Associations of anxiety and fatigue with hazardous occupational conditions of Korean nurses in early pregnancy: A cross-sectional study.

AIM: To identify occupational conditions associated with anxiety and fatigue among Korean nurses in early pregnancy. BACKGROUND: Pregnant nurses, like non-pregnant hospital nurses, are exposed to dangerous and stressful work environments, which can affect fatigue and anxiety. DESIGN AND METHODS: This cross-sectional study enrolled 1490 nurses who participated in the early pregnancy module in the Korea Nurses' Health Study between 2014 and 2020. Hierarchical linear regression analyses were employed to identify the factors associated with anxiety and fatigue among nurses in early pregnancy. RESULTS: One-fifth of participants were working night shifts, and more than two-thirds were working overtime. When using antineoplastic drugs and disinfectants, the rate of use of protective equipment varied depending on the size of the hospital. Working overtime and lifting heavy objects were associated with increased anxiety and fatigue among nurses. CONCLUSION: Overtime work was associated with both anxiety and fatigue among pregnant nurses. Pregnant hospital nurses were exposed to both night shift and overtime work. Therefore, hospital managers should improve hazardous working environments to protect the health of nurses in early pregnancy and their fetuses.

Exploring the impact of water on the morphology and crystallinity of xylan hydrate nanotiles.

There has been a resurgence of studies on xylan particles describing various properties and exploring new applications. The aim of this study was to analyze xylan hydrate crystals in the wet state and after air-drying using state-of-art imaging techniques in order to assess the impact of water on both crystallinity and particle morphology. Xylan from esparto grass (Stipa tenacissima) was crystallized and formed convex platelets, termed 'nanotiles'. Fully hydrated xylan crystals were examined in a layer of vitreous ice by cryogenic electron microscopy. Selected area electron diffraction of the xylan hydrate crystals revealed an oriented crystalline core, unlike the dried crystals that showed no orientation. The surface topographies and thickness of wet and air-dried xylan nanotiles were observed using atomic force microscopy imaging in both liquid and in air. X-ray diffraction was used to assess the crystallinity of xylan nanotiles after drying to varying levels. Air-dried crystals gave diffraction maxima corresponding to xylan hydrate, while wet crystals gave diffraction maxima corresponding to xylan dihydrate. This study offers new insight into xylan hydrate particles, focusing on the role of water on their crystallinity, ultrastructure, and orientation of the crystalline layers.

Functional Lignin Building Blocks: Reactive Vinyl Esters with Acrylic Acid.

Introducing vinyl groups onto the backbone of technical lignin provides an opportunity to create highly reactive renewable polymers suitable for radical polymerization. In this work, the chemical modification of softwood kraft lignin was pursued with etherification, followed by direct esterification with acrylic acid (AA). In the first step, phenolic hydroxyl and carboxylic acid groups were derivatized into aliphatic hydroxyl groups using ethylene carbonate and an alkaline catalyst. The lignin was subsequently fractionated using a downward precipitation method to recover lignin of defined molar mass and solubility. After recovery, the resulting material was then esterified with AA, resulting in lignin with vinyl functional groups. The first step resulted in approximately 90% of phenolic hydroxyl groups being converted into aliphatic hydroxyls, while the downward fractionation resulted in three samples of lignin with defined molar masses. For the esterification reaction, the weight ratio of reagents, reaction temperature, and reaction time were evaluated as factors that would influence the modification efficacy. 13C NMR spectroscopy analysis of lignin samples before and after esterification showed that the optimized reaction conditions could reach approximately 40% substitution of aliphatic hydroxyl groups. Both steps only used lignin and the modifying reagent (no solvent), with the possibility of recovery and reuse of the reagent by dilution and distillation. An additional second esterification step of the resulting lignin sample with acetic acid or propionic acid converted 90% of remaining hydroxyl groups into short-chain carbon aliphatic esters, making a hydrophobic material suitable for further copolymerization with synthetic hydrophobic monomers.

Revisiting the Molar Mass and Conformation of Derivatized Fractionated Softwood Kraft Lignin.

