3D-printable, lightweight, and electrically conductive metal inks based on evaporable emulsion templates jammed with natural rheology modifiers

Conductive metal inks with 3D-printable rheological properties have gained considerable attention, owing to their potential for manufacturing 3D electronics. Typically, such inks are formulated with high volume fractions of metal particles to achieve both rheological and electrical percolation. However, this leads to a high product cost and weight, making this approach potentially undesirable for practical application. In this study, naturally occurring ingredients, i.e., bee pollen microparticles (BPMPs) and citric acids (CAs), are used to produce a jammed hexane-in-aqueous suspension-type emulsion with controllable viscoelasticity as a template for conductive metal particles. Correspondingly, it is possible to develop 3D-printable, lightweight, and conductive inks. The BPMPs and CAs, as rheology modifiers, facilitate the 3D printability of the ink. After drying, the ink forms 3D networks without macroscopic discontinuities. Hexanes co-dispersed with BPMPs and CAs in the aqueous continuous phase improve the ink rheological processability and create internal macropores within the 3D-printed structure upon evaporation under ambient conditions, decreasing the product density. A conductive copper ink based on the emulsion template shows excellent 3D printability and electrical percolation at low metal loadings (<10 vol%); moreover, the printed ink with the optimized formulation has a remarkably low density (<2 g ∙ cm^-3).

Role of electrostatic interactions in the adsorption of dye molecules by Ti3C2-MXenes

MXenes, a new class of 2D materials, have recently attracted increasing attention as promising adsorbents for environmental remediation. It has been previously demonstrated that MXenes can successfully capture selected organic dyes from aqueous media; however, to date, the adsorption performance of MXenes for a wide variety of dyes in simulated real-life aquatic environments other than clean laboratory deionized (DI) water has not been systematically investigated. In this study, we systematically investigated the adsorption performance of delaminated Ti3C2-MXenes for six different organic dyes in aquatic media at different pH levels and ionic strengths. Our results strongly suggest the importance of the electrostatic interactions between the ionizable functional groups of MXenes and dyes for removal efficiency. The electrostatic repulsions between negatively charged MXenes and certain anionic dyes reduced the removal efficiencies of MXenes for these dyes in DI water; however, the presence of divalent cations significantly improved the removal efficiencies, possibly owing to the charge screening effects and like-charge attractions mediated by cation binding to the functionalities of dyes and MXenes. These results provide a rational strategy for optimizing the conditions for efficient removal of different types of organic dyes using MXenes.

Bulk Nanoencapsulation of Phase Change Materials (PCMs) via Spontaneous Spreading of a UV-Curable Prepolymer

Phase change materials (PCMs) have received considerable attention for various latent heat storage systems for efficient thermal energy utilization. Herein, a facile and fast method for the bulk nanoencapsulation of organic PCMs is proposed, based on the thermodynamically spontaneous spreading phenomenon of three immiscible liquid phases. In this approach, a complete engulfing of PCM nanodroplets (core phase) by immiscible prepolymer droplets (coating phase), both of which are bulk-dispersed in another immiscible medium (continuous phase), is thermodynamically driven by the relation between the surface energies of the core, coating, and continuous phases. To demonstrate the proposed method, melted n-docosane (PCM, core phase) nanodroplets are completely engulfed within a couple of minutes by immiscible polyethylene glycol diacrylate (PEGDA, coating phase) in an aqueous poly(vinyl alcohol) solution (continuous phase), and the PEGDA layer quickly cross-linked upon UV irradiation to form a rigid shell protecting the PCM core. As-produced PCM nanocapsules display promising heat storage and release performances as well as high durability in repeated heating-cooling cycles in both dry and wet states. The proposed process may serve as a useful platform for bulk production of PCM nanocapsules with various core and shell compositions in a facile, fast, and scalable way.

