Confined Growth of Highly Ordered Metal Atomic Arrays for Seawater Oxidation.

Metal atom catalysts have been among the most important research objects due to their specific physical and chemical properties. However, precise control of the anchoring of metal atoms is still challenging to achieve. Cobalt and iridium atomic arrays formed sequentially ordered stable arrays in graphdiyne (GDY) triangular cavities depending on their intrinsic chemical properties and interactions. The success of this method was attributed to multifunctional integration of GDY, enabling selective growth from one to several atoms and various atomic densities. The bimetallic atom arrays show several advantages resulting from reducibility of acetylene bonds, space limiting effect, incomplete charge transfer between GDY and metal atoms, and sp-C hybridized triple bond skeleton. This well-designed system exhibits unprecedented oxygen evolution reaction (OER) performance with a mass activity of 2.6 A mgcat.-1 at a low overpotential of 300 mV, which is 216.6 times higher than the state-of-the-art IrO2 catalyst, and long-term stability.

Self-Organized Gradually Single-Atom-Layer of Metal Osmium for an Unprecedented Hydrogen Production from Seawater.

Atomic thick two-dimensional (2D) materials with exciting physical, chemical, and electronic properties are gaining increasing attention in next-generation science and technology, showing great promise in catalysis and energy science. However, the precise design and synthesis of efficient catalytic systems based on such materials still face many difficulties, especially in how to control the preparation of structurally determined, highly active, atomic-scale distribution of material systems. Here, we report that a highly active zerovalent osmium single-atom-layer with a thickness of single atom size has been successfully and controllably self-organized on the surface of 2D graphdiyne (GDY) material. Detailed characterizations showed that the incomplete charge transfer effect between the Os atoms and GDY not only stabilized the catalytic system but also improved the intrinsic activity, making the Gibbs free energy reach the best and resulting in remarkable performance with a small overpotential of 49 mV at 500 mA cm-2, large specific j0 of 18.6 mA cm-2, and turnover frequency of 3.89 H2 s-1 at 50 mV. In addition, the formation of sp-C-Os bonds guarantees the high long-term stability of 800 h at a large current density of 500 mA cm-2 in alkaline simulated seawater.

Controllable Assembly of Highly Oxidized Cobalt on Graphdiyne Surface for Efficient Conversion of Nitrogen into Nitric Acid.

The manufacture of nitric acid (HNO3 ) consumes large amounts of energy and causes serious environmental pollution. Electrochemical synthesis is regarded as a key way to eliminate carbon emissions from the chemicals industry. The selective electrosynthesis of HNO3 from nitrogen was achieved by controllable assembly of cobalt metal on graphdiyne surface using a powerful tool of electrochemistry at ambient conditions. As an advanced material, graphdiyne (GDY) has a large conjugated structure on its surface and is rich in sp-C triple bond skeleton, which can achieve strong interaction with metal atoms, resulting in incomplete charge transfer between graphdiyne and cobalt atoms. The experimental and theoretical calculation results show that the highly oxidized cobalt on graphdiyne (HOCo/GDY) can selectively and efficiently activate and convert the nitrogen into the key intermediate *NO, which promotes the efficient overall conversion performance of nitrogen to nitric acid. Thus, the highest nitric acid yield (192.0 µg h-1 mg-1 ) and Faradaic efficiency (21.5 %) were achieved at low potentials.

Mapping out the bibliometric characteristics of classic articles published in a Taiwanese academic journal in dentistry: A scopus-based analysis.

Background/purpose: Since its inception, the Journal of Dental Sciences (JDS) has aimed to publish quality articles relevant to all fields in dentistry. The purpose of this study was to analyze the bibliometric characteristics and dissected associated factors correlated with citation counts of classic articles published in the JDS. Materials and method: Scopus® database was used to search the qualified articles published in JDS from 2009 to 2021. The bibliometric parameters, including journal impact factor (JIF), self-citation, study design, research field, geographic, country and institute of origin, inter-institute, inter-nation collaboration, keywords hotness and associated factors correlated with citation counts of classic articles were analyzed. Results: One hundred and eight articles from Scopus® database were eligible for analysis. The citation counts of classic articles ranged from 12 to 192, the average citation was 22.02. The most common study design was the in vitro/in vivo, followed by the cross-sectional study, and the major research field were Dental Materials. The most productive country and institute is Taiwan, and Chung Shan Medical University, respectively. The trend of inter-institute (71.03%) and inter-nation (11.22%) collaboration steadily increased since 2009. By using the multivariable linear regression model, Preventive and Community Dentistry in the research field significantly increased the citation counts. Conclusion: Despite its limitations, the escalating trends in JIFs, and JIFs without self-citations, and inter-nation and inter-institute collaboration of classic articles were noticed. Of all the dissected associated factors, Preventive and Community Dentistry in the research field significantly increased the citation counts of classic article.

