Devitrite-based optical diffusers.

Devitrite is a novel material produced by heat treatment of commercial soda-lime-silica glass. It consists of fans of needle-like crystals which can extend up to several millimeters and have interspacings of up to a few hundred nanometers. To date, only the material properties of devitrite have been reported, and there has been a distinct lack of research on using it for optical applications. In this study, we demonstrate that randomly oriented fans of devitrite crystals can act as highly efficient diffusers for visible light. Devitrite crystals produce phase modulation of light because of their relatively high anisotropy. The nanoscale spacings between these needles enable light to be diffused to large scattering angles. Experimentally measured results suggest that light diffusion patterns with beam widths of up to 120° are produced. Since devitrite is an inexpensive material to produce, it has the potential to be used in a variety of commercial applications.

El Nino phenomenon in simple ocean data assimilation data

To study how the air and sea interact with each other during El Nino/La Nina onsets, extended associate pattern analysis (EAPA) is adopted with the simple ocean data assimilation (SODA) data. The results show that as El Nino/La Nina's parents their behaviors are quite different, there does not exist a relatively independent tropical atmosphere but does exist a relatively independent tropical Pacific Ocean because the air is heated from the bottom surface instead of the top surface and of much stronger baroclinic instability than the sea and has a very large inter-tropical convergence zone covering the most tropical Pacific Ocean. The idea that it is the wester burst and wind convergence, coming from middle latitudes directly that produce the seawater eastward movement and meridional convergence in the upper levels and result in the typical El Nino sea surface temperature warm signal is confirmed again.

热带太平洋次表层海温变化及其与ENSO循环的研究

随着全球变暖和各种极端天气事件发生频率的增加，气候变化已成为全世界关注的焦点问题，ENSO事件是年际尺度上气候变化的最强信号，它的影响波及到世界各地，所以，对ENSO事件进行深入研究，弄清其发生机制，具有重要的科学意义。虽然，目前对ENSO事件的研究已经取得了巨大成果，但仍不能对其发生发展的全过程进行准确的预测，因此，仍需要对其进行深入研究，本文正是从热带太平洋次表层温度场和流场的变化着手，对ENSO循环过程中的相关机理进行研究。 通过对TOGA/TAO、SODA和NCEP等海洋大气实测和再分析资料的分析，研究了热带太平洋次表层海温和流场的变化特征，分析了它们的变化机理，进而深入探讨了它们与ENSO事件的相互关系，并利用全球海洋数值模式的敏感性试验，探讨了大气风场的变化对海洋次表层要素的影响，主要得到以下结论： 1. 上世纪70年代末的气候突变之后，用28℃定义西太平洋暖池（WPWP），已不能合理的描述WPWP的基本特征。我们通过对比分析提出，用28.5℃来定义WPWP更合理，这一定义即可以充分反映WPWP突变前的特征，又能够合理的反映WPWP突变后的特征；对新定义的WPWP区域不同深度的海温距平的分析表明，次表层（148m）海温距平的变化趋势和变化幅度与表层和深层的变化差异较大，次表层海温的变化幅度最大并且年代际变化趋势与上下层正好相反；进一步的研究表明，WPWP次表层海温的年代际变化与PDO的变化有一定关系。 2. 利用热带太平洋次表层海温的变化特征，定义了表征ENSO事件的新指数——赤道太平洋温跃层海温振荡指数（EPOI），与其它ENSO指数相比，EPOI将东、西太平洋次表层海温的变化信息都包括在内，能够较全面的反映出ENSO事件的变化特征，特别是EPOI可以较好的反映出ENSO循环的年代际变化特征。另外，EPOI的变化比ONI的变化超前2个月，更有利于对ENSO事件的提前预报。由于EPOI主要反映海洋次表层的变化特征，因此能够更好的满足对ENSO机理研究的需要。 3. 赤道潜流距平场的EOF分析表明，其前两个模态的方差贡献较大，第一模态方差贡献为30.75%，主要反映东太平洋赤道潜流的变化特征；第二模态方差贡献为16.18%，主要反映中太平洋赤道潜流的变化特征。赤道潜流前两个模态与ENSO指数的变化有很好的相关关系，其中东太平洋潜流在滞后ENSO指数1个月时，二者达到最大负相关（r=-0.74）。中太平洋赤道潜流的变化对“东部型”和“中部型”El Niño事件的形成有一定影响。“东部型”El Niño事件发生前，中太平洋赤道潜流异常增强，次表层异常海温信号随着潜流中心迅速向东移动到达东太平洋，使得“东部型”El Niño事件爆发；而“中部型”El Niño事件发生前，中太平洋赤道潜流则异常减弱，西太平洋异常海温信号不能迅速向东传播，而是在中西太平洋堆积并向上扩展，使得异常海温首先在中太平洋出现，“中部型”El Niño事件爆发。 4. ENSO循环过程中，异常冷（暖）信号之所以在8ºN-10ºN附近向西传播的原因较多，其中温跃层深度在8ºN-10ºN的特殊分布特征对其有一定贡献，具体表现为在北半球8ºN-10ºN正好是温跃层深度较浅的区域，该区域的温跃层相当于从东到西的一个海下“山脊”，使得来自南北两侧的异常信号都很难穿过这一区域，而只能沿该纬度向西传播；而南半球的温跃层对来自赤道地区的异常信号没有阻挡作用，使其可以直接传播到高纬度地区。ENSO信号的强度在传播过程中发生了明显的变化，主要是ENSO事件爆发后，4-5年的周期信号并没有传到东太平洋10ºN附近，在从东到西的传播过程中，4-5年的周期信号有所增加，但增加的幅度较小。在西太平洋有来自南、北半球中高纬度异常信号的补充，从而使得ENSO循环得以维持。 5. 数值模拟表明，不同区域风应力的变化对海洋的影响各不相同。赤道地区风应力对海洋的影响主要通过纬向分量的变化来产生作用，它的变化主要对赤道次表层海温的变化产生影响，并且东西太平洋呈现反位相变化趋势；而对流场的影响则是上下层反位相变化。北太平洋副热带地区风应力的变化对海洋的影响与赤道有明显不同，对温度场的影响表现为东西太平洋次表层海温的变化一致，而对流速的影响则是东西太平洋反位相变化。

