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- Beal, Jacob, et al.
(författare)
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Robust estimation of bacterial cell count from optical density
- 2020
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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- Chhabra, Saurabh, et al.
(författare)
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Myeloablative vs reduced-intensity conditioning allogeneic hematopoietic cell transplantation for chronic myeloid leukemia
- 2018
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Ingår i: Blood Advances. - : American Society of Hematology. - 2473-9529 .- 2473-9537. ; 2:21, s. 2922-2936
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Tidskriftsartikel (refereegranskat)abstract
- Allogeneic hematopoietic cell transplantation (allo-HCT) is a potentially curative treatment of chronic myeloid leukemia (CML). Optimal conditioning intensity for allo-HCT for CML in the era of tyrosine kinase inhibitors (TKIs) is unknown. Using the Center for International Blood and Marrow Transplant Research database, we sought to determine whether reduced-intensity/nonmyeloablative conditioning (RIC) allo-HCT and myeloablative conditioning (MAC) result in similar outcomes in CML patients. We evaluated 1395 CML allo-HCT recipients between the ages of 18 and 60 years. The disease status at transplant was divided into the following categories: chronic phase 1, chronic phase 2 or greater, and accelerated phase. Patients in blast phase at transplant and alternative donor transplants were excluded. The primary outcome was overall survival (OS) after allo-HCT. MAC (n = 1204) and RIC allo-HCT recipients (n = 191) from 2007 to 2014 were included. Patient, disease, and transplantation characteristics were similar, with a few exceptions. Multivariable analysis showed no significant difference in OS between MAC and RIC groups. In addition, leukemia-free survival and nonrelapse mortality did not differ significantly between the 2 groups. Compared with MAC, the RIC group had a higher risk of early relapse after allo-HCT (hazard ratio [HR], 1.85; P = .001). The cumulative incidence of chronic graft-versus-host disease (cGVHD) was lower with RIC than with MAC (HR, 0.77; P = .02). RIC provides similar survival and lower cGVHD compared with MAC and therefore may be a reasonable alternative to MAC for CML patients in the TKI era.
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3. |
- Dhake, Kushal, et al.
(författare)
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Effect of Pretreatment and Temperature on Drying Characteristics and Quality of Green Banana Peel
- 2023
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Ingår i: AgriEngineering. - 2624-7402.
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Tidskriftsartikel (refereegranskat)abstract
- In banana cultivation, a considerable amount of the production is wasted every year because of various constraints present in the post-harvest management chain. Converting green banana pulp and peels into flour could help to reduce losses and enable the food sector to keep the product for an entire year or more. In order to use green banana fruit and peel flour in the food industry as a raw ingredient such as in bakery and confectionery items—namely biscuits, cookies, noodles, nutritious powder, etc.—it is essential to standardize the process for the production of the flour. As a result, the purpose of this study was to investigate the influence of pretreatment and temperature on the drying capabilities and quality of dried green banana peel. The green banana peel pieces were pretreated with 0.5 and 1.0% KMS (potassium metabisulfite), and untreated samples were taken as control, and dried at 40°, 50°, and 60 °C in a tray dryer. To reduce the initial moisture content of 90–91.58% (wb) to 6.25–9.73% (wb), a drying time of 510–360 min was required in all treatments. The moisture diffusivity (Deff) increased with temperature, i.e., Deff increased from 5.069–6.659 × 10−8, 6.013–7.653 × 10−8, and 4.969–6.510 × 10−8 m2/s for the control sample, 0.5% KMS, and 1.0% KMS, respectively. The Page model was determined to be the best suited for the drying data with the greatest R2 and the least χ2 and RSME values in comparison with the other two models. When 0.5% KMS-pretreated materials were dried at 60 °C, the water activity and drying time were minimal. Hue angle, chroma, and rehydration ratio were satisfactory and within the acceptable limits for 0.5% KMS-pretreated dried banana peel at 60 °C.
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5. |
- Jain, Sandeep K., et al.