Highly Selective Electrocatalytic Olefin Hydrogenation in Aqueous Solution.

Selective hydrogenation of olefins with water as the hydrogen source at ambient conditions is still a big challenge in the field of catalysis. Herein, the electrocatalytic hydrogenation of purely aliphatic and functionalized olefins was achieved by using graphdiyne based copper oxide quantum dots (Cux O/GDY) as cathodic electrodes and water as the hydrogen source, with high activity and selectivity in aqueous solution at high current density under ambient temperature and pressure. In particular, the sp-/sp2 -hybridized graphdiyne catalyst allows the selective hydrogenation of cis-trans isomeric olefins. The chemical and electronic structure of the GDY results in the incomplete charge transfer between GDY and Cu atoms to optimize the adsorption/desorption of the reaction intermediates and results in high reaction selectivity and activity for hydrogenation reactions.

Two-Dimensional Carbon Graphdiyne: Advances in Fundamental and Application Research.

Graphdiyne (GDY), a rising star of carbon allotropes, features a two-dimensional all-carbon network with the cohybridization of sp and sp2 carbon atoms and represents a trend and research direction in the development of carbon materials. The sp/sp2-hybridized structure of GDY endows it with numerous advantages and advancements in controlled growth, assembly, and performance tuning, and many studies have shown that GDY has been a key material for innovation and development in the fields of catalysis, energy, photoelectric conversion, mode conversion and transformation of electronic devices, detectors, life sciences, etc. In the past ten years, the fundamental scientific issues related to GDY have been understood, showing differences from traditional carbon materials in controlled growth, chemical and physical properties and mechanisms, and attracting extensive attention from many scientists. GDY has gradually developed into one of the frontiers of chemistry and materials science, and has entered the rapid development period, producing large numbers of fundamental and applied research achievements in the fundamental and applied research of carbon materials. For the exploration of frontier scientific concepts and phenomena in carbon science research, there is great potential to promote progress in the fields of energy, catalysis, intelligent information, optoelectronics, and life sciences. In this review, the growth, self-assembly method, aggregation structure, chemical modification, and doping of GDY are shown, and the theoretical calculation and simulation and fundamental properties of GDY are also fully introduced. In particular, the applications of GDY and its formed aggregates in catalysis, energy storage, photoelectronic, biomedicine, environmental science, life science, detectors, and material separation are introduced.

The impact of smoking on peri-implant microbiota: A systematic review.

OBJECTIVES: Peri-implantitis is associated with bacterial plaque biofilms and with patients who have a history of periodontitis. Smoking is a risk factor for periodontitis, but the relationship between smoking and peri­implantitis is unclear. The aim of this systematic review was to assess evidence ascertaining the relationship between smoking and peri­implant microbiota. DATA SOURCES: An electronic search was conducted in the MEDLINE/PubMed, Embase and Scopus® databases in duplicate up to January 2023 without language restrictions. Studies were considered eligible for inclusion if they involved evaluation of the peri­implant microbiota of smokers and nonsmokers. Methodological quality was assessed with the adapted Newcastle-Ottawa scale. STUDY SELECTION: Fourteen studies were identified for inclusion in the present study, and 85.7% of the studies were defined as medium to high methodological quality. Overall, the evidence presented in this review was limited to medium to high methodological quality. The data indicates that significantly higher frequencies of anaerobic pathogens are detectable in healthy peri­implant tissues of smokers. A lower diversity of microbiota was observed in healthy peri­implant sites of smokers. In the transition from clinically healthy to a diseased status, smoking shaped a reduced peri­implant microbiota by depleting commensal and enriching pathogenic species. CONCLUSIONS: The composition of peri­implant microbiota may be influenced by smoking. More studies are needed to determine the impact of smoking on peri­implant microbiota. CLINICAL SIGNIFICANCE: In the transition from clinically healthy to a diseased status, smoking shaped a reduced peri­implant microbiota by depleting commensal and enriching pathogenic species. The composition of peri­implant microbiota may be influenced by smoking.