北太平洋低纬度西边界流的时空特征和变异规律研究

北太平洋低纬度西边界流连接着太平洋热带环流和副热带环流，对于世界大洋经向质量、热量和盐量输送起着重要的作用，对北赤道流（NEC）、源区黑潮（KC）和棉兰老流（MC）的时空特征和变异规律进行研究，对认识北太平洋西边界流海洋在全球气候系统中的作用具有重要的理论和实践意义。 本文利用1957-2006年共50年的涡解高分辨率OFES（OGCM for the Earth Simulator）海洋模式资料，对北太平洋低纬度西边界流的时空特征和变异规律进行了分析，结果表明： （1）涡解高分辨率的OFES模式数据结果较SODA能更好地刻画NMK流系三维空间结构的分布特征；黑潮源区涡结构的变化，MUC、 LUC及NEC下的东向流也得到了较好的刻画；其空间结构与实测结果相吻合。 （2）北太平洋低纬度西边界流NMK流系流量具有明显的季节、年际和年代际变化，NEC、KC和MC流量的变化周期频谱较宽,主要为3－6个月的季节振荡和2-7年左右ENSO尺度周期以及10年以上周期的年代际变化。MC主要表现为准两年周期振荡。 （3）NEC、MC流量变化表现为单峰型分布，春季最大（5月），秋季最小（11月）；KC流量的变化为双峰型，大值出现在春季和夏末秋初，春季最大（4月），秋季次之，冬季最小（1月）。在季节时间尺度上，NEC、MC流量同相变化，除冬季外，KC与MC输运反向。 （4） 在年际时间尺度上，受北赤道流流量变化的影响，NEC与KC、MC流量之间为正相关关系；KC与MC分配量（北赤道流向北、向南的经向分配量）之间则为强的负相关关系，其年际异常变化与NEC分叉位置的变化和冷、暖ENSO事件发生密切相关。分叉位置偏北（南）时，KC分配量小（大）而MC分配量大（小）；在El Nino年，KC分配量小，MC分配量大，La Nina年情况则刚好相反。 （5）在年代际时间尺度上，在70年代末气候跃变以后，NEC、KC和MC流量明显减少，NMK环流系统减弱。NEC的减弱主要受上世纪80年代以后ENSO暖事件发生频率和强度的增加所影响，而KC和MC的减弱则主要受NEC减弱控制。同时发现，NEC分叉位置存有明显的年代际变化，在气候跃变以后有长期偏北的趋势，受其影响，与之相对应的是北赤道流向南经向分配量的增加和向北流量分配率的减少。 关键词：北太平洋，低纬度西边界流，北赤道流分叉，ENSO

