VIDEOFLUOROSCOPIC EVALUATION OF THE IMPACT OF CAPSULE SIZE AND SUBJECT'S AGE AND GENDER ON CAPSULE SWALLOWING.

BACKGROUND: People recurrently have difficulties swallowing solid medications, which can be associated with the size of the medication and the age and gender of individuals. OBJECTIVE: To evaluate the impact of capsule size and adults' age and gender on oral and pharyngeal capsule transit during capsule swallows. METHODS: Videofluoroscopy was used to measure capsule oral and pharyngeal transit during swallows in 49 healthy individuals (17 men and 32 women), with a mean age of 46 years (ranging from 23 to 88 years). Smaller capsules were filled with 0.50 mL of barium sulfate, and larger capsules were filled with 0.95 mL of barium sulfate; the volume of liquid ingested with the capsules was also quantified in each ingestion. The measurements included the oral preparation time, oral transit time, swallowing reaction time, time to laryngeal vestibule closure, laryngeal vestibule closure duration, pharyngeal transit time, and upper esophageal sphincter opening duration. RESULTS: The capsule size did not influence either the oral or pharyngeal transit time. Increased liquid volume was ingested with larger capsules and by people older than 40 years. The oral transit time was shorter in older adults (60-88 years), and the time to laryngeal vestibule closure was longer in women. CONCLUSION: The size of large capsules did not make a difference in oral or pharyngeal transit when compared with smaller capsules. The capsule size and the participant's age influenced the volume of liquid ingested - larger capsules and older individuals required a larger volume. The capsule oral transit was faster in individuals older than 60 years. BACKGROUND: •Swallowing is influenced by the characteristics of what is being swallowed. BACKGROUND: •There was no difference in swallowing capsules containing 0.50 mL or 0.95 mL. BACKGROUND: •Larger capsules need more liquid ingestion to make swallowing easier. BACKGROUND: •Individuals older than 40 years need a greater volume of liquid to swallow capsules than younger adults.

Flotation recovery of barite from high-density waste drilling fluid using ß-cyclodextrin as a novel depressant and its mechanism.

High-density waste drilling fluid contains an abundance of recyclable weighting reagents, direct disposal can pollute the environment. In this paper, the primary mineral composition of a high-density waste drilling fluid from a well in the southwest oil and gas field was analyzed. This paper proposes ß-cyclodextrin (ß-CD) as a depressant for the recovery of barite from waste drilling fluid. The recovery process was investigated through inverse flotation experiments, and the mechanism was analyzed using zeta potential, contact angle analysis, and FTIR. The flotation experiments showed that under the SDS flotation system, when the pH was 9.0 and the amount of depressant ß-CD was 900 g/t, the barite recovery and density reached the highest values, which were 87.41% and 4.042 g/cm3, respectively. Zeta potential experiments, contact angle analysis, and FTIR analysis indicate that ß-CD adsorbed onto barite through enhancing the hydrophilicity of barite, electrostatic force adsorption, and strong adsorption, which could not be displayed by SDS through competitive adsorption. Furthermore, ß-CD exhibited a selective inhibitory effect on barite and enabled reverse flotation. The mechanism model of the flotation separation process was established.

A novel gelatinized barium sulfate injection method for assessment of bronchoalveolar lavage parameters.

INTRODUCTION: Bronchoalveolar lavage (BAL) is frequently used in pulmonary medicine though it requires further optimization. Practical obstacles such as patient safety and procedural limitation have to date precluded large, controlled trials aimed at standardization of BAL procedure. Indeed, BAL guidelines are based on observational data. Innovative research methods are necessary to advance the clinical practice of BAL. METHODS: In our study, we evaluated the effect of injecting a gelatinized barium solution into different lobes and segments of cadaveric lungs. As the technique requires an irreversible injection into lung airspaces, it is not suitable for in vivo purposes. We measured the volume returned from BAL as well as the distribution of BAL injection via dissection. Segmental anatomic orientation was compared to a radiologist's impression of plain film radiographs taken of injected lungs. RESULTS: Mean injected volume distributions were greatest in the upper lobes and lowest in the lower lobes; mean ratios of injected volume distribution to lung lobe volume also followed this trend. Cannulated bronchi orders favored lower branches in the upper lobe and higher branches in the lower lobes. Segmental anatomy varied by the lung lobe injected and was most varied in the lower lobes. CONCLUSION: This novel gelatinized-barium injection technique provides a minimally complex method to yield clinically meaningful feedback on the performance of BAL. The technique is also adaptable to study of procedural parameters in the context of variable lung anatomies and pathologies.

