Effect of mechanical loading on the I-c degradation behavior of Bi-2223 tapes

During the winding process of HTS coils the tapes of Bi-2223 are subjected to the influence of bending strain, axial strain, compressive force and torsional deformation resulting in I-c degradation. In the literature the effects of the individual strain components are separately analyzed in spite of during coil winding and energizing the strain-stress effects are combined. In this work using commercial tapes of Bi-2223 Ag/AgMg with and without stainless steel reinforcement several samples were wound on cylindrical FRP G-10 holder in which different combined strains are applied. Measurements of I - V characteristic curves are done to determine the degree of critical current degradation and the operational limits. The results are compared with the I, values of short samples and other specimens subjected to deformation generated by loading types such as tensile and bending strain.

Friction losses in valves and fittings for viscoplastic fluids

Data on pressure drop were obtained in stainless steel, sanitary fittings and valves during laminar and turbulent flow of aqueous suspensions of sucrose and bentonite. The rheological properties of these suspensions were determined and the Bingham model provided the best fitting with the experimental data. Friction losses were measured in fully- and partially-open butterfly and plug valves, bends and union. Values of loss coefficients (k(f)) were calculated and correlated as functions of the classical Reynolds number and the Reynolds number proposed by Govier and Aziz (1972) for viscoplastic fluids. The two-k method and a new proposed model presented the best adjustments for the Govier and Aziz Reynolds number, and Hedstrom and classical Reynolds numbers, respectively.

LATERAL PARABRACHIAL SEROTONERGIC MECHANISMS - ANGIOTENSIN-INDUCED PRESSOR AND DRINKING RESPONSES

This study investigated the effects of bilateral injections of serotonergic receptor ligands into the lateral parabrachial nucleus (LPBN) on the presser and dipsogenic responses induced by intracerebroventricular (icv) injection of angiotensin II (ANG II). Rats with stainless steel cannulas implanted bilaterally into the LPBN and into the left lateral ventricle were used to study icy ANG II-induced water intake and presser responses. Pretreatment with the serotonergic 5-HT1/5-HT2 receptor antagonist methysergide (1-8 mu g/200 nl) bilaterally injected into the LPBN increased the water intake induced by icv ANG II (50 ng/mu l) administered via the lateral ventricle, but pretreatment with methysergide (4 mu g/200 nl) did not change the presser response produced by icy ANG II. After bilateral injection of either serotonin (5-HT, 5 mu g/200 nl) or the serotonergic 5-HT2a/5-HT2c receptor agonist (+/-)-2,5-dimetoxy-4-iodoamphetamine hydrochloride (DOI; 0.5-10 mu g/200 nl) into the LPBN, the water intake induced by ANG II was significantly reduced. These results are consistent with other observations indicating that the LPBN is associated with inhibitory mechanisms controlling water intake induced by ANG II treatment and suggest that serotonergic pathways may be involved in this effect.

ROLE OF LATERAL HYPOTHALAMUS ON FLUID, ELECTROLYTE, AND CARDIOVASCULAR-RESPONSES TO ACTIVATION OF THE MSA

In this study we investigated the influence of electrolytic lesion or of opioid agonist injections into the lateral hypothalamus (LH) on the dipsogenic, natriuretic, kaliuretic, antidiuretic, presser, and bradycardic effects of cholinergic stimulation of the medial septal area (MSA) in rats. Sham- and LH-lesioned male Holtzman rats received a stainless steel cannula implanted into the LH. Other groups of rats had cannulas implanted simultaneously into the MSA and LH. Carbachol (2 nmol) injection into the MSA induced water intake, presser, and bradycardic responses. LH lesion reduced all of these effects (1-3 and 15-18 days). Previous injection of synthetic opiate agonist, FK-33824 (100 ng), into the LH reduced the water intake, natriuresis, kaliuresis, and presser responses induced by carbachol injected into the MSA. These data show that both electrolytic lesion or injection of an opiate agonist in the LH reduces the fluid-electrolyte and cardiovascular responses to cholinergic activation of the MSA. The involvement of LH with central excitatory and inhibitory mechanisms related to fluid-electrolytic and cardiovascular control is suggested.