Yield Stress Enhancement of a Ternary Colloidal Suspension via the Addition of Minute Amounts of Sodium Alginate to the Interparticle Capillary Bridges

Capillary suspensions are ternary solid-liquid-liquid systems produced via the addition of a small amount of secondary fluid to the bulk fluid that contained the dispersed solid particles. The secondary fluid could exert strong capillary forces between the particles and dramatically change the rheological properties of the suspension. So far, research has focused on capillary suspensions that consist of additive-free fluids, whereas capillary suspensions with additives, particularly those of large molecular weight that are highly relevant for industrial purposes, have been relatively less studied. In this study, we performed a systematic analysis of the properties of capillary suspensions that consist of paraffin oil (bulk phase), water (secondary phase), and α-Al₂O₃ microparticles (particle phase), in which the aqueous secondary phase contained an important eco-friendly polymeric binder, sodium alginate (SA). It was determined that the yield stress of the suspension increased significantly with the increase in the SA content in the aqueous secondary phase, which was attributed to the synergistic effect of the capillary force and hydrogen bonding force that may be related to the increase in the number of capillary bridges. The amounts of SA used to induce a significant change in the yield stress in this study were very small (<0.02% of the total sample volume). The addition of Ca²⁺ ions to the SA-containing secondary phase further increased the yield stress with possible gelation of the SA chains-in the presence of excess Ca²⁺ ions, however, the yield stress decreased because of the microscopic phase separation that occurred in the aqueous secondary phase. The microstructures of the sintered porous materials that were produced by using capillary suspensions as precursors were qualitatively well correlated to the rheological behavior of the precursor suspensions, suggesting a new method for the subtle control of the microstructures of porous materials using the addition of minute amounts of polymeric additives.

A Systematic Investigation on the Properties of Silica Nanoparticles "Multipoint"-Grafted with Poly(2-acrylamido-2-methylpropanesulfonate-co-acrylic Acid) in Extreme Salinity Brines and Brine-Oil Interfaces

Nanoparticles (NPs) may have great potential for various subsurface applications, including oil and gas recovery, reservoir imaging, and environmental remediation. One of the important challenges for these downhole applications is to achieve colloidal stability in subsurface media at high salinity and high temperature. It has been previously shown that several functional NPs "multipoint"-grafted with anionic poly(2-acrylamido-2-methyl-1-propanesulfonate-co-acrylic acid; AMPS-co-AA) exhibited remarkable colloidal stabilities in specific environments mimicking the harsh subsurface aquatic media, such as the American Petroleum Institute (API) brine. However, many important properties of such particles, other than the colloidal stabilities, must be studied in a more systematic fashion for a wide range of salt concentrations (C_s). Herein, we investigate various properties of the silica (SiO₂) NPs multipoint-grafted with poly(AMPS-co-AA), SiO₂-g-poly(AMPS-co-AA), in NaCl and CaCl₂ solutions across a range of salinities. The brush behavior of the grafted random copolymers was investigated in both salt solutions from salt-free conditions up to extreme salinities. The particles displayed brine-oil interfacial activity with increasing C_s, stabilizing oil-in-brine emulsions as Pickering emulsifiers. A high internal phase emulsion (HIPE) with an internal oil phase of up to 80 vol % could be formed in CaCl₂ solutions at high C_s, which exhibited gel-like behaviors.

Polyelectrolyte-grafted Ti3C2-MXenes stable in extreme salinity aquatic conditions for remediation of contaminated subsurface environments

Polyelectrolyte-grafted Ti₃C₂-MXenes display high colloidal stability and low adsorption to mineral substrates in extreme salinity aquatic media, while maintaining decent removal efficiency for aqueous organic dyes.

A graphene mesh as a hybrid electrode for foldable devices

A graphene mesh with arrays of micro-holes was fabricated on a polymer substrate using photolithography for use as an electrode in flexible devices. The optimal mesh structure with high optical transmittance and electrical conductivity was designed using a finite element method, in which the conductivity of the mesh was simulated as a function of structure, size, and periodicity of the hole array. The sheet resistance of the graphene mesh was lowered to that of a graphene monolayer by chemical doping and found to be 330 Ω Sq^-1 at 98.5% transparency. The figure of merit of the doped graphene mesh was calculated to be 106 at 98% transmittance, a value that has not yet been reported for any conventional transparent electrode material. Due to strong bonding between the polymer and substrate, the hybrid electrode composed of a silver nanowire (AgNW)/graphene mesh coated with an over-coating layer exhibited more stable electrical characteristics during mechanical fatigue deformation compared to a hybrid film composed of a AgNW/graphene sheet. The AgNW/graphene sheet underwent breakdown at less than 20 000 cycles in cyclic bending tests with 6.5% strain, but the AgNW/graphene mesh showed a 38% increase in resistance at 20 000 cycles and no breakdown even at 100 000 cycles. Therefore, in this study, we propose a hybrid structure composed of a AgNW/graphene mesh, which is optically and mechanically superior to AgNW/graphene sheets, and therefore suitable for application as a transparent electrode in foldable devices with long-term stability.

