Pure Fusion Research Articles

The entanglement of fusion energy research and bombs

ABSTRACT The recent achievement of fusion ignition—meaning more energy came out of a self-sustaining fusion reaction than was put in—at Lawrence Livermore National Laboratory’s National Ignition Facility has brought to the fore long-simmering questions about whether certain experiments violate the Comprehensive Test Ban Treaty on nuclear explosions. Fusion research for peaceful use and military use are highly intertwined, despite attempts to cloak nuclear weapons with the aura of the so-called “peaceful atom.” Ignition has been achieved, but there is still a remarkable silence around whether pure fusion weapons—weapons that could kill large numbers of humans with neutron radiation but have blast effects much smaller than current thermonuclear weapons—are an objective of the overall program. Even if not an explicit objective, would they be built if fusion technology makes them feasible?

The impact of neutral beam parameters on current drive and neutron yield in DEMO-FNS tokamak

DEMO-FNS (DEMO Fusion Neutron Source) will be a hybrid reactor designed to combine fusion and fission technologies. In a hybrid reactor the power is mainly produced by a fission blanket which is exposed to the neutron flux generated by confined fusion plasma used as a Fusion Neutron Source (FNS). The steady-state operation of the FNS is easier to achieve as compared to pure fusion reactors, allowing the FNS to be more compact. The DEMO-FNS will produce 40 MW of fusion power. The neutral beam injectors (NBI) are designed to provide a steady state plasma heating, rotation, fueling, current drive and neutron generation in DEMO-FNS. Four injector units will deliver 30 MW power in deuterium with energy Eb = 500 keV. The NBI concept and main components are inspired from ITER HNBI design implementing acceleration of negative ions with their neutralization on gas.The high density of injected power in DEMO-FNS leads to a very specific operation scenario with ahigher ratio of high-energy ions in the plasma with respect to conventional tokamaks, where the mainpart of neutron flux will result from fusion between hot-tail ions and relatively coldbackground. The current drive and neutron yield produced by the tangentially injected beam in asteady-state operation are strongly affected by magnetic configuration and plasma kineticprofiles. The fast ions deposition and performance in plasma are limited by the losses associatedwith the neutral beam shape and aiming. The main channels of direct beam losses includeshine-through losses, as well as fast ion orbital losses. The detailed evaluation of NB parametersand geometry effects is a necessary step of scenario optimization.BTR code (Beam Transmission or, in earlier versions, Beam Transmission with Reionization) is intended for injector beamlines study, and BTR detailed beam model can be also applied to perform a detailed analysis of beam losses and performance in plasma. The analysis of beam in plasma shows the ways towards higher values of beam driven current (NBCD) and neutral yield; the beam-in-plasma behaviour can be tuned for a given tokamak configuration. The NB tracing model workflow is implemented in the BTOR suite (Beam in TORoids). The results for DEMO-FNS are compared with the NBI performance in ITER tokamak, as both machines are beam-driven and implement a similar NBI concept.

Pure kernel graph fusion tensor subspace clustering under non-negative matrix factorization framework

Currently, graph-based multi-kernel subspace clustering methods have achieved rich research results in dealing with nonlinear data structures. However, most of the methods still have the following two limitations: (1) the model optimization goal is finding the optimal consensus kernel rather than the optimal affinity graph, which leads to kernel noise always interfering with the learning of the target affinity graph in the optimization process; (2) in the process of finding the optimal affinity graph, only the correlation between different kernel views is exploited, ignoring the higher-order correlation between multiple kernel views. In light of this, we propose a pure kernel graph fusion tensor (PKGT) subspace clustering under non-negative matrix factorization (NMF) framework. Specifically, we first use NMF to construct local affinity feature graphs with standard block diagonal structure for each base kernel matrix, and then achieve adaptive weight assignment by optimizing the inconsistencies among multiple local affinity feature graphs. Finally, we use tensor to capture the higher-order correlation between multiple local affinity feature graphs to provide more feature information for the learning of optimal target affinity graph, which enhances the model clustering performance. Extensive experiments on nine real datasets demonstrate that PKGT has superior clustering performance. The code is available at https://github.com/ZS0124/PKGT.

