scholarly journals Structure-Properties Correlation of Cross-Linked Penicillin G Acylase Crystals

Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 451
Author(s):  
Marta Kubiak ◽  
Janine Mayer ◽  
Ingo Kampen ◽  
Carsten Schilde ◽  
Rebekka Biedendieck
Keyword(s):  
Mechanical Stability ◽  
Structural Characteristics ◽  
Penicillin G ◽  
Bacillus Species ◽  
Diffusion Limitations ◽  
Small Water ◽  
Long Term Stability ◽  
Atomic Force ◽  
First Time

In biocatalytic processes, the use of free enzymes is often limited due to the lack of long-term stability and reusability. To counteract this, enzymes can be crystallized and then immobilized, generating cross-linked enzyme crystals (CLECs). As mechanical stability and activity of CLECs are crucial, different penicillin G acylases (PGAs) from Gram-positive organisms have proven to be promising candidates for industrial production of new semisynthetic antibiotics, which can be crystallized and cross-linked to characterize the resulting CLECs regarding their mechanical and catalytic properties. The greatest hardness and Young’s modulus determined by indentation with an atomic force microscope were observed for CLECs of Bacillus species FJAT-PGA CLECs (26 MPa/1450 MPa), followed by BmPGA (Priestia megaterium PGA, 23 MPa/1170 MPa) and BtPGA CLECs (Bacillus thermotolerans PGA, 11 MPa/614 MPa). In addition, FJAT- and BtPGA CLECs showed up to 20-fold higher volumetric activities compared to BmPGA CLECs. Correlation to structural characteristics indicated that a high solvent content and low number of cross-linking residues might lead to reduced stability. Furthermore, activity seems to be restricted by small water channels due to severe diffusion limitations. To the best of our knowledge, we show for the first time in this study that the entire process chain for the characterization of diverse industrially relevant enzymes can be performed at the microliter scale to discover the most important relationships and limitations.

scholarly journals Scribing Method for Carbon Perovskite Solar Modules

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1589 ◽  
Author(s):  
Simone M. P. Meroni ◽  
Katherine E. A. Hooper ◽  
Tom Dunlop ◽  
Jenny A. Baker ◽  
David Worsley ◽  
...  
Keyword(s):  
Screen Printing ◽  
Fill Factor ◽  
Transparent Electrode ◽  
Perovskite Solar Cell ◽  
Metal Contacts ◽  
Good Efficiency ◽  
Long Term Stability ◽  
First Time

The fully printable carbon triple-mesoscopic perovskite solar cell (C-PSC) has already demonstrated good efficiency and long-term stability, opening the possibility of lab-to-fab transition. Modules based on C-PSC architecture have been reported and, at present, are achieved through the accurate registration of each of the patterned layers using screen-printing. Modules based on this approach were reported with geometric fill factor (g-FF) as high as 70%. Another approach to create the interconnects, the so-called scribing method, was reported to achieve more than 90% g-FF for architectures based on evaporated metal contacts, i.e., without a carbon counter electrode. Here, for the first time, we adopt the scribing method to selectively remove materials within a C-PSC. This approach allowed a deep and selective scribe to open an aperture from the transparent electrode through all the layers, including the blocking layer, enabling a direct contact between the electrodes in the interconnects. In this work, a systematic study of the interconnection area between cells is discussed, showing the key role of the FTO/carbon contact. Furthermore, a module on 10 × 10 cm2 substrate with the optimised design showing efficiency over 10% is also demonstrated.

scholarly journals Targeted Release of Probiotics from Enteric Microparticulated Formulations

Polymers ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1668 ◽  
Author(s):  
Cristina Yus ◽  
Ruben Gracia ◽  
Ane Larrea ◽  
Vanesa Andreu ◽  
Silvia Irusta ◽  
...  
Keyword(s):  
Targeted Delivery ◽  
Target Tissue ◽  
Release Formulation ◽  
Long Term Stability ◽  
Pharmaceutical Ingredients ◽  
Efficient Delivery ◽  
Synthesized Materials ◽  
First Time ◽  
Targeted Release

