULTS: The duration of analgesia with the lumbosacral epidural KEMG combination was 115 ± 17 min (mean ± SD, that is, more than twice that obtained with KE (41 ± 7 min or MG (29 ± 5 min alone. KE and KEMG used in this experiment induced severe ataxia. The heart rate and arterial blood pressures changes were no statistical difference in these clinically health sheep. CONCLUSION: The dose of magnesium sulphate to lumbosacral epidural ketamine in sheep is feasible, and can be used in procedures analgesics in sheep.OBJETIVO: Determinar os efeitos analgésicos, motores, sedativos e sistêmicos da adição de sulfato de magnésio na analgesia epidural com quetamina em carneiros. MÉTODOS: Foram utilizados seis carneiros machos sadios, pesando 43 ± 5 kg, com idade entre 20 a 36 meses. Cada animal recebeu três tratamentos, com duas semanas entre experimentos via administração epidural: (1 quetamina (KE; 2,5 mg/kg, (2 sulfato de magnésio (MG; 100 mg e (3 KE + MG (KEMG; 2,5 mg/kg + 100 mg, respectivamente. As administrações epidurais foram administradas no espaço lombosacral. Analgesia, bloqueio motor, sedação, efeitos cardiovasculares, freqüência respiratória, temperatura retal e de pele foram avaliados antes (basal e depois da administra

Significantly Enhanced Dielectric Performances and High Thermal Conductivity in Poly(vinylidene fluoride)-Based Composites Enabled by SiC@SiO2 Core-Shell Whiskers Alignment.

Science.gov (United States)

He, Dalong; Wang, Yao; Song, Silong; Liu, Song; Deng, Yuan

2017-12-27

Design of composites with ordered fillers arrangement results in anisotropic performances with greatly enhanced properties along a specific direction, which is a powerful tool to optimize physical properties of composites. Well-aligned core-shell SiC@SiO 2 whiskers in poly(vinylidene fluoride) (PVDF) matrix has been achieved via a modified spinning approach. Because of the high aspect ratio of SiC whiskers, strong anisotropy and significant enhancement in dielectric constant were observed with permittivity 854 along the parallel direction versus 71 along the perpendicular direction at 20 vol % SiC@SiO 2 loading, while little increase in dielectric loss was found due to the highly insulating SiO 2 shell. The anisotropic dielectric behavior of the composite is perfectly understood macroscopically to have originated from anisotropic intensity of interfacial polarization based on an equivalent circuit model of two parallel RC circuits connected in series. Furthermore, finite element simulations on the three-dimensional distribution of local electric field, polarization, and leakage current density in oriented SiC@SiO 2 /PVDF composites under different applied electrical field directions unambiguously revealed that aligned core-shell SiC@SiO 2 whiskers with a high aspect ratio significantly improved dielectric performances. Importantly, the thermal conductivity of the composite was synchronously enhanced over 7 times as compared to that of PVDF matrix along the parallel direction at 20 vol % SiC@SiO 2 whiskers loading. This study highlights an effective strategy to achieve excellent comprehensive properties for high-k dielectrics.

Alkoxide-based magnesium electrolyte compositions for magnesium batteries

Science.gov (United States)

Dai, Sheng; Sun, Xiao-Guang; Liao, Chen; Guo, Bingkun

2018-01-30

Alkoxide magnesium halide compounds having the formula: RO--Mg--X (1) wherein R is a saturated or unsaturated hydrocarbon group that is unsubstituted, or alternatively, substituted with one or more heteroatom linkers and/or one or more heteroatom-containing groups comprising at least one heteroatom selected from fluorine, nitrogen, oxygen, sulfur, and silicon; and X is a halide atom. Also described are electrolyte compositions containing a compound of Formula (1) in a suitable polar aprotic or ionic solvent, as well as magnesium batteries in which such electrolytes are incorporated.

Corrosion resistance of multilayered magnesium phosphate/magnesium hydroxide film formed on magnesium alloy using steam-curing assisted chemical conversion method

International Nuclear Information System (INIS)

Ishizaki, Takahiro; Kudo, Ruriko; Omi, Takeshi; Teshima, Katsuya; Sonoda, Tsutomu; Shigematsu, Ichinori; Sakamoto, Michiru

2012-01-01

Anticorrosive multilayered films were successfully prepared on magnesium alloy AZ31 by chemical conversion treatment, followed by steam curing treatment. The crystal structures, chemical composition, surface morphologies, chemical bonding states of the film was characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and field emission scanning electron microscope (FE-SEM) measurements. All the films had thicknesses of ranging from 24 to 32 μm. The film had two layers that were composed of crystalline NH 4 MgPO 4 ·H 2 O, Mg 2 PO 4 OH·3H 2 O, Mg(OH) 2 and amorphous MgO. The outer layers include magnesium, oxygen, and phosphorous, and the inner layers include magnesium and oxygen. The corrosion resistant performances of the multilayered films in 5 wt% NaCl aqueous solution were investigated by electrochemical and gravimetric measurements. The potentiodynamic polarization curves revealed that the corrosion current density (j corr ) of all the film coated magnesium alloys decreased by more than four orders of magnitude as compared to that of the bare magnesium alloy, indicating that all the films had an inhibiting effect of corrosion reaction. Gravimetric measurements showed that the average corrosion rates obtained from the weight loss rates were estimated to be in the ranges of ca. 0.085–0.129 mm/y. American Society for Testing and Materials (ASTM) standard D 3359-02 cross cut tape test revealed that the adhesion of our anticorrosive multilayered film to the magnesium alloy surface was very good.

Abiotic nitrate and sulphate reduction by hydrogen: a comparative experimental study

International Nuclear Information System (INIS)

Truche, L.; Berger, G.; Albrecht, A.; Giffaut, E.

2010-01-01

Document available in extended abstract form only. The bituminous waste which is part of the intermediate level, long-lived waste (MAVL) is characterised, amongst others, by the coexistence of nitrates, sulphates, organic matter, native metals and hydrogen gas in the waste mixture and package. It can be considered as the most complex example that will be used to discuss redox reactions occurring in such waste mixtures. The evaluation of the redox conditions requires quantification of the amount of electron acceptors and donors and definition of the kinetics of redox reaction. The objectives of an experimental study to unravel some of these reaction complexities are: - to investigate nature and rate of sulphate and nitrate reduction by hydrogen in the presence of different catalysts (stainless steel, hastelloy, magnetite and argillite); - to compare sulphate and nitrate as electron acceptors; - to provide a mechanistic model of these reactions. It is well known that reduction of sulphate and nitrate requires high activation energies, usually supplied either by thermal processes or via bacterial and surface catalysis, of which the latter has been investigated in this study. Preliminary experiments performed at 150 deg. C and under H 2 pressure show that sulphate reduction is enhanced in the presence of magnetite, but essentially under the restricted condition of low sulphate concentration and at a pH below the Point of Zero Charge of magnetite. This suggests that sorption of sulphate contributes to the catalysed reaction (at low pH) but provided that the magnetite surface sites are not saturated with respect to aqueous sulphate (low concentration). On the contrary, nitrate reduction is observed whatever the pH and the nitrate concentration in the presence of both magnetite and hastelloy C276 (Ni, Cr, Mo, W, Fe alloy). The effect of temperature on the rate of nitrate reduction (500 ppm KNO 3 solution) is shown by comparing three different experiments conducted in

Nanostructured magnesium increases bone cell density.