Multi-Focus Microscopy Image Fusion Based on Swin Transformer Architecture

In this study, we introduce the U-Swin fusion model, an effective and efficient transformer-based architecture designed for the fusion of multi-focus microscope images. We utilized the Swin-Transformer with shifted window and path merging as the encoder for extracted hierarchical context features. Additionally, a Swin-Transformer-based decoder with patch expansion was designed to perform the un-sampling operation, generating the fully focused image. To enhance the performance of the feature decoder, the skip connections were applied to concatenate the hierarchical features from the encoder with the decoder up-sample features, like U-net. To facilitate comprehensive model training, we created a substantial dataset of multi-focus images, primarily derived from texture datasets. Our modulators demonstrated superior capability for multi-focus image fusion to achieve comparable or even better fusion images than the existing state-of-the-art image fusion algorithms and demonstrated adequate generalization ability for multi-focus microscope image fusion. Remarkably, for multi-focus microscope image fusion, the pure transformer-based U-Swin fusion model incorporating channel mix fusion rules delivers optimal performance compared with most existing end-to-end fusion models.

A Safer, Smaller, Cleaner Subcritical Thorium Fission—Muonic Fusion Hybrid Reactor

Until the pure fusion ages come true, present nuclear power is a crucial option if humanity takes aim for a zero net carbon society by the 2050s. A thorium subcritical reactor activated and controlled by muon-catalyzed fusion (MuCF) is an alternative until the completion of the pure fusion reactors. This proposal consists of two main technologies: a steady-state MuCF and the thorium subcritical fission reactor with cascaded neutron multipliers. It will be an environmentally friendly quantum energy source built only by the present science and technologies in a few decades.

FUSION BREEDING AND PURE FUSION DEVELOPMENT – PERCEPTIONS AND MISPERCEPTIONS

This paper examines fusion breeding, namely the use of 14 MeV fusion neutrons to breed 233U fuel for thermal nuclear reactors. This can be accomplished much more quickly than pure fusion. It can become main component of a power architecture that is economical, environmentally sound and has little if any proliferation risk

Civilization Needs Sustainable Energy – Fusion Breeding May Be Best

Civilization requires power. For a while it can get by with the power supplies we currently use, fossil fuel, nuclear fuel; and hydroelectric, solar and wind. Only the last 3 are sustainable. The first two will run out as some point, very likely well before the end of this century, especially if the less developed parts of the world come up to OECD standards. This paper makes the case that solar and wind are not up to the job, and neither is pure fusion, at least in this century. However, using fusion to breed fissile material for current nuclear reactors could play an important role well before century’s end. The requirements on a fusion device used as a breeder are considerably relaxed from the requirements for pure fusion. It is likely that an ITER type device, could be used for fusion breeding on a large scale. Fusion breeding can support nuclear fuel for civilization, at 30- 40 terawatts (TW), at least as far into the future as the dawn of civilization was in the past.

Phenotypic Consequences of SLC25A40-ABCB1 Fusions beyond Drug Resistance in High-Grade Serous Ovarian Cancer.

