Entorhinal-hippocampal connections: a speculative view of their function

A 20 MHz pulsed Doppler ultrasound system was used to obtain steady flow velocity profiles in cylindrical tubes. A deconvolution technique was employed to improve the spatial resolution and the corrected results were compared with Poiseuille's theory. Frequency domain windowing was used to suppress noise in the deconvolution procedure, using a method which reduced distortions at the window boundaries. Wall shear rate was calculated from the measured velocity profiles both before and after deconvolution, and compared with theory to quantify the accuracy of the technique. The results illustrate the significant improvement provided by deconvolution, with the average error in measured wall shear rate reducing from 46 to 12% after applying the technique. Some of the discrepancy is in part attributed to the method used to determine wall shear rate.     

Deoxidation equilibria of calcium and magnesium in liquid iron

Calcium-oxygen and magnesium-oxygen equilibria in liquid iron saturated with CaO-SiO₂-Al₂O₃-MgO slags were studied at 1873 K using CaO, Al₂O₃, and MgO crucibles. The applicability of the first-order and second-order interaction coefficients between Ca and O and between Mg and O was studied by comparing the Ca-O and Mg-O equilibria observed in the present and previous experiments with the calculated ones from the respective interaction coefficients. As a result, the interaction coefficients obtained in the present work by using a new method were found to explain the measured solubilities of CaO and MgO. The phase stability region in Fe-Al-M (M=Ca, Mg)-O system was described at 1873 K.     

高纯金属镁比较-气体容量法测定炼钢辅料中金属镁或金属钙

提出了一种采用高纯金属镁比较-气体容量法测定炼钢辅料钝化镁脱硫剂中金属镁和钙铁包芯线中金属钙的方法。分别采用稀盐酸和氯化铵溶液溶解钝化镁脱硫剂和钙铁包芯线样品, 使样品中的金属镁或金属钙与溶样试剂中的氢离子发生反应, 置换出等当量的氢气, 用自制的排水法量气体体积装置测定样品的产氢气体积;在相同温度和压力下, 采用溶样试剂溶解高纯金属镁标样, 测定其产氢气体积;根据气体状态方程, 通过比较法计算出钝化镁脱硫剂中金属镁或钙铁包芯线中金属钙的含量。方法应用于钝化镁脱硫剂样品中金属镁的测定, 结果与碘-乙醇提取-EDTA络合滴定法一致, 相对标准偏差(RSD, n=6)小于0.3%;方法应用于钙铁包芯线样品中金属钙的测定, RSD(n=6)小于1.8%, 回收率为98%~99%。     

钢渣中钙镁离子的选择性浸出行为

钢渣富含大量的碱性氧化物,是CO₂矿化的潜在廉价原料。以乙酸作为浸出剂,探究了钢渣颗粒粒度、浸出温度、时间、固液比和乙酸浓度对钢渣中主要元素钙、镁、铁、硅溶出行为的影响。试验结果表明钢渣颗粒粒径的降低、乙酸浓度的提高均能有效促进钙、镁离子的浸出,同时也发现延长浸出时间反而会带来铁、硅离子浸出率的降低。在乙酸浓度为1 mol/L、浸出温度为80 ℃、浸出时间为90 min、固液比为1∶20的条件下,能够实现钢渣中钙、镁离子的选择性高效浸出,其最高浸出率达到了92%和52%,而铁离子、硅离子为29.5%和15.9%。浸出渣的物相分析表明经乙酸浸出后滤渣中主要的物相为RO相与磁铁相,这意味着乙酸酸浸不仅能够高效浸出钙、镁,其浸出液能够作为CO₂间接矿化的原料,而且浸出后得到的滤渣中富含含铁相,可以作为优质的炼铁原料。     

Compartmental shifts of calcium and magnesium as a result of swimming and swimming training in rats

To describe accurately the mineral changes (Ca and Mg) provoked by swimming, the aims of this study were to analyze those tissues that, with regard to their mineral content, can better classify individuals performing both swimming until exhaustion and swimming as training and to know the shifts of these minerals between different tissues after a single session of swimming until exhaustion and after training. Wistar rats were distributed into 12 groups, six male and six female (N = 10): 1) control rest group (CR); 2) trained rest group (TR); 3) control exercise group (CE); 4) trained exercise group (TE); 5) control recovery group (CER) and 6) trained recovery group (TER). The most informative tissues of Ca and Mg compartmental shifts during exercise have been determined. Discriminant analysis selected heart Ca, muscle Ca and bone Ca, bone Mg, erythrocyte Mg, and serum Mg as the most significant variables. The animals were classified by means of two canonical axes: the first one relates to training situation and sex, and the second one shows the special characteristics of trained male rats. Another independent discriminant analysis applied to male and female groups separately showed that the first canonical axis (control/trained) is basically defined by heart Ca, bone Ca, and erythrocyte Mg (male), and by heart Ca, bone Ca, and bone Mg (female), while the second axis, related to the exercise situations, is defined by the serum Mg levels in both sexes. We think that discriminant analysis is a statistical method capable of explaining physiological processes and classifying individuals performing exercises of different length. It suggests that the homeostasis of Ca and Mg is somewhat different for males and females. Serum magnesium must be considered to distinguish exercise situations. The analysis of these tissues could inform us about the mineral status of the rats and then we could correct possible deficiencies in our research. In this work we have only found different mineral redistributions among tissues. The trained animals have a better mineral recovery capacity than the untrained ones. Training has a different physiological repercussion in male and female rats on the basis of their respective maximal swimming times after training and their mineral behavior.     

