The extracellular volume (ECV) and intracellular volume (ICV) estimated by bioimpedance analysis (BIA) deviates markedly from the textbook volumes of 20% and 40% of the body weight (BW). We estimated the transcellular exchange of water by calculating solute equilibriums after fluid challenges to examine whether the BIA or the textbook volumes are likely to be most correct.Data was retrieved from 8 healthy male volunteers who received 25 mL/kg of Ringer’s solution or 3–5 mL/kg of hypertonic (7.5%) saline over 30 min after the ECV and ICV had been estimated by BIA. The exchange of water between the ECV and the ICV was calculated according to a sodium equation and an osmolality equation. Simulations were performed, where deviating body fluid volumes were applied.p < 0.05 versus the “textbook” volume). Mean ICV measured with BIA was 22.3% of BW (p < 0.05). The sodium and osmolality equations correlated closely with respect to the translocation of water across the cell membrane (r2 = 0.86). By applying the “textbook” ECV, the sodium equation indicated that Ringer’s solution exchanged negligible amounts of water, while hypertonic saline withdrew 1.4 L from the ICV to the ECV. By contrast, applying the BIA-derived ECV to the sodium equation implied that 3 L of water would be translocated from the ECV to the ICV once hypertonic saline was administered.The mean ECV measured with BIA was 24.9% of BW (The “textbook” ECV and ICV volumes but not the BIA-derived volumes were consistent with the fluid shifts obtained by two solute equations. The body fluids are traditionally divided into an extracellular volume (ECV) and an intracellular volume (ICV). Medical textbooks teach that the ECV represents 20% of the body weight (BW), while ICV corresponds to 40% of the BW based on indicator–dilution techniques –3.These fractions have been challenged by studies, where electric bioimpedance analysis (BIA) has been applied. The software used with the BIA is calibrated using isotope methods –6 but thIn the present work, we study the usefulness of mass balance equations to examine whether a reported body fluid size is reasonable or more likely to be erroneous. For this purpose, we applied a sodium and an osmolality equation that are dependent on correct sizes of the ECV and ICV to estimate the transcellular shift of water after a fluid challenge , 14. TheA comparison between the “textbook volumes” and those reported by BIA served as an example. We used data obtained during experiments in volunteers, where BIA had been measured and isotonic and hypertonic electrolyte fluids were infused in volunteers , 15.The report is a retrospective analysis of two prospective studies of hemodilution during fluid therapy in volunteers. The protocols had been approved by the Ethics Committee of Huddinge University Hospital  , 15. InfThe volunteers had a light breakfast consisting of one glass of water or milk and one sandwich at least 2 h before the infusion. They voided and were weighed just before the infusion started. A recumbent equilibration period of 30 min was allowed before the experiments were initiated.Ringer group) or 5 mL/kg of 7.5% (hypertonic) saline or 3 mL/kg of 7.5% saline in 6% dextran (Hypertonic group). All infusions were administered at a constant rate over 30 min using infusion pump. Volunteers received both types of infusion. The washout period between the experiments was at least 1 week.The infusions were 20–25 mL/kg of nearly isotonic crystalloid fluid either Ringer’s lactate or acetate , and at 240 min. They were analyzed for the serum sodium and the serum osmolality at the hospital’s certified clinical chemistry laboratory. The urinary excretion was measured at 240 min and taken into consideration for sodium and osmolality equation calculation at that point in time. Hence, any adjustment of the fluid shifts indicated by the osmolality equation at 30 min and 240 min was solely due to urinary losses of water and osmolality. By contrast, the sodium equation considered measurements of serum sodium both at 30 min and 240 min in addition to urinary losses at 240 min.Sodium was analyzed by an ion-selective, direct potentiometry technique using an IL BGE analyzer  with a coefficient of variation of between 1 and 2%. Osmolality was measured by an Osmometer 3C2  which is based on freezing-point depression. The CV was approximately 1%.The size of the ECV and the ICV were estimated by multi-frequency bioelectrical impedance  just before each infusion was initiated. The software calculates these volumes based on a series of 50 currents of different frequencies between electrodes affixed to the dorsum of one hand and one foot. The mean of three consecutive measurements was used.The diffusion of fluid into and out of the cells (fluid shift) was calculated by both a sodium equation and an osmolality equation.T) during or after an intravenous infusion of fluid (NaT) equals the amount of Na in the ECV volume divided by the current ECF volume.The sodium equation is based on a mass balance concept implying that sodium ions (Na) and water in the ECV remain constant over time except for additions and losses. All these additions and losses are known except for fluid exchange between the ECV and ICV spaces. Since Na is distributed throughout the ECV space, the serum Na concentration at any time . p < 0.05 was considered statistically significant.Data is presented as the mean and standard deviation (SD). The relationship between fluid shift according to different equations was evaluated by simple linear regression analysis, where Ringer group), while 7.5% saline was given to two individuals and 7.5% saline in 6% dextran 70 dextran to seven volunteers (Hypertonic group).A complete data set was obtained from 15 experiments that were performed in eight male volunteers with a mean age (SD) of 32 (8) years and with a BW of 82 (9) kg. Three volunteers received Ringer’s lactate and three Ringer’s acetate (p < 0.05). Mean ICV measured with BIA was 18.5 L (22.3% of BW), which is significantly smaller than the assumed 32.5 L based on 40% of BW (p < 0.05).The ECV measured with BIA was 20.4 L (24.9% of BW), which is 4 L more than given by the widely assumed fraction of 20% of the BW (Table p = 0.002). Similarly, 87% more osmoles were excreted compared to the Ringer group (p < 0.01), while the excreted fluid volumes did not differ (p = 0.39).Table The osmolality equation indicated that the transfer of water across the cell membrane in the Ringer group amounted to − 72 (10) mL at 30 min and to − 183 (174) mL at 240 min. The corresponding values according to the sodium equation were − 194 (9) mL and + 198 (104) mL, respectively.In the Hypertonic group fluid recruitment derived by the osmolality equation was + 1355 (595) mL at 30 min and + 694 (404) mL at 240 min. When based on the sodium equation the fluid transfer amounted to + 1212 (385) mL and + 1178 (466) mL.The urinary losses of solutes and water were considered in the calculation at 240 min but these data were not available at 30 min.Figure Figure The mean difference between the output of the osmolality and the sodium equation was − 153 mL (SD 350 mL).The following simulations aimed to examine whether the solute data best agreed with ECV and ICV volumes as measured by the BIA or by the commonly reported “textbook” fractions of 20% and 40% of the BW.The sodium and osmolality equations were then used to simulate the transcellular fluid shift based on changes of assumed ECV and ICV volumes in steps of 10% between 50 and 130% of the “textbook” fractions. These simulations showed that the ECV but not the ICV greatly affected the calculated fluid shift  in the sodium equation Fig. A the fluDeliberate changes of the ICV in the osmolality equation resulted in much smaller variations of the fluid translocation (during this simulation, the ECV was maintained at 20% of the BW, Fig. Our results illustrate that solute equations can be applied after an infusion of isotonic or hypertonic fluid to ascertain whether assumed or measured ECV is reasonable from a physiological point of view. The osmolality equation tells us that Ringer’s should translocate only very minor amounts of water across the cell membrane. However, using the solute equations with an ECV that differs that from the “textbook” value it would imply that a large transfer of water in and out of the ECV occurs, which we know is not the case Fig. A. The laThe precise volumes may be modified by urinary excretion and solutes and fluid, but our calculations show that dramatically different flows are predicted if the ECV is changed. By contrast, the solute equations proved less useful to ascertain whether a reported ICV is reasonable.The transcellular transport of fluid as indicated by of one sodium and one osmolality equation was calculated in a young volunteer population given an infusion of hypertonic or isotonic crystalloid infusion. Both equations yielded similar mean values for transcellular transport of water when the ECV and ICV were set to the “textbook” volumes. The Ringer infusions caused only minor changes of intracellular water, while hypertonic fluid withdrew more than 1 L from the ICV, which represents approximately 4.5 times the infused volume of 7.5% saline. One could perhaps expect 7.5 times the infused volume would be withdrawn, but more pronounced transcellular allocation of water is counteracted by concentration of the intracellular electrolytes.No data on the urinary excretion was obtained at 30 min, but losses of electrolytes and water were probably quite small at that time. Complete data was only available at 240 min. Then calculations then disclosed a left-sided displacement of the fluid recruitment curve as evidence that some fluid had already returned to the ICV (cf. Figs. Our results suggest that calculations based on solute changes can be used to examine how realistic a reported ECV volume is. Logical transcellular fluid shifts were obtained when the ECV was set to the “textbook volumes” being 20% of BW for the ECV and the 40% of the BW for the ICV. However, the simulation using the BIA-derived size the ECV is highly unlikely to be correct. Being 25% of the BW would mean that several liters of fluid enters the ICV when hypertonic saline is infused Fig. A. The laWe have previously pointed out that the ECV and ICV measured with BIA disagrees with these commonly accepted “textbook” volumes, although it has been unclear which one is most correct . The BIAOur results further show that calculations based on solute changes cannot be used to examine how realistic a reported ICV volume is using the same reasoning as for the ECV volume. The size of the ICV could not be adequately assessed by the osmolality equation. However, a regression plot comparing the osmolar balance and the change in serum osmolality yielded more clear information. This plot indicated that the ICV amounted to 33% of the BW Fig. . Hence, There may be several explanations to the difference in body fluid volumes between the textbooks and the more recently obtained BIA values. One is that the ICV, and to some degree the ECV, depends on the daily water intake as indicated by urinary biomarkers; a low intake is associated with a larger ICV and a high daily intake, resulting in more diluted urine, with a smaller ICV . The larAlternatively, the radioisotope measurements used to create the computer program that converts the BIA spectral signals to ECV and ICV for the widely used Xitron spectroscope may have been interpreted erroneously. The original study used for this purpose measured the ECV with bromide and arrive at 24.5% of the BW . The autThe BIA literature has caused uncertainty about the sizes of the body fluid compartments. Several previously published studies using BIA report fractions higher than the commonly accepted 20% of the BW for ECV and markedly lower fractions than 40% for the ICV. These results seem to be in line with findings in this study with ECV accounting for 25% of BW and ICV for 22% of BW of BW Table .When applying BIA in males, Ohashi et al. found the ECV to be 22.4% of the BW , while iOld studies using dilution–indicators techniques report body fluid volumes that agree better with the “textbook volumes” than the more recent BIA literature , 3, 19. The presence of fractions of structured water may possibly explain differences on measuring body compartments with different methods , 21. NorSodium might the stored in non-osmotic form when given in a large surplus. Engberink et al. showed that only 47% of the sodium and 55% of the potassium could be recovered in the urine 4 h after infusion of hypertonic saline in 12 healthy volunteers . PossiblThe sample size was relatively small and did not include females, who are known to have a different water composition than men. A surgical population of elderly patients with comorbidities could also have had different body fluid composition and fluids , 24.Some of the hypertonic infusions contained dextran, which redistributes fluid from the interstitial fluid space to the plasma. However, the osmolality due to the colloid component is negligible, leaving almost no room for additional redistribution of fluid across the cell membrane.Mass balance calculations based on whole-body equilibriums of solutes after intravenous infusion of isotonic and hypertonic fluid show that the estimated water exchange across the cell membrane is incompatible with the size of the ECV obtained by Xitron BIA. By contrast, the same calculations agree well with the ECV volume amounting to 20% of the body weight which is commonly reported in medical textbooks.