Science.gov (United States)

Weng, Lucy; Webster, Thomas J

2012-12-07

Magnesium has attracted some attention in orthopedics due to its biodegradability and mechanical properties. Since magnesium is an essential natural mineral for bone growth, it can be expected that as a biomaterial, it would support bone formation. However, upon degradation in the body, magnesium releases OH(-) which results in an alkaline pH that can be detrimental to cell density (for example, osteoblasts or bone forming cells). For this reason, modification of magnesium may be necessary to compensate for such detrimental effects to cells. This study created biologically inspired nanoscale surface features on magnesium by soaking magnesium in various concentrations of NaOH (from 1 to 10 N) and for various periods of time (from 10 to 30 min). The results provided the first evidence of increased roughness, surface energy, and consequently greater osteoblast adhesion, after 4 h as well as density up to 7 days on magnesium treated with any concentration of NaOH for any length of time compared to untreated controls. For these reasons, this study suggests that soaking magnesium in NaOH could be an inexpensive, simple and effective manner to promote osteoblast functions for numerous orthopedic applications and, thus, should be further studied.

Calcium and magnesium determination

International Nuclear Information System (INIS)

Bhattacharya, S.K.

1982-01-01

The roles of calcium and magnesium in human health and disease have been extensively studied. Calcium and magnesium have been determined in biological specimens by atomic absorption spectroscopy using stiochiometric nitrous oxide-acetylene flame

3.4. Durability of soil-cement mixtures influenced by hostile environment

International Nuclear Information System (INIS)

Saidov, D.Kh.

2011-01-01

It is determined that soil-cement mixture is one of most perspective materials, that can substitute concrete. Experiments on revelation of magnesium sulphate influence on soil-cement mixtures were carried out. Data on granulometric composition and physical parameters of loess soils is presented in this article. Portland cement M 400 was used as binder. According to the results it is concluded that stability of soil-cement mixtures from loess soils in solutions of magnesium sulphate depends on concentration of solution.

Magneto-resistance of Si0,97Ge0,03 whiskers irradiated by reactor fast neutrons

International Nuclear Information System (INIS)

Pavlovska, N.T.; Litovchenko, P.G.; Karpenko, A.Ya.; Uhryn, Yu.O.; Pavlovskyj, Yu.V.; Ostrovskii, I.P.; Khoverko, Yu.M.

2012-01-01

The influence of reactor fast-neutrons irradiation by the fluence of 8,6·10 17 n/cm 2 and strong magnetic field (up to 14 T) on resistance of Si 1-x Ge x (x = 0.03) whiskers in the temperature range of 4,2 - 300 K is studied. The activation energy of the of impurity levels is calculated. The interpretation of changes in the magneto-resistance is proposed

A SEARCH FOR MAGNESIUM IN EUROPA'S ATMOSPHERE

International Nuclear Information System (INIS)

Hörst, S. M.; Brown, M. E.

2013-01-01

Europa's tenuous atmosphere results from sputtering of the surface. The trace element composition of its atmosphere is therefore related to the composition of Europa's surface. Magnesium salts are often invoked to explain Galileo Near Infrared Mapping Spectrometer spectra of Europa's surface, thus magnesium may be present in Europa's atmosphere. We have searched for magnesium emission in the Hubble Space Telescope Faint Object Spectrograph archival spectra of Europa's atmosphere. Magnesium was not detected and we calculate an upper limit on the magnesium column abundance. This upper limit indicates that either Europa's surface is depleted in magnesium relative to sodium and potassium, or magnesium is not sputtered as efficiently resulting in a relative depletion in its atmosphere.

Sulphate content of the Muntimpa dam water and its impact on water quality

International Nuclear Information System (INIS)

Tembo, F; Shitumbanuma, V; Simukanga, S; Mudenda, G; Chileshe, P; Mulenga, S; Phiri, Y

2004-01-01

This article presents results of a study of the quality of water from Muntimpa Dam, a reservior of waste mine water released from the processing of copper and cobalt ores by Konkola Copper Mines(KCM) Plc in Chingola. The mine water is discharged into the local Muntimpa stream, a possible source of drinking and domestic water for the local population. The purpose of the study was to determine levels of sulphate in the dam and stream water and recommend possible methods of partial sulphate removal to levels below the recommended statutory limits and secondly, to assess the impact of high sulphate levels on water quality. Study methods included the sampling of water from the Muntimpa dam and catchment area. Stream water samples were collected about 5m from the stream banks while water samples from the dam were randomly collected from the near the centre of the dam at a depth of 50cm. Laboratory methods involved the determination of physical and chemical properties of the water using standard analytical techniques. Results of the study indicate that both total (2470mg/l) and available (1965mg/l) sulphate concentrations are higher than the recommended statutory limit for the discharge of sulphates into natural streams of 1500mg/l. From the study it is concluded that water in Muntimpa dam and stream is not suitable for drinking and other domestic use due to the high sulphate levels. From theorectical considerations, it was established that sulphate reduction could be achieved by addition of lime, which however had the consquence of increasing the pH of the water in excess of the recommended Zambian statutory value of nine, and would thus require an additional process to reduce the pH. (author)

Corrosion of magnesium and some magnesium alloys in gas cooled reactors

International Nuclear Information System (INIS)

Caillat, R.; Darras, R.

1958-01-01

The results of corrosion tests on magnesium and some magnesium alloys (Mg-Zr and Mg-Zr-Zn) in moist air (like G1 reactor) and in CO 2 : (like G2, G3, EDF1 reactors) are reported. The maximum temperature for exposure of magnesium to moist air without any risk of corrosion is 350 deg. C. Indeed, the oxidation rate follows a linear law above 350 deg. C although it reaches a constant level and keeps on very low under 350 deg. C. However, as far as corrosion is concerned this temperature limit can be raised up to 500 deg. C if moist air is very slightly charged with fluorinated compounds. Under pressure of CO 2 , these three materials oxidate much more slowly even if 500 deg. C is reached. The higher is the temperature, the higher is the constant level of the weight increase and the quicker is reached this one. However, Mg-Zr alloy behaves quite better than pure magnesium and especially than Mg-Zr-Zn alloy. (author) [fr

Grass-cellulose as energy source for biological sulphate removal from acid mine effluents

CSIR Research Space (South Africa)

Greben, HA

2008-11-01

Full Text Available The biological sulphate removal technology requires carbon and energy sources to reduce sulphate to sulphide. Plant biomass, e.g. grass, is a sustainable source of energy when cellulose is utilised during anaerobic degradation, producing volatile...

