超临界CO2法制备超细HMX颗粒

考察了预膨胀压力、HMX丙酮溶液初始浓度、取样停留时间及其他因素对制备HMX超细微粒粒度和晶体性质的影响.制备的超细HMX微粒平均粒径在350 nm以下,一部分微粒粒度小于100 nm.结果表明,预膨胀压力对HMX颗粒尺寸的影响较大,压力增加,HMX平均粒度变小,粒度分布变窄;HMX丙酮溶液初始浓度对HMX的粒度和粒度分布有很大影响,初始浓度越小平均粒径就变小,粒度分布变窄.停留时间及喷嘴尺寸对颗粒粒度、粒度分布及其形貌都有不同程度的影响.     

初始过饱和度对谷氨酸结晶的影响研究

以谷氨酸一钠(MSG)水溶液模拟发酵液,采用pH-shift模式研究溶液初始过饱和度对谷氨酸结晶的影响。结果表明:过饱和度同时影响谷氨酸结晶的晶习和粒度分布。当过饱和度S≤7.15时,谷氨酸主要以α型晶习析出,粒径呈对数对称分布。随着过饱和度增大,β型结晶比例增大,中位径趋小且粒度分布范围变宽。当S≥14.17以后,晶体全部是β型晶习,晶体粒度分布分散且无规律。根据经典成核理论计算了不同过饱和度/MSG浓度时两种谷氨酸晶习的成核速率,证明两种晶习的成核速率均随过饱和度增加而加快,相同过饱和度时α型晶习成核速率大于β型,而相同MSG浓度时β型成核速率大于α型。研究认为,结晶成核速率随过饱和度增大而加快是影响谷氨酸结晶粒度分布的主要原因,而晶体晶习主要取决于α、β型两种晶核的竞争性成核速率的差值。基于已有研究报道及实验结果,提出了α和β型谷氨酸晶体的C-pH相图模型,解释了过饱和度影响谷氨酸结晶晶习的规律。     

砷铁水热共沉淀制备大颗粒臭葱石

开展了硫酸体系中砷铁水热共沉淀为大颗粒晶型臭葱石的研究,考察了初始Fe/As摩尔比、初始pH、反应温度、搅拌速度和氧分压等因素对砷铁沉淀率、臭葱石晶型形成及臭葱石粒度的影响. 结果表明,Fe/As摩尔比、初始pH及反应温度降低有利于形成纯净大颗粒臭葱石,臭葱石颗粒粒度与氧分压关系不大. 高搅拌速度有利于形成纯净臭葱石,但不利于大颗粒臭葱石晶体的形成. 在Fe/As摩尔比1.5、初始pH 1.0、反应温度160℃、搅拌速度500 r/min和氧分压0.4 MPa的优化条件下,除砷率高于97%,沉砷渣中砷含量大于30%,平均粒度大于20 ?m.     

含钌吸收液沉钌实验研究

利用氯化铵沉淀含钌吸收液,研究了游离氯化铵浓度、盐酸浓度、反应温度和反应时间对沉钌率及晶体粒度与形貌的影响。结果表明：在一定范围内,增加游离NH₄Cl浓度和盐酸浓度能较大幅度提高沉钌率,升高反应温度和延长反应时间仅略微提高沉钌率;增加游离NH₄Cl浓度、提高反应温度和延长反应时间有助于形成细小的颗粒,改变盐酸浓度会影响晶体的粒度与形貌。     

浅析结晶工艺参数的优化

青海盐湖百万t钾肥项目光卤石冷结晶法,主要是通过控制低钠光卤石的分解条件和溶液中氯化钾的过饱和度,来减少氯化钾的晶体数量,达到在常温下使氯化钾晶体颗粒长大的目的.在氯化钾结晶过程中,溶液的过饱和度,底流流量以及循环母液量,溶液的循环速率,搅拌强度,结晶温度,晶体磨损、结晶器内壁的粗糙度等非均相成核是影响产品粒度的几个因素.实验通过控制分解液的密度,减小底流流量及增加循环母液量,得到了较理想的产品粒度,提高了产品质量和收率,以最佳工艺控制条件指导工业生产,大幅度降低了生产成本,提高了企业的经济效益.     