The Mn55Al45C2(VC)x  alloys have been prepared by induction melting resulting in a high content of the ferromagnetic τ-phase (> 94 wt.%). Powder X-ray diffraction indicates that nano-VC can be dissolved in the alloy matrix up to 1 at.%. On the other side, metallography investigations by scanning electron microscopy and scanning transmission electron microscope show inclusions of the nanosized additives in the microstructure. The effect of nano-VC on the grain and twin boundaries has been studied by electron backscattering diffraction. The magnetization has been measured by magnetometry up to 9 T while the domain structure has been studied using both magnetic force microscopy as well as Kerr-microscopy. For nano-VC contents above 0.25 at.%, a clear increase of the coercive force is observed, from 57 to 71 kA/m. The optimum appears to be for 0.5 at.% nano-VC which shows a 25% increase in coercive force without losing any saturation magnetization. This independent increase in coercivity is believed to originate from the nano-VC reducing the overall magnetic domain size. Overall, we observe that addition of nano-VC could be an interesting route to increase the coercive force of MnAl, without sacrificing saturation magnetization.Alloys of Mn After the rare-earth crisis in 20111, increasing attention has been placed on finding the so-called gap permanent magnets2 with performance exceeding those of hexagonal ferrites. One potential candidate is MnAl, which has enough anisotropy3 to be a permanent magnet of gap performance, i.e. to be able to supersede hexagonal ferrites but not rare-earth magnets. In the Mn–Al phase diagram4, there is only a single ferromagnetic phase, τ-MnAl, which is metastable5. The compound was discovered by Kono in 19586 and found to be ferromagnetic by Koch7 in 1960 but has still not been realized as a commercial product despite promising properties such as high saturation magnetization  were added in MnAl (but without carbon) as (Mnx0.5+Alx0.5-)y100-REy 20, which created nanoprecipitates of ~ 20 nm size that helped to pin domain walls and thus realizing a coercivity as large as 420 kA/m (5.43 kOe). We therefore, chose Mn55Al45C2 as base material for our investigations since it is more stable and the performance is more promising compared to the C-free τ-MnAl. The goal was to prepare Mn55Al45C2 with well dispersed nanoparticles to create pinning sites for domain walls. To achieve this, we added different amount of nano-VC to the Mn55Al45C2 base compound to elucidate its effect on the microstructure and magnetic properties.In a recent study, nanoparticles of rare earths (55Al45C2(VC)x  alloys (~ 15 g each) were synthesized by induction melting. High purity raw materials have been used as starting materials for synthesis of the Mn55Al45C2(VC)x alloys: Mn powder , Al , C , VC nanopowder . Firstly, powders of Mn and nano-VC were weighed, well mixed and pressed into pellets in a glovebox. Appropriate amounts of Al and C were put together with the Mn55(VC)x-pellets in an Al2O3-crucible. Afterwards the crucible was transferred to a high frequency induction furnace and vacuum pumped for 1 h. The melting was done by introducing 5 N Ar gas to have an atmosphere of 400 mbar. At the highest temperature (1300–1500 °C) the temperature was kept for 1–3 min to form a homogeneous solution. Finally, the furnace was switched off, followed by natural cooling to room temperature. The total mass loss during synthesis was less than 2 wt.%. In the event of larger losses, more Mn was added to compensate as for these alloys only Mn evaporates during melting.MnKα radiation on a zero-background single crystal Si sample holder. Phase analysis and Rietveld refinements of the X-ray data were done with the GSAS suite software21. For the Rietveld refinement of the PXRD we have used following information from literature14: the main τ-phase is a tetragonal L10 superstructure  with interstitial of C at [1/2 1/2 0], γ2 phase  and VC .All samples were characterized using a Bruker D8 powder X-ray diffractometer with a Lynx-eye position sensitive detector and Cu-3 3 ml, HF 1 ml and H2O 290 ml. Samples were analyzed in a field emission scanning electron microscope (FE-SEM) Hitachi SU6600 equipped with an EDS system (Bruker EDX XFLASH 5010). Furthermore, the EBSD experiment was done using a Zeiss Merlin equipped with a Nordlys Max detector and evaluated by the AZtec HKL software. Characterization at high magnification was done using an FEI Titan Themis 200 scanning transmission electron microscope (STEM) equipped with SuperX EDS and spherical aberration corrector. The TEM specimen was prepared by the in-situ lift-out technique in a Zeiss Crossbeam 550 focused ion beam scanning electron microscope (FIB-SEM). The surface was protected with Pt and a final polishing step using a 5 kV ion beam was utilized to minimize beam damage from the preparation.Microstructural evaluations were carried out using scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS), electron backscattering diffraction (EBSD), magnetic force microscopy (MFM) as well as magneto-optical Kerr effect (MOKE) microscopy. Samples were cut in an Accutom-50 and subsequently mounted in Levofast resin and bakelite PhenoCure™, grinded and polished down to 1 µm by a standard process. The polishing was done with OPS-S non-drying colloidal silica suspension for 5 min in order to improve planeness and for relief polishing. Before etching, the samples were analyzed with a light optical microscope (LOM) in a Zeiss Axio Imager M2m microscope. They were afterwards etched in a diluted modified Keller’s reagent: with HCl 6 ml, HNO22 using background correction and flattening. Magnetic hysteresis curves were measured at 300 K using a Quantum Design PPMS with a maximum applied field of 9 T. The samples were corrected for demagnetizing effects.Magnetic force microscopy (MFM) was performed using a Bruker Dimension Icon system. Images were processed by the software GWYDDION23.An evico magnetics Kerr microscope, with motion correction since the forces on the samples are rather strong, was used for magnetic domains observation. Room temperature Kerr microscopy studies were carried out in longitudinal geometry, i.e. applying an in-plane magnetic field parallel to the plane of incidence. In this configuration, out-of-plane components are dominating the magnetic contrast55Al45 phase (Mn55Al45C2 made by drop synthesis)25 showed great purity and promising magnetic properties. However, despite being able to obtain close to 100% phase pure τ-MnAl the material still has challenges, mainly in terms of its microstructural properties which need to be improved to compete with ferrites. In this investigation, nano-VC additive has been selected in an attempt to achieve this. It should be taken into account that all samples in this work were synthesized by direct induction melting and all further investigations were done on the as-prepared samples. The Mn55Al45C2 alloy has been made as a reference for comparison. Investigation of the quality of Mn55Al45C2(VC)x alloys has been done by powder X-ray diffraction (PXRD). Figure 55Al45C2, Mn55Al45C2(VC)0.25, Mn55Al45C2(VC)0.5, Mn55Al45C2(VC)1 and Mn55Al45C2(VC)3.5 samples. Notably, peaks of VC are not visible by PXRD up to a concentration of 1 at.% of VC. A complete phase analysis of the synthesized and processed samples is presented in Table Previous investigations on the carbon stabilized τ-Mn55Al45C2 has 85 wt.% of τ-phase purity while doped Mn55Al45C2(VC)x (x ≤ 1) alloys have greater purity (see in Table 55Al45C2(VC)x alloys is very close to the drop synthesized10. Using C is thus important for stabilization of the τ-phase even when introducing nano-dopants. One sample with larger content of nano-VC (3.5 at.%) has been prepared to verify the solubility limit. Additionally, one alloy without carbon (sample not presented here) but with nano-VC has been made. However, the purity of the C-free sample dropped drastically (65 wt.% of τ-phase). It should be noted that the chosen additive even promotes and amplifies in combination with carbon the stabilization/formation of the τ-phase alloys.From the Rietveld refinement it was found that MnVC)x x ≤  alloys h55Al45C2(VC)1 alloy was selected for detailed microstructural analysis. SEM observations on this etched sample  and Mn39Al61(Al-rich region) are in agreement with the τ-Mn0.55Al0.45C0.02 and γ2-Mn5Al8 phases, respectively. This is in good agreement with the results from PXRD.EDX analysis cannot confirm the existence of nano-VC in the alloy, since the particles are too small in comparison with the resolution of the instrument. However, EDX mapping reveals a homogeneous distribution of V and a few Al-rich regions within the τ-phase Figure . In addiThe presence of VC particles in the τ-phase was further investigated in the TEM. Figure 55Al45C2, Mn55Al45C2(VC)0.5 and Mn55Al45C(VC)1 samples. It can be seen in Fig. 2-phase (shown in blue) randomly distributed within the samples. Figure 2-phase for the three samples. The τ-phase is randomly oriented, but all individual grains of the γ2-phase appear to be oriented in similar directions, which could originate from solidification if the γ2-phase solidifies with a preferred orientation in regard to the thermal gradient. In the last few years, much work has been done to elucidate certain features of the microstructure and its effect on the performance of τ-MnAl such as anti-phase defects26, dislocations28, interfaces29 and twins30. As many of these features are coexisting, often together with a difference in tetragonality (c/a ratio) of the τ phase, it is still not fully resolved which of these features have a negative impact on magnetic properties like magnetization, remanence and coercivity. Very recently, two studies31 were presented which show that for instance the coercivity can be negatively affected by twinning and that dislocations instead improve the coercivity.Figure 55Al45C2, Mn55Al45C2(VC)0.5 and Mn55Al45C(VC)1 samples, respectively. It can be seen that a large amount of low angle grain boundaries  are formed in the sample without nano-VC, as well as a large fraction of grain boundaries with angles of 75˚ and 85˚ corresponding to <100> and <110> twins. With the addition of nano-VC, the amount of small angle grain boundaries decreases significantly to 17% and 14% for 0.5 at.% and 1 at.