Multichamber Device Research Articles

Features of the structure of coatings of tungsten and chromium carbides during detonation-gas spraying with energy accumulation in a multichamber device

Features of the structure of coatings of tungsten and chromium carbides during detonation-gas spraying with energy accumulation in a multichamber device

An easy-to-open multi-chamber device to study the molecular changes behind the plant root microscale phenotypic variations

Plant chips provide non-destructive, real-time, continuous high-resolution observations of plant development. However, the observations are limited to phenotypic changes such as morphology, number, growth rate, etc. Herein, we developed an easy-to-open multi-chamber device, namely a Lid open-seal Switchable Plant Chip (LSPC), to achieve high spatial observation and periodically collect plant samples for biochemical analysis. The proposed multi-chamber device was applied to study the morphological and molecular changes of the fibrous root system of O.Sativa. The result showed that switching the lid of the growth chambers did not affect the seedling growth. The physical damages on the root cap and tip were modeled on-chip to study the root regeneration capacity. The results showed that physical damage localized at the root cap did not ramp the renewal of the root tip. Periodically collecting root structures, such as border-like cells and root tips, was demonstrated to measure reactive oxygen species and soluble sugar. Last, the root tip swelling phenomenon was observed from the seedlings growing in 10 % and 20 % PEG 6000 mimicked drought environment. The swelling roots were collected for biochemical assays and found that the histology swelling was accompanied by an accumulation of soluble sugar within the root tip. The transcript levels of OsjDHN1, C4-PEPC, NAC1, PCD, and P450 genes in drought-induced swelling tips were significantly different from normal seedlings. The swelling tip phenomenon, corresponding soluble sugar level, and gene transcript changes will help underlie the plant adaptation response mechanisms to drought stress.

A Multi-Chamber Paper-Based Platform for the Detection of Amyloid β Oligomers 42 via Copper-Enhanced Gold Immunoblotting.

The early diagnosis of Alzheimer’s disease (AD) remains a challenge for medical scientists worldwide, leading to a number of research efforts that focus on biosensor development for AD biomarkers. However, the application of these complicated biosensors is limited in medical diagnosis, due to the difficulties in robust sensing platform development, high costs, and the necessity for technical professionals. We successfully developed a robust straightforward manufacturing process for the fabrication of multi-chamber paper devices using the wax printing method and exploited it to detect amyloid beta 42 oligomers (AβO42, a significant biomarker of AD) using copper-enhanced gold nanoprobe colorimetric immunoblotting. Small hydrophilic reaction chambers could concentrate the target sample to the desired size to improve the sensing performance. The copper-enhanced gold nanoprobe immunoblot using the designed multi-chamber platform exhibited a highly sensitive performance with a limit of detection of 320 pg/mL by the naked eye and 23.7 pg/mL by a smartphone camera. This process from sensing manufacture to sensing conduction is simple to perform whenever medical technicians require time- and cost-savings, without complicated instruments or the need for technical professionals, making it feasible to serve as a diagnostic tool worldwide for the early monitoring of AD and scalable devices for the sensing application of various biomarkers in clinical settings.

The role of implantable cardioverter-defibrillators and sudden cardiac death prevention: indications, device selection, and outcome.

Multiple randomized multicentre clinical trials have established the role of the implantable cardioverter-defibrillator (ICD) as the mainstay in the treatment of ventricular tachyarrhythmias and sudden cardiac death (SCD) prevention. These trials have focused mainly on heart failure patients with advanced left ventricular dysfunction and were mostly conducted two decades ago, whereas a more recent trial has provided conflicting results. Therefore, much remains to be determined on how best to balance the identification of patients at high risk of SCD together with who would benefit most from ICD implantation in a contemporary setting. Implantable cardioverter-defibrillators have also evolved from the simple, defibrillation-only devices implanted surgically to more advanced technologies of multi-chamber devices, with physiologic bradycardic pacing, including cardiac resynchronization therapy, atrial and ventricular therapeutic pacing algorithms, and subcutaneous ICDs. These multiple options necessitate individualized approach to device selection and programming. This review will focus on the current knowledge on selection of patients for ICD treatment, device selection and programming, and future directions of implantable device therapy for SCD prevention.