若干大洋西边界潜流的分布特征及其形成机制

大洋环流是海盆尺度上海水的持久流动，是海洋中质量、热量输运的主要通道，对全球气候变化有重要影响。经过二十年来的大量调查研究，对海洋上层的风生大洋环流有了比较充分的认识。然而，近几十年来的大量观测显示，大洋环流的垂直结构并非像传统认识的那样单一，在很多区域存在与之反向的次表层潜流，如北赤道流（NEC）下方的北赤道逆流（NEUC）、棉兰老海流（MC）下方的棉兰老潜流（MUC），吕宋岛附近黑潮（KC）下方的吕宋潜流（LUC），东澳大利亚海流（EAC）下方的大堡礁潜流（GBRUC）和东澳大利亚潜流（EAUC），阿加勒斯海流（AC）下方的阿加勒斯潜流（AUC）等。这些潜流一般分布在西边界，或者在西边界处增强，称为“西边界潜流（WBUC）”。与表层环流相比，对次表层潜流的结构和形成机制认识不足，因此利用不断更新的各种实测数据和高分辨率同化数据，通过理论分析和数值试验，探讨研究次表层潜流的分布特征和形成机制，对于大洋环流动力学理论的进一步发展具有重要的科学意义。 本文利用中国ARGO资料中心提供的ARGO资料、全球简单海洋资料同化分析系统产生的SODA同化资料和日本地球模拟器模拟出来的OFES资料，分析了北太平洋潜流（NEUC、MUC和LUC）、南太平洋潜流（GBRUC和EAUC）和南印度洋潜流（AUC）的时间和空间分布特征，并基于温跃层以下转向的地转判据分析了其形成机制。主要结果如下： （1）在菲律宾以东海域，表层的NEC在12N附近的西边界分叉，形成向北的KC和向南的MC。在400-800米左右棉兰老岛东侧128E-130E处出现与上层海流方向相反的潜流MUC，MUC在9N和12N附近转向东并分成2支，汇入NEC下方的2支并行向东流的NEUC。到了1000米左右，吕宋岛东侧122E-124E处出现LUC，而MUC也有向岸的趋势，限制在127E以西的范围，两者在12Ｎ附近相遇，然后转向东汇入NEUC。随着深度的加深，NEUC的北侧分支流轴向北偏移。从SODA资料和OFES资料在8N、18N和138E断面的气候态年平均和月平均温度剖面可以很清晰的看出，温跃层分别呈现东高西低、西高东低和南高北低的趋势，这与各个断面上表层流和次表层逆流之间等值线倾斜方向一致。从月平均的速度剖面可以看出，MC一般位于600db以上，600db以下出现北向次表层潜流MUC，MUC春夏较强，秋冬较弱；KC一般位于500db以上，个别月份深入到2000db，其下方均有南向的LUC出现，LUC春夏较弱，秋冬较强；上层西向NEC的主体一般位于400db以上，其下方均有东向的NEUC出现，NEUC春夏较强，秋冬较弱。 在北太平洋菲律宾以东海域，同时满足两个判据的区域与潜流的发生区域符合情况较好，唯一的不同在于LUC汇入NEUC的区域没有同时满足两个判据。