Relative Mass Change Research Articles

Relationship between low relative muscle mass and aortic regional morphological changes in adults underwent contrast CT scans for cancer diagnostics

ObjectivesLow muscle mass is related to cardiovascular risk factors. This study aimed to investigate whether relative low muscle mass is related to the diameter and tortuosity of the aorta. MethodsWe performed a cross-sectional study of 208 adults without known cardiovascular disease who underwent Computed Tomography (CT) enhanced scan between 2020 and 2021. Skeletal muscle index (SMI) was estimated. The morphology of the aorta was measured by diameter and tortuosity using CT. We assessed the relationship between SMI and diameter and tortuosity of the aorta using Spearman correlation analysis and univariate and multivariate-adjusted regression models. ResultsOf all -individuals, 124 (59.6%) were male. The average age was 60.13 ± 16.33 years old. SMI was inversely associated with the diameter and tortuosity of the aorta (p < 0.05). Specifically, in a multivariable-adjusted model adjusting for potential confounders, a one-unit increase in the SMI was associated with a -13.56mm(95% confidence intervals (CI): −18.16 to −8.96, p < 0.001), −7.93 mm (95% CI: −10.85 to −5.02, p < 0.001), −8.01 mm (95% CI: −11.30 to −4.73, p < 0.001), −5.16 mm (95% CI: −7.57 to −2.75, p < 0.001) and −2.73 mm (95% CI: −5.18 to −0.27, p = 0.031) increase in L1-L5 diameter respectively, a −0.89 (95% CI: −1.14 to −0.64, p < 0.001) increase in the aorta tortuosity, a −0.48 (95% CI: −0.59 to −0.36, p < 0.001) increase in the descending thoracic aorta tortuosity, and a −0.44 (95% CI: −0.52 to −0.35, p < 0.001) increase in the abdominal aorta tortuosity. ConclusionsRelative muscle mass was negatively associated with the diameter and tortuosity of the aorta, suggesting muscle mass maintenance may play a role in preventing aortic morphological changes.

Chemical and thermal stability of electrospinned polyvinylidene fluoride/graphene composite membranes

The effect of graphene content, spinning flow rate, and distance on the chemical and thermal stability of electrospinned polyvinylidene fluoride (PVDF)/graphene composite membranes was systematically investigated. Long-duration soaking experiments by three typical solution media, diluted hydrochloric acid, dimethyl sulfoxide, and mixed-solution of lithium hexafluorophosphate/methyl ethyl carbonate, were used to evaluate the chemical stability of the selected samples. The relevant results of relative mass change rate all indicate that the chemical stability of PVDF composite materials increases with increasing graphene content as well as flow rate or decreasing distance. Moreover, there is a clear consistency between thermal stability and chemical stability. The results of the thermal shrinkage rate evidence that the thermal stability of the samples could be enhanced by increasing graphene content, flow rate, and decreasing spinning distance.

Restoring skeletal muscle mass as an independent determinant of liver fat deposition improvement in MAFLD

AimsCross-sectional studies have demonstrated the association of skeletal muscle mass with metabolic-associated fatty liver disease (MAFLD), while longitudinal data are scarce. We aimed to explore the impact of changes in relative skeletal muscle mass on the MAFLD treatment response.MethodsMAFLD patients undergoing magnetic resonance imaging-based proton density fat fraction for liver fat content (LFC) assessments and bioelectrical impedance analysis before and after treatment (orlistat, meal replacement, lifestyle modifications) were enrolled. Appendicular muscle mass (ASM) was adjusted by weight (ASM/W).ResultsOverall, 256 participants were recruited and divided into two groups: with an ASM/W increase (n=166) and without an ASM/W increase (n=90). There was a great reduction in LFC in the group with an ASM/W increase (16.9% versus 8.2%, P < 0.001). However, the change in LFC in the group without an ASM/W increase showed no significant difference (12.5% versus 15.0%, P > 0.05). △ASM/W Follow-up-Baseline [odds ratio (OR)=1.48, 95% confidence interval (CI) 1.05-2.07, P = 0.024] and △total fat mass (OR=1.45, 95% CI 1.12-1.87, P = 0.004) were independent predictors for steatosis improvement (relative reduction of LFC ≥ 30%). The subgroup analysis showed that, despite without weight loss, decrease in HOMA-IR (OR=6.21, 95% CI 1.28-30.13, P=0.023), △total fat mass Baseline -Follow-up (OR=3.48, 95% CI 1.95-6.21, P <0.001 and △ASM/W Follow-up-Baseline (OR=2.13, 95% CI 1.12-4.05, P=0.022) independently predicted steatosis improvement.ConclusionsASM/W increase and loss of total fat mass benefit the resolution of liver steatosis, independent of weight loss for MAFLD.