% respectively. Figure 55Al45C2, Mn55Al45C2(VC)0.5 and Mn55Al45C(VC)1 samples, respectively. Furthermore, the coherent boundaries in the twins are illustrated in Fig. Figure 55Al45C2, Mn55Al45C2(VC)0.25, Mn55Al45C2(VC)0.5 and Mn55Al45C2(VC)1 to investigate the magnetic properties. All curves were corrected for demagnetizing effects. The results can be seen in Fig. Hysteresis measurements were performed up to 7200 kA/m (9 T) on samples of Mn55Al45C2(VC)0.5 and Mn55Al45C2(VC)1, where first one has slightly less concentration of τ-phase compare to the last one . However, measured magnetization values show opposite trend 100Cx increases saturation magnetization14 slightly from carbon free to some carbon added, while too much decreases the saturation magnetization. This is however further complicated by the fact that the c/a ratio varies between the samples, which is also known to affect magnetization32. The τ-phase in all Mn55Al45C2(VC)x  alloys has higher c/a ratio than in Mn55Al45C2, which also has been seen to affect both HA and TC. This increase in c/a ratio is most probably due to differences in the C content of the samples.To start with, there is no strong correlation between the magnetization measured in an applied magnetic field of 9 T and the amount of τ-phase. Compare for instance MnThe vanadium carbide seems to have more pronounced effect on the coercive force, which is varying between 57–71 kA/m. The optimum appears to be for 0.5 at.% nano-VC which shows a 25% increase in coercive force (from 57 to 71 kA/m) without losing any saturation magnetization.55Al45C2, Mn55Al45C2(VC)0.5 and Mn55Al45C2(VC)1 to investigate the influence of added precipitates on the magnetic microstructure. The as-cast samples were polished in the same way as it had been done for the SEM studies. The measurements were performed on a Dimension Icon system from Bruker. Each sample was investigated at different positions and one representative result is shown in Fig. We performed magnetic force microscopy (MFM) studies on the as-cast samples for Mn33. For the stereological procedure, arbitrary line profiles are drawn through the domain image and the changes of the domain state along each line is recorded. The domain width is calculated as follows:Qualitatively, smaller domains can be seen for the samples with VC precipitates, to investigate the domain size quantitatively we use the stereological procedureApplying this procedure to each domain image and averaging the results for one sample yield the domain width distributions presented in Fig. 55Al45C2, Mn55Al45C2(VC)0.5 and Mn55Al45C2(VC)1 it can be seen that the samples with VC precipitates have a reduced domain width, verifying the more qualitative observations based on Fig. Comparing the distributions of Mn55Al45C2(VC)1 sample in more detail, we noticed at different locations a correlation between the domain appearance and precipitates visible in the topography. Figure Investigating the MnComparing the location of the smaller and larger domains in the magnetic contrast image in Fig. 55Al45C2, Mn55Al45C2(VC)0.5 and Mn55Al45C2(VC)1. The measurements were performed using the polar and longitudinal magneto-optical Kerr effect (MOKE); therefore, we are sensitive to magnetization components both out-of- plane and parallel to the applied in-plane magnetic field. The investigated as-cast samples have various orientations of the grains. Hence, a preferred anisotropy axis could not be identified and each grain had an almost unique response to the applied magnetic field. Figure To investigate the domain structure under applied field we performed Kerr microscopy studies on the polished surface of the as-cast pieces of Mn55Al45C2(VC)0.5 and Mn55Al45C2(VC)1 in comparison with Mn55Al45C2. But this observation cannot be quantified using the Kerr microscopy studies, as the domain structure visible in the images will interfere in any grain size analysis.Another observation based on the microstructure is that the grain size seems to be reduced for the samples MnThe lower two rows in Fig. These results from the domain dynamics are expected, as there are no big differences between the samples in the magnetization measurements for the available field range of the Kerr microscope Fig. .55Al45C2 have been investigated by various techniques. It was shown that the nano-VC containing Mn55Al45C2(VC)x  samples were purer in τ-phase in comparison to the reference . Metallography studies demonstrate a microstructure with nanometer sized inclusions of carbides. The addition of nano-VC significantly decreases the amount of small angle grain boundaries as compared to Mn55Al45C2. In relation to this, the presence of twin boundaries with angles of 75˚ and 85˚ corresponding to <100> and <110> twins, respectively, increases with the addition of nano-VC.The effects of the nano-VC on the microstructure and magnetic properties of Mn32. Comparing carbon free τ-phase MnAl to carbon substituted τ-phase MnAl show that some amount of carbon is beneficial for saturation magnetization, while too much lowers the saturation magnetization14. This has also been reported to decrease K1 and TC14. However, all of this is further complicated by the fact that atomic order, carbon content and c/a ratio  varies in these samples. Separating these effects from each other is however outside of the scope of this work.For nano-VC contents above 0.25 at.%, a clear increase of the coercive force is observed, from 57 to 71 kA/m. The optimum appears to be for 0.5 at.% nano-VC which shows a 25% increase in coercive force without losing any saturation magnetization. This independent increase in coercivity is believed to originate from the nano-VC reducing the overall magnetic domain size. Also, as there is a weaker than usual correlation of τ-phase purity and magnetization in these alloys, it is concluded that saturation magnetization is here not only determined by the amount of τ-phase, but also the amount of carbon, which has been reported to have effects on saturation magnetization55Al45C2. This effect can be caused by nucleation of magnetic domain walls by the precipitates or being an indirect effect of a reduced grain size, but most likely it is a combined effect of both.From magnetic force microscopy, we can conclude that nano-VC precipitates reduce the domain size in Mn55Al45C2, Mn55Al45C2(VC)0.5 and Mn55Al45C2(VC)1 samples. This finding is in good agreement with the magnetization measurements. Additionally, we can see a large variety of grain orientations leading to a vastly different response of the magnetic domains to the applied field. However, we cannot identify traces of strong pinning within a single grain in neither the Mn55Al45C2(VC)0.5 or Mn55Al45C2(VC)1 sample.Kerr microscopy studies revealed that there are no measurable differences in the dynamic response to the applied magnetic field for the investigated MnOverall, we can conclude that addition of nano-VC could be an interesting route to increase the coercive force of MnAl, without sacrificing saturation magnetization. However, before this can be realized, much deeper investigations on the effects of inclusions of nanoparticles in MnAl are needed.Supplementary Figures.Supplementary Video 1.Supplementary Video 2.Supplementary Video 3.


Given the ubiquity of bubbles and non-biodegradable wastes in aqueous environments, their transport through bubbles should be widely extant in water bodies. In this study, we investigate the effect of bubble-induced waste transport on microbial growth by using yeasts as model microbes and a silicone rubber object as model waste. Noteworthily, this object repeatedly rises and sinks in fluid through fluctuations in bubble-acquired buoyant forces produced by cyclic nucleation, growth and release of bubbles from object's surface. The rise–sink movement of the object gives rise to a strong bulk mixing and an enhanced resuspension of cells from the floor. Such spatially dynamic contaminant inside a nutrient-rich medium also leads to an increment in the total microbe concentration in the fluid. The enhanced concentration is caused by strong nutrient mixing generated by the object's movement which increases the nutrient supply to growing microbes and thereby, prolonging their growth phases. We confirm these findings through a theoretical model for cell concentration and nutrient distribution in fluid medium. The model is based on the continuum hypothesis and it uses the general conservation law which takes an advection–diffusion growth form. We conclude the study with the demonstration of bubble-induced digging of objects from model sand. Approximately 10 quintillion  a bubble-trapping object. Such an object is preferably hydrophobic so that it can easily capture gas bubbles in order to levitate. Various interesting researches in the recent past have played with these two ingredients to have a desired control over the transported object. For instance, Pinchasik et al. [et al. [et al. [et al. [The bubble-induced transport has two main ingredients: (i) k et al.  demonstr [et al.  devised  [et al.  created  [et al.  fabricat [et al. ,23.In this study, we explore the bubble-induced transport of hydrophobic objects with a different objective. According to the report of the United Nations World Water Assessment Programme (UN-WWAP) 2003, about 2 million tons of industrial and agricultural wastes are discharged into the world's waters every day . Given tIn the next section, we elaborate upon our experimental results, which include describing the phenomenon of bubble-induced vertical transport of a hydrophobic object and the process of sediment suspension through object's wake. In §3, we quantify the enhanced cell transport caused by the motion of the object with the help of a continuum model for vertical distribution of yeasts within the fluid. In §4, we describe how the bubble-induced object transport led to an increase in the total yeast concentration through enhanced nutrient utilization, which is also supported through a mathematical model. Finally, in §5, before presenting our concluding remarks, we show that a rubber object, initially buried underneath a layer of model sand, can make its way into the fluid medium by harnessing bubbles. All experimental techniques, protocols and mathematical methods are described in §6.. 