Simple SummaryAmong the plethora of malignancies affecting the female reproductive tract, those concerning the ovary are the most frequently fatal. In particular, chemotherapy-resistant High-Grade Serous Ovarian Cancer (HGSOC) remains a clinically intractable disease with a high rate of mortality. We previously identified SLC25A40-ABCB1 transcriptional fusions as the driving force behind drug resistance in HGSOC. As success in the clinical arena will only be achieved by enhancing our fundamental understanding of the drivers that mediate cellular drug resistance, this report sought to elucidate the phenotypic, metabolomic and transcriptional consequences of SLC25A40-ABCB1 fusions beyond drug resistance. High-throughput FDA drug screening was also undertaken to identify new therapeutic avenues against drug-resistant cellular populations.Despite high response rates to initial chemotherapy, the majority of women diagnosed with High-Grade Serous Ovarian Cancer (HGSOC) ultimately develop drug resistance within 1–2 years of treatment. We previously identified the most common mechanism of acquired resistance in HGSOC to date, transcriptional fusions involving the ATP-binding cassette (ABC) transporter ABCB1, which has well established roles in multidrug resistance. However, the underlying biology of fusion-positive cells, as well as how clonal interactions between fusion-negative and positive populations influences proliferative fitness and therapeutic response remains unknown. Using a panel of fusion-negative and positive HGSOC single-cell clones, we demonstrate that in addition to mediating drug resistance, ABCB1 fusion-positive cells display impaired proliferative capacity, elevated oxidative metabolism, altered actin cellular morphology and an extracellular matrix/inflammatory enriched transcriptional profile. The co-culture of fusion-negative and positive populations had no effect on cellular proliferation but markedly altered drug sensitivity to doxorubicin, paclitaxel and cisplatin. Finally, high-throughput screening of 2907 FDA-approved compounds revealed 36 agents that induce equal cytotoxicity in both pure and mixed ABCB1 fusion populations. Collectively, our findings have unraveled the underlying biology of ABCB1 fusion-positive cells beyond drug resistance and identified novel therapeutic agents that may significantly improve the prognosis of relapsed HGSOC patients.

Thrombolytic and anticoagulant effects of a recombinant staphylokinase-hirudin fusion protein

A pure recombinant staphylokinase-hirudin fusion protein (SFH) was obtained by recombinant genetic engineering and purification techniques. The thrombolytic and anticoagulant activities of SFH were investigated using in vitro coagulation models and chromogenic assays. The results showed that intact SFH had targeted thrombolytic activity, and gained anticoagulant activity when cleaved by FXa. In addition, we investigated the pharmacodynamics of SFH in vivo using a variety of animal models, including a rat inferior vena cava thrombosis model, a rat coronary thrombosis model, a rabbit carotid artery thrombosis model and a canine coronary thrombosis model. We found that SFH had an obvious thrombolytic effect and could prevent and reduce re-embolization after thrombolysis and reduce the serious bleeding side effects caused by the combination of thrombolytic and anticoagulant drugs. The results suggest that SFH can be used for thrombolytic therapy in thromboembolic diseases.

Deep-learning-enabled Bayesian inference of fuel magnetization in magnetized liner inertial fusion

Fuel magnetization in magneto-inertial fusion (MIF) experiments improves charged burn product confinement, reducing requirements on fuel areal density and pressure to achieve self-heating. By elongating the path length of 1.01 MeV tritons produced in a pure deuterium fusion plasma, magnetization enhances the probability for deuterium–tritium reactions producing 11.8−17.1 MeV neutrons. Nuclear diagnostics thus enable a sensitive probe of magnetization. Characterization of magnetization, including uncertainty quantification, is crucial for understanding the physics governing target performance in MIF platforms, such as magnetized liner inertial fusion (MagLIF) experiments conducted at Sandia National Laboratories, Z-facility. We demonstrate a deep-learned surrogate of a physics-based model of nuclear measurements. A single model evaluation is reduced from O(10–100) CPU hours on a high-performance computing cluster down to O(10) ms on a laptop. This enables a Bayesian inference of magnetization, rigorously accounting for uncertainties from surrogate modeling and noisy nuclear measurements. The approach is validated by testing on synthetic data and comparing with a previous study. We analyze a series of MagLIF experiments systematically varying preheat, resulting in the first ever systematic experimental study of magnetic confinement properties of the fuel plasma as a function of fundamental inputs on any neutron-producing MIF platform. We demonstrate that magnetization decreases from BR∼0.5 to BR∼0.2 MG cm as laser preheat energy deposited increases from Epreheat∼460 J to Epreheat∼1.4 kJ. This trend is consistent with 2D LASNEX simulations showing Nernst advection of the magnetic field out of the hot fuel and diffusion into the target liner.

