Alanine is a transfer standard dosimeter using in gamma-ray and electron beam calibration. One of the important factor affecting its dosimetric response is amount of humidity which can deviate the dosimetry expert from the exact value of absorbed doses. Ab initio molecular dynamics calculations were performed to determine the environmental effects on the EPR parameters of L-α-Alanine radicals in acidic and alkaline solutions. Similar to the closed-shell amino acid molecule alanine, the zwitterionic form of alanine radical is the stable form in the gas phase while the non-zwitterionic neutral alanine radical is not a stable structure. Geometric and EPR parameters of radicals in both gas and solution phases are found to be dependent on hydrogen bonding of water molecules with the polar groups and by dynamic solvation. Calculations on the optimized free radicals in the gas phase revealed that for neutral radical, hydrogen bonding to water molecules drives a decrease in the magnitudes of g-tensor components gxx and gyy without affecting neither gzz component nor the HFCCs. For the transfer from the gas to solution phase of the alanine radical anion is accompanied with an increase in the spin density on the carboxylic group’s oxygen atoms. However, for the neutral radical, this transfer from gas to solution phase is accompanied with the decrease in the spin density on oxygen atoms. Calculated isotropic HFCCs and g-tensor of all radicals were in good agreement with their experimental counterparts in both acidic and alkaline solutions, which enhances the confidence in our calculated results.
Background: Lack of time has consistently been reported as a major barrier to effective research evidence-uptake into clinical practice. There has been no research to our knowledge that explores time as a barrier within the Transtheoretical model of Stages of Change (SoC), to better understand the processes of physiotherapists’ uptake of clinical practice guidelines (CPG). This paper explores the concept of lack of time as a barrier for CPG uptake for physiotherapists at different SoC. Methods: A 6-step process is presented to determine the best-fit SoC for 31 physiotherapy interviewees. This process used an amalgamation of interview findings and socio-demographic data, which was layered onto the SoC and previously identified time-barriers to CPG uptake (few staff; high workload; access to CPGs; evidence-based practice as priority in clinical practice; “time is money” attitude; and knowledge on the use of CPGs). Results: The analysis process highlighted the complexities of assigning individuals to a SoC. A model of time management for better CPG uptake is proposed which is a novel approach to assist evidence implementalists and clinicians alike to determine how to progress through the SoC and barriers to improve CPG uptake. Conclusions: To the authors’ knowledge, this is the first attempt at exploring the construct of (lack of) time for CPG-uptake in relation to the physiotherapists’ readiness to behaviour change. This study shows that ‘lack of time’ is a euphemism for quite different barriers, which map to different stages of readiness to embrace current best evidence into physiotherapy practice. By understanding what is meant by ‘lack of time’, it may indicate specific support required by physiotherapists at different stages of changing these behaviours.
Technological advancements in the past few decades have made it possible to manufacture nanomaterials at large scale and ENPs are increasingly found in consumer products such as cosmetics, sports products and LED displays. A large amount of these ENPs are in wastewater and potentially impact the performance of wastewater treatment plants (WWTPs). One important function of the WWTP is nitrification, which is carried out by the actions of two groups of bacteria, ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB). Since most ENPs are found to have or are designed to have antimicrobial activities, it is a legitimate concern that ENPs entering WWTPs may have negative impacts on nitrification. In this paper, the effects of ENPs on nitrification is discussed, focusing mainly on autotrophic nitrification by AOBs and NOBs. This review also covers ENPs effects on ANAMMOX. Generally, nitrifiers in pure and mixed culture can be inhibited by a variety of ENPs, but stress response mechanisms may attenuate toxicity. Long-term studies demonstrated that a wide range of NPs can cause severe deterioration of AOBs and/or NOBs when the influent concentration exceeded an inhibition threshold. Proposed mechanisms include the generation of reactive oxygen species, dissolved metals, physical disruption of cell membranes, bacterial engulfment, and intracellular accumulation of ENPs. Future research needs are also discussed.