Natural killer cells promote intra-cellular-infected trophoblasts survival via APOD-LRP1 axis.

Natural killer (NK) cells are known for their potent ability to kill stressed cells, whereas host cells infected with intra-cellular bacteria may also be benefit from the selective killing function of NK cells and survive. The mechanism of how NK cells protect host cells infected with intra-cellular bacteria is still unclear. Here, we discovered that decidual NK (dNK) cells cannot only eliminate intra-cellular bacteria which infected trophoblasts, but can also synthesize more lipids and transport lipids to trophoblasts to avoid their apoptosis. Mechanically, NK cells synthesize more lipids accompanied by increasing expression of apolipoprotein APOD. Lipids in NK cells can be delivered to trophoblast cells through APOD, maintaining adequate lipid droplet content and lipid metabolism homeostasis in trophoblasts. Blocking the APOD receptor LRP1 abolished lipid transport from NK cells to trophoblasts, and the reduction of lipid droplets caused by bacterial infection in trophoblast cells could not be restored, culminating in cell apoptosis. Our study provides new evidence for the immune surveillance and protective effect of NK cells on embryos during early pregnancy.

Flexible, Multifunctional Micro-Sensor Applied to Internal Measurement and Diagnosis of Vanadium Flow Battery.

The vanadium redox flow battery (VRFB) system is an emerging energy storage technology with many advantages, such as high efficiency, long life, and high safety. However, during the power-generation process, if local high temperature is generated, the rate of ions passing through the membrane will increase. In addition, it will also cause vanadium pentoxide molecules (V2O5) to exist in the solid state. Once the solid is formed, it will affect the flow of the vanadium electrolyte, which will eventually cause the temperature of the VRFB to continue to rise. According to the various physical parameters of VRFB shown in the literature, they have a significant impact on the efficiency and life of VRFB. Therefore, this research proposes to develop flexible multifunction (voltage, current, temperature, and flow) micro-sensors using micro-electro-mechanical systems (MEMS) technology to meet the need for real-time micro-diagnosis in the VRFB. The device is embedded in the VRFB of real-time microscopic sensing and diagnosis. Its technical advantages are: (1) it can simultaneously locally measure four physical quantities of voltage, current, temperature, and flow; (2) due to its mall size it can be accurately embedded; (3) the high accuracy and sensitivity provides it with a fast response time; and (4) it possesses extreme environment resistance.

Molecular dynamics simulation guided distal mutation of Thermotoga naphthophila ß-glucosidase for significantly enhanced synthesis of galactooligosaccharides and expanded product scope.

For efficient enzymatic production of health-beneficial galactooligosaccharides (GOSs), a glycone (-1)/aglycone (+2) subsite mutation strategy to engineer a thermophilic GH1 ß-glucosidase (Tn0602) from Thermotoga naphthophila RKU-10 was introduced. Six single mutation variants (F226G, N246G, N246E, N222F, N222Y, G224T) and two double mutants (F226GF414S, F226GF414Y) were designed. The +2-subsite variant F226G produced 136 mM galactooligosaccharide 1.2-fold more than the wild type (115 mM). More significantly, a superimposed mutation of the -1/+2 subsites F226G/F414S gave a total GOS production of 314 mM (82.16% lactose conversion), 2.7-fold higher than the total GOS production of the wild type. Furthermore, the variant F226GF414S was profiled 241 mM of trisaccharide (galß (1 â†’ 3)/(1 â†’ 4) lactose) and 73 mM tetrasaccharide (galß (1 â†’ 3)/(1 â†’ 4) galß (1 â†’ 3)/(1 â†’ 4) lactose). According to a 300-ns molecular dynamic simulation, the superimposed mutation increased GOS productivity and expanded the scope of products by changing the structural flexibility and reducing the steric hindrance of the substrate tunnel. Overall, our study successfully demonstrated that a - 1/+2 subsite mutagenesis method could be used in ß-glucosidases Tn0602 to improve enzyme productivity and expand product scope, which could be a potential route to evolve retaining glycosidases towards the desired direction.

Gaussian Accelerated Molecular Dynamics Simulations Investigation on the Mechanism of Angiotensin-Converting Enzyme (ACE) C-Domain Inhibition by Dipeptides.