The prognostic value of pretreatment of systemic inflammatory responses in patients with urothelial carcinoma undergoing radical cystectomy

Background:

Systemic inflammatory response (SIR) is important in the relationship between the tumour, the host, and outcome in cancer patients. However, limited data exist regarding the prognostic significance of SIR in bladder cancer. We investigate the utility of pretreatment SIR in patients with urothelial carcinoma undergoing radical cystectomy.

Methods:

The study cohort consisted of 419 patients with a median follow-up of 37.7 months. The SIRs used for each described prognostic nomogram are consistent with previously published data: C-reactive protein, albumin, white cell count, neutrophil count, lymphocyte count, and platelet count. Primary end point was disease-specific survival (DSS) and overall survival (OS) after surgery. Cox regression models were used to determine the time to disease-specific and overall mortality. Multivariate regression coefficients of the predictors were used to develop nomograms for predicting 5-year DSS and OS probability.

Results:

Multivariate Cox regression analyses revealed that albumin, lymphocyte count, and platelet count were significantly associated with a significantly increased risk for death from bladder cancer. The nomograms including each index were developed to predict the probability of 5-year DSS and OS after radical cystectomy. The C statistics were 77.8% and 77.3%, respectively, and exceeded the 2002 AJCC (72.0% and 70.3%, respectively). In the decision curve analyses, the nomograms including SIR demonstrated higher net benefit gains compared with the models without SIR.

Conclusions:

Cellular components of SIR have better prognostic values compared with acute-phase protein in patients undergoing radical cystectomy for bladder cancer.

WITHDRAWN: Prognostic factors of biochemical recurrence after radical prostatectomy in Korean men with high-risk prostate cancer

This article has been withdrawn consistent with Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). The Publisher apologizes for any inconvenience this may cause.

Comparative trend analysis of characteristics of internationally educated nurses and U.S. educated nurses in the United States

AIM

This study compares characteristics of internationally educated nurses (IENs) and US educated nurses in the USA and examines trends and implications.

BACKGROUND

Internationally educated nurses have been an integral part of the US nurse workforce since the end of the Second World War, especially since the immigration reform in 1965. With the worsening nurse shortage, US employers are intensifying their recruitment efforts by targeting IENs.

METHODS

Secondary analysis using datasets from the National Sample Survey of Registered Nurses conducted during 1977-2000 in the USA.

RESULTS

Findings indicated that there were important differences between IENs and US educated nurses in their trends of demographical, educational and employment characteristics over time. As a group, IENs were younger but more experienced as nurses and better prepared educationally; worked more hours in both primary and secondary nursing positions; and were primarily employed in urban hospitals as staff nurses in direct care roles, with an increasing proportion working in extended care facilities.

CONCLUSIONS

Inter-group and intra-group comparisons suggest that (a) IENs were likely to have longer, more productive nursing careers, (b) because of their demographical and employment characteristics, IENs had a greater impact on relieving the US nurse shortage per capita during 1977-2000, and (c) IENs were making increasingly important contributions to the care of Americans, particularly older Americans and those cared for in inner city hospitals.

Ureteric stenting after ureteroscopy for ureteric stones: a prospective randomized study assessing symptoms and complications

OBJECTIVE

To compare patients with and with no stenting after ureteroscopy for ureteric calculi, as placing such stents is routine, although many patients complain of pain and urinary symptoms.

PATIENTS AND METHODS

In all, 45 patients with ureteric calculi amenable to ureteroscopic management were prospectively randomized into a stented (23) or an unstented (22) group. Standard ureteroscopic basketing and lithotripsy was used, through a ureteroscope (8.5 F) with or without ureteric dilatation. Symptom questionnaires were completed by the patients after treatment, and they were followed radiographically to assess stone-free rate and evidence of obstruction.

RESULTS

There was no statistically significant difference in age, stone size, operative duration or hospital stay between the groups (P > 0.05). Furthermore, there was no statistical difference in flank pain or urinary symptoms (P > 0.05), except haematuria, between the groups; haematuria was more severe and prolonged in the stented group (P = 0.001).

CONCLUSIONS

Uncomplicated ureteroscopy for removing calculi is safe with no stent after treatment, and after considering complications and side-effects we think that the routine use of ureteric stents after uncomplicated ureteroscopy for stone extraction is unnecessary.