Ex Vivo Drug Screening Assay with Artificial Membranes: Characterizing Cholesterol Desorbing Competencies of Beta-Cyclodextrins.

Despite advancements in contemporary therapies, cardiovascular disease from atherosclerosis remains a leading cause of mortality worldwide. Supported lipid bilayers (SLBs) are membrane interfaces that can be constructed with varying lipid compositions. Herein, we use a solvent-assisted lipid bilayer (SALB) construction method to build SLB membranes with varying cholesterol compositions to create a lipid-sterol interface atop a piezoelectric sensor. These cholesterol-laden SLBs were utilized to investigate the mechanisms of various cholesterol-lowering drug molecules. Within a flow-cell, membranes with varying cholesterol content were exposed to cyclodextrins 2-hydroxypropyl-beta-cyclodextrin (HPβCD) and methyl-beta-cyclodextrin (MβCD). Quartz-crystal microgravimetry with dissipation monitoring (QCM-D) enabled the collection of in vitro, real-time changes in relative areal mass and dissipation. We define the cholesterol desorbing competency of a cyclodextrin species via measures of the rate of cholesterol removal, the rate of the transfer of membrane-bound cholesterol to drug-complexed cholesterol, and the binding strength of the drug to the cholesterol-ladened membrane. Desorption data revealed distinct cholesterol removal kinetics for each cyclodextrin while also supporting a model for the lipid-cholesterol-drug interface. We report that MβCD removes a quantity of cholesterol 1.61 times greater, with a speed 2.12 times greater, binding affinity to DOPC lipid interfaces 1.97 times greater, and rate of internal cholesterol transfer 3.41 times greater than HPβCD.

Determination of Variation of Mass with Gravity

The paper demonstrates that the theory of mass and gravity in the existing normally acknowledged version of theory of gravitational red-shift is completely erroneous. What makes it erroneous is that the frequency of particle in a gravitational field is considered to change depending on its location while mass of particle is treated as constant parameter. This paper predicts that a body in a gravitational field of escape velocity Ve will be more massive by a factor of 1 + (Ve2/C2) , where C is the speed of light, as compared to mass of a similar body outside the field. It manifests that mass of a body measured at earth surface is different than actual mass because of the influence of gravity. If m' and m denote mass of body within and beyond the gravitational field respectively, then the mass (m') measured at earth surface as compared to actual mass (m) is given by the formula m' = m (1+1.39 × 10-9). It reveals that an actual relative mass change at earth m' - m/m = 1.39 × 10-9) is extremely small, with change measure in nanogram. Based on this postulate of variation of mass with gravity, the correct criteria for a particle to be inside black hole turns out to be m'&gt;2m. Therefore, a gravitational field is a black hole if the mass of a body inside the field will be more than two times of its actual mass. In this highly interesting topic, the particular purpose is to present a succinct and carefully reasoned account of new aspect of gravitational red shift which properly allows to determine the change of mass with gravity.

Dollo meets Bergmann: morphological evolution in secondary aquatic mammals

Secondary transitions to aquatic environments are common among vertebrates, and aquatic lineages display several adaptations to this realm, some of which might make these transitions irreversible. At the same time, discussions about secondary transitions often focus only on the marine realm, comparing fully terrestrial with fully aquatic species. This, however, captures only a fraction of land-to-water transitions, and freshwater and semi-aquatic groups are often neglected in macroevolutionary studies. Here, we use phylogenetic comparative methods to unravel the evolution of different levels of aquatic adaptations across all extant mammals, testing if aquatic adaptations are irreversible and if they are related to relative body mass changes. We found irreversible adaptations consistent with Dollo's Law in lineages that rely strongly on aquatic environments, while weaker adaptations in semi-aquatic lineages, which still allow efficient terrestrial movement, are reversible. In lineages transitioning to aquatic realms, including semi-aquatic ones, we found a consistent trend towards an increased relative body mass and a significant association with a more carnivorous diet. We interpret these patterns as the result of thermoregulation constraints associated with the high thermal conductivity of water leading to body mass increase consistently with Bergmann's rule and to a prevalence of more nutritious diets.