Analyzing the performance of synthesized nano-catalysts for transesterification of waste cooking oil as environment friendly drilling fluid.

Ester-based drilling fluids (EBDF) are preferred over oil-based drilling fluids (OBDF) and water-based drilling fluids (WBDF) because of their great biodegradability, low toxicity, and improved performance. In this work, waste cooking oil methyl ester (WCOME) was used to prepare an environmentally friendly EBDF. Through a transesterification process utilizing a modified calcium oxide based heterogenous catalyst, the waste cooking oil is transformed into waste cooking oil methyl ester. Response surface approach was used to strengthen the transesterification. The optimize conditions for CaO/Al2O3 resulted in the highest yield of 96.56% at a molar ratio of 11.9:1, 3.19 wt % of CaO/Al2O3, 53.79 °C, and 76.86 min. In contrast, CaO/TiO2 yielded 98.15% at a molar ratio of 11.99:1, with a CaO/TiO2 of 2.53 wt % at 59.79 in 68.14 min. Additionally, two separate densities of 9 ppg and 12 ppg EBDF are formulated with two distinct oil-to-water ratios (70:30 and 80:20) using synthesized WCOME. To assess the effectiveness of formulated EBDF thorough rheological investigation is conducted at 150°. Additionally, the filtration loss at HPHT conditions, emulsion stability, and Barite sag analysis of the drilling fluid are all analyzed at before ageing and after dynamic ageing. With better rheological features, less fluid loss, good emulsion stability, and minimal barite sagging, the designed EBDF performs efficiently. The drilling fluid met the API requirement and demonstrated stability even after ageing at 250 °F for 72 h, suggesting that it may be used for extended periods of time in drilling.

Improved radiologic diagnosis of delayed gastric conduit emptying (DGCE) after esophagectomy using a functional upper gastrointestinal contrast study.

BACKGROUND: With increasing incidence of esophageal cancer, a growing number of patients are at risk of developing delayed gastric conduit emptying (DGCE) in the early postoperative phase after esophagectomy. This condition is of great postoperative concern due to its association with adverse outcomes. PURPOSE: To give a narrative review of the literature concerning radiological diagnosis of DGCE after esophagectomy and a proposal for an improved, functional protocol with objective measurements. MATERIAL AND METHODS: The protocol was designed at Virginia Mason Medical Center in Seattle and is based on the Timed Barium Esophagogram (TBE) concept, which has been adapted to assess the passage of contrast from the gastric conduit into the duodenum. RESULTS: The literature review showed a general lack of standardization and scientific evidence behind the use of radiology to assess DGCE. We found that our proposed standardized upper gastrointestinal (UGI) contrast study considers both the time aspect in DGCE and provides morphologic information of the gastric conduit. This radiological protocol was tested on 112 patients in a trial performed at two high-volume centers for esophageal surgery and included an UGI contrast study 2-3 days postoperatively. The study demonstrated that this UGI contrast study can be included in the standardized clinical pathway after esophagectomy. CONCLUSION: This new, proposed UGI contrast study has the potential to diagnose early postoperative DGCE in a standardized manner and to improve overall patient outcomes after esophagectomy.

Usefulness of barium sulfate and iohexol as contrast agents for VFSS in visualizing components of swallowing predictable of poor outcomes.

Barium sulfate and iohexol are commonly used as contrast agents for videofluoroscopic swallowing study (VFSS). This study compared their usefulness as contrast agents in visualizing components of swallowing predictable of subsequent pneumonia and unintentional weight loss after VFSS. This was a randomized, controlled, crossover trial. The two contrast agents were alternately used in the same participants, and the order in which the contrast agent was tested first was randomly assigned. After VFSS, we followed the participants for 3 months and the association between VFSS findings of each contrast agent and the subsequent pneumonia and unintentional weight loss were analyzed. A total of 30 participants were included in the analysis. We recorded 11 cases of subsequent pneumonia and 13 of unintentional weight loss. Regarding the risk of subsequent pneumonia after VFSS, only the oral transit time and number of swallows tested with barium sulfate indicated significant differences between participants with and without subsequent pneumonia. For unintentional weight loss, oral transit time and pharyngeal wall coating after swallowing tested with barium sulfate, as well as oral transit time, nasal penetration, residue in the valleculae, PAS scores, and number of swallows when testing with iohexol demonstrated significant differences between those with and without unintentional weight loss.

Occurrence state of fluoride in barite ore and the complexation leaching process.