Co-cultivation of the marine sponge Halichondria panicea and its associated microorganisms

Marine sponges host bacterial symbionts with biotechnological potential, yet isolation of true sponge symbionts remains difficult due to their host dependency. Moreover, attempts to grow sponges for their pharmacologically-active compounds outside of their habitat often results in a shift of their microbial community. In this study we evaluate suitable sponge cultivation methods that allow maintenance of both the marine sponge Halichondria panicea and its associated bacteria in an ex situ environment. In addition, we present a method for co-cultivation of sponge explants and microbes separated by a membrane in a multi-chamber device. Tests on ex situ cultivation of H. panicea under different controlled conditions showed that only high water exchange rates in the aquarium enabled maintenance of its dominant symbiont “Candidatus Halichondribacter symbioticus” at a high relative abundance in the sponge body, a prerequisite for co-cultivation. The bacterial enrichment retrieved from co-cultivation contained bacteria from nine different classes in addition to sequences corresponding to “Ca. H. symbioticus”. This represents an increase of the cultivable bacterial classes from H. panicea compared to standard isolation techniques on solid media plates. The current study provides insights into sponge-microbe maintenance under ex situ conditions and proposes a new method for the isolation of sponge-associated bacteria.

Leukocyte Migration and Deformation in Collagen Gels and Microfabricated Constrictions.

In multicellular organisms, cell migration is a complex process. Examples of this are observed during cell motility in the interstitial space, full of extracellular matrix fibers, or when cells pass through endothelial layers to colonize or exit specific tissues. A common parameter for both situations is the fast adaptation of the cellular shape to their irregular landscape. In this chapter, we describe two methods to study cell migration in complex environments. The first one consists in a multichamber device for the visualization of cell haptotaxis toward the collagen-binding chemokine CCL21. This method is used to study cell migration as well as deformations during directed motility, as in the interstitial space. The second one consists in microfabricated channels connected to small constrictions. This procedure allows the study of cell deformations when single cells migrate through small holes and it is analogous to passage of cells through endothelial layers, resulting in a simplified system to study the mechanisms operating during transvasation. Both methods combined provide a powerful hub for the study of cell plasticity during migration in complex environments.

Laudation for PD Dr. Wolfgang Ahlf to celebrate his 65th birthday

In 1982, the University of Technology Hamburg-Harburg (TUHH), Germany, installed a new section under the programme title BPreventive Environmental Protection Technologies in an Ecological Context^. In retrospective, it was less difficult to find a director and a chief engineer, doctoral students and laboratory staff; rather, the search was for a broadly qualified biologist, who could manage the embedding of the other scientists and engineers within an ecological concept. The practical issues that the section needed to address were common knowledge in the BHamburg industrial landscape^: historical contaminated sediments in the Elbe, dredged materials in the harbour, arsenic in air and soil around the BAffi^ (the Norddeutsche Affinerie, a copper ore refinery and well-known industrial polluter in the 1970s and 1980s that was close to Hamburg) and soon the situation culminating in the international case of dioxins at Georgswerder. Professor AdolfWeber, director at the Botanical Institute of the University of Hamburg and an expert on environmental issues in the Hamburg State planning group, convinced a promising young colleague (Ahlf 1983) to join our team. At the end, even the administration at TUHH changed its strict department structure rules to provide a permanent position to Wolfgang Ahlf. Wolfgang Ahlf and his Becotoxicology^ research group fulfilled its specific mandate in all respects. Our Monday morning meetings got instructions at different levels, from scientific publishing to global environmental ethics, and our projects and those of the neighbouring departments were checked for their ecological correctness. The two big Collaborative Research Programs of the German Research Foundation (DFG), SFB 327 Interactions between Abiotic and Biotic Processes in the Tidal Elbe (1986–1995) and, particularly, SFB 188 Treatment of Contaminated Soil (1988–2000) profited much from Wolfgang Ahlf’s competence, eloquence and ecological spirit. During all these years, one cannot remember the failure of any proposal when he was personally involved. In our transdisciplinary view, one of the secrets for success of the Harburg ecotoxicologists was their pragmatic approach. From the beginning, the group focussed on interfaces and on real world situations rather than on models. The typical test systems for the study of competing sorption and uptake of contaminants by different substrates and organisms were two-chamber and multichamber devices (Ahlf 1985). The biggest challenge for ecotoxicologists is the transfer of laboratory and field results into risk assessment schemes and finally into regulations. The activities of Wolfgang Ahlf during the last 25 years centred around microbial biotests for the toxicological assessment of contaminated sediments, both in the international network of the Society of Environmental Toxicology and Chemistry (SETAC) and with a national focus on the contact test (Feiler et al. 2013). In 2002,Wolfgang Ahlf was appointed to the national committee of experts for the authorisation of plant protection products. Since 2003, the group undertook a new orientation in the direction of an ecological assessment of chemicals in foodstuffs. Since the beginning of the Journal of Soils and Sediments in 2001 until 2015, Wolfgang Ahlf served as a valuable member of the Editorial Board and both his * Ulrich Forstner u.foerstner@tu-harburg.de

