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Shared energy storage has the potential to decrease the expenditure and operational costs of conventional energy storage devices. However, studies on shared energy storage configurations have primarily focused on the peer-to-peer competitive game relation among agents, neglecting the impact of network topology, power loss, and other practical factors on energy storage configuration. Additionally, they do not differentiate between various roles of agents, such as shared energy storage operators, electricity consumers, and distribution network operators. To address the challenges presented by the complex interest structures, diverse usage patterns, and potentially sensitive location associated with shared energy storage, we present a multi-agent model for shared energy storage services that takes into account the perspectives of different actors in distribution networks. We develop a tri-level programming model for the optimal allotment of shared energy storage and employ a combination of analytical and heuristic methods to solve it. A case study demonstrates that our model can attain effective allocation of shared energy storage, take into account the interests of multiple parties, and converge well. We examine the impacts of different energy storage service patterns on distribution network operation modes and compare the benefits of shared and non-shared energy storage patterns. By analyzing data on the cost of operating distribution networks, voltage stability, and distributed power consumption, we investigate the potential advantages of the multi-agent distributed shared energy storage service pattern in distribution networks. Our research provides valuable insights into implementing shared energy storage on a large scale in distribution networks. • A multi-agent model for distributed shared energy storage services is proposed. • A tri-level model is designed for optimizing shared energy storage allocation. • A hybrid solution combining analytical and heuristic methods is developed. • A comparative analysis reveals shared energy storage's features and advantages. [ABSTRACT FROM AUTHOR]

• A protection inductor used in the energy system of the laser fusion facility as the protection component is designed and its reliability is proved by the finite element simulation and experimental testing. • The structure of the protection inductor is introduced and the inductor is of low production cost and processing difficulty. • The design method of inductor parameters is presented based on temperature constraint and the design method is simplified by using the material with low temperature coefficient of resistance. High energy density capacitor banks are used in pump power supplies of the laser fusion facility. The capacitor bank works in the state of high voltage and enormous energy, so it is vital to protect the capacitor bank from faults, especially capacitor internal insulation breakdown. In that case, the discharge circuit will be a huge short-circuit current and cause serious structure and fire damage to the capacitor and nearby components. In this paper, a protection inductor is designed to protect the capacitor bank applied to the 100 kA/1 MJ discharge condition. The solenoid inductor coil is made of manganin wire and installed in the epoxy resin cylinder. The design process of the coil is simplified by using the material with low temperature coefficient of resistance, and the design method of inductor parameters is presented based on temperature constraint. It is found that the von Mises stress in the designed inductor is below the ultimate tensile strength of the materials by finite element simulation. A simulated fault current discharge platform was built to test the inductor, and the inductor keeps structure integrity after the test. The inductor design method can provide guidance for the protection design of the capacitive power supply system. [ABSTRACT FROM AUTHOR]

Heat shock response (HSR), in terms of transcription regulation of two heat shock proteins genes hsp70 and hsp90 ), was analysed in a widespread tropical copepod Pseudodiaptomus annandalei . The mRNA transcripts of both genes were quantified after copepods at a salinity of 20 underwent an acclimation process involving an initial acclimation temperature of 29 °C, followed by gradual thermal ramping to the target exposure temperature range of 24–36 °C. The respective cellular HSR and organismal metabolism, measured by respiratory activity at exposure temperatures, were compared. The fold change in mRNA expression for both hsp70 and hsp90 (8–9 fold) peaks at 32 °C, which is very close to 32.4 °C, the upper thermal optimum for respiration in the species. Unexpectedly, the modelled HSR curves peak at only 3 °C ( hsp90 ) and 3.5 °C ( hsp70 ) above the mean water temperature (29.32 °C) of the copepod in the field. We propose that copepods in tropical waters adopt a preparative HSR strategy, early at the upper limit of its thermal optimum, due to the narrow thermal range of its habitat thus precluding substantial energy demand at higher temperatures. However, the model suggests that the species could survive to at least 36 °C with short acclimation time. Nevertheless, the significant overlap between its thermal range of hsp synthesis and the narrow temperature range of its habitat also suggests that any unprecedented rise in sea temperature would have a detrimental effect on the species. [ABSTRACT FROM AUTHOR]