2a with fermenting yeasts (Saccharomyces cerevisiae) as model microorganism residing inside a nutrient broth (standard yeast extract–peptone–dextrose (YPD) medium [2 bubbles, released as the consequence of nutrient metabolism by yeasts, creates a bubble layer above the fluid layer. This setting loosely mimics a water body with a sediment layer of live benthic microorganisms, where water with dissolved organic matter constitutes the fluid domain and where bubbles are formed via various phenomenon ranging from wave-breaking to methane generation by cyanobacteria.The model physical setting for this report is illustrated in figure 1) medium , details) medium . The nutbρ ≈ 1.10 g cm−3) within this set-up. As can be seen, the inherent surface roughness and hydrophobicity of the foreign object leads to heterogeneous nucleation and accumulation of gas bubbles on its surface. Depending upon the duration of bubble residence (bt = 820.8 ± 368.0 s) on the surface and mean bubble departure diameter (bd = 1 ± 0.4 mm), the density of such object can effectively be reduced below that of the ambient medium. Please note that, in our case, the bubble size distribution on object surface has a mean diameter of 394.7 µm with a standard deviation of 190.9 µm. The further details of bubble behaviour on different material surfaces, along with a probability distribution for bubble size on silicone rubber, can be found in electronic supplementary material, S1.For our investigation, to see how the presence of an inert non-biodegradable foreign object affects the microorganisms and their dynamics, we introduce a silicone rubber cuboid  cycle on yeast cells? So, we performed three simultaneous experiments which included: (i) a control (YPD broth + yeasts), (ii) fermentation with a fixed object (YPD broth + yeasts + static cuboid), and (iii) fermentation with an object free to rise and sink (YPD broth + yeasts + dynamic cuboid). The fixed-object experiment was done in order to rule out any mysterious chemical effect that silicone rubber might have on yeasts cells and their metabolism. As can be seen from figure 1id layer . Note thid layer ,31.. 2.1Moving on, the fluid agitation due to R–S cycle causes mixing of yeast cells. The yeasts cells already suspended into the fluid layer due to bubbles' wake or yeast–bubble adhesion are influenced by strong fluid disturbances caused by the repeated rising and sinking of a large object in a confined fluid. Such disturbances due to R–S lead these yeast cells to follow chaotic trajectories created within the fluid layer which can be understood as a diffusion phenomenon with an apparent diffusion coefficient ous work  studied, mixing’ . Since, fo of the R–S cycle. A rapid cycling will cause much stronger agitation when compared with a slower cycle. This is analogous to external mechanical mixing which is a function of the rotational speed of the impeller. We observed that the frequency fo is dependent upon the bubble flux bf  in an ebullient fluid. Such bubble flux is composed of bubbles that have a mean diameter of (306.14 ± 47.5) µm, which more or less remain unchanged throughout the course of fermentation . Notice, from figure 2a, fo is non-zero only when the number of bubbles produced in the fluid is very small (0 < bf ≤ 0.8 cm−2 s−1), which is during first (20–22 h post-inoculation) and last phases (50–52 h post-inoculation) of yeast fermentation process. During moderate to strong bubbling, the amount of gas in the fluid medium is high and the number of bubbles adhering to the object is very large. For this reason, from 22 to 50 h post-inoculation, the effective density of the object remains less than that of the ambient fluid and hence, a zero fo. Note that for determining fo, our counting method involves counting all ‘rise events which are followed by a sink event’ in a 10 min window. The fortuitous occurrence of R–S only during weak bubbling phases is exploitable by brewing industries, as it can enhance fluid mixing when bubble-induced mixing is feeble and is insufficient to avoid nutrient and temperature inhomogeneities, which are crucial to the quality of the finished product [The strength of quasi-natural mixing intuitively depends upon the frequency  product .Figure z as half of the flask width zL i.e. y, it was set to 0.6 cm, which is liberally larger than the capillary length ℓc for air–fluid interface as γ is the surface tension of the medium and air and mρ is the density of the fluid medium. Experimentally speaking, a thinner object is held at the free surface for a very long time (approx. days) due to the relative dominance of surface tension effects over the body weight.Another factor that governs the strength of quasi-natural mixing is the size of the object. A large object displaces more fluid during its motion when compared with a smaller one. For the introduced rubber cuboid, we fixed its width ℓb and found that of is dependent on cuboid length ℓx, given ℓy and ℓz are unchanged. The graph shows that for smaller lengths, the R–S frequency is lower and as the length is increased of grows and then begins to plateau. This tendency possibly occurs due to the stochasticity in bubble-induced buoyant force arising from the randomness in bubble cavity size, bubble detachment diameter and bubble detachment time.Further, we also performed a size study as in figure 2. 2.2a. Observe that after gathering enough bubbles, as the cuboid commences its upward journey, it pulls some of the yeast cells with it into the fluid medium through its wake. This is called sediment suspension and it is widely present in aquatic environments. The contents of sediment layer at the bottom of a water body are often suspended due to a variety of mechanisms including methane ebullition [Other than quasi-natural mixing, a rising object can also mobilize loosely bounded yeast cells in the sediment layer as illustrated in figure 3ullition , bioturbullition ,37, bottullition  and waveullition ,39 in waW of radius 3 mm, near the sediment layer. Note that, velocity streamlines form small vortices in the wake (vorticity υ ≈ 40 s−1) as in figure 3b, which are convected upstream and dissipate rapidly. Corresponding velocity vectors are shown in figure 3c.In this study, we report a new cause of sediment suspension, i.e. the wake of a large non-biodegradable foreign object which is transported through naturally generated gas bubbles. To visualize the fluid disturbances due to a rising cuboid and its evolution, we performed a two-dimensional particle image velocimetry (PIV) measurement of a part of cuboid's left wake, in a fixed circular window τ* is generally used [τ* = τ/(yρ − mρ)gd, where τ is the shear stress on the sediment layer introduced due to the fluid disturbance, yρ is the density of the sediment particle, mρ is the density of the fluid layer, g is acceleration due to gravity, and d is the diameter of the sediment particle. In our case, yρ ≈ 1.07 g cm−3, which is the density of a yeast cell, d ≈ 10 µm is the mean diameter of a yeast cell, and mρ ≈ 1.00 g cm−3 is the density of the YPD medium. Since for yeast cells, the Reynolds number Re is vanishingly small, the shear stress τ can be obtained as η is the viscosity of the medium i.e. 0.001 Pa s, and xu/∂y in the observed wake, which is about 45 s−1. Plugging everything in, we get τ* = 6.55, implying that the shear stress due to object's wake is strong enough to suspend loosely bounded yeasts from the sediment layer into the fluid layer, as we already demonstrated in figure 3a.To characterize whether a given fluid disturbance is strong enough to initiate sediment suspension, Shields parameter lly used . It is ad shows how the number of yeasts that are brought into the medium varies with cuboids of different lengths, with the same widths and thicknesses. Note, the increment Now, to quantify the amount of yeast suspension by the object, we estimated the increment . 3In the previous section, we elaborated upon our experimental results related to the occurrence of repeated rising and sinking of a silicone rubber object inside a fermenting broth which was divided into two main subheads. The first one talked about the quasi-natural mixing of the fluid layer by the R–S cycle and the second one highlighted the process of sediment suspension through cuboid's wake. To be more rigorous, in this section, we will try to quantify these findings.. 3.1FL is the diffusive length scale which is limited by the height of the fluid layer. In our setting, the maximum value of −2 cm2 s−1, and during periods of weak bubbling, where R–S occurs, it is approximately FL and its time scale can be assumed to be the inverse of the R–S frequency of, yielding −1 cm2 s−1, which is about three times the value of maximum bubble-induced diffusivity and is two orders of magnitude larger than the bubble-induced diffusivity in weak bubbling periods. The R–S-induced diffusivity is non-existent during moderate to peak bubbling (a).In §2.1, we talked about the quasi-natural fluid agitation caused by the R–S cycle of a rubber cuboid and mentioned that it can be modelled as a diffusive phenomenon for yeast transport. In the absence of the cuboid, such diffusion occurs due to bubble-induced disturbances, given that the magnitude of fluid agitation occurring due to other small-scale mechanisms such as the Brownian motion and thermal convection are trivially small, approximately us study , this bububbling a.Table . 3.2wN is the number of yeasts cells brought to the bottom of the fluid medium through bubbles’ wake, aN is the number of cells that are carried by each bubble from the sediment layer into the fluid layer through adhesion (given yeasts are hydrophobic in nature) and bf is the number of bubbles produced in unit area of the sediment layer per unit time (cm−2 s−1). However, when an R–S cuboid is present, we have an enhanced suspension flux d, as V is the total volume of the fluid, xzA is the horizontal cross-sectional area of the flask and of is the frequency of R–S cycle. From table 1b, note that In §2.2, we reported the suspension of yeast sediment due to a rising cuboid. Without any cuboid, as elaborated in our previous study , upward . 