Methods of Uranium Hexafluoride Purification

The article contains an analytical overview of techniques used for UF6 purification. Structures of respective devices have been considered. Their advantages and drawbacks have been outlined. It has been shown that heat discharge desublimators and multi-chamber devices with two heated walls are the most efficient in UF6 purification.

β-amyloid induces a dying-back process and remote trans-synaptic alterations in a microfluidic-based reconstructed neuronal network.

IntroductionRecent histopathological studies have shown that neurodegenerative processes in Alzheimer’s and Parkinson’s Disease develop along neuronal networks and that hallmarks could propagate trans-synaptically through neuronal pathways. The underlying molecular mechanisms are still unknown, and investigations have been impeded by the complexity of brain connectivity and the need for experimental models allowing a fine manipulation of the local microenvironment at the subcellular level.ResultsIn this study, we have grown primary cortical mouse neurons in microfluidic (μFD) devices to separate soma from axonal projections in fluidically isolated microenvironments, and applied β-amyloid (Aβ) peptides locally to the different cellular compartments. We observed that Aβ application to the somato-dendritic compartment triggers a “dying-back” process, involving caspase and NAD+ signalling pathways, whereas exposure of the axonal/distal compartment to Aβ deposits did not induce axonal degeneration. In contrast, co-treatment with somatic sub-toxic glutamate and axonal Aβ peptide triggered axonal degeneration. To study the consequences of such subcellular/local Aβ stress at the network level we developed new μFD multi-chamber devices containing funnel-shaped micro-channels which force unidirectional axon growth and used them to recreate in vitro an oriented cortico-hippocampal pathway. Aβ application to the cortical somato-dendritic chamber leads to a rapid cortical pre-synaptic loss. This happens concomitantly with a post-synaptic hippocampal tau-phosphorylation which could be prevented by the NMDA-receptor antagonist, MK-801, before any sign of axonal and somato-dendritic cortical alteration.ConclusionThanks to μFD-based reconstructed neuronal networks we evaluated the distant effects of local Aβ stress on neuronal subcompartments and networks. Our data indicates that distant neurotransmission modifications actively take part in the early steps of the abnormal mechanisms leading to pathology progression independently of local Aβ production. This offers new tools to decipher mechanisms underlying Braak's staging. Our data suggests that local Aβ can play a role in remote tauopathy by distant disturbance of neurotransmission, providing a putative mechanism underlying the spatiotemporal appearance of pretangles.Electronic supplementary materialThe online version of this article (doi:10.1186/s40478-014-0145-3) contains supplementary material, which is available to authorized users.