Under natural application conditions, water in the forms of condensates and high-speed raindrops tend to form Wenzel contact with the surface of superhydrophobic coatings, and in this case, the effect of the standing water on the abrasion mechanisms of superhydrophobic coatings is not clear. To investigate the issue, comparative tests of abrasion-induced aging on the surface of the superhydrophobic coating under dry, and water infiltration conditions are conducted. A theoretical prediction model of the friction magnitude on the surface of the superhydrophobic coating under the above two conditions is established, and the experimental phenomenon is analyzed based on the theoretical results of the model. The results show that once water wets superhydrophobic surfaces in Wenzel mode, the microscopic rough structures on the surfaces are more likely to fall off under external friction due to the presence of Laplace pressure, which means that the presence of water makes the superhydrophobic surfaces more prone to abrasion-induced aging in this condition. [Display omitted] [ABSTRACT FROM AUTHOR]

The polyamide 66 (PA66) fabrics are hard to be colored or glued in industrial production due to the poor hydrophily. Diffuse plasma is a kind of non-thermal plasma generated at atmospheric pressure in air. This paper proposes that large-scale diffuse plasma generated between wire electrodes can be employed for improving the hydrophily of PA66 fabrics. A repetitive nanosecond-pulse diffuse-discharge reactor using a cylindrical wire electrode configuration is presented, which can generate large-scale non-thermal plasmas steadily at atmospheric pressure without any barrier dielectric. Then the reactor is used to treat PA66 fabrics in different discharge conditions. The hydrophilicity property of modified PA66 is measured by wicking test method. The modified PA66 is also analyzed by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) to prove the surface changes in physical microstructure and chemical functional groups, respectively. What's more, the effects of treatment time and treatment frequency on surface modification are investigated and discussed. [ABSTRACT FROM AUTHOR]

Methyl-silica superhydrophobic coatings have the capability of providing anti-pollution flashover protection for outdoor electrical insulators. However, in practical applications, the deposition and dissolution of atmospheric pollutants on the coating generates acidic or alkaline ions and leads to chemical degradation of the coating's surface property, which in turn causes a decrease in the anti-pollution flashover performance of the coating. Currently, there is a lack of research on the hydrophobic degradation characteristics of superhydrophobic methyl-silica coatings induced by chemical corrosion. Meanwhile, it is not clear how chemical corrosion affects the anti-pollution flashover performance of methyl-silica superhydrophobic coatings. To address the above issues, the static water contact angle and sliding angle on the corroded methyl-silica superhydrophobic coatings were tested to reflect the surface hydrophobicity degradation, and the results were theoretically interpreted; the surface leakage current amplitudes of the coatings aged to different degrees were measured under dirty and wet conditions to characterize the anti-pollution flashover performance of the corroded coatings. The surface leakage current amplitudes of the aged methyl-silica superhydrophobic coating under different corrosion environment temperatures, different applied electric field strengths, and different wetting times of surface pollutants are measured to characterize the anti-pollution flashover performance of the corrosion-aged coating, and the influences of the above factors on the anti-pollution flashover performance of the methyl-silica superhydrophobic coating are analyzed. [Display omitted] [ABSTRACT FROM AUTHOR]

The effect of isotretinoin on the chemotaxis of human monocytes was studied in an in vitro system using a Nucleopore chamber. The chemoattractant used was zymosan-activated serum. Inhibition of monocyte chemotaxis was achieved with isotretinoin in concentrations of 1 × 10-3 M and 5 × 10-4 M. It is felt that the improvement seen in patients with inflammatory skin diseases such as cystic acne and acne conglobata who are treated with isotretinoin may in part be a result of this anti-inflammatory action. [ABSTRACT FROM AUTHOR]

