The early days of experimental neutrino physics

The neutrino hypothesis, put forward by Pauli to account for the apparent loss of energy and momentum in beta decay, was verified by a series of measurements at a nuclear reactor nearly 25 years ago. An account is given of the first observations of the interaction of neutrinos in a target remote from the fission process that produced them. These experiments completed the observations of the particles involved in beta decay and paved the way for use of the free neutrino to probe the nature of the weak interaction.     

Chemistry and chemical intermediates in supersonic free jet expansions

Short-lived intermediates often play key roles in determining the course of chemical reactions. Recently the combination of sophisticated laser techniques and supersonic free jet expansions has offered new insight into the structure and reactivity of such intermediates. Because of their extremely reactive nature the intermediates are produced in situ in the expansion. The free jet expansion provides cooling of the intermediates to very low temperatures, so that even complex organic free radicals and molecular ions can be identified and characterized. Radical-radical reactions and ionic cluster formation likewise proceed in the expansion and can be monitored by laser spectroscopy.     

Relativistic projectile fragment interactions: anomalons

Interaction mean free paths are calculated for projectile fragments from relativistic heavy-ion interactions in emulsions and plastic. There are important discrepancies between emulsion results and those from other techniques. "Anomalous" secondaries (anomalons) may prove to be interpretable by conventional nuclear physics: short mean free paths may be due to convoys of collinear light fragments from peripheral interactions (for example, with neutrons) or from low-excitation particle-unbound fragments that decay in flight.     

Interaction of 3.9-gev nitrogen ions with matter

The interaction with matter of nitrogen ions in the 3.9-billion-electron-volt (Gev) beam of the Princeton Particle Accelerator has been studied. In polyethylene, the range of ions is 12.6 +/- 0.2 grams per square centimeter and the mean free path for nuclear collisions is 15.4 +/- 3.8 centimeters; the loss of energy by the ions passing through polyethylene agrees with that predicted by stopping-power theory. The production of secondary particles has been investigated. These data are useful for experiments and for evaluating the merits of nitrogen ions in biomedical application.     

利用核磁共振自由感应衰减曲线测定木材含水率

为定量测定木材含水率,以水分子中的质子为探针,利用核磁共振技术探究木材内部水分的变化情况。通过对胡桃木、红橡木和水曲柳解吸过程中,水分变化的核磁共振自由感应衰减曲线（FID）进行分析,发现木材的含水率与核磁共振的FID信号量高度线性相关,相关系数均超过0.99;因此,可以通过建立含水率与核磁共振FID信号的标准曲线实现木材含水率的核磁共振定量测量。同时,可以根据绝干木材的核磁共振FID信号量比较不同材种基本密度的大小。      

Physical model for the decay and preservation of marine organic carbon

Degradation of marine organic carbon provides a major source of atmospheric carbon dioxide, whereas preservation in sediments results in accumulation of oxygen. These processes involve the slow decay of chemically recalcitrant compounds and physical protection. To assess the importance of physical protection, we constructed a reaction-diffusion model in which organic matter differs only in its accessibility to microbial degradation but not its intrinsic reactivity. The model predicts that organic matter decays logarithmically with time t and that decay rates decrease approximately as 0.2 x t(-1) until burial. Analyses of sediment-core data are consistent with these predictions.     

University Isotope Separator at Oak Ridge: The UNISOR Consortium

The UNISOR cooperative project, envisioned more than 3 years ago, is now successfully working. Research problems that involve a full range of experiments on nuclei far from beta stability are being investigated jointly by groups of scientists from several institutions. Some of the first work reported (16) included the identification, half-lives, and decay schemes of three new isotopes, (186)T1, (188)T1, and (116)I; the first or new decay schemes of (189)T1, (190)T1, (117)Xe, and (117)I; and the results of the perturbed gamma-gamma directional correlation work in (126)Xe. UNISOR is already stimulating international interest. A report (1) on the new research being planned with an isotope separator on-line to ORIC was presented at a Soviet Academy of Sciences meeting on nuclear structure in 1971. At an international nuclear physics conference in Munich in August 1973, Academician G. N. Flerov, director of the heavy-ion laboratory in Dubna, said the UNISOR project had inspired his laboratory to secure funds for a new, much improved isotope separator which is now installed on-line to their heavy-ion cyclotron to be used for detailed studies of nuclei far from stability. The UNISOR model for research has inspired a second such project, the Atomic Physics Consortium at Oak Ridge (APCOR). After an exploratory conference at Oak Ridge, scientists from ten institutions met in November 1973 to form an organizing committee for APCOR. As with UNISOR, the universities and the AEC will each provide a significant portion of the capital and operating costs. Heavy ions have opened up much new research in atomic physics, but such accelerator-based research represents a real "shift from traditional approaches concerning how, where, and on what time scale atomic physics experiments should be done" (17).     