The limited utilization of reliable tools and standards for determination of the softwood kraft lignin molar mass and the corresponding molecular conformation hampers elucidation of the structure-property relationships of lignin. At issue, conventional size exclusion chromatography (SEC) is unable to robustly measure the molar mass because of a lack of calibration standards with a similar structure to lignin. In the present work, the determination of the absolute molar mass of acetylated technical lignin was revisited utilizing SEC combined with multi-angle light scattering with a band pass filter to suppress the fluorescence. Fractionated lignin isolated using sequential techniques of solvent and membrane methods was used to enhance the clarity of light-scattering profiles by narrowing the molar mass distribution of lignin fractions. Further information on the molecular conformation of derivatized samples was studied utilizing a differential viscometer, and chemical structures were identified by NMR spectroscopy analysis. Through the help of fractionation, intrinsic viscosity values were determined for the different fractions as a function of molecular weight cut-off membranes. The derivatized acetone-soluble lignin was found to possess a lower molecular weight and an extremely compact structure relative to the derivatized acetone-insoluble fraction based on a significantly lower "α" value in the Mark-Houwink-Sakurada plot (0.15 acetone-soluble vs 0.33 acetone-insoluble). The differences in geometry were supported by the linkage analysis from NMR showing the acetone-soluble part containing fewer native linkages. In both of these examples, kraft lignin behaved like a solid sphere, limiting the ability to provide entanglements between molecular chains. From this standpoint, macroscopic properties of lignin are justified with this knowledge of a dense and extremely compact structure.

Influence of Irritable Bowel Syndrome on Stress and Depressive Symptoms in Nurses: The Korea Nurses' Health Study.

Despite the high risk of irritable bowel syndrome (IBS) and stress/depressive symptoms in nurses, limited research has examined the relationship between these conditions in female nurses. The purpose of this study was to determine the prevalence of IBS and the influence of IBS on stress and depressive symptoms in female nurses. We analyzed the data from the Korea Nurses' Health Study. Among 7667 participants from the 7th survey conducted from December 2018 to September 2019, 178 nurses were identified as having IBS based on the Rome IV criteria. Using the propensity score matching, 712 were selected as a comparison group. Multivariate ordinal logistic regression analyses were conducted to examine the influence of IBS on stress and depressive symptoms. The prevalence of IBS was 2.3% and the prevalence of depressive symptoms among nurses with IBS was 13.5%. Female nurses with IBS were 2.214 times more likely to experience increased stress levels. However, when demographics, dietary habits, sleep quality, and depressive symptoms were considered, having IBS was no longer an influential factor for increased stress levels. When all the variables were considered, female nurses with IBS were still 2.205 times more likely to experience depressive symptoms. Adequate support is needed to relieve depressive symptoms in nurses with IBS.

Bacterial Transformation of Aromatic Monomers in Softwood Black Liquor.

The valorization of lignin, a major component of plant-derived biomass, is essential to sustainable biorefining. We identified the major monoaromatic compounds present in black liquor, a lignin-rich stream generated in the kraft pulping process, and investigated their bacterial transformation. Among tested solvents, acetone extracted the greatest amount of monoaromatic compounds from softwood black liquor, with guaiacol, vanillin, and acetovanillone, in an approximately 4:3:2 ratio, constituting ~90% of the total extracted monoaromatic content. 4-Ethanol guaiacol, vanillate, and 4-propanol guaiacol were also present. Bacterial strains that grew on minimal media supplemented with the BL extracts at 1mM total aromatic compounds included Pseudomonas putida KT2442, Sphingobium sp. SYK-6, and Rhodococcus rhodochrous EP4. By contrast, the extracts inhibited the growth of Rhodococcus jostii RHA1 and Rhodococcus opacus PD630, strains extensively studied for lignin valorization. Of the strains that grew on the extracts, only R. rhodochrous GD01 and GD02, isolated for their ability to grow on acetovanillone, depleted the major extracted monoaromatics. Genomic analyses revealed that EP4, GD01, and GD02 share an average nucleotide identity (ANI) of 98% and that GD01 and GD02 harbor a predicted three-component carboxylase not present in EP4. A representative carboxylase gene was upregulated ~100-fold during growth of GD02 on a mixture of the BL monoaromatics, consistent with the involvement of the enzyme in acetovanillone catabolism. More generally, quantitative RT-PCR indicated that GD02 catabolizes the BL compounds in a convergent manner via the ß-ketoadipate pathway. Overall, these studies help define the catabolic capabilities of potential biocatalytic strains, describe new isolates able to catabolize the major monoaromatic components of BL, including acetovanillone, and facilitate the design of biocatalysts to valorize under-utilized components of industrial lignin streams.

Tailoring renewable materials via plant biotechnology.