Portable, fully autonomous, ion chromatography system for on-site analyses

The basic operating principles of a portable, fully autonomous, ion chromatography system are described. The system affords the user the ability to collect and analyze samples continuously for 27 days, or about 1930 injections before needing any user intervention. Within the 13kg system, is a fully computer controlled autosampling, chromatography and data acquisition system. An eluent reflux device (ERD), which integrates eluent suppression and generation in a single multi-chambered device, is used to minimize eluent consumption. During operation, about 1μL of water per minute is lost to waste while operating standard-bore chromatography at 0.5mLmin−1 due to eluent refluxing. Over the course of 27 days, about 100mL of rinse water is consumed, effectively eliminating waste production. Data showing the reproducibility (below 1% relative standard deviation over 14 days) of the device is also presented. Chromatographic analyses of common anions (Cl−, NO3−, SO42−, PO43−), is accomplished in under 15min using a low backpressure guard column with ∼25mM KOH isocratic elution. For detection, a small capacitively-coupled contactless conductivity detector (C4D) is employed, able to report analytes in the sub to low micromolar range. Preconcentration of the injected samples gives a 50-fold decrease in detection limits, primarily utilized for in-situ detection of phosphate (LOQ 10μgL−1). Field analyses are shown for multiple on-site analyses of stream water indifferent weather conditions.

ß-amyloid induces a dying-back process and remote trans-synaptic alterations in a microfluidic-based reconstructed neuronal network

Recent histopathological studies have shown that neurodegenerative processes in Alzheimer's and Parkinson's Disease develop along neuronal networks and that hallmarks could propagate trans-synaptically through neuronal pathways. The underlying molecular mechanisms are still unknown, and investigations have been impeded by the complexity of brain connectivity and the need for experimental models allowing a fine manipulation of the local microenvironment at the subcellular level. In this study, we have grown primary cortical mouse neurons in microfluidic (μFD) devices to separate soma from axonal projections in fluidically isolated microenvironments, and applied β-amyloid (Aβ) peptides locally to the different cellular compartments. We observed that Aβ application to the somato-dendritic compartment triggers a “dying-back” process, involving caspase and NAD+ signalling pathways, whereas exposure of the axonal/distal compartment to Aβ deposits did not induce axonal degeneration. In contrast, co-treatment with somatic sub-toxic glutamate and axonal Aβ peptide triggered axonal degeneration. To study the consequences of such subcellular/local Aβ stress at the network level we developed new μFD multi-chamber devices containing funnel-shaped micro-channels which force unidirectional axon growth and used them to recreate in vitro an oriented cortico-hippocampal pathway. Aβ application to the cortical somato-dendritic chamber leads to a rapid cortical pre-synaptic loss. This happens concomitantly with a post-synaptic hippocampal tau-phosphorylation which could be prevented by the NMDA-receptor antagonist, MK-801, before any sign of axonal and somato-dendritic cortical alteration. Thanks to μFD-based reconstructed neuronal networks we evaluated the distant effects of local Aβ stress on neuronal subcompartments and networks. Our data indicates that distant neurotransmission modifications actively take part in the early steps of the abnormal mechanisms leading to pathology progression independently of local Aβ production. This offers new tools to decipher mechanisms underlying Braak's staging. Our data suggests that local Aβ can play a role in remote tauopathy by distant disturbance of neurotransmission, providing a putative mechanism underlying the spatiotemporal appearance of pretangles.

Time-domain modeling of a fixed detached oscillating water column towards a floating multi-chamber device

A simplified time-domain model for a fixed detached Oscillating Water Column (OWC) device is presented as a first step towards modeling a floating multi-chamber OWC device. The motion of a floating body in the time-domain is expressed by Cummins integro-differential equation, and based on it, water mass motion inside the chamber has been modeled here as a piston-like motion. Radiation, hydrostatic, excitation and viscous forces have been considered, as well as the added mass of the water in the chamber and the effect of the air pressure inside it. The equation of the floating body in the time domain has been approximated by a state-space method, which comes from the extension of the state-space system corresponding to the convolution integral of the radiation force. Experimental data have been used for model calibration and validation. Furthermore, the model has also been validated with a widely used Computational Fluid Dynamics (CFD) model (IH-2VOF). These show that the model presented is reliable and computationally efficient allowing for massive simulations for a statistical design or economic feasibility studies.