这是由于在吕宋岛和棉兰老岛东侧，海底地形较为陡峭，海流情况较为清晰，沿岸涡较少，而且在此区域内温跃层较浅，这些都为形成温跃层以下的地转流反向提供了充分的条件。 （2）在澳大利亚以东海域，表层的南赤道流（SEC）在澳大利亚东岸15S附近分叉，分为向北的北昆士兰海流（NQC）和向南的东澳大利亚海流（EAC）。500m-1000m，23S附近出现一支北向的次表层海流，沿着澳大利亚陆坡经过大堡礁抵达巴布亚新几内亚沿岸转向东，汇入新几内亚沿岸潜流（NGCUC），这支海流就是大堡礁潜流（GBRUC）。1000m-2000m，SEC下方15S附近出现东向的逆流。在2000m以下，由于地形的影响，海流局限在几个不连续的部分，而且流型较乱。从SODA资料和OFES资料在18S和30S断面的气候态年平均和月平均温度剖面可以很清晰的看出，温跃层均呈现西高东低的趋势。在18S，南向的EAC一般位于400db以上，其下方均有持续的GBRUC出现，一般有两个中心，春夏季较强，秋冬季较弱。在30S断面，EAC一般存在于2000db以上，其下方的次表层流并不规则。从此海域的气候态月平均分布来看，在大多月份没有北向的逆流存在，这说明其下方的次表层逆流并不是一个常年存在的现象。 在南太平洋，同时满足两个判据的区域包括SEC下方逆流的发生区域和澳大利亚东岸的沿岸区域，这些区域部分与潜流的发生区域符合较好，只是在30S左右并没有发生潜流的区域也同时满足判据。这是由于在30S附近，温跃层较深，导致了地转流较深，同时此区域内海底地形变化比较大，虽然在此位置形成了逆向的地转流，但是因为地形的限制，在此区域内不能形成有体系的逆流。 （3）在西南印度洋，SEC在非洲东岸分叉，形成一支源于25S的西南向海流——AC，这支海流平均流速达90cm/s左右，最大速度超过140cm/s。在其下方2000m左右，从35S开始在岸边出现东北向逆流——AUC，速度较小，仅为2cm/s左右。从31S、33S和35S断面的气候态年平均温度断面可以很清晰的看出，温跃层明显呈现西高东低的趋势。从月平均经向流速断面可以看出，在各个月份AC下方均出现不同强度的AUC，AC和AUC之间的等值线倾斜方向与温跃层的倾斜方向一致。 在南印度洋，满足判据的区域包括南非沿岸AUC的发生区域和南非东南的部分海域，南非沿岸的AUC紧靠岸边且深度较深，这是因为此区域内温跃层较深，导致形成的地转流位置较深，而形成的逆流由于与海底的摩擦而大大削弱。南非东南部分海域满足判据，大概是由于此区域海流比较复杂，而且此海域多涡。 表面风应力的强迫以及风生环流的斜压调整，使得潜流所在海域的海平面高度和温跃层倾斜方向相反，热带流涡和副热带流涡西向强化加强了该海域温跃层的倾斜程度，从而导致了次表层地转流反向。因此，大洋中次表层潜流是大洋斜压风生环流不可缺少的重要部分。但是在不同的海域存在不同的地形分布和海流分布，所以此理论只在某些合适的区域得到很好的体现。