The chitosan/polyvinyl Alcohol/zeolite electrospun composite nanofibrous membrane was fabricated for adsorption of methyl orange. The EDX, TGA and tensile test were carried out for the characterization of the membrane. The Young’s Modulus of the nanofibrous membranes increased by more than 100% with the addition of zeolite to chitosan/PVA. The batch adsorption tests were conducted by varying the initial concentration of methyl orange, contact time and pH of the dye solution. UV–vis results showed that most of the dye was adsorbed within 6 min. An adsorption kinetic study was carried out using the pseudo-second-order kinetic model, Lagergren-first-order model and intra particle diffusion model. The adsorption kinetics obeyed the Pseudo second order model. The adsorption mechanism was analyzed using the Langmuir and Freundlich isotherm model. The experimental data fits well with the Freundlich model. The adsorption capacity of the membrane was 153 mg/g. Adsorption capacity was decreased with increasing pH value. The resulting nanofiber became less active over methyl orange after several runs. [ABSTRACT FROM AUTHOR]

Superhydrophobic (SH) and superamphiphobic (SAP) coatings have been viewed as an alternative to conventional hydrophobic room temperature vulcanizing (RTV) silicone rubber coatings in anti-pollution flashover application. However, being one of the most important properties in RTV-based anti-flashover materials and devices, the hydrophobicity transfer property was rarely documented for SH and SAP coatings, which restricts their practical applications in environments with heavy contamination. Herein, we propose for the first time a superhydrophobicity transfer effect in superwetting (SW) coatings (e.g., SAP and SH coatings) containing low-surface-energy molecules (e.g., polydimethylsiloxane (PDMS)) as a migratory reagent. When the surface is stained by artificial simulated pollutants, PDMS molecules can migrate from the coating to the contamination layer, followed by a surface modification. Through this process, the surface wettability of the contaminant layer gradually evolves from superhydrophilicity to hydrophobicity, and finally to SH state. This evolution is investigated in relation to the amount and species of migratory reagents, migration time, pollution grade, and pollutant species. The superhydrophobicity transfer effect offers the coated glass insulators an outstanding anti-pollution flashover strength. This work can provide a novel and universal protocol to realize a superhydrophobicity transfer property in SW coatings, which may stimulate further investigation and applications in not only anti-pollution flashover but also other fields such as anti-fouling and anti-icing. • Superhydrophobicity transfer effect is proposed for the first time. • Superwetting coatings with superhydrophobicity transfer property are obtained. • The mechanism behind the superhydrophobicity transfer effect is proposed. • Superhydrophobicity transfer effect improves the anti-pollution flashover strength of insulator. [ABSTRACT FROM AUTHOR]

Using micro-nanostructure superhydrophobic coating with the unique self-cleaning phenomenon is a feasible method to further reduce the frequency of insulator pollution flashover. However, the research on the anti-pollution flashover performance of superhydrophobic coating is still insufficient. This paper analyzes the various types of forces on the polluted particles accumulated on the superhydrophobic coating surface, and calculates that the vertical force or the horizontal force on the nano-scale and micro-scale particles is positive when they are in contact with most types of droplets. After being fully wetted, these particles are easily absorbed or pulled by the droplets and leave the coating surface. So it is necessary to establish a new DC pollution flashover mechanism model of superhydrophobic coatings surface from the electric field perspective. Based on this model, the relationship between the pollution flashover voltage and the dry flashover voltage is clarified in the state of extremely small leakage current. Furthermore, the anti-pollution flashover performance experiment was carried out on superhydrophobic coating, RTV coating, and uncoated surface to test the leakage current under different conditions. The experimental results show that at any pollution degree, the leakage current of superhydrophobic coating surface always remains about 16.3μA after being completely wetted. [Display omitted] [ABSTRACT FROM AUTHOR]