Pressures and Timing of Intermittent Pneumatic Compression Devices for Efficient Tissue Fluid and Lymph Flow in Limbs with Lymphedema

Pneumatic compression of tissues with lymph stasis is, aside from the manual massage, a commonly used therapeutic modality in limb lymphedema. A number of pneumatic devices have been constructed. There is lack of reports of comparative studies determining inflation pressure levels, inflation/deflation cycle times, and total pumping times. We tried to answer the question how high compression pressure and how long compression timing should be applied to the limb soft tissues to reach tissue fluid (TF) head pressure above 30 mmHg, necessary to initiate proximal flow. TF pressures were measured subcutaneously during intermittent pneumatic compression in the lymphedematous limbs stage II to IV. Pressures of 50, 80, and 120 mmHg and timing 5, 20, and 50 sec were applied. a) the TF head pressures were lower than those in inflated chambers, b) inflation time of 5 and 20 sec was not long enough to generate TF head pressures above 30 mmHg, even if the compression pressures were as high as 120 mmHg, c) the 50 sec timing allowed to reach head pressures above 30 mmHg; however, they remained always lower than in the compression chamber, d) TF head pressures differed at various levels of the limb depending on the soft tissue mass, e) deflation of the inflated whole sleeve for 5 and 20 sec was followed by high end pressures, whereas that of 50 sec brought about pressure drop to 0, facilitating refilling with TF of the distal parts of the massaged limb. Our observations point to the necessity of applying high pressures and compression times over 50 sec, to generate effective TF pressures and provide enough time for creating TF flow. Short inflation times generate TF pressures as in one-chamber devices that preclude its effectiveness compared to the multi-chamber devices.

Ultrafast Amplification of DNA on Plastic Microdevices for Forensic Short Tandem Repeat Analysis

The majority of microfluidic devices used as a platform for low-cost, rapid DNA analysis are glass devices; however, microchip fabrication in glass is costly and laborious, enhancing the interest in polymeric substrates, such as poly (methyl methacrylate) (PMMA), as an inexpensive alternative. Here, we report amplification in PMMA polymerase chain reaction (PCR) microchips providing full short tandem repeat profiles (16 of 16 loci) in 30-40 min, with peak height ratios and stutter percentages that meet literature threshold requirements. In addition, partial profiles (15 of 16 loci) were generated using an ultrafast PCR method in 17.1 min, representing a ~10-fold reduction in reaction time as compared to current amplification methods. Finally, a multichamber device was demonstrated to simultaneously amplify one positive, one negative, and five individual samples in 39 min. Although there were instances of loci dropout, this device represents a first step toward a microfluidic system capable of amplifying more than one sample simultaneously.

Simultaneous Use of Two External Subcutaneous Pumps Delivering Insulin and SYMLIN: Use of a Double-Pump System

