Aqueous solution properties of a silicone surfactant and its mixed surfactant systems

The aqueous solution properties of a nonionic silicone surfactant of dimethylpolysiloxane and its mixed surfactant systems were studied. It was found that the silicone surfactant has a high surface activity and forms micelles in two steps: premicelles in dilute concentrations and polymolecular micelles above 3.7 × 10⁻⁷ mol dm⁻³. In mixed systems of the silicone surfactant with anionic hydrocarbon or fluorocarbon surfactant, weak intermicellar interactions were found. They are due to electrostatic interaction between hydrophilic groups of the respective micelles. Dye solubilization measurements showed that the solubilized amount of Yellow-OB is greater than predicted by ideal systems. Hydrazo-azo tautomerism is observed in fluorocarbon-silicone surfactant systems, while Yellow-OB is solubilized only in the azo-form in the hydrocarbon-silicone surfactant system.     

Increases in hematopoietic responses caused by beta-glucans in mice

The effects of various (1-->3)-beta-D-glucans on hematopoietic responses of mice were investigated by measuring colony stimulating activity in sera and ascites of the mice administered glucan. We have demonstrated that the hematopoietic response was increased by various structures of (1-->3)-beta-D-glucans, i.e. soluble glucans (linear, branched, single helix, triple helix) and particulate glucans. From the viewpoint of structure and activity relationships, we found several characteristic features: i) hematopoietic response induced by the particulate glucan disappeared faster than that by the soluble glucans, ii) conformation of the glucans, single vs. triple helix, are relatively independent of the response, iii) linear glucan had a weaker response, and iv) there is a strong strain-dependency of the response. These results corresponded well with the fact that branched (1-->3)-beta-D-glucans, but not linear and not particulate, are often used as biological response modifiers for cancer patients.     

Defect structure and electrical conductivity in rapidly-quenched and slowly-cooled rhombohedral solid solutions of the system Bi2O3-BaO

The solid solubility limit, grain orientation, defect structure and electrical conductivity of solidified rhombohedral specimens in the Bi₂O₃-BaO system are described. The c-axes (in hexagonal notation) of solidified specimens were almost entirely oriented along the platelet/film thickness. Slow-cooling (∼ 10⁻²° Csec⁻¹) of the system gave solid solutions with substitutional type of 2BaO → 2Ba_Bi′ + 20+ V ₀ ^.. for 12 to 32 mol % BaO. High-temperature modification of slowly-cooled sample (16 mol % BaO) showed a conductivity of 8.8×10⁻¹ Ω⁻¹ cm ⁻¹ at 600° C along the conduction plane (perpendicular to the c-axis). Rapid quenching (∼ 10⁵° C sec⁻¹) produced solid solutions for 8 to 20 mol % BaO introducing interstitial Ba²⁺ (10–12 mol % BaO) and Schottky type defects such as V_Bi‴ and V _Bi ^‴ and V ₀ ^.. (16 to 20 mol % BaO), however the high-temperature modification of the rhombohedral structure could not be frozen.     

Transdiscal lumbar sympathetic block: a new technique for a chemical sympathectomy

Genitofemoral neuritis, which occurs when the neurolytic solution spreads into the psoas muscle, is the most common complication after neurolytic lumbar sympathetic block. We developed a transdiscal approach for neurolytic lumbar sympathetic block to reduce the danger of genitofemoral neuritis by making a sympathectomy without penetration of the psoas muscle, through which the genitofemoral nerve passes. We attempted transdiscal lumbar sympathetic block in 14 patients for whom the last previous lumbar sympathetic block performed by using the conventional paravertebral method was unsuccessful. Under fluoroscopic guidance, the needle was inserted transdiscally at L2-3 and/or L3-4 and was advanced until its tip pierced the anterior longitudinal ligament. Radiography and computed tomography revealed that the injected contrast media spread along the anterolateral surface of the vertebral column without any flow into the psoas muscle. Alcohol was injected successfully in all patients. During the 1-mo follow-up period, no patients had any symptom of genitofemoral neuritis. Thirteen patients who had been suffering from lower extremity pain achieved partial or complete pain relief. One patient with plantar hyperhidrosis achieved persistent anhidrosis. These results suggest that the transdiscal approach can be a technical option for neurolytic lumbar sympathetic block. Implications: Neurolytic lumbar sympathetic block was performed with the needle advanced through the intervertebral disc. With this technique, the risk of genitofemoral neuritis, the most common complication after neurolytic lumbar sympathetic block, was reduced because the needle does not penetrate the psoas muscle, through which the genitofemoral nerve passes.     