3.3Moving on, in order to understand how the enhanced transport (i.e. increased diffusivity and increased suspension flux) affects the distribution of yeast concentration within the fluid, it is imperative to develop a mathematical model. In our case, we want this model to describe the vertical distribution of horizontally averaged yeast concentration. Such model was originally developed in our previous study  which ema, and touched upon in §2, there are three layers in the present setting. Since yeast cells are inoculated near the bottom of the flask (i.e. at y = 0.5 cm), after inoculation, all the cells sediment to the floor forming a thin sublayer of yeasts with a typical thickness of one yeast diameter and having a volume fraction ϕ ≈ 10−4. Now, as cells begin to grow, this sublayer starts to get denser. After a certain volume fraction ϕ = Tϕ ≈ 0.6, the layer cannot accommodate any more cells, and hence, the growing cells begin to stack on the top of the tightly packed yeast sublayer. This goes on till we have many tightly packed yeast sublayers forming what we call the yeast sediment layer, which is about 1–2 mm thick. This sediment layer is the source and sink of all yeast cells in the fluid layer and in the bubble layer. We assume that, inside a tightly packed cell layer, advection and diffusion phenomenon can be ignored.As illustrated in figure 1−2 cm, during bubbling. The total yeast flux CL < y < FL) has an advection–diffusion form, which can be given as (a)afbN is the advective flux due to yeast–bubble adhesion pointing vertically upwards, V. A similar yeast flux equation can be written for the bubble layer (CL < y < BL).In the fluid layer, the length scale of the bulk motion and the length scale of the yeast concentration distribution are, respectively, large enough compared with the yeast diameter and the typical cell spacing. The length scales for the bulk motion and yeast concentration distribution are of the order of a few centimetres (i.e. height of the free surface). On the other hand, the yeast diameter is approximately 10 µm and the typical cell spacing i.e. given as a3.1JT=Naα is the yeast growth rate.If we apply the equation of continuity to equation (3.1), we getIntegrating equation (3.2) over the horizontal cross-section of the flask gives us-workers ,42 to moIt is important to mention a couple of points here to avoid confusion. Firstly, since the convection flow and yeast cells satisfy conservation of mass , fluid velocity disturbances do not contribute to the advective yeast transport, and secondly, in equation (3.4), different transport (advective and diffusive) effects can be superimposed because they have relatively independent origins. Also, the linearity of two kinds of diffusivity can be assumed because y = 0.5 cm), initial yeast concentration is set to 105 cells ml−1 for y ≤ 0.5 cm and zero for y > 0.5 cm. At the sediment layer–fluid medium moving interface, the total yeast flux is given by considering upward fluxes due to bubbles and the cuboid and a downward flux due to sedimentation. A similar boundary condition is introduced at the fluid medium–bubble layer interface. At the bubble layer–air interface and the flask floor, we assume there is no flux. The finer details on the mathematical treatment of the cell sediment layer, bubble layer and the boundary conditions can be accessed in the electronic supplementary material S2. The nuances of growth rate α will be explained in the next section as it does not considerably affect the results in this section.For completion, we also need to specify the initial and boundary conditions in the given setting. For the initial condition, since we inoculated yeasts cells near the floor of the flask (i.e. at y = FL − 0.5 cm) and lower (y = cL + 0.5 cm) regions of the fluid layer during two periods of weak bubbling that occur at about 20 and 50 h after initial yeast inoculation. This was performed inside the broth which only had yeast cells and the broth which had yeast cells along with an R–S cuboid. Note from figure 4a,b that yeast concentration in the fluid is increased by about 1200% for the first period of weak bubbling and about 300% for second period of weak bubbling. This is due to the phenomenon of sediment suspension from the wake of the rising cuboid as discussed in §2.2. Also, to assess the effect of quasi-natural mixing leading to enhanced diffusivity, we measured the normalized concentration gradient in the fluid layer as in figure 4c,d. Note that it reduces by about 85–90% for both periods of weak bubbling and is in good agreement with the simulation data.We will now compare the solutions of the governing equation (equation (3.4)) obtained through the method of finite volumes with the experimental measurement of yeast concentration. To do this, we measured the yeast concentration at upper ) typically has three phases: (i) a faster exponential phase (α ≈ 0.38 h−1), (ii) a slower exponential phase (α ≈ 0.015 h−1), and (iii) a stationary phase (α = 0 h−1). Without the R–S cycles, the phase (i) occurs during t = 0–20 h post-inoculation, whereas phase (ii) occurs during t = 20–50 h and lastly, there is a period of no growth for t > 50 h. However, with cuboid R–S cycles, we assume that phase (i) is elongated by a period of 2 h. The effect of glucose supply to the bottom is, therefore, modelled as a corresponding elongation in the ‘fast exponential growth phase’ by 2 h (i.e. the width of the first R–S frequency spike illustrated in figure 2a), which then affects the cell concentration in equation (3.4). During the second spike, the effect of the glucose supply to the floor is negligible as yeasts have already entered the stationary phase.Moving ahead, the growth rate a the yeast concentration y ≤ 0.5 cm), obtained through experiments and simulations are in agreement and the effect of R–S cycles on cell growth is visible. The increment in cell concentration b. The extra mixing by the R–S cycles during weak bubbling significantly increases the glucose concentration at the bottom, using which cells continue their faster exponential phase for a longer time. This tendency can be confirmed in figure 5c, in which a reduction in total glucose concentration in the flask Observe that in figure 5The results in this section suggest that the reported increase in cell growth by R–S cycles occurs due to an increased supply of glucose to the bottom of the flask where most of the cells are present. This increased supply elongates the faster exponential growth phase for the model microbe, thereby leading to an increment in the cell population.. 5In this study, with an objective to understand how bubble-induced movement of non-biodegradable wastes affect water bodies, we started with a model demonstration of cyclic rising and sinking (R–S cycle) of a silicone rubber object in yeast fermentation set up by gas bubbles. Interestingly, this cycle had an effect to increase total cell concentration in the flask. The mechanism of such enhancement in cell growth could be understood through increased nutrient utilization by the cells with the help of R–S cycles. The ingredients to construct the mechanism, i.e. enhanced mixing, enhanced sediment suspension and enhanced glucose consumption, were studied experimentally and a mathematical model was developed which could reproduce the observed phenomena and supported the proposed mechanism.Since, the bubbles and non-biodegradable wastes are abundant, the demonstrated R–S phenomena should be ubiquitous in water bodies, which should affect the vertical distribution of benthic organic matter, the cycling of nutrients in aqueous media, and the cell growth and nutrient consumption in cell sediments. Moreover, there might be some implications for the aquatic food web and the microbial gas emission by such disturbances in nutrient and microbe distribution. As far as the applicative aspect of this research is concerned, our idea can immediately be exploited to design a fluid mixer for brewing industries that does not require any external power source to operate, but rather harnesses the bubbles produced during fermentation itself.Although the space of this article is limited, we would like to conclude by reporting a curious consequence of the bubble-induced transport of hydrophobic objects in a more realistic scenario. In . 6. 6.1S. cerevisiae) of top-fermenting  kind in this research. The yeast culture was performed in three steps which involved dry yeast hydration, a solid YPDA  culture and a liquid YPD culture. In this manuscript, we called the standard laboratory growth medium for yeasts the ‘standard YPD medium’. The composition of such medium includes 1% yeast extract, 2% d-glucose and 2% peptone in distilled water. The percentages are given as the weight of the ingredient in grams (g) divided by the volume of distilled water in millilitres (100 ml). We employed yeasts cultured via this procedure for all our investigations. The details of the cell culture protocol can be found in the electronic supplementary material, S3.We used a fermenting strain of yeasts  or with a DSLR .Our experimental technique for observing object transport in figure 1. 6.3of is then obtained as a,b.To measure the frequency of R–S cycle, we observed the number. 6.4bf cm−2 s−1 which is represented in figure 2a and is used to indicate periods of weak bubbling.It was measured with the help of a DSLR camera  focused at the yeast sediment layer and then counting manually the number of bubbling sources and the number of bubbles released by them per second. This was done for entire floor area to obtain the bubble flux as . 6.5b,c, a cell culture flask containing 50 ml of YPD broth was inoculated with 105 yeasts ml−1 along with a rubber cuboid. Twenty-one hours after this inoculation (weak bubbling period), a vertical plane within the flask was illuminated from the sides with two red sheet lasers (670 nm) inside a dark chamber [In order to do the PIV measurement of the wake in figure 3 chamber . As soon chamber . Velocit. 6.6d.In order to determine the increment in suspended yeast concentration, we counted the number of yeast cells by taking out aliquots of 10 µl from the centre of the fluid layer using a cell counting plate and a vertical microscope . This was done right before . This constituted the suspended yeasts in the fluid due to various mechanisms including bubbles' wake, object's wake and yeast–bubble adhesion. On the other hand, to obtain c.The measurement of total yeast concentration  with a stripette. We were careful that it did not touch or disturb the cell layer. After the removal, we were left with a cell layer along with some fluid. We mixed this up vigorously and then diluted it to do the cell counting. This was done to obtain figure 5. 6.9y = 5 cm. This gives us the concentration gradient as c,d.It was calculated by measuring fluid yeast concentration, through the method described earlier, in upper and lower regions of the fluid. The distance between two points of measurement was Δ. 6.10To estimate glucose concentration, we used 3,5-dinitrosalicylic acid (DNS) reagent, which measures reducing sugars . For thi. 6.11α, in all the three phases, we selected a 2 h duration and measured an increase in total yeast concentration To measure the growth rate . 6.12ξ, we measured the increase in cell concentration t near the flask floor. The consumption parameter was then obtained as ξ remains constant in both phases of its exponential growth . However, as soon as yeasts growth hits the stationary phases of no growth (i.e. 50 h post-yeast inoculation), glucose consumption comes to a halt, thereby turning ξ = 0 g cell−1 s−1. This was observed experimentally too.For estimation of the consumption parameter . 6.13We used one-dimensional finite volume method for solving the governing equation (i.e. equation (3.2)) using freely available computation software SCILAB. We exploited QUICK (Quadratic Upstream Interpolation for Convective Kinematics) scheme for discretization of advection terms and employed second-order central differencing scheme for diffusion term discretization. Time-marching was performed by the explicit Euler method with a time step of 20 s for 80 h.Click here for additional data file.