(författare)
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Boundaries determine the formation energies of lattice defects in two-dimensional buckled materials
- 2016
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Ingår i: PHYSICAL REVIEW B. - : American Physical Society. - 2469-9950. ; 94:2
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Tidskriftsartikel (refereegranskat)abstract
- Lattice defects are inevitably present in two-dimensional materials, with direct implications on their physical and chemical properties. We show that the formation energy of a lattice defect in buckled two-dimensional crystals is not uniquely defined as it takes different values for different boundary conditions even in the thermodynamic limit, as opposed to their perfectly planar counterparts. Also, the approach to the thermodynamic limit follows a different scaling: inversely proportional to the logarithm of the system size for buckled materials, rather than the usual power-law approach. In graphene samples of similar to 1000 atoms, different boundary conditions can cause differences exceeding 10 eV. Besides presenting numerical evidence in simulations, we show that the universal features in this behavior can be understood with simple bead-spring models. Fundamentally, our findings imply that it is necessary to specify the boundary conditions for the energy of the lattice defects in the buckled two-dimensional crystals to be uniquely defined, and this may explain the lack of agreement in the reported values of formation energies in graphene. We argue that boundary conditions may also have an impact on other physical observables such as the melting temperature.
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6. |
- Jain, Sandeep K., et al.
(författare)
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Probing the shape of a graphene nanobubble
- 2017
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Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 19:11, s. 7465-7470
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Tidskriftsartikel (refereegranskat)abstract
- Gas molecules trapped between graphene and various substrates in the form of bubbles are observed experimentally. The study of these bubbles is useful in determining the elastic and mechanical properties of graphene and adhesion energy between graphene and the substrate, and manipulating the electronic properties via strain engineering. In our numerical simulations, we use a simple description of the elastic potential and adhesion energy to show that for small gas bubbles (similar to 10 nm) the van derWaals pressure is in the order of 1 GPa. These bubbles show universal shape behavior irrespective of their size, as observed in recent experiments. With our results, the shape and volume of the trapped gas can be determined via the vibrational density of states (VDOS) using experimental techniques such as inelastic electron tunneling and inelastic neutron scattering. The elastic energy distribution in the graphene layer which traps the nanobubble is homogeneous apart from its edge, but the strain depends on the bubble size; thus variation in bubble size allows control of the electronic and optical properties.
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7. |
- Jain, Sandeep K., et al.
(författare)
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Structure of twisted and buckled bilayer graphene
- 2017
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Ingår i: Current Opinion in Chemical Engineering. - : Institute of Physics Publishing (IOPP). - 2211-3398. ; 4:1
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Tidskriftsartikel (refereegranskat)abstract
- We study the atomic structure of twisted bilayer graphene, with very small mismatch angles (theta similar to 0.28(0)), a topic of intense recent interest. We use simulations, in which we combine a recently presented semi-empirical potential for single-layer graphene, with a new term for out-of-plane deformations, (Jain et al. 2015 J. Phys. Chem. C119 9646) and an often-used interlayer potential (Kolmogorov et al 2005 Phys. Rev. B 71 235415). This combination of potentials is computationally cheap but accurate and precise at the same time, allowing us to study very large samples, which is necessary to reach very small mismatch angles in periodic samples. By performing large scale atomistic simulations, we show that the vortices appearing in the Moire pattern in the twisted bilayer graphene samples converge to a constant size in the thermodynamic limit. Furthermore, the well known sinusoidal behavior of energy no longer persists once the misorientation angle becomes very small (theta < 1(0)). We also show that there is a significant buckling after the relaxation in the samples, with the buckling height proportional to the system size. These structural properties have direct consequences on the electronic and optical properties of bilayer graphene.
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8. |
- Paschoal Jr., Waldomiro, 1977-, et al.
(författare)
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Magnetoresistance in Mn ion-implanted GaAs:Zn nanowires
- 2014
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Ingår i: Applied Physics Letters. - New York : American Institute of Physics (AIP). - 0003-6951 .- 1077-3118. ; 104:15
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Tidskriftsartikel (refereegranskat)abstract
- We have investigated the magnetoresistance (MR) in a series of Zn doped (p-type) GaAs nanowires implanted with different Mn concentrations. The nanowires with the lowest Mn concentration (~0.0001%) exhibit a low resistance of a few kΩ at 300K and a 4% positive MR at 1.6K, which can be well described by invoking a spin-split subband model. In contrast, nanowires with the highest Mn concentration (4%) display a large resistance of several MΩ at 300K and a large negative MR of 85% at 1.6K. The large negative MR is interpreted in terms of spin-dependent hopping in a complex magnetic nanowire landscape of magnetic polarons, separated by intermediate regions of Mn impurity spins. Sweeping the magnetic field back and forth for the 4% sample reveals a hysteresis that indicates the presence of a weak ferromagnetic phase. We propose co-doping with Zn to be a promising way to reach the goal of realizing ferromagnetic Ga1-xMnxAs nanowires for future nanospintronics. © 2014 AIP Publishing LLC.
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