Deviation Of Composition Research Articles

Maternal Intrapartum Antibiotic Treatment and Gut Microbiota Development in Healthy Term Infants

Objective: The aim of the study was to investigate the impact of intrapartum antibiotic treatment (IAT) on the compositional development of gut microbiota in healthy term infants. Study Design: A case-control study of 24 infants exposed to and 24 matched infants not exposed to IAT was conducted. All subjects were born by vaginal delivery at term and breastfed. None of the infants received antibiotics during the immediate neonatal period. Fecal samples were obtained at the ages of 1 and 6 months. The composition of the intestinal microbiota was assessed by 16S rRNA gene sequencing. Results: IAT was associated with reduced microbial richness but not diversity at 1 month of age. Furthermore, the relative abundances of Clostridiaceae and Erysipelotrichaceae were significantly altered in infants exposed to IAT as compared to nonexposed infants at 1 month of age. The observed deviations in gut microbiota composition between infants exposed and not exposed to IAT diminished by the age of 6 months. Conclusions: IAT is associated with short-term perturbations in the gut microbiota development in healthy term, vaginally delivered, breastfed infants. The composition of the gut microbiota is mostly restored by the age of 6 months.

Secondary Malnutrition and Nutritional Intervention in Cholestatic Liver Diseases in Infants.

We aimed to conduct an updated review on the pathophysiology, diagnosis, and nutritional intervention of CCLD and secondary malnutrition in infants. Protein-energy malnutrition, impaired linear growth, fat-soluble vitamin deficiencies, and hepatic osteodystrophy can occur in up to 80% of cases. The proposed pathophysiological mechanisms include insufficient energy intake, lipid- and fat-soluble vitamin malabsorption, increased energy expenditure, altered intermediate metabolism, hormonal dysregulation, and systemic inflammation. The current approach to diagnosis is the identification of the deviation of growth parameters, body composition, and serum concentration of micronutrients, which determines the type and magnitude of malnutrition. Currently, liver transplantation is the best therapeutic alternative for the reversal of nutritional impairment. Early and effective portoenteroanatomosis can extend survival in patients with biliary atresia. Medical and dietary interventions in some storage and metabolic diseases can improve liver damage and thus the nutritional status. A proportion of patients with biliary atresia have fat-soluble vitamin deficiencies despite receiving these vitamins in a water-soluble form. With aggressive enteral nutrition, it may be possible to increase fat stores and preserve muscle mass and growth. The nutritional issues identified in the pre- and post-transplantation stages include muscle mass loss, bone demineralization, growth retardation, and obesity, which seems to correspond to the natural history of CCLD. Due to the implications for the growth and development of infants with CCLD with this complex malnutrition syndrome, innovative projects are required, such as the generation of prediction and risk models, biomarkers of growth and body composition, and effective strategies for nutritional prevention and intervention.

Nutritional Status Assessment of Pistachio Orchards in Qazvin Plain, Iran

ABSTRACT Plant analysis is used to optimize the fertilizer applications and diagnosis of the plant nutrition disorders. In the present study, the standard norms for pistachio orchards have been calculated and compared using two methods of Compositional Nutrient Diagnosis (CND) and Deviation from Optimum Percentage (DOP) in Qazvin Plain (Iran). The composite leaf samples were taken from 200 pistachio orchards during three years (2017–2019) and concentrations of Manganese (Mn), Zinc (Zn), Iron (Fe), Magnesium (Mg), Calcium (Ca), Potassium (K), Phosphorus (P), Nitrogen (N), Boron (B), and Copper (Cu) were measured, along with recording the orchards’ yield. The results of CND method showed that the most frequency percentage of the nutrients deficiency was respectively belonged to Mn, Mg, and P in the orchards. Same results were obtained in DOP method. The priority of the nutrient’s deficiency in DOP method was as follows: Mn > Mg > P > K> Ca. In general, it is concluded that Mn, Mg, and P are the most limiting nutrients, are which due to being calcareous, high K content and low organic matter content of the soil, these deficiencies are justified. Therefore, it is recommended to use organic matters, P, Mg, and Mn to improve the yield of pistachio orchards.