Homologous recombination over large genomic regions is difficult to achieve due to low efficiencies. Here, we report the successful engineering of a humanized mTert allele, hmTert, in the mouse genome by replacing an 18.1-kb genomic region around the mTert gene with a recombinant fragment of over 45.5-kb, using homologous recombination facilitated by the Crispr/Cas9 technology, in mouse embryonic stem cells (mESCs). In our experiments, with specific sites of DNA double strand breaks (DSBs) by Crispr/Cas9 system, the homologous recombination efficiency was up to 11% and 16% in two mESC lines TC1 and v6.5, respectively. Overall, we obtained a total of 27 mESC clones with heterozygous hmTert/mTert alleles and 3 clones with homozygous hmTert alleles. DSBs induced by Crispr/Cas9 cleavages also caused high rates of genomic DNA deletions and mutations at small guide RNA (sgRNA) target sites. Our results indicated the Crispr/Cas9 system significantly increased the efficiency of homologous recombination-mediated gene editing over a large genomic region in mammal cells, but also inherently caused mutations at unedited target sites. Overall, this strategy provides an efficient and feasible way for manipulating large chromosomal regions.
The available pneumococcal conjugate vaccines provide protection against only those serotypes that are included in the vaccine, which leads to a selective pressure and serotype replacement in the population. An alternative low-cost, safe and serotype-independent vaccine was developed based on a non-encapsulated pneumococcus strain. This study evaluates process intensification to improve biomass production and shows for the first time the use of perfusion-batch with cell recycling for a bacterial vaccine production. Batch, fed-batch and perfusion-batch were performed at 10 L scale using a complex animal component-free culture medium. Cells were harvested at the highest optical density, concentrated and washed using microfiltration or centrifugation to compare cell separation methods. Higher biomass was achieved using perfusion-batch, which removes lactate while retaining cells. The biomass produced in perfusion-batch would represent at least 4-fold greater number of doses per cultivation than in the previously described batch process. Each strategy yielded similar vaccines in terms of quality as evaluated by Western blot and animal immunization assays, indicating that, so far, perfusion-batch is the best strategy for the intensification of pneumococcal whole cell vaccine production, since it can be integrated to the cell separation process keeping the same vaccine quality.
Background: Most studies on the transition from pediatric to adult care focus on practices at a single institution. We examine the transition for young adults with type 1 diabetes across an entire Canadian province with a small, mostly rural population: Newfoundland and Labrador (NL). Our aim is to determine a comprehensive picture of how transition is occurring in one jurisdiction and explore potential methods for improvement. Methods: A provincial diabetes database and hospital admission data were reviewed for a cohort of young adults who transitioned into adult care to determine the number of transfers occurring, patient characteristics, and the number of diabetes-related hospitalizations. Semi-structured interviews with pediatric and adult diabetes providers were conducted to determine the current process of transition and identify ways for improvement, including the potential role of family physicians. Results: Between 2008 and 2013, 93 patients with type 1 diabetes transitioned into adult care. Fifteen interviews were conducted across the province’s four regional health authorities. Various models of transition care are being employed, reflecting staff and resource availability. While no structured transition program was identified, many providers were comfortable with their current transition processes. Suggested improvements included more structured processes, shared educational resources, and a dedicated transfer clinic. Conclusions: In a province with a relatively small number of patients who transition out of pediatric care annually, we found different approaches for transitioning them into adult care, but this variation may not negatively impact patient outcomes.
Many manufacturers of biopharmaceuticals are moving from batch to continuous processing. While this approach offers advantages over batch processing to manufacturers, demonstration of viral clearance for continuous processes is more complex. Regulators expect manufacturers to use an appropriate scale down model, based on solid scientific justification, to verify the viral reduction capacity of the manufacturing process. The output from chromatography columns operated in continuous processes fluctuates in concentration so that the load for the subsequent column is not homogenous. This must be considered when designing viral clearance studies. One way to approach clearance studies is to downscale the continuous process, using multi-column chromatography systems and in-line spiking of virus. The multi-column chromatography systems and experienced operators, however, may not be available at the CRO performing the study. Another approach is to evaluate each step in traditional batch mode, using existing chromatography systems, but to modify the spiking and loading conditions to mimic the variance introduced by the transition between the two connected process steps. Using a standard chromatography system, we have evaluated a flow through anion exchange chromatography step in a monoclonal antibody process using five different methods to introduce the virus to the column. We have shown that regardless of whether the virus spike is introduced in a well-mixed batch mode, introduced as a concentrated pulse of virus with homogeneous mAb or with a concentrated peak of mAb, the clearance of MMV was similar. This study introduces an alternative way to evaluate viral clearance in a continuous process.