Complex ALK Fusions Are Associated With Better Prognosis in Advanced Non-Small Cell Lung Cancer.

BackgroundEchinoderm microtubule-associated protein-like 4 (EML4) is the canonical anaplastic lymphoma kinase (ALK) fusion partner in non-small cell lung cancer (NSCLC), and ALK-positive patients showed promising responses to ALK tyrosine kinase inhibitors (TKIs). However, studies that comprehensively investigate ALK TKI treatment in patients with different ALK fusion patterns are still lacking.MethodsNinety-eight ALK-positive patients with advanced NSCLC were retrospectively studied for their response to crizotinib and subsequent treatments. Comprehensive genomic profiling (CGP) was conducted to divide patients into different groups based on their ALK fusion patterns. Non-canonical ALK fusions were validated using RNA-sequencing.Results54.1% of patients had pure canonical EML4-ALK fusions, 19.4% carried only non-canonical ALK fusions, and 26.5% harbored complex ALK fusions with coexisting canonical and non-canonical ALK fusions. The objective response rate and median progression-free survival to crizotinib treatment tended to be better in the complex ALK fusion group. Notably, patients with complex ALK fusions had significantly improved overall survival after crizotinib treatment (p = 0.012), especially when compared with the pure canonical EML4-ALK fusion group (p = 0.010). The complex ALK fusion group also tended to respond better to next-generation ALK TKIs, which were used as later-line therapies. Most identified non-canonical ALK fusions were likely to be expressed in tumors, and some of them formed canonical EML4-ALK transcripts during mRNA maturation.ConclusionOur results suggest NSCLC patients with complex ALK fusions could potentially have better treatment outcomes to ALK TKIs therapy. Also, diagnosis using CGP is of great value to identify novel ALK fusions and predict prognosis.

Neutronics analysis of the stellarator-type fusion-fission hybrid reactor based on the CAD optimization method

The stellarator plasmas devices have some advantages in steady state operation with less magneto hydrodynamic activities, and the development of stellarator-type FFHR (Fusion-Fission Hybird Reactor) can provide viable energy in the foreseeable future with less requirements to the plasmas technology compared with the pure fusion system. However, the neutronics design of the stellarator-type FFHR has some challenges and difficulties, since the construction of helical structures with large number of high order spline surfaces are the extremely complicated process, and the physical parameters of the complex model have to be changed frequently in the primary design stage, which make the corresponding manual input simulation work into the time consuming and error prone tasks. In this context, the CAD optimization method has been used in converting the dense mesh oriented CAD structure to the low poly style, and the CAD-PSFO code has been employed for the modeling transformation process in Monte Carlo calculation. The thorium resource has been selected as the breeding material for the stellarator-type FFHR, and the polonium and natural abundance of uranium have been used as the seed fuel for the initial loading in order to get the high energy multiplication factor. The OMCB (OpenMC basedBurnupcode) has been introduced to study the burnup features, and stellarator-type FFHR has been designed as the multi-purposes facility that can keep tritium self-sufficiency and get the high breeding ratio with steady energy output.

A case report of severe degenerative lumbar scoliosis associated with windswept lower limb deformity