The ankle brace significantly (p < 0.05) decreased the angular displacement, angular velocity, and angular acceleration of the ankle both without and with the backpack. In conclusion, the ankle brace could restrict ankle motion and significantly increase ground reaction force without the backpack. However, the ankle brace did not significantly influence ground reaction force and still restricted ankle motion with the backpack. Therefore, the ankle brace was more effective in half-squat parachuting landing with the backpack than no-backpack landing.Half-squat parachuting landing is a kind of activity with high impact force. Injuries on lower-extremity joints are common in half-squat parachuting landing and would be increased with a backpack. An ankle brace was used to prevent ankle injuries in landing. However, few quantitative studies reported about the protection of an ankle brace for lower-extremity joints in half-squat parachuting landing with a backpack. This study focused on evaluating the protective effects of an ankle brace in half-squat parachuting landing with a backpack. Seven male participants landed from 120 cm with a backpack and an ankle brace. Each participant performed three landing trials on every experimental condition. Kinetics and kinematics of the hip, knee, and ankle were analyzed. It was found that the ankle brace did not significantly affect the ground reaction force with backpack but increased the ground reaction force from 14.7 ± 2.0 bodyweight to 16.2 ± 1.9 bodyweight ( Parachuting landing, one kind of landing with high impact force, was common in military and civil activities. Injuries, such as ankle fracture, ankle sprains, and hip contusions, occurred on lower-extremity joints  due to the high impact force on the lower extremity . Half-sqAn ankle brace was developed to decrease injuries in parachuting landing by restricting the excessive motion of the ankle . It was The ankle brace, on one hand, could restrict ankle motion, decrease the angular displacement and the angular velocity of the ankle, and increase stabilization of the ankle in the half-squat parachuting landing . HoweverIn our previous study, the multi-joint protection for the hip, knee, and ankle in the half-squat parachuting landing was found to be provided by a knee brace, which was another type of protective device . For motA backpack, containing the necessities for military missions and living, was carried in parachuting landing, which would increase injuries by approximate 160% . Ankle sThe purpose of this study was to evaluate the protective effects of an ankle brace on lower-extremity joints in half-squat parachuting landing with a backpack by analyzing kinetics and kinematics of the hip, knee, and ankle. Participants would be recruited for the experiment. The hypothesis was that the ankle brace could protect the lower-extremity joints in the half-squat parachuting landing with the backpack.Seven participants  were recruited. The studies involving human participants were reviewed and approved by the Science and Ethics Committee of School of Biological Science and Medical Engineering in Beihang University, China (no. BM201900121). The participants provided their written informed consent to participate in this study.Thirteen passive infrared reflex markers were attached to the bony landmarks of the participant: the left anterior superior iliac spines, the left posterior superior iliac spines, the right anterior superior iliac spines, the right posterior superior iliac spines, the greater trochanter, the lateral knee, the medial knee, the lateral ankle, the medial ankle, the heel, the fifth metatarsal, the second toe, and the first toe, as shown in A 5 kg sports vest was regarded as the backpack because the markers on the pelvis could be conveniently attached and traded. The ankle brace in this study was made of terylene, spandex, and elastic fiber, as shown in The experimental conditions were group 1: no backpack + no brace (without the backpack and without the ankle brace), group 2: backpack + no brace (with the backpack and without the ankle brace), group 3: no backpack+ ankle brace (without the backpack and with the ankle brace), and group 4: backpack+ ankle brace (with the backpack and with the ankle brace). The three-dimensional displacements of the markers were measured by using a three-dimensional motion capture system  at the sample frequency of 200 Hz. The ground reaction force was measured by using the force plate  at the sample frequency of 1,600 Hz. All participants had already trained the half-squat parachuting landing technique before trials. Before landing, the participant stood straightly and unbent two arms with the palms toward the body to get the static calibration of the markers. Then, the participant dropped from a 120 cm high platform and landed on the force plate, as shown in A multi-rigid-body model including the pelvis and right lower-extremity was developed based on the static calibration of markers by using the Visual3D software . The center of the hip was estimated based on the markers on the left anterior superior iliac spines, the left posterior superior iliac spines, the right anterior superior iliac spines, the right posterior superior iliac spines, and the greater trochanter. The center of the knee was defined as the middle point between the markers on the lateral and medial knee. The center of the ankle was defined as the middle point between the markers on the lateral and medial ankle.The angular displacement and the joint moment of the hip, knee, and ankle on sagittal plane and frontal plane were computed by using the Visual3D software. The angular velocity and angular acceleration of the hip, knee, and ankle on sagittal plane and frontal plane were computed based on the angular displacement and the numerical differential formula. The joint energy absorption was computed by integrating the joint moment over the angular displacement. The ground reaction force, the joint moment, and the joint energy absorption were normalized with BW.p < 0.05. The study power was analyzed using G*Power based on the data of angular displacement of the knee, assuming an alpha of 0.05. The statistical power (1-beta) was equal to 1.0, larger than 0.8. The Kolmogorov–Smirnov method was used to test that all outcomes conformed to normal distribution. The one-way repeated measures ANOVA was used to test the repeatability of the three trials based on the angular displacement of the hip, knee, and ankle on sagittal plane and the peak ground reaction force in the four experimental groups, and there was a good repeatability of the three trials (p > 0.05).The peak vertical ground reaction force and the joint moment, the joint energy absorption, the angular displacement, the angular velocity, and the angular acceleration of the hip, knee, and ankle on sagittal plane and frontal plane were analyzed by using ANOVA by SPSS v19.0 software. The level of significant difference was p = 0.012), as shown in p = 0.017) by the ankle brace in the landing without the backpack. There was a significant difference in the interaction (p = 0.009) between the backpack and the ankle brace in the peak vertical ground reaction force.The peak vertical ground reaction force was increased by the backpack from 14.7 ± 2.0 to 16.0 ± 1.6BW (p > 0.05) with the backpack as well as the ankle brace, as shown in p > 0.05) between the backpack and the ankle brace in the joint moment of the hip, knee, and ankle on sagittal plane and frontal plane.The joint moment of the hip, knee, and ankle on sagittal plane and frontal plane was not significantly affected (p = 0.037), 0.49 ± 0.07 BW (p = 0.001) and 0.11 ± 0.02 BW (p = 0.045) respectively. The joint energy absorption of ankle was decreased by the ankle brace from 0.10 ± 0.02 BW to 0.08 ± 0.03 BW (p = 0.037) without the backpack, and was decreased from 0.11 ± 0.02 BW to 0.09 ± 0.02 BW (p < 0.001) with the backpack. There was no significant difference in the interaction (p > 0.05) between the backpack and the ankle brace in the joint energy absorption of the hip, knee, and ankle.As shown in p = 0.006), 110.1 ± 9.3° (p = 0.009) and 53.8 ± 5.1° (p < 0.001) respectively by the backpack. The angular displacement of ankle on sagittal plane was decreased from 45.2 ± 7.8° to 36.0 ± 10.9° (p = 0.005) by the ankle brace without the backpack, and was decreased from 53.8 ± 5.1° to 48.0 ± 5.5° (p = 0.001) by the ankle brace with the backpack. There was no significant difference in the interaction (p > 0.05) between the backpack and the ankle brace in the angular displacement of the hip, knee, and ankle on sagittal plane.As shown in p = 0.037), 855.9 ± 65.3°/s (p = 0.022), and 594.0 ± 99.5°/s (p = 0.014), respectively, by the backpack. The angular velocity of the ankle on sagittal plane was decreased from 508.7 ± 105.9°/s to 332.0 ± 104.2°/s (p < 0.001) by the ankle brace without the backpack and was decreased from 594.0 ± 99.5°/s to 471.3 ± 110.4°/s (p = 0.001) by the ankle brace with the backpack. There were no significant differences in the interaction (p > 0.05) between the backpack and the ankle brace in the angular velocity of the hip, knee, and ankle on sagittal plane.As shown in 2, 12,791.7 ± 1,266.5°/s2, and 10,813.6 ± 2,179.3°/s2 to 9,810.8 ± 1,478.1°/s2 (p = 0.003), 14,025.1 ± 1,979.6°/s2 (p = 0.021), and 13,099.7 ± 2,280.0°/s2 (p = 0.002), respectively, by the backpack. The angular acceleration of the ankle on sagittal plane was decreased from 10,813.6 ± 2,179.3°/s2 to 7,764.4 ± 2,542.5°/s2 (p < 0.001) by the ankle brace without the backpack and was decreased from 13,099.7 ± 2,280.0°/s2 to 11,077.1 ± 1,703.4°/s2 (p = 0.002) by the ankle brace with the backpack. There were no significant differences in the interaction (p > 0.05) between the backpack and the ankle brace in the angular acceleration of the hip, knee, and ankle on sagittal plane.As shown in p = 0.017) by the ankle brace without the backpack and was decreased from 14.5 ± 4.7° to 11.5 ± 3.5° (p = 0.026) by the ankle brace with the backpack. There were no significant differences in the interaction (p > 0.05) between the backpack and the ankle brace in the angular displacement of the hip, knee, and ankle on frontal plane.As shown in p = 0.005) by the ankle brace without the backpack and was decreased from 180.5 ± 56.1°/s to 151.7 ± 30.1°/s (p = 0.043) by the ankle brace with the backpack. There were no significant differences in the interaction (p > 0.05) between the backpack and the ankle brace in the angular velocity of the hip, knee, and ankle on frontal plane.As shown in 2 to 3,075.4 ± 972.4°/s2 (p = 0.009) by the ankle brace without the backpack and was decreased from 3,997.8 ± 670.6°/s2 to 3,515.3 ± 738.8°/s2 (p = 0.032) by the ankle brace with the backpack. There were no significant differences in the interaction (p > 0.05) between the backpack and the ankle brace in the angular acceleration of the hip, knee, and ankle on frontal plane.As shown in In this study, kinetic and kinematic parameters of the hip, knee, and ankle were analyzed to evaluate the protective effects of an ankle brace for the lower-extremity joints in the half-squat parachuting landing with a backpack. It was found that the ankle brace could provide more effective protection in the half-squat parachuting landing with the backpack than that without the backpack.The peak vertical ground reaction force was increased by the backpack, as shown in The joint moment of the hip, knee, and ankle was not significantly affected by the backpack, as shown in The peak vertical ground reaction force was increased with the ankle brace in the landing without the backpack , possiblThe joint moments of the hip, knee, and ankle were not significantly influenced by the ankle brace in the landing both without and with the backpack. This outcome was similar to that in the drop landing . The angThe motion of the ankle on frontal plane was another factor of ankle sprain injury . InjurieIn this study, the ankle brace did not significantly influence the ground reaction force with the backpack but increased the ground reaction force without the backpack. In our previous study, the multi-joint protection of a knee brace for the hip, knee, and ankle was provided in the half-squat parachuting landing without the backpack, but the knee brace could only protect the knee in the half-squat parachuting landing with the backpack . DiffereOne limitation of this study was that the sample size of the participants was limited due to the cost. Each participant performed three trials to enlarge the sample size. The G*Power software was used to analyze the study power of the sample size. Only male participants were recruited in this experiment because the injury risk of male paratroopers was higher than that of females . AnotherThe ankle brace could restrict ankle motion and protect the ankle in the half-squat parachuting landing both without and with the backpack. The ankle brace significantly increased the ground reaction force, which thus decreased the protective effects of the ankle brace. The ankle brace did not significantly increase the ground reaction force but could still maintain the protective effects with a backpack. The ankle brace could provide more effective protection for the lower-extremity joints in the half-squat parachuting landing with a backpack than no-backpack landing.