The combination of insulin and an amylin mimetic is an option for diabetes treatment.1,2 The effectiveness of this modality has been established, but there is a limited amount of literature regarding the use of this combined treatment via continuous subcutaneous infusion by external pumps. A short 16-week trial of 10 patients studied the pharmacokinetics of pramlintide (SYMLIN®, Amylin Pharmaceuticals, LLC, San Diego, CA) in continuous subcutaneous infusion and found this modality to be safe and well tolerated.3 Treatment was initiated in a small study of 10 subjects (7 females and 3 males) with age range 24-69 years. There were 5 patients with type 1 diabetes and 5 with type 2 diabetes (duration of diabetes: 15-38 years). Patients were switched from conventional multiple-dose insulin injection therapy or oral hypoglycemic agents to the combination of insulin and SYMLIN via continuous subcutaneous infusion using two external pumps simultaneously. Treatment was continued over a period of 1-5 years. Hemoglobin A1c (HbA1c), total daily insulin, total daily SYMLIN, weight, and blood glucose levels were measured, with follow-up ranging from 1-5 years. Patients using the double-pump system showed an average reduction in HbA1c from 8.3% to 6.9%. Total daily insulin was reduced from an average of 147 to 96 units per day. SYMLIN dosages increased from an average of 35 units per day to 50 units per day (Figure 1). Weight reduction was noted, with an initial average of 132 to 500 lb, decreasing to 110 to 360 lb. Figure 1 Insulin dosage vs SYMLIN dosage over duration of study. Amylin conversion of units to micrograms: 1 unit = 6 μg. Patients were treated with basal SYMLIN 0.5-2.5 unit/h (3-15 μg). Meal bolus was 2.5-10 units (15-60 μg). All patients completed a satisfaction survey and expressed satisfaction with the treatment regimen but indicated their preference for a dual or multichamber device. They also noted that they would not return to conventional SYMLIN injections if given the choice. We conclude that continuous infusion of insulin and SYMLIN via a pump system is a viable and effective therapeutic option. In this small observational study, all patients showed improvement in metabolic and weight control over a period of 1-5 years. Further studies with a larger population and a control group are needed to empower these results.

How, Why, and When May Atrial Defibrillation Find a Specific Role in Implantable Devices? A Clinical Viewpoint

This viewpoint article discusses the potential for incorporation of atrial defibrillation capabilities in modern multi-chamber devices. In the late 1990s, the possibility of using shock-only therapy to treat selected patients with recurrent atrial fibrillation (AF) was explored in the context of the stand-alone atrial defibrillator. The failure of this strategy can be attributed to the technical limitations of the stand-alone device, low tolerance of atrial shocks, difficulties in patient selection, a lack of predictive knowledge about the evolution of AF, and, last but not least, commercial considerations. An open question is how atrial defibrillation capability may now assume a specific new role in devices implanted for sudden death prevention or cardiac resynchronization. For patients who already have indications for implantable devices, device-based atrial defibrillation appears attractive as a "backup" option for managing AF when preventive pharmacological/electrical measures fail. This and several other personalized hybrid therapeutic approaches await exploration, though assessment of their efficacy is methodologically challenging. Achievement of acceptance by patients is an essential premise for any updated atrial defibrillation strategy. Strategies that are being investigated to improve patient tolerance include waveform shaping, pharmacologic modulation of pain, and patient-activated defibrillation (patients might also perceive the problem of discomfort somewhat differently in the context of a backup therapy). The economic impact of implementing atrial defibrillation features in available devices is progressively decreasing, and financial feasibility need not be a major issue. Future studies should examine clinically relevant outcomes and not be limited (as occurred with stand-alone defibrillators) to technical or other soft endpoints.

Low-cost and Chemical Resistant Microfluidic Devices Based on Thermoplastic Elastomers for a Novel Biosensor System

AbstractLow-cost and chemical resistant microfluidic devices based on thermoplastic elastomers have been fabricated by hot embossing technology. Commercial available thermoplastic elastomer foils based on polyurethane (PU) in a thickness range of 100-600 μm have been used. Prior to the fabrication of the microfluidic devices the chemical resistance of the material against a wide range of standard biological buffer solutions and solvents had been analysed. We created systems of channels, reservoirs and holes for the connections to external capillaries by double-sided hot embossing with an alignment accuracy of +/- 3 micrometer. Closed channel structures were produced by an additional chemical bonding process of the embossed devices with another thermoplastic elastomer foil. The total volume of the fluidic cell was 2 μl/sensor for the use with SAW (surface-acoustic wave) sensor chip and about 0.2 μ/sensor for the impedance sensors. A novel multi-chamber fluidic device was successfully tested for in-situ immobilization of thrombin antibodies and Bovin Serum Albumin (BSA) on different sensor elements of the same sensor chip.