A period of anaerobic exercise increases the accumulation of reactive carbonyl derivatives in the lungs of rats

Compartment syndrome is caused by an increase in intracompartmental pressure above the capillary level, preventing capillary flow. The acute onset of symptoms occurs after events such as fracture, soft tissue trauma, and revascularization and usually necessitates prompt fasciotomy to avoid loss of function or even necrosis of the enclosed muscle. Compartment syndromes in athletes are of a recurrent nature and are usually referred to as chronic. Nonoperative treatment is often successful. Although compartment syndromes can occur in several anatomic regions, the most commonly seen in athletes involve the leg. Chronic compartment syndromes of the upper extremity are rare, and only a few cases have been reported in the literature. The intracompartmental pressures causing chronic symptoms in these cases ranged between 22 mm Hg at rest and 40 mm Hg after 30 minutes of exercise. Under maximal contraction, a pressure of 58 mm Hg has been recorded. The object of this paper is to report a case of a tennis player where much higher flexor-pronator muscle intracompartmental pressures than those noted above were recorded. We compared the intracompartmental pressure data of this patient with intracompartmental pressures measured in six symptom-free volunteers.     

Measurement of stress relaxation in broken fibers embedded in epoxy using Raman spectroscopy

Raman spectroscopy was used to study the stress relaxation in broken fibers in a unidirectional composite. A single-fiber model composite consisting of a high modulus PAN-based carbon fiber and an epoxy resin matrix was loaded incrementally until the fiber got broken.Then the stress profile in the broken fiber was monitored under constant overall strain for 1000 hours by determining fiber stress through the stress dependence of the 2700 cm–1 Raman band peak position. Three experiments were done at different overall strains.It was observed that the stress profile in each broken fiber changed only a little even after 1000 hours whereas matrix normal stress in the fiber direction relaxed to about a quarter of the initial value in about 200 hours. It is shown that this result does not support linear viscoelastic solutions based on perfect bonding at interface since the present experiments had interfacial debonding and matrix shear yielding around fiber breaks.     

Ion conductive characteristics of boron stabilized carbanion derived from organoboron π-conjugated systems

Summary Ion conductive properties of boron stabilized carbanions (BSC) have been studied as a model of π-conjugated ion conductive polymer in which counter anion of lithium ion is delocalized in π-conjugated system. After treatment of the BSC precursor (trimesitylborane or dimesityl-9-anthrylborane) with an organolithium reagent, the color of the reaction mixture dramatically turned to dark red or purple. Interestingly, BSC derived from dimesityl-9-anthrylborane showed moderate ion conductivities of 4.02×10⁻⁷ S/cm at 50°C even in bulk, indicating high dissociation degree of the BSC lithium salt. This can be attributed to the decreace in site hopping energy of the lithium ion, since anionic charge is delocalized via vacant p-orbital of the boron atom. These observations might have important implication for potential capability of ion conductive π-conjugated systems. Received: 20 January 2003/Revised version: 10 April 2003/ Accepted: 19 April 2003 Correspondence to Hiroyuki Ohno     

Effects of AsH3 surface treatment for the improvement of ultra-shallow area-selective regrown GaAs sidewall tunnel junction

Low-temperature (290°C) area-selective regrowth by molecular layer epitaxy (MLE) was applied for the fabrication of an ultra-shallow sidewall (50 nm) GaAs tunnel junction. Fabricated tunnel junctions have shown a record peak current density up to 35,000 A/cm². It is shown that the tunnel junction characteristics are strongly dependent on the sidewall orientation and the AsH₃ surface treatment conditions just prior to regrowth. The effects of AsH₃ surface treatment are discussed in view of the control of surface stoichiometry.