Thrombospondin-1, vascular endothelial growth factor expression and their relationship with p53 status in prostate cancer and benign prostatic hyperplasia

OBJECTIVE

To evaluate the expression of thrombospondin-1 (TSP-1, a potent inhibitor of angiogenesis) and vascular endothelial growth factor (VEGF, an important angiogenic factor in solid tumours) in prostate cancer, and their relationship with p53 status.

PATIENTS AND METHODS

Using immunohistochemistry, the expression of VEGF, TSP-1 and p53 was assessed in 82 archival tissue specimens from 23 patients with benign prostatic hyperplasia (BPH), 22 with localized prostate cancer and 37 with metastatic prostate cancer. Seven of the last group had received androgen deprivation therapy. The relationship between the expression of VEGF, TSP-1 and p53 status was also evaluated with tumour grade and stage in patients with prostate cancer.

RESULTS

The seven patients receiving hormonal treatment were excluded from the analysis because androgen deprivation significantly increased TSP-1 and decreased VEGF expression (both P < 0.01). Immunohistochemical analysis showed significantly higher VEGF and significantly lower TSP-1 expression (both P < 0.01) in prostate cancer than in BPH tissues. There was also significantly higher VEGF and significantly lower TSP-1 expression (both P < 0.05) in tissues from metastatic than localized prostate cancer. There was no significant correlation between VEGF or TSP-1 expression and Gleason score, but a significant inverse correlation between TSP-1 and VEGF expression. There was a significant association between VEGF expression and p53 status (P < 0.05), but TSP-1 expression was not associated with p53 status.

CONCLUSIONS

Angiogenic factors, including VEGF and TSP-1, might be important in the development and progression of prostate cancer. These changes seem to be influenced by p53 status. Identifying the angiogenic factors involved in prostate cancer might lead to the development of diagnostic or therapeutic strategies based on anti-angiogenesis.

Daytime sleepiness and other sleep disorders in Parkinson's disease

BACKGROUND

PD is associated with a variety of sleep problems. The dopamine agonists (DA) pramipexole and ropinirole were recently implicated in causing "sleep attacks" and motor vehicle accidents.

METHODS

In order to determine the overall rate of subjective sleep problems in PD and to determine if any factors, including specific medications, correlate with sleep pathology, the authors surveyed consecutive patients with PD seen over a 3-month period in a Movement Disorders Clinic. The authors collected demographic and medication data, and the patients completed the Epworth Sleepiness Scale (ESS), questions assessing the presence of restless legs syndrome (RLS), a modified National Sleep Foundation sleep survey, and specific questions regarding falling asleep while driving.

RESULTS

A total of 320 patients completed the questionnaire. The authors eliminated 17, six for incomplete data and 11 for having a primary diagnosis other than PD. The mean age of the remaining 303 patients was 67.1 +/- 10.7 years, and the mean duration of PD was 9.1 +/- 5.7 years. The ESS scores averaged 11.1 +/- 5.9, and in 50.2% of patients the score was abnormally high (>10). Stepwise regression analysis found that sleepiness correlated with longer duration of PD (p < 0.001), more advanced PD (p < 0.004), male sex (p < 0.001), and the use of any DA (p < 0.003). The soporific effects of the three most common DA (pramipexole, ropinirole, and pergolide) were similar. Falling asleep while driving was reported by 63/279 (22.6%) of current drivers and correlated with higher ESS scores (p < 0.05). Other sleep disorders, including RLS, were also frequently reported.

CONCLUSION

Daytime sleepiness is common in PD and correlates with more advanced and longer duration of PD, and male sex. The DA were also independently associated with daytime sleepiness, but in this group, no single DA was more culpable than the others.

Molecular identification of Oxalobacter formigenes with the polymerase chain reaction in fresh or frozen fecal samples

OBJECTIVE

To develop a simple and rapid polymerase chain reaction (PCR) method for detecting Oxalobacter formigenes (which degrades oxalate in the gut) in fecal specimens from healthy volunteers and patients with urolithiasis, and to determine whether O. formigenes can be detected in frozen or fresh fecal samples.

MATERIALS AND METHODS

Whole bacterial DNA was isolated directly from fresh and frozen fecal samples obtained from 30 healthy volunteers free from urolithiasis and from fresh fecal samples obtained from 38 patients with urolithiasis. Genus-specific oligonucleotide sequences were designed, corresponding to homologous regions residing in the oxc gene that encodes for oxalyl-coenzyme A decarboxylase. A PCR-based assay was used on both fresh and frozen fecal samples, and the nucleotide sequences analysed to confirm oxc.