纳米CuO/硅溶胶制剂处理杨木性能的研究

【目的】探究不同后处理方式对纳米木材防腐剂浸渍材的耐腐性、顺纹抗压强度以及对浸渍材中铜离子抗流失性的影响,旨在为纳米防腐剂的应用提供依据。【方法】通过机械共混制备了一种纳米CuO/硅溶胶制剂,并结合电感耦合等离子体发射光谱仪(ICP-OES)、扫描电镜(SEM),探究不同后处理方式(100℃蒸汽和-30℃冷冻)对浸渍材耐腐性、顺纹抗压强度、浸渍材制剂分布和铜离子抗流失性的影响。【结果】经过纳米CuO/硅溶胶制剂浸渍的杨木耐腐性显著提高,达到了Ⅰ级强耐腐标准,顺纹抗压强度较未处理材提高了24.42%。相比于浸渍试样,蒸汽后处理时间的延长使制剂更加均匀致密地分布在处理材中,而在冷冻后处理中呈颗粒状。经过蒸汽后处理90 min和冷冻后处理8 h的浸渍材质量损失率较普通浸渍材分别降低了18.30%和24.37%;在抗流失性方面,较短时间的蒸汽后处理可以提高浸渍材中铜离子的抗流失性,而经过不同时间冷冻后处理浸渍材中的铜离子抗流失性要优于普通浸渍材,铜离子流失量减少了8.72%～34.40%。在抗压强度方面,蒸汽后处理浸渍材顺纹抗压强度要高于普通浸渍试样,强度提高了0.64%～5.31%,而冷冻后...     

Ionization of liquids by radiation: measurement by a clearing field

A method has been developed for determining the yield of free ions formed by irradiation of a liquid with high-energy x-rays. Contrary to expectation, branched-chain paraffins produce many more free ions than straight-chain paraffins do, and the ether 1,4-dioxane produced only a third as many free ions as its hydrocarbon analog, cyclohexane.     

甜椒胞质雄性不育(CMS)系及其保持系花药中游离氨基酸含量

分析了不同核背景的甜椒胞质雄性不育(CMS)系ZTA、17A、8A和相应保持系ZTB、17B、8B花药中17种游离氨基酸,结果表明:不育系花药中游离脯氨酸和游离赖氨酸含量均明显低于相应的保持系;不育花药中严重缺乏游离脯氨酸;不育花药中游离苏氨酸和精氨酸含量均明显高于相应保持系的可育花药;不育系花药中游离氨基酸总量则明显低于保持系。核遗传背景差异导致3份同质异核甜椒不育系花药中同种游离氨基酸含量间存在差异。     

Ionization of liquids by radiation: measurement by charge scavenging

Pulse radiolysis of dilute solutions of triphenylcarbinol in saturated hydrocarbon gives spectra of the triphenylmethyl free radical, (C(6)H(5))(3)C., and cation, (C(6)H(5))(5)C(+). The yield of the ion is independent of the carbinol concentration, and is thought to measure the yield of free ions generated in the solvent. The relative yields of ions thus found in cyclohexane and 2,2,4-trimethylpentane agree with measurements made by the clearing-field method.     

Exotic nuclei and their decay

Recent advances in nuclear accelerators and experimental techniques have led to an increased ability to synthesize new isotopes. As isotopes are produced with more and more extreme combinations of neutrons and protons in their nuclei, new phenomena are observed, and the versatility of the nucleus is increased as a laboratory for studying fundamental forces. Among the newly discovered decay modes are (i) proton radioactivity, (ii) triton, two-proton, two-neutron, and three-neutron decays that are beta-delayed, as well as (iii)(14)C emission in radioactive decay. Precise tests of the properties of the weak force have also been achieved.     

汽油电化学催化氧化脱硫机理探索

以乙硫醇、甲硫醚和噻吩为模型硫化物,分析反应前后模型硫化物的变化,探索汽油电化学催化氧化脱硫的机理。推测电化学催化氧化脱硫的机理,在酸性电解体系中为具有催化功能的金属离子Mn+,首先在阳极表面被氧化为金属离子M(n+m)+,后者将硫醇类氧化为二硫化物,将硫醚类氧化为亚砜,将噻吩氧化为噻砜。在碱性电解体系中为阳极表面的OH-离子首先失去电荷生成高活性的氢氧自由基,将硫醇类首先氧化为二硫化物,并进一步氧化为二亚砜;将硫醚类氧化为亚砜或砜,将噻吩类氧化为噻砜类有机硫化物。     

催化裂化汽油质量衰变规律

采用43℃催速储存实验方法,以未洗胶质、实际胶质、酸度、色度、诱导期为表征指标,研究了催化裂化汽油的安定性变化规律,并利用最小二乘法、相关分析、方差分析等方法考察了催化裂化汽油安定性的影响因素,建立了安定性指标与储存时间的关系模型以及安定性指标间的定量关系。结果表明：催化裂化汽油在储存过程中,由于不饱和烃的氧化反应导致质量衰变,安定性指标均随储存时间的延长而变差;生产原料不同导致催化裂化汽油的质量衰变速率不同,且对安定性的影响大于储存时间的影响;未洗胶质、酸度与实际胶质的相关性良好,相关系数均在0.9以上,且环状烯烃、双烯烃等化学组成对衰变速率的影响显著。     