Barite ore is typically associated with difficult-to-remove vein minerals, but commercial barite products require a high BaSO4 content. We investigated the occurrence state of fluoride in barite ore using various analytical techniques, which indicated that elemental fluorine in barite predominantly exists as fluorite. Fluoride was then leached from barite ore via complexation. The effects of HCl and AlCl3 concentrations, temperature, time, and liquid-solid ratio on the leaching rate were examined, and the leaching conditions were optimized using an orthogonal array method. The fluorine leaching rate approached 93.11% after stirring for 30 min at 90 °C and 300 rpm with 3 mol/L HCl, 0.4 mol/L AlCl3, a liquid-solid ratio of 10:1 mL/g, and an ore sample size of -75 µm + 48 µm. According to the leaching kinetics, the process conformed to the solid membrane diffusion control model at a high temperature and the joint chemical reaction-diffusion control model at a low temperature. The apparent activation energy was 56.88 kJ/mol. Furthermore, aluminum and fluorine coordination numbers increased with increasing Al3+/F- molar concentration ratios. Competing complexation reactions of Al3+, H+, and F- occurred at three levels. This complexation approach effectively leaches fluoride from barite, improves barite product quality, and reduces environmental pollution.

Assessing the ecological impacts of NORM-contaminated scale on marine infauna using sediment microcosms.

Naturally occurring radioactive materials (NORMs) can be found in decommissioned oil and gas infrastructure (e.g. pipelines), including scales. The effects of NORM contaminants from offshore infrastructure on benthic macroorganisms remain poorly understood. To test the potential ecological effects of NORM-contaminated scale, we exposed a marine amphipod, a clam and a polychaete to marine sediments spiked with low level concentrations of barium sulfate scale retrieved from a decommissioned subsea pipe. Only amphipods were included in further analysis due to treatment mortalities of the clam and polychaete. Barium (Ba) and copper (Cu) were elevated in the seawater overlying the spiked sediments, although no sediment metals exceeded guidelines. 210Po was the only NORM detected in the overlying waters while both 210Po and 226Ra were significantly elevated in the scale-contaminated sediments when compared with the control sediments. The whole-body burden of Ba and 226Ra were significantly higher in the scale-exposed amphipods. Using experiment- and scale-specific parameters in biota dose assessments suggested potential dose rates may elicit individual and population level effects. Future work is needed to assess the biological impacts and effects of NORM scale at elevated levels above background concentrations and the accumulation of NORM-associated contaminants by marine organisms.

Controls on Barite (BaSO4) Precipitation in Unconventional Reservoirs.

Barite (BaSO4) precipitation is one of the most ubiquitous examples of secondary sulfate mineral scaling in shale oil and gas reservoirs. Often, a suite of chemical additives is used during fracturing operations to inhibit the accumulation of mineral scales, though their efficacy is widely varied and poorly understood. This study combines experimental data and multi-component numerical reactive transport modeling to offer a more comprehensive understanding of the geochemical behavior of barite accumulation in shale matrices under conditions typical of fracturing operations. A variety of additives and conditions are individually tested in batch reactor experiments to identify the factors controlling barite precipitation. Our experimental results demonstrate a pH dependence in the rate of barite precipitation, which we use to develop a predictive model including a pH-dependent term that satisfactorily reproduces our observations. This model is then extended to consider the behavior of three major shale samples of highly variable mineralogy (Eagle Ford, Marcellus, and Barnett). This data-validated model offers a reliable tool to predict and ultimately mitigate against secondary mineral accumulation in unconventional shale reservoirs.

Quantifying the subjective: length-to-height ratio characterizes achalasia esophageal tortuosity.