热带印度洋－太平洋热力异常联合模及其对我国旱涝的影响研究

热带太平洋、印度洋的热力异常对我国夏季降水都有重要影响。然而，由于两大洋的海温变化并非完全孤立，而是相互联系的，因此将两大洋作为一个整体来考虑，研究其热力异常的时空变化，建立一个能够较好表征两大洋热状况变化的联合模指数，进而探讨其对我国旱涝的影响既有重要的理论意义又有明显的实用价值。 本文根据1955－2003年的全球海洋上层热含量资料、SODA数据、我国降水资料、850hPa月平均纬向风资料及副热带高压指数等资料，利用经验正交函数（EOF）分解法和典型相关分析等方法，分析了热带印度洋－太平洋上层热含量距平场的时空变化，提出了一个热带印度洋－太平洋热力异常联合模指数，并研究了该联合模的变化原因及其对我国夏季降水的影响。得到的研究结果主要如下。 1．热带印度洋-太平洋热力异常联合模具有显著的年际和年代际变化，并在1976年前后发生了一次由冷到暖的气候跃变。该联合模的变化特征能够较好地反映出太平洋ENSO和印度洋偶极子的基本信息。 2. 热带印度洋－太平洋热力异常联合模的年代际变化主要是由西太平洋暖池的纬向变异和赤道中东太平洋纬向风异常引起的，而该联合模的年际变化则是西太平洋暖池和东印度洋暖池的纬向变异以及赤道中太平洋和赤道东印度洋纬向风异常共同作用的结果。 3．热带印度洋－太平洋热力异常联合模对我国夏季降水有一年到半年的超前影响，其中以冬季联合模对次年夏季降水的影响最显著。冬季联合模对我国夏季降水的影响可能是通过夏季西太平洋副热带高压的变动来实现的。

O comportamento do consumidor de software de gestão e contabilidade das PMEs em Portugal, França e Espanha

Dissertação de Mestrado apresentada à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Ciências Empresariais.

Effect of glass substrate and deposition technique on the properties of sol gel TiO2 thin films

Na+ ions have a detrimental effect on the photocatalytic activity of thin sot gel films deposited on soda lime glass due to their diffusion into the film during the calcination process. Given that the content of sodium in glass substrate might be the crucial parameter in determining the activity of a photocatalyst, the aim of the present work was the comparison of the photoinduced properties of a thin TiO2 film prepared on three different glass substrates namely on quartz (Q) glass, borosilicate (BS) glass and soda lime (SL) glass which have different sodium content. The prepared layers were characterised by X-ray diffraction and UV-vis spectroscopy. The diffusion of Na+ from the substrate into the layers was determined by Glow Discharge Atomic Emission Spectroscopy. The photocatalytic activities of the films were assessed using two model pollutant test systems (resazurin/resorufin ink and stearic acid film), which appeared to correlate reasonably well. It was observed that TiO2 layer on SL glass has a brookite crystalline structure while the TiO2 layer on BS and Q glass has an anatase crystalline structure. On the other hand, the photodegradation of the model dye on TiO2 films deposited on Q and BS glass is about an order higher than on SL glass. The low sodium content of BS glass makes it the most suitable substrate for the deposition of photoactive sol gel TiO2 films. (C) 2011 Elsevier B.V. All rights reserved.

The potential for kelp manufacture to lead to arsenic pollution of remote Scottish islands

Burning seaweed to produce kelp, valued for its high potash and soda content, was formerly a significant industry in remote coastal areas of Scotland and elsewhere. Given the high concentrations of arsenic in seaweeds, up to 100 mg kg(-1), this study investigates the possibility that the kelp industry caused arsenic contamination of these pristine environments. A series of laboratory-scale seaweed burning experiments was conducted, and analysis of the products using HPLC ICP-MS shows that at least 40% of the arsenic originally in the seaweed could have been released into the fumes. The hypothesis that the burning process transforms arsenic from low toxicity arsenosugars in the original seaweeds (Fucus vesiculosus and Laminaria digitata) to highly toxic inorganic forms, predominantly arsenate, is consistent with As speciation analysis results. A field study conducted on Westray, Orkney, once a major centre for kelp production, shows that elevated arsenic levels (10.7+/-3.0 mg kg(-1), compared to background levels of 1.7+/-0.2 mg kg(-1)) persist in soils in the immediate vicinity of the kelp burning pits. A model combining results from the burning experiments with data from historical records demonstrates the potential for arsenic deposition of 47 g ha(-1) year(-1) on land adjacent to the main kelp burning location on Westray, and for arsenic concentrations exceeding current UK soil guideline values during the 50 year period of peak kelp production.