阻燃剂DPB改性木材的体积稳定性和防腐性能

采用阻燃剂ＤＰＢ改性大青杨木材,测定了处理木材的阻燃性及改性对木材体积稳定性和防腐性能的影响。实验表明：ＤＰＢ是一种性能较好的木材阻燃剂,但ＤＢＰ处理木材的抗胀缩率和阻湿率值均很低,低分子ＰＦ树脂、ＤＰＢ和季铵盐作为防腐剂均可使处理木材达到天然强耐腐级的要求,且ＤＰＢ和季铵盐类低毒、无污染,与ＰＦ树脂复配,可以大大提高处理木材的抗胀缩率和阻湿率。为了增强化学改性木材的体积稳定性、防腐性能和力学强度,复配药剂,使处理木材的品质得到综合性功能性改良。     

睾酮在北方山溪鲵精巢发育周期中的分布

用免疫组织化学方法检测了睾酮(testosterone,T)在北方山溪鲵(Batrachuperustibetanus)精巢发育周期中的变化。结果表明,在北方山溪鲵的精巢中,4月份T定位在次级精原细胞的胞质中;5月份T定位在次级精原细胞的胞核中;6~7月,精母细胞和精子细胞核中呈T阳性反应;8月份,精巢的非成熟区和成熟区散在地出现T的弱阳性位点;9~10月,精巢非成熟区的精原细胞胞质及成熟区精子中有较强的T阳性反应;11月,精原细胞的胞质及精子中的阳性反应减弱。在山溪鲵的生殖周期中,4~11月精巢中始终呈现T阳性反应,而且T的分布呈现出一定的规律性。在4~5月和9~10月,精巢间质细胞和支持细胞中也有T阳性反应。上述结果说明,在山溪鲵精巢中,T对生殖细胞增殖及精子形成起调控作用。     

落花生对中铜与锰的富集能力研究

[目的】研究落花生对中铜与锰的富集能力。【方法】通过水培的方法,研究落花生对铜和锰的吸收及修复水体能力。经过25d的培养后,用酸消解植物,采用分光光度计法测定植物中的铜和锰的含量。[结果]结果表明,与对照组相比,试验组处理25d后,落花生生长状况受重金属离子的影响明显,其中高浓度组有些种苗出现腐烂情况,并且生长明显比其他组缓慢。从、蒯定结果来看,低、中、高浓度处理组中落花生对铜离子平均吸收量分别为115．2、127．2、69．4mg／kg,都显著高于对照组合量（8．2mg／kg）,说明落花生对铜有一定富集能力;而在低、中、高的重金属浓度下,落花生对锰离子的平均吸收量分别为30．4、24．0、24．7μg／kg,与对照组锰离子的含量（19．2μg／kg）无明显差异,落花生对锰的富集效果并不理想。[结论】落花生适用于低、中浓度重金属铜污染水体或土壤的生态修复。     

哺乳期锌缺乏对小鼠海马锌离子含量影响的研究

目的检测哺乳期母鼠锌缺乏对其仔鼠大脑海马内锌离子含量的影响.方法 CD-1母鼠产后即喂以缺锌饲料（锌含量为0.85μg/g）以及去离子水,它们未断乳的仔鼠即作为锌缺乏组模型,在小鼠生后7、14、21 d,应用金属自显影技术检测海马中游离锌离子含量变化.结果与对照组相比,锌缺乏组未断乳仔鼠海马中的锌离子含量明显减少.结论哺乳期母鼠锌缺乏会导致仔鼠海马中游离锌离子含量显著减少.     

Undetectable intracellular free copper: the requirement of a copper chaperone for superoxide dismutase

The copper chaperone for the superoxide dismutase (CCS) gene is necessary for expression of an active, copper-bound form of superoxide dismutase (SOD1) in vivo in spite of the high affinity of SOD1 for copper (dissociation constant = 6 fM) and the high intracellular concentrations of both SOD1 (10 microM in yeast) and copper (70 microM in yeast). In vitro studies demonstrated that purified Cu(I)-yCCS protein is sufficient for direct copper activation of apo-ySOD1 but is necessary only when the concentration of free copper ions ([Cu]free) is strictly limited. Moreover, the physiological requirement for yCCS in vivo was readily bypassed by elevated copper concentrations and abrogation of intracellular copper-scavenging systems such as the metallothioneins. This metallochaperone protein activates the target enzyme through direct insertion of the copper cofactor and apparently functions to protect the metal ion from binding to intracellular copper scavengers. These results indicate that intracellular [Cu]free is limited to less than one free copper ion per cell and suggest that a pool of free copper ions is not used in physiological activation of metalloenzymes.     

Fragmentation of nitrogen-14 nuclei at 2.1 gev per nucleon

An experiment has been carried out at the bevatron on the nuclear fragmentation of nitrogen-14 ions at an energy of 2.1 billion electron volts (Gev) per nucleon. Because of the near equality of the velocities of the nitrogen-14 beam and the fragmentation products at an angle of 0 degrees , we find it possible to identify the nuclear fragments isotopically.