BACKGROUND: Esophageal morphology in achalasia is thought to affect outcomes, with "end-stage" sigmoidal morphology faring poorly; however, evaluation of morphology's role in outcomes has been limited by lack of objective characterization. Hence, the goals of this study were twofold: characterize the variability of timed barium esophagram (TBE) interpretation and evaluate an objective classification of TBE tortuosity: length-to-height ratio (LHR). We hypothesized that the esophagus must elongate to become sigmoidal such that sigmoidal morphology would demonstrate a larger LHR. METHODS: Ninety pre-operative TBEs were selected from an institutional database. Esophageal morphology was categorized as straight, intermediate, or sigmoidal. Esophageal length was measured by a mid-lumen line from the aortic knob to the esophagogastric junction on TBE; height was measured vertically from the aortic knob to the level of the esophagogastric junction. The length divided by the height generated the LHR. Descriptive statistics and frequency of expert agreement were calculated. Median LHR was compared between consensus morphologies. A receiver operating characteristic (ROC) determined the optimal LHR for sigmoidal vs non-sigmoidal characterization. RESULTS: From a total of 90 pre-operative TBEs, expert consensus morphology was reached in 56 (62.2%) cases. Pairs of experts agreed on morphology in 62-74% of TBEs, with all three experts agreeing on 46.7-48.9% of cases. Median LHR between expert consensus morphologies was 1.03, 1.09, and 1.24 for straight, intermediate, and sigmoidal morphologies, respectively (p < 0.001). ROC demonstrated that an LHR cutoff of 1.13 was 100% sensitive and 95% specific (AUC 0.99) for ruling out sigmoidal morphology. CONCLUSION: These findings confirm our anecdotal experience that subjective morphology interpretation is variable, even between experts at a high-volume center. LHR provides an objective method for classification, allowing us to overcome the limitations of inter-observer variability, thus paving the way for future study of the role of morphology in achalasia outcomes.

Assessment of 226Ra and U colloidal transport in a mining environment.

The colloidal transport of trace (Fe, Al, Ba, Pb, Sr, U) and ultra-trace (226Ra) elements was studied in a mining environment. An original approach combining 0.45 µm filtered water sampling, the Diffusive Gradient in Thin films (DGT) technique, mineralogical characterization, and geochemical modelling was developed and tested at 17 sampling points. DGT was used for the truly dissolved fraction of the elements of interest, while the 0.45 µm filtration includes both colloidal and truly dissolved fractions (together referred to as total dissolved fraction). Results indicated a colloidal fraction for Al (up to 50%), Ba (up to 86%), and Fe (up to 99%) explained by the presence of submicrometric grains of kaolinite, barite, and ferrihydrite, respectively. Furthermore, the total dissolved 226Ra concentration in the water samples reached up to 10-25 Bq/L (1.2-3.0 10-12 mol/L) at 3 sampling points, while the truly dissolved aqueous 226Ra concentrations were in the mBq/L range. Such high total dissolved concentrations are explained by retention on colloidal barite, accounting for 95% of the total dissolved 226Ra concentration. The distribution of 226Ra between the truly dissolved and colloidal fractions was accurately reproduced using a (Rax,Ba1-x)SO4 solid solution, with values of the Guggenheim parameter a0 close to ideality. 226Ra sorption on ferrihydrite and kaolinite, other minerals well known for their retention properties, could not explain the measured colloidal fractions despite their predominance. This illustrates the key role of barite in such environments. The measured concentrations of total dissolved U were very low at all the sampling points (<4.5 10-10 mol/L) and the colloidal fraction of U accounted for less than 65%. U sorption on ferrihydrite could account for the colloidal fraction. This original approach can be applied to other trace and ultra-trace elements to complement when necessary classical environmental surveys usually performed by filtration on 0.45 µm.

Effects of barium sulfate on rheological properties and IDDSI flow consistency of liquid stimuli prepared using commercial thickening powders.

During videofluoroscopic swallowing study (VFSS), barium sulfate (BaSO4 ) is commonly added into food samples as a radiopaque contrast media for bolus visualization and examination. Accordingly, the consistency and flow behavior of barium stimuli can differ significantly from their non-barium counterparts. Such differences may have a subsequent impact on the validity of VFSS. Therefore, in this study, effects of barium sulfate on the shear and extensional rheological properties and IDDSI (International Dysphagia Diet Standardization Initiative) flow consistency of liquids prepared using various commercial thickening powders were investigated. Results showed that all barium stimuli exhibited shear thinning behavior but with significantly higher shear viscosity compared to the non-barium counterparts. A shift factor of viscosity at shear rate 50 s-1 with values in range of 1.21-1.73 could be used to describe the increase in the viscosity for samples thickened with gum-based thickeners. However, the change in the viscosity was not invariant for the stimuli prepared starch-based thickener. The addition of BaSO4 had a negative impact on extensional properties of samples by demonstrating a faster filament rupture. The extent of impact on the decrease in filament breakup time was more pronounced in xanthan > guar gum ≈ tara gum-based thickeners. Based on the IDDSI flow test, no significant effect of BaSO4 was found on the gum-based thickeners, whereas there was a marked effect in the starch-based sample. These results can be used beneficially to assist clinicians in the dysphagia diagnosis for matching rheological properties of the barium stimuli to enhance effectiveness dysphagia interventions.