Multiplex Touchdown PCR for Rapid Typing of the Opportunistic Pathogen Propionibacterium acnes.

The opportunistic human pathogen Propionibacterium acnes is comprised of a number of distinct phylogroups, designated types IA1, IA2, IB, IC, II and III, that vary in their production of putative virulence factors, inflammatory potential, as well as biochemical, aggregative and morphological characteristics. Although Multilocus Sequence Typing (MLST) currently represents the gold standard for unambiguous phylogroup classification, and individual strain identification, it is a labour and time-consuming technique. As a consequence, we have developed a multiplex touchdown PCR assay that will, in a single reaction, confirm species identity and phylogeny of an isolate based on its pattern of reaction with six primer sets that target the 16S rRNA (all isolates), ATPase (type IA1, IA2, IC), sodA (type IA2, IB), atpD (type II) and recA (type III) housekeeping genes, as well as a Fic family toxin gene (type IC). When applied to 312 P. acnes isolates previously characterised by MLST, and representing type IA1 (n=145), IA2 (n=20), IB (n=65), IC (n=7), II (n=45) and III (n=30), the multiplex displayed 100% sensitivity and 100% specificity for the detection of isolates within each targeted phylogroup. No cross-reactivity with isolates from other bacterial species was observed. The multiplex assay will provide researchers with a rapid, high-throughput and technically undemanding typing method for epidemiological and phylogenetic investigations. It will facilitate studies investigating the association of lineages with various infections and clinical conditions, as well as a pre-screening tool to maximise the number of genetically diverse isolates selected for downstream, higher resolution sequence-based analyses.

Impacts of Milk Fraud on Food Safety and Nutrition with Special Emphasis on Developing Countries

Milk in its natural form has a high food value, since it is comprised of a wide variety of nutrients which are essential for proper growth and maintenance of the human body. In recent decades, there has been an upsurge in milk consumption worldwide, especially in developing countries, and it is now forming a significant part of the diet for a high proportion of the global population. As a result of the increased demand, in addition to the growth in competition in the dairy market and the increasing complexity of the supply chain, some unscrupulous producers are indulging in milk fraud. This malpractice has become a common problem in the developing countries, which lack strict vigilance by food safety authorities. Milk is often subjected to fraud (by means of adulteration) for financial gain, but it can also be adulterated due to ill-informed attempts to improve hygiene conditions. Water is the most common adulterant used, which decreases the nutritional value of milk. If the water is contaminated, for example, with chemicals or pathogens, this poses a serious health risk for consumers. To the diluted milk, inferior cheaper materials may be added such as reconstituted milk powder, urea, and cane sugar, even more hazardous chemicals including melamine, formalin, caustic soda, and detergents. These additions have the potential to cause serious health-related problems. This review aims to investigate the impacts of milk fraud on nutrition and food safety, and it points out the potential adverse human health effects associated with the consumption of adulterated milk.