Highly conductive Al-doped tetra-needle-like ZnO whiskers prepared by a solid state method

International Nuclear Information System (INIS)

Wan Cuifeng; Tan Hairen; Jin Shengming; Yang Huaming; Tang Motang; He Jing

2008-01-01

Tetra-needle-like zinc oxide whiskers (T-ZnO W ) were doped with Al 3+ by a solid state method. In this study, modification conditions were thoroughly investigated to obtain low resistivity T-ZnO W , without destroying the tetra-needle-like structure. The Al-doped T-ZnO W was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transition infrared (FT-IR) spectra and electrical resistance measurement. The SEM and XRD results indicated that the tetra-needle-like structure of ZnO whiskers could be well maintained after modification and the doped (0 0 2) face was preferred. FT-IR results showed that the decrease of resistivity of Al-doped T-ZnO W resulted from formation of [AlO 4 ] configuration in T-ZnO W bulk. Experiment results showed that the annealing temperature, doping concentration and type of Al sources affected the resistivity of T-ZnO W considerably. The optimum Al-doped concentration was 7.0 at.% and the resistivity of T-ZnO W could be considerably decreased from 10 8 to 10 2 Ω cm

Development of a glass matrix for vitrification of sulphate bearing high level radioactive liquid waste

International Nuclear Information System (INIS)

Kaushik, C.P.; Mishra, R.K.; Thorat, Vidya; Ramchandran, M.; Amar Kumar; Ozarde, P.D.; Raj, Kanwar; Das, D.

2004-07-01

High level radioactive liquid waste (HLW) is generated during reprocessing of spent nuclear fuel. In the earlier reprocessing flow sheet ferrous sulphamate has been used for valancy adjustment of Pu from IV to III for effective separation. This has resulted in generation of HLW containing significance amount of sulphate. Internationally borosilicate glass matrix has been adopted for vitrification of HLW. The first Indian vitrification facility at Waste Immobilislition Plant (WIP), Tarapur a five component borosilicate matrix (SiO 2 :B 2 O 3 :Na 2 O : MnO : TiO 2 ) has been used for vitrification of waste. However at Trombay HLW contain significant amount of sulphate which is not compatible with standard borosilicate formulation. Extensive R and D efforts were made to develop a glass formulation which can accommodate sulphate and other constituents of HLW e.g., U, Al, Ca, etc. This report deals with development work of a glass formulations for immobilization of sulphate bearing waste. Different glass formulations were studied to evaluate the compatibility with respect to sulphate and other constituents as mentioned above. This includes sodium, lead and barium borosilicate glass matrices. Problems encountered in different glass matrices for containment of sulphate have also been addressed. A glass formulation based on barium borosilicate was found to be effective and compatible for sulphate bearing high level waste. (author)

Nanostructured magnesium increases bone cell density

International Nuclear Information System (INIS)

Weng, Lucy; Webster, Thomas J

2012-01-01

Magnesium has attracted some attention in orthopedics due to its biodegradability and mechanical properties. Since magnesium is an essential natural mineral for bone growth, it can be expected that as a biomaterial, it would support bone formation. However, upon degradation in the body, magnesium releases OH − which results in an alkaline pH that can be detrimental to cell density (for example, osteoblasts or bone forming cells). For this reason, modification of magnesium may be necessary to compensate for such detrimental effects to cells. This study created biologically inspired nanoscale surface features on magnesium by soaking magnesium in various concentrations of NaOH (from 1 to 10 N) and for various periods of time (from 10 to 30 min). The results provided the first evidence of increased roughness, surface energy, and consequently greater osteoblast adhesion, after 4 h as well as density up to 7 days on magnesium treated with any concentration of NaOH for any length of time compared to untreated controls. For these reasons, this study suggests that soaking magnesium in NaOH could be an inexpensive, simple and effective manner to promote osteoblast functions for numerous orthopedic applications and, thus, should be further studied. (paper)

Nutrition and magnesium absorption

NARCIS (Netherlands)

Brink, E.J.

1992-01-01

The influence of various nutrients present in dairy products and soybean-based products on absorption of magnesium has been investigated. The studies demonstrate that soybean protein versus casein lowers apparent magnesium absorption in rats through its phytate component. However, true

Physical properties of magnesium affected soils in Colombia

International Nuclear Information System (INIS)

Garcia-Ocampo, A.

2004-01-01

Magnesium has some capacity to develop higher exchangeable sodium levels in clays and soil materials. The Mg +2 accumulation on the exchange complex of soils to a very high saturation levels affect their physical, chemical and biological properties. Colombia has a large area of these soils, located mainly in the main rivers valleys and in the Caribbean Region. In the Cauca River Valley there are about 117,000 hectares affected. There is a lack of information about the soil forming processes, the Mg +2 effects on soils, the type and source of compounds responsible for the magnesium enrichment, their relationship with the landscape and the way this accumulation occurs. To identify and quantify soil Mg +2 enriched areas over 2500 soil profiles from different landscape positions of the Cauca River Valley were studied. The information was processed to generate Mg-saturation maps, to identify the different soil profile types and to estimate the affected area. A topographic sequence from the alluvial inundation plain to the hills was used to explore the presence of diagnostic horizons and to determine the main soil characteristics and genetic, mineralogical or chemical evidences of soil forming processes. Two 180 kilometer transects parallel to the river were used to: a) study the type and source of Mg-compounds responsible for the Mg-enrichment and the way this accumulation occurs. b) the soil hydraulic properties like infiltration, saturated hydraulic conductivity and matrix potential at different depths were also measured. Samples of nine profiles were collected and the porosity and soil volume changes at different water content were examined. The program RETC was used for prediction of the hydraulic properties of non saturated soils. These properties involved the retention curve, the function of hydraulic conductivity and the diffusivity of the water in the soil. By grouping together the soil profiles, five main type of Mg-affected soils were identified as being

Magnesium-DNA interactions and the possible relation of magnesium to carcinogenesis. Irradiation and free radicals.