BackgroundThe windswept lower limb deformity describes valgus deformity in one leg with varus deformity in the other. It is mostly seen in young children with metabolic bone diseases (such as rickets) and may lead to leg length discrepancy (LLD) and Degenerative scoliosis (DS) in older age. To the best of our knowledge, there was no report of the spinal surgery in patient with severe DS associated with windswept deformity. The objective of this study is to report the unique case of a 60-year-old woman with severe degenerative scoliosis (DS) associated with windswept deformity caused by rickets who underwent a posterior correction and fusion surgery in spine.Case presentationThe patient was diagnosed as rickets windswept lower limb deformity for 50 years but never went through routine treatment. Then, she performed lumbar scoliosis for more than 20 years and suffered from severe back pain for 4 years. After overall clinical evaluation and radiographic measures, we performed a posterior surgical correction and fusion from T9-L5. With this surgery, the main thoracolumbar curve Cobb angle corrected from 72.5° to 21.0°, the coronal balance from 0 cm to 2.0 cm while the sagittal vertical axis (SVA) from 1.5 cm to − 1.0 cm. At 2 years postoperative follow-up, her back pain has almost completely relieved with a satisfied fixation and bone fusion showed on CT scans. However, a coronal imbalance was found with C7-CSVLdistance equal to 4.0 cm. This coronal imbalance was highly correlated to the untreated LLD and pelvic obliquity, and should be improved by standing posture or shoe lifts.ConclusionsFor such patient, the pure spinal correction and fusion surgery, in spite of lower limbs deformity, can achieve good relieve of back pain symptom, however may accompany by the complication of coronal imbalance due to the unimproved pelvic obliquity and LLD. However, longer follow-up is necessary to observe the long-term outcome of this patient’s postoperative coronal imbalance.

Fusion breeding for mid-century, sustainable, carbon free power

Fusion has often been billed as the ultimate 21st century sustainable energy source. However, not only is the pace of the program glacially slow, it seems to recede further and further into the future. One way to speed up the delivery of economical fusion could be to change the objective from pure fusion, that is the use of the 14 MeV fusion neutron's kinetic energy to boil water; to fusion breeding, that is the former, but also making use of the neutrons 'potential energy' to breed ten times its energy in the form of nuclear fuel to be burned in separate reactors. The requirements of a fusion breeder are greatly relaxed from the requirements for a pure fusion reactor. For instance, ITER, the large tokamak being built by an international consortium in France, could well be the basis of an economical fusion breeder, but would have to clear many more scientific and technical hurdles before it could become the basis for a pure fusion reactor; hurdles it may or may not be able to clear. Even if it clears them, ITER is unlikely to evolve into an economical pure fusion power supply this century. A fusion breeder as could be alternate approach to speed the delivery of economical of fusion power.

Collaborative Semantic Understanding and Mapping Framework for Autonomous Systems

Performing collaborative semantic mapping is a critical challenge for cooperative robots to enhance their comprehensive contextual understanding of the surroundings. This article bridges the gap between the advances in collaborative geometry mapping that relies on pure geometry information fusion, and single robot semantic mapping that focuses on integrating continuous raw sensor data. In this article, a novel hierarchical collaborative probabilistic semantic mapping framework is proposed, where the problem is formulated in a distributed setting. The key novelty of this work is the modeling of the hierarchical semantic map fusion framework and its mathematical derivation of its probability decomposition. At the single robot level, the semantic point cloud is obtained by combining information from heterogeneous sensors and used to generate local semantic maps. At the collaborative robots level, local maps are shared among robots for global semantic map fusion. Since the voxel correspondence is unknown between local maps, an expectation-maximization approach is proposed to estimate the hidden data association. Then, Bayesian rule is applied to perform semantic and occupancy probability update. Experimental results on the unmanned aerial vehicle and the unmanned ground vehicle platforms show the high quality of global semantic maps, demonstrating the accuracy and utility in practical missions.