Studies on the transfer of heavy metals between sedimentary phases with a multi-chamber device: Combined effects of salinity and redox variation

FSrstner, U., Ahlf, W. and Calmano, W., 1989. Studies on the transfer of heavy metals between sedimentary phases with a multi-chamber device: combined effects of salinity and redox variation. Mar. Chem., 28: 145-158. Mobilization and transfer of heavy metals to major sediment components after changes of typical estuarine conditions (salinity, redox potential/pH) have been studied in a newly developed experimental device, consisting of a central chamber connected with six external chambers and separated by membranes of 0.45-~m pore diameter. Algal cell walls (Scenedesmus quadricauda), bentonite, Al-oxide, Mn-oxide, quartz powder and goethite were used as model sediment components. Significant metal enrichment was found on algal cell walls, and on freshly precipitated iron hydroxide. Oxidation of anoxic mud from Hamburg harbour causes lowering of pH and remobilization of cadmium and zinc. The experiments on the effect of seawater on sediment components and dredged mud indicate the dominant role of organic substrates in the binding of metals such as cadmium and copper, suggesting that even at relatively small percentages of organic substrates these materials are primarily involved in metabolic processes and thus may constitute the major carriers by which metals are transferred within the food chain. These results demonstrate that it is particularly problematic to disperse waste materials in ecologically productive, high-energy environments such as estuaries.

A miniaturized multichamber solution isoelectric focusing device for separation of protein digests.

A miniaturized multichamber device was constructed for solution isoelectric focusing (IEF) separation of complex peptide mixtures. The system, based on immobilized pH gels, consisted of 96 minichambers ( approximately 75 nuL each) arranged in eight rows. Neighboring chambers in a given row were separated by short glass tubes (4 mm inner diameter, 3 mm long), within which Immobiline gels of specific pH values were polymerized. During focusing, the device was sandwiched between two supporting blocks incorporating the reservoirs for anolyte and catholyte. In principle, multiple samples could be simultaneously fractionated, each separated into 12 fractions of various pI ranges. A variety of standard peptide mixtures and tryptic digests of proteins were separated by IEF using this device, and the fractions were characterized by mass spectrometry. For a codigested nine-protein mixture, both the total number of peptides identified and the average sequence coverage were similar to the results of ion-exchange chromatography (IEC), according to matrix assisted laser/desorption/ionization--time of flight (MALDI-TOF) data. The IEF separation provided concentrated and desalted fractions, suitable for an additional separation liquid chromatography, capillary electrophoresis (LC, CE) or mass spectrometry (MS) detection without additional sample cleanup. High loading capacity was achieved for the miniaturized multichamber IEF device. Importantly, a linear correlation was found between the experimentally determined and calculated pI values of peptides.

Preliminary studies on mobilisation of copper and lead from contaminated soils and readsorption on competing sorbents

The mobilisation and transfer of copper and lead from polluted soil (sample taken from the vicinity of copper smelter) to five different — mainly clayey — competing sorbents have been studied using a multichamber device. The system consists of a central chamber which contained the soil suspension and six external chambers containing the different sorbents: zeolite, smectite, vermiculite, diatomite and halloysite. The solids in the central and external chambers are separated by 0.45 μm membranes which allow diffusion of the mobilised, dissolved metal constituents. In the central chamber the metals from the soil were mobilised by decrease of pH (< 5). The readsorbed amounts of Cu and Pb were obtained by taking samples after different time periods. The copper is mobilised to a higher degree than lead. The distribution of Cu is dominated by transfer and readsorption on smectite and zeolite, and also on halloysite at higher pH. Lead is mainly readsorbed on zeolite, and, at lower pH, on halloysite and smectite as well. Under the applied experimental conditions no significant transfer of both the Cu and Pb to the vermiculite and diatomite could be observed. These results indicate the higher affinity of lead on zeolite if compared with smectite; however, the latter remains the most effective sorbent of Cu. A mixture of smectite and zeolite is proposed for soil remediation procedures.