Science.gov (United States)

Anastassopoulou, J; Theophanides, T

2002-04-01

Magnesium deficiency causes renal complications. The appearance of several diseases is related to its depletion in the human body. In radiotherapy, as well as in chemotherapy, especially in treatment of cancers with cis-platinum, hypomagnesaemia is observed. The site effects of chemotherapy that are due to hypomagnesaemia are decreased using Mg supplements. The role of magnesium in DNA stabilization is concentration dependent. At high concentrations there is an accumulation of Mg binding, which induces conformational changes leading to Z-DNA, while at low concentration there is deficiency and destabilization of DNA. The biological and clinical consequences of abnormal concentrations are DNA cleavage leading to diseases and cancer. Carcinogenesis and cell growth are also magnesium-ion concentration dependent. Several reports point out that the interaction of magnesium in the presence of other metal ions showed that there is synergism with Li and Mn, but there is magnesium antagonism in DNA binding with the essential metal ions in the order: Zn>Mg>Ca. In the case of toxic metals such as Cd, Ga and Ni there is also antagonism for DNA binding. It was found from radiolysis of deaerated aqueous solutions of the nucleoside 5'-guanosine monophosphate (5'-GMP) in the presence as well as in the absence of magnesium ions that, although the addition of hydroxyl radicals (*OH) has been increased by 2-fold, the opening of the imidazole ring of the guanine base was prevented. This effect was due to the binding of Mg2+ ions to N7 site of the molecule by stabilizing the five-member ring imitating cis-platinum. It was also observed using Fourier Transform Infrared spectroscopy, Raman spectroscopy and Fast Atom Bombardment mass spectrometry that *OH radicals subtract H atoms from the C1', C4' and C5' sites of the nucleotide. Irradiation of 5'-GMP in the presence of oxygen (2.5 x 10(-4) M) shows that magnesium is released from the complex. There is spectroscopic evidence that

Treatment of acid and sulphate-rich effluents in an integrated biological/chemical process

CSIR Research Space (South Africa)

Maree, JP

2004-04-01

Full Text Available .4 g SO4/(l.d). The rate of biological sulphate removal was found to be directly related to the square root of sulphate, COD and VSS concentrations respectively, and inversely proportional to sulphide concentration. The practical value of simultaneous...

Comparison of the effects of the K(+)-channel openers cromakalim and minoxidil sulphate on vascular smooth muscle.

Science.gov (United States)

Wickenden, A. D.; Grimwood, S.; Grant, T. L.; Todd, M. H.

1991-01-01

1 The actions of the potassium channel openers, cromakalim and minoxidil sulphate, were compared in a range of isolated blood vessel preparations. 2 Cromakalim and minoxidil sulphate inhibited spontaneous mechanical activity of the guinea-pig portal vein and relaxed the noradrenaline precontracted rat aorta with similar potency. In contrast, minoxidil sulphate was less potent than cromakalim in inhibiting spontaneous activity in the rat portal vein and was essentially inactive in the noradrenaline precontracted rat mesenteric artery and rabbit aorta. 3 Minoxidil sulphate did not antagonize the effects of cromakalim in the rabbit aorta indicating it was not acting as a partial 'agonist'. 4 Charybdotoxin, noxiustoxin and rubidium failed to discriminate between cromakalim and minoxidil sulphate indicating that the apparently selective effects of minoxidil sulphate were not mediated by either Ca(2+)-activated potassium channels, delayed rectifiers or rubidium impermeable potassium channels. 5 Glibenclamide antagonized the effects of cromakalim in an apparently competitive manner whereas the effects of minoxidil sulphate were antagonized in a non-competitive manner. The involvement of subtypes of ATP-sensitive potassium channels is discussed. PMID:1878752

Sodium Sulphate Effect on Cement Produced with Building Stone Waste

Directory of Open Access Journals (Sweden)

Emre Sancak

2015-01-01

Full Text Available In this study, the blended cements produced by using the building stone waste were exposed to sulphate solution and the cement properties were examined. Prepared mortar specimens were cured under water for 28 days and then they were exposed to three different proportions of sodium sulphate solution for 125 days. Performances of cements were determined by means of compressive strength and tensile strength tests. The broken parts of some mortar bars were examined with scanning electron microscope (SEM. Besides, they were left under moist atmosphere and their length change was measured and continuously monitored for period of 125 days. In blended cements, solely cements obtained by replacing 10–20% of diatomites gave similar strength values with ordinary Portland cement (CEM I 42.5R at the ages of 7, 28, and 56 days. In all mortar specimens that included either waste andesite (AP or marble powder (MP showed best performance against very severe effective sodium sulphate solutions (13500 mg/L.

Thermal decomposition of hydrotalcite with chromate, molybdate or sulphate in the interlayer

Energy Technology Data Exchange (ETDEWEB)

Frost, Ray L. [Inorganic Materials Research Program, School of Physical and Chemical Sciences, Queensland University of Technology, GPO Box 2434, Brisbane Queensland 4001 (Australia)]. E-mail: r.frost@qut.edu.au; Musumeci, Anthony W. [Inorganic Materials Research Program, School of Physical and Chemical Sciences, Queensland University of Technology, GPO Box 2434, Brisbane Queensland 4001 (Australia); Bostrom, Thor [Inorganic Materials Research Program, School of Physical and Chemical Sciences, Queensland University of Technology, GPO Box 2434, Brisbane Queensland 4001 (Australia); Adebajo, Moses O. [Inorganic Materials Research Program, School of Physical and Chemical Sciences, Queensland University of Technology, GPO Box 2434, Brisbane Queensland 4001 (Australia); Weier, Matt L. [Inorganic Materials Research Program, School of Physical and Chemical Sciences, Queensland University of Technology, GPO Box 2434, Brisbane Queensland 4001 (Australia); Martens, Wayde [Inorganic Materials Research Program, School of Physical and Chemical Sciences, Queensland University of Technology, GPO Box 2434, Brisbane Queensland 4001 (Australia)

2005-05-15

The thermal decomposition of hydrotalcites with chromate, molybdate and sulphate in the interlayer has been studied using thermogravimetric analysis coupled to a mass spectrometer measuring the gas evolution. X-ray diffraction shows the hydrotalcites have a d(0 0 3) spacing of 7.98 A with very small differences in the d-spacing between the three hydrotalcites. XRD was also used to determine the products of the thermal decomposition. For the sulphate-hydrotalcite decomposition the products were MgO and a spinel MgAl{sub 2}O{sub 4}, for the chromate interlayered hydrotalcite MgO, Cr{sub 2}O{sub 3} and spinel. For the molybdate interlayered hydrotalcite the products were MgO, spinel and MgMoO{sub 4}. EDX analyses enabled the formula of the hydrotalcites to be determined. Two processes are observed in the thermal decomposition namely dehydration and dehydroxylation and for the case of the sulphate interlayered hydrotalcite, a third process is the loss of sulphate. Both the dehydration and dehydroxylation take place in three steps each for each of the hydrotalcites.

Porous bioresorbable magnesium as bone substitute

Energy Technology Data Exchange (ETDEWEB)

Wen, C.E.; Yamada, Y.; Shimojima, K.; Chino, Y.; Hosokawa, H.; Mabuchi, M. [Inst. for Structural and Engineering Materials, National Inst. of Advanced Industrial Science and Technology, Nagoya (Japan)

2003-07-01

Recently magnesium has been recognized as a very promising biomaterial for bone substitutes because of its excellent properties of biocompatibility, biodegradability and bioresorbability. In the present study, magnesium foams were fabricated by using a powder metallurgical process. Scanning electron microscopy equipped with energy dispersive X-ray spectrometer (EDS) and compressive tester were used to characterize the porous magnesium. Results show that the Young's modulus and the peak stress of the porous magnesium increase with decreasing porosity and pore size. This study suggests that the mechanical properties of the porous magnesium with the low porosity of 35% and/or with the small pore size of about 70 {mu}m are close to those of human cancellous bones. (orig.)