Barium sulphate microparticles are taken up by three different cell types: HeLa, THP-1, and hMSC.

Cytotoxicity and cellular uptake of spherical barium sulphate microparticles (diameter 1 µm) were studied with three different cell lines, i.e. THP-1 cells (monocytes; model for a phagocytosing cell line), HeLa cells (epithelial cells; model for a non-phagocytosing cell line), and human mesenchymal stem cells (hMSCs; model for non-phagocytosing primary cells). Barium sulphate is a chemically and biologically inert solid which allows to distinguish two different processes, e.g. the particle uptake and potential adverse biological reactions. Barium sulphate microparticles were surface-coated by carboxymethylcellulose (CMC) which gave the particles a negative charge. Fluorescence was added by conjugating 6-aminofluorescein to CMC. The cytotoxicity of these microparticles was studied by the MTT test and a live/dead assay. The uptake was visualized by confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). The particle uptake mechanism was quantified by flow cytometry with different endocytosis inhibitors in THP-1 and HeLa cells. The microparticles were easily taken up by all cell types, mostly by phagocytosis and micropinocytosis, within a few hours. STATEMENT OF SIGNIFICANCE: The interaction of particles and cells is of primary importance in nanomedicine, drug delivery, and nanotoxicology. It is commonly assumed that cells take up only nanoparticles unless they are able to phagocytosis. Here, we demonstrate with chemically and biologically inert microparticles of barium sulphate that even non-phagocytosing cells like HeLa and hMSCs take up microparticles to a considerable degree. This has considerable implication in biomaterials science, e.g. in case of abrasive debris and particulate degradation products from implants like endoprostheses.

Double-contrast barium enema is no longer justified as a backup examination for colonoscopy in the population screening program: Population study in an organized fecal immunochemical test-based screening program.

BACKGROUND AND AIM: Currently, some countries still acknowledge double-contrast barium enema (DCBE) as a backup confirmatory examination when colonoscopy is not feasible or incomplete in colorectal cancer (CRC) screening programs. This study aims to compare the performance of colonoscopy and DCBE in terms of the risk of incident CRC after negative results in the fecal immunochemical test (FIT)-based Taiwan Colorectal Cancer Screening Program. METHODS: Subjects who had positive FITs and received confirmatory exams, either colonoscopy or DCBE, without the findings of neoplastic lesions from 2004 to 2013 in the screening program comprised the study cohort. Both the colonoscopy and DCBE subcohorts were followed until the end of 2018 and linked to the Taiwan Cancer Registry to identify incident CRC cases. Multivariate analysis was conducted to compare the risk of incident CRC in both subcohorts after controlling for potential confounders. RESULTS: A total of 102 761 colonoscopies and 5885 DCBEs were performed after positive FITs without neoplastic findings during the study period. By the end of 2018, 2113 CRCs (2.7 per 1000 person-years) and 368 CRCs (7.6 per 1000 person-years) occurred in the colonoscopy and DCBE subcohorts, respectively. After adjusting for major confounders, DCBE had a significantly higher risk of incident CRC than colonoscopy, with an adjusted HR of 2.81 (95% CI = 2.51-3.14). CONCLUSIONS: In the FIT screening program, using DCBE as a backup examination was associated with a nearly threefold risk of incident CRC compared with colonoscopy, demonstrating that it is no longer justified as a backup examination for incomplete colonoscopy.

Sulfate supply decreases barium availability, uptake, and toxicity in lettuce plants grown in a tropical Ba-contaminated soil.

Barium (Ba) is a non-essential element that can cause toxicity in living organisms and environmental contamination. Plants absorb barium predominantly in its divalent cationic form Ba2+. Sulfur (S) can decrease the availability of Ba2+ in the soil by causing its precipitation as barium sulfate, a compound known for its very low solubility. The objective of this study was to evaluate the effect of soil sulfate supply in soil Ba fractions, as well as on plant growth, and Ba and S uptake by lettuce plants grown in artificially Ba-contaminated soil under greenhouse conditions. The treatments consisted of five Ba doses (0, 150, 300, 450, and 600 mg kg-1 Ba, as barium chloride) combined with three S doses (0, 40, and 80 mg kg-1 S, as potassium sulfate). The treatments were applied to soil samples (2.5 kg) and placed in plastic pots for plant cultivation. The Ba fractions analyzed were extractable-Ba, organic matter-Ba, oxides associated-Ba, and residual-Ba. The results indicate that the extractable-Ba fraction was the main one responsible for Ba bioavailability and phytotoxicity, probably corresponding to the exchangeable Ba in the soil. The dose of 80 mg kg-1 of S reduced extractable-Ba by 30% at higher Ba doses while it increased the other fractions. Furthermore, S supply attenuated the growth inhibition in plants under Ba exposure. Thus, S supply protected the lettuce plants from Ba toxicity by reduction of Ba availability in soil and plant growth enhancement. The results suggest that sulfate supply is a suitable strategy for managing Ba-contaminated areas.