Angiotensin-converting enzyme (ACE)-inhibitory peptides extracted from food proteins can lower blood pressure by inhibiting ACE activity. A recent study showed that the inhibitory activity of IY (Ile-Tyr, a dipeptide derived from soybean protein) against ACE was much higher than that of LL (Leu-Leu), although they had similar hydrophobic and predicted activity values. It was difficult to reveal the deep molecular mechanism underlying this phenomenon by traditional experimental methods. The Apo and two complex systems (i.e., ACE-LL and ACE-IY) were therefore subjected to 1 µs long Gaussian accelerated molecular dynamics (GaMD) simulations. The results showed that the binding of IY can cause obvious contraction of the active site of ACE, mainly manifested by a significant lateral shift of α13, α14, and α15. In addition, hinge 2 and hinge 3 were more stable in the ACE-IY system, while these phenomena were not present in the ACE-LL system. Moreover, the α10 of the IY-bound ACE kept an inward state during the simulation progress, which facilitated the ACE to remain closed. However, for the LL-bound ACE, the α10 switched between two outward states. To sum up, our study provides detailed insights into inhibitor-induced conformational changes in ACE that may help in the design of specific inhibitors targeting ACE for the treatment of hypertension.

A Possible Mechanism of Graphene Oxide to Enhance Thermostability of D-Psicose 3-Epimerase Revealed by Molecular Dynamics Simulations.

Thermal stability is a limiting factor for effective application of D-psicose 3-epimerase (DPEase) enzyme. Recently, it was reported that the thermal stability of DPEase was improved by immobilizing enzymes on graphene oxide (GO) nanoparticles. However, the detailed mechanism is not known. In this study, we investigated interaction details between GO and DPEase by performing molecular dynamics (MD) simulations. The results indicated that the domain (K248 to D268) of DPEase was an important anchor for immobilizing DPEase on GO surface. Moreover, the strong interactions between DPEase and GO can prevent loop α1'-α1 and ß4-α4 of DPEase from the drastic fluctuation. Since these two loops contained active site residues, the geometry of the active pocket of the enzyme remained stable at high temperature after the DPEase was immobilized by GO, which facilitated efficient catalytic activity of the enzyme. Our research provided a detailed mechanism for the interaction between GO and DPEase at the nano-biology interface.

A bibliometric analysis of top 100 most-cited articles in dentistry with author(s) affiliated with Taiwan institutes.

BACKGROUND: Citation analysis can provide a historical perspective in the advancement of research, evolution, and areas of research. Taiwan exhibits rigorous academic and scientific activities in dentistry; however, based on its empirical contribution in research, there is no report in the literature analyzing the top-cited articles published by authors affiliated with Taiwan institutes. The purpose of this study was to analyze the citation characteristics of the top 100 most-cited articles published in dentistry with author(s) affiliated with Taiwan institutes. METHODS: The Scopus database was used to search the qualified articles with authors from Taiwan published in journals. The bibliometric parameters, including year of publication, study design, research fields, citation half-life, self-citation, institute of origin, and international collaboration were analyzed. Multivariable linear regression in generalized linear model was used to find associate factors related to trends of citation counts. RESULTS: The top 100 most-cited articles were determined by analyzing 7667 articles from the Scopus database. The steadily increasing trends were observed in the number and percentage of articles of author(s) affiliated with Taiwan institutes to the world. The most common study design was the in vitro research (55 %). The majority citation half-life is 3-5 and 6-8 years, and self-citation counts were between one to five times (n = 26). The percentage of international collaboration of these most-cited articles was 32%, and the main collaboration country was the United States. By using multivariable linear regression in the generalized linear model, the associated factors, study design, and self-citation were significantly associated with the escalating trends of citation counts. CONCLUSION: This is the first study that provides valuable information in the dentistry regarding the academic activity, and empirical contribution of author(s) affiliated with Taiwan institutes in the world. The trends of citation characteristics were significantly correlated with study design and self-citation of these articles.

Conformational Changes of Glutamine 5'-Phosphoribosylpyrophosphate Amidotransferase for Two Substrates Analogue Binding: Insight from Conventional Molecular Dynamics and Accelerated Molecular Dynamics Simulations.