Following the publication of this article , the autIn reviewing this issue, additional concerns were raised regarding the results presented in Figs 1, 2, 3, 4, and 5. Specifically,Data are repeated across figure panels in Figs 1–4: Fig 1A and 2E report the same Rbm46 and Gapdh RT-PCR results; Fig 1A and 4A report the same Rbm46 and Beta-Actin western blot results; and Fig 3A and 3F report the same Rbm46 and Gapdh RT-PCR results. In each case, the first author noted that the repeated panels represent the same experiment but different terminology was used in figure labels.The tumour sizes reported in Figs 2 and 3 exceed sizes commonly accepted for mouse tumour studies. In response to the journal’s queries the first author clarified that whereas the Methods section mentions tumour measurements  tumour size data were not collected over the course of the experiment but instead tumour weight data was only collected after animals had been euthanised.In Fig 5C, there appear to be abrupt discontinuities around the positive signal areas in the PABPC1 and Merge panels when levels are adjusted. The first author stated that no adjustments were made to the panels presented in Fig 5C, but the surrounding (background) areas of the published panels do not match the underlying data provided for the PABPC1 and Merge panels. This does not appear to impact the overall results reported in the figure.The first author has provided individual level data for the results presented in the study but indicated that the raw uncropped blots underlying the published RT-PCR and western blot results are no longer available.PLOS ONE Editors retract this article.The authorship issues discussed above indicate that this submission did not comply with the PLOS Authorship policy. In light of this issue, the concerns regarding the reported mouse tumour sizes, and the concern about data reporting in Fig 5C, the LL and CW agreed with the retraction. LZ, YC, and SZ did not comment on the editorial decision. LL apologises for the issues with the published article.


Parenteral products must be compounded using an aseptic technique to ensure sterility of the medicine. We compared the effect of three clinical environments as compounding areas as well as different aseptic techniques on the sterility of the compounded parenteral product. Clinical pharmacists and pediatric nurses compounded 220 samples in total in three clinical environments: a patient room, a medicine room and biological safety cabinet. The study combined four methods: observation, environmental monitoring (settle plates), monitoring of personnel (finger dab plates) and sterility testing (membrane filtration). Of the compounded samples, 99% were sterile and no significant differences emerged between the clinical environments. Based on the settle plates, the biological safety cabinet was the only area that fulfilled the requirements for eliminating microbial contamination. Most of the steps on the observation form for aseptic techniques were followed. All participants disinfected their hands, wore gloves and disinfected the septum of the vial. Non-contaminated finger dab plates were mostly detected after compounding in the biological safety cabinet. Aseptic techniques were followed relatively well in all environments. However, these results emphasize the importance of good aseptic techniques and support the recommendation of compounding parenteral products in biological safety cabinets in clinical environments. Parenteral products are sterile products that are administered as an injection, infusion or implantation . These mErrors in aseptic techniques might lead to contamination of the compounded product; however, there are large variations in reported error rates 4.0–98.7%) of aseptic techniques .7% of as,11. The Most parenteral products must be compounded  before administration. According to the Finnish Medicines Agency (Fimea), compounding of sterile products should be done in a hospital pharmacy whenever possible . Fimea fPrevious studies have focused on comparing the contamination rates of products compounded in clinical or pharmaceutical environments ,14,15,16The aim of this study was to compare the effect of three environments for compounding of parenteral products in pediatric wards, namely, the patient’s room (PR), medicine room (MR) and biological safety cabinet (BSC), on the contamination rate of the compounded product. Another objective was to determine how well aseptic techniques are followed during compounding of parenteral products in hospital wards.The study was conducted in two separate pediatric wards at HUS Helsinki University Hospital between March and May 2019. One of the wards provides intensive care and the other emergency care. Altogether 12 volunteers, one clinical pharmacist and five nurses from each ward were recruited to the study by nurse managers or clinical pharmacists. All participants were experienced in medicine compounding. Three environments were used for compounding in the wards: PR, MR and BSC. In the PR, a separate cart or small desk served as the compounding area. Compounding was done in the empty PR to prevent any disturbance to patients or their medical care. In the MR, compounding was performed on a desk, and other nurses could be present in the room simultaneously. There is no significant difference in the air flow between the PR and MR. The BSC was situated either in the MR or in a separate room with an entrance from the MR. The following BSCs were used: Kojair SL-66 Silver, 2009 (ward 1) and BioWizard Silver SL-170 C Blue Series, 2016 (ward 2). Ward 2 was recently renovated, hence the BSC is newer in ward 2.The compounding of test samples was designed to simulate the procedure of dissolving, diluting and dispensing commonly used cefuroxime for intravenous infusion. The test samples were prepared by adding 5 mL of sterile water for injections  to a vial containing sterile sodium chloride (NaCl) powder . After dissolving NaCl, the solution was drawn into two syringes , 2 mL in each, where it was further diluted to 10 mL with sterile 0.9% NaCl solution . Detailed instructions for the compounding are provided in A total of 220 samples were collected during the study . Each paThe study combined four different methods: observation, environmental monitoring, monitoring of personnel and sterility testing .® Microbiology Pump  and MicroFunnel™ filters  with a membrane pore size of 0.2 µm. After filtration, the membrane was cut into two halves. One half was transferred into a thioglycolate broth  and the other half into a tryptic soy broth . Both media were incubated for 14 days, TSB at 25 °C and thioglycolate broth at 35 °C, after which they were visually examined for turbidity. If turbidity was detected, 100 µL of five serial dilutions of the media were plated on a tryptic soy agar (TSA) plate  and incubated at 35 °C for 5 days. The plate was visually examined after incubation and the number of colony-forming units (CFUs) was calculated. A stock solution of each phenotypically different colony was prepared in order to identify the contaminants using an OmniLog ID System . The stock solutions were stored at −80 °C prior to analyses with the OmniLog ID System [Membrane filtration was used as a sterility test for the compounded samples. One duplicate was filtrated within 4 h of compounding to simulate a situation where the product is administered immediately after compounding. The second duplicate was filtrated after 24 hours’ storage to simulate a situation where the compounded product is stored in a refrigerator for 24 h in the wards prior to administration. The samples were stored at 4 °C before membrane filtration. Membrane filtration was performed in an aseptic laboratory in a laminar flow hood cabinet using a SentinoD System .® Excel was used to collect and analyze the data. IBM® SPSS® Statistics 25  was used for statistical analyses (ANOVA). Observations were collected from the structured observation forms , and the rest of the settle plates from the BSC fulfilled the requirements for grade C (50 CFU/4 h) . In addiAccording to the results obtained from finger dab plates, the least number of contaminated gloves was seen after compounding in the BSC . HoweverComparison of the results of finger dab plates  with recOf the 220 samples, 5 were excluded from the results because both the compounded samples and the negative controls were contaminated. All excluded samples were filtrated simultaneously, which indicates that they were contaminated during sterility testing. Almost all (99%) of the compounded samples were sterile, and no significant differences were found in the contamination rates between the environments. One of the contaminated samples was compounded in the PR and filtrated after 24 h of storage. The other contaminated sample was compounded in the BSC and filtrated within 4 h of compounding. Participant 1, who compounded the contaminated sample in the PR, completed all steps included on the observation form. The finger dab plates were non-contaminated  and the Dietzia maris and Corynebacterium mycetoides. Contaminants from the BSC sample were identified as Paenibacillus castaneae and Staphylococcus capitis.Both contaminated samples contained two phenotypically different colonies each –Table S3Even though aseptic techniques were followed relatively well in this study , almost The results of environmental monitoring varied markedly between participants , which mn = 27 studies and 1.1–20.7%, n = 13 studies). The contamination rate for the compounded samples in this study is lower than the mean results of two systematic reviews (0.9% vs. 3.7% and 7.5%) ,16. BothNo significant differences emerged in the contamination rates of the compounded samples between the three different environments. However, the results from the environmental monitoring  showed tDiezia maris and Corynebacterium mycetoides). There are three case reports of infections, namely bacteraemia, aortitis and hip prosthesis infection, caused by Diezia maris [Corynebacterium mycetoides were found. The other contaminated sample from the BSC included Gram-variable bacteria (Paenibacillus castaneae) and Gram-positive bacteria (Staphylococcus capitis) [Paenibacillus castaneae infections were found. However, several case reports described infections caused by Staphylococcus capitis, such as septicaemia and septic meningitis, even in preterm infants [The contaminated sample from the PR included Gram-positive bacteria  . No case infants ,29,30.Participants in this study were volunteers, therefore, they might have been more interested in adhering to aseptic techniques than average workers. Participants could also have been working more carefully than usual since they were aware of the study and observation. Participants at ward 1 were not familiar with using the BSC prior to this study. Despite a training session on use of the BSC given by a clinical pharmacist, the lack of experience might have caused deficiencies in aseptic techniques, affecting the results. In addition, the compounding experience between the participants might be different and could affect the results. PR samples were compounded in empty rooms, which might have resulted in lower numbers of microbes on settle plates than in PR with patients present.Although our results are similar to those of previous studies, we did not obtain significant differences in contamination rates of the compounded samples in the different environments. A larger number of compounded samples might have revealed significant differences in the contamination rates. In addition, the compounded samples might have been contaminated during membrane filtration. More similar studies are needed to verify these results.To ensure patient safety in pediatric wards, high-quality compounding is necessary. Aseptic techniques were mostly sufficiently followed in all three study environments; however, there is room for improvement and additional training is recommended to improve the compliance. The compounding environment had a larger impact on microbial growth on the settle plates than the aseptic technique applied. The BSC is the most suitable environment for compounding of parenteral products in a clinical environment since the BSC fulfils the European Union Good Manufacturing Practices (EU GMP) guidelines for microbial monitoring to the greatest extent .