Small for Gestational Age and Magnesium: Intrauterine magnesium deficiency may induce metabolic syndrome in later life

Directory of Open Access Journals (Sweden)

Junji Takaya

2015-12-01

Full Text Available Magnesium deficiency during pregnancy as a result of insufficient or low intake of magnesium is common in developing and developed countries. Previous reports have shown that intracellular magnesium of cord blood platelets is lower among small for gestational age (SGA groups than that of appropriate for gestational age (AGA groups, suggesting that intrauterine magnesium deficiency may result in SGA. Additionally, the risk of adult-onset diseases such as insulin resistance syndrome is greater among children whose mothers were malnourished during pregnancy, and who consequently had a low birth weight. In a number of animal models, poor nutrition during pregnancy leads to offspring that exhibit pathophysiological changes similar to human diseases. The offspring of pregnant rats fed a magensium restricted diet have developed hypermethylation in the hepatic 11β-hydroxysteroid dehydrogenase-2 promoter. These findings indicate that maternal magnesium deficiencies during pregnancy influence regulation of non-imprinted genes by altering the epigenetic regulation of gene expression, thereby inducing different metabolic phenotypes. Magnesium deficiency during pregnancy may be responsible for not only maternal and fetal nutritional problems, but also lifelong consequences that affect the offspring throughout their life. Epidemiological, clinical, and basic research on the effects of magnesium deficiency now indicates underlying mechanisms, especially epigenetic processes.

Magnesium in Prevention and Therapy

Science.gov (United States)

Gröber, Uwe; Schmidt, Joachim; Kisters, Klaus

2015-01-01

Magnesium is the fourth most abundant mineral in the body. It has been recognized as a cofactor for more than 300 enzymatic reactions, where it is crucial for adenosine triphosphate (ATP) metabolism. Magnesium is required for DNA and RNA synthesis, reproduction, and protein synthesis. Moreover, magnesium is essential for the regulation of muscular contraction, blood pressure, insulin metabolism, cardiac excitability, vasomotor tone, nerve transmission and neuromuscular conduction. Imbalances in magnesium status—primarily hypomagnesemia as it is seen more common than hypermagnesemia—might result in unwanted neuromuscular, cardiac or nervous disorders. Based on magnesium’s many functions within the human body, it plays an important role in prevention and treatment of many diseases. Low levels of magnesium have been associated with a number of chronic diseases, such as Alzheimer’s disease, insulin resistance and type-2 diabetes mellitus, hypertension, cardiovascular disease (e.g., stroke), migraine headaches, and attention deficit hyperactivity disorder (ADHD). PMID:26404370

Corrosion of Magnesium in Multimaterial System

Energy Technology Data Exchange (ETDEWEB)

Joshi, Vineet V.; Agnew, Sean

2017-08-16

The TMS Magnesium Committee has been actively involved in presenting cutting-edge research and development and the latest trends related to magnesium and its alloys to industry and academia. Topics including magnesium alloy development, applications, mechanism of deformation and corrosion, thermomechanical processing, modelling, etc. have been captured year after year through the Magnesium Technology symposium and conference proceedings at TMS and through special topics in JOM. Every year, based on the unanimous endorsement from the industry and academia, a topic is selected to address the latest developments within this subject in JOM. In continuation with last year’s coverage of Advances and Achievements in In-Situ Analysis of Corrosions and Structure–Property Relationship in Mg Alloys,[1] this year’s topic focuses on the Corrosion of Magnesium in Multimaterial Systems. Magnesium, the lightest of all the structural materials, has garnered much interest in the transportation, electronics packaging, defense equipments and industries alike and are more commonly being incorporated in multimaterial design concepts.[2-4] However, the application of the same is limited due to its highly corrosive nature, and understanding and mitigating the corrosion of magnesium has been a major research challenge.

The reference range of serum, plasma and erythrocyte magnesium

Directory of Open Access Journals (Sweden)

Suzanna Immanuel

2006-12-01

Full Text Available The interest in the clinical importance of serum magnesium level has just recently begun with the analysis and findings of abnormal magnesium level in cardiovascular, metabolic and neuromuscular disorder. Although the serum level does not reflect the body magnesium level, but currently, only serum magnesium determination is widely used. Erythrocyte magnesium is considered more sensitive than serum magnesium as it reflects intracellular magnesium status. According to NCCLS (National Committee for Clinical Laboratory Standards every laboratory is recommended to have its own reference range for the tests it performs, including magnesium determination. The reference range obtained is appropriate for the population and affected by the method and technique. This study aimed to find the reference range of serum and plasma magnesium and also intracellular magnesium i.e. erythrocyte magnesium by direct method, and compare the results of serum and plasma magnesium. Blood was taken from 114-blood donor from Unit Transfusi Darah Daerah (UTDD Budhyarto Palang Merah Indonesia (PMI DKI Jakarta, consisted of 57 male and 57 female, aged 17 – 65 years, clinically healthy according to PMI donor criteria. Blood was taken from blood set, collected into 4 ml vacuum tube without anticoagulant for serum magnesium determination and 3 ml vacuum tube with lithium heparin for determination of erythrocyte and plasma magnesium Determination of magnesium level was performed with clinical chemistry auto analyzer Hitachi 912 by Xylidil Blue method colorimetrically. This study showed no significant difference between serum and heparinized plasma extra cellular magnesium. The reference range for serum or plasma magnesium was 1.30 – 2.00 mEq/L and for erythrocyte magnesium was 4.46 - 7.10 mEq/L. (Med J Indones 2006; 15:229-35Keywords: Reference range, extracellular magnesium, intracellular magnesium

Magnesium Tube Hydroforming

International Nuclear Information System (INIS)

Liewald, M.; Pop, R.; Wagner, S.

2007-01-01

Magnesium alloys can be considered as alternative materials towards achieving light weight structures with high material stiffness. The formability of two magnesium alloys, viz. AZ31 and ZM21 has been experimentally tested using the IHP forming process. A new die set up for hot IHP forming has been designed and the process experimentally investigated for temperatures up to 400 deg. C. Both alloys exhibit an increase in formability with increasing forming temperature. The effect of annealing time on materials forming properties shows a fine grained structure for sufficient annealing times as well as deterioration with a large increase at the same time. The IHP process has also been used to demonstrate practicability and feasibility for real parts from manufacture a technology demonstrator part using the magnesium alloy ZM21

Extraction and characterization of cellulose nano whiskers from balsa wood; Extracao e caracterizacao de nanocristais de celulose obtidos da madeira balsa

Energy Technology Data Exchange (ETDEWEB)