Effect of a non-peptide angiotensin receptor antagonist on water intake caused by centrally administered carbachol in the rat

Angiotensin II (ANG II) administered centrally produces drinking by acting on subtype 1 ANG II (AT1) receptors, Carbachol, a cholinergic receptor agonist, also induces drinking behavior by a central action. In the present study we determined whether the response to carbachol also involves AT1 receptors. Male Holtzman rats (250-300 g) with stainless steel cannula implanted into the lateral ventricle (LV) were used. Water intake after injection of 0.15 M NaCl (1.0 mu l) into the LV was 0.2 +/- 0.01 ml/h (N = 8). The AT1 receptor antagonist DUP-753 (50 nmol/mu l) injected into the LV reduced water intake induced by ANG II (10 nmol/mu l) from 9.2 +/- 1.4 to 0.4 +/- 0.1 ml/h (N = 8), and water intake induced by carbachol (2 nmol/mu l) from 9.8 +/- 1.4 ml/h to 3.7 +/- 0.8 ml/h (N = 8), These results suggest that AT1 receptors play a role in the drinking behavior observed after central cholinergic stimulation in rats.

Effect of intracerebroventricular injection of ramipril on the drinking response caused by injection of noradrenaline into the third ventricle

We studied the effect of ramipril injected into the third ventricle (3rdV) on the control of water intake induced by injection of noradrenaline into the 3rdV of adult male Holtzman rats (250-300 g) implanted with a chronic stainless steel cannula into the 3rdV. The injection volume was always 1 mu l and was injected over a period of 30-60 sec. Control animals were injected with 0.15 M NaCl. After the injection of isotonic saline (control, 0.15 M NaCl) into the 3rdV, water ingestion was 0.3 +/- 0.1 ml/h. Ramipril (1 mu g/mu l) injected into the 3rdV prior to isotonic saline produced no changes in water ingestion (0.4 +/- 0.2 ml/h). The injection of noradrenaline (40 nmol/mu l) after isotonic saline induced an increase in water intake (3.0 +/- 1.1 ml/h). The prior injection of ramipril decreased this ingestion to 1.8 +/- 0.3 ml/h. These data show that the inhibition of converting enzyme in the brain reduces the water intake induced by catecholaminergic stimulation. We conclude that the brain is able to transform the prodrug ramipril into the active drug ramiprilat.

The influence of cervical finish line, internal relief, and cement type on the cervical adaptation of metal crowns

Objective: the aim of this investigation was to evaluate the cervical adaptation of metal crowns under several conditions, namely (1) variations in the cervical finish line of the preparation, (2) application of internal relief inside the crowns, and (3) cementation using different luting materials. Method and Materials: One hundred eighty stainless-steel master dies were prepared simulating full crown preparations: 60 in chamfer (CH), 60 in 135-degree shoulder (OB), and 60 in rounded shoulder (OR). The finish lines were machined at approximate dimensions of a molar tooth preparation (height: 5.5 mm; cervical diameter: 8 mm; occlusal diameter: 6.4 mm; taper degree: 6; and cervical finish line width: 0.8 mm). One hundred eighty corresponding copings with the same finish lines were fabricated. A 30-mu m internal relief was machined 0.5 mm above the cervical finish line in 90 of these copings. The fit of the die and the coping was measured from all specimens (L0) prior to cementation using an optical microscope. After manipulation of the 3 types of cements (zinc phosphate, glass-ionomer, and resin cement), the coping was luted on the corresponding standard master die under 5-kgf loading for 4 minutes. Vertical discrepancy was again measured (L1), and the difference between L1 and L0 indicated the cervical adaptation. Results: Significant influence of the finish line, cement type, and internal relief was observed on the cervical adaptation (P < .001). The CH type of cervical finish line resulted in the best cervical adaptation of the metal crowns regardless of the cement type either with or without internal relief (36.6 +/- 3 to 100.8 +/- 4 mu m) (3-way analysis of variance and Tukey's test, alpha = .05). The use of glass-ionomer cement resulted in the least cervical discrepancy (36.6 +/- 3 to 115 +/- 4 mu m) than those of other cements (45.2 +/- 4 to 130.3 +/- 2 mu m) in all conditions. Conclusion: the best cervical adaptation was achieved with the chamfer type of finish line. The internal relief improved the marginal adaptation significantly, and the glass-ionomer cement led to the best cervical adaptation, followed by zinc phosphate and resin cement.