The existence and stability of MNg42+(Sb2F11−1)2 (Ng=Ar,Ne,He,M=Au, Ag, Cu) salt compounds are theoretically investigated in this study. This undertaking is carried out to address the following challenges: (1) synthesizing a bulk salt compound containing a noble gas lighter than krypton and (2) synthesizing the congeners of AuXe42+(Sb2F11−1)2 containing noble gases other than Xe. The reliability of our calculations on the MNg42+(Sb2F11−1)2 (Ng=Ar,Ne,He,M=Au, Ag, Cu) systems is assessed by benchmark calculations of the well-known AuXe42+(Sb2F11−1)2 salt. In the benchmark calculations, a two-pronged evaluation strategy, including direct and indirect evaluation methods, is used to theoretically investigate the spectroscopic constants of AuXe42+and the existence and stability of the AuXe42+(Sb2F11−1)2 salt. The validity of the theoretical calculation methods in the benchmark calculations of AuXe42+(Sb2F11−1)2 allows us to adopt a similar methodology to effectively predict the existence and stability of MNg42+(Sb2F11−1)2 (Ng=Ar,Ne,He,M=Au, Ag, Cu) salt compounds. Calculations based on the Born–Haber cycle using estimated lattice energies and some necessary ancillary thermochemical data show that MAr42+(Sb2F11−1)2 (M=Au, Ag, Cu) salt compounds can be synthesized. The upper-limit stable temperatures are estimated to be −224.43, −146.21, and −80.39 °C. The CuAr42+(Sb2F11−1)2salt compound is a promising candidate. Our calculations also show that the MNg42+(Sb2F11−1)2 (Ng=Ne,He,M=Au, Ag, Cu) salt compounds cannot be stabilized.
Grassland ecosystems account for more than 10% of the global CH4 sink in soils. A 4-year field experiment found that addition of P alone did not affect CH4 uptake and experimental addition of N alone significantly suppressed CH4 uptake, while concurrent N and P additions suppressed CH4 uptake to a lesser degree. A meta-analysis including 382 data points in global grasslands corroborated these findings. Global extrapolation with an empirical modeling approach estimated that contemporary N addition suppresses CH4 sink in global grassland by 11% and concurrent N and P deposition alleviates this suppression by 6%. The P alleviation of N-suppressed CH4 sink is primarily attributed to substrate competition, defined as the competition between ammonium and CH4 for the methane monooxygenase enzyme. The N and P impacts on CH4 uptake indicate that projected increases in N and P depositions might substantially affect CH4 uptake and alter the global CH4 cycle.
Carbazole (Cz) dimers in various cofacial conformations, including staggered (Stg), anti, and syn, were explored by means of ab initio calculations at SOS-MP2, SOS-CIS(D0), and additional coupled cluster calculation levels. As in other π-conjugated molecules, strong Cz excimers form in the syn conformation in both the S1 and T1 states, leading to significantly reduced optical excitation energies, whereas the dimers in the Stg and anti conformations, upon excitation, remain as simple excited dimers, showing similar optical energy gaps to that of the monomer. Being far more stable in the ground state, however, the Stg dimer turned out to be nearly isoenergetic to the syn dimer in the S1 state, and even more stable in the T1 state. In addition, a considerable potential energy barrier between the syn and Stg dimers was found in the calculated S1-state potential energy surface. Given that the ground-state intermolecular interactions are expected to govern the dimer conformations of Cz-based materials in the solid-state films of organic electronics, these results strongly demonstrate that the electronic excitation of Cz dimers do not necessarily lead to the strong excimer formation, unless Cz molecules were forced to be arranged in the syn conformation.
In this study, data from MODIS land surface temperature product level 3 (MOD11A2) were used to investigate the spatiotemporal variation of Eurasian lakes water surface temperature (LWST) from 2001 to 2015, and to examine the most influencing factors of that variation. The temperature of most lakes in the dry climate zone and in the equatorial climatic zone varied from 17 to 31°C and from 23 to 27 °C, respectively. LWSTs in the warm temperate and cold climatic zones were in the range of 20 to 27 °C and -0.6 and 17 °C, respectively. The average daytime LWST in the polar climate zone was -0.71°C in the summer. Lakes in high latitude and in the Tibetan Plateau displayed low LWST, ranging from –11°C to 26°C during the nighttime. Large spatial variations of diurnal temperature difference (DTD) was observed in lakes across Eurasia. However, variations in DTDs were small in lakes located in high latitude and in tropical rainforest regions. The shallow lakes showed a rapid response of LWST to solar and atmospheric forcing, while in the large and deep lakes, that response was sluggish. Results of this study demonstrated the applicability of remote sensing and MODIS LST products to capture the spatial-temporal variability of LWST across continental scales, in particular for the vast wilderness areas and protected environment in high latitude regions of the world. The approach can be used in future studies examining processes and factors controlling large scale variability of LWST.