Ultrashort pulse laser-induced submicron bubbles generation due to the near-surface material modification of soda-lime glass

Experimental evidence for near-surface micro- and nanoscopic processes at ultrashort pulsed laser irradiation(wavelength 775 nm, pulse duration 150 fs) of soda-lime glass near the laser ablation threshold is acquired by transmission electron and secondary electron microscopy (SEM, TEM) as well as by energy disperse x-ray spectroscopy (EDX) investigations of laser-induced subsurface bubbles. Well separated laser irradiations result in individual micrometre bubbles while submicron bubble groups or asymmetrically damaged bubbles appear for overlapping pulses. The overlapping laser irradiations result in a direction dependent damage for the successive bubbles when the inter-pulse distance is small. TEM/SEM studies of cross sectioned bubble prove that precipitations and jets are formed in the centre of the micron bubbles’ bottom. This nano-jets inside the bubble can be related to the self-focusing of the femtosecond laser. A modified layer with a composition deviation from the bulk glass can be a key factor for the formation of the bubble with a thin shell about 100 nm. Moreover, next to the central main bubble, nanometre sized bubbles appear below the surface. Thermal processes inside the bubble cause a smooth inner surface as well as redeposited material mainly opposite to the jet formed at the bottom. The different glass composition near the surface strongly suggests that the altered glass surface composition contributes to the forming mechanism of these near-surface features. Implications of these sub-surface bubbles and jet formation for laser ablation related applications comprise incubation as well as roughness development that limits the achievable precision.

Poly(1,5-pentylene-co-2,2,4,4-tetramethyl cyclobutylene terephthalate) copolyesters with high Tg and improved ductility and thermal stability

Poly(1,5-pentylene-co-2,2,4,4-tetramethyl cyclobutylene terephthalate) (PPecBT) random copolyesters glass transition temperature up to 136 °C were synthesized through two-step melting polycondensation of dimethyl terephthalate (DMT) or terephthalic acid (TPA), 2,2,4,4-tetramethyl-1,3-cyclobutanediol (CBDO) and 1,5-pentanediol (PeDO). They were characterized and assessed with intrinsic viscosity, 1H NMR, DSC, TGA, tensile and impact testing as well as melt foaming observation. Using PeDO as a diol comonomer was helpful to depress CBDO sublimation and pipeline blocking, and to reduce the composition and cis-trans ratio deviations between monomer and copolymer. The presence of PeT repeat unit in PPecBT was beneficial to improve the thermal stability of PPecBT and to reduce undesired melt foaming and volume expansion during melt processing. The Tg of these amorphous copolymers is determined by intrinsic viscosity, copolymer composition and cis-cB unit fraction, and a quantitative relationship among them is established. Futhermore, these PPecBTs showed superior tensile ductility as well as strength and modulus.

CO1-Based DNA barcoding for assessing diversity of Pteropus giganteus from the state of Azad Jammu Kashmir, Pakistan.

The flying fox (Pteropus giganteus) also familiar with the name of the greater Indian fruit Bat belongs to the order Chiroptera and family Pteropodidae. Current research emphasis on the DNA barcoding of P. giganteus in Azad Jammu Kashmir. Bat sequences were amplified and PCR products were sequenced and examined by bioinformatics software. Congeneric and conspecific, nucleotide composition and K2P nucleotide deviation, haplotype diversity and the number of haplotypes were estimated. The analysis showed that all of the five studied samples of P. giganteus had low G contents (G 19.8%) than C (27.8%), A (25.1%) and T (27.3%) contents. The calculated haplotype diversity was 0.60% and the mean intraspecific K2P distance was 0.001% having a high number of transitional substitutions. The study suggested that P. giganteus (R=0.00) do not deviate from the neutral evolution. It was determined from the conclusion that this mtDNA gene is a better marker for identification of Bat species than nuclear genes due to its distinctive characteristics and may serve as a landmark for the identification of interconnected species at the molecular level and in the determination of population genetics.

Effect of crystal quality on twinning stress in Ni–Mn–Ga magnetic shape memory alloys

Low twinning stress (TS) is a prerequisite for magnetic shape memory functionality in ferromagnetic martensites. We compare Ni 50 Mn 28 Ga 22 (nominal at.%) single crystals from four different producers to reveal the effect of crystal quality on the TS. Near the reverse martensite transformation, the TS is generally low, about 1 MPa, regardless of mosaicity of up to 1.7° and chemical composition deviations of up to 2 at.% of Mn. Pure type I and type II twin boundaries occur in crystals with smooth chemical composition gradients. The corresponding temperature dependences of TS follow universal linear trends with the slopes of −0.045 MPa/K for type I twins and −0.001 MPa/K for type II twins, enabling a very low TS down to 2 K for the latter. An intermediate slope of −0.023 MPa/K appears for mixed type I/type II twin boundaries in a crystal with sharp local chemical deviations. We conclude that the crystal quality affects the magnitude of the TS indirectly, through its impact on the character of the twin boundaries. The effect is weak near the martensite transformation temperature and strong at low temperatures.