RESULTS

A PCR product of 416 bp encoding the oxc gene was detected in 23 (77%) of 30 healthy volunteers free from urolithiasis and in 14 (37%) of 38 patients with urolithiasis. In healthy volunteers, the results of PCR for the fresh and the frozen samples were identical in each subject. The nucleotide sequence analysis showed that the sequence of the amplified product was compatible with that of oxc.

CONCLUSION

O. formigenes can be identified easily and efficiently using this PCR-based detection system. The colonization rate of O. formigenes in patients with urolithiasis was significantly lower than that in healthy volunteers known to be free from urolithiasis. Furthermore, as the PCR-based assay results in the frozen fecal samples were identical to those from fresh samples in each subject, immediate processing of fecal samples may not be necessary to detect O. formigenes in the clinical setting.

Ethnic differences in the age-related distribution of serum prostate-specific antigen values: a study in a healthy Korean male population

OBJECTIVES

To further improve the use of prostate-specific antigen (PSA) as a screening test for prostate cancer in Asian countries, we sought to establish the normal distribution of serum PSA values in Korean men, because, until recently, studies conducted to establish normal serum PSA values have involved few Asian populations.

METHODS

Between May 1995 and June 1997, 5805 healthy Korean men 30 to 79 years old who visited our hospital for a routine health checkup were entered into a prospective study of early screening for prostate cancer. All men underwent detailed clinical examinations, including a digital rectal examination and serum PSA determination. All men who were more than 50 years old with abnormal digital rectal examination findings and/or an elevated serum PSA level (greater than 4.0 ng/mL) also underwent transrectal ultrasound-guided sextant biopsy. Four were found to have cancer and were excluded from the analysis.

RESULTS

The median serum PSA concentration (5th to 95th percentile range) was 0.8 ng/mL (0.2 to 1.8) for patients 30 to 39 years old (n = 1382); 0.8 ng/mL (0.2 to 2.0) for patients 40 to 49 years old (n = 1776); 0.9 ng/mL (0.2 to 2.4) for those 50 to 59 years old (n = 1775); 1.0 ng/mL (0.2 to 3.9) for men 60 to 69 years old (n = 746); and 1.3 ng/mL (0.5 to 6.3) for patients 70 to 79 years old (n = 122). The serum PSA concentration correlated with age (P <0.001), with an increase by approximately 1.2% annually, although the statistical correlation was weak (r = 0.16). Almost no change occurred in the median serum PSA value in patients 50 years old or younger; a gradual increase was observed in patients older than 50. In those 50 years old or older, the median and 95th percentile serum PSA values for Korean men were lower than those for white men.

CONCLUSIONS

Contrary to earlier observations that the serum PSA level strongly correlates with age, the influence of age on serum PSA was found to be weaker in this study. Moreover, the results also demonstrated that the distribution of the serum PSA level differs along ethnic lines. The cutoff value for serum PSA in mass screening for prostate cancer should be adjusted in nonwhite races.

The application of an anti-angiogenic gene (thrombospondin-1) in the treatment of human prostate cancer xenografts

Angiogenesis is a critical event for solid tumor growth and metastasis. Within a given microenvironment, the angiogenic response is determined in part by the balance between angiogenesis inducers and inhibitors. The aim of this study was to establish a thrombospondin-1 (TSP-1) ( an antiangiogenic gene) expression vector, and to determine the feasibility for use of TSP-1 in prostate cancer gene therapy. The results of this study showed that pCR-TSP-1, the cloned TSP-1 expression plasmid vector, expressed the TSP-1 gene efficiently in DU145, a human prostate cancer cell line. pCR -TSP-1 did not exert any significant growth inhibitory activity on the tested cell line in vitro. However, TSP-1 overexpression inhibited the growth of DU-145 xenografts in Balb/c nude mice when directly transfected with pCR-TSP-1 in combination with a liposomal agent (DOSPER). Histological analysis showed that there were extensive areas of necrosis in the TSP-1 overexpressing tumors, whereas no necrotic foci were observed in the control tumors. Furthermore, the microvessel density was lower in the TSP-1 overexpressing tumors compared to the control tumors. These results suggest that TSP-1 may be a potentially useful gene for prostate cancer gene therapy.