Bone Mass Changes Following Percutaneous Radiofrequency Ablation, Osteoplasty, Reinforcement, and Internal Fixation of Periacetabular Osteolytic Metastases.

The success of orthopedic interventions for periacetabular osteolytic metastases depends on the progression or regression of cancer-induced bone loss. To characterize relative bone mass changes following percutaneous radiofrequency ablation, osteoplasty, cement reinforcement, and internal screw fixation (AORIF). Of 70 patients who underwent AORIF at a single institution, 21 patients (22 periacetabular sites; average follow-up of 18.5 ± 12.3 months) had high-resolution pelvic bone CT scans, with at least one scan within 3 months following their operation (baseline) and a comparative scan at least 6 months post-operatively. In total, 73 CT scans were measured for bone mass changes using Hounsfield Units (HU). A region of interest was defined for the periacetabular area in the coronal, axial, and sagittal reformation planes for all CT scans. For 6-month and 1-year scans, the coronal and sagittal HU were combined to create a weight-bearing HU (wbHU). Three-dimensional volumetric analysis was performed on the baseline and longest available CT scans. Cohort survival was compared to predicted PathFx 3.0 survival. HU increased from baseline post-operative (1.2 ± 1.1 months) to most recent follow-up (20.2 ± 12.1 months) on coronal (124.0 ± 112.3), axial (140.3 ± 153.0), and sagittal (151.9 ± 162.4), p < 0.05. Grayscale volumetric measurements increased by 173.4 ± 166.4 (p < 0.05). AORIF median survival was 27.7 months (6.0 months PathFx3.0 predicted; p < 0.05). At 12 months, patients with >10% increase in wbHU demonstrated superior median survival of 36.5 months (vs. 26.4 months, p < 0.05). Percutaneous stabilization leads to improvements in bone mass and may allow for delays in extensive open reconstruction procedures.

Ethyl cellulose composite membranes containing a 2D material (MoS2) and helical carbon nanotubes for efficient solar steam generation and desalination

With the increasing water consumption, water evaporators have been investigated for clean water production. Herein, the fabrication of electrospun composite membrane evaporators based on ethyl cellulose (EC), with the incorporation of light-absorption enhancers 2D MoS2 and helical carbon nanotubes, for steam generation and solar desalination is described. Under natural sunlight, the maximum water evaporation rate was 2.02 kg m−2 h−1 with an evaporation efficiency of 93.2 % (1 sun) and reached 2.42 kg m−2 h−1 at 12:00 pm (1.35 sun). The composite membranes demonstrated self-floating on the air–water interface and minimal accumulation of superficial salt during the desalination process due to the hydrophobic character of EC. For concentrated saline water (21 wt% NaCl), the composite membranes maintained a relatively high evaporation rate of up to ~79 % compared to the freshwater evaporation rate. The composite membranes are robust due to the thermomechanical stability of the polymer even while operating under steam-generating conditions. Over repeated use, they exhibited excellent reusability with a relative water mass change of >90 % compared to the first evaporation cycle. Moreover, desalination of artificial seawater produced a lower cation concentration (~3–5 orders of magnitude) and thereby yielded potable water, indicating the potential for solar-driven freshwater generation.

Effects of the Addition of Amino-Terminated Highly Branched Polyurea on Curing Properties of Phenol-Formaldehyde Resin.

In this work, a highly branched polyurea (HBP-NH2) similar to urea structure was introduced to phenol-formaldehyde (PF) resin to accelerate itscuring speed The results of gel time and bonding strength were combined to obtain a good modified additional stage and amount of HBP-NH2. The relative molar mass changes of HBP-NH2-modified PF resin were investigated by gel permeation chromatography (GPC). The effects of HBP-NH2 on the curing of PF resin were investigated by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The effect of HBP-NH2 on the structure of PF resin was also investigated by nuclear magnetic resonance carbon spectroscopy (13C-NMR). The test results show that the gel time of the modified PF resin was reduced by 32% and 51% at 110 °C and 130 °C, respectively. Meanwhile, the addition of HBP-NH2 increased the relative molar mass of PF resin. The bonding strength test showed that the bonding strength of modified PF resin increased by 22% after soaking in boiling water (93 °C ± 2) for 3 h. The DSC and DMA analysis indicated that the curing peak temperature decreased from 137 °C to 102 °C, and the curing rate of the modified PF resin was also faster than that of the pure PF resin. The 13C-NMR results showed that HBP-NH2 in the PF resin reacted to produce a co-condensation structure. Finally, the possible reaction mechanism of HBP-NH2 for the modification of PF resin was given.