Glutamine 5'-phosphoribosylpyrophosphate amidotransferase (GPATase) catalyzes the synthesis of phosphoribosylamine, pyrophosphate, and glutamate from phosphoribosylpyrophosphate, as well as glutamine at two sites (i.e., glutaminase and phosphoribosylpyrophosphate sites), through a 20 Å NH3 channel. In this study, conventional molecular dynamics (cMD) simulations and enhanced sampling accelerated molecular dynamics (aMD) simulations were integrated to characterize the mechanism for coordination catalysis at two separate active sites in the enzyme. Results of cMD simulations illustrated the mechanism by which two substrate analogues, namely, DON and cPRPP, affect the structural stability of GPATase from the perspective of dynamic behavior. aMD simulations obtained several key findings. First, a comparison of protein conformational changes in the complexes of GPATase-DON and GPATase-DON-cPRPP showed that binding cPRPP to the PRTase flexible loop (K326 to L350) substantially effected the formation of the R73-DON salt bridge. Moreover, only the PRTase flexible loop in the GPATase-DON-cPRPP complex could remain closed and had sufficient space for cPRPP binding, indicating that binding of DON to the glutamine loop had an impact on the PRTase flexible loop. Finally, both DON and cPRPP tightly bonded to the two domains, thereby inducing the glutamine loop and the PRTase flexible loop to move close to each other. This movement facilitated the transfer of NH3 via the NH3 channel. These theoretical results are useful to the ongoing research on efficient inhibitors related to GPATase.

Molecular Dynamic Simulations of Bromodomain and Extra-Terminal Protein 4 Bonded to Potent Inhibitors.

Bromodomain and extra-terminal domain (BET) subfamily is the most studied subfamily of bromodomain-containing proteins (BCPs) family which can modulate acetylation signal transduction and produce diverse physiological functions. Thus, the BET family can be treated as an alternative strategy for targeting androgen-receptor (AR)-driven cancers. In order to explore the effect of inhibitors binding to BRD4 (the most studied member of BET family), four 150 ns molecular dynamic simulations were performed (free BRD4, Cpd4-BRD4, Cpd9-BRD4 and Cpd19-BRD4). Docking studies showed that Cpd9 and Cpd19 were located at the active pocket, as well as Cpd4. Molecular dynamics (MD) simulations indicated that only Cpd19 binding to BRD4 can induce residue Trp81-Ala89 partly become α-helix during MD simulations. MM-GBSA calculations suggested that Cpd19 had the best binding effect with BRD4 followed by Cpd4 and Cpd9. Computational alanine scanning results indicated that mutations in Phe83 made the greatest effects in Cpd9-BRD4 and Cpd19-BRD4 complexes, showing that Phe83 may play crucial roles in Cpd9 and Cpd19 binding to BRD4. Our results can provide some useful clues for further BCPs family search.

Effects of water matrices on the degradation of naproxen by reactive radicals in the UV/peracetic acid process.

The UV/peracetic acid (UV/PAA) process as a novel advanced oxidation process has been reported to produce carbon-centered radicals (RC•) for Naproxen (NAP) degradation, which is a representative of naphthyl structure substances. Real water matrices, such as carbonate and bicarbonate ions (CO32-/HCO3-), humic acid (HA), and chloride ion (Cl-), may react with these reactive radicals and change their contributions to NAP degradation. The results showed that RC• contributed 60.8% and •OH contributed 39.2% to NAP degradation in pure water by a competition method. CO32-/HCO3- (0-20 mM) showed minimal effect on NAP degradation in the UV/PAA process, meanwhile, it has observable inhibition effect on NAP degradation in the UV/H2O2 process (mainly of •OH) and minimal effect in the UV/PAA process with tert-butanol (TBA) (mainly of RC•). Results suggested that CO32-/HCO3- could react with •OH yielding CO3•- with low reactivity to NAP, CO3•- could further react with PAA to produce RC•. This speculation was confirmed by the increased contribution of RC• to NAP degradation with the increase of CO32-/HCO3- concentration through the competition method. HA (0-5 mg/L) had a higher scavenging capacity for RC• than •OH because HA with naphthyl structure was likely to be attacked by RC•. Cl- (0-200 mM) had little effect on NAP degradation in the UV/PAA and UV/H2O2 processes, while exerted an observable inhibition on NAP degradation in the UV/PAA process with TBA. This finding suggested that Cl- could react with RC• to produce Cl•, which could further convert into HOCl•-, and then excess •OH was formed. The new knowledge on the conversion of reactive radicals obtained in this study provides an important basis for facilitating further research on the UV/PAA advanced oxidation.