Ecosystem carbon stocks were compared in three island mangrove forests, subjected to different anthropogenic stresses, close to Port Klang in Selangor State on the west coast of Peninsular Malaysia. Carbon stocks in living biomass, litter, deadwood and soil were quantified, and the carbon isotopic signature in mangrove soils was also measured, to estimate their carbon source. We hypothesize that carbon stock would be more readily available in undisturbed mangroves. The results indicated that, in general, soil organic carbon pool comprised the majority of the ecosystem carbon stock, while dead organic matter made a negligible contribution. The highest ecosystem carbon stock was measured in the permanent undisturbed mangrove reserve on Pulau Klang. Carbon isotope data revealed that disturbed mangroves in Pulau Ketam had a more enriched δ13C signature of soil samples compared to the other two sites. The soil organic carbon in Pulau Ketam was mostly derived from mangrove materials (92.8%). The results suggested that the organic carbon accumulated in the soils was not only regulated by the burial of mangrove-derived organic carbon, but also the site conditions. • Ecosystem carbon stock in mangrove environment can be influenced by its land use status. • Soil organic carbon in undisturbed mangrove forest can contribute to the majority of the ecosystem carbon stock, regardless of the vegetation stands. • Isotope data revealed that the mangrove leaf and suspended particulate organic matter in the sea water are the sources of soil organic matter. [ABSTRACT FROM AUTHOR]

• A 1.46 MJ capacitive pulsed power supply is designed by using the pulse thyristors. • The synchronous triggering of multiple sets of thyristors enables high current output of the pulsed power supply. • The high gate trigger system is developed to control the synchronous conduction of the thyristors of each module. • Simulation and project experience show that the high-probability failure will not affect the other components in the power supply. In order to study the adaptation of the semiconductors for the special power supply application, a capacitive pulsed power supply is designed by using the pulse thyristors. The modular integrated method is adopted to redesign the main circuit of the power supply. The synchronous triggering of multiple sets of thyristors enables high current output of the pulsed power supply, which can avoid excessive current passing through the thyristors and eliminate current-sharing measures of the thyristors. Applying the fast switching MOSFET and magnetic induction of pulse transformer, a set of high gate trigger system is developed to control the synchronous conduction of the thyristors of each module. The simulation and experimental results show that most of the faults occurring during the operation of the pulsed power supply can be limited by protection devices. Practical operation indicates that the pulse power supply can provide specific required pulse current and energy for the pulsed xenon lamp. The design method of the pulsed power supply can provide a reference for the design of the pulsed power supply, and lay a foundation for the higher capacitive energy storage application. [ABSTRACT FROM AUTHOR]