A semiconductor strain gage tactile transducer

This paper describes the development of a semiconductor strain gage tactile transducer. It was designed with the goal of measuring finger forces without affecting the hand dexterity. The transducer structure was manufactured with stainless steel and has small dimensions ( 4 min diameter and I min thickness). It is light and suitable to connect to the finger pads. It has a device that prevents its damage when forces are applied. The semiconductor strain gage was used over due its small size and high sensitivity, although it has high temperature sensitivity. Theory, design and construction details are presented the signal conditioning circuit is very simple because the semiconductor strain gage sensitivity is high. It presents linear response from 0 to 100 N, 0.5 N resolution, fall time of 7.2 ms, good repeatability, and small hysteresis. The semiconductor strain gage transducer has characteristics that can make it very useful in Rehabilitation Engineering, Robotics, and Medicine.

Design, manufacturing, and testing of a Nb3Sn coil employing Ti alloy as structural material

We describe the design, manufacturing, and testing results of a Nb3Sn superconducting coil in which TiAIV alloys were used instead of stainless steel to reduce the magnetization contribution caused by the heat treatment for the A-15 Nb-3 Sn phase formation that affects the magnetic field homogeneity. Prior to the coil manufacturing several structural materials were studied and evaluated in terms of their mechanical and magnetic properties in as-worked, welded, and heat-treated conditions. The manufacturing process employed the wind-and-react technique followed by vacuum-pressure impregnation(VPI) at 1 MPa atm. The critical steps of the manufacturing process, besides the heat treatment and impregnation, are the wire splicing and joint manufacturing in which copper posts supported by Si3N4 ceramic were used. The coil was tested with and without a background NbTi coil and the results have shown performance exceeding the design quench current confirming the successful coil construction.

AV3V LESION REDUCES THE PRESSOR, DIPSOGENIC, AND NATRIURETIC RESPONSES TO VENTROMEDIAL HYPOTHALAMUS ACTIVATION

In the present study, we investigated the effect of anteroventral third ventricle (AV3V) lesion on pressor, tachycardic, dipsogenic, natriuretic, and kaliuretic responses induced by the injection of the cholinergic agonist carbachol into the ventromedial hypothalamic nucleus (VMH) of rats. Male rats with sham or AV3V lesion and a stainless steel cannula implanted into the VMH were used. Carbachol (2 nmol) injected into the VMH of sham rats produced pressor (32 +/- 4 mmHg). tachycardic (83 +/- 14 bpm), dipsogenic (8.2 +/- 1.1 ml/h). natriuretic (320 +/- 46-mu-Eq/120 min), and kaliuretic (155 +/- 20-mu-Eq/120 min) responses. In AV3V-lesioned rats (2 and 15 days), the pressor (4 +/- 2 and 15 +/- 2 mmHg. respectively), dipsogenic (0.3 +/-0.2 and 1.4 +/- 0.7 ml/h), natriuretic (17 +/- 7 and 99 +/- 21-mu-Eq/120 min), and kaliuretic (76 +/- 14 and 79 +/- 7-mu-Eq/120 min) responses induced by carbachol injection into the VMH were reduced. The tachycardia was also abolished (27 +/- 15 and -23 +/-29 bpm, respectively). These results show that the AV3V region is essential for the pressor, tachycardic, dipsogenic, natriuretic. and kaliuretic responses induced hy cholinergic activation of the VMH in rats.