The development of advanced probiotic delivery systems, which preserve bacteria from degradation of the gastrointestinal tract and achieve a targeted release mediated by pH-independent swelling, is of great interest to improve the efficient delivery of probiotic bacteria to the target tissue. Gram-positive and Gram-negative bacteria models (Lactobacillus acidophilus (Moro) Hansen and Mocquot (ATCC® 4356™) and Escherichia coli S17, respectively) have been successfully encapsulated for the first time in pH-independent microparticulate polymethacrylates (i.e., Eudraguard biotic) used for the targeted delivery of nutraceuticals to the colon. These bacteria have also been encapsulated within the mucoadhesive polymethacrylate Eudragit RS 100 widely used as targeted release formulation for active pharmaceutical ingredients. The enteric microparticles remained unaltered under simulated gastric conditions and released the contained viable microbial cargo under simulated intestinal conditions. Buoyancies of 90.2% and 57.3% for Eudragit and Eudraguard microparticles, respectively, and long-term stability (5 months) for the encapsulated microorganisms were found. Cytotoxicity of the microparticles formulated with both polymers was evaluated (0.5–20 mg/mL) on Caco-2 cells, showing high cytocompatibility. These results underline the suitability of the synthesized materials for the successful delivery of probiotic formulations to the target organ, highlighting for the first time the potential use of Eudraguard biotic as an effective enteric coating for the targeted delivery of probiotics.

Enhancement of efficiency and long-term stability in graphene/Si-quantum-dot heterojunction photodetectors by employing bis(trifluoromethanesulfonyl)-amide as a dopant for graphene

2017 ◽  
Vol 5 (48) ◽  
pp. 12737-12743 ◽  
Author(s):  
Dong Hee Shin ◽  
Chan Wook Jang ◽  
Ju Hwan Kim ◽  
Jong Min Kim ◽  
Ha Seung Lee ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Term Stability ◽  
Long Term Stability ◽  
Si Quantum Dot ◽  
First Time ◽  
Si Quantum Dots

Bis(trifluoromethanesulfonyl)-amide (TFSA) is for the first time employed as a dopant for graphene for graphene/Si-quantum-dots-based photodetectors.

Penicillin G Acylase-Fatty Lipid Biocomposite Films Show Excellent Catalytic Activity and Long Term Stability/Reusability

2002 ◽  
Vol 18 (3) ◽  
pp. 483-488 ◽  
Author(s):  
S. Phadtare ◽  
P. Parekh ◽  
A. Gole ◽  
M. Patil ◽  
A. Pundle ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Penicillin G Acylase ◽  
Penicillin G ◽  
Term Stability ◽  
Long Term Stability ◽  
Biocomposite Films

scholarly journals Optical Axis Perturbation Analysis for the Unit-Magnification Multipass System

2017 ◽  
Vol 2017 ◽  
pp. 1-11
Author(s):  
Yin Guo ◽  
Liqun Sun ◽  
Zheng Yang
Keyword(s):  
Optical Axis ◽  
Optical Element ◽  
Transfer Model ◽  
Tolerance Range ◽  
Long Term Stability ◽  
Generalized Sensitivity ◽  
Sensitivity Factors ◽  
Element Transfer ◽  
First Time

The optical axis sensitivity for the unit-magnification multipass system (UMS) is presented by using a general misaligned optical element transfer model. The generalized sensitivity factors SD1, SD2, ST1, and ST2 influenced by both the axial and angular misalignments of the objective mirrors in a UMS have been calculated for the first time. The Bernstein-Herzberg White Cells are used as an example, and their alignment tolerance and stability properties are found when their configurations change. The analysis in this paper is helpful for the design of other kinds of multipass gas cells (MGC) with high robustness and avoiding the violent vibration of the optical axis when the misalignment of each mirror is controlled within the tolerance range. Among the five possible perturbations sources, the misaligned factors δix,δiy,θix have more effects on the output beam’s position and the perturbed sources from δix,θix and δiy,θiy have more impacts on the output beam’s slope referred to as x-axis and y-axis, respectively. Higher reflection times mean smaller tolerance range. The results benefit the multipass cell design and the precise alignment of the mirrors within the cell with the purpose of long-term stability in measurements.

scholarly journals Stability Assessment of Four Chimeric Proteins for Human Chagas Disease Immunodiagnosis

Biosensors ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 289
Author(s):  
Paola Alejandra Fiorani Celedon ◽  
Leonardo Maia Leony ◽  
Ueriton Dias Oliveira ◽  
Natália Erdens Maron Freitas ◽  
Ângelo Antônio Oliveira Silva ◽  
...  
Keyword(s):  
Chagas Disease ◽  
Structural Integrity ◽  
Structural Characteristics ◽  
Control Group ◽  
Stability Tests ◽  
Adverse Conditions ◽  
Term Stability ◽  
Long Term Stability