Study on the fusion reactor performance with different materials and nuclear waste actinides

In this study, both pure fusion blanket and fusion-fission (hybrid) reactor blanket performance were investigated and discussed separately in two phases. In the first phase, a Monte Carlo radiation damage analysis has been performed for stainless steel (SS304, SS316, and oxide dispersion strengthened (ODS)), molybdenum, vanadium, and tungsten as the first wall (FW) materials, in combination with selected tritium breeders. The main technical parameters for fusion reactors, such as tritium breeding ratio, fusion energy multiplication factor (M), displacement per atom (DPA), and gas production (He, H) have been evaluated. All numerical calculations have been carried out in spherical geometry with MCNP6 code package using continuous energy cross-sections from the ENDF/B-VIII.0 library, except DPA calculations. Instead of the ENDF/B-VIII.0 library, the 30-group CLAW-IV library was employed for DPA calculations. Structural material selection for the FW respect to radiation damage limits and reactor performance for energy production and tritium has been concluded. Conventional thermal reactors, such as light water reactors andCanada Deuterium Uranium (CANDU) reactors are producing substantial quantities of transuranic elements, which represent serious nuisance and permanent hazard potential. On the other hand, they become fissionable material under high energetic fusion neutron irradiation and multiply the fusion energy. In the second phase, the investigations are extended to the incineration of minor actinides (MA) in the fusion-fission (hybrid) mode. The transmutation history of MA nuclear waste is included. MA are added into the first zone of the coolant in TRi-structural ISOtropic particle TRISO particles with a volume fraction of 6%. The transformation scenario for all MA by SS 304 steel FW is practically the same as with the ODS FW.

Neutronics conceptual research on a hybrid blanket of china fusion engineering test reactor

• A hybrid CFETR blanket using natural uranium U-10Zr alloy and water is proposed. • Multi-layer alternate arrangement of fission zone and tritium breeding zone is used. • 3D detailed neutronics model is built for JMCT by CMGC. • MCNP results are crosschecked by JMCT. • TBR and M are 1.26 and 3.18 respectively. The engineering concept research of China Fusion Engineering Test Reactor (CFETR) is underway. In order to achieve tritium self-sufficiency and lower tritium startup inventory, a fusion fission hybrid blanket scheme is proposed in this paper as a backup for the traditional pure fusion blanket concepts. In the hybrid blanket design, natural uranium is used as fuel, light water as coolant and Li 4 SiO 4 as tritium breeder. MCORGS, a burnup code coupled by MCNP and ORIGENS, is used in burnup calculation. JMCT, a Joint Monte Carlo Transportation code developed by Institute of Applied Physics and Computational Mathematics, is used to crosscheck the MCNP results. One dimensional design and optimization is firstly made to propose a multi-layer alternate arrangement of fission zone and tritium breeding zone so as to maximum Tritium Breeding Ratio (TBR) and a moderate energy Multiplication (M). A 3D neutronics model of CFETR is converted from MCNP benchmark files to a GDML file which is used in JMCT. At the beginning of the core, TBR 3D is 1.26 which is bigger than the max achievable TBR for pure fusion blanket (around 1.15), M is 3.18 which means the tritium startup inventory will be 3 times lower than the pure fusion blanket in case of a fixed blanket thermal power. After 12 years burnup with 200 MW fusion power, TBR and M will be 1.28 and 4.05 respectively. The hybrid system is in an ultra deep subcritical state, the effective multiplication constant varies from 0.161 to 0.227. If the natural uranium in fission zone is replaced by spent fuel or LEU, more higher TBR and M will be obtained.

Distribution Patterns of Valvular and Vascular Complications in Bicuspid Aortic Valve.