ALPHA-ADRENERGIC PATHWAYS IN THE LATERAL HYPOTHALAMUS ARE IMPORTANT FOR THE DIPSOGENIC EFFECT OF CARBACHOL INJECTED INTO THE MEDIAL SEPTAL AREA

We studied the effect of the alpha(1)- and alpha(2)-adrenergic receptors of the lateral hypothalamus (LH) on the control of water intake induced by injection of carbachol into the medial septal area (MSA) of adult male Holtzman rats (250-300 g) implanted with chronic stainless steel cannulae into the LH and MSA. The volume of injection was always 1 mu l and was injected over a period of 30-60 s. For control, 0.15 M NaCl was used. Clonidine (20 nmol) but not phenylephrine (160 nmol) injected into the LH inhibited water intake induced by injection of carbachol (2 nmol) into the MSA, from 5.4 +/- 1.2 ml/h to 0.3 +/- 0.1 and 3.0 +/- 0.9 ml/h, respectively (N = 26). When we injected yohimbine (80 nmol) + clonidine (20 nmol) and prazosin (40 nmol) + clonidine (20 nmol) into theLH, water intake induced by injection of carbachol into the MSA was inhibited from 5.4 +/- 1.2 ml/h to 0.8 +/- 0.5 and 0.3 +/- 0.2 ml/h, respectively (N = 19). Water intake induced by carbachol (2 nmol) injected into the MSA was decreased by previous injection of yohimbine (80 nmol) + phenylephrine (160 nmol) and prazosin (40 nmol) + phenylephrine (l60 nmol) from 5.4 +/- 1.2 ml/h to 1.0 +/- 0.7 and 1.8 +/- 0.8 ml/h, respectively (N = 16). The cannula reached both the medial septal area in its medial portion and the lateral hypothalamus. It has been suggested that the different pathways for induction of drinking converge on a final common pathway. Thus, adrenergic stimulation of alpha(2),-adrenoceptors ofLH can influence this final common pathway.

Lateral parabrachial nucleus serotonergic mechanisms and salt appetite induced by sodium depletion

This study investigated the effects of bilateral injections of a serotonin (5-HT) receptor agonist into the lateral parabrachial nucleus (LPBN) on the intake of NaCl and water induced by 24-h water deprivation or by sodium depletion followed by 24 h of sodium deprivation (injection of the diuretic furosemide plus 24 h of sodium-deficient diet). Rats had stainless steel cannulas implanted bilaterally into the LPBN. Bilateral LPBN injections of the serotonergic 5-HT1/2 receptor antagonist methysergide (4 mu g/200 nl at each site) increased hypertonic NaCl intake when tested 24 h after sodium depletion and after 24 h of water deprivation. Water intake also increased after bilateral injections of methysergide into the LPBN. In contrast, the intake of a palatable solution (0.06 M sucrose) under body fluid-replete conditions was not changed after bilateral LPBN methysergide injections. The results show that serotonergic mechanisms in the LPBN modulate water and sodium intake induced by volume depletion and sodium loss. The finding that sucrose intake was not affected by LPBN serotonergic blockade suggests that the effects of the methysergide treatment on the intakes of water and NaCl are not due to a mechanism producing a nonspecific enhancement of all ingestive behaviors.

Mineral trioxide aggregate as a root canal filling material in reimplanted teeth. Microscopic analysis in monkeys

This study analyzed mineral trioxide aggregate (MTA) as a root canal filling material for the immediate reimplantation of monkey teeth. Four adult capuchin monkeys Cebus apella were used, which had their maxillary and mandibular lateral incisors on both sides extracted and reimplanted after 15 min. During the extra-alveolar period, the teeth were kept in saline solution and after reimplantation retention was performed with a stainless steel wire and composite resin for 14 days. After 7 days, the reimplanted teeth were submitted to endodontic treatment with biomechanics up to file n. 30 and irrigation with a saturated solution of calcium hydroxide [Ca(OH)(2)], and then divided into two study groups: group I - root canal filled with a Ca(OH)(2) paste, and group II - root canal filled with MTA. Radiographic follow up was performed at 30, 60 and 90 days postoperatively, and after 180 days the animals were killed and specimens were processed for histomorphological analysis. The results revealed that most specimens of both groups presented organized periodontal ligament with no inflammation. The resorptions observed were surface resorptions and were repaired by cementum. Both MTA and Ca(OH)(2) were good root canal filling materials for immediately reimplanted teeth, providing good repair and also allowing biological sealing of some lateral canals. There was no significant difference between the study groups (alpha = 29.60%).