硝酸钾结晶生长特性的研究

利用5LMSMPR结晶器,通过改变停留时间、过饱和度和搅拌速度等因素,对硝酸钾结晶的粒度分布、平均粒径、主粒径、成核及生长速率等动力学特性进行了研究,并在结晶温度25℃、过饱和度2℃、搅拌速度400r/min和停留时间10～50min条件下,建立了硝酸钾晶体生长动力学模型:B°=6.19×1022G2.02。研究结果表明:当停留时间大于30min、搅拌速度为400r/min时,晶体的平均粒径和主粒径较大;过饱和度的减小也会使晶体粒径增大,但其影响较小。     

溶液电导率法对绿色水处理剂聚天冬氨酸的阻垢性能的研究

采用电导法研究聚天冬氨酸(PASP)对碳酸钙垢的阻垢性能,考察了PASP用量、温度、溶液中钙离子浓度、pH等因素的影响。结果表明,PASP的质量浓度从10 mg/L上升到40 mg/L,CaCO3相对过饱和度增加迅速,浓度升高到40 mg/L以后,相对过饱和度增加态势趋于稳定,其相对过饱和度为4.7;温度越高,PASP的相对过饱和度越高,适用于高温环境;钙离子浓度对相对过饱和度影响不大,PASP可适用于高钙离子含量的溶液中。     

溶析结晶法制备聚苯乙烯微粒

采用溶析结晶法制备了球形聚苯乙烯(PS)亚微米粒子,并用激光粒度仪、FESEM等分析方法对粒子大小、粒度分布以及粒子形貌等进行了表征,对料液浓度、搅拌速度、料液/反溶剂体积比、结晶温度对粒径的影响进行了考察.结果表明,溶析结晶法制备的PS粒子为球形,粒径分布比较窄,平均粒径在500nm左右,比文献报道的超临界流体技术法制备的PS颗粒小;料液浓度是影响粒径的重要因素,其他因素对粒径影响较小.     

超临界溶液快速膨胀法制备二氯二茂钛微粒及催化乙烯聚合

为克服茂金属催化剂得到的聚合物形态难以控制、表观密度较低、易粘釜和不适于气相淤浆聚合等缺点,以超临界溶液快速膨胀过程为手段,以期制得颗粒分布均匀的细微催化剂颗粒,继而得到形态良好的聚合物.作为超临界流体技术的基础,首先测定了二氯二茂钛在超临界丙烷中的溶解度.在此基础上,用RESS方法制得了均匀的超细催化剂颗粒,且系统考察了溶液浓度、预膨胀温度、喷嘴结构和接收距离对沉析颗粒粒径的影响.最后,将RESS所制得的催化剂颗粒进行乙烯淤浆聚合,并分析聚合物形态结构.实验结果表明,在温度为383.15～408.15 K和压力为10～35 MPa范围内,溶解度随温度的增加而增加,随压力的升高而增加,说明在该操作范围内,不存在反向区.RESS操作的结果显示,二氯二茂钛颗粒粒径随溶液浓度的增大而减小,随预膨胀温度的升高而增大,而喷嘴直径的减小和喷嘴长度的增加将使得颗粒粒径增大,而收集距离的增加将使得颗粒粒径先增加后减缓,直至不再变化.通过对原始的催化剂颗粒和RESS制得的催化剂颗粒进行乙烯淤浆聚合表征发现,相比于原始催化剂,由于烯烃催化剂的复制原理,RESS制得的催化剂颗粒的聚合物具有良好的形态.     