Cleanliness and desiccative are necessary for outdoor insulation surfaces to maintain the voltage withstand capability especially in humid and polluted operation conditions. Once the voltage withstanding capability of insulation coatings is reduced by contaminant electrolyte, flashover accidents would be easier to happen, causing tremendous economy and energy losses. Superhydrophobic coatings, due to their self-cleaning property, are deemed to have great application potential in maintaining outdoor insulation performance, especially in humid and polluted environments. The water patterns on superhydrophobic coating in humid and polluted conditions are obviously different from those on traditional insulation coatings. Flashover voltage is one of the indices for quantifying insulation strength, while to date it is still unclear whether the commonly-used flashover voltage prediction models based on Obenaus's theory are still suitable to be applied in the cases with superhydrophobic surface. Here we proposed a facile and low-cost preparation method of superhydrophobic coating. By analyzing the specific surface condition under humid and polluted conditions, and considering the development of arc path, a novel theoretical model for predicting flashover voltage of superhydrophobic coatings is established from the perspective of electric field. The flashover voltage of the synthesized coating as well as Room Temperature Vulcanized (RTV) silicone rubber coating are tested and compared, for investigating the insulation strength on the synthesized superhydrophobic coating, and verifying the accuracy of the proposed prediction model. It is found the synthesized superhydrophobic coating shows self-cleaning property during the wetting and voltage applying process, the flashover voltage of superhydrophobic coating is higher than that of RTV coating, and is affected less obviously by the change in pollution degree, compared with RTV coating. The established model shows better accuracy in predicting the flashover voltage of superhydrophobic coating than the traditional one, with errors of less than 6%. Based on the proposed model, the flashover voltage of polluted superhydrophobic coating surface is positively and negatively related to the volume and the contact angle of the polluted electrolyte droplet, respectively. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: S. aureus bacteremia (SAB) is a severe systemic illness, which is associated with high mortality and healthcare cost. It has been reported that older age per se is a poor prognostic factor of SAB, but little is known whether poor clinical outcomes is related to conservative attitudes of treating physicians. A retrospective cohort of 126 patients (mean age: 73.7±13.6years, 72.2% males) with community-onset SAB during 2004–2008 in a tertiary medical center in Taiwan was obtained for study. Demographic data, clinical characteristics, primary infectious focus, metastatic lesions, access to critical care units, performance of invasive procedures, Charlson comorbidity index (CCI) and in-hospital mortality for all study subjects were collected. The overall in-hospital mortality was 32.5%, which was not significantly different between adult and elderly groups. SAB of elderly patients was more likely to be primary than that of the adult patients (20.4% vs. 3.6%, p =0.043). Deep-seated abscess, osteomyelitis and metastatic lesion with central nervous system (CNS) involvement were more common infection foci in the adult patient group. Chronic obstructive pulmonary disease and cerebrovascular accident were more common underlying conditions of the elderly group. Chances of patients admitted to intensive care unit and employment of invasive procedures were not different between groups although elderly patients were supposed to be of a greater risk of mortality. In conclusion, the overall in-hospital mortality of community-onset SAB was 32.5%, which was not different between age groups. In general, older patients were of similar chance to receive critical care and invasive procedures except arterial line and non-tunneled central venous catheters. Further prospective investigation is needed to clarify whether physicians hold different attitudes to older patients with SAB and the differences in treatment attitude resulting in poorer clinical outcomes. [Copyright &y& Elsevier]

The application of the superhydrophobic coating is expected to be an effective method to further improve the pollution flashover voltage of insulators. However, so far, the relationship between electric field strength, droplet volume, and sliding angle in strong electric fields is not clear. This is not conducive to the evaluation of the practical application effect of superhydrophobic insulators. In this paper, the self-cleaning property of superhydrophobic coating and the critical motion condition of droplets in the electric field were analyzed theoretically. Then an experimental platform was set up to observe the movement of the droplet driven by the electric field, and the critical electric field strength for droplet motion was measured. Experimental and theoretical analysis results show that the critical electric field strength for positive droplet motion is less than that for the negative droplet. The droplet driven by the electric field can also remove water-insoluble pollution particles. And the maximum pollution concentration that droplets can remove by means of self-cleaning performance is calculated theoretically. The theoretical calculation method of the sliding angle of superhydrophobic coating in uniform DC electric field is obtained, which is in good agreement with the experimental results. This paper provides theoretical support for evaluating the practical performance of the superhydrophobic insulator in strong electric fields. [Display omitted] [ABSTRACT FROM AUTHOR]

Thin-layer chromatography and infrared reflectance spectroscopy were compared as methods for measuring sebum composition. Solutions of varying known Concentrations of free fatty acids and triglycerides were analyzed by both methods. Skin surface lipid samples were similarly analyzed. Infrared spectroscopy produced more variable data than thin-layer chromatography with photodensitometry. This was particularly true at low concentrations of free fatty acids. It is concluded that thin-layer chromatography with photodensitometry is a more accurate method for the measurement of sebum composition. [ABSTRACT FROM AUTHOR]