Binary mixture isothermal vapour-liquid equilibrium: Trifluoromethane (R23) + octafluoropropane (R218) at the temperature from 223.150 K to 263.150 K

The mixed-refrigerant Joule-Thomson refrigerator (MJTR) is simple in structure, safe and reliable, and is suitable for temperatures from 80 to 230 K. Trifluoromethane (R23) and octafluoropropane (R218) are satisfactory as non-flammable refrigerants in MJTR. In this paper, the gas-phase single-cycle method was used to conduct a vapor–liquid equilibrium (VLE) experiment on the R23 + R218 binary system in the temperature range from 223.150 K to 263.150 K. The VLE experimental data were correlated using the Peng-Robinson (PR) equation of state and the Huron-Vidal (HV) mixing rule combined with non-random two-liquid (NRTL) activity coefficient model. The maximum average absolute relative deviation of pressure (AARDp) and the maximum average absolute deviation of vapor phase composition (AADy) are 0.67% and 0.005, respectively.

A General-Purpose Biotic Index to Measure Changes in Benthic Habitat Quality across Several Pressure Gradients

Realistic assessments of the ecological status of benthic habitats, as requested by European directives such as the Water Framework Directive and the European Marine Strategy Framework Directive, require biotic indices capable of detecting anthropogenic impact without having preliminary knowledge of the occurring pressures. In this context, a new general-purpose biotic index (GPBI) based on the deviation of benthic macrofauna community composition and structure from a valid reference (i.e., good ecological status) is proposed. GPBI is based on the assumption that as a site becomes impacted by a pressure, the most sensitive species are the first to disappear, and that stronger impacts lead to more important losses. Thus, it explicitly uses the within-species loss of individuals in the tested station in comparison to one or several reference stations as the basis of ecological status assessment. In this study, GPBI is successfully used in four case studies considering the impact of diversified pressures on benthic fauna: (1) maerl extraction in the northern Bay of Biscay, (2–3) dredging and trawling in the North Sea, and (4) hypoxic events at the seafloor in the Gullmarfjord. Our results show that GPBI was able to efficiently detect the impact of the different physical disturbances as well as that of hypoxia and that it performs better than commonly used pressure-specific indices (M-AMBI and TDI). Signal detection theory was used to propose a sound good/moderate ecological quality status boundary, and recommendations for future monitoring are also provided based on the reported performance of GPBI.

Fabricating Homogeneous FeCoCrNi High-Entropy Alloys via SLM In Situ Alloying

Selective laser melting (SLM) in situ alloying is an effective way to design and fabricate novel materials in which the elemental powder is adopted as the raw material and micro-areas of elemental powder blend are alloyed synchronously in the forming process of selective laser melting (SLM). The pre-alloying process of preparation of raw material powder can be left out, and a batch of bulk samples can be prepared via the technology combined with quantitative powder mixing and feeding. The technique can be applied to high-throughput sample preparation to efficiently obtain a microstructure and performance data for material design. In the present work, bulk equiatomic FeCoCrNi high-entropy alloys with different processing parameters were fabricated via laser in situ alloying. Finite element simulation and CALPHAD calculation were used to determine the appropriate SLM and post-heating parameters. SEM (scanning electron microscope), EDS (energy dispersive spectroscopy), XRD (X-ray diffraction), and mechanical testing were used to characterize the composition, microstructure, and mechanical properties of as-printed and post-heat-treated samples. The experimental results show that the composition deviation of laser in situ alloying samples could be controlled within 20 wt %. The crystal structure of as-printed samples is a single-phase face-centered cubic (FCC), which is the same as those prepared by the traditional method. The mechanical properties of the samples prepared by laser in situ alloying with elemental powder blend are comparable to those prepared by pre-alloying powder and much higher than those prepared by the traditional method (arc melting). As-printed samples can get a homogeneous microstructure under the optimal laser in situ alloying process combined with post-heat treatment at 1200 °C for 20 h.