Morelli, Carolina L.; Bretas, Rosario E.S., E-mail: bretas@ufscar.br [Universidade Federal de Sao Carlos - UFSCar, Sao Carlos, SP (Brazil); Marconcini, Jose M. [Embrapa Instrumentacao, Sao Carlos, SP (Brazil); Pereira, Fabiano V. [Universidade Federal de Minas Gerais - UFMG, Belo Horizonte, MG (Brazil); Branciforti, Marcia C. [Universidade de Sao Paulo - USP, Sao Carlos, SP (Brazil)

2011-07-01

In this study cellulose nano whiskers were obtained from balsa wood. For this purpose, fibers of balsa wood were subjected to hydrolysis reactions for lignin and hemi cellulose digestion and acquisition of nano-scale cellulose. Cellulose nano crystals obtained had medium length and thickness of 176 nm and 7 nm respectively. Infrared spectroscopy and x-ray diffraction showed that the process used for extracting nano whiskers could digest nearly all the lignin and hemi cellulose from the balsa fiber and still preserve the aspect ratio and crystallinity, satisfactory enough for future application in polymer nano composites. Thermogravimetry showed that the onset temperature of thermal degradation of cellulose nano crystals (226 degree C) was higher than the temperature of the balsa fiber (215 degree C), allowing its use in molding processes with many polymers from the molten state.(author)

Magnesium-phosphate-glass cements with ceramic-type properties

Science.gov (United States)

Sugama, T.; Kukacka, L.E.

1982-09-23

Rapid setting magnesium phosphate (Mg glass) cementitious materials consisting of magnesium phosphate cement paste, polyborax and water-saturated aggregate, exhibits rapid setting and high early strength characteristics. The magnesium glass cement is prepared from a cation-leachable powder and a bivalent metallic ion-accepting liquid such as an aqueous solution of diammonium phosphate and ammonium polyphosphate. The cation-leachable powder includes a mixture of two different magnesium oxide powders processed and sized differently which when mixed with the bivalent metallic ion-accepting liquid provides the magnesium glass cement consisting primarily of magnesium ortho phosphate tetrahydrate, with magnesium hydroxide and magnesium ammonium phosphate hexahydrate also present. The polyborax serves as a set-retarder. The resulting magnesium mono- and polyphosphate cements are particularly suitable for use as a cementing matrix in rapid repair systems for deteriorated concrete structures as well as construction materials and surface coatings for fireproof structures.

Magnesium phosphate glass cements with ceramic-type properties

Science.gov (United States)

Sugama, Toshifumi; Kukacka, Lawrence E.

1984-03-13

Rapid setting magnesium phosphate (Mg glass) cementitious materials consisting of magnesium phosphate cement paste, polyborax and water-saturated aggregate exhibiting rapid setting and high early strength characteristics. The magnesium glass cement is prepared from a cation-leachable powder and a bivalent metallic ion-accepting liquid such as an aqueous solution of diammonium phosphate and ammonium polyphosphate. The cation-leachable powder includes a mixture of two different magnesium oxide powders processed and sized differently which when mixed with the bivalent metallic ion-accepting liquid provides the magnesium glass cement consisting primarily of magnesium ortho phosphate tetrahydrate, with magnesium hydroxide and magnesium ammonium phosphate hexahydrate also present. The polyborax serves as a set-retarder. The resulting magnesium mono- and polyphosphate cements are particularly suitable for use as a cementing matrix in rapid repair systems for deteriorated concrete structures as well as construction materials and surface coatings for fireproof structures.

Magnesium deficiency and increased inflammation: current perspectives

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Nielsen FH

2018-01-01

Full Text Available Forrest H Nielsen Research Nutritionist Consultant, Grand Forks, ND, USA Abstract: Animal studies have shown that magnesium deficiency induces an inflammatory response that results in leukocyte and macrophage activation, release of inflammatory cytokines and acute-phase proteins, and excessive production of free radicals. Animal and in vitro studies indicate that the primary mechanism through which magnesium deficiency has this effect is through increasing cellular Ca2+, which is the signal that results in the priming of cells to give the inflammatory response. Primary pro-inflammatory cytokines such as tumor necrosis factor-α and interleukin (IL-1; the messenger cytokine IL-6; cytokine responders E-selectin, intracellular adhesion molecule-1 and vascular cell adhesion molecule-1; and acute-phase reactants C-reactive protein and fibrinogen have been determined to associate magnesium deficiency with chronic low-grade inflammation (inflammatory stress. When magnesium dietary intake, supplementation, and/or serum concentration suggest/s the presence of magnesium deficiency, it often is associated with low-grade inflammation and/or with pathological conditions for which inflammatory stress is considered a risk factor. When magnesium intake, supplementation, and/or serum concentration suggest/s an adequate status, magnesium generally has not been found to significantly affect markers of chronic low-grade inflammation or chronic disease. The consistency of these findings can be modified by other nutritional and metabolic factors that affect inflammatory and oxidative stress. In spite of this, findings to date provide convincing evidence that magnesium deficiency is a significant contributor to chronic low-grade inflammation that is a risk factor for a variety of pathological conditions such as cardiovascular disease, hypertension, and diabetes. Because magnesium deficiency commonly occurs in countries where foods rich in magnesium are not consumed in

Effect of Magnesium Hydride on the Corrosion Behavior of Pure Magnesium in 0.1 M NaCl Solution

OpenAIRE

Xu, Shanna; Dong, Junhua; Ke, Wei

2010-01-01

The effect of magnesium hydride on the corrosion behavior of pure magnesium in 0.1 M NaCl solution was investigated using the gas collection method, potentiostatic current decay test, and in situ Raman spectrum. The formation of magnesium hydride (MgH2, Mg2H4) was observed at the cathodic region. Applying anodic potential leads to decomposition of magnesium hydride. Magnesium hydride plays an important role on the negative difference effect (NDE) in both the cathodic and anodic regions.

Electrospun composite nanofiber membrane of poly(l-lactide) and surface grafted chitin whiskers: Fabrication, mechanical properties and cytocompatibility.

Science.gov (United States)

Liu, Hua; Liu, Wenjun; Luo, Binghong; Wen, Wei; Liu, Mingxian; Wang, Xiaoying; Zhou, Changren

2016-08-20

To improve both the mechanical properties and cytocompatibility of poly(l-lactide) (PLLA), rod-like chitin whiskers (CHWs) were prepared, and subsequently surface modified with l-lactide to obtain grafted CHWs (g-CHWs). Then, CHWs and g-CHWs were further introduced into PLLA matrix to fabricate CHWs/PLLA and g-CHWs/PLLA nanofiber membranes by electrospinning technique. Morphologies and properties of the CHWs and g-CHWs were characterized. The surface-grafted PLLA chains played an important role in improving interfacial interaction between the whiskers and PLLA matrix. The g-CHWs dispersed more uniformly in matrix than CHWs, and the as-prepared g-CHWs/PLLA nanofiber membrane showed relative smooth and uniform fiber. As a result, the tensile strength and modulus of the g-CHWs/PLLA nanofiber membrane were obviously superior to those of the pure PLLA and CHWs/PLLA nanofiber membranes. Cells culture results indicated that g-CHWs/PLLA nanofiber membrane is more effectively in promoting MC3T3-E1 cells adhesion, spreading and proliferation than pure PLLA and CHWs/PLLA nanofiber membrane. Copyright © 2016 Elsevier Ltd. All rights reserved.