五水柠檬酸钠连续结晶动力学研究

研究了五水柠檬酸钠的连续结晶过程。利用马尔文激光粒度分析仪对不同温度和停留时间下连续结晶过程产品的粒度分布进行分析。通过实验数据和粒度无关生长模型,分别计算了连续结晶过程中五水柠檬酸钠晶体生长与成核速率方程。研究表明,在33.3℃的连续结晶过程中,五水柠檬酸钠的成核速率较生长速率对溶液的过饱和度变化更敏感,增加溶液过饱和度更易形成较小粒度的晶体。     

Many Drugs of Abuse May Be Acutely Transformed to Dopamine,Norepinephrine and Epinephrine In Vivo

It is well established that a wide range of drugs of abuse acutely boost the signaling of the sympathetic nervous system and the hypothalamic–pituitary–adrenal (HPA) axis, where norepinephrine and epinephrine are major output molecules. This stimulatory effect is accompanied by such symptoms as elevated heart rate and blood pressure, more rapid breathing, increased body temperature and sweating, and pupillary dilation, as well as the intoxicating or euphoric subjective properties of the drug. While many drugs of abuse are thought to achieve their intoxicating effects by modulating the monoaminergic neurotransmitter systems (i.e., serotonin, norepinephrine, dopamine) by binding to these receptors or otherwise affecting their synaptic signaling, this paper puts forth the hypothesis that many of these drugs are actually acutely converted to catecholamines (dopamine, norepinephrine, epinephrine) in vivo, in addition to transformation to their known metabolites. In this manner, a range of stimulants, opioids, and psychedelics (as well as alcohol) may partially achieve their intoxicating properties, as well as side effects, due to this putative transformation to catecholamines. If this hypothesis is correct, it would alter our understanding of the basic biosynthetic pathways for generating these important signaling molecules, while also modifying our view of the neural substrates underlying substance abuse and dependence, including psychological stress-induced relapse. Importantly, there is a direct way to test the overarching hypothesis: administer (either centrally or peripherally) stable isotope versions of these drugs to model organisms such as rodents (or even to humans) and then use liquid chromatography-mass spectrometry to determine if the labeled drug is converted to labeled catecholamines in brain, blood plasma, or urine samples.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

ICP-MS法测定地球化学样品中As、Cr、Ge、V等18种微量痕量元素的研究

建立了测定地球化学样品中包括As、Cr、Ge、V等18种微量、痕量元素的ICP-MS方法。地化试样用HF-HNO3混酸分解后,以1 1 HNO3溶解干渣。由于制样不使用盐酸,避免了Cl对As、Cr、Ge、V的质谱干扰。用国家一级地球化学标准物质GBW 07309制备溶液优化仪器工作参数,并用于校准。方法测定限(6s)为:0.007~6.4μg/g,精密度(RSD%,n=12)为:29%~9.4%,经过国家一级地球化学标准物质的分析验证,结果与标准值吻合。方法已应用于国土资源调查的试样分析。     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

基于ATRP法制备的触角状亲水性羟胺树脂的吸硼性能的研究

以大分子引发剂氯乙酰化聚苯乙烯微球(PS-acyl-Cl)经原子转移自由基聚合(ATRP)法引发丙烯酰胺(AM)和甲基丙烯酸缩水甘油酯(GMA)单体的共聚接枝,制得一种触角状亲水性环氧载体(PS-acyl-g-P(AM-co-GMA)),再经二乙醇胺(DEA)的环氧基开环胺化反应,得到一种含多个-NCH2CH2OH螯合配基的多齿-五元螯合环的触角状亲水性羟胺树脂(PS-acyl-g-P(AM-co-GMA)-DEA)。将此树脂用于硼吸附研究,结果表明,PS-acyl-g-P(AM-co-GMA)-DEA树脂对硼的吸附满足Langmuir方程,为单分子层吸附;饱和吸附量约为37.7 mg·g-1,且树脂5 min即可达到吸附平衡,与其它已报道的吸硼树脂相比,该树脂具有更高的吸附量和吸硼速率。吸附动力学研究表明,树脂吸附硼的过程主要由颗粒扩散过程控制。重复使用5次后该树脂的吸附量基本不变,解吸率均在90%以上,重复使用性能良好。