The performance of an immunoassay relies on antigen-antibody interaction; hence, antigen chemical stability and structural integrity are paramount for an efficient assay. We conducted a functional, thermostability and long-term stability analysis of different chimeric antigens (IBMP), in order to assess effects of adverse conditions on four antigens employed in ELISA to diagnose Chagas disease. ELISA-based immunoassays have served as a model for biosensors development, as both assess molecular interactions. To evaluate thermostability, samples were heated and cooled to verify heat-induced denaturation reversibility. In relation to storage stability, the antigens were analyzed at 25 °C at different moments. Long-term stability tests were performed using eight sets of microplates sensitized. Antigens were structurally analyzed through circular dichroism (CD), dynamic light scattering, SDS-PAGE, and functionally evaluated by ELISA. Data suggest that IBMP antigens are stable, over adverse conditions and for over a year. Daily analysis revealed minor changes in the molecular structure. Functionally, IBMP-8.2 and IBMP-8.3 antigens showed reactivity towards anti-T. cruzi antibodies, even after 72 h at 25 °C. Long-term stability tests showed that all antigens were comparable to the control group and all antigens demonstrated stability for one year. Data suggest that the antigens maintained their function and structural characteristics even in adverse conditions, making them a sturdy and reliable candidate to be employed in future in vitro diagnostic tests applicable to different models of POC devices, such as modern biosensors in development.

Long-term stability and tree-ring oxidation of WSe2 using phase-contrast AFM

Nanoscale ◽  
2021 ◽  
Author(s):  
Lene Gammelgaard ◽  
Patrick Rebsdorf Whelan ◽  
Timothy J Booth ◽  
Peter Bøggild
Keyword(s):  
Atomic Force Microscopy ◽  
Tree Ring ◽  
Phase Contrast ◽  
Ambient Conditions ◽  
Force Microscopy ◽  
Long Term Stability ◽  
Atomic Force ◽  
Term Evolution ◽  
Ring Oxidation

In this work, we use atomic force microscopy (AFM) to investigate the long-term evolution of oxidative defects of tungsten diselenide (WSe2) in ambient conditions over a period of 75 months,...

Towards the Optimal Crown-to-Implant Ratio in Dental Implants

2017 ◽  
Author(s):  
T. J. Sego ◽  
Yung-Ting Hsu ◽  
Tien-Min Gabriel Chu ◽  
Andres Tovar
Keyword(s):  
Dental Implants ◽  
Strain Distribution ◽  
Mechanical Stability ◽  
Element Model ◽  
Equivalent Strain ◽  
Skeletal Tissue ◽  
Term Stability ◽  
Long Term Stability ◽  
Clinical Scenarios

Short dental implants are commonly recommended to be implemented with small crown-to-implant (C/I) ratios due to their mechanical stability — decreasing C/I ratios cause less deformation in skeletal tissue under occlusal force. However, the long-term stability of short implants with high C/I ratios remains a controversial issue due to biomechanical complications. This study evaluates the strain distribution and functional implications in an implant-supported crown with various C/I ratios using a high-fidelity, nonlinear finite-element model. Several clinical scenarios are simulated by loading implants with various implant lengths (IL) and crown heights (CH). Strain distribution and maximum equivalent strain are analyzed to evaluate the effects and significance of CH, IL, and the C/I ratio. The study shows underloading for certain implant configurations with high C/I ratio. Increasing IL and decreasing C/I in moderation demonstrates a positive effect in long-term stability.

scholarly journals Extinction-resistant attention to long-term conditioned threat is indexed by selective visuocortical alpha suppression in humans

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Christian Panitz ◽  
Andreas Keil ◽  
Erik M. Mueller
Keyword(s):  
Visual Attention ◽  
Time Windows ◽  
Alpha Power ◽  
Physiological Measures ◽  
Time Frequency ◽  
Long Term Stability ◽  
Electrophysiological Studies ◽  
First Time

Abstract Previous electrophysiological studies in humans have shown rapid modulations of visual attention after conditioned threat vs. safety cues (<500 ms post-stimulus), but it is unknown whether this attentional prioritization is sustained throughout later time windows and whether it is robust to extinction. To investigate sustained visual attention, we assessed visuocortical alpha suppression in response to conditioned and extinguished threat. We reanalysed data from N = 87 male participants that had shown successful long-term threat conditioning and extinction in self reports and physiological measures in a two-day conditioning paradigm. The current EEG time-frequency analyses on recall test data on Day 2 revealed that previously threat-conditioned vs. safety cues evoked stronger occipital alpha power suppression from 600 to 1200 ms. Notably, this suppression was resistant to previous extinction. The present study showed for the first time that threat conditioning enhances sustained modulation of visuocortical attention to threat in the long term. Long-term stability and extinction resistance of alpha suppression suggest a crucial role of visuocortical attention mechanisms in the maintenance of learned fears.

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