Desorption of cholesterol from model membranes by β-cyclodextrins: Characterizing plaque fighting compounds via quartz crystal microgravimetry with dissipation monitoring.

Atherosclerosis is induced by low-density lipoprotein cholesterol retention in arterial walls and is identifiable by the presence of atherosclerotic plaques. Supported lipid bilayers (SLBs) are model membrane interfaces that resemble biological cell membranes and can be constructed with various combinations of lipid compositions. Herein, we exploit the solvent-assisted lipid bilayer (SALB) formation method to construct SLB model membranes with varying cholesterol compositions to create a novel lipid-sterol interface atop of biosensors. Cholesterol-laden SLBs are utilized as surfaces where quantitative investigations of various molecules’ cholesterol-fighting competencies can occur. At constant flow, we introduced the cyclodextrins 2-hydroxypropyl-beta-cyclodextrin (HPBCD) and methyl-beta-cyclodextrin (MBCD) atop the membranes of varying cholesterol mol fractions and measured changes in relative areal mass and surface viscosity. Quartz crystal microgravimetry with dissipation monitoring allowed for the collection of these measurements in vitro, overtime. Aggregated experimental desorption data correlates as expected with the relative hydrophobicities and topological polar surface areas of the drug candidates. Data also supports a steady-state kinetic model mechanism for our lipid-cholesterol-drug interface. Overall, our findings demonstrate that MBCD not only removes a distinct quantity of cholesterol greater than that of HPBCD, but MBCD also outperforms the rate constant of cholesterol desorption of HPBCD by a factor of 8.

Developmental Exposure to Trace Concentrations of Chlorpyrifos Results in Nonmonotonic Changes in Brain Shape and Behavior in Amphibians.

Despite regulations and improved design, pesticides remain ubiquitous in the environment at relatively low, trace concentrations. To understand how prolonged exposure to trace pesticide concentrations impacts vertebrate brain development and behavior, we raised larval amphibians (northern leopard frogs, Lithobates pipiens) in 0, 1, or 10 μg/L of the organophosphorus pesticide chlorpyrifos (CPF) from hatching to metamorphosis. Tadpoles exposed to 1 μg/L CPF, but not 10 μg/L CPF, had changes in relative brain mass, relative telencephalon shape, and behavioral responses to a novel visual cue. Tadpoles exposed to 10 μg/L CPF had altered behavioral responses to predator-associated olfactory cues. After metamorphosis, frogs raised in 1 μg/L CPF, but not 10 μg/L CPF, had changes in the shape of their optic tectum and medulla. Thus, we provide robust evidence that even trace, yet ecologically realistic, concentrations of CPF have neurodevelopmental and behavioral effects that carry over to later life-history stages, further emphasizing the potent effects of trace levels of CPF on vertebrate development. Also, some but not all effects were nonmonotonic, meaning that effects were evident at the lowest but not at the higher concentration of CPF.

Oxidation-affected zone in the sintered ZrB2–SiC–HfB2 composites

Understanding the behavior of ultra-high temperature ceramics (UHTCs) against oxidation is of particular importance in high-temperature applications. In this study, ZrB2–SiC–HfB2 UHTC composites were fabricated by spark plasma sintering (SPS) method at different temperatures, times, and pressures to investigate the effects of sintering process variables on their oxidation resistance. Before the oxidation tests, the as-sintered samples contained ZrB2 and SiC phases with (Zr,Hf)B2 solid solution. The samples were subjected to oxidative conditions at 1400 °C and their relative mass changes were measured as a function of oxidation time up to 20 hours. FESEM and EDS equipment were used for microstructural and elemental analyzes of cross-sections of different oxide layers. Due to the oxygen diffusion, ZrO2 and SiO2 phases appeared alongside (Zr, Hf)O2 in the surface layers. After identifying the several oxides and SiC-depleted layers in the oxidation-affected zone, a schematic model for the arrangement of such layers was proposed.