Pulsed laser deposited stoichiometric GaSb films for optoelectronic and phase change memory applications

Phase-change memory (PCM) holds great potential in realizing the combination of DRAM-like speeds with non-volatility and large storage capacity for future electronic devices including in-memory computing. However, various (reliability) issues related to e.g. too high programming current (power consumption), resistance drift, data retention (low crystallization temperature), phase separation and density change upon switching stand in the way to make PCM really attractive. GaSb thin films have interesting optical and electrical properties which are attractive for optoelectronic and PCM applications but so far reported stoichiometric GaSb compositions are Sb-rich which produced reliability issues in PCM devices. In this study, we managed to deposit stoichiometric GaSb thin films using pulsed laser deposition (PLD) by varying deposition parameters and conditions. Using electron microscopy, the morphology of deposited films and target surface and the compositional deviation from exact stoichiometry have been investigated. We show that the directional nature of laser-target interaction is directly responsible for film quality in PLD in which particulates with high number density are generated due to directional pillar formation. Suppressing this pillar formation, by a simple 180° target rotation, showed an increase in deposition yield by 60%, exact stoichiometric transfer from target to substrate, and large reduction in particulate density. Moreover, from XRD analysis, we show that exact stoichiometric transfer from target to substrate is crucial for structural integrity of the produced films. Temperature induced structural transformation from resistivity vs. temperature measurements show a high crystallization temperature of 250 °C for stoichiometric GaSb thin film. We believe the exact stoichiometric GaSb thin films with reduced particulate densities and favorable structural and (opto)electronic properties are attractive for future PCM devices.

Investigation of the effect of contamination with chemical elements on changes in the content of clay fraction in sandy-clay rocks

The reasons for soil pollution that causes deviations in the mineral composition are considered. It is noted that changes in the chemical composition of the soil lead to a change in various fractions. This process is considered on the example of clay fractions. The sandy-clay rocks of the Leningrad region in the Russian Federation are considered. Modeling of situations on taking samples of rocks for research has been performed. Comparison of the calculations with the results of express control of the state of rocks by other methods is carried out. The method for determining the content of clay fraction in sandy-clay rocks has been determined.

Nutritional and Botanical Approaches for Inflammatory Bowel Disease

Nutritional and Botanical Approaches for Inflammatory Bowel Disease

Optimized crop growth area composition for long duration spaceflight

This paper presents an optimized composition of crop growth areas for biological life support systems with respect to nutrition and equivalent system mass. For this purpose, crop growth area compositions from literature are compared with compositions derived from an optimization algorithm. The optimization algorithm uses literature data for crop growth rates and crop nutrient content to minimize the required crop growth area required to supply all nutrients for a human. The algorithm derives the required crop growth area per crew member under different dietary boundary conditions and the resulting nutrient supply is compared to reported diets from crops for spaceflight. The primary goal of this optimization is to find the minimal area required to supply all relevant macronutrients. The minimal area for the exact desired composition of macronutrients (carbohydrates, fats and proteins) was 106.86 m² using chard, lettuce, peanut, bell pepper, snap beans and spinach. If a deviation in the macronutrient composition is allowed the required area can be reduced to 39.88 m² of wheat and white potatoes. Since the variety of crops is a relevant factor for long term food supply, a limit of the maximum growth area per crop was introduced to derive a diet with more variety, which resulted in a minimal area of 57.04 m² using drybean, rice, snap beans, sweet potato, wheat and white potato. Based on this result, a further manual adjustment of the crop growth areas was performed to also introduce lettuce and tomato in the crops provided and adjust the remaining crop compositions to receive better macro- and micronutrient conformity while maintaining a crop growth area of 57 m². One major result of this analysis is that soybeans are not the most favorable crop with regard to protein and fat productivity and the focus of NASA crop selection for full nutrient supply on soybean results in exceedingly large required crop areas of 164.15 m². The resulting crop growth areas from both the optimization and literature are then analyzed as plant growth chambers (PGC) in the Life Support Trade-Off Tool (LiSTOT) of the institute of astronautic from the Technical University of Munich (TUM). LiSTOT calculates the impact of the PGC on an ISS based environmental control and life support system (ECLSS) using averaged steady state values for the plants from literature. Based on this result LiSTOT scales the physical chemical systems and calculates the resulting equivalent system mass (ESM) of the different cases. This approach allows the consideration of not only the PGC ESM, but also the impacts the PGC has on other ECLSS systems and their ESM. The ESM values for PGC were updated to assume LEDs instead of high pressure sodium lamps resulting in a new logistic mass of the PGC of 1.28 kg/(y m²) and a lower specific system mass of 87.7 kg/m². The mass balance analysis of carbon within the overall ECLSS lead to a reduction of the plant growth area to 50.6 m² and the break-even time with the ISS ECLSS was calculated to 87.2 years. With more optimistic assumptions for the LED and using urine as nutrient supply this time can be reduced to 14.6 years. The analysis also showed that the derived crop composition is not only favorable regarding nutrient supply but also with regard to the ESM and break-even time compared to previously reported crop compositions. Only the PGC with only wheat and white potatoes has a lower ESM but also provides a less balanced nutrient supply. This PGC is downscaled to 37.55 m² to achieve carbon balance and a break-even time of 38.4 years or 10.3 years with the optimistic assumptions.