Mercury (II) removal from aqueous solutions by microporous materials

O Mercúrio é um dos metais pesados mais tóxicos existentes no meio ambiente, é persistente e caracteriza-se por bioamplificar e bioacumular ao longo da cadeia trófica. A poluição com mercúrio é um problema à escala global devido à combinação de emissões naturais e emissões antropogénicas, o que obriga a políticas ambientais mais restritivas sobre a descarga de metais pesados. Consequentemente o desenvolvimento de novos e eficientes materiais e de novas tecnologias para remover mercúrio de efluentes é necessário e urgente. Neste contexto, alguns materiais microporosos provenientes de duas famílias, titanossilicatos e zirconossilicatos, foram investigados com o objectivo de avaliar a sua capacidade para remover iões Hg2+ de soluções aquosas. De um modo geral, quase todos os materiais estudados apresentaram elevadas percentagens de remoção, confirmando que são bons permutadores iónicos e que têm capacidade para serem utilizados como agentes descontaminantes. O titanossilicato ETS-4 foi o material mais estudado devido à sua elevada eficiência de remoção (>98%), aliada à pequena quantidade de massa necessária para atingir essa elevada percentagem de remoção. Com apenas 4 mg⋅dm-3 de ETS-4 foi possível tratar uma solução com uma concentração igual ao valor máximo admissível para descargas de efluentes em cursos de água (50 μg⋅dm-3) e obter água com qualidade para consumo humano (<1.0 μg⋅dm-3), de acordo com a legislação Portuguesa (DL 236/98). Tal como para outros adsorbentes, a capacidade de remoção de Hg2+ do ETS- 4 depende de várias condições experimentais, tais como o tempo de contacto, a massa, a concentração inicial de mercúrio, o pH e a temperatura. Do ponto de vista industrial as condições óptimas para a aplicação do ETS-4 são bastante atractivas, uma vez que não requerem grandes quantidades de material e o tratamento da solução pode ser feito à temperatura ambiente. A aplicação do ETS-4 torna-se ainda mais interessante no caso de efluentes hospitalares, de processos de electro-deposição com níquel, metalúrgica, extracção de minérios, especialmente ouro, e indústrias de fabrico de cloro e soda cáustica, uma vez que estes efluentes apresentam valores de pH semelhantes ao valor de pH óptimo para a aplicação do ETS-4. A cinética do processo de troca iónica é bem descrita pelo modelo Nernst-Planck, enquanto que os dados de equilíbrio são bem ajustados pelas isotérmicas de Langmuir e de Freundlich. Os parâmetros termodinâmicos, ΔG° and ΔH° indicam que a remoção de Hg2+ pelo ETS-4 é um processo espontâneo e exotérmico. A elevada eficiência do ETS-4 é confirmada pelos valores da capacidade de remoção de outros materiais para os iões Hg2+, descritos na literatura. A utilização de coluna de ETS-4 preparada no nosso laboratório, para a remoção em contínuo de Hg2+ confirma que este material apresenta um grande potencial para ser utilizado no tratamento de águas. ABSTRACT: Mercury is one of the most toxic heavy metals, exhibiting a persistent character in the environment and biota as well as bioamplification and bioaccumulation along the food chain. Natural inputs combined with the global anthropogenic sources make mercury pollution a planetary-scale problem, and strict environmental policies on metal discharges have been enforced. The development of efficient new materials and clean-up technologies for removing mercury from effluents is, thus, timely. In this context, in my study, several microporous materials from two families, titanosilicates and zirconosilicates were investigated in order to assess their Hg2+ sorption capacity and removal efficiency, under different operating conditions. In general, almost all microporous materials studied exhibited high removal efficiencies, confirming that they are good ion exchangers and have potential to be used as Hg2+ decontaminant agents. Titanosilicate ETS-4 was the material most studied here, by its highest removal efficiency (>98%) and lowest mass necessary to attain it. Moreover, according with the Portuguese legislation (DL 236/98) it is possible to attain drinking water quality (i.e. [Hg2+]< 1.0 μg⋅dm-3) by treating a solution with a Hg2+ concentration equal to the maximum value admissible for effluents discharges into water bodies (50 μg⋅dm-3), using only 4 mg⋅dm-3 of ETS-4. Even in the presence of major freshwater cations, ETS-4 removal efficiency remains high. Like for other adsorbents, the sorption capacity of ETS-4 for Hg2+ ions is strongly dependent on the operating conditions, such as contact time, mass, initial Hg2+ concentration and solution pH and, to a lesser extent, temperature. The optimum operating conditions found for ETS-4 are very attractive from the industrial point of view because the application of ETS-4 for the treatment of wastewater and/or industrial effluents will not require larges amounts of adsorbent, neither energy supply for temperature adjustments becoming the removal process economically competitive. These conditions become even more interesting in the case of medical institutions liquid, nickel electroplating process, copper smelter, gold ore tailings and chlor-alkali effluents, since no significant pH adjustments to the effluent are necessary. The ion exchange kinetics of Hg2+ uptake is successfully described by the Nernst-Planck based model, while the ion exchange equilibrium is well fitted by both Langmuir and Freundlich isotherms. Moreover, the feasibility of the removal process was confirmed by the thermodynamic parameters (ΔG° and ΔH°) which indicate that the Hg2+ sorption by ETS-4 is spontaneous and exothermic. The higher efficiency of ETS-4 for Hg2+ ions is corroborate by the values reported in literature for the sorption capacity of other adsorbents for Hg2+ ions. The use of an ETS-4 fixed-bed ion exchange column, manufactured in our laboratory, in the continuous removal of Hg2+ ions from solutions confirms that this titanosilicate has potential to be used in industrial water treatment.