Molecular structure of dextran sulphate sodium in aqueous environment

Science.gov (United States)

Yu, Miao; Every, Hayley A.; Jiskoot, Wim; Witkamp, Geert-Jan; Buijs, Wim

2018-03-01

Here we propose a 3D-molecular structural model for dextran sulphate sodium (DSS) in a neutral aqueous environment based on the results of a molecular modelling study. The DSS structure is dominated by the stereochemistry of the 1,6-linked α-glucose units and the presence of two sulphate groups on each α-glucose unit. The structure of DSS can be best described as a helix with various patterns of di-sulphate substitution on the glucose rings. The presence of a side chain does not alter the 3D-structure of the linear main chain much, but affects the overall spatial dimension of the polymer. The simulated polymers have a diameter similar to or in some cases even larger than model α-hemolysin nano-pores for macromolecule transport in many biological processes, indicating a size-limited translocation through such pores. All results of the molecular modelling study are in line with previously reported experimental data. This study establishes the three-dimensional structure of DSS and summarizes the spatial dimension of the polymer, serving as the basis for a better understanding on the molecular level of DSS-involved electrostatic interaction processes with biological components like proteins and cell pores.

Corrosion and protection of magnesium alloys

Energy Technology Data Exchange (ETDEWEB)

Ghali, E. [Laval Univ., Quebec City, PQ (Canada). Dept. of Mining and Metallurgy

2000-07-01

The oxide film on magnesium offers considerable surface protection in rural and some industrial environments and the corrosion rate lies between that of aluminum and low carbon steels. Galvanic coupling of magnesium alloys, high impurity content such as Ni, Fe, Cu and surface contamination are detrimental for corrosion resistance of magnesium alloys. Alloying elements can form secondary particles which are noble to the Mg matrix, thereby facilitating corrosion, or enrich the corrosion product thereby possibly inhibiting the corrosion rate. Bimetallic corrosion resistance can be increased by fluxless melt protection, choice of compatible alloys, insulating materials, and new high-purity alloys. Magnesium is relatively insensible to oxygen concentration. Pitting, corrosion in the crevices, filiform corrosion are observed. Granular corrosion of magnesium alloys is possible due to the cathodic grain-boundary constituent. More homogeneous microstructures tend to improve corrosion resistance. Under fatigue loading conditions, microcrack initiation in Mg alloys is related to slip in preferentially oriented grains. Coating that exclude the corrosive environments can provide the primary defense against corrosion fatigue. Magnesium alloys that contain neither aluminum nor zinc are the most SCC resistant. Compressive surface residual stresses as that created by short peening increase SCC resistance. Cathodic polarization or cladding with a SCC resistant sheet alloy are good alternatives. Effective corrosion prevention for magnesium alloy components and assemblies should start at the design stage. Selective surface preparation, chemical treatment and coatings are recommended. Oil application, wax coating, anodizing, electroplating, and painting are possible alternatives. Recently, it is found that a magnesium hydride layer, created on the magnesium surface by cathodic charging in aqueous solution is a good base for painting. (orig.)

Effect of Magnesium Hydride on the Corrosion Behavior of Pure Magnesium in 0.1 M NaCl Solution

Directory of Open Access Journals (Sweden)

Shanna Xu

2010-01-01

Full Text Available The effect of magnesium hydride on the corrosion behavior of pure magnesium in 0.1 M NaCl solution was investigated using the gas collection method, potentiostatic current decay test, and in situ Raman spectrum. The formation of magnesium hydride (MgH2, Mg2H4 was observed at the cathodic region. Applying anodic potential leads to decomposition of magnesium hydride. Magnesium hydride plays an important role on the negative difference effect (NDE in both the cathodic and anodic regions.

21 CFR 582.5431 - Magnesium oxide.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Magnesium oxide. 582.5431 Section 582.5431 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Supplements 1 § 582.5431 Magnesium oxide. (a) Product. Magnesium oxide. (b) Conditions of use. This substance...

21 CFR 582.1431 - Magnesium oxide.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Magnesium oxide. 582.1431 Section 582.1431 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1431 Magnesium oxide. (a) Product. Magnesium oxide. (b) Conditions of use. This substance is...

21 CFR 582.5443 - Magnesium sulfate.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Magnesium sulfate. 582.5443 Section 582.5443 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Supplements 1 § 582.5443 Magnesium sulfate. (a) Product. Magnesium sulfate. (b) Conditions of use. This...

Correlation analysis between sulphate content and leaching of sulphates in recycled aggregates from construction and demolition wastes.

Science.gov (United States)

Barbudo, Auxi; Galvín, Adela P; Agrela, Francisco; Ayuso, Jesús; Jiménez, Jose Ramón

2012-06-01

In some recycled aggregates applications, such as component of new concrete or roads, the total content of soluble sulphates should be measured and controlled. Restrictions are usually motivated by the resistance or stability of the new structure, and in most cases, structural concerns can be remedied by the use of techniques such as sulphur-resistant cements. However, environmental risk assessment from recycling and reuse construction products is often forgotten. The purpose of this study is to analyse the content of soluble sulphate on eleven recycled aggregates and six samples prepared in laboratory by the addition of different gypsum percentages. As points of reference, two natural aggregates were tested. An analysis of the content of the leachable amount of heavy metals regulated by European regulation was included. As a result, the correlation between solubility and leachability data allow suggest a limiting gypsum amount of 4.4% on recycled aggregates. This limit satisfies EU Landfill Directive criteria, which is currently used as reference by public Spanish Government for recycled aggregates in construction works. Copyright © 2012 Elsevier Ltd. All rights reserved.

Sulphated glycosaminoglycans and proteoglycans in the developing vertebral column of juvenile Atlantic salmon (Salmo salar).

Science.gov (United States)

Hannesson, Kirsten O; Ytteborg, Elisabeth; Takle, Harald; Enersen, Grethe; Bæverfjord, Grete; Pedersen, Mona E

2015-08-01

In the present study, the distribution of sulphated glycosaminoglycans (GAGs) in the developing vertebral column of Atlantic salmon (Salmo salar) at 700, 900, 1100 and 1400 d° was examined by light microscopy. The mineralization pattern was outlined by Alizarin red S and soft structures by Alcian blue. The temporal and spatial distribution patterns of different types of GAGs: chondroitin-4-sulphate/dermatan sulphate, chondroitin-6-sulphate, chondroitin-0-sulphate and keratan sulphate were addressed by immunohistochemistry using monoclonal antibodies against the different GAGs. The specific pattern obtained with the different antibodies suggests a unique role of the different GAG types in pattern formation and mineralization. In addition, the distribution of the different GAG types in normal and malformed vertebral columns from 15 g salmon was compared. A changed expression pattern of GAGs was found in the malformed vertebrae, indicating the involvement of these molecules during the pathogenesis. The molecular size of proteoglycans (PGs) in the vertebrae carrying GAGs was analysed with western blotting, and mRNA transcription of the PGs aggrecan, decorin, biglycan, fibromodulin and lumican by real-time qPCR. Our study reveals the importance of GAGs in development of vertebral column also in Atlantic salmon and indicates that a more comprehensive approach is necessary to completely understand the processes involved.