Phase Composition and Thermoelectric Properties of Materials Based on Cu2 – xSe (0.03 ≤ x ≤ 0.23)

The phase composition and thermoelectric properties of Cu2 – xSe samples with different deviations from the stoichiometric composition (x = 0.03, 0.08, 0.13, 0.18, and 0.23) are studied. Bulk thermoelectric materials based on Cu2 – xSe are synthesized by spark plasma sintering. The phase composition is studied using the X-ray diffraction method. Depending on the chemical composition, the materials based on Cu2 – xSe at room temperature can be either a single-phase material containing only the cubic β-Cu2Se phase or a two-phase material containing a mixture of monoclinic α-Cu2Se and cubic β-Cu2Se phases. It is shown that the deviation of the stoichiometric composition has a substantial effect on the electrophysical characteristics of the material. With an increase in the deviation of the stoichiometric composition, the concentration of the main charge carriers in Cu2 – xSe increases because of the formation of copper vacancies. The change in the thermal conductivity substantially contributes to the thermoelectric figure of merit of Cu2 – xSe compounds. In the investigated range of chemical compositions, the maximum values of thermoelectric figure of merit around ZT ~ 1.3 at 600°C are observed in samples with the Cu1.97Se composition.

Clinical and bioimpedance features of manifestations of chronic non-bacterial prostatitis with an inflammatory component in young men

Introduction. Chronic prostatitis is the most common androurological disease affecting mainly young and middle-aged men. The variety of pathogenetic mechanisms and clinical manifestations, the tendency to recurrence necessitate the search for new methods of examination and monitoring of this disease. This can be facilitated by the study of bioimpedance parameters in patients with chronic prostatitis.Purpose of the study. To identify bioimpedance and clinical features of the manifestations of chronic non-bacterial prostatitis with an inflammatory component (CNPIC) in young men.Materials and methods. In the period from 2018 to 2020, on the basis of Krasnoyarsk Interdistrict Clinical Hospital No 4, a comprehensive survey of 80 men with CNPIC of the first period of adulthood from 22 to 35 years was conducted using valid questionnaires. Bioimpedansometry was carried out using a complex KM-AR-01, grade “DIAMANT-AIST mini”.Results. Pain predominates in the clinical picture of CNPIC, dysuric disorders are less pronounced. The examined men had pronounced deviations of the component composition of the body due to an increase in fat mass and extracellular fluid volume, which, due to common pathogenetic mechanisms, can support chronic inflammation and influence treatment outcomes.Conclusion. Bioimpedansometry can be a promising method in complex diagnostics and subsequent objective monitoring of the course of CNPIC.

Influence of Synthesis-Related Microstructural Features on the Electrocaloric Effect for 0.9Pb(Mg1/3Nb2/3)O3–0.1PbTiO3 Ceramics

Despite having a very similar electrocaloric (EC) coefficient, i.e., the EC temperature change divided by the applied electric field, the 0.9Pb(Mg1/3Nb2/3)O3–0.1PbTiO3 (PMN-10PT) ceramic prepared by mechanochemical synthesis exhibits a much higher EC temperature change than the columbite-derived version, i.e., 2.37 °C at 107 °C and 115 kV/cm. The difference is due to the almost two-times-higher breakdown field of the former material, 115 kV/cm, as opposed to 57 kV/cm in the latter. While both ceramic materials have similarly high relative densities and grain sizes (>96%, ≈5 μm) and an almost correct perovskite stoichiometry, the mechanochemical synthesis contributes to a lower level of compositional deviation. The peak permittivity and saturated polarization are slightly higher and the domain structure is finer in the mechanochemically derived ceramic. The secondary phases that result from each synthesis are identified and related to different interactions of the individual materials with the electric field: an intergranular lead-silicate-based phase in the columbite-derived PMN-10PT and MgO inclusions in the mechanochemically derived ceramic.