GET YOUR Iron FROM THE Food YOU EAT.

Iron helps your blood carry enough oxygen to all parts of your body. Low iron levels can make you feel tired, grumpy, or more likely to become ill. You can do four things to build up iron in your blood: Eat several of these iron rich foods daily ; Eat a vitamin C-rich food with your iron food ; Cook more often in an iron skillet ; Avoid tea, chocolate, coffee, soda.

Inventário hidrogeológico e dos potenciais focos de contaminação nas bacias hidrográficas da Asprela e Massarelos: implicações no ciclo hidrológico urbano

O desenvolvimento incessante em áreas urbanas ameaça a qualidade e quantidade das águas subterrâneas. O Porto é uma cidade densamente urbanizada, dominada por granitos, os quais constituem um meio fraturado anisotrópico e heterogéneo. O principal objetivo desta dissertação foi realçar a importância da cartografia hidrogeológica, bem como a relevância de realizar inventários hidrogeológicos e de potenciais focos de contaminação para compreender a vulnerabilidade dos sistemas aquíferos na cidade do Porto. Para tal, foram selecionadas as bacias hidrográficas da Asprela e de Massarelos. Assim, foram levados a cabo dois inventários, um hidrogeológico e outro das potenciais atividades de contaminação. O estudo foi apoiado pelos Sistemas de Informação Geográfica (SIG), os quais foram fundamentais para um melhor conhecimento e integração nas áreas de estudo. Previamente à implementação dos inventários foi feita uma caracterização das duas bacias, em termos geográficos, hidroclimatológicos, de ocupação do solo, geomorfológicos e hidrogeológicos. As duas bacias desenvolvem‐se, principalmente, na unidade hidrogeológica do granito de grão médio a fino, por vezes com saprólito. O inventário hidrogeológico contemplou principalmente fontanários e nascentes, tendo incluído, respetivamente, 8 e 21 pontos de água nas bacias da Asprela e de Massarelos. As águas subterrâneas são límpidas, sem turvação ou cheiro, ácidas, com mineralizações baixas a médias, temperaturas baixas e caudais muito pequenos. Quanto aos potenciais focos de contaminação, na bacia da Asprela foram reconhecidos 61, enquanto que na bacia de Massarelos foram identificados 78. A maioria destas atividades é pontual correspondendo, nomeadamente, a estabelecimentos de ensino e estações de serviço/oficinas de automóveis. Contudo, os focos lineares apresentam uma difusão significativa nas duas bacias hidrográficas. Apesar de a vulnerabilidade intrínseca à contaminação das águas subterrâneas nestas áreas ser baixa a moderada, a localização dos potenciais focos de contaminação poderá ser responsável pelo aumento da vulnerabilidade nas duas bacias estudadas. Esta metodologia demonstrou ser extremamente importante para um melhor conhecimento dos sistemas de água subterrânea do Porto e, ainda, da hidrogeologia de áreas urbanas.

Three essays in risky behaviors

A PhD Dissertation, presented as part of the requirements for the Degree of Doctor of Philosophy from the NOVA - School of Business and Economics