Body composition changes at 12 months following different surgical weight loss interventions in adults with obesity: A systematic review and meta‐analysis of randomized control trials

SummaryTo determine relative lean mass and fat mass changes in adults with obesity following surgical weight loss interventions, a systematic review and meta‐analysis was conducted. The Cochrane Central Register of Controlled Trials, PubMed, Web of Science, EMBASE, and Scopus were screened for eligible studies. Inclusion criteria included randomized controlled trials (RCTs) performed in populations with obesity (body mass index ≥30 kg/m2) aged over 18 years, who underwent any type of bariatric surgery and reported body composition measures via dual‐energy X‐ray absorptiometry or bio‐electrical impedance analysis. Authors conducted full text screening and determined that there were six RCTs eligible for inclusion, with data extracted at 12 months post‐surgery. Meta‐analysis revealed that, relative to gastric banding, Roux‐en‐Y gastric bypass (RYGB) led to greater total body mass loss (mean difference [MD]: −9.33 kg [95% CI: −12.10, −6.56]) and greater fat mass loss (MD: −8.86 kg [95% CI: −11.80, −5.93], but similar lean mass loss (MD: −0.55 kg [95% CI: −3.82, 2.71]. RYGB also led to similar changes in total body mass, fat mass, and lean mass compared with sleeve gastrectomy. RYGB results in greater 12‐month weight and fat loss, but similar changes in lean mass, compared with gastric banding. Further RCTs comparing body composition changes following different bariatric surgery procedures are required.

Acute safety assessment of lithium bioacummulated in mycelial biomass of Ganoderma lucidum

Lithium is a first-line treatment for bipolar disorder, a disorder that is characterized by alternating manic and depressive episodes. However, because of its narrow therapeutic index, lithium can cause adverse effects. The association of lithium with more complex molecules, such as proteins and polysaccharides, may help control the release of lithium throughout the digestive system, thereby reducing the doses that are used by patients and consequently reducing adverse effects. The present study evaluated the acute oral toxicity of lithium bioaccumulated in mycelial biomass of Ganoderma lucidum, a research step that precedes preclinical efficacy studies. The study followed Organization for Economic Cooperation and Development guideline. Male Wistar rats (n = 6) were acutely treated by gavage with fixed doses (300 and 2000 mg/kg) of lithium bioaccumulated in mycelial biomass of G. lucidum. Changes in clinical signs, body mass, relative organ mass, biochemical parameters, blood count, leukocytes, and histopathological changes were evaluated. A group of animals that were treated with vehicle (n = 6) served as the basal group. No signs of toxicity were observed in any of the investigated parameters. Lithium bioaccumulation in mycelial biomass of G. lucidum did not induce signs of toxicity in rats that were acutely orally treated.

Analysis of prolonged marine exposure on properties of AH36 steel

Corrosive marine environment has negative impact on welded steel structures, so it is necessary to investigate the effect of sea exposure on such materials. This research investigates the change of mechanical properties and surface condition of AH36 shipbuilding steel butt-welded specimens exposed to natural marine environment for prolonged periods (6, 12 and 24 months). Contrary to accelerated tests in simulated laboratory environment, this approach is rarely used. Engineering stress–strain diagrams are obtained using standardized procedures for uniaxial tensile tests, giving insight into the change of material strength due to length of exposure and type of corrosive environment (water, sea water, sea waves). Using impact tests, values of measured Charpy impact energy are given. Additionally, relative mass change over time is given along with calculated corrosion rates. Corroded surface is microscopically inspected and comparison, based on number and dimensions of corrosion pits in the observed area, is given.