Plasma nitriding of sintered AISI 316L at several temperatures

Samples of sintered AISI 316L stainless steel were plasma nitrided in a mixture of H-2-20% N-2, for 3 or 4 h. The treatment temperature was selected in 400-550 degreesC interval, in steps of 50 degreesC. X-ray diffraction (glancing angle geometry-GAXRD), conversion electron Mossbauer spectroscopy (CEMS), optical microscopy and Vickers microhardness were used as analytical techniques. For T greater than or equal to 500 degreesC and t = 4 h, a 40-mum layer is formed. The GAXRD results showed a transformation of the austenite gamma phase to the martensite in the sinterization process and showed as well, that the gamma' (Fe4N) phase is the predominant nitride besides small amounts of epsilon-Fe2N, gamma(N) CrN, Cr2O3 and the fcc nitrogen supersatured solid phase gamma(N). The CrN phase seems to decrease with temperature while the gamma(N) phase fraction is almost less than or equal to10%, independently on the temperature. The CEMS results indicated that while the gamma(N) fraction decreases with temperature of plasma nitriding, the gamma' fraction increases proportionally. (C) 2003 Elsevier B.V. All rights reserved.

Central moxonidine on water and NaCl intake

In this study we investigated: (a) the effects of intracerebroventricular (i.c.v.) injections of moxonidine (an alpha(2)-adrenergic and imidazoline receptor agonist) on the ingestion of water and NaCl induced by 24 h of water deprivation; (b) the effects of i.c.v. injection of moxonidine on central angiotensin II (ANG II)- and carbachol-induced water intake; (c) the effects of the pre-treatment with i.c.v, idazoxan (an alpha(2)-adrenergic and imidazoline receptor antagonist) and RX 821002 (a selective alpha(2)-adrenergic antagonist) on the antidipsogenic action of central moxonidine. Male Holtzman rats had stainless steel cannulas implanted in the lateral cerebral ventricle. Intracerebroventricular injection of moxonidine (5 and 20 nmol/1 mu l) reduced the ingestion of 1.5% NaCl solution (4.1 +/- 1.1 and 2.9 +/- 2.5 ml/2 h, respectively vs. control = 7.4 +/- 2.1 ml/2 h) and water intake (2.0 +/- 0.6 and 0.3 +/- 0.2 ml/h, respectively vs. control = 13.0 +/- 1.4 ml/h) induced by water deprivation, Intracerebroventricular moxonidine (5 nmol/1 mu l) also reduced i.c.v. ANG Ii-induced water intake (2.8 +/- 0.9 vs. control = 7.9 +/- 1.7 ml/1 h) and i.c.v. moxonidine (10 and 20 nmol/1 mu l) reduced i.c.v. carbachol-induced water intake (4.3 +/- 1.7 and 2.1 +/- 0.9, respectively vs. control = 9.2 +/- 1.0 ml/1 h). The pre-treatment with i.c.v. idazoxan (40 to 320 nmol/1 mu l) abolished the inhibitory effect of i.c.v, moxonidine on carbachol-induced water intake. Intracerebroventricular idazoxan (320 nmol/1 mu l) partially reduced the inhibitory effect of moxonidine on water deprivation-induced water intake and produced only a tendency to reduce the antidipsogenic effect of moxonidine on ANG Ii-induced water intake. RX 821002 (80 and 160 nmol/1 mu l) completely abolished the antidipsogenic action of moxonidine on ANG Ii-induced water intake. The results show that central injections c: moxonidine strongly inhibit water and NaCl ingestion. They also suggest the involvement of central alpha(2)-adrenergic receptors in the antidipsogenic action of moxonidine. (C) 1999 Elsevier B.V.