Improvement of the Stability of IO3--, SeO32--, and SeO42--Coprecipitated Barite after Treatment with Phosphate.

Coprecipitation of radionuclides with barite has been studied to remove radionuclides from radioactive liquid waste because of its excellent removal efficiency; however, little information exists concerning the stability of the ions coprecipitated with barite. This study systematically investigated the stability of iodate, selenite, and selenate coprecipitated with barite via leaching tests. These oxyanions were gradually leached from the oxyanion-bearing barite into ultrapure water over time. Leaching of the oxyanions significantly increased in leaching solutions containing NaCl (pH 5.3), NaNO3 (pH 5.9), and Na2SO4 (pH 5.7). Conversely, leaching of the oxyanions was suppressed in KH2PO4 solution (pH 8.5), indicating that phosphate stabilized the oxyanion-bearing barite. The effect of phosphate treatment on oxyanion-bearing barite was further investigated. The results showed that the barite surface was modified with phosphate, and a thin surface layer of a barium phosphate-like structure was formed. The amount of oxyanions leached from the phosphate-treated samples into leaching solutions containing NaCl or NaNO3 was much lower than the amounts leached from the untreated barite samples into ultrapure water. The barite coprecipitation combined with subsequent phosphate treatment may be a promising method to efficiently remove iodate, selenite, and selenate from wastewater and stabilize them as barite coprecipitates.

Barium sulfate and pigment admixture for photoacoustic and x-ray contrast imaging of the gut.

Significance: X-ray imaging is frequently used for gastrointestinal imaging. Photoacoustic imaging (PAI) of the gastrointestinal tract is an emerging approach that has been demonstrated for preclinical imaging of small animals. A contrast agent active in both modalities could be useful for imaging applications. Aim: We aimed to develop a dual-modality contrast agent comprising an admixture of barium sulfate with pigments that absorb light in the second near-infrared region (NIR-II), for preclinical imaging with both x-ray and PAI modalities. Approach: Eleven different NIR-II dyes were evaluated after admixture with a 40% w/v barium sulfate mixture. The resulting NIR-II absorption in the soluble fraction and in the total mixture was characterized. Proof-of-principle imaging studies in mice were carried out. Results: Pigments that produced more uniform suspensions were assessed further for photoacoustic contrast signal at a wavelength of 1064 nm that corresponds to the output of the Nd:YAG laser used. Phantom imaging studies demonstrated that the pigment-barium sulfate mixture generated imaging contrast in both x-ray and PAI modalities. The optimal pigment selected for further study was a cyanine tetrafluoroborate salt. Ex-vivo and whole-body mouse imaging demonstrated that photoacoustic and x-ray contrast signals co-localized in the intestines for both imaging modalities. Conclusion: These data demonstrate that commercially-available NIR-II pigments can simply be admixed with barium sulfate to generate a dual-modality contrast agent appropriate for small animal gastrointestinal imaging.

Manipulation of Morphology, Particle Size of Barium Sulfate and the Interacting Mechanism of Methyl Glycine Diacetic Acid.

In this paper, methyl glycine diacetic acid (MGDA) was found to have great influence on the morphology and particle size of barium sulfate. The effects of additive, concentration, value of pH and reaction temperature on the morphology and particle size of barium sulfate were studied in detail. The results show that the concentration of reactant and temperature have little effect on the particle size of barium sulfate. However, the pH conditions of the solution and the dosage of MGDA can apparently affect the particle size distribution of barium sulfate. The particle size of barium sulfate particles increases and the morphology changes from polyhedral to rice-shaped with the decreasing of the dosage of MGDA. In solution with higher pH, smaller and rice-shaped barium sulfate was obtained. To investigate the interacting mechanism of MGDA, the binding energy between MGDA and barium sulfate surface was calculated. It was found that the larger absolute value of the binding energy would result in stronger growth inhibition on the crystal face. Finally, the experimental data and theoretical calculations were combined to elucidate the interacting mechanism of the additive on the morphology and particle size of barium sulfate.