This disease is characterized by a massive pancreatic release of pro-inflammatory cytokines that causes a systemic inflammatory response syndrome and a profound intravascular fluid loss. This leads to a mixed hypovolemic and distributive shock and ultimately to multiorgan failure. Aggressive fluid resuscitation is traditionally considered the mainstay treatment of AP. In fact, all available guidelines underline the importance of fluid therapy, particularly in the first 24–48 h after disease onset. However, there is currently no consensus neither about the type, nor about the optimal fluid rate, total volume, or goal of fluid administration. In general, a starting fluid rate of 5–10 ml/kg/h of Ringer’s lactate solution for the first 24 h has been recommended. Fluid administration should be aggressive in the first hours, and continued only for the appropriate time frame, being usually discontinued, or significantly reduced after the first 24–48 h after admission. Close clinical and hemodynamic monitoring along with the definition of clear resuscitation goals are fundamental. Generally accepted targets are urinary output, reversal of tachycardia and hypotension, and improvement of laboratory markers. However, the usefulness of different endpoints to guide fluid therapy is highly debated. The importance of close monitoring of fluid infusion and balance is acknowledged by most available guidelines to avoid the deleterious effect of fluid overload. Fluid therapy should be carefully tailored in patients with severe AP, as for other conditions frequently managed in the ICU requiring large fluid amounts, such as septic shock and burn injury. A combination of both noninvasive clinical and invasive hemodynamic parameters, and laboratory markers should guide clinicians in the early phase of severe AP to meet organ perfusion requirements with the proper administration of fluids while avoiding fluid overload. In this narrative review the most recent evidence about fluid therapy in severe AP is discussed and an operative algorithm for fluid administration based on an individualized approach is proposed.Patients with acute pancreatitis (AP) often require ICU admission, especially when signs of multiorgan failure are present, a condition that defines AP as  Acute pancreatitis (AP) is an acute inflammatory disease of the pancreas and is among the most common gastrointestinal disorders requiring hospitalization. About 80% of patients with AP have a mild, self-limiting form that needs only brief treatment in a non-critical setting. However, 15–20% of AP episodes are moderately severe or severe, potentially leading to multi-organ failure (MOF), and are burdened by a 20–40% mortality rate ) and strong anions ([Cl-]). According to Stewart’s acid–base approach, SID is an independent variable affecting the pH of a biological solution [+ and Cl− have the same concentration, and its net effect is, therefore, always acidifying. On the other hand, the infusional SID of balanced crystalloids ranges between 28 and 55 mEq/L with a reduced effect on plasma acid–base [Normal saline (0.9% sodium chloride solution) and balanced crystalloid solutions (such as Ringer’s lactate) are broadly used fluids. Balanced solutions are more similar to extracellular fluid as they contain some organic anions (buffers), which are metabolized once delivered to the patient and allow to lower the chloride concentration of the fluid. Different crystalloids have different strong ion differences (SID), i.esolution , 91. Norsolution . The SIDsolution , 86. Norcid–base .Ringer’s lactate solution (RL), a slightly hypotonic, balanced crystalloid, has been compared to NaCl 0.9% for fluid resuscitation in a small RCT in patients with AP . In thisThese findings might be explained by a possible immunomodulatory, anti-inflammatory, and organ-protective effect of lactate, but also to a detrimental effect of high chloride concentrations . Indeed,Colloids are solutions based on semi-synthetic or plasma-derived molecules dissolved in crystalloids. Human albumin, starches, gelatines, and dextrans are the colloids used in clinical practice. In theory, these molecules are large enough to be retained by semi-permeable membranes and should exert higher colloidal-osmotic pressures than crystalloids. Their putative advantage is the achievement of higher volume expansions with less infused volume and the longer persistence in the intravascular space, conceptually leading to less edema formation and better hemodynamic stability , 84. HowIn the specific context of AP, experiments conducted in animals suggest that resuscitation with dextrans could be superior to crystalloids, possibly due to improved pancreatic perfusion , 105. InIt is, therefore, clear that no conclusive evidence exists about the ideal fluid in SAP and guidelines do not provide a definitive indication, given the moderate quality of the available evidence , 110. HoRecent data support the importance of a tailored and individualized fluid therapy in the context of SAP requiring ICU admission . As descClinical parameters that are commonly and easily monitored are MAP, HR, and UO. A high HR and/or a low MAP and UO can be indicative of low circulating blood volume, oxygen delivery, and impaired end-organ perfusion . An HR <Invasive hemodynamic parameters, such as those obtained from a central line catheter or from the arterial pulse contour analysis, are useful to assess hypovolemia and fluid responsiveness. Static indices of cardiac preload like central venous pressure (CVP) are still used in common practice, though their use is highly debated. CVP values might be useful as a safety limit to avoid fluid overload in the setting of right-heart failure. Calibrated hemodynamic monitoring systems, such as PiCCO , are based on transpulmonary thermodilution. Such systems are commonly available in the ICU and have been investigated also in the specific setting of SAP with promising results –122, shoLactate levels and central venous saturation are indirect markers of organ perfusion and oxygen delivery . InadequClinical endpoints that could guide fluid resuscitation in patients with SAP can be classified in three groups: noninvasive clinical parameters (1), invasive hemodynamic parameters (2), and laboratory markers (3).Resuscitation), the patient might be in hypovolemic shock and the physician must provide an early, adequate goal-directed fluid management with an abundant fluid infusion. A positive fluid balance is inevitable and tolerated to achieve adequate perfusion. In the Optimization phase (phase 2), although still hypovolemic, patients with SAP present a more compensated shock. The individual fluid requirement must be regularly assessed. The goal is to maintain adequate tissue oxygenation to limit organ damage and to maintain a neutral fluid balance to avoid fluid overload. Intra-abdominal pressure measurement has been advocated in patients with abdominal problems, to monitor the possible development of abdominal compartment syndrome [Stabilization (phase 3) evolves over the following days and signs of circulatory shock are absent. Fluids are needed only to replenish ongoing losses. Finally, the Evacuation (phase 4) starts with spontaneous evacuation (the “flow” phase) when the acute insult resolves. When evacuation is not spontaneous, a strategy of active fluid removal, using diuretics, might be pursued [Resuscitation and Optimization phases. In both cases, an individualized approach for fluids administration is advocated.Four distinct phases of fluid resuscitation for critically ill patients have been recently proposed and conceptualized through the R.O.S.E. acronym , which could also be adapted for patients with SAP . In the syndrome , 125. Th pursued . If thisA single clinical marker alone unlikely reflects the overall volume status and the assessment of multiple parameters simultaneously is considered more reliable . The patOver the first Resuscitation phase and the following Optimization phase, the use of vasopressors (like norepinephrine) could be considered . During Three main questions are still not completely answered about fluid therapy during SAP. First, the optimal rate and the extent of fluid administration in the early phase of the disease. Second, the most accurate clinical and laboratory endpoint to guide fluid resuscitation. Third, the best fluid that, administered in large volume, could guarantee the highest efficacy and safety .WATERFALL is a very recently published RCT . The stuOther ongoing RCTs are mainly focused on the comparison between normal saline and other crystalloids. Farrell et al. plan to enroll 80 pediatric patients with acute pancreatitis receiving either RL or NS to assess inflammatory markers and SIRS status at 24 and 48 h . Poropat et al. aim to enroll 276 adult patients with acute pancreatitis to receive either Plasmalyte or normal saline as an initial bolus of 10 ml/kg in the first 60 min after randomization, and then at a rate of 2 ml/kg for the next 72 h . The primary endpoint of the study is the incidence of SIRS.Fluid therapy is a key treatment of patients admitted to the ICU with severe forms of acute pancreatitis. A broadly accepted early and aggressive fluid therapy has been recently questioned due to potential harm and not definitive efficacy in clinical trials. Since there is a possible risk of under-resuscitation when a fixed infusion rate is used, a more tailored approach is warranted. It should be based on a careful assessment of the patient’s volume status, with enhanced volume expansion in the first hours of admission for the most severe cases. Crystalloids, and in particular RL, are the fluids of choice, with a suggested initial fluid rate usually ranging between 5–10 ml/kg/h. Then, if at any time during the first 24 h resuscitation goals are met, it is reasonable to reduce fluid rate to 2–3 ml/kg/h. Patients with SAP should be strictly monitored in the ICU, where advanced hemodynamic monitoring systems are available to guide clinicians.


Pseudomonas aeruginosa isolates. New BL/BLIs, such as ceftazidime-avibactam (CAZ-AVI), ceftolozane-tazobactam (C/T), and imipenem-relebactam (IMI-REL), are active against most P. aeruginosa isolates from US hospitals, but the ability of these agents to induce resistance have not been explored. We subjected 8 P. aeruginosa isolates, including ATCC 27853 and 7 clinical isolates, to a 10-day serial passage with 6 antipseudomonal agents to evaluate resistance levels and mechanisms in terminal mutant strains.The acquisition of mutations is the main driver of β-lactam resistance in Fold change in MIC results from parent isolate to terminal mutantSerial passaging was performed in broth microdilution (BMD) for CAZ-AVI, IMI-REL, C/T, meropenem (MEM), cefepime (FEP), and piperacillin-tazobactam (P/T). The MIC of the terminal mutants was determined after 2X passaging on drug-free agar. Parent strains and terminal mutants were subjected to short-read whole genome sequencing (WGS) at 100X coverage. Parent isolates were sequenced using long-read WGS and the data was combined with short-reading sequencing for single nucleotide polymorphism (SNP) analysis.nalD regulator alteration, and 1 of these had a clpA chaperone missense substitution. FEP terminal mutants exhibited alterations in ampD, mexB, and the TetR family transcriptional regulator AmrR. C/T mutants had ampG and ftsI missense alterations. MEM mutants had nalC, ftsI, and phoP missense alterations. Mutations in merR, nalC, and ampD were observed in the P/T terminal mutants. Among 2 IMI-REL terminal mutants displaying a SNP alteration, 1 displayed a nonsense mutation in pilF, a pilus forming protein. Many terminal mutants displayed alterations in genes not commonly associated to β-lactam resistance.Overall, IMI-REL (1- to 4-fold) and CAZ-AVI (2- to 8-fold) displayed lower fold increases in MIC values when compared to other agents tested . Of the CAZ-AVI terminal mutants, 3 displayed a MEM, FEP, and P/T terminal mutants displayed high MIC values compared to those obtained after exposure to C/T, CAZ-AVI, and IMI-REL. This data might indicate a benefit of using these newer agents to prevent the emergence of high-level resistance.Mariana Castanheira, PhD, AbbVie: Grant/Research Support|Cidara: Grant/Research Support|GSK: Grant/Research Support|Melinta: Grant/Research Support|Pfizer: Grant/Research Support|Shionogi: Grant/Research Support Jill Lindley, BS, AbbVie: Grant/Research Support Timothy Doyle, MS, AbbVie: Grant/Research Support John H. Kimbrough, PhD, AbbVie: Grant/Research Support|GSK: Grant/Research Support Jessica Ewald, PhD, AbbVie: Grant/Research Support Helio S. Sader, MD, PhD, AbbVie: Grant/Research Support|Cidara: Grant/Research Support|Melinta: Grant/Research Support|Nabriva Therapeutics: Grant/Research Support|Pfizer: Grant/Research Support.


Page 19: In the Acknowledgments section, a grant number for the National Science Foundation (NSF) was inadvertently omitted. The correct acknowledgment for NSF funding should include two grant numbers, CBET-1435661 and CBET-1803055.Volume 6, no. 5, e00906-21, 2021,