Plants inherently display a rich diversity in cell wall chemistry, as they synthesize an array of polysaccharides along with lignin, a polyphenolic that can vary dramatically in subunit composition and interunit linkage complexity. These same cell wall chemical constituents play essential roles in our society, having been isolated by a variety of evolving industrial processes and employed in the production of an array of commodity products to which humans are reliant. However, these polymers are inherently synthesized and intricately packaged into complex structures that facilitate plant survival and adaptation to local biogeoclimatic regions and stresses, not for ease of deconstruction and commercial product development. Herein, we describe evolving techniques and strategies for altering the metabolic pathways related to plant cell wall biosynthesis, and highlight the resulting impact on chemistry, architecture, and polymer interactions. Furthermore, this review illustrates how these unique targeted cell wall modifications could significantly extend the number, diversity, and value of products generated in existing and emerging biorefineries. These modifications can further target the ability for processing of engineered wood into advanced high performance materials. In doing so, we attempt to illuminate the complex connection on how polymer chemistry and structure can be tailored to advance renewable material applications, using all the chemical constituents of plant-derived biopolymers, including pectins, hemicelluloses, cellulose, and lignins.

Predictors of actual turnover among nurses working in Korean hospitals: A nationwide longitudinal survey study.

AIM: To examine the factors affecting actual turnover among nurses working in hospitals using the Brewer-Kovner synthesis model. BACKGROUND: To increase retention of nurses, it is important to understand factors contributing to actual turnover among nurses. METHODS: A longitudinal study design was utilized with 2,633 of 20,613 eligible female hospital nurses who participated in Korea Nurses' Health Study. We created two age groups: a younger group (20-35 years) and an older group (36-49 years). Multivariate logistic regression was used to identify the factors influencing turnover by age group. RESULTS: Pregnancy and childbirth increased young nurses' turnover. When we excluded intent to leave, depression and burnout were significant factors affecting young nurses' turnover. Salary and hospital size were factors predicting nurse turnover among nurses older than 36 years. CONCLUSIONS: It is essential to develop prevention strategies of female nurse turnover based on the age group in Korea. IMPLICATIONS FOR NURSING MANAGEMENT: Nurse managers and health care institutes need to develop new managerial and policy strategies to reduce nurse turnover in each age group.

Factors affecting frontline Korean nurses' mental health during the COVID-19 pandemic.

AIM: To identify the factors affecting fear, anxiety and depressive symptoms among frontline nurses working with COVID-19 patients or are in charge of COVID-19 screening in Korea. BACKGROUND: Nurses are at a higher risk of COVID-19 infection because they are in closer, longer-duration contact with patients. These situations can negatively affect the mental health of nurses. METHODS: This study analysed data from COVID-19 module in the Korean Nurses' Health Study. Data from 906 participants were analysed. To identify the factors influencing mental health, descriptive statistics, Pearson's correlation and hierarchical multiple regression analyses were performed. RESULTS: Caring for patients who are COVID-19-positive increased levels of fear, anxiety and depressive symptoms of nurses. The hospital safety climate influenced mental well-being among nurses. CONCLUSION: Caring for patients with COVID-19 had a negative impact on fear, anxiety and depressive symptoms. However, the higher was the perceived hospital safety climate, the lower were the nurses' psychological symptoms. Further research on the mental health of nurses is warranted. IMPLICATIONS FOR NURSING AND HEALTH POLICY: Institutions should manage human resources to enable periodic rotation of nurses' work and working periods related to COVID-19. In addition, hospital managers should provide sufficient personal protective equipment, related education, and safety climate.

Data on making uniform lignin building blocks via in-situ real-time monitoring of hydroxyethyl modification.

In this work, a lab-designed apparatus was developed to collect and record the CO2 amount during the hydroxyethyl modification of lignin. We presented the CO2 volume amount and the production rate under different reaction conditions (80 - 120 °C and 2 - 6 hrs). Nuclear magnetic resonance spectroscopy was performed to analyze the chemical structure of the hydroxyethyl lignin corresponding with different amounts of CO2 that evolved during the reaction. The aliphatic hydroxyl, aromatic hydroxyl, and carboxylic acid groups were analyzed and tabulated. The acetylated hydroxyethyl lignin samples were characterized by 13C NMR to obtain the aliphatic hydroxyl (primary and secondary), phenol (ortho substituted and ortho-free), hydroxyethyl, methoxy, and aromatic hydrogen groups semi-quantitatively. Fourier-transform infrared (FTIR) spectroscopy was adopted to analyze the surface functional groups including alkyl aryl ether bond, carboxylic acid groups, and aromatic hydroxyl groups. Gel permeation chromatography combined with a multi-angle light scattering detector and differential refractive index detector were used to obtain the molar mass of lignin before and after the modification.