Debris Emergence Elevations and Glacier Change

Debris-covered glaciers represent potentially significant stores of freshwater in river basins throughout High Mountain Asia (HMA). Direct glacier mass balance measurements are extremely difficult to maintain on debris-covered glaciers, and optical remote sensing techniques to evaluate annual equilibrium line altitudes (ELAs) do not work in regions with summer-accumulation type glaciers. Surface elevation and glacier velocity change have been calculated previously for debris-covered glaciers across the region, but the response of debris cover itself to climate change remains an open question. In this research we propose a new metric, i.e. the debris emergence elevation (ZDE), which can be calculated from a combination of optical and thermal imagery and digital elevation data. We quantify ZDE for 975 debris-covered glaciers in HMA over three compositing periods (1985–1999, 2000–2010, and 2013–2017) and compare ZDE against median glacier elevations, modelled ELAs, and observed rates of both mass change and glacier velocity change. Calculated values of ZDE for individual glaciers are broadly similar to both median glacier elevations and modelled ELAs, but slightly lower than both. Across the HMA region, the average value of ZDE increased by 70 +/− 126 m over the study period, or 2.7 +/− 4.1 m/yr. Increases in ZDE correspond with negative mass balance rates and decreases in glacier velocity, while glaciers and regions that show mass gains and increases in glacier velocity experienced decreases in ZDE. Regional patterns of ZDE, glacier mass balance, and glacier velocities are strongly correlated, which indicates continued overall increases in ZDEE and expansion of debris-covered areas as glaciers continue to lose mass. Our results suggest that ZDE is a useful metric to examine regional debris-covered glacier changes over decadal time scales, and could potentially be used to reconstruct relative mass and ELA changes on debris-covered glaciers using historical imagery or reconstructed debris cover extents.

Water Intake and Ion Exchange in PEDOT:Tos Films upon Cyclic Voltammetry: Experimental and Molecular Dynamics Investigation

Conductive polymer PEDOT:Tos (3,4-ethylenedioxythiophene doped with molecular tosylate) gained considerable attention in various devices for bioelectronic applications, such as organic transistors and sensors. Many of these devices function upon oxidation/reduction processes in contact with aqueous electrolytes. So far, theoretical insight into morphological changes, ion injection, and water intake during these processes was rather limited. In the present work, we combined experiments and molecular dynamics simulations to study the water intake, swelling, and exchange of ions in the PEDOT:Tos film during cyclic voltammetry. We showed that the film underwent significant changes in morphology and mass during the redox processes. We observed both experimentally and in simulations that the film lost its mass during reduction, as tosylate and Na were expelled and gained mass during oxidation mainly due to the uptake of anions, i.e., tosylate and Cl. The results were in line with the UV–VIS–NIR absorption measurements and X-ray photoelectron spectroscopy (XPS) measurements, which revealed that during the redox process a portion of Tos was replaced by Cl– as the counterion for PEDOT. Also, the relative mass change between the most oxidized and reduced states was ∼10 to 14% according to both experiments and simulations. We detected an overall material loss of the film during voltammetry cycles indicating that a portion of the material leaving the film during reduction did not return to the film during the consecutive oxidation. Our combined experimental/simulation study unraveled the underlying molecular processes in the PEDOT:Tos film upon the redox process, providing the essential understanding needed to improve and assess the performance of bioelectronic devices.

Long-Term Marine Environment Exposure Effect on Butt-Welded Shipbuilding Steel

Extreme environments, such as marine environments, have negative impacts on welded steel structures, causing corrosion, reduced structural integrity and, consequently, failures. That is why it is necessary to perform an experimental research sea exposure effect on such structures and materials. Research presented in this paper deals with the mechanical behavior of butt-welded specimens made of AH36 shipbuilding steel when they are exposed to a natural marine environment (water, seawater, sea splash) for prolonged periods (3, 6, 12, 24, and 36 months). The usual approach to such research is to perform accelerated tests in a simulated laboratory environment. Here, relative mass change due to corrosion over time is given along with calculated corrosion rates. Corroded surfaces of specimens were inspected using optical and scanning electron microscopy and comparison, based on the numbers and dimensions of the corrosion pits (diameter and depth) in the observed area. As a result, it can be concluded that exposure between 3 and 6 months shows significant influence on mass loss of specimens. Further, sea splash generally has the most negative impact on corrosion rate due to the combined chemical and mechanical degradation of material. Pit density is the highest at the base metal area of the specimen. The diameters of the corrosion pits grow over the time of exposure as the pits coalesce and join. Pit depths are generally greatest in the heat affected zone area of the specimen.