If the apparent contact angle (ACA) of superhydrophobic materials could be significantly affected by drop volume, it would not be reliable to use ACA as an important index to evaluate the wettability of superhydrophobic materials. In order to explore the effect of drop volume on the ACA of hierarchical structured superhydrophobic surfaces, two kinds of hierarchical structured superhydrophobic surfaces, natural lotus leaf surface and superhydrophobic coating, were used for experimental analysis. In addition, a physical model of ACA considering drop volume was established. And the relationship curve between drop volume and ACA was calculated. The experiment and simulation results show that for each kind of drop, the volume has no significant effect on the ACA of hierarchical structured superhydrophobic surfaces. And the ACA can reflect the wettability of the superhydrophobic material effectively. [ABSTRACT FROM AUTHOR]

Barnacles are ubiquitous in coastal ecosystems of different geographical regions worldwide. This is the first study attempting to assess the suitability of barnacles as bioindicators of persistent organic pollutants (POPs) in coastal environments. Barnacles were collected from the coasts around Peninsular Malaysia and analyzed for POPs including polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and organochlorine pesticides (OCPs). Among POPs, PCBs showed the highest concentrations with elevated contributions of CB28 and CB153. As for PBDEs, BDE47 was the most frequently detected congener, while BDE209 was detected in barnacles from two stations in Port Klang and the levels reached up to >70% of total PBDE concentrations. Concentrations of OCPs detected in barnacles were in the order of CHLs > DDTs > HCHs > HCB and 4,4′-DDE and cis - and trans -chlordane were the predominant OCP compounds. A comparison with previous studies in Malaysia showed consistent levels of POPs. Green mussels collected from selected barnacles' habitats, for the sake of a comparison, showed almost similar profiles but lower concentrations of POPs. The spatial distribution of POPs observed in barnacles and comparison of POP levels and profiles with mussels indicated that barnacles can be useful bioindicators for monitoring POPs contamination in the coastal ecosystems. Image 1 • Coastal biomonitoring survey on POPs was conducted using barnacles from Malaysia. • Elevated levels of PCBs and PBDEs were found in barnacles from a populated area. • Compositions of CHLs, DDTs and HCHs indicated their recent use. • Almost similar profiles of POPs were observed between barnacles and mussels. • Barnacles can be useful bioindicators of POPs in coastal ecosystems worldwide. [ABSTRACT FROM AUTHOR]

We have shown previously that human genome editing can be performed at high efficiency using designed zinc finger nucleases (ZFNs). ZFNs can be engineered to generate a double-strand break at a specific chromosomal location both in transformed and primary human cells. These breaks are repaired by the cell's own DNA repair machinery, and when a homologous extrachromosomal donor molecule is provided, a homology-directed repair process leads to highly efficient transfer of single-base-pair changes into the chromosome (Urnov et al. Nature 435: 646). ZFNs can be engineered to target virtually any chromosomal location (Pabo et al., Ann. Rev. Biochem. 70: 313), and function robustly in human hematopoietic stem cells, hence such localized gene modification may potentially be useful in the correction and treatment of certain monogenic diseases. Here we show that ZFNs can also be used for the preciseinsertion of a novel sequence into a pre-determined location in the human genome. Remarkably, this novel sequence can constitute a short patch sequence or several kilobases of one or more transgenes. We have observed ZFN-driven targeted integration into endogenous chromosomal loci in human cells of entire open reading frames and promoter-transcription units at a frequency of 5% in the absence of any selection. We also show the use of this process to disrupt with high efficiency an endogenous chromosomal locus with a selectable marker ORF. Finally, we describe our work on using ZFN-driven integration to insert a therapeutically-relevant transgene into a “safe-harbor” locus in the human genome, potentially avoiding the problem of insertional mutagenesis. Hence, the homology-directed repair process invoked by the ZFNs can be used to carry out high-efficiency targeted integration to potentially improve the safety and efficacy of gene therapy.Molecular Therapy (2006) 13, S386–S387; doi: 10.1016/j.ymthe.2006.08.1097 [ABSTRACT FROM AUTHOR]