Evolution of Al–Ti Oxide Inclusions in Fe-Based Alloys During Thermal Holding by a Novel Inductive Separation Method

Steelmaking has undergone significant technological advancements, particularly regarding oxide metallurgy. Herein, we employed a novel method of inductive separation for separating Al–Ti oxide from Ti-bearing oxides to trace the evolution of a specific type of oxide in a solid Fe-based alloy during thermal holding. The evolution occurred within the solid alloy; hence surface effects were prevented. The evolution was investigated at a lower temperature than what was used in previous studies; using this information, the impact of temperature was ascertained. The results revealed that, after holding for 0.5 hours at 1273 K, the shape of the Al–Ti oxide changed from spherical to irregular. The homogeneous oxide changed to a heterogeneous oxide containing Al- and Ti-rich parts, and the compositional deviation became distinct after thermal holding. After 12 hours, the composition of the Al-rich parts approached that of Al2O3. A comparison of the variation of the Al–Ti oxide at 1273 K and 1573 K revealed that the ratio of the heterogeneous oxide increased at lower temperatures due to the greater degree of supersaturation of Al2O3. The mechanism involved the precipitation of Al2O3 from Al–Ti oxide during holding. The fundamental data on the time-dependent variation in the morphology and composition of the Al–Ti oxide function as a first step to modify the oxide using thermal holding to promote the induction of an intragranular acicular ferrite (IAF) microstructure.

Andersson‐Magnéli Phases TinO2n‐1: Recent Progress Inspired by Swedish Scientists

AbstractAmong homologous series of metal oxides, Andersson‐Magnéli phases TinO2n‐1 (n=4–10) have attracted renewed scientific attention because of their behaviour in electrical conductivity and chemical/thermal stability. Various applications have also been reported for the phases with different values of n, or slightly reduced rutile (TiO2). The characteristic properties of these materials depend strongly on the compositional deviation from TiO2 and the way in which the structure accommodates the deviation. Thus, an urgent requirement is to overcome difficulties in characterizing such materials at atomic resolution. Here, we trace the discovery of the Andersson‐Magnéli phases, and report the application of recent developments in electron microscopy to reveal the relation, at the local level, between structural characteristics and electronic states, specifically for the materials TinO2n‐1 with n=4–8. The electrical conductivity of Ti4O7 has been reported previously to show three clearly distinct states on decreasing temperature from 300 K. For this reason, we focus on Ti4O7 as a representative example of the TinO2n‐1 phases and report structural characteristics at temperatures corresponding to each of the three different phases, focusing on the distribution of Ti3+ and Ti4+ cations from analysis of single‐crystal XRD data. Electron diffraction experiments and electrical conductivity measurements are also reported.

Impact of Temporal pH Fluctuations on the Coexistence of Nasal Bacteria in an in silico Community.

To manipulate nasal microbiota for respiratory health, we need to better understand how this microbial community is assembled and maintained. Previous work has demonstrated that the pH in the nasal passage experiences temporal fluctuations. Yet, the impact of such pH fluctuations on nasal microbiota is not fully understood. Here, we examine how temporal fluctuations in pH might affect the coexistence of nasal bacteria in in silico communities. We take advantage of the cultivability of nasal bacteria to experimentally assess their responses to pH and the presence of other species. Based on experimentally observed responses, we formulate a mathematical model to numerically investigate the impact of temporal pH fluctuations on species coexistence. We assemble in silico nasal communities using up to 20 strains that resemble the isolates that we have experimentally characterized. We then subject these in silico communities to pH fluctuations and assess how the community composition and coexistence is impacted. Using this model, we then simulate pH fluctuations—varying in amplitude or frequency—to identify conditions that best support species coexistence. We find that the composition of nasal communities is generally robust against pH fluctuations within the expected range of amplitudes and frequencies. Our results also show that cooperative communities and communities with lower niche overlap have significantly lower composition deviations when exposed to temporal pH fluctuations. Overall, our data suggest that nasal microbiota could be robust against environmental fluctuations.