Continuous cell lysis in microfluidics through acoustic and optoelectronic tweezers

A versatile platform for efficient cell lysis using a combination of acoustic and electric fields in a microchannel is presented. Cell membrane disruption is triggered by electric fields inducing electroporation and then lysis. The principle of optoelectronic tweezers (OET) is applied to control the electric field strength and a surface acoustic wave transducer is attached to an OET chip to implement acoustic tweezing (AT). The system is characterized in terms of spatial control of electric fields, single cell precision and lysi

Presence of arthralgia exacerbates decreased quality of life in hidradenitis suppurativa patients

Hidradenitis suppurativa is characterized by chronic follicular occlusion that presents with recurrent nodules, inflamed abscesses, and scarring. Research has shown that these patients have a decreased quality of life. In addition to its psychosocial effects, hidradenitis suppurativa has recently been associated with joint pathology. In this study, we distributed a survey consisting of the Short Form 12 Health Survey, used for assessing health outcomes, along with additional questions about joint pain to an online hidradenitis suppurativa support group in order to understand the effect of comorbid arthralgia on quality of life in this disease. The respondents in this study had significantly reduced physical health composite scores-12 (PCS-12), (35.8 versus 50, P<0.001) and mental health composite scores-12 (MCS-12), (33.7 versus 50, P<0.001) scores compared to the general population. Additionally, patients reporting severe arthralgia had significantly lower PCS-12 (32.3 versus 36.5; P<0.05) and MCS-12 (33.3 versus 40.5; P<0.001) scores compared to those with mild arthralgia. Despite the effect of comorbid arthralgia on quality of life, only 11% reported having been asked about joint pain by their dermatologist. Routine screening questions concerning associated arthralgia and diminished quality of life may be helpful during clinician assessment and treatment of hidradenitis suppurativa patients

A multi-resolution model to capture both global fluctuations of an enzyme and molecular recognition in the ligand-binding site

In multi-resolution simulations, different system components are simultaneously modelled at different levels of resolution, these being smoothly coupled together. In the case of enzyme systems, computationally expensive atomistic detail is needed in the active site to capture the chemistry of substrate binding. Global properties of the rest of the protein also play an essential role, determining the structure and fluctuations of the binding site; however, these can be modelled on a coarser level. Similarly, in the most computationally efficient scheme only the solvent hydrating the active site requires atomistic detail. We present a methodology to couple atomistic and coarse-grained protein models, while solvating the atomistic part of the protein in atomistic water. This allows a free choice of which protein and solvent degrees of freedom to include atomistically, without loss of accuracy in the atomistic description. This multi-resolution methodology can successfully model stable ligand binding, and we further confirm its validity via an exploration of system properties relevant to enzymatic function. In addition to a computational speedup, such an approach can allow the identification of the essential degrees of freedom playing a role in a given process, potentially yielding new insights into biomolecular function

Irreversible processes and the accelerated-decelerated phases of the Universe

A model for the Universe is proposed where it is considered as a mixture of scalar and matter fields. The particle production is due to an irreversible transfer of energy from the gravitational field to the matter field and represented by a non-equilibrium pressure. This model can simulate three distinct periods of the Universe: (a) an accelerated epoch where the energy density of the scalar field prevails over the matter field, (b) a past decelerated period where the energy density of the matter field becomes more predominant than the scalar energy density, and (c) a present acceleration phase where the scalar energy density overcomes the energy density of the matter field.Comment: 6 pages, 2 figures, to be published in Brazilian Journal of Physic

Advantages and challenges in coupling an ideal gas to atomistic models in adaptive resolution simulations

In adaptive resolution simulations, molecular fluids are modeled employing different levels of resolution in different subregions of the system. When traveling from one region to the other, particles change their resolution on the fly. One of the main advantages of such approaches is the computational efficiency gained in the coarse-grained region. In this respect the best coarse-grained system to employ in the low resolution region would be the ideal gas, making intermolecular force calculations in the coarse-grained subdomain redundant. In this case, however, a smooth coupling is challenging due to the high energetic imbalance between typical liquids and a system of non-interacting particles. In the present work, we investigate this approach, using as a test case the most biologically relevant fluid, water. We demonstrate that a successful coupling of water to the ideal gas can be achieved with current adaptive resolution methods, and discuss the issues that remain to be addressed