HIV entry into target cells requires binding of the envelope protein GP120 to the CD4 co-receptors CCR5 or CXCR4. Loss of these HIV co-receptors is therefore attractive as a potential therapy for HIV patients, yet no current methods permit the efficient therapeutic disruption of a chosen gene in the human genome. To this end, we have developed designed zinc-finger protein nucleases (ZFNs) to target predetermined sequences within the CCR5 gene. Once these ZFNs create a double strand break (DSB) in the targeted DNA, natural DNA repair pathways, including Non-Homologous End Joining (NHEJ), subsequently repair the DSB. Importantly, however, NHEJ is error prone and thus can result in permanent disruption of the targeted gene.Designed ZFNs that recognize coding sequences within the CCR5 gene were generated and their DNA-binding and cleavage properties were determined in vitro. Vectors encoding the validated ZFNs were introduced into human cells for in vivo assessment of function. ZFNs targeted to the CCR5 co-receptor efficiently cleaved their expected DNA target sites, leading to high efficiency target gene disruption (>5%) in transiently transfected cells even in the absence of selective pressure. These results have been confirmed in relevant primary cell types (monocytes, CD4+ T cells, CD34+ hematopoietic precursors). We also demonstrated that PM-1 and GHOST cells modified by the CCR5-ZFNs became resistant to HIV infection. Challenge assays using T cells pre-treated with these ZFNs are in progress, although it is well established that a patients cells carrying a deletion within the CCR5 gene are resistant to infection despite repeated exposure to R5-tropic virus. Moreover, the frequency of gene disruption observed supports its examination as a possible method for the therapeutic modification of isolated patient cells to generate HIV resistant T cells or hematopoietic precursors.Molecular Therapy (2006) 13, S293–S293; doi: 10.1016/j.ymthe.2006.08.842 [ABSTRACT FROM AUTHOR]

Zinc finger nucleases have been shown to be effective tools for high-frequency genome editing with potential therapeutic applications (Urnov et al., Nature 435:646-651). Such nucleases are created by fusing the cleavage domain of the type IIs restriction enzyme Fok I to engineered zinc finger proteins. One limitation of this architecture is that the natural Fok I cleavage domain must dimerize in order to cleave DNA; therefore two different zinc finger protein-Fok I fusions are required to introduce a double-stranded break at an asymmetric target site. As a consequence, use of this technology for genome editing may expose the cell to three different nuclease species – the desired heterodimer as well as two homodimers which are irrelevant to the desired process but which may still contribute to off-target cleavage events.Creating Fok I cleavage domain variants that do not function as homodimers would eliminate the possibility of off-target cutting by these species and would also increase the availability of the desired heterodimer. In order to develop such variants, we used a process of iterative structure-based design and screening in which candidate designs were tested for their ability to cleave DNA in vitro and for their ability to potentiate gene correction in a reporter cell line. A pair of nuclease variants, each containing two mutations at the dimerization interface, were developed that worked well when paired together, but were severely impaired when paired with a second copy of themselves. These mutant cleavage domains were substituted for the wild-type FokI cleavage domains in the reagents used by Urnov et al. and tested for their ability to induce sequence alterations at the endogenous human common gamma chain gene. In this system we observed that a heterodimer of our designed cleavage domains was as active as wild type Fok I at stimulating gene correction while inducing significantly fewer overall DNA cutting events. Moreover, homodimers of the designed Fok I cleavage domain variants were completely inactive. These studies demonstrate that we have successfully developed Fok I cleavage domain variants that function as obligate heterodimers. These variants should be broadly useful for increasing the potency and specificity of designed zinc finger nucleases.Molecular Therapy (2006) 13, S305–S305; doi: 10.1016/j.ymthe.2006.08.875 [ABSTRACT FROM AUTHOR]