Solubility of magnesium oxide in calcium oxide-calcium chloride mixtures

Measurements and theoretical calculations of the solubility product of magnesium oxide in calcium chloride-calcium oxide mixtures at 1133 K are reported. A filtration technique in an inert atmosphere was used to obtain samples for analysis by atomic absorption for magnesium content. At low concentrations of O^-2, the data are in consonance with the very low solubility product of 10^-6.2 predicted by a simple thermodynamic cycle first proposed by Flood, Fϕrland and Grjotheim. Work performed under the auspices of the U.S. Energy Research and Development Administration.     

Prevention by calcium administration of reserpine action on rat brain noradrenaline stores: a reappraisal

The conditions under which pretreatment with a calcium salt may prevent the action of reserpine on brain noradrenaline stores in the rat were investigated. The results show that only after subcutaneous administration of reserpine in the same site as a previous CaCl2 injection, was the action of reserpine prevented and reduced levels of this drug were found in the brain. Conversely, the depletion of encephalic noradrenaline following reserpine, as well as the reserpine brain concentration, were not affected by subcutaneously administered calcium chloride, when reserpine was administered either intravenously, or subcutaneously in a site different from that selected for pretreatment with the calcium salt. In essence calcium chloride, a well known irritant, acts accordingly at the site of subcutaneous administration, thus limiting by a non specific mechanism the absorption of reserpine. Under similar conditions, in fact, the absorption of a different drug, i.e. harmaline, was likewise altered. In view of these findings the significance of some studies on calcium-reserpine interaction appearing in the literature requires a reappraisal.     

Effects of calcium ions and magnesium ions on 5-hydroxytryptamine-receptor interaction

A case of a malignant germ cell tumor of the testis in a 28-year-old man is reported. The patient showed spontaneous regression of pulmonary metastasis and is well 7 years after orchiectomy and irradiation of abdominal lymph nodes. A plea is made for further documentation of such cases.     

碱熔-EDTA滴定法测定铬铁矿中钙和镁

用过氧化钠熔融分解试样,在强碱性条件下沉淀分离基体及铬、硅,控制溶液pH 6~7,用六次甲基四胺和铜试剂沉淀分离铁、铝、钛等干扰元素,再采用两种不同浓度的EDTA标准滴定溶液对滤液中的钙(以氧化钙计)和镁(以氧化镁计)分别进行滴定,建立了测定铬铁矿中钙和镁的方法。采用电感耦合等离子体原子发射光谱法(ICP-AES)对沉淀法分离铬后滤液中的钙进行了测定,结果表明,滤液中钙含量与样品中钙含量相比可忽略不计。干扰试验表明,试样中的共存元素均不干扰测定。按照实验方法对GTK-1铬铁矿样品、GBW 07820GCr-3铬铁矿标准物质和GSBD 33001-94铬铁矿标准物质中钙和镁进行测定,测定值与认定值一致,结果的相对标准偏差(RSD,n=8)在0.25%～4.9%之间,方法的极差在GB/T 24221-2009规定的允许差范围内。     

Complementary vascular-protective actions of magnesium and taurine: a rationale for magnesium taurate

A comparison was made among the elastic moduli of various combinations of dimethacrylates that may be used as matrix resins in dental restorative composite biomaterials systems. Two ceramic filler materials with contrasting shape and size were synthesized by wet chemistry; these were used to produce a range of experimental composite systems. Dynamic elastic moduli determinations were used to study the influence of filler volume, filler size/shape, use of silane coupling agents, and storage in water. The filler was varied from 0 to 59% by volume for filler A and from 0 to 48% volume for filler B. Silane treatment was found to have a significant effect on modulus. Moduli for composite materials containing silane-treated filler were higher compared to materials containing the same volume loading of non-silane-treated filler. Using a light curing resin as a matrix gave a significantly higher modulus for a filler loading of 38% by volume. Storage in water for 29 days was found to have only a slight effect on moduli for composite systems containing in excess of 20% by volume of filler. The experimental composite systems produced slightly higher values for moduli than were predicted by the theoretical Reuse constant stress model.     

Experimental aneurysms: proposal for a new technic

The authors present a critical analysis of the various methods of experimental production of aneurysms and report their own method in which saccular aneurysms were produced at the bifurcation of the common carotid artery in dogs with vein patch grafts. The objective point of this study was the creation of an experimental model to evaluate the efficacy of a therapeutic procedure. These aneurysms have a low incidence of thrombosis and a tendency to enlarge and to become spherical. They closely simulate the saccular aneurysms developing spontaneously in the cerebral arteries of man, and as such are useful models for experimental purposes.