Mussel adhesive proteins (MAPs) have great potential as bioglues, in particular in wet conditions. Although in vivo residue-specific incorporation of 3,4-dihydroxyphenylalanine (Dopa) in tyrosine-auxotrophic Escherichia coli cells allows production of bioengineered MAPs (bMAPs), the low production yield hinders the practical application of bMAPs. Such low production yield of Dopa-incorporated bMAPs (Dopa-bMAPs) was known to be caused by low translational activity of a noncanonical amino acid, Dopa, in E. coli cells. Herein, in order to enhance the production yield of Dopa-bMAPs, we investigated the coexpression of Dopa-recognizing tyrosyl-tRNA synthetases (TyrRSs). In order to use the Dopa-specific Methanococcus jannascii TyrRS (MjTyrRS-Dopa), we altered the anti-codon of tyrosyl-tRNA amber suppressor into AUA (MjtRNATyrAUA) to recgonize a tyrosine codon (MjtRNATyrAUA). Co-overexpression of MjTyrRS-Dopa and MjtRNATyrAUA increased the production yield of Dopa-MAP by 57%. Similarly, overexpression of E. coli TyrRS (EcTyrRS) led to a 72% higher production yield of Dopa-incorporated bMAP. Even with coexpression of Dopa-recognizing TyrRSs, Dopa-bMAPs have a high Dopa incorporation yield (over 90%) compared to Dopa-bMAPs prepared without any coexpression of TyrRS.
Taking hydrophilic and water-repellent soils from the Guishui River Basin as the research object, one-dimensional infiltration experiments were conducted to study the effects of soil water repellency on cumulative infiltration (CI) and the infiltration rate (IR). The test results show that, for the hydrophilic soil (HS) sample, the CI increases monotonously with time and the IR decreases monotonously. For the water-repellent soil (W-RS), however, the following characteristics were observed: (1) There is an inflection point in the CI and a sudden increase in IR. Larger values of the initial soil water content produce an earlier and more significant inflection point in CI, and a larger peak value of IR. (2) The post-peak stable IR is greater than that the pre-peak value, ignoring the beginning of rapid infiltration, and the overall IR presents a single peak. The applicability of various water infiltration models was analyzed for the two soil types. Numerical analysis suggests the following conclusions: (1) For both HS and W-RS, the Kostiakov function, Gamma function, and Beta function (BF) models exhibit good applicability. (2) For W-RS, the Gauss function model not only reflects the monotonous decrease in IR, but also produces a steady IR in the initial stage, a gradual increase before the peak value, and a gradual decrease after the peak value. Similarly, the BF model reflects the monotonous decrease in IR. A piecewise BF can also reflect the U-shaped change in rapid infiltration before the inflection point, as well as the gradual increase and right-skewed distribution curve of W-RS infiltration before and after the inflection point. The BF model achieves the best simulation accuracy and has the widest applicability.
Rationale, aims and objectives. Applying traditional industrial Quality Improvement (QI) methodologies to primary care is often inappropriate because primary care is best thought of as a network of highly interconnected agents in a complex adaptive system (CAS) that is particularly responsive to bottom-up rather than top-down management approaches. We report on a demonstration case study of improvements made in the Family Health Center (FHC) of the JPS Health Network in a refugee patient population that illustrate features of QI in a CAS framework as opposed to a traditional QI approach. Methods. We report on changes in health system utilization by new refugee patients of the FHC from 2016-2017 and summarize relevant theoretical understandings of quality management in complex adaptive systems. Results. Applying CAS principles in the FHC, utilization of the Emergency Department and Urgent Care by newly arrived refugee patients before their first clinic visit was reduced by more than half (total visits decreased from 31% to 14% of the refugee patients). Our review of the literature demonstrates that traditional top-down QI processes are most often unsuccessful in improving even a few single-disease metrics, and increases clinician burnout and penalizes clinicians who care for vulnerable patients. Improvement in a CAS occurs when front-line clinicians identify care gaps and are given the flexibility to learn and self-organize to enable new care processes to emerge, which are created from bottom-up leadership that utilize existing interdependencies made more sustainable as front-line clinicians use sensemaking to improve care processes. Conclusions and future directions. Recent reforms announced in primary care in Scotland, a few examples in the medical literature, and statements from some healthcare system leaders are examples of early adapters who are applying the principles of CAS to their QI efforts. Such initiatives and our example provide models for others to follow.