Evaluating the urate-lowering effects of different microbial fermented extracts in hyperuricemic models accompanied with a safety study.

Uric acid (UA) is an end product of purine metabolism by the enzyme xanthine oxidase (XOD). Hyperuricemia is characterized by the accumulation of serum UA and is an important risk factor for gout and many chronic disorders. XOD inhibitors or uricase (catalyzes UA to the more soluble end product) can prevent these chronic diseases. However, currently available hypouricemic agents induce severe side effects. Therefore, we developed new microbial fermented extracts (MFEs) with substantial XOD inhibition activity from Lactobacillus (MFE-21) and Acetobacter (MFE-25), and MFE-120 with high uricase activity from Aspergillus. The urate-lowering effects and safety of these MFEs were evaluated. Our results showed that MFE-25 exerts superior urate-lowering effects in the therapeutic model. In the preventive model, both MFE-120 and MFE-25 significantly reduced UA. The results of the safety study showed that no organ toxicity and no treatment-related adverse effects were observed in mice treated with high doses of MFEs. Taken together, the results showed the effectiveness of MFEs in reducing hyperuricemia without systemic toxicity in mice at high doses, suggesting that they are safe for use in the treatment and prevention of hyperuricemia.

Linewidth enhancement factor in semiconductor lasers subject to various external optical feedback conditions.

The linewidth enhancement factor α of a semiconductor laser under the influences of optical feedback with different feedback strengths, external cavity lengths, and feedback phases are studied both experimentally and theoretically. The value of α is determined from the minimum of the Hopf bifurcation curve when the laser is subject to both optical feedback and optical injection. In the experiment, a pellicle beamsplitter mounted on a PZT stage placed on a linear translation stage is used as the reflector, where the external cavity length can be adjusted continuously from the long cavity regime to the short cavity regime with phase accuracy. With a moderate feedback strength, α is found to increase as the feedback strength increases. Moreover, while α is insensitive to the feedback phase in the long cavity regime, it can be tuned continuously in the short cavity regime when varying the phase. A normalized variation range of 21.59% is obtained experimentally at an external cavity length of 1.5 cm, which can be further enhanced by shortening the external cavity. To the best of our knowledge, this is the first detailed study of α from the long to the short cavity regime in a semiconductor laser subject to optical feedback. More particularly, the continuous tuning of α under phase variation is demonstrated the first time.

[Breast- and bottle-feeding in preterm infants: a comparison of behavioral cues].

BACKGROUND: Developmental care has been broadly applied to identify the behavioral cues and care needs of preterm infants. Past studies indicate a significantly higher level of physical distress in bottle-fed preterm infants than in preterm infants who are breastfed. However, no evidence has yet been reported that supports the influence of feeding methods on behavioral cues. PURPOSE: This study compares differences in the type and frequency of behavioral cues between breast- and bottle-fed preterm infants. METHODS: A comparison study design and secondary data analysis method were used to assess data from two previous research projects. Infant feeding behavioral cues were observed and compared between two groups: 7 preterm infants who were breastfed and 7 preterm infants who were bottle-fed. After cases were matched by infant gestational age, behavioral responses were coded according to the preterm feeding cues coding system (PFCCS) from 7 paired maternal-infant feeding videos that featured preterm infants of 25 to 32 weeks gestational age at birth. RESULTS: The PFCCS classifies 24 feeding behavioral cues into hunger cues, self-regulatory cues, stress cues, and satiety cues. Infants in the breastfeeding group had a higher hunger cue frequency than their bottle-fed peers (p = .013), while bottle-fed infants had a higher stress cue frequency than their breastfed peers (p = .041). Other significant differences in behavioral cues between the two feeding methods included "fluid spillage" (bottle- >breast-, p = .008), "central cyanosis" (bottle- >breast-, p = .024) and "hand pushing" (breast- >bottle-, p = .034). CONCLUSIONS/IMPLICATIONS FOR PRACTICE: Preterm infants in this study who breastfed showed significantly fewer stress cues than those who bottle fed. These findings support the importance of enhancing care provider sensitivity with regard to behavioral-cue observation. Findings further support breastfeeding rather than bottle-feeding for preterm infants.