Comparison between Washing and Ambient Storage of Ni-Rich Active Materials By TGA-MS and XPS

To achieve the energy density needed for automotive applications, Ni-rich cathode active materials (CAMs), like NCM851005 (Li1+ d(Ni0.85Co0.10Mn0.05)1- dO2), are promising candidates.[1] However, these materials are susceptible to the formation of surface impurities upon ambient air exposure during storage.[2–4] These surface groups were subject of various studies, but detailed information on their formation rate and on their decomposition temperatures are lacking. In this study, we investigated the changes in surface chemistry during ambient storage and during subsequent heating for the Ni-rich material NCM851005 in comparison to that of NCM111. We thus identify the surface groups after storage and also provide evidence for a Li+/H+-exchange, a phenomenon which had been observed during the washing of these materials with water.[5] In order to gain knowledge about the formation rate of surface impurities on NCM111 and NCM851005, the pristine powders were subjected to an accelerated storage test. The samples were stored at 25°C in ambient air with a constant relative humidity of ~85% (further on referred to as wet-storage) for increasing time intervals starting from 5 min up to 1 week. After each storage interval, a TGA-MS measurement (thermogravimetric analysis coupled with mass spectrometry) was performed under Ar (at 40 mL/min). The TGA-MS protocol contains a temperature hold phase at 25 °C, then a heat ramp (10 K/min) to 120 °C with a hold at this temperature for 30 minutes, followed by a second temperature ramp to 450 °C (10 K/min), and a final hold at this temperature (see red line in Fig. 1a). The plateau at 120 °C is designed to deconvolute the physisorbed from the chemisorbed water. A washed material (at a water to CAM mass ratio of 5:1) was also analyzed by the same TGA-MS procedure.In addition to the TGA measurements, a special XPS sample holder was used to heat the samples inside the main XPS chamber to evaluate the NCM surface at different temperatures, monitoring the decomposition and desorption of surface contaminants.It was found that the amount of surface contaminants indeed increased with storage time. Predictably, the extent of surface contaminants increased more rapidly for the Ni-rich NCM851005 material than compared to a Ni-poor NCM111 sample. Furthermore, oxygen release at already 280 °C was seen for NCM851005 kept under wet-storage for 7 days (Fig. 1c, blue line). Oxygen release for the as-received material is only observed at higher temperatures (T>650°C). This early onset of oxygen evolution is reminiscent of that of either partially delithiated NCMs or of washed NCMs (see also green line in Fig. 1c).[5,6] We will discuss the likely mechanism for this behavior, supporting our arguments with XPS measurements, where we have found a defective oxygen-deficient phase after heating the materials above the O2 release temperature when the materials was washed, but not in case of the as-received material. This is further evidence for a Li+/H+-exchange during storage of Ni-rich materials under ambient conditions.We will discuss future mitigation strategies such as surface coatings or gas treatment to minimize the effects of ambient storage.Figure 1: TGA-MS analysis of as-received (black lines), wet-stored (in blue) and washed (in green) NCM851005 under Ar. The upper panel shows the TGA profile and relative mass change of the different samples. The other panels show the MS traces of (b) H2O (m/z = 18), (c) O2 (m/z=32) and (d) of CO2 (m/z=44). Figure 1

Allometric growth in mass by the brain of mammals.

I re-examined published data for ontogenetic change in relative mass of the brain in six species of mammal (i.e., sheep, pig, cow, horse, rat, cat) to illustrate an insidious problem with conventional analyses of brain-body allometry. Graphical displays of logarithmic transformations of the original data for each species give the appearance of two discrete mathematical distributions, but untransformed observations nonetheless conform to a single distribution that is well described by a single, nonlinear equation. The concept of biphasic, allometric growth by the brain consequently is an artifact of transformation. The notion of Rapid and Slow phases in relative growth by the brain also is an artifact, because the notion is based explicitly on the concept of biphasic growth allometry. Relative growth by the brain in sheep, pigs, cows, and horses follows the path of a power curve with an exponent less than 1, so relative growth declines progressively as animals grow to their maximum size, at which point growth effectively ends for both brain and body. Relative growth by the brain in rats and cats follows the path of an exponential curve and consequently is more like relative growth by the brain of odontocoete cetaceans and primates, with the brain growing rapidly relative to the body early in ontogeny and attaining maximum (cats) or near-maximum (rats) mass well before the body reaches its maximum. An exponential pattern of relative growth by the brain appears to have evolved independently in rodents, carnivores, odontocoetes, and primates.