Pyrazolidines are very important compounds that widely exist in many natural products. Herein, we have employed high-level DFT calculations to systematically investigate the underlying mechanism of Cu(OTf)2 catalyzed [3+2] cycloaddition reactions that synthesis CF3substituted pyrazolidines. About eight possible initial configurations of the [3+2] reaction is considered and all relevant reactants, transition states and products are optimized. Based on these structures, IRC paths and the wavefunction analysis, we concluded that the Cu(OTf)2 catalyzed [3+2] cycloaddition follow a concerted asynchronous mechanism. The CN bond forms immediately after the formation of the CC bond. Among all eight reaction paths, the energy barrier for the [3+2] reaction that lead to the CF3substituted synpyrazolidine is the lowest one, ca. 3.2 kcal/mol, which might result in the diastereoselectivity that observed in experiment. We have also investigated the reaction processes that without Cu(OTf)2 molecule. The computational results indicate that the energy barriers that form the diastereoisomers are much closer and also larger than the Cu(OTf)2 catalyzed one. Therefore, Cu(OTf)2 catalyst plays an important role for the diastereoselectivity of the [3+2] cycloaddition reaction. Our present work not only gives the detail mechanism of the Cu(OTf)2 catalyzed [3+2] cycloaddition, but can also be helpful for the future designation of Cu(OTf)2 based cycloaddition processes.
Pathogen persistence in host communities is influenced by a hierarchy of heterogeneities from individual host to landscape-level attributes, but isolating the relative contributions of these heterogeneities is challenging. We developed theory to partition the influence of host species, habitat patches, and landscape connectivity on pathogen persistence within host-pathogen metacommunities. We used the framework to quantify the contributions of host species composition and habitat patch identity on the persistence of an amphibian pathogen across the landscape. By sampling over 11,000 hosts of six amphibian species, we found that a single host species could maintain the pathogen in 91% of the metacommunities we observed. Moreover, this dominant maintenance species contributed, on average, twice as much to landscape-level pathogen persistence compared to the most influential source patch in a metacommunity. Our analysis demonstrates substantial inequality in how species and patches contribute to pathogen persistence, with important implications for targeted disease management.
Clinical use of pancreatic beta islets for regenerative medicine applications requires mass production of functional cells. Current technologies are insufficient for large-scale production in a cost-efficient manner. Here, we evaluate advantages of a porous cellulose scaffold and demonstrate scale-up to a wicking-matrix bioreactor as a platform for culture of human endocrine cells. Scaffold modifications were evaluated in a multi-well platform to find the optimum surface condition for pancreatic cell expansion followed by bioreactor culture to confirm suitability. Preceding scale-up, cell morphology, viability and proliferation of primary pancreatic cells were evaluated. Two optimal surface modifications were chosen and evaluated further for insulin secretion, cell morphology and viable cell density for human induced pluripotent stem cell-derived pancreatic cells at different stages of differentiation. Scale-up was accomplished with uncoated, amine-modified cellulose in a miniature bioreactor, and insulin secretion and cell metabolic profiles were determined for 13 days. We achieved 10-fold cell expansion in the bioreactor along with a significant increase in insulin secretion compared with cultures on tissue-culture plastic. Our findings define a new method for expansion of pancreatic cells on wicking-matrix cellulose platform to advance cell therapy biomanufacturing for diabetes.
Calcium carbonate (CaCO3) is an inorganic compound which is widely used in industry, chemistry, construction, ocean acidification and biomineralization due to its rich constituent on earth and excellent performance, in which calcium carbonate hydrates are important systems. In Z.Y. Zou et al’s work (Science, 2019, 363, 396–400), they found a novel calcium carbonate hemihydrate phase, but the structure stability, optical and mechanical properties has not been studied. In this work, the stability, electronic, optical, and mechanical properties of novel calcium carbonate hydrates were investigated by using the first-principles calculations within density functional theory (DFT). CaCO3·xH2O (x=1/2, 1 and 6) are determined dynamically stable phases by phonon spectrum, but the Gibbs energy of reaction of CaCO3·1/2H2O is higher than other calcium carbonate hydrates. That’s why the CaCO3·1/2H2O is hard to synthesize in the experiments. In addition, the optical and mechanical properties of CaCO3·xH2O (x=1/2, 1 and 6) are expounded in detail. It shows that the CaCO3·1/2H2O has the largest bulk modulus, shear modulus, Young’s modulus with the values 60.51, 36.56 and 91.28 GPa with respect to other two calcium carbonate hydrates investigated in this paper. This work will provide guidance for experiments and its applications, such as biomineralization, geology, and industrial processes.