Imparting passivity to vapor deposited magnesium alloys

Science.gov (United States)

Wolfe, Ryan C.

Magnesium has the lowest density of all structural metals. Utilization of low density materials is advantageous from a design standpoint, because lower weight translates into improved performance of engineered products (i.e., notebook computers are more portable, vehicles achieve better gas mileage, and aircraft can carry more payload). Despite their low density and high strength to weight ratio, however, the widespread implementation of magnesium alloys is currently hindered by their relatively poor corrosion resistance. The objective of this research dissertation is to develop a scientific basis for the creation of a corrosion resistant magnesium alloy. The corrosion resistance of magnesium alloys is affected by several interrelated factors. Among these are alloying, microstructure, impurities, galvanic corrosion effects, and service conditions, among others. Alloying and modification of the microstructure are primary approaches to controlling corrosion. Furthermore, nonequilibrium alloying of magnesium via physical vapor deposition allows for the formation of single-phase magnesium alloys with supersaturated concentrations of passivity-enhancing elements. The microstructure and surface morphology is also modifiable during physical vapor deposition through the variation of evaporation power, pressure, temperature, ion bombardment, and the source-to-substrate distance. Aluminum, titanium, yttrium, and zirconium were initially chosen as candidates likely to impart passivity on vapor deposited magnesium alloys. Prior to this research, alloys of this type have never before been produced, much less studied. All of these metals were observed to afford some degree of corrosion resistance to magnesium. Due to the especially promising results from nonequilibrium alloying of magnesium with yttrium and titanium, the ternary magnesium-yttrium-titanium system was investigated in depth. While all of the alloys are lustrous, surface morphology is observed under the scanning

Separation of magnesium from magnesium chloride and zirconium and/or hafnium subchlorides in the production of zirconium and/or hafnium sponge metal

International Nuclear Information System (INIS)

Abodishish, H.A.M.; Adams, R.J.; Kearl, S.R.

1992-01-01

This patent describes the producing of a refractory metal wherein a sponge refractory metal is produced as an intermediate product by the use of magnesium with the incidental production of magnesium chloride, and wherein residual magnesium is separated from the magnesium chloride and from refractory metal to a vacuum distillation step which fractionally distills the magnesium, the magnesium chloride, and the metal sub-chlorides; the steps of: recovering fractionally distilled vapors of magnesium chloride and metal sub-chlorides from a sponge refractory metal; separately condensing the vapors as separately recovered; and recycling the separately recovered magnesium at a purity of at least about 96%

Sulphation of calcium-based sorbents in circulating fluidised beds under oxy-fuel combustion conditions

Energy Technology Data Exchange (ETDEWEB)

Francisco Garcia-Labiano; Luis F. de Diego; Alberto Abad; Pilar Gayan; Margarita de las Obras-Loscertales; Aranzazu Rufas; Juan Adanez [Instituto de Carboquimica (CSIC), Zaragoza (Spain). Dept. Energy and Environment

2009-07-01

Sulphur Retention (SR) by calcium-based sorbents is a process highly dependent on the temperature and CO{sub 2} concentration. In circulating fluidised beds combustors (CFBC's) operating under oxy-fuel conditions, the sulphation process takes place in atmospheres enriched in CO{sub 2} with bed concentrations that can vary from 40 to 95%. Under so high CO{sub 2} concentrations, very different from that in conventional coal combustion atmosphere with air, the calcination and sulphation behaviour of the sorbent must be defined to optimise the SR process in the combustor. The objective of this work was to determine the SO{sub 2} retention capacity of a Spanish limestone at typical oxy-fuel conditions in CFBC's. Long term duration tests of sulphation (up to 24 h), to simulate the residence time of sorbents in CFBC's, were carried out by thermogravimetric analysis (TGA). Clear behaviour differences were found under calcining and non-calcining conditions. Especially relevant was the result obtained at calcining conditions but close to the thermodynamic temperature given for sorbent calcination. This situation must be avoided in CFBC's because the CO{sub 2} produced inside the particle during calcination can destroy the particles if a non-porous sulphate product layer has been formed around the particle. The effect of the main variables on the sorbent sulphation such as SO{sub 2} concentration, temperature, and particle size were analysed in the long term TGA tests. These data were also used to determine the kinetic parameters for the sulphation under oxy-fuel combustion conditions, which were able to adequately predict the sulphation conversion values in a wide range of operating conditions. 20 refs., 5 figs., 2 tabs.

Spore-forming, Desulfosporosinus-like sulphate-reducing bacteria from a shallow aquifer contaminated with gasoline.

Science.gov (United States)

Robertson, W J; Franzmann, P D; Mee, B J

2000-02-01

Previous studies on the geochemistry of a shallow unconfined aquifer contaminated with hydrocarbons suggested that the degradation of some hydrocarbons was linked to bacterial sulphate reduction. There was attenuation of naphthalene, 1,3,5-trimethylbenzene (TMB), toluene, p-xylene and ethylbenzene in the groundwater with concomitant loss of sulphate. Here, the recovery of eight strains of sulphate-reducing bacteria (SRB) from the contaminated site is reported. All were straight or curved rod-shaped cells which formed endospores. Amplification and sequencing of the 16S rDNA indicated that the strains were all sulphate reducers of the Gram-positive line of descent, and were most closely related to Desulfosporosinus (previously Desulfotomaculum) orientis DSM 8344 (97-98.9% sequence similarity). The strains clustered in three phylogenetic groups based on 16S rRNA sequences. Whole cell fatty acid compositions were similar to those of D. orientis DSM 8344, and were consistent with previous studies of fatty acids in soil and groundwater from the site. Microcosms containing groundwater from this aquifer indicated a role for sulphate reduction in the degradation of [ring-UL-14C]toluene, but not for the degradation of [UL-14C]benzene which could also be degraded by the microcosms. Adding one of the strains that was isolated from the groundwater (strain T2) to sulphate-enriched microcosms increased the rate of toluene degradation four- to 10-fold but had no effect on the rate of benzene degradation. The addition of molybdate, an inhibitor of sulphate reduction, to the groundwater samples decreased the rate of toluene mineralization. There was no evidence to support the mineralization of [UL-14C]benzene, [ring-UL-14C]toluene or unlabelled m-xylene, p-xylene, ethylbenzene, TMB or naphthalene by any of the strains in pure culture. Growth of all the strains was completely inhibited by 100 micromol l-1 TMB.

Der er evidens for profylaktisk magnesiumsulfat som neuroprotektion ved præmature fødsler