Molecular Orientation and Organization of Technical Lignin-Based Composite Nanofibers and Films.

Natural materials are highly anisotropic, maximizing performance of the polymeric structures while conserving mass and enhancing function. In synthetic materials, nanoscale fibers produced by electrospinning often contain molecular alignment of polymers along the fiber axis achieving some similarity to natural fibers. In this study, isolated softwood kraft lignin (SKL) was electrospun into aligned fibers utilizing a special collector. The molecular organization of lignin within the aligned nanofibers was investigated by polarized light optical microscopy. Furthermore, the functional groups that had preferred alignment along the fiber axis were identified with polarized Fourier transform infrared (FTIR) spectroscopy based on dichroism measurements. In addition, nanocrystalline cellulose (NCC) was added to the lignin solutions in order to create composite nanofibers. Both the orientation of NCC within the nanoscale fibers and the impact this component had on the degree of orientation of SKL within the aligned nanofibers were revealed by utilizing polarized FTIR. Finally, solvent cast lignin films were analyzed for their anisotropic polarizability, demonstrating birefringence with and without nanocrystalline cellulose. The work provided unique insight into both preferred orientation (fibers) and assembly (films) for technical lignin due to processing.

Impact of Thermal Oxidative Stabilization on the Performance of Lignin-Based Carbon Nanofiber Mats.

Lignin is a renewable biopolymer considered as a potential precursor for low-cost carbon materials. Thermal oxidative stabilization (TOS) is an important processing step to maintain fiber geometry during carbonization, yet the impact of  TOS on the properties of lignin-based carbon materials has not been clearly identified in the literature. Yield, change in fiber diameter/distribution, elemental composition, and mechanical properties were explored for both stabilized and carbonized lignin fibers. Vibrational spectroscopy and solid-state 13C nuclear magnetic resonance spectroscopy were used to analyze the changes in lignin molecular structure after exposure to various heating conditions during the TOS steps. Further, studies were focused on the effects of TOS conditions on the resulting carbon structure of fiber mats through Raman spectroscopy measurements and electrical conductivity analysis. Although TOS conditions influenced the properties of the oxidized lignin fiber mats, properties of the carbonized samples were invariant to the TOS procedures used in this study over most of the conditions. As a result, there was flexibility for the parameters (time and temperature) in the TOS process when conditioning softwood lignin materials for carbon fibers.

Hemorrhagic shock occurring due to a concealed hematoma after insertion of a subclavian venous catheter in a patient undergoing anticoagulation therapy: a case report.

A 74-year-old man who had been receiving warfarin for atrial fibrillation, underwent emergency thrombectomy. A central venous catheter (CVC) was inserted via the left subclavian vein, and heparin was administered to prevent preoperative and postoperative thrombotic events. After an uneventful thrombectomy, the patient was transferred to the intensive care unit (ICU). On the second postoperative day, the patient developed syncope and his blood pressure and oxygen saturation decreased. A computed tomography (CT) revealed a huge hematoma under the pectoralis major muscle. The patient was then treated with continuous renal replacement therapy and mechanical ventilation for multiorgan dysfunction syndrome, which developed due to hemorrhagic shock in the ICU. These findings suggest that when a CVC is inserted in patients requiring anticoagulant therapy, the possible risk of excessive bleeding must be carefully considered. Further, choosing a proper insertion site and performing an ultrasound-guided aspiration may be helpful in preventing these complications.

A compact system for simultaneous measurement of linear and angular displacements of nano-stages.

We report on a novel compact interferometery system for measuring parasitic motions of a precision stage. It is a combination of a Michelson interferometer with an auto-collimator, of which full physical dimension is mere 70 mm x80 mm x35 mm (WxLxH) including optical components, photo-detectors, and electronic circuits. Since the beams, which measure displacement and angle, can be directed at the same position on the moving mirror, the system is applicable for testing small nano-stages where commercial interferometers are not able to be used. And thus, errors from nano-scale deformation of the moving mirror can be minimized. We find that the residual errors of linear and angular motion measurements are 2.5 nm in peak-to-peak and 0.2'', respectively.