For its high occurrence and elevated risks for aortic valve dysfunction and vascular complications, bicuspid aortic valve (BAV) represents a great health challenge. However, the prevalence and clinical features of BAV in the Chinese population are inadequately illustrated.From January 2011 to December 2015, 3,673 BAV patients with 69.1% male predominance were identified among 325,910 recipients of transthoracic echocardiography in our institution, demonstrating 58.4% overt aortic valve dysfunction, 52.5% ascending aortic dilatation, and 19.2% aortic root dilatation. The prevalence of pure aortic stenosis and mixed aortic valve dysfunction rose strikingly with age (both P < 0.0001), while pure aortic regurgitation showed significant decrease with age (P < 0.0001). Males showed elevated prevalence of pure aortic regurgitation (OR 3.16, 95% CI 2.55-3.91, P < 0.0001) and mixed aortic valve dysfunction than females (OR 1.63, 95% CI 1.23-2.17, P = 0.0008), but lower prevalence of pure aortic stenosis (OR 0.51, 95% CI 0.43-0.60, P < 0.0001). Aortic root dilatation was associated with male gender (OR 5.02, 95% CI 3.74-6.74, P < 0.0001), pure aortic regurgitation (OR 2.61, 95% CI 2.15-3.17, P < 0.0001), and right-left (RL) cusp fusion type (OR 1.98, 95% CI 1.64-2.40, P < 0.0001). Ascending aortic dilatation was associated with an elder age (OR 1.04, 95% CI 1.04-1.05, P < 0.0001), pure aortic stenosis (OR 1.37, 95% CI 1.16-1.61 P = 0.0002), and mixed aortic valve dysfunction (OR 2.51, 95% CI 1.89-3.33, P < 0.0001).Bicuspid aortic stenosis and ascending aortic dilatation demonstrate a similar pattern of age escalation, while aortic regurgitation is more prevalent in younger BAV patients. Aortic root dilatation intervenes closely with a unique phenotypic subgroup of male BAV patients with pure aortic regurgitation and RL fusion type.

Asymmetric Rab activation of vacuolar HOPS to catalyze SNARE complex assembly.

Intracellular membrane fusion requires Rab-family GTPases, their effector tethers, soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins, and SNARE chaperones of the Sec1/Munc18 (SM), Sec17/α-SNAP, and Sec18/NSF families. We have developed an assay using fluorescence resonance energy transfer to measure SNARE complex formation in real time. We now show that yeast vacuolar SNAREs assemble spontaneously into RQaQbQc complexes when the R- and Qa-SNAREs are concentrated in the same micelles or in cis on the same membrane. When SNAREs are free in solution or are tethered to distinct membranes, assembly requires catalysis by HOPS, the vacuolar SM and tethering complex. The Rab Ypt7 and vacuole lipids together allosterically activate the bound HOPS for catalyzing SNARE assembly, even if none of the SNAREs are membrane bound. HOPS-dependent fusion between proteoliposomes bearing R- or Qa-SNAREs shows a strict requirement for Ypt7 on the R-SNARE proteoliposomes but not on the Qa-SNARE proteoliposomes. This asymmetry is reflected in the strikingly different capacity of Ypt7 in cis to either the R- or Qa-SNARE to stimulate SNARE complex assembly. Membrane-bound Ypt7 activates HOPS to catalyze 4-SNARE complex assembly when it is on the same membrane as the R-SNARE but not the Qa-SNARE, thus explaining the asymmetric need for Ypt7 for fusion.

Cry Protein Crystal-Immobilized Metallothioneins for Bioremediation of Heavy Metals from Water

Cry proteins have been the subject of intense research due to their ability to form crystals naturally in Bacillus thuringiensis (Bt). In this research we developed a new strategy that allows for the removal of cadmium and chromium from wastewater by using one Cry protein, Cry3Aa, as a framework to immobilize tandem repeats of the cyanobacterial metallothionein SmtA from Synechococcus elongatus (strain PCC 7942). SmtA is a low molecular weight cysteine-rich protein known to bind heavy metals. A series of Cry3Aa-SmtA constructs were produced by the fusion of one, three, or six tandem repeats of SmtA to Cry3Aa. Overexpression of these constructs in Bt resulted in the production of pure Cry3Aa-SmtA fusion crystals that exhibited similar size, crystallinity, and morphology to that of native Cry3Aa protein crystals. All three Cry3Aa-SmtA constructs exhibited efficient binding to cadmium and chromium, with the binding capacity correlated with increasing SmtA copy number. These results suggest the potential use of Cry3Aa-SmtA crystals as a novel biodegradable and cost-effective